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

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.