Unraveling Na-ion storage performance of vertically-aligned interlayer-expanded two-dimensional MoS2@C@MoS2 heterostructure
Achieving hierarchically uniform surface manipulated nanostructured materials is important to accomplish the high performance storage devices, but it is still challenging. Herein, we successfully synthesized a vertically aligned interlayer expanded caterpillar-like heterostructure consisting of MoS2@C nanosheets (NSs) over MoS2 nanorods (NRs) (MoS2@C@MoS2) as an advanced anode material for sodium-ion batteries (SIBs). A step-wise ramping rate tuned MoS2 nanorods (NRs) was achieved via surface sulfurization of MoO3 NRs by vapor phase ion-exchange method. The presence of hetero-interphased MoS2@C nanosheets performed a crucial role in achieving excellent electrochemical performance by facilitating better Na+ ion diffusion and faster electron transport. The hierarchical MoS2@C@MoS2 electrode delivered a high specific capacity of 434 mAh g-1 (after 100 cycles at 100 mA g-1) and excellent cycling stability (352 mAh g-1 after 200 cycles at 1000 mA g-1). Kinetic analysis revealed that an exaggerated sodium storage performance of MoS2@C@MoS2 electrode could be accompanied with the ameliorated capacitive contribution reaction. Moreover, the sodium-ion full cell assembled with MoS2@C@MoS2 anode and Na3V2(PO)4F3 cathode demonstrated a high specific capacity of 305 mAh g-1 after 50 cycles with good capacity retention.