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

Abstract

• A new carbon-coated MoS 2 /N-doped carbon nanotubes composite has been designed. • The in-situ conversion growth strategy proposed is simple, and high-efficient. • The C-MoS 2 /NCNTs electrode prepared delivers a remarkable sodium storage behavior. • The unique structural merits contribute to the superior electrochemical performance. Layered structure MoS 2 nanosheets have shown great potential for energy storage applications. However, the methodology for elaborately controllable growth of MoS 2 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-MoS 2 /NCNTs product undergoes a dissolution-recrystallization process, in which ultrathin carbon layer-coated MoS 2 nanosheets densely assembled onto the surface of polyimide (PI) derived N-doped carbon nanotubes (CNTs). Theoretical simulation reveals that MoS 2 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-MoS 2 /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 MoS 2 interlayer distance, ultrathin outer carbon coating, and N-doped CNTs matrix together accounts for the outstanding sodium storage capability for the C-MoS 2 /NCNTs electrode.