Liquid Metal Batteries as a Power Buffer in Aluminium Production Plants

A new type of liquid metal battery based on sodium and zinc is described. One possible use of such a battery is as a power buffer in an aluminium plant, thus enabling extreme power cycling. By locating the battery in an idled potline, existing infrastructure such as buildings, rectifiers, potshells, and busbars can be utilised. The reversible voltage of the battery is about 1.9 V, and it is suggested to place three battery stacks connected in series to 5.7 V in each potshell of the idle line. By limiting the voltage loss in the electrolyte to 0.15 V per stack at 250 kA, it was estimated that the battery capacity could be about 2.40 MAh, corresponding to 250 kA for 9.6 hours. Provided that the electrolyte height constitutes 50 percent of the total, the stack height will be less than 1.4 m, which can easily be accommodated inside a potshell.