NOVELTY - A gel polymer electrolyte comprises high molecular weight polymer, ionic liquid, organic solvent, lithium salt and film forming additive, where the polymer is polyethylene oxide, polymethyl methacrylate, polyvinylidene fluoride and/or polyvinylidene fluoride-hexafluoropropylene, and the ionic liquid is 1-methyl-3-ethyl-imidazolium tetrafluoroborate, 1-methyl-3-ethyl-imidazolium hexafluorophosphate, 1-methyl-3-ethyl-imidazolium bis(trifluoromethanesulfonyl) imide and/or 1,2-dimethyl-3-propyl-imidazolium bis(trifluoromethylsulfonyl) imide.    USE - Gel polymer electrolyte for use in a lithium ion battery.    ADVANTAGE - The electrolyte has high temperature stability, safety and compatibility, and improves charging and discharging performance of the lithium ion battery.    DETAILED DESCRIPTION - A gel polymer electrolyte comprises high molecular weight polymer, ionic liquid, organic solvent, lithium salt and film forming additive, where the high molecular weight polymer is polyethylene oxide, polymethyl methacrylate, polyvinylidene fluoride and/or polyvinylidene fluoride- hexafluoropropylene, the ionic liquid is 1-methyl-3-ethyl-imidazolium tetrafluoroborate, 1-methyl-3-ethyl-imidazolium hexafluorophosphate, 1-methyl-3-ethyl-imidazolium bis(trifluoromethanesulfonyl) imide, 1,2-dimethyl-3-propyl-imidazolium bis(trifluoromethylsulfonyl) imide, N,N,N-trimethyl-n-propylammonium bis(trifluoromethanesulfonyl)imide, N-methyl-N-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide and/or N-methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide, and the forming additive is ethylene sulfite, vinylene carbonate and/or vinyl ethylene carbonate. An INDEPENDENT CLAIM is also included for a gel polymer electrolyte, which involves mixing the polymer with solvent followed by heating and stirring the mixture to obtain base body, mixing the organic solvent and a lithium salt in the ratio of film-forming additive for dissolving the lithium salt to obtain an electrolytic solution, adding the electrolytic solution slowly to the base body, stirring the mixture to obtain a transparent homogeneous liquid gel, pouring the obtained gel into a mold and removing the solvent by drying the substrate followed by de-molding to obtain an ionic liquid gel polymer electrolyte.