Synergistic Regulation of Hierarchical Anode Interphase and Cathode Electronic Structure by a Fe( <scp>III</scp> ) Complex for High‐Performance Aqueous Zinc‐Manganese Battery

Aqueous zinc‐ion batteries (AZIBs), particularly zinc‐manganese (Zn‐Mn) systems, hold great promise for large‐scale energy storage but face challenges from parasitic reactions of the anode and poor conductivity of the cathode. Herein, a multifunctional additive naphthol green B (NGB), which contains a planar organic group and a transition metal ion, is applied to concurrently address anode and cathode issues during battery cycling. Specifically, the adsorption and partial decomposition of the planar organic group construct a hierarchical interfacial layer on the anode surface, comprising an organic outer phase and an inorganic inner phase, assists to alleviate side reactions and modulate zinc deposition. Meanwhile, Fe 3+ ions released from NGB incorporate into the α‐MnO 2 cathode during discharge, increasing oxygen defects and lowering the Mn average oxidation state, which improves the structural stability and electrical conductivity of the Mn‐based cathode, further boosting capacity and cycling performance. Consequently, the Zn‖Zn cell demonstrates stable operation for 3500 h at 1 mA cm −2 , and the Zn‖Cu cell achieves an average Coulombic efficiency of 99.87% over 2500 cycles at 5 mA cm −2 . Notably, the Zn‖MnO 2 cell employing modified electrolyte exhibits no capacity decay after cycling 250 and 1000 times at 0.2 and 1 A g −1 , respectively. This work presents new perspectives on simultaneously addressing anode and cathode issues in AZIBs based on electrolyte engineering, highlighting the function of the additive structure and composition.