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Item Kinetic mechanism for water in vibrating carbon nanotubes(APS, 2018-09) Zhou, Xiaoyan; Zhu, Fangqiang; Physics, School of ScienceRecent simulations revealed that, when an atom in a single-wall carbon nanotube was artificially driven to oscillate radially with the two ends of the nanotube fixed, water transport became highly unusual at some oscillation frequencies. Here we systematically investigate the underlying mechanism for such effects through a series of simulations and detailed analysis. We find that the pattern and magnitude for the vibration of the nanotube are sensitive to the driving frequency but largely independent of the presence of water. At certain resonance frequencies, some carbon atoms of the nanotube oscillate at much larger amplitudes than does the driving atom. Furthermore, a strongly vibrating nanotube tends to have a much-reduced water occupancy, which is mainly due to the heating effect rather than the induced deformation. Indeed, the water molecules inside the nanotube can be significantly heated and gain large kinetic energies due to the collisions with the vibrating carbon atoms. Consequently, the kinetic rate of water exchange through the nanotube could be enhanced even when the water occupancy is low. Our findings here may help understanding the physical mechanisms of similar nanodevices.Item Paper-Based Lithium-Ion Battery(Office of the Vice Chancellor for Research, 2013-04-05) Aliahmad, Nojan; Agarwal, Mangilal; Shrestha, Sudhir; Varahramyan, KodyLithium-ion batteries have a wide range of applications including present day portable consumer electronics and large-scale energy storage. Realization of these batteries in flexible, light-weight forms will further expand the usage in current and future innovative electronic devices. Lithium titanium oxide (Li4Ti5O12), lithium magnesium oxide (LiMn2O4) and lithium cobalt oxide (LiCoO2) materials have been consistently studied for application in high capacity batteries, and thus considered in the devices that are presented in the poster. Carbon nanotube (CNT) coated wood microfiber papers are used as current collectors, which provide high surface area, flexibility, and texture of paper, with low CNT utilization (10.1μg/cm2). The CNT microfiber paper is fabricated by layer-by-layer (LbL) nano-assembly of CNT over cellulose microfibers. Results from paper-based half-cell batteries show capacities of 130 mAh/g for LiMn2O4, 150 mAh/g for LiCoO2, and 158 mAh/g for Li4Ti5O12 at C/5 rate. These results are comparable with metallic electrode based cells. The fabrication of CNT microfiber paper, assembly of batteries, experimental methods, and results are presented and discussed.Item V2O5/Graphene Hybrid Supported on Paper Current Collectors for Flexible Ultrahigh-Capacity Electrodes for Lithium-Ion Batteries(ACS, 2018-04) Aliahmad, Nojan; Liu, Yadong; Xie, Jian; Agarwal, Mangilal; Mechanical Engineering, School of Engineering and TechnologyAn ultrahigh-capacity, flexible electrode made with vanadium pentoxide/graphene (with a specific capacity of 396 mAh/g) supported on paper-based current collectors has been developed. The ultrahigh-capacity graphene-modified vanadium pentoxide is fabricated by incorporating graphene sheets (2 wt %) into the vanadium pentoxide nanorods to improve the specific capacity, cycle life, and rate capability. This active material is then incorporated with the paper-based current collectors [carbon nanotube (CNT)–microfiber paper] to provide flexible electrodes. The flexible current collector has been made by depositing single-wall CNTs over wood microfibers through a layer-by-layer self-assembly process. The CNT mass loading of the fabricated current collectors is limited to 10.1 μg/cm2. The developed electrodes can be used to construct the flexible battery cells, providing a high-capacity/energy and rechargeable energy storage unit for flexible electronic devices.