SiO2/vinylidine fluoride-hexnfluropropene copolymer[P(VDF-HFP)] composite porous polymer electrolytes were prepared by phase inversion induced by water vapor．The influence of nano-SiO2 on the porous structure and performance of the porous polymer electrolytes was studied．The results show that when the weight ratio of SiO2 to polymer is about 0.05

the porous polymer electrolytes have improved conductivity and interfaeial stability against lithium metal electrodes；but when the amount of SiO2 is further increased

serious aggregation of nano—SiO2 can be found in the pores

and the performance of the porous polymer electrolytes is reduced．