COPOLYMER FOR ELECTRODE BINDER AND LITHIUM ION SECONDARY BATTERY

To provide a copolymer for a binder for an electrode and a slurry for a lithium ion secondary battery using the copolymer for an electrode binder, in which the peel strength of an electrode active material layer to a collector is high while suppressing the generation of aggregates in a slurry containing the electrode active material and suppressing the generation of cracks in the electrode active material layer formed on the collector. The copolymer for an electrode binder comprises a structural unit derived from a monomer (A) represented by formula (1), a structural unit derived from a monomer (B) which is at least 1 kind selected from the group consisting of (meth)acrylic acid and its salts, a structural unit derived from a monomer (C) represented by formula (2), a structural unit derived from a hydrophilic monomer (D) having only 1 ethylenically unsaturated bond and an n-octanol/water partition coefficient LogP of < 2.0, and a structural unit derived from a hydrophobic monomer (E) having only 1 ethylenically unsaturated bond and an n-octanol/water partition coefficient LogP of ≥ 2.0.