Method for evaluating battery safety under internal short-circuit condition, battery and battery pack whose safety is identified by internal short-circuit safety evaluation method, and method for producing the same

Abstract

The invention provides a method for evaluating the safety of a battery under an internal short-circuit condition. The battery includes: an electrode group including a positive electrode, a negative electrode, and an insulating layer for electrically insulating the electrodes, which are 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 of the invention includes: 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 by the pressure applied by a pressing tool to locally crush the insulating layer between the positive and negative electrodes, thereby causing an internal short-circuit. The contact area of the electrode group and the pressing tool during the pressing is larger than the area of a rectangle circumscribed about the foreign object. A short-circuit test is conducted at a given location inside the battery to comprehensively evaluate the safety of the battery under an internal short-circuit condition.