A novel bifunctional zinc gluconate electrolyte for a stable Zn anode

Aqueous zinc ions batteries, being developed rapidly as a promising type of energy storage devices, are troubled by dendrite growth on Zn anode surface. Herein, a novel bifunctional electrolyte—zinc gluconate, is employed as a new zinc salt for Zn-ion battery. This electrolyte possesses two important functions: acting as a nontoxic and even drinkable Zn salt to conduct stable and efficient electrochemical reactions of zinc plating/stripping, and supplying gluconate anions to construct artificial stable anionic interface for dendrite-free Zn deposition. Theoretical simulations and in-situ digital holography technology reveal the preferentially and horizontally adsorbed gluconate anions on metallic Zn to shield protuberances and fill concaves. As a result, an efficient and dendrite-free Zn anode interface can be simply achieved using 0.3 M zinc gluconate electrolyte without other electrolyte additives. This bifunctional zinc gluconate integrates cationic Zn2+ source and anionic gluconate interface, which provides a simple yet practical solution to stable and dendrite-free Zn anode.