Tailoring Carbon Nanostructure for High Frequency Supercapacitor Operation

Pritesh Hiralal,Gehan A J Amaratunga,Piers Andrew,Masamichi Yoshimura,Gemma Rius

doi:10.1155/2014/619238

Abstract

The possibility of enhancing the frequency performance of electrochemical capacitors by tailoring the nanostructure of the carbon electrode to increase electrolyte permeability is demonstrated. Highly porous, vertically oriented carbon electrodes which are in direct electrical contact with the metallic current collector are produced via MPECVD growth on metal foils. The resulting structure has a capacitance and frequency performance between that of an electrolytic capacitor and an electrochemical capacitor. Fully packaged devices are produced on Ni and Cu current collectors and performance compared to state-of-the-art electrochemical capacitors and electrolytic capacitors. The extension of capacitive behavior to the AC regime (~100 Hz) opens up an avenue for a number of new applications where physical volume of the capacitor may be significantly reduced.

Highlights

Electrical energy storage devices exploit a range of charge storage mechanisms, ranging from purely physical processes, as employed in dielectric capacitors, all the way to the full electrochemical reactions employed in batteries
The synthesis is driven by field-boosted mechanism(s), and the result is advantageous as it generally consists of single step processing with very reasonable deposition rates [16]
The 2D peak width (FWHM ∼83 cm−1) indicates that the material consists of multilayer graphene, precision in the number of layer determination is compromised, by the carbon nanowalls (CNWs) vertical orientation

Summary

Introduction

Electrical energy storage devices exploit a range of charge storage mechanisms, ranging from purely physical processes, as employed in dielectric capacitors, all the way to the full electrochemical reactions employed in batteries. These different mechanisms result in remarkable performance variation between the various technologies. Dielectric capacitors store energy in the electric field arising from polarization of highly mobile surface charges. These devices have the capability of high frequency operation, but their overall energy storage density is small. Supercapacitors have a battery-like structure, consisting of electrodes and an electrolyte, but store charge in an electric field like a dielectric capacitor [1]

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Conclusion