Patent ID: 7491464
Filing Date: 2009-02-17
Classification: H01M,Y02E,Y02P

Abstract:
1. A primary alkaline cell comprising a negative and a positive terminal, and an outer housing having a pair of opposing flat sides running along the length of said housing, said housing having a closed end and opposing open end, said cell further comprising an anode and a cathode within said housing, a separator between said anode and cathode, and an end cap assembly sealing the open end of said housing thereby forming a boundary surface around the cell interior; wherein said end cap assembly comprises a metal cover at the open end of said housing and a weld formed between said housing and said metal cover to close said open end; wherein said end cap assembly further comprises an insulating seal member having an aperture therein and an elongated electrically conductive member passing through both said metal cover and said aperture in said insulating seal member; wherein said insulating seal member comprises an integrally formed central boss having a side wall defining a central cavity within said boss, wherein a portion of said elongated conductive member is held within said boss central cavity; wherein said metal cover comprises a plate having an integrally formed sleeve extending downward therefrom when the cell is viewed with said end cap assembly on top, wherein said sleeve surrounds said central boss side wall thereby forming an interface between said sleeve and said insulating boss side wall; wherein said central boss side wall thickness is held compressed between said metal cover sleeve and said elongated conductive member, said compression of said central boss side wall thickness being in the direction perpendicular to the cell's central longitudinal axis; wherein with the percentage compression of the insulating seal boss side wall thickness defined as ΔR % and the length of the interface between said metal cover sleeve and said insulating boss side wall as L (mm), then the product of ΔR % multiplied by L is between about 16.2 and 93.1; wherein said cell further comprises a vent mechanism located on said boundary surface, wherein said vent mechanism activates to release gas pressure from within the cell as said gas pressure rises, said vent mechanism comprising a first rupture zone comprising a groove on said boundary surface, said groove defining an underlying material region thinner than the average thickness of said boundary; and a second rupture zone forms a weld on said boundary surface, wherein the first zone ruptures when gas pressure within the cell rises to a first pressure level and said second zone ruptures when gas pressure within the cell rises to a second pressure level being higher than said first pressure level allowing gas from within the cell to escape from the cell interior through said ruptures.