Effect of applied potential polarity on electrochemical properties of electrophoretically deposited activated carbon on an indium tin oxide substrate

Abstract

Herein, an activated carbon (AC) film was deposited on a transparent indium tin oxide (ITO) substrate via electrophoresis, assembling electrodes for electrochemical capacitors. The colloidal solution for deposition comprised AC, conducting carbon black (CB), and an ethyl cellulose binder. The polarity of the practical applied voltage was investigated to determine the optimum electrochemical performance because the different zeta potentials of the individual elements influence the type and quantity of the deposit. Potentials with different polarities but same magnitude (+100 V, −100 V) were applied and the results were compared with those of dip coating. The composition of an electrode formed at different conditions was evaluated based on the particle size and pore size distribution of AC and CB. Owing to the high negative zeta potential, CB with 1555 m2 g−1 was rapidly deposited in large quantities (0.9 mg cm−2) under an applied potential of +100 V. Dip coating primarily resulted in the precipitation of CB owing to its high dispersion due to the negative zeta potential. Both AC and CB were deposited at an appropriate ratio at the negative applying potential of −100 V, although both carbons have the negative zeta potential. However, the overall amount (0.3 mg cm−2) of deposit was reduced. The highest specific capacitance was achieved at −100 V based on the large specific surface area (1945 m2 g−1) of AC. Furthermore, adhesion to the ITO substrate was stronger at −100 V than at other conditions.