Solid polymer electrolytes for lithium cells

This paper reports on ionic conductivity, mechanical characteristics, thermal stability, and electrochemical stability of solid polymer electrolytes (SPEs) that use a cross-linked poly(ethylene oxide) and a cross-linked ethylene oxide copolymer both containing a plasticizer. We obtained the SPEs that have a high ionic conductivity of 2.4 × 10−3 S cm−1 at 20 °C, a mechanical strength that creates no problems in practical use, and higher thermal stability than liquid electrolytes. Batteries using these SPEs were manufactured and submitted to various tests. The results showed that the low-temperature and rate characteristics of these batteries were comparable with those of liquid electrolyte batteries. The results of loading, bending and twisting tests indicated that no internal shorting of the batteries occurred. These batteries did not swell at high temperatures at which liquid electrolyte batteries usually do.