Eletrodeposição de Hidróxido de Cobalto para aplicação em Supercapacitores

Electrochemical supercapacitors have high power performance, long working lifetime and environment-friendly characteristics. The cobalt hydroxide (Co(OH)2) is a promising material for supercapacitors because of its low cost and well defined electrochemical behaviors (high power density, excellent cyclability and high specific energy). Cobalt hydroxide was electrodeposited onto titanium and stainless steel cloth as substrates using potenciostatic method in three electrode system. The electrolyte consists of a mixture of 0,05M CoCl2.6H2O and 0,05M Co(NO3)2.6H2O. The electrodeposition was carried out under potencial of -1 V for 10 min. Figure 1a shows cyclic voltammetry curves for the films obtained at different substrates at a scan rate of 10 mV s-1. The area surrounded within the CV curve for the films deposited in stainless steel cloth is obviously larger than the area of the films obtained to titanium plate, indicating that more active materials were involved and then better results of capacitance were obtained on steel. Capacitance values were calculated using charge- discharge curves for current density of 1mA for the films deposited on steel, represented on Figure 1b. The Nyquist plots consisted in a typical behavior of supercapacitors, with the formation of a small semicircle in the high-frequency region, related to the resistive processes corresponding to charge transfer. These results indicate that Co(OH)2 films deposited in stainless steel cloth have superior capacitive behaviors and has huge potential of application in supercapacitors.