Engineering design of liquid metal batteries

Abstract

Liquid Metal Batteries can operate using both electrodes as well as the molten salt electrolyte are in liquid state at a temperature between 400ºC and 600ºC. The engineering design of the single cells to make up a battery will depend on the materials selected for the electrode and on the electrolytes. Presently, the liquid metal batteries are in constant research and development, following the work in the 1960s carried out at Argonne National Laboratory, since 2006 the work was reinitiated by the authors at the Massachusetts Institute of Technology (MIT). Besides, Prof. Donald Sadoway is teaching and researching at the MIT, and a student of him was the founder of the Ambri’s technology (Liquid Metal Battery Corporation) which is developing an electricity storage solution that will change the way electric grids are operated in all the world. In this work, the design and evaluation of the singles cells and battery systems will be crucial to construct the battery model, including the current collector, the current bus bars, the heating system and the insulation layers, in terms of manufacturing requirements and assembly effort. Furthermore, the geometrical and mechanical requirements, due to the hot liquid metals and high currents in the collector and conductor material. The model designed for the battery, contain 1944 cells operating in a current voltage of 1458 V, operates at a capacity of 2.5 MWh, and has a power of 0.126 MW. This battery will be connected in parallel with two identical batteries, to can achieve more capacity and power. Then the ratio between the capacity and power will be around 1:6. The single cell will be rectangular according to 2:1 ratio and shallow. The self-heating of the battery will take 14.37h to achieve the temperature of 450º for the materials in a liquid phase. For this heat flow passing through the wall, the length of the insulation layer needed for the two longer walls will be 0.552 m, for the width walls surface 0.368 m, and for the top horizontal surface 0.527 m. There are other 6 more battery model designed for three different capacities (0.1; 1; 10 MWh) and for three different powers (0.1; 1; 10 MW).