In Situ Growth of Polypyrrole onto Three-Dimensional Tubular MoS2 as an Advanced Negative Electrode Material for Supercapacitor

In this work, three-dimensional (3D) tubular molybdenum disulfide (MoS2)/PPy composites have been prepared, in which the MoS2 is as the framework to promote the insertion and extraction of electrolyte ions, and PPy spherical particles or nanowires are synthesized by an in-situ oxidative polymerization method in the presence of the MoS2. FT-IR, XRD, XPS, FESEM and HRTEM are used to characterize the structures and morphologies of the as-prepared materials. The combination of conductive PPy and 3D tubular MoS2 leads to a significant synergistic effect. For MoS2/PPy particle composites, the best performance (specific capacitance of 350 F/g at a current density of 1 A/g) is obtained from a sample prepared with the mass ratio of pyrrole to MoS2 being 2:1. While for MoS2/PPy nanowire composites, the best performance (specific capacitance of 462 F/g at 1 A/g and a good cycling stability of 82% after 2000 cycles at 3 A/g) is obtained from a sample prepared with the mass ratio of pyrrole to MoS2 being 5:1, which shows much better supercapacitor performance than the MoS2/PPy composite. Moreover, the composite electrode material delivers an energy density as high as 25.5 Wh/kg at a power density of 266.3 W/kg and maintains 14.5 Wh/kg at a high power density of 4002 W/kg. These performances feature the composite as advanced negative electrode materials and are superior to previous reports.