Characterization of carbon pastes as matrices in composite electrodes for use in electrochemical capacitors.

Carbon paste electrodes (CPEs) were prepared from carbon black powder with different binders (Silicon Oil or Nujol).Cyclic voltammetry, chronoamperometry and chronopotentiometry techniques and different electrolytes (1M HClO4 and 1MLiClO4) were used to characterize the capacitive response and evaluate the capacitance (F/cm2, F/g) of CPEs, with andwithout surface modification. The surface modification was carried out by applying a potential pulse (1.35 V vs. saturatedcalomel electrode, SCE) at a time of 300 s, where the growth of carbon-oxygen (C-O) species were induced on the surface ofthe electrode. The results show that modified electrodes enhanced the capacitance and the electrolytic system has animportant influence in the stability and reactivity of electrodes. The modified electrodes shows an importantpseudocapacitive behavior as result of a diffusion processes that involved an interfacial reaction between the C-O speciesformed during the electrochemical surface treatment and the protons present in the electrolyte.