TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The inorganic lithium salt is chosen from lithium hexafluorophosphate, lithium tetrafluoroborate, lithium perchlorate and lithium hexafluoroarsenate, preferably lithium tetrafluoroborate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The monomer (A) is a divinyl compound, di(meth)acrylate compound, or combination of di(meth)acrylate compound and compound having a vinyl group and a (meth)acryl group, preferably ethylene glycol di(meth)acrylate. The monomer component further contains monomer (B) (0.05-3 mol with respect to 1 mol of monomer (A)) having a fluoroalkyl group and radically polymerizable double bond(s) in a molecule, and monomer (C) having a substituent including ether bond and radically polymerizable double bond(s) in molecule. The monomer (B) is a compound having a vinyl group or a (meth)acryl group, a fluoroalkyl-containing compound of formula: CH=C(-R1)-C(=O)-O-R2 (I), or carbonyl group-containing compound of formula: CH=C(-R1)-C(=O)-O-(CH2)m-(CF2)n-CF2-X (II). The polymerization initiator is an azo polymerization initiator chosen from 2,2'-azobisisobutyric acid dimethyl ester and 2,2'-azobis(2,4,4-trimethyl pentane). The solvent is chosen from benzene, toluene, xylene, ethylbenzene, tetralin, n-hexane, n-heptane, mineral spirit, cyclohexane, methyl chloride, methyl bromide, methyl iodide, methylene dichloride, chloroform, carbon tetrachloride, trichloroethylene, perchlorethylene, ortho-di chlorobenzene, ethyl acetate, butyl acetate, methoxybutyl acetate, methyl-cellosolve acetate, ethyl cellosolve acetate, propylene glycol monomethyl ether acetate, diethyl ether, tetrahydrofuran, 1,4-dioxane, methyl cellosolve, ethyl cellosolve, butyl cellosolve, propylene glycol monomethyl ether, acetone, methyl ethyl ketone, methyl isobutyl ketone, di-n-butylketone, cyclohexanone, methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, tert-butanol, 2-ethylhexyl alcohol, benzyl alcohol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethylsulfoxide and N-methyl-2-pyrrolidone, preferably methyl isobutyl ketone and tetrahydrofuran. The electrolytic salt is inorganic lithium salt and organic lithium salt chosen from lithium trifluoromethane sulfonate, tris(trifluoromethanesulfonyl)methide, bis(trifluoromethanesulfonyl)imide, lithium bisperfluoroethylsulfonyl imide and lithium compound (LiN(SO2CF3)(SO2C4F9)), and its derivative(s), preferably bis(trifluoromethanesulfonyl)imide.R1=H or methyl;R2=2-12C fluoroalkyl group optionally substituted by hydroxy;X=H or fluoro;m=1 or 2;andn=0-5.    TECHNOLOGY FOCUS - POLYMERS - Preferred Process: The highly-branched polymer and electrolytic salt are dissolved in a solvent, to obtain polymer-electrolyte precursor solution. The polymer electrolyte is obtained by removing the solvent from the polymer electrolyte precursor solution.