A flexible polymer membrane was synthesized by a emulsion polymerization with methyl acrylate (MA) and acrylonitrile (AN) as monomer and polyvinyl alcohol (PVA) as stabilizer. The physicochemical property of the resultant materials were characterized by fourier transform infrared (FTIR), scanning electron microscopy (SEM), mechanical strength measurements, thermal analysis, electrochemical impedance spectroscopy (EIS) and charge-discharge test. The results showed the mass ratio of MA to AN was 23:2, the polymer membrane possessed mechanical strength of 14.3MPa and elongation of 248%. And the ionic conductivity of the flexible electrolyte is 0.95 mS cm?1 at 25oC.The electrochemical performances were characterized using the S2 membrane as a separator, LiCoO2 and graphiteas cathode and anode, respectively. The battery initially delivers an initial discharge capacity of 140 mAh g?1 based on the LiCoO2active material in the cathode, 307 mAh g?1 based on graphite in the anode, and 132.7 mAh g?1and 323mAh g?1 after 50th cycle, respectively. The results indicate that the flexible polymer membrane demonstrates satisfactory electrochemical performances.