Electromagnetically driven convection suitable for mass transfer enhancement in liquid metal batteries

Liquid metal batteries (LMBs) were recently proposed as cheap large scale energy storage. Such devices are urgently required for balancing highly fluctuating renewable energy sources. During discharge, intermetallic phases tend to form in the cathode of LMBs. These do not only limit the up-scalability, but also the efficiency of the cells. Generating a mild fluid flow in the fully liquid cell will smoothen concentration gradients and minimise the formation of intermetallics. With this application in mind, electro-vortex flow is studied numerically. A recent LMB related experiment is simulated, and it is further discussed how the feeding lines to the cell can be optimised to enhance mass transfer. The Lorentz forces have to overcome the stable thermal stratification in the cathode of the cell; it is shown that thermal effects may reduce electro-vortex flow velocities considerably. Finally, the influence of the Earth magnetic field on the flow is studied.