Microscale and molecular regulation for molybdenum disulfide with extended layer spacing for high-performance sodium ion battery anodes

Abstract

Molybdenum disulfide (MoS2) exhibits large layer spacing (0.62 nm) and considerable theoretical capacity (670 mAh g−1), which has been expected to be used as anode materials for sodium ion batteries (SIBs). However, MoS2 prepared by traditional hydrothermal method has the disadvantages of poor conductivity, easy agglomeration and uncontrollable morphology. Therefore, in this work two kinds of carbonaceous materials (carbon nanotubes and nitrogen doped carbon) are used to improve the electrochemical sodium storage ability of MoS2 at the molecular level and micron scale by one-pot hydrothermal method. Among them, carbon nanotubes contribute greatly to the conductivity and morphology of the composites at the micron scale, while cetyltrimethylammonium bromide (CTAB) derived nitrogen doped carbon is inserted into the interlayer of MoS2 crystal at the molecular level to realize the layer by layer protection of MoS2. Meanwhile, it is found that the CTAB addition amount of 1.5 mmol for the optimized experiment can provide the best electrochemical performance of the final modified MoS2 electrode materials. Experiments show that the synergistic dual-carbon MoS2 composite has uniform diameter of 1 μm flower ball morphology, excellent conductivity and improved cycle stability along with a high capacity of 350 mAh g−1 at 1A g−1 after 500 cycles, showing a high capacity retention rate of 89.4%. This work may develop a simple and effective way to synthesis high performance two-dimensional MoS2 composite anode for SIBs.