A study of the electrochemical behaviour of electrodes in operating solid-state supercapacitors

The electrochemical behaviour of electrodes and of complete solid-state supercapacitors has been studied by cyclic voltammetry (CV) and alvanostatic charge/discharge (CD) measurements using two independent electrochemical equipments. The first one controlled the execution of he test and recorded the voltage and current values of the complete supercapacitor while the other one recorded the potential changes of the single lectrodes. In this work, two different types of capacitors were studied: (a) a symmetric supercapacitor using carbon electrodes, and (b) a hybrid asymmetric) supercapacitor with ruthenium oxide/carbon in the positive electrode and carbon in the negative electrode. The studies evidenced that n the symmetric capacitors the positive electrode controlled the capacitive performance and an optimal mass ratio from 1.2:1 to 1.3:1 between the ositive and the negative electrodes was found in the investigated conditions. For the hybrid supercapacitor it was observed that the ruthenium-based ositive electrode influenced the capacitive performance of carbon-based negative electrode and that an accurate balance of carbon loading in the egative electrode was necessary. 2007 Elsevier Ltd. All rights reserved.