Patent ID: 7147962

Claim:
A lithium secondary battery comprising: an internal electrode body formed by winding a positive electrode and a negative electrode on an outer peripheral wall of a hollow cylindrical winding core; a cylindrical battery case containing the internal electrode body inside; nonaqueous electrolyte solution contained in said case and contacting said positive electrode and said negative electrode; at least one electrode cap sealing said internal electrode; and at least one pressure release hole positioned in at least one of first and second ends of said cylindrical case, wherein a position of said pressure release hole corresponds with a center axis of said winding core; wherein the capacity (C) of said internal electrode body is not less than 2 Ah, and said pressure release hole's sectional area (S 1 ) as well as said winding core's center hollow portion's sectional area (S 2 ) are larger than 0.3 (cm 2 ), and wherein the values given by dividing said pressure release hole's sectional area (S 1 ) and said winding core's center hollow portion's sectional area (S 2 ) by said internal electrode body's battery capacity (C) respectively (S 1 /C and S 2 /C) are both larger than 0.02 (cm 2 /Ah).