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Thermal runaway propagation of the power battery pack is an essential factor affecting the safety of electric vehicles. The commonly adopted propagation inhibition methods mainly include adding heat insulation materials and enlarging battery spacing, which could cause problematic heat dissipation and lower the system energy density. Herein, an innovative battery thermal management system composed of non-uniform thermal conductivity phase change materials and assisted liquid cooling is proposed. Combining the phase change materials with high and low thermal conductivity balances heat transfer and heat insulation requirements. The cooling performance and the ability of thermal runaway propagation mitigation of the proposed schemes are numerically studied. The results show that the proposed strategy can meet the heat dissipation requirements under normal operation and control the thermal runaway in a safe range by transferring the heat generated from the battery thermal runaway in the set direction. The maximum battery temperature and the temperature difference are 38.1 °C and 2.1 °C, respectively, under 3C discharge. Under thermal runaway conditions, the strategy successful confines the thermal runaway propagation within the middle row. The maximum battery temperature in other rows can be controlled under the irreversible thermal runaway reaction temperature of 200 °C. Further study found that increased thermal conductivity benefits the battery heat dissipation and reduces the risk of thermal runaway. However, it propagates faster and broader once the thermal runaway is triggered. In comparison, the decrease of thermal conductivity is beneficial to the mitigation of propagation but may reduce the overall heat dissipation of the battery module. This study can provide a new way to solve the contradiction between battery temperature control and thermal runaway spread suppression. • An innovative strategy is proposed to mitigate thermal runaway propagation. • Non-uniform phase change materials with different thermal conductivity are adopted. • The thermal runaway generated heat can be limited to transfer in a specific direction. • A suitable combination of high and low thermal conductivity for PCM is necessary. • Temperature control and thermal runaway suppression can be achieved simultaneously. [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]

• Three layout schemes of liquid cooling plate were discussed. • The heat dissipation in a liquid cooling system was considered under various factors. • The heat dissipation scheme for imported coolant cooling of variable temperature was proposed. • The solution reduces the temperature difference of the battery pack by 36.09 %. To promote energy conservation and emission reduction, the electric vehicles (EVs) are developing rapidly. An effective battery thermal management system (BTMS) can extend the service life of batteries and avoid thermal runaway. In this study, a liquid-cooling management system of a Li-ion battery (LIB) pack (Ni-Co-Mn, NCM) is established by CFD simulation. The effects of liquid-cooling plate connections, coolant inlet temperature, and ambient temperature on thermal performance of battery pack are studied under different layouts of the liquid-cooling plate. Then, A new heat dissipation scheme, variable temperature cooling of the inlet coolant, is proposed. Results indicate that connecting two sets of liquid coolant plates in a 3-series, 1-parallel configuration can effectively reduce the maximum temperature of the battery pack from 48.73 ℃ to 30.75 ℃, while controlling the maximum temperature difference to 3.98 ℃ at the end of discharge. Simultaneously, the proposed cooling scheme reduces the maximum temperature difference within the battery pack by 36.09 % at the beginning of the discharge period. This study provides a valuable reference into advancing BTMSs of battery pack-level for EVs. [ABSTRACT FROM AUTHOR]

• Pulsating heat pipes with good thermal performance were designed for battery module heating management at low–temperatures. • The low–temperatures thermal management system for the battery module with pulsating heat pipes was proposed. • The thermal and electrical performance of the battery module with low–temperatures thermal management system was investigated. To effectively solve the problem that the capacity of lithium power batteries decreases significantly and is prone to irreversible damage under low–temperature charge and discharge scenarios, which seriously affects the driving range, cycle life and service safety of electric vehicles (EVs). In this paper, a low–temperatures thermal management system of pulsating heat pipes with ethanol as the base fluids and TiO 2 nanofluids as the working fluids (TiO 2 –CLPHP TMS) is constructed. On this basis, the thermal performance analysis of TiO 2 nanofluids pulsating heat pipes (TiO 2 –CLPHP) is carried out under different volume concentrations (0 %, 0.5 %, 1.0 %, 2.0 %, 4.0 %, and 8.0 %) and different fluid filling rates (30 %, 50 %, 70 %, and 90 %) in a low–temperature environment. Aiming at the low–temperatures charging scenario of the battery module, the performance test of the TiO 2 –CLPHP TMS for the battery module heating management is carried out under different low–temperature environments (−5 °C, −15 °C, and −25 °C) and different charging rates (0.3C, 0.5C, 0.7C, and 1.0C). The experimental results show that TiO 2 –CLPHP with fluids filling rate of 50.00 % and TiO 2 nanofluids concentration of 2.00 % has good performance in start–up and heat transfer, and can optimize the thermal performance of TiO 2 –CLPHP. Meanwhile, TiO 2 –CLPHP TMS can ensure that the battery module has superior thermal performance. the battery module can be charged within the allowed temperature range (greater than 0 °C). under different low temperature environments (−5 °C, −15 °C, and −25 °C), the temperature of the battery module is basically maintained at 3.30 °C, 8.00 °C and 16.00 °C. The temperature difference between different areas of the battery module is within the allowable temperature difference range of 5 °C, which reduces the adverse effects of the battery aging caused by low–temperature charging and uneven temperature. Moreover, the battery module also has good electrical performance, the battery module voltage is in a low–level range in the early and middle stages of charging. During the complete charging process, the low–temperature charging capacity of the battery module has almost no attenuation, and the charging capacity ratio is as high as 95.92 %. Compared with the pure battery module, the charging capacity and charging efficiency of the battery module with the TiO 2 -CLPHP TMS has been improved to different degrees. Especially at −25 °C, the maximum charging capacity and charging efficiency can be increased to 24.51 %, and the minimum can be increased to 13.17 %. which ensures the efficient charging of the battery module. This proves that the designed TiO 2 –CLPHP TMS is feasible and effective for battery module heating 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]

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

In this work, a composite cooling system including composite phase change material(CPCM) and liquid cooling is designed for battery pack, and the effects of coolant flow rate, battery spacing, thermal conductivity of CPCM, channel number of cooling plate on the safety performance of battery pack under thermal runaway propagation are studied. The results reveal that: (1)Coolant flow rate increase mainly delays the thermal runaway propagation on both sides of cooling plate. When the coolant flow rate is 0.029 m/s, the thermal runaway propagation time through the cooling plate is 32.9s, which is extended by 1.84 times than that at 0.009 m/s (2)Battery spacing increase delays thermal runaway propagation and changes the propagation path. (3)Thermal conductivity reduction of CPCM can significantly delay thermal runaway propagation, because the heat is concentrated in the periphery of the battery and is hard to transfer though CPCM and cooling plate. (4)Compared with other influence factors, channel number of cooling plate has less influence on the overall thermal runaway propagation time. When the channel number is between 5 and 1, the total thermal runaway time changes within 25.5s–27s. The conclusions in this work are helpful to design a safer thermal management system for lithium-ion battery packs. • A novel composite cooling strategy is designed for cylindrical battery pack. • Effects of different factors on the thermal safety of the battery pack are studied. • Thermal runaway propagation path and time of the battery pack are analyzed and obtained. [ABSTRACT FROM AUTHOR]

• Stimulus strategy with auxiliary heat load is valid for start-up promotion and heat transfer enhancement of PHP. • High interference temperature, weak auxiliary heat load and long period are optimal for stimulus strategy. • Phase-change mechanism and hysteresis of working medium in PHP is the main reason for validity of stimuls. Stimulus strategy is proposed to enhance the heat dissipation performance of Pulsating Heat Pipe (PHP) at low heat load for local hot spot regression in Battery Thermal Management (BTM). An auxiliary heat load is applied to stimulate the start-up of PHP. The performances of PHP with and without stimulus are compared and the properties of PHP after stimulus are discussed. It is concluded that the application of auxiliary heat load is able to stimulate the start-up of PHP in experiments. The strategy is mainly based on the phase-change mechanism as well as the hysteresis of working medium. Thermal resistance and the evaporator temperature are significantly reduced, if PHP starts operation after stimulus. Long period of stimulus and strong auxiliary heat load are favored for the reduction of thermal resistance and the shortening of period for start-up. The thermal resistance may be reduced by 29.1 ∼ 69.6 % and the temperature may be regressed by around 8 °C. However, PHP may suffer from temperature uplift and overshot to the maximum evaporator temperature. Therefore, high interference temperature coupled with weak auxiliary heat load and long period of stimulus are suggested as the optimal strategy. The verified strategy offers a new method for local hot spot regression and a possible way to mitigate the risk of thermal runaway, since the heat dissipation is enhanced at the initial stage of damage or destruction. [ABSTRACT FROM AUTHOR]

The battery thermal management system (BTMS) with liquid cold plates has been proven to be effective in temperature control and heat transfer. In this work, a novel liquid cold plate featuring pin fins for the cooling of prismatic lithium-ion batteries is proposed. The performances of BTMS with liquid cold plates are numerically investigated by using a three-dimensional CFD model and compared under different coolant inlet velocities, pin fins' heights, and arrangements. The efficiency index (EI) is employed to evaluate the comprehensive performances of cold plates by considering heat transfer and liquid flow. The results indicate that the introduction of pin fins contributes to improving the heat transfer performance and thus reducing the maximum battery temperature rise (Δ T rise) and temperature difference (Δ T diff). Besides, both the Δ T rise and Δ T diff increase as the pin fins' height (PFH) decreases. However, the cooling micro-channel with pin fins featuring a dimensionless height (H d) of 1/4 provides the best thermo-hydraulic performance and the lowest power consumption under the same battery thermal performance. In addition, the cooling micro-channel with pin fins placed on two opposite heat transfer walls exhibits better heat transfer performance and thus better battery thermal performance, compared with the cooling micro-channel with pin fins placed on the single heat transfer wall. When the coolant inlet velocity of 0.4 m/s at a 3C discharge rate the Δ T rise and Δ T diff of the cold plates with pin fins staggered arrangement in stream-wise direction for the opposite walls on both top and bottom walls are reduced by 4.045K and 3.122K, respectively, compared with the cold plates without pin fins. • A novel LCP featuring pin fins for enhancing BTMS performance is proposed. • A transient thermo-fluid multi-physical field numerical model is developed. • Effects of pin fins' height and arrangement on the thermo-hydraulic performance are studied. • A novel LCP is used for enhancing temperature uniformity and reduce maximum temperature. [ABSTRACT FROM AUTHOR]

• Numerically studied the cell-spacing effect on Li-ion battery pack air cooling. • Optimization of cell-spacing is done using DOE method. • Results of numerical simulation are validated by conducting experiments. • The optimum design significantly improves the thermal performance of BTMS. The spacing in a lithium-ion battery pack is crucial in various aspects; including mechanical stability, heat dissipation, temperature distribution, thermal coupling, and cooling effectiveness. This research aims to enhance the cooling efficiency of a 24 V, 10Ah, 4P7S aligned battery pack by optimizing the distribution of spacing among the battery cells. The parameters examined in this study are the longitudinal pitch (D x), transverse pitch (D y), and distance of first row with the side walls (D w). The Computational Fluid Dynamics (CFD) approach is utilized to compute the flow and temperature fields of the battery thermal management system (BTMS). Thereafter, CFD simulations, in conjunction with the Taguchi approach of Design of Experiments (DOE), is used to determine the optimal parameters. Additionally, an experimental set-up is developed to validate the numerical results with experimental outcomes. Thermal performance evaluation includes examining temperature changes both along and across the airflow direction, temperature variation around the circumference of the cells. The key parameters such as maximum temperature (T max), average temperature (T avg.), maximum temperature differential (∆T max), and temperature standard deviation (σT) are also determined. Furthermore, it is assessed that how different distances affect the necessary power (P) and space utilization factor (α) for the airflow. Enlargement of the cooling air vortices within the backflow zone with an increase in D x is observed to cause a drop in T max , T avg. , ∆T max , and σT. In addition, as D y is increased, the values of these parameters fall to a minimum and then begin to rise. D w also shows a similar impact. Changing D x from 20.00 mm to 36.00 mm raises inlet pressure, which causes P to increase by 0.57 W. It is determined that the optimal dimensions to maximize the thermal performance of the battery pack in question are (D y = 24.00, D x = 36.00, and D w = 12.00, mm). The numerical results closely matched with the experimental results, with a maximum absolute relative error of 1.48%. [ABSTRACT FROM AUTHOR]

Recently, there has been a vast increase in interest in renewable energy technologies. In the present era of sustainable energy evolution, battery thermal energy storage has emerged as one of the most popular areas. A clean energy alternative to conventional vehicles with internal combustion engines is to use lithium-ion batteries in electric vehicles (EVs) and hybrid electric vehicles (HEVs). While Lithium-ion batteries are advantageous, they face several challenges including concerns over rapid charging capabilities, degradation over time, and sensitivity to external environmental conditions. One of the most challenging barriers to this technology is its operating temperature range which is limited within 15°C–35°C. This review aims to provide a comprehensive overview of recent advancements in battery thermal management systems (BTMS) for electric vehicles and stationary energy storage applications. A variety of thermal management techniques are reviewed, including air cooling, liquid cooling, and phase change material (PCM) cooling methods, along with their practical applications. The review also covers the challenges and limitations of current BTMS and highlights the need for further research and development in this field. The review concludes with a discussion of future trends and potential solutions for improving the performance and safety of BTMS. [Display omitted] • Comprehensive review of air, liquid, and PCM cooling strategies for Li-ion batteries. • Comparative analysis of cooling methods based on performance metrics and applications. • Analyzes advantages and limitations of different cooling approaches including practical applications. • Identifies current challenges in BTMS and suggests future enhancements. • Effective battery thermal management crucial for safety, performance, and longevity. [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]

The safe and efficient power battery thermal management system (BTMS) is a prerequisite for the effectiveness and long service life of electric vehicles. So, a BTMS with inserted multi-layer phase change materials (PCMs) is proposed to enhance the safety and working performance of battery pack. Effects of PCM settings and operating conditions on the thermal performance of battery pack are discussed and analyzed. The results reveal that PCM cooling plays a significant role in the thermal management of battery pack, where the maximum temperature value and temperature difference of BTMS with multi-layer PCM #C are respectively reduced by 13.61 °C and 2.54 °C compared to battery pack without PCM. Besides, the coupling effects of multiple factors, that is, PCM permutation, the thickness and height of PCMs, and ambient temperature, on the heat dissipation of battery pack are discussed via orthogonal results analysis. The optimized multi-layer PCMs are obtained for the BTMS, i.e., P s = 121, h 1 = 5 mm and L = 6 mm, which achieves the lowest values of T max = 43.02 °C and Δ T = 3.37 °C at T amb = 20 °C. It provides insights for optimizing thermal control strategies for the advancement of thermal management in electric vehicles, ultimately enhancing safety, performance, and longevity. • A battery thermal management system with multi-layer phase change materials is proposed. • Multifactorial effects of phase change materials on the thermal performance are discussed. • Orthogonal results analysis is employed to gain the optimized thermal management systemt setting. • Thermal performance of battery pack is strongly improved. [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]

• Air-cooled thermal management of battery module has been explored numerically. • Thermal performance for inline and staggered cell arrangement was examined. • Negligible effect of cell arrangement occurs beyond a critical number of cells. • For small number of cells, the staggered arrangement slightly improves thermal uniformity. Global environmental concerns over increased emissions from the transportation vehicles have driven research instincts towards development of clean energy vehicles. Pure and hybrid electric vehicles coupled with lithium-ion batteries for energy storage are environmental friendly options to realize the future dream of low carbon emissions. However, an efficient battery thermal management system (BTMS) is a prerequisite for safe operation of such high voltage batteries to avoid thermal runaway and degradation, thereby maintaining the temperature uniformity in the battery pack. Thus, the present work numerically investigates the performance of an air cooled battery module for efficient removal of heat generated during the discharge process at different values of air-flow velocity, cell configuration and the number of cells in the battery module. A coupled electrochemical-thermal model is employed to model the discharge behaviour of the battery in conjunction with the two-dimensional flow and heat transfer model to monitor the temperature in and out of each battery cell. A correlation is developed for the maximum temperature in the module as a function of the number of cells in the system. The flow configuration (inline or staggered arrangement) of cells in the stack is observed to have no influence over the velocity and thermal field beyond a critical value of number of cells in the module. [Display omitted] [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]

• An enhanced thermal network model with added thermal resistances and capacities. • Thermal resistances and heat capacities are determined via genetic algorithm. • The impact of added resistances and capacities on thermal response is discussed. • Temperature prediction error is reduced from 4.24 to 0.95 ℃. Battery thermal management is crucial for preventing the safety issues of lithium-ion batteries. Due to the simple modeling and fast calculation speed, the thermal resistance-capacity (RC) network model is broadly applied in the design of battery thermal management systems. However, the simplification of heat flow paths and the lumped definition of thermal capacity in traditional RC models result in large temperature prediction errors, which fail to reflect the thermal response in complex and diverse heat transfer situations. To improve the prediction accuracy, a decentralized centroid multi-path RC network model is constructed for a typical prismatic lithium-ion battery. This novel model incorporates multiple heat flow paths with additional thermal resistances and legitimately decentralizes the lumped heat capacity to other surface center points, resulting in a more realistic thermal response. A genetic algorithm is employed to determine the unknown thermal resistances and heat capacities at the attributed nodes. Results show that compared to the traditional RC network model, the multi-path decentralized RC network model can reduce the temperature prediction error from 4.24 to 0.95 ℃. This more refined modeling approach extends the application scope of thermal resistance network models to more complex scenarios while maintaining efficient simulation speed, which enables the attainment of more accurate and reliable onboard temperature predictions for lithium-ion power systems. [ABSTRACT FROM AUTHOR]

Electric vehicles that utilize lithium-ion batteries (LIBs) as a power source provides viable solution to realize the decarbonization of transportation sector. However, their future application is severely hindered by the temperature sensitivity of LIBs. Thus, a well-designed battery thermal management system (BTMS) is recommended to ensure proper temperature environment for improving LIBs' performance. Here, the aim is to provide a clear and detailed understanding on the two-phase heat transfer technologies for BTMS, especially given the urgent demands for fast-charging and harsh operating conditions. The fundamentals of BTMS, including battery working principles, adverse temperature effects, and modelling approaches are first analyzed. What's more, typical battery cooling methods are briefly discussed and categorized in terms of working mediums. However, with the ever-growing trend towards high energy density and fast charging, these methods are insufficient to effectively regulate the temperature of batteries. To address the rigorous demands, two-phase heat transfer strategies, with heat transfer rate several orders of magnitude higher than typical BTMS, have gained great interests. The up-to-date progresses of such system based on refrigerant flow boiling, immersion boiling, spray cooling, and other strategies, are comprehensively reviewed. Besides, discussions on battery thermal management studies are presented from the perspectives of heat transfer mechanism, pros and cons, and future insights. This state-of-the-art review is expected to deliver guidance and draw more attention to the development of advanced thermal management approaches in EV applications. • A review of emerging two-phase battery thermal management strategies is presented. • Two-phase heat transfer-based BTMSs effectively control battery temperature. • The mechanism, limitations and future insights of emerging BTMS are discussed. [ABSTRACT FROM AUTHOR]

The control of a battery thermal management system (BTMS) is essential for the thermal safety, energy efficiency, and durability of electric vehicles (EVs) in hot weather. To address the battery cooling optimization problem, this paper utilizes dynamic programming (DP) to develop an online rule-based control strategy. Firstly, an electrical–thermal-aging model of the LiFePO 4 battery pack is established. A control-oriented onboard BTMS model is proposed and verified under different speed profiles and temperatures. Then in the DP framework, a cost function consisting of battery aging cost and cooling-induced electricity cost is minimized to obtain the optimal compressor power. By exacting three rules "fast cooling, slow cooling, and temperature-maintaining" from the DP result, a near-optimal rule-based cooling strategy, which uses as much regenerative energy as possible to cool the battery pack, is proposed for online execution. Simulation results show that the proposed online strategy can dramatically improve the driving economy and reduce battery degradation under diverse operation conditions, achieving less than a 2.18% difference in battery loss compared to the offline DP. Recommendations regarding battery cooling under different real-world cases are finally provided. • A precise BTMS model for EV under diverse operation conditions is first proposed. • Battery capacity degradation and cooling energy is minimized by dynamic programming. • An online near-optimal battery cooling strategy is proposed from dynamic programming. • Using regenerative energy for cooling can dramatically reduce battery degradation. • Improved driving economy and battery life gained from the proposed cooling method. [ABSTRACT FROM AUTHOR]

A battery thermal management system (BTMS) using a composite phase change material (CPCM) is proposed for both heat dissipation under fast charging conditions and preheating in low temperature environments. Based on the validated battery thermal model and CPCM model, a parametric study was performed to determine the optimal conditions. As a result, in the proposed concept, the highest maximum temperature and maximum temperature difference are 39.3 °C and 3 °C under 3C charging conditions at room temperature. This is achieved by decreasing the total operating time of the liquid cooling system by 35.2% compared to that of the conventional BTMS, and after the cycle, the latent heat is fully recovered for use in a continuous cycle. Also, under low temperature conditions of −10 °C, the final maximum temperature is 29.2 °C after preheating in the proposed BTMS. The temperature difference is 2.5 °C, which is significantly lower than when applying the existing liquid heating method. Therefore, the proposed BTMS is advantageous in terms of both the cooling performance under fast charging conditions and preheating under low temperature conditions. • A compact BTMS with composite phase change material using copper foam is proposed. • Both the extreme conditions of fast charging and low temperature are covered. • The practical application of CPCM under charge-discharge cycle is considered. • Battery thermal model and CPCM model were validated well with experimental data. [ABSTRACT FROM AUTHOR]

A hybrid BTMS considering heat dissipation and mechanical protection for prismatic battery modules is constructed, which combines the modularized liquid-cooling plate (MLCP) and the phase change material (PCM)-negative Poisson's ratio structural laminboard. The effects of interior structure, flow direction, flow rate, and cooling strategy of the MLCP on the thermal performance of the battery module were investigated. It showed that the proposed MLCP was able to weaken the heating effect of coolant along the flow path by more than 50 % through modularized design. Furthermore, the alternating cooling strategy of sub-domains of MLCP was designed, which halved the energy consumption of liquid cooling systems. In comparison to the case without the laminboard, the maximum temperature and temperature difference of the case with it were reduced by 3.79 °C and 2.50 °C, respectively. Meanwhile, the maximum stress and total deformation of the battery cell were also decreased by 1.67 MPa and 78.1 μm with the protection of the laminboard at 1000 N. With the MLCP and the multifunctional laminboard, the maximum temperature and temperature difference of the battery module were kept below 35 °C and 4 °C, respectively, even at a high discharge current of 100 A and under dynamic conditions. [Display omitted] • Thermal, mechanical, lightweight, and energy-saving designs are considered in BTMS. • Modularized liquid-cooling plate is designed to improve temperature inconsistency. • A novel laminboard is proposed combining negative Poisson's ratio structure and PCM. • Alternating and delaying cooling strategies can both save energy consumption of BTMS. [ABSTRACT FROM AUTHOR]

• Various approaches to modeling the thermal behavior of batteries are reviewed with regard to thermal coupled battery models for the thermal analysis of battery and battery thermal management system (BTMS). • Three commonly used battery models for thermal-coupled simulations, simple battery model, electrical circuit model (ECM), and physics-based electrochemical model are reviewed. • The methods of the parameter identification for the thermal-coupled battery modeling are also introduced. • The merits and drawbacks of each model are discussed in detail, and the complexities involved in parameter identification are investigated. • The objective of this extensive review is to assist researchers and engineers in choosing and effectively employing suitable tools for the investigation of battery thermal management. With the increasing popularity of electric vehicles, there is a growing need for efficient and reliable thermal management systems to regulate the temperatures of lithium-ion batteries. Heat generation, which can lead to decreased performance, reduced lifespan, and even safety hazards if not properly managed, is a major challenge for these batteries. This review provides an overview of the numerical modeling techniques used to simulate heat generation and thermal management in lithium-ion batteries for electric vehicles. Various approaches to modeling the thermal behavior of batteries are reviewed with regard to thermal coupled battery models for the thermal analysis of battery and battery thermal management system (BTMS). This review discusses various modeling approaches, including simple battery models, electrical circuit models (ECMs), and physics-based electrochemical models, focusing on the Newman P2D model. Thermal runaway model that is employed to inform safety design for lithium-ion battery is also reviewed. In addition, the parameter identification methods for these models are reviewed. The merits and drawbacks of each model are discussed in detail, and the complexities involved in parameter identification are investigated. This comprehensive review aims to guide researchers and engineers in selecting and utilizing appropriate tools for battery thermal management studies. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries (LIBs) are frequently employed in electric vehicles for their high energy density and lengthy cycle life. However, efficient battery thermal management system (BTMS) is critical for ensuring the reliability, safety, and service life, as temperature greatly impacts their performance. The potential risks of battery fire and explosion under excessive temperatures necessitate the development of effective emergency management and technologies to maintain safe operation. Phase change material (PCM) which offers distinct advantages, including reasonable cost, low energy consumption, and excellent temperature uniformity, making it an attractive candidate for thermal management, has emerged as a promising solution for BTMS. This comprehensive review aims to shed light on PCM-based BTMS, and it is found that carbon-based additives are better than metal-based additives concerning density and stability, and the addition of polymers and nanomaterials can improve the structural stability and mechanical properties. However, the flammability of PCM exacerbates the fire risk and hazard of battery thermal runaway (TR), and this review also has a particular emphasis on enhancing PCM's flame retardant properties and exploring its applications in BTMS. Flame-retardant PCM can ensure the safety of LIB utilization process and has a promising application in suppressing TR. Moreover, there exists a prominent challenge of the comprehensive need for optimization of heat dissipation optimization and improvement of TR propagation suppression ability of PCM-based BTMS. Finally, the challenges and outlooks focus on the future PCM-based BTMS are disclosed, in the hope of bring new insights to building a synergistic BTMS. Graphic abstract [Display omitted] • Heat dissipation optimization and thermal runaway propagation suppression coordination. • Highly thermally conductive, non-leakage deformable, flame retardant PCM compared. • Feasibility to utilize PCM to prevent the propagation of thermal runaway proposed. • Insights into research gap and further development and of PCM provided. [ABSTRACT FROM AUTHOR]

Nowadays, the cylindrical 21700-type lithium-ion batteries (LIB) are increasingly being implemented to enhance the distance covered by electric vehicles. In parallel, practical battery thermal management systems should be taken into consideration for battery packages during high current rate discharge operations. In the present work, an innovative hybrid nano/dielectric fluid cooling system that included indirect/direct coolant cooling strategies is numerically studied. The mediums for indirect and direct cooling systems are selected Al2O3-water nanofluid and HFE-7100, respectively. In this investigation, the influences of different C-rates (3C, 5C, and 7C) and coolants, different inflow velocities (0.2 m/s, 0.25 m/s, and 0.3 m/s), geometrical changes (include separator plates and corner curvatures), and real driving cycles for the 21700 cylindrical shaped batteries' thermal performance are widely studied. Additionally, a comparison between 21700 and the new model of LIBs, 4680-types was carried out to comprehend the effects of various energy-related factors on the behavior of the LIB packs in terms of temperature. According to the numerical results, 4%VF Alumina nanofluid with 0.3 m/s inlet flow rate has much better thermal performance compared to the water with 0.2 m/s inlet flow rate as the coolants for the indirect cooling channels. Moreover, results exhibited that using curved cooling channels and integrated separator plates inside the channels reduced maximum and non-homogeneity temperatures of the LIB bundle by 0.61 °C, and 0.16 °C, respectively. Eventually, two different types of LIBs (21700 and 4680) are compared using a similar number of cells and a cooling system. The comparison indicates that not only using a lower number of 4680-format LIB can provide enough energy but also its thermal performance has better results in comparison with 21700-format LIB. [ABSTRACT FROM AUTHOR]

The applications of lithium-ion batteries (LIBs) still suffer from thermal sensitivity and safety issues, especially given the rigorous requirements of fast charging and discharging. When choosing a proper battery thermal management system (BTMS), a comprehensive investigation should be made in terms of design complexity, system cost, and cooling efficiency, which usually forms a trade-off. In this study, four types of BTMS including air cooling, single phase immersion, indirect cooling, and two phase immersion are first evaluated on pouch battery pack. To describe the uniform heat generation, batteries are simulated by a three-dimensional electrochemical-thermal coupled model. Results show that air cooling and immersion cooling exhibits less extra weight, while two phase immersion delivers better in suppressing temperature rise and maintaining temperature uniformity. Then, the simulations involving different coolants are conducted for two phase immersion-based BTMS. The thermal behaviors of battery pack are examined at 5, 7, and 9 C discharge rates. The R1336mzz(Z) coolant with high boiling heat transfer coefficient is suitable for thermal management at high discharge rates. Besides, analysis reveals that increasing the immersion level of battery pack can improve battery temperature behaviors. This work is expected to provide preliminary proof of BTMS design for fast discharging. • A three-dimensional electrochemical-thermal coupled model for a pouch battery is established. • Comparative studies on air cooling, single phase immersion, indirect cooling and two phase immersion are conducted. • Effects of different immersion coolants and immersion levels are investigated. • R1336mzz(Z) performs optimal in regulating temperature and higher immersion level is recommended at fast discharging. [ABSTRACT FROM AUTHOR]

In this work, a novel battery thermal management system (BTMS) integrated with thermoelectric coolers (TECs) and phase change materials (PCMs) is developed to ensure the temperature working environment of batteries, where a fin framework is adopted to enhance the heat transfer. By establishing a transient thermal-electric-fluid multi-physics field numerical model, the thermal performance of the BTMS is thoroughly examined in two cases. The findings demonstrate that increasing the TEC input current, fin length, and thickness is beneficial for reducing the maximum temperature and PCM liquid fraction. Nevertheless, although the increase in fin length can lower the temperature difference, the influence of fin thickness and TEC input current on the temperature difference is tiny. Based on the numerical findings, the optimal fin length and thickness of 7 mm and 3 mm are obtained. In this situation, when the TEC input current is 3 A, the maximum temperature, temperature difference, and PCM liquid fraction in Case 1 are 315.10 K, 2.39 K, and 0.002, respectively, and those are respectively 318.24 K, 3.60 K, and 0.181 in Case 2. The configuration of Case 1 outperforms that of Case 2, due to the fewer TECs and greater distance from the battery pack to the TEC within Case 2. When experiencing a higher battery discharge rate, the TEC input current should also be correspondingly increased to ensure the temperature performance of the battery. The relative findings contribute to new insights into battery thermal management. • A novel BTMS combined with thermoelectric coolers and phase change materials is proposed. • A transient thermal-electric-fluid multi-physical field numerical model for the BTMS is developed. • The fin length, thickness, and TEC input current are suggested at 7 mm, 3 mm, and 3A. • The proposed BTMS can ensure battery temperature performance at high discharge rates. [ABSTRACT FROM AUTHOR]

• The presence of mechanical vibrations has been found to alter the optimal number of fins in the PCM-fin structure thermal management system. • Amplitude and frequency of mechanical vibration notably impact the thermal performance of the PCM-fin structure thermal management system. • The research findings emphasize the significance of considering mechanical vibrations in the design of the PCM-fin structure thermal management system, contributing to the development of lightweighting strategies in electric vehicle battery thermal management. The PCM-fin structure battery thermal management system (PCM-fin structure BTMS) has garnered significant attention due to its exceptional thermal performance. However, existing research has overlooked the presence of mechanical vibration that is inevitable in the operational environment of electric vehicle BTMS. This study aims to address this knowledge gap by comprehensively analyzing the effect of mechanical vibration on the thermal performance of the BTMS under high-temperature and high-rate discharge condition. Four novel findings are introduced for the first time: Firstly, mechanical vibration can significantly enhance the thermal performance of the BTMS, and the enhancement effect is more pronounced compared to the PCM-based BTMS without fins. Secondly, mechanical vibration also affects the ideal fin quantity for the BTMS. Under no vibration condition, the ideal quantity of fins is 10, while under mechanical vibration condition of 30 mm amplitude and 20 Hz frequency, the ideal fin quantity is 8. Thirdly, the thermal performance of the BTMS can be improved by increasing the vibration amplitude. Nevertheless, once a certain high value is reached, further increasing the vibration amplitude has a negligible effect on the enhancement of thermal performance. Lastly, even under low vibration frequency of 10 Hz, the BTMS can still perform well. However, as the vibration frequency increases, the thermal performance of the BTMS becomes progressively less sensitive to changes in vibration frequency. This work can provide guidance for the design and practical application of PCM-fin structure BTMS. [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]

In this study, the NTGK model was used to evaluate the thermal and electrical analyzes of the battery model and Taguchi design was implemented to investigate the main effects of four control factors in the battery thermal management process, those are inlet velocity, mixing ratio, ambient temperature, and C-rate. The Taguchi's L16 array was fabricated using varying control factors to obtain detailed battery temperature behaviors. As the discharge rate increased, the temperature value of the model increased, while the temperature value of the model decreased as the mixing ratio of the nanoparticle increased. As the inlet velocity of the refrigerant increases, the temperature value taken by the model decreases, while the higher the ambient temperature, the less the increase in the maximum temperature reached by the model. Also results showed that the most influential factor on both maximum battery temperature and temperature uniformity responses was the C-rate, while the least effective factor was the mixing ratio. It was found that an inlet velocity of 0.04 m/s, a mixing ratio of 5, a C-rate of 2, and an ambient temperature of 283 K will yield the lowest maximum battery temperature. The maximum battery temperature was 294 K under these conditions. On the other hand, to maximize the temperature uniformity, 0.04 m/s inlet velocity, 3 mixing ratio, 2 C-rate, and 313 K ambient temperature need to be set as processing parameters. The results showed that the C-rate has to be closely controlled during the discharge process and the influence of the mixing ratio is negligible. This study can be used as a robust guideline in the design of battery thermal management systems using nanofluids. • Thermal behavior of lithium-ion battery pack has been studied statistically by the Taguchi method. • Impacts of ambient temperature, C-rate, mixing ratio, and inlet velocity were studied for battery temperature. • C-rate was the main influential factor among the four assessed factors. • The confirmatory test validates the optimization process. [ABSTRACT FROM AUTHOR]

• An integrated system capable of cooling battery and cab is proposed. • Phase change cooling and liquid cooling are used to inhibit thermal runaway. • The parameters affecting the cooling performance of system are discussed. • A reasonable and economical parameter combination is determined. Nowadays, thermal runaway of lithium-ion battery is widely considered to be a serious hazard to the safety of electric vehicles. In order to effectively prevent thermal runaway, an integrated thermal management solution is proposed. Firstly, a few models of battery, air conditioning system, phase change cooling and liquid cooling are established, respectively. The temperature and heat are used to coupling each model. Then the effectiveness of models is validated by experiment. Finally, the cooling performances of this system are discussed. Under the circumstance of thermal runaway, the battery thermal management system can inhibit thermal runaway, and the battery temperature is reduced from 1208.17 to 304.82 K. In addition, the influences of the convective heat transfer coefficient and flow channel number on the cooling effect are also studied, and in order to ensure that the batteries have an appropriate temperature and reduce energy consumption, their values should be 20 W∙m−2∙K−1 and 5, respectively. When the vehicle is normally driving, the influences of different driving speeds, pump speeds and compressor speeds on the battery temperature are discussed, meanwhile, combined with the cooling effect of air conditioning, a reasonable and economic scheme is determined, that is, the pump speed is 2250 r∙min−1 and the compressor speed is 2500 r∙min−1, and under this scheme, the maximum battery temperature is only 35 °C, and the cab temperature can be reduced to the target temperature within 112 s. [Display omitted] [ABSTRACT FROM AUTHOR]

• Handled the battery thermal management of a novel helical channeled cylindrical Li-ion battery. • Tested the performance of nanofluid and hybrid nanoparticle-enhanced phase change material for BTMS. • Noticed that the cooling channel arrangement actively removes stored heat from PCM, and reduces PCM temperature. • Observed that the coolant circulation rate keeps the cell temperature below the safe range even with a lower circulation rate of 30 mL/min. Electric vehicles (EVs) have emerged as a viable alternative to Internal Combustion (IC) engine-powered vehicles, and efforts have been directed toward developing EVs that are more reliable and safer to operate. The safe working of EVs necessitates the use of an efficient battery cooling system. In this paper, cooling of cylindrical type Li-ion battery embedded with helical coolant channels is proposed. The effects of nanoparticles on removing heat from the battery cooling system have been investigated for four different nanoparticle concentrations: 0, 2, 5, and 10% of Al 2 O 3 in the base fluid. Two cases of base fluids are considered: phase change material kept in a concentric container surrounding battery volume and coolant water circulated through liquid channels attached to the outer walls of the PCM (phase change material) cylindrical container. This study presented the three configurations (i) base case PCM-WLC: battery cooling system with a cylindrical enclosure filled with RT-42 phase change material. (ii) base case nePCM-WLC: battery cooling system filled with nano-enhanced phase change material. (iii) nePCM-LC: battery cooling system with helical liquid channels and filled with nano-enhanced PCM. The nanofluid was circulated through the liquid passages connected to the PCM container. Results showed using the helical channels, the nePCM-LC arrangement efficiently removes accumulated heat from the phase change material and provides better battery cooling than straight rectangular channel-based BTMS (battery thermal management system). [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]

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]

• 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]

• A novel hybrid battery thermal management is proposed. • The mathematical model is established and then validated by the experiments. • The effectiveness of the proposed management system is proved experimentally. • The space of the proposed system is optimized via the mathematical model. A novel hybrid battery thermal management system, combining air-forced convection with phase change material, is proposed. The effectiveness of the system is proved experimentally. The maximum temperature difference and the maximum temperature are controlled within the optimum range in the proposed thermal management system even though the dynamic charge/discharge current rate is 4 C rate. Meanwhile, the thermal performance is also compared under the passive and active strategy. The result shows that the thermal performance under the active mode is obviously superior to that under the passive mode. Comparing with the passive mode, the maximum temperature difference and the maximum temperature in the active mode are reduced 1.2 °C and 16 °C under 3 C rate, respectively. Moreover, the mathematical model, based on the three-dimension heat transfer model coupled with the electrochemical model, is carried out and then validated with experimental data. Taking advantage of the mathematical model, the space of designed structures is further optimized. [ABSTRACT FROM AUTHOR]

• A thermal model of full-size-scale real EV battery packs is developed. • Thermal management of the battery pack cooled by channeled liquid flow is studied. • The thermal management system is fine-tuned by re-managing the flow distribution. • Parametric studies on discharge/charge C-rate and coolant flow rate are conducted. A numerical study with the aim of upgrading thermal performances of battery pack of electric vehicles is conducted for a full-size-scale battery pack with 22 modules (totally 5664 18650-type lithium-ion batteries contained) cooled by a channeled liquid flow. The heat generation of the battery is modeled based on experimental measurements. Experiments with one typical module (consisting of 180 batteries) of the pack, charging and discharging at different C-rate (2C, 1C or 0.5C) at a specified liquid flow rate, are first carried out. The experimental results in what concerns maximum temperature in the battery module is in good agreement with the corresponding numerical predictions, demonstrating the reliability/fidelity and consequent accuracy of the developed model. The battery thermal management system is then fine-tuned to re-manage the flow distribution among modules for the sake of improving the thermal uniformity across the pack. The effect on the pack thermal performance of different charge/discharge C-rates and flow rates are extensively investigated, and the results indicate that the pack is thermally well-performed during 1C/0.5C discharge/charge operation with a fluid flow rate of 18 L/min; increasing the discharge/charge C-rate worsens the battery pack's thermal characteristics and increasing the coolant flow rate makes the battery pack perform better. [ABSTRACT FROM AUTHOR]

• The LiFePO 4 overcharge process is divided into four stages. • ICA and DVA are used to reveal the internal mechanism when different gases are detected. • A Three-Level warning strategy is proposed based on the voltage, temperature, and gases. The thermal runaway (TR) of lithium-ion batteries (LIBs) is difficult to control when it reaches the late stage, which results in disastrous accidents, while the current means of early warning are biased late or inaccurate. Therefore, an early monitoring and warning strategy is necessary for LIB to mitigate TR. In this study, overcharge tests on LiFeO 4 batteries were conducted at various current rates (C-rates). The evolutions of voltage, gas, and temperature during overcharge were analyzed, and the TR process could be divided into four stages: Stage I (initial stage), Stage II (gas detected stage), Stage III (reaction accelerating stage), Stage IV (post-TR stage). The maximum surface temperature difference (Δ T max) exceeded 5 °C in Stage II. Incremental capacity analysis (ICA) and differential voltage analysis (DVA) were used to reveal the internal mechanism when different gases were detected in Stage II, and the safety performance of the LIB was affected severely. To avoid TR of LIB, it was necessary to start early warning in Stage II. A Three-Level warning strategy was proposed based on the voltage turning point (V TP), temperature, and the appearance of various gases in Stage II. A reliable warning before the TR was achieved by setting the threshold effectively, and the TR event was mitigated successfully. These findings provide a critical basis to enhance the monitoring and warning capability of the battery management system as well as battery safety. [ABSTRACT FROM AUTHOR]

—The accurate battery pack model is of great significance for the strategy development and functional verification of battery management system with the advantages of the high repeatability, fast state switching, and high safety. In this paper, a total of 49 dimensions of battery pack parameters are obtained through systematic experiments, including equivalent circuit model parameters and thermal characteristic parameters. Since the variational auto-encoder (VAE) can well preserve the correlation between parameters by training the neural network with small samples (95 samples), a novel battery pack inconsistency method is proposed based on VAE. Moreover, the parameter correlation and similarity are further considered based on the original loss function, which enables parameters generation for any amount of samples. The simulation results of the 95 and 500 generated samples illustrated that the proposed method can well maintain the similarity with the original parameters in both parameters distribution and parameters correlation, compared with the Copula-based and Metropolis-Hastings-based method. The average temperature error of the VAE-based method (0.02%) is much smaller than that of the Copula-based method (0.80%), and the temperature standard deviation error of the VAE-based method can be reduced to 4.53%, while the Copula-based method can reach 105.38%. [Display omitted] • Inconsistency modeling based on the variational auto-encoder. • Inconsistency statistics and modeling with 49 parameters. • Parameters generation considering the correlation and distribution characteristics. • Parameters generation for any amount of samples. • Inconsistency simulation of battery voltage and thermal characteristics. [ABSTRACT FROM AUTHOR]

The key to accurate simulation the thermal characteristics of lithium-ion batteries is to develop a reliable estimation model of the battery calorific value, which is very useful to design the thermal management system of the battery pack. This paper proposes a semi-empirical thermal model with virtues of high computational efficiency and precision for thermal analysis of the lithium-ion battery. In this model, a generalized and simple equation is developed to calculate the heat generation rate of the battery on the basis of its thermogenesis mechanisms. Two experimental fitting equations are acquired to estimate the battery ohmic resistance and entropy change coefficient, and a general formula is derived for the polarization resistance based on an approximate model of lithium diffusion process. Then, the semi-empirical thermal model is established for the battery by using the proposed computational method of the heat generation rate. The galvanostatic discharging and charging processes of a prismatic lithium-ion battery are separately simulated at the different currents and temperatures, and the corresponding experiments are conducted for the model validation. The results show that the battery temperatures simulated by the proposed model are good agreement with the experimental data. According to the calculation, the mean absolute deviations of the simulated battery temperatures are 0.27 °C for the discharging processes and 0.17 °C for the charging process under the orthogonal conditions of the operation currents (0.3C, 1.0C and 2.0C) and the ambient temperatures (10 °C，25 °C and 35 °C). Compared with the theoretically based model, the proposed model exhibits a higher computational accuracy in the most operating regions and improves calculation speed by more than 4.0 times at the same grid density and time step setups. Consequently, the semi-empirical model proposed in this work is well-suited to pre-assess thermal characteristics and thermal management system schemes of the large-scale battery pack due to its superiorities of easy implementation, high computational efficiency and high precision. • An accurate and simple heat estimation method is built for lithium-ion batteries. • A general formula is derived for the polarization resistance of the battery. • An improved semi-empirical model is developed for thermal analysis of the battery. • The proposed model improves calculation rate greatly without compromising precise. [ABSTRACT FROM AUTHOR]

Highlights • A plug-in OHP with flat-plate evaporator and tube condenser was developed. • Excellent heat transfer performance of plug-in OHP was achieved using ethanol-water mixtures. • EV battery temperature could be well-controlled below 46.5 °C based on the plug-in OHP. Abstract The development of highly-efficient, cost-effective, and reliable cooling schemes of electric vehicle (EV) battery is still a big challenge for massive commercialization of EVs. In this work, a proof-of-concept plug-in oscillating heat pipe (OHP) with flat-plate evaporator and tube condenser has been developed and experimentally tested for the potential applications in EV battery thermal management. Pure water, ethanol, and binary-fluid mixtures of them at different mixing ratios (MRs) ranging from 1:1 to 4:1 were used at volumetric filling ratios (FRs) of 30%, 40% and 50%. Owing to the zeotropic properties in phase transition and the complex molecular interactions between the ethanol component and water component, the OHP charged with ethanol-water mixtures exhibited better start-up and heat transfer performance. The average battery pack temperature could be controlled below 46.5 °C under the power input of 56 W. Besides, well-satisfied temperature uniformity was achieved on the battery module and the maximum temperature differences were mostly in the range of 1–2 °C. The complementary features for ethanol-water mixture thermo-physical properties and temperature/concentration gradients induced mass transport account for the OHP performance improvement. The novel plug-in OHP associated with desirable heat transfer performance provides a promising candidate for battery thermal management system. [ABSTRACT FROM AUTHOR]

• Recent advances in experimental and numerical studies on the suppression of thermal runaway of Li-ion batteries are reviewed. • The research progress of battery management system with thermal control and energy control is summarized. • The latest research results on li-ion battery safety devices are classified and analyzed and recommendations are made. • Electrolyte additives that are commercially available and have research potential are summarized. • Analyzed the advantages and disadvantages of various security strategies,proposed development prospects and directions. With its high energy density and long lifespan, li-ion battery (LIB) is now dominating the power source market for portable electronics such as smartphones, laptops, and electric vehicles. However, LIB electrolyte is flammable, and the diaphragm has low stability, making it easy to cause thermal runaway (TR). This paper reviews the research progress on TR propagation characteristics and prevention strategies. The study reviewed the analysis of practical measures of battery management systems, safety devices, flame retardants, electrolyte additives, and thermal absorption materials. It also discusses accidents related to TR of LIBs to emphasise the significance of TR to the entire accident investigation and analysis process. This paper can provide useful information on how to avoid TR-related accidents. [ABSTRACT FROM AUTHOR]

Indirect-cooling through cooling plate is a common way in the design of liquid-based battery thermal management system (BTMS), which can be divided into side-cooling and terminal-cooling according to the position arrangement of the cooling plates. In this work, comparative investigations are performed to analyze the specific merits and demerits between these two cooling structures and further understandings are provided for the heat dissipation mechanisms of BTMSs for the cylindrical battery modules. It is found that the side-cooling BTMS exhibits a better ability in the temperature rise control with a maximum temperature (T max) of 30.84 °C at the end of 1 C discharge compared with the terminal-cooling one where corresponding T max rises to 35.48 °C. But meanwhile, it encounters an inherent drawback on the temperature uniformity with a maximum temperature difference (Δ T max) of 5.76 °C after 1 h discharging due to the low radial thermal conductivity of the batteries, which forms a significant thermal gradient along its thermal transport paths. In contrast, corresponding Δ T max in the terminal-cooling case is only 2.86 °C. Effects of coolant velocity and channel number on the heat dissipation performances of the side-cooling and terminal-cooling BTMSs are examined and further, different strategies are proposed and tested for these two cooling structures respectively to ameliorate their heat dissipation performances based on their different characteristics in the heat transport paths and thermal field distributions. The results could provide useful guidance for the future design of BTMS for the cylindrical battery modules. • Investigations are performed on side-cooling and terminal-cooling BTMSs. • Side-cooling BTMS performs better in temperature rise control. • Terminal-cooling BTMS provides a superior temperature uniformity. • Strategies are proposed to further improve the heat dissipation performances. [ABSTRACT FROM AUTHOR]

• A comprehensive model based on battery aging effect is developed for MHP-BTMS. • A framework combing deep learning and multi-objective genetic algorithm. • BTMS shows poor cooling capacity due to SEI formation inside the aged battery. • Two optimization strategies are proposed for multi-objective optimization. • The trade-off between battery temperature and performance is achieved. Battery thermal management and electrochemical performance are critical for efficient and safe operation of battery pack. In this research, a multi-physics model considering the battery aging effect is developed for micro heat pipe battery thermal management system (MHP-BTMS). A novel multi-variables global optimization framework combining multi-physics modeling, deep learning and multi-objective optimization algorithms is established for optimizing the structural parameters of MHP-BTMS to improve battery thermal management and electrochemical performance simultaneously. It is found that MHP-BTMS fails to control the temperature of aged battery pack due to the higher heat generation caused by solid electrolyte interphase formation. After 1000 cycles, the maximum temperature and maximum temperature difference were increased by 3.32 K, 2.49 K, 2.04 K and 1.78 K, 1.46 K, 1.26 K, respectively. It is also found that the battery electrochemical performance during the cycling is highly related to battery thermal behaviors. MHP-BTMS with 0.004/s inlet velocity achieved the best performance in preventing SEI formation and battery aging effect, which was lower by 7.01 nm (SEI) and 1.65% (aging), 2.31 nm and 0.58% as compared to 0.002 and 0.003 m/s cases. Besides, MHP-BTMS with optimized inlet velocity, MHP arrangement and cold plate can improve cooling performance and electrochemical performance. Multi-variables global optimization can provide the optimal structure parameters of MHP-BTMS under the different combinations of weighted coefficients and optimization strategies to achieve the trade-off between battery thermal issues and electrochemical performance. In addition, it is demonstrated that the weighted coefficients and optimization strategies in this novel framework can be changed according to the actual needs in engineering applications. [ABSTRACT FROM AUTHOR]

• A novel petal-type battery thermal management system (BTMS) with dual phase change materials (PCMs) is proposed. • The thermal performance of the proposed BTMS at different ambient temperatures and discharge rates is investigated. • The environmental adaptability of 18650 Li-ion batteries is significantly improved. • The proposed BTMS is optimized by fin-reinforced heat transfer technology. Phase change material (PCM) cooling is a prominent approach for battery thermal management. However, its application scenario is severely limited by the narrow range of phase change temperature. When the temperature of PCM does not reach the phase change temperature range, it is either a pure thermal conductive material or a completely molten liquid material, neither of which can play a role in battery thermal management. The present study proposes a novel petal-type battery thermal management system (BTMS) with dual PCMs, which has significantly enhanced the environmental adaptability of the battery based on PCM cooling. The thermal performance of the BTMS at different ambient temperatures and discharge rates is investigated by numerical simulation methods. The results show that when the battery is discharged at 1∼5C at an ambient temperature of 25°C, the maximum battery temperature (T max) is 29.87°C, 32.89°C, 34.69°C, 36.84°C, and 39.41°C, respectively. When the battery is discharged at 2C at 20°C, 30°C and 40°C, the T max is 30.49°C, 34.16°C and 43.70°C, respectively. Compared with the other two conventional BTMSs using a single type of PCM, the thermal performance and environmental adaptability of the proposed BTMS is the best under the three typical ambient temperatures. Furthermore, the above BTMS is optimized using fin-reinforced heat transfer technology in this paper. Compared to the BTMS without fins, the optimized solution 2 with asymmetric fin arrangement reduces the maximum temperature difference (Δ T max) by 5.53% and 29.19% and the maximum temperature rise (Δ T mrise) by 36.15% and 42.76% at ambient temperatures of 30°C and 40°C. [ABSTRACT FROM AUTHOR]

[Display omitted] • The safety issues in LIBs and their impacts are discussed in depth. • Detailed classifications of various abuse conditions responsible for safety issues in LIBs are presented. • The advances in inner battery materials and outer materials for enhancing the overall safety of LIBs are presented. • Future research directions and potential solutions for LIBs safety are proposed. This review aims to summarize the safety concerns in LIBs, as well as the safety measures taken by various researchers and recent significant developments from a materials perspective. The advances in materials include material modifications, the development of novel materials, and the use of additives. The safety strategies of LIBs from advances in inner battery material as well as in outer material perspective have been reviewed. The advances in inner battery materials include improvements in cathode materials, and anode materials, using non-flammable electrolytes, flame-retardant additives, and overcharge protective additives, which help to improve the battery's safety from electrochemical and thermal abuses. The advances in the outer material to enhance battery safety involve the improvement in battery thermal management systems (BTMS) materials and battery protective casing materials. The BTMS enhances the LIB's safety from thermal abuses and the battery protective casing enhances the battery's safety from mechanical and thermal abuses. This paper provides valuable insight into strategies like material modification, novel material development, and additives used by researchers to increase the safety of LIBs as well as motivation for further advancement in high energy density batteries. [ABSTRACT FROM AUTHOR]

To optimize the working temperature of a vehicular lithium-ion battery, a double-layered I-shaped liquid cooling plate was designed. The upper layer channel uses coolant to dissipate heat, and the lower layer channel recovers the cooling liquid. The effects of three design variables (length ratio, width ratio, and channel spacing) and different inlet conditions on the heat transfer performance of the liquid-cooled plates were investigated. The results showed that the optimum maximum temperature and temperature uniformity were obtained at a length ratio of 0.70, width ratio of 0.85, and channel spacing of 2.0 mm approximately. Moreover, the thermal performances of the optimized structure and serpentine channel under the same channel area and inlet mass flow rate were compared. The optimized I-shaped liquid cooling plate can reduce the maximum temperature from 307.02 K to 303.94 K and the standard deviation of surface temperature from 0.80 K to 0.25 K. In addition, the pressure drop was reduced by 73.36% compared to that in the serpentine channel. The double-layered I-shaped channel can be used to improve the heat dissipation capacity of battery thermal management systems. • I-shaped liquid cooling plate was used for battery thermal management. • Compared the heat performance of I-shaped channel and serpentine (SP) channel. • The I-shaped liquid cooling plate reduces the temperature by 3.08 K. • The pressure drop in the I-shaped channel was 26.64% of that in the SP channel. [ABSTRACT FROM AUTHOR]

The mileage range of electric vehicles is still restricted incredibly due to the limitation of the onboard battery energy and long charging time; therefore, a comprehensive energy consumption optimization of the thermal management system is necessary to guarantee the normal use of electric vehicles. A test bench of integrated battery thermal management system for pure electrical transportation vehicles is established in this study. The optimal thermal management strategy is developed based on analyzing the energy-saving potential of thermal management components. When the battery system operates under real-vehicle operating conditions at representative ambient temperatures, the thermal management system characteristics applied to the proposed strategy are validated and analyzed. The experimental tests show that the proposed thermal management strategy can effectively reduce the energy consumption of the thermal management system under the premise that the battery temperature is controlled within the appropriate range, compared with the prototype vehicle. • The performances of thermal management system based on a real vehicle prototype test. • Analyzation on the energy-saving potential of the energy consuming components for the battery thermal management system. • Experimental investigation of a collaborative control strategy at the real vehicle application level. • Recommendations for optimizing the energy consumption of battery thermal management systems. [ABSTRACT FROM AUTHOR]

• Hybrid cooling using PCM plates and MCPs is numerically studied. • Using 3 PCM plates reduces the maximum battery temperature by 16.2 K. • Hybrid cooling system considerably improves temperature uniformity. • Adding PCM plates, the required water pumping power is decreased by up to 68%. • Using 3 PCM plates increased the time to battery overheating by up to 105%. Battery thermal management systems play a significant role in the safety, performance, and maintenance of electric vehicles. This paper proposes a new hybrid cooling system incorporated with phase change material (PCM) and liquid cooling to achieve high performance and safety for the pack of prismatic batteries. Each four battery cells are grouped as a module and placed between vertically orientated mini-channel cold plates. PCM plates are also placed horizontally between the battery cells. This new design is simple enough to be implemented easily in common cooling systems and could provide parallel cooling of the active and passive methods with subsequent improvement in thermal performance and system safety. Three-dimensional numerical simulations are validated against previous empirical and numerical works. The thermal performance, power consumption, and safety of the hybrid cooling systems are investigated in a variety of battery discharge rates and mini-channel inlet velocities using different numbers of PCM plates. Also, the system performance is tested in a real driving cycle. This new design could notably improve the battery thermal management characteristics. The maximum battery temperatures in the hybrid system with three PCM plates at 2C and 3C discharge rates were 5.6 K and 16.2 K lower than those without PCM plates. Besides, adding three PCM plates reduced the temperature difference by up to 33 % at 3C discharge rate. Another key finding was that at 3C discharge rate, by simultaneously utilizing three PCM plates and decreasing the fluid inlet velocity, the power consumption per battery cell is reduced by 68 % (from 1.187 mW to 0.0375 mW). Furthermore, considering the PCM plates as the emergency backup, the time to reach the critical temperature increased by 38 % and 105 % in the systems with 1 and 3 PCM plates, respectively. Testing in a real driving cycle reveals the superiority of the hybrid system over the active cooling method by peak shaving of the thermal loads and reducing thermal fluctuations and maximum temperature. This novel design for battery thermal management could provide high performance for batteries and reduce fabrication and maintenance costs. [ABSTRACT FROM AUTHOR]

• A model coupling electrochemistry, battery aging and heat transfer is developed. • The comparison between different coolants and nanofluids is performed. • BTMS shows poor cooling capacity due to SEI formation inside the aged battery. • Dispersing nanoparticle into BTMSs can improve thermal behaviors of aged battery. • Nanoparticle shapes have a significant effect on BTMS overall performance. In this research, a novel model considering electrochemistry, battery aging and heat transfer is developed for the design and optimization of battery thermal management system (BTMS) to ensure efficient and durable operation of batteries. The multiphysics behaviors in different working cycles of BTMSs are analyzed and compared. It is found that solid electrolyte interphase (SEI) formation inside the aged battery pack leads to the higher heat generation rate, which is the main reason that BTMSs only provide effective cooling performance in the initial working cycles but fail to control the battery temperature after 1000 cycles. Meanwhile, BTMS with water provides the lowest maximum temperature and temperature difference with the lowest pressure loss, which were 5.14 K, 4.33 K, 3.79 K and 3.94 K, 3.51 K, 3.2 K and 2772.7 Pa, 3980.9 Pa, 5271.8 Pa lower than those of BTMS with EO, were 2.17 K, 1.66 K, 1.37 K and 1.79 K, 1.43 K, 1.19 K and 544.4 Pa, 758.1 Pa, 984.3 Pa lower than those of BTMS with EG. In addition, BTMS with water also showed the best performance in controlling SEI formation and capacity fade, leading the highest average potential. Furthermore, dispersing nanoparticles into BTMSs can further enhance the cooling performance with a higher pressure loss, and BTMS with water-based nanofluid achieves the best performance. Besides, the cooling performance of BTMS increases with increasing volume fraction of nanoparticles, although the pressure loss is also higher. Nanoparticle shapes also have a significant effect on battery thermal behaviors and electrochemical performance. With brick-shaped nanoparticles, BTMS well cools the battery pack and reduces the battery capacity fade. For comparison, BTMS with spherical-shaped nanoparticles achieves the lowest pressure loss with providing favorable thermal manage for battery pack. [ABSTRACT FROM AUTHOR]