Tuning Zn-ion de-solvation chemistry with trace amount of additive towards stable Aqueous Zn anodes

Aqueous Zn-ion batteries (AZIBs) have attracted widespread attention due to their intrinsic safety, cost-effectiveness. However, active H₂O in the solvated ions [Zn(H₂O)₆]²⁺ continuously migrate to the Zn surface to trigger hydrogen evolution reaction (HER) and accelerate Zn corrosion. Herein, Zn dendrites and the related by-products have been successfully inhibited by using trace amounts of Nitrilotriacetic acid (NTA). Theoretical research indicates that two carboxyl groups of NTA molecule strongly anchored on the Zn surface and exposed another carboxyl group outside. Due to the violent interaction of carboxyl groups of NTA with H₂O, the de-solvation energy barrier of solvated Zn²⁺ ([Zn(H₂O)₆]²⁺) on the Zn surface was obviously decreased, inhibit the active water splitting. Meanwhile, the preferential adsorption of NTA on the Zn surface increases the thickness of electric double layer EDL and provides a buffer layer to hinder the dendrite growth. Using 0.04 M NTA as additives in 2.0 M ZnSO₄ electrolyte, the cycling lifespan of both Zn||Zn symmetric and Zn||MnO₂ full cells is markedly prolonged. This study provides certain perspectives for trace amounts of electrolyte additives to satisfy the demand of long-cycle life AZIBs.