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

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

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

Highlights • Two FAC and SP heating strategies are designed for a PCM-based power battery pack. • Several evaluation factors are developed to compare the performance of the strategies. • The FAC strategy has been optimized by constructing a "close-ended" hot air cycle. • The SP heating strategy demonstrates the best heating performance. Abstract Constructing a complete battery thermal management (BTM) system consisting of both the heating and cooling functionalities is critical to guarantee the cycling life and safety of the power battery pack. In this work, we focus on the neglected issue of replenishing a cooling system with a heating functionality in a standardized power battery module. Two kinds of heating strategies, including forced air convection (FAC) heating and silicone plate (SP) heating are developed and then optimized on an advanced phase change material (PCM)-cooling based battery module. The experimental results show that the performance of the FAC heating strategies can be optimized by constructing a "close-ended" battery pack and increasing the fan number to recycle the waste heat and uniform the air flow field, respectively. The strategy of SP heating at 90 W demonstrates the most effective heating performance. For instance, an acceptable heating time of 632 s and a second lowest temperature difference of 3.55 °C can be obtained, resulting in a highest comprehensive evaluation factor of 0.42, much higher than those of other heating strategies (0.29–0.32). These encouraging results may raise concerns about constructing suitable cooling and heating functionalities simultaneously in a BTM system to realize a target oriented use, particularly those targeting various harsh operating environments. [ABSTRACT FROM AUTHOR]

Battery thermal management system (BTMS) is critical to dissipate the heat generated by the battery pack and guarantee the safety of the electric vehicles. Among the various battery thermal management technologies, the air cooling is one of the most commonly used solutions. In this paper, the cooling performance of the parallel air-cooled BTMS is improved through using the secondary vent. Computational fluid dynamics is introduced to calculate the flow field and the temperature field, finally evaluating the cooling performance of the BTMS. Mathematical analysis is conducted to explore the influences of the inlet air temperature and the heat generation rate on the battery cell temperature. The analysis results demonstrate that the temperature rise and the temperature difference of the battery pack are independent of the inlet air temperature, and are proportional to the heat generation rate for the situation of the constant heat generation rate. Subsequently, the influences of the position and the size of the secondary vent on the cooling performance of the BTMS are investigated through using the typical numerical cases. The results show that the position of the secondary vent strongly affects the maximum temperature and the maximum temperature difference of the battery pack. When the vent is on the convergence plenum, it is suggested to be located against the cooling channel around the battery cell with the maximum temperature. Compared to the vent located on the convergence plenum, the one against the outlet performs better. In this situation, the maximum temperature of the battery pack is reduced by 5 K or more, and the maximum temperature difference is reduced by 60% or more compared to the BTMS without vent for the situation of the constant heat generation rate. Moreover, the cooling performance of the BTMS becomes better as the size of the secondary vent increased, and similar conclusion can be obtained when the heat generation rate is unsteady. [ABSTRACT FROM AUTHOR]

Lithium-ion batteries are commonly used in hybrid electric and full electric vehicles (HEV and EV). In HEV, thermal management is a strict requirement to control the batteries temperature within an optimal range in order to enhance performance, safety, reduce cost, and prolong the batteries lifetime. The optimum design of a thermal management system depends on the thermo-electrochemical behavior of the batteries, operating conditions, and weight and volume constraints. The aim of this study is to investigate the effects of various operating and design parameters on the thermal performance of a battery module consisted of six building block cells. An electrochemical-thermal model coupled to conjugate heat transfer and fluid dynamics simulations is used to assess the effectiveness of two indirect liquid thermal management approaches under the FUDC driving cycle. In this study, a novel pseudo 3D electrochemical-thermal model of the battery is used. It is found that the cooling plate thickness has a significant effect on the maximum and gradient of temperature in the module. Increasing the Reynolds number decreases the average temperature but at the expense of temperature uniformity. The results show that double channel cooling system has a lower maximum temperature and more uniform temperature distribution compared to a single channel cooling system. [ABSTRACT FROM AUTHOR]

In this study, a hybrid liquid cold plate design containing Z-type parallel cooling channel and PCM/aluminum foam composite, in conjunction with a novel delayed cooling strategy, is proposed to provide a compact, lightweight, and energy efficient solution for battery thermal management systems (BTMSs). A total of nine different cold plate designs, including one baseline cold plate without PCM composite and eight hybrid cold plates containing PCM composite, are analyzed systematically to demonstrate the superior cooling performance of the proposed cooling design. Specifically, the average temperature of battery surface and total power consumption performance of each design are analyzed and compared at a battery discharging rate of 1C under both continuous and delayed cooling schemes. Subsequently, two selected designs with superior cooling performance as well as the baseline cold plate are further investigated to discuss the effectiveness of hybrid liquid cold plates for cooling batteries at high discharge rates. The results show that the optimum hybrid cold plate design, which only weighs half of the baseline cold plate, can provide more than 50% reduction in the total pumping power while achieving the same cooling performance (i.e., with the average battery temperature controlled within 40 °C) compared with the baseline cold plate at battery discharging rates of 1C, 2C and 3C. These results can potentially provide important guidance to the design of advanced cooling systems for lithium-ion batteries. • A compact and lightweight battery thermal management system is proposed. • A delayed cooling strategy is proposed and analyzed. • Cooling performances were compared between different designs numerically. • Optimum cooling system allows >50% reduction in power consumption and weight. [ABSTRACT FROM AUTHOR]

A kind of new hybrid thermal management system combining phase change materials with a series of liquid cooling is designed. The characteristics of the temperature change is studied experimentally and numerically when the ambient temperature is 25 °C to 40 °C. The results indicate that the temperature of phase change cooling system is reduced by 44.2%, 30.1% and 5.4%, respectively, compared with air cooling system, liquid cooling system and pure phase change material cooling system. To further enhance heat transfer, copper fins are added around the battery, the results shows that the maximum longitudinal difference of the battery temperature decreased by 69.7%. The research of this paper provides a theoretical basis for the thermal characteristics of hybrid cooling system and a design method with higher cooling efficiency and better temperature uniformity for the design of power battery thermal management system. • A new hybrid thermal management system combining phase change materials with liquid cooling is designed. • The simulation results are in good agreement with the experimental results. • The design structure of BTMS is optimized and validated again with experiments and simulation. • Hybrid thermal management system improves the temperature uniformity of the battery pack. [ABSTRACT FROM AUTHOR]

• Shark-skin bionic heat sink containing phase change material is developed. • The value of T max and ΔT of bionic heat sink are reduced by 5.49 K and 4.11 K. • The optimization method for the bionic structure height is proposed. • The ΔT of battery model is reduced to 1.22 K after the structure height optimized for seven times. • Environmental adaptability of the battery thermal management is studied. To improve the cooling efficiency and temperature consistency of battery module, a novel heat sink inspired by shark-skin microstructure is proposed to apply in battery thermal management system (BTMS), which is combined with axial air cooling and phase change material (PCM). The surface of the shark-skin bionic heat sink shows a number of regularly arranged and hollow raised structures. The cavities of these raised structures are filled with PCM. The effect of the structure parameters of shark-skin bionic structure on the cooling performance is investigated using validated computational fluid dynamic method. When the shape, height, length and interval of shark-skin bionic structure are triangular, 3 mm, 7 mm and 2.5 mm, respectively, the maximum temperature (T max) and temperature difference (ΔT) of battery module are control to 308.98 K and 3.21 K, while the consumption energy is 34.57 J. As compared with the normal case, the T max and ΔT of shark-skin bionic sink are reduced by 5.49 K and 4.11 K, respectively. Then, a method is proposed to optimize the height distribution of bionic structure. After the height distribution of bionic structure for battery module is optimized for seven times, its ΔT and energy consumption are reduced to 1.22 K and 26.81 J, while its T max is 309.19 K. Furthermore, the BTMS exhibits reliable cooling performance under different ambient temperatures and dynamic conditions. [ABSTRACT FROM AUTHOR]

• A compound liquid cooling system for battery thermal management was developed. • Temperature rise of the cooling water affected the temperature uniformity. • Heating power, flowing rate, filling ratio and inclination were investigated. To develop an efficient and practicable liquid cooling system for battery thermal management, a compound liquid cooling system combining a grooved aluminum vapor chamber with a one-through flow cold plate was proposed and its thermal performance experimentally was studied. The heating power, coolant flow rate, filling ratio and tilting angle of the vapor chamber were investigated, which had an impact on the thermal resistance and temperature difference on the heating surface. The results showed that the vapor chamber with a 20%~30% filling ratio had the smallest thermal resistance and preferable temperature uniformity in horizontal configuration. Due to the heat and mass transport of phases along the longitudinal direction inside the vapor chamber, the temperature difference of the heating surface arising from the temperature rise of the coolant could be suppressed effectively. To evaluate the suppressed effect on the temperature difference of the heating surface, the suppression ratio was proposed. The suppression ratio on the heating surface rose with the increase in heating power and the decrease in flowing rate. The thermal resistance and temperature uniformity of the vapor chamber deteriorated in tilting configuration. The vapor chamber at a positive tilting angle configuration performed better compared with that at a negative tilting angle configuration. At 20%~30% filling ratio, the suppression ratio of the temperature difference on the heating surface could be achieved at 0.78 under positive tilting angle configuration. [ABSTRACT FROM AUTHOR]

• A boiling-cooling system is proposed for large-format pouch lithium-ion cells. • The system has good performance for single-discharge processes in static mode. • The flow mode enables the system a stable performance during cyclic operations. • The temperature gradient is abnormally enlarged by the fast flow of the coolant. • The intermittent flow mode delivers an impressive cooling performance. To manage the undesirable temperature spike and significant temperature gradient developed on the large-format lithium-ion cell, we propose and experimentally demonstrate a boiling-cooling thermal management system using NOVEC 7000 as coolant for a large-format 20-Ah LiFePO 4 lithium-ion cell. It shows that the boiling-cooling system delivers excellent capabilities in reducing maximum temperature and improving temperature uniformity under the static mode even for the 4C discharge process. To enable the boiling-cooling system a stable cooling performance during cyclic operations, the flow mode is explored. The maximum temperature is successfully controlled over cycles but a large temperature difference between regions near cell bottom and tabs is observed, especially at high flow rates. To resolve issues of the static and flow modes, the intermittent flow mode is finally conceived for the boiling-cooling system, with which the temperature spike and maximum temperature difference are controlled to be less than 36 °C and 2 °C at 2C operation. Such an impressive cooling performance, combined with the substantially low pumping work, suggests that efficient thermal management of large-format lithium-ion cells can be achieved by the boiling cooling system operated with an intermittent flow mode, which takes full advantage of the large latent heat absorbed and the high heat transfer coefficient during the boiling process. [ABSTRACT FROM AUTHOR]

• A novel cooling scheme by nano emulsion and ultrathin cold plate was presented. • Nano emulsion with no subcooling and particle size of 335–360 nm was prepared. • Lower T max and ΔT were obtained cooled by nano emulsion than cooled by water. • Lower Pumping power than water of nano emulsion was obtained. • The T max and ΔT were below 50 °C and 4 °C in discharge of 9C. This paper presents a 4 mm ultrathin mini-channel cooling system based on a nano phase change material emulsion (NPCME) for prismatic Li-ion batteries under high-rate discharge. The NPCME has a larger specific heat capacity than water and no subcooling. Experiments were conducted to compare the cooling performance of water versus NPCME. The results indicate that NPCME can obtain a better cooling effect than water if the inlet temperature is below and near the melting point. At the discharge of 9C, the temperature and temperature difference of the battery pack cooled by 10 wt% NPCME-OP44E were 46 °C and 3.5 °C, compared with 49.5 °C and 4.8 °C under water cooling. Beyond that, the NPCME was able to reach the same cooling performance as water using lower pumping power. The pumping power of the 10 wt% NPCME-OP44E cooling system was only 18.5% that of the water cooling system when the cooling target for the battery temperature difference was 3.5 °C. With regard to charge-discharge duties, the 10 wt% NPCME-OP44E cooling system could limit T max and ΔT max to 45.5 °C and 4 °C throughout all four cycles. [ABSTRACT FROM AUTHOR]

• The novel radiator with bionic surface structure is proposed and applied to battery module cooled by an axial air-cooled BTM system. • The cooling performance of the battery module is enhanced when the inlet velocity of air increases, but the power consumption increases obviously. • The novel radiator thickness and the bionic surface structure height can effectively reduce the maximum temperature and the temperature difference of battery module. • When the optimal parameters of the bionic surface structure are used, the air cooling effect of the battery is the best. In order to enhance the cooling performance of air, a new type of radiator with bionic surface structure is proposed and applied to a cylindrical lithium-ion power battery pack with axial air cooling in this paper. The computational fluid dynamics (CFD) model of the battery module is established to study the effect of the inlet velocity and structure parameter of radiator with bionic surface structure on the cooling performance. It is found that when inlet velocity is higher than 0.8 m.s−1, the maximum temperature and the temperature difference of the battery module can be maintained within 308 K and 5 K during the 3 C discharge rate, respectively. Then, four structure parameters (thickness, shape, height, and length) of the radiator with bionic surface structure are optimized by the single factor analysis and the orthogonal test to enhance cooling performance and reduce power consumption. The results show that the thickness of plate is the most important parameter influencing the cooling performance and power consumption. Then, the height of bionic surface structure is the secondary parameter, and the shape of bionic surface structure is the parameter with a minimal impact on the BTMS. The best cooling performance can be obtained when the four structure parameters are 0.4 mm, trapezoid, 1 mm, and 61 mm, respectively. As compared with the original radiator, the temperature difference and power consumption of the optimized battery module are reduced by 8.1 % and 15.54 %, respectively, while the maximum temperature varies a little. The optimal case in this research can be widely applied to enhance the cooling performance in air-cooled BTMS. [ABSTRACT FROM AUTHOR]