MODIFIER FOR POLYVINYLIDENE FLUORIDE, BINDER RESIN COMPOSITION FOR BATTERIES, SECONDARY CELL ELECTRODE, AND BATTERY

A modifier for polyvinylidene fluoride (PVDF), which improves the adhesion of PVDF to a metal, a binder resin composition for battery and a battery using the PVDF modifier are provided. The modifier for polyvinylidene fluoride herein is a modifier in which the peeling strength of a specific cured film to an aluminium foil is 20 g/cm or more, and the specific cured film is obtained from a mixture of 6 parts by mass of the modifier for polyvinylidene fluoride and 14 parts by mass of a polyvinylidene fluoride composition. The modifier preferably contains a macromonomer copolymer (X), obtained by polymerizing both a macromonomer (A) having unsaturated double bonds and a vinyl monomer (B) having polar groups. The macromonomer (A) is preferably a methacrylic acid ester-based macromonomer (A-1). The vinyl monomer (B) is preferably a methacrylate, and a fluoroalkyl methacrylate.