Spatially confined synthesis of TiNb₂O₇ quantum dots onto mesoporous carbon and Ti₃C₂T_X MXene for boosting lithium storage

TiNb₂O₇ has been emerged as one of the most promising electrode materials for highenergy lithium-ion batteries. However, limited by the slow electron/ion transport kinetics, and insufficient active sites in the bulk structure, the TiNb₂O₇ electrode still suffers from unsatisfactory lithium storage performance. Herein, we demonstrate a spatially confined strategy toward a novel TiNb₂O₇-NMC/MXene composite through a triblock copolymer-directed one-pot solvothermal route, where TiNb₂O₇ quantum dots with a particle size of 2-3 nm are evenly embedded into N-doped mesoporous carbon (NMC) and Ti₃C₂T_X MXene. Impressively, the as-prepared TiNb₂O₇-NMC/MXene anode exhibits a high reversible capacity (486.2 mAh g^-1 at 0.1 A g^-1 after 100 cycles) and long cycle lifespan (363.4 mAh g^-1 at 1 A g^-1 after 500 cycles). Both experimental and theorical results further demonstrate that such a superior lithium storage performance is mainly ascribed to the synergistic effect among 0D TiNb₂O₇ quantum dots, 2D Ti₃C₂T_X MXene nanosheets, and N-doped mesoporous carbon. The strategy presented also opens up new horizon for space-confined preparation of highperformance electrode materials.