Electrochemical cell with low volume cover assembly

An electrochemical battery cell comprising a metal container with an open end closed with a metal cover. The top portion of the container side wall has a torus above an inward necked area, and the cover has a flange shaped around the outside of the torus and extending into the necked area. The inside diameter of the cover flange is smaller than the outside diameter of the torus, so that the cover is locked onto the top of the can. The components sealing the top of the cell require a small volume so that the internal volume for active materials and electrolyte is large. The cell can be closed and sealed with little downward force on the can side wall below the neck, allowing use of a thinner can.