Center for Energy and Advanced Materials Science

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Browsing Center for Energy and Advanced Materials Science by Author "Adair, Desmond"

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    Fabrication and Properties of Carbon- Encapsulated Cobalt Nanoparticles over NaCl by CVD
    (Nanoscale Research Letters, 2016-09-27) Li, Haipeng; Li, Yue; Zhang, Yongguang; Liang, Chunyong; Wang, Hongshui; Li, Baoe; Adair, Desmond; Bakenov, Zhumabay
    Carbon-encapsulated cobalt (Co@C) nanoparticles, with a tunable structure, were synthesized by chemical vapor deposition using Co nanoparticles as the catalyst and supported on a water-soluble substrate (sodium chloride), which was easily removed by washing and centrifugation. The influences of growth temperature and time on the structure and magnetic properties of the Co@C nanoparticles were systematically investigated. For different growth temperatures, the magnetic Co nanoparticles were encapsulated by different types of carbon layers, including amorphous carbon layers, graphitic layers, and carbon nanofibers. This inferred a close relationship between the structure of the carbon-encapsulated metal nanoparticles and the growth temperature. At a fixed growth temperature of 400 °C, prolonged growth time caused an increase in thickness of the carbon layers. The magnetic characterization indicated that the magnetic properties of the obtained Co@C nanoparticles depend not only on the graphitization but also on the thickness of the encapsulated carbon layer, which were easily controlled by the growth temperatures and times. Optimization of the synthesis process allowed achieving relatively high coercivity of the synthesized Co@C nanoparticles and enhancement of its ferromagnetic properties, which make this system promising as a magnetic material, particularly for high-density magnetic recording applications.
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    Thermal Management of Lithium/Sulphur Cells Using a Simple 2D Model
    (Modern Environmental Science and Engineering (ISSN 2333-2581). Academic Star Publishing Company, 2016., 2016-04) Ismailov, Kairat; Massalin, Yerzhan; Bakenov, Zhumabay; Adair, Desmond
    Lithium sulphur (Li/S) batteries are currently receiving significant attention as an alternative power source for zero-emission vehicles and advanced electronic devices due to the very high theoretical specific capacity of the sulphur cathode. Here a simple 2D transient method for the simulation of thermal characteristics of a lithium/sulfur cell is developed. The method is capable of determining the transient response of the thermal field. The heat sources associated with charging and discharging are estimated from experimental data and used as boundary conditions, and the simulations are performed at different charge and discharge current rates. The simulations were carried out for natural cooling.