二氟磷酸锂改善LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2电池的高温性能

Improving elevated temperature performance of LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2 battery by lithium difluorophosphate

将二氟磷酸锂(LiPO_2F_2)作为添加剂来改善LiNi_(0.6)Co_(0.2)Mn_(0.2)O_2电池高温贮存性能。相对于没有添加LiPO_2F_2的电池,电解液中添加1%LiPO_2F_2的电池在高温60℃下贮存14 d,容量保持率提高6.05%,容量恢复率提高6.01%,并能抑制电池高温产气。采用电化学交流阻抗谱测试电池高温贮存前后的阻抗行为,用SEM、X射线光电子能谱(XPS)对电极表面进行分析,发现LiPO_2F_2能够在正极表面形成热稳定性好且可降低界面阻抗的固体电解质相界面(SEI)膜。

Lithium difluorophosphate （LiPO2F2 ） was investigated as an electrolyte additive to improve the elevated temperature storage performance of LiNi0.6Co0.2Mn0.2O2 cells. By adding 1% LiPO2 F2 in the electrolyte ,the capacity retention and recovery ratio of the cell enhanced by 6.05% and 6. 01% ,respectively ,after stored at 60 qC for 14 d. LiPO2F2 decreased gas generation during the storage at high temperature. Electrochemical impedance spectroscopy was used to investigate the emerging of the cell resistance before and after high temperature storage. SEM and X-ray photoelectron spectroscopy （ XPS ） were used to analyze the electrode surface of electrode. It was discovered that a high thermal stability and low impedance layer film were formed on the cathode surface through sacrificing LiPO2 F2.