Articles de revues : « Li-ion batteries, Cell degradation, Anode, Cathode »

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Mao, Jing, Ke Hua Dai et Yu Chun Zhai. « Properties of LiNi_0.5Mn_1.5O₄ /Li Cell in Ionic Liquid Electrolyte Based on N-methyl-N-propylpiperidinium Bis(trifluoromethanesulfonyl)imide ». Advanced Materials Research 391-392 (décembre 2011) : 978–81. http://dx.doi.org/10.4028/www.scientific.net/amr.391-392.978.

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LiNi0.5Mn1.5O4material was synthesized by PVP-assisted gel-combustion method and examined as a cathode material for lithium-ion batteries, working together with a room temperature ionic liquid electrolyte and a lithium metal anode. The LiTFSI-Pp13TFSI ionic liquid electrolyte was obtained by dissolution of solid lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) in liquid N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl) amide (Pp13TFSI). The LiNi0.5- Mn1.5O4/LiTFSI-Pp13TFSI/Li cell was tested by galvanostatic charging/discharging and compared with standard carbonate/LiPF6electrolyte. At low current (0.05 C) density, the LiNi0.5Mn1.5O4/ LiTFSI-Pp13TFSI/Li cell exhibited stable cycling for 11 cycles, but it degraded rapidly in subsequent cycles. Preliminary tests showed that both the cathode and anode interfacial reaction contributed to the rapid degradation.

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Saneifar, Hamidreza, et Jian Liu. « Optimization of Loading Content of Li₄Ti₅O₁₂-Hard Carbon Composite Anode for the Fast Charging Li-Ion Battery ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 226. http://dx.doi.org/10.1149/ma2022-012226mtgabs.

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Fast charge of lithium-ion batteries (LIBs) needs anode and cathode materials operating at high current densities. Li4Ti5O12 (LTO) can enable fast lithium ion (Li+) transport due to its 3D crystal structure. Nonetheless, this material suffers from low specific capacity and high operating voltage. In contrast, Hard Carbon (H.C) with high specific capacity and low practical voltage is one of the promising anode materials for high-energy lithium-ion batteries. However, practical application of this material is compromised with its slow kinetic, and reduced cycling performance associated with irreversibly trapped ions in its structure [1]. In this report, effect of loading ratio of H.C and LTO composite anode on the electrochemical behavior of fast charging lithium ion battery is studied. Electrochemical characterization results show that a certain loading of H.C plays a critical role in improving the electrochemical performance of LTO-H.C composite electrodes. Specifically, superior cycling stability and specific capacity achieved for the composite electrode with 20 wt.% H.C. It is believed that composite electrodes with an optimized ratio can effectively contribute to Li-ion storage and form a robust protective solid electrolyte interface (SEI) on the electrode surface. The latter might minimize further electrolyte decomposition and continuous growth of the SEI layer upon cycling, then improves the cycling stability of the electrode. In addition, the cycling performance and rate capability of LiNiMnCoO2 (NMC) with different nickel (Ni) and manganese (Mn) contents were evaluated and compared. The results clearly suggest that higher Ni content can improve specific capacity (115 mAhg-1for NMC333 vs 149 mAhg-1 for NMC811 at 1C). However, cycling stability deteriorates with increasing the Ni content (77% capacity retention for NMC333 vs 45% for NMC811 after 300 cycles). It is postulated that electrodes with higher Ni content are susceptible to transition metal dissolution and side reactions at electrode-electrolyte interface, which could lead to performance degradation by impeding Li+ diffusion across the electrode, and irreversible consumption of Li+ [2]. Finally, the possibility of use of the optimized anode for fabricating full cell with the selected NMC cathode is investigated. References: [1] Weiss, M., Ruess, R., Kasnatscheew, J. et al. Fast Charging of Lithium‐Ion Batteries: A Review of Materials Aspects. Adv. Energy Mater 11,2101126 (2021). [2] Lin, R., Bak, SM., Shin, Y. et al. Hierarchical nickel valence gradient stabilizes high-nickel content layered cathode materials. Nat Commun 12, 2350 (2021).

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Poches, Christopher, Amir Abdul Razzaq, Haiden Studer, Xuguang Li, Krzysztof Pupek et Weibing Xing. « High Voltage Electrolytes to Stabilize Ni-Rich Lithium Battery Performance ». ECS Meeting Abstracts MA2022-02, n^o 3 (9 octobre 2022) : 188. http://dx.doi.org/10.1149/ma2022-023188mtgabs.

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State-of-the-art (SOA) lithium-ion (Li-ion) batteries are approaching their specific energy density limit (~250 Wh kg−1).1 Layered structured, nickel-rich (Ni-rich or high Ni content) lithium transition metal oxides, e.g., LiNi0.8Mn0.1Co0.1O2 (NMC811), have attracted great interests2 owning to their practically deliverable high specific capacity >200 mAh/g. Coupled with high average discharge voltages (~4V vs. Li/Li+), Ni-rich cathode-based lithium batteries possess a great potential to achieve much higher specific energies, e.g., >350 Wh/kg at cell level targeted for electric drive vehicles,3 than SOA Li-ion batteries. In addition, Ni-rich oxides are economically viable as low-cost battery cathode materials due to their low cobalt content. However, Ni-rich cathode-based Li-ion batteries exhibit a quick capacity degradation upon cycling particularly at high charge cutoff voltages (e.g., 4.5V vs. Li/Li+) and at elevated temperatures. Possible degradation mechanisms of Ni-rich based Li cells include structural changes of the material (large c-axis shrinkage at high potentials)4 and parasitic reactions that arise from the interactions between the electrolytes and highly reactive delithiated cathode surface (due to high oxidation state Ni4+ ions).5,6 Therefore, R&D efforts are needed to tackle technical challenges facing the Ni-rick based Li batteries before they become commercially viable. We will present our efforts of developing high voltage electrolytes to afford stable electrochemical performance of Ni-rich cathode-based Li cells. Figure 1 shows the electrochemical performance of NMC-811 cathode, paired Li metal anode, in conventional Li-ion battery electrolyte (Baseline electrolyte) and the high voltage electrolyte developed in this study, evaluated at C/4 rate during the formation and 1 C rate during cycling, between 2.5V and 4.5V, at room temperature. The cell with the high voltage electrolyte maintained ~80% capacity retention after 400 cycles. In contract, the cell with the baseline electrolyte experieced a large capacity fade with only ~25% capacity retention after 400 cycles. The superior cycle stability of the high votage electrolyte, Ni-rich based cell is attributed to the inharently high-voltage stable, multi-functional. Electrolyte chemical structures and their correlation with the electrochemical stability will be discussed. References Chen, W.; Lei, T.; Qian, T.; Lv, W.; He, W.; Wu, C.; Liu, X.; Liu, J.; Chen, B.; Yan, C.; Xiong, J., Advanced Energy Materials 2018, 8 (12). Jiang, M.; Danilov, D. L.; Eichel, R.-A.; Notten, P. H. L., Advanced Energy Materials 2021, 11 (48), 2103005. Gomez‐Martin, A.; Reissig, F.; Frankenstein, L.; Heidbüchel, M.; Winter, M.; Placke, T.; Schmuch, R., Advanced Energy Materials 2022, 12 (8). Cho, D.-H.; Jo, C.-H.; Cho, W.; Kim, Y.-J.; Yashiro, H.; Sun, Y.-K.; Myung, S.-T., Journal of The Electrochemical Society 2014, 161 (6), A920-A926. Chen, C. H.; Liu, J.; Amine, K., Journal of Power Sources 2001, 96 (2), 321-328. Li, J.; Downie, L. E.; Ma, L.; Qiu, W.; Dahn, J. R., Journal of The Electrochemical Society 2015, 162 (7), A1401-A1408. Acknowledgement This material is based upon work supported by the Naval Air Warfare Center Weapons Division, China Lake, CA under Contract No N6893622C0017. Any opinions, findings and conclusions or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the Naval Air Warfare Center Weapons Division, China Lake, CA. Figure 1

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Guo, Jia, Yaqi Li, Kjeld Pedersen, Leonid Gurevich et Daniel-Ioan Stroe. « The Influence and Degradation Mechanism of the Depth of Discharge on the Performance of NMC-Based Cathodes for Li-Ion Batteries ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 252. http://dx.doi.org/10.1149/ma2022-012252mtgabs.

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Many factors affect the degradation behavior of lithium-ion (Li-ion) batteries and one of these is the depth of discharge (DOD). As Li-ion batteries are used, a reasonable DOD can not only extend their service life (by reducing the degradation rate) but can also reduce the frequency of the re-charging. Therefore, to investigate and clarify the effect of the DOD on cathode performance, we performed cycle aging tests on coin cells considering three DODs. Furthermore, we proposed a degradation mechanism, to account for the influence of the DOD on the cathode performance, through ex-situ post-mortem analysis. The investigated positive electrode was from a commercial cathode NMC 532, assembled with a lithium metal anode in a 2016 type coin cell. The initial discharge capacity was about 163 mAh g–1 at a 1 C rate (1C taken as 160 mAh g–1). After every certain number of cycles, the 100% DOD (2.75 – 4.3 V) capacity was measured and recorded for all DOD ranges. Our cycle aging test experiment results (in the below Figure) show that the capacity fades faster in the higher DOD range (i.e., 3.65 – 4.3 V); the capacity of coin cells showed an initial increase due to the initial activation and a rapid decline thereafter. In contrast, the battery capacity faded slower in the two lower DOD ranges (i.e., 2.75 – 4.3 V and 3.55 – 4.3 V). The results also show that the higher DOD makes the battery more active during the initial cycles, as shown in the Figure. We refined and analyzed the XRD results of different states of the charged cathode to calculate the change in unit cell volume in initial different DOD cycles. By calculating the Li-ion diffusion coefficient through the EIS measurements, it was found that it is larger in the higher state of charge (SOC) state, which explains the higher activity of the cathode in a higher DOD range. Furthermore, we disassembled and analyzed the coin cells, after the same numbers of equivalent full cycles. Surface microcracks of the cathode were observed by SEM, and the cathode-electrolyte interphase (CEI) film was analyzed and quantified by XPS technology. Based on these results, we concluded that higher DODs enable the material to maintain a faster Li-ion diffusion rate and are always in a highly activated state. At the same time, it leads to a faster cathode decay. The post-mortem analysis showed the detailed mechanism of degradation. Looking at the results of this study, frequent charging, making the battery operation at a higher voltage, aggravates deterioration of the cathode. Acknowledgments This project has received funding from the China Scholarship Council (no. 202006370035; no. 202006220024). Furthermore, the authors would like to thank Haidi company for providing the cathode material. Figure 1

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Kim, Jin-Yeong, Jae-Yeon Kim, Yu-Jin Kim, Jaeheon Lee, Kwon-Koo Cho, Jae-Hun Kim et Jai-Won Byeon. « Influence of Mechanical Fatigue at Different States of Charge on Pouch-Type Li-Ion Batteries ». Materials 15, n^o 16 (12 août 2022) : 5557. http://dx.doi.org/10.3390/ma15165557.

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Since flexible devices are being used in various states of charge (SoCs), it is important to investigate SoCs that are durable against external mechanical deformations. In this study, the effects of a mechanical fatigue test under various initial SoCs of batteries were investigated. More specifically, ultrathin pouch-type Li-ion polymer batteries with different initial SoCs were subjected to repeated torsional stress and then galvanostatically cycled 200 times. The cycle performance of the cells after the mechanical test was compared to investigate the effect of the initial SoCs. Electrochemical impedance spectroscopy was employed to analyze the interfacial resistance changes of the anode and cathode in the cycled cells. When the initial SoC was at 70% before mechanical deformation, both electrodes well maintained their initial state during the mechanical fatigue test and the cell capacity was well retained during the cycling test. This indicates that the cells could well endure mechanical fatigue stress when both electrodes had moderate lithiation states. With initial SoCs at 0% and 100%, the batteries subjected to the mechanical test exhibited relatively drastic capacity fading. This indicates that the cells are vulnerable to mechanical fatigue stress when both electrodes have high lithiation states. Furthermore, it is noted that the stress accumulated inside the batteries caused by mechanical fatigue can act as an accelerated degradation factor during cycling.

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Abe, Yusuke, Natsuki Hori et Seiji Kumagai. « Electrochemical Impedance Spectroscopy on the Performance Degradation of LiFePO4/Graphite Lithium-Ion Battery Due to Charge-Discharge Cycling under Different C-Rates ». Energies 12, n^o 23 (27 novembre 2019) : 4507. http://dx.doi.org/10.3390/en12234507.

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Lithium-ion batteries (LIBs) using a LiFePO4 cathode and graphite anode were assembled in coin cell form and subjected to 1000 charge-discharge cycles at 1, 2, and 5 C at 25 °C. The performance degradation of the LIB cells under different C-rates was analyzed by electrochemical impedance spectroscopy (EIS) and scanning electron microscopy. The most severe degradation occurred at 2 C while degradation was mitigated at the highest C-rate of 5 C. EIS data of the equivalent circuit model provided information on the changes in the internal resistance. The charge-transfer resistance within all the cells increased after the cycle test, with the cell cycled at 2 C presenting the greatest increment in the charge-transfer resistance. Agglomerates were observed on the graphite anodes of the cells cycled at 2 and 5 C; these were more abundantly produced in the former cell. The lower degradation of the cell cycled at 5 C was attributed to the lowered capacity utilization of the anode. The larger cell voltage drop caused by the increased C-rate reduced the electrode potential variation allocated to the net electrochemical reactions, contributing to the charge-discharge specific capacity of the cells.

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Wang, Chongming, Tazdin Amietszajew, Ruth Carvajal, Yue Guo, Zahoor Ahmed, Cheng Zhang, Gregory Goodlet et Rohit Bhagat. « Cold Ageing of NMC811 Lithium-ion Batteries ». Energies 14, n^o 16 (4 août 2021) : 4724. http://dx.doi.org/10.3390/en14164724.

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In the application of electric vehicles, LiNi0.8Mn0.1Co0.1O2 (NMC811)-a Ni-rich cathode has the potential of replacing LiNiMnCoO2 (NMC111) due to its high energy density. However, NMC811 features relatively poor structural and thermal stabilities, which affect its cycle life. This study aims to address the limited data availability research gap on NMC811 low-temperature degradation. We aged commercial 21700 NMC811 cells at 0 °C under 0.5 C and 1 C current rates. After 200 cycles, post-mortem visual, scanning electron microscopy (SEM) and energy-dispersive X-ray (EDX) spectroscopy, the inspections of harvested electrodes were conducted. In just 200 cold cycles, capacity drops of 25% and 49% were observed in cells aged at 1 C and 0.5 C, respectively. The fast degradation at low temperatures is largely due to lithium plating at the anode side during the charging process. The surprisingly better performance at 1 C is related to enhanced cell self-heating. After subsequent 3-month storage, the cells that experienced 200 cycles at 0 °C and 0.5 C became faulty (voltage: ≈ 0 V), possibly due to cell lithium dendrites and micro short circuits. This work demonstrates that NMC811 suffers from poor cold ageing performance and subsequent premature end-of-life.

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Cabello, Marta, Emanuele Gucciardi, Guillermo Liendo, Leire Caizán-Juananera, Daniel Carriazo et Aitor Villaverde. « A Study to Explore the Suitability of LiNi0.8Co0.15Al0.05O2/Silicon@Graphite Cells for High-Power Lithium-Ion Batteries ». International Journal of Molecular Sciences 22, n^o 19 (25 septembre 2021) : 10331. http://dx.doi.org/10.3390/ijms221910331.

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Silicon–graphite (Si@G) anodes are receiving increasing attention because the incorporation of Si enables lithium-ion batteries to reach higher energy density. However, Si suffers from structure rupture due to huge volume changes (ca. 300%). The main challenge for silicon-based anodes is improving their long-term cyclabilities and enabling their charge at fast rates. In this work, we investigate the performance of Si@G composite anode, containing 30 wt.% Si, coupled with a LiNi0.8Co0.15Al0.05O2 (NCA) cathode in a pouch cell configuration. To the best of our knowledge, this is the first report on an NCA/Si@G pouch cell cycled at the 5C rate that delivers specific capacity values of 87 mAh g−1. Several techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS) and gas chromatography–mass spectrometry (GC–MS) are used to elucidate whether the electrodes and electrolyte suffer irreversible damage when a high C-rate cycling regime is applied, revealing that, in this case, electrode and electrolyte degradation is negligible.

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Reid, Hamish Thomas, Rhodri Jervis et Paul R. Shearing. « (Digital Presentation) Understanding the Impact of High-Nickel Cathode Microstructure on Battery Safety and Cycling Performance ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 265. http://dx.doi.org/10.1149/ma2022-012265mtgabs.

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To meet the increasing energy demands of portable devices and electric vehicles, high-nickel lithium-ion cathode materials with the general formula Li(NixMnyCoz)O2 (NMC) have been extensively researched. Currently NMC811 is used commercially for high-energy applications. The energy density of NMC also comes with concerns over cycle life and safety1,2. To improve the cycle life of NMC-based cells, single-crystal materials have recently gained attention to tackle the particle cracking issues found in polycrystalline cathodes3. However, for successful introduction to the lithium-ion battery market, inherent safety over a material’s lifetime also needs to be proven. Failure and degradation mechanisms both need to be fully understood to improve the stability of future cathode materials. Abusive testing, such as overheating, overcharge and nail penetration, has been used in conjunction with in-situ and ex-situ X-ray computed tomography (CT) 3D imaging to perform post-mortem studies and understand the relationship between thermal failure and cathode microstructure4,5. However, the interplay between safety characteristics, microstructural properties and material degradation remains unclear. This work first aims to compare the safety performance of polycrystalline and single-crystal NMC811 in 200 mAh pouch cells. Accelerating rate calorimetry (ARC) with a heat-wait-search (HWS) technique is used to heat cells and determine the onset of self-heating, onset of thermal runaway and the peak thermal runaway temperature. Laboratory-based pre- and post-mortem in-situ and ex-situ X-ray CT is also used for non-destructive imaging at multiple length scales to determine how failure propagates through the cells and the impacts on the electrodes and microstructure. Pouch cells containing polycrystalline and single-crystal NMC811 cathode and graphite anode are electrochemically cycled to induce material degradation. EIS measurements and diagnostic cycles are performed to identify prevalent degradation modes in both types of cathode materials. Finally, the same ARC and X-ray CT characterisations are performed on the aged cells to determine how degradation and changes to the material structure affect the safety performance in high-nickel cathode materials. The results of this work will improve the current understanding of capacity fade in high-nickel cathodes and the safety behaviour over the lifetime of a battery cell. This information can then be used to inform future materials development and strategies for mitigating thermal runaway in batteries. References L. Ma, M. Nie, J. Xia, and J. R. Dahn, J. Power Sources, 327, 145–150 (2016). H. J. Noh, S. Youn, C. S. Yoon, and Y. K. Sun, J. Power Sources, 233, 121–130 (2013). J. Langdon and A. Manthiram, Energy Storage Mater., 37, 143–160 (2021). D. Patel, J. B. Robinson, S. Ball, and D. J. L. Brett, (2020). D. P. Finegan et al., Phys. Chem. Chem. Phys., 18, 30912–30919 (2016).

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Carelli, Serena, et Wolfgang G. Bessler. « Prediction of Reversible Lithium Plating during Fast Charging with a Pseudo-3D Lithium-Ion Battery Model ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 344. http://dx.doi.org/10.1149/ma2022-012344mtgabs.

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Mathematical modelling and numerical simulation have become standard techniques in Li-ion battery research and development, with the purpose of studying the issues of batteries, including performance and ageing, and consequently increasing the model-based predictability life expectancy. The efficient and fast charging of Li-ion batteries remains a delicate challenge for the automotive industry, being seriously affected by the formation of lithium metal on the surface of the anode during charge. This degradation process, lithium plating, is very damaging for the mechanical and chemical integrity of the battery, which not only sees its capacity lowered but could also incur serious damage and the risk of thermal runaway. It is very difficult to detect lithium plating in situ without a direct observation of the open cell, but it is possible to deduce its presence by analyzing the cell behavior during cycles of charge/discharge in critical conditions and detecting some peculiarities which have been shown to indicate plating. The most common hints are a voltage plateau due to lithium oxidation during discharge at constant temperature and a voltage drop due to re-intercalation of metallic lithium during heating of the cell. On the other hand, the absence of any evidence of changes in voltage should not be considered as proof of evidence of a complete absence of lithium plating. Following our development of a comprehensive modelling and simulation framework for a commercial 0.35 Ah high-power lithium-ion pouch cell with LCO/NCA blend cathode1, here we present an extended pseudo-3D (P3D) model2 in which a lithium plating reaction has been integrated and parameterized. The model is able to describe and predict both the equilibrium potentials and the non-equilibrium kinetics of the competing intercalation and plating reactions for arbitrary macroscopic operating conditions (C-rate, temperature, SOC). A relatively simple and common way to assess plating risk with P2D models is to compare the simulated local anode potential Δφ an with the thermodynamic plating condition of Δφ Li eq = 0 V, but this approach shows several pitfalls that have not been well discussed in literature, including the effects of temperature, pressure and ion concentration on the thermodynamics and kinetics of the plating reaction (see Figure 1a). An extra reaction, simulating explicitly the re-intercalation of the plated lithium, has also been included and can be freely switched on to simulate a case in which the cell is likely not showing macroscopic plating hints. The models allow the creation of operation maps (see Figure 1b) and an accurate spatiotemporal analysis of the competing reactions and lithium plating formation at the electrode-pair scale (1D, mesoscale) and intraparticle scale (1D, microscale) over a wide range of conditions. The governing equations for this model are implemented in an in-house multiphysics software. The electrochemistry model is based on the use of the open-source chemical kinetics code CANTERA, enabling the thermodynamically consistent description of the main and side reactions. To validate our extended model, we simulated and successfully reproduced our own experimental data on our modelling reference cell (0.35 Ah high-power lithium-ion pouch cell with LCO/NCA blend cathode - where no macroscopic plating hints are present) and the published experimental data from Ecker et al.3 (40 Ah high-power lithium-ion pouch cell with NMC cathode - where the plating hints are instead clearly visible). References S. Carelli, M. Quarti, M. C. Yagci and W. G. Bessler, J. Electrochem. Soc., 166(13), A2990-A3003 (2019). S. Carelli and W. G. Bessler, J. Electrochem. Soc., 167(100515) (2020). M. Ecker, Lithium Plating in Lithium-Ion batteries: An experimental and simulation approach, RWTH Aachen University (2016). Figure 1

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ShakeriHosseinabad, Fatemeh, Alireza Sadeghi Alavijeh, Shantanu Shukla, Mahmood Khalghollah, Simon Fan et Edward P. L. Roberts. « Analysis of Performance Degradation and Durability of the Air Cathode in an Alkaline Fuel Cell ». ECS Meeting Abstracts MA2022-01, n^o 3 (7 juillet 2022) : 503. http://dx.doi.org/10.1149/ma2022-013503mtgabs.

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Degradation of the air cathodes is one of the key issues affecting the lifetime and durability of alkaline fuel cells and metal-air batteries. To prevent the ingress of electrolyte in the air cathode, modifying the hydrophobicity and thickness of the AL has been reported [1,2]. It was reported that increased hydrophobicity/thickness of the AL resulted in a decrease in the air cathode performance [1,2]. In this work, experimental in-situ and post-test analyses of the air cathode were applied to investigate the mechanism of performance degradation. In-situ methods including performance / lifetime analysis using a half-cell setup [3, 4], polarization studies, and electrochemical impedance spectroscopy (EIS) were used to investigate the electrochemical characteristics of the electrodes during operation. Post-mortem analysis methods included X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), X-ray computed tomography (X-ray CT), and Raman spectroscopy. The properties of pristine, conditioned, and failed air cathodes were characterized by these methods. Conditioning of air cathodes was performed by operating in half-cell utilizing 6 M KOH solution for 24 hours at 200 mA cm 2. The composition of the air cathode, operating conditions, and procedure for determining the performance and lifetime of the air cathode have been discussed in our previous work [3]. Cross-sectional SEM-EDX analysis was conducted on the air cathode to determine the amount of flooding/penetration of the electrolyte inside the active layers for electrodes prepared with 15, 25, and 40 wt% PTFE in the AL. Air cathodes were operated in the half-cell battery at 200 mA cm -2. EDX maps of the air cathodes showed that increasing the PTFE content leads to increased hydrophobicity and decreased depth of KOH penetration inside the AL after 5 hours of operation. However, air cathodes with higher PTFE content of 40 wt% exhibited a lifetime of only 48 hours, compared to > 150 hours for those containing 15 wt% and 25 wt% (conducted in a limited test duration). This could be due to decreased electrolyte content in the AL or blocking of pore space and active reaction sites [5], leading to higher local current densities and more rapid degradation. Cross-sectional EDX analysis indicated that electrolyte penetration/flooding inside the macrostructure of the backing layer (BL) was not observed in any of the electrodes. XPS was performed to reveal further information of the chemical states of the conditioned and failed cathodes [6]. XPS analysis indicated changes in the surface functional groups, in particular increasing hydroxyl groups in the failed cathodes, which may be indicative of reduced hydrophobicity of the carbon support. XPS analysis also indicated other changes in the chemical states of the catalyst, oxygen, fluorine and carbon after conditioning and failure of the air cathode. In-situ galvanostatic EIS was conducted during long-duration and accelerated stress tests to determine ohmic resistance, charge transfer resistance, and mass transfer limitation. The EIS data indicates that mass transfer resistance increased significantly after failure of the air cathode, confirming that oxygen transport to the catalyst was the cause of the poor performance of failed cathodes. Raman spectra and mapping was carried out to obtain additional information about changes in the AL after degradation. X-ray CT were conducted on air cathodes to determine the changes of pore structure, distribution of catalyst, PTFE and potassium. References: [1] Li, Y. S., Zhao, T. S., & Liang, Z. X. (2009). Effect of polymer binders in anode catalyst layer on performance of alkaline direct ethanol fuel cells. Journal of Power Sources, 190(2), 223-229. [2] Jo, J. H., Moon, S. K., & Yi, S. C. (2000). Simulation of influences of layer thicknesses in an alkaline fuel cell. Journal of applied electrochemistry, 30(9), 1023-1031. [3] ShakeriHosseinabad, F., SadeghiAlavijeh, A. , Khalghollah, M., Shukla, S., Fan, S., & Roberts, E. P. (2021, October). Mechanisms of Degradation of the Air Cathode in an Alkaline Fuel Cell. In ECS Meeting Abstracts (No. 40, p. 1217). IOP Publishing. [4] Endrődi, B., Samu, A., Kecsenovity, E., Halmágyi, T., Sebők, D., & Janáky, C. (2021). Operando cathode activation with alkali metal cations for high current density operation of water-fed zero-gap carbon dioxide electrolysers. Nature Energy, 6(4), 439-448. [5] Holdcroft, S. (2014). Fuel cell catalyst layers: a polymer science perspective. Chemistry of materials, 26(1), 381-393. [6] Guo, J., Kang, L., Lu, X., Zhao, S., Li, J., Shearing, P. R., ... & Parkin, I. P. (2021). Self-activated cathode substrates in rechargeable zinc–air batteries. Energy Storage Materials, 35, 530-537.

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Liu, Ping. « (Invited) Pushing Lithium-Metal Batteries to the Limit : Fast Charging, Low Temperature, and Safety ». ECS Meeting Abstracts MA2022-02, n^o 5 (9 octobre 2022) : 561. http://dx.doi.org/10.1149/ma2022-025561mtgabs.

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The performance of lithium metal batteries has advanced significantly, thanks to continuous improvement in the lithium metal anode. Many chemical and mechanical control strategies have been employed to combat its degradation mechanisms such as parasitic reactions, dendritic growth, and formation of isolated lithium. Electrolytes with high salt concentrations, including those with non-solvating diluents (known as localized high concentration electrolytes, or LHCE), electrolyte additives, artificial coatings, 3D plating hosts Li, and applying pressures in the 100s-1000s of kPa range have all been found to be effect in yielding dense, high efficiency Li metal deposits. Despite these advancements, reported lithium metal batteries tend to be charged at low rates, operated under ambient conditions, and lacking sufficient information on their safety characteristics. In this talk, we will review our recent progress in pushing the lithium metal batteries to extreme operating conditions in term of temperature, charging rates, and shorting behavior. To enable fast charging, we have focused on developing a nucleation agent on the surface of current collector that can induce the formation of large, uniform nucleation sites. These nanoscopic sites enable dense lithium plating at 5 mA c-2 of current density, when a planar Cu electrode will fail catastrophically. This uniform nucleation method leads to a 45 um thick Li deposit that is nearly porosity free. A lithium metal cell with a metal oxide cathode is capable of 1C charging for extended cycles. To enable low temperature operation, we have focused on the development of new electrolyte compositions that uses weakly solvating solvents. These electrolytes, represented by monodentate ethers and LHCEs made of ethers, promote the formation of contact ion pairs after solvation over solvent separated ion pairs. These electrolytes have enabled the formation of dense lithium metal deposits at as low as -60oC, while strongly solvating electrolytes will promote the formation of dendrites and cell shorting. Finally, any practical implementation of lithium metal batteries operating under these extreme conditions have to feature safety designs that mitigate the impact of internal shorting. In this regard, we have focused on separator designs that can detect and intercept lithium dendrites.

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Boulanger, Thomas, Ahmed Eldesoky, Connor P. Aiken, Eric R. Logan, Saad Azam, Jeff R. Dahn et Michael Metzger. « Investigation of Redox Shuttle Generation in LiFePO₄/Graphite and NMC811/Graphite Cells for Different Additives and Conducting Salts ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 200. http://dx.doi.org/10.1149/ma2022-012200mtgabs.

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LFP/Graphite cells are attractive because they are cheaper[1], safer[2,3] and can achieve acceptable energy density for most applications. A limitation of the LFP/Graphite cells is their inferior capacity retention at elevated temperature when compared to NMC/Graphite cells especially in the absence of electrolyte additives, e.g., VC (Vinylene carbonate), as observed by our group in a recent study[4].The time it takes for a LFP graphite cell to completely self-discharge at 60oC is around 500 hours with a base electrolyte of 1.5 M LiPF6 (Lithium hexafluorophosphate) dissolved in 7:3 DMC:EC (Dimethyl carbonate/ethylene carbonate)[4]. It also has been observed that during cycling some Fe will accumulate on the anode which can be explained by dissolution of Fe from the cathode and subsequent deposition on the anode. With the same electrolyte as mentioned before we can observe up to 0.2 μg/cm2 on the anode after 60 cycles at 40⁰C[4]. The goal of this research is to understand what is happening inside the LFP/Graphite cells by analyzing the electrolyte from cells that only did a formation procedure. We were able to extract different electrolytes from LFP/Graphite and NMC811/Graphite pouch cells. We expected the electrolyte to stay clear as it was just after preparation, but we observed yellow and red colors depending on the temperature of formation. If the electrolyte contained 2%wt VC, no color change was observed. The different electrolytes used for the experiments were LiPF6, LiFSI (Lithium bis(fluorosulfonyl)imide) and LiPF6+2%wt VC all dissolved in 7:3 DMC:EC. The extracted electrolytes were put inside coin cells with an Al foil working-electrode (WE) and a Li foil counter-electrode (CE) and cyclic voltammetry (CV) was done on them from 2.6 V - 3.75 V vs. Li+/Li. The CV traces show the presence of current in the μA range for electrolyte without VC extracted from LFP cells, indicating the presence of a reversible shuttle species. The electrolyte with no VC expected from LFP cells showed more current than the corresponding electrolyte extracted from NMC811 cells. There was almost no current in the coin cells using electrolytes with 2% VC extracted from the LFP and NMC811 cells. We also made systematic experiments at different formation temperature and different wait times before extraction. Figure 1: Observation of the different electrolytes extracted from LFP/Graphite cells with a) 1.5 M LiPF6 EC:DMC 3:7 and b) 1.5 M LiPF6 +2%wt VC EC:DMC 3:7 that did formation at 25, 40 ,55 and 70⁰C (left to right). References W. Li, Y. Cho, W. Yao, Y. Li, A. Cronk, R. Shimizu, M. A. Schroeder, Y. Fu, F. Zou, V. Battaglia, A. Manthiram, M. Zhang, and Y. S. Meng. “Enabling high areal capacity for Co-free high voltage spinel materials in next-generation Li-ion batteries”, Journal of Power Sources, 473 (2020). D. Jian, T. Xuan, D. Haifeng, Y. Ying, W. Wangyan, W. Xuezhe, and H. Yunhui. “Building Safe Lithium-Ion Batteries for Electric Vehicles: A Review”, Electrochem. Energ. Rev. 3, 1–42 (2020). W. Li, H. Wang, Y. Zhang, and M. Ouyang. “Flammability characteristics of the battery vent gas: A case of NCA and LFP lithium-ion batteries during external heating abuse”, Journal of Energy Storage, 24 (2019) E. R. Logan, H. Hebecker, A. Eldesoky, A. Luscombe, M. B. Johnson, and J. R. Dahn. “Performance and Degradation of LiFePO4/Graphite Cells: The Impact of Water Contamination and an Evaluation of Common Electrolyte Additives”, Journal of The Electrochemical Society, 167, 13 (2020) Figure 1

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Han, Sang-Don, Bertrand J. Tremolet de Villers, Lydia Meyer et Jason Morgan Porter. « In Situ Multi-Modal Approach for Electrode-Electrolyte Interfacial Chemistryand Electrode and Electrolyte Aging Behavior Studies ». ECS Meeting Abstracts MA2022-02, n^o 3 (9 octobre 2022) : 354. http://dx.doi.org/10.1149/ma2022-023354mtgabs.

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Increasing demands for cost-effective electric vehicles and electrochemical energy storage systems require advanced secondary batteries with higher energy density, longer lifetime, and enhanced safety. Increase of the battery operating voltage is one realistic strategy to extend the energy density, but it is accompanied by irreversible structural changes to the electrodes and parasitic reactions within an electrode-electrolyte interphase resulting in capacity fading and subsequent battery failure. Therefore, a fundamental understanding of underlying electrochemical mechanisms in the electrodes during battery cycling is critical for the development of next-generation secondary batteries. Based on our previous studies utilizing in situ surface-enhanced Raman spectroscopy to monitor the evolution of the Si-electrolyte interphase1 and in situ ATR-FTIR to investigate the voltage dependent electrolyte solution structure changes at the interface, transition metal redox chemistry, and cathode/electrolyte interfacial layer evolution,2 recently we updated the in situATR-FTIR with a newly designed ‘full-cell’ that enables us to analyze the interfacial reactions and interactions on the surfaces of both electrodes that directly influence battery performance, lifetime, and safety. Specifically, we focus on transition metal complex formation and its effect on solid-electrolyte interphase (SEI) formation and evolution on the anode due to transition metal dissolution and crosstalk of Mn-rich cathodes at high voltages (≥4.4 V). In addition, using our multi-modal characterization—a combination of in situ gas chromatography with flame ionization detection (GC-FID) and in situ ATR-FTIR—(electro)chemical degradation of the electrolyte is correlated with gas evolution in the battery. For example, GC-FID measures increasing amounts of ethylene gas until the end the first charging cycle of a LiNiO2//Graphite cell with Gen2 electrolyte (LiPF6 in ethylene carbonate (EC):ethyl methyl carbonate (EMC), 3:7 wt.%). Concurrently, in situ ATR-FTIR shows decreasing concentration of EC solvent, as calculated from the FTIR intensity of EC vibrational absorption. Ethylene is a known by-product of ethylene carbonate electrochemical reduction and is produced during SEI formation.3 Quantifying multiphase reactions occurring during battery operation is critical to understanding and mitigating battery degradation pathways, and developing next-generation battery materials systems. References: Ha, B. J. Tremolet de Villers, Z. Li, Y. Xu, P. Stradins, A. Zakutayev, A. Burrell and S.-D. Han, “Probing the Evolution of Surface Chemistry at the Silicon-Electrolyte Interphase via In-situ Surface-Enhanced Raman Spectroscopy,” J. Phys. Chem. Lett. 2020, 11, 286-291. J. Tremolet de Villers, J. Yang, S.-M. Bak and S.-D. Han, “In Situ ATR-FTIR Study of Cathode-Electrolyte Interphase: Electrolyte Solution Structure, Transition Metal Redox, and Surface Layer Evolution,” Batter. Supercaps 2021, 4, 778-784. Han, C. Liao, F. Dogan, S. E. Trask, S. H. Lapidus, J. T. Vaughey and B. Key, “Using Mixed Salt Electrolytes to Stabilize Silicon Anodes for Lithium-Ion Batteries via in Situ Formation of Li–M–Si Ternaries (M = Mg, Zn, Al, Ca),” ACS Appl. Mater. Interfaces 2019, 11, 29780-29790.

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Micari, Salvatore, Salvatore Foti, Antonio Testa, Salvatore De Caro, Francesco Sergi, Laura Andaloro, Davide Aloisio, Salvatore Gianluca Leonardi et Giuseppe Napoli. « Effect of WLTP CLASS 3B Driving Cycle on Lithium-Ion Battery for Electric Vehicles ». Energies 15, n^o 18 (13 septembre 2022) : 6703. http://dx.doi.org/10.3390/en15186703.

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Capacity loss over time is a critical issue for lithium-ion batteries powering battery electric vehicles (BEVs) because it affects vehicle range and performance. Driving cycles have a major impact on the ageing of these devices because they are subjected to high stresses in certain uses that cause degradation phenomena directly related to vehicle use. Calendar capacity also impacts the battery pack for most of its lifetime with a capacity degradation. The manuscript describes experimental tests on a lithium-ion battery for electric vehicles with up to 10% capacity loss in the WLTP CLASS 3B driving cycle. The lithium-ion battery considered consists of an LMO-NMC cathode and a graphite anode with a capacity of 63 Ah for automotive applications. An internal impedance variation was observed compared to the typical full charge/discharge profile. Incremental capacitance (IC) and differential voltage (DV) analysis were performed in different states of cell health. A lifetime model is described to compute the total capacity loss for cycling and calendar ageing exploiting real data under some different scenarios of vehicle usage.

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Mastrogiorgio, Massimiliano, Basab Ranjan Das Goswami, Marco Ragone, Farzad Mashayek et Vitaliy Yurkiv. « Advanced Data-Driven Modeling Framework for Predicting Thermal Failures in Li-Ion Pouch Batteries ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 434. http://dx.doi.org/10.1149/ma2022-012434mtgabs.

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With the rapid development and widespread applications of lithium-ion batteries (LIBs), there is an ongoing need to extend and apply theoretical models that assist LIB’s safety aspects. It is particularly important for electric vehicles (EVs) due to numerous recent fire accidents. Thermal runaway (TRA) is one of the principal causes of LIB’s failures in EVs occurring due to thermal or mechanical breakdown, internal/external short-circuiting, or electrochemical abuse. During EV’s operation, it is impossible to directly monitor the TRA; however, the change in thermo-electrical characteristics (pattern) during TRA-like events could signal the presence of a failure, allowing for the prediction of LIB malfunction. Thus, in this work, we employ machine learning-based techniques informed by multi-physics models to predict and prevent the TRA in large pouch LIBs as presently used in various EVs. The multi-physics model is implemented in commercial software Comsol, with the P2D electrochemical model1 and a 3D thermal model. The degradation sub-model2 includes oxygen release in the positive electrode to simulate the overcharge phenomenon during EV’s charging. In addition, the oxygen released in the positive electrode may exothermically react with the electrolyte as well as create significant stress in the electrode, which may lead to the mechanical deformation of the electrode and a subsequent TRA. An LG Chem lithium-ion pouch cell consisting of Li(Ni0.6Mn0.2Co0.2)O2 – NMC622 – cathode and graphite anode are studied to address this severe TRA problem. As a result of the time-varying nature of the variables that affect TRA, we propose three potential machine learning algorithms. These are Support Vector Machine, Deep Neural Network, and Recurrent Neural Network, tailored and implemented for estimating the TRA likelihood, using thermal images acquired from the multi-physics modeling of LIB pouch cells. Hyperparameters optimization has been performed to identify a set of variables for the best performing ML method. The proposed combined multi-physics and machine learning modeling methodology provide interesting insight and predictive capabilities for TRA prediction. References J. Newman and W. Tiedemann, J. Electrochem. Soc., 140, 1–5 (1993). X. Feng, X. He, M. Ouyang, L. Wang, L. Lu, D. Ren and S. Santhanagopalan, J. Electrochem. Soc., 165, A3748–A3765 (2018).

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Thornton, Daisy Barbara, Bethan Davies, Søren Scott, Zonghao Shen, Ainara Aguadero, Mary Ryan et Ifan Erfyl Lester Stephens. « Probing Crossover Degradation Effects in Nickel-Rich LiNi_xMn_yCo_zO₂ Lithium-Ion Battery Cathodes with Ultrasensitive on-Chip Electrochemistry Mass Spectrometry ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 350. http://dx.doi.org/10.1149/ma2022-012350mtgabs.

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Performance improvements in electric vehicle batteries are needed in order to reduce their cost and encourage greater use.1 This improvement is dependent on the properties (e.g. specific capacity and stability) of the cathode active material in the electric vehicle’s lithium ion battery.1 Lithium Nickel Cobalt Manganese Oxide (NMC) is a layered transition metal oxide that shows great promise as an electrode in lithium ion batteries for electric vehicles, with a high theoretical specific capacity and good stability in the layered structure.2 As the nickel content of the cathode material increases, so does the discharge capacity, however this increase comes at the cost of significantly decreased capacity retention.1 The mechanisms that contribute to this degradation are complex and interlinking and many of them are accompanied by some form of gas evolution. For example, the solid electrolyte interphase (SEI) formation at the cathode evolves CO2, which is able to crossover and contribute to solid electrolyte interphase formation at the anode.1 Similarly, upon electrochemical cycling a reactive form of oxygen can be evolved from the NMC lattice, resulting in a cascade of parasitic reactions within a lithium-ion battery.2 Herein, we probe these gas evolving degradation mechanisms through the development and use of a novel type of electrochemistry mass spectrometry (EC-MS) with unprecedented time resolution and sensitivity.3,4 The new technique, known as on-chip EC-MS, employs a microfabricated membrane chip to precisely control the transfer of volatile species from an electrochemical cell to a mass spectrometer. Its design also allows instantaneous gas exchange, particularly useful to simulate cross talk phenomena. This work demonstrates the first application of this technique to the study of lithium-ion batteries; this study uses a new cell design to facilitate operando measurements of gas evolution in lithium-ion batteries to provide important insight into these complex mechanisms.4 More specifically, the effect of transition metal dissolution on the stability of the anodic SEI is investigated by monitoring ethylene evolution. Isotopic labelling studies are also performed to probe the evolution and consumption of CO2 that is evolved from the cathode. Complementary and correlative ex situ surface sensitive analysis (such as x-ray photoelectron spectroscopy and secondary ion mass spectrometry) are carried out in order to develop a holistic understanding of the complex reactivity and chemistry evolution of lithium-ion batteries during operation. References (1) Jung, R.; Metzger, M.; Maglia, F.; Stinner, C.; Gasteiger, H. A. Chemical versus Electrochemical Electrolyte Oxidation on NMC111, NMC622, NMC811, LNMO, and Conductive Carbon. J. Phys. Chem. Lett. 2017, 8 (19), 4820–4825. (2) Wandt, J.; Freiberg, A. T. S.; Ogrodnik, A.; Gasteiger, H. A. Singlet Oxygen Evolution from Layered Transition Metal Oxide Cathode Materials and Its Implications for Lithium-Ion Batteries. Mater. Today 2018, 21 (8), 825-833. (3) Trimarco, D. B.; Scott, S. B.; Thilsted, A. H.; Pan, J. Y.; Pedersen, T.; Hansen, O.; Chorkendorff, I.; Vesborg, P. C. K; Stephens, I. E. L. Enabling Real-Time Detection of Electrochemical Desorption Phenomena with Sub-Monolayer Sensitivity. Electrochim. Acta 2018, 268, 520–530. (4) Thornton D. B.; Cavalca F.; Aguadero A.; Ryan M.; Stephens I.E.; UK Patent filed 17 September 2021

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Daubinger, Philip, Matthias Schelter, Ronny Petersohn, Felix Nagler, Sarah Hartmann, Matthias Herrmann et Guinevere A. Giffin. « Mechanical Effects Occurring inside Large Format 94 Ah Prismatic Lithium-Ion Cells at Different Bracing during Aging ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 436. http://dx.doi.org/10.1149/ma2022-012436mtgabs.

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One of the biggest obstacles to the widespread adoption of fully electrified vehicles is the limited volumetric/gravimetric energy density of lithium-ion batteries to achieve driving ranges comparable to vehicles with internal combustion engines. Electrode thicknesses are being increased to enhance the energy density of the battery cells. Furthermore, the space within the confinements of the cell housing is utilized as much as possible. Today’s state-of-the-art (SoA) electrode materials exhibit volume and Young’s modulus change during formation and cycling, e.g. a volume change up to ~10% for graphite [1] and a threefold increase of the Young’s modulus of the graphite active particles [2]. This leads to a pressure build up within the cells due to reversible and irreversible volume changes, especially of the anode materials, during cycling. The optimized packing for SoA electrodes and the volume changes of the electrodes result in increased electrochemical/mechanical interactions that leads to stress inside the cells. In this work, the interactions between mechanical bracing and aging are studied for large format prismatic 94 Ah lithium-ion battery cells [3]. The impact of external bracing is shown for lithium-ion cells cycled up to over 7000 cycles with 100% depth of discharge (Figure 1 (a)), where the braced cells show an enhanced performance in the region of 80% state of health (SOH). The braced cells reach this threshold around 900 cycles later compared to the unbraced cells. Furthermore, the unbraced cells have a thickness change of around 17.5% after more than 7000 cycles (Figure 1 (b)). After cycling, the cells are examined with post-mortem analysis, showing significantly increased aging phenomena (e.g. lithium plating) in the unbraced cell compared to the braced cell. Inductively coupled plasma optical emission spectrometry (ICP-OES) analyses confirm these assumptions (Figure 1 (c) + (d)). In contrary to the enhanced lithium plating on the anode of the unbraced cell, X-Ray diffraction (XRD) show that bracing leads to an increased structural cathode degradation compared to the unbraced cells. Those ex-situ post-mortem experiments were also confirmed by electrochemical tests in laboratory cells, showing only small capacity fading of the aged anodes of the braced cell compared to unaged reference anode cells. Nevertheless the main factor for capacity loss inside the prismatic 94 Ah cells is the loss of lithium inventory. External pressure on cells is beneficial to guarantee sufficient contact of the components within an electrode stack and hence decreased aging phenomena mainly on the anode. The downside of the increased pressure on the cells are the significantly increased morphological and structural degradation of the cathode, which, however, plays a minor role in the overall cell degradation. The external bracing results in a more ‘homogeneous’ aging over the entire cell with only little locally different degradation characteristics. References: [1] Daubinger, P., Ebert, F., Hartmann, S., & Giffin, G. A. (2021). Impact of electrochemical and mechanical interactions on lithium-ion battery performance investigated by operando dilatometry. Journal of Power Sources, 488, 229457. [2] Qi, Y., Guo, H., Hector Jr, L. G., & Timmons, A. (2010). Threefold increase in the Young’s modulus of graphite negative electrode during lithium intercalation. Journal of The Electrochemical Society, 157(5), A558. [3] Daubinger, P., Schelter, M., Petersohn, R., Nagler, F., Hartmann, S., Herrmann, M. & Giffin, G. A. (2021). Impact of Bracing on Large Format Prismatic Lithium-Ion Battery Cells During Aging. Accepted manuscript at Advanced Energy Materials. Figure 1

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Pfleging, Wilhelm, Peter Smyrek, Katja Froehlich, Jianlin Li et Zheng Yijing. « Evaluation of Electrochemical Performance Tuning By Laser Structuring of Electrodes and Its Impact on Cell Degradation Mechanisms ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 413. http://dx.doi.org/10.1149/ma2022-012413mtgabs.

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Tuning of electrochemical properties of lithium-ion batteries by using ultrafast laser structuring of electrodes is a rather new technical approach. At Karlsruhe Institute of Technology (KIT) this technology was developed and established for the first time. However, quite recently, other research groups and institutions worldwide also recognized the high potential of this technology for lithium-ion battery production. Lately, a roll-to-roll laser processing infrastructure for structuring large footprint electrode materials for high capacity pouch cells and cylindrical cells was installed at KIT in order to push this technology to demonstrator level, namely technology readiness level 6. The high rate capability of the produced high energy battery cells were significantly improved and twice lifetime of cells could be achieved in comparison to cells with unstructured electrodes. In frame of research, cooperative, and industrial projects the impact of laser structuring for small and large footprint electrodes was studied with regard to lithium distribution caused electrochemical cycling. Hereby, different types of LiNixMnyCo1-x-yO2 (NMC) as a cathode material and graphite as well as silicon-graphite as an anode material with areal capacities up to 4 mAh/cm2 were investigated. Quantitative lithium distribution along entire electrodes were measured by laser-induced breakdown spectroscopy (LIBS). From the 3D elemental mapping starting points for electrochemical degradation could be identified. In cathode materials the local increase of lithium indicated the formation of electrical short cuts which were most related to electrode material inhomogeneity, e.g., by a macroscopic change in porosity or macroscopic film defects. The compressive stress applied to electrodes and separator during cycling has also a significant influence on lithium distribution and subsequent cell degradation. The appropriate type of laser generated patterns such as holes, lines or grids strongly depends on the application scenario as well as type of materials. For silicon-graphite anodes the huge volume expansion during lithium silicide needs to be considered and more rectangular and broader structure features become relevant. Laser structuring of electrodes showed in all cases, for small and large footprint cathodes and anodes, a rather homogenized lithium distribution along the surface and electrode thickness. For full cells elemental mapping of electrodes facing each other was performed indicating the mutual influence on lithium distribution. It can be concluded that the laser-based 3D electrode concept is beneficial regarding a reduced cell degradation. In addition, it could be proven by LIBS that for the 3D battery concept new lithium diffusion pathways were generated which becomes activated at elevated C-rates. Those new lithium diffusion pathways counteract the increase of diffusion overpotential leading to a higher capacities also for high power operation.

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Shim, Jinha, Woowon Chung et Jin Ho Bang. « Mn Interdiffusion Mobility Controlled By Simple Drying Process for Cobalt Free Core-Shell Ni Rich Cathode Material in Lithium Ion Batteries ». ECS Meeting Abstracts MA2022-02, n^o 7 (9 octobre 2022) : 2413. http://dx.doi.org/10.1149/ma2022-0272413mtgabs.

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Lithium-ion batteries (LIBs) become an essential part of many portable devices and even electric vehicles than ever before. Among the various cathode materials, Ni rich layered cathode material has big attention because it has higher specific capacity and energy density. However, at a delithiated state, unstable Ni4+ leads to oxygen release and structural degradation and as a result, irreversible phase transition from R3m to electrochemical inactive Fm3m is observed. So, various strategy is applying to overcome this limitation like three-component system (NCM) or surface coating. However, NCM still cannot solve that problem perfectly and surface coating makes a problem like reducing specific capacity caused by insulating coating material (Al2O3, MnO2...etc) And also, this day, Co free structure of Ni rich cathode material has received more great attention as an alternative to NCM because of its hazardous toxicity and increasing price of Co. At this perspective, many studies have demonstrated Core-Shell or FCG (Full Concentration Gradient) structure can make better structural stability without Co metal than surface coating, which has insulated coating materials. In addition, core shell structure is easier to control the composition than FCG structure. However, in Core-Shell structure, interdiffusion of shell metal to core deteriorate the stability of Core-Shell material, so it needs very delicate heat treatment. And generally, to prevent interdiffusion from traditional core-shell structure, lower synthesis temperature or high valence metal dopant would be needed and that leads lower initial specific capacity or additional doped metal. So, we prevent the Mn interdiffusion by changing valence state of Mn in precursor through simple convection drying process not vacuum drying without decreasing synthesis temperature and additional dopant. Atomic interdiffusion in layered metal oxide structures follows the atomic migration through octahedral and tetrahedral sites. In case of various stated Mn, higher valence state Mn has higher energy barrier to migrate between each Oh and Td sites. Based on this theory, surface Mn rich shell can be oxidized easily under convection oven drying and highly oxidized Mn will be remained better than lower state Mn during high temperature calcination. These more remained Mn in shell can protect the particle surface from electrolyte attack and also higher valence state Mn makes slightly more Ni2+ due to thermodynamic stability and charge balance of Mn on the surface. And that Ni2+ in Li slab (Cation mixing) acts as a pillar to suppress irreversible phase transition of Ni rich materials. Through this surface passivation, phase transition (layered to rock salt ) propagation surface to bulk can be blocked. Furthermore, mechanical pulverization of secondary particle is also prevented because of less permeating electrolyte into bulk structure. Therefore, Li ion diffusion will not be sluggish after cycling as observed by GITT. In addition, more clear Ni rich core assure high specific capacity and faster electrochemical reaction kinetic without severe capacity fading. And also, in Full cell test (using graphite as anode), convection oven dried sample has better structure stability and that means our strategy for core-shell LiNi0.97Mn0.03O2 sample can be good candidate to alternate conventional cathode active material for Lithium ion battery practically. As prepared materials, atomic distribution was observed by EDS and XPS analysis. This study suggests useless of vacuum drying and more cost effective way to prepare Co free Core Shell LiNi0.97Mn0.03O2 cathode material for Lithium Ion Batteries.

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Pahlevaninezhad, Maedeh, Ashutosh Kumar Singh, Thomas Storwick, Elizabeth Esther Miller, Anne Yang, Majid Pahlevani, Michael Pope et Edward P. L. Roberts. « An Advanced Composite Membrane for the All-Vanadium Redox Flow Battery ». ECS Meeting Abstracts MA2022-01, n^o 3 (7 juillet 2022) : 466. http://dx.doi.org/10.1149/ma2022-013466mtgabs.

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Redox flow batteries (RFBs) are a promising technology for grid scale stationary energy storage to complement renewable energy systems. These batteries have a relatively low energy density; however, they offer important advantages, including: long life-time; decoupled energy (arbitrarily large electrolyte volume) and power (electrode area); high round-trip efficiency; scalability and design flexibility; fast response; and low environmental impacts. These advantages make them superior to many energy storage technologies for stationary applications [1-4]. Among the various types of RFBs, vanadium RFBs (VRFBs) are an emerging technology for grid scale energy storage and the integration of renewable energy generation [5]. The membrane is a key component of a VRFB that separates the two half-cell electrolytes and prevents cross-mixing, while allowing the transport of ions during charge-discharge cycles [6]. The VRFB membrane should exhibit low vanadium ion permeability to minimize self-discharge, low cost, and long‐term chemical stability under normal operating conditions. A high proton conductivity and low vanadium ion crossover are known to improve the efficiency of VRFBs [6-7]. In this study, we present a novel composite Nafion based membrane that results in a significant increase in the VRFB performance. The composite membrane has been characterized for its chemical, structural, and thermal properties using appropriate analytical techniques. The battery performance was evaluated in a flow cell using a ‘zero-gap’ design with an electrode area of 5 cm2. The electrolytic solution, 1.6 M VOSO4 in 3 M H2SO4, was circulated through the cell. Thermally treated carbon papers were used as the cathode and anode electrodes. For charge-discharge experiments, a constant current density (10 to 80 mA cm−2) was applied with upper and lower voltage cut-offs of 1.65 and 0.8 V, respectively. The stability of the battery using the composite membrane was evaluated over 100 cycles. Figures 1 and 2 show the energy efficiency and capacity retention during 100 charge-discharge cycles. The results reveal that the energy efficiency was improved from 51% to 63% by using the composite membrane. In addition, the charge-discharge capacity and capacity retention improved by around 200% and 25%, respectively. This improvement can be attributed to a higher proton conductivity and lower vanadium permeability of the composite membrane. References: [1] M. Skyllas-Kazacos, L. Cao, M. Kazacos, N. Kausar, A. Mousa, Vanadium Electrolyte Studies for the Vanadium Redox Battery-A Review, ChemSusChem. 9 (2016) 1521–1543. [2] A.K. Singh, M. Pahlevaninezhad, N. Yasri, E. Roberts, Degradation of Carbon Electrodes in the All-Vanadium Redox Flow Battery, ChemSusChem. (2021). [3] K.E. Rodby, T.J. Carney, Y. Ashraf Gandomi, J.L. Barton, R.M. Darling, F.R. Brushett, Assessing the levelized cost of vanadium redox flow batteries with capacity fade and rebalancing, J. Power Sources. 460 (2020) 227958. [4] M. Pahlevaninezhad, P. Leung, M. Pahlevani, F. C. Walsh, C. Ponce de Leon, and E. P. L. Roberts, Experimental and Computational Studies of Disperse Blue-1 in Organic Non-Aqueous Redox Flow Batteries, J. Power Sources, Volume 500, 15 July 2021, 229942. [5] X.Z. Yuan, C. Song, A. Platt, N. Zhao, H. Wang, H. Li, K. Fatih, D. Jang, A review of all-vanadium redox flow battery durability: Degradation mechanisms and mitigation strategies, Int. J. Energy Res. (2019). https://doi.org/10.1002/er.4607. [6] X. Li, H. Zhang, Zh. Mai, H. Zhang, I. Vankelecom, Ion exchange membranes for vanadium redox flow battery (VRB) applications, Energy Environ. Sci., 2011, 4, 1147. [7] L. Yu, F. Lin, L. Xua, J. Xi, A recast Nafion/graphene oxide composite membrane for advanced vanadium redox flow batteries, RSC Adv., 2016, 6, 3756. Figure 1

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Mehta, Mohit Rakesh, Chetan S. Kulkarni et John Lawson. « Predicting Thermal Runaway Event in an Li-Ion Cell on UAV Fight Profiles ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 448. http://dx.doi.org/10.1149/ma2022-012448mtgabs.

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As the energy storage devices continue to "pack" more energy in a small space, any damage, battery component failure, manufacturing defect, or electrically abusing the battery can lead to catastrophic thermal runaway events. A catastrophic thermal event in a cell leads to high temperature, in some instances spewing of battery materials due to gas development from side reactions initiated due to high internal temperatures. Also, a thermal runaway event can propagate from a single "failed" cell to the pack in a battery pack, leading to a more significant event. Mitigating a thermal runaway event is important in the commercial and automotive sectors. However, preventing such events in an electric aircraft (or air taxis) is paramount due to the lack of alternatives in the event of a failure. Battery prognostics algorithms allow the prediction of state-of-charge (SOC) and end-of-life (EOL) of a Li-ion battery in a UAV (unmanned air vehicle) [1]. For this presentation, we will extend this two-level battery predictive algorithm to predict SOC, EOL, and estimated maximum temperature during a simulated flight. The model is extended by integrating a lumped physics-driven thermal model for high current densities [2]. The parameters used to control SOC and EOL are maximum storable charge, time constant for Li-ion diffusivity in the carbon particles, and internal cell resistance. Cycling leads to an increase in the heat generated by an aged Li-ion cell with a LiyCoO2 (LCO) cathode and a LixC6 (MCMB) anode. The aging of a cell leads to increase in SEI layer thickness, the diffusion time for the lithium ions inside the electrodes, and the local reaction rates, in addition to the thermodynamic abuse caused by fixed cycling voltages controlled by a Battery Management System. As the battery ages, the cell resistance increases, while the onset temperature of the thermal runaway decreases (depends on the cell chemistry and cell abuse history). Any large deviation of the cell temperature from the estimated (expected) value can identify a faulty cell. Since SEI decomposition has the lowest onset temperature in the series of reactions leading to thermal runaway, the model considers the self-heating rate of the SEI decomposition as onset temperature (similar to Ref. [3]). The parameters in the Arrhenius equation for the SEI heating rate depend on the number of cycles, the cell's operating temperature, and the cell's abuse history [4,5]. Coupling the electrochemical, thermal, and aging model allow the prognostic algorithm to estimate a typical cell voltage and temperature as a function of age (cycling and calendar), whose departure from measured values from the BMS is used to identify a safety event. In addition, we will present the results from two simulated flight scenarios for a UAV: typical and extreme, since the power requirements vary significantly during take-off, landing, and changing altitudes, while the power requirements remain low during the cruise. For this presentation, the power requirement for a battery pack in a UAV is scaled to a single cell. This cell is cycled through a simulated profile, and the data is collected and used to predict a safety event. References: [1] M. Daigle, C.S. Kulkarni, End-of-discharge and End-of-life Prediction in Lithium-ion Batteries with Electrochemistry-based Aging Models, in: AIAA Infotech @ Aerospace, American Institute of Aeronautics and Astronautics, San Diego, California, USA, 2016. https://doi.org/10.2514/6.2016-2132. [2] J. Mao, W. Tiedemann, J. Newman, Simulation of temperature rise in Li-ion cells at very high currents, Journal of Power Sources. 271 (2014) 444–454. https://doi.org/10.1016/j.jpowsour.2014.08.033. [3] A. Kriston, A. Podias, I. Adanouj, A. Pfrang, Analysis of the Effect of Thermal Runaway Initiation Conditions on the Severity of Thermal Runaway—Numerical Simulation and Machine Learning Study, Journal of the Electrochemical Society. 167 (2020) 090555. https://doi.org/10.1149/1945-7111/ab9b0b. [4] V. Ruiz, A. Kriston, I. Adanouj, M. Destro, D. Fontana, A. Pfrang, Degradation Studies on Lithium Iron Phosphate - Graphite Cells. The Effect of Dissimilar Charging – Discharging Temperatures, Electrochimica Acta. 240 (2017) 495–505. https://doi.org/10.1016/j.electacta.2017.03.126. [5] M. Börner, A. Friesen, M. Grützke, Y.P. Stenzel, G. Brunklaus, J. Haetge, S. Nowak, F.M. Schappacher, M. Winter, Correlation of aging and thermal stability of commercial 18650-type lithium ion batteries, Journal of Power Sources. 342 (2017) 382–392. https://doi.org/10.1016/j.jpowsour.2016.12.041.

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Tan, Sha, Xiao-Qing Yang, Xuelong Wang, Jie Xiao, Yijin Liu, Kang Xu et Enyuan Hu. « (Invited) Identification of Lithium Hydride and Nanocrystalline Lithium Fluoride in the SEI of Lithium Metal Anodes and the Stabilization of High Ni Layered Structure at Ultra-High Voltage through Cathode Electrolyte Interphase Engineering ». ECS Meeting Abstracts MA2022-02, n^o 2 (9 octobre 2022) : 129. http://dx.doi.org/10.1149/ma2022-022129mtgabs.

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Solid-electrolyte interphase (SEI) plays a pivotal role in the performance of lithium metal anode, which is promising for high energy batteries. Understanding SEI composition is important but very challenging. Here we report on the use of synchrotron-based X-ray diffraction and pair distribution function analysis to identify and differentiate the two elusive components, LiH and LiF, in the SEI of lithium metal anodes. LiH is identified as a component of SEI in high abundance, and the possibility of its misidentification as LiF in the literature is discussed. LiF in the SEI is found to have different structural features from LiF in bulk phase, including larger lattice parameter and smaller grain size (<3 nm). These characteristics favor Li+ transport, and explain why an ionic insulator, like LiF, has been found to be a favored component for SEI. PDF analysis of the SEI reveals key amorphous components related to solvent or anion decomposition. Nickel-rich layered cathode materials with high energy density are very promising for next generation batteries when coupled with lithium metal anode. However, the practical capacities accessible are far less than the theoretical value due to their structural instability during cycling, especially when charged at high voltages. Such challenge has been attributed to the concomitant electrolyte instability and cathode structural and morphological degradation. Therefore, various approaches have been developed through electrolyte engineering and bulk cathode material modifications. In this presentation, we will report a simple interphase engineering approach by using an ionic electrolyte additive, lithium difluorophosphate (LiDFP). Through theoretical calculation, we found that self-decomposition product PO2F of LiDFP additive is adsorbed strongly and uniformly on the Ni-rich cathode, which is further decomposed to Li3PO4 and LiF through the catalytic effect of transition metals. The new interphasial chemistry contributed from LiDFP stabilizes the bulk structure of Ni-rich cathode materials and prevents the performance degradation by suppressing the dissolution of transition metals and undesired structural changes. Even after 200 cycles with charge limit as high as 4.8 V, no rock-salt phase can be detected in LiNi0.76Co0.10Mn0.14O2 (NMC76), and the cell consisting of NMC76 cathode and lithium metal anode retains 97% of the initial capacity (235 mAh/g). Various advanced characterizations were used, on both atomic and electrode levels, to reveal the mechanism how a new interphase stabilizes the layer structures in bulk electrode. The dissolution of nickel was identified to be most serious at high voltage, rather than the widely believed manganese dissolution. The transition metal dissolution can be effectively suppressed by LiDFP additive. Furthermore, the cathode surface protected by LiDFP-derived interphase is shown to regulate a more uniform lithium distribution within the bulk cathode particles and effectively mitigate the strain and crack formation. Machine-learning assisted nano-tomography discovered that such interphase-bulk interaction is most effective for those small-sized, spherically-shaped particles. Acknowledgement: The work done at Brookhaven National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Vehicle Technology Office of the U.S. DOE through the Advanced Battery Materials Research (BMR) Program, (Battery500 Consortium), and Applied Battery Research for Transportation (ABRT) program under contract No. DE-SC0012704. This work used the resources of the Center for Functional Nanomaterials, a U.S. DOE office of Science User Facility, at Brookhaven National Laboratory, and beamlines 5-ID, 7-BM, 23-ID-2, and 28-ID-2 of the National Synchrotron Light Source II, a US DOE Office of Science user facility operated for the DOE Office of Science by Brookhaven National Laboratory under contract no. DE-SC0012704. The work done at Pacific Northwest National Laboratory was supported by the Assistant Secretary for Energy Efficiency and Renewable Energy, Office of Vehicle Technologies of the US Department of Energy through the Advanced Battery Materials Research (BMR) Program (Battery500 Consortium) under contract No. DE-AC02-05CH11231. The work at ARL was performed under JCESR, an Energy Research Hub funded by Basic Energy Science, US Department of Energy.

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Streck, Luiza, Thomas Roth, Peter Keil, Benjamin Strehle, Severin Ludmann et Andreas Jossen. « Determination of Leakage Currents Via Voltage Hold and Voltage Relaxation Method Using High Precision Coulometry - a Comparison and Optimization Study ». ECS Meeting Abstracts MA2022-02, n^o 3 (9 octobre 2022) : 350. http://dx.doi.org/10.1149/ma2022-023350mtgabs.

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Parasitic side reactions on the surface of the anode and the cathode of lithium-ion batteries contribute significantly to calendar and cyclic aging [1, 2]. In order to investigate these parasitic side reactions, such as solid electrolyte interface growth, this study focuses on two methods broadly utilized to determine leakage currents: the voltage hold and the voltage relaxation method. Regarding the voltage relaxation method, the open circuit voltage (OCV) decay is observed over weeks without allowing active electrode de-/lithiation [3] and subsequently, a small pulse is performed to calculate the leakage current [4]. For the voltage hold method, a defined voltage is kept constant, which compensates the parasitic side effects and allows active electrode de-/lithiation to maintain the state of charge (SoC) [5, 6]. To compare these methods, different results are found in literature. On the one hand, both methods were reported to deliver individual results [3, 7], while other research activities [8] found the variance only at 100% SoC. Therefore, voltage hold and voltage relaxation were compared in this study, utilizing high precision coulometry (HPC). The measurements were conducted on 16 commercial LGChem INR18650MJ1 cylindrical cells at 25 °C, 40 °C and 55 °C and different SoCs of 10%, 50%, 90%, and 100% SoC, respectively. The cells were preconditioned to each SoC and were subsequently stored for 30 days to minimize relaxation and anode overhang effects. Afterwards, voltage hold and voltage relaxation measurements were carried out for 21 days at each temperature and SoC. In addition to the discharge pulse, an incremental capacity analysis (ICA) was conducted for all three temperatures through the whole voltage range to compare and validate the results obtained. The measurements of this study delivered similar results for the voltage hold and the voltage relaxation method, especially at 10% SoC and 50% SoC. Consequently, the voltage hold did not contribute to additional parasitic side reactions from allowing active de-/lithiation of the electrode. Minor deviations were found for 90% SoC and 100% SoC, for which one possible explanation may be the flat shape of the OCV curve, among others. In addition, the results show a strong dependency on the pulse length and strength. This study was part of the project ExZellTUM III, funded by the German Federal Ministry of Education and Research (BMBF) under grant number 03XP0255, supervised by Project Management Jülich (PTJ). Literature [1] Smith, A.; Burns, J.; Dahn, J.: A high precision study of the coulombic efficiency of Li-ion batteries, In: Electrochemical and Solid-State Letters 13, p. A177, 2010 [2] Birkl, C. R.; Roberts, M. R.; McTurk, E.; Bruce, P. G.; Howey, D. A.: Degradation diagnostics for lithium ion cells, In: Journal of Power Sources 341, p. 373-386, 2017 [3] Zilberman, I.; Sturm, J.; Jossen, A.: Reversible self-discharge and calendar aging of 18650 nickel-rich, silicon-graphite lithium-ion cells, In: Journal of Power Sources 425 (9), p. 217-226, 2019 [4] Schmidt, J. P.; Weber, A.; Ivers-Tiffée, E.: A novel and fast method of characterizing the self-discharge behaviour of lithium-ion cells using a pulse-measurements technique, In: Journal of Power Sources 274, p.1231-1238, 2015 [5] Lewerenz, M.; Käbitz, S.; Knips, M.; Münnix, J.; Schmalstieg, J.; Warnecke, A.; Uwe Sauer, D.: New method evaluating currents keeping the voltage constant for fast and highly resolved measurement of Arrhenius relation and capacity fade, In: Journal of Power Sources 353, p.144-151, 2017 [6] Vadivel, N. R.; Ha, S.; He, M.; Dees, D.; Trask, S.; Polzin, B.; Gallagher, K. G.: On leakage current measured at high cell voltages in lithium-ion batteries, In: Journal of The Electrochemical Society, 164 (2), p. 508-A517, 2017 [7] Theiler, M.; Endisch, C.; Lewerenz, M.: Float Current Analysis for Fast Calendar Aging Assessment of 18650 Li(NiCoAl)O2/Graphite Cells, In: Batteries 7 (2), p. 22–22, 2021 [8] Käbitz, S.; Gerschler, J. B.; Ecker, M., Yurdagel, Y.; Emmermacher, B.; André, D.; Mitsch, T.; Uwe Sauer, D.: Cycle and calendar life study of a graphite LiNi1/3Mn1/3Co1/3O2 Li-ion high energy system. Part A: Full cell characterization, In: Journal of Power Sources 239, p. 572-583, 2013

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Thiagarajan, Raghav Sai, Suryanarayana Kolluri, Maitri Uppaluri, Yuliya Preger et Venkat R. Subramanian. « A Thermal Tanks-in-Series Model for Capacity Fade Studies in Lithium-Ion Batteries ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 187. http://dx.doi.org/10.1149/ma2022-012187mtgabs.

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Lithium ion batteries are widely adopted due to their high energy density, low self-discharge rate and fast charging capabilities1. However, during their operation, capacity fade occurs as a result of various parasitic reactions causing loss of cyclable lithium ions. A dominant and widely studied fade mechanism is the formation of the Solid Electrolyte Interphase (SEI) layer caused by the reduction of electrolyte at the anode-electrolyte boundary. Temperature plays a crucial role on the electrochemical performance of individual cells, affecting the diffusivities of ions, kinetics of reactions and rate of degradation of the battery. Thermal battery models allow us to study the thermal behavior of cells and are often used for cell configuration optimization and thermal management system design2. In literature, thermal models are incorporated with empirical and physics-based models to capture battery dynamics influenced by temperature. Empirical thermal models are simple and fast to solve but are applicable only for specific operating conditions and cannot capture electrochemical subtleties. Conversely, physics-based models use equations that incorporate transport phenomena and electrochemical reactions occurring in the cell. Common physics-based models are the Single Particle Model (SPM) and the Psuedo-2D (P2D) model. The P2D model is robust but computationally expensive3 and the SPM model does not capture electrolyte transport which has a non-linear temperature dependence. The Thermal Tank-In-Series4,5 model is a systematically volume-averaged form of the P2D model with energy balance equations for the current collectors, cathode, separator and anode. This reduces the number of equations in the model and improves computational speed while maintaining accuracy. This model can be ideal to predict capacity fade during fast charging. Extending on our previous work, we now couple the Thermal Tanks-in-Series model with the growth of the SEI layer for a single-cell sandwich. This model will facilitate understanding of diffusive, kinetic and temperature effects on the growth of the SEI layer and cell capacity fade. References M. Pathak, S. Kolluri, and V. R. Subramanian, J. Electrochem. Soc., 164, A973–A986 (2017). H. Liu, Z. Wei, W. He, and J. Zhao, Energy Convers. Manag., 150, 304–330 (2017). V. Ramadesigan et al., J. Electrochem. Soc., 159, R31–R45 (2012). A. Subramaniam, S. Kolluri, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 113506 (2020). A. Subramaniam et al., J. Electrochem. Soc., 167, 013534 (2020).

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Doumbi, Romuald Teguia, Guy Bertrand Noumi et Tinda Domga. « Electrochemical Degradation of Synthetic Textile Wastewater by C/MnO2 Electrode Assessed by Surface Response Methodology ». Avicenna Journal of Environmental Health Engineering 8, n^o 2 (29 décembre 2021) : 116–25. http://dx.doi.org/10.34172/ajehe.2021.15.

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The current work investigated the optimization of synthetic textile wastewater (STW) containing methyl orange, crystal violet, and neutral red reactive dye degradation on manganese dioxide coated on graphite electrode using the Box-Behnken design (BBD). Carbon coated by manganese oxide (C/ MnO2 ) electrode was prepared by the sol-gel method. Graphite substrates were obtained from spent lithium-ion batteries for recycling and reducing the price of the electrode material in electrochemical processes. C/MnO2 was used as anode and cathode in an electrochemical cell during experiments. In addition, BBD was applied to design the experiments and find the optimal conditions for the degradation of STW. From the proposed model, the rate of the removal efficiency of chemical oxygen demand (COD) reached 83.63% with the optimum conditions (6.989 hours, concentration of 1.5 g/L NaCl, and current density of 50 mA/cm2 ). Based on the obtained optimum values, the specific energy consumption was around 30.359 kWh (kg COD)-1. Furthermore, the C/MnO2 electrode was characterized by Raman spectroscopy, and MnO2 films were prepared from the sol-gel process and deposited on graphite. Thus, using graphite coated with manganese dioxide, indirect anodic oxidation (IAO) can be efficient for the removal of the organic matter from the real textile dye bath.

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Tok, Guelen Ceren, Leonhard Reinschlüssel, Anne Berger et Hubert Andreas Gasteiger. « Spatially Resolved Operando X-Ray Absorption Spectroscopy in NCA/Graphite to Quantify the Potential-Dependent Transition Metal Dissolution and Its Effect on Capacity Fading ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 172. http://dx.doi.org/10.1149/ma2022-012172mtgabs.

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Layered transition metal oxides like NCAs (LiNixCoyAlzO2, with x+y+z=1) and NCMs (LiNixCoyMnzO2, with x+y+z=1) are used as cathode active materials (CAMs) for high energy Li-ion batteries due to their high capacity. However, at high upper cut-off potentials, those CAMs suffer from structural instabilities, resulting in severe capacity fading and thus limiting the accessible capacity that can be obtained. Possible causes for the capacity fade at high cut-off potentials and high state-of-charge (SOC) include the (electro)chemical oxidation of the electrolyte oxidation and transition metal (TM) dissolution from the CAM surface.1 Furthermore, layered TM-oxides are known to release lattice oxygen from the near-surface region at high SOC (i.e., at ≈80% SOC when referenced to the total amount of lithium), resulting in reactive oxygen species that induce electrolyte oxidation and HF formation.2 This release of lattice oxygen results in a surface reconstruction from the pristine layered structure to a more resistive spinel- or rocksalt-like structure, thereby inducing an impedance build-up on the cathode. Diffusion of dissolved transition metals to the anode and their subsequent deposition on the anode active material particles can also have a severe effect on cell aging, as the accumulation of metal species on the graphite anode has shown to catalyze the degradation of the protective anode solid/electrolyte interphase (SEI), eventually resulting in the loss of active lithium and in an anode impedance growth. Since the dissolution of manganese is considered to have the most detrimental effect on the anode SEI compared to cobalt and nickel,3 manganese-free NCAs (e.g., LiNi0.8Co0.15Al0.05O2) might have an advantage over manganese-containing NCMs. In this study, we will examine the potential-dependent dissolution of Ni and Co in NCA/graphite cells using operando XAS, and compare it to the potential-dependent dissolution of Ni, Co, and Mn from LiNi0.6Co0.2Mn0.2O2 (NMC622) that we had determined previously by operando XAS.4 Owing to the specially designed geometry of the operando XAS cell,5 we can spectroscopically access and independently investigate the concentration and oxidation state of transition metals, both dissolved in the electrolyte and deposited within the graphite anode. This is illustrated for an NCA/graphite cell in Figure 1. We will also examine the effect of lattice oxygen release from NCA on the NCA/graphite full-cell performance by applying different techniques: We employ a three-electrode Swagelok® type T-cell with a gold wire micro reference electrode (µ-GWRE)6 to quantify the anode and the cathode impedance over the course of 100 cycles as a function of the upper cutoff voltage. In addition, on-line electrochemical mass spectrometry (OEMS)7 is applied to detect the onset SOC for the release of lattice oxygen. From these comparisons, we aim to get a detailed understanding about the influence of transition metal dissolution from NCA on capacity fade and cycle life. References: J. A. Gilbert, I. A. Shkrob, and D. P. Abraham, Journal of The Electrochemical Society, 164 (2), A389-A399 (2017). R. Jung, M. Metzger, F. Maglia, C. Stinner, and H. A. Gasteiger, Journal of The Electrochemical Society, 164 (7), A1361-A1377 (2017). S. Solchenbach, G. Hong, A. T. S. Freiberg, R. Jung, and H. A. Gasteiger, Journal of The Electrochemical Society, 165 (14), A3304-A3312 (2018). R. Jung, F. Linsenmann, R. Thomas, J. Wandt, S. Solchenbach, F. Maglia, C. Stinner, M. Tromp, and H. A. Gasteiger, Journal of The Electrochemical Society, 166 (2), A378-A389 (2019). J. Wandt, A. Freiberg, R. Thomas, Y. Gorlin, A. Siebel, R. Jung, H. A. Gasteiger, and M. Tromp, Journal of Materials Chemistry A, 4 (47), 18300-18305 (2016). S. Solchenbach, D. Pritzl, E. J. Y. Kong, J. Landesfeind, and H. A. Gasteiger, Journal of The Electrochemical Society, 163 (10), A2265-A2272 (2016). N. Tsiouvaras, S. Meini, I. Buchberger, and H. A. Gasteiger, Journal of The Electrochemical Society, 160 (3), A471-A477 (2013). Figure 1

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Thiagarajan, Raghav Sai, Akshay Subramaniam, Suryanarayana Kolluri, Maitri Uppaluri, Yuliya Preger et Venkat R. Subramanian. « A Thermal Tanks-in-Series Model for Capacity Fade Validation Studies in Lithium-Ion Batteries ». ECS Meeting Abstracts MA2022-02, n^o 3 (9 octobre 2022) : 177. http://dx.doi.org/10.1149/ma2022-023177mtgabs.

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Lithium ion batteries are widely adopted due to their high energy density, low self-discharge rate and fast charging capabilities1. However, during their operation, capacity fade occurs as a result of various parasitic reactions causing loss of cyclable lithium ions. A dominant and widely studied fade mechanism is the formation of the Solid Electrolyte Interphase (SEI) layer caused by the reduction of electrolyte at the anode-electrolyte boundary. Temperature plays a crucial role on the electrochemical performance of individual cells, affecting the diffusivities of ions, kinetics of reactions and rate of degradation of the battery. Thermal battery models allow us to study the thermal behavior of cells and are often used for cell configuration optimization and thermal management system design2. In literature, thermal models are incorporated with empirical and physics-based models to capture battery dynamics influenced by temperature. Empirical thermal models are simple and fast to solve but are applicable only for specific operating conditions and cannot capture electrochemical subtleties. Conversely, physics-based models use equations that incorporate transport phenomena and electrochemical reactions occurring in the cell. Common physics-based models are the Single Particle Model (SPM) and the Psuedo-2D (P2D) model. The P2D model is robust but computationally expensive3 and the SPM model does not capture electrolyte transport which has a non-linear temperature dependence. The Thermal Tank-In-Series4,5 model is a systematically volume-averaged form of the P2D model with energy balance equations for the current collectors, cathode, separator and anode. This reduces the number of equations in the model and improves computational speed while maintaining accuracy. This model can be ideal to predict capacity fade during fast charging. Extending on our previous work, we take the Thermal Tanks-in-Series model coupled with SEI layer formation for a single-cell sandwich and apply it to analyze capacity fade under different temperature cycling conditions. Experimental validation of the model will facilitate understanding of diffusive, kinetic and temperature effects on the growth of the SEI layer and cell capacity fade. References M. Pathak, S. Kolluri, and V. R. Subramanian, J. Electrochem. Soc., 164, A973–A986 (2017). H. Liu, Z. Wei, W. He, and J. Zhao, Energy Convers. Manag., 150, 304–330 (2017). V. Ramadesigan et al., J. Electrochem. Soc., 159, R31–R45 (2012). A. Subramaniam, S. Kolluri, S. Santhanagopalan, and V. R. Subramanian, J. Electrochem. Soc., 167, 113506 (2020). A. Subramaniam et al., J. Electrochem. Soc., 167, 013534 (2020).

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Mori, Yuki, Chiyuri Komori et Gen Inoue. « (Digital Presentation) Prediction of an in-Plane Anomalous Current Using Numerical Simulation and Machine Learning ». ECS Meeting Abstracts MA2022-02, n^o 6 (9 octobre 2022) : 604. http://dx.doi.org/10.1149/ma2022-026604mtgabs.

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Even normally shipped batteries may contain disturbing factors such as very small amounts of foreign matter or structural inhomogeneity, which can cause serious accidents such as thermal runaway or explosions. Since dismantling and identifying the cause is time-consuming and costly, nondestructive techniques for identifying the cause are required. A method for detecting abnormal current distribution by magnetic field inverse analysis has been proposed as one such method, but it is difficult to directly elucidate the factors that cause the abnormal current distribution itself. In this study, we first focused on the effect of different separator structures and analyzed the in-plane directional current distribution using machine learning in order to construct a non-destructive model for estimating the causes. A one-dimensional model based on porous electrode theory [1] was used. Constant current charging, homogeneous electrode layer structure, uniform Li concentration in active material particles, and isothermal conditions were assumed. The electrode layer was assumed to be a porous body consisting of active material, electrolyte, and auxiliary materials (conductivity assistant and binder). Using the previously reported structural information and physical properties [2], [3], Case 1 was a coin cell using LiNi1/3Co1/3Mn1/3O2 as the cathode active material, and Case 2 was a laminated cell using LiCoO2 as the cathode active material. The anode active material was graphite and the electrolyte was 1.0 M LiPF6 solution in EC・DEC solvent for both Case 1 and 2. The degree of flexure of the cathode and anode was determined using the formulas from previous studies [4]. Cross-sectional images of the actual biaxially oriented separator were obtained using a focused ion beam scanning electron microscope, and the three-dimensional simulated structure was reproduced based on these images (Sep. A). Similarly, a nonwoven fabric structure (Sep. B) and a foam structure (Sep. C) were also reproduced. Since the collector foils are connected in-plane, the potentials at both ends of the cell must be uniform. Under this constraint, the ion current distribution can be estimated depending on the in-plane structure distribution of the separator. In this study, the correlation between the local porosity (ε) of the separator and the local ion current (denoted as C-rate) was determined using a nonlinear regression method called Support Vector Regression (SVR) [5]. 100 points were taken randomly from 0.4~1.0 and 5~10 for ε and C-rate, respectively, and used as explanatory variables. Each charging curve was compared with the charging curve at the in-plane mean value of (ε, C) = (0.545, 7.5), and the RMSE (root mean square error) of the voltage was calculated as the objective variable. The in-plane reaction distribution was obtained from the voltage error predicted from ε and C-rate by SVR and the porosity distribution of the separator. The mesh size was 40 nm/pixel. For each separator, the difference between high and low reaction profiles was more clearly observed in Case 2. The reaction overvoltage distribution at a certain point in Case 2 was acquired, and it was confirmed that the reaction was concentrated near the separator of the negative electrode. This also made it possible to estimate the Li deposition point, which is the starting point of degradation. Using machine learning to analyze the in-plane current distribution, it was found that the current distribution differs depending on the electrode conditions even for the same separator. We will use this technology to develop a technique for identifying factors based on the current distribution obtained by nondestructive measurement. References [1] G. M. Goldin et al., Electrochim. Acta., 64 118 (2012). [2] G. Inoue et al., J. Chem. Eng. Japan., 54 (5) 207-212 (2021). [3] K. Ikeshita et al., ECS Trans., 75 (20) 165-172 (2017). [4] G. Inoue et al., J. Pow. Sour., 342, 476 (2017). [5] C. Cortes et al., Mach. Learn., 20 (3) 273-297 (1995).

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Witt, Daniel, Lars Bläubaum, Florian Baakes et Ulrike Krewer. « In-Depth Analysis of the Substantial Effect of Fast Formation on Lithium-Ion Cell Characteristics ». ECS Meeting Abstracts MA2022-02, n^o 6 (9 octobre 2022) : 623. http://dx.doi.org/10.1149/ma2022-026623mtgabs.

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The formation of lithium-ion batteries is a crucial process step in battery production. Although it covers only the first few charging and discharging cycles, it impacts both the long-term degradation as well as the performance characteristics of the final cell. Commonly, formation times are on the order of multiple days due to relatively low C-rates. Although this prevents safety-critical lithium plating, research has shown that neither the slowest nor the fastest formation result into the best possible cell characteristics. [1] To allow for a knowledge-based design of the cell formation process, detailed cell diagnostics including the characterization of the formed solid electrolyte interphase (SEI) are indispensable. However, the preparative effort for most experimental methods for SEI characterization like SEM or XPS is significant and will also require cell disassembly. An in-operando cell diagnosis can be realized with physicochemical modeling based on non-destructive dynamic electrochemical measurements. However, the dynamics of the SEI are commonly either modeled in a simplified way or the models are not designed for the simulation of various measurement types. To overcome these limitations, we extended the classic battery model from Doyle et al. [2] with a detailed SEI modeling. This finally allows to describe C-Rate and EIS data with the same parameter set (see Fig. 1a,1b), providing detailed insights into performance-limiting processes and their changes along cell aging. [3] On the experimental side, we performed a broad formation study at different temperatures with different currents and current profiles, using small-scale three-electrode test cells. Fig. 1c) shows the discharge capacity for different formation procedures. Clearly, the performance significantly depends on the chosen formation conditions. The model-based cell diagnosis helps to shed light onto this interrelation. Surprisingly, we found that the bulk and interfacial properties of the SEI are not the root cause for the substantial differences in the cell’s fast charge/discharge capability. In fact, the effective transport properties in the anode electrolyte phase are driving the performance differences. Furthermore, the cathode reaction kinetics are affected by the chosen cell formation protocol. Ultimately, our experimental formation study in combination with the model-based cell diagnosis highlights that the cell formation process is not only about a stable SEI but also about minimizing the impact of reaction products from the SEI formation on the bulk electrolyte phase. References: [1] H. Mao et al. (2018) J Power Sources 402, 107-115 [2] M. Doyle et al. (1993) J Electrochem Soc 140 (6), 1526-1533 [3] D. Witt et al. (2022) Batteries Supercaps, 10.1002/batt.202200067 Figure 1

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Pfleging, Wilhelm, Peter Smyrek, Zheng Yijing, Ulrich Rist, Yannic Sterzl, Alexandra Meyer et Penghui Zhu. « (Invited) 3D Electrode Architectures for High Power and High Energy Lithium-Ion Battery Operation - Recent Approaches and Process Upscaling ». ECS Meeting Abstracts MA2022-02, n^o 6 (9 octobre 2022) : 593. http://dx.doi.org/10.1149/ma2022-026593mtgabs.

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During the next decades, combustion driven cars will be completely replaced by electrical vehicles (EVs) and it seems quite obvious that liquid electrolyte lithium-ion batteries (LIBs) will be the dominating energy storage system for the next at least 5 to 10 years. As a consequence, in Europe numerous Gigafactories have recently been planned with this state of technology. However, the current lithium-ion battery technology suffers so far from some restrictions like the inability to combine high power and high energy operations at the same time. This limitation is mainly attributed to the cathode architecture and respective mass loading. In addition, the further demand for a significantly enhanced fast charging mainly requires an optimization of the anode design flanked by a high areal capacity. Advanced 3D electrode architectures based on a thick film electrode concept seem to be the most promising approach to overcome the current limitations in battery performances. However, respective technology innovations need to provide a high compatibility grade to existing manufacturing routes in order to enable the required integration in existing and planned factories. For so-called “generation 3” materials, i.e., nickel-rich lithium nickel manganese cobalt oxide (NMC) cathode and silicon-based anode materials, structuring technologies using cutting edge ultrafast high power lasers, are being developed in order to manufacture 3D electrode architectures with high areal capacity. Multibeam laser processing using diffractive optical elements and dual scanner approaches were established in order to enable high processing speeds in roll-to-roll electrode handling systems. The technology readiness level (TRL 6) is demonstrated for pouch cells geometries. For water-based NMC 622 and silicon-graphite composites the laser structuring process was developed. Different structures including hole, grid, and line patterns, were studied regarding their impact on electrochemical performances such as high-rate capability and cell lifetime. Lithium concentration profiles of unstructured and structured electrodes were studied post mortem using laser-induced breakdown spectroscopy (LIBS) in order to evaluate lithium intercalation/deintercalation efficiencies and detect possible cell degradation processes. In comparison to unstructured electrodes, 3D electrodes could hereby always be identified as superior: unstructured thick film electrodes show a significant drop in capacity retention for high power operation and tend to form hot spots acting as starting point for cell failure. The upscaling process is flanked by a further improvement of electrode design. For this purpose very recently laser induced forward transfer (LIFT) is applied as printing technology to draw new concepts for sophisticated model electrode architectures with advanced electrochemical performances. Finally, the micro-/nano-scaled texturing of current collectors and separator material is discussed as further possible approaches for boosting the electrochemical performances of LIB pouch cells.

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Cao, Chuntian, Hans-Georg Steinrück, Partha P. Paul, Alison R. Dunlop, Stephen E. Trask, Andrew N. Jansen, Robert M. Kasse et al. « Conformal Pressure and Fast-Charging Li-Ion Batteries ». Journal of The Electrochemical Society 169, n^o 4 (1 avril 2022) : 040540. http://dx.doi.org/10.1149/1945-7111/ac653f.

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Batteries capable of extreme fast-charging (XFC) are a necessity for the deployment of electric vehicles. Material properties of electrodes and electrolytes along with cell parameters such as stack pressure and temperature have coupled, synergistic, and sometimes deleterious effects on fast-charging performance. We develop a new experimental testbed that allows precise and conformal application of electrode stack pressure. We focus on cell capacity degradation using single-layer pouch cells with graphite anodes, LiNi0.5Mn0.3Co0.2O2 (NMC532) cathodes, and carbonate-based electrolyte. In the tested range (10–125 psi), cells cycled at higher pressure show higher capacity and less capacity fading. Additionally, Li plating decreases with increasing pressure as observed with scanning electron microscopy (SEM) and optical imaging. While the loss of Li inventory from Li plating is the largest contributor to capacity fade, electrochemical and SEM examination of the NMC cathodes after XFC experiments show increased secondary particle damage at lower pressure. We infer that the better performance at higher pressure is due to more homogeneous reactions of active materials across the electrode and less polarization through the electrode thickness. Our study emphasizes the importance of electrode stack pressure in XFC batteries and highlights its subtle role in cell conditions.

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Lian, Fang, Zhong Bao Yu, Sheng Wen Zhong, Li Hua Xu et Qing Guo Liu. « Electrochemical Performance of AA Size MCMB/LiCoO₂ Lithium-Ion Battery Using Three-Electrode Cell ». Key Engineering Materials 336-338 (avril 2007) : 502–4. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.502.

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AA size Li-ion batteries using LiCoO2, MCMB and lithium metal as cathode, anode and reference electrode respectively were assembled, in order to study the individual effect of anode and cathode on the cyclic and overcharge performances. The experimental results showed that the LiCoO2 cathode was the main electrode related to the capacity decay and discharge voltage drop. Increasing polarization of the LiCoO2 cathode, especially at overcharge situation, and the irreversible change of cathode structure led to reduction of discharge capacity and voltage plateau of batteries.

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Nokelainen, Johannes, Bernardo Barbiellini, Jan Kuriplach, Stephan Eijt, Rafael Ferragut, Xin Li, Veenavee Kothalawala et al. « Identifying Redox Orbitals and Defects in Lithium-Ion Cathodes with Compton Scattering and Positron Annihilation Spectroscopies : A Review ». Condensed Matter 7, n^o 3 (26 juillet 2022) : 47. http://dx.doi.org/10.3390/condmat7030047.

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Reduction-oxidation (redox) reactions that transfer conduction electrons from the anode to the cathode are the fundamental processes responsible for generating power in Li-ion batteries. Electronic and microstructural features of the cathode material are controlled by the nature of the redox orbitals and how they respond to Li intercalation. Thus, redox orbitals play a key role in performance of the battery and its degradation with cycling. We unravel spectroscopic descriptors that can be used to gain an atomic-scale handle on the redox mechanisms underlying Li-ion batteries. Our focus is on X-ray Compton Scattering and Positron Annihilation spectroscopies and the related computational approaches for the purpose of identifying orbitals involved in electrochemical transformations in the cathode. This review provides insight into the workings of lithium-ion batteries and opens a pathway for rational design of next-generation battery materials.

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Poyner, Mark A., Indumini Jayasekara et Dale Teeters. « Fabrication of a Novel Nanostructured SnO2/LiCoO2 Lithium-Ion Cell ». MRS Advances 1, n^o 45 (2016) : 3075–81. http://dx.doi.org/10.1557/adv.2016.537.

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ABSTRACTIncorporating nanotechnology processes and techniques to Li ion batteries has helped to improve the cycling capabilities and overall performance of several lithium ion battery chemistries. Nanostructuring a lithium ion battery’s anode and cathode, allows for extremely high surface area electrodes to be produced and utilized in many of these battery systems. Using a nanoporous Anodized Aluminum Oxide (AAO) membrane with nanopores of 200nm in diameter as a template, high surface area nanostructured electrode materials can be synthesized and utilized in a lithium ion cell. Through the use of RF magnetron sputter coating, these nanoporous AAO templates can be sputter coated with a thin film of active anode or cathode materials. The anode and cathode material in this research are SnO2 and LiCoO2, respectively. Nanostructured SnO2 has been investigated as an alternative high capacity anode to replace the more commonly used carbon based anodes of current lithium ion batteries. A novel nanostructured SnO2/LiCoO2 cell can be fabricated in a liquid electrolyte. The galvanostatic cell cycling performance will be discussed. Nanostructuring both electrode materials as well as the electrolyte can lead to a novel all-solid-state Li ion battery. Nanostructured SnO2 anode and LiCoO2 electrodes have been generated along with a polyethylene-oxide (PEO) based electrolyte nanoconfined in an AAO membrane, to generate a functioning nanostructured all-solid-state cell. The cell was investigated using AC impedance spectroscopy and galvanostatic cell cycling. The cycling results of both SnO2/LiCoO2 cell systems will be discussed.

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Ishtiaque, MD Mahdi UL, Jayanth R. Ramamurthy, Cary L. Pint et Todd A. Kingston. « Quantifying the Thermo-Electrochemical Sensitivity of Li-Ion Batteries to Modulating Interelectrode Thermal Gradients ». ECS Meeting Abstracts MA2022-02, n^o 3 (9 octobre 2022) : 348. http://dx.doi.org/10.1149/ma2022-023348mtgabs.

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Li-ion secondary batteries are used in many applications and technologies as energy storage devices because of their relatively high Coulombic efficiency and energy and/or power density. However, Li-ion batteries (LIBs) are prone to safety concerns (e.g., thermal runaway), which limit their application [1]. Thermal conditions are one of the major parameters that influence the safety and performance of LIBs due to temperature-dependent electrochemistry. Low temperatures [2] and high temperatures [3] have distinct effects on LIB electrochemistry and are well-reported in the literature. Although non-uniform thermal conditions are more practical during use, the effect of various non-uniform thermal conditions is not fully understood. A non-uniform temperature distribution can easily develop inside Li-ion cells by surface cooling, and the resulting thermal gradient can have adverse effects. Moreover, the direction of the thermal gradient can dictate local transport mechanisms and can cause different degradation modes [4]. Thus, further assessment of the impact of thermal gradients is needed to fully understand the fundamental electrochemical mechanisms, performance, and safety implications. In this work, we quantify the thermo-electrochemical sensitivity of LIBs to modulating interelectrode thermal gradients in synchronization with electrochemical cycling using a custom test facility. Instrumented single-layer pouch cells are fabricated using NMC cathodes and graphite anodes. The internal temperature of each electrode is obtained in real-time using a thin thermistor. Electrochemical impedance spectroscopy is performed before and after galvanostatic cycling at C/5, and the magnitude and the direction of the thermal gradient in synchronization with cell cycling is varied. Acknowledgments The authors thank Dr. Michele Anderson (Office of Naval Research, grant N00014-21-1-2307) for financial support of this work. The authors also acknowledge Dr. Corey Love and Dr. Rachel Carter (U.S. Naval Research Laboratory) for technical discussion of this work. References [1] X. Wu, K. Song, X. Zhang, N. Hu, L. Li, W. Li, L. Zhang, H. Zhang, Safety Issues in Lithium Ion Batteries: Materials and Cell Design, Frontiers in Energy Research, 7 (2019). [2] H.P. Lin, D. Chua, M. Salomon, H.C. Shiao, M. Hendrickson, E. Plichta, S. Slane, Low-temperature behavior of Li-ion cells, Electrochemical and Solid-State Letters, 4(6) (2001) A71-A73. [3] P. Ramadass, B. Haran, R. White, B.N. Popov, Capacity fade of Sony 18650 cells cycled at elevated temperatures, Journal of Power Sources, 112(2) (2002) 614-620. [4] R. Carter, T.A. Kingston, R.W. Atkinson, M. Parmananda, M. Dubarry, C. Fear, P.P. Mukherjee, C.T. Love, Directionality of thermal gradients in lithium-ion batteries dictates diverging degradation modes, Cell Reports Physical Science, 2(3) (2021) 100351.

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Bae, Ki Yoon, Sung Ho Cho, Byung Hyuk Kim, Byung Dae Son et Woo Young Yoon. « Energy-Density Improvement in Li-Ion Rechargeable Batteries Based on LiCoO2 + LiV3O8 and Graphite + Li-Metal Hybrid Electrodes ». Materials 12, n^o 12 (24 juin 2019) : 2025. http://dx.doi.org/10.3390/ma12122025.

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We developed a novel battery system consisting of a hybrid (LiCoO2 + LiV3O8) cathode in a cell with a hybrid (graphite + Li-metal) anode and compared it with currently used systems. The hybrid cathode was synthesized using various ratios of LiCoO2:LiV3O8, where the 80:20 wt% ratio yielded the best electrochemical performance. The graphite and Li-metal hybrid anode, the composition of which was calculated based on the amount of non-lithiated cathode material (LiV3O8), was used to synthesize a full cell. With the addition of LiV3O8, the discharge capacity of the LiCoO2 + LiV3O8 hybrid cathode increased from 142.03 to 182.88 mA h g−1 (a 28.76% improvement). The energy density of this cathode also increased significantly, from 545.96 to 629.24 W h kg−1 (a 15.21% improvement). The LiCoO2 + LiV3O8 hybrid cathode was characterized through X-ray diffraction analysis, scanning electron microscopy, and energy-dispersive X-ray spectroscopy. Its electrochemical performance was analyzed using a battery-testing system and electrochemical impedance spectroscopy. We expect that optimized synthesis conditions will enable the development of a novel battery system with an increase in energy density and discharge capacity.

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Li, Yao Yao, Yin Hu et Cheng Tao Yang. « Regulating Li+ ; Transfer and Solvation Structure via Metal-Organic Framework for Stable Li Anode ». Key Engineering Materials 939 (25 janvier 2023) : 123–27. http://dx.doi.org/10.4028/p-in7u78.

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Lithium metal batteries (LMBs) possess large application potential for advanced rechargeable batteries due to the high energy density (> 500 Wh kg−1) and alternative cathode materials. Random Li dendrite growth caused by uneven Li+ distribution and local ion depletion near surface of Li anode induces battery failure with inferior long-term stability. Therefore, regulation of ion distribution near anode surface is essential to realize dendrite-free and uniform Li deposition. Herein, a metal-organic framework (MOF), i.e., ZIF-8, is applied to regulate Li+ solvation structure via unsaturated metal-ion sites to achieve uniform Li+ distribution and Li deposition. A stable cycling performance over 800 h for Li symmetrical cell at 3 mA cm−2 and 3 mAh cm−2 without short circuit is realized. The facilitated Li+ solvation via the adsorption effect of metal-ion sites on anions is demonstrated, which further enhances the uniform Li+ distribution near Li anode surface. This work demonstrates an effective strategy for regulating ion coordination and Li+ distribution to stabilize Li anode via MOF-based materials.

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Gohari, Salimeh, Vaclav Knap et Mohammad Reza Yaftian. « Investigation on Cycling and Calendar Aging Processes of 3.4 Ah Lithium-Sulfur Pouch Cells ». Sustainability 13, n^o 16 (23 août 2021) : 9473. http://dx.doi.org/10.3390/su13169473.

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Much attention has been paid to rechargeable lithium-sulfur batteries (Li–SBs) due to their high theoretical specific capacity, high theoretical energy density, and affordable cost. However, their rapid c fading capacity has been one of the key defects in their commercialization. It is believed that sulfuric cathode degradation is driven mainly by passivation of the cathode surface by Li2S at discharge, polysulfide shuttle (reducing the amount of active sulfur at the cathode, passivation of anode surface), and volume changes in the sulfuric cathode. These degradation mechanisms are significant during cycling, and the polysulfide shuttle is strongly present during storage at a high state-of-charge (SOC). Thus, storage at 50% SOC is used to evaluate the effect of the remaining degradation processes on the cell’s performance. In this work, unlike most of the other previous observations that were performed at small-scale cells (coin cells), 3.4 Ah pouch Li–SBs were tested using cycling and calendar aging protocols, and their performance indicators were analyzed. As expected, the fade capacity of the cycling aging cells was greater than that of the calendar aging cells. Additionally, the measurements for the calendar aging cells indicate that, contrary to the expectation of stopping the solubility of long-chain polysulfides and not attending the shuttle effect, these phenomena occur continuously under open-circuit conditions.

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Lucht, Brett L. « (Invited) Electrolyte Oxidation and the Role of Crossover Species in Capacity Loss for Lithium Ion Batteries ». ECS Meeting Abstracts MA2022-01, n^o 2 (7 juillet 2022) : 195. http://dx.doi.org/10.1149/ma2022-012195mtgabs.

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Cycling lithiated metal oxides to high potential (>4.5 V vs Li) is of significant interest for the next generation of lithium ion batteries. Cathodes cycled to high potential suffer from rapid capacity fade due to a combination of thickening of the anode solid electrolyte interphase (SEI) and impedance growth on the cathode. While transition metal catalyzed degradation of the anode SEI has been widely proposed as a primary source of capacity loss, we propose a related acid induced degradation of the anode SEI. A systematic investigation of LiMn2O4, LiNi0.5Mn1.5O4, LiNi0.6Mn0.2Co0.2O2, and LiNi0.8Mn0.1Co0.1O2 cathodes will be presented. The role of potential on the generation of soluble acidic fluorophosphates crossover species and the impact of these species on the structure and stability of the SEI will be presented.

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Zhang, Changhuan, Liran Zhang, Nianwu Li et Xiuqin Zhang. « Studies of FeSe2 Cathode Materials for Mg–Li Hybrid Batteries ». Energies 13, n^o 17 (25 août 2020) : 4375. http://dx.doi.org/10.3390/en13174375.

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Rechargeable magnesium (Mg)-based energy storage has attracted extensive attention in electrochemical storage systems with high theoretical energy densities. The Mg metal is earth-abundant and dendrite-free for the anode. However, there is a strong Coulombic interaction between Mg2+ and host materials that often inhibits solid-state diffusion, resulting in a large polarization and poor electrochemical performances. Herein, we develop a Mg–Li hybrid battery using a Mg-metal anode, an FeSe2 powder with uniform size and a morphology utilizing a simple solution-phase method as the counter electrode and all-phenyl-complex/tetrahydrofuran (APC)-LiCl dual-ion electrolyte. In the Li+-containing electrolyte, at a current density of 15 mA g−1, the Mg–Li hybrid battery (MLIB) delivered a satisfying initial discharge capacity of 525 mAh g−1. Moreover, the capacity was absent in the FeSe2|APC|Mg cell. The working mechanism proposed is the “Li+-only intercalation” at the FeSe2 and the “Mg2+ dissolved or deposited” at the Mg foil in the FeSe2|Mg2+/Li+|Mg cell. Furthermore, ex situ XRD was used to investigate the structural evolution in different charging and discharging states.

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Liang, Dong, Tengfei Bian, Qing Han, Hua Wang, Xiaosheng Song, Binbin Hu, Jinling He et Yong Zhao. « Inhibiting the shuttle effect using artificial membranes with high lithium-ion content for enhancing the stability of the lithium anode ». Journal of Materials Chemistry A 8, n^o 28 (2020) : 14062–70. http://dx.doi.org/10.1039/c9ta13304f.

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A composite membrane with high lithium-ion content demonstrates the capability for inhibiting the diffusion of redox chemicals from cathode to anode in the Li-metal based batteries, and then the cell cycling stabilities are improved.

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Ikhsanudin, Muhammad Nur. « Comparative Study of Novelty Thin-films for Li-ion Batteries ». Energy Storage Technology and Applications 2, n^o 1 (27 juin 2022) : 21. http://dx.doi.org/10.20961/esta.v2i1.61268.

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The development of Li-ion batteries leads to high-density Li-ion battery technology as a storage system. to realize a Li-ion battery with a high energy density is to modify its anode, called a thin-film anode. The anode used is coated with a material thickness of 10 mm, increasing the cathode material that can be accommodated in one cell. This study aimed to analyze the Cu-powder and LTO materials used in Thin-film Li-ion batteries as a substitute for graphite because they offer higher capacity, chemical stability, fast charging technology (LTO), cheap, and environmentally friendly (Cu-powder). Based on XRD and FTIR tests, the material has a good crystal structure, and not many impurities are still contained in it. The SEM results showed that both particles showed uniformity in the shape of a single particle and were strengthened by the SEM-EDX test to review the quantity of each element present in the two materials. The electrochemical test results showed that Cu-powder material was better, with a specific capacity of 144.82 mAh g-1, higher than LTO (81.04 mAh g-1).

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Sun, Yongjiang, Genfu Zhao, Yao Fu, Yongxin Yang, Conghui Zhang, Qi An et Hong Guo. « Understanding a Single-Li-Ion COF Conductor for Being Dendrite Free in a Li-Organic Battery ». Research 2022 (6 octobre 2022) : 1–10. http://dx.doi.org/10.34133/2022/9798582.

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In addition to improving ion conductivity and the transference number, single-Li-ion conductors (SLCs) also enable the elimination of interfacial side reactions and concentration difference polarization. Therefore, the SLCs can achieve high performance in solid-state batteries with Li metal as anode and organic molecule as cathode. Covalent organic frameworks (COFs) are leading candidates for constructing SLCs because of the excellent 1D channels and accurate chemical-modification skeleton. Herein, various contents of lithium-sulfonated covalently anchored COFs (denoted as LiO3S-COF1 and LiO3S-COF2) are controllably synthesized as SLCs. Due to the directional ion channels, high Li contents, and single-ion frameworks, LiO3S-COF2 shows exceptional Li-ion conductivity of 5.47×10−5 S·cm−1, high transference number of 0.93, and low activation energy of 0.15 eV at room temperature. Such preeminent Li-ion-transported properties of LiO3S-COF2 permit stable Li+ plating/stripping in a symmetric lithium metal battery, effectively impeding the Li dendrite growth in a liquid cell. Moreover, the designed quasi-solid-state cell (organic anthraquinone (AQ) as cathode, Li metal as anode, and LiO3S-COF2 as electrolyte) shows high-capacity retention and rate behavior. Consequently, LiO3S-COF2 implies a potential value restraining the dissolution of small organic molecules and Li dendrite growth.

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Shelni Rofika, Rida Nurul, Mardiyati Mardiyati et Rahmat Hidayat. « Characteristics of Ni-Zn Rechargeable Batteries with Zn Anode Prepared by Using Nano-Cellulose as its Binder Agent ». Materials Science Forum 1028 (avril 2021) : 105–10. http://dx.doi.org/10.4028/www.scientific.net/msf.1028.105.

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While the operating voltages of Ni-Zn batteries are smaller than Li-ion batteries, Ni-Zn batteries offer some advantages, such as high specific energy and low cost. Ni-Zn batteries use green materials as they use aqueous electrolytes and do not need hazardous organic solvents. Both Ni and Zn are abundant and much less expensive in comparison to lithium. Therefore, Ni-Zn batteries are more suitable as secondary batteries for applications that do not need mobility, such as for storing electricity from solar panels at home or office building. At present, large scale usage of Ni-Zn batteries is hindered by their low life cycle due to Zn anode degradation during the operation. The Zn anode deteriorates as dendrite and passivation growth causing self-discharge at the Zn anode. Many efforts have been tried to solve those problems by adding additives in the electrode or electrolyte and a specific binder in the Zn anode. In the present work, in addition to standard CMC and PTFE as the binder in Zn anode, we also added nano-cellulose as its binder agent as the host matrix may be formed with a much smaller void, providing much more dispersion of ZnO nanoparticles and better reduction on Zn dendrite formation. The battery structures in this work were Zn-anode | electrolytes (KOH, aqueous) | Ni-cathode. Ni cathode used in this work is similar to those found in commercial Ni-Zn batteries. The Zn anode was prepared with various compositions of binder and hydroxides, such as Ca(OH)2, and ZnO nanoparticles as the active materials. The characteristics of the batteries are largely affected by the composition of the binder and other substances forming the Zn anode, particularly the proportion of the hydroxide. However, in general, the present result shows the potential of this modified Ni-Zn battery as an alternative to supersede expensive Li-ion batteries for low-cost and stationary applications.

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Schulze, Maxwell C., Kae Fink, Jack Palmer, Mike Michael Carroll, Nikita Dutta, Christof Zweifel, Chaiwat Engtrakul, Sang-Don Han, Nathan R. Neale et Bertrand J. Tremolet de Villers. « Reduced Electrolyte Reactivity of Pitch-Carbon Coated Si Nanoparticles for Li-Ion Battery Anodes ». ECS Meeting Abstracts MA2022-02, n^o 4 (9 octobre 2022) : 491. http://dx.doi.org/10.1149/ma2022-024491mtgabs.

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Silicon-based anodes for Li-ion batteries (LIB) have the potential to increase the energy density over graphite-based LIB anodes. However, silicon anodes exhibit poor cycle and calendar lifetimes due to mechanical instabilities and high chemical reactivity with the carbonate-based electrolytes that are typically used in LIBs. In this work, we synthesize a pitch-carbon coated silicon nanoparticle composite active material for LIB anodes that exhibits reduced chemical reactivity with the carbonate electrolyte compared to an uncoated silicon anode. Silicon primary particle sizes <10 nm minimize micro-scale mechanical degradation of the anode composite, while conformal coatings of pitch-carbon minimized the parasitic reactions between the silicon and the electrolyte. When matched with a high voltage NMC811 cathode, the pitch-carbon coated Si anode retains ~75% of its initial capacity over 1000 cycles. Efforts to increase the areal loading of the pitch-carbon coated silicon anodes to realize real energy density improvements over graphite anodes results in severe mechanical degradation on the electrode level. Developing procedures to engineer the architecture of the composite silicon anode may be a solution to this mechanical challenge. Figure 1

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Bhargav, Amruth, et Arumugam Manthiram. « Using Organosulfur Materials to Solve Critical Challenges Facing Lithium-Sulfur Batteries ». ECS Meeting Abstracts MA2022-02, n^o 7 (9 octobre 2022) : 2577. http://dx.doi.org/10.1149/ma2022-0272577mtgabs.

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The high abundance and environmental benignity of sulfur coupled with its high energy density of nearly 2,500 Wh kg-1 render the lithium-sulfur (Li-S) battery technology a sustainable energy storage solution for the future. Unfortunately, in Li-S batteries, the sulfur cathode suffers from poor electronic and ionic conductivity and the notorious polysulfide shuttle effect. Meanwhile, the anode suffers from continuous degradation owing to the high reactivity of Li metal. Organosulfur materials may present a way to overcome these limitations. Organic functional groups bound to sulfur could enhance electronic and ionic conductivity. Limiting the polysulfide order in an organosulfur material can minimize the shuttle effect. Furthermore, organic groups could stabilize the electrolyte-anode interface. Two studies on using organosulfur materials to overcome the challenges of Li-S will be presented. The first study shows a method to rationally design organosulfide polymers that can provide inherent Li-ion conductivity. The enhancement in ionic conductivity results in an improvement in performance under high-rate and high-loading conditions. The application of such materials in flexible Li-S batteries will be showcased. In the second study, a mechanistic understanding of how organosulfide-rich interphase at the Li-metal anode improves the stripping/plating efficiency will be elucidated. By understanding the effect of different functional groups on the efficiency of the anode, a set of design rules for developing organosulfide molecules that generate a stable interface will be proposed.

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Yusuf, Maha. « The In-situ Characterization of Fast-charging Degradation Modes in Li-ion Batteries Using High-resolution Neutron Imaging ». Electrochemical Society Interface 31, n^o 4 (1 décembre 2022) : 38–39. http://dx.doi.org/10.1149/2.f04224if.

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Extreme fast charging (XFC) of lithium-ion batteries (LIBs) in 10 minutes is one of the main goals of the US Advanced Battery Consortium for low-cost, fast-charged electric vehicles by 2023. However, existing LIBs cannot achieve these XFC goals without significant capacity fade over cycling due to complex XFC degradation modes. One of the key XFC failure mechanisms is dead Li plating on the graphite anode. While numerous methods have detected Li plating, they lack three-dimensional non-invasive visualization of dead Li on graphite anodes in full cells during battery cycling. Herein, we demonstrate the viability of high-resolution (spatial resolution: 10–15 μm) neutron micro-computed tomography (μCT) for in-situ characterization of dead Li on graphite anodes (thickness: ~130 μm) in full cells containing NMC cathode, that were cycled at 1C and 6C.

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Zhou, Liu (Amy), Sarah Lucienne Guillot, Monica Lee Usrey et Adrián Peña-Hueso. « Estimating Surface Layer Thickness on Electrodes from Lithium-Ion Batteries By Surface Analysis ». ECS Meeting Abstracts MA2022-02, n^o 3 (9 octobre 2022) : 327. http://dx.doi.org/10.1149/ma2022-023327mtgabs.

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As energy density and operational requirements increase, traditional battery electrolytes are pushed to the breaking point. Silatronix® organosilicon (OS) electrolyte materials are a key building block in next-generation Li-ion systems. Silatronix® has developed and synthesized an entirely new class of OS molecules with superior thermal, chemical, and electrochemical properties including lower anode and cathode impedance and reduce gas generation after high temperature cycling1. The surface layers that form on the electrodes during battery aging are one of the main factors affecting the performance of lithium-ion batteries and can be key to understanding battery electrochemistry2. Thicker surface layers may lead to higher impedance while composition of the surface layer can also affect impedance. In this work, X-ray photoelectron spectroscopy (XPS) was used as the main tool to estimate the thickness of the surface layers on both cathode and anode (Figure 1). The anode surface layer thickness was estimated using depth profiling through the decomposition layer to reveal signal from the bulk anode. The cathode surface layer thickness was estimated using the PVDF signal from the bulk cathode and calculating the attenuation of the pristine signal due to the overlying decomposition species3. Utilizing these methods, the surface layer thicknesses on the anode and cathode were estimated after formation, after HT cycling and after HT storage4. The trend of anode surface layer thickness with aging was explored, as well as the effects of different OS materials on surface layer thickness after different stages of aging, and the correlation between the cell impedance and surface layer thickness. References: Guillot, S.L.; Usrey, M. L.; Peña-Hueso, A.; Kerber, B.M.; Zhou, L.; Du, P.; Johnson, T. Reduced gassing in Lithium-ion batteries with organosilicon additives. Journal of The Electrochemical Society 2021, 168, 030533-030543. Wang, A.; Kadam, S.; Li, H.; Shi, S.; Qi, Yue. Review on modeling of the anode solid electrolyte interphase (SEI) for lithium-ion batteries, npj Computational Materials 2018, 4, 15. Cumpson, P.J. The Thickogram: a method for easy film thickness measurement in XPS. Surf. Interface Anal. 2000, 29, 403-406. Niehoff, P.; Passerini, S.; Winter, M. Interface investigations of a commercial Lithium-ion battery graphite anode material by sputter Depth Profile X-ray Photoelectron Spectroscopy. Langmuir 2013, 29, (19), 5806–5816. Figure 1

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Rahman, Ashikur, Xianke Lin et Chongming Wang. « Li-Ion Battery Anode State of Charge Estimation and Degradation Monitoring Using Battery Casing via Unknown Input Observer ». Energies 15, n^o 15 (4 août 2022) : 5662. http://dx.doi.org/10.3390/en15155662.

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The anode state of charge (SOC) and degradation information pertaining to lithium-ion batteries (LIBs) is crucial for understanding battery degradation over time. This information about each cell in a battery pack can help prolong the battery pack’s life cycle. Because of the limited observability, estimating the anode state and capacity fade is difficult. This task is even more challenging for the cells in a battery pack, as the current through the individual cell is not constant when cells are connected in parallel. Considering these challenges, this paper presents a novel method to set up three-electrode cells by using the battery’s casing as a reference electrode for building a three-electrode battery pack. This work is a continuation of the authors’ previous research. An unknown input observer (UIO) is employed to estimate the anode SOC of an individual battery in the battery pack. To ensure the stability of a defined Lyapunov function, the UIO parameter matrices are expressed as a linear matrix inequality (LMI). The anode SOC of a lithium nickel manganese cobalt oxide (NMC) battery is estimated by using the standard graphite potential (SGP) and state of lithiation (SOL) characteristic curve. The anode capacity is then calculated by using the total charge transferred in a charging cycle and the estimated SOC of the anode. The degradation of the battery is then evaluated by comparing the capacity fading of the anode to the total charge carried to the cell. The proposed method can estimate the anode SOC and capacity fade of an individual battery in a battery pack, which can monitor the degradation of the individual batteries and the battery pack in real time. By using the proposed method, we can identify the over-degraded batteries in the pack for remaining useful life analysis on the battery.

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Articles de revues sur le sujet « Li-ion batteries, Cell degradation, Anode, Cathode »

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