UC Irvine

Metal-air batteries (MAB) is becoming a revived interest because of its high theoretical energy density, low-cost, and environmentally friendly nature. It has wide range of applications from portable transportation to stationary applications. However, commercialization of this technology is hindered by the limitations associated with the metal anode, air cathode, and electrolyte.Commercial benchmark catalysts at the cathode and anode are platinum nanoparticles over carbon-based supports and iridium oxide particles, respectively. However, carbon supports are highly susceptible to corrosion resulting in major performance losses. These metals are also expensive, limited, and difficult to obtain. Hence, corrosion-resistant support materials or an alternative metal are needed. In this study, catalytic activity of a library of transition metal oxides with various supports is explored. All the catalysts were characterized physically and electrochemically to understand their morphological and electrocatalytic properties towards oxygen reduction reaction and oxygen evolution reaction. The oxygen reduction reaction activity, investigated in aqueous 1 M KOH electrolyte, using rotating disk electrode showed worse performance than benchmark Pt/C. However, the oxygen evolution reaction activity surpassed performance of industrial catalyst IrOx. The best performing catalyst in nickel iron oxides and nickel cobalt oxides, neglecting carbon supports, are also investigated in MABs. This thesis provides an exploration of novel bifunctional catalysts tested electrochemically in aqueous 1 M KOH and aqueous 2 M NaCl. The best performing catalysts are then tested in a Zinc-Air battery in aqueous 1 M KOH.