期刊
ELECTROCHIMICA ACTA
卷 83, 期 -, 页码 241-246出版社
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.electacta.2012.08.026
关键词
Methylene blue; Multiwalled carbon nanotubes; Faradaic reactions; Redox electrolyte; Supercapacitor
资金
- MICINN [MAT2010-20601-C02-01]
MWCNT-based supercapacitors (SC) containing methylene blue (MB) as redox active electrolyte were studied. MWCNTs were employed as model of electrode active material due to their ideal double-layer behavior facilitates the investigation of the energy storage mechanisms involved. MB led to a cell capacitance enhancement equal to 4.5 times the original cell capacitance of MWCNTs in sulphuric acid with a capacitance reduction of only 12% after 6000 charge-discharge cycles. The potential evolution of each electrode during galvanostatic cycling revealed that MB redox reaction develops in both electrodes simultaneously in the voltage range of 0-0.104 V and that this is the main cause of cell capacitance enhancement. Beyond this voltage range, the Faradaic contribution from the MB redox reaction decreases because the anode behaves as a capacitative electrode with a rather reduced charge-capacity due to the small surface area of MWCNTs. By means of a modified assembly composed of a Nafion membrane and MB and sulfuric acid solutions located in the cathode and anode compartments, respectively, it was demonstrated the limiting role of the capacitative electrode in the cell charge-capacity in this type of hybrid devices. (C) 2012 Elsevier Ltd. All rights reserved.
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