Comparative evaluation of PPyNF/CoOx and PPyNT/CoOx nanocomposites as battery-type supercapacitor materials via a facile and low-cost microwave synthesis approach

Abstract

Two nanocompisitees with different morphologies of polypyrrole nanofibers/cobalt oxide (PPyNF/CoOx) and polypyrrole nanotubes/cobalt oxide (PPyNT/CoOx) were successfully prepared via a rapid and cost-efficient microwave approach. The micromorphology, surface chemical and crystalline structure of the resultant samples were characterized by FT-IR, XRD, SEM and XPS. Besides, electrochemical performances of the as-produced nanocompisitees with different mass ratio, microwave powers and times were further investigated as a battery-type electrode materials for supercapacitors. It was found that the maximum capacitance of PPyNF/CoOx could reached up to 270C g−1 at 1 A g−1, as well as with good cycling stability (almost nothing capacitance loss after 1000 cycles). Compared to PPyNF/CoOx, PPyNT/CoOx, showed a lower specific capacitance of 167.5C g−1 at the same current density. Surprisingly, the specific capacitance of PPyNT/CoOx could be further increased by 166% (278.4C g−1 at 1 A g−1) after 1200 cycles, and the cycling stability with nearly 105% of the initial capacitance could be achieved after 4000 cycles. Moreover, the asymmetric supercapacitor device based on the PPyNF/CoOx//active carbon showed a maximum gravimetric energy density of 24.22 Wh kg−1 and power density of 6.8 kW kg−1, testifying its enormous potential for energy storage devices.