Robust fluorine-rich YF artificial interfacial layer for providing uniform Zn flux and enhancing cycling stability of Zn anodes.

Zn metal anodes have emerged as promising candidates for aqueous Zn-based energy storage devices owing to their high theoretical specific capacity, low redox potential, and abundance of raw materials. However, sluggish Zn kinetics and uneven electric-field distribution at the interface between the Zn anode and electrolyte can lead to the formation of harmful Zn dendrites, reducing the cycle life of both the Zn anode and Zn-based devices. Here, a structurally stable rare-earth compound, yttrium fluoride (YF), is introduced as an artificial interfacial layer for Zn anodes to facilitate Zn migration and nucleation. This modification results in a uniform Zn flux and deposition environment, effectively reducing the nucleation overpotential of Zn and enhancing the cyclic lifespan of Zn anodes. By varying the fluorine source, two different morphologies, , YF nanorods (CYF) and fluorine-rich YF nanospheres (SYF) are synthesized. The non-stoichiometric SYF nanospheres, characterized by abundant fluorine-containing zincophilic sites, demonstrate superior performance in optimizing the Zn migration and deposition behaviors. The SYF@Zn-based symmetric cell exhibits stable cycling for over 1000 h at 5 mA cm while maintaining a low and stable polarization voltage. The SYF@Zn//Cu half-cell demonstrates stable cycling performance over 6000 cycles, with a total operating time exceeding 2400 h at 5 mA cm. Furthermore, a Zn-ion capacitor based on SYF@Zn and activated carbon exhibits a high-capacity retention of 74% after 40 000 cycles at 1 A g, demonstrating excellent cycling stability. The excellent electrochemical performance of SYF@Zn is attributable to accelerated interfacial Zn migration, uniform Zn flux, and reversible Zn plating/stripping. These findings provide valuable insights for the development of advanced dendrite-free reversible Zn anodes and Zn-based energy storage devices.