Experimental investigation of thermal management system for lithium ion batteries module with coupling effect by heat sheets and phase change materials

Some potential safety risks for lithium ion battery such as overheating, combustion, and explosion occurred in practical application may cause accidents of electric vehicles. Phase change material (PCM)‐based thermal management system was demonstrated as a feasible approach. However, the batteries have to endure various environment and climate, which would not work normally under cold area. Especially when the surrounding temperature falls to below 10°C, which can bring about the energy and power of Li‐ion batteries rapidly reducing. In this study, a coupling heating strategy of the PCM‐based batteries module with 2 heat sheets at low temperature was proposed for batteries module and cannot only balance the temperature among different batteries in the module but also ensure to pre‐heat the batteries module at low temperature. The experiment displayed that 7% of EG in paraffin‐based composite PCMs was the best proportion for batteries module, considering both fluidity and thermal conductivity factors. In addition, the temperature difference of PCM‐based batteries module was 2.82°C, while that of the air‐based one was 14.49°C, which was 5 times more than former, exhibiting an excellent performance in balancing temperature uniformly, and was beneficial for prolonging the lifespan of batteries. The coupling heating strategy‐based PCM with heat sheets provided as an extremely promising technology for lithium batteries module at low temperature.     

Experimental investigation on thermal performance of silica cooling plate‐aluminate thermal plate‐coupled forced convection‐based pouch battery thermal management system

The power battery as an indispensable part of electric vehicle has attracted much attention in recent years. Among these, the lithium‐ion battery is the most important option due to the high energy density, good stability, and low discharge rate. However, the thermal safety problem of lithium‐ion battery cannot be ignored. Therefore, it is very necessary to explore an effective thermal management system for battery module. Here, a thermal silica cooling plate‐aluminate thermal plate (SCP‐ATP) coupling with forced convection air cooling system as a thermal management system is proposed for improving the cooling performance of pouch battery module. The results reveal that the heat dissipating performance and temperature uniformity of pouch battery module with SCP‐ATP are greatly improved compared with other thermal management systems. Moreover, the highest temperature can be controlled below 50°C, and the temperature differences can be maintained with 3°C when the SCP‐ATP coupling forced convection is utilized to enhance the heat transfer coefficient. Furthermore, considering the cooling effectiveness and consumption cost comprehensively, the optimal air velocity of the SCP‐ATP coupling forced convection cooling system is 9 m/s. In addition, the SCP‐ATP filling with different proportions of acetone has also been investigated for pouch battery module, indicating that 50% acetone exhibited a better heat transfer effect than the 30% one. Therefore, this research would provide a significant value in the design and optimization of thermal management systems for battery module.     

A review of novel thermal management systems for batteries

In the recent years, significant developments in the electric batteries have made them one of the most promising storage technologies for electrical energy. Among the various rechargeable batteries that are developed, lithium ion batteries stand out due to their capability of storing more energy per unit mass, low discharge rate, low weight, and lack of a memory effect. The advantages that batteries offer have promoted the development of the electric and hybrid electric vehicles. However, during charging and discharging processes, batteries generate heat. If this heat is not removed quickly, the battery temperature will rise, resulting in safety concerns and performance degradation. Thermal management systems are developed to maintain the temperature of the battery within the optimum operation range. This review paper focuses on novel battery thermal management systems (BTMSs). Air, liquid, phase change material, and pool‐based BTMSs are considered. Air‐based thermal management systems are discussed first. Liquid cooling systems and phase change‐based systems are discussed subsequently, and then the recently proposed evaporating pool‐based thermal management system is considered.     

Investigation on the thermal performance of phase change material/porous medium‐based battery thermal management in pore scale

With the latent heat, the phase change material (PCM) is widely used in battery thermal management (BTM) to control the temperature. In this paper, the porous medium is employed to enhance the heat transfer of PCM. The lattice Boltzmann model for PCM/porous medium in pore scale is considered, where the mesh system with porous medium (fixed point) is generated by quartet structure generation set (QSGS) method. The effects of the Rayleigh number and porosity on the heat transfer process in BTM are investigated. The results show that decreasing the porosity will accelerate the melting rate. When the porosities are 0.9, 0.8, 0.7, and 0.6, the total melting times are decreased by 23.7%, 43.3%, 58.0%, and 75.4%, compared with pure PCM. The heat is transferred through the high‐conductivity framework. The natural convection in the porous medium is weak, and the conduction is the dominated heat transfer. As a result, the area of solid–liquid interface will be increased, and the heat‐transferred rate is accelerated. However, when the Rayleigh number is raised to 10⁵, applying the porous medium with porosity of 0.9 will increase the total melting time, resulted from the stronger natural convection of PCM. The present study is helpful for design of PCM/porous medium‐based BTM.     

基于液体介质的电动汽车动力电池热管理研究进展

电动汽车在节能减排上具有很大的潜力和优势,但其性能受动力电池的制约,而温度又会影响电池的安全和寿命。因此,为保证电动汽车的综合性能,需配置合理的电池热管理系统。由于液体冷却具有较好的降温效果,采用液体介质对电池进行热管理近年来逐渐引起重视。本文介绍了基于液体介质的电池热管理基本原理,综述了液体介质应用于电池热管理的研究进展,并重点介绍了新型热管在电池散热方面的应用,同时指出了目前液体介质冷却电池时存在的一些问题。     

A review on lithium-ion power battery thermal management technologies and thermal safety

Lithium-ion power battery has become one of the main power sources for electric vehicles and hybrid electric vehicles because of superior performance compared with other power sources.In order to ensure the safety and improve the performance,the maximum operating temperature and local temperature difference of batteries must be maintained in an appropriate range.The effect of temperature on the capacity fade and aging are simply investigated.The electrode structure,including electrode thickness,particle size and porosity,are analyzed.It is found that all of them have significant influences on the heat generation of battery.Details of various thermal management technologies,namely air based,phase change material based,heat pipe based and liquid based,are discussed and compared from the perspective of improving the external heat dissipation.The selection of different battery thermal management (BTM) technologies should be based on the cooling demand and applications,and liquid cooling is suggested being the most suitable method for large-scale battery pack charged/discharged at higher C-rate and in high-temperature environment.The thermal safety in the respect of propagation and suppression of thermal runaway is analyzed.     

3D electro‐thermal modelling and experimental validation of lithium polymer‐based batteries for automotive applications

This article presents an electro‐thermal model of a stack of three lithium ion batteries for automotive applications. This tool can help to predict thermal behaviour of battery cells inside a stack. The open source software OpenFOAM provides the possibility to add heat generation because of Joule losses in a CFD model. Heat sources are introduced at the connectors and are calculated as a function of battery discharge current and internal resistance. The internal resistance is described in function of temperature. Simulation results are validated against experimental results with regard to cooling air flow field characteristic and thermal behaviour of the cell surface. The validation shows that the simulation is capable to anticipate air flow field characteristics inside the battery box. It also predicts correctly the thermal behaviour of the battery cells for various discharge rates and different cooling system conditions. The simulation supports the observation that batteries have a higher temperature close to the connectors and that the temperature increase depends highly on discharge rate and cooling system conditions. Copyright © 2016 John Wiley & Sons, Ltd.     

Thermal behavior of lithium batteries used in electric vehicles using phase change materials

Electric vehicles equipped with lithium-ion batteries face a huge challenge, and the fact that battery life is very much affected by the temperature conditions of their operating environment, the heat reduces battery life cycle and time and increases the likelihood of thermal degradation and explosion. This problem has forced engineers to cool the battery. The methods used to cool the battery includes a cool water method (passing water or a dielectric fluid from the battery pack), cooling air (blowing air into the battery compartment by the fan), using a refrigeration system (such as cooling screens), and the use of phase-change material (PCM). In this research after reviewing and referring to valid authorities, it was found that PCMs are superior to all three other cooling systems because the air-conditioning system is not very desirable due to the high-temperature gradient between the battery cells. Also, cooling and refrigeration systems with refrigerant gases will also cost a very high cost on the electric car. The results of the studies showed that the cooling the battery using the PCM creates a similar temperature profile between the batteries in the battery pack, the temperature gradient is much smaller than the air cooler and cool water, and the final cost will be much lower. Also, it performs more efficiently in high-speed road dynamics and increases the battery life of an electric car or electric hybrid.     

Thermal analysis of high‐power lithium‐ion battery packs using flow network approach

High‐power applications of lithium‐ion batteries require efficient thermal management systems. In this work, a lumped capacitance heat transfer model is developed in conjunction with a flow network approach to study performance of a commercial‐size lithium‐ion battery pack, under various design and operating conditions of a thermal management system. In order to assess the battery thermal management system, capabilities of air, silicone oil, and water are examined as three potential coolant fluids. Different flow configurations are considered, and temperature dispersions, cell‐averaged voltage distributions, and parasitic losses due to the fan/pump power demand are calculated. It is found that application of a coolant with an appropriate viscosity and heat capacity, such as water, in conjunction with a flow configuration with more than one inlet will result in uniform temperature and voltage distributions in the battery pack while keeping the power requirement at low, acceptable levels. Simulation results are presented and compared with literature for model validation and to show the superior capability of the proposed battery pack design methodology. Copyright © 2014 John Wiley & Sons, Ltd.     

Thermal management of lithium-ion batteries using phase change materials

良好的热管理系统是电池安全及高效使用的保证,电池的热管理需要确保电池温度在安全温度范围以及电池组内最大温差不超过5 ℃.传统的热管理方式,如空气冷却,不仅需要额外的动力输入,而且越来越不能满足高能量密度的新型锂离子电池的热管理需要.使用相变材料的电池热管理系统,利用相变材料的相变潜热吸收电池产生的热量,在不使用外界功耗的条件下,可以长时间保持电池的温度在适宜的范围内.通过与膨胀石墨,金属泡沫复合,相变材料的热导率可以大大提高,电池组内体系温度均匀性可以满足工作要求.而且,相变材料的形状不固定,可以使用在任意形状的电池上.被动式热管理是应用于电池热管理系统中最具前景的技术.     

Liquid cooling based on thermal silica plate for battery thermal management system

To achieve safe, long lifetime, and high‐performance lithium‐ion batteries, a battery thermal management system (BTMS) is indispensable. This is especially required for enabling fast charging‐discharging and in aggressive operating conditions. In this research, a new type of battery cooling system based on thermal silica plates has been designed for prismatic lithium‐ion batteries. Experimental and simulations are combined to investigate the cooling capability of the BTMS associated to different number of cooling channels, flow rates, and flow directions while at different discharge C‐rates. Results show that the maximum temperature reached within the battery decreases as the amount of thermal silica plates and liquid channels increases. The flow direction had no significant influence on the cooling capability. While the performance obviously improves with the increase in inlet flow rate, after a certain threshold, the gain reduces strongly so that it does not anymore justify the higher energy cost. Discharged at 3 C‐rate, an inlet flow rate of 0.1 m/s was sufficient to efficiently cool down the system; discharged at 5 C‐rate, the optimum inlet flow rate was 0.25 m/s. Simulations could accurately reproduce experimental results, allowing for an efficient design of the liquid‐cooled BTMS.     

锂离子电池热管理技术

电动汽车在应对气候变化和减少碳排放方面显示出了巨大潜力,电池作为电动汽车的动力来源,在性能和安全方面受温度影响很大。一套有效的热管理控制系统能使电池组温度保持在最佳工作范围内,提高整车的续驶里程。主要总结了目前对电池进行散热和保温的主流电池热管理技术——风冷、液冷、相变冷却、热管冷却以及电池加热技术。提出电池热管理技术应往智能化、集成化、与机器学习相结合、能够自适应调节电池生态温度的方向发展,将会有很大的研究空间。     

Numerical investigation of thermal runaway propagation in a Li-ion battery module using the heat pipe cooling system

It is a promising cooling strategy to use the heat pipe for the Li-ion battery module, which can maintain the temperature of the battery module properly and prevent high temperature, triggering the thermal runaway among adjacent batteries. In this study, the thermal runaway model is simulated through the internal short circuit, which couples with Volume of Fluid (VOF) model of the heat pipe cooling and solves in ANSYS FLUENT to realize the heat and mass transfer between batteries and heat pipes. A user-defined function (UDF) code including mass source and energy source is used to calculate the heat and mass transfer in VOF model during the thermal runaway process. Numerical simulations are adopted to probe thermal runaway processes of a single battery under different operation conditions and the thermal runaway propagation from a battery to adjacent batteries. It is concluded that the heat pipe cooling system cannot prevent the thermal runaway of a single battery, but it can prevent the thermal runaway propagation from a battery to adjacent batteries.     

Recent progress in lithium-ion battery thermal management for a wide range of temperature and abuse conditions

Lithium-ion batteries are important power sources for electric vehicles and energy storage devices in recent decades. Operating temperature, reliability, safety, and life cycle of batteries are key issues in battery thermal management, and therefore, there is a need for an effective thermal-management system. This review summarises the latest research progress on lithium-ion battery thermal management under high temperature, sub-zero temperature, and abuse conditions. Heat generation mechanisms are characterised under both normal and abuse conditions. Different cooling methods, which include air cooling, liquid cooling, phase change cooling, heat pipe cooling, and their combinations are reviewed and discussed. Thereafter, features of different battery heating methods such as air/liquid heating, alternate current heating, and internal self-heating are discussed. An improvement in battery safety under abuse conditions is discussed from the perspective of battery material modification and thermal management design. The research progress in recent investigations is summarised, and the prospects are proposed.     

Experimental study of a direct evaporative cooling approach for Li-ion battery thermal management

A desirable operating temperature range and small temperature gradient is beneficial to the safety and longevity of lithium-ion (Li-ion) batteries, and battery thermal management systems (BTMSs) play a critical role in achieving the temperature control. Having the advantages of direct access and low viscosity, air is widely used as a cooling medium in BTMSs. In this paper, an air-based BTMS is modified by integrating a direct evaporative cooling (DEC) system, which helps reduce the inlet air temperature for enhanced heat dissipation. Experiments are carried out on 18650-type batteries and a 9-cell battery pack to study how relative humidity and air flow rate affect the DEC system. The maximum temperatures, temperature differences, and capacity fading of batteries are compared between three cooling conditions, which include the proposed DEC, air cooling, and natural convection cooling. In addition, a DEC tunnel that can produce reciprocating air flow is assembled to further reduce the maximum temperature and temperature difference inside the battery pack. It is demonstrated that the proposed DEC system can expand the usage of Li-ion batteries in more adverse and intensive operating conditions.     

泡沫金属-PCM-液冷复合方式下动力电池散热分析

电池是电动汽车的核心动力元件,而电池的热管理系统是动力电池发挥最佳工作性能的重要保障,在保证最佳工作性能的同时提升汽车安全性能、电池寿命及能源利用效率。基于21700NCA圆柱型三元锂离子电池,建立以泡沫铝为支撑骨架的电池组系统,在骨架和电池之间的孔隙注入相变材料（PCM）以提高结构内部温度均匀性,在电池底部添加液冷板来强化冷却效果,利用计算流体力学（CFD）仿真技术分析单体电池的耦合散热效果。结果表明,与单一冷却模式相比,使用泡沫金属与相变材料、液体冷却的耦合散热系统,可以达到更加良好的散热效果;对于相变材料,在一定密度范围内,密度越大,对电池系统的冷却效果越好,混合比主要影响相变材料的凝固融化速率。     

Multi‐objective design optimization for mini‐channel cooling battery thermal management system in an electric vehicle

Lithium‐ion battery packs have been generally used as the power source for electric vehicles. Heat generated during discharge and limited space in the battery pack may bring safety issues and negative effect on the battery pack. Battery thermal management system is indispensable since it can effectively moderate the temperature rise by using a simple system, thereby improving the safety of battery packs. However, the comprehensive investigation on the optimal design of battery thermal management system with liquid cooling is still rare. This article develops a comprehensive methodology to design an efficient mini‐channel cooling system, which comprises thermodynamics, fluid dynamics, and structural analysis. The developed methodology mainly contains four steps: the design of the mini‐channel cooling system and computational fluid dynamics analysis, the design of experiments and selection of surrogate models, formulation of optimization model, and multi‐objective optimization for selection of the optimum scheme for mini‐channel cooling battery thermal management system. The findings in the study display that the temperature difference decreases from 8.0878 to 7.6267 K by 5.70%, the standard temperature deviation decreases from 2.1346 to 2.1172 K by 0.82%, and the pressure drop decreases from 302.14 to 167.60 Pa by 44.53%. The developed methodology could be extended for industrial battery pack design process to enhance cooling effect thermal performance and decrease power consumption.     

Thermal modeling of secondary lithium batteries for electric vehicle/hybrid electric vehicle applications

A major obstacle to the development of commercially successful electric vehicles (EV) or hybrid electric vehicles (HEV) is the lack of a suitably sized battery. Lithium ion batteries are viewed as the solution if only they could be “scaled-up safely”, i.e. if thermal management problems could be overcome so the batteries could be designed and manufactured in much larger sizes than the commercially available near-2-Ah cells.

Here, we review a novel thermal management system using phase-change material (PCM). A prototype of this PCM-based system is presently being manufactured. A PCM-based system has never been tested before with lithium-ion (Li-ion) batteries and battery packs, although its mode of operation is exceptionally well suited for the cell chemistry of the most common commercially available Li-ion batteries. The thermal management system described here is intended specifically for EV/HEV applications. It has a high potential for providing effective thermal management without introducing moving components. Thereby, the performance of EV/HEV batteries may be improved without complicating the system design and incurring major additional cost, as is the case with “active” cooling systems requiring air or liquid circulation.     

Thermal management of lithium‐ion batteries for electric vehicles

Thermal issues associated with electric vehicle battery packs can significantly affect performance and life cycle. Fundamental heat transfer principles and performance characteristics of commercial lithium‐ion battery are used to predict the temperature distributions in a typical battery pack under a range of discharge conditions. Various cooling strategies are implemented to examine the relationship between battery thermal behavior and design parameters. By studying the effect of cooling conditions and pack configuration on battery temperature, information is obtained as to how to maintain operating temperature by designing proper battery configuration and choosing proper cooling systems. It was found that a cooling strategy based on distributed forced convection is an efficient, cost‐effective method which can provide uniform temperature and voltage distributions within the battery pack at various discharge rates. Copyright © 2012 John Wiley & Sons, Ltd.     

Heat dissipation design for lithium-ion batteries

A two-dimensional, transient heat-transfer model for different methods of heat dissipation is used to simulate the temperature distribution in lithium-ion batteries. The experimental and simulation results show that cooling by natural convection is not an effective means for removing heat from the battery system. It is found that forced convection cooling can mitigate temperature rise in the battery. Nevertheless, a non-uniform distribution of temperature on the surface of the battery is inevitable and this makes thermal management difficult.As a better means of suppressing increases in temperature, a heat pipe has been used to effect heat dissipation. The connection between the heat pipe and the battery wall pays an important role in heat dissipation. Inserting the heat pipe in to an aluminum fin appears to be suitable for reducing the rise in temperature and maintaining a uniform temperature distribution on the surface of the battery.