Double‐Layer Ordered Conducting Polymers Toward High Stable Iron Anode

Abstract Aqueous iron (Fe) metal ion batteries have great application possibilities and prospects due to their remarkably low cost and high safety. However, the cycle life of the Fe metal anode is limited by severe corrosion and dendrite growth, which hinders their practical application. This study employs a double‐layered, two‐dimensional (2D) ordered polyaniline film as a protective layer for Fe metal anodes. On one hand, it forms a uniform double‐layer electrostatic field on the surface of the Fe anode, which is beneficial for the migration, desolvation, and even deposition of Fe²⁺ and suppresses uneven pitting corrosion on the surface of the Fe metal. On the other hand, it serves as a physical barrier to prevent corrosive ions and water from coming into contact with the surface of the Fe anode. The protective layer enhances the cycle life of the Fe metal anode, with symmetric cells cycling for over 1600 h at 0.125 mA cm⁻² and 0.125 mAh cm⁻². The strategy of introducing ordered conductive polymers into the protection of the anode in aqueous metal‐ion batteries will further promote the development of high‐performance aqueous batteries.