(JP11504173-X)      Crosslinkable polyether copolymer comprises: (A) 1-99 mol.% repeating units derived from a monomer of formula (I), (B) 99-1 mol.% repeating units derived from a monomer of formula (II), and 0-15 mol.% repeating units derived from a monomer which contains one epoxy group and at least one reactive functional group and has weight average molecular weight = 104-107. In (I), R1 = divalent organic group.    Also claimed is a solid polymer electrolyte containing the polymer, an electrolyte salt compound, aprotic solvent, and as plasticiser metal salts and derivatives of linear or branched polyalkylene glycols with number average molecular weight of 200-500 and metal salts of the derivatives.    USE -   Used to fabricate solid polymer electrolyte which can then be applied to the production of batteries (claimed).    ADVANTAGE -   Solid polymer electrolytes made with the polymer have superior processability, mouldability, mechanical strength, softness and heat resistance, and good ionic conductivity.    (US6201071-B1)      Crosslinkable polyether copolymer comprises: (A) 1-99 mol.% repeating units derived from a monomer of formula (I), (B) 99-1 mol.% repeating units derived from a monomer of formula (II), and 0-15 mol.% repeating units derived from a monomer which contains one epoxy group and at least one reactive functional group and has weight average molecular weight = 104-107. In (I), R1 = divalent organic group.    Also claimed is a solid polymer electrolyte containing the polymer, an electrolyte salt compound, aprotic solvent, and as plasticiser metal salts and derivatives of linear or branched polyalkylene glycols with number average molecular weight of 200-500 and metal salts of the derivatives.    USE -   Used to fabricate solid polymer electrolyte which can then be applied to the production of batteries (claimed).    ADVANTAGE -   Solid polymer electrolytes made with the polymer have superior processability, mouldability, mechanical strength, softness and heat resistance, and good ionic conductivity.