Characterization and Mechanism of Fe3O4/Carbon Supercapacitors
Date Issued
2004
Date
2004
Author(s)
Wang, Shi-Yu
DOI
zh-TW
Abstract
Composite electrodes which comprise a non-conductive activated carbon of large surface area (1436 m2/g) and a conductive carbon black (CB) of small surface area (220 m2/g) have been prepared and studied for their capacitive properties in aqueous KOH and Na2SO4 electrolytes. For either electrolyte, maximum capacitance exists at the composition believed to correspond to the percolation threshold for CB, the conductive phase. At a CB content less than the threshold, the capacitance is limited mainly by the electronic resistance on the electrode side. The interfacial surface area becomes the limiting factor as the threshold is exceeded. A maximum capacitance of 108 F/g at a voltage sweep rate of 20 mV/s is obtained in 1 M KOH aqueous electrolyte with a CB content of 25 wt.% (or ~ 14 vol.%).
Magnetite (Fe3O4) supercapacitor contained 10 wt.% CB as conductive additive (≧ percolation threshold), operating characteristics in aqueous electrolytes of Na2SO3, KOH and Na2SO4 were investigated. While the capacitance of the oxide was found to depend heavily on electrolyte composition, the self-discharge mechanism in these electrolytes appeared to be the same. Reduction in dissolved oxygen content (DOC) of electrolyte reduced leakage current and profoundly improved the cycling stability. In particular, Na2SO3(aq) gives the highest capacitance, nearly 30 F/g-Fe3O4 or 80
Subjects
氧化鐵
碳
電化學石英晶體微量天平
機制
Carbon
Mechanism
Fe3O4, EQCM
Supercapacitor
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-93-D88524006-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):2b6a6c40f901c35db97f7e9087c2ec40