Vertically Aligned Carbon Nanotubes Grown on Copper Foil as Electrode for Electrochemical Double Layer Capacitors

Abstract

This study presents the synthesis and electrochemical analysis of vertically aligned carbon nanotubes VACNTs directly grown on Cu foil substrates using a plasma enhanced chemical vapor deposition (PECVD) technique for electrochemical double layer capacitor (EDLC) applications. The VACNTs exhibit a highly uniform and dense array with direct attachment and strong adhesion to the Cu substrate, which minimizes contact resistance and enhances electrical conductivity. The Cyclic voltammetry (CV) results reveal that the VACNT-based electrode has a specific capacitance (Csp) of 8 Fg-1 at a scan rate of 5 mV/s. The Nyquist plot shows a low equivalent series resistance of 3.70  and a charge transfer resistance of 0.48 , resulting from the direct attachment of the VACNTs to the Cu current collector. This enables efficient electron transfer and rapid ion diffusion, crucial for high-power energy storage devices. The electrode also exhibits excellent rate capability and high cycling stability, retaining 92 % of its initial specific capacitance after 3000 cycles. These results demonstrate the potential of directly grown VACNT-based electrodes for high-performance EDLCs, particularly in applications requiring rapid charge-discharge cycles and sustained energy delivery.

Keywords: VACNTs, PECVD, copper substrate, EDLC, Specific capacitance, Supercapacitor