NOVELTY - Method for preparing solid-state lithium-ion batteries, by adding positive and negative electrode active material for lithium ion, conductive agent and alginate to water to obtain paste, coating the paste on the surface of the positive and negative electrode collector and drying respectively, mixing lithium salts, polyoxyethylene and plasticizer uniformly to obtain gel-like mixture, molding, and drying to obtain solid electrolyte, stacking, and sealing battery case to obtain solid-state lithium-ion batteries.    USE - The method is useful for solid-state lithium-ion batteries (claimed).    ADVANTAGE - The method increases wettability between solid electrolyte and electrodes improves performance of solid-state electrochemical cells and reduces internal resistance of the positive and negative electrode contact between active layer and the solid electrolyte.    DETAILED DESCRIPTION - Method for preparing solid-state lithium-ion batteries, involves (a) adding 36-38.4 %mass positive electrode active material for lithium ion, 0.8-2 %mass conductive agent and 0.8-2 %mass alginate to water, and stirring the mixture to obtain positive electrode paste, coating the paste on the surface of the positive electrode collector and drying to obtain positive electrode, where the paste comprises 60 %mass water, (b) adding 36-38.4 %mass negative electrode active material for lithium ion, 0.8-2 %mass conductive agent and 0.8-2 %mass alginate to water, and stirring the mixture to obtain negative electrode paste, coating the paste on the surface of the negative electrode collector and drying to obtain negative electrode, where the paste comprises 60 %mass water, (c) mixing 5-20 %mass lithium salts, 5-20 %mass polyoxyethylene and 5-50 %mass plasticizer uniformly to obtain gel-like mixture, adding the gel-like mixture into mold, and drying the molded material to obtain solid electrolyte, and (d) stacking the positive electrode, the solid electrolyte, the negative electrode in order, and sealing battery case to obtain solid-state lithium-ion batteries.