TECHNOLOGY FOCUS - POLYMERS - Preferred Monomer: The monomer providing unit (I) is (meth)acrylonitrile, an (alpha-alkyl)acrylic acid, an alkyl(alpha-alkyl)acrylate, a fluoroalkyl(alpha-alkyl)acrylate, a fluoroalkyl(alpha-fluoroalkyl)acrylate, a vinyl ester, a vinylalkyl ether, an allyl alkyl ether, an allyl ester, vinyl alcohol, vinyl chloride, vinylidene chloride, and a cyclic olefin.Preferred Polymer Gel: The polymer gel further comprises a compound providing unit (III) derived from a plasticizing compound having a polymerizable group.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Compound: (IIa) is represented by the formula (1) and (2) and has a weight average molecular weight of 5000 or less.H2C=C(R)COO(CH2CH2O)n-COC(R)=CH2 (1)H2C=C(R)COO((CH2CH2O)p-(CH2CH(R1)Oq-(X)r-(CH2CH2O)p)COC(R)=CH2 (2)n = 1-23;R = 1-4C alkyl;R1 = H, a methyl group;X = bisphenol group;p = 16 or smaller;q = 34 or smaller;r = 0 or 1.(IIb) is represented by the formula (3),(4) and (5).H2C=C(R)COO(CH2CH(R1)O)s-R2 (3)H2C=CHCH2O-(CH2CH2O)x-(CH2CH(R1)O)y-R3 (4)H2C=CHCOO(CH2CH2O)x-(CH2CH(R1)O)y-R2 (5)R = H, 1-4C alkyl;R1 and R2 = H or a methyl group;s = 1-100.x and y = mole percents totaling 100 %, in which x = 100 % and y = 0 %, or x at most 50 % and y at least 50 % or x =0 % and y = 100 %, or x at least 50 % and y at most 50 %.A compound providing unit (III) is benzylmethacrylate, isobornyl-methacrylate, diethylaminoethylbenzyl methacrylate chloride, diethylaminoethyl-methacrylate, dimethylaminoethylmethyl-methacrylate chloride, trifluoroethylmethacrylate, cyclohexyl-methacrylate, 2-methacryloyloxyethylphthalate, 2-methacryloxyloxyethylhexahydrophthalate, butylepoxystearate, and dioctylepoxyhexahydrophthalate.Preferred Electrolyte: The electrolyte contains lithium salt such as CF3SO3Li, C4F9SO3Li, (CF3SO2)2NLi, (CF3SO2)3CLi, LiBF4, LiPF6, LiClO4, and LiAsF6.Preferred Solvent: The nonaqueous solvent is a cyclic carbonate, an acyclic carbonates, a cyclic ester, an amide compound, and a nitrile compound.