Oxide Nanoclusters on Ti₃ C₂ MXenes to Deactivate Defects for Enhanced Lithium Ion Storage Performance

The commercialization of MXenes as anodes for lithium-ion batteries is largely impeded by low initial coulombic efficiency (ICE) and unfavorable cycling stability, which are closely associated with defects such as Ti vacancies (V_Ti ) in Ti₃ C₂ MXenes. Herein, an effective strategy is developed to deactivate V_Ti defects by in situ growing Al₂ O₃ nanoclusters on MXenes to alleviate the irreversible electrolyte decomposition and Li dendrites formation trend induced by defects, improving ICE and cycling stability. Furthermore, it is revealed that excessively lithiophilic V_Ti defects would impede Li ions diffusion due to their strong adsorption, leading to a locally nonuniform Li flux to these "hot spots," setting scene for the formation of Li dendrites. The Al₂ O₃ nanoclusters anchored on V_Ti sites can not only improve Li diffusion kinetics but also promote the homogeneous solid electrolyte interphase formation with small charge transfer resistance, achieving uniform Li deposition in a smaller overpotential without formation of Li dendrites. As expected, Ti₃ C₂ @Al₂ O₃ -11 electrode delivers a high ICE of 76.6% and an outstanding specific capacity of 285.5 mAh g^-1 after 500 cycles, which is much higher than that of pristine Ti₃ C₂ sample. This work sheds light on modulating defects for high-performance energy storage materials.