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 cetyltrimethylammonium bromide (CTAB). The structure and electrochemical properties of few-layered MoS2 have been characterized and explored in detail. The results show that ions intercalation causes an interlayer spacing change of the obtained MoS2, and that the prepared few-layered MoS2 exhibits fairly good specific capacitance (330.8 F g-1 at 2.0 A g-1), a high rate capability (specific capacitance can still retain 256 F g-1 at 40 A g-1) and good cycle stability (capacitance can retain 88.8 % over 5000 cycles). Furthermore, different from most of the current literatures in which MoS2's capacitance is generally attributed to electric double-layer capacitance, the relationships between current responses and scan rates uncover that few-layered MoS2's capacitance mainly comes from intercalation pseudo capacitance. The result of this work predicts that few layered-MoS2 can be developed as a promising electrode material for energy storage.