Power-cell packaging material

A method for producing a battery packaging material comprising the step of:

• laminating at least a base material layer, a metal layer, an insulating layer, and a sealant layer in this order to obtain a laminate, wherein:
• the insulating layer is formed of a resin composition containing a modified polyolefin resin modified with an unsaturated carboxylic acid or acid anhydride thereof;
• in the step, the insulating layer having a hardness, when measured by using a nanoindenter and pressing the indenter 5 μm into the insulating layer from a cross-section of the laminate in the laminating direction thereof, ranging from 10 MPa to 300 MPa is formed;
• and
• in the sealant layer, an elastic modulus, when measured by using a nanoindenter and pressing an indenter 5 μm into the sealant layer from a cross-section of the laminate in the laminating direction thereof, ranges from 100 MPa to 1000 MPa.