Patent ID: 6991872

Claim:
In an AA size alkaline cell having an open ended cylindrical housing and an end cap assembly inserted therein closing said housing, said cell having a positive and a negative terminal, said end cap assembly comprising an end cap functioning as a cell terminal and an insulating sealing member insulating the end cap from the cell housing, said insulating sealing member having an elongated electrically conductive current collector passing therethrough, the current collector being in electrical contact with the end cap, and the edge of said housing being crimped over the peripheral edge of said end cap to form a cell shoulder along the line of crimp, the improvement comprising: the end cap assembly in said AA size cell comprising an end cap, and an insulating sealing member underlying said end cap when the cell is viewed in vertical position with the end cap assembly on top; said end cap being formed of a disk of single piece metallic construction having a convoluted surface and at least one vent aperture through its surface; wherein said end cap assembly does not include a metal disk other than said end cap within any portion of said cell housing at the open end thereof; said insulating member comprising an insulating sealing disk having a peripheral edge abutting the cell housing and electrically insulating said end cap from the cell housing; said insulating sealing disk comprising a central boss and an integrally formed radially extending arm extending from said boss; wherein said radially extending arm forms a continuous surface around said boss; said radially extending arm having a thinned portion therein forming a rupturable membrane which underlies said end cap when the cell is viewed in vertical position with the end cap assembly on top; wherein said rupturable membrane circumvents said boss circumference; wherein at least one of the top and bottom surfaces of said radially extending arm, when viewed with the cell in vertical position with the end cap assembly on top, has an annular groove therein, wherein said annular groove circumvents said boss and forms said rupturable membrane portion at the base of said groove, said rupturable membrane circumventing said boss; wherein when gas pressure within the cell reaches a pressure in a range between about 400 and 800 psig (2758×10 3 and 5516×10 3 pascal gage), said membrane ruptures thereby releasing gas directly into the surrounding environment through said vent aperture in the end cap.