TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Composition: The electrolyte film consists of lithium salt such as tetrafluoro lithium borate, hexafluoro lithium phosphate, CnF2n+1CO2Li, (FSO2)2NLi, (CF3SO2)2NLi, (C2F5SO2)2NLi, (CF3SO2-N-COCF3)Li or (R-SO2-N-SO2CF3)Li, where n is 1-4 and R is alkyl or aryl group. The electrolyte film is plasticized with non-polymerizable molten quaternary ammonium salt such as N-methyl-N-propyl piperidinium cation, N-methoxyethyl-N-methyl-N,N-diethyl ammonium cation or N,N,N-triethyl-N-methoxyethyl ammonium cation, and bis((trifluoromethyl)sulfonyl)amide anion or tetra fluoroborate anion. The weight ratio of lithium salt with respect to graft copolymer is 0.1:1-1:1 and the weight ratio of non-polymerizable quaternary ammonium salt compound with respect to graft copolymer is 0.1:1-1:1.    TECHNOLOGY FOCUS - POLYMERS - Preferred Polymer: The trunk polymer is polyvinylidene fluoride, poly(tetrafluoroethylene), poly(hexafluoropropylene) or their copolymers. Poly(quaternary ammonium salt) side chain is polymer of salt of quaternary ammonium cation having ethylenic unsaturated group and fluorine atom containing anion. The quaternary ammonium cation is 1-vinyl-3-alkyl imidazolium ion, 4-vinyl-1-alkyl pyridinium cation, 1-alkyl-3-allyl imidazolium ion, 1-(4-vinyl oxyethyl)-3-alkyl imidazolium ion, 1-vinyl imidazolium ion, 1-allyl imidazolium ion, N-allyl benzo imidazolium ion, N,N-diallyl alkyl ammonium cation, N-alkyl piperidinium cation, vinylbenzyl alkyl ammonium cation, acryloyl aminoalkyl ammonium cation or N-(meth)acryloyl oxyalkyl-N,N,N-trialkyl ammonium cation. Fluorine containing anion is bis((trifluoromethyl)sulfonyl)amide anion, 2,2,2-trifluoro-N-(trifluoromethyl sulfonyl)acetamide anion, bis((pentafluoro ethyl)sulfonyl)amide anion, bis(fluoro sulfonyl)amide anion, tetra fluoroborate anion or trifluoromethane sulfonate anion. The side chain is introduced alternately using molten ammonium salt. Ethylenic unsaturated monomer having reactive functional group (A) is graft copolymerized to form trunk polymer. Then, molten ammonium salt having reactive functional group (B) is reacted to form graft copolymer. Functional group (B) forms a coupling group by the reaction with the functional group (A) of the produced side chain of graft copolymer. The combination of reactive functional groups (A,B) is combination of isocyanate, hydroxyl or amino group, glycidyl and carboxyl group. Ethylenic unsaturated monomer having reactive functional group (A) is glycidyl (meth)acrylate or block copolymer of 2-isocyanate ethyl (meth)acrylate, and molten ammonium salt having reactive functional group (B) is salt of N-(3-carboxy propyl)-N-N-N-trimethyl-ammonium cation and bis(trifluoro methylsulfonyl)imide anion or salt of hydroxyethyl trimethyl-ammonium cation and bis(trifluoro methylsulfonyl)imide anion. EXAMPLE - Polyvinylidene fluoride (in g) (2) and N-methyl-2-pyrrolidone (NMP) (30) were mixed in a flask. N-methacryloyl oxyethyl-N,N,N-triethyl ammonium-bis(trifluoro methyl sulfonyl)imide salt (128) was added and stirred. Argon gas was blown and 4,4'-diphenyl-2,2'-bipyridyl (0.2) dissolved in NMP and cupric chloride solution (0.04) were added and reacted at 90degreesC for 20 hours. Ethanol aqueous solution (500 ml) was added after reaction completion. The obtained precipitate was separated by filtration and dissolved in NMP (30). Graft copolymer (8.8) was obtained after vacuum drying the precipitate at 70degreesC. An electrolyte film was formed using graft copolymer and lithium salt of bis(trifluoro methyl sulfonyl)imido acid in a weight ratio of 7:3. The electrolyte film had thickness of 30 microns, ionic conductivity of 26x10-3 S/cm and peel strength of 13 MPa.