Center for Energy and Advanced Materials Science

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Browsing Center for Energy and Advanced Materials Science by Author "Bakenov, Zhumabay"

Now showing 1 - 9 of 9
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    A simple approach to synthesize novel sulfur/graphene oxide/multiwalled carbon nanotube composite cathode for high performance lithium/sulfur batteries
    (Ionics. Springer-Verlag Berlin Heidelberg 2016, 2016-04-30) Yuan, Guanghui; Zhao, Yan; Jin, Huafeng; Bakenov, Zhumabay
    A sulfur/graphene oxide/multiwalled carbon nanotube (S/GO/MWNT) composite was synthesized via a simple ultrasonic mixing method followed by heat treatment. By taking advantage of this solution-based self-assembly synthesis route, poisonous and noxious reagents and complicated fabrication processes are rendered unnecessary, thereby simplifying its manufacturing and decreasing the cost of the final product. Transmission and scanning electronic microscopy observations indicated the formation of the threedimensional interconnected S/GO/MWNTcomposite through the environmentally friendly process...
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    Corn stalk-derived activated carbon with a stacking sheet-like structure as sulfur cathode supporter for lithium/sulfur batteries
    (Ionics. DOI 10.1007/s11581-015-1528-6, 2015-09-02) Yuan, Guanghui; Yin, Fuxing; Zhao, Yan; Bakenov, Zhumabay; Wang, Gongkai; Zhang, Yongguang
    A novel stacking sheet-like carbon (SSC) has been synthesized by carbonizing the corn stalks and composited with sulfur to prepare a cathode for lithium/sulfur batteries. Scanning electronic microscopy observations showed the formation of irregularly interlaced nanosheet-like structure consisting SSC with uniform sulfur coating on its surface. The SSC nanoflakes in the composite act as nanocurrent collectors, favoring the charge carrier ion transport and electrolyte diffusion. The interlaced SSC nanoflakes irregularly stack together and form a three-dimensional network, which is beneficial for both trapping soluble polysulfide intermediates and rendering the electrical conductivity of the composite electrode...
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    Exploring 3D microstructural evolution in Li-Sulfur battery electrodes using in-situ X-ray tomography
    (www.nature.com/scientificreports, 2016-09-17) Yermukhambetova, Assiya; Tan, Chun; Daemi, Sohrab R.; Bakenov, Zhumabay; Darr, Jawwad A.; Brett, Daniel J. L.; Shearing, Paul R.
    Lithium sulfur (Li-S) batteries offer higher theoretical specific capacity, lower cost and enhanced safety compared to current Li-ion battery technology. However, the multiple reactions and phase changes in the sulfur conversion cathode result in highly complex phenomena that significantly impact cycling life. For the first time to the authors’ knowledge, a multi-scale 3D in-situ tomography approach is used to characterize morphological parameters and track microstructural evolution of the sulfur cathode across multiple charge cycles. Here we show the uneven distribution of the sulfur phase fraction within the electrode thickness as a function of charge cycles, suggesting significant mass transport limitations within thick-film sulfur cathodes. Furthermore, we report a shift towards larger particle sizes and a decrease in volume specific surface area with cycling, suggesting sulfur agglomeration. Finally, we demonstrate the nano-scopic length-scale required for the features of the carbon binder domain to become discernible, confirming the need for future work on in-situ nano-tomography. We anticipate that X-ray tomography will be a powerful tool for optimization of electrode structures for Li-S batteries.
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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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    Simple One-Pot Synthesis of Hexagonal ZnO Nanoplates as Anode Material for Lithium-Ion Batteries
    (Copyright © 2016 Haipeng Li et al., 2015-12-15) Li, Haipeng; Wei, Yaqiong; Zhao, Yan; Zhang, Yongguang; Yin, Fuxing; Zhang, Chengwei; Bakenov, Zhumabay
    Hexagonal ZnO nanoplates were synthesized via simple one-pot hydrothermal reaction of Zn(CH3COO)2 and CO(NH2)2. XRD, SEM, and HRTEM were used to investigate the composition and microstructure of the material. Together with the facile strain relaxation during structure and volume change upon cycling, this plate-like structure of ZnO is favorable for physical and chemical interactions with lithium ions because of its large contact area with the electrolyte, providing more active sites and short diffusion distances.The resulting hexagonal ZnO nanoplates electrode exhibited good cyclability and delivered a reversible discharge capacity of 368mAh g−1 after 100 cycles at 0.1 C.
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    Synthesis of hierarchical MoS2 microspheres composed of nanosheets assembled via facile hydrothermal method as anode material for lithium-ion batteries
    (Springer Science+Business Media Dordrecht 2016. J Nanopart Res (2016) 18:63, 2016-02-24) Zhang, Yongguang; Li, Yue; Li, Haipeng; Yin, Fuxing; Zhao, Yan; Bakenov, Zhumabay
    A hierarchical MoS2 architecture composed of nanosheet-assembled microspheres with an expanded interplanar spacing of the (002) planes was successfully prepared via a simple hydrothermal reaction. Electron microscopy studies revealed formation of the MoS2 microspheres with an average diameter of 230 nm. It was shown that the hierarchical structure of MoS2 microspheres possesses both the merits of nanometer-sized building blocks and micrometer-sized assemblies, which offer high surface area for fast kinetics and buffers the volume expansion during lithium insertion/deinsertion, respectively. The micrometer-sized assemblies were found to contribute to the enhanced electrochemical stabilities of the electrode materials....
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    Synthesis of Multiwalled Carbon Nanotube Aqueous Suspension with Surfactant Sodium Dodecylbenzene Sulfonate for Lithium/Sulfur Rechargeable Batteries
    (Electrochemistry. The Electrochemical Society of Japan, 2015-12-27) Zhao, Yan; Liu, Xinyi; Zhang, Yongguang; Bakenov, Zhumabay; Yin, Fuxing
    Due to the hydrophobic nature of multiwalled carbon nanotube (MWNT), sodium dodecylbenzene sulfonate (SDBS) was adopted as a surfactant to synthesize a well-dispersed, homogeneous MWNT aqueous suspension. By simple stirring mixing of the resultant MWNT suspension with nano-sulfur aqueous suspension, a novel porous sulfur/ multiwalled carbon nanotube composite (S/MWNT) was synthesized. This preparation method based on the suspension mixing possesses the advantages of simplicity and low cost. Homogeneous dispersion and integration of MWNT in the composite results in a porous, highly conductive and mechanically flexible framework with enhanced electronic conductivity and ability to absorb the polysulfides into its porous structure. The cell with this S/MWNT composite cathode demonstrates a high reversibility, resulting in a stable reversible specific discharge capacity of 708mAhg−1 after 100 cycles at 0.1 C. Furthermore, the S/MWNT composite cathode with sulfur content of 62.5wt% exhibits a good rate capability with discharge capacities of 946, 780 and 516mAhg−1 at 0.5, 1 and 1.5 C, respectively.
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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.
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    ZnO Nanorods Grown Directly on Copper Foil Substrate as a Binder-Free Anode for High Performance Lithium-Ion Batteries
    (International Journal of ELECTROCHEMICAL SCIENCE. www.electrochemsci.org, 2016-09-06) Huang, Lanyan; Wang, Xin; Yin, Fuxing; Zhang, Yongguang; Gao, Jinwei; Liu, Junming; Zhou, Guofu; Bakenov, Zhumabay
    ZnO nanorods directly grown on copper foil substrate were obtained via hydrothermal method without using templates. Structure and morphology of the as-prepared ZnO nanorods were characterized by X-ray diffraction, scanning electron microscopy and high-resolution transmission electron microscopy. The ZnO nanorods on copper foil (ZnO@CF) exhibited remarkably enhanced performance as anode for lithium batteries with the initial discharge capacity of 1236 mAh g-1 and a capacity of 402 mAh g-1 retained over 100 cycles at a current density of 200 mA g-1. The ZnO@CF anode demonstrated an excellent rate capability, delivering a reversible capacity of 390 mAh g-1 at 1500 mA g-1. This superior performance of the ZnO@CF anode is believed to be due to the unique structure of this binder-free anode, favoring mass and charge transfer at its interface with the electrolyte, effectively reducing the Li-ions diffusion paths and providing conditions to accommodate the anode volume variations upon charge-discharge cycling.