In-situ conversion growth of carbon-coated MoS2/N-doped carbon nanotubes as anodes with superior capacity retention for sodium-ion batteries

Layered structure MoS2 nanosheets have shown great potential for energy storage applications. However, the methodology for elaborately controllable growth of MoS2 onto carbonaceous matrix for promoting the electrochemical performance is highly desirable. Herein, a high-effective, all-in-one in-situ conversion growth strategy has been proposed to construct a stable sandwich-type nanostructure. The formation of the optimized C-MoS2/NCNTs product undergoes a dissolution-recrystallization process, in which ultrathin carbon layer-coated MoS2 nanosheets densely assembled onto the surface of polyimide (PI) derived N-doped carbon nanotubes (CNTs). Theoretical simulation reveals that MoS2 nanosheets possessing an expanded interlayer spacing of 0.92 nm can greatly reduce the barrier energy of Na ions mitigation. Accordingly, the as-made C-MoS2/NCNTs anode delivers superior cycling stability (82% capacity retention after 400 cycles at 1 A g−1) and rate performance (348 mAh g−1 at 2 A g−1). The results demonstrate that the expanded MoS2 interlayer distance, ultrathin outer carbon coating, and N-doped CNTs matrix together accounts for the outstanding sodium storage capability for the C-MoS2/NCNTs electrode.