Patent ID: 8444717

Claim:
A method for evaluating the safety of a battery under an internal short-circuit condition, the battery comprising: an electrode group comprising a positive electrode, a negative electrode, and an insulating layer for electrically insulating the positive electrode and the negative electrode from each other, the positive electrode, the negative electrode and the insulating layer being wound or laminated; an electrolyte; a housing for housing the electrode group and the electrolyte; and a current-collecting terminal for electrically connecting the electrode group and the housing, the method comprising: placing a foreign object at a location inside the electrode group of the battery where the positive electrode and the negative electrode face each other; and pressing the location where the foreign object is placed by the pressure applied by a pressing tool, to locally crush the insulating layer interposed between the positive electrode and the negative electrode, thereby causing an internal short-circuit, wherein the contact area of the electrode group and the pressing tool during the pressing is larger than the area of a rectangle circumscribing the foreign object, and the part of the pressing tool to come into contact with the electrode group comprises a material with a heat conductivity of 15 W/m·K or less.