Patent ID: 6355372
Filing Date: 2002-03-12
Classification: H01M,Y02E

Abstract:
A non-aqueous electrolyte secondary cell comprising:a positive electrode comprising a positive metallic foil capable of serving as a positive current collector and a positive active material layer formed on opposite sides of said positive metallic foil, said positive active material layer formed of a lithium complex oxide; a negative electrode formed of a negative metallic foil capable of serving as a negative current collector and a negative active material layer formed on opposite sides of said negative metallic foil, said negative active material formed of a carbon material capable of being doped with a lithium ion, a metal lithium, or a lithium alloy; a separator disposed between said positive electrode and said negative electrode; said positive electrode, negative electrode and said separator being spirally wound together into a spirally wound structure, wherein said positive active material layer and said negative active material layer are arranged opposite to each other through said separator; a cleavage valve which is realized by bonding a metal foil to an opening in the cell, said metal foil being cleft due to rise in the internal pressure in the cell to release the pressure and wherein the valve comprises a thin-walled portion formed in said metal foil, said thin-walled portion having a thickness less than the thickness of said metal foil, and said thin-walled portion disposed radially internally of said opening in said cell; and wherein a value K corresponding to the internal cell volume in cm3 divided by the area of the opening in cm2 is such at 40&lE;K&lE;350 cm.