期刊
JOURNAL OF SOLID STATE ELECTROCHEMISTRY
卷 16, 期 5, 页码 1781-1789出版社
SPRINGER
DOI: 10.1007/s10008-011-1619-x
关键词
Polypyrrole; Carbon nanotubes; Supercapacitors; Capacitance; Functionalization
资金
- National High Technology Research and Development Program of China [2007AA03Z249]
- National Natural Science Foundation of China [20804030]
The composite film of polypyrrole and functionalized multi-walled carbon nanotubes (PPy/F-MWNTs) was prepared by electropolymerization. MWNTs were functionalized by sonicating with a concentrated solution of H2SO4/HNO3 (3/1, volume ratio) in a water bath for different times. The carbon nanotubes (CNTs) are cut into smaller portions with more functional groups introduced on their surface when the sonicating time (nominated as functionalization time hereafter) is increased. However, the specific capacitance of the composite film reaches a maximum of 240 F g(-1) at the scanning rate of 10 mV s(-1) when MWNTs are functionalized for 24 h, which is about 205 F g(-1), 225 F g(-1) and 232 F g(-1), respectively, when MWNTs are functionalized for 6 h, 12 h and 48 h. At a current load of 1.0 A g(-1), PPy/F-MWNT composite film functionalized for 24 h (PPy/F-MWNTs (24 h)) retains 93.49% of its initial capacitance after 1,000 cycles of galvanostatic charge/discharge, and the discharge efficiency is higher than 98.15% during cycling. High specific capacitance, good rate performance, fast charge/discharge ability and long cycling life are ascribed to the synergistic effect of the two components to form a porous composite film as well as the easy accessibility of counter ions into the film. Therefore, PPy/F-MWNT (24 h) composite film is a kind of promising electrode material for supercapacitors. The mechanism of underfunctionalization and overfunctionalization of carbon nanotubes is also discussed.
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