To realize high ion conductivity and an excellent cycle characteristic in area from a low temperature up to a high temperature by making high polymer gel electrolyte by nonaqueous electrolytic solution including a specified rate of supporting electrolyte salt and nonaqueous solvent of specified viscosity or below and acrylonitrile copolymer or polymethacrylonitrile having a methacrylonitrile unit of a specified rate.
As nonaqueous solvent having viscosity of 1.0 cP or more at an ordinary temperature, chain carbonate is suitable. By including nonaqueous solvent by 5 wt.% or more in nonaqueous electrolytic solution, heat resistance stability, oxidation-reduction stability and excellent ion conductivity at a low temperature in high polymer electrolyte are secured. Cyclic carbonate having relative dielectric constant of 20 or more may be mixed as nonaqueous solvent having viscosity exceeding 1.0 cP by a prescribed ratio and supporting electrolyte salt such as LiPF6 can be dissolved with high concentration. Amount in which copolymer including a methacrylo unit by 10 mole % or more, preferably, 60 mole % or more is included in high polymer electrolyte is suitable to be 5 to 50 wt.%, copolymer is dissolved in nonaqueous solvent and gel is formed.
HOSAKO YOSHIHIKO
YAMADA TERUYUKI
CHIBA TOMOYOSHI
KOMATSU NORIYUKI
