Multifunctionalized Supramolecular Cyclodextrin Additives Boosting the Durability of Aqueous Zinc-Ion Batteries.

The poor cycling stability of aqueous zinc-ion batteries hinders their application in large-scale energy storage due to uncontrollable dendrite growth and harmful hydrogen evolution reactions. Here, we designed and synthesized an electrolyte additive, -methylimidazolium-β-cyclodextrin -toluenesulfonate (NMI-CDOTS). The cations of NMI-CD are more easily adsorbed on the abrupt Zn surface to regulate the deposition of Zn and reduce dendrite generation under the combined action of the unique cavity structure with abundant hydroxyl groups and the electrostatic force. Meanwhile, -toluenesulfonate (OTS) is able to change the Zn solvation structure and suppress the hydrogen evolution reaction by the strong interaction of Zn and OTS. Benefiting from the synergistic role of NMI-CD and OTS, the Zn||Zn symmetric cell exhibits superior cycling performance as high as 3800 h under 1 mA cm and 1 mA h cm. The Zn||VO full battery also shows a high specific capacity (198.3 mA h g) under 2.0 A g even after 1500 cycles, and its Coulomb efficiency is nearly 100% during the charging and discharging procedure. These multifunctional composite strategies open up possibilities for the commercial application of aqueous zinc-ion batteries.