A review on system and materials for aqueous flexible metal–air batteries

Abstract The exploration of aqueous flexible metal–air batteries with high energy density and durability has attracted many research efforts with the demand for portable and wearable electronic devices. Aqueous flexible metal–air batteries feature Earth‐abundant materials, environmental friendliness, and operational safety. Each part of one metal–air battery can significantly affect the overall performance. This review starts with the fundamental working principles and the basic battery configurations and then highlights on the common issues and the recent advances in designing high‐performance metal electrodes, solid‐state electrolytes, and air electrodes. Bifunctional oxygen electrocatalysts with high activity and long‐term stability for constructing efficient air electrodes in flexible metal–air batteries are summarized including metal‐free carbon‐based materials and nonprecious Co/Fe‐based materials (alloys, metal oxides, metal sulfites, metal phosphates, metal nitrates, single‐site metal–nitrogen–carbon materials, and composites). Finally, a perspective is provided on the existing challenges and possible future research directions in optimizing the performance and lifetime of the flexible aqueous solid‐state metal–air batteries.