  Hierarchical C@MoS2@C hollow spheres with the active MoS2 nanosheets being
sandwiched by carbon layers have been produced by means of a modified template
method. The process applies polydopamine (PDA) layers which inhibit morphology
change of the template thereby enforcing the hollow microsphere structure. In
addition, PDA forms complexes with the Mo precursor, leading to an in-situ
growth of MoS2 on its surface and preventing the nanosheets from agglomeration.
It also supplies the carbon that finally sandwiches the 100-150 nm thin MoS2
spheres. The resulting hierarchically structured material provides a stable
microstructure where carbon layers strongly linked to MoS2 offer efficient
pathways for electron and ion transfer, and concomitantly buffer the volume
changes inevitably appearing during the charge-discharge process.
Carbon-sandwiched MoS2-based electrodes exhibit high specific capacity of
approximately 900 mA h g-1 after 50 cycles at 0.1 C, excellent cycling
stability up to 200 cycles, and superior rate performance. The versatile
synthesis method reported here offers a general route to design hollow sandwich
structures with a variety of different active materials.
