| Summary: | 碩士 === 國立臺灣科技大學 === 材料科學與工程系 === 102 === In order to match the increasing energy and to avoid resource depletion and environmental pollution, there is a demand for the development of high-performance, low cost and environmental-friendly energy storage devices. Suitable materials become the essential ingredients. So the development and utilization of biomass waste materials could boost the exploring of novel materials for sustainable energy, enhance price competitiveness in energy supply markets, relieve environmental pollution and match the urgent requirement for green and sustainable development strategies.
Coffee, a readily available biological material in kitchen and Starbucks, has become more and more popular to public in the past few years. In this paper, porous carbon were synthesized from coffee ground through a green and low-cost chemical activation method and used for high-performance supercapacitor materials. We also have developed an electrode composed of well-aligned cobalt oxide nanowire arrays which are grown on nickel foam surfaces fabricated by a facile hydrothermal approach and further investigated as the electrode for high-performance supercapacitors.
The morphology and chemical composition of the electrode materials were characterized by X-ray Diffraction (XRD), Raman spectroscopy, Surface Area and Porosimetry Analyzer (BET), Scanning Electron Microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Transmission electron microscope (TEM). The electrochemical properties are analyzed by using cyclic voltammetry, constant current charge-discharge measurement and Electrochemical Impedance Spectroscopy (EIS).
The pseudo supercapacitor device with a potential range from 0-1.8 V is consisted of the positive electrode (cobalt oxide) and coffee ground as the negative electrode has demonstrated high energy density (90.9 Wh/kg at 1623.7 W/kg), high power density (16200 W/kg at 63 Wh/kg) and an excellent long-term stability. Two pseudo supercapacitors connected in series can efficiently power a blue LED indicator and drive a mini motor.
This paper illustrated that the utilization of inexpensive precursors and universal resource taken from nature is an ideal way for the preparation of high performance supercapacitor electrode materials.
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