Abstract: The Al₂O₃/SiO₂/PAN composite membrane was prepared as the separator for Li-ion batteries in order
to replace the traditional microporous polyolefin membrane. The composite membrane has high porosity，and can be well wetted by the liquid electrolyte. The ion conductivity of the membrane is easily achieved by absorbing the liquid electrolyte due to the high capillary effect. The amphoteric character of Al₂O₃/SiO₂ can scavenge acidic hydrogen fluoride，which is inevitably present in the LiPF₆-based elect rolytes used currently in the Li-ion batteries. With the composite membrane as a separator，the graphite/ cathode cell exhibited a good capacity retention. It is also found that the Li-ion cell fabricated in this manner not only has stable capacity retention and high temperature safety，but also shows good high-rate performance and overcharge proof performance.