BINDER COMPOSITION FOR POWER STORAGE DEVICES, SLURRY FOR POWER STORAGE DEVICE ELECTRODES, POWER STORAGE DEVICE ELECTRODE, AND POWER STORAGE DEVICE

A binder composition for an electrical storage device may include: a polymer (A); and a liquid medium (B). When a total of repeating units in the polymer (A) is defined as 100 mass %, the polymer (A) may contain 15 mass % to 64 mass % of a repeating unit (a1) derived from an unsaturated carboxylic acid ester having an aliphatic hydrocarbon group (except an unsaturated carboxylic acid ester having an alicyclic hydrocarbon group), and 35 mass % to 84 mass % of a repeating unit (a2) derived from an aromatic vinyl compound, and tan δ (loss elastic modulus/storage elastic modulus) in dynamic viscoelasticity of the polymer (A) expresses only one peak top in a range of from −50° C. to 0° C. and one peak top in a range of from 50° C. to 150° C.