Low-Cost Electrolyte Additive Enables an Ultra-stable and Dendrite-Free Zn Anode

With their cost-effectiveness and superior safety features, zinc-ion batteries (ZIBs) have emerged as highly promising energy storage systems. However, severe Zn dendrites and harmful side reactions exist on the Zn surface during cycling, resulting in poor coulombic efficiency (CE) and cycling stability. Herein, the above problems have been solved by adding sodium gluconate (Ga) additive in a 2 M ZnSO4 (ZSO) electrolyte (ZSO–0.05Ga). On the one hand, the Ga additive is adsorbed on the surface of the Zn metal anode to form a protective layer, which effectively reduces the corrosion reaction and induces uniform deposition. On the other hand, the strong adsorption capacity between Ga and Zn2+ in the electrolyte can change the solvation structure of Zn2+, thereby effectively inhibiting the generation of side reactions. Thus, a Zn||Zn symmetric battery with a ZSO–0.05Ga electrolyte can be cycled stably for more than 2700 h at a current density of 1 mA cm–2; the Zn||Cu half-battery has an ultrahigh stability of 500 cycles; and the average charge–discharge efficiency reaches 99.2%. In addition, the Ga additive greatly improves the cycle stability of the Zn||AC battery (89.3% after 1000 cycles at 1 A g–1). This electrolyte additive with co-regulation functions of the solvation shell and interface adsorption effect provides an idea for improving the stability of the Zn anode for further application of ZIBs.