【摘要】 以丙酸乙酯(EP)作为碳酸乙烯酯(EC)、碳酸甲乙酯(EMC)和碳酸二甲酯(DMC)的共溶剂,研究其对LiFePO4锂离子电池低温电化学性能的影响.利用循环伏安曲线、交流阻抗图谱和恒电流充放电曲线等方法测试电池电化学性能.结果表明,添加一定量EP,可提高碳酸酯电解液的离子电导率,改善电解液与正极LiFePO4材料和负极石墨材料的相容性,从而提高LiFePO4锂离子电池的低温性能.使用1 mol·L-1LiPF6/(EC:EMC:DMC:EP=1:1:1:3,by mass)电解液的石墨/LiFePO4锂离子电池在10oC(1C)、-10oC(0.2C)、-20oC(0.2C)、-30oC(0.2C)和-40oC(0.2C)下的相对放电容量(以25oC时的放电容量为基准)分别为82.9%、75.6%、59.0%、46.4%和37.6%.更多还原

【Abstract】 A linear carboxylic,ester ethyl propionate(EP),was used as the co-solvent of carbonates,ethylene carbonate(EC),ethyl-methyl carbonate(EMC) and dimethyl carbonate(DMC),and its effect on low-temperature performance of LiFePO4-based Li-ion battery was studied by cyclic voltammetry(CV),electrochemical impedance spectroscopy(EIS) and galvanostatic charge-discharge test.The application of EP enhances the ionic conductivity of the electrolyte,improves the compatibility of the electrolyte with both LiFePO4and graphite materials,and thus improves the low-temperature performance of LiFePO4-based Li-ion battery.The Li-ion battery using the optimized electrolyte of 1 mol.L-1 LiPF6/EC:EMC:DMC:EP(1:1:1:3) shows the capacity retention of 82.9%,75.6%,59.0%,46.4%,and 37.6% of discharge capacity at room temperature when discharged at 10 oC(1C),-10 oC(0.2C),-20oC(0.2C),-30oC(0.2C),and-40oC(0.2C),respectively.更多还原