A solid phase electrolyte composition containing at least one conducting salt and at least one random copolymer, wherein the random copolymer comprises 5 to 95 wt.-% polymerized units of monomers (a) and 95 to 5 wt.-% polymerized units of monomers (b), based on the total weight of the copolymer, wherein (a) is at least one functionalized polyether containing at least one polymerizable C—C double bond per molecule in average, and (b) is at least one ethylenically unsaturated monomer (b1) or a mixture of at least one ethylenically unsaturated monomer (b1) and at least one ethylenically unsaturated monomer (b2) wherein (b1) is selected from the group consisting of styrene, alpha-methyl styrene, maleic anhydride, N-phenylmaleimide, C1-C4 alkyl methacrylates, C1-C22 alkyl acrylates, acrylic acid, salts of acrylic acid, C1-C4 alkylacrylic acids, salts of C1-C4 alkylacrylic acids, acrylic amides, and vinyl alcohol derivates, and (b2) is selected from the group consisting of acrylonitrile and methacrylonitrile.