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Nowadays, what captures consumers' primary attention is how to purchase electric vehicles with long range and desirable price. Lightweight construction stands as one of the most effective approaches for prolonging range and lowering costs. As a consequence, it is particularly imperative to undertake lightweight design optimization for the battery bracket of new energy vehicles by applying 3D printing technology. To actualize this goal, Rhino software was initially employed for 3D modeling to design the battery bracket system for a pure electric vehicle in China. Subsequently, topology optimization design of the battery bracket was carried out by adopting Altair Inspire software. Last but not least, manufacturing and assembly inspection were completed using a 3D printer. The results show that the maximum displacement of the battery lower tray bracket after topology optimization is 3.20 mm, which is slightly higher than before, but still relatively small. The maximum Mises equivalent stress rose to 240.7 MPa post-optimization, but brought about a uniform stress distribution at the bottom of the bracket. In comparison, the minimum factor of safety met design requirements at 1. The mass was lessened to 0.348 kg, representing a 49.2% decrease in comparison with pre-optimization levels. The 3D-printed bracket was fabricated by employing a 3D printer, thereby achieving the aforementioned mass abatement. The battery pack parts exhibited a bright surface with low roughness and no discernible warping or deformation defects. As revealed by the assembly results, the components of the battery pack bracket are tightly coordinated with each other, with no evident assembly conflicts, revealing that the dimensional accuracy and fit of the completed parts meet production requirements. These findings lay solid groundwork for the mass production of high-performance battery pack brackets. [ABSTRACT FROM AUTHOR]

Interest towards electric vehicle adoption is on the rise due to the lower running and maintenance cost it offers, along with zero tailpipe emissions. Range anxiety is one of the only concern that affects the adoption of electric vehicles. The state of charge of the traction battery pack has to be accurately determined and provided to the user to avoid range anxiety. Minute battery parameters has to be considered to improve the accuracy of the state of charge determination. In order to overcome the problem of range anxiety, an innovative strategy that takes into account how vibrations affect the performance of EV batteries is developed in this research. By doing this, the state of charge estimation precision is improved and thereby raises the driver's faith in electric vehicles. The impacts and vibrations felt on the traction battery pack during driving would lead to heat generation. The heat generated is found to be highest when the vibrations resonate at the natural frequencies of the traction battery pack. The natural frequency of the battery pack is considered when the battery is kept in the battery chamber of the two-wheeler electric vehicle. The vibrations at natural frequency produces heat which is accounted for when the state of charge is determined. To obtain accurate state of charge estimation, a Kalman filter-based approach is used. The Kalman filter-based estimation uses the conventional methods which are the open circuit voltage method and the Coulomb counting method to improve the estimation process along with the consideration of the heat component due to vibrations and impact. The vibration analysis is performed using MATLAB, while the state of charge determination is implemented in hardware and the Kalman estimation done using Python. The system is modelled on an electric two-wheeler platform and the testing is done to compare the state of charge accuracy of the open circuit voltage method, the Coulomb counting method and the Kalman filter-based estimation approach. The inclusion of the vibrational heat analysis for State of Charge estimation in the hardware testing of the electric two-wheeler provides an accurate state of charge value. [ABSTRACT FROM AUTHOR]

The fire hazard resulting from the thermal runaway of lithium-ion batteries constitutes an severe threat for electric vehicles, and discovering an effective and prompt method for suppressing battery fire is still challenging. In this paper, a finite volume model for simulating the process of extinguishing lithium-ion battery fire was established, and the effect of water mist on suppressing battery fire was studied. It was found that the larger the droplet size, the greater the initial spray velocity, or the higher the nozzle height, the worse the fire extinguishing effect. The larger number of nozzles, the greater the spray flow, or the earlier the spray start time, the better the fire extinguishing effect. As the spray duration increased, the suppression effect at the center module gradually increased. When the water mist nozzle faced the center point of the module, the temperature rise was much lower than at other angles, and the fire extinguishing performance was the most effective. [ABSTRACT FROM AUTHOR]

This study contains experimental and numerical investigation of the shape effect of the pack on the performances of PCM (or GNP/PCM) based passive thermally protected battery packs. Also, the performances of the PCM and thermally enhanced GNP/PCM composite for battery thermal protection are compared from low to high discharge rates. The thermal response results show that the cylindrical pack performs worse than the rectangular pack in terms of the maximum temperature and maximum temperature difference performance criteria. For the maximum temperature restriction criteria, 7% GNP/RT44 composite, that has enhanced thermal conductivity, performs better at first, but then its performance deteriorates compared to RT44 depending on the increase of its viscosity. It was determined that 7% GNP/RT-44 extend the effective protection times by 95.8%, 73.3% and 28.0% at the discharge rates of 4.4 W, 6.6 W and 8.8 W, respectively. [ABSTRACT FROM AUTHOR]

Electric vehicles are a clean energy transportation option recently emerged as an alternative to the conventional engine powered vehicles. These vehicles are using Lithium ion battery as energy storage for their propulsion because of its energy density. Due to the chemical reaction of battery elements and internal resistance, the battery releases heat during charging and discharging. Unless this heat is controlled to be within the battery optimum operating temperature, the battery performance and life will be seriously affected. This paper is dedicated to conduct fundamental studies on the battery cooling. A three dimensional numerical analysis is made using PHOENICS version 2018. Cylindrical type battery cell is used in this study. The study gives insight to thermal response, flow field and temperature profiles in the battery module with air flow direction relative to battery cell orientation and cell arrangement. Temperature variation along the flow, and transverse direction of the battery pack is discussed. With a 5 mm inter cell spacing and symmetric arrangement, maximum cell to cell temperature variation in the axial flow type is observed to be 0.2 °C, while in the radial flow type about 3.5 °C for same arrangement. Quantitative and qualitative results obtained from the numerical test are presented. Furthermore, this work is believed to contribute to the improvement of battery air cooling system design in such a way the associated cost and efficiency is compromised. [ABSTRACT FROM AUTHOR]

In order to suppress leakage current caused in the traditional multi-cells series Li-ion battery pack protection system, a new battery voltage transfer method is presented in this paper, which uses the current generated in the transfer process of one of the batteries to compensate for the leakage of itself and other cells except the top cell. Based on the 0.18 µm Bipolar and CMOS and DMOS technology, this proposed circuit has been integrated into a 7-cells Li-ion battery charge and discharge protection chip successfully. The experimental results of cell balancing confirm that the balancing algorithm can help with the shortage of the voltage transfer circuit. Furthermore, analysis of 20 samples shows that the new method can greatly suppress the battery leakage. Compared with the traditional solution, the voltage transfer circuit proposed in this paper greatly reduces the leakage current, which helps to extend the service life of the battery. [ABSTRACT FROM AUTHOR]

The effectiveness of suppression of lithium ion battery, LIB, fires with water mist was investigated experimentally using a previously developed bench-scale wind tunnel. The experiments were conducted on lithium ion cell arrays constructed from twelve cylindrical (18,650 form factor), fully charged, lithium cobalt oxide cells, which were densely packed in a rectangular configuration without gaps. An electric heater was employed to initiate thermal runaway in one cell. Failure propagation was then tracked using thermocouples located at the bottom surfaces of the cells. Heat release due to flaming combustion was computed based on the oxygen consumption method. Experiments conducted at 640 l min−1 of air, 320 l min−1 of air, and 186 l min−1 of nitrogen tunnel purge flow were used as reference points. All reference point experiments underwent complete cascading failure. Addition of 1.0 and 1.6 g s−1 of water mist to 320 and 640 l min−1 of air produced agent concentrations of 14.1 and 11.1 wt%, respectively, which are slightly above the concentration of water mist recommended for suppression of traditional fires. Application of water mist at 1.0 and 1.6 g s−1 prevented cascading failure in 40% and 50% of the tests, respectively, and significantly reduced the rate of failure propagation in the other tests. At both water mist delivery rates, flaming combustion associated with burning of battery ejecta was inhibited, reducing the combustion efficiency below 50%. One of the key findings of this study is that suppression of flaming combustion is not sufficient to stop cascading failure. The array must be continually cooled with water mist until the temperature of the cells decreases below a certain threshold, which prevents chemical reactions between battery materials inside the cell casings. [ABSTRACT FROM AUTHOR]

Purpose: Battery electric vehicles (BEVs) have been widely publicized. Their driving performances depend mainly on lithium-ion batteries (LIBs). Research on this topic has been concerned with the battery pack's integrative environmental burden based on battery components, functional unit settings during the production phase, and different electricity grids during the use phase. We adopt a synthetic index to evaluate the sustainability of battery packs. Methods: A life cycle assessment (LCA) is used to reveal the aspects of global warming potential (GWP), water consumption, and ecological impact during the two phases. An integrative indicator, the footprint-friendly negative index (FFNI), is combined with footprint family indicators of battery packs and electricity sources. We investigate two cases of 1 kg battery production and 1 kWh battery production to assess nickel–cobalt–manganese (NMC) and lithium–iron phosphate (LFP) battery packs and compare their degrees of environmental friendliness. Then, we break down the battery pack to identify the key factors influencing the environmental burden and use sensitivity analysis to analyze the causes. Moreover, we evaluate the environmental impact of battery packs during the use phase among different regions. Results and discussion: Regardless of the functional unit (FU), the weights of the carbon footprint (CF), water footprint (WF), and ecological footprint (EF) are approximately the same. The results of the integrative environmental indicator, the FFNI, illustrate that the LFP is approximately 0.014, which is lower than that of the NMC battery pack in the mass production case. When using energy units as the FU, the FFNI of the NMC is 0.015, which reflects a lower environmental burden than that of other battery packs. In the use phase, 1kWh electricity consumption in China and Europe has the highest and lowest FFNI, respectively. When breaking down the battery-pack components, the simplified model advocates the cathode as the major contributor that determines the total environmental performance. In the following sensitivity analysis, the battery management system (BMS) is found to be the most intensive part of the footprint of most battery packs. Conclusion: FU can influence the evaluation results. Developing proper renewable energy sources can reduce the footprints of battery packs during the use phase. The positive electrode pastes in the battery cell, BMS, and packaging in the battery pack can influence the environmental burden. Adopting green materials in sections like the BMS may be a specific measure to enhance the environmental friendliness of a battery pack during the production phase. [ABSTRACT FROM AUTHOR]

To reduce the internal resistance of battery cells or electrolyte leakage, stacked type battery packs are typically assembled and are tightly compressed by fixture structures such as endplates. Endplates must have enough rigidity to uniformly compress a battery stack, especially for large-formatted battery stacks. The present study proposes a computational approach to analyze and predict the bending deformation of endplates of stacked type battery packs. Computational result agrees well with the actual measurement of bending deformation in a flow battery stack. Analyzing the stress distribution of endplates, nine stiffener models are considered to minimize the bending deformation by reinforcing the endplates. It is found that the endplate with three vertical stiffeners is the most effective design. Additionally, response surface method (RSM) is conducted to find the optimal value of design parameters for the stiffeners. [ABSTRACT FROM AUTHOR]

This paper offers novel insights to the design and implementation of an innovative state-of-charge (SOC) estimator for the lithium-ion (Li-Ion) series battery pack. The most interesting feature of this approach is that it can utilize information from each filtered terminal voltage of the Li-Ion cells connected in series for SOC estimation of the battery pack. Without actual sensing each discharging/charging current (DCC) applied to the Li-Ion cells, it is possible to extract each DCC estimation from the corresponding filtered terminal voltages with an equivalent electrical circuit model (EECM) identification of all Li-Ion cells in the battery pack. There are two advantages to SOC estimation of the battery pack with this approach. First, the proposal can be implemented simply and effectively, reducing the computational steps required for SOC estimation. By reducing computational steps, the proposal is expected to be more cost-effective. Second, the approach guarantees an improved SOC performance, even if the battery pack results in inevitable cell-to-cell variation among Li-Ion cells. Accordingly, there are fewer differences to previously estimated DCCs among Li-Ion cells. Specifically, all values from the estimated DCCs are properly compensated for by simultaneous parameter modification according to each cell's electrochemical characteristics. Experimental results clearly demonstrate that our DCC sensorless SOC estimator provides robust SOC performance for the battery pack. This approach considered an experimental battery pack (12S1P) connected in series using 2.6 Ah LiCoO2 cells produced by Samsung SDI. [ABSTRACT FROM AUTHOR]