关键词: 锂离子电池, 电解液添加剂, 石墨, 固体电解质界面膜, 二氟草酸硼酸钠

Abstract: The fast development in applications of Li-ion batteries (LiBs) in daily life urges for better electrochemical performance of LiBs, which can be promoted by adding appropriate electrolyte additives. This work studied the effect of NaDFOB as the additive on a common electrolyte formula (1 mol·L^-1 LiPF₆ in EC+DMC+EMC, 1:1:1 by volume). Analysis methods such as CV, EIS and SEM were adopted to study electrochemical performance of experimental battery and interface profiles. It was revealed that the reversible charge-discharge capacity and cycling performance of graphite anode had been dramatically improved. In addition, the cycling performance of graphite anode at moderate temperature was obviously improved by the adoption of NaDFOB. Both anion and cation in NaDFOB participated the formation of SEI film on the graphite anode surface and thus generated a highly stable electrolyte/electrode interface.

Key words: Li-ion battery, electrolyte additive, graphite, SEI film, sodium difluoro (oxalato)borate