[Problems] An object is to provide a pressure sensitive adhesive composition, a pressure sensitive adhesive sheet for batteries, and a lithium-ion battery in which the pressure sensitive adhesive is less likely to dissolve into an electrolyte solution even when the pressure sensitive adhesive sheet is in contact with the electrolyte solution.[Solution] A battery (2) comprising a pressure sensitive adhesive sheet (1), wherein: the pressure sensitive adhesive sheet is used at a site in the battery at which there is a possibility of contact with an electrolyte solution; the pressure sensitive adhesive sheet comprises a base material (11) and a pressure sensitive adhesive layer (13) laminated at one side of the base material; and the pressure sensitive adhesive layer is formed of a pressure sensitive adhesive composition comprising: a (meth)acrylic ester polymer containing a monomer having a carboxy group in a molecule as a monomer unit that constitutes the polymer; and a metal chelate-based crosslinker.