Power Electronics
Ashkan Nahvibayani; Shaghayegh Baktashian; Mohsen Babaiee; Rahim Eqra
Abstract
One of the reasons for the increasing popularity of lithium- ion batteries is the improvement of their rate capability and power density. All components of a battery, including the anode, cathode, electrolyte, and separator, can limit the capability of lithium-ion batteries. While most efforts have focused ...
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One of the reasons for the increasing popularity of lithium- ion batteries is the improvement of their rate capability and power density. All components of a battery, including the anode, cathode, electrolyte, and separator, can limit the capability of lithium-ion batteries. While most efforts have focused on the new electrode architecture and electrolyte formulation to improve battery performance, studies on separators have focused mainly on their mechanical and physical properties and little attention has been paid to their effect on the performance of lithium-ion batteries. In this study, a comprehensive study of the physical, thermal and electrochemical properties of disassembled high drain lithium- ion battery separator (HDLIB) with high discharge rate capability and commercial polyethylene separator with a thickness of 16µm (G16) is reported. According to the research, it has been shown that HDLIB separator has 26% less contact angle and better wettability than commercial polyethylene separator. Also, HDLIB separator at 150°C has shrunk by 55.6% less than G16, which may be due to the presence of boehmite ceramic particles in its structure. In addition, it shows that HDLIB separator can play an important role in improving the rate performance and safety of lithium- ion batteries
Electric power
Mohammad Zarei-Jelyani; Mohammad Mohsen Loghavi; Mohsen Babaiee; Rahim Eqra; Masood Masoumi
Abstract
In recent years, extensive research has been focused on the key materials of vanadium redox flow batteries (VRFBs) to improve the power and energy density. In a VRFB system, the ion-exchange membrane is an important component, because it is used to separate the positive and negative electrolytes and ...
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In recent years, extensive research has been focused on the key materials of vanadium redox flow batteries (VRFBs) to improve the power and energy density. In a VRFB system, the ion-exchange membrane is an important component, because it is used to separate the positive and negative electrolytes and to allow the transfer of ions. Nafion membrane is now widely used in VRFBs due to its high proton conductivity and remarkable chemical stability. In the present study, the Nafion 117 membrane was subjected to acid-heat pretreatment for utilizing in VRFBs. Three-cell stacks of VRFB were assembled using bare and pretreated membranes, and their performances were evaluated during charge/discharge cycles. The results indicate that acid and heat pretreatment on the Nafion 117 membrane improves the VRFB energy density up to 30%. In addition, the average discharge voltage, which is one of the key parameters in the VRFB performance, is increased from 3.57 V (for the bare membrane) to 3.9 V (for the pretreated membrane). This helps to reduce the weight of the VRFB stack as well as the cost of the battery manufacturing. On the other hand, the acid and heat pretreatment of the membrane improves the energy and voltage efficiencies of VRFB from 66.9% and 76.8% to 73% and 87%, respectively
Power Electronics
Mahmoud Hasanloo; Mahdi Kargahi; Shahrokh Jalilian
Abstract
In this paper, we investigate the effect of task scheduling on the lifetime of a real- time hard drive system that uses a composite energy tank consisting of a battery, a super capacitor, and a solar energy picker to power supply itself. The lifetime of a system in this document is the moment the system ...
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In this paper, we investigate the effect of task scheduling on the lifetime of a real- time hard drive system that uses a composite energy tank consisting of a battery, a super capacitor, and a solar energy picker to power supply itself. The lifetime of a system in this document is the moment the system starts until the moment its tasks are disrupted due to lack of energy. Due to the nonlinear properties of batteries and super capacitors which cause their internal charge to be divided into available (IAC) and inaccessible (IUC); the lifetime of such a system depends entirely on the charging and discharging pattern of the energy tank. Ultimately, its leads to the amount of charge stored in the IUC section and the amount of charge extracted from this section. Therefore, we can influence the lifetime of the system and increase it by managing the charge/ discharge pattern of energy tanks. Since the pattern of energy delivery from the environment is beyond the control of the system, the main idea of this paper is to influence the charge/ discharge pattern of the tank by adjusting the pattern of energy consumption to improve the lifetime of the system. In this regard, we have presented two scheduling algorithms MCF and MGF, which are respectively trying to perform the most consumed and least consumed task in the system, then using the MCG policy, which at any time, Decisions are made on the use of one of these algorithms according to the conditions. Experimental results show that we can increase system lifetime between 5% and 16%. Considering that in recent years the issue of using super capacitors along with batteries and solar cells in space systems has been raised, so the results of this research can be investigated for use in satellites.
