In this work, a sponge-like polysulfonamide (PSA)/SiO2 composite membrane is unprecedentedly prepared by the phase inversion method, and successfully demonstrated as a novel separator of lithium-ion batteries (LIBs). Compared to the commercial polypropylene (PP) separator, the sponge-like PSA/SiO2 composite possesses better physical and electrochemical properties, such as higher porosity, ionic conductivity, thermal stability and flame retarding ability. The LiCoO2/Li half-cells using the sponge-like composite separator demonstrate superior rate capability and cyclability over those using the commercial PP separator. Moreover, the sponge-like composite separator can ensure the normal operation of LiCoO2/Li half-cell at an extremely high temperature of 90 degrees C, while the commercial PP separator cannot. All these encouraging results suggest that this phase inversion based sponge-like PSA/SiO2 composite separator is really a promising separator for high performance LIBs. (C) 2018 The Chemical Industry and Engineering Society of China, and Chemical Industry Press. All rights reserved.