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, N-methylimidazolium-β-cyclodextrin p-toluenesulfonate (NMI-CDOTS). The cations of NMI-CD⁺ are more easily adsorbed on the abrupt Zn surface to regulate the deposition of Zn²⁺ and reduce dendrite generation under the combined action of the unique cavity structure with abundant hydroxyl groups and the electrostatic force. Meanwhile, p-toluenesulfonate (OTS^-) is able to change the Zn²⁺ solvation structure and suppress the hydrogen evolution reaction by the strong interaction of Zn²⁺ 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^-2 and 1 mA h cm^-2. The Zn||V₂O₅ full battery also shows a high specific capacity (198.3 mA h g^-1) under 2.0 A g^-1 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.