Investigating the effect of vacuum impregnation of supercapacitor electrode in electrolyte

Abstract

Supercapacitors provide much higher power density than conventional batteries, while providing comparable energy density. Generally, porous materials like activated carbon, carbon nanotubes etc. are used to fabricate supercapacitor electrodes. A critical factor influencing the performance of the supercapacitor is the effective surface area of the porous electrode accessed by the electrolyte ions. The electrode micro-structure, the size of the electrolytic ions, etc. influence the effective surface area. It is hypothesized that due to the presence of air bubbles in the finer pores of the electrode, the electrolyte ions are unable to access the electrode surface easily. In the present work, the effect of vacuum impregnation of the electrode in improving the effective surface area is investigated. Activated carbon-based supercapacitor electrodes are fabricated and characterized by electrochemical techniques, before and after vacuum impregnation. Vacuum impregnation is seen to result in higher energy density but lower power density, and this is thought to be linked to easier access to deeper and finer pores on the electrode surface.