Surface Protection and Interface Regulation for Zn Anode via 1‐Hydroxy Ethylidene‐1,1‐Diphosphonic Acid Electrolyte Additive toward High‐Performance Aqueous Batteries

Metallic zinc is regarded as an ideal anode material for high-energy aqueous zinc ion batteries owing to its high theoretical capacity, low cost, and abundant resource. However, the undesirable dendrite formation and side reactions occurring on Zn anode during the long-term cycling process seriously restrict the electrochemical performance of the device. Herein, 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP) is used as electrolyte additive to release the chemical corrosion and hydrogen evolution occurring on Zn anode based on the absorption of HEDP on the Zn foil. Moreover, the strong coordination of HEDP with Zn2+ can balance ion flux at the electrode/electrolyte interface, thus inducing uniform Zn deposition. Thereby, Zn anode exhibits a prolonged cycle life of reversible Zn plating/stripping under different current densities (2800 h at 2 mA cm-2 , 1 mAh cm-2 , and more than 1772 h at 4 mA cm-2 , 1 mAh cm-2 ). Moreover, the cell shows a high average coulombic efficiency of ≈99.6% for ≈600 cycles at 1 mA cm-2 with a cycling capacity of 1 mAh cm-2 . This work provides a facile yet effective method for developing reversible aqueous zinc metal batteries.