Conductivity enhancement of CO2 activated high surface area carbon aerogel using high temperature treatment

Abstract

High specific surface area carbon aerogels are being studied for various electrochemical applications. Their utility in these applications is limited due to moderate electrical conductivity. The current manuscript briefs about the effect of high temperature (HT) treatment (-1400 °C) on the conductivity and surface properties of resorcinol-formaldehyde (R-F) based carbon aerogels. Aqueous medium based carbon aerogel with high specific surface area (1796 m2/g) was synthesized by R-F gelation, ambient drying followed by CO2 activation treatment. The samples of carbon aerogel with HT treatment (CA-HT) were characterized for textural properties, conductivity, X-ray diffraction and specific capacitance. The specific surface area of CA-HT (1742 m2/g) showed only marginal decrease after HT treatment mainly due to partial collapse of micropores. The bulk electrical conductivity of CA-HT showed ∼ 35% improvement over the untreated CA with respective values of 165 S/m and 115 S/m. The specific capacitance for both CA and CA-HT were evaluated nearly ∼ 112 F/g at scan rate of 10 mV/s. For higher scan rate 100 mV/s, the CA showed drastic decrease in specific capacitance to 74 F/g, however, for CA-HT the value decreased only to 92 F/g. Equivalent series resistance (ESR), a crucial electrochemical parameter, improved to 0.5 n after HT treatment. The higher specific capacitance at faster scan rates and lower ESR for CA-HT is attributed to improvement in bulk conductivity which makes it a better choice for supercapacitor application.