Regulating the solventized structure to achieve highly reversible zinc plating/stripping for dendrite-free Zn anode by sulfolane additive

Aqueous zinc ion batteries (AZIBs) are a kind of ideal rechargeable batteries due to their high theoretical ca-pacity, low cost and good safety. However, dendrite growth and side reactions prevent AZIBs from becoming excellent energy storage devices. Herein, an electrolyte additive of sulfolane (SL) is added to ZnSO4 electrolyte to inhibit zinc dendrite growth and side reactions. It is found that SL molecules replace water molecules in the solventized structure of [Zn(H2O)6]2+, reducing the number of highly chemically active water molecules at the interface between anode and electrolyte, thus inhibiting the growth of zinc dendrites and side reactions. As a result, a super long cycle life of > 4300 h is achieved at 2 mA cm-2/0.5 mAh cm-2 (>5700 h at 1 mA cm-2/0.25 mAh cm-2) for the Zn-Zn symmetrical cell with SL additive, which is much higher than that of the symmetrical battery without additive (50 h). The present work provides a general strategy to achieve the inhibition of zinc dendrites and side reactions via tailoring the solventized structure of [Zn(H2O)6]2+ by using small organic molecular as electrolyte additive to reduce the number of highly chemically active water molecules at the interface between zinc metal and aqueous electrolyte.