Molten Zinc Alloys for Lower Temperature, Lower Cost Liquid Metal Batteries

Abstract

A nontraditional liquid metal battery (LMB) is devised to address the drawbacks of molten salt‐based batteries with a simple design that does not require fragile membranes and is not limited to materials of specific densities. This battery contains coaxial, coplanar liquid Sn and Bi electrodes and a ZnCl2:KCl eutectic electrolyte. Molten Sn serves as a high‐capacity host material for depositing and stripping active Zn. In cells operating at 320 °C, the molten salt blankets the molten electrodes, isolating the half reactions while balancing charge with mobile Cl– ions. Even under exposure to ambient air and moisture, minimal capacity fade occurs during 30 days of cycling. The results indicate ZnCl2:KCl to be an excellent LMB electrolyte that functions without hermetic sealing when used at elevated temperatures. The findings contribute to the increasing interest in Zn‐based electrical energy storage with a design concept that opens the door to many unexplored materials for use in lower temperature liquid metal batteries.