Advances in cathode materials for Li-O2 batteries

Lithium-oxygen (Li-O2) batteries have attracted significant attention due to their ultra-high theoretical energy density. However, serious challenges, such as potential lag, low-rate capability, round-trip efficiency, and poor cycle stability, greatly limit their practical application. This review provides a comprehensive account of the development of Li-O2 batteries, elucidates the current discharge/charge mechanism, and highlights both the advantages and bottlenecks of this technology. In particular, recent research progress on various cathode materials, such as carbon-based materials, noble metals, and non-noble metals, for Li-O2 batteries is deeply reviewed, emphasizing the impact of design strategies, material structures, chemical compositions, and microphysical parameters on oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) kinetics, as well as discharge products and overall battery performance. This review will also shed light on future research directions for oxygen electrode catalysts and material construction to facilitate the development of Li-O2 batteries with maximized electrochemical performance.