Patent ID: 7910242

Claim:
A nonaqueous electrolyte secondary battery in which an electrode plate group including a positive electrode plate and a negative electrode plate which have a positive electrode mixture layer formed on a positive electrode current collector to contain a positive electrode active material and a negative electrode mixture layer formed on a negative electrode current collector to contain a negative electrode active material, respectively, and are spirally wound or stacked with a separator interposed therebetween is encapsulated in a battery exterior packaging body with an electrolyte, wherein the battery exterior packaging body includes a gas releasing valve for releasing gas in the battery exterior packaging body to the outside when a gas pressure in the battery exterior packaging body reaches a working pressure of the gas releasing valve, wherein the battery exterior packaging body is formed to be deformable, in a temperature range which is lower than a decomposition temperature of the positive electrode active material, when the gas pressure in the battery exterior packaging body is lower than the working pressure of the gas releasing valve, wherein the battery exterior packaging body has a cylindrical shape, and a tensile strength of the battery exterior packaging body is smaller than PR/t where the working pressure of the gas releasing valve is P, an inner diameter of the battery exterior packaging body is R and a thickness of the battery exterior packaging body is t, and wherein the battery exterior packaging body is made of iron, nickel, or stainless steel, or the battery exterior packaging body is made of aluminum or aluminum alloy.