锂电池用草酸二氟硼酸锂有机电解液的电化学性能

Electrochemical Properties of LiBC_2O_4F_2 Organic Electrolytes for Lithium Batteries

以草酸锂和三氟化硼乙醚溶液合成了草酸二氟硼酸锂(LiBC2O4F2),并用碳酸二甲酯溶剂萃取和重结晶提纯。LiBC2O4F2有机电解液能在铝箔上形成一层致密的保护膜,这能较好地抑制在高电位时电解液在铝箔上发生氧化反应,而且在很宽的温度范围内LiBC2O4F2基电解液都具有较好的离子电导率。电化学测试结果表明:使用1.0mol·L-1LiBC2O4F2有机电解液的LiMn2O4/Li电池首次放电容量为110.2mAh·g-1,并且具有比使用LiPF6有机电解液的LiMn2O4/Li电池更好的高低温循环性能和更优良的低温放电性能。

Lithium difluoro（axalato）borate（LiBC2O4F2） was synthesized by the reaction of Li2C2O4 and BF3 etherate,and purified through extraction and recrystallization using dimethyl carbonate （DMC） as the solvent. LiBC2O4F2 organic electrolytes can form a dense protecting layer on the Al current collector surface so as to effectively suppress the oxidation of electrolytic solvents at high potentials. LiBC2O4F2 organic electrolytes possessed excellent ionic conductivity in a wide temperature range. The results of electrochemical experiments indicated that the discharging capacity of LiMn2O4/Li batteries using 1.0 mol·L^-1 LiBC2O4F2 organic electrolytes was 110.2 mAh ·g^-1, and LiMn2OdLi batteries using the electrolyte containing LiBC2O4F2 exhibited better cycling performance at both room temperature and higher temperature, and excellent low temperature discharging performance.