Preparation and performance of polypropylene separator modified by SiO2/PVA layer for lithium batteries

Abstract

An aqueous silica (SiO2) dispersion was prepared by using silica as ceramic particles, polyvinyl alcohol (PVA) as a binder and deionized water as a dispersion medium. A SiO2 ceramic layer was applied to the surface of the polypropylene (PP) separator by dip coating. The separators before and after modification were characterized by XRD, SEM, DTA, lyophilic performance test, contact angle test and heat resistance test. The separators were assembled into lithium-ion batteries for electrochemical performance test. The results show that after the successful introduction of SiO2/PVA coating on the surface of PP separator, the lyophilic and heat resistance and electrochemical performance of PP separator have been improved significantly. The battery rate performance and cycle performance are significantly improved. Especially the capacity retention rate of the original separator was only 75.79% at 100 charge-discharge times, and that of the modified separator was as high as 87.18%.