Patent ID: 7501201
Filing Date: 2009-03-10
Classification: H01M,Y02E,Y02P,Y10T

Abstract:
1. A battery comprising a wound electrode group accommodated in a battery case together with electrolyte, and a sealing plate that is configured to seal an open end of the battery case, wherein the wound electrode group comprises an electrode stack that includes a lamination of a strip of positive electrode plate, a strip of negative electrode plate, and a pair of separators interposed therebetween so as to cover both surfaces of one of the positive and negative electrode plates, and when the electrode stack is wound, a difference L in length between an inner turn and an adjacent outer turn satisfies L=2tπ+(W×k), where t is a thickness of the electrode stack, W is a maximum diameter of a cross section of the wound electrode group, and k is a coefficient that is preset in accordance with expansion coefficients of active materials of the positive and negative electrode plates and is within a range from 0.005 to 0.05.