摘要
电解液易受使用环境温度的影响。研究四氟硼酸锂(LiBF_(4))/二氟草酸硼酸锂(LiODFB)混合锂盐和四元溶剂碳酸乙烯酯(EC)/碳酸丙烯酯(PC)/碳酸甲乙酯(EMC)/乙酸乙酯(EA)(体积比1∶1∶1∶2)构成的电解液,用于钴酸锂(LiCoO_(2))锂离子电池时的低温(-20℃)性能。LiCoO_(2)正极在LiBF_(4)/LiODFB基电解液体系中的性能较好:在25℃时,以1.0 C在2.7~4.2 V充放电,混盐LiBF_(4)/LiODFB(物质的量比7∶3)基电解液电池的首次放电比容量为145.6 mAh/g,优于六氟磷酸锂(LiPF_(6))基电解液的129.6 mAh/g;在-20℃时,0.1 C的首次放电比容量为110.6 mAh/g,循环100次的容量保持率为89.96%,优于LiPF_(6)基电解液的83.4 mAh/g和76.16%。SEM分析表明:混盐LiBF_(4)/LiODFB(7∶3)基电解液形成一层均匀、致密的正极电解质相界面(CEI)膜,可保护电极和阻止电解液分解。
Electrolyte was susceptible to the influence of ambient temperature.The electrolyte consisted of lithium tetrafluoroborate(LiBF_(4))/lithium difluoroxalate borate(LiODFB)mixed lithium salt and quaternary solvent ethylene carbonate(EC)/propylene carbonate(PC)/methyl ethyl carbonate(EMC)/ethyl acetate(EA)(volume ratio was 1∶1∶1∶2)was studied,which was used for low temperature(-20℃)performance of lithium cobalate(LiCoO_(2))Li-ion battery.The performance of LiCoO_(2)cathode in LiBF_(4)/LiODFB based electrolyte system was better.At 25℃,the initial specific discharge capacity of the mixed salt LiBF_(4)/LiODFB(molar ratio was 7∶3)was 145.6 mAh/g at 1.0 C in 2.7-4.2 V,which was better than 129.6 mAh/g of lithium hexafluorophosphate(LiPF_(6))based electrolyte.At-20℃,the initial specific discharge capacity at 0.1 C was 110.6 mAh/g,the capacity retention rate of 100 cycles was 89.96%,which was better than 83.4 mAh/g and 76.16%of LiPF_(6)-based electrolyte.SEM analysis showed that mixed salt LiBF_(4)/LiODFB(7∶3)electrolyte formed a uniform and dense cathode electrolyte interphase(CEI)film,to protect the electrode and prevent the decomposition of electrolyte.
作者
辛娟
张丽娟
李海朝
何劲作
XIN Juan;ZHANG Li-juan;LI Hai-chao;HE Jin-zuo(College of Chemistry and Chemical Engineering,Qinghai Minzu University,Xining,Qinghai 810007,China)
出处
《电池》
CAS
北大核心
2022年第6期623-626,共4页
Battery Bimonthly
基金
青海省自然科学基金青年项目(2019-ZJ-938Q)
青海民族大学高层次人才项目(2018XJG03)
青海民族大学研究生创新项目(12M2021009)。
