Advanced Energy Technologies
Shokoofeh Bagheri; Hassan Moradi CheshmehBeigi
Abstract
Today, the presence of energy storage systems along with the alternative nature of renewable energy sources has become undeniable and one of these types of systems is battery energy storage systems. The most important factor in studying the stability of DC microgrids (DCMGs) is the stabilization of the ...
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Today, the presence of energy storage systems along with the alternative nature of renewable energy sources has become undeniable and one of these types of systems is battery energy storage systems. The most important factor in studying the stability of DC microgrids (DCMGs) is the stabilization of the DC bus voltage when an error occurs on its reference value. Therefore, batteries along with power electronic converters play an important role in maintaining DCMG stability. In this paper, the use of Cascaded Buck-Boost Converter (CBBC) can be considered as a suitable alternative to bidirectional buck-boost converter due to such advantages as high power density, 98 % efficiency, and higher operating temperature in battery. The control strategy is applied in the microgrid implemented in the converter system set with storage, and Virtual DC Machine (VDCM) is based on charging and discharging battery through CBBC. In the studied control method, the theoretical properties of the DC machine, which is responsible for amplifying the virtual inertia in the system, are directed to the CBBC for correct switching. VDCM can be changed from motoring to generating mode or vice versa, regardless of mechanical machinery. Therefore, the proposed control system is simulated in an islanded DCMG in Matlab/Simulink and the stability of the studied system is analyzed according to the small-signal model of the proposed control and converter units. According to the simulation results and small-signal model analysis, the stability of the proposed idea under different scenarios is confirmed.
Advanced Energy Technologies
Mohsen Babaiee; Mohammad Zarei-Jelyani; Shaghayegh Baktashian; Rahim Eqra
Abstract
A mechanical technique was applied to the copper current collector of lithium-ion battery anode to improve interface adhesion between Cu foil and anode film. The mechanical and electrochemical performances of graphite anodes coated on Bare Cu Foil (BCF) and Modified Cu Foil (MCF) were evaluated. The ...
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A mechanical technique was applied to the copper current collector of lithium-ion battery anode to improve interface adhesion between Cu foil and anode film. The mechanical and electrochemical performances of graphite anodes coated on Bare Cu Foil (BCF) and Modified Cu Foil (MCF) were evaluated. The BCF and MCF anodes exhibited adhesion strengths of 1.552 and 1.617 MPa, respectively. The electrochemical studies of BCF and MCF anodes showed that the initial discharge capacity of graphite anode coated on the MCF (323.6 mAh g-1) was about 8 % higher than the BCF anode (299.9 mAh g-1). The BCF anode capacity reached 227.9 mAh g-1 after 100 charge/discharge cycles at 0.5C rate, while this value was 247.7 mAh g-1 for MCF anode. The results of electrochemical impedance spectra demonstrated that the diffusion coefficient of lithium-ion for MCF anode was about 56 % higher than that for BCF anode. On the other hand, the surface modification of the copper current collector reduced the charge transfer resistance of anode from 28.5 Ω to 23.2 Ω.
Advanced Energy Technologies
Ashkan Nahvi Bayani; Mohammad Hadi Moghim; Saeed Bahadorikhalili; Abdolmajid Ghasemi
Abstract
Despite the extensive use of polyolefins, especially in the form of lithium-ion battery (LIB) separators, their flammability limits their large-scale battery applications. Therefore, the fabrication of flame-retardant LIB separators has attracted much attention in recent years. In this work, composite ...
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Despite the extensive use of polyolefins, especially in the form of lithium-ion battery (LIB) separators, their flammability limits their large-scale battery applications. Therefore, the fabrication of flame-retardant LIB separators has attracted much attention in recent years. In this work, composite separators were fabricated by applying a ceramic-based composite coating composed of a metal hydroxide as a filler and flame-retardant agent (Aluminium hydroxide, Al(OH)3) and a binder (Poly(vinylidene Fluoride-co-hexafluoropropylene), P(VDF-HFP)) to the polypropylene (PP) commercial separator. Thermal shrinkage, thickness, air permeability, porosity, wettability, ionic conductivity, flame retardancy, and electrochemical performance of the fabricated ceramic-coated composite separator were investigated. The results showed that the addition of Al(OH)3 particles improved thermal shrinkage ( 8 %) and flame retardancy of the commercial separator, which can prevent dimensional changes at high temperatures and significantly increase LIBs safety. Applied 11 µm ceramic-based coating layer on PP commercial separator had 76 % porosity that increased the value of air permeability from 278.15 (s/100 cc air) to 312.8 (s/100 cc air), causing much facile air permeation through the pores of commercial separator than the composite one. Furthermore, suitable electrolyte uptake and the contact angle of ceramic coated separator (135 % and 91.19°, respectively) facilitated ion transport through the pores, which effectively improved the ionic conductivity of Al(OH)3-coated PP separator (about 1.4 times higher than bare separator). Moreover, the cell comprising Al(OH)3-coated PP separator had better cyclic performance than that of bare PP separator. All these characteristics make the fabricated flame-retardant Al(OH)3 composite separator an appropriate candidate to ensure the safety of the large-scale LIB.
Advanced Energy Technologies
Mohammad Zarei-Jelyani; Shaghayegh Baktashian; Mohsen Babaiee; Rahim Eqra
Abstract
In recent years, many studies have focused on the active materials of anodes to improve the performance of LIBs, while limited attention has been given to polymer binders, which act as inactive ingredients. However, polymer binders have amazing influence on the electrochemical performance of anodes. ...
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In recent years, many studies have focused on the active materials of anodes to improve the performance of LIBs, while limited attention has been given to polymer binders, which act as inactive ingredients. However, polymer binders have amazing influence on the electrochemical performance of anodes. Herein, to investigate the binding performance between MCMB artificial graphite and the copper current collector, three binders such as PVDF, MSBR, and CMC+SBR were used to prepare the anode electrodes. The mechanical and electrochemical tests were conducted for different MCMB electrodes. The results show that the water-based binders (CMC+SBR and MSBR) made better adhesion properties for the coating on the current collector in comparison with the organic solvent-based binder (PVDF). MCMB anode fabricated with CMC+SBR binder shows the highest discharge capacity and the best rate performance at various C-rates of 0.2C, 0.5C, and 1C that result in the brilliant electrochemical performance. Therefore, artificial graphite anode materials using cheap aqueous CMC+SBR binder instead of toxic solvent like NMP and expensive PVDF improve electrochemical property and reduce the cost of LIBs.