MoS2 nanosheets vertically grown on reduced graphene oxide via oxygen bonds with carbon coating as ultrafast sodium ion batteries anodes

Rational material design is a key to develop high performance electrode for sodium ion batteries (SIBs). Sandwich-like graphene@MoS2@C sheets (G@MS@C), with MoS2 nanosheets perpendicularly connecting with reduced graphene oxide (rGO) through the direct chemical coupling (COMo bonds), are synthesized by a facile two-step method, which involves in situ growth of MoS2 on rGO sheets and a followed amorphous carbon coverage process. The interfacial interaction via the COMo bonds can accelerate electron transport rate and enhance structural stability of G@MS@C electrode. Meanwhile, the vertical nanostructure provides more active sites and short diffusion distance for sodium ion reaction, leading to fast electrode reaction kinetics. The rGO sheets and carbon shells not only improve the electrical conductivity of the composite, but also act as buffers to accommodate the volume changes of MoS2 and ensure the integrity of the electrode during cycling. As an anode material for SIBs, the G@MS@C electrode shows superior reversible capacity (520 mAh g−1 after 110 cycles at 100 mA g−1), excellent rate capability (304 mAh g−1 after 200 cycles at 5 A g−1) and stable cycling performance (260 mAh g−1 after 300 cycles at 10 A g−1).

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