Heteroanionic Halogenated TiBT _x MBene Protective Layer With Dual‐Functional Zincophilic and Hydrophobic Characteristics for Dendrite‐Free Zinc Anode

Abstract

Abstract Two‐dimensional (2D) hexagonal transition metal borides ( h ‐MBenes), emerging members of 2D materials, demonstrate significant potential as protective layers for metal anodes. However, conventional MBenes synthesized by wet etching have massive oxygen‐containing terminations imported during the chemical synthesis process, with zincophobic and hydrophilic, resulting in severe dendrite growth kinetics and compromising electrode performance. In this study, we report a novel hetero‐halogen TiBT X (T X  = Cl and I) h ‐MBenes through a halogen‐radius‐isomerization strategy, enabling precise mixed‐halogen functionalization to create an ultrahigh zincophilic and hydrophobic microenvironment. Compared to single ‐I terminations, the mixed‐halogen TiBT X exhibits significantly enhanced zincophilicity with ordered Zn 2+ adsorption, attributed to the asymmetry‐inductive effect of the larger‐radius ‐I ions. Simultaneously, the ‐Cl moieties serve as a protective barrier, mitigating water‐induced corrosion of the Zn anode in aqueous electrolytes. Notably, the dual‐functional TiBT x ‐31 layer (TiBI 0.32 Cl 0.13 ) demonstrates exceptional electrochemical performance, achieving a prolonged cycling life exceeding 2000 h an impressive average coulombic efficiency of 99.86%. Furthermore, the TiBT x ‐31@Zn||NVO full pouch cell maintains 95.3% capacity retention over 100 cycles. This work highlights the innovative halogen‐radius‐isomerization approach for interfacial engineering by tailoring halogen terminations, offering new insights for the development of high‐performance h ‐MBenes‐based energy storage devices.