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8 results on '"Electrolyte solvent"'

1. Cathode reaction mechanism of non-aqueous Li–O2 batteries with highly oxygen radical stable electrolyte solvent

Author

Mizuno, Fuminori, Takechi, Kensuke, Higashi, Shougo, Shiga, Tohru, Shiotsuki, Taishi, Takazawa, Nobuaki, Sakurabayashi, Yasunori, Okazaki, Sanae, Nitta, Iwao, Kodama, Tomoki, Nakamoto, Hirofumi, Nishikoori, Hidetaka, Nakanishi, Shinji, Kotani, Yukinari, and Iba, Hideki

Subjects
*LITHIUM cells, *CATHODES, *CHEMICAL reactions, *NONAQUEOUS electrolytes, *REACTIVE oxygen species, *SOLVENTS, *ELECTRIC potential
Abstract

Abstract: High oxygen radical stability of electrolyte solvent is a key parameter necessary to overcome a large voltage gap in discharge–charge profiles of the non-aqueous Li–air battery. We have proposed N-methyl-N-propylpiperidinium bis(trifluoromethansulfonyl)amide (PP13TFSA) as an appropriate candidate of the electrolyte solvent. PP13TFSA based Li–O2 cells enabled us to draw low charging voltage of around 3.3 V, lowering the voltage gap by nearly half in comparison with those of conventional carbonate-based cells (c.a. 1.4 V). Here, through the detailed analyses of discharge products, we verified the fact that the voltage gap was notably decreased by using the highly radical stable electrolyte solvent. TEM-EELS and FT-IR analyses indicated that Li2O2 was deposited as a discharge product. 13C NMR spectroscopy suggested that no decomposed species derived from electrolyte decomposition was observed from a discharged cathode. GC–MS analyses also revealed that CO and CO2 gases as indices of the decomposed species were not monitored at all. Above-described data substantiated a desirable discharge reaction, resulting in low charging voltage as well as small voltage gap. Design of electrolyte solvents based on their oxygen radical stability and full understanding of the cathode reaction mechanism contributed greatly to a dramatic improvement of the Li–air battery performances. [Copyright &y& Elsevier]

Published
2013
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2. Experimental study on flammability limits of electrolyte solvents in lithium-ion batteries using a wick combustion method

Author

Guo, Feng, Hase, Wataru, Ozaki, Yu, Konno, Yusuke, Inatsuki, Masaya, Nishimura, Katsunori, Hashimoto, Nozomu, 1000010183930, Fujita, Osamu, Guo, Feng, Hase, Wataru, Ozaki, Yu, Konno, Yusuke, Inatsuki, Masaya, Nishimura, Katsunori, Hashimoto, Nozomu, 1000010183930, and Fujita, Osamu

Abstract

To quantify the flammability limits of organic electrolyte solvents used in lithium-ion batteries, a unique wick combustion system was developed in conjunction with limiting oxygen concentration (LOC) of candle-like flame, named wick-LOC method. By controlling the oxygen-nitrogen ratio of external flow of the wick diffusion flame, the flammability limits (LOC) of electrolyte solvents were determined experimentally. To provide reproducible results under specified conditions, the effects of axial flow velocity, exposed wick length and elapsed time after ignition on the wick-LOC were studied, and the proper experimental conditions were selected for further applications. To validate the reliability of wick-LOC in flammability evaluation, correlation analyses to other flammability properties (flash point, auto-ignition temperature, the heat of combustion and other types of LOC) were conducted. The wick-LOC method was then applied to quantify the flammability of mixed solvents. The linear changes of wick-LOC with mixing ratios were found in the mixture of linear and cyclic carbonates, while the non-linear trends were found in carbonate-ether mixed solvents. To evaluate the flame-retardant effectiveness of organophosphorus compounds (OPCs) as additives in electrolyte solvents, a series of tests were conducted. Results showed that small amounts of OPCs had significant flame-retardant effects, but the efficiency decreased with the higher OPC additions. The effectiveness of four OPCs was distinguished as well. The results of this work provided valuable information about the flammability limits of single and mixed electrolyte solvents, and it may be useful for designing electrolyte balanced in both performance and safety.

Published
2019

3. A new phosphate-based nonflammable electrolyte solvent for Li-ion batteries

Author

Wu, Lei, Song, Zhiping, Liu, Lishan, Guo, Xiangfeng, Kong, Lingbo, Zhan, Hui, Zhou, Yunhong, and Li, Zaoying

Subjects
*LITHIUM-ion batteries, *ELECTROLYTE solutions, *PHOSPHATES, *ORGANIC synthesis, *FIREPROOFING agents, *ELECTROCHEMISTRY, *LITHIUM compounds
Abstract

Abstract: A new fire-retardant—dimethyl(2-methoxyethoxy)methylphosphonate (DMMEMP) has been synthesized and evaluated as a high safe electrolyte solvent for lithium-ion batteries. This report summarizes the physical and electrochemical properties of the new compound. It is found that, this nonflammable phosphonate has a moderate viscosity, a high dielectric constant and a good thermal stability. It can provide a wide electrochemical stability window of 0–5.5V (vs. Li+/Li), a high conductivity of 2.0mScm−1 at 20°C with 1M LiTFSI. The electrochemical performance investigated with the Li/LiFePO4 half-cells shows a good capacity of 148.1mAhg−1 and a coulombic efficiency close to 100% at the 10th cycle. [Copyright &y& Elsevier]

Published
2009
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4. Dimethyl methyl phosphate: A new nonflammable electrolyte solvent for lithium-ion batteries

Author

Feng, J.K., Sun, X.J., Ai, X.P., Cao, Y.L., and Yang, H.X.

Subjects
*PHOSPHATES, *ELECTROLYTES, *LITHIUM ions, *ELECTRIC batteries, *METHYL phosphates
Abstract

Abstract: A new fire retardant-dimethyl methyl phosphate (DMMP) was tested as a nonflammable electrolyte solvent for Li-ion batteries. It is found that in the addition of chloro-ethylene carbonate (Cl-EC) as an electrolyte additive, the electrochemical reduction of DMMP molecules can be completely suppressed and the graphite anode can be cycled very well with high initial columbic efficiency (∼84%) and excellent cycling stability in the DMMP electrolyte. The prismatic C/LiCoO2 batteries using 1.0molL−1 LiClO4 +10% Cl-EC+DMMP electrolyte exhibited almost the same charge and discharge performances as those using conventional carbonate electrolytes, suggesting a feasible use of this new electrolyte for constructing nonflammable Li+-ion batteries. [Copyright &y& Elsevier]

Published
2008
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5. Possible use of non-flammable phosphonate ethers as pure electrolyte solvent for lithium batteries

Author

Feng, J.K., Ai, X.P., Cao, Y.L., and Yang, H.X.

Subjects
*LITHIUM cells, *CATHODE rays, *LITHIUM, *ELECTRIC batteries
Abstract

Abstract: Dimethyl methyl phosphonate (DMMP) was selected and tested as a non-flammable solvent for primary and secondary lithium batteries, because of its non-flammability, good solvency of lithium salts and appropriate liquidus properties. Experimental results demonstrated that DMMP can solvate considerable amount of commonly used lithium salts to form non-flammable and Li+-conducting electrolyte, which has very wide electrochemical window (>5V vs. Li) and excellent electrochemical compatibility with metallic lithium anode and oxide cathodes. Primary Li–MnO2 cells using DMMP-based electrolyte showed almost the same discharge performances as those using organic carbonate electrolytes, and also, Li–LiMn2O4 cells using DMMP electrolyte exhibited greatly improved cycleability and dischargeability, suggesting a feasible application of this new electrolyte for constructing high performance and non-flammable lithium batteries. [Copyright &y& Elsevier]

Published
2008
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6. Asymmetric Star-Shaped Functionalized Triazine Architecture and Its Electrochromic Device Application

Author

Metin Ak, Erhan Karatas, and Merve Guzel

Subjects
Cyclic voltammetry, Inorganic compounds, 02 engineering and technology, Star-shaped copolymer, Star (graph theory), Electrochromic devices, Photochemistry, Spectroelectrochemical study, Electrolytes, chemistry.chemical_compound, Electrochromic switching, Copolymerization, 0202 electrical engineering, electronic engineering, information engineering, Materials Chemistry, Electrochemistry, Copolymer, Spectroelectrochemistry, Hydroxyquinoline, Electrolyte solvent, PEDOT, Triazine, Conductive polymer, s-Triazines, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Polycyclic aromatic hydrocarbons, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Electrochromism, 0210 nano-technology, Materials science, 020209 energy, Conducting polymers, Nanotechnology, Triazine derivatives, Electrically conductive, Open circuit memory, Electrochromic properties, PEDOT:PSS, Crosslinked, Electrochromic materials, Renewable Energy, Sustainability and the Environment, Star-shaped polymers, Electropolymerization, Stars, Polycarbazoles, chemistry, Lithium perchlorate, Poly(3 ,4 ethylenedioxythiophene) (PEDOT)
Abstract

A new asymmetric functionalized star shaped triazine derivative, namely 2,2'-((6-(quinolin-8-yloxy)-1,3,5-triazine-2,4-diyl)bis(oxy))bis(9H carbazole) (TQC) was synthesized from 2-hydroxy carbazole and 8-hydroxyquinoline. The electrically conductive PTQC film was synthesized via electropolymerization on ITO in a 0.1 M lithium perchlorate/acetonitrile (LiClO4/ACN) electrolyte-solvent couple. H-1-NMR, FTIR and elemental analysis were used to analyze the structure of the TQC. Both electrochemical and spectroelectrochemical studies of the polymer were examined. PTQC revealed color changes between transparent and dark green in the reduced and oxidized states, respectively. Dual type polymer electrochromic devices (ECDs) based on PTQC and poly(3,4-ethylenedioxythiophene) (PEDOT) have been constructed. A potential range of 0 to 2.5 V was found to be proper for working the PTQC/PEDOT device between transparent and blue colors. The spectroelectrochemistry, electrochromic switching, open circuit memory and stability of the device were studied. The properties of the electrochromic device have been investigated such as spectroelectrochemistry, electrochromic switching, stability and open circuit memory. (C) 2017 The Electrochemical Society. All rights reserved.

Published
2017

7. Examining the Role of Electrolyte and Binders in Determining Discharge Product Morphology and Cycling Performance of Carbon Cathodes in Li-O2Batteries

Author

Hugh Geaney and Colm O'Dwyer

Subjects
Cathodes, Energy storage, Materials science, Morphology (linguistics), Bins, Low water-content, Inorganic chemistry, Galvanostatic tests, chemistry.chemical_element, Cycling performance, 02 engineering and technology, Electrolyte, Lithium, 010402 general chemistry, 01 natural sciences, law.invention, Electrolytes, Li-O2 battery, law, Product morphology, Binders, Materials Chemistry, Electrochemistry, Li-air battery, Discharge capacities, Electrolyte solvent, Electrodes, Renewable Energy, Sustainability and the Environment, Secondary batteries, Electrochemical response, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Electric batteries, Cathode, 0104 chemical sciences, Surfaces, Coatings and Films, Electronic, Optical and Magnetic Materials, Lithium batteries, chemistry, Chemical engineering, Electric discharges, Cathode composition, 0210 nano-technology, Cycling, Carbon
Abstract

In this report we examine the influence of electrode binder and electrolyte solvent on the electrochemical response of carbon based Li-O2 battery cathodes. Much higher discharge capacities were noted for cathodes discharged in DMSO compared to TEGDME. The increased capacities were related to the large spherical discharge products formed in DMSO. Characteristic toroids which have been noted in TEGDME electrolytes previously were not observed due to the low water content of the electrolyte. Linear voltage sweeps were used to investigate ORR in both of the solvents for each of the binder systems (PVDF, PVP, PEO and PTFE) and related to the Li2O2 formed on the cathode surfaces. Galvanostatic tests were also conducted in air as a comparison with the pure O2 environment typically used for Li-O2 battery testing. Interestingly, tests for the two electrolytes showed opposite trends in terms of discharge capacity values with capacities increased in TEGDME (compared to those seen in O2) and decreased in DMSO. The report highlights the key roles of electrolyte and cathode composition in determining the stability of Li-O2 batteries and highlights the importance of identifying more stable electrolyte/cathode pairings.

Published
2015

8. Experimental study on flammability limits of electrolyte solvents in lithium-ion batteries using a wick combustion method

Author

Yu Ozaki, Katsunori Nishimura, Feng Guo, Osamu Fujita, Wataru Hase, Yusuke Konno, Nozomu Hashimoto, and Masaya Inatsuki

Subjects
Materials science, General Chemical Engineering, Aerospace Engineering, 02 engineering and technology, Electrolyte, Combustion, 01 natural sciences, Lithium-ion battery, 010305 fluids & plasmas, Flammability limit, Wick combustion, 020401 chemical engineering, 0103 physical sciences, 0204 chemical engineering, Electrolyte solvent, Flammability, Fluid Flow and Transfer Processes, Mechanical Engineering, Diffusion flame, Nuclear Energy and Engineering, Chemical engineering, Organophosphorus compound, Flame-retardant, Limiting oxygen concentration, Fire retardant
Abstract

To quantify the flammability limits of organic electrolyte solvents used in lithium-ion batteries, a unique wick combustion system was developed in conjunction with limiting oxygen concentration (LOC) of candle-like flame, named wick-LOC method. By controlling the oxygen-nitrogen ratio of external flow of the wick diffusion flame, the flammability limits (LOC) of electrolyte solvents were determined experimentally. To provide reproducible results under specified conditions, the effects of axial flow velocity, exposed wick length and elapsed time after ignition on the wick-LOC were studied, and the proper experimental conditions were selected for further applications. To validate the reliability of wick-LOC in flammability evaluation, correlation analyses to other flammability properties (flash point, auto-ignition temperature, the heat of combustion and other types of LOC) were conducted. The wick-LOC method was then applied to quantify the flammability of mixed solvents. The linear changes of wick-LOC with mixing ratios were found in the mixture of linear and cyclic carbonates, while the non-linear trends were found in carbonate-ether mixed solvents. To evaluate the flame-retardant effectiveness of organophosphorus compounds (OPCs) as additives in electrolyte solvents, a series of tests were conducted. Results showed that small amounts of OPCs had significant flame-retardant effects, but the efficiency decreased with the higher OPC additions. The effectiveness of four OPCs was distinguished as well. The results of this work provided valuable information about the flammability limits of single and mixed electrolyte solvents, and it may be useful for designing electrolyte balanced in both performance and safety.

Published
2019

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