MoSe₂/TiO₂ heterostructure integrated in N-doped carbon nanosheets assembled porous core–shell microspheres for enhanced sodium storage

Engineering the structure and composition of electrode materials is one of the essential means for achieving excellent electrochemical performance. The rational design of Na⁺ host materials is still a massive challenge for sodium ion batteries (SIBs). Herein, MoSe₂/TiO₂ heterostructure is integrated with N-doped carbon nanosheets to assemble into hierarchical flower-like porous core–shell microspheres (MoSe₂/TiO₂@N-C), which is firstly reported by room-temperature stirring coupled with vulcanization treatment. The cavity of the core–shell structure could provide enough storage space for Na⁺ and alleviate the volume expansion during charge/discharge processes. The apertures between nanosheets provide a guarantee for the rapid penetration of electrolyte to enhance the utilization rate of electrode materials. Furthermore, building heterostructures by combining different phase structures can facilitate electron transfer and accelerate reaction kinetics. Benefiting from the synergistic contributions of structure and composition, MoSe₂/TiO₂@N-C as SIBs anode material shows better reversible capacities of 302.5 mAh·g⁻¹ at 1 A·g⁻¹ for 400 cycles and 217.4 mAh·g⁻¹ at 4 A·g⁻¹ for 900 cycles. Strikingly, the reversible capacities can be restored entirely to the initial level after a high current density cycle.