β-cyclodextrin as an electrolyte additive for enhancing electrochemical performance of aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are considered as highly promising energy storage devices owing to their high safety, low cost, and environmental benignity. Nevertheless, the uncontrollable growth of Zn dendrites and severe interfacial side reactions remain critical challenges that restrict their practical application. β-Cyclodextrin (β-CD), which features abundant hydroxyl groups and a unique cavity structure, can regulate the solvation structure of Zn ions, reduce the nucleation overpotential, induce uniform Zn deposition, and suppress dendrite formation and parasitic reactions. In this work, β-CD was introduced as an electrolyte additive, and its optimal content was systematically explored. The Zn||Zn symmetric cell with the optimized β-CD electrolyte exhibits an ultra-long cycle life of 850 h at 2 mA·cm and 1 mAh·cm. Meanwhile, the Zn||Cu half-cell exhibits a stable Coulombic efficiency (CE) of 99.85% for 322 cycles. For the Zn||MnO full cell, it delivers an initial discharge specific capacity of around 133 mAh g and retains 87% of its capacity after 812 cycles at a current density of 1 A g. This work provides a feasible strategy for stabilizing Zn anodes and demonstrates great potential for the practical application of β-CD in high-performance AZIBs.