Navigating the progress and challenges of solid-state metal–oxygen batteries for the sustainable energy horizon: A comprehensive review and future prospects

All-solid-state metal–oxygen batteries are considered promising for next-generation energy storage applications owing to their superior theoretical capacity, energy density, and safety. In this review, we cover the latest advances in the development of solid-state Li-O₂ and Na-O₂ batteries. First, we summarize the problems associated with liquid-based Li-O₂ and Na-O₂ batteries. We then discuss the reaction pathways in all-solid-state Li-O₂ and Na-O₂ batteries and examine their components, discharge products, and possible side reactions during charging/discharging processes. In addition, we describe the outstanding advances in solid electrolytes, electrocatalysts, and anodic/cathodic electrodes. We also review the solid-electrolyte interfaces in these batteries and developing advanced characterization methods recently applied to evaluate changes during electrochemical reactions. As part of future research, a separate section focuses on the expanded concept of next-generation all-solid-state K-O₂, Mg-O₂, Al-O₂, and Fe-O₂ batteries. Finally, we evaluate several unsolved problems associated with solid-state Li-O₂ and Na-O₂ batteries and present our perspectives and ideas for future endeavors. We propose timely and significant research directions for the rational development of new electrode materials, catalysts, and solid electrolytes with superior ionic conductivity, low-impedance interfaces, multiple three-phase boundaries, and modified charge/discharge reaction pathways with more compatible discharge products.