Blending with poly(vinyl alcohol) (PVA) and poly(oxyphenylene sulfone) (PESf) has been investigated to improve the properties of a polymer electrolyte based on a poly(ethylene oxide) (PEO) matrix. The composite electrolyte shows a high ionic conductivity of 0.83 × 10−3 S cm−1 at 60 °C due to the significant inhibition of crystallization caused by the synergistic effects of PVA and PESf. The symmetrical cell Li/CPE/Li is continuously operated for at least 200 hours at a current density of 0.1 mA cm−2 without the enhancement in the polarization potential. In addition, the all-solid-state LiFePO4/CPE/Li cells exhibit small hysteresis potential (about 0.10 V), good cycle stability and excellent reversible capacity (126 mA h g−1 after 100 cycles).
