Influence of surface oxides on the impedance behavior of carbon-based electrochemical capacitors

Yau Ren Nian, Hsisheng Teng

研究成果: Article同行評審

201 引文 斯高帕斯(Scopus)

摘要

Electrochemical capacitors made of activated carbon fabrics containing different compositions of surface oxides are analyzed using ac impedance spectroscopy. The oxides are introduced and controlled via HNO3 treatment followed by thermal treatment at different temperatures within 150-900°C. The impedance spectra showed that the overall resistance mainly came from the fiber contact resistance, which was an increasing function of oxide number, while the overall capacitance was contributed by the interface inside micropores. Oxidation enhanced the specific capacitance of the electrodes, but it was found that a thermal treatment temperature of 450°C gave the highest capacitance. Constant phase element (CPE) analysis of the capacitive behavior showed insignificant deviation from ideality, indicating the low resistance in the carbon micropores as well as the domination of the double layer mechanism in energy storage. Thus, the capacitance increase from oxidation resulted mainly from the double layer mechanism as well. The deviation from ideality was more obvious for lower temperature treated electrodes, indicating that the surface oxides that desorb as CO2 upon heat treatment may enhance formation of aggregates to retard the charge process, while the surface oxides that desorb as CO are responsible for the promotion of the double layer capacitance.

原文English
頁(從 - 到)119-127
頁數9
期刊Journal of Electroanalytical Chemistry
540
DOIs
出版狀態Published - 2003 一月 2

All Science Journal Classification (ASJC) codes

  • 分析化學
  • 化學工程 (全部)
  • 電化學

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