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AssigneeDuracell Inc.
InventorsViet H. Vu, William T. McHugh, Jane A. Blasi, Lucien P. Fontaine, Robert J. Pinault
Estimating the term…
A current interrupt mechanism for electrochemical cells is disclosed. A thermally activated current interrupt mechanism is integrated into an end cap assembly for an electrochemical cell. The thermally responsive mechanism preferably includes a free floating bimetallic disk or shape memory alloy member which deforms when exposed to elevated temperature causing a break in an electrical pathway within the end cap assembly. This prevents current from flowing through the cell and effectively shuts down an operating cell. The end cap assembly may include a pressure responsive mechanism which ruptures when there is extreme gas pressure buildup. Gas is allowed to escape from the cell interior to the external environment through a series of vent apertures within the end cap assembly.
An end cap assembly for application to an electrochemical cell having a positive and a negative terminal and a pair of internal electrodes (anode and cathode), said end cap assembly comprising a housing, a chamber within the housing, and an exposed end cap plate, said plate functional as a cell terminal, said end cap assembly having an electrically conductive pathway therethrough permitting the end cap plate to be electrically connected to a cell electrode when said end cap assembly is applied to a cell, said end cap assembly further comprising a) thermally responsive means for preventing current from flowing through said electrical pathway, wherein said thermally responsive means comprises a shape memory alloy member activatable when the temperature within said end cap assembly reaches a predetermined level causing a break in said electrical pathway, and b) a pressure responsive means comprising a rupturable member located at the end of said end cap assembly opposite said end cap plate, said rupturable member rupturing when gas pressure on the side thereof furthest from said end cap plate reaches a predetermined level producing a rupture in said member allowing gas to pass therethrough.
In an electrochemical cell of the type formed by an end cap assembly inserted into an open ended cylindrical case for the cell, said cell further having a positive and a negative terminal and a pair of internal electrodes (anode and cathode), wherein said end cap assembly has a housing and an exposed end cap plate, said end cap plate functional as a cell terminal, the improvement comprising said end cap plate being electrically connected to one of said electrodes through an electrically conductive pathway within said end cap assembly, wherein said end cap assembly comprises a) thermally responsive means comprising an electrically conductive shape memory alloy member for preventing current from flowing through the cell, wherein said shape memory member comprises a flexible member having a bent surface and a thickness smaller than its length, said flexible member oriented within said end cap assembly so that current passes substantially in a direction through the thickness of said flexible member, wherein when the cell temperature reaches a predetermined temperature said shape memory member deflects along said bent surface causing a break in said electrical pathway between said end cap plate and said electrode thereby preventing current from flowing through the cell.
An end cap assembly for application to an electrochemical cell having a positive and a negative terminal and a pair of internal electrodes (anode and cathode), said end cap assembly comprising a housing and an exposed end cap plate, said plate functional as a cell terminal, said end cap assembly having an electrically conductive pathway therethrough permitting the end cap plate to be electrically connected to a cell electrode when said end cap assembly is applied to a cell, said end cap assembly further comprising a) thermally responsive means for preventing current from flowing through said electrical pathway, wherein said thermally responsive means is activatable when the temperature within said end cap assembly reaches a predetermined level causing a break in said electrical pathway, wherein said thermally responsive means comprises a chamber within said end cap assembly and further comprises a shape memory alloy member, the shape memory alloy member forming a portion of said electrical pathway, wherein a portion of said shape memory alloy member comprises a disk having an aperture through the thickness thereof, said disk having an outer edge with a flexible portion protruding inwardly into said aperture from a portion of said outer edge, wherein the outer edge rests on a surface of an insulating member within said end cap assembly, wherein when the cell temperature within said assembly reaches a predetermined level said flexible portion deforms causing a break in the electrical pathway.
Dependencies are inferred from the claim text.