Self-standing carbon nanotube forest electrodes for flexible supercapacitors

Abstract

A self-standing, vertically aligned carbon nanotube forest grown on unidirectional carbon fibers has been fabricated by using chemical vapour deposition. The vertically aligned carbon nanotube forest grown on unidirectional carbon fiber (VACNTF/UCF) was further used as an electrode-cum-current collector integrated system for fabricating a flexible supercapacitor. Highly bendable, electrically conductive unidirectional carbon fibers were used both as substrate for the growth of the carbon nanotube forest and as current collectors for the supercapacitor. No other separate current collectors were used in this study. The Brunauer–Emmett–Teller surface area of VACNTF/UCF is found to be 553.8 m² g⁻¹. The flexibility of the VACNTF/UCF supercapacitor is tested by galvanostatic charge/discharge measurements by bending the supercapacitor at various angles. No significant variations in the supercapacitive properties were observed at different bending angles. Galvanostatic charge/discharge measurements show that the supercapacitor exhibits a volume specific capacitance of 3.4 F cm⁻³ with a high volume specific power density of 1195 mW cm⁻³. The VACNTF/UCF supercapacitor also exhibits good cycling stability over more than 27 000 cycles.