Direct Growth Of Vertically Aligned Carbon Nanotube (VACNT) On Different Conducting Substrates For Electrochemical Capacitor (EC)

Electrochemical capacitor (EC) is highly promising energy device due to its electrical charge storage performance and significant lifecycle ability. Construction of the EC cell especially its electrode fabrication is critical to ensure great application performance. The purpose of this research is to introduce direct growth of vertically aligned carbon nanotube (VACNT) on conducting substrates, namely SUS 310S, Inconel 600, and YEF 50 and their usage as symmetric VACNT electrode in EC. The substrates were deposited by alumina and cobalt catalyst thin films, and then the growth was done by using alcohol catalytic chemical vapour deposition. By this, VACNT was successfully grown and their structures (dimension, walls)have been confirmed by means of electron microscopies. The thickness of the VACNT is typically about 31.68 μm (SUS 310S) and 10.58 μm (Inconel 600), respectively which indicate that no particular agglomerated metals were observed on the exposed surface of the substrate.In contrast, the field emission scanning electron microscopy (FESEM) image obtained shows that most of the entire areas, a thicker carbon products forest/agglomerated was formed on the top surface of YEF 50 substrate. Meanwhile, the transmission electron microscopy (TEM)image reveals that the VACNT on Co/Al2O3/SUS 310S are multi-walled CNTs (MWCNTs) with the inner and outer diameter of CNTs are approximately 4.89 nm and 16.43 nm, respectively. The Raman spectra results indicate that the CNT was typical of MWCNTs,which is in agreement with the TEM observation. Regardless of the difference in current collectors being used, cyclic voltammetry (CV) analysis from the EC depicted a relatively good specific gravimetric capacitance (Csp) and rate capability performance. A nearly rectangular-shaped CV curve was observed even at a scan rate of 1000 mV s−1. The Csp measured at 1 mV s-1 was 33.35 F g-1 (SUS 310S), 16.73 F g-1 (Inconel 600), and 24.82 F g-1 (YEF 50), respectively. Besides, from the charge-discharge measurement, the symmetrical triangular curves reveal that there is no IR drops or voltage drops because of low internal resistance in the electrode for SUS 310S, Inconel 600, and YEF 50 substrates. Also, the VACNT electrode shows excellent discharge behaviour and good capacitance retention of up to 1,000 cycles. Thus, this binder free and aligned CNT structure may provide excellent rate capabilities, high capacitance, and long lifecycle energy device. This is very promising for then development of high energy and high power density of device for multi-scale applications or industries