In this study, a novel ceramic-polyethylene (PE) composite separator is designed and achieved by a very facile preparation strategy for high-safety lithium-ion batteries (LIBs). The optimized ceramic slurry composed of Al2O3 and polyvinyl pyrrolidone (PVP) is coated on one side of PE separator in an economically efficient way to form the novel Al2O3/PVP-PE separator. It is found that the superior PVP binder can improve the adherence of heat-resistant Al2O3 ceramic powders on the PE substrate, which significantly enhances the thermal stability of the optimized separator. The Al2O3/PVP-PE separator shows negligible shrinkage at a high temperature of 180 °C after 30 min thermal treatment. In addition, the prepared Al2O3/PVP-PE separator shows excellent wettability with electrolyte, large porosity and high liquid storage capacity, which are quite beneficial to the ionic conductivity and charge storage kinetics. Furthermore, LIBs (LiFePO4/graphite) assembled with the optimized Al2O3/PVP-PE separator shows superior electrochemical performance than LIBs assembled with bare PE separator. This study provides insight into the practical application and commercialization of novel Al2O3/PVP-PE separator for high-safety LIBs with improved electrochemical performance.