Exterior material for power storage device, production method for same, and power storage device

A method for manufacturing an exterior material for electrical storage devices, comprising the step of laminating at least a base material layer, a barrier layer and a heat-sealable resin layer in this order from the outside to obtain an exterior material for electrical storage devices which includes a laminate, wherein

• with respect to a test piece A having a width of 15 mm in a transverse direction and obtained by heat-sealing the heat-sealable resin layers of the exterior material for electrical storage devices under conditions of a temperature of 190° C., a surface pressure of 1.0 MPa and 3 seconds, sealing strength in an environment at 60° C., A (60° C.) is larger than sealing strength in an environment at 25° C., A (25° C.), where the sealing strength is a maximum strength (N/15 mm) when heat-sealed portions of the heat-sealable resin layers of the test piece A are peeled in a direction of 180 degrees under conditions of a chuck-to-chuck distance of 50 mm and a tension speed of 5 mm/min using a tensile tester.