Preparation of silica glass films on the surface of polypropylene microporous membrane separators by dip coating with polysilazane and their application in lithium-ion batteries

Abstract

Silica glass films were coated on polypropylene (PP) microporous membrane separators by a dip coating method, in which polysilazane diluted with xylene was used as precursor material for the silica glass. Scanning electron microscopy (SEM) observation showed that the silica glass films were uniformly coated on the separator surfaces, while Fourier transform infrared spectroscopy (FTIR) measurements revealed that almost all polysilazane in the as-prepared films was converted to silica after heating at 100°C in a steam oven. In addition, the thermal shrinkage properties of the PP microporous membrane separators were significantly improved after coating. Electrochemical studies of an Al ion-doped lithium manganese oxide cathode were conducted to evaluate the coating effect on the properties of the PP microporous membrane separator. The results revealed that rechargeable capacity, cycle stability, and rate performance of the lithium-ion batteries were not changed by the silica glass coating.