Facet-governed Zn homoepitaxy via lattice potential regulation

Abstract

The irreversibility of the Zn anode stemming from disordered Zn deposition and rampant hydrogen evolution has been a formidable challenge, impeding the practical advancement of aqueous Zn-ion batteries. Directing the epitaxial deposition of polycrystalline Zn at the anode/electrolyte interface is appealing to address the obstacle, but remains poorly explored. Here, a comprehensive strategy by employing facet-governed homoepitaxy of polycrystalline Zn via lattice potential regulation is reported. The crystallinity of the Zn substrate could be significantly improved during the growth of a prototype fluoride-contained overlayer by chemical vapour deposition. This treatment establishes a periodic lattice potential field for Zn deposition. The introduction of an overlayer promotes the uniform nucleation of Zn at the infancy stage of electrodeposition. To counteract the tip effect of Zn growth, an ionic liquid is concurrently employed to alleviate Zn²⁺ accumulation throughout cation adsorption, fostering stable orientational deposition. Such an additive can also reduce water activity, effectively inhibiting hydrogen evolution. The thus-derived Zn anodes demonstrate decent durability even at a low N/P ratio. This work unlocks a new opportunity for guiding epitaxial Zn deposition toward pragmatic Zn anodes.