Unveiling Anion-Cation Interaction of Electrolyte for Long-Life Ah-Level Aqueous Zinc Metal Batteries

Aqueous zinc metal batteries (AZMBs) are attractive for stationary energy storage due to their low cost and high safety. However, parasitic side reactions and severe Zn dendrites hinder practical implementation. Here, we propose the anion/cation dehydration shielding force as an effective guideline for electrolyte engineering that prioritizes anion-cation coordination structure. The methodology identifies 2-ethoxyethanol solvent as optimal components, enhancing Zn²⁺ diffusion kinetics and suppressing water activity through anion-dominated coordination chemistry. The preferential reduction of OTF^- enables fluorine-rich solid electrolyte interphase formation with high Zn²⁺ conductivity and excellent mechanical robustness, protecting Zn anode from side reaction and dendrite growth. As a result, the designed electrolyte enables symmetric Zn||Zn pouch cells to achieve 1500 h cycling with a remarkable cumulative capacity of 30 Ah cm^-2 under demanding conditions (20 and 10 mAh cm^-2). More importantly, Ah-level pouch cells set extremely excellent durability milestones, maintaining 1400 cycles (4.2 months/3000 h operation) while outperforming most reported Zn metal counterparts in comparable capacity ranges.