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

## TL;DR

Researchers developed a new method to grow carbon nanotubes on copper foil for energy storage devices, achieving high performance and durability.

## Contribution

A binder-free and catalyst-free fabrication method for vertically aligned carbon nanotubes on copper foil for EDLCs is introduced.

## Key findings

- The VACNTs on copper foil achieved a gravimetric capacitance of 8 F g−1 and areal capacitance of 3.5 mF cm−2.
- The electrode retained 92% of its capacitance after 3000 charge–discharge cycles, showing strong cycling stability.
- Low resistance values (3.70 Ω and 0.48 Ω) enabled efficient electron transport and rapid ion diffusion.

## Abstract

This study reports a binder-free, catalyst-free method for fabricating vertically aligned carbon nanotubes (VACNTs) directly on copper (Cu) foil using plasma-enhanced chemical vapor deposition (PECVD) for electrochemical double-layer capacitor (EDLC) applications. This approach eliminates the need for catalyst layers, polymeric binders, or substrate pre-treatments, simplifying electrode design and enhancing electrical integration. The resulting VACNTs form a dense, uniform, and porous array with strong adhesion to the Cu substrate, minimizing contact resistance and improving conductivity. Electrochemical analysis shows gravimetric specific capacitance (Cgrav) and areal specific capacitance (Careal) of 8 F g−1 and 3.5 mF cm−2 at a scan rate of 5 mV/s, with low equivalent series resistance (3.70 Ω) and charge transfer resistance (0.48 Ω), enabling efficient electron transport and rapid ion diffusion. The electrode demonstrates excellent rate capability and retains 92% of its initial specific capacitance after 3000 charge–discharge cycles, indicating strong cycling stability. 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.