Mr Yasin Salami Ranjbaran, Dr Mohammad Hassan Shoajeefard, Dr Gholam Reza Molaeimanesh,
Volume 8, Issue 2 (6-2018)
Abstract
This paper mainly discusses the thermal behavior and performance of Lithium-ion batteries utilized in hybrid electric vehicles (HEVs), battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) based on numerical simulations. In this work, the battery’s thermal behavior is investigated at different C-rates and also contour plots of phase potential for both tabs and volume-monitored plot of maximum temperature inside the computational domain is illustrated. The numerical simulation is done via ANSYS Fluent traditional software package which utilizes the dual potential multi-scale multi-dimensional (MSMD) battery model to analyze the cell discharge behavior and investigate the thermal performance and potential variation(s). The results show that the maximum temperature of battery surface is proportional to the battery discharge rate, i.e., the higher the C-rate, the greater cell surface temperature. Moreover, an increasing symmetric pattern is noticed for volume monitor of maximum temperature over the simulation period. Finally, it is worth noting that the battery tab potential varies more quickly if the C-rate becomes greater. In fact, the lowest and highest rate of changes are observed for 1C and 4C, respectively.
Mahdi Khoorishandiz, Abdollah Amirkhani,
Volume 13, Issue 1 (3-2023)
Abstract
As electric vehicles become more popular, we need to keep improving the lithium-ion batteries that power them. Electrochemical impedance spectroscopy (EIS) is used based on a discrete random binary sequence (DRBS) to reduce excitation time in the low-frequency region and excite the input of the battery. In this paper, voltage and current signals are processed with wavelet transform for impedance evaluation. In using wavelet transform, choosing the most optimal mother wavelet is crucial for impedance evaluation since different mother wavelets can produce different results. We aim to compare three types of continuous Morse mother wavelet, continuous Morlet, and continuous lognormal wavelet, which are among the most important mother wavelets, to determine the best method for impedance evaluation. We used the dynamic time-warping algorithm to quantify the difference between the initial values obtained from standard laboratory equipment and the impedance evaluation through three different continuous wavelets. Our proposed method (lognormal wavelet) has the lowest difference (3.4086) from the initial values compared to the Morlet (3.5504), and Morse (3.5457) methods. As a result, our simulation shows that the lognormal wavelet transform is the best method for impedance evaluation compared to Morlet and Morse wavelets.
Mr. Mohammad Zarei-Jelyani, Mr. Amirhossein Salehi, Dr. Mohsen Babaiee, Dr. Mohammad Mohsen Loghavi,
Volume 14, Issue 2 (6-2024)
Abstract
The global transition towards renewable energy necessitates efficient energy storage solutions to address the intermittency of renewable sources. Lithium-ion batteries (LIBs), widely utilized in electric vehicles (EVs) for their high energy density and efficiency, yet their performance at low temperatures remains a challenge. This study investigates the influence of electrolyte solvent composition on LIB performance under low-temperature conditions. Three electrolytes were studied: a standard electrolyte (STDE) comprising 1 M LiPF6 in ethylene carbonate (EC) and diethyl carbonate (DEC), a low-temperature electrolyte (LTE) consisting of 1 M LiPF6 in EC, ethyl methyl carbonate (EMC), and ethyl acetate (EA), and a long-cycle-life electrolyte (LCLE) containing 1 M LiPF6 in EC/EMC. The EIS results revealed significant differences in resistance values among the electrolytes at varying temperatures. Specifically, at 0 °C, the STDE exhibited a charge transfer resistance (Rct) of 1055.3 Ω and a solid electrolyte interface resistance (RSEI) of 803.4 Ω, whereas the LTE showed a substantially lower Rct of 507.4 Ω and RSEI of 64.2 Ω, indicating superior low-temperature performance. Similarly, at -20 °C, the Rct values for STDE, LTE, and LCLE were 8878.6 Ω, 854.2 Ω, and 15622 Ω, respectively, with corresponding RSEI values of 172.1 Ω, 92.4 Ω, and 2364 Ω. Notably, the addition of EA in the LTE formulation contributed to enhanced low-temperature performance, likely by lowering the overall viscosity of the electrolyte mixture and improving ionic mobility. This study demonstrates the critical role of solvent composition, particularly EA, in optimizing LIB performance for cold climate applications.
