Air cathodes for metal-air batteries and fuel cells

Metal-air batteries and variant technologies have the potential to drastically increase the power density and decrease the cost of energy storage. This paper highlights some of the compositions, designs and methods of fabrication of air-cathodes for metal-air batteries. 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 activity towards the oxygen reduction reaction 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.