Patent ID: 7687196
Filing Date: 2010-03-30
Classification: H01M,Y02P

Abstract:
1. A method for manufacturing a prismatic battery, the prismatic battery comprising an electrode plate group comprising a positive electrode plate, a negative electrode plate and a separator, an electrolyte and a battery case for accommodating the electrode plate group and the electrolyte; and the electrode plate group is an electrode plate group in which the positive electrode plate and the negative electrode plate are stacked with the separator interposed therebetween and the stack is wound; the method comprising: (i) forming a stack by stacking the positive electrode plate and the negative electrode plate with the separator interposed therebetween; winding the stack to form a cylindrical configuration, and pressing the cylindrical configuration so as to have a rectangular, polygonal or oval cross sectional shape; (ii) accommodating the pressed electrode plate group and the electrolyte in the battery case having a side face provided with a flat surface portion, and a corner portion of the battery case for connecting adjacent flat surface portions with a curved surface; and (iii) sealing an opening portion of the battery case with a sealing member; wherein in the step (i), the radius of curvature of a cross section of a corner portion of the electrode plate group is larger than the radius of curvature of the inner circumference of the corner portion in the battery case, detecting a winding end portion of the electrode plate group when the winding end portion is positioned on a detection sensor side relative to an innermost winding of the wound stack so that the winding end portion is located to be the corner portion when pressed, and pressing the electrode plate group so that the winding end portion of the electrode plate group is located at the corner portion of the electrode plate group after being pressed, wherein in the step (ii), the pressed electrode plate group is accommodated in the battery case in such a manner in which the winding end portion of the pressed electrode plate group is located at the corner portion of the battery case, the method further comprising the following step (a) between the steps (ii) and (iii), (a) a step of forming a battery case comprising a cylindrical head portion, a prismatic body portion and a transition portion located between the body portion and the head portion by forming the vicinity of the opening portion of the prismatic battery case to have a cylindrical shape, wherein in the step (a), the transition portion having a continuous curved surface is formed from a first boundary between the corner portion of the battery case and the transition portion toward a second boundary between the head portion and the transition portion, and an angle of a line connecting a center of the first boundary to the second boundary on the continuous curved surface by the most direct way with respect to a direction of a central axis of the battery case is in the range from 14° to 22°.