Patent ID: 7455930

Claim:
A method for manufacturing a battery, said battery comprising: a prismatic metal case formed from a cylindrical metal case, said cylindrical case forming a negative terminal and having an open top end with a predetermined interior diameter; a sealing plate forming a lid and sealing the open end of the case, said sealing plate being radially centered in said case; said sealing plate being a positive terminal and including an axially extending exterior cylindrical wall with an exterior diameter that is smaller than the interior diameter of said case; said sealing plate further including a radially centered and axially extending protrusion; and said battery further comprising a cylindrically rolled electrode plate assembly disposed in the case; said method comprising the steps of: disposing the electrode plate assembly in said open top of said cylindrical case prior to applying said sealing plate; reducing the interior diameter of the open top end portion of the cylindrical case so as to coincide with the exterior diameter of said sealing plate; forming a radially inward protruding edge in said top end portion of said cylindrical case, said protruding edge having an internal diameter that is smaller than the external diameter of said sealing plate for supporting an axially bottom edge of said sealing plate; sealing the open end of the cylindrical case with the sealing plate by bending said top end portion of said case over an axially top edge of said exterior cylindrical wall of said sealing plate; and processing the cylindrical case by compression molding so as to have a body portion having a substantially square cross section.