Atmospheric pressure plasma-jet treatment of polyacrylonitrile-nonwovens: Activation leading to high surface area carbon electrodes

Abstract

Carbon nanofiber nonwovens (CFN) are powerful electrode materials with exceptional performance in energy storage devices, such as batteries and supercapacitors. Small fiber-diameters together with hierarchical porosity endow CFN-electrode materials with large surface areas and high electrical capacitance. Porosity of the fiber surface is often realized by corrosive activation methods such as wet-etching or using oxidative gases at elevated temperatures. In this study, we present a chemical-free, environmental-friendly, and easily controllable surface activation method using an atmospheric pressure plasma-jet. We investigate the best instant for activation along the process chain and show that the surface area of nanofiber nonwovens can be tailored by adjusting the plasma exposure-dose. Plasma-activated CFNs show an almost 20-fold increase in capacitance (CspPJ = 10.1 F/g) in an electrochemical supercapacitor setup compared to nonactivated CFN (CspnoPJ = 0.55 F/g).