LiODFB电解液的高低温性能
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摘要
采用DSC、电化学工作站和电池测试系统研究LiODFB/(EC+DMC+EMC)和LiPF6/(EC+DMC+EMC)电解液的热稳定性、高低温下的电化学窗口及其对铝箔集流体的稳定性、LiFePO4/G(石墨,graphite,简称G)电池在60和-20℃的高循环性能,通过SEM分析循环后的正负极极片形貌,探索高低温下电解液与极片的相互作用机理。研究结果表明:LiODFB电解液在250℃才会分解,而LiPF6电解液的分解温度为120℃;在-20和60℃时,LiODFB电解液的电化学窗口及其对集流体铝箔的稳定性比LiPF6电解液的大;以LiFePO4/G为电极的LiODFB电池在-20和60℃循环100次后的容量保持率均比LiPF6电池的大,LiODFB电解液能够帮助石墨表面SEI膜的形成,而LiPF6电解液在高温下会产生HF破坏SEI膜,致使电池性能降低。
The thermal stability of LiODFB/(EC+DMC+EMC) electrolyte and LiPF6/(EC+DMC+EMC) electrolyte,electrochemical window and stability with the aluminum foil at high and low temperature,and the cycle performance of LiFePO4/G(graphite) battery at 60 and -20 ℃ were studied by DSC,electrochemical workstations and battery test system.SEM was used to analyse the anode morphology after cycle,and the interaction mechanism between the electrolyte and electrode at high and low temperature was also investigated.The results show that LIODFB electrolyte is decomposed at 250 ℃,while LiPF6 electrolyte has a decomposition temperature of 120 ℃.The electrochemical of LiODFB electrolyte and its stability with aluminum foil are superior to those of LiPF6 electrolyte at -20 and 60 ℃.LiODFB battery with LiFePO4/G for electrode has better capacity retention than the LiPF6 battery at -20 and 60 ℃.LiODFB electrolyte is benefitial to the formation of the SEI film on the G electrode.However,LiPF6 electrolyte would generate HF to destroy the SEI film at high temperature.
The thermal stability of LiODFB/(EC+DMC+EMC) electrolyte and LiPF6/(EC+DMC+EMC) electrolyte,electrochemical window and stability with the aluminum foil at high and low temperature,and the cycle performance of LiFePO4/G(graphite) battery at 60 and -20 ℃ were studied by DSC,electrochemical workstations and battery test system.SEM was used to analyse the anode morphology after cycle,and the interaction mechanism between the electrolyte and electrode at high and low temperature was also investigated.The results show that LIODFB electrolyte is decomposed at 250 ℃,while LiPF6 electrolyte has a decomposition temperature of 120 ℃.The electrochemical of LiODFB electrolyte and its stability with aluminum foil are superior to those of LiPF6 electrolyte at -20 and 60 ℃.LiODFB battery with LiFePO4/G for electrode has better capacity retention than the LiPF6 battery at -20 and 60 ℃.LiODFB electrolyte is benefitial to the formation of the SEI film on the G electrode.However,LiPF6 electrolyte would generate HF to destroy the SEI film at high temperature.
引文
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[3]Fang S H,Tang Y F,Tai X Y,et al.One ether-functionalizedguanidinium ionic liquid as new electrolyte for lithium battery[J].Journal of Power Sources,2011,196(3):1433-1441.
[4]Angenendt K,Johansson P.Ionic liquid based lithium batteryelectrolytes:Charge carriers and interactions derived by densityfunctional theory calculations[J].Journal of Physical ChemistryB,2011,115(24):7808-7813.
[5]Yoshizawa H,Ikoma M.Thermal stabilities of lithiummagnesium cobalt oxides for high safety lithium-ion batteries[J].J Power sources,2005,146(6):121-124.
[6]Andersson A M,Henningson A,Siegbahn H,et a1.Electrochemically lithiated graphite characterized byphotoelectron spectroscopy[J].Journal of Power Sources,2003,119/120/121:522-527.
[7]Yokoyama K,Hiwar A,Fujita A,et al.Carbonate compoundsnon-aqueous electrolytic solutions and batteries comprisingnon-aqueous electrolytic solutions:US,5847188[P].1998-12-08.
[8]Masashi I,Hideaki K,Masayuki M,et al.Li(CF3SO2)2N as aelectrolytic salt for rechargeable lithium batteries withgraphitized mesocarbon microbeads anodes[J].Journal of PowerSources,2000,62(2):229-232.
[9]付茂华.磷酸铁锂电池用高低温电解液的研究[D].长沙:中南大学化学化工学院,2010:16-42.FU Maohua.Study of LiFePO4-battery with high/lowtemperature electrolyte[D].Changsha:Central South University.School of Materials Science and Engineering,2010:16-42.
[10]Fu M H,Huang K L,Liu S Q,et al.Lithiumdifluoro(oxalato)borate/ethylene carbonate+propylene carbonate+ethyl(methyl)carbonate electrolyte for LiMn2O4-cathode[J].Journal of Power Sources,2010,195(11):862-866.
[11]付茂华,黄可龙,刘素琴,等.二氟草酸硼酸锂对LiFePO4/石墨电池高温性能的影响[J].物理化学学报,2009,25(10):1985-1990.FU Maohua,HUANG Kelong,LIU Suqin,et al.Effect oflithiumdifluoro(oxalato)borate on the high-temperatureperformance of LiFePO4/graphite batteries[J].Acta Phys ChimSin,2009,25(10):1985-1990.
[12]邓凌峰,陈洪.锂离子电池电解质LiBC2O4F2的合成与电化学性能[J].电源技术,2010,34(3):237-240.DENG Lingfeng,CHEN Hong.Electrochemical properties andsynthesis of LiBC2O4F2-for lithium batteries[J].Chinese Journalof Power Sources,2010,34(3):237-240.
[13]李凡群.LiODFB基电解液及其与LiFePO4-AC/AG-AC超级电容电池电极材料的相容性研究[D].长沙:中南大学化学化工学院,2009:1530.LI Fanqun.Study of LiODFB electrolyte and its compatibilitywith super capacity material LiFePO4-AC/AG-AC[D].Changsha:Central South University.School of Materials Science andEngineering,2009:15-30.
[14]郑洪河.锂离子电池电解质[M].北京:化学工业出版社,2007:51-53.ZHENG Honghe.Lithium battery electrolyte[M].Beijing:Chemical Industry Press,2007:51-53.
[15]Mori S,Asahina H,Suzuki H,et al.Proceedings of the eighthinternational meeting on lithium batteries[C]//EnergyDevelopment.Nagoya,Japan:International Academic Publishers,1996:16-21.
[16]Sato K,Zhao L W,Okada S,et al.LiPF6/methyl difluoroacetateelectrolyte with vinylene carbonate additive for Li-ionbatteries[J].Journal of Power Sources,2011,196(13):5617-5622.
[17]Peled E,Golodnitsky D,Menachem C,et al.Advanced tool forthe selection of electrolyte components for rechargeable lithiumbatteries[J].Journal of the Electrochemical Society,1998,145(10):3482-3486.
[18]Deng T S,Hsieh P H,Yang M H.Effect of mixed LiBOB andLiPF6-salts on electrochemical and thermal properties inLiMn2O4-batteries[J].Journal of Power Sources,2007,174(25):663-667.
[19]Zhang S S,Ding M S,Xu K,et al.Understanding solidelectrolyte interface film formation on graphite electrodes[J].Electrochemical and Solid-State Letters,2001,4(12):206-208.
[20]Colclasure A M,Smith K A,Kee R J.Modeling detailedchemistry and transport for solid-electrolyte-interface(SEI)filmsin Li-ion batteries[J].Electrochimica Acta,2011,58(1):33-43.