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Composite phase change materials commonly exhibit drawbacks, such as low thermal conductivity, flammability, and potential leakage. This study focuses on the development of a novel flame-retardant phase change material (RPCM). The material's characteristics and its application in the thermal management of lithium-ion batteries are investigated. Polyethylene glycol (PEG) serves as the medium for phase change; expanded graphite (EG) and multi-walled carbon nanotubes (MWCNT) are incorporated. Moreover, an intumescent flame retardant (IFR) system based on ammonium polyphosphate (APP) is constructed, aided by the inclusion of bio-based flame-retardant chitosan (CS) and barium phytate (PA-Ba), which can improve the flame retardancy of the material. Experimental results demonstrate that the RPCM, containing 15% IFR content, exhibits outstanding flame retardancy, achieving a V-0 flame retardant rating in vertical combustion tests. Moreover, the material exhibits excellent thermomechanical properties and thermal stability. Notably, the material's thermal conductivity is 558% higher than that of pure PEG. After 2C and 3C high-rate discharge cycles, the highest temperature reached by the battery module cooled with RPCM is 18.71 °C lower than that of natural air-cooling; the material significantly reduces the temperature difference within the module by 62.7%, which achieves efficient and safe thermal management. [ABSTRACT FROM AUTHOR]

In this study, the effects of battery thermal management (BTM), pumping power, and heat transfer rate were compared and analyzed under different operating conditions and cooling configurations for the liquid cooling plate of a lithium-ion battery. The results elucidated that when the flow rate in the cooling plate increased from 2 to 6 L/min, the average temperature of the battery module decreased from 53.8 to 50.7 °C, but the pumping power increased from 0.036 to 0.808 W. In addition, an increase in the width of the cooling channel and number of channels resulted in a decrease in the average temperature of the battery module and a reduction in the pumping power. The most influential variable for the temperature control of the battery was an increase in the flow rate. In addition, according to the results of the orthogonal analysis, an increase in the number of cooling plate channels resulted in the best cooling performance and reduced pumping power. Based on this, a cooling plate with six channels was applied to both the top and bottom parts, and the top and bottom cooling showed sufficient cooling performance in maintaining the average temperature of the battery module below 45 °C. [ABSTRACT FROM AUTHOR]

Performance of battery cells in an electric vehicle (EV) highly depends on environmental temperature. However, many studies do not consider its regional or seasonal characteristics. These characteristics can have a significant impact on the EV battery life in California, where there is a large variation of climate across the state. In some regions, the maximum ambient temperature can cause a rapid life degradation of the battery cells. In this study, we investigated the environmental temperature effects of six major cities in California on the capacity fade of the EV battery cells. A numerical model of an automotive battery pack and cycle-life model of a lithium-ion battery cell were implemented to predict the cell temperature and its corresponding capacity loss. The numerical results demonstrated the regional and seasonal effects of environmental temperature must be considered to prevent rapid life degradation in the automotive battery cells. [ABSTRACT FROM AUTHOR]

The primary objective of this study was to explore the impact of integrating nano-additives on heat transfer enhancement within an LHTES (Latent Heat Thermal Energy Storage) system. Our findings revealed that introducing a minimal amount of nano-materials (less than 5.0 vol%) into the Phase Change Material (PCM) led to a remarkable alignment between experimental correlations and mixture models. Furthermore, employing the mixing model allowed for the accurate prediction of outcomes. In the current context of scientific research, there is a strong endorsement for the widespread adoption of Electric Vehicles (EVs) as a sustainable alternative to Internal Combustion Engines (ICEs), crucial for advancing decarbonization and mitigating climate-related crises. Lithium-ion batteries are the predominant choice for EVs and various electrical devices. However, the operational challenges posed by high temperatures, impacting their lifespan, charge/discharge cycles, and the risk of thermal runaway, necessitate effective thermal management systems. Given this background, our study focuses on simulating the heat dissipation of a single cylindrical Li-ion battery cell employing a Nano-enhanced Phase Change Material (NePCM)-based cooling system. We also introduce a novel fin design in this work. Through comprehensive analysis, we examine the performance of battery modules utilizing PCM and NePCM at different discharge rates, both with and without the newly proposed fin design. Our research demonstrates that the incorporation of fins and nanoparticles into PCM significantly enhances heat transfer and reduces the charging time compared to the base PCM. Notably, carbon-based nanoparticles outshine their metal-based counterparts in terms of melting rate and maintaining a uniform temperature profile within the battery. [ABSTRACT FROM AUTHOR]

Copyright of Advances in New & Renewable Energy is the property of Editorial Office of Advances in New & Renewable Energy and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

A sizable composite phase change material (CPCM) that can be used for battery thermal management is prepared by blending expanded graphite (EG) and boron nitride (BN) with hot melt method and taking polyethylene glycol (PEG1000) as the raw material. The effects of the addition of EG and BN on the thermophysical properties of CPCM were investigated by adjusting the amounts of EG and BN. The chemical structure, phase change characteristics and thermal stability of CPCM were investigated based on infrared spectroscopy, differential scanning calorimetry and thermogravimetric analysis. A thermal conductivity test device was built based on the steady-state method to measure and calculate the thermal conductivity of CPCM. The results show that when the mass fraction of both EG and BN is 5%, the CPCM of PEG1000/5% EG/5 % BN has good thermal stability and the best thermal torage effect, with the latent heat of 126.72 kJ/kg, and the subcooling degree decreasing by 0.63 °C compared with that of PEG1000. The thermal conductivity of PEG1000/5% EG/5 % BN can reach 2.09 W/( m·K), which is 226.6% higher than that of PEG1000, and 27.4% larger than that of PEG1000/5% EG. Overall, PEG1000/5% EG/5% BN has a simple preparation process and a thermal conductivity greater than 2 W/(m·K) and a latent heat greater than 120 kJ/kg, making it suitable for battery thermal management systems. [ABSTRACT FROM AUTHOR]

In this paper, phase change material (PCM) based hybrid thermal management strategies are proposed for cylindrical Lithium-ion battery modules. Experimental and numerical studies are conducted to analyze the proposed strategies at a high discharge rate of 7 C. Three different types of thermal management configurations are developed. In all the configurations primary coolant is the PCM and secondary coolants are liquid and air. In one of the configuration vertical liquid coolant channels are placed between the PCM and airflow at the top of the cells. Whereas, in the two configurations different designs of cold plates are utilized in place of liquid channels. The experimental studies are conducted to obtain the temperature and heat flux profiles of the battery module. Moreover, a numerical model is developed and validated using the experimental data obtained. Using the numerical model, the thermal performance of the battery module was obtained for the proposed strategies. Based on the results, the maximum temperature of the battery module was limited to 29.1 °C and a high temperature uniformity was achieved by the end of the discharge cycle with the temperature difference limited to 1.2 °C. Additionally, the proposed hybrid thermal management strategy was capable of maintaining the required optimal thermal operating conditions without changing the phase of the PCM. Furthermore, it eliminates the requirement of a pump and reservoir since there is no flow of liquid within the battery module. This reduces the energy required for the operation of the thermal management system, thereby increasing the available energy for propulsion. Additionally, the developed strategy also increases the safety of the battery modules as it is capable of maintaining the required thermal environment in high discharge rates up to 7 C.

A phase change materials (PCM) coupled mini-channel cooling plates model was established for the optimization of the battery thermal management system (BTMS). Specific cooling strategies with different discharge rates of the battery were discussed. For a discharge rate of under 2C, using PCM can meet the heat dissipation needs. Particularly, for a discharge rate below 1.2C, external cooling was not necessary. For a discharge rate above 2C, active cooling should be added to compensate for the lack of heat storage of PCM. In the research of optimization structure, it was found that the scheme of four cooling plates and each cooling plate with two mini-channels was the most ideal in this research, which not only reduced the battery temperature efficiently but also maintained a good temperature uniformity of the battery. For the optimization parameters, the effect of the ethylene glycol solution temperature, ethylene glycol solution volume fraction and the start-up time of active cooling on the maximum temperature of the battery and the melting fraction of PCM were discussed. After the multi-factor parameters optimization by Response Surface Methodology, three optimization schemes were put forward, which could reduce the driving power consumption by 35% – 40%. The research could provide valuable information support and optimization suggestions for the design of BTMS.

Phase change material (PCM) cooling is regarded as a promising thermal management technique to realize a proper battery working temperature. However, the low thermal conductivity of PCM restricts its practical applications. In this study, the impact of aluminum fin insertion on the thermal performance of PCM thermal management is explored. Couples of fin structure shapes were adopted and their performances were compared. It is demonstrated from the simulation results that, among the fin structures investigated in this study, the bifurcated fin structures achieved the lowest battery maximum temperatures, specifically, the battery temperature was reduced by 6.16 K compared to the pure PCM case under 5C discharge (5C means that battery is discharged from full of charge to 0% state of charge in 1/5 h). The 2-branch bifurcated fin structure could realize a further 0.50 K temperature drop than the single-branch counterpart. Besides, the impacts of various parameters were investigated. The maximum temperature at the end of 5C discharge process was reduced from 314.30 K to 311.36 K when the fin quantity increased from 3 to 8. The maximum battery temperature reaches up to 313.80 K if the thermal contact resistance between the battery and fin structure grows to 0.0025 W/(m2⋅ K) with 8 fins while it could be decreased by 1.21 K if the contact resistance reduced half to 0.00125 ((m2⋅ K)/W. The maximum battery temperature was found to decrease by 0.27 K with PCM width enlarged from 28 mm to 29 mm.

Traditionally it has been assumed that battery thermal management systems should be designed to maintain the battery temperature around room temperature. That is not always true as lithium-ion battery (LIB) R&D is pivoting towards the development of high energy density and fast charging batteries. Therefore, it is necessary to have a comprehensive review of thermal considerations for LIBs targeted for high energy density and fast charging, i.e., the optimal thermal condition, thermal physics (heat transport and generation) inside the battery, and thermal management strategies. As the energy density and charge rate increases, the optimal battery temperature can shift to be higher than room temperature. In the first part of the review various sources of heat generation inside LIBs and various approaches to minimizing battery heat generation are summarized. The importance of heat of mixing due to ion diffusion during fast charging is also highlighted. To improve the temperature uniformity and avoid excessive internal temperature rise, heat transfer inside the battery needs to be enhanced, and reducing the thermal contact resistance between the electrodes and separator can significantly increase the effective thermal conductivity of batteries. In the second part of the review various challenges and latest developments related to thermal transport and properties of LIBs are discussed. Finally, a summary of latest advancement on smart control of internal temperature of LIBs is discussed as depending on the ambient temperature and the optimal temperature; the battery heat needs to be retained or dissipated to elevate or avoid temperature rise.

Traditionally it has been assumed that battery thermal management systems should be designed to maintain the battery temperature around room temperature. That is not always true as lithium-ion battery (LIB) R&D is pivoting towards the development of high energy density and fast charging batteries. Therefore, it is necessary to have a comprehensive review of thermal considerations for LIBs targeted for high energy density and fast charging, i.e., the optimal thermal condition, thermal physics (heat transport and generation) inside the battery, and thermal management strategies. As the energy density and charge rate increases, the optimal battery temperature can shift to be higher than room temperature. In the first part of the review various sources of heat generation inside LIBs and various approaches to minimizing battery heat generation are summarized. The importance of heat of mixing due to ion diffusion during fast charging is also highlighted. To improve the temperature uniformity and avoid excessive internal temperature rise, heat transfer inside the battery needs to be enhanced, and reducing the thermal contact resistance between the electrodes and separator can significantly increase the effective thermal conductivity of batteries. In the second part of the review various challenges and latest developments related to thermal transport and properties of LIBs are discussed. Finally, a summary of latest advancement on smart control of internal temperature of LIBs is discussed as depending on the ambient temperature and the optimal temperature; the battery heat needs to be retained or dissipated to elevate or avoid temperature rise.

The air-cooled system is one of the most widely used battery thermal management systems (BTMSs) for the safety of electric vehicles. In this study, an efficient design of air-cooled BTMSs is proposed for improving cooling performance and reducing pressure drop. Combining with a numerical calculation method, a strategy with a varied step length of adjustments (∆d) is developed to optimize the spacing distribution among battery cells for temperature uniformity improvement. The optimization results indicate that the developed strategy reduces the optimization time by about 50% compared with a strategy using identical ∆d values while maintaining good performance of the optimized system. Furthermore, the system’s pressure drop does not increase after the spacing optimization. Based on this characteristic, a structural design strategy is proposed to improve the cooling performance and reduce the pressure drop simultaneously. First, the appropriate flow pattern is arranged and the secondary outlet is added to reduce the pressure drop of the system. The results show that the BTMS with U-type flow combined with a secondary outlet against the original outlet can effectively reduce the pressure drop of the system. Subsequently, this BTMS is further improved using the developed cell spacing optimization strategy with varied ∆d values while the pressure drop is fixed. It is found that the final optimized BTMS achieves a battery temperature difference below 1 K for different inlet airflow rates, with the pressure drop being reduced by at least 45% compared with the BTMS before the optimization.

Maintaining the peak temperature of a battery within limits is a mandate for the safer operation of electric vehicles. In two-wheeler electric vehicles, the options available for the battery thermal management system are minuscule due to the restrictions imposed by factors like weight, cost, availability, performance, and load. In this study, a multi-strategical cooling approach of forced convection and mist cooling over a single-cell 21,700 lithium-ion battery working under the condition of 4C is proposed. The chosen levels for air velocities (10, 15, 20 and 25 m/s) imitate real-world riding conditions, and for mist cooling implementation, injection pressure with three levels (3, 7 and 14 bar) is considered. The ANSYS fluent simulation is carried out using the volume of fluid in the discrete phase modelling transition using water mist as a working fluid. Initial breakup is considered for more accurate calculations. The battery’s state of health (SOH) is determined using PYTHON by adopting the Newton–Raphson estimation. The maximum temperature reduction potential by employing an airflow improviser (AFI) and additives (Tween 80, 1-heptanol, APG0810, Tween 20 and FS3100) is also explored. The simulation results revealed that an additional reduction of about 11% was possible by incorporating additives and AFI in the multi-strategical approach. The corresponding SOH improvement was about 2%. When the electric two-wheeler operated under 4C, the optimal condition (Max. SOH and Min. peak cell temp.) was achieved at an air velocity of 25 m/s, injection pressure of 7 bar with AFI and 3% (by wt.) Tween 80 and a 0.1% deformer.

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.

This paper presents an innovative approach to Battery Thermal Management Systems (BTMS) utilizing a hybrid algorithm, the Dwarf Mongoose-based Coati Optimization Algorithm (DMCOA), in conjunction with a deep neural network (DNN). Our objective is to optimize the temperature of lithium-ion batteries, particularly in Electric Vehicles (EVs). The DMCOA draws inspiration from cooperative behaviors seen in coatis and dwarf mongooses. It employs advanced strategies, such as cooperative attacks simulation and escape behavior imitation to ensure efficient minimization of cost function. Additionally, a DNN is employed to predict vehicle speed and battery heat production rate under various conditions, enhancing the control of the BTMS. Simulation outcomes demonstrate the effectiveness of the hybrid algorithm in maintaining battery temperatures, with minimal deviation from the target range. Simulation results show that the proposed hybrid algorithm efficiently maintains battery temperatures, with just a 0.3°C average difference from the target and a maximum 1.1°C difference among modules. Additionally, it extends battery lifespan by 0.02%, 0.015%, and 0.01% compared to Fuzzy Logic control (FLC), Artificial Neural Network (ANN) and intelligent model predictive control (IMPC), respectively. It also achieves energy savings of 23%, 25% and 15% compared to the FLC, ANN, and IMPC models. Hence, it is evident that the proposed model holds promise for enhancing battery life span with minimal cost in EVs with its simplicity, efficiency, and robustness.

In this paper, an experimental and numerical study was conducted to analyze the performance of a hybrid thermal management concept for cylindrical lithium-ion battery modules at various discharge rates. The proposed concept consists of primary cooling through phase change material (PCM) and secondary cooling through vertical liquid channels between the PCM and airflow at the top of the cells. Two experimental studies were performed to obtain the temperature and heat flux profiles. In addition, the thermal performance of the battery module was obtained for 1 C, 2 C, 3 C, 5 C, and 7 C discharge rates using the numerical study. The results show that the maximum temperature was limited to ~30 °C. Additionally, the temperature uniformity in all the discharge rates was maintained below 5 °C. Finally, a meager amount of PCM was utilized during all the discharge cycles. At 1 C none of the PCM changed its phase, whereas at 2 C, 0.32%, 3 C, 0.14%, 5 C, 0.3%, and at 7 C, 0.12% of PCM changed its phase. The proposed hybrid concept can maintain the thermal environment required by the Li-ion cells for effective performance. Furthermore, this concept does not require excessive pumping fluid power and high air velocities, which reduces the energy required for the operation of the thermal management system, thereby increasing the available energy for propulsion. [ABSTRACT FROM AUTHOR]

Air cooling is a common cooling strategy to guarantee the performance and safety of electric vehicles, in battery thermal management systems (BTMS). Based on the traditional Z‐type and U‐type, a novel F‐type air‐cooling BTMS is proposed in this paper. The computational fluid dynamics (CFD) method is used to investigate the cooling performance of F‐type BTMS, and the effectiveness of the CFD method is verified by experiments. First, the effect of the outlet's position on the cooling efficiency of the F‐type BTMS is explored. It is revealed in the results that the outlet's position plays an important role in the cooling effect. Subsequently, the angle of the distribution manifold of the F‐type model is optimized. It is shown in the results that the maximum temperature (Tmax) and the maximum temperature difference (ΔTmax) of the optimized model are reduced by 2.28 (5.22%) and 4.36 °C (89.33%), respectively, compared with the Z‐type model. Then, baffles are added to some air flow channels and the shape of the battery box top corners is changed to further optimize its heat dissipation performance. Compared with the Z‐type model, the Tmax and ΔTmax of the optimum model are decreased by 2.48 (5.66%) and 4.60 °C (94.26%), respectively. [ABSTRACT FROM AUTHOR]

Electrification on transportation and electricity generation via renewable sources play a vital role to diminish the effects of energy usage on the environment. Transition from the conventional fuels to renewables for transportation and electricity generation demands the storage of electricity in great capacities with desired power densities and relatively high C-rate values. Yet, thermal and electrical characteristics vary greatly depending on the chemistry and structure of battery cells. At this point, lithium-ion (Li-ion) batteries are more suitable in most applications due to their superiorities such as long lifetime, high recyclability, and capacities. However, exothermic electrochemical reactions yield temperature to increase suddenly which affects the degradation in cells, ageing, and electrochemical reaction kinetics. Therefore, strict temperature control increases battery lifetime and eliminates undesired situations such as layer degradation and thermal runaway. In the literature, there are many distinct battery thermal management strategies to effectively control battery cell temperatures. These strategies vary based on the geometrical form, size, capacity, and chemistry of the battery cells. Here, we focus on proposed battery thermal management strategies and current applications in the electric vehicle (EV) industry. In this review, various battery thermal management strategies are documented and compared in detail with respect to geometry, thermal uniformity, coolant type and heat transfer methodology for Li-ion and post-lithium batteries. [ABSTRACT FROM AUTHOR]

Battery thermal management system (BTMS) is essential to the safe operation of electric vehicles. In order to improve the heat dissipation performance of BTMS, the Non-dominated sorting genetic algorithm-2 (NSGA2) combined with neural network is used to optimize the battery pack with multiple objectives. First, the three-dimensional battery pack model is converted into the two-dimensional model to simulate 2000 battery packs, saving much calculation time. Subsequently, five parameters, including the width of the inlet and the outlet, the position of the inlet and the outlet, and the battery spacing, are used as design variables to establish a BP neural network model with a good prediction effect of BTMS. After that, the NSGA2 algorithm is used to optimize the neural network model with multiple objectives. Finally, the final design solution with the lowest maximum temperature in the Pareto solution set is selected and simulated. The results show that the maximum temperature of the optimized battery pack is reduced by 7.5 K, the maximum temperature difference is reduced by 67.4%, and the power consumption is reduced by 26%. [ABSTRACT FROM AUTHOR]

Maintaining batteries within a specific temperature range is vital for safety and efficiency, as extreme temperatures can degrade a battery’s performance and lifespan. In addition, battery temperature is the key parameter in battery safety regulations. Battery thermal management systems (BTMSs) are pivotal in regulating battery temperature. While current BTMSs offer real-time temperature monitoring, their lack of predictive capability poses a limitation. This study introduces a novel hybrid system that combines a machine learning-based battery temperature prediction model with an online battery parameter identification unit. The identification unit continuously updates the battery’s electrical parameters in real time, enhancing the prediction model’s accuracy. The prediction model employs an Adaptive Neuro-Fuzzy Inference System (ANFIS) and considers various input parameters, such as ambient temperature, the battery’s current temperature, internal resistance, and open-circuit voltage. The model accurately predicts the battery’s future temperature in a finite time horizon by dynamically adjusting thermal and electrical parameters based on real-time data. Experimental tests are conducted on Li-ion (NCA and LFP) cylindrical cells across a range of ambient temperatures to validate the system’s accuracy under varying conditions, including state of charge and a dynamic load current. The proposed models prioritise simplicity to ensure real-time industrial applicability.

In this study, we present an innovative, fully automated, and digitalized methodology to optimize the energy efficiency and cost effectiveness of Li-ion battery modules. Advancing on from today’s optimization schemes that rely on user experience and other limitations, the mechanical and thermal designs are optimized simultaneously in this study by coupling 3D multi-physical behavior models to multi-objective heuristic optimization algorithms. Heat generation at various loading and ambient conditions are estimated with a physics-based, fractional-order battery cell-level model, which is extrapolated to a module that further accounts for the interconnected cells’ heat transfer phenomena. Several key performance indicators such as the surface temperature increase, the temperature variations on the cells, and heat uniformity within the module are recorded. For the air-cooled study case, the proposed coupled framework performs more than 250 module evaluations in a relatively short time for the whole available electro-thermal-mechanical design space, thereby ensuring global optimal results in the final design. The optimal module design proposed by this method is built in this work, and it is experimentally evaluated with a module composed of 12 series-connected Li-ion NMC/C 43Ah prismatic battery cells. The performance is validated at various conditions, which is achieved by accounting the thermal efficiency and pressure drop with regard to power consumption improvements. The validations presented in this study verify the applicability and overall efficiency of the proposed methodology, as well as paves the way toward better energy and cost-efficient battery systems.

Compared to the use of positive temperature coefficient (PTC) materials that consume electrical energy for low-temperature heating, heat pump air conditioners can provide more energy-efficient heating performance by absorbing and utilizing heat from the outdoor air to heat the cab in order to improve the range of electric vehicles. In addition, in order to make the battery work under safe working conditions, this paper proposes battery thermal management coupled with vapor injection heat pump air conditioning. The system is modeled and analyzed through simulation, and the impact of the compressor speed and ambient temperature changes in the battery cooling performance of the system. The results show that under different compressor RPM (Revolution Per Minute) with an ambient temperature of 5 °C, the average temperature of the battery pack remains below 30 °C, and the majority of individual cell temperatures are maintained within the range of 20 to 35 °C. At a constant compressor RPM of 4000/min under varying ambient temperatures, the average temperature of the battery pack remains below 30 °C, with the majority of individual cell temperatures staying within the range of 20 to 35 °C. And the battery cooling performance still performs well. In the low temperature of −10 °C and −20 °C, the system can still maintain a relatively stable heating capacity compared with the 2009.1W, provided by the environment temperature of 5 °C at the same RPM.

This paper introduces a novel hybrid thermal management strategy, which uses secondary coolants (air and fluid) to extract heat from a phase change material (paraffin), resulting in an increase in the phase change material’s heat extraction capability and the battery module’s overall thermal performance. A novel cold plate design is developed and placed between the rows and columns of the cells. The cold plate contains a single fluid body to improve the thermal performance of the battery module. Experimental studies were conducted to obtain the temperature and heat flux profiles of the battery module. Moreover, a numerical model is developed and validated using the experimental data obtained. The numerical data stayed within ±2% of the experimental data. In addition, the ability of nanoparticles to increase the thermal conductivity of water is examined and it is found that the cooling from the liquid cooling component is not sensitive enough to capture the 0.32 W/m K increase in the thermal conductivity of the fluid. Furthermore, in order to enhance the air cooling, fins were added within the air duct to the cold plate. However, this is not feasible, as the pressure drop through the addition of the fins increased by ~245%, whereas the maximum temperature of the battery module reduced by only 0.6 K. Finally, when scaled up to an entire battery pack at a high discharge rate of 7 C, the numerical results showed that the overall temperature uniformity across the pack was 1.14 K, with a maximum temperature of 302.6 K, which was within the optimal operating temperature and uniformity ranges. Therefore, the developed thermal management strategy eliminates the requirement of a pump and reservoir and can be scaled up or down according to the energy and power requirements.

The hybrid fuel cell/battery technology is an attractive option for a sustainable mobility with zero emissions. In fact, this solution owns system scalability features and high efficiency and, compared to battery electric solutions, it offers advantages in terms of flexibility of use and fast charging times. However, the thermal management for the battery in this type of powertrain is a crucial issue, since operating temperatures can significantly affect safety and performance. In this study, an innovative system aimed at providing high storage energy density and improving the battery pack performance of hybrid fuel cell/battery vehicles is investigated for use on-board of a plug-in fuel cell electric bike. The proposed system, developed by the authors in previous studies, integrates the battery pack with a hydrogen storage based on metal hydrides. The idea behind this solution is to exploit the endothermic desorption processes of hydrogen in metal hydrides to cool down the battery pack during operation. An experimental analysis is conducted to assess the thermal management capabilities of this system: by considering a typical duty cycle designed on the base of road test measurements, battery pack temperature profiles are evaluated and compared against those from a control experiment where no battery thermal management is enabled (i.e. no hydrogen desorption from the metal hydride tank). The results show that, beside enhancing the on-board stored energy capacity, the proposed system represents an effective solution to provide an efficient thermal management for the battery pack, with significant advantages in terms of attainable riding range. • Plug-in fuel cell electric bicycle with greater riding range than e-bike. • On-board storage system integrating metal hydrides tank and battery pack. • Enhanced volumetric and gravimetric on-board energy storage density. • Optimal thermal management of battery pack and metal hydride tank. [ABSTRACT FROM AUTHOR]

The accumulation of thermal energy in the form of latent heat of phase transition using phase change materials (PCMs) is one of the most attractive and studied research areas with huge application potential in both passive and active technical systems. The largest and most important group of PCMs for low-temperature applications are organic PCMs, mainly paraffins, fatty acids, fatty alcohols, and polymers. One of the major disadvantages of organic PCMs is their flammability. In many applications such as building, battery thermal management, and protective insulations, the crucial task is to reduce the fire risk of flammable PCMs. In the last decade, numerous research works have been performed to reduce the flammability of organic PCMs, without losing their thermal performance. In this review, the main groups of flame retardants, PCMs flame retardation methods as well as examples of flame-retarded PCMs and their application areas were described. [ABSTRACT FROM AUTHOR]

Adhering to the thermal management requirements of prismatic battery modules, an improved lightweight parallel liquid cooling structure with slender tubes and a thin heat-conducting plate is proposed. The multiobjective optimization of the structure, operating parameters of the thermal management system, and thermal characteristics of a battery module are carried out. The effects of the equivalent diameter of the square tubes and the inner diameter of the circular tubes on the maximum temperature, maximum temperature difference of the batteries, and coolant pressure drop of liquid cooling battery thermal management system (BTMS) are investigated. The more significant factors, selected as the design variables, are the equivalent diameter of the square tubes, the inner diameter of the circular tube, and the coolant inlet velocity. Combining the computational fluid dynamics (CFD) method with multiobjective optimization, the different conditions of heat management parameters obtained by Latin hypercube sampling are numerically calculated, and the optimization of these parameters is carried out by the second-generation Elitist Nondominated Sorting Genetic Algorithm (NSGA-II). Compared with the thermal characteristics of the battery module before optimization, the maximum temperature of the module after optimization is reduced by 9.3%, the maximum temperature difference is reduced by 20.7%, and the coolant pressure drop from inlet to outlet is reduced by 49.1%. [ABSTRACT FROM AUTHOR]

This study presents the experimental results of the effects on base oils after thermal and electrical aging to determine key parameters of next-generation fluids for thermal management in electric vehicles. The test fluids selected were a mineral base oil API G-III, an API G-IV Polyalphaolefin (PAO), a diester, and a polyolester, all of which had similar kinematic viscosity (KV100 = 4 cSt). All were initially characterized with measurements of density, viscosity, thermal conductivity, specific heat capacity, breakdown voltage, resistivity, and dissipation factor. They underwent two separate aging processes, one thermal, heating the test fluid at 150 °C for 120 h with a copper strip as a catalyst; and the second one an electrical aging process, with the application of 1000 breakdown voltage discharges. The same properties were measured again after each aging process and compared to the initial ones. It was found that the thermal properties ranged with similar values and did not suffer major changes after the aging processes, unlike electrical properties, which vary between samples and after thermal and electrical stress. The insights gained from this study have implications for both the development of next-generation e-thermal fluids and the future standardization of these fluids for EV thermal management applications. The findings of this study underscore the significance of formulating and selecting a suitable dielectric fluid for EV thermal management. By leveraging the insights provided, researchers and engineers can advance in the development of efficient and reliable e-thermal fluids while working towards future standardization to enhance the performance and safety of EV battery systems. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Refrigeration is the property of Journal of Refrigeration Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Based on the Peltier effect, a method of real-time controlling battery temperature through thermoelectric device (TED) was proposed. It integrated the refrigeration and heating functions of TED, has a good temperature control effect, and can meet the thermal management needs of battery modules. The battery module consists of 3x5 rows of cylindrical batteries filled with foam metal composite phase change materials, and the thermoelectric device was arranged on the large face of the battery module shell. Compared with the liquid cooling experiment, thermoelectric refrigeration could significantly reduce the temperature of the battery module at 1 ~ 5 W of single cell heat generation power, and control the temperature difference of the module within 5 °C. The temperature control experiment further shows that the TED controlled by the thermostat in real-time can effectively stabilize the module temperature and control the temperature fluctuation within 2 ~ 3 °C. In addition, a one-dimensional thermal resistance network was established, and the thermal performance of TED was analyzed based on steady-state theory. The result shows that under the refrigeration condition, the cold junction temperature of TED is decreasing first and then increasing with increasing of its current, and the hot junction temperature is proportional to the TED current. [ABSTRACT FROM AUTHOR]

Trying to prevent and mitigate carbon emissions and air pollution is one of the biggest challenges for the technological development of the automobile industry. In addition, the automobile industry has stepped up research and field applications of electric vehicles as the European Union encourages the restriction of the use of conventional fuel-powered vehicles such as diesel and gasoline vehicles. However, the cycle life, environmental adaptability, driving range, and charging time of the battery currently used in electric vehicles are far beyond comparison with internal combustion engines. Therefore, studies have focused on batteries, and battery thermal management systems (BTMSs) have been developed. Battery performance is highly dependent on temperature and the purpose of an effective BTMS is to ensure that the battery pack operates within an appropriate temperature range. Ensuring that the battery operates in the appropriate temperature range is vital for both efficiency and safety. To determine the best convenient BTMS for several types of battery packs attached to many factors such as volumetric constraints, installation costs, and working efficiency. The maximum temperature rise and the maximum temperature difference are the basic parameters to analyze the efficiency of the BTMS. Most of the research about thermal management has focused on especially air cooling, liquid cooling, and phase change material (PCM) cooling methods. In this study, different BTMSs (air cooling, liquid cooling, PCM cooling, etc.) were examined and their advantages and disadvantages were compared, usage restrictions in today's technology, requirements, and studies on this subject were reported. [ABSTRACT FROM AUTHOR]

Paraffin phase change materials (PCMs) exhibit great potential in battery thermal management (BTM); nevertheless, their application has been hampered by the handicap of low thermal conductivity, leakage, and volume expansion during phase transition. In this work, ternary composite PCMs formed of paraffin, expanded graphite (EG), and low-density polyethylene (LDPE) were developed for application in BTM. The structure and properties of the composite PCMs were characterized via X-ray diffraction, scanning electron microscopy, differential scanning calorimetry, and thermal constant analysis. The result shows that EG can form a large-size graphite frame as heat conduction paths to improve the thermal conductivity of the composite PCM, and LDPE can form an interpenetrating network within the composite PCM to resist the internal stress of paraffin expansion and prevent deformation. The latent heat and thermal conductivity of the composite PCMs loaded with 10 wt% EG and 4 wt% LDPE can reach 172.06 J/g and 3.85 Wm−1K−1 with a relatively low leakage ratio of 6.2 wt%. Remarkably, the composite PCMs could reduce the temperature rise of the battery by 55.1%. In brief, this work provides a feasible route to develop high-performance PCMs for BTM. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Chongqing University of Technology (Natural Science) is the property of Chongqing University of Technology and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Liquid cooling (LC) performs better than various other cooling technologies for battery thermal management (BTM) in electric vehicles (EVs), attributed to its high efficiency and low power consumption. However, the LC system for cylindrical lithium-ion batteries (CLIBs) has been scarcely designed and studied from the perspective of BTM unitization. In present work, a solution of unitization-based BTM with a novel distributed water-cooling component was proposed. Then, in COMSOL software, the multi-physical-field model of BTM system was carefully built to investigate the effects of three important system parameters (Vef, Ncc, and Tin) on the system performance. The results show that all the three parameters required determining moderately for balancing the system cooling performance, power consumption, and lightweight. Via stepwise analysis, the relatively optimal values of Vef, Ncc, and Tinwere found to be 9 × 10−7m3s−1, 4, and 34 °C respectively. In this case, Tmaxmwas controlled at 38.95 °C with ΔTmaxmas 4.36 °C, which could also well meet the battery temperature requirement under the unfavorable conditions of high ambient temperature (35 °C) and large discharge C-rate (3 C). Comparatively, Tinmore significantly influenced the transient thermal behavior of BTM system, and should not be lower than 32 °C. For the temperature distribution, the results of this study are superior to those in the referred literature at both the battery and module levels. In particular, such an advantage is favorable to improve the performance consistency among battery cells, and thus helps to prolong the lifespan of battery module/pack. In practical EV applications, the BTM unitization enables the restraining of thermal runaway propagation in battery system. This study can provide valuable reference to design and study the LC-BTM system of CLIBs in EVs.

Abstract Phase change materials (PCMs) are expected to achieve dual-mode thermal management for heating and cooling Li-ion batteries (LIBs) according to real-time thermal conditions, guaranteeing the reliable operation of LIBs in both cold and hot environments. Herein, we report a liquid metal (LM) modified polyethylene glycol/LM/boron nitride PCM, capable of dual-mode thermal managing the LIBs through photothermal effect and passive thermal conduction. Its geometrical conformation and thermal pathways fabricated through ice-template strategy are conformable to the LIB’s structure and heat-conduction characteristic. Typically, soft and deformable LMs are modified on the boron nitride surface, serving as thermal bridges to reduce the contact thermal resistance among adjacent fillers to realize high thermal conductivity of 8.8 and 7.6 W m−1 K−1 in the vertical and in-plane directions, respectively. In addition, LM with excellent photothermal performance provides the PCM with efficient battery heating capability if employing a controllable lighting system. As a proof-of-concept, this PCM is manifested to heat battery to an appropriate temperature range in a cold environment and lower the working temperature of the LIBs by more than 10 °C at high charging/discharging rate, opening opportunities for LIBs with durable working performance and evitable risk of thermal runaway.

The selection of a battery thermal management technique is important to overcoming safety and performance problems by maintaining the temperature of batteries within a desired range. In this study, a LiFePO4 (LFP) pouch-type battery having a capacity of 20 Ah was experimentally cooled with both air and liquid (immersion cooling) techniques. Distilled water was selected as the immersion fluid in the experiments, and the impact of discharge rate (1–4C), immersion ratio (50–100%), and coolant fluid inlet temperature (15–25 °C) on the battery temperature were investigated during the discharge period. The experiments revealed that maximum temperatures were reached at approximately 45 °C and 33 °C for air and distilled water cooling techniques, respectively, at the discharge rate of 4C. The average and maximum battery surface temperatures can be reduced by 28% and 25%, respectively, with the implementation of the liquid immersion technique at the discharge rate of 4C compared to the air technique. Moreover, the experiments demonstrated that the maximum temperature difference could be lowered to 4 °C by means of 100% liquid immersion cooling at the highest discharge rate, where they are approximately 11 °C and 12 °C for air and 50% for immersion cooling, respectively. In addition, it was observed that the coolant fluid inlet temperature has a significant impact on battery temperature for %100 liquid immersion. [ABSTRACT FROM AUTHOR]

Nanoencapsulated phase change materials (NePCMs) are promising thermal energy storage (TES) and heat transfer materials that show great potential in battery thermal management systems (BTMSs). In this work, nanocapsules with a paraffin core and silica shell were prepared using an optimized sol-gel method. The samples were characterized by different methods regarding chemical composition, thermal properties, etc. Then, the nanocapsules were used as the coolant by mixing with insulation oil in the immersion cooling of a simulative battery. The sample doped with Ag on the shell with a core-to-shell ratio of 1:1 showed the best performance. Compared to the sample without doping material, the thermal conductivity increased by 49%, while the supercooling degree was reduced by 35.6%. The average temperature of the simulative battery cooled by nanocapsule slurries decreased by up to 3.95 °C compared to the test performed with pure insulation oil as the coolant. These novel nanocapsules show great potential in the immersion cooling of a battery. [ABSTRACT FROM AUTHOR]

Refrigerant indirect contact phase-change cooling system flows refrigerant into a cold plate and utilizes the phase-change to exchange heat with the battery. However, R134a, commonly used, is being gradually restricted due to its environmental impact. A new kind of near azeotrope mixed refrigerant R1234yf/R152a (mass ratio 60.5:39.5) is proposed under environmental protection and safety. Based on the fluid-structure interaction model, the evaluation of different indirect contact phase-change cooling systems for battery thermal management (BTM) using R1234yf/R152a is investigated. After obtaining battery (150 Ah, 3.2 V LiFePO4) parameters, heat generation power, and main test conditions through experiments, the thermal properties are numerically studied by computational fluid dynamics (CFD). At 1 C discharge rate, the temperature gradient (TG) of single battery and the maximum temperature difference (TD) among batteries are analyzed for two cases: The maximum TD among batteries of Case_b is 6.5°C lower than that of Case_a. In addition, the effect of the mixed refrigerant and traditional liquid cooling on the battery temperature is studied at different evaporation temperatures (ETs) (20°C, 25°C) and different mass flow rates (MFRs) (0.02, 0.10, and 0.18 kg/s). The results show that both the increase of inlet MFR and the reduction of inlet ET may significantly improve the battery module cooling rate. Compared with 0.02 kg/s, as the MFR increases, the temperature drop slopes to 9.56 and 11.2 at 20°C. The battery module temperature uniformity is improved with the increase of ET. Overall, the mixed refrigerant has advantages in temperature uniformity and consistency. The new mixed refrigerant plays a positive role in controlling battery temperature. [ABSTRACT FROM AUTHOR]

The promotion of electric vehicles (EVs) is restricted due to their short cruising range. It is desirable to design an effective energy management strategy to improve their energy efficiency. Most existing work concerning energy management strategies focused on hybrids rather than the EVs. The work focusing on the energy management strategy for EVs mainly uses the traditional optimization strategies, thereby limiting the advantages of energy economy. To this end, a novel energy management strategy that considered the impact of battery thermal effects was proposed with the help of reinforcement learning. The main idea was to first analyze the energy flow path of EVs, further formulize the energy management as an optimization problem, and finally propose an online strategy based on reinforcement learning to obtain the optimal strategy. Additionally, extensive simulation results have demonstrated that our strategy reduces energy consumption by at least 27. 4% compared to the existing methods. [ABSTRACT FROM AUTHOR]

This work investigates on the performance of a hybrid energy storage system made of a metal hydride tank for hydrogen storage and a lithium-ion battery pack, specifically conceived to replace the conventional battery pack in a plug-in fuel cell electric scooter. The concept behind this solution is to take advantage of the endothermic hydrogen desorption in metal hydrides to provide cooling to the battery pack during operation. The analysis is conducted numerically by means of a finite element model developed in order to assess the thermal management capabilities of the proposed solution under realistic operating conditions. The results show that the hybrid energy storage system is effectively capable of passively controlling the temperature of the battery pack, while enhancing at the same time the on-board storage energy density. The maximum temperature rise experienced by the battery pack is around 12 °C when the thermal management is provided by the hydrogen desorption in metal hydrides, against a value above 30 °C obtained for the same case without thermal management. Moreover, the hybrid energy storage system provides the 16% of the total mass of hydrogen requested by the fuel cell stack during operation, which corresponds to a significant enhancement of the hydrogen storage capability on-board of the vehicle. • Hybrid energy storage system for plug-in fuel cell electric scooter • Numerical modelling of metal hydride tank integrated with battery pack • Passive, self-sustained thermal management of metal hydride tank and battery pack • Enhanced on-board energy density and improved vehicle driving range [ABSTRACT FROM AUTHOR]

Liquid fuel has been the main source of energy in internal combustion engines (ICE) for decades. However, lithium-ion batteries (LIB) have replaced ICE for environmentally friendly vehicles and reducing fossil fuel dependence. This paper focuses on the comparative analysis of battery thermal management system (BTMS) to maintain a working temperature in the range 15–35 °C and prevent thermal runaway and high temperature gradient, consequently increasing LIB lifecycle and performance. The proposed approach is to use biodiesel as the engine feed and coolant. A 3S2P LIB module is simulated using Ansys-Fluent CFD software tool. Four selective dielectric biodiesels are used as coolants, namely palm, karanja, jatropha, and mahua oils. In comparison to the conventional coolants in BTMS, mainly air and 3M Novec, biodiesel fuels have been proven as coolants to maintain LIB temperature within the optimum working range. For instance, the use of palm biodiesel can lightweight the BTMS by 43%, compared with 3M Novec, and likewise maintain BTMS performance. [ABSTRACT FROM AUTHOR]