ELECTROCHEMICAL CELL WITH FLAT CASING AND VENT

An electrochemical cell generating hydrogen gas upon discharge, wherein the cell has an outer casing, a vent aperture passing through a wall of the casing, and a rupturable membrane covering the vent aperture. The outer casing preferably has a flat wall running along the cell's length and a vent aperture passing through the flat wall. The cell may typically be an alkaline cell in the shape of a cuboid. The rupturable membrane may be secured by a ring facing the inside surface of the flat wall of the casing in a position adjacent the vent aperture. The rupturable membrane is preferably of polysulfone. The membrane allows hydrogen gas to permeate therethrough to the environment and is rupturable if hydrogen gas within the cell interior builds up rapidly to a threshold pressure level. Optionally, a pointed puncture member extends into the vent aperture to assist membrane rupture.