Polymer electrolytes based on the mixture of the blended polymer matrix (P(VdF-co-HFP)(Kynar 2801)/poly(vinyl acetate)(PVAc)) and the liquid electrolyte(EC/PC/1M LiClO4) were prepared by solution casting. Ionic conductivity, interfacial stability with the lithium electrode, and electrochemical stability window of the polymer electrolytes were investigated by varying the PVAc content in the matrix polymer. The ionic conductivity of the plasticized polymer electrolyte slightly decreased with the PVAc content. The ionic conductivity of the polymer electrolyte based on the Kynar 2801/PVAc (7/3, w/w) blend was 2.3×10−3 S cm−1 at 25°C. Interfacial stability between the polymer electrolyte and the lithium electrode was enhanced by blending PVAc with the Kynar 2801. The polymer electrolyte based on the Kynar 2801/PVAc (7/3, w/w) blend was electrochemically stable up to 5.0 V.