Postpone Interfacial Impoverishment of Zn‐Ions via Neodymium‐Based Conversion Films for Stable Zn Metal Anodes

Abstract The widespread adoption of aqueous zinc‐ion batteries (AZIBs) is significantly limited by the diminished cycling stability and reduced lifetime caused by the formation of rampant dendrites and detrimental side reactions, resulting from over‐fast depletion of Zn 2+ at the interface. In this contribution, a negatively charged neodymium‐based film via in situ conversion (NCF‐Zn) is presented that attracts Zn 2+ ions and repels OH − and SO 4 2− anions. Thereby, a higher Zn 2+ concentration is mentioned to postpone the impoverishment of Zn 2+ due to the over‐fast kinetics, lower the nucleation barrier, and thus uniform the electrodeposition. Meanwhile, the side reactions on the Zn anode can be suppressed due to the repelling of OH − and SO 4 2− anions. Taking these synergetic advantages, the NCF‐Zn anode enables ultra‐stable cycles for more than 2500 h in Zn|Zn symmetric cells at a current density of 10 mA cm −2 and impressive reversibility of 99.93% Coulombic efficiency in Zn|Cu asymmetric cells at a current density of 5 mA cm −2 . Notably, the assembled MnO 2 |NCF‐Zn full cell demonstrates remarkable long‐term cycling stability, retaining 97.2% of its capacity at 1 A g −1 after 1000 cycles. This work offers a straightforward yet effective strategy for constructing a stable protective layer, advancing the development of highly reversible AZIBs.