Patent ID: 11552297

Abstract:
Provided is a binder composition for lithium ion secondary battery electrode-use that reduces internal resistance of a lithium ion secondary battery while also providing the lithium ion secondary battery with excellent life characteristics. The binder composition contains a copolymer X and a solvent. The copolymer X is obtained from a monomer composition X that contains at least 20.0 mass % and no greater than 75.0 mass % of an ethylenically unsaturated carboxylic acid compound (A) composed of either or both of an ethylenically unsaturated carboxylic acid and an ethylenically unsaturated carboxylic acid salt, and at least 20.0 mass % and no greater than 75.0 mass % of a copolymerizable compound (B) that has an ethylenically unsaturated bond and a solubility of at least 7 g in 100 g of water at 20° C. The copolymer X has a degree of swelling in electrolysis solution of less than 120 mass %.