Trace electrolyte additives dynamically regulating the zinc anode interface towards stable zinc-based energy storage

Abstract

Aqueous zinc-ion batteries are competitive candidates for next-generation energy storage systems; however, their practical applications are plagued by zinc dendrite and parasitic reaction issues that cause inferior stability of zinc anodes. Herein, we report glycolide (GB) as a trace additive of the ZnSO₄ electrolyte to dynamically regulate the zinc deposition interface, realizing long-term stable zinc anodes. The spontaneous reversible hydrolysis of the GB stabilizes the electrolyte pH and generates hydroxyacetic acid to modulate the electrolyte solvation structure by disrupting the H-bond network in the electrolyte and preventing SO₄²⁻ anions and water molecules from coordinating with Zn²⁺, thereby inhibiting water molecules, anions and pH variation-induced parasitic reactions at the zinc anode interface. Meanwhile, the hydrolyzed GB molecules preferentially adsorb on the zinc anode, increasing the Zn²⁺ transference number, inducing low-barrier zinc nucleation and accelerating Zn²⁺ desolvation to realize dendrite-free and fast-kinetics zinc deposition. As a result, the ZnSO₄/GB hybrid electrolyte with an optimal GB concentration of 10 mM enables the zinc anode to achieve notably improved electrochemical stability and reversibility, such as the operation lifetimes of 2100 and 720 h at 1 and 10 mA cm⁻², respectively, ∼30 times longer than that of the zinc anode in the ZnSO₄ electrolyte. Furthermore, the utilization of the ZSO/GB-10 electrolyte enables the zinc-based electrochemical energy storage systems to present good rate performance and exceptional cycling stability (e.g., over 8000-cycle lifespan). This work provides novel insights into exploring advanced electrolytes toward stable zinc anodes.