Iron metal anode for aqueous rechargeable batteries

Iron metal anode satisfies the safety, low-cost, non-toxicity, and energy-dense pursuits chasing by the battery community, but passivation, parasitic hydrogen evolution reaction, and low plating efficiency challenging its electrochemical performance limit its continuous practical applications. Here, the redox behaviors of the iron metal anode in both alkaline and acidic electrolytes have been summarized first to shape the fundamental mechanisms. Recent progress in developing high-performance iron metal anodes has been introduced with the highlights on representative strategies, including electrode additives, electrolyte modification, and nanoarchitecture. Especially, the history of aqueous battery systems with iron metal anode is overviewed from its earliest beginning to the new era, following by the discussion regarding the specialization of each system. We believe this review could bring the fundament of redox behavior for optimizing the iron metal anode and pave a way toward a reliable iron-based aqueous battery.