Stability characterization of liquid metal batteries

As illustrated by the simplified scheme shown on the right, the battery is a cell filled with a light metal A (for example, Li or Mg) at the top, heavy metalloid B (Bi, Sb, or Pb-Sb alloy) at the bottom, and electrolyte dissolving ions of A and B in the middle. The battery is discharged when A and B form a compound and charged when they are electrochemically reduced from this compound. During the charging and discharging, the strong electric current flowing through the battery induces magnetic field in and around the cell, and generates strong Joule heating in the electrolyte.

In our project, we consider the matter of hydrodynamic instabilities, which are expected to appear in batteries of large size. Little is known about the instabilities at the moment, although it is clear that their mechanisms are complex and diverse. Our work is currently focused on the two mechanisms found to lead to practically unavoidable instabilities:

1. Thermal convection in layers E and A caused by the Joule heating that occurs than electric current passes the poorly conducting electrolyte

2. The so called metal pad instability, in which slight deformations of the A-E and B-E interfaces are enhanced, with potentially catastrophic consequences, by electromagnetic forces.

An account of the results of the project can be found in our publications, such as:

1. Shen, Yu., Zikanov, O., “Thermal convection in a liquid metal battery,” Theor. Comp. Fluid Dyn. 30 (4) pp. 275-294, 2016.

2. Zikanov, O., “Metal pad instabilities in liquid metal batteries,” Phys. Rev. E 92, 063021, 2015.

3. Zikanov, O., Shen, Y. “Mechanisms of instability in liquid metal batteries,” Fundamental and Applied MHD, Proc. of 10^th PAMIR conf., 2016.