Packaging material for battery

A packaging material for a battery, comprising:

• a base material layer as an outer layer;
• a sealant layer as an inner layer;
• and
• a barrier layer provided between the base material layer and the sealant layer,
• wherein the sealant layer includes a first sealant layer serving as an innermost layer made of a propylene-based resin,
• wherein the propylene-based resin is a mixture of an ethylene-propylene copolymer and polyethylene,
• wherein in the ethylene-propylene copolymer,
• a ratio Mw/Mn of a weight average molecular weight Mw to a number average molecular weight Mn, measured by a gel permeation chromatography (GPC), is 1 to 7,
• a melt flow rate measured at 230° C. at a load of 2.16 kg based on JIS K7210 is 5 g/10 min to 30 g/10 min, and
• a melting point calculated by a differential scanning calorimetry analysis is 120° C. to 133° C.,
• wherein the ethylene-propylene copolymer is a metallocene catalyst-derived copolymer,
• wherein a content of the polyethylene in the mixture is 7 mass % to 20 mass %,
• wherein 65% or more and 95% or less by mass of polyethylene is polyethylene derived from a metallocene catalyst,
• wherein the sealant layer is composed of a multi-layer in which the first sealant layer, a second sealant layer composed of one or more layers, and a third sealant layer are laminated in order from an inside of the packaging material toward a barrier layer side,
• wherein the third sealant layer is made of an ethylene-propylene random copolymer,
• wherein a melt flow rate of a resin constituting at least one layer of the second sealant layer is smaller than a melt flow rate of the ethylene-propylene copolymer of the first sealant layer, and
• wherein the sealant layer is attached to the barrier layer via an adhesive layer.