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1
Francisco, Mark, Cheng-Tang Pan, Bo-Hao Liao, Mao-Sung Wu, Ru-Yuan Yang, Jay Chu, Zhi-Hong Wen, Chien-Feng Liao et Yow-Ling Shiue. « Fabrication and Analysis of Near-Field Electrospun PVDF Fibers with Sol-Gel Coating for Lithium-Ion Battery Separator ». Membranes 11, no 3 (9 mars 2021) : 186. http://dx.doi.org/10.3390/membranes11030186.
Texte intégralRésumé :
Environmental and economic concerns are driving the demand for electric vehicles. However, their development for mass transportation hinges largely on improvements in the separators in lithium-ion batteries (LIBs), the preferred energy source. In this study, innovative separators for LIBs were fabricated by near-field electrospinning (NFES) and the sol-gel method. Using NFES, poly (vinylidene fluoride) (PVDF) fibers were fabricated. Then, PVDF membranes with pores of 220 nm and 450 nm were sandwiched between a monolayer and bilayer of the electrospun fibers. Nanoceramic material with organic resin, formed by the sol-gel method, was coated onto A4 paper, rice paper, nonwoven fabric, and carbon synthetic fabric. Properties of these separators were compared with those of a commercial polypropylene (PP) separator using a scanning electron microscope (SEM), microtensile testing, differential scanning calorimetry (DSC), ion-conductivity measurement, cyclic voltammetry (CV), and charge-discharge cycling. The results indicate that the 220 nm PVDF membrane sandwiched between a bilayer of electrospun fibers had excellent ionic conductivity (~0.57 mS/cm), a porosity of ~70%, an endothermic peak of ~175 °C, better specific capacitance (~356 mAh/g), a higher melting temperature (~160 °C), and a stable cycle performance. The sol-gel coated nonwoven fabric had ionic conductivity, porosity, and specific capacitance of ~0.96 mS/cm., ~64%, and ~220 mAh/g, respectively, and excellent thermal stability despite having a lower specific capacitance (65% of PP separator) and no peak below 270 °C. The present study provides a significant step toward the innovation of materials and processes for fabricating LIB separators.
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Ahmed, Faheem, Shalendra Kumar, Nagih Mohammed Shaalan, Osama Saber, Sarish Rehman, Abdullah Aljaafari, Hatem Abuhimd et Mohammad Alshahrani. « Synergistic Effect of Hexagonal Boron Nitride-Coated Separators and Multi-Walled Carbon Nanotube Anodes for Thermally Stable Lithium-Ion Batteries ». Crystals 12, no 2 (18 janvier 2022) : 125. http://dx.doi.org/10.3390/cryst12020125.
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In this work, we report the development of separators coated with hexagonal boron nitride (hBN) to improve the thermal stability of Li-ion batteries (LIBs). Aiming to achieve a synergistic effect of separators and anodes on thermal stability and electrochemical performance, multiwalled carbon nanotubes (MWCNTs) were prepared via plasma-enhanced chemical vapor deposition (PECVD) method and used as potential anode materials for LIBs. The grown MWCNTs were well characterized by using various techniques which confirmed the formation of MWCNTs. The prepared MWCNTs showed a crystalline structure and smooth surface with a diameter of ~9–12 nm and a length of ~10 μm, respectively. Raman spectra showed the characteristic peaks of MWCNTs and BN, and the sharpness of the peaks showed the highly crystalline nature of the grown MWCNTs. The electrochemical studies were performed on the fabricated coin cell with a MWCNT anode using a pristine and BN-coated separators. The results show that the cell with the BN-coated separator in a conventional organic carbonate-based electrolyte and MWCNTs as the anode resulted in a discharge capacity (at 65 °C) of ~567 mAhg−1 at a current density of 100 mAg−1 for the first cycle, and delivered a capacity of ~471 mAhg−1 for 200 cycles. The columbic efficiency was found to be higher (~84%), which showed excellent reversible charge–discharge behavior as compared with the pristine separator (69%) after 200 cycles. The improved thermal performance of the LIBs with the BN-coated separator and MWCNT anode might be due to the greater homogeneous thermal distribution resulting from the BN coating, and the additional electron pathway provided by the MWCNTs. Thus, the fabricated cell showed promising results in achieving the stable operation of the LIBs even at higher temperatures, which will open a pathway to solve the practical concerns over the use of LIBs at higher temperatures without compromising the performance.
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Huang, Yi-Chen, Yin-Ju Yen, Yu-Hsun Tseng et Sheng-Heng Chung. « Module-Designed Carbon-Coated Separators for High-Loading, High-Sulfur-Utilization Cathodes in Lithium–Sulfur Batteries ». Molecules 27, no 1 (30 décembre 2021) : 228. http://dx.doi.org/10.3390/molecules27010228.
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Lithium–sulfur batteries have great potential as next-generation energy-storage devices because of their high theoretical charge-storage capacity and the low cost of the sulfur cathode. To accelerate the development of lithium–sulfur technology, it is necessary to address the intrinsic material and extrinsic technological challenges brought about by the insulating active solid-state materials and the soluble active liquid-state materials. Herein, we report a systematic investigation of module-designed carbon-coated separators, where the carbon coating layer on the polypropylene membrane decreases the irreversible loss of dissolved polysulfides and increases the reaction kinetics of the high-loading sulfur cathode. Eight different conductive carbon coatings were considered to investigate how the materials’ characteristics contribute to the lithium–sulfur cell’s cathode performance. The cell with a nonporous-carbon-coated separator delivered an optimized peak capacity of 1112 mA∙h g−1 at a cycling rate of C/10 and retained a high reversible capacity of 710 mA∙h g−1 after 200 cycles under lean-electrolyte conditions. Moreover, we demonstrate the practical high specific capacity of the cathode and its commercial potential, achieving high sulfur loading and content of 4.0 mg cm−2 and 70 wt%, respectively, and attaining high areal and gravimetric capacities of 4.45 mA∙h cm−2 and 778 mA∙h g−1, respectively.
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Maraschky, Adam M., Melissa L. Meyerson, Stephen J. Percival, Martha M. Gross, Amanda S. Peretti, Erik D. Spoerke et Leo J. Small. « Optimizing the Current Collector for Sodium Iodide-Metal Halide Catholytes in Low-Temperature Molten Sodium Batteries ». ECS Meeting Abstracts MA2022-02, no 55 (9 octobre 2022) : 2135. http://dx.doi.org/10.1149/ma2022-02552135mtgabs.
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Low-cost, long-duration energy storage is critically needed for a robust electric grid powered by renewable sources. In the pursuit of meeting this need, low-temperature (<130 °C) molten sodium batteries (MNaBs) with NaI-metal halide molten salt catholytes have been developed. This battery design circumvents many of the safety concerns caused by metal dendrites and flammable organic solvents found in Li-metal or Li-ion batteries. It also drastically reduces the high-temperature material requirements and operating costs compared to traditional MNaBs, such as ZEBRA, which operate near 300 °C. The presented battery operates at 110 °C—just above the melting point of Na (98 °C). It features a molten Na anode, a NaSICON ceramic separator, and a NaI/AlCl3 catholyte. Among the key challenges to widespread utilization of these emerging MNaBs is reducing the overpotential on the cathode while operating at practical current densities over numerous cycles. To improve the performance of the cathode, we examined the electrochemical behavior of a variety of disk electrode materials, including W, Mo, Ta, and glassy carbon (GC) in a 3-electrode configuration. A custom cell was designed to mimic a full battery with separators for both the reference and counter electrodes. Excess molten salt was used to keep bulk concentrations practically constant over the course of the experiments. This enabled experiments that isolated the working electrode from other battery elements, such as a changing catholyte or the NaSICON interfaces. Voltammetry, electrochemical impedance spectroscopy, chronopotentiometry, and chronoamperometry were used to evaluate each material’s charge/discharge kinetics and stability. Instability on charging is hypothesized to be due to iodine (I2) adsorption on rapid iodide (I-) oxidation. Discharge, on the other hand, is limited by the transport of triiodide (I3 -), which depends on the battery’s state of charge. Insights from these studies serve as the foundation for the rational design of high-surface area electrodes for iodide-based molten salt catholytes. After initial testing in the 3-electrode cell, the performance of several high surface area current collectors was evaluated in rate tests and continuous cycling of lab-scale battery cells. Sandia National Laboratories is a multi-mission laboratory managed and operated by National Technology and Engineering Solutions of Sandia, LLC., a wholly owned subsidiary of Honeywell International, Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525.
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Dalwadi, Shrey, Arnav Goel, Constantine Kapetanakis, David Salas-de la Cruz et Xiao Hu. « The Integration of Biopolymer-Based Materials for Energy Storage Applications : A Review ». International Journal of Molecular Sciences 24, no 4 (16 février 2023) : 3975. http://dx.doi.org/10.3390/ijms24043975.
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Biopolymers are an emerging class of novel materials with diverse applications and properties such as superior sustainability and tunability. Here, applications of biopolymers are described in the context of energy storage devices, namely lithium-based batteries, zinc-based batteries, and capacitors. Current demand for energy storage technologies calls for improved energy density, preserved performance overtime, and more sustainable end-of-life behavior. Lithium-based and zinc-based batteries often face anode corrosion from processes such as dendrite formation. Capacitors typically struggle with achieving functional energy density caused by an inability to efficiently charge and discharge. Both classes of energy storage need to be packaged with sustainable materials due to their potential leakages of toxic metals. In this review paper, recent progress in energy applications is described for biocompatible polymers such as silk, keratin, collagen, chitosan, cellulose, and agarose. Fabrication techniques are described for various components of the battery/capacitors including the electrode, electrolyte, and separators with biopolymers. Of these methods, incorporating the porosity found within various biopolymers is commonly used to maximize ion transport in the electrolyte and prevent dendrite formations in lithium-based, zinc-based batteries, and capacitors. Overall, integrating biopolymers in energy storage solutions poses a promising alternative that can theoretically match traditional energy sources while eliminating harmful consequences to the environment.
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Wisinska, Natalia H., Magdalena Skunik-Nuckowska, Sławomir Dyjak, Wladyslaw Wieczorek et Pawel J. Kulesza. « Poly(norepinephrine) As a Functional Additive for Hybrid Cellulose/Agarose-Based Hydrogel Membranes : Application to Supercapacitors ». ECS Meeting Abstracts MA2022-02, no 54 (9 octobre 2022) : 2051. http://dx.doi.org/10.1149/ma2022-02542051mtgabs.
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A rapidly growing interest in renewable energy sources requires not only developing efficient energy storage systems but also incorporating a greater number of eco-friendly components. Electrochemical double-layer capacitors (EDLCs) are a class of energy storage devices capable to store the electrical charge due to the separation of oppositely charged ions in the electrical field which results in the formation of an electrical double layer (EDL) at the electrode/electrolyte interface. EDLCs consist in general of two porous carbon-based electrodes pre-soaked with electrolyte and separated with a membrane (separator). The simple electrostatic mechanism of energy storage, coupled with a lack of chemical changes and faradaic transitions during operation, results in high electrical capacitance compared to classical capacitors, significantly higher power density in contrast to batteries, and practically unlimited life span. Currently, commercial EDLCs typically rely on organic solvents, such as acetonitrile or propylene carbonate, with the addition of ionically-conductive salts. However, there are several drawbacks when it comes to practical applications involving particular low conductivity, toxicity, flammability and high cost. This resulted in an increased interest in aqueous electrolytes such as KOH, H2SO4 or simple inorganic salts, which although they have a limited potential window, exhibit many positive features including higher ionic conductivity, lower viscosity, increased safety, lower cost and ease of assembly under ambient atmosphere. Modern and technologically advanced charge storage devices often require high safety flexible and deformable devices for specific applications. However, at the current state-of-the-art, the EDLCs suffer from two prominent limitations (i) the possibility of electrolyte leakage and (ii) high standards of technology to safely encapsulate electrolytes in the device. Therefore, a lot of research is held to develop alternatives for currently used liquid (aqueous and organic) electrolytes. One of the solutions to overcome these limitations are solid-state EDLCs. Those systems use an ionically-conductive polymer or hydrogel membrane, which serves as both the separator and the electrolyte. Cellulose, built of β-(1→4)-linked D-glucose units, is one of the most prevalent and easily degradable biopolymers. Albeit, its wide availability, biodegradability and low cost, the usage of cellulose is limited due to insolubility in most common solvents. The recent alternative, to toxic and flammable organic compounds, such as N, N- dimethylformamide/N2O4, N-methylmorpholine oxide (NMMO), are ionic liquids (ILs), that have been gaining lately a lot of attention in energy storage systems. Various ILs based on imidazolium, pyridinium and ammonium cation paired with strongly basic anion (e.g., OAc-, HCOO-) were also recently used to dissolve cellulose. However, the requirements of high-purity syntheses and the cost of some of the cations/anions may affect a large scale application. Therefore, our research refers to an alternative route of chemical regeneration of microcrystalline cellulose, i.e. its dissolution using an aqueous mixture of NaOH/urea, and further processing into a hydrogel membrane in the presence of cross-linking agent epichlorohydrin. To improve the mechanical strength and electrolyte uptake, in-situ polymerized norepinephrine and agarose were subsequently incorporated obtaining an interpenetrating polymer network (IPN). The structure and morphology of the membranes were characterized with SEM/EDX, CP/MAS 13C-NMR, AT-FTIR, TGA, contact angle, and elementary analysis. The ionic conductivity was determined using impedance spectroscopy over a wide range of temperatures (5-60°C). The relation between stress and strain in the materials was also determined to diagnose the mechanical properties. The cellulose-based hydrogel membranes were further used as a support for various aqueous electrolytes, including H2SO4, Na2SO4, i.e. most commonly used for aqueous EDLCs. Also, the alternative electrolyte was used, i.e. silicotungstic acid, H4SiW12O40 which according to our recent results seems to be a promising candidate to replace conventional acidic electrolytes [1]. The designed systems were compared, in terms of energy, power and cycleability, with their analogues using conventional polypropylene separators and a liquid electrolyte. [1] N.H. Wisinska, M. Skunik-Nuckowska, S. Dyjak, P.J. Kulesza, Factors affecting the performance of electrochemical capacitors operating in Keggin-type silicotungstic acid electrolyte, Appl. Surf. Sci. 530 (2020) 147273, https://doi.org/10.1016/j.apsusc.2020.147273 Acknowledgement Financial support was provided by the National Science Center under Preludium 19 grant no. 2020/37//N/ST4/01679. This work was implemented as a part of Operational Project Knowledge Education Development 2014–2020 co-financed by the European Social Fund, Project No POWR.03.02.00-00-I007/16-00 (POWER 2014-2020)
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Su, Tzu-Chi, et Han-Yi Chen. « Suppression of Dendrite Formation with Porous and Conductive Carbon on Anode for Aqueous Zinc-Ion Hybrid Capacitors ». ECS Meeting Abstracts MA2022-01, no 3 (7 juillet 2022) : 489. http://dx.doi.org/10.1149/ma2022-013489mtgabs.
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Electrochemical energy storage systems with high power and energy density have been drawing attention with the increasing demand for electric vehicles and portable electronics. However, rechargeable nonaqueous lithium-based energy storage system, which is the most widely-used type, is still limited with unsafety, resulting from its toxic organic electrolyte and flammability. Hence, zinc has been considered a strong candidate in rechargeable aqueous energy storage systems. With high theoretical capacity (823 mAh g−1) and low operating potential (−0.76 V vs. standard hydrogen electrode), Zinc-ion batteries show the highest energy density among all aqueous batteries at low cost. Moreover, to improve the low power density and short cycle life for batteries, Zinc-ion hybrid capacitors (ZICs) are introduced by combining the characterizations of both battery and supercapacitor. Despite the advantages of ZICs mentioned above, the instability during the charging and discharging process are unneglectable. Formation of dendrites due to uneven zinc electrostripping and electroplating process on zinc metal anode can cause internal short-circuit after they penetrate the separators of the batteries. Hydrogen generation also results in low Columbic efficiency. To enhance electrochemically stability for zinc metal anode, a zinc anode modification with porous reduced graphene oxide (rGO) is reported. Electrostatic Spray Deposition (ESD) is a technique through which liquid droplets of a precursor solution are accelerated by a high DC voltage to form aerosol and deposit on the heated substrate. By coating rGO with ESD on zinc anode, the study of how the morphology of coating affects the electrostripping and electroplating process can be discussed in detail. The modified materials were examined by scanning electron microscopy and electrochemical active surface area. The porous rGO coated zinc anode shows small voltage polarization and long cycle life. With porous rGO coated zinc anode, the charge distribution on the electrode can be optimized, and the porous structure can guide pathways for zinc ions. Furthermore, the zinc deposition is much uniform than bare zinc during cycling, which can be observed in several operando techniques, including transmission X-ray microscopy and optical microscopy.
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Meng, Jiang-Ping, Yun Gong, Qiang Lin, Miao-Miao Zhang, Pan Zhang, Hui-Fang Shi et Jian-Hua Lin. « Metal–organic frameworks based on rigid ligands as separator membranes in supercapacitor ». Dalton Transactions 44, no 12 (2015) : 5407–16. http://dx.doi.org/10.1039/c4dt03702b.
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Choi, Hyoungwoo, et Byoung-Sun Lee. « Pilot Scale Hybrid Organic/Inorganic Coatings on a Polyolefin Separator to Enhance Dimensional Stability for Thermally Stable Long-Life Rechargeable Batteries ». Polymers 14, no 21 (22 octobre 2022) : 4474. http://dx.doi.org/10.3390/polym14214474.
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The electric vehicle and energy storage markets have grown rapidly in recent years. Thermal runaway caused by malfunctioning Li-ion batteries is an urgent issue with many causes (e.g., mechanical, electrical, and thermal abuse). The most common cause of thermal runaway is the formation of an internal short circuit because of damage to the separator. There has been significant effort to improve the design of separators, but to our knowledge, only inorganic nanoparticle coatings are used in commercial Li-ion batteries. Here, hybrid organic/inorganic coating layers are synthesized in a pilot-scale process that was developed from a crosslinkable polyamide-imide synthesis technique. The fabrication process is optimized to achieve reproducible hybrid organic/inorganic coating layers that are thin (≤4 μm), permeable (≤250 s/100 cc), and thermally stable beyond 150 °C. The hybrid coating layer is applied to mini-18650 Li-ion cells to show that the discharge capacity did not change at low discharge rates, and the retention capacity after 500 cycles was better than that of the reference cells used for comparison. This work demonstrates that a novel hybrid coating layer has the potential to improve the stability of commercial Li-ion batteries.
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Lin, Yupo J. « (Invited) Applications of Novel Electrochemical Technologies for Sustainable Fuel/Chemical Production and Resources Recovery ». ECS Meeting Abstracts MA2022-02, no 27 (9 octobre 2022) : 1043. http://dx.doi.org/10.1149/ma2022-02271043mtgabs.
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Electrochemical processes offer R&D opportunities toward decarbonization and resource recovery for circular economics. Innovate material produced by advancing manufacture techniques further widens its applications. In this presentation, we will discuss electrochemical process designs and material innovation to address technical and economic challenges of separations in biochemical/ biofuel production, resources recovery, CO2 utilization and impaired water treatment. In separations, the electrically driven force enabling selective capture of charged species and/or in-situ aqueous pH manipulation provides high energy efficiency, low capital footprint and cost for industrial applications compared to other separation technologies, e.g., separations by pressure-driven, thermally driven and biological-related. The common practices known are electrodialysis (ED), electrodeionization (EDI), capacitive deionization (CDI), cation intercalation desalination (CID), and ion concentration polarization (ICP). In these techniques, concentrated ions are separated from the liquid energy use is correlated with the quantity of ions removed. Therefore, the selective target capture provides “fit-for-purpose” separations. Pressure-driven processes cannot tune salinity for fit-for-purpose quality desalination but are effective at organic and biological species removal that electrochemical processes are not able to do. Thermal-driven processes cannot tune salinity for fit-for-purpose quality but are effective at organic and biological species removal. Biological-related processes typically apply bioelectrochemical reactions via microbes and bacteria to drive the removal of ions from the solution. In biological processes, ions are removed from the water solution. The ability to produce fit-for-purpose water has not been explored with biological processes, but they can treat targeted organics and biologicals. Compared to the pressure-driven membrane separation technologies used most in industrial separations, applications of selective separations have increased in recent years and becomes important to address the challenges of technology adaptation to climate change. For examples, the production of biofuel and bio-products to reduce green-house gas emission from fossil fuel and the non-conventional water supply for water-energy nexus have required high energy efficient and cost effective separation technologies. Innovative electrochemical separations can provide transformational impacts in advancing selective separations for highly energy efficient, small capital footprints and low processing cost. It, thus, enables the paradigm-shift of using alternative fuels and water supplies for industrial applications. We will discuss the key process performance metrics, energy consumption and processing rate, of various electrochemical technologies applied in biorefinery, waste to energy and water energy nexus to separate charges species from “dilute” aqueous phase. The ions separation performance demonstrated from various aqueous streams include 1) Inorganic and organic salts removal/capture in lignin valorization. and from bioprocessing streams in biofuel production; 2) volatile fatty acid removal/capture as well as biogas purification from solid waste anaerobic digester for waste to energy; 3) selective desalination of hardness, alkalinity, silica, and ammonia from impaired water for cooling water supply; 4)Capture and delivery for CO2 utilization. Critical issues in process design and material property to achieve electrochemical separation rate and energy efficiency for economic viability will be discussed.
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Lin, Guo, Chenchen Liu, Zhongxiang Bai, Shuning Liu, Mangui Han, Yumin Huang et Xiaobo Liu. « Heat-resistant poly (arylene ether nitriles) separator for high-safety lithium batteries via dual-functional modification ». Journal of Physics : Conference Series 2338, no 1 (1 septembre 2022) : 012031. http://dx.doi.org/10.1088/1742-6596/2338/1/012031.
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Abstract Herein, we report a dual-modified organic-inorganic separator as an alternative to polyolefin commercial separator for lithium metal batteries. This composite separator exhibits high thermal stability properties due to the use of an engineering plastic matrix of poly (arylene ether nitriles) (PEN). The dual hydrophilic modification strategy also allows the separator to have a high ionic conductivity and a low interfacial impedance. With this new separator, lithium-metal batteries have high charge/discharge capacity and high-rate performance. Moreover, Li/Li symmetric cells display long-term stability and phenomenon of suppressing the lithium dendrite in lithium-metal batteries.
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Parkinson, Bruce Alan, John Hoberg, Katie Li-Oakey et Phuoc Duong. « Selective Ion Sieving and Disorder in Membranes Constructed from Two-Dimensional Covalent Organic Frameworks ». ECS Meeting Abstracts MA2022-01, no 47 (7 juillet 2022) : 1987. http://dx.doi.org/10.1149/ma2022-01471987mtgabs.
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Two-dimensional covalent organic frameworks (2D-COFs) have been of increasing interest in the past decade due to their potentially ordered porous structures. One of the most common routes to these polymers relies on Schiff-base chemistry, i.e. the condensation reaction between a carbonyl and an amine. However, the judicious choice of these two building blocks is critical given that many COF forming reactions can lead to an inherent disorder if such a pathway is available. Examples of disorder in 2D-COFs due to both inherent growth mechanisms and reaction pathways will be given and their influence on ion sieving membranes will be discussed. A 2D-COF with negatively charged carboxylated pores, where disorder is minimized, has been shown to be highly charge and size selective for ion conductivity for a series of tetraalkyl ammonium cations. Progress on membranes for desalinization and small ion separations such as Li ion separation from brines using negatively charged, positively charged and zwitterion pores will also be presented.
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Abbasi, Ali, Soraya Hosseini, Anongnat Somwangthanaroj, Ahmad Azmin Mohamad et Soorathep Kheawhom. « Poly(2,6-Dimethyl-1,4-Phenylene Oxide)-Based Hydroxide Exchange Separator Membranes for Zinc–Air Battery ». International Journal of Molecular Sciences 20, no 15 (26 juillet 2019) : 3678. http://dx.doi.org/10.3390/ijms20153678.
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Rechargeable zinc–air batteries are deemed as the most feasible alternative to replace lithium–ion batteries in various applications. Among battery components, separators play a crucial role in the commercial realization of rechargeable zinc–air batteries, especially from the viewpoint of preventing zincate (Zn(OH)42−) ion crossover from the zinc anode to the air cathode. In this study, a new hydroxide exchange membrane for zinc–air batteries was synthesized using poly (2,6-dimethyl-1,4-phenylene oxide) (PPO) as the base polymer. PPO was quaternized using three tertiary amines, including trimethylamine (TMA), 1-methylpyrolidine (MPY), and 1-methylimidazole (MIM), and casted into separator films. The successful synthesis process was confirmed by proton nuclear magnetic resonance and Fourier-transform infrared spectroscopy, while their thermal stability was examined using thermogravimetric analysis. Besides, their water/electrolyte absorption capacity and dimensional change, induced by the electrolyte uptake, were studied. Ionic conductivity of PPO–TMA, PPO–MPY, and PPO–MIM was determined using electrochemical impedance spectroscopy to be 0.17, 0.16, and 0.003 mS/cm, respectively. Zincate crossover evaluation tests revealed very low zincate diffusion coefficient of 1.13 × 10−8, and 0.28 × 10−8 cm2/min for PPO–TMA, and PPO–MPY, respectively. Moreover, galvanostatic discharge performance of the primary batteries assembled using PPO–TMA and PPO–MPY as initial battery tests showed a high specific discharge capacity and specific power of ~800 mAh/gZn and 1000 mWh/gZn, respectively. Low zincate crossover and high discharge capacity of these separator membranes makes them potential materials to be used in zinc–air batteries.
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Shomura, Ryo, Ryota Tamate et Shoichi Matsuda. « Lithium-Ion-Conducting Ceramics-Coated Separator for Stable Operation of Lithium Metal-Based Rechargeable Batteries ». Materials 15, no 1 (3 janvier 2022) : 322. http://dx.doi.org/10.3390/ma15010322.
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Lithium metal anode is regarded as the ultimate negative electrode material due to its high theoretical capacity and low electrochemical potential. However, the significantly high reactivity of Li metal limits the practical application of Li metal batteries. To improve the stability of the interface between Li metal and an electrolyte, a facile and scalable blade coating method was used to cover the commercial polyethylene membrane separator with an inorganic/organic composite solid electrolyte layer containing lithium-ion-conducting ceramic fillers. The coated separator suppressed the interfacial resistance between the Li metal and the electrolyte and consequently prolonged the cycling stability of deposition/dissolution processes in Li/Li symmetric cells. Furthermore, the effect of the coating layer on the discharge/charge cycling performance of lithium-oxygen batteries was investigated.
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Lekakou, C., O. Moudam, F. Markoulidis, T. Andrews, J. F. Watts et G. T. Reed. « Carbon-Based Fibrous EDLC Capacitors and Supercapacitors ». Journal of Nanotechnology 2011 (2011) : 1–8. http://dx.doi.org/10.1155/2011/409382.
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This paper investigates electrochemical double-layer capacitors (EDLCs) including two alternative types of carbon-based fibrous electrodes, a carbon fibre woven fabric (CWF) and a multiwall carbon nanotube (CNT) electrode, as well as hybrid CWF-CNT electrodes. Two types of separator membranes were also considered. An organic gel electrolyte PEO-LiCIO4-EC-THF was used to maintain a high working voltage. The capacitor cells were tested in cyclic voltammetry, charge-discharge, and impedance tests. The best separator was a glass fibre-fine pore filter. The carbon woven fabric electrode and the corresponding supercapacitor exhibited superior performance per unit area, whereas the multiwall carbon nanotube electrode and corresponding supercapacitor demonstrated excellent specific properties. The hybrid CWF-CNT electrodes did not show a combined improved performance due to the lack of carbon nanotube penetration into the carbon fibre fabric.
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Lau, Ying Yin, Tamer Andrea, Philip G. Jessop et J. Hugh Horton. « The effect of switchable additives on colloidal interactions found in oil sands as measured by chemical force spectrometry ». Canadian Journal of Chemistry 94, no 5 (mai 2016) : 482–89. http://dx.doi.org/10.1139/cjc-2015-0464.
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After oil sands separations, settling of clays from aqueous tailings can be promoted by additives such as Ca2+ salts. However, if the liberated water is then recycled, these same additives in the water interfere with bitumen recovery in the separator. Therefore, we have tested CO2-triggered switchable additives to see whether they can switch back and forth between a form that is suitable for the separation stage and a form that promotes tailings ponds settling. CO2-triggered switchable additives can reversibly change water chemistry merely by introduction and removal of CO2, a benign trigger. Here, the effects of CO2-mediated switchable additives on colloidal interactions found in model oil sands were studied by chemical force spectrometry. Self-assembled monolayers of 12-phenyldodecanethiol and 12-mercaptododecanoic acid were used to chemically modify gold-coated atomic force microscope tips. These were subsequently used to study the adhesion force between the modified tips and the minerals silica and mica. The adhesion between the tips and the mineral substrates was studied in aqueous solutions of varying pH and divalent cation concentration and in the presence of cationic switchable additives of varying surfactant potency, both in the presence and in the absence of CO2. In the presence of CO2, the best additive promotes attractive forces, while in the absence of CO2, the forces are repulsive. These results are discussed in the context of the mechanism of colloidal interactions in an oil sands system.
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Wang, Jun, Jing-Ping Ke, Zhen-Yi Wu, Xiao-Na Zhong, Song-Bai Zheng, Yong-Jun Li et Wen-Hua Zhao. « Cationic Covalent Organic Framework as Separator Coating for High-Performance Lithium Selenium Disulfide Batteries ». Coatings 12, no 7 (30 juin 2022) : 931. http://dx.doi.org/10.3390/coatings12070931.
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Selenium disulfide that combines the advantages of S and Se elements is a new material for Li-chalcogen battery cathodes. However, like Li-S batteries, the shuttle effect seriously restricts the performance of Li-SeS2 batteries. In this work, we have synthesized a kind of nitrogen-rich lithophilic covalent organic framework (ATG-DMTZ-COF) as a separator coating material for Li-SeS2 batteries. Here, the N atom in the ATG-DMTZ-COF channel preferentially interacts with the lithium ion in the electrolyte to form N…Li bond, which significantly improves the diffusion coefficient of lithium ions during the charge and discharge. More importantly, we prove that the pore size of ATG-DMTZ-COF will decrease sharply because there is a large amount of TFSI- in the channel, and finally the shuttling of polysulfide and polyselenide is suppressed by the sieving effect. As a consequence, Li-SeS2 batteries using the ATG-DMTZ-COF separator coating show excellent performances with an initial discharge capacity of 1028.7 mAh g−1 at 0.5 C under a SeS2 loading of 2.38 mg cm−2. Furthermore, when the current density is 1C, the specific capacity of 404.7 mAh g−1 can be maintained after 700 cycles.
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Baranowska-Korczyc, Anna, Ewelina Mackiewicz, Katarzyna Ranoszek-Soliwoda, Jaroslaw Grobelny et Grzegorz Celichowski. « Core/Shell Ag/SnO2 Nanowires for Visible Light Photocatalysis ». Catalysts 12, no 1 (28 décembre 2021) : 30. http://dx.doi.org/10.3390/catal12010030.
Texte intégralRésumé :
This study presents core/shell Ag/SnO2 nanowires (Ag/SnO2NWs) as a new photocatalyst for the rapid degradation of organic compounds by the light from the visible range. AgNWs after coating with a SnO2 shell change optical properties and, due to red shift of the absorbance maxima of the longitudinal and transverse surface plasmon resonance (SPR), modes can be excited by the light from the visible light region. Rhodamine B and malachite green were respectively selected as a model organic dye and toxic one that are present in the environment to study the photodegradation process with a novel one-dimensional metal/semiconductor Ag/SnO2NWs photocatalyst. The degradation was investigated by studying time-dependent UV/Vis absorption of the dye solution, which showed a fast degradation process due to the presence of Ag/SnO2NWs photocatalyst. The rhodamine B and malachite green degraded after 90 and 40 min, respectively, under irradiation at the wavelength of 450 nm. The efficient photocatalytic process is attributed to two phenomenon surface plasmon resonance effects of AgNWs, which allowed light absorption from the visible range, and charge separations on the Ag core and SnO2 shell interface of the nanowires which prevents recombination of photogenerated electron-hole pairs. The presented properties of Ag/SnO2NWs can be used for designing efficient and fast photodegradation systems to remove organic pollutants under solar light without applying any external sources of irradiation.
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Scott, T. W., et C. L. Braun. « Picosecond measurements of geminate charge pair recombination in photoionized liquids ». Canadian Journal of Chemistry 63, no 1 (1 janvier 1985) : 228–31. http://dx.doi.org/10.1139/v85-037.
Texte intégralRésumé :
The recombination dynamics of geminate cation–electron pairs in liquid hexane is studied by combining picosecond photoionization and infrared-stimulated charge dissociation measurements. The observed yield of free charge is determined by the product of the charge pair survival probability and the probability for infrared-stimulated charge dissociation. Experimental results are compared with transient solutions of the Smoluchowski equation governing diffusive recombination in a Coulomb well. Reasonable agreement with experiment can be reached by allowing for a radial distribution of initial pair separations. However, the stimulated dissociation yield exhibits a functional dependence on pair separation which complicates the analysis. A simple model of geminate charge pair dissociation by infrared stimulation is presented and its implications for these experiments are discussed.
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Woo, Sang-Hee, Gunhee Lee, Bangwoo Han et Seokhwan Lee. « Development of Dust Collectors to Reduce Brake Wear PM Emissions ». Atmosphere 13, no 7 (15 juillet 2022) : 1121. http://dx.doi.org/10.3390/atmos13071121.
Texte intégralRésumé :
In this study, two different dust collectors, one based on an inertial separator and the other based on an electrostatic precipitator (ESP), were developed in order to reduce brake wear particulate matter (PM) emissions. Additionally, the collection efficiencies for brake wear particles (BWPs) of the inertial separator and the ESP were evaluated according to brake pad type. In the case of the inertial separator, the BWP collection efficiencies for the low-metallic (LM) and non-asbestos organic (NAO) pads were similar, and the cut-off size at 50% collection efficiency (D50) was 2.2 µm. The ESP was designed without an additional electrostatic charging device because naturally induced electrostatic charging occurred due to the friction between the brake disc and pad. The BWP collection efficiency of the ESP was higher for NAO pad than for LM pad because the BWPs generated from the NAO pad contained a relatively low iron (Fe) component compared to that of the LM pad, thereby generating more frictional electricity. The maximum ESP collection efficiencies of the BWPs generated from the LM and NAO pads were determined to be 60% and 75%, respectively, and the remaining BWPs that were not collected were presumed to be particles that were not frictionally charged.
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Latchem, Emma Jane, Thomas Kress, Clare P. Grey, Peter A. A. Klusener, Ramachandran Vasant Kumar et Alexander C. Forse. « Investigating Transport through Separator Membranes in Aqueous Organic Redox Flow Batteries Using NMR Spectroscopy ». ECS Meeting Abstracts MA2022-01, no 48 (7 juillet 2022) : 1995. http://dx.doi.org/10.1149/ma2022-01481995mtgabs.
Texte intégralRésumé :
Electricity and heat generation contribute 25% of greenhouse gas emissions globally.1 Redox flow batteries (RFBs) are prospective devices for long-duration energy storage, which is required to integrate more renewable energy sources onto the electricity grid.2 RFBs have a modular design with decoupled power and energy ratings, allowing them to be scaled to suit grid-level energy storage requirements. The development of aqueous organic redox flow batteries (AORFBs), such as quinone-based systems, is gaining momentum because they are potentially cheaper, safer and more sustainable than vanadium-based RFBs.3-5 However, the crossover of redox-active species through the separator membrane can lead to irreversible capacity fade, limiting their lifetime and economic viability.6 It has previously been demonstrated that in situ spectroscopic techniques are powerful tools for determining reaction mechanisms in redox flow batteries.5,7 Here, we explore how solution-state in situ nuclear magnetic resonance (NMR) spectroscopy and solid-state NMR spectroscopy can be used to study the crossover of electrolytes in AORFBs. We demonstrate that in situ solution NMR spectroscopy can be used to characterise transport in operating AORFBs with high temporal resolution and minimal system disturbance. This method can therefore be applied to investigate how crossover is governed by structure-property relationships and the charging protocols used. Furthermore, polymer-electrolyte interactions within the membrane can be probed using complementary solid-state NMR studies. Together, these fundamental studies will ultimately advance our understanding of electrolyte crossover, so that improved separator membranes can be developed. References: Climate Change 2014: Synthesis Report; Pachauri, R. K., Mayer, L., Intergovernmental Panel on Climate Change, Eds.; Intergovernmental Panel on Climate Change: Geneva, Switzerland, 2015. Rugolo, J.; Aziz, M. J., Energy Environ. Sci. 5 7151-7160 (2012). Lin, K.; Chen, Q.; Gerhardt, M. R.; Tong, L.; Kim, S. B.; Eisenach, L.; Valle, A. W.; Hardee, D.; Gordon, R. G.; Aziz, M. J.; Marshak, M. P., Science 349, 1529-1532 (2015). Kwabi, D. G.; Lin, K.; Ji, Y.; Kerr, E. F.; Goulet, M.-A.; De Porcellinis, D.; Tabor, D. P.; Pollack, D. A.; Aspuru-Guzik, A.; Gordon, R. G.; Aziz, M. J., Joule 2, 1894–1906 (2018). Zhao, E. W.; Liu, T.; Jónsson, E.; Lee, J.; Temprano, I.; Jethwa, R. B.; Wang, A.; Smith, H.; Carretero-González, J.; Song, Q.; Grey, C. P., Nature 579, 224–228 (2020). Tan, R.; Wang, A.; Malpass-Evans, R.; Williams, R.; Zhao, E. W.; Liu, T.; Ye, C.; Zhou, X.; Darwich, B. P.; Fan, Z.; Turcani, L.; Jackson, E.; Chen, L.; Chong, S. Y.; Li, T.; Jelfs, K. E.; Cooper, A. I.; Brandon, N. P.; Grey, C. P.; McKeown, N. B.; Song, Q., Mater. 19, 195–202 (2020). Zhao, E. W.; Jónsson, E.; Jethwa, R. B.; Hey, D.; Lyu, D.; Brookfield, A.; Klusener, P. A. A.; Collison, D.; Grey, C. P., Am. Chem. Soc. 143, 1885–1895 (2021).
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Na, Ruiqi, Xingrui Zhang, Pengfei Huo, Yinlong Du, Guanze Huo, Kai Zhu et Guibin Wang. « High performance disulfonated poly(arylene ether sulfone)/poly(ethylene oxide) composite membrane used as a novel separator for supercapacitor with neutral electrolyte and activated carbon electrodes ». High Performance Polymers 29, no 8 (31 août 2016) : 984–93. http://dx.doi.org/10.1177/0954008316666386.
Texte intégralRésumé :
High performance disulfonated poly(arylene ether sulfone)/poly(ethylene oxide) (SPAES/PEO) composite membranes were prepared by a simple method such as a novel separator saturated by the lithium sulfate (Li2SO4) aqueous electrolyte for application in supercapacitors (SCs). As prepared composite membranes exhibit excellent mechanical properties and thermal stabilities, which are beneficial for the safety in potential applications, meanwhile, the addition of PEO on membrane also enhanced the affinity with electrolyte and the ion conduction for lithium salts. In addition, the SC cell was fabricated with optimized SPAES/PEO composite membrane and activated carbon electrodes with Li2SO4 aqueous electrolyte. The obtained SC with the SPAES/PEO separator revealed a specific capacitance of 142.5 F g−1 at a current density of 0.1 A g−1. Furthermore, the energy density of the SC was promoted to 19.04 Wh kg−1 due to the wide working voltage range of the neutral electrolyte, and the SC exhibited an excellent coulombic efficiency of almost 99% and nearly 100% cycling retention after 5000 galvanostatic charge/discharge cycles. All of these results indicated that SPAES/PEO composite membrane is suitable as a novel separator for SC.
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Deng, Fengjun, Yuhang Zhang et Yingjian Yu. « Conductive Metal–Organic Frameworks for Rechargeable Lithium Batteries ». Batteries 9, no 2 (3 février 2023) : 109. http://dx.doi.org/10.3390/batteries9020109.
Texte intégralRésumé :
Currently, rechargeable lithium batteries are representative of high-energy-density battery systems. Nevertheless, the development of rechargeable lithium batteries is confined by numerous problems, such as anode volume expansion, dendrite growth of lithium metal, separator interface compatibility, and instability of cathode interface, leading to capacity fade and performance degradation of batteries. Since the 21st century, metal–organic frameworks (MOFs) have attracted much attention in energy-related applications owing to their ideal specific surface areas, adjustable pore structures, and targeted design functions. The insulating characteristics of traditional MOFs restrict their application in the field of electrochemistry energy storage. Recently, some teams have broken this bottleneck through the design and synthesis of electron- and proton-conductive MOFs (c-MOFs), indicating excellent charge transport properties, while the chemical and structural advantages of MOFs are still maintained. In this review, we profile the utilization of c-MOFs in several rechargeable lithium batteries such as lithium-ion batteries, Li–S batteries, and Li–air batteries. The preparation methods, conductive mechanisms, experimental and theoretical research of c-MOFs are systematically elucidated and summarized. Finally, in the field of electrochemical energy storage and conversion, challenges and opportunities can coexist.
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Salehen, P. M. W., H. Razali, K. Sopian, T. K. Lee et M. S. Su'ait. « Evaluation of Charge-Discharge Characteristic of Lithium Cobalt Nickel Manganese Oxide for High-Energy Density Lithium-Ion Batte ». Journal of the Society of Automotive Engineers Malaysia 1, no 3 (28 avril 2021) : 183–90. http://dx.doi.org/10.56381/jsaem.v1i3.66.
Texte intégralRésumé :
The development of suitable cathode materials of lithium ion batteries (LIBs) for energy storage towards improving the performance of LIBs in order to meet the increasing demand globally is one of the challenges. This paper investigates the charge-discharge characteristic for lithium ion batteries developed focusing on cathode materials of LiNiCoMnO2 (NCM) – layered structured material with lithium anode. It also discusses the characteristic features of charge-discharge profile, optimized charge-end voltage as well as discharged limit voltage with a constant current C-rate with 0.1C, 0.3C and 0.5C. The coin cells were fabricated in a glove box full of argon gas using those cathode and anode with separator and organic electrolyte (1M LiPF6, EC: DEC 1:1). The performance of charge-discharge test was conducted with NEWARE tester equipment BTS 3000. This includes obtaining experimental data charge- discharge and power capacity to improve the performance of battery. Thus it is reported that charge-discharge characteristic of LNCM material is important to be analysed for LIBs. The parameter attained is vital and necessary enhancement work for the resolution of optimization BMS simulation.
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Jachalke, Sven, Erik Mehner, Hartmut Stöcker, Tilmann Leisegang et Dirk Meyer. « Evaluation of structural phase transition by pyroelectric measurements ». Acta Crystallographica Section A Foundations and Advances 70, a1 (5 août 2014) : C60. http://dx.doi.org/10.1107/s2053273314099392.
Texte intégralRésumé :
In non-centrosymmetric crystalline matter, marked by the pyroelectric effect, a change in temperature alters the materials spontaneous polarization, which further changes the charge density on the material's surface. This results in a current flow trough an external circuit, which differs drastically at the boundary between two crystallographic phases. Therefore, pyroelectric materials offer a great potential of low-temperature waste heat recovery by utilizing e.g. the Olsen-Cylce to convert residual heat into electric energy. A previous characterization is necessary to determine the operating conditions of the active material. This work presents a method to evaluate temperature depended pyroelectric properties, especially the pyroelectric coefficient p and the phase transition temperture TC, with the help of a computer controlled thermal/electrical stimulation and a simultaneously recording of the electrical response of the material. Here, the analysis with the Sharp-Garn-method [1] separates the pyroelectric from eventually disturbing non-pyroelectric signal, enabling the characterization of p and TC over a broad spectrum of materials, ranging from inorganic single crystals and ceramics to organic polymers.
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Salmerón-Valverde, Amparo, Sylvain Bernès et Juan Gerardo Robles-Martínez. « Structure and degree of charge transfer of two polymorphs of a 1:1 molecular complex : [2,2′-bis-1,3-dithiole][9-dicyanomethylene-4,5,7-trinitrofluorene-2-carboxylic acid methyl ester] (TTF-MeDC2TNF) ». Acta Crystallographica Section B Structural Science 59, no 4 (25 juillet 2003) : 505–11. http://dx.doi.org/10.1107/s0108768103011893.
Texte intégralRésumé :
A new organic charge-transfer complex, C18H7N5O8·C6H4S4, has been prepared using TTF (tetrathiafulvalene) as a donor (D) and MeDC2TNF (9-dicyanomethylene-4,5,7-trinitro-fluorene-2-carboxylic acid methyl ester) as an acceptor (A). Two monoclinic polymorphs of the 1:1 salt were crystallized and characterized by X-ray diffraction. Form α crystallizes in space group P21/n with Z′ = 1, while form β crystallizes in space group C2/c with Z′ = 1\over 2 and the MeDC2TNF moiety disordered across a twofold axis. Both phases have mixed-stack crystal packings, which are characteristic of semiconducting one-dimensional organic complexes. However, the observed crystal packings are significantly different, with a single D...A interlayer separation of 3.452 Å for the disordered β polymorph and interlayer separations of 3.378 and 3.483 Å in the case of the ordered α form. These variations are reflected in the degree of charge transfer, δ, which was estimated on the basis of the b 2u stretching-mode frequency shift observed in the IR spectra for the cyano groups of the MeDC2TNF radical anion. The fact that the charge transfer is more efficient for α-(TTF-MeDC2TNF) than for β-(TTF-MeDC2TNF) (δ = 0.35 and 0.31, respectively) is consistent with the structural features observed for each crystalline form.
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Ghazali, Nazlee Faisal, et Lim Ki Min. « Mass Transport Models in Organic Solvent Nanofiltration : A Review ». Journal of Advanced Research in Fluid Mechanics and Thermal Sciences 76, no 3 (29 octobre 2020) : 126–38. http://dx.doi.org/10.37934/arfmts.76.3.126138.
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Membrane technology has been gradually used as an alternative to the conventional separation and purification method in various industries. In recent years, solvent-stable nanofiltration or organic solvent nanofiltration has becoming practicable through the development of solvent-stable commercial polymeric membranes. Organic solvent nanofiltration has a great potential to replace the conventional energy-demanding process such as distillation due to its ability of separating organic solvents and solutes on a molecular level without phase change and operation at relatively mild temperature. Predicting the performance of such membrane separations is crucial in the process design. Important performance indicator such as the permeate flux and the rejections are strongly related to the fluid dynamics, mass transfer and solute-solvent-membrane interactions. The aim of this paper is to review and assess the transport models of solute and solvent transport relevant to organic solvent nanofiltration. The link between concentration polarization and the hydrodynamics in various configurations are discussed. The effects of process variables on membrane performance and solute-solvent membrane interactions are also reviewed.
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M. R. Gonçalves, Helena, Susana A. F. Neves, Abel Duarte et Verónica de Zea Bermudez. « Nanofluid Based on Carbon Dots Functionalized with Ionic Liquids for Energy Applications ». Energies 13, no 3 (3 février 2020) : 649. http://dx.doi.org/10.3390/en13030649.
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The development of materials that can help overcome the current limitations in energy storage and consumption is a pressing need. Recently, we developed non-Newtonian nanofluids based on non-toxic, carbon nanoparticles (NPs), carbon dots (Cdots) functionalized with ionic liquids. Here, we wanted to prove that these new nanofluids are, not only interesting as possible electrolytes, but also as new organic/inorganic hybrid separators. As such, we developed an entrapment method using poly(vinyl alcohol) (PVA). Indeed, the highly conductive Cdots were successfully retained inside the membrane even upon the application of several wetting/drying cycles. Moreover, the morphological characteristics did not change upon wetting/drying cycles and remained constant for more than four months. These nanofluids could be an interesting approach to tackle some of the current problems in the fields of solid-state batteries, and energy storage, among others.
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Haeri, Blaffert, Schöffmann, Blech, Hartl, Garidel et Hinderberger. « Concentration Effects in the Interaction of Monoclonal Antibodies (mAbs) with their Immediate Environment Characterized by EPR Spectroscopy ». Molecules 24, no 14 (10 juillet 2019) : 2528. http://dx.doi.org/10.3390/molecules24142528.
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Monoclonal antibodies (mAbs) are often needed and applied in high concentration solutions, >100 mg/mL. Due to close intermolecular distances between mAbs at high concentrations (~10-20 nm at 200 mg/mL), intermolecular interactions between mAbs and mAbs and solvent/co-solute molecules become non-negligible. Here, EPR spectroscopy is used to study the high-concentration solutions of mAbs and their effect on co-solvated small molecules, using EPR “spin probing” assay in aqueous and buffered solutions. Such, information regarding the surrounding environments of mAbs at high concentrations were obtained and comparisons between EPR-obtained micro-viscosities (rotational correlation times) and macroscopic viscosities measured by rheology were possible. In comparison with highly viscous systems like glycerol-water mixtures, it was found that up to concentrations of 50 mg/mL, the mAb-spin probe systems have similar trends in their macro- (rheology) and micro-viscosities (EPR), whereas at very high concentrations they deviate strongly. The charged spin probes sense an almost unchanged aqueous solution even at very high concentrations, which in turn indicates the existence of large solvent regions that despite their proximity to large mAbs essentially offer pure water reservoirs for co-solvated charged molecules. In contrast, in buffered solutions, amphiphilic spin probes like TEMPO interact with the mAb network, due to slight charge screening. The application of EPR spectroscopy in the present work has enabled us to observe and discriminate between electrostatic and hydrophobic kinds of interactions and depict the potential underlying mechanisms of network formation at high concentrations of mAbs. These findings could be of importance as well for the development of liquid-liquid phase separations often observed in highly concentrated protein solutions.
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Sheriff, Falana Aziza, et Styliani Consta. « Charge-induced instabilities of droplets containing macromolecular complexes ». Canadian Journal of Chemistry 93, no 2 (février 2015) : 173–80. http://dx.doi.org/10.1139/cjc-2014-0299.
Texte intégralRésumé :
Solvated macromolecular complexes are ubiquitous in nature, notably in biological systems containing proteins and nucleic acids. Studies of the interactions within a macromolecular complex and between the complex and the solvent in droplet environments are critical for understanding the stability of macromolecular complexes in electrospray ionization (ESI) and nanofluidic experiments. In this study, two distinct cases of macromolecular complexes in aqueous nanodrops are examined by using molecular dynamics simulations: (i) a pair of sodiated poly(ethylene) glycol (PEG) macroions and (ii) a double-stranded DNA (dsDNA). PEG represents a case in which the surface energy of the aqueous droplet is larger than the solvent–macromolecule energy. Conversely, in a droplet solvating dsDNA, the solvent–macromolecule interaction energy overcomes the solvent interaction energy. We report that charge-induced instabilities previously identified for single macroions also appear in the case of complexes, but with a higher level of complexity. In the case of a pair of PEG macroions, we found that their conformations on the surface of a droplet “sense” each other. The charged PEGs are each released from a droplet at different times through contiguous extrusion or drying-out mechanisms. In the case of the DNA, the charge-induced instability manifests as a spine droplet morphology. Narrow regions of the spines promote break down of the hydrogen bonds that hold the dsDNA together. The dsDNA separates into two single strands as it is increasingly exposed to vacuum. These findings elucidate charge-induced instabilities of macromolecular complexes in droplets, which are critical intermediates in ESI and nanofluidic experiments.
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Ohnishi, Yu, Kentaro Yamamoto et Kazuo Takatsuka. « Suppression of Charge Recombination by Auxiliary Atoms in Photoinduced Charge Separation Dynamics with Mn Oxides : A Theoretical Study ». Molecules 27, no 3 (24 janvier 2022) : 755. http://dx.doi.org/10.3390/molecules27030755.
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Charge separation is one of the most crucial processes in photochemical dynamics of energy conversion, widely observed ranging from water splitting in photosystem II (PSII) of plants to photoinduced oxidation reduction processes. Several basic principles, with respect to charge separation, are known, each of which suffers inherent charge recombination channels that suppress the separation efficiency. We found a charge separation mechanism in the photoinduced excited-state proton transfer dynamics from Mn oxides to organic acceptors. This mechanism is referred to as coupled proton and electron wave-packet transfer (CPEWT), which is essentially a synchronous transfer of electron wave-packets and protons through mutually different spatial channels to separated destinations passing through nonadiabatic regions, such as conical intersections, and avoided crossings. CPEWT also applies to collision-induced ground-state water splitting dynamics catalyzed by Mn4CaO5 cluster. For the present photoinduced charge separation dynamics by Mn oxides, we identified a dynamical mechanism of charge recombination. It takes place by passing across nonadiabatic regions, which are different from those for charge separations and lead to the excited states of the initial state before photoabsorption. This article is an overview of our work on photoinduced charge separation and associated charge recombination with an additional study. After reviewing the basic mechanisms of charge separation and recombination, we herein studied substituent effects on the suppression of such charge recombination by doping auxiliary atoms. Our illustrative systems are X–Mn(OH)2 tied to N-methylformamidine, with X=OH, Be(OH)3, Mg(OH)3, Ca(OH)3, Sr(OH)3 along with Al(OH)4 and Zn(OH)3. We found that the competence of suppression of charge recombination depends significantly on the substituents. The present study should serve as a useful guiding principle in designing the relevant photocatalysts.
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Kasem, Kasem K., Sara Menges et Stephenie Jones. « Photoelectrochemical studies on poly[1-(2-aminophenyl)pyrrole] — Creation of a photoactive inorganic–organic semiconductor interface (IOI) ». Canadian Journal of Chemistry 87, no 8 (août 2009) : 1109–16. http://dx.doi.org/10.1139/v09-079.
Texte intégralRésumé :
The compound 2-APPy [1-(2-aminophenyl)pyrrole] as an organic phase in an inorganic–organic semiconductor interface (IOI) assembly was the subject of photoelectrochemical studies in aqueous solutions. Results show that thin films of poly(2-APPy) can be prepared using oxidative electropolymerization. Furthermore, absorption spectroscopic studies indicate that the protonated 2-APPy polymer’s ionization potential (IP) is 4.7 eV, the electron affinity (EA) is 1.90 eV, and a gap of 2.80 eV separates the higher occupied molecular orbital’s (HOMO) and lower unoccupied molecular orbital’s (LUMO) energy levels of this polymer. Impedance measurements under illumination show an increase in the film charge capacitance compared with those measured under darkened conditions. The behavior of the poly(2-APPy) film as a host for redox-active dopants was also explored. The results show that the film did not alter the redox potentials of a large dopant such as PMo12O403–. The photoactivities of the IOI assemblies consisting of 2-APPy and nanoparticles of ZnO, and of Fe2O3 were investigated using fluorescence emissions. Results show that the fluorescence emissions generated by 2-APPy were quenched by 5% and 55% on ZnO and on Fe2O3, respectively. The charge injection rate constants, kct, at the inorganic metal oxide–2-APPy interface, were calculated.
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George, Thomas Young, Emily F. Kerr, Naphtal O. Haya, Roy G. Gordon et Michael J. Aziz. « Size and Charge Effects on Organic Flow Battery Crossover Evaluated By Quinone Permeabilities through Nafion ». ECS Meeting Abstracts MA2022-01, no 3 (7 juillet 2022) : 486. http://dx.doi.org/10.1149/ma2022-013486mtgabs.
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Organic and metalorganic reactants have become promising for long-lifetime flow batteries. Synthetic chemistry unlocks a wide design space to tailor reactant redox potential, solubility, chemical and electrochemical stability, redox kinetics, and transport properties. Minimizing the crossover of reactants through the membrane or separator is one crucial design goal. To that end, this work contributes a systematic evaluation of size- and charge-based effects on small molecule permeability through Nafion. These results inform the design of flow battery electrolytes that improve the transport selectivity of ion exchange membranes. Some recent flow battery designs have included crossover suppression strategies based on size and charge of reactants. One option is to leverage size-exclusion, for example by tethering redox-active moieties to polymer backbones,1,2 or by oligomerizing redox-active monomers.3-5 A charge-based strategy has been employed to decrease viologen crossover: sulfonate6 or phosphonate7 solubilizing groups were attached to the redox active core and paired with a cation exchange membrane, reducing crossover compared to previous iterations of this chemistry. Crossover rates of some organic-based flow battery molecules have been estimated to be very low, but other considerations must be balanced for designing viable battery technology. For example, electrolyte cost and solubility may be in direct tension with a crossover suppression strategy based on increasing redox mediator size.8 Untangling the effects of different membrane-molecule selectivity mechanisms is a valuable step on the path to advancing redox active molecule design. This work evaluates a set of quinones in which size is varied by the number of aromatic rings (e.g. hydroquinone, anthraquinone) and charge number is varied almost independently through sulfonation. Each sulfonate moiety contributes a -1 charge, increasing the magnitude of the molecule charge number with the same sign as the fixed charges in Nafion. Effective size of solvated species is accessed through rotating disk electrode voltammetry: Stokes radii are calculated from measured diffusion coefficients. We found over an order of magnitude permeability reduction per sulfonate, emphasizing the importance of charge-based exclusion for ion exchange membranes. In comparison, size-exclusion effects are less impactful. For example, the Stokes radius of anthraquinone 2,6-disulfonate (AQDS) is twice that of hydroquinone 2,5-disulfonate but their permeabilities fall within the same order of magnitude. 1. T. Hagemann, J. Winsberg, M. Grube, I. Nischang, T. Janoschka, N. Martin, M. D. Hager, and U. S. Schubert, Journal of Power Sources, 378, 546 (2018). 2. T. Janoschka, N. Martin, U. Martin, C. Friebe, S. Morgenstern, H. Hiller, M. D. Hager, and U. S. Schubert, Nature, 527, 78 (2015). 3. M. J. Baran, M. N. Braten, E. C. Montoto, Z. T. Gossage, L. Ma, E. Chenard, J. S. Moore, J. Rodrıguez-Lopez, and B. A. Helms, Chemistry of Materials, 30, 3861 (2018). 4. K. H. Hendriks, S. G. Robinson, M. N. Braten, C. S. Sevov, B. A. Helms, M. S. Sigman, S. D. Minteer, and M. S. Sanford, ACS Central Science, 4, 189 (2018). 5. S. E. Doris, A. L. Ward, A. Baskin, P. D. Frischmann, N. Gavvalapalli, E. Chenard, C. S. Sevov, D. Prendergast, J. S. Moore, and B. A. Helms, Angewandte Chemie, 129, 1617 (2017). 6. C. Debruler, B. Hu, J. Moss, J. Luo, and T. L. Liu, ACS Energy Letters, 3, 663, (2018). 7. S. Jin, E. M. Fell, L. Vina-Lopez, Y. Jing, P. W. Michalak, R. G. Gordon, and M. J. Aziz, Advanced Energy Materials, 10, (2020). 8. M. L. Perry, J. D. Saraidaridis, and R. M. Darling, Current Opinion in Electrochemistry, 21, 311 (2020).
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Yuan, Deling, Mengting Sun, Shoufeng Tang, Yating Zhang, Zetao Wang, Jinbang Qi, Yandi Rao et Qingrui Zhang. « All-solid-state BiVO4/ZnIn2S4 Z-scheme composite with efficient charge separations for improved visible light photocatalytic organics degradation ». Chinese Chemical Letters 31, no 2 (février 2020) : 547–50. http://dx.doi.org/10.1016/j.cclet.2019.09.051.
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Cottet, Herv�, et Jean Philippe Biron. « Charge- and Size-Based Separations of Polyelectrolytes by Heart-Cutting Two-Dimensional Capillary Electrophoresis ». Macromolecular Chemistry and Physics 206, no 6 (18 mars 2005) : 628–34. http://dx.doi.org/10.1002/macp.200400538.
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Nowacki, Krzysztof, Maciej Galiński et Izabela Stępniak. « SYNTHESIS AND CHARACTERIZATION OF CHITOSAN/SODIUM ALGINATE BLEND MEMBRANE FOR APPLICATION IN AN ELECTROCHEMICAL CAPACITOR ». Progress on Chemistry and Application of Chitin and its Derivatives XXV (30 septembre 2020) : 174–91. http://dx.doi.org/10.15259/pcacd.25.014.
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In this work, we report a stepwise formation method of a chitosan/sodium alginate polyelectrolyte complex (CS/SA PEC) membrane. The proposed method aiming at the utilization of the ultrasonic treatment of chitosan and sodium alginate solution allowed us to obtain a highly homogeneous hybrid membrane for electrochemical usage. The CS/SA PEC membrane saturated in a 2 M Li2SO4 aqueous solution was used in electrochemical double layer capacitor (EDLC) cell to study its applicability as quasi-solid electrolyte. Electrochemical characteristic of EDLC cells was determined by electrochemical impedance spectroscopy, cyclic voltammetry and galvanostatic charge/discharge methods. The results show that the EDLC cell with CS/SA PEC quasi-solid electrolyte exhibit a comparable specific capacitance (102 F g-1 for 0–0.8 V) to CS reference (100 F g-1 for 0–0.8 V) and commercial separator (99 F g-1 for 0–0.8 V) cells. Thus, the CS/SA PEC membrane can be considered as an alternative modification for chitosanbased materials of electrochemical purpose.
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Ramm, Patrice, Carsten Jost, Elisabeth Neitmann, Ulrich Sohling, Oliver Menhorn, Karl Weinberger, Jan Mumme et Bernd Linke. « Magnetic Biofilm Carriers : The Use of Novel Magnetic Foam Glass Particles in Anaerobic Digestion of Sugar Beet Silage ». Journal of Renewable Energy 2014 (2014) : 1–10. http://dx.doi.org/10.1155/2014/208718.
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The use of recently developed magnetic foam glass particles for immobilization of microbial biomass was tested. The effect of the particles was illustrated at the production of biogas from sugar beet silage as the sole substrate. Lab-scale fermentation experiments were conducted using a mesophilic completely stirred tank reactor and a magnetic separator. Microscopic analysis revealed biofilm coverage of 50–60% on the surface of the particles within 110 days. It was possible to recover 76.3% of the particles from fermentation effluent by means of a separation procedure based on magnetic forces. Comparing a particle charged reactor with a control reactor showed a small performance gain. The methane rate was increased from1.18±0.09to1.25±0.06 L L−1 d−1and the methane yield was increased from0.302±0.029to0.318±0.022 L g−1(volatile solids) at an organic loading rate of3.93±0.22 g L−1 d−1(volatile solids). Maximum methane rates of 1.42 L L−1d−1at an organic loading rate of 4.60 g (volatile solids) L−1 d−1(reactor including magnetic particles) and 1.34 L L−1 d−1at 3.73 g L−1 d−1(control reactor) were achieved. Based on the results, it can be concluded that the use of magnetic particles could be an attractive option for the optimization of biogas production.
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Zhu, Jun-Jie, Luis Martinez-Soria et Pedro Gomez-Romero. « Coherent Integration of Organic Gel Polymer Electrolyte and Ambipolar Polyoxometalate Hybrid Nanocomposite Electrode in a Compact High-Performance Supercapacitor ». Nanomaterials 12, no 3 (1 février 2022) : 514. http://dx.doi.org/10.3390/nano12030514.
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We report a gel polymer electrolyte (GPE) supercapacitor concept with improved pathways for ion transport, thanks to a facile creation of a coherent continuous distribution of the electrolyte throughout the electrode. Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) was chosen as the polymer framework for organic electrolytes. A permeating distribution of the GPE into the electrodes, acting both as integrated electrolyte and binder, as well as thin separator, promotes ion diffusion and increases the active electrode–electrolyte interface, which leads to improvements both in capacitance and rate capability. An activation process induced during the first charge–discharge cycles was detected, after which, the charge transfer resistance and Warburg impedance decrease. We found that a GPE thickness of 12 μm led to optimal capacitance and rate capability. A novel hybrid nanocomposite material, formed by the tetraethylammonium salt of the 1 nm-sized phosphomolybdate cluster and activated carbon (AC/TEAPMo12), was shown to improve its capacitive performance with this gel electrolyte arrangement. Due to the homogeneous dispersion of PMo12 clusters, its energy storage process is non-diffusion-controlled. In the symmetric capacitors, the hybrid nanocomposite material can perform redox reactions in both the positive and the negative electrodes in an ambipolar mode. The volumetric capacitance of a symmetric supercapacitor made with the hybrid electrodes increased by 40% compared to a cell with parent AC electrodes. Due to the synergy between permeating GPE and the hybrid electrodes, the GPE hybrid symmetric capacitor delivers three times more energy density at higher power densities and equivalent cycle stability compared with conventional AC symmetric capacitors.
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Buncel, Erwin, Sam-Rok Keum, Srinivasan Rajagopal, Eric Kiepek et Robin A. Cox. « Wallach rearrangement of azoxypyridines and azoxypyridine N-oxides — Charge distributions and dramatic reactivity differences ». Canadian Journal of Chemistry 86, no 4 (1 avril 2008) : 298–304. http://dx.doi.org/10.1139/v08-016.
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Extension of our studies of the generic Wallach rearrangement (of azoxybenzene to 4-hydroxyazobenzene) to the heteroaromatic series (azoxypyridines and axoxypyridine N-oxides) has revealed some dramatic reactivity differences, particularly for the α and β compounds. We have studied the 3-isomers and the 4-isomers in each series, each with α and β forms, eight compounds in all, in the 100 wt% sulfuric acid region of acidity. In those cases in which a product could be observed, the α and β isomers both give the same one, the corresponding 4′-hydroxyazo compounds. All the compounds react much more slowly than does azoxybenzene itself, presumably because of the extra positive charge present in the substrates, but the β isomers have half-lives of seconds and the α isomers half-lives of hundreds of hours in the 100 wt% H2SO4 acidity region. The α compounds have measurable pKBH+ values, but the β compounds do not, exhibiting only a medium effect in the acidity region in which the α compounds protonate. This means that for the β compounds, the protonated intermediates must be much less stable and the postulated reaction intermediates must be much more stable than for the α compounds. To clarify this, we have obtained Mulliken charge distributions for the various species concerned, calculating the charge carried by each half of the molecule, larger charge separations being taken to indicate lesser stability. As far as we can establish, this is the first time that this technique has been used to indicate the stabilities of carbocationic species.Key words: azoxypyridines, azoxypyridine N-oxides, Wallach rearrangement, excess acidity, basicities, theoretical calculations, charge distributions, reactivities.
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Colburn, Andrew, Ronald J. Vogler, Aum Patel, Mariah Bezold, John Craven, Chunqing Liu et Dibakar Bhattacharyya. « Composite Membranes Derived from Cellulose and Lignin Sulfonate for Selective Separations and Antifouling Aspects ». Nanomaterials 9, no 6 (7 juin 2019) : 867. http://dx.doi.org/10.3390/nano9060867.
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Cellulose-based membrane materials allow for separations in both aqueous solutions and organic solvents. The addition of nanocomposites into cellulose structure is facilitated through steric interaction and strong hydrogen bonding with the hydroxy groups present within cellulose. An ionic liquid, 1-ethyl-3-methylimidazolium acetate, was used as a solvent for microcrystalline cellulose to incorporate graphene oxide quantum dots into cellulose membranes. In this work, other composite materials such as, iron oxide nanoparticles, polyacrylic acid, and lignin sulfonate have all been uniformly incorporated into cellulose membranes utilizing ionic liquid cosolvents. Integration of iron into cellulose membranes resulted in high selectivity (>99%) of neutral red and methylene blue model dyes separation over salts with a high permeability of 17 LMH/bar. With non-aqueous (alcohol) solvent, iron–cellulose composite membranes become less selective and more permeable, suggesting the interaction of iron ions cellulose OH groups plays a major role in pore structure. Polyacrylic acid was integrated into cellulose membranes to add pH responsive behavior and capacity for metal ion capture. Calcium capture of 55 mg Ca2+/g membrane was observed for PAA-cellulose membranes. Lignin sulfonate was also incorporated into cellulose membranes to add strong negative charge and a steric barrier to enhance antifouling behavior. Lignin sulfonate was also functionalized on the commercial DOW NF270 nanofiltration membranes via esterification of hydroxy groups with carboxyl group present on the membrane surface. Antifouling behavior was observed for both lignin-cellulose composite and commercial membranes functionalized with lignin. Up to 90% recovery of water flux after repeated cycles of fouling was observed for both types of lignin functionalized membranes while flux recovery of up to 60% was observed for unmodified membranes.
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Rahman, Ataur, et Kyaw Myo Aung. « Development of solar supercapacitor by utilizing organic polymer and metal oxides for subsystem of EV ». Materials Research Express 8, no 12 (1 décembre 2021) : 125301. http://dx.doi.org/10.1088/2053-1591/ac3ce9.
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Abstract The limitations of the electric vehicles are weight, size, range, charging time and high price tag. Thus, development of a renewable energy-boosting system for EVs is significant. This paper proposes the materials and control system for development of the automotive body panels which are capable to generate electrical energy from solar energy and store the energy not only as structural capacitor but also as solar panel. A solar supercapacitor prototype is developed by utilizing Carbon Fiber Reinforced Polymer, nano Zinc Oxide and Copper Oxide fillers as the positive and negative electrodes and a dielectric layer sandwiched between the electrodes. Different weight percentage compositions of nano CuO/ZnO filled epoxy reinforced Carbon Fiber and different combinations of separators are investigated experimentally. Samples with higher nanoparticle composition can boost both the energy generation and storage performance. Simulation study is conducted on solar supercapacitor concept which is hybrid energy storage system, modelled as the supplementary renewable energy source of electric vehicle. Experiment data from the laboratory scale organic solar supercapacitor are considered as input reference data to design solar supercapacitor HESS in Simulink to generate electricity from solar energy and provide storage. The solar supercapacitor can be considered as the roof panel of EV and simulated at different solar irradiance (200 ∼ 1000 W m−2) and different load conditions (200 ∼ 500 W) to reflect the practical conditions. The test results of SSC show potential of energy conversion efficiency (η ec) 17.78%, open-circuit voltage (Voc) 0.79 mV, current density (Jsc) 222.22 A m−2, capacitance (C) 11.17 μF cm−2, energy density (Ed) 120 Wh kg−1 and power density (Pd) 29 kW kg−1. Based on Simulink results, fully charged solar supercapacitor system with solar irradiance of 1000 W m−2 can provide power of 2.3 kWh (18.24 km extra range every hour). Therefore, the system can provide extra 4.56% of conventional EV’s power and range per hour. Solar supercapacitor system integrated with EV battery has the potential to reduce battery size by 10%, weight 7.5%.
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Taer, Erman, Arnold Riccahd G, Apriwandi et Rika Taslim. « Effect of N2 carbonization temperature on porous activated carbon derived from jicama (Pachyrhizus erosus L.) peel as electrode material for supercapacitor ». Journal of Physics : Conference Series 2193, no 1 (1 février 2022) : 012016. http://dx.doi.org/10.1088/1742-6596/2193/1/012016.
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Abstract This study presents the different effects of nitrogen carbonization temperature of porous carbon as electrode material based for supercapacitor applications. The precursor origin material as a carbon source is focused on the bio-waste of jicama peel. The precursor is directly chemically activated ZnCl2 followed by high-temperature pyrolysis. This work has been performed with three different carbonization temperatures of 550 °C, 600 °C, and 650 °C. Experimental results show that carbonization at different temperatures causes the formation of different material properties to support the performance of the supercapacitor. The dimensions of the carbon coins display different density values with data trends being degraded after the high-temperature pyrolysis process. In addition, microcrystalline properties were also evaluated by means of the X-ray diffraction technique. The supercapacitor cells were evaluated in two-electrode configurations with an organic membrane as a separator. Electrochemical properties such as specific capacitance, energy density, and power density were thoroughly evaluated through cyclic voltammetry and galvanostatic charge-discharge techniques. The highest specific capacitance was confirmed at 179 F g−1 in a constant current density of 1.0 A g−1. Furthermore, the maximum energy density was found as high as 12.60 Wh kg−1 at the optimum power density of 105.86 Wh kg−1. These results confirm that the carbonization temperature needs to be considered to obtain high-porous activated carbon derived from bio-waste jicama peel for supercapacitor electrode materials.
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Gajewski, Piotr, Aneta Lewandowska, Katarzyna Szcześniak, Grzegorz Przesławski et Agnieszka Marcinkowska. « Optimization of the Properties of Photocured Hydrogels for Use in Electrochemical Capacitors ». Polymers 13, no 20 (12 octobre 2021) : 3495. http://dx.doi.org/10.3390/polym13203495.
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In this work, hydrogel polymer electrolytes (HPEs) were obtained by the photopolymerization of a mixture of two monomers: Exothane 8 (Ex8) and 2-hydroxyethylmethacrylate acid phosphate (HEMA-P) in an organic solvent N-methyl-2-pyrrolidone (NMP), which was replaced after polymerization with water, and then with the electrolyte. The ratio of monomers as well as the concentration of NMP was changed in the composition to study its influence on the properties of the HPE: conductivity (electrochemical impedance spectroscopy, EIS) and mechanical properties (puncture resistance). Properties were optimized using a mathematical model to obtain a hydrogel with both good mechanical and conductive properties. To the best of our knowledge, it is the first publication that demonstrates the application of optimization methods for the preparation of HPE. Then, the hydrogel with optimal properties was tested as a separator in a two-electrode symmetric AC/AC pouch-cell. The cells were investigated by cyclic voltammetry galvanostatic charge/discharge with potential limitation and EIS. Good mechanical properties of HPE allowed for obtaining samples of smaller thickness while maintaining very good dimensional stability. Thus, the electrochemical capacitor (EC) resistance was reduced and their electrochemical properties improved. Moreover, photopolymerization kinetics in the solvent and in bulk by photo-DSC (differential scanning calorimetry) were performed. The great impact on the polymerization of HEMA-P and its mixtures (with Ex8 and NMP) have strong intermolecular interactions between reagents molecules (i.e., hydrogen bonds).
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Shen, Yang, Erik Svensson Grape, Dag Noréus, Erika Widenkvist et Stina Starborg. « Upcycling of Spent NiMH Battery Material—Reconditioned Battery Alloys Show Faster Activation and Reaction Kinetics than Pristine Alloys ». Molecules 25, no 10 (17 mai 2020) : 2338. http://dx.doi.org/10.3390/molecules25102338.
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During formation and cycling of nickel–metal hydride (NiMH cells), surface corrosion on the metal hydride particles forms a porous outer layer of needle-shaped rare-earth hydroxide crystals. Under this layer, a denser but thinner oxidized layer protects the inner metallic part of the MH electrode powder particles. Nano-sized nickel-containing clusters that are assumed to promote the charge and discharge reaction kinetics are also formed here. In this study, mechanical treatments are tested to recycle hydrogen storage alloys from spent NiMH batteries. This removes the outer corroded surface of the alloy particles, while maintaining the catalytic properties of the surface. Scanning electron microscopy images and powder X-ray diffraction measurements show that the corrosion layer can be partly removed by ball milling or sonication, combined with a simple washing procedure. The reconditioned alloy powders exhibit improved high rate properties and activate more quickly than the pristine alloy. This indicates that the protective interphase layer created on the alloy particle during their earlier cycling is rather stable. The larger active surface that is created by the mechanical impact on the surface by the treatments also improves the kinetic properties. Similarly, the mechanical strain during cycling cracks the alloy particles into finer fragments. However, some of these particles form agglomerates, reducing the accessibility for the electrolyte and rendering them inactive. The mechanical treatment also separates the agglomerates and thus further promotes reaction kinetics in the upcycled material. Altogether, this suggests that the MH electrode material can perform better in its second life in a new battery.
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Bond, T. C., C. Zarzycki, M. G. Flanner et D. M. Koch. « Quantifying immediate radiative forcing by black carbon and organic matter with the Specific Forcing Pulse ». Atmospheric Chemistry and Physics Discussions 10, no 6 (28 juin 2010) : 15713–53. http://dx.doi.org/10.5194/acpd-10-15713-2010.
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Abstract. We propose a measure to quantify climate warming or cooling by pollutants with atmospheric lifetimes of less than one year: the Specific Forcing Pulse (SFP). SFP is the amount of energy added to the Earth system per mass of pollutant emitted. Global average SFP for black carbon, including atmosphere and cryosphere, is 1.12 GJ g−1 and that for organic matter is −0.061 GJ g−1. We provide regional values for black carbon (BC) and organic matter (OM) emitted from 23 source-region combinations, divided between atmosphere and cryosphere impacts and identifying forcing by latitude. Regional SFP varies by about 40% for black carbon. This variation is relatively small because of compensating effects; particles from regions that affect ice albedo typically have shorter atmospheric lifetimes because of lower convection. The ratio between BC and OM SFP implies that, for direct forcing, an OM:BC mass ratio of 15 has a neutral effect on top-of-atmosphere direct forcing for any region, and any lower ratio induces direct warming. However, important processes, particularly cloud changes that tend toward cooling, have not been included here. We demonstrate ensemble adjustment, in which we produce a "best estimate" by combining a suite of diverse but simple models and enhanced models of greater complexity. Adjustments for black carbon internal mixing and for regional variability are discussed; regions with convection are implicated in greater model diversity. SFP expresses scientific uncertainty and separates it from policy uncertainty; the latter is caused by disagreements about the relevant time horizon, impact, or spatial scale of interest. However, metrics used in policy discussions, such as global warming potentials, are easily derived from SFP. Global-average SFP for biofuel and fossil fuel emissions translates to a 100-year GWP of about 760 for black carbon and −40 for organic matter when snow forcing is included. Ensemble-adjusted estimates of atmospheric radiative impact by black and organic matter using year 2000 emissions are +0.46 W m−2 and −0.17 W m−2, respectively; anthropogenic forcing is +0.38 W m−2 and −0.12 W m−2. The black carbon value is only 11% higher than that of the Intergovernmental Panel on Climate Change (IPCC), although this value includes enhanced absorption due to internal mixing.
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Dizon, Joseph B., et Erin R. Johnson. « van der Waals potential energy surfaces from the exchange-hole dipole moment dispersion model ». Canadian Journal of Chemistry 94, no 12 (décembre 2016) : 1049–56. http://dx.doi.org/10.1139/cjc-2016-0215.
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The potential energy surfaces (PESs) of 28 simple van der Waals complexes, each consisting of a rare-gas (Rg) atom interacting with a linear molecule, are calculated using the exchange-hole dipole moment (XDM) dispersion model in conjunction with three base density functionals (HFPBE, PW86PBE, and a commensurate hybrid functional). Results are compared with literature coupled-cluster reference data. The quality of the computed PESs is assessed based on the positions of the global minima and the corresponding binding energies. Only the hybrid functional is found to provide generally reliable PESs. Dispersion-corrected HFPBE strongly underestimates the equilibrium intermolecular separations and predicts different global minima than the reference PESs for Rg–HCl, Rg–HBr, and two of the Rg–HCN complexes. Analysis of the binding-energy errors reveals that the performance of HFPBE degrades as the size of the Rg atoms increase down the group, while the performance of PW86PBE is significantly worse for strongly-polar molecules. PW86PBE, and to a lesser extent the hybrid, strongly overbind Kr–HF due to charge-transfer error. Despite this, the XDM-corrected hybrid functional displays the best overall error statistics and provides binding energies to within ca. 10 cm–1 of the coupled-cluster reference data at a greatly reduced computational cost.
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Chanturia, Valentin, Valery Morozov, Galina Dvoichenkova et Elena Chanturia. « Increasing the recoverability of diamonds in the process of x-ray luminescent separation using phosphor-containing compositions ». Sustainable Development of Mountain Territories 14, no 3 (30 septembre 2022) : 410–21. http://dx.doi.org/10.21177/1998-4502-2022-14-3-410-421.
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Introduction. A promising way to solve the problem of reducing the losses of weakly and abnormally luminescent diamonds in the process of X-ray luminescent separation is to modify their spectral characteristics with special compositions of phosphors. The phosphor-containing compositions used include inorganic and organic phosphors that provide the necessary change in the kinetic characteristics of the diamond X-ray luminescence signal. The purpose of the work. Investigation of the mechanism of the process and selection of compositions of phosphorcontaining compositions that provide the required modification of spectral characteristics and increase the extraction of weakly and abnormally luminescent diamonds in the process of X-ray-luminescent separation. Methodology results. Studies of the mechanism of formation of the X-ray luminescence signal from diamond-phosphor complexes were carried out by determining the degree of coating of the surface of diamonds with phosphors by the visiometric method and the amplitude of the luminescence signal with varying concentrations of phosphor in the emulsion. The effectiveness of the selected compositions of the phosphor-containing composition was evaluated by determining and comparative analysis of the acquired spectral and kinetic characteristics of the diamond-phosphor complexes using the Polyus–M separator. The evaluation of the effectiveness of the selected formulations was determined by the results of a test on industrial X-ray luminescent separators. Research results. The mechanism of formation of the X-ray luminescence signal from a diamond with a phosphorcontaining composition fixed on its surface is determined. It is shown that the total signal is the sum of the diamond and phosphor signals attenuated by screening and scattering of luminescent radiation by 5-15% for the diamond signal and 20-40% for the phosphor signal. The use of inorganic phosphors based on zinc sulfide, or a mixture of phosphor based on zinc orthosilicate and anthracene in compositions is justified, providing an increase in the intensity of the X-ray luminescence signal of a weakly luminescent diamond by 2.5 times, and preserving the shape of the X-ray luminescence signal of natural diamonds. It is proposed to use catalytic cracking as a collector of a diesel fraction compound and heavy gas oil, which ensures effective fixation of the phosphor on the surface of diamonds. The composition of the composition (FL-530, anthracene, diesel fraction, THCC) is proposed, which provides the required modification of spectral characteristics and detection of low-luminous diamonds. Resume. The results of the tests carried out on diamonds of various sizes have established the possibility of increasing the extraction of diamonds by 5-15% due to the detection of diamond crystals with weak or abnormal luminescence. At the same time, the required selectivity of the process with respect to kimberlite minerals is maintained. Conclusions. The results of the research are recommended for practical implementation in X-ray luminescent separation schemes at ALROSA processing plants to reduce losses of weakly and abnormally luminescent diamonds and will also be used in further studies of the possibility of increasing the selectivity of separation of diamonds and rock minerals during kimberlite enrichment.
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Henley, W. Hampton, Yan He, J. Scott Mellors, Nicholas G. Batz, J. Michael Ramsey et James W. Jorgenson. « High resolution separations of charge variants and disulfide isomers of monoclonal antibodies and antibody drug conjugates using ultra-high voltage capillary electrophoresis with high electric field strength ». Journal of Chromatography A 1523 (novembre 2017) : 72–79. http://dx.doi.org/10.1016/j.chroma.2017.07.059.
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Yadav, Nitish, Kuldeep Mishra et SA Hashmi. « Nanofiller-incorporated porous polymer electrolyte for electrochemical energy storage devices ». High Performance Polymers 30, no 8 (6 mai 2018) : 957–70. http://dx.doi.org/10.1177/0954008318774392.
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We report the poly(vinylidene fluoride-co-hexafluoropropylene) (PVdF-HFP)-based microporous polymer membranes, prepared by phase inversion technique, incorporated with different amounts of nanosized zirconium dioxide (ZrO2) filler. Scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and thermal studies confirm the role of ZrO2 nanofiller to modify the polymer structure, pore geometry and crystallinity. The nanofillers interact with the PVdF-HFP chains via surface groups and electrostatic interactions, and their incorporation led to an increase in crystalline content of the membrane and ionic conductivity (when activated with a liquid electrolyte (LE)). A possible mechanism for the increase in crystallinity in the polymer due to interaction with nanofiller particles has also been presented. The optimized membrane has been saturated with an LE sodium perchlorate-ethylene carbonate:propylene carbonate for use as a separator/electrolyte in electrical double-layer capacitor (EDLC). The cells fabricated with the nanofiller-incorporated membrane show better performance in terms of specific electrode capacitance, specific energy and specific power (approximately 76 F g−1, approximately 20.9 Wh kg−1 and 2.62 kW kg−1) than the cells using the membrane devoid of nanofillers (approximately 61 F g−1, approximately 17.3 Wh kg−1 and approximately 3.16 kW kg−1), respectively. The EDLC shows approximately 85% retention in specific capacitance for 10,000 charge–discharge cycles.
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Xue, Kaiming, et Denis Yu. « (Digital Presentation) A 2.8V Reversible Sn-Li Battery ». ECS Meeting Abstracts MA2022-01, no 1 (7 juillet 2022) : 80. http://dx.doi.org/10.1149/ma2022-01180mtgabs.
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Tin (Sn) is a metal that is commonly used in our daily life. With the rapid development of lithium-ion battery in the past decades, Sn and its alloy, such as Sn-Cu[1], and Sn-Ni[2], Sn-Co[3] and Sn-Fe[4] have been used as anode for lithium-ion battery because they can undergo alloying/dealloying process with lithium ions and exhibit high capacity and suitable working voltage of about 0.4 V vs. Li/Li+. Sn can also undergo an oxidation reaction to Sn2+, with an electrode potential of about -0.14 V vs. SHE. It is therefore possible to also use Sn as a cathode material. Herein, we are first to demonstrate a metal-metal battery made up of Sn metal as the cathode and Li metal as the anode in organic electrolyte (see Fig. a). Sn foil and Li foil are simply assembled with 3M LiTFSI in dimethoxyethane/propylene carbonate (DME/PC) electrolyte in an Ar-filled glove box to form a pouch cell. During charging, Sn will give out two electrons and dissolves into the electrolyte as Sn2+, while during discharging, the metal ions will be re-deposited onto the cathode. Thus, the energy is stored in the form of Sn2+ in the electrolyte. The charge-discharge curves in Fig. b show that the operating voltage of the battery is about 2.8 V. Since Sn2+ that is dissolved into the electrolyte from the cathode has higher potential than the Li metal anode, any Sn2+ ions cross-over to the anode will be spontaneously reduced, decreasing the efficiency of the battery. To suppress such self-discharge process, an anion exchange membrane based on poly(ionic liquid) polymer coated on common polypropylene separator is adopted. The Sn-Li battery with the modified separator tested in a current rate of 0.2 mA cm-2 with a capacity limitation of 0.1 mAh cm-2 gives an average Coulombic efficiency about 99.5% and can be cycled for more than 1500 cycles(See Fig. c). We found that the stripping/deposition of Sn on the cathode, and its polarization depend strongly on the type of electrolyte used. With 3M LiTFSI in DME/PC electrolyte, the discharge voltage is lowered by about 0.05 V when the current density is increased from 0.2 mA cm-2 to 1 mA cm-2. More results on the factors affecting the charge-discharge performance of Sn-Li batteries will be discussed at the meeting. [1]X. F. Tan, S. D. McDonald, Q. Gu, Y. Hu, L. Wang, S. Matsumura, T. Nishimura, K. Nogita, Journal of Power Sources 2019, 415, 50. [2]H. Zhang, T. Shi, D. J. Wetzel, R. G. Nuzzo, P. V. Braun, Advanced Materials 2016, 28, 742. [3]J. Yang, J. Zhang, X. Zhou, Y. Ren, M. Jiang, J. Tang, ACS Applied Materials & Interfaces 2018, 10, 35216. [4]Z. Lin, X. Lan, X. Xiong, R. Hu, Materials Chemistry Frontiers 2021, 5, 1185. Figure 1