Siloxane copolymer and solid polymer electrolyte comprising such siloxane copolymers

A solid polymer electrolyte composition comprising:

• (i) a copolymer comprising (a) a first monomer represented by Formula (1)
• where n is 2 to 1,000;
• m is 2 to 1,000;
• x and y are individually 1 to 100;
• p is 0 to 10;
• q is 0 to 10;
• R1 is an alkyl group having 1-10 carbon atoms, and A is an alkyl acryloyl group, an acryloyl group, a methacryloyl group, an alkyl methacryloyl group, a vinyl group, an allyl group, a styryl group, or a combination of two or more thereof;
• and (b) a second monomer chosen from a hydroxyl-substituted alkyl acrylate, a hydroxyl-substituted alkyl methacrylate, or a combination of two or more thereof;
• (ii) a plasticizer;
• and
• (iii) a salt.

A copolymer comprising:

• a first monomer of Formula (3)
• wherein n is 2 to 1,000;
• m is 2 to 1,000;
• x and y are individually 1 to 100, R1 is an alkyl group having 1 to 10 carbon atoms, and R2 is hydrogen or an alkyl of 1 to 10 carbon atoms;
• and
• a second monomer chosen from a hydroxyl-substituted alkyl acrylate, a hydroxy-substituted alkyl methacrylate, or a combination of two or more thereof.