Zeolitic imidazolate framework-67 based separator for enhanced high thermal stability of lithium ion battery

Abstract

The separator is a crucial part of lithium ion battery, such as preventing internal short-circuit and offering ion-conducting routes. However, conventional separators are usually based on polymer materials, which show the low thermal stability and poor electrolyte wettability, thus greatly restricting the electrochemical performance of lithium ion battery, especially for high-temperature safety. In this study, zeolitic imidazolate framework-67 (ZIF-67) was employed as separator via direct coating onto the surface of LiNi0.5Co0.2Mn0.3O2 electrode through a facile blade-coating technique. Comparing with the conventionally used polypropylene (PP) separator, the new ZIF-67 based separator features superior electrolyte uptake (154%), higher ionic conductivity (0.00164 S cm−1) and thermal stability. Notably, at a high temperature of 55 °C, the cell with ZIF-67 based separator exhibits nearly 2 times higher capacity retention than the PP separator (ZIF-67: 61.20% vs PP: 35.09%). In view of its advantages, the ZIF-67 based separator shows significant potential in the design of safe lithium ion batteries.