Manganese oxide precipitated into activated carbon electrodes for electrochemical capacitors |
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Authors: | Chuen-Chang Lin Chia-Cheng Yen |
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Affiliation: | (1) Department of Chemical & Materials Engineering, National Yunlin University of Science and Technology, 123 University Road Sec. 3, Douliu, Yunlin, 64002, Taiwan, ROC |
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Abstract: | Manganese oxide was prepared at different pH and temperatures and then precipitated into activated carbon by the chemical impregnation method. Size distributions of manganese oxide sol were also measured by light scattering. The electrodes were annealed in nitrogen gas at different temperatures. In addition, electrochemical characterization was carried out using cyclic voltammetry (CV) at a scan rate of 25 mV s−1 and chronopotentiometry (CP) with constant-current (10 mA cm−2). Maximum capacitance of 461.3 F g−1 was obtained in a 0.1 M Na2SO4 solution for manganese oxide prepared under optimum conditions (pH = 13.11 and T = 25 oC) and annealed at a temperature of 195 oC. The manganese oxide particle size decreased with annealing. This probably leads to increased specific capacitance. Using X-ray photoelectron spectroscopy (XPS) the results reveal that manganese oxide species are transformed from hydroxide to oxide after annealing. |
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Keywords: | Manganese oxide Chemical impregnation Annealing Scanning electron microscope Electrochemical capacitors |
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