Construction of a multifunctional Ti₃C₂T_x MXene/g-C₃N₄ artificial protective layer for dendrite-free aqueous Zn-ion batteries

The electrochemical utilization of Zn anodes in aqueous batteries is hampered by the intricate and interconnected issues of Zn dendrite growth, H₂ evolution and Zn corrosion reactions. In this study, a multifunctional protective layer comprising MXene and graphitic carbon nitride (g-C₃N₄) was constructed using a self-assembly strategy. The MXene/g-C₃N₄ protective layer exhibited robust zincophilic characteristics, which facilitated a uniform distribution of the electric field and ensured a sufficient influx of Zn²⁺. This reduces the Zn²⁺ nucleation barrier and prevents dendrite growth. In addition, the hydrophobic nature of the protective layer, coupled with its negative charge, can repel SO₄²⁻ and select water molecules from the electrolyte, which aids in mitigating corrosion and H₂ evolution. The symmetric Zn cell coated with the MXene/g-C₃N₄ protective layer showed remarkable stability, achieving over 2000 h of reversible cycling at 1 mA·cm⁻². Furthermore, the MXene/g-C₃N₄-coated Zn anode paired with a sodium-doped V₂O₅ cathode (NVO) exhibited enhanced cycling capability over 1500 cycles.