Poly(3,4-ethylenedioxithiophene)/MnO2 composite electrodes for electrochemical capacitors

Composite electrodes of poly(3,4-ethylenedioxithiophene) and manganese oxide (PEDOT/MnO₂) have been prepared by electrodeposition of manganese oxide over PEDOT-modified titanium substrate. The PEDOT layers are deposited on titanium by potentiostatic deposition at 1.4 V and at two different temperatures: 5 and 25 °C (named PEDOT₍₅₎ and PEDOT₍₂₅₎, respectively). The electrodes are characterized by field emission gun scanning electron microscopy (FEG-SEM) and their electrochemical performances are evaluated by using cyclic voltammetry (CV) in 1 molL⁻¹ Na₂SO₄. The results show an improvement in the specific capacitance (C_s) of the oxide due to the presence of the polymer layer. Considering only the MnO₂ mass, the C_s values of the electrodes Ti/MnO₂, Ti/PEDOT₍₅₎/MnO₂ and Ti/PEDOT₍₂₅₎/MnO₂, estimated by the CV technique, are 151, 159 and 199 Fg⁻¹ at 10 mVs⁻¹ respectively. The micrographies of electrodes show that the polymer layer leads to very significant changes in the morphology of the oxide layers, which in turn generates the improvement observed in the capacitive property.