Oxygen plasma-engineered ZnF2 with built-in electric field enables rapid Zn2 <b>+</b> transport for robust Zn metal batteries

Abstract

Aqueous zinc metal batteries are an attractive candidate for next-generation energy storage, yet their application is still impeded by uncontrollable zinc dendrite growth, anode corrosion, and parasitic hydrogen evolution side reaction. Benefiting from its corrosion-resisting property and low desolvation energy barrier for hydrated Zn2+ ions, ZnF2 emerges as a promising protective material for zinc anodes. However, the migration kinetics of Zn2+ in ZnF2 is insufficient, thereby causing severe interfacial polarization and uneven Zn deposition. Herein, we develop an oxygen plasma-engineered ZnF2 interlayer (ZnO/ZnF2) on the zinc anode utilizing the built-in electric field to accelerate the transfer kinetics of Zn2+. Both experimental and theoretical findings reveal that the formation of ZnO/ZnF2 heterojunction can also raise the energy barrier for hydrogen evolution, inhibit side reactions, homogenize the electric field, and promote uniform Zn2+ plating. Remarkably, the symmetric cell based on ZnO/ZnF2@Zn demonstrates exceptional cycling stability up to 2000 and 550 h at 1 and 20 mA cm−2, respectively. When paired with an NH4V4O10 (NVO) cathode, the ZnO/ZnF2@ZnǁNVO full cell achieves a notable specific capacity of 280.9 mAh g−1 and maintains 85% of its initial capacity after 1000 cycles even under a high current density of 3 A g−1, highlighting the efficacy of plasma-engineering strategy in developing advanced zinc metal batteries.