Molten Salt Etching of V₂AlC to Fabricate Multifunctional Coating for High-Performance Zinc-Iodine Batteries

Aqueous zinc metal batteries suffer from uncontrollable dendrite growth and undesirable side reactions, which drastically compromise the battery performance and practical application. To address these issues, an accordion-type multifunctional coating of Cu-V₂CBr₂ MXene with zincophilic and hydrophobic properties is developed by molten salt etching to achieve highly redox reversibile of zinc. Experimental results and theoretical calculations demonstrate that the -Br terminating groups have a strong electronegativity, which can electronically modify the surface of MXene, affecting the local electrochemical environment. This creates a low surface energy and a strongly hydrophobic surface, thereby inhibiting the side reactions. In addition, the in situ formation of copper nanoparticles within the interlayers provides abundant nucleation sites and promotes uniform electron distribution throughout the framework, thereby regulating Zn²⁺ ions flux and facilitating uniform zinc deposition. As a result, the symmetric cells demonstrate good rate performance and stable cycling performance for up to 1700 h at 10 mA cm^-2. The full batteries paired with iodine-loaded porous carbon cathode exhibit an excellent capacity retention of 89.3% after 5000 cycles at 5 C. This work opens a new pathway to modulate the zinc anode interface process, which can also be extended to other aqueous batteries.