Battery Thermal Management Research Articles

Structural optimization of thermal management system for bionic liquid cold battery based on fuzzy grey correlation analysis

An energy-efficient battery thermal management system with efficient enhanced heat transfer characteristics, low power consumption and backflow inhibition performance is of great importance for electric vehicle power batteries. Based on the design of the Tesla valve and inspired by bionics, a new type of bionic blade-like mini-channel liquid cold plate with high efficiency, low power consumption and certain anti-reverse flow performance was proposed. Firstly, the initial liquid-cooled plate thermal simulation model at 5C discharge was established by CFD method and its reliability was verified by experiment. Then, orthogonal tests and fuzzy correlation analysis (FGRA) were used as evaluation methods to analyze the effects of four structural parameters (inner angle α, circumcenter angle θ1, circumcenter angle θ2, and channel height d) on the average temperature, heat transfer coefficient, and friction coefficient. The results show that the variation of the channel height d had the highest degree of influence on the mean temperature (Tave) and friction coefficient f, and that the internal angle α had the highest correlation with the heat transfer coefficient h. Finally, based on the optimization results, a better model within the range of values of each factor was obtained. When α = 25°, θ1 = 90°,θ2 = 75°, and d = 1.2 mm, Nu was increased by 0.932 (95.08 %), and ΔP was decreased by 501.686 Pa (84.74 %).The results of the optimization were shown in the following table.

Thermal management of Li-ion battery by using eutectic mixture of phase-change materials

Lithium-ion batteries have a wide range of applications in portable electronic devices, global positioning systems, and the automobile industry due to their remarkable attributes like high energy density, long life cycle, higher efficiency, low self-discharging, and worthier operational performance. Although under different vigilant operating parameters, lithium-ion batteries generate a significant amount of heat, which deteriorates their performance and can lead to thermal runaway. To mitigate this issue and to improve safety, battery life, capacity, and overall performance, a robust thermal management system is very necessary. This study scrutinizes the effect of a passive cooling method using phase-change materials and their eutectic mixture on a 2600 mAh lithium-ion battery pack during the charging and discharging at various C-rates (1C, 1.5C, and 2C). Phase-change materials used in the experimentation are salt hydrates namely calcium nitrate tetrahydrate and zinc nitrate hexahydrate and their eutectic mixture contains 55 % calcium nitrate tetrahydrate and 45 % zinc nitrate hexahydrate. Experimental results reveal that without the usage of any phase-change material, the highest temperature was recorded at a 2C rate due to high current, with cell 5 recording a temperature of 60.98 °C. Zinc nitrate hexahydrate reduced the temperature by 18.98 °C to maintain it at 42 °C, and calcium nitrate tetrahydrate led to a temperature drop of 14.48 °C, maintaining it at 46.50 °C. The eutectic mixture caused a temperature reduction of 21.97 °C, maintaining it at 39.01 °C. The results of this study illustrate that the implementation of eutectic mixture as a phase-change material diminishes both the maximum surface temperature and the temperature gradient. This implies its efficacy as a viable material for the cooling of battery packs.

Thermal performance enhancement with snowflake fins and liquid cooling in PCM-based battery thermal management system at high ambient temperature and high discharge rate

The application of phase change materials (PCMs) in battery thermal management system (BTMS) is restricted by their low thermal conductivity and the challenge of heat-storage saturation after latent heat depletion, particularly in conditions with high ambient temperature and discharge rate. To enhance the performance of thermal management, this study firstly evaluates the thermal behaviors of two designs, Batteries-PCM and Batteries-PCM-Fins, under discharge rates of 3C and 5C, in conjunction with ambient temperatures of 25 °C and 40 °C. Building on this foundation, a hybrid thermal management system that incorporates snowflake fins and liquid cooling is proposed. The cooling efficiency of five different liquid cooling plate configurations (Design I-V) is compared, and the impact of coolant flow rate is explored. The results indicate that the snowflake fins in the Batteries-PCM-Fins design effectively reduce battery temperatures at a 3C discharge rate, maintaining a max temperature difference below 3 °C. However, at a 5C discharge rate and 40 °C ambient temperature, there is a noticeable increase in the peak temperature of the battery module across numerous cycles. Among the tested designs, Design IV shows the best performance. Specifically, when the coolant flow rate is 0.1 m/s, the discharge rate is 5C, and the ambient temperatures are 25 °C and 40 °C, compared to the design lacking a liquid cooling plate, the maximum temperature of the battery module decreases by 17.40 % and 21.36 % respectively, with respective decreases of 42.53 % and 55.77 % in the maximum temperature difference.

Case study on thermal management of planar elements with various polymeric heat exchangers: experiment and simulation

A reliable battery thermal management system (BTMS) is essential to ensure proper performance, a long life span and high electric vehicle safety. The primary objective of BTMS is to maintain the cells’ temperature in the range of 15–35 °C while limiting the temperature spread between cells to below 5 °C. Active thermal management with polymeric hollow fibers (PHFs) has been reported in a few articles, but its tremendous flexibility is mainly advantageous for cylindrical cells. Extruded polymeric cold plate heat exchangers with rounded rectangle channels (RRCs) are proposed as a more elegant solution for planar batteries. Heat exchangers using PHFs and RRCs were experimentally compared, with a strong focus on minimizing the maximum temperature and temperature spread of the experimental setup while simultaneously achieving minimal pressure drops. The system behavior with different parameters, including materials, geometry and thermophysical properties, was further studied using properly validated CFD models.

Two-phase cooling system for electric vehicles’ battery

The objective of this research project is to design an innovative cooling system for effectively managing the thermal conditions of batteries in electric vehicles. Electric vehicles commonly utilize Lithium-Ion cells as their power source. Despite significant advancements in Lithium-Ion technology from an electrochemical standpoint, the thermal management of these batteries remains a formidable challenge. This is primarily due to the demanding operational conditions that Lithium-Ion cells face during battery discharge, motion, and charging. The power supply unit in electric vehicles often demands high power outputs within short durations, leading to the generation of substantial heat by the batteries. This elevated working temperature poses a risk of decreased battery performance or even malfunction. Therefore, an efficient battery thermal management system is essential to optimize the performance of the batteries. In our research project, we propose and investigate a cooling system that is directly integrated into the power supply unit. Our study introduces an innovative thermal management system that combines two-phase direct liquid cooling with pulsating heat pipes. This system provides a compelling solution by combining high thermal efficiency, passive operation, and cost-effectiveness. Within this configuration, batteries are immersed in a low-boiling dielectric fluid contained in a Plexiglas container, facilitating efficient heat exchange. Simultaneously, the pulsating heat pipe operates to manage heat spikes by promoting vapor recondensation, thereby maintaining safe operational temperatures. The proposed battery thermal management system has demonstrated remarkable efficiency, ensuring that battery temperatures remain within the recommended range even under high load conditions. A notable advantage of this cooling system is its complete passivity, eliminating the need for energy-consuming coolant circulation.

Prediction of the minimum heat loss coefficient for safe operation of a Li-ion cell: A machine learning approach

The operating conditions, either C-rate or DoD, of all the Li-ion cells in the battery pack of EVs are subject to continuous change. In addition, the cells’ ambient temperature (Tamb ) is also not constant due to geographical or day/night conditions. As the generation and transfer of heat from the cells are vital functions of C-rate, DoD, and Tamb , choosing an appropriate heat loss coefficient for the given conditions is imperative to maintain the operating temperature of the cell below a specified Set Point Temperature (SPT). The selected heat loss coefficient must be the minimum possible such that overcooling of the cells can also be eliminated. The present study employed a machine learning based surrogate model called Gaussian Process Regression (GPR) to achieve this objective for an AMP20M1HD - A0 Li-ion pouch cell. The training and validation of the surrogate model are conducted with the samples generated using Latin Hypercube Sampling and simulated using the NTGK model available in the Ansys Fluent. The model’s accuracy is further tested for three new combinations of the operating conditions, which are not used for training or validation. Using the present model, the predicted minimum heat loss coefficient successfully regulates the cell’s maximum temperature below a user-specified SPT for the same user-given operating conditions. The developed model immensely helps in designing a cost-effective battery thermal management system with optimum cooling capacity by predicting the nature of heat loss coefficients for all plausible combinations of the operating conditions.

Simulation of health assessment model for thermal management system of lithium-ion battery based on fuzzy clustering algorithm

Considering the inadequate assessment of the factor decline index in the thermal management system for lithium-ion batteries, which has a negative impact on their efficient utilization, a fuzzy clustering algorithm is suggested to create a simulation model for evaluating the health of the lithium-ion battery thermal management system. In the process of restoring characteristic data by the fuzzy clustering algorithm, according to the characteristic parameters of energy signal and power signal, the decay characteristic results of the lithium-ion battery thermal management system are extracted. Taking the minimum attenuation as a reference, the evaluation function is calculated, the health trend of the lithium-ion battery thermal management system is evaluated, the health grade is established, and the health evaluation model of the lithium-ion battery thermal management system is constructed. The experimental results show that the prediction of the remaining service life of five kinds of lithium-ion batteries by this model is consistent with the actual value, and the average absolute error is always within 0.02, which is superior in health assessment.

Estimation of thermophysical properties of a pouch-type Li-ion battery using an inverse methodology

The growing popularity of electric vehicles highlights the crucial role of batteries. Effective battery thermal management is crucial for improving performance, reliability, and safety, especially in tropical areas where overheating is a key challenge. This necessitates a comprehensive understanding of the thermophysical properties of batteries. The present study concerns the estimation of the temperature-dependent orthotropic thermophysical properties (kx , ky , kz , cp ) of the active material in a pouch-type Li-ion battery using an inverse methodology. An experimental study is conducted on a commercial AMP20M1HD-A Li-ion battery to measure the surface temperature at various locations using thermocouples. The forward model consists of the three-dimensional unsteady conduction problem and is solved in COMSOL using experimental boundary conditions. The data generated is used to train an Artificial Neural Network, which acts as a replacement for the forward model. The Metropolis Hasting-Markov Chain Monte Carlo algorithm along with the Bayesian inference inverse model is used for analyzing the posterior distribution and the average estimates for thermophysical properties are obtained. The temperature dependence study shows a significant correlation between temperature and battery thermophysical properties. The accuracy of the employed inverse model is validated by obtaining the surface temperature using the estimated thermophysical properties and comparing it with the measured surface temperature.

A review on recent progress in battery thermal management system in electric vehicle application

Global challenges of energy crisis and air pollution have presented a tremendous opportunity for the development of electric cars. Li-ion batteries are crucial for electric cars (EVs). Nevertheless, Li-ion batteries are sensitive to the operating temperature and only function optimally within a certain temperature range. Hence, EVs require a battery thermal management system (BTMS). A cooling system's advantage is that it prevents the premature deterioration of battery life. This article examines several battery temperature management techniques and classifies them as either active or passive. In addition, the hybrid BTMS with an active/passive combination is described. This article gives an overview of current advancements in the direction of BTMS with direct and indirect cooling technologies, as well as key insights into hybrid BTMS.

Numerical study on hybrid battery thermal management system integrating water, phase change material, and fins, under New European Driving Cycle

This study introduced a hybrid thermal management system for a 4×4 cylindrical lithium-ion battery module, simulating New European Driving Cycle (NEDC) conditions. The system integrated water, phase change material (PCM), and fins for enhanced heat dissipation. The batteries, attached to an aluminium shell, incorporated PCM and a central coolant path. Fins were introduced between the coolant channel and Al shell to enhance heat transfer between batteries, PCM, and water. Comparative analysis against passive (PCM only) and active (liquid) cooling systems revealed the hybrid system’s superior performance. With a water flow rate of 2×10−8 m3/s, the system consistently kept temperatures below 50°C during charge-discharge cycles. Compared to active cooling, it achieved a significant temperature reduction of 18.47% and 5.01% after the charge and discharge processes. An intermittent cooling strategy further demonstrated its effectiveness in preventing thermal runaway (> 60°C) compared to the active cooling system. The proposed hybrid system demonstrated efficient thermal performance with low pumping power, suggesting its potential for multiple charge/discharge cycles.

A numerical investigation on a liquid-cooled battery thermal management system: Effect of inlet temperature and flow rate

Battery thermal management systems (BTMSs) and their stable operation are crucial for safety and efficiency of electrical vehicles. A BTMS utilized a cold plate is proposed in this paper for cooling of a cylindrical Li-ion Battery Pack (BP) arranged in 2×18 layout. The main focus of the study is on the effects of cooling fluid inlet temperature to cooling efficiency, and it is numerically investigated for 2C discharge rate at various flow rates from 0.1 to 1.0 l/min. The maximum temperature difference (ΔT max ) inside the BP and the maximum cell temperature (Tmax ) are analyzed via ANSYS Fluent software. Based on the comprehensive analysis of all system evaluation criteria, it can be concluded that the optimum flow rate is 0.5 l/min, and the optimum inlet temperature is 20 °C.

Enhancing Li‐Ion Electric Vehicle Battery Performance: Analysis of Advanced Thermal Management Cooling Strategies with Phase Change Material

Battery thermal management systems (BTMSs) are crucial for modern electric vehicle (EV) battery design, impacting system complexity, cost, and performance. This study calculates thermal performance using advanced computational analysis, employing a standard k‐ε turbulence model to simulate two cooling system setups: active and passive techniques utilizing phase change material (PCM). PCM with air cooling exhibits the lowest performance among hybrid BTMS setups, failing to maintain battery temperature uniformity. Conversely, PCM with n‐heptane, water cooling, and single liquid cooling (n‐heptane) achieve optimal battery module temperature ranges (20–40 °C) while preserving uniformity. Compared to noncooling configurations, the PCM + n‐heptane arrangement reduces Li‐ion battery module temperatures by 3.422, 10.261, and 28.33 °C at 1‐C, 2‐C, and 5‐C discharge rates, respectively. However, maximum temperatures at higher discharge rates (10C and 15C) remain elevated (350–380 K) with shorter discharge periods. The study highlights the necessity of appropriate cooling systems for battery thermal management to enhance performance and lifespan in EVs. Hybrid BTMS, particularly utilizing PCM, emerges as superior in maintaining uniform battery temperatures. Optimization strategies, including controlling coolant pump energy consumption and designing coolant pipes, are vital for efficient thermal management in diverse environmental conditions.

Developing a flame-retardant flexible composite phase change material to realize both temperature control and thermal runaway prevention for lithium-ion battery pack

Exploring a facile solution to controlling the operating temperature within the range between −25 °C and 60 °C and the temperature difference between batteries less than 5 °C as well as preventing thermal runaway for battery packs, is significant, but remains challenging. Herein, a flame-retardant flexible composite phase change material was developed and applied for both the temperature control and thermal runaway prevention of battery packs. Specifically, a flame-retardant coating comprising 70 % polydimethylsiloxane as a binder was first investigated to determine the optimal mass ratio of 3:1 for the blend of expandable graphite and ammonium polyphosphate. The flame-retardant flexible composite phase change material was then produced by applying the optimal coating at a loading of 15 % on a flexible composite phase change material that was obtained from incorporating an ethylene propylene diene monomer with a mass fraction of 40 % into an 80 % paraffin/20 % expanded graphite composite. The flame-retardant flexible CPCM not only exhibited the highest flame-retardant rating of V-0, a significant latent heat capacity and good thermal reliability, but also demonstrated improved thermal conductivity and enhanced mechanical properties in tensile strength, bending, and compression as compared with the uncoated counterpart. The flame-retardant flexible composite phase change material achieves better temperature control performance for a battery pack compared to the material without a flame-retardant coating. Moreover, the flame-retardant flexible composite phase change material effectively prevents thermal runaway propagation within a battery pack. These favorable characteristics demonstrate the considerable potential of the flame-retardant flexible CPCM for battery thermal management in electric vehicles.

Experimental Study of the Liquid Cold Plate Cooling System for Lithium-Ion Battery in Electric Vehicle

The battery remains the primary choice of energy and power storage in electric vehicles. To optimize battery performance, manufacturers have developed various technologies, including the battery thermal management system (BTMS). In this study, an experimental investigation was conducted to determine the cooling performance and characteristics of a liquid cold plate cooling system for 18650 lithium-ion battery. The testing involved an 18650 SONY 2100 mAh lithium-ion battery and a 400 W DC Load Tester. Testing was carried out by discharging the battery module and taking data on battery temperature and working fluid temperature to get the heat transfer coefficient. The discharge current varied at 1.25 C, 1.5 C, 1.75 C, and 2 C, while the flow rate was set at 0.2 LPM, 0.5 LPM, and 0.8 LPM. The results indicate that the cooling rate increases as the flow rate rises. The battery temperature rises quicker near the negative pole than at the further location. Furthermore, the pressure drop on the liquid cold plate increases as the flow rate rises, while the highest heat transfer coefficient to pressure drop ratio is observed at 0.2 LPM.

Wave and straight plenum effects on thermal management system performance

The need to offset heat generated by batteries in electric vehicles (EVs) necessitated the design and development of battery thermal management systems (BTMS), one of which adopt air cooling technique. The redesign of plenums of the BTMS has been beneficial in the enhancement of the BTMS's performance. In view of these, this study considered wave and straight design of plenums in an attempt to enhance the performance of the system. The proposed designs were investigated using Computational Fluid Dynamics (CFD) methodology. The CFD methodology was validated by first investigating the conventional Z-design of BTMS with straight plenums and the results were compared with existing results from experiments in literature. Findings from the study revealed that by replacing straight-horizontal plenum with straight-inclined plenum, maximum temperature (Tmax), and maximum temperature difference (ΔTmax) of the Z-design was reduced by 3.47 K and 6.82 K, respectively, with increase in pressure drop (ΔP) by 2.24 Pa and pumping power (Pp) by 0.01 W.Furthermore, by adopting wave-inclined plenum design, Tmax, and ΔTmax were reduced by 4.61 K and 8 K, respectively when compared with the conventional Z-design BTMS. More so, the pressure drop (ΔP) and pumping power (Pp) increased by 3.17 Pa and 0.0133 W, respectively. The study generally revealed that careful redesign of divergence plenum with inclined straight and wave-like structure will enhance the thermal performance of BTMS.

An energy saving strategy on the composite phase change material and spiral liquid cooling channel for battery thermal management

In order to ensure the safety and stability of the cooling system during the operation of the battery thermal management system combined with composite phase change material cooling and liquid cooling, it is usually necessary to continuously pump cooling water. It inevitably caused that the latent heat of composite phase change material could not be fully released and extra pump power was consumed. In the study, five different energy saving strategies were proposed and the energy efficiency ratio was defined to evaluate their cooling effects and energy saving. The effect of energy saving strategies on energy consumption of liquid cooling and latent heat utilization of composite phase change material was analyzed. The results show that III and V can meet their cooling requirements and have a high energy efficiency ratio. The screw pitch and cooling water flow rate in these two modes were investigated. The results show that the increase in screw pitch reduces the heat transfer efficiency, resulting in an increase in Tmax and ΔTmax, and ΔTmax exceeding the maximum range. Diminishing the cooling water flow will precipitate a rise in battery temperature, enabling the CPCM to operate at its maximum capacity and consequently decreasing ΔTmax. As a cooling water flow of 20 ml/min in III and V all can satisfy the cooling requirements. Additionally, the III was also competent when the cooling water temperature was raised from 25 °C to 35 °C.

Comparative Evaluation of Liquid Cooling-Based Battery Thermal Management Systems: Fin Cooling, PCM Cooling, and Intercell Cooling

The escalating demand for electric vehicles and lithium-ion batteries underscores the critical need for diverse battery thermal management systems (BTMSs) to ensure optimal battery performance. Despite this, a comprehensive comparative analysis remains absent. This study seeks to assess and compare the thermal and hydraulic performances of three prominent BTMSs: fin cooling, intercell cooling, and PCM cooling. Simulation models were meticulously developed and experimentally validated, with each system’s design parameters optimized under identical volumes to ensure equitable comparisons. In the context of fast-charging conditions, intercell cooling consistently met and even surpassed the desired target temperature, reducing the maximum temperature to 30.6°C with an increasing flow rate, while fin cooling faced challenges. Effective control of coolant temperature emerged as a critical factor for achieving optimal PCM cooling, with a potential reduction in temperature difference by 4.3 K. Despite exhibiting higher power consumption, intercell cooling demonstrated the most efficient cooling effect during fast charging. Considering the BTMS weight, fin cooling exhibited the lowest energy density, approximately half that of other methods. Addressing precooling and preheating conditions for high and low temperatures, the intercell method proved adept at meeting temperature requirements with minimal power consumption in significantly shorter durations. Conversely, the practicality of using PCM at high temperatures was deemed challenging.

Experimental study on flexible flame retardant phase change materials for reducing thermal runaway propagation of batteries

The current research on phase change materials (PCM) for Battery Thermal Management Systems (BTMS) often focuses on a single characteristic, either flame retardancy or flexibility. PCM with both flexibility and flame retardancy is relatively uncommon, and studies on flexible PCMs have lacked experimental validation of their effectiveness. This study explored the optimal ratio of aluminium hydroxide (ATH)/ magnesium hydroxide (MTH)/ ammonium polyphosphate (APP), successfully creating a flexible flame-retardant PCM and applying it to battery cooling. The ratio of ATH/MTH/APP was determined as 9: 3:8, providing features such as leak resistance, high thermal conductivity, flame retardancy, and flexibility. Compared to the blank sample without flame retardants, the Peak Heat Release Rate (PHRR) and Total smoke production (TSP) of the PCM decreased by 48 % and 24.3 %, respectively. When applied to BTMS, the PCM restricted the battery's surface peak temperature and maximum temperature difference to 48.76 °C and 4.07 °C, respectively, at a discharge rate of 6C. After applying pressure to leverage flexibility, the temperature difference was further reduced to 1.76 °C, demonstrating the effectiveness of flexibility. In Thermal Runaway (TR) experiments, the PCM delayed the time triggered by TR by 84 s and reduced the maximum temperature by 92.3 °C. This work successfully combines flame retardancy and flexibility, offering valuable insights for the application of flame retardant flexible CPCM in BTMS and other relevant fields.

The use of thin aerogel sheets to suppress the thermal runaway propagation of high energy density cells (LiNi0.8Co0.1Mn0.1O2/Si-C) based module

Safety issue is the main concern for current lithium-ion batteries (LIBs), especially for the high energy density cells based on nickel-rich oxide/Si-C chemistries, which could experience violent explosion and intense burning with the temperature exceeding 1000 °C during thermal runaway (TR). And moreover, within a module/system, the TR of a single cell might trigger the TR of neighboring cells, usually called TR propagation, leading to a fire accident or even a server disaster. The objective of this work is to introduce an aerogel sheet with extremely low thermal conductivity and high thermal stability to block the TR propagation. The silica aerogel sheet (SAS) is synthesized via a sol-gel process followed by supercritical fluid drying. The thermal conductivities of the obtained SAS are 0.018, 0.029, 0.043 and 0.074 W (m·K) −1 at 20 °C, 300 °C, 500 °C and 800 °C, respectively. A simple module is constructed with two LIBs (NCM811/Si-C, 320 Wh/kg) sandwiched with a piece of SAS with various thicknesses (1.2–2.8 mm). The results show that the SAS of 1.2 mm or 1.8 mm thickness cannot stop the TR propagation. The propagation times to next cell are 50 (1.2 mm) and 106 s (1.8 mm), respectively. While the SAS of 2.3 mm or thicker can suppress the TR propagation successfully, and moreover, protect the neighboring cell from any voltage drop/collapse. The microstructure and thermal conductivity of the SAS after TR experiments do not show evident change, revealing that the as-prepared SAS is thermally stable during the violent TR process. This work provides new insights for battery thermal management system (BTMS).

Li-Ion Battery Thermal Characterization for Thermal Management Design

Battery design efforts often prioritize enhancing the energy density of the active materials and their utilization. However, optimizing thermal management systems at both the cell and pack levels is also key to achieving mission-relevant battery design. Battery thermal management systems, responsible for managing the thermal profile of battery cells, are crucial for balancing the trade-offs between battery performance and lifetime. Designing such systems requires accounting for the multitude of heat sources within battery cells and packs. This paper provides a summary of heat generation characterizations observed in several commercial Li-ion battery cells using isothermal battery calorimetry. The primary focus is on assessing the impact of temperatures, C-rates, and formation cycles. Moreover, a module-level characterization demonstrated the significant additional heat generated by module interconnects. Characterizing heat signatures at each level helps inform manufacturing at the design, production, and characterization phases that might otherwise go unaccounted for at the full pack level. Further testing of a 5 kWh battery pack revealed that a considerable temperature non-uniformity may arise due to inefficient cooling arrangements. To mitigate this type of challenge, a combined thermal characterization and multi-domain modeling approach is proposed, offering a solution without the need for constructing a costly module prototype.