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Articles de revues sur le sujet "Li-ion batteries, Cell degradation, Anode, Cathode"
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Mao, Jing, Ke Hua Dai et Yu Chun Zhai. « Properties of LiNi0.5Mn1.5O4 /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.
Texte intégralRésumé :
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, no 2 (7 juillet 2022) : 226. http://dx.doi.org/10.1149/ma2022-012226mtgabs.
Texte intégralRésumé :
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, no 3 (9 octobre 2022) : 188. http://dx.doi.org/10.1149/ma2022-023188mtgabs.
Texte intégralRésumé :
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, no 2 (7 juillet 2022) : 252. http://dx.doi.org/10.1149/ma2022-012252mtgabs.
Texte intégralRésumé :
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, no 16 (12 août 2022) : 5557. http://dx.doi.org/10.3390/ma15165557.
Texte intégralRésumé :
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, no 23 (27 novembre 2019) : 4507. http://dx.doi.org/10.3390/en12234507.
Texte intégralRésumé :
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, no 16 (4 août 2021) : 4724. http://dx.doi.org/10.3390/en14164724.
Texte intégralRésumé :
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, no 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, no 2 (7 juillet 2022) : 265. http://dx.doi.org/10.1149/ma2022-012265mtgabs.
Texte intégralRésumé :
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, no 2 (7 juillet 2022) : 344. http://dx.doi.org/10.1149/ma2022-012344mtgabs.
Texte intégralRésumé :
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
Thèses sur le sujet "Li-ion batteries, Cell degradation, Anode, Cathode"
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FATHI, REZA. « Investigation of Alkaline Ion Rocking Chair Batteries ». Doctoral thesis, Università degli Studi di Milano-Bicocca, 2015. http://hdl.handle.net/10281/77623.
Texte intégralRésumé :
The work was devoted to the improvement of rechargeable batteries. Two different strategies were applied: i) investigation of new electrode materials to increase the battery performance, and ii) studies on failure mechanism of commercial rechargeable batteries. Both Li-ion and Na-ion systems were explored. In the former case, carbon based materials were investigated as high capacity anode (chapter 2), while the cell failure of commercial cells (chapter 3) and pouch cells (chapter 4) were investigated by Ultra High Precision Coulometry (UHPC) and dQ/dV analysis. Moreover, Na-ion systems, a low cost alternative to the Li-ion batteries, were investigated. Sn films were characterized as negative electrode (chapter 5), while Na0.44MnO2 cathode material was investigated by electrochemical techniques (chapter 6). A brief description of the aforementioned chapters is here reported.
Chapter 2. Carbon films were prepared by DC magnetron sputtering at argon pressures ranging from 1 to 30 mTorr. The film sputtered at the lowest pressure was fully amorphous, and showed a density of 1.9±0.3 g/cc indicating little porosity. The film sputtered at the highest pressure showed a broad (002) Bragg peak and had a density of 1.35 ± 0.15 g/cc, indicating significant porosity. Electrochemical testing showed that the low pressure sputtered carbon had a reversible specific capacity of about 800 mAh/g, and an average delithiation potential of about 1 V vs. Li/Li+. Heating the same film to 900oC in argon decreased the reversible capacity and the average voltage to 600 mAh/g and 0.75V, respectively.
Chapter 3. Commercial aged LiCoO2/Graphite cells having different cycling histories were studied. Even after 12 years of operation at 37oC, the cells still retained 80% of their initial capacity with coulombic efficiency of 0.99985 when measured at C/20 and 40oC. The capacity loss of these cells could be explained by loss of lithium inventory through growth of the solid electrolyte interphase (SEI) at the anode. There is no evidence of active material loss due to electrical disconnect in these cells. A low upper cut-off voltage (4.075 V) is crucial to the long lifetime of these cells due to electrolyte oxidation reactions at the positive electrode, revealed by the UHPC experiments.
Chapter 4. Li[Ni1/3Mn1/3Co1/3]O2/graphite pouch cells were cycled at various discharge rates of C/2, C, 2C, and 4C at 30.oC. According to dV/dQ analysis there is very small, if any, active mass loss in any of these cells up to 540 cycles. All the lost capacity is due to loss of active lithium atoms in the negative electrode SEI as relative electrode slippage, derived from dV/dQ analysis, and capacity loss are nicely correlated. Scanning electron microscopy images show clear evidence of particle or/and SEI layer cracking at the negative electrode for the cells discharged at 4C, while the NMC particles were unaffected.
Chapter 5. Sn films, obtained by electrodeposition, were structural and electrochemical characterized. Electrochemical potential spectroscopy (EPS) and galvanostatic cycling of the electrodes were investigated in organic electrolyte. Three crystalline and one amorphous phases were identified as well as high discharge capacity (738 mAh/g) was obtained after 4 cycles. Unfortunately material fading, due to the internal stress during cycling, causes poor cyclability.
Chapter 6. Na0.44MnO2 compound was prepared by a modified Pechini method and characterized. The material exhibits a discharge capacity (about 110 mAh/g) at low current (11 mA/g) which decreases to 65 mAh/g at high current (275 mA/g). The electrochemistry was investigated by electrochemical impedance spectroscopy. It was observed that the kinetic limitations are mainly due to the low diffusion coefficient of Na+ in the structure and to the high values of the surface resistance which is the sum of two contributes attributed to the charge transfer process and the presence of a passive layer.
Actes de conférences sur le sujet "Li-ion batteries, Cell degradation, Anode, Cathode"
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Rudolf, Christopher, Corey Love et Marriner Merrill. « Investigation of an Ionic Liquid As a High-Temperature Electrolyte for Silicon-Lithium Systems ». Dans ASME 2020 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2020. http://dx.doi.org/10.1115/imece2020-23780.
Texte intégralRésumé :
Abstract Electrolytes for lithium ion batteries which work over a wide range of temperatures are of interest in both research and applications. Unfortunately, most traditional electrolytes are unstable at high temperatures. As an alternative, solid state electrolytes are sometimes used. These are inherently safer because they have no flammable vapors, and solid state electrolytes can operate at high temperatures, but they typically suffer from very low conductivity at room temperatures. Therefore, they have had limited use. Another option which has been previously explored is the use of ionic liquids. Ionic liquids are liquid salts, with nominally zero vapor pressure. Many are liquid over the temperature of interest (20–200°C). And, there is a tremendous range of available chemistries that can be incorporated into ionic liquids. So, ionic liquids with chemistries that are compatible with lithium ion systems have been developed and demonstrated experimentally at room temperature. In this study, we examined a silicon-lithium battery cycling at room temperature and over 150°C. Using half-cell vial and split-cell structures, we examined a standard electrolyte (LiPF6) at room temperature, and an ionic liquid electrolyte (1-ethyl-3-methylimidazolium bis(trifluorosulfonyl)imide) at room temperature and up to ∼150°C. The ionic liquid used was a nominally high purity product purchased from Sigma Aldrich. It was selected based on results reported in the open literature. The anode used was a wafer of silicon, and the cathode used was an alumina-coated lithium chip. The cells were cycled either 1 or 5 times (charge/discharge) in an argon environment at constant current of 50 μA between 1.5 and 0.05 volts. The results for the study showed that at room temperature, we could successfully cycle with both the standard electrolyte and the lithium ion electrolyte. As expected, there was large-scale fracture of the silicon wafer with the extent of cracking having some correlation with first cycle time. We were unable to identify any electrolyte-specific change in the electrochemical behavior between the standard electrolyte and the ionic liquid at room temperature. Although the ionic liquid was successfully used at room temperature, when the temperature was increased, it behaved very differently and no cells were able to successfully cycle. Video observations during cycling (∼1 day) showed that flocs or debris were forming in the ionic liquid and collecting on the electrode surface. The ionic liquid also discolored during the test. Various mechanisms were considered for this behavior, and preliminary tests will be presented. All materials were stable at room temperature, and the degradation appeared to be linked to the electrochemical process. As a conclusion, our working hypothesis is that, particularly at elevated temperatures, ionic liquid cleanliness and purity can be far more important than at room temperature, and small impurities can cause significant hurdles. This creates an important barrier to research efforts, because the “same” ionic liquids could cause failure in one situation and not in another due to impurities.
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Alavi-Soltani, S. R., T. S. Ravigururajan et Mary Rezac. « Thermal Issues in Lithium-Ion Batteries ». Dans ASME 2006 International Mechanical Engineering Congress and Exposition. ASMEDC, 2006. http://dx.doi.org/10.1115/imece2006-15106.
Texte intégralRésumé :
This paper reviews various studies carried out on thermal issues in lithium-ion batteries. Although thermal behavior of Li-ion batteries plays an important role in performance, life cycle and safety of these batteries, it has not been studied as intensely as chemical characteristics of these batteries. In this review paper, studies concerning thermal issues on Li-ion batteries are classified based on their methodologies and the battery components being investigated. The methodologies include mathematical thermal modeling, calorimetry, electrochemical impedance spectroscopy and thermal management system method. The battery components that have been studied include anode, cathode, electrolyte and the whole cell.
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Jang, Kyung-min, Kwang-Woo Choi, John E. NamGoong et Kwang-Sun Kim. « A Study on Li-Ion Battery Performance Subject to Cathode Materials Using CFD ». Dans ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-87194.
Texte intégralRésumé :
As the demand of the rechargeable battery has been requested not only from operating the small devices, but also from operating the large and medium size equipment such as an electric vehicle, the research has been focused on the stability of the battery, minimization of the energy loss, and finding the new materials for effective energy storage. The Lithium-ion (Li-ion) battery consists of four main components which are cathode active material, anode active material, electrolyte, and the separator. One of current research fields of the Li-ion battery material is in the area of cathode active material. It is because the cathode active material has 30∼40% of the manufacturing cost and it vastly affects the capacity of the batteries. In this research, we conduct one-cell simulation to compare the battery performance for changing the properties of the Cathode material. It is one of the thermochemical parameters that can affect the charge/discharge rate and the life of the batteries. Although, the certain kind of active materials has been reported in previous reports, we used the new material properties and researched about the whole discharge curve for future material development. The heating behavior is also investigated with the arbitrary properties being varied.
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Ma, Jun, Christopher Rahn et Mary Frecker. « Multifunctional NMC-Si Batteries With Self-Actuation and Self-Sensing ». Dans ASME 2017 Conference on Smart Materials, Adaptive Structures and Intelligent Systems. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/smasis2017-3886.
Texte intégralRésumé :
Among anode materials for lithium ion batteries, silicon (Si) is known for high theoretical capacity and low cost. Si changes volume by 300% during cycling, however, often resulting in fast capacity fade. With sufficiently small Si particles in a flexible composite matrix, the cycle life of Si anodes can be extended. Si anodes also demonstrate stress-potential coupling where the open circuit voltage depends on applied stress. In this paper, we present a NMC-Si battery design, utilizing the undesired volume change of Si for actuation and the stress-potential coupling effect for sensing. The battery consists of one Li(Ni1/3Mn1/3Co1/3)O2 (NMC) cathode in a separator pouch placed in an electrolyte-filled container with Si composite anode cantilevers. Models predict the shape of the cantilever as a function of battery state of charge (SOC) and the cell voltage as a function of distributed loading. Simulations of a copper current collector coated with Si active material show 11.05 mAh of energy storage, large displacement in a unimorph configuration (>60% of beam length) and over 100 mV of voltage change due to gravitational loading.
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Barai, Pallab, Srdjan Simunovic et Partha P. Mukherjee. « Damage and Crack Analysis in a Li-Ion Battery Electrode Using Random Spring Model ». Dans ASME 2012 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/imece2012-88624.
Texte intégralRésumé :
Lithium-ion batteries (LiB) are widely used in the electronics industry (such as, cell phones and laptop computers) because of their very high energy density, which reduced the size and weight of the battery significantly. LiB also serves as a renewable energy source for the transportation industry (see Ref. [1,2]). Graphite and LiCoO2 are most frequently used as anode and cathode material inside LiB (see Ref. [2,3]). During the charging and discharging process, intercalation and de-intercalation of Li occur inside the LiB electrodes. Non-uniform distributions of Li induce stress inside the electrodes, also known as diffusion induced stress (DIS). Very high charge or discharge rate can lead to generation of significant amount of tensile or compressive stress inside the electrodes, which can cause damage initiation and accumulation (see Ref. [4]). Propagation of these micro-cracks can cause fracture in the electrode material, which impacts the solid electrolyte interface (SEI) (see Ref. [2,3,5]). Concurrent to the reduction of cyclable Li, resistance between the electrode and electrolyte also increases, which affects the performance and durability of the electrode and has a detrimental consequence on the LiB life (see Ref. [6]).