Exterior Material For Power Storage Device, Production Method For Same, And Power Storage Device

Abstract: Provided is an exterior material for a power storage device, the exterior material being formed from a laminate comprising at least a base material layer, a barrier layer, and a thermally-fusible resin layer in this order from the outside, and the exterior material having a tensile strength at break of 180 MPa or greater as measured by the method below, and having a creep resistance characteristic of 10 minutes or more as measured by the method below. Each tensile strength at break in the machine direction (MD) of the exterior material for the power storage device is measured by a method compliant with the provisions of JIS K7127:1999 by using a tensile tester. The measurement conditions are such that a dumbbell 7 shape is used for a sample shape, the distance between target lines is 10 mm, the tensile speed is 0.5 mm/min, the test environment is set to a temperature of 120ºC, and the average value from three measurements is used. The exterior material for a power storage device is cut out so as to have a width of 60 mm in the transverse direction (TD) and a length of 150 mm in the MD direction and is then folded in half such that the thermally-fusible resin layer is positioned at the inside. The folded exterior material is then heat sealed using a 7 mm heat seal bar at a position 10 mm from the fold such that the thickness of the thermally-fusible resin layer is in a range of 60-95% the thickness prior to sealing. The resulting heat-sealed exterior material for a power storage device is then cut to a width of 15 mm to form a sample. Both of the mutually opposing ends of the sample are affixed to respective SUS plates (stainless steel plates) by using an adhesive, and a weight of 2 kg is applied to one side. The end on the opposite side is hung from the top of a thermostatic bath and stored in the thermostatic bath at 150ºC. The creep resistance is evaluated using the time until the sealed part opens. The SUS plates that are used have a thickness of 2 mm, a width of 30 mm, a length of 100 mm, and a weight of 42.5 g, and one side of the SUS plates is S-shaped.

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