Dendrite‐Free Zn Anode Enabled by Dual‐Function Itaconic Acid Electrolyte Additive Via Controllable Acidic Environment and In Situ Interfacial Protective Layer for Durable Aqueous Zinc Ion Batteries

Abstract The side reactions and dendritic growth largely impede the utilization of Zn anode in aqueous zinc ion batteries (AZIBs). Herein, a novel strong acidic electrolyte additive of itaconic acid (IA) is introduced to achieve highly stable Zn anode via dual functions. First, the use of trace amounts of IA can provide a steady low pH environment for the electrolyte, which is beneficial to eliminate the alkaline by‐products by neutralizing the OH⁻ that accumulated near the Zn anode. Second, an interfacial protective layer can be in situ formed via the cross‐linking and reduction reaction between IA and Zn anode, helping to inhibit the continuous corrosion on the Zn anode and promote the formation of uniform Zn deposition. Consequently, the Zn anode achieves an ultra‐long cycle‐life (5390 h at 1 mA cm⁻², 1 mAh cm⁻²) and an enhanced coulombic efficiency (99.86% upon 2100 cycles at 5 mA cm⁻², 1 mAh cm⁻¹). Besides, the full cell assembled with sodium vanadate delivers a high reversible capacity of 179.6 mAh g⁻¹ over 2000 cycles at 2 A g⁻¹. This work offers a new solution and related insights for the design and utilization of aqueous electrolytes with strong acidic additives toward highly stable Zn anode for AZIBs.