Binder aqueous solution for lithium-ion battery electrode, slurry for lithium-ion battery electrode, lithium-ion battery electrode, and lithium-ion battery

A binder aqueous solution for a lithium-ion battery electrode, comprising:

• a water-soluble polymer (A), the water-soluble polymer (A) being a polymer of a monomer group containing, with respect to 100 mol % of the monomer group, 10 mol % to 60 mol % of a hydroxyl group-containing vinyl ether (a) and 40 mol % to 90 mol % of (Meth)acrylamide Group-containing Compound (b),
• the hydroxyl group-containing vinyl ether is represented by general formula (1):
• H2C=CH—R—OH (1),
• wherein in the general formula (1), R represents unsubstituted oxyalkylene group having 1 to 5 carbon atoms, or
• general formula (2),
• wherein in the general formula (2), q is an integer of 1 to 3, and n is an integer of 1 or more.