An electrochemical cell has a silver vanadium oxide cathode material formed into a pellet shape which expands as the cell is discharged. A cathode current collector circumferentially surrounds the cathode pellet and is in contact with the peripheral edge of the cathode pellet to prevent peripheral cathode expansion. The peripheral cathode current collector maintains a stable cell impedance during cell discharge. The cell has a D-shaped housing in which the cathode is disposed adjacent to a first interior surface, and a lithium anode is disposed adjacent to a second interior surface.