Electrochemically synthesized and vertically aligned carbon nanotube-polypyrrole nanolayers for high energy storage devices

In this work, we successfully demonstrate the fabrication of vertically aligned carbon nanotube (VACNT)-polypyrrole (PPY) nanocomposites as a hybrid supercapacitor material directly integrated on silicon-based electrodes. In contrast to previous works, three distinctive achievements have been accomplished: (1) a hybrid supercapacitor using VACNT forest with electroplated PPY and dodecylbenzenesulfonate (DBS) as a dopant in acetonitrile, (2) realizing 500% higher capacitance as compared to the capacitance of electrodes made of VACNT or DBS-doped PPY alone, and (3) highly reversible cycling between -1 V and +1 V with improved knee frequency at 797 Hz. As such this hybrid nanocomposite could become a new class of material for future supercapacitors. We also demonstrate the life-cycle stability of the VACNT-PPY nanocomposite supercapacitor, as well as its rapid charge-discharge capabilities and low leakage current. Electrochemical impedance modeling results suggest that the VACNT-PPY supercapacitor has higher electric double layer capacitance in addition to higher pseudocapacitance compared to uncoated VACNTs. (C) 2014 Elsevier B.V. All rights reserved.