High-Capacity Iron-Based Anodes for Aqueous Secondary Nickel−Iron Batteries: Recent Progress and Prospects

Aqueous rechargeable nickel-iron (Ni−Fe) batteries characterized by their ultra-flat discharge plateau, low cost, and remarkable safety show attractive prospects for applications in wearable and large-scale energy storage. Electrode materials, as the key part of Ni−Fe batteries, determine their performance. Comparatively, Fe-based anode materials possess much lower capacity and energy density than available Ni-based cathode materials; thus, the overall electrochemical performance of Ni−Fe batteries is dominated by Fe-based anode materials. The key challenge of Fe-based anodes for Ni−Fe batteries is their inferior electrochemical performance originating from their poor electrical conductivity. Recently, significant progress has been achieved in the development of Fe-based anodes for Ni−Fe batteries through nanostructural design, componential regulation, interface engineering and elemental doping, whereby both intrinsic capacity and energy density have been enhanced. This Review presents an overview of the recent progress in Fe-based anode materials by categories of metal, oxide, sulfide, hydroxide, phosphide and selenide based on chemical composition. Finally, the challenges and possible solutions are briefly presented with some perspectives toward the future development of Fe-based anode materials for next-generation aqueous secondary Ni−Fe batteries.