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Excessive temperature of battery pack causes the performance degradation, affecting the normal operation and safety of the electric vehicles (EVs). This paper proposes an ant colony optimization-fuzzy sliding mode control (ACO-FSMC) hierarchical strategy for the battery thermal management system (BTMS) of EVs. Ignoring the dynamic process of the pump and compressor leads to the deviation of the cooling efficiency of EVs. Therefore, a control-oriented BTMS model is established to describe the temperature dynamics of battery pack and coolant, considering driving current effect on the speed of pump and compressor. Then, a hierarchical optimization strategy is designed to realize the control of the battery cooling rate as well as the speed of the pump and compressor. The upper layer of controller use an ant colony optimization (ACO) to solve the reference speed of the pump and compressor while satisfying constraints of physical characteristics of actuators, aiming at reducing battery temperature deviation and saving energy of BTMS. Considering the nonlinearity of lower layer of BTMS caused by the disturbance of time-varying load torque, fuzzy sliding mode control (FSMC) is applied to control the speed of pump and compressor, in which an integral sliding surface is designed to reduce the influence of disturbance. In order to weaken the chattering of sliding mode control and reduce energy consumption, fuzzy controller is used to adjust the reaching law parameters of sliding mode surface. The simulation results show that compared with PID, the maximum temperature deviation of ACO-FSMC is reduced by 43%, and the energy consumption is reduced by 23%. • A control-oriented battery thermal management model is established. • The dynamic process of the pump and compressor is considered. • ACO is used to solve the reference speed of the pump and compressor. • Fuzzy sliding mode control is applied to weaken the chattering of system. • The cooling performance and energy saving of the proposed method is verified. [Display omitted] [ABSTRACT FROM AUTHOR]

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]

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]

[Display omitted] • The thermal application of carbon nanotube from waste plastic was firstly studied. • The thermal conductivity of phase change composite material increased by 104%. • Latent heat capacity of phase change composite material retains 90.7%. • The produced carbon nanotube shows similar potential as commercial carbon nanotube. • This phase change nanocomposite is promising for battery thermal management. Carbon nanotube (CNT), has been demonstrated as a promising high-value product from thermal chemical conversion of waste plastics and securing new applications is an important prerequisite for large-scale production of CNT from waste-plastic recycling. In this study, CNT, produced from waste plastic through chemical vapor deposition (pCNT), was applied as a nanofiller in phase change material (PCM), affording pCNT-PCM composites. Compared with pure PCM, the addition of 5.0 wt% pCNT rendered the peak melting temperature increase by 1.3 ℃, latent heat retain by 90.7%, and thermal conductivity increase by 104%. The results of morphological analysis and leakage testing confirmed that pCNT has similar PCM encapsulation performance and shape stability to those of commercial CNT. The formation of uniform pCNT cluster networks allowed for a large CNT loading into the PCM on the premise of free phase change, responsible for the high thermal conductivity inside the homogeneous phase. Thus, the resulting capillary forces retained a high latent heat capacity and suitable melting temperature and prohibited PCM leakage from the matrix to the outside during re-melting as the pCNT loading ratio increased. Therefore, the as-prepared pCNT-PCM composite is believed to have similar potential to cCNT and shows prominent performance as a flowable conductive filler for battery thermal management systems. [ABSTRACT FROM AUTHOR]

Application of refrigerant-cooled multi-channel evaporators (MCEs) is a promising solution to cool electric vehicle batteries because the non-uniformly distributed heat from a battery can be efficiently dissipated by suitable arrangement of the multi-channels in an MCE. In order to provide a simulation tool for the design of an MCE, a distributed parameter model for quickly predicting the performance of an MCE at various channel arrangements and non-uniformly distributed heating conditions is useful, and thus it is developed in this study. In the model, heat and mass transfer in multiple flow paths in an MCE are separately described; the uneven mass flow distribution among these channels is predicted based on the pressure balance; each flow path is divided into multiple control volumes to reflect the non-uniformly distributed heating conditions; and the mass flow distribution among flow paths and the heat transfer in all the control volumes are jointly solved by a combined iteration algorithm of pressure drop and heat transfer. The proposed model is validated by experiments under the condition of battery heat flux ranging from 500 to 1500 W m−2. The results show that the prediction deviations of the average temperature and the highest temperature on the MCE surface from the experimental ones are 1.5 °C and 1.6 °C, respectively, which indicates that the proposed model can well predict the thermal performance of MCE under non-uniformly distributed battery heat. • A distributed parameter model of refrigerant-cooled MCE for power battery is developed. • Refrigerant flow among multi-channels is modeled as uneven flow with fix direction. • Arbitrary heat flux input can be calculated by the model. • The average deviation of temperature predictions is less than 3.0 °C. [ABSTRACT FROM AUTHOR]

The in-depth research on the heat exchanger for lithium-ion batteries is of significant importance due to its crucial role in ensuring the safe operation of electric vehicle (EV) power systems. To enhance the thermal and flow characteristic of the heat exchangers, the novel heat exchangers for 18650-cylinderical lithium-ion batteries have been proposed by topology optimization with the minimization of pressure drop and the lowest average temperature (∏ 1) and the minimization of pressure drop and the lowest temperature difference (∏ 2) as two different optimal goals. The topology optimization based on the variable density method is utilized to get two-dimensional (2D) optimal channels, and then the optimized results are extended to three-dimensional (3D) heat exchangers. The 3D heat exchangers are named TOHE-1 which is gotten by stretching the topology channels with ∏ 1 as optimal goal and TOHE-2 which is gotten by that with ∏ 2 as optimal goal. Subsequently, a detailed thermodynamic analysis is performed to assess the effect of the type of heat exchangers, channel heights, weight factor of topology optimization function, mass flow rates and discharge rates on the cooling effect of the batteries. The results show that compared with the traditional channel heat exchangers, the heat transfer coefficient of topological heat exchangers have increased by 49.92%, while reducing pressure drop by 27.81%. Meanwhile, compared to TOHE-1, heat transfer coefficient of TOHE-2 is increased by 9.70%, while pressure drop is saved by 4.70%. Other studies have indicated that for a 4 C discharge of the battery, a topological heat exchanger with a channel height of 1.5 mm, a thermal performance weight factor of 0.1, and a mass flow with 3.3 × 10−3 kg s−1 is the optimum heat dissipation scheme. Finally, the numerical studies are verified by conducting the convective heat transfer experimental tests. [Display omitted] • The topology optimization heat dissipation scheme for cylindrical lithium batteries is proposed. • The performance of topological heat exchangers is studied numerically and verified experimentally. • The performance of different functional types of topological heat exchangers is compared. • The ratio of heat dissipation scheme to battery weight is considered in cooling scheme design. [ABSTRACT FROM AUTHOR]

• Design for hybrid battery pack with high energy density and high safety. • Thermal Management Optimization Layout Design for Hybrid Battery Packs. • The P2D model is used to study electrochemical properties of single battery. • Multiphysics coupling analysis of electro-thermal behavior. • The SOC estimation method for hybrid battery pack. As traditional battery systems, lithium iron phosphate (LFP) batteries have better safety but lower energy density and nickel manganese cobalt oxide (NMC) batteries have higher energy density but poorer safety. In this work, we design a hybrid battery pack that has both higher energy density and higher battery safety. By analyzing the thermal properties of battery packs with aligned, staggered, and staggered arrangements, it can be concluded that the aligned arrangement has superior cooling efficiency and space-efficient optimization compared to the other arrangements, which have shorter flow paths to minimize air energy loss and reduce pressure drop. Notably, we design the optimal arrangement to avoid placing the NMC cells near the air outlet, to avoid NMC concentration, and to decentralize the LFP cells to reduce the relatively high maximum temperature and temperature difference. This hybrid battery pack is expected to give a boost to lithium-ion battery applications. [ABSTRACT FROM AUTHOR]

To maintain the optimal operating temperature range for the power batteries of new energy vehicles, this paper proposes a novel tree-structured channel cold plate. An orthogonal experimental approach was employed to investigate the effects of inlet flow rate m, inlet channel quantity n, channel width d, and hierarchy ratio α on battery temperatures T max , standard temperature difference T σ , and pressure drop Δ P. Non-dominated sorting genetic algorithm II (NSGA-II) was utilized to obtain an optimized solution set. The results reveal that the tree-like cold plate configuration including m = 15 g/s, n = 7 and 8, d = 3 mm, and α = 1:2:1 demonstrates superior performance. Thus, the developed cold plate was further compared with the conventional straight-through cold plate design. The results indicate that the proposed tree-like cold plate exhibits the maximum decreases of 13.94% in T max , 52.94% in T σ , and 61.5% in Δ P. The most significant improvement in the composite indicator PEC was 89%. In conclusion, the tree-like channel cold plate developed in this study provides excellent heat dissipation capability for power batteries, offering valuable insights for the thermal design of battery liquid cooling systems. [ABSTRACT FROM AUTHOR]

Electric autonomous underwater vehicles (AUVs) are facing more urgent battery thermal management (BTM) demands than electric cars, as their battery compartment design is constrained by limited volume, airtightness and impact loads. In this paper, a novel hybrid battery thermal management strategy of metal foam/paraffin composite combined with thermal bridges is proposed for the AUVs' BTM. A three-dimensional model considering the non-thermal equilibrium effect for AUVs' battery module was developed. Gradient PCMs and gradient foam porosity were introduced to improve the temperature and melting behaviors in various regions of AUVs' battery pack. The trade-off between performance and weight of metal foam/PCM composite on AUVs' battery thermal management was also quantitatively analyzed. The results showed that the temperature in the top region of the battery pack was higher than that in the bottom region due to the natural convection of the liquid PCM. The positive gradient porosity of metal foam has the advantages of large porosity increasing the heat storage and small porosity improving the thermal conductivity, both benefit to reduce the maximum temperature of the battery module. The positive gradient latent heat and melting point hybrid strategy of PCM demonstrates the best thermal management performance when compared with constant parameter cases, and the maximum temperature of battery modules is more sensitive to the melting point of PCM. When the metal foam/PCM composite was introduced, the weight of the battery module increased by 27.1%, while the maximum temperature and temperature difference of the battery module decreased by 44.27 K and 11.1 K, respectively. The safe working time of the battery module was extended by 105.7%, and the mass-energy density that can be utilized was increased by 61.9%. The findings can help AUVs to achieve the goals of high speed and long range. • The metal foam/paraffin composite was innovatively used for AUVs' BTM. • A 3D model was established considering non-thermal-equilibrium effect. • The thermal and melting behaviors of battery module were discussed in depth. • The performance of metal foam/paraffin with gradient parameters was compared. • The trade-off between performance and weight of metal foam/paraffin was evaluated. [ABSTRACT FROM AUTHOR]

An optimization workflow combining Latin hypercube sampling (LHS), surrogate models and multi-objective optimization is explored and applied to augment the effectiveness of a hexagonal mini-channelled cooling plate proposed previously in mitigating the overheating issues of 20Ah pouch batteries. Three design parameters are selected and deliberately randomized to explore a range of geometric configurations that might not be readily apparent through traditional intuition. Alongside, two thermo-fluidic parameters are varied with an optimization objective to minimize maximum battery temperature, pressure drop and enhance heat transfer performance simultaneously. Initially, 160 sample points are generated using LHS, followed by simulations conducted using COMSOL Multiphysics for a fixed discharge rate of 3C and an ambient temperature of 35 °C. Then, Multi linear regression, Response surface approximation, Support vector machine, and Kriging model are considered in search of the best surrogate. Results highlighted that the Kriging model could make predictions more accurately and is used further. Later, a Pareto analysis is performed using non-dominated sorting genetic algorithm II to generate 100 optimal solutions influencing the three conflicting objectives. Finally, the best compromise solutions are obtained using a K-means clustering algorithm and are numerically validated. The case with a side length of 18.99 mm, a channel width of 4.99 mm, a branching angle of 91.51° and a coolant temperature of 25 °C is ideal. This aided in reducing the pressure drop by 62.32% and enhancing heat transfer coefficient by 64.41%, with a minimal change in maximum temperature compared to that of the initial design under the same mass flow rate limit of 0.003 kg s−1. In addition, the SHapley Additive exPlanations technique is employed to unravel the design and operating variable's impact on the objective functions. Overall, the proposed framework could be a valuable contribution to optimizing the cooling channel design and potentially boosting the battery lifespan. [Display omitted] • Performed multi-objective optimization of hexagonal cold plate design for Li-ion battery. • Identified Kriging as the superior model with a higher R2 value for different cases. • Implemented NSGA II to get optimal design, forming a balance amid conflicting goals. • SHAP insights in assessing the feature impact in the machine learning prediction. [ABSTRACT FROM AUTHOR]

Efficient cooling during rapid battery charging/discharging necessitates forced circulating flow in immersion cooling systems. However, under forced flow immersion cooling (FFIC), the comprehensive impact on the electrical and thermal performance of battery modules remains inadequately explored. This study constructs an immersion-cooled battery module test platform for experimental research on the evolution of electrical and thermal characteristics. The results show that under FFIC, when the depth of discharge (DOD) during 2C and 3C discharges is below 85 %, the voltage deviation of module (δ U,t) remains stable within 1 % and 2 %, respectively. At DOD of 100 %, the maximum δ U,t for 2C and 3C are 10 % and 24.5 %, respectively. Furthermore, the analysis of Pearson correlation coefficient under FFIC reveals that the δ U,t exhibits a very strong positive correlation with temperature difference of battery module and cell, with correlation coefficients of +0.94 and + 0.87, respectively. Higher flow rates accelerate the recovery of module temperature and facilitate voltage distribution equalization after discharge. Additionally, to elucidate the influence of flow rate on FFIC, module-scale heat transfer characteristics during battery discharge are theoretically analyzed, establishing a fitting relationship between C-rates, flow rates, and the Nusselt number (Nu). This study provides a comprehensive understanding of integrated electro-thermal performance and external heat transfer capability for flow regulation in immersion cooling. [Display omitted] • Immersion-cooled battery platform was developed for electro-thermal performance. • Evolution of module electro-thermal performance was analyzed at varied Re and C-rates. • Interaction and strength between electrical and thermal parameters were revealed. • Heat transfer characteristics during discharging were theoretically analyzed. • The relationships between discharge C-rate, Re and Nu were established. [ABSTRACT FROM AUTHOR]

In advanced battery thermal management systems for electric vehicles, liquid cooling (LC) is typically coupled with a phase-change material (PCM) cooling for secondary heat dissipation. However, a continuous LC consumes a considerable amount of energy without considering the operating conditions. In this study, the thermal behaviors of tubular PCMs were examined under different liquid temperatures (25, 45, and 65 °C) to simulate the complex operating conditions of battery modules. In addition, a thermal management module coupling the PCM and copper pipe (CP) with LC was assembled to enhance the secondary heat dissipation of PCM cooling, particularly in a high-temperature environment. The experimental results confirmed the superior cooling effect of the PCM–CP module, even at high temperatures. Moreover, a dynamic LC (DLC) mode was proposed to reduce the energy consumption caused by LC, where LC operates intermittently. The effects of the LC activation time on the cooling behavior were explored. A coefficient illustrating the energy efficiency ratio (EER) was defined to evaluate the cooling performance and energy consumption of the two DLC modes with varying working times. The results proved that DLC-2 performed better than DLC-1 with E E R ¯ j values of 0.35 and 0.24, respectively. These results are expected to provide insights into the development of advanced energy-saving thermal management systems. [Display omitted] [ABSTRACT FROM AUTHOR]

• The heat generation model for cylindrical Li-ion battery was built. • A liquid immersion cooling battery pack containing 60 batteries were established. • At 2C discharge rate, 0.5 L/min flow rate was recommended. • The battery pack can address localized high-rate discharge events (4.5C or 6.5C). • Liquid immersion cooling BTMSs have great heat dissipation performance. With the increasingly severe challenges of the thermal management of battery packs for electric vehicles, the liquid immersion cooling technology has gradually attracted more attention due to its superior characteristics such as high heat dissipation efficiency, well temperature uniformity and low risk of thermal runaway. To investigate the heat transfer characteristics of the liquid immersion cooling BTMSs, the 3D model of the 60-cell immersion cooling battery pack was established, and a well-established heat generation model that leveraged parameters derived from theoretical analysis and experiments was incorporated into the 3D simulation to analyze the thermal characteristics of battery pack. The simulation results showed that under the discharging rate of 2C, even with the lowest coolant flow rate in this work (0.2 L/min), no localized abnormal overheating within the battery pack was observed, and the highest temperature was 34.22 °C. The temperature uniformity within the battery pack improved with the increase of the coolant flow rate. It was recommended to maintain a flow rate above 0.5 L/min to ensure a temperature difference below 5 °C. The experimental apparatus of the immersion cooling battery pack was also developed to explore the heat dissipation and temperature uniformity at 2C discharge rate. The simulation results were in well agreement with the experimental results, with the deviation less than 0.43 °C when the flow rate exceeded 0.6 L/min. The effect of the localized high-rate discharge events (4.5C and 6.5C) at different battery pack locations on temperature distribution and uniformity was further discussed based on the verified 3D model. The results suggested that liquid immersion cooling systems offered promising potential for achieving both efficient heat dissipation and preventing thermal runaway in battery packs. [ABSTRACT FROM AUTHOR]

The discharge performance of lithium-ion batteries (LIBs) is severely degraded at low temperatures. The existing LIBs preheating systems face challenges including high costs and consumption of battery capacity. Therefore, this paper developed an innovative electrically-controlled crystallization electrode based on calcium chloride hexahydrate (CCH) (ECE-CCH) by melting-solidification method and devised an electrically-controlled phase change material (PCM) preheating system based on CCH (EPS-CCH) for LIBs. The stable supercooling and great heat storage/release properties of the CCH, as well as the excellent low-voltage electrically-controlled crystallization performance of ECE-CCH, enable EPS-CCH to achieve safe and controllable thermal management of LIBs at the optimal operating temperature. Under the premise of maintaining the stable supercooling and heat storage properties of CCH (50.67 wt% CaCl 2 solution), 48 wt% CaCl 2 solution was selected as the heat storage material (melting point: 31.5 °C, latent heat: 153.0 J /g). The ECE-CCH could release the latent heat of the supercooled CCH solution in <5 s at low DC voltages (1.0–2.0 V). 100-cycle experiments illustrated that ECE-CCH had good cycle stability and an optimal operating voltage range of 1.0–1.5 V. Finally, EPS-CCH was designed to achieve on-demand control of thermal management of LIBs at low temperatures. Compared to LIBs without EPS-CCH at 5 °C, LIBs with EPS-CCH exhibited a significantly increased discharge capacity of 14.27%, 11.35%, and 7.04% at discharge rates of 0.5C, 1.0C, and 1.5C, respectively. The research findings of the ECE-CCH and the EPS-CCH would promote the development of LIBs preheating technologies. • A novel electrically-controlled electrode based on calcium chloride hexahydrate (CCH) was developed. • The crystallization of supercooled CCH was electrically triggered by 1.5 V DC voltage. • The crystallization behavior of supercooled CCH was investigated in-depth. • The EPS-CCH achieved a smart thermal management of lithium-ion batteries. [ABSTRACT FROM AUTHOR]

To address the bottleneck of easy leakage and low thermal conductivity of phase change materials (PCMs) for battery thermal management. Phase change composite (PCCs) with paraffin (PA) as the PCM, styrene ethylene butylene styrene (SEBS) as the supporting skeleton, and boron nitride (BN) as the thermally conductive filler were fabricated by the sacrificial template method. Compared with the composite prepared by melt-blending method, the thermal conductivity of PCC was improved by 27.6 % and the leakage rate was reduced by 82.4 % because the BN was rubbed with Na 2 SO 4 under the shear provided by internal mixer. As a result, the maximum temperature and maximum temperature difference of the battery pack with PCC cooling were 35.8 % and 62.5 % lower than those without PCC cooling at 2C discharge rate. In total, this work offers a strategy for improving the thermal conductivity and the leakage-proof ability of PCCs as well as for large-scale fabrication. [Display omitted] • The SEBS-BN@PA composites are prepared by the sacrificial template method. • The prepared composites have good leakage-proof ability and shape stability. • The composite has higher thermal conductivity than those prepared by melt-mixing method. • The composite presents excellent performances for battery thermal management. [ABSTRACT FROM AUTHOR]

To maintain the optimal battery performance, it is essential to develop an efficient battery thermal management system for keeping the battery operation temperature within the appropriate range. In this work, a novel design of cold plate featuring airfoil fin channel is developed as a highly effective cooling module of a prismatic LiFePO 4 battery pack. The thermal performance of battery and the thermo-hydraulic performance of the cooling module for the cold plate featuring airfoil fin channel, U-type channel and serpentine channel are numerically investigated and compared to reveal the superiority of the novel cold plate. The results indicate that compared with the U-type channel and the serpentine channel, the airfoil fin channel can enhance the total heat dissipation amount by 3.47% and 4.64%, respectively. Besides, the airfoil fin channel can provide the smallest battery maximum temperature and temperature difference under the same coolant flow rate. The airfoil fin channel provides the smallest pressure loss and heat transfer coefficient but the largest overall thermo-hydraulic performance indictor in terms of j / f factor. Under the same requirement of battery cooling performance, the remarkably smaller power consumption is required for the airfoil fin channel compared with the U-type channel and serpentine channel. • A novel cold plate with airfoil fins is designed for cooling battery. • Performance of airfoil fin cold plate and two conventional cold plates is compared. • Airfoil fin cold plate is of the largest heat dissipation capacity. • Airfoil fin cold plate is of the best overall performance. [ABSTRACT FROM AUTHOR]

Efforts to mitigate environmental pollution from the use of petroleum-based energy sources have promoted research on rechargeable secondary batteries for applications such as electric vehicles and energy storage systems. In this context, Li-ion batteries have attracted significant interest. Notably, the thermal management of such batteries is crucial for achieving a stable output and long lifespan and reducing the risk of thermal runaway. Despite extensive exploration of various cooling schemes, thermal management techniques for Li-ion batteries continue to face challenges due to the high thermal resistance resulting from low thermal conductivity of thermal interfacial materials and inadequate convective heat transfer. Therefore, this study is aimed at using laser-induced graphene (LIG) to enhance the heat transfer characteristics and battery thermal management. LIG is applied through direct laser irradiation on the polyimide substrate of a LiFePO 4 battery. Thermal tests conducted under a discharge rate of 5C demonstrate that immersion cooling using HFE-7000 on the LIG surface substantially reduces the temperature increase by up to 84.3% compared with conventional air cooling. In addition, immersion cooling with LIG surfaces results in outstanding cooling performance through nucleate boiling, attaining a maximum temperature of 37.5 °C, which is lower than that (43.5 °C) on a pristine polyimide surface. Overall, this research provides valuable insights into the thermal management of high-performance batteries operating under extreme conditions, such as high-speed charging, high-power discharging, and high-temperature conditions, with significant implications for future applications. • Introducing laser-induced graphene (LIG) for novel immersion, boiling cooling. • Various aspects of battery behavior were investigated, including discharge rates, working fluids, and temperatures. • LIG-coated battery enhances thermal performance, especially in high-temperature and high C-rate conditions. • LIG-coated battery exhibited a remarkable temperature reduction of up to 84.3%. [ABSTRACT FROM AUTHOR]

In recent years, there has been a growing demand for electrical vehicles, which are more energy efficient and environmentally friendly than their traditional counterpart. One of the crucial aspects of electrical systems is energy storage. A promising option for energy storage is Lithium-ion batteries (LIBs) due to their high energy density, longer life cycles, and faster charging when compared to other batteries. The disadvantage of employing LIBs is that they are more difficult to maintain because they are more prone to failure, and they are greatly dependent on the system's thermal behavior, which has led to an emphasis in research on battery thermal management systems (BTMSs). The BTMS aims to address this issue by limiting the temperature fluctuation of the battery cells to maintain the average temperature within recommended limits throughout the charging and discharging processes. There has been a continuous interest in nanofluids and phase change materials (PCMs) because of their unique properties and their potential thermal application as a cooling medium for high-density batteries. Recent studies have aimed to use different active and passive methods with varying materials and cooling system geometries to achieve the highest possible thermal performance. The current review aims to outline the recent studies on thermal management systems for LIBs. Three main sections have been presented in this paper. The first section reviewed studies on nanofluids in different BTMSs, the other one highlighted techniques adopted to overcome the low thermal conductivity drawback in PCMs for BTMs, and the last one focuses on the effects of combining both cooling approaches. We believe that the present review paper provides useful information that could be a significant step toward developing high-performance BTMS. • A summary of the most recent research on BTMS of LIBs. • Nanofluids and PCM-based BTMS attract significant interest in LIBs. • PCM with carbon additives enhance LIB pack temperature uniformity. • Incorporation of fins has demonstrated effectiveness in improving BTMS performance. • Metal foams with PCMs enhance BTMS performance via improved thermal conductivity. [ABSTRACT FROM AUTHOR]

The demand for high energy density in lithium-ion battery packs for electric vehicles poses a challenge to maintaining its optimum operating temperature while reducing the risk of thermal runaway (TR) propagation. This study proposes a novel hybrid TR propagation mitigation system that balances heat transfer and thermal insulation requirements using low and high thermal conductivity phase change materials (PCM), heat pipes (HP), and air-cooling. The design and optimization of such a mitigation system are complex due to the many design parameters involved. The Adaptive-Kriging-High dimensional model representation (Adaptive-Kriging-HDMR) is used to establish a surrogate model of the system, and the sensitivity of the system's design parameters is evaluated with the maximum battery temperature and the system weight as the targets, thereby improving the efficiency of model calculation and reducing the dimension of optimization parameters. Then, the design of the sensitive parameters is optimized using an extended elitist non‐dominated sorting genetic algorithm (E-NSGA-II) multi-objective optimization algorithm. The results show that the modeling difficulty and optimization calculation time are significantly reduced by using a surrogate model. The calculation time for a single surrogate model only takes a few seconds instead of several hours for the original three-dimensional heat transfer and flow calculation. The thermal conductivity of high thermal conductivity-PCM, the distance between battery and low thermal conductivity-PCM, the battery spacing, and the HP length significantly affect the system. The optimized system substantially reduces the overall weight of the battery system while ensuring its good heat dissipation capability. In the case of TR in a single battery, the system succeeds in limiting the TR propagation to the same row, with the maximum battery temperature in the second row being only 64.3 °C, well below the battery TR trigger point. Under more severe conditions, such as TR occurring in two batteries simultaneously, the maximum battery temperature in the second row is 155.5 °C, and no TR spreads to the adjacent row. This study provides a rapid and effective method for designing a TR propagation mitigation system. It can serve as a reference for the engineering design and optimization of battery thermal management systems. [ABSTRACT FROM AUTHOR]

Phase change material (PCM) is widely adopted to construct integrated battery thermal management systems (BTMSs) for all climates. However, integrated BTMSs in cylindrical battery modules remain arduous challenges due to the compact/massive cuboid-shaped PCM module and the curved surface of the cells. Herein, we propose a novel all-climate BTMS integrating units-assembled composite PCM (CPCM) module with force air convection. The CPCM module assembled by sleeve-like CPCM units provides developed airflow channels and enlarged heat transfer surface from 1.17 × 10−3 to 3.63 × 10−3 m2 for enhancing convective heat transfer. Consequently, compared to conventional cuboid-shaped module, the thermal resistance of the units-assembled module is remarkably reduced by 52.0% and 60.1%, and the heat flux is enhanced by 7 times under both cooling and preheating modes. In cooling tests, this BTMS demonstrates superior performance by controlling the temperature and temperature difference below 40.30 and 2.80 °C at 3-C discharge, respectively. In preheating tests, it effectively preheats the battery module from 0 to 10 °C in 302 s with a low temperature difference of 3.82 °C. Furthermore, this units-assembled CPCM module saves 53.8 wt% of the CPCM dosage, and thus the energy density of the battery module is increased from 75.6 to 94.4 Wh·kg−1. • All-climate BTMS integrates units-assembled CPCM module with force air convection. • Units-assembled CPCM module provides developed internal structure for heat transfer. • Thermal resistance of CPCM module is reduced, and heat flux is enhanced by 7 times. • BTMS shows superior cooling, preheating and heat-preservation performances. • BTMS reduces CPCM module weight, increasing the energy density of battery module. [ABSTRACT FROM AUTHOR]

The introduction of a high-thermal-conductivity porous medium stands as an effective strategy for enhancing the heat transfer rate within battery thermal management using phase change material (PCM). In this study, we have delved into the investigation of heat transfer augmentation in battery thermal management through the implementation of toroidal porous medium. The exploration encompasses the effects of Rayleigh numbers, thicknesses of the toroidal porous medium, different kinds of porous medium and PCM. By comparing the liquid fraction, dynamic temperature and the latent heat ratio, we found the effect of Rayleigh number and thickness of porous medium on the property of the battery thermal management. The results indicate that by applying thicker toroidal porous medium could weaken the heat accumulation derived by high Rayleigh numbers. Case of d = 0.273R exhibits superior performance for a significant portion of the entire process compared to other cases with thickness of 0.235R, 0.326R, 0.408R and uniform distributed, while the dominant position is difficult to hold due to the heat accumulation. The conclusion is universal for different porous medium and PCM materials. The optimal distribution of porous medium should seek a balance between enhancing heat conduction and weakening thermal convection. A more scattered distributed porous medium could weaken the effect of heat convection and rises the latent heat ratio. [ABSTRACT FROM AUTHOR]

The performance of the battery is affected by temperature, and the battery thermal management (BTM) system consumes considerable energy to maintain the temperature in the suitable range. The unnecessary acceleration and deceleration of electric vehicles (EVs) during driving causes higher energy consumption in the powertrain. The emergence of connected and automated vehicle (CAV) technology provides an opportunity for predictive control of thermal and energy management. To explore the coordination optimization between battery thermal and vehicle energy management, this article proposes a two-level optimization framework for the speed and BTM of EVs, which improves energy efficiency and battery safety. Each level consists of a sequential optimization of speed and battery thermal. In the upper layer, speed planning based on iterative dynamic programming (IDP) is first proposed to reduce powertrain energy consumption using intelligent traffic information. Then, based on the BTM system and the battery thermodynamics features, the long-term optimal trajectory of the battery temperature is derived according to optimized speed. In the lower layer, the model predictive controllers (MPC) are designed to track reference speed and temperature trajectories in real-time and enforce energy saving. Meanwhile, to improve the prediction accuracy of the system model, we integrate the Gaussian process (GP) model in the MPC and build the learning-based MPC strategy. Simulation results verify the performance of the proposed method which reduces the powertrain energy consumption by 20.95%. In the high and low temperature environment, compared with normal MPC, PID-based and Rule-based, it reduces BTM energy consumption by up to 15.69%, 29.68% and 38.73%. [Display omitted] • A two-level optimization strategy is proposed for speed and thermal management. • Global reference trajectory of speed and battery temperature for connected and automated vehicle is planned. • Speed following and temperature tracking based on model predictive control are realized. • The Gaussian process model is integrated into the model predictive control to improve the estimation accuracy. [ABSTRACT FROM AUTHOR]

The use of a hybrid cooling system, which combines phase change material (PCM) and liquid channels, has been extensively researched to mitigate the risk of battery thermal runaway. However, the existing studies on hybrid cooling systems have overlooked the impact of buoyancy-driven natural convection in PCM. This results in a uniform flow rate allocation among liquid channels, leading to inadequate heat dissipation performance. To this end, this paper proposed a prediction-informed adaptive flow rate allocation strategy for the hybrid cooling system considering natural convection in PCM. First, a novel thermal runaway model was developed, followed by a PCM model that considers natural convection. Then, the proposed strategy utilized Bi-directional Long Short-Term Memory (Bi-LSTM) to predict the outlet temperature, which represents the cooling demand. The flow rate was regulated based on the predicted temperature to avoid an initial flow rate of 0 in the liquid channel and achieve a timely response. The results showed that the proposed strategy extended the thermal runaway propagation interval by 60.6% (85.9 s) and reduced the total flow rate by 31.7%. This strategy significantly enhanced the hybrid cooling system's performance, without increasing the parasitic energy or reducing the battery pack's energy density. • Prediction-informed strategy to enhance hybrid cooling systems' performance. • Adaptive flow rate regulation for hybrid cooling systems considering natural convection. • Novel coupled electrochemical–thermal model for thermal runaway analysis. [ABSTRACT FROM AUTHOR]

This study introduces a streamlined modeling framework that integrates a volume-averaged thermal (VAT) model with the Tank-in-Series battery model, a recently developed volume-averaged electrochemical model. The framework enables efficient simulations of electrochemical-thermal interactions in large-scale battery packs. This framework is used to investigate the effects of coolant flow rates and inlet temperature, initial and ambient temperatures, battery pack configurations, and cell-to-cell manufacturing related variations. Results showed a notable current distribution variation among modules connected in parallel at the end of discharge and beginning of charge. This is found to be directly related to the temperature variation in the battery pack governed by the coolant mass flow rate. Additionally, with the introduction of a 0.5% cell-to-cell to variation in the cell design parameters for the purpose of simulating manufacturing variation, a significant voltage variation of over 0.2 V across cells is found to be possible. Furthermore, rapidly changing the inlet temperatures to simulate a potential battery management system failure indicated the risk of some cells in the pack exceeding the desired cut-off voltage. The present framework can be used to design battery packs with effective thermal management strategies, enhancing the overall reliability and performance of battery systems. • Developed a multiphysics modeling framework to simulate electrochemical-thermal characteristics of Li-ion battery packs • Flexible, scalable, and efficient physics-based simulation of Li-ion battery packs • In-depth analysis of Li-ion battery pack at various operating conditions, including extreme thermal conditions • Effect of cell-to-cell manufacturing variation on cell-level and pack-level electrochemical and thermal characteristics [ABSTRACT FROM AUTHOR]

To ensure the optimal operating temperature of lithium-ion batteries, a novel thermoelectric-based battery thermal management system coupled with water cooling and air cooling is proposed in this work. Also, a hydraulic-thermal-electric multiphysics model is established to assess the system's thermal behavior. Through numerical simulations, the effect of different cooling parameters, including TEC (thermoelectric cooler) input current, air convection heat transfer coefficient, and cooling water flow rate on thermal performance is comprehensively analyzed. The results show that the introduction of thermoelectric cooling into battery thermal management can amplify the cooling ability of traditional air cooling and water cooling, and the cooling power and COP (coefficient of performance) of thermoelectric coolers first increase and then decrease with the increase of input current. Under the air convection heat transfer coefficient of 50 W m−2 K−1, water flow rate of 0.11 m/s, and TEC input current of 5 A, the battery thermal management system reaches the optimal thermal performance, corresponding to the maximum temperature and temperature difference of 302.27 K and 3.63 K respectively. However, the cooling parameters of these three factors interact with each other, and it is vital to select appropriate cooling parameters to balance the thermal performance and energy consumption of the battery thermal management system. More importantly, this work provides a brand-new idea for the thermal management of batteries. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface modification of hBN was carried out, making hBN more compatible with matrix. • FPCMs with excellent overall performance have been prepared. • Induced SBS/LDPE cross-linking improves the high-temperature resistance of FPCMs. • FPCMs show much better battery thermal management performance. In battery thermal management (BTM), flexible phase change materials (FPCMs) emerge as highly promising substances, owing to their simple installment and low contact thermal resistance. However, FPCMs based on high thermal conductivity fillers and polymers always suffer from the enduring challenges of poor high-temperature resistance and poor filler-matrix compatibility. To solve these problems, a novel strategy is reported in this work, wherein FPCMs with excellent filler-matrix compatibility and satisfactory high-temperature resistance are synthesized by two steps: functionalizing the hexagonal boron nitride (hBN) surface and inducing the inter crosslinking between Styrene-Butadiene-Styrene(SBS) and Low-density polyethylene(LDPE). Vinyltrimethoxysilane (VTMS) molecules were introduced on the surface of raw hBN by hydroxylation and silanization surface modification to improve the compatibility of hBN with the matrix. Concluding from the results, the addition of 6.7 wt% LDPE doubled the high-temperature resistance of FPCMs, enabling them to maintain their structural integrity even at 200 °C for 1 h. The prepared FPCMs also exhibited higher thermal conductivity (increased by 20.5 %), low leakage rate (<0.6 wt% after 70 heating–cooling cycles), high enthalpy (122 J g−1), and strong adhesion (>0.1 MPa), etc. In terms of BTM performance, the FPCMs-based passive cooling BTM presents remarkable temperature control capabilities (maximum temperature reduction by 16.3 ℃) and uniform temperature performance (maximum temperature difference < 2.5 ℃). Collectively, this work will provide a promising approach for the fabrication of high-performance FPCMs in BTM and other thermal management applications for electronic devices. [ABSTRACT FROM AUTHOR]

• Developed and analyzed a novel hybrid battery pack thermal management system. • Incorporated a novel three-stage cooling strategy into the thermal management system. • Latent heat of PCM effectively extracts heat from the cylindrical Li-ion cells. • Secondary coolants increase the overall heat transfer coefficient of PCM. This paper introduces a novel hybrid thermal management concept, which use secondary coolants (air and water) to extract heat from a phase change material (paraffin), resulting in increased heat extraction capability of the paraffin and improvement the overall thermal performance of the battery module. This concept was analyzed using experimental and numerical studies. The experimental studies were conducted to obtain the temperature and heat flux profiles of the battery module. The numerical model is developed and validated using the experimental data obtained. The outcome of the study showed that the battery module temperature reached the phase change temperature threshold of the PCM in the fifth discharge cycle, and the through the use of latent heat the battery module temperature was maintained between 42 and 44 °C. Additionally, the thermal uniformity started to increase once the PCM started to change and the PCM utilization was ∼2.3 % after seven discharge cycles. Therefore, the proposed thermal management concept for the battery module can sustain the thermal environment needed for effective operation of the Lithium-ion batteries. [ABSTRACT FROM AUTHOR]

• The coupled BTMS with PCMs and cold plates is designed for performance improvement. • Aerogel is used to replace the unmelted PCMs for weight reduction. • A strategy is developed to optimize the distribution of PCMs/Aerogel. • T max and Δ T are reduced by 1 K and 49 % respectively after the optimization. • The weight of PCMs/Aerogel is reduced by 45 % after the optimization. The thermal management system is critical for battery packs in electrical vehicles. Coupling the battery thermal management system (BTMS) with phase change materials (PCMs) and cold plates (CPs) has demonstrated good cooling performance. However, part of the PCMs inside the existing systems doesn't experience phase change, which contribute less to the cooling performance as the weight load increases. In this study, aerogel as the typical lightweight flame retardant materials (FRMs) is adopted to replace the un-melted PCMs to reduce the weight of the system. An optimization strategy for the distribution of PCMs/FRMs in the coupled BTMS is proposed to improve the cooling performance with the system's volume fixed. By locating PCMs on the high-temperature area, an optimized system can be obtained by taking just a few adjusting steps using the developed strategy. After the optimization, the maximum temperature and temperature difference inside the battery pack are reduced by1.0 K and 49% respectively, with the weight of the filling materials among battery cells decreasing by 45%. The proposed strategy shows great potential for efficient optimization of coupled BTMSs with phase change materials and cold plates, which can improve the cooling and lightweight performance of the system simultaneously. [ABSTRACT FROM AUTHOR]

In the work, a composite cooling system coupled with PCM (phase change material) and liquid cooling was designed. The influence of parameters such as spacing, EG (expanded graphite) content, battery direction, coolant flow rate and pipe diameter on the cooling performance was analyzed. The results revealed that: (1) The increase of spacing makes the temperature of the pack decrease, but the effect degree of increasing the spacing on temperature performance decreases when the spacing exceeds 14 mm. At the same time, CPCM formed by the added high thermal conductivity material expanded graphite and paraffin can effectively improve the temperature control performance of the pack, which can control the temperature at 313.15K under the condition of an ambient temperature of 308.15K (2) By comparing the maximum temperature and the temperature difference of the pack under different discharge methods, it is concluded that the poles facing inward can reduce the accumulation of the interior heat. (3) The convective heat transfer coefficient and Nu number of the pack are increasing as the flow rate increases, but the slope of the temperature versus flow rate decreasing slowly. After increasing the inlet size, the inner wall surface area of the pipe increases and the average convective heat transfer coefficient of the pack reduces. However, the Nu number increases with the increase of the pipe diameter, indicating that the growth of the pipe diameter can enhance the heat transfer rate. (4) Orthogonal experiment and fuzzy correlation analysis were combined to analyze the parameters that affect the thermal performance of the BTMS. It was determined that using a proper coolant flow rate can maximize the thermal performance of the pack. • A composite cooling system coupled with PCM and liquid cooling is designed. • Influences of the key parameters on the cooling performance are analyzed. • Orthogonal experiment and fuzzy correlation analysis are used to analyze affecting parameters. • Some results for enhancing cooling performance are obtained. [ABSTRACT FROM AUTHOR]

• Refrigeration system with evaporator mini-channel structure was developed for power batteries. • The effects of refrigerant charge, OTV and heating power were examined. • For OTV from 41.9% to 79.1%, the heat transfer coefficient first increases and then decreases slightly. • Temperature of battery module with heating power of 100 W-200 W can be restrained within 10.8°C -45.7°C by adjusting OTV. The vapor compression refrigeration system possesses excellent thermal performance owing to two phase boiling with large latent heat, which can be a promising option for refrigerant cooling of battery modules. In this work, the battery thermal management equipped with a small-scale refrigeration system was built up, which primarily consisted of the mini-channel evaporator directly mounted with a battery module, compressor, throttle valve and fan-cooled condenser. The influencing factors such as the refrigerant charge, openness of throttling valve (OTV) and the heating power were examined experimentally. It is found that, with the increase in the refrigerant charge, the system coefficient of performance (COP) first increased and then decreased. When the heating power is between 100 W to 200 W, the temperature of the battery module could be controlled in a suitable range, namely 10°C-45°C, by adjusting the OTV within the range of 48.8%-72.1%. As the OTV increased, the heat transfer coefficient of the mini-channels first increased and then levelled off. As the heat power increased, the heat transfer coefficient of the mini-channels first increased and then decreased. The present study helps better understanding of thermal management using the vapor compression refrigeration system in the battery thermal management. [ABSTRACT FROM AUTHOR]

The era of electric mobility has started, and petrol/diesel vehicles are being replaced by electric vehicles (EVs). The phase change material (PCM) is a trending field of research in its application of energy storage and thermal management. PCM-based thermal management method is found to be quite simple and effective for battery packs. However, its commercialization is difficult due to its low thermal conductivity and extra weight addition to the battery pack. Hence, the present research focuses on the battery performance with PCM. The experimental setup for a 48V, 25Ah battery pack is developed, and its performance is explored with and without PCM. The numerical model for same sized battery pack is developed, and validated with experimental results. The major objective of the present research is to find the optimal gap between two battery cells so that a sufficient amount of PCM can be filled inside the battery pack. Initially, inline and staggered cell arrangements are examined, and no significant difference in thermal performance is found. Further, cell spacing of 5 mm, 3 mm, and 1 mm are examined, and maximum temperature and temperature difference are compared along with the weight and volume of the battery pack. For a single charging process, 1 mm cell spacing is found sufficient, considering the weight of the battery pack and thermal performance. However, with 1 mm cell spacing, temperature increases significantly after each charging and discharging. At the same time, 3 mm and 5 mm are found as feasible solutions considering single and double charging-discharging cycles, respectively. 3 mm cell spacing is better option when weight is a critical issue, while 5 mm cell spacing is better when thermal performance is a critical issue. The current study offers guidance in the advancement of battery packs, particularly in cases where space constraints are a concern. • The research focuses on utilization of optimal amount of PCM. • The battery charging experiments are carried out on 48V, 25Ah battery pack. • PCM OM42 reduced battery temperature by 18 %. • The inline and staggered arrangements are found equally effective. • 3 mm cell spacing is found sufficient with limited weight increment. [ABSTRACT FROM AUTHOR]

• High-stable CPCM for battery thermal management is prepared via one-pot strategy. • 3D nano-framework is in-situ constructed to obtain high shape stability of CPCM. • Nano-framework stacks into a developed mesoporous structure to suppress leakage. • The obtained CPCM shows outstanding cooling performance for the battery module. • No leakage trace is detected on the battery module during accelerated aging tests. Mainstream phase change material (PCM) for the thermal management of battery modules has been suffering from the leakage issue due to the weak capillary condensation from its micron-scaled polymer framework. Therefore, in this work, we design a high-stable and leakage-proof composite PCM (CPCM) by in-situ constructing a nano-scaled resorcinol-furfural polymer framework (RF-PF) in PCM via a one-pot strategy. Compared to classical micron-scaled framework of epoxy resin, the nano-scaled RF-PF stacks into a three-dimensionally mesoporous structure, and thus provides a much more intensive adsorbability towards PCM to prevent leakage. The mass retention rate of the RF-PF-based CPCM (RF-CPCM) during the leakage tests is up to 99.84 wt%. Combining with the suitable thermo-physical properties including a phase change enthalpy of 107.18 J g−1, phase change temperature region of 40– ∼ 55 °C and thermal conductivity of 1.58 W m−1 K−1, the RF-CPCM demonstrates effective and stable thermal management performances towards the pouch and cylindrical battery modules. For example, the temperature of the pouch battery module can be controlled below 41.15, 44.16 and 46.82 °C during 0.5-C, 1-C and 2-C discharges, respectively. During the accelerated aging test, the leakage trace appearing on the traditional CPCM module, is effectively overcome in the RF-CPCM module. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are the most commonly used battery type in commercial electric vehicles due to their high energy densities and ability to be repeatedly charged and discharged over many cycles. In order to maximize the efficiency of a li-ion battery pack, a stable temperature range between 15 °C to 35 °C must be maintained. As such, a reliable and robust battery thermal management system is needed to dissipate heat and regulate the li-ion battery pack's temperature. This paper reviews how heat is generated across a li-ion cell as well as the current research work being done on the four main battery thermal management types which include air-cooled, liquid-cooled, phase change material based and thermo-electric based systems. Additionally, the strengths and weaknesses of each battery thermal management type is reviewed in this study. It was determined that air cooled systems are suited for short-distance travel electric vehicles, liquid cooled are for electric vehicles that require long-distance travel, larger battery packs and for high thermal loads, phase change material based are for electric vehicles with constant thermal loads and stable ambient temperatures and thermo-electric battery thermal management systems are best best suited in conjunction with the other types for better control. • Present simplified heat generation model for li-Ion batteries. • Review of upcoming PCM Cooling BMS models. • Analysis of strengths and weaknesses of air, liquid, PCM, and thermoelectric BMS. • Recommendation on appropriate BTMS type for different EV models. • Identified main attributes required for an effective BMS for EV systems. [ABSTRACT FROM AUTHOR]

A powerful thermal management scheme is the key to realizing the extremely fast charging of battery electric vehicles. In this scheme, a water-cooled plate is set at the bottom of the battery modules, which has a remarkable heat dissipation ability but increases the temperature difference between the top and bottom of the battery. This temperature difference problem is more obvious during the high-rate charge/discharge process; in particular, in the area of battery tabs, which are usually located far from the cooling plate, heat accumulates, risking thermal runaway. To address this problem, a thermal management method based on an ultrathin vapour chamber (UTVC) is proposed in this paper to improve temperature uniformity and reduce the highest temperature of batteries. According to the number of applied UTVCs, a unilateral UTVC (U-UTVC) and a bilateral UTVC (B-UTVC) cooling approach were presented, the effectiveness of which was verified by a set of thermal performance experiments. The test data show that the temperature differences in the batteries under the U-UTVC and B-UTVC schemes are 39.77% and 73.54% lower than those under the traditional method at a 25 °C ambient temperature and a 1.39C charge rate, respectively. The temperature difference on the battery surface with the B-UTVC scheme is approximately 3 °C at 25 °C and 40 °C ambient temperature. • An ultra-thin vapour chamber-based power battery thermal management is proposed to improve the temperature uniformity. • The methods have limited effect on battery volumetric specific energy, and the volumetric specific energy of battery is only reduced by 1.2% which is far less than reported investigations. • Temperature difference and maximum temperature of battery module of the presented scheme are reduced by 15.49% and 73.54%, respectively. [ABSTRACT FROM AUTHOR]

To enhance the cooling and preheating performance of the battery, a novel hybrid battery thermal management system (BTMS) containing bionic spiral fins wrapped with phase change material (PCM) and embedded liquid cooling is proposed. The cylindrical battery is strategically positioned on a spiral fin, the heat of the battery and PCM is transferred to the cold plate through the extended winglets. The thickness (L 1), height (L 2), distance (L 3) and number of winding turns (N) of fin are optimized using the response surface method (RSM). The effects of the liquid cooling duration, flow rate, channel shape and direction of the flow channel on the latent heat recovery of PCM and the cooling performance of the battery module are analyzed. The results demonstrated that at the duration of 600 s and flow rate of 0.09 g/s, the liquid fraction of PCM reduced from 57 % to 26 %. Furthermore, the preheating efficiency of the BTMS was investigated under different parameter configuration and boundary conditions. The preheating temperature increased by 5.6 °C compared with the BTMS without fins. Additionally, the temperature difference (ΔT) of the BTMS with Layout 2 decreases by 0.5 °C compared with 4.1 °C of Layout 1 at flow rate of 0.5 g/s. [ABSTRACT FROM AUTHOR]

Pursuing high cooling-preheating performances of integrated battery thermal management system (BTMS) inevitably complicates the module structure, leading to great decreases in energy densities. To unblock this trade-off relationship, we propose a compact and lightweight integrated-BTMS by introducing bi-functional heating-cooling plates (BF-HCPs) and temperature-equalizing strategies based on differentiated inlet velocities (v I and v II) and heating powers (P I and P II). Firstly, the skillful design of BF-HCPs simplifies the structure of BTMS by reducing individual heating/cooling accessories. Subsequently, multi-objective optimization of v I , v II , P I , P II and channel width ratio (WR) realizes temperature equalization in large modules. The optimal WR locates at 0.60–0.65; differentiated v I and v II is fixed at large values of 0.25 and 0.16 m·s−1, respectively; the total P I + P II is preferably larger than 695 W with a narrow P II / P I of 0.53–0.56. Consequently, the obtained BTMSs demonstrate outstanding comprehensive performances. In cooling mode, the maximum temperature and temperature difference can be controlled below 30 and 3 °C at 4-C discharge. In preheating mode, the preheating time is lower than 500 s with a temperature difference < 3 °C. Furthermore, the obtained battery module possesses higher energy densities of 143.6 Wh·kg−1 and 332.2 Wh·L−1 than the reported battery modules with existing integrated BTMSs. [ABSTRACT FROM AUTHOR]

The phase change immigration of flame retardant Composite Phase Change Material (CPCM), especially the temperature aging effect during multicycle process, greatly restricted its application in power battery pack of electric vehicle and energy storage system. In this study, the properties of flexible flame-retardant CPCMs before and after temperature aging were investigated, and the battery thermal management effects of battery modules were compared. The results revealed that flexible CPCMs with styrene block copolymers exhibited little volume change owing to their elastic and anti-leakage properties, effectively alleviating flow and agglomeration. In addition, battery modules with flexible flame-retardant CPCMs exhibited prominent battery thermal management. These mechanisms in flame-retardant CPCMs can profoundly affect the design and preparation of multifunction CPCMs, providing novel insights into passive thermal management of battery systems. [ABSTRACT FROM AUTHOR]

For cylindrical Li-ion battery packs, the battery thermal management system can be properly designed and analyzed from an energy-exergy viewpoint during charging and discharging to ensure the proper functionality of batteries; however, not been explored yet. Hence, cylindrical Li-ion battery pack with novel-designed serpentine microchannel-cooled thermal management system are analyzed. Applying the Multi-Scale Multi-Domain Newman, Tiedemann, Gu, and Kim model, an electrochemical model is used for the 3D battery thermal modeling. Effects of circular and rectangular cross-sectional shaped microchannels and using ternary hybrid nanofluids [THNF1 (Al 2 O 3 (0.5%) + Cu (0.5%) + MWCNT (1%)/water) and THNF2 (Al 2 O 3 (0.5%) + Cu (0.5%) + Graphene (1%)/water] are investigated at a 3C-discharge rate. Results indicate that the use of ternary hybrid nanofluid and microchannel cross-sectional shape has a strong influence. Maximum temperature, temperature uniformity, pumping power, heat transfer coefficient to pressure drop ratio, and entropy generation are the key factors. The present simulation can predict individual battery thermal behavior during charging and discharging. The suggested design successfully lowers the cell temperature to 305.24 K by using THNF2 and the temperature difference to 5.23 K of the 26,650-type cylindrical cell. Rectangular cross-sectioned microchannel is found to be more effective. The thermal control of batteries is greatly enhanced by using ternary hybrid nanofluid. The suggested technique will improve the battery life. • Novel serpentine microchannel-cooled system is proposed for cylindrical battery pack. • Multi-Scale Multi-Domain Newman, Tiedemann, Gu and Kim model is used for battery. • Different microchannel cross-sections and ternary hybrid nanofluids are investigated. • Thermal performance parameters, pressure drop and entropy generation are evaluated. • Suggested design and fluid successfully keep cell temperature within desired range. [ABSTRACT FROM AUTHOR]

Improper battery temperature will lead to reduced battery discharge efficiency and electric vehicle driving range. Endeavors to find an efficient and precise battery temperature control method for the transcritical CO 2 thermal management system of electric vehicles, two evaporation temperature control methods for battery cooling were proposed. First, the effects of the control methods on battery temperature, optimal discharge pressure and coefficient of performance (COP) were simulated under typical operating conditions. Subsequently, a comparative simulation was conducted on the battery temperatures and COP of the two control methods under full cooling conditions. The results revealed that equal evaporation temperature control induced a reduction in battery temperature to 11 °C (suboptimal levels) under conditions of low ambient temperature and vehicle speed. Conversely, while unequal evaporation temperature control could maintain the battery temperature within the optimal range of 20–45 °C, it would result in a maximum COP drop of more than 20% under certain conditions. Furthermore, the effects of the two control methods on driving range under different ambient temperatures and vehicle speeds were studied. The reasults indicated that the ultimate influence of uneuqal evaporation temperature control on the quarterly average driving range was virtually negligible, peaking at 1.35%. Given the dual-objective constraints pertaining to the driving range and the battery cooling performance, it was concluded that uneuqal evaporation temperature control was the optimal choice for direct battery cooling. • A transcritical CO 2 battery direct cooling thermal management cycle is studied. • The effects of battery temperature controls on driving range of EVs are evaluated. • Coupling effects of operation conditions and controls on driving range of EVs is revealed. • The optimal option for battery temperature control is recommended. [ABSTRACT FROM AUTHOR]

• An improved FRN model is developed for variable cross-section air-cooled BTMSs. • An efficient method based on FRN model is proposed for design of deflector shape. • The optimized BTMS outperformed those using the previous optimization methods. • Experiments are carried out to verify the effectiveness of the optimization method. Air-cooled systems are widely used for cooling of battery packs in electric vehicles. Optimization method combined with the flow resistance network (FRN) model is effective for system design. However, the local pressure loss of divergence and convergence ducts in the traditional FRN model is ignored, leading to large error when applying the model in systems with variable cross-section channels. In this study, the local loss coefficients of the contractive and diffusive channels are derived and the improved FRN model is developed for velocity calculation of variable cross-section air-cooled systems. The improved model is verified using computational fluid dynamics method. Based on the improved FRN model, the cross-section width distribution of the divergence duct is calculated from the given flow rate distribution. The shape of the divergence deflector is optimized by adjusting the flow rate distribution and using the improved model. The results indicate that the temperature difference of the battery cells decreases by more than 84% after the optimization, with the maximum temperature decreasing by more than 3.8 K. Furthermore, the optimized system performs better than those in the previous studies. Also, experiments are carried out to verify the effectiveness of the developed optimization method based on the improved FRN model. [ABSTRACT FROM AUTHOR]

It is seen from this figure that the maximum temperature rise of the cell module decreases as the increasing rate of fluid flow. The maximum temperature rise of the cell module is under 40 °C and 36 °C respectively since the flow rate is 0.40 × 10−3 L·s−1 and 1.20 × 10−3 L·s−1, indicating that increasing flow rate increases the cooling capability of the LCP. • A new cooling plate is developed for controlling undesirable cell temperature field. • Inlet and outlet of cooling plate have big impact on cell temperature distribution. • Increasing flow rate decreases cell temperature rise markedly. • Cooling plate channel width has weak impact on cell temperature distribution. • Channel width has great effect on ratio of power consumption of cooling plate. The thermal management for a lithium ion battery cell plays a pivotal role in enhancing the cell performance and reliability for electric vehicles. In this work, a novel serpentine-channel liquid cooling plate with double inlets and outlets is developed for better managing an undesirable temperature distribution of a cell module. With a simplified model for the cell module, numerical analyses are implemented using the software of FloEFD to study effects of flow directions, flow rates and channel widths of the cooling plate on cell temperature distribution under different operating conditions; Likewise, a ratio of power consumption as a non-dimensional number is defined to analyze the hydraulic performance of the developed cooling plate. Results show that locations of the inlet and the outlet as well as flow directions have great impacts on the cell temperature distribution and the ratio of power consumption of the cooling plate. Increasing fluid flow rate substantially decreases the maximum temperature rise of the cell module while it has little effect on the temperature distribution. Moreover, the channel width of the cooling plate has a strong influence on its ratio of power consumption as well as the cell temperature distribution but it has a weak influence on the cell maximum temperature rise. Interestingly, the developed serpentine-channel cooling plate offers one a new method to design a lithium ion battery thermal management system for controlling temperature distribution of a cell module. [ABSTRACT FROM AUTHOR]

The current study proposed a heat pipe (HP)-assisted hybrid fin (HF) for inter-cell cooling in a battery thermal management system (BTMS). Its thermal performance was comprehensively investigated under extreme thermal conditions of up to 50 W along with critical variables. A numerical model for the proposed HF-BTMS was developed using the finite difference method and integrated with a performance prediction model based on an artificial neural network. After successfully validating with experimental results, the developed numerical model was intensely used for module-level thermal analysis and multivariate optimization. The proposed HF-BTMS exhibited a better thermal performance, which was experimentally verified by the reduction in the maximum temperature and deviation by 5.4 and 3.8 °C, respectively, than the BTMS with conventional plain fin (PF). The multivariate optimization indicated that the optimized performances of the HF-BTMS were all within the desired temperature ranges. The condensation lengths are known to be most influential rather than other variables related to coolant operating conditions. Finally, under the most thermally harsh condition, compared to PF-BTMS, the HF-BTMS was found out to dramatically reduce the maximum temperature and temperature deviation of the BTMS by over 17.95 °C and 16.37 °C, successfully maintaining within the safety range. [ABSTRACT FROM AUTHOR]

The electrical and thermal characteristics of Li-ion batteries (LIBs) are closely related and need to be further investigated. Especially for the promising immersion cooling LIBs, the interaction between battery performance and immersion thermal management system still needs to be clearly illustrated. This research aims to reveal the electro-thermal equalization behaviors of LIB modules with immersion cooling. An electro-thermal test platform was established for a series-connected LIB module. Besides the experimental research on the thermal control capability, the electro-thermal equalization behaviors of the LIB module with different cooling methods are also investigated at steady and dynamic operations. Results show that the electrical inconsistency between the LIBs with different cooling schemes intensifies at the end of discharge, and the voltage deviation (δ U,t) increases quickly at high rates. However, immersion cooling can mitigate this behavior effectively. As the immersion height ratio varies from 0 to 1, the δ U,t at the end of the 2C discharge declines from 17.1% to 4.3%, then rises to 7.9%. From a general viewpoint, the indicators, including the equalization rates of the voltage, average temperature, and temperature difference, are defined further to assess the electro-thermal equalization behaviors of the module. According to the estimation, the equalization capacities are static flow > forced flow > air cooling for all indicators. Static flow immersion cooling demonstrates superiority in thermal and electrical equalization, while forced flow immersion cooling is still necessary at high discharge rates for reducing thermal recovery time and temperature rise. [Display omitted] • Battery immersion cooling test was developed for electro-thermal performance. • Immersion cooling mitigates the aggravation of voltage deviation of batteries. • Effect of immersion heights on electro-thermal equalization behavior was discussed. • The equalization rates are proposed to assess equilibrium ability. • The equalization behavior of module shows static flow > forced flow > air cooling. [ABSTRACT FROM AUTHOR]

The heat dissipation performance of batteries is crucial for electric vehicles, and unreasonable thermal management strategies may lead to reduced battery efficiency and safety issues. Therefore, this paper proposed an optimization strategy for battery thermal management systems (BTMS) based on linear time-varying model predictive control (LTMPC). To begin, based on the results of three-dimensional thermal flow analysis, a reduced order substitution model for the battery cooling system was established. Next, to address the issue of high computational complexity caused by the nonlinear model in the controller, a linearization method based on staged control was designed. Furthermore, the control parameters were optimized using the particle swarm optimization algorithm. Finally, a BTMS physical model based on SIMSCAPE was established for performance simulation. The performance of the logic threshold controller (LTC), linear model predictive controller (LMPC), and nonlinear model predictive controller (NMPC) was compared and analyzed. LTMPC was found to reduce the average temperature of the battery by up to 2.33 °C and 1.90 °C, and the cumulative temperature difference is reduced by 13.9% and 16.6% compared to LTC and NMPC, respectively. Compared to LMPC, LTMPC reduces thermal management energy consumption by 21.2%. • A complete mathematical model of the liquid cooling cycle circuit was derived through the order reduction method. • Reasonably incorporate future information into the controller to improve robustness of system. • Adopting a staged control strategy to segment the model, establishing a linear time-varying control model, greatly improving computational efficiency. • The upper controller uses the heat exchange between the coolant and the air conditioning system as the control variable, improving control efficiency. • The combination of particle swarm optimization algorithm and pareto curve fully exploits the optimization potential of parameters. [ABSTRACT FROM AUTHOR]

In order to improve the heat dissipation performance of lithium-ion batteries in hot climate, a coupled heat dissipation model including different air inlet and air outlet arrangements and PCM thicknesses was established by extracting cooling air from a vehicle air-conditioner. At the condition of the fixed PCM thickness, the effects of air inlet and air outlet arrangement on heat dissipation performance (HDP) of battery pack were researched, and the results indicate that case 5 is the optimal choice because of the low energy consumption and good HDP. The results of PCM thickness on HDP of battery pack be investigated through catastrophe theory analysis method. Thus, the results reveal that case 8 has highest evaluation value 0.97536 of the heat dissipation level of the battery pack among them. Based on the above results, four cases had been investigated to pursue the lower temperature difference of battery pack, and the results indicate that case 10 is the optimal choice, because of the lower energy consumption and temperature difference. • A coupled heat dissipation model including different air inlet and air outlet arrangements and PCM thicknesses was established. • Effects of different conditions on the heat dissipation of the battery pack is studied. • Catastrophe model was used to evaluate the heat dissipation level of the battery pack. [ABSTRACT FROM AUTHOR]

• An easily-assembled liquid cooling (LC) system is developed by an embedding process. • The system avoids processing tailor-made LC components, reducing cost and complexity. • The flexibility of the silica gel greatly reduces the thermal contact resistance. • A hierarchically thermal conductive skeleton is constructed in the battery module. • The battery module presents superior cooling performance in harsh working condition. Liquid cooling (LC) technology is most widely used in battery thermal management systems. However, for cylindrical battery modules, tailor-made LC components with curved surface and complicated LC structures are required to match the curved surface of the cells. Herein, we design an easily-assembled LC structure by directly embedding thermal conductive silica gel (SG) into a 21.6 V/39Ah cylindrical battery module with thermal conductive plates (TCPs) connected to LC plates (LCPs). This LC strategy avoids the tedious and costly procedure of processing LC components with special specifications, and demonstrates excellent adaptability to battery modules with diversified specifications. By selecting copper plates and flexible SG with 2 wt% expanded graphite as the TCPs and embedding material respectively, a high-efficient thermal conductive skeleton can be constructed, endowing the module center with a greatly reduced thermal resistance of 1.27 × 10−2 m2∙K∙ W −1. In addition, the optimal water inlet velocity and cell distance are determined to be 0.2 m∙ s −1 and 7 mm, respectively. As a result, the maximum temperature (T max) and temperature difference (ΔT max) of the battery module are well maintained within the optimal ranges of 28.9∼41.7 °C and 1.4∼4.7 °C under all working conditions, respectively. Remarkably, even under the harsh working conditions with a 3 C discharge rate under 25, 35 and 40 °C, the T max can be controlled below 31.6, 40.3 and 41.7 °C, while the corresponding ΔT max are only 4.6, 3.8 and 3.8 °C, respectively. [ABSTRACT FROM AUTHOR]

The temperature has a significant effect on the lifespan and the safety of the batteries which are one of the core components of electric vehicles. A well-designed battery thermal management system is required to adjust the temperature of the batteries within an appropriate range for thermal safety, and further minimize the energy consumption for energy savings. However, these two goals form a tradeoff. Typically, increased energy consumption for cooling results in safer batteries thermally. To examine this tradeoff, firstly, a linear electro-thermal model is built to evaluate the thermal dynamics of the operating battery-cooling module. The linear model accounts for the heat generation based on internal resistance, and the heat transfer based on a resistance–capacitance model. Such linear model reduces the computation of the model simulation to dynamically catch up with the change of temperatures and to implement control strategies on the cooling system in a short time. Based on this model, a model predictive control (MPC) framework is proposed to design thermal control methods, which considers both thermal safety and energy saving. The weight of these two goals can be adjusted to explore the tradeoff between them. Finally, we investigate the performance of the MPC framework by applying the Urban Dynamometer Driving Schedule (UDDS) to the battery module. The simulation results show that the electro-thermal model is effective for battery thermal dynamics evaluation. Additionally, the tradeoff between the two goals is demonstrated by the simulation. • A fast temperature prediction and closed-loop thermal control framework is proposed. • An electro-thermal model of an active-liquid-cooling battery module is developed. • A thermal prevention control strategy is proposed. [ABSTRACT FROM AUTHOR]

• A computationally efficient model for large-scale battery packs is developed. • Parameters are devised to evaluate the structural designs for the battery pack. • Pros and cons of the alternative structural designs are analyzed. • Interspersed battery pack design is suggested to enhance the thermal performance. In this paper, a comparative study for structural design of battery thermal management system is presented for electric vehicles. A thermal model for the pouch battery pack with liquid cooling is developed for thermal analysis of various pack designs. Typical battery pack with fin-cooling structure is set as a reference design, and thermal behavior of the battery pack is examined in the aspect of cooling performance and temperature uniformity. Numerical results indicate that poor heat conductivity from the bottom of the cell stack to the cooling plate is one of the major barriers to the efficient heat dissipation and asymmetric design of fin-cell arrangement have negative effect on the temperature uniformity of the battery pack. To improve the performance of the thermal management system, various structural designs are suggested and evaluated based on plural criteria. A new structural design for the large-scale battery pack is suggested to enhance the cooling performance and temperature uniformity of the battery pack minimizing the increase in system volume, weight, and pressure drop. [ABSTRACT FROM AUTHOR]

This paper describes a set of experimental tests carried out to better understand the thermal behavior of Lithium-ion batteries under load and the capability of various cooling fluids in maintaining the working conditions within a safe range for the cells. Despite several theoretical models are available in the literature, very few experimental data are reported. Different types of cells have been analyzed. The generation of hot spots has sometimes been registered, their occurrence being independent of cell geometry and size; instead, the battery's history and age, appeared the main factors in determining the onset of hot spots on the surface of the cell. Two experimental rigs have been set up to test the capability of different cooling fluids in removing the surplus heat generated in a Li-ion battery module, where the cells of interest have been replaced with electrically heated elements with the same thermal characteristics of the cells. It was thus possible to safely investigate "extreme" operating conditions, where the occurrence of a thermal runaway is possible. Among the tested fluids, air was unable to adequately limit the surface temperature increase, while a perfluorinated polyether, allowed to work within the optimal temperature range, even under severe operating conditions. • The thermal behavior of different types of Li-ion batteries has been experimentally investigated. • The cells have been tested under both ordinary and severe operating conditions. • Dangerous operating conditions of the batteries have been identified. • A reliable and dedicated experimental facility has been set up. • The cooling efficiency of a range of thermal fluids has been evaluated. [ABSTRACT FROM AUTHOR]

• Structural theory is adopted to design the bifurcating channels of the cold plate. • Effects of structural parameters and flow rate on cooling performance are studied. • Optimization of main channel width has the greatest effect on reducing pressure drop. For rectangular Li-ion batteries, this paper optimized the heat dissipation of the cold plate embedded with leaf-like network according to the structural theory. Not only the distributed network layer was established, but also the collection network layer was designed to mitigate the inherent temperature gradient problem of the conventional single channel. The effects on the split point of symmetrical/asymmetrical bifurcation, the width ratio of symmetrical bifurcation, the inlet mass flow rate, the number of feed-out channels and the width of main channel on the thermal performance of cooling plate were numerically simulated. The results demonstrated that the heat dissipation was better when the split point is near the limit position of the outer channel. Compared with the offset bifurcation network, the symmetric bifurcation network can achieve better heat transfer characteristics, but its pressure drop was slightly higher than that of offset bifurcation network. The increase of width ratio and inlet mass flow can meet both maximum temperature and temperature uniformity objectives, but at the expense of pressure drop. Compared with the single feed-out channel, the double feed-out channels can meet both the thermal performance and the pressure drop requirements. As the width of the main channel (D 1) was elevated, pressure drop greatly declined on the basis of heat transfer. The simulation results can provide a reference for the design of cold plate embedded fractal-like network based on battery thermal management systems. [ABSTRACT FROM AUTHOR]