TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: Lithium salt comprises at least one of lithium chlorate, lithium borofluoride, lithium hexafluorophosphate, lithium triflate salt, lithium bis(trifluoromethylsulfonyl)amide and lithium triflate.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preparation of the comb-shaped polymer which comprises:(A) processing substitution reaction for 3,3-di(brooethyl)oxetane with polypropylene oxide to prepare macromolecule of 3,3-bi(polypropylene oxide) oxetane;(B) opening loop and homopolymerizing obtained macromolecule; or(C) processing substitution reaction for 3,3- di(bromoethyl) oxetane with polypropyleneoxide to prepare macromolecule of 3, 3-bis(polypropylene oxide) oxetane;(D) copolymerizing macromolecule with oxetane and/or tetrahydrofuran; or(E) opening loop and homopolymerizing 3,3-bi(polypropylene oxide) oxetane;(F) processing substitution reaction for obtained polymer and polypropylene oxide to prepare comb-shaped polymer with polypropylene oxide repeating unit on the side chain; or(G) copolymerizing 3, 3-di(brooethyl) oxetane with oxetane and/or tetrahydrofuran; and(H) processing substitution reaction for obtained polymer with polypropylene oxide to prepare the comb-shaped polymer with polypropylene oxide repeating unit on the side chain.Preferred Method: The substitution reaction is processed in condition of strong base with pH value not lower than 13.5. The preparation method comprises uniformly mixing polymer matrix, lithium salt and solvent; pouring mixing solution in step to mold, and drying to obtain polymer electrolyte; processing radiation crosslinking for obtained polymer electrolyte through gamma ray or UV ray to obtain solid polymer electrolyte. Preferred Components: Main chain repeating unit further comprises oxetane unit and/or a tetrahydrofuran unit. Side chain is connected to propylene oxide unit in main chain repeating unit. Main chain repeating unit is propylene oxide unit; or main chain repeating unit comprises at least one of two of the propylene oxide unit, oxetane unit and the tetrahydrofuran unit. Side chain comprises 1-15repeating units. Length of the side chain comprises 3-5 repeating units. Molar ratio of repeating unit connected with side chain to all the repeating units of main chain is 1:1-1:10. Molar ratio of repeating unit connected with side chain to all the repeating units of main chain is 1:1-1:5.    TECHNOLOGY FOCUS - POLYMERS - Preferred Components: The weight part of lithium salt is 1-120 (preferably 5-80)% of weight part of polymer matrix.