Concurrent Regulation of Surface Topography and Interfacial Physicochemistry via Trace Chelation Acid Additives toward Durable Zn Anodes

Abstract

Electrolyte additive engineering is a feasible protocol in improving Zn anode stability. Typical additive designs center on the regulation of Zn deposition; nevertheless, versatile additives are urgently requested to comprehensively manage the surface landscape, interface physicochemistry, and by-product elimination. Here, a straightforward strategy is presented to meet such needs employing an environmentally-friendly chelator, hydroxyethyl-ethylenediaminetriacetate acid (HEDTA), as an additive for ZnSO₄ electrolyte. Throughout theoretical computations and experimental investigations, it is demonstrated that protons released from the gradual ionization of HEDTA during rest periods aid in the mild engraving of the Zn surface. Both the amino and carboxyl groups of HEDTA⁻ can be protonated, which effectively buffers the interfacial pH value in the entire battery lifespan and eliminates the formation of by-products. The HEDTA⁻ anions can also adsorb onto the Zn surface, helping facilitate Zn²⁺ mass transfer and accelerate the desolvation process. Benefiting from the synchronous modulation of surface topography and interfacial physicochemistry, the assembled half cells affording HEDTA additive maintain a durable operation of up to 8821 cycles at 5.0 mA cm⁻²/1.0 mAh cm⁻². Additionally, symmetric cells manifest stable cycling for over 4600 h at 0.5 mA cm⁻²/0.25 mAh cm⁻².