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

TL;DR

This paper investigates how electromagnetic forces can induce fluid flow in liquid metal batteries to improve mass transfer, reduce intermetallic formation, and enhance efficiency, considering thermal and geomagnetic effects.

Contribution

It introduces a numerical study of electro-vortex flow in LMBs, optimizing feeding lines and analyzing thermal and magnetic influences on flow dynamics.

Findings

Electro-vortex flow can be enhanced by optimizing feeding line configurations.

Thermal stratification significantly reduces flow velocities.

Earth magnetic field influences flow patterns in the battery.

Abstract

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. In this context we study electro-vortex flow numerically. We simulate a recent LMB related experiment and discuss 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; we show that thermal effects may reduce electro-vortex flow velocities considerable. Finally, we study the influence of the Earth magnetic field on the flow.