Patent ID: 7704632

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 peripheral edge; 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 edge, a terminal cover reception channel located adjacent the upstanding perimeter wall, said edge of the cover 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 flap 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 a bottom surface of the thin diaphragm region at the vent flap than to an elevation of an inner surface of the cover's central region to prevent the vent flap from contacting the cover when pressurized gas in the cell escapes through the vent assembly; 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 an orifice through which pressurized gas in the cell can escape; and iv) an electrically conductive current collector that contacts said hub, extends through the opening in said seal member and contacts said second electrode.