Single-walled carbon nanotube film for electrochemical energy storage devices
| Author(s) | Rong, Jiepeng | |
| Date Accessioned | 2011-05-24T13:52:24Z | |
| Date Available | 2011-05-24T13:52:24Z | |
| Publication Date | 2010 | |
| Abstract | Development of materials and structures leading to high energy and power density electrochemical energy storage systems is a major requirement to the power needs of portable electronics and electric vehicles. Lithium-ion batteries and electrical double-layer capacitors are among the leading electrical energy storage technologies today. Carbon nanotubes (CNTs), since the discovery in 1991, have exhibited promising applications in electrochemical energy storage by taking advantage of their unique mechanical, chemical, and electrical properties. Two concrete examples of CNT macro-film ‘s applications in lithium-ion batteries and electrical double-layer capacitors are demonstrated in this thesis. Lithium-ion batteries with substantially higher specific capacity and better cycling performance are needed in next generation portable electronics, especially if all-electric vehicles are to be deployed broadly as replacements for gasoline-powered vehicles. Silicon (Si) is an attractive anode material being closely scrutinized for use in lithium-ion batteries but suffers from a poor cyclability and early capacity fading. A simple method to fabricate tandem structure of porous Si film on CNT film to significantly improve cycling stability of Si film as lithium-ion battery anode materials was reported in this thesis. With the new structure, both reversible specific capacity and cycling stability of the battery cells are improved. Reversible specific capacity of Si film retains 2221 mAh g¹ after 40 charge-discharge cycles at 0.1C rate, more than 3 times of Si film on regular copper current collector. The enhanced reversible specific capacity was attributed to the unique morphology of CNT film, where the functional mechanism of CNT film was investigated and modeled. The facile method is efficient and effective in improving specific capacity and stability of Si anode lithium-ion batteries, and will provide a powerful means for the development of lithium-ion batteries. Supercapacitors, as the complementary energy-storage devices of battery, have been intensively studied due to their longer cycle life and higher specific power density in comparison with batteries. A recent direction in electronic field seeking to develop high-performance circuits to be formed on flexible substrates, namely flexible and stretchable electronics has also attracted considerable attention from scientific and technological communities because of its promising wide applications where flexibility, space savings, or production constraints limit the serviceability of rigid circuit boards or hand wiring. To accommodate the needs of the emerging flexible and stretchable electronics, power source devices like capacitors, which are indispensable components in all electronics, must also be flexible and stretchable in addition to their high energy and power density, light weight, miniaturization in size, and safety requirements. In this thesis, we demonstrated stretchable supercapacitors using buckled single-walled carbon nanotube (SWNT) macro-films as the electrodes and polydimethylsiloxane (PDMS) as the elastomeric substrates. The stretchability depends on the level of pre-stain applied on the PDMS substrate, which could be as high as 30%. The electrochemical performance remains unchanged during mechanical stretch. This stretchable supercapacitor just enlightens a broad area of stretchable energy storage devices, which are naturally compatible with the developed stretchable electronics. | en_US |
| Advisor | Wei, Bingqing | |
| Degree | M.S.M.E. | |
| Department | University of Delaware, Department of Mechanical Engineering | |
| URL | http://udspace.udel.edu/handle/19716/5915 | |
| Publisher | University of Delaware | en_US |
| dc.subject.lcsh | Nanotubes | |
| dc.subject.lcsh | Energy storage | |
| dc.subject.lcsh | Lithium ion batteries | |
| dc.subject.lcsh | Carbon | |
| dc.subject.lcsh | Silicon | |
| dc.subject.lcsh | Thin films | |
| Title | Single-walled carbon nanotube film for electrochemical energy storage devices | en_US |
| Type | Thesis | en_US |