Constructing Hierarchical Porous MoO₂@Mo₂N@C Composite via a Confined Pyrolysis Synthetic Strategy Towards Lithium-Ion Battery Anodes

Molybdenum dioxide (MoO2) demonstrates a big potential toward lithium-ion storage due to its high theoretical capacity. The sluggish reaction kinetics and large volume change during cycling process, however, unavoidably lead to inferior electrochemical performance, thus failing to satisfy the requirements of practical applications. Herein, we developed a molybdenum-based oxyacid salt confined pyrolysis strategy to achieve a novel hierarchical porous MoO2@Mo2N@C composite. A two-step successive annealing process was proposed to obtain a hybrid phase of MoO2 and Mo2N, which was used to further improve the electrochemical performance of MoO2-based anode. We demonstrate that the well-dispersed MoO2 nanoparticles can ensure ample active sites exposure to the electrolyte, while conductive Mo2N quantum dots afford pseudo-capacitive response, which conduces to the migration of ions and electrons. Additionally, the interior voids could provide buffer spaces to surmount the effect of volume change, thereby avoiding the fracture of MoO2 nanoparticles. Benefiting from the aforesaid synergies, the as-obtained MoO2@Mo2N@C electrode demonstrates a striking initial discharge capacity (1760.0 mAh g(-1) at 0.1 A g(-1)) and decent long-term cycling stability (652.5 mAh g(-1) at 1.0 A g(-1)). This work provides a new way for the construction of advanced anode materials for lithium-ion batteries.