CAP FOR ELECTROCHEMICAL CELL

A cap assembly is disclosed that creates a gas-tight seal with a cell can housing. The cap assembly has an outer surface, an inner surface and a perimeter edge. The cap assembly further includes an electrolyte injection port forming a port opening between the outer surface and the inner surface, a vent constructed to form a vent opening from the inner surface to the outer surface when a vent pressure differential is achieved between an outer surface pressure and an inner surface pressure. The vent is positioned (a) concentric to the electrolyte injection port, and (b) closer to the perimeter edge than the position of the electrolyte injection port.