Abstract: An aluminum battery comprises an aqueous alkaline electrolyte and an anode which is an alloy of aluminum containing magnesium and/or calcium. Tin is present in the electrolyte (as stannate at a concentration of 0.001 to 0.01 M) and/or in the anode (at a concentration of at least 0.005%). The batteries operate at high coulombic efficiency at both high and low current densities. Preferred conditions of operation comprise drawing current at an average current density of 5 to 400 mA/cm.sup.2 of anode surface for at least one hour, and introducing seed crystals into the electrolyte to aid precipitation of aluminum values from the electrolyte.

Abstract: A high amp-hour aluminium battery comprises a cathode, an alkaline electrolyte and at least one massive aluminium anode plate. The electrolyte contains dissolved indium. The anode is an alloy of aluminium with manganese and with one or both of magnesium and calcium and optionally gallium. When operated at a current density below 400 mA/cm.sup.2 particularly in the presence of seed crystals, the battery remains viable during and after aluminium hydroxide precipitation in the electrolyte.