Interlayer engineering and electronic regulation of MoSe2 nanosheets rolled hollow nanospheres for high-performance sodium-ion half/full batteries

Layered transition metal dichalcogenides are promising candidates for sodium storage but suffering from low intrinsic electronic conductivity and limited interlayer spacing for fast electron/ion transport, which restricts their high-rate capability and cycling stability. In this work, rGO@MoSe₂/NAC hierarchical architectures, consisting of conductive reduced graphene oxide (rGO) supported by hollow nanospheres that are rolled from superlattices of alternatively overlapped MoSe₂ and N-doped amorphous carbon (NAC) monolayers, are synthesized as a high-performance sodium storage anode. Theoretical calculations reveal the intercalation of NAC monolayer between two adjacent MoSe₂ monolayers improving electronic conductivity of MoSe₂ in both surface and internal bulk to fully accelerate electron transport and enhance Na⁺ ​adsorption. The interoverlapped MoSe₂/NAC superlattice featuring a wide interlayer expansion (72.3 ​%) of MoSe₂ dramatically decreases Na⁺ ​diffusion barriers for fast insertion/extraction. Moreover, the hollow nanospheres and the rGO conductive network contribute to a robust hiberarchy that can well release internal stress and buffer the volume expansion, thereby enabling outstanding structural stability. Consequently, the rGO@MoSe₂/NAC anode exhibits excellent high-rate capability of 194 mAh g⁻¹ and ultralong cyclability of 12 ​000 cycles with a low capacity fading rate of 0.0038 ​% per cycle at an ultra-high current of 50 ​A ​g⁻¹, delivering the best high-rate cycling performance to date. Remarkably, the Na₃V₂(PO₄)₃‖rGO@MoSe₂/NAC full cells also present outstanding cycling stability (600 cycles) at 10C rate, which proves the great potential in fast-charging applications.