LiBF4／LiODFB混合盐电解液的低温性能  

Low temperature performance of LiBF_4/LiODFB blend salts electrolyte

作　　者：张丽娟[1,2,3,4] 周园 孙艳霞[1,2,3] 胡树青 ZHANG Li-juan;ZHOU Yuan;SUN Yan-xia;HU Shu-qing(Key Laboratory of Comprehensive and Highly Efficient Utilization of Salt Lake Resources, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences,Xining,Qinghai 810008 ,China;Key Laboratory of Salt Lake Resources Chemistry of Qinghai Province,Xining,Qinghai 810008 ,China;University of Chinese Academy of Sciences,Beijing 100049,China;College of Chemistry and Chemical Engineering, Qinghai University for Nationalities, Xining , Qinghai 810007, China)

机构地区：[1]中国科学院青海盐湖研究所,中国科学院盐湖资源综合高效利用重点实验室,青海西宁810008 [2]青海省盐湖资源化学重点实验室,青海西宁810008 [3]中国科学院大学,北京100049 [4]青海民族大学化学化工学院,青海西宁810007

出　　处：《电池》2018年第3期138-141,共4页Battery Bimonthly

基　　金：青海省应用基础研究项目(2015-ZJ-740),教育部春晖计划(Z2012111)

摘　　要：研究四氟硼酸锂(LiBF_4)和二氟草酸硼酸锂(LiODFB)混合锂盐电解液用于磷酸铁锂(LiFePO4)锂离子电池时的低温-20℃性能。探讨电导率与电解液组成、温度的关系;通过循环伏安、充放电、倍率性能及电化学阻抗谱(EIS)测试,比较不同电解液体系中LiFePO_4正极在25℃和-20℃的放电比容量、循环稳定性等。在25℃和-20℃下于2.5~4.2 V充放电,LiFePO_4电极在LiBF_4/Li ODFB基电解液体系中的电化学性能较好:在25℃时以1.0 C倍率充放电,混合盐基电解液电池的首次放电比容量为140 m Ah/g,优于六氟磷酸锂(Li PF6)基电解液的130.5 m Ah/g;-20℃时0.1 C倍率下,首次放电比容量为101.7 m Ah/g,100次循环的容量保持率为86.62%,优于Li PF6基电解液的97.4 m Ah/g和60.57%。The low temperature - 20 ℃ performance of electrolyte based on blend salts lithium tetrafluoroborate （ LiBF4 ） and lithium difluoro（oxalato） borate （LiODFB） for lithium iron phosphate （LiFePO4 ） Li-ion battery was studied. The relation between electric conductivity and electrolyte composition, temperature was discussed. Through the tests of cyclic voltammetry, charge-discharge, rate capability and electrochemical impedance spectroscopy （EIS） ,the specific discharge capacity and cycle stability of LiFePO4 cathode in different electrolyte systems were compared at 25 ℃ and - 20 ℃. The blend salts LiBF4/LiODFB based electrolyte had better electrochemical performance at 25 ℃ and - 20 ℃. The battery with blend salts-based electrolyte was charged-discharged with 1.0 C at 25 ℃ and 0. 1 C at - 20 ℃. The initial discharge capacity was 140 mAh/g, which was higher than 130. 5 mAh/g of lithium hexafluorophosphate （ LiPF6 ） -based electrolyte at 25 ℃. The initial discharge capacity was 101.7 mAh/g and capacity retention was 86. 62% after 100 cycles at -20 ℃ ,which was better than that of LiPF6 based electrolyte 97.4 mAh/g and 60. 57%.

关 键 词：四氟硼酸锂(LiBF4) 二氟草酸硼酸锂(LiODFB) 电解液 锂离子电池 磷酸铁锂(LiFePO4) 低温 

分 类 号：TM912.9[电气工程—电力电子与电力传动]