US Patent 7147962 Lithium secondary battery and manufacturing method thereof

A lithium secondary battery comprises an internal electrode body formed by winding a positive electrode and a negative electrode on an outer peripheral wall of a hollow winding core, nonaqueous electrolyte solution contained in the case, a cylindrical battery case containing this internal electrode body inside, at least one electrode cap sealing the internal electrode body, and at least one pressure release hole in a position corresponding with the center axis of the winding core.