Patent ID: 8828591

Claim:
A nonaqueous electrolyte secondary battery comprising: a battery device composed of a positive electrode and a negative electrode which are stacked with a separator disposed in between and spirally wound; and an external packaging material for covering the battery device, in which the external packaging material is sealed around the battery device so that electrode terminals of the positive electrode and the negative electrode are protruded from the battery device to an exterior of the external packaging material from the battery device, wherein the external packaging material is composed of a laminated film having a laminated structure having two or more resin film layers stacked, wherein the laminated structure has no metallic foil, wherein at least one layer in the resin film layers of the laminated structure containing no metallic foil contains 0.1 wt % to 45 wt % of a material mixed thereinto, the material selected from the group consisting of: an oxide, a chloride, a sulfate, and a nitrate of sodium, potassium, magnesium, or calcium, a polyacrylate represented by the following general formula (—CH 2 —CH(COOM)-), where M represents sodium, potassium, magnesium, or calcium, and n represents a natural number of 100 to 5,000, and mixtures thereof, and wherein the at least one layer in the resin film layers has a thickness in the range of 10 μm to 50 μm.