B‐Modified Ti 3 C 2 T x Electrode via H 3 BO 3 Annealing Strategy for Enhanced Supercapacitance

Although Ti 3 C 2 T x is an exceptional energy storage material due to its high capacitance, tunable surface functional groups, and excellent electrical conductivity, a disordered interfacial environment caused by the inherent surface terminal groups on the Ti 3 C 2 T x nanosheets causes the slowing of the ion transport kinetics and decrease of the specific capacitance. A simple boron modified Ti 3 C 2 T x surface strategy is developed to covalently anchor boron species onto the Ti 3 C 2 T x surface via B–O–Ti bonds in the present work, B modified Ti 3 C 2 T x electrode material (B‐Ti 3 C 2 T x −400) is obtained and its structure, surface chemistry, and the electrochemical performance are systematically investigated. The modified boron species reorganize the local interfacial environment of Ti 3 C 2 T x nanosheets, reduce ion diffusion resistance, and enhance accessibility of active sites, thus significantly improve the specific capacitance and rate performance, and the as‐prepared B‐Ti 3 C 2 T x −400 material electrode exhibits a high specific capacitance of 491 F g −1 . Moreover, the assembled B‐Ti 3 C 2 T x ‐400‐based symmetric supercapacitor achieves an energy density of 7.94 Wh kg −1 (at 400 W kg −1 ) and retains 88.5% of its initial capacitance over 10,000 charge–discharge cycles at 50 mV s −1 . This work offers a facile and practical strategy for optimizing the energy storage performance of Ti 3 C 2 T x ‐based energy storage materials through surface chemical modification approach.