The effects of local graphitization on the charging mechanisms of microporous carbon supercapacitor electrodes

Abstract

The electrochemical quartz crystal microbalance (EQCM) technique has been used to study the charge mechanisms in two TiC-derived nanoporous carbons (CDC), synthesized at 800 ℃ and 1100 ℃. These two carbons have a similar pore size and porous volume, but the CDC prepared at 1100 °C shows a more graphitic microstructure. The EQCM study revealed that the charge storage mechanism in the CDC-800 is mainly controlled by a counter-ion adsorption process, while an expanded ion-exchange process was observed for the CDC-1100. Combined with the potential of zero charge (PZC), these measurements suggest a strong interaction between the anions and graphitic carbon. For the first time, we provide experimental evidence that the local carbon structure affects the charge storage mechanism of the electrical double-layer capacitance in high surface area porous carbons.