Effects of Porous Structure on Oxygen Mass Transfer in Air Cathodes of Nonaqueous Metal–Air Batteries: A Mini-review

Among various energy-storage technologies, metal–air batteries are gaining more and more attention since they have super-high-energy density. However, the low rate capacity, poor circularity, and instability of metal–air batteries need to be addressed before they can be implemented in practice. The mass transfer in air cathodes is worth investigating to enhance the development of metal–air batteries. In this Review, we survey the effects of surface area, pore volume, and pore size on the mass transfer in air cathodes. The latest studies of electrode materials and porous structure are reviewed and discussed. Besides, the relationship between electrocatalysts and porous structure are also mentioned. Fundamental advances in developing materials and rational design of porous structures with electrocatalysts are important to enhance mass transfer and further promote metal–air batteries. Based on the discussion of effects of porous structures in air cathodes, some personal views on the advanced design of cathodes are proposed to facilitate the development of metal–air batteries.