A review on air cathodes for zinc–air fuel cells

This paper reviews the compositions, design and methods of fabrication of air cathodes for alkali zinc–air fuel cells (ZAFCs), one of the few successfully commercialized fuel cells. The more promising compositions for air cathodes are based on individual oxides, or mixtures of such, with a spinel, perovskite, or pyrochlore structure: MnO2, Ag, Co3O4, La2O3, LaNiO3, NiCo2O4, LaMnO3, LaNiO3, etc. These compositions provide the optimal balance of ORR activity and chemical stability in an alkali electrolyte. The sol–gel and reverse micelle methods supply the most uniform distribution of the catalyst on carbon and the highest catalyst BET surface area. It is shown that the design of the air cathode, including types of carbon black, binding agents, current collectors, Teflon membranes, thermal treatment of the GDL, and catalyst layers, has a strong effect on performance.