Iron anode‐based aqueous electrochemical energy storage devices: Recent advances and future perspectives

Abstract The ever‐growing demands for green and sustainable power sources for applications in grid‐scale energy storage and portable/wearable devices have enabled the continual development of advanced aqueous electrochemical energy storage (EES) systems. Aqueous batteries and supercapacitors made of iron‐based anodes are one of the most promising options due to the remarkable electrochemical features and natural abundance, pretty low cost and good environmental friendliness of ferruginous species. Though impressive advances in developing the state‐of‐the‐art ferruginous anodes and designing various full‐cell aqueous devices have been made, there still remain key issues and challenges on the way to practical applications, which urgently need discussing to put forwards possible solutions. In this review, rather than focusing on the detailed methods to optimize the iron anode, electrolyte, and device performance, we first give a comprehensive review on the charge storage mechanisms for ferruginous anodes in different electrolyte systems, as well as the newly developed iron‐based aqueous EES devices. The deep insights, involving the inherent failure mechanisms and corresponding modification/optimization strategies toward iron anodes for the development of high‐performance aqueous EES devices, will then be discussed. The advances in applying iron‐based aqueous EES devices for emerging fields such as flexible/wearable electronics and functionalized building materials will be further outlined. Last, future research trends and perspectives for maximizing the potential of current iron anodes and devices as well as exploiting brand‐new iron‐based aqueous EES systems are put forward.