Synergistic Performance of Composite Supercapacitors between Carbon Nanohorn and Conducting Polymer

This paper described the electrochmical behavior of composites of carbon nanohorns (CNHs) with conducting polymers [polyaniline (PA) and polypyrrole (PP)]. The materials at different weight ratios (monomer:CNH = 1:0, 1:0.33, 1:1, 1:3, and 0:1) were prepared by the in situ polymerization method. In the case of PA-series electrodes, the specific capacitance was a maximum (762 F/g at scan rate of 5 mV/s). Meanwhile, in the PP-series electrodes, the specific capacitance gradually decreased from 769 F/g at 5 mV/s for 1:0 (pyrrole:CNH) upon increasing the content of CNHs. However, the charge transfer resistance behaved completely contrary to the dependence of specific capacitance on the composite ratio. These electrochemical results revealed the strong synergistic effect between PA and CNHs of the PA-series composites, being facilitated by fast charge transfer, small internal resistance, and preferable mechanical properties and resulting in the improved capacitance performances. Furthermore, since the composites of both polymers at 1:3 (monomer:CNH) ratio showed an excellent capacitance retention, even after 5000 cycles, both polymers strengthened their cycling stability after the hybridization with CNHs.