Research Institute of renewable energy, energy saving, efficiency and future energy
http://nur.nu.edu.kz:80/handle/123456789/1119
2024-03-28T14:51:05ZAtomic Force Microscopy Study of Cross-Sections of Perovskite Layers
http://nur.nu.edu.kz:80/handle/123456789/4418
Atomic Force Microscopy Study of Cross-Sections of Perovskite Layers
Migunov, D.; Eidelman, K.; Kozmin, A.; Saranin, D.; Ermanova, I.; Gudkov, D.; Alekseev, A.
Improvement of methods for imaging of the volume structure of photoactive layers is one of the important directions towards development of highly efficient solar cells. In particular, volume structure of photoactive layer has critical influence on perovskite solar cell performance and life time. In this study, a perovskite photoactive layer cross-section was prepared by using Focused Ion Beam (FIB) and imaged by Atomic Force Microscopy (AFM) methods. The proposed approach allows using advances of AFM for imaging structure of perovskites in volume. Two different types of perovskite layers was investigated: FAPbBr(3) and MAPbBr(3). The heterogeneous structure inside film, which consist of large crystals penetrating the film as well as small particles with sizes of several tens nanometers, is typical for FAPbBr(3). The ordered nanocrystalline structure with nanocrystals oriented at 45 degree to film surface is observed in MAPbBr(3). An optimized sample preparation route, which includes FIB surface polishing by low energy Ga ions at the angles around 10 degree to surface plane, is described and optimal parameters of surface treatment are discussed. Use of AFM phase contrast method provides high contrast imaging of perovskite structure due to strong dependence of phase shift of oscillating probe on materials properties. The described method of imaging can be used for controllable tuning of perovskite structure by changes of the sample preparation routes....
2019-01-01T00:00:00ZTechno-economic modellingto strategize energyexportsinthe Central AsianCaspian region
http://nur.nu.edu.kz:80/handle/123456789/2828
Techno-economic modellingto strategize energyexportsinthe Central AsianCaspian region
Bakdolotov, Aidyn; De Miglio, Rocco; Akhmetbekov, Yerbol; Baigarin, Kanat
This paper studies the concept of energy security from export-oriented countries’ point ofview. It aims to test the effects of long-term energy export strategies in the Central Asian Caspian(CAC) region,by exploring the trade-offs between a “risk” indicator and some key variables of the energy system such as the total cost,the quantities exported, and the corresponding revenues.Risk reduction goals are combined with securing a minimum level of revenues from the hydrocarbon exports goals. It is also attempted to provide a definition and aquantification of a risk indicator on the basis of four components. The analysis makes use of a techno-economic energy system model to quantitatively
evaluate the response of the energy sector to energy security risks,and it ssensitivity to different export strategies.
2017-03-27T00:00:00ZThermal Management of Lithium/Sulphur Cells Using a Simple 2D Model
http://nur.nu.edu.kz:80/handle/123456789/1850
Thermal Management of Lithium/Sulphur Cells Using a Simple 2D Model
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.
2016-04-01T00:00:00ZA simple approach to synthesize novel sulfur/graphene oxide/multiwalled carbon nanotube composite cathode for high performance lithium/sulfur batteries
http://nur.nu.edu.kz:80/handle/123456789/1849
A simple approach to synthesize novel sulfur/graphene oxide/multiwalled carbon nanotube composite cathode for high performance lithium/sulfur batteries
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...
2016-04-30T00:00:00ZExploring 3D microstructural evolution in Li-Sulfur battery electrodes using in-situ X-ray tomography
http://nur.nu.edu.kz:80/handle/123456789/1848
Exploring 3D microstructural evolution in Li-Sulfur battery electrodes using in-situ X-ray tomography
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.
2016-09-17T00:00:00ZFabrication and Properties of Carbon- Encapsulated Cobalt Nanoparticles over NaCl by CVD
http://nur.nu.edu.kz:80/handle/123456789/1847
Fabrication and Properties of Carbon- Encapsulated Cobalt Nanoparticles over NaCl by CVD
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.
2016-09-27T00:00:00Z