Packaging material for power storage device, method for producing the same, and power storage device

Abstract

To provide a packaging material for a power storage device that includes a heat-fusible resin layer containing polypropylene and polyethylene, in which whitening and deterioration in insulation properties due to molding are suppressed.SOLUTION: A packaging material for a power storage device is constituted of a laminate comprising at least a base material layer, a barrier layer, and a heat-sealable resin layer in this order from an outer side to an inner side. The heat-sealable resin layer contains polypropylene and polyethylene. A sea-island structure is observed in a cross-sectional image obtained using a scanning electron microscope with respect to a cross section in a thickness direction parallel to a TD of the heat-sealable resin layer. The cross-sectional image is obtained within a range of 12.5% of a thickness from a surface opposite a barrier layer side of the heat-sealable resin layer when a total thickness of a layer located closer to the inner side than the barrier layer is taken as 100%. In the cross-sectional image, a ratio of a total number of island portions having an area of 0.02 μm2 or less among the island portions to a total number of island portions of the sea-island structure is 80.0% or more.SELECTED DRAWING: None

Images