ELECTRODE BINDER COMPOSITION, ELECTRODE COATING COMPOSITION, POWER STORAGE DEVICE ELECTRODE, AND POWER STORAGE DEVICE

Provided are an electrode binder composition that provides an electrode that exhibits high durability even when an active material that shows a large volume change is used, an electrode coating liquid composition containing the electrode binder composition, a power storage device electrode including an electrode mixture layer containing a solid of the electrode coating liquid composition, and a power storage device including the power storage device electrode. An electrode binder composition includes (A) a polyurethane, (B) a fibrous nanocarbon material having an average fiber length of 0.5 μm or more, and (C) water. The polyurethane is obtained by reacting together (a) a polyisocyanate, (b) a polyol, (c) a compound having one or more active hydrogen groups and a hydrophilic group, and (d) a chain extender. (b) contains an olefinic polyol having 1.5 or more active hydrogen groups and/or a carbonate diol having less than 6 carbon atoms between carbonate bond chains.