| abstract |
An exterior material for power storage devices comprising at least a base layer, a metal foil layer having a corrosion-preventing treatment layer formed on one or both sides thereof, and a sealant layer in this order, wherein the sealant layer is a polypropylene resin (A) and a polypropylene resin A resin layer containing (A) and an incompatible component (B) is provided, and the sealant layer has a maximum value of -30 to 30°C in the loss tangent tan δ obtained by dynamic viscoelasticity measurement at a frequency of 1.0 Hz. It has, and the ratio (II/I) of the maximum value (II) of tan δ in -30 to 30°C to the value (I) of tan δ in -50°C is 2.50 or more. |