Reconstructing the solvation structure and solid-liquid interface enables dendrite-free zinc-ion batteries

Dendrite growth and side reactions are culprits leading to the short lifespan and low Coulombic efficiency in aqueous Zn-ion batteries. Electrolyte engineering has been considered as the most facile and efficient strategy to overcome the above issues. Herein, introducing trace zinc gluconate to adjust the content of the strong H-bond in a conventional ZnSO4 electrolyte is proposed to achieve a stable Zn anode. Experimental measurements demonstrate that the solvation configuration around Zn ions has been evidently reconstructed due to the intensive coordination ability of gluconate anions. At the same time, gluconate anions electrostatically adsorb on the Zn metal surface, forming a new solid-liquid interface. As such, side reactions with water molecules and the self-corrosion of Zn metal have been significantly suppressed due to the newly formed solvation structure and interface, restraining the growth of dendrites. Impressively, the cycling life of the Zn||Zn symmetric cell in the modified electrolyte is able to sustain as long as 1500 h even at 5.0 mA cm−2. The as-assembled NH4V4O10||Zn full cell also realizes 1000 cycles with only 0.0049% capacity decay per cycle. This study offers a facile yet pragmatic route for the design of a multifunctional electrolyte for a superior stable Zn-metal anode.