Intercalation pseudo-capacitance behavior of few-layered molybdenum sulfide in various electrolytes

Abstract The insertion and de-insertion of ions in layered materials are important processes during the energy storage. The investigation on the preparation and electrochemical properties of layered materials attracts a lot of attention. Here, few-layered MoS2 nanosheets are prepared by solvothermally treating ammonium tetrathiomolybdate ((NH4)2MoS4) in the presence of hydrazine and cetyltrimethyl-ammonium bromide (CTAB). The structure of few-layered MoS2 is explored in detail. Obviously, the ions intercalation causes an interlayer spacing change by XRD patterns. Furthermore, different from MoS2’s capacitance generally attributed to EDLC in most of the current literatures, the relationships between current responses and scan rates uncover that the material’s capacitance mainly comes from intercalation pseudo capacitance, and that the prepared few-layered MoS2 also exhibits preferable specific capacitance (330.8 F g-1 at 2.0 A g-1), a great rate capability (the specific capacitance can still retain 256 F g-1 at 40 A g-1) and good cycle stability (the capacitance can retain 88.8 % over 5000 cycles). This result predicts that few layered-MoS2 can be developed as a promising electrode material for energy storage.