Advanced Architectures of Air Electrodes in Zinc–Air Batteries and Hydrogen Fuel Cells

Air electrode is an essential component of air-demanding energy storage/conversion devices, such as zinc-air batteries (ZABs) and hydrogen fuel cells (HFCs), which determines the output power and stability of the devices. Despite atom-level modulation in catalyst design being recently achieved, the following air electrodes have received much less attention, causing a stagnation in the development of air-demanding equipment. This Progress Report begins with the evolution of air electrodes for ZABs and HFCs from the early stages to current requirements. Then, the operation mechanism and the corresponding electrocatalytic mechanisms of ZABs are summarized. In particular, by clarifying the air electrode interfaces of ZABs at different scales, several approaches to improve the air electrode in rechargeable ZABs are reviewed, including the innovative electrode structures and bifunctional oxygen catalysts. Afterwards, we explain the operating mechanisms of proton exchange membrane fuel cells (PEMFCs) and anion-exchange membrane fuel cells (AEMFCs). Subsequently, the strategies employed to enhance the efficiency of the membrane electrode assembly (MEA) in PEMFCs and AEMFCs, respectively, are highlighted and discussed in detail. Last, the prospects for air electrodes in ZABs and HFCs are considered by discussing the main challenges. This Progress Report aims to facilitate the industrialization of ZABs and HFCs. This article is protected by copyright. All rights reserved.