高温锂离子电池用混盐电解液体系  

Mixed salt electrolyte system for high-temperature Li-ion battery

作　　者：何劲作 闫啸 张丽娟 HE Jinzuo;YAN Xiao;ZHANG Lijuan(College of Chemistry and Chemical Engineering,Qinghai Minzu University,Xining,Qinghai 810007,China)

机构地区：[1]青海民族大学化学化工学院,青海西宁810007

出　　处：《电池》2024年第2期165-169,共5页Battery Bimonthly

基　　金：青海省科学技术国际合作项目(2022-HZ-809);青海民族大学高水平人才项目(2018XJG03);青海民族大学研究生优质示范课程建设(JK-2023-06)。

摘　　要：正极电解质相界面(CEI)膜会影响锂离子电池的高温性能。商用电解液在高温下的热稳定性差,形成的CEI膜不够稳定,易导致电池失效。以热稳定性及成膜性能良好的双三氟磺酰亚胺锂(LiTFSI)和二氟草酸硼酸锂(LiODFB)为锂盐,EC+EMC(体积比3∶7)为溶剂,构建电解液体系,考察制备的LiCoO_(2)/Li半电池的电化学性能。在70℃下,LiCoO_(2)/Li半电池在0.5 mol/L LiTFSI+0.5 mol/L LiODFB基电解液体系下,以1.0 C在2.7~4.2 V循环,首次放电比容量为131.2 mAh/g,循环100次的容量保持率为90.8%。这得益于电解液体系生成了均匀、致密且具有良好离子电导率的CEI膜。The cathodic solid electrolyte interphase(CEI)film will affect the high-temperature performance of Li-ion battery.Commercial electrolytes have poor thermal stability at high temperature and the formed CEI film is not stable enough,which can easily lead to battery failure.Lithium difluorosulfonate(LiTFSI)and lithium difluorooxalate borate(LiODFB),which have good thermal stability and film-forming performance,are used as lithium salts,EC+EMC(volume ratio is 3∶7)are used as the solvent,to construct an electrolyte system.The cycle performance of the prepared LiCoO_(2)/Li half cell is investigated.At 70℃,the initial specific discharge capacity of LiCoO_(2)/Li half cell in a 0.5 mol/L LiTFSI+0.5 mol/L LiODFB based electrolyte system is 131.2 mAh/g,the capacity retention rate is 90.8%after 100 cycles at 1.0 C in 2.7-4.2 V.This is due to the uniform and dense CEI film formed on the electrode surface by the electrolyte system,it also has good ionic conductivity.

关 键 词：锂离子电池 电解液 高温 双三氟磺酰亚胺锂(LiTFSI) 二氟草酸硼酸锂(LiODFB) 铝箔腐蚀 正极电解质相界面(CEI)膜 协同效应 

分 类 号：TM912.9[电气工程—电力电子与电力传动]