Preparation of Polyaniline Solution. To obtain polyaniline solution, prepare 0.12M aniline solution by adding 2 ml of aniline into 200 ml of 1 M sulfuric acid. Start with 98% purity sulfuric acid, 10.8784 ml of 98% sulfuric acid is added to 200 ml distilled water to obtain 1 M sulfuric acid. 0.12 M aniline solution can be created by adding 2 ml of aniline and 200 ml of 1 M sulfuric acid. Refrigerated the solution for a night to let the polyaniline solution form nanotube structure.
Preparation of Working Electrode. Carbon fiber is used as the conducted electrode for this experiment. Cut two long stripes of carbon fiber into 8 shorter stripes around the same length. The chart shows the length, width and area of each of the eight carbon fiber pieces.
To clean the carbon fiber pieces, soak the carbon fiber pieces into 1 M sulfuric acid for 10 minutes. This process can increase its hydrophilic property (oxidizing) and clean other chemicals on its surface. Then dip the carbon fiber pieces into ethanol for 5 minutes in order to clean them
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From these data, the specific capacitance is calculated using the equation C= 2i*t/SΔV where i is the applied current, t is the discharging time, S is the area of the tested electrode in supercapacitor, ΔV is the voltage window. The surface-specific capacitance of sample 4 at 0.5mA is 2.611 mF/〖cm〗^(-2). For the galvanostatic charge and discharge curves before and after 100 cycles, it can be concluded that the sample is charged and discharged faster after 100 cycles, which indicated that the capacitance is smaller after repeated charging and discharging for many times. The calculated surface-specific capacitance of sample 4 after 100 cycles at 0.5mA is 1.625 mF/〖cm〗^(-2). From visual observation, less polyaniline is attached to the carbon fiber after 100 cycles’