In Situ Zn ²⁺ Etching of MXene Coating Unlocks 5000-Cycle Dendrite-Free Zinc Anodes

Zinc-ion batteries are hindered by the poor reversibility of zinc anodes from dendrite growth and side reactions. MXene coatings stabilize zinc deposition but typically rely on toxic fluorine-based etchants. To overcome this limitation, we developed a green in situ conversion strategy that directly transforms Ti₃AlC₂ into a protective Ti₃C₂T_<i>x</i> MXene coating on Zn (ISC-Ti₃C₂T_<i>x</i>@Zn) during battery operation using Zn²⁺ as the etchant. This process releases Al³⁺ that forms a dynamic electrostatic shield, which synergizes with the zincophilic MXene surfaces to guide uniform deposition. Consequently, the designed anode achieves exceptional stability, with symmetric cells sustaining over 5000 cycles at 10 mA cm^-2 and asymmetric cells maintaining 99.19% Coulombic efficiency over 700 cycles. This work integrates an in situ MXene synthesis strategy with advanced interface engineering, offering a novel approach for constructing durable zinc-based batteries.