Battery Thermal Management Research Articles

Numerical investigation on heat transfer characteristics in battery thermal management with phase change material composited by toroidal porous medium

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

Numerical Investigation of Thermal Management of a Large Format Pouch Battery Using Combination of CPCM and Liquid Cooling

As electric vehicles (EVs) gain market dominance, ensuring safety during the battery usage is crucial. This paper presents a new thermal management approach to address the battery heat accumulation challenge through a novel combination of composite phase change material (CPCM) with liquid cooling systems. An optimised hybrid cooling model is developed to evaluate the proposed battery thermal management system (BTMS) under high-temperature and high-power conditions. Benchmark studies are conducted to assess the impact of inlet position, inlet flow rate, and flow channel distribution on the cooling performance to achieve a uniform temperature distribution within the battery. The optimised BTMS, consisting of a five-cell battery pack, demonstrates a maximum temperature of 41.15 °C and a temperature difference of 4.89 °C in a operating condition at 36 °C with a discharge rate of 3 C. The BTMS outperforms the initial model, reducing the maximum temperature by 1.5%, temperature difference by 5%, and liquid fraction by 13%, with a slight (1.3%) increase in weight. The cooling performance is most efficient at a liquid flow rate of 0.1 m/s, minimising energy consumption. The proposed BTMS with CPCM-3 is also sufficient enough to keep the battery pack under a thermal runaway event. Overall, the theoretical simulation highlights the BTMS’s ability to effectively control battery temperatures and temperature differences, ensuring safe operation during high-temperature and high-power conditions in practical EV usage.

Development of bio-based flexible phase change materials utilizing lauric acid for battery thermal management systems

Lithium-ion batteries, serving as the cornerstone of electric vehicles, generate significant thermal output during their operation. This underscores the imperative need for the implementation of an appropriate battery thermal management system (BTMS). Extensive attention has been directed towards thermal-induced flexible phase change material (FPCM) within the domain of BTMS. However, it is notable that the predominant choice in contemporary practice for FPCM in BTMS remains paraffin (PA)-based, sourced from petroleum origins. This study utilizes an environmentally friendly bio-based phase change material (PCM), lauric acid (LA), to fabricate FPCM. The FPCM is skillfully crafted through the incorporation of styrene-ethylene-propylene-styrene (SEPS) and expanded graphite (EG) as supporting materials, forming the LA/SEPS/EG composite phase change material (CPCM). The addition of EG increases the thermal conductivity of CPCM by 4.97 times and enhances the leakage resistance. Furthermore, comprehensive assessments were conducted to evaluate the thermal performance, thermally induced flexibility, heat storage, release characteristics, and cyclic stability of the fabricated FPCM. In the battery discharge tests conducted at 2C/3C/4C rates, the battery containing FPCM consistently maintained its maximum temperature below 50 °C, with a minimal temperature difference of <1 °C, showcasing excellent thermal management performance.

Optimisation of a liquid cooling system for eVTOL aircraft: Impact of sizing mission and battery size

High-energy and -power density lithium-ion batteries (LiB) can enable viable electric vertical take-off and landing (eVTOL) aircraft for advanced air mobility provided that their battery thermal management system (BTMS) allows safe and efficient operations with acceptable weight penalties and capacity degradation. In this paper, we present the first optimisation of a liquid-cooled LiB BTMS for a notional tilt-wing reference eVTOL aircraft. Using an in-house developed BTMS sizing and battery degradation modelling algorithm, we investigate the effects of cruise altitude, hover duration, and battery pack oversizing on BTMS weight and battery lifetime. We minimise the BTMS weight, power, and battery temperature. The optimisation results reveal that varying cruise altitude has a negligible effect on BTMS design. While an extended hover duration does not adversely impact degradation, a considerably heavier BTMS is needed. The BTMS is about twice as heavy when the hover duration increases from one to seven minutes. Shortening the flight distance or oversizing the battery pack greatly impacts the battery lifespan. The battery capacity degradation rate halves when increasing the battery pack size by 20%.

Multi-objective parameter optimization of the Z-type air-cooling system based on artificial neural network

The performance of electric vehicles is significantly influenced by the battery thermal management system (BTMS). In this article, the Z-type air cooling BTMS is studied, and a method combining an artificial neural network (ANN) model as a surrogate model with non-dominated sorting genetic algorithm II (NSGA-II) for multi-objective optimization is proposed to enhance the heat dissipation performance. The ANN model is trained by using 1529 sets of numerical simulation data of Z-type air cooling system, and the fast and high-precision prediction of heat dissipation performance is realized, which effectively avoids the repeated calculation of CFD. The design variables studied include geometric structure parameters and inlet wind speed (vinlet), and the target variables are maximum temperature (Tmax), temperature difference (ΔTmax) and pressure loss (ΔP). From the new perspective of genetic evolution process of NSGA-II, it is proved that the design of tapered inlet and outlet is better than that of flat and expansion outlet, the wide channel near the inlet and narrow channel near the outlet are more conducive to the improvement of heat dissipation performance. Further analysis shows that there is a linear relationship among vinlet, Tmax and ΔP in the Pareto solution set of Z-type air-cooling system, which simplifies the Pareto model effectively, and engineers can predict the optimal performance of BTMS by this relationship. In addition, through sensitivity analysis, it is found that in the Z-type BTMS, the operating parameter vinlet has the greatest influence on the heat dissipation performance and pressure loss, while the geometric parameters have less influence. Compared with the benchmark case, the optimized design scheme reduces Tmax, ΔTmax and ΔP by 1.97 K, 6.32 K and 2.82 Pa, respectively, which significantly improves the heat dissipation performance.

Multiphysics-informed thermal runaway model for estimating the pressure evolution induced by the gas formation in a lithium-ion battery

This study proposes a multiphysics-informed thermal runaway (TR) model for a lithium-ion battery to replicate TR phenomena by considering the evolution of the SOC and SOH, thermodynamics, chemical reactions, pressure evolution, vent, and ejection phenomena. This versatile model contributes to estimate both temperature and pressure evolutions, and thereby understand the underlying multiphysics of TR better by deploying three key features. First, the proposed model accounts for TR dependency on the SOC and SOH of a cell by controlling kinetic parameters of positive and negative active materials. Second, simple yet accurate governing equations of vent and ejection phenomena are coupled to complex and nonlinear thermodynamics, elaborating the TR characteristics predicted by the proposed model. Third, the proposed model directly couples the chemical reactions of the five main components to predict gas formation (CO, C2H4, CO2, H2, and CH4) and evolution because the pressure evolution is initiated by different reaction ratios of these components. Quantitative experimental validation with both nickel-manganese-cobalt and lithium–iron-phosphate cells shows that the maximum error for prediction of temperature and pressure evolution is 2.2 and 14.5 % respectively, confirming the accuracy and robustness of the proposed model. This study also includes in-depth discussions for the applications of the proposed model, including the early detection of TR and gas monitoring. These insightful discussions not only reveal the effectiveness of the proposed model but also provide guidelines for optimal battery thermal management strategies.

Evaporation performance of propane in offset strip-fin plate heat exchanger for refrigerant-based battery thermal management in electric vehicles

This study investigates the potential of refrigerant-based cooling (RC) using a natural refrigerant (propane) and lightweight energy-efficient brazed plate heat exchangers (PHXs) in the battery thermal management systems (BTMSs) of the electric vehicles (EVs). Experimental assessments were conducted to analyze the evaporative heat transfer characteristics of propane within an offset strip-fin flow-structured PHX under various operational conditions resembling the BTMS operation. The battery discharge rates, often represented by the C-rate, are determined by the discharging current relative to the battery's capacity. In this study, a heat generation model based on the C-rate was employed to evaluate the thermal performance of the battery. Parameters, such as mass flux (G) at 30–70 kg/m2s, discharge rates (C-rate) of 1, 1.25, and 1.5C, and saturation temperatures (Tsat) of 16–24 °C were explored, with the inlet vapor quality (xin) in the range of 0.1–0.8. The influence of G and Tsat on the heat transfer performance showed that higher G values (60 and 70 kg/m2s) achieved the maximum heat transfer coefficients (HTC), which resulted in impractical pressure drops (PD). While higher HTC and lower PD were observed at a Tsat of 24 °C, concerns about increased inner wall temperature (Tiw) and safety emerged at this temperature. Hence, the optimum conditions of G (30 and 50 kg/m2s) and Tsat (16 and 20 °C) were investigated. The average HTC increased by 29, 27, and 21 % at 50 kg/m2s compared to that at 30 kg/m2s with Tsat of 20 °C, resulting in an average of 0.7, 0.9, and 1.2 °C reduction in the Tiw for C-rates of 1.5, 1.25, and 1C respectively. Compared to the Tsat of 16 °C, higher HTC and lower PD were observed at 20 °C, however, the Tiw was in the range of 21.12–20.47 °C for Tsat of 20 °C, which is 3.5–4 °C higher than that at Tsat of 16 °C. The results from the critical heat transfer coefficient analysis showed that the peak heat dissipation with minimal wall temperature was attained with optimal xm of 0.45–0.5, which enhanced the cooling efficiency for both the G values of 30 and 50 kg/m2s, and both the Tsat values (16 and 20 °C).

Temporal numerical analysis of beeswax PCM melting in a cube geometry subjected to a constant wall temperature condition

The ability of phase change materials (PCM) to store thermal energy has gained wide application area, like battery thermal management, solar water desalination and many other. The melting process of beeswax phase change material within the cube geometry with constant wall temperature (65 °C) boundary condition has been investigated using solidification and melting model. The fluid flow and heat transfer governing equations are solved using second order finite volume scheme. A PRESTO algorithm is applied for pressure-velocity coupling. The convergence criteria of 10−10 have been selected for energy equation, while 10−8 is selected for both momentum and continuity equations. The results like percentage variation along length-height and height-width plane for transient liquid fraction and temperature has been plotted, along with velocity streamlines within the cube geometry. From the obtained results it is concluded that the melting fraction and temperature of beeswax PCM is different in different planes and the major factors which affect the complete melting process is wall temperature, and the geometry. A difference of more than 0.1 °C in temperature has been recorded between mid-length-height and height-width plane while a difference of more than 2% in liquid fraction of PCM is observed. Even the uniformity of temperature and liquid fraction is notably influenced and vary along length, height, and width of cube geometry. Thus, it is concluded that melting process of PCM may affect the ability to store and release the heat energy which further affect the performance parameters of applied physical system.

Operando Entropy Profiling of Sodium-Ion Batteries via Optical Fiber Sensing for Thermal Management and Ageing Monitoring

Batteries are essential for the electrification of transport and the replacement of internal combustion engines. Thermodynamics was largely established with the development of the engines, and this knowledge has been applied to batteries for years. In particular, entropy profiles are sensitive to structural changes and are useful for diagnosing and understanding battery ageing. However, entropy profiling of aged batteries is mainly limited to the potentiometric method, which makes the technique in situ and time-consuming. Herein, we rely on optical fiber calorimetry to perform operando entropy profiling of commercial sodium-ion cells. Firstly, we directly compare the entropy profile of sodium-ion Na3V2(PO4)2F3/hard carbon (NVPF/HC) chemistry against those of commercialized lithium-ion chemistries, highlighting the uniqueness of NVPF/HC chemistry in battery thermal management. Operando entropy profiling of NVPF/HC chemistry further elucidates the structural degradations that take place during cycling and provide features that can be important indicators of the battery’s state of health. This work reintroduces thermodynamic analyses as a valuable tool for batteries and spotlights the new horizons offered by the convergence of battery sensing, thermodynamics, and other disciplines.

Flame retardant composite phase change materials with MXene for lithium-ion battery thermal management systems

A high-quality thermal management system is crucial for addressing the thermal safety concerns of lithium ion batteries. Despite the utilization of phase change materials (PCMs) in battery thermal management, there is still a need to raise thermal conductivity, shape stability, and flame retardancy in order to effectively mitigate battery safety risks. This study investigates a flame-retardant PCM composed of polyethylene glycol, expanded graphite, MXene, APP (ammonium polyphosphate), and ZHS (Zinc hydroxy stannate). The properties of the PCM and its thermal management performance during the operation of batteries are explored and evaluated. The results demonstrate that the incorporation of MXene enhances both the enthalpy of phase transition and thermal conductivity of PCM. Furthermore, the synergistic flame retardancy of APP and ZHS increases the carbon residue content, enabling PCM to achieve a V0 flame retardant rating. PCM exhibits a noticeable cooling effect on the battery temperature, reducing the highest temperature of the battery module to 57.03 °C during 3C discharge while maintaining a temperature difference of within 5 °C. This research contributes valuable insights into the potential use of PCMs with MXene in thermal management systems for batteries, with the aim of improving lithium batteries safety during operation.

Study on the potential of multi-performance enhanced phase change materials in battery thermal management

Lots of research has proved the effectiveness of flexible composite phase change material (CPCM) in thermal management of electronic products. However, the key properties of materials, e.g., flexibility, thermal conductivity and resistance are mutually restricted, further limiting its application in practical thermal management engineering. Unfortunately, the above performance has not been comprehensively considered in the existing research. In this work, a novel shape-stabilized flexible CPCM with considerable comprehensive performance was proposed. Styrene-b-ethylene-co-butylene-b-styrene (SEBS) was used as a flexible matrix to expand the flexible temperature range, and ALN was used to improving the thermal conductivity (0.786 W·m−1·K−1), strengthening the three-dimensional thermal conductivity skeleton of expanded graphite and improving the resistivity to 5.16 × 1010 Ω·m. Meanwhile, the CPCMs showed excellent performance in cycle stability, the melting enthalpy only decreased by 1.29 % after 500 cycles. The result of thermal management exhibited that the maximum temperature (Tmax) and maximum temperature difference (ΔTmax) of the battery at 6C discharge rate were 43.64 °C and 2.39 °C respectively with the help of CPCMs. More importantly, it was also obtained that the thermal conductivity played a major role in the battery temperature control in the long-term operation, the increase of the thermal conductivity reduced ΔTmax by 68.05 %. This work will further provide technical support for the practical engineering application of flexible CPCMs for electronic thermal management.

A novel hybrid liquid-cooled battery thermal management system for electric vehicles in highway fuel-economy condition

A hybrid liquid cooling system that contains both direct and indirect liquid cooling methods is numerically investigated to enhance the thermal efficiency of a 21700-format lithium-ion battery pack during the discharge operation. One of the most significant challenges that liquid-based direct cooling systems face is the filling of the heat capacity of the coolant during the cooling process, hindering the effective dissipation of heat generated from batteries. This paper aims to introduce a battery thermal management system to address this issue. In the present study, the influences of immersion and flow cooling methods using HFE-7100 and water (as working fluids), inflow velocities of cooling channel and tubes, parallel and counter flow, battery cell space, and highway fuel-economy test on the temperature distribution of batteries were studied comprehensively. Results highlight that immersion cooling with water outperforms due to the lower thermal conductivity of HFE-7100. In addition, Flow cooling significantly reduces the battery pack's highest temperature and non-uniformity compared to immersion. According to the numerical results, using cooling tubes as an indirect cooling system integrated with the direct flow cooling method can remarkably improve the thermal efficiency of the battery pack. Moreover, results exhibited that counterflow between cooling tubes/channels can keep the highest temperature and temperature variance of Li-ion battery package below 32.15 °C and 3.04 °C, respectively. Varying battery cell spaces shows that a 14 mm space reduces the battery package's highest temperature by 1.54 °C compared to a 10 mm space. Finally, highway fuel-economy condition is applied to the simulations of this study, illustrating the effect of an innovative hybrid battery thermal management system for a 21700-type Li-ion battery pack.

High flame retardant composite phase change materials with triphenyl phosphate for thermal safety system of power battery module

The thermal safety of battery pack has attracted much attention accompany with the growth in electric vehicles (EVs) in recent years. Although various battery thermal management systems (BTMS) are investigated by many research, the thermal runaway propagation (TRP) of battery packs under extremely abused conditions is just at the level of structural design and theoretical model. How to explore an innovative technology to improve the integrated thermal safety including the BTMS and TRP is still a great challenge. In this study, a multifunctional flame-retardant paraffin (PA)/styrene-butadiene-styrene (SBS)/expanded graphite (EG)/methylphenyl silicone resin (MPS)/triphenyl phosphate (TPP) composite phase change material (PSEMT) has successfully prepared. Besides, it has applied in 26650 ternary power battery modules. When the proportion of MPS and TPP is 1:2, the experimental results reveal that PSEMT possesses high thermal stability, and excellent flame-retardant properties owing to synergistic flame-retardant effect with phosphorus and silicon. Further, the cylindrical 26650 battery module with PSEMT exhibits optimum thermal management performance. Even at 2C discharge rate after ten cycles, the maximum operating temperature of battery module can still be maintained below 50 °C, and the maximum temperature difference is controlled within 4.6 °C. Additionally, it displays an excellent thermal runaway suppression through triggering by multiple heat sources. What's more, the battery with PSEMT can suppress the peak temperature and delay the occurrence time of thermal runaway. Therefore, it can be induced that the battery module with PSEMT can effectively avoid heat accumulation and significantly reduce its thermal safety risk. This study offers a new solution with promising prospects from the perspectives of energy storage and EVs, for balancing the temperature inconsistencies in batteries and suppressing thermal runaway in the battery packs.

Optimization design of a hybrid thermal runaway propagation mitigation system for power battery module using high-dimensional surrogate models

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

Numerical heat generation analysis of the tabbed and novel tabless designs of cylindrical-type lithium-ion batteries

The heat generation behaviours of a traditional tabbed cylindrical lithium-ion (Li-ion) battery are known to greatly affect its performance, cycle life, and safety. In this study, we explore the heat generation behaviours of the tabbed and novel tabless designs of a 21,700 cylindrical cell with graphite anode and NCA/LiNi0.8Co0.15Al0.05O2 cathode, by coupling the discreet layers of a three-dimensional (3D) disassembled electrochemical (EC) model with a two-dimensional (2D) axisymmetric heat transfer (HT) model. The respective heat generation mechanisms of each battery components of tabbed and tabless designs are first compared, and it is observed that the tabbed design generates significantly more heat than the tabless design, with the negative current collectors (NCC) in the tabbed design accounting for over 80 % of the total heats at 1C-rate. Also, the tabless design reduces the cell voltage drop due to its lower ohmic impedance and promotes a more homogenous cell temperature than the tabbed design. Next, the effects of particle size (ω) for the tabless design on the ohmic, reversible, and polarization heats of the battery’s electrodes are investigated at a high discharge rate of 10C, and the results show that polarisation heat decreases significantly in both electrodes as ω decreases. At the Negative Electrode (NE), the ohmic heating decreases initially as ω decreases because the battery is not drawing significant current. As the current drawn increases, Li-ion transport resistance also increases and at depth of discharge (DoD) = 36 %, a reverse in the trend is observed leading to an increase in Ohmic heating up to the end of life. In contrast, the ohmic heating at the Positive Electrode (PE) increases throughout the discharge process as ω decreases. For the reversible heat, the heat is negative in the NE side initially and fluctuates with ω towards the end of life (DOD = 88 %) when it changes from heat sink to heat source, whereas in the PE it remains unchanged for all ω throughout the discharge process. The resulting temperature drop is caused by the increase in the overall reversible heat sink effect in the NE side, as well as the weakened polarization heat in both electrodes. On the other hand, miniaturising the electrode thickness (η) causes a considerable decrease in ohmic heating in both electrodes resulting in larger temperature drops and elevated voltage curve. This study provides relevant insights in support of the development of battery thermal management systems (BTMS) for the tabbed and novel tabless batteries in a realistic environment.

Live update of the battery thermal parameters for reliable short-term temperature model

Battery Thermal Management systems are a key component for modern electric vehicles. Many systems use advanced models for temperature prediction and for the optimal cooling or heating strategies. Thermo-electric characterizations of cells and battery packs are performed inside the research labs to properly tune the models before uploading them to the on-board control units. However, these data depict the storage system under brand new conditions. Throughout the vehicle life, the battery pack behavior can change because of several factors related to the surrounding environment and operating conditions. Moreover, in the case of battery swap strategies, that consist in the pack replacement, the temperature model would be totally unsuitable for the new installed one. Therefore, an on-board, online procedure for the evaluation and update of the battery thermal behavior could be needed. This work presents a method for the evaluation of the battery thermal parameters on-board, during real driving cycles using data that are available in the vehicle control unit. The main novelty of this work consists in the solution to combine and assist the temperature model in the vehicle control units with an optimization algorithm which does not increase the computational load and provides reliable thermal parameters estimations. To demonstrate the potential of this methodology, the evaluated parameters are used in a short-term temperature model suitable for control strategies for battery thermal management systems. Concerning the first part, an optimization procedure is run for different driving cycles, recorded using a GPS system on a real vehicle. Finite-difference method is used to identify the convective heat transfer coefficient and the specific heat capacity of a single cell that composes the battery pack in laboratory tests. Then, the reliability of the estimated thermal parameters is analyzed reducing the number of source records and using the remaining cycles for the validation. Four worst cases have been identified and used to check the performance of the model prediction. Considering a temperature measure tolerance of 6 %, up to 93.75 % of the estimated values is reliable. Finally, the thermal parameters are used in a short-term temperature model for control strategies. The results highlight the good performance of the model in the estimation of the on-board battery temperature during a real driving cycle, simulating the future heat generation on the basis of the current load demand of the previous time step. The temperature predictions of the short-term model have been also tested in the worst cases denoting a good reliability; the maximum error is + 5 % in overestimation and 3 % in underestimation. Temperature predictions would help in the feed-forward control of battery thermal management systems for a smooth and safe operation of future electric vehicles. Moreover, this solution can be adopted for even more complex cooling methods, enhancing the update of the battery pack characteristics also in case of deterioration or battery swap.

Electro-thermal performance evaluation of a prismatic battery pack for an electric vehicle

Abstract In recent years, electric vehicles (EVs) have grown in popularity as a viable way to reduce greenhouse gas emissions by replacing conventional vehicles. The need for EV batteries is steadily increasing. An essential and expensive part of electric transportation is the battery. The operating temperature of the lithium-ion (Li-ion) battery significantly impacts the performance of the EV battery pack. Battery packs undergo temperature fluctuations during the charging and discharging procedures due to internal heat generation, necessitating an examination of the temperature distribution of the battery pack. The geometrical spacing between cells is considered larger and identical and is kept open on two sides for free air circulation. A novel battery thermal management system (BTMS) design is required to effectively dissipate heat from the prismatic battery pack module. The electro-thermal behaviour of the prismatic Li-ion battery pack module was investigated based on the high charge/discharge rate. This study presents the development of a three-dimensional free open-source OpenFOAM computational fluid dynamics model for prismatic cell battery packs that simulates heat generation, air flow field, and temperature distribution across the width and depth of the battery pack module. The prismatic battery pack simulation results are compared with the experimental and simulation results of the cylindrical battery pack. It was also revealed that prismatic cells generate more heat on the backside, requiring battery packs to have increased cooling and space between individual cells to ensure sufficient air circulation for cooling and gas removal. The BTMS is improved by designing with increased space among the prismatic battery cells as compared with the conventional prismatic cell battery pack design.

Flexible and Thermally Conductive Phase-Change Films with a Two-Level Network for Dual-Mode Thermal Management of Batteries

Flexible and Thermally Conductive Phase-Change Films with a Two-Level Network for Dual-Mode Thermal Management of Batteries

Thermal Performance Analysis of a Prismatic Lithium-Ion Battery Module under Overheating Conditions

Thermal runaway (TR) of lithium-ion batteries has always been a topic of concern, and the safety of batteries is closely related to the operating temperature. An overheated battery can significantly impact the surrounding batteries, increasing the risk of fire and explosion. To improve the safety of battery modules and prevent TR, we focus on the characteristics of temperature distribution and thermal spread of battery modules under overheating conditions. The heat transfer characteristics of battery modules under different battery thermal management systems (BTMSs) are assessed. In addition, the effects of abnormal heat generation rate, abnormal heat generation location, and ambient temperature on the temperature distribution and thermal spread of battery modules are also studied. The results indicate that the BTMS consisting of flat heat pipes (FHPs) and bottom and side liquid cooling plates can effectively suppress thermal spread and improve the safety of the battery module.

Flexible phase change materials based on hexagonal boron nitride (hBN) surface modification and styrene-butadiene-styrene (SBS)/low-density polyethylene (LDPE) crosslinking for battery thermal management applications

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