Patent ID: 7527891

Claim:
An electrochemical cell, comprising: (a) an open ended container, said container comprising 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 first and second electrodes and said separator; and (b) a vent assembly, having a longitudinal axis, concentrically aligned with and secured to the open end of said container, said vent assembly comprising: i) an electrically conductive cup shaped terminal cover having a recessed central region and a rolled back edge that is approximately perpendicular to the central region; ii) a disc shaped rupturable seal member made of a polymeric material, said seal member comprising an upstanding perimeter wall compressed between said container and said cover's rolled back edge, a terminal cover reception channel located adjacent the upstanding perimeter wall, said rolled back edge disposed within said cover reception channel, and a thin rupturable diaphragm region having a first edge and a second edge, said diaphragm region 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 comprising a hinge located adjacent the first edge of the thin diaphragm region and a vent located adjacent the second edge of the thin diaphragm region, said hinge having an elevation, relative to the longitudinal axis of the vent assembly, that is closer to an elevation of the vent than to an elevation of the cover's central region; iii) a vent deflection zone, said zone defined as the space below the cover, above the diaphragm region and between the diaphragm's first edge and second edge, said zone devoid of any structural element, wherein in response to an undesirable increase in the cell's internal pressure, said seal ruptures along at least a portion of said thin diaphragm region's second edge thereby creating a vent flap and an orifice through which pressurized gas in the cell can escape, said flap rotates about the hinge and through the vent deflection zone without contacting any object; and iv) an electrically conductive current collector that contacts said hub, extends through the opening in said seal member and contacts said second electrode, 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.