Effect of Surface Treatment of Graphite Particles on the Composite Supercapacitor of Hydrous Ruthenium Oxides Coatings by Cathodic Deposition Method

Y Lin, H-S Hwang, W-J Lee
2006 Microscopy and Microanalysis  
Supercapacitors have many advantages using in electrical devices for their larger capacitance、high power density and long cycle life. In general, supercapacitors can be classified into two categories, namely, pseudo-capacitors and double-layer capacitors. The fomer stores electrical charges in electrode surface region by faradaic reaction. While, in the latter, electrical charges are stored ate the double-layer formed at electrode/electrolyte interface. Various methods have been utilized to
more » ... facture electrode including cyclic voltammetric method、sol-gel method、anodizing、cathodic deposition method and etc. [1]. In this study, hydrous ruthenium oxide with adding graphite particles was deposited on Ti substrate by cathodic deposition method. The purpose of adding graphite particles is to increase the specific surface area of hydrous ruthenium oxide coating. The concentration of graphite particles added in the deposition process varies from 0.1wt% to 2wt%. The effect of surface treatment of graphite particles before deposition was investigated in this study. The graphite particles was treated in 120 ℃-6M HNO 3 solution for one hour to active the graphite surface. The specimen was then immersed into the coating bath for 60 minutes. The electrical capacity characteristics of coating were examined by cyclic voltammetry. The microstructure of hydrous ruthenium oxide coating was also observed by scanning electron microscopy. Figure 1(a) and (b) show the microstructures of hydrous ruthenium oxide coating after the surface treatment of graphite particles. The electrical capacitance of specimen with 0.3wt% of graphite particles after surface treatment was measured about 408F/g. Figure 2 reveals the difference of electrical capacity characteristics of specimens with different concentration of graphite added in deposition processes. Figure 3 reveals the distribution of the capacitance as increasing the concentration of graphite. It can be observed that the capacitance can be increased very effectively when small amount of graphite added in the deposition bath. The reason could be that the graphite after surface treatment will increase the effective area during deposition which leads to the increasing of the amount of hydrous ruthenium oxide. However, it was also found that the
doi:10.1017/s1431927606062234 fatcat:63ave6webnc6dait2jv22jlsai