Seal for an electrochemical cell

Abstract

An electrochemical cell with a vent assembly that reliably prevents resealing of a vented seal member is provided. The vent assembly seals the end of a container that includes a first electrode, a second electrode, a separator located between the first and second electrodes and an electrolyte in contact with the electrodes and separator. The seal member includes a diaphragm with a hinge along one edge and a vent along another edge. The hinge and vent are located so that, relative to the longitudinal axis of the vent assembly, the hinge is closer to the vent than to the cell's terminal cover.

What is claimed is:  
     
         1 . An electrochemical cell, comprising: 
 (a) an open ended container, said container comprises a first electrode in contact with said container, a separator in contact with said first electrode, a second electrode in contact with said separator and electrolyte in contact with said electrodes and said separator; and    (b) a vent assembly, having a longitudinal axis, is concentrically aligned with and secured to the open end of said container, said vent assembly comprises: 
 i) an electrically conductive cup shaped cover having a recessed central region;  
 ii) a disc shaped rupturable seal member made of a polymeric material and contacting said cover, said seal member comprises an upstanding wall defining the perimeter of the seal member, and a thin rupturable diaphragm region having a first edge, a second edge and located between the seal member's upstanding perimeter wall and a centrally located hub which defines an opening through said seal member, said seal member comprises a hinge located adjacent a first edge of the thin diaphragm region and a vent located adjacent a second edge of the thin diaphragm region, said hinge's elevation, relative to the longitudinal axis of the vent assembly, is closer to the elevation of the vent than to the elevation of the cover's central region;  
 iii) an electrically conductive current collector extends through the opening in said seal member and contacts said second electrode.  
   
     
     
         2 . The electrochemical cell of  claim 1  wherein said second edge of said thin diaphragm region comprises a grooved section and a nongrooved section, said grooved section defining the location of said vent and said nongrooved section defining an anchor which secures said diaphragm region to said hub.  
     
     
         3 . The electrochemical cell of  claim 2 , wherein said groove is arc shaped and concentrically aligned with the central opening in said seal member.  
     
     
         4 . The electrochemical cell of  claim 2 , wherein said nongrooved section forms at least a 30° arc.  
     
     
         5 . The electrochemical cell of  claim 2 , wherein said nongrooved section forms approximately a 100° arc.  
     
     
         6 . The electrochemical cell of  claim 2 , wherein said nongrooved section forms less than a 180° arc.  
     
     
         7 . The electrochemical cell of  claim 2  wherein said grooved section forms an arc greater than 180°.  
     
     
         8 . The electrochemical cell of  claim 2  wherein said grooved section forms an arc greater than 220°.  
     
     
         9 . The electrochemical cell of  claim 2  wherein said grooved section forms an arc greater than 250°.  
     
     
         10 . The electrochemical cell of  claim 1  wherein said hinge's elevation is between the elevation of the vent and the elevation of the cover's central region.  
     
     
         11 . The electrochemical cell of  claim 1  wherein said hinge is arc shaped and concentrically aligned with the central opening in said seal member.  
     
     
         12 . The electrochemical cell of  claim 1  wherein said seal member comprises a buttress wall abutting said diaphragm region and said cover when said cell is pressurized, said buttress wall positioned to resist the compressive force exerted on said diaphragm by an increase in the cell's internal pressure.  
     
     
         13 . The electrochemical cell of  claim 1  wherein said polymeric material is selected from the group consisting of nylon, polypropylene and impact modified polystyrenes.