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Dr. Tom Weier

Head Liquid metal battery
t.weierAthzdr.de
Phone: +49 351 260 2226

Local, small scale short-circuits in liquid metal batteries

When cycling liquid metal batteries, local short circuits have been observed several times. They manifest e.g. in the cell voltage. Fig. 1. shows one example: the sudden drop of the terminal voltage is a clear evidence of a short circuit of the battery. At the same time, a certain increase in cell temperature might be observed.

Lade-Entladekurve einer Li-Bi Flüssigmetallbatterie ©Copyright: Dr. Weber, Norbert

Fig. 1: Charge-discharge curve of a Li-Bi liquid metal battery with short-circuits during operation.

Picture: Norbert Weber

After dismantling used cells, the cathode metal can sometimes be found attached to the anode current collector. Fig. 2 shows one example: the small metallic deposits are in fact a mixture of Li and Bi. During normal operation, such effects should not occur. They can only be explained by small, localised short-circuits.

Anode einer Li-Bi Flüssigmetallbatterie nach lokalem Kurzschluss ©Copyright: Landgraf, Steffen

Fig. 2: Anode of a Li-Bi liquid metal battery after localised short circuits.

Picture: Steffen Landgraf

Such small-scale short-circuits can, amongst others, be explained by insufficient wetting of the current collector by the molten metal. Fig. 3 shows one example: as the molten Li does not wet the wire, large Li-droplets form. If these droplets grow too much, they might induce local short-circuits.

Anode einer Flüssigmetallbatterie mit schlechter Benetzung ©Copyright: Landgraf, Steffen

Fig. 3: Anode of a liquid metal battery with insufficient wetting of the current collector.

Picture: Steffen Landgraf

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