Unraveling the Na-ion storage performance of a vertically aligned interlayer-expanded two-dimensional MoS2@C@MoS2 heterostructure†
Achieving hierarchically uniform surface manipulated nanostructured materials is important to accomplish 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). Step-wise ramp rate tuned MoS2 nanorods (NRs) were achieved via surface sulfurization of MoO3 NRs by a vapor phase ion-exchange method. Heterointerphased MoS2@C nanosheets performed a crucial role in enacting an 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 mA h g−1 (after 100 cycles at 100 mA g−1) and excellent cycling stability (352 mA h g−1 after 200 cycles at 1000 mA g−1). Kinetic analysis revealed that an enhanced sodium storage performance of the MoS2@C@MoS2 electrode could be accompanied by an ameliorated capacitive contribution reaction. Moreover, the sodium-ion full cell assembled with the MoS2@C@MoS2 anode and a Na3V2(PO4)2F3 cathode exhibited a high specific capacity of 320 mA h g−1 with good capacity retention.