NOVELTY - Mixed solution of poly(vinylidene fluoride-co-hexafluoropropylene) and titania is coated on active material surface layers of positive and negative pole plates of battery, and solvent is volatized to form composite porous films on pole plates. The positive and negative pole plates are assembled with membrane, and liquid-state electrolyte is poured in the assembled battery core. The battery core is heated and baked to form gel form composite porous film. Then, the battery core is pre-charged and capacity is graded to form gel polymer battery.    USE - Manufacture of gel polymer lithium ion battery.    ADVANTAGE - The gel polymer lithium ion battery is easily and economically manufactured with excellent cycle characteristics. The porous film is manufactured with high porosity and fluid absorption rate.    DETAILED DESCRIPTION - Poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) powder is dissolved in an organic solvent to form PVDF-HFP solution. The organic solvent is chosen from dimethylformamide, dimethyl sulfoxide, acetone, N-methyl pyrrolidone and tetrahydrofuran. The mass ratio of hexafluoropropylene to vinylidene fluoride in PVDF-HFP powder is 6-20:100. Tetrabutyl titanate is mixed and stirred with a solvent and a complexing agent to form precursor solution. The mass ratio of tetrabutyl titanate to complexing agent is 1.7-6.8:1. The complexing agent is acetyl acetone. The solvent is butanol, glycol or methyl benzene. PVDF-HFP solution is uniformly mixed with the precursor solution, and organic solvent and hydrochloric acid (5-25%) are added, uniformly mixed and aged to form PVDF-HFP-titania mixed solution. The amount of PVDF-HFP in mixed solution is 1-20 %mass. The organic solvent is dimethylformamide, dimethyl sulfoxide, acetone, N-methyl pyrrolidone and/or tetrahydrofuran. The mixed solution is coated on active material surface layers of positive and negative pole plates of battery, and the solvent is volatized to form composite porous films on pole plates. The positive and negative pole plates are assembled with membrane, and liquid-state electrolyte is poured in the assembled battery core. The battery core is heated and baked to form gel form composite porous film. Then, the battery core is pre-charged and capacity is graded to form gel polymer battery.