Gas-Phase Conversion Promising Controlled Construction of Functional ZnF2/V2CTx for Stabilizing Zn Metal Anodes Toward Aqueous Zinc-Ion Batteries

Abstract

The practical application of aqueous zinc-ion batteries (AZIBs) is impeded by notorious side reactions occurring at the zinc anode including zinc dendrite growth, hydrogen evolution reaction and anodic corrosion. To address these issues, ZnF₂ combined with V₂C MXene composite (ZnF₂/V₂CT_x) is in-situ synthesized from V₂ZnC MAX through a facile gas-phase fluorination strategy and utilized as an efficient protective coating layer for Zn anode. The ionically conductive and hydrophobic ZnF₂ inhibits hydrogen evolution reaction and promotes uniform distribution and migration of Zn²⁺. Meanwhile, the electronically conductive V₂CT_x effectively homogenizes the electric field and reduces local current density. Consequently, a stable, dendrite-free Zn anode with excellent cycling stability (over 2100 h at 3.0 mA cm⁻²) is achieved. Furthermore, ZnF₂/V₂CT_x coating layer not only significantly improves the reversibility of zinc deposition/stripping, but efficiently reduces the electrochemical polarization. When paired with a zinc vanadate (Zn₂V₂O₇ and ZnV₃O₈) cathode derived directly from the gas-phase oxidation of V₂ZnC, the full cells exhibit a 1000-cycle lifespan at 5.0 A g⁻¹, and superior rate performance (≈237.6 mAh g⁻¹ at 10.0 A g⁻¹). This work presents a novel and efficient strategy to controllably construct MAX phase derivatives for next-generation AZIBs.