摘要
以2-三氟甲基苯腈(2-TB)、3-三氟甲基苯腈(3-TB)、4-三氟甲基苯腈(4-TB)作为锂离子电池电解液添加剂,考察其取代基位置对电池性能的影响。首先,通过量子化学方法计算了3种添加剂的最高占据分子轨道(HOMO)和最低未占据分子轨道(LUMO);接着,测试了电池的电化学性能;最后,采用SEM、TEM及FTIR表征了钴酸锂电极的表面形貌及组成。结果表明,相对于不含添加剂的基础电解液,含有质量分数为0.5%添加剂的电解液可形成一层致密而稳定的正极电解液界面保护膜,从而提高电解液的电化学性能。其中,与2-TB和3-TB相比,4-TB可在首次充放电后形成15.0~40.0 nm的电极保护膜,将界面传输电阻降低至61.63Ω,循环30圈后的放电比容量提高至126.8 mA·h/g。不同取代基在苯环对位的电化学性能最佳,其次是邻位和间位。
2-Trifluoromethylbenzonitrile(2-TB),3-trifluoromethylbenzonitrile(3-TB)and 4-trifluoromethylbenzonitrile(4-TB)were used as lithium-ion battery electrolyte additives to investigate the influence of substituent position on battery performance.The highest occupied molecular orbital(HOMO)and lowest unoccupied molecular orbital(LUMO)of the three additives were firstly calculated by quantum chemistry method,followed by electrochemical performance of lithium ion battery analysis.Finally,the surface morphology and composition of lithium cobaltate electrode were characterized by SEM,TEM and FTIR.The results showed that,compared with the control without any additives,the electrolytes containing additives with a mass fraction of 0.5%could form a dense and stable layer of interface protection film for the anode,thus led to electrochemical performance improvement,4-TB of the three additives could form a 15.0~40.0 nm electrode protective film upon the first charge and discharge cycle,reduced the interface transmission resistance to 61.63Ω,and increased the discharge specific capacity to 126.8 mA·h/g after 30cycles.The results suggested that substituents on the para-position of phenyl ring had most influence on electrochemical performance,followed by ortho-and meta-position.
作者
张嘉玉
雷英
李颜利
ZHANG Jiayu;LEI Ying;LI Yanli(School of Chemical Engineering,Sichuan University of Science&Engineering,Zigong 643002,Sichuan,China)
出处
《精细化工》
EI
CAS
CSCD
北大核心
2022年第4期783-789,共7页
Fine Chemicals
基金
化学合成与污染控制四川省重点实验室开放项目资助(CSPC202102)
四川省科技厅重点研发项目资助(2020YFG0422)
自贡市重点科技计划项目资助(2019YYJC19)
四川轻化工大学人才引进项目资助(2018RCL02)。
关键词
锂离子电池
量子化学
电化学
稳定性
含氟添加剂
有机电化学
lithium-ion battery
quantum chemistry
electrochemistry
stability
fluoride additives
electroorganic chemistry
