## 3 Results and Discussion  
Figure 2 shows that the carbon electrode prepared using the MCMB was in an amorphous state. According to the JCPDS cards, peaks at 37.2\({}^{\circ}\) and 43.2\({}^{\circ}\) of 20 correspond to the (111) and (200) diffractions of NiO (JCPDS files: 20-1324) deposited on the carbon electrode. However, there were not obvious diffraction peaks for WO\({}_{3}\) deposited on the carbon electrode; therefore, it was in an amorphous state. Because WO\({}_{3}\) films were deposited at R.T., the amount of energy was insufficient to induce crystalline growth. Figure 1: The preparation flow diagram of the composite electrode. Figure 3 shows the morphologies of a layer NiO deposited on the activated carbon surface. The WO\({}_{3}\) films deposited on the activated carbon are round rock structures as shown in Figure 4. Cracks are visible on the WO\({}_{3}\) films. The MCMB has a high specific surface area and porosity. The thickness of the metal oxide (WO\({}_{3}\) or NiO) films deposited on the MCMB surface is about 500 nm via electron beam evaporation. This caused cracks, but a high power density of the supercapacitor with composite structure electrodes was obtained. Electrochemical measurements were conducted in a 2-electrode disc-type cell (capacitor), in which a separator was soaked in 1 M Et\({}_{4}\)NBF\({}_{4}\) and inserted between the two carbon electrodes. A voltage ranges of \(-\)3.0 to 3.0 V was applied. Figure 3: SEM morphologies and EDS of the NiO thin films deposited on the carbon electrode: (**a**) the magnification of 1000\(\times\) (**b**) the magnification of 30,000\(\times\). Figure 2: X-ray patterns of the composite electrodes: (**a**) ITO/glass substrate; (**b**) MCMB/ITO/glass; (**c**) NiO/MCMB/ITO/glass; (**d**) WO\({}_{3}\)/MCMB/ITO/glass. While at lower scan rates all the active surface area can be utilized for charge storage [16]. Therefore, a smooth current peak was obtained. However, the current peak increased with the increasing scan rate. As the scan rate of the CVs gradually increased, the shape of the CVs changed from rectangular to ovular. In Figure 5, when the scan rate was 25-200 mV\(\cdot\)s\({}^{-1}\), carbon electrodes and composite electrodes exhibited a similar hysteresis area of CVs. However, when the scan rate exceeded 250 mV\(\cdot\)s\({}^{-1}\), the hysteresis area of the CVs of the composite electrodes was larger than that of the carbon electrodes. The composite electrode, on which NiO was deposited, exhibited a larger hysteresis area. Table 1 shows the specific capacitances that were calculated using Equation (1) at various scan rates of CVs. Specific capacitances decreased gradually when scan rates increased, as shown in Figure 6. When the voltage scan rate was slower, a chemical adsorption/desorption or redox reaction occurred on the surfaces of the electrodes, enabling electrolyte ions to migrate into the inner pores of the electrodes. The ions may not have had enough time to reach the surface of the capacitor electrode at a high scan rate. However, when the scan rate was slower, the redox reaction occurred on the surfaces of  
Figure 4: SEM morphologies and EDS of the WO\({}_{3}\) thin films deposited on the carbon electrode: (**a**) the magnification of 1000\(\times\) (**b**) the magnification of 30,000\(\times\). Figure 5: CVs of the carbon electrodes and the composite electrodes in 1M Et\({}_{4}\)NBF\({}_{4}\) solution at various scan rates: (**a**) 25 mV/s (**b**) 50 mV/s (**c**) 100 mV/s (**d**) 200 mV/s (**e**) 250 mV/s (**f**) 500 mV/s. the electrodes, enabling ions to migrate into the inner pores of the electrodes. Therefore, a low scan rate demonstrates a better specific capacitance for devices. As a result, when the electrode with a large specific surface area is adopted, the specific capacitance is increased [17; 18; 19]. When the scan rate was lower than 200 mV\(\cdot\)s\({}^{-1}\), the specific capacitance of the carbon electrodes was larger than the specific capacitance of the composite electrodes.