锂离子电池中广泛采用的聚丙烯和聚乙烯隔膜由于热稳定性差、易燃等问题,成为导致严重火灾事故的原因之一。本研究以聚偏二氯乙烯(PVDC)为基体,通过乙烯-乙烯醇(EVOH)掺杂,对PVDC隔膜进行增韧改性及阻燃增强。EVOH具有良好的阻隔空气和水的作用,可以保护锂盐在空气中稳定保存;而锂盐的添加,使EVOH隔膜具有锂离子传输能力。结果表明,在空气条件下采用溶液浇筑法制备出一种可控掺杂的EVOH@PVDC复合隔膜,提高隔膜的电导率及电解液的润湿性,从而提高电化学性能。EVOH@PVDC复合隔膜展现出相对于聚丙烯隔膜优异的高倍率性能,在5C的倍率下其放电比容量为120mAh/g。同时EVOH@PVDC复合隔膜的高阻隔性使锂金属电池具备优异的循环寿命,100次循环后,比容量为145mAh/g且仍保持98%的平均库仑效率。

Polypropylene and polyethylene separators widely used in lithium-ion batteries are one of the causes of serious fire accidents due to their poor thermal stability and flammability.This study used polyvinylidene chloride (PVDC) as the matrix and doped with ethylene-vinyl alcohol (EVOH) to enhance the toughness and flame retardancy of PVDC membranes.EVOH had good air and water barrier properties,which could protect lithium salts from degradation in the air.The addition of lithium salts made EVOH membranes capable of lithium ion transport.The results indicated that a controllably doped EVOH@PVDC composite membrane was prepared by solution casting under ambient air conditions.It improved the conductivity of the membrane and the wettability of the electrolyte,enhancing the electrochemical performance of the membrane.The composite membrane exhibited superior high rate performance compared to PP membrane,with a discharge specific capacity of 120mA/g at a rate of 5C.At the same time,the high barrier properties of composite membrane enabled lithium metal batteries to have excellent cycle life.After 100 cycles,the specific capacity was 145mAh/g and the average coulombic efficiency could still maintain at 98%.