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.