Patent ID: 6632559
Filing Date: 2003-10-14
Classification: H01M,Y02E

Abstract:
A safety device for a closed battery comprising:a positive electrode lid attached at one end of an outer container, said positive electrode lid including a pressure plate forming the innennost lid adapted and constructed to be electrically connected to a positive electrode of an electrode member through a positive electrode lead; a shield plate consisting of a clad metallic plate comprising an intermediate lid and which is electrically connected to said pressure plate through a central contacting portion; and a sealing plate comprising the outermost lid and electrically connected to said shield plate; wherein at least one gas flow hole is provided at said pressure plate so as to communicate an internal space of said outer container with a contacting space between said pressure plate and said shield plate, said central contacting portion includes a protrusion protruded from a central portion of said pressure plate toward said shield plate and having a first flat contacting surface and a second contacting surface provided at a central portion of said shield plate and contacting with said first flat contacting surface of said protrusion, and said pressure plate and said shield plate are isolated when an inner pressure level of said outer container exceeds a predetermined electric current isolation pressure.