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MoS 2 has been intensively studied as a promising anode material for high capacity lithium ion batteries (LIBs), which is strongly limited by its poor cycling stability and inferior rate performance. In this work, the strategy of interlayer spacing engineering is applied on MoS 2 to effectively expand the interlayer spacing from 0.62 nm to 0.98 nm, with the addition of ւ-cysteine during hydrothermal process. The cycling stability is significantly improved. The composites of interlayer expanded MoS 2 and graphene oxide are further treated by N plasma to effectively dope N into both reduce graphene oxide and MoS 2. The final product exhibits outstanding electrochemical performance as anode in LIBs, with high reversible capacity of 643 mA h·g−1 after 400 cycles at the rate of 500 mA g−1 and excellent rate capacity of 580 mA h·g−1 up to the rate of 2000 mA g−1. This work demonstrates that proper nanostructure engineering and electronic structure modification can make MoS 2 a promising electrode material in highly fast and stable energy storage applications. Image 1 • MoS 2 with enlarged interlayer spacing were synthesized. • Few-layered MoS 2 nanosheets grow vertically on GO sheets. • N plasma treatment is applied on GO/ISE-MoS 2 composites. • N has been uniformly doped into both rGO and MoS 2. • N-rGO/ISE-MoS 2 exhibits excellent reversible and rate capacity. [ABSTRACT FROM AUTHOR]

Petal-like graphene oxide-MoS 2 (GO-MoS 2) composites are prepared by the hydrothermal method. The structural characterizations confirm the metallic phase (1T) of MoS 2 sheets with a few layers, and the uniform distribution of graphene oxide (GO) and MoS 2. However, the functional groups on the surface of GO and the intrinsic low conductivity of MoS 2 lead to the poor electrochemical performance of GO-MoS 2 in lithium ion batteries. N-doped GO-MoS 2 (N-GO-MoS 2) composites are prepared by N plasma treatment on GO-MoS 2 composites at room temperature. N is clearly confirmed to be doped into both graphene oxide and MoS 2 uniformly, and MoS 2 changes to semiconducting phase (2H). In lithium ion batteries, it is found that the initial capacity increases from 561.4 mAh g−1 for GO-MoS 2 to 726.9 mAh g−1 for N-GO-MoS 2 at 1 C. After 100 cycles, N-GO-MoS 2 still exhibits capacity of 592.7 mAh g−1 (1.34 mAh g−1 loss per cycles and 81.5% capacity retention rate), which is much better than that of GO-MoS 2 (only 31.6 mAh g−1 after 100 cycles). The significantly improved high-rate cycling electrochemical performance for N-GO-MoS 2 can be attributed to the improved stability of MoS 2 by the phase transition from 1T to 2H, the enhanced electron transportation by the reduction of graphene oxide to graphene and the simultaneous N doping in MoS 2 and graphene oxide. Image 1 • N plasma treatment is applied on graphene oxide (GO)-MoS 2 composites (N-GO-MoS 2). • N has been successfully doped into both GO and MoS 2. • The structure of MoS 2 transforms from the metallic phase (1T) to semiconducting phase (2H). • The electrochemical performance of N-GO-MoS 2 anode has been significantly improved due to better electronic conductivity. [ABSTRACT FROM AUTHOR]