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AssigneeDuracell Inc.
InventorsJeffrey Poirier, Paul Cheeseman, Michael McDermott, Jane A. Blasi, Reynald Cantave, Jeffrey Hewes, Yelena Kouznetsova, Bhupendra Patel, Alex Kaplan, Viet Vu, William T. McHugh, Lucien P. Fontaine, Robert J. Pinault
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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 thermally responsive mechanism may include a heat producing electrical resistance means, preferably a Zener diode, to enhance thermal sensitivity. 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 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 including thermally responsive means for preventing current from flowing through said electrical pathway and electrical resistance means in proximity to said thermally responsive means, said resistance means causing heating as current passes therethrough, said resistance means exhibiting decreasing resistance as voltage applied thereto increases, wherein said thermally responsive means activates when the temperature within said end cap assembly rises causing a break in said electrical pathway.
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 and a.1) electrical resistance means electrically connected to said cell terminals for causing heating as current passes therethrough, said resistance means exhibiting decreasing resistance as voltage applied thereto increases, wherein said thermally responsive means comprises a shape memory alloy member which activates when the temperature within said end cap assembly rises causing a break in said electrical pathway, and said end cap assembly further comprises b) a pressure responsive means comprising a member capable of rupture located at the end of said end cap assembly opposite said end cap plate, said member rupturing when gas pressure on the side thereof farthest from said end cap plate rises 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 and a.1) electrical resistance means in proximity to said thermally responsive means, said resistance means causing heating as current passes therethrough, said resistance means exhibiting decreasing resistance as voltage applied thereto increases, 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 rises, 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.
Dependencies are inferred from the claim text.