| Summary: | 碩士 === 國立臺北科技大學 === 化學工程與生物科技系化學工程碩士班 === 107 === Owing to the ever-changing technology and the development of mobile devices, smart wearable devices and transportation, the requirements for energy storage devices are becoming more and more strict. Researchers are looking for an energy storage device with high safety, large capacity, fast charging and excellent cycle life. Supercapacitors seem to be the best candidate for the energy storage devices in the next generation. Supercapacitors have the advantages of safety, small size, light weight, high energy density, high power density, wide operating temperature range and excellent cycle life. Nevertheless, the conventional supercapacitors have not been able to satisfy the interests of scientists. Many research group have developed flexible, stretchable or even transparent functions to supercapacitors in recent years. But there are few research on transparent flexible supercapacitors in that it is difficult to balance the nature of these functions.
In this study, using the Poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) as active material of the supercapacitor electrode and the PVA/H3PO4 system as a gel electrolyte. In this article will be divided into two parts：
The first part (Chapter 3) will perform physical and electrochemical analysis on the electrode of a transparent stretchable supercapacitor. The conductive solution is doped with a small amount of ethylene glycol and surfactant, which can change the configuration and greatly reduce the sheet resistance of the thin film to 155.9 Ω/sq. In addition, by pre-coating AgNWs layer, the sheet resistance of the electrode can be further reduced to 19.9 Ω/sq. At a wavelength of 550 nm, the transmittance of the composite electrode is about 87.02%. After cyclic voltammetry, it has a capacitance of 158 F/g at a scan rate of 10 mV/s. After 1000 cycles of charge and discharge, the electrode can still maintains 50% of its initial performance.
In the second part (Chapter 4), the electrode will be taking the stretching process to observe the change of the surface morphology. After the composite electrode is stretched by 100% and then released back to 0%, the rate of change of the resistance in the elastic region and in the inelastic region is about 4 times and 40 times, respectively. However, in the cyclic voltammetry test, the composite electrode can stretch to 40% tensile strain. In addition, the bending test is performed when assembled into the transparent flexible supercapacitor. When the radius of curvature is 1.25 cm, the capacitance of the supercapacitor is increased instead of decreasing. The capacitance retention is 111% of the initial value. Here, we report the fabrication of a transparent stretchable electrodes by using PEDOT:PSS/AgNWs to improve the application of supercapacitors, such as electronic skin or self-charging smart textile.
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