Regeneration of Zinc Particles for Zinc-Air Battery by Spouted-bed Electrochemical Reactor

Abstract

Zinc-air batteries are a promising energy storage system due to its high energy density, low toxicity, and low flammability. They are currently used commercially in low-current devices. Batteries for high-current applications are constructed with zinc particles for increased specific surface areas. Nevertheless, the regeneration of zinc particles from dissolved zincate ions in spent electrolytes has been relatively neglected. We fabricate and study a spouted-bed electrochemical reactor for the regeneration of zinc particles from spent electrolytes. The reactor measures 220 mm high and 130 mm wide with copper as a cathode and stainless steel as an anode. The reactor is separated into two compartments with a cation-exchange membrane. The model spent electrolytes are made by saturating 6 M KOH solutions with ZnO. Stainless steel particles are spouted into the reactor along with the electrolyte as seed particles. Zinc is deposited on stainless steel particles in the cathode compartment electrochemically by imposing potential differences between the anode and the cathode. Effects of zinc particle morphology, current efficiency, and energy consumption are studied. The regenerated zinc deposits are used as an anode in the zinc-air battery to test the performance of the battery.