Stimulating the Potential of Zn Anodes to Operate in Low pH and Harsh Environments forHighly Sustainable Zn Batteries

Compared to near-neutral electrolytes (pH=3-6), Zn||Mn batteries in acidic environments can achieve voltages up to ~2 V. However, high proton concentrations raise concerns about Zn anode stability. Current strategies for inhibiting hydrogen evolution corrosion (HEC) on the anode in Zn-based batteries mainly focus on the near-neutral electrolytes. To supplement this gap, we developed a conversion-type interphase strategy using phosphate, sulfate precipitation, and phytic acid modification layers for Zn anodes to demonstrate the potential of Zn anode to operate in acidic electrolytes. This approach enables stable Zn stripping/plating at pH=2.2 for over 3,600 h and 400 h at 1 mA cm^-2/0.5 mAh cm^-2 and 20 mA cm^-2/10 mAh cm^-2. Benefiting from stable Zn electrodes, the electrolytic Zn||Mn batteries can operate at 1.90 V. To show more harsh scenarios, the seawater-based 0.25 Ah-scale Zn||Mn pouch cells can be assembled with a practical energy density of 57.4 Wh kg-1 cell. Significantly, we analyze and emphasize that seawater holds promise as an alternative to deionized water for electrolyte solvents due to its energy and economic effectiveness. This strategy has motivated to expand the working pH range of metal anodes and provides the rational design for grid-scale energy storage technologies.