Binder composition for lithium ion secondary battery negative electrode, slurry composition for lithium ion secondary battery negative electrode, negative electrode for lithium ion secondary battery, and lithium ion secondary battery

摘要

The purpose of the present invention is to provide a binder composition for the negative electrode of a lithium ion secondary cell with which a lithium ion secondary cell having excellent cycle properties can be provided, swelling of the cell under high temperatures can be controlled, and high-temperature shelf life can be guaranteed. This binder composition for a negative electrode of a lithium ion secondary cell comprises water and polymer particles containing 50 to 80 mass% of aromatic vinyl monomer units, 20 to 40 mass% of aliphatic conjugate diene monomer units, 0.5 to 10 mass% of ethylenic unsaturated carboxylic acid monomer units, and 0.1 to 3 mass% of (meth)acrylic acid ester monomer units. The THF degree of swelling of the polymer particles is 3 to 10 times.