ELECTRICITY STORAGE DEVICE CLADDING

A packaging material for a power storage device, comprising at least: a substrate layer; a metallic foil layer with an anti-corrosion treatment layer being disposed on one face or both faces thereof; and a sealant layer in this order, wherein a sealant layer includes a resin layer containing a polypropylene-based resin (A) and an incompatible component (B) incompatible with a polypropylene-based resin (A), and as for loss tangent tan δ obtained by dynamic viscoelasticity measurement at a frequency of 1.0 Hz, the sealant layer has a maximal value of tan δ at −30 to 30° C., and in addition, a ratio (II/I) of the maximal value (II) of tan δ at −30 to 30° C. to a value (I) of tan δ at −50° C. is 2.50 or more.