Performance of serpentine channel based Li-ion battery thermal management system: An experimental investigation

Thermal management of large-scale Li-ion battery packs is of great significance to their safety and life cycle, which would impact their applicability in electric vehicles. Of the many strategies developed for this purpose, indirect liquid cooling has already demonstrated quite high potentials in thermal regulation of such battery systems. In this study, a compact lightweight serpentine wavy channel configuration was chosen to construct an indirect liquid cooling system for a battery module of cylindrical Li-ion cells. The serpentine channel has a number of six internal minichannels. Experimental test data were used to conduct a comprehensive thermal analysis to examine the highest temperature, the maximum temperature difference, and the heat accumulation percentages, and so forth within the battery pack. Results have revealed the ability of the cooling system to maintain the module temperature within appropriate working conditions for electric vehicle applications for most cycling tests including two driving cycles. Furthermore, the analysis insights raised by this study could be useful in understanding the cooling performance of the liquid-based thermal management systems for electric vehicles.     

Intelligent optimization methodology of battery pack for electric vehicles: A multidisciplinary perspective

Past studies focused on proposing new materials for batteries components, state of health (SOH) prediction, thermal design, equivalent circuit modeling, and so on. Those studies have been implemented on individual basis on a single battery or battery pack. However, there is hardly any research found that encompasses all the multidisciplinary aspects (such as materials, SOH, intelligent configuration [assembly], thermal design, mechanical safety, and recycling of materials and pack) simultaneously for the battery pack design of electric vehicles. This research article proposes a synthetic methodology for an advanced design of battery pack and its components by incorporating optimal scenario of materials selection for battery electrodes, SOH estimation, configurations (assembly) of cells, thermal (air and liquid cooling) design, battery pack casing mechanical safety, and recycling aspects of battery and battery pack. The problem is divided into the several parts and methodology for each is proposed. Cumulative advantages of the methodology with six future critical directions are discussed in the end.     

车用锂离子电池液冷式热管理系统实验研究

锂离子电池组的热管理对电动汽车的性能和安全性具有重要意义。基于多通道蛇形波纹管液冷式热管理系统,以200个18650型锂离子电池组为热管理对象,对电池在各种充放电倍率下所需的冷却液流量、泵功消耗以及热管理收益进行了实验研究。结果表明,热管理系统对动力电池在各种充放电应用条件下都具有较好的热管理效果,电池最大温度和最大温差基本可控制在40℃以下和5℃以内。提高冷却水流速对系统热管理能力的提升具有一定的效果,但是随着流速增大,热管理能力提升的边际效益也更趋明显;而系统运行所消耗的泵功增加导致了热管理收益随冷却水流速增加而大幅降低。从电池的性能安全以及热管理有效性的角度综合考虑,各充放电倍率下热管理系统的冷却水流速都是以保证电池安全和性能指标的最低流速为优。     

Recent progress on thermal runaway propagation of lithium-ion battery

简述了电动汽车锂离子动力电池热失控蔓延机理、建模与抑制技术的最新研究进展。为了满足汽车高能量的要求,需要动力电池进行串并联成组来提供动力。电池组成组安全问题成为电动汽车大规模应用的重要技术问题。电池组中的某一个电池单体发生热失控后产生大量热,导致周围电池单体受热产生热失控。因而,电池组成组安全问题的重要关注点是电池组内的热失控蔓延问题。本文对锂离子电池热失控蔓延问题的国内外研究进展进行了综述,分析了对于不同种类锂离子动力电池影响其热失控蔓延特性的主要因素。总结了文献中的热失控蔓延建模方法,并指出了已有方法的不足。从电池系统热安全管理的角度,阐述并分析了热失控蔓延防控技术的研究成果与方向。最后对锂离子电池热失控蔓延研究进行了展望。     

Exploring the heat transfer performance of nanofluid as a coolant for power battery pack

Nanofluids with high thermal conductivity coefficient are introduced to the thermal management system of power battery packs for electric vehicles and hybrid electric vehicles. Two typical cooling structures of cylindrical and square battery packs are described, and their flow models are established. By similarity transformations, the nonlinear system of partial differential equations is reduced and then solved numerically by the shooting method. The heat transfer properties of three types of nanofluids, that is, CuO‐EG, Al₂O₃‐EG, TiO₂‐EG, are analyzed in detail. It is found that CuO‐EG nanofluid is the best coolant for the cylindrical battery pack, whereas Al₂O₃‐EG nanofluid is the best choice for square battery pack cooling.     

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.     

Analysis of Heat Dissipation Performance between a Horizontal and Longitudinal Battery Pack Based on Forced Air Cooling

A battery pack is the main energy storage element, and directly affects the performance of an electric vehicle. Battery thermal management system research and its development for a modern electric vehicle is required. This paper selects the forced air cooling of battery pack as the research object, and uses simulation methods to research the heat dissipation performance with different structures of battery packs. The results indicate that according to the four types of transient state conditions, the rising temperature of both battery packs are significantly higher than the temperature difference, the maximum temperature rise and temperature difference of a horizontal battery pack are lower than a longitudinal battery pack. When an electric vehicle begins to decrease speed, the curves of temperature rising and temperature difference increase. This shows the internal heat is continuously rising, so even in a electric vehicle beginning to decrease speed, the fan must work. The reference basis for choosing battery pack type and an analysis of heat flow field characteristics, including fan run‐time control, are offered.     

Research on heat dissipation performance and flow characteristics of air‐cooled battery pack

With the depletion of fossil fuels and the aggravation of environmental pollution, the research and development speed of electric vehicles has been accelerating, and the thermal management of battery pack has become increasingly important. This paper selects the electric vehicle battery pack with natural air cooling as the study subject, conducts simulation analysis of the heat dissipation performance of battery packs with and without vents. Then this paper researches on the influence of internal flow field and external flow field. Field synergy principle is used to analyze the effect of velocity field and temperature field amplitude. The results show the following: it is found that the maximum temperature rise and the internal maximum temperature difference of the battery pack with vents are reduced by about 23.1% and 19.9%, raising speed value can improve the heat dissipation performance, and raising temperature value can decrease the heat dissipation performance. Reasonable design of the vents can make the inner and outer flow field work synergistically to achieve the best cooling effect. Then the reference basis for the air cooling heat dissipation performance analysis of electric vehicle, battery pack structure arrangement, and air‐inlet and air‐outlet pattern choosing are offered.     

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.     

A generic framework for recycling of battery module for electric vehicle by combining the mechanical and chemical procedures

By year 2020, due to enormous growth of production of electric vehicles, it is estimated that approximately 250 000 tons of battery must be disposed or recycled. Till date, the technology to recycle this much amount of batteries in a single year does not exist. Nor, do the methods for recycling are standardized and regulated because of differences in configurations of battery packs. This article conducts a systematic review on research of recycling methods for battery pack used in various stages such as from the dismantling/ disassembly of the battery pack, the detection of the residual energy of the battery, and the recycling/recovery of materials from the battery. The review summarizes basically the 2 main aspects of recycling of battery pack: the mechanical procedure and the chemical recycling. The work describes the existing recycling technology in these 2 aspects and identifies the important research problems in the process of recycling of battery pack such as (1) complexity of dismantling process of battery pack; (2) diversity of connectors used in battery pack; (3) safety of dismantling of battery pack; (4) instability of chemical materials in battery; (5) the chaos of the recycling market; and (6) emerging battery dismantling technologies. One important direction suggested is the automation of battery pack disassembly, which is a main factor towards formulation of generic framework for recycling of battery pack in an efficient manner. Based on these gaps, the present work also proposes a framework for the recycling of battery pack by combining the semi‐automation mechanical procedure of battery pack and enhanced chemical recycling of battery for recovery of vital materials. Future work for authors is to work on establishing and validation of proposed framework. The advantages of the proposed framework are compared with that obtained from the existing framework. The proposed framework when used shall result in efficient and effective recycling of battery module and promote greener environment.     

Research on the heat dissipation performance of lithium‐ion cell with different operating conditions

This paper aims to research the thermal power of lithium‐ion cell with different operating conditions. A 55‐Ah lithium‐ion cell is selected as the research object. Experiment and simulation are chosen as the methods to research the temperature distribution and thermal power of the cell under different conditions. Combining with the thermal power of cells, this paper also researches the heat dissipation performance of battery pack under different operation conditions. The results indicated that average thermal power of a 55‐Ah lithium‐ion cell decreases along with the increase of ambient temperature and the decrease of state of charge and charge and discharge rates. The results achieved through simulation and experiment are consistent, so simulation could be used to research the temperature distribution of cell during charge and discharge. As considering the longitudinal battery pack with steady analysis, high temperature area is in the centre, and the temperature of air inlet is relatively low. The airflow mostly passes the top of battery pack but not through both sides. As considering the longitudinal battery pack with transient analysis, the temperature rise of battery pack is evidently higher than the inner temperature difference by studying three operating conditions (sustained deceleration, sustained acceleration and pulsed discharge). The curves of temperature rise and inner temperature difference rise along with sustained acceleration of the electric vehicle; therefore, even if the electric vehicle begins to decelerate, the fan must still work until the temperature of battery pack decreases. Then, the references are given for researching thermal characteristic during charge and discharge of the cell and the heat dissipation analysis of battery pack. Copyright © 2017 John Wiley & Sons, Ltd.     

Design of a thermal management system for a battery pack in an electric vehicle using Dymola

As the world moves toward more green and efficient means of modes of transport, electric vehicles are the most suitable and ideal choice to fulfill this requirement. Rapid developments in the field of battery technology are the main reason for their progress, but thermal management in such systems has been an area of concern for a long time. The work undertaken is to design and develop a battery management system (BMS) with a specific focus on the thermal behavior of the battery pack with varying vehicle loads as well as environmental conditions. To design an efficient BMS, one needs to model the battery behavior covering the thermal as well as electrical aspects of the battery. Apart from the battery model, a mathematical model of the electrical vehicle to mimic the various road load conditions for battery also needs to be modeled. Depending on the need for cooling based on battery behavior, the cooling circuit is modeled for the battery pack used. The entire study has been carried out using Dymola, a mathematical modeling software.     

Simulation of abuse tolerance of lithium-ion battery packs

A simple approach for using accelerating rate calorimetry data to simulate the thermal abuse resistance of battery packs is described. The thermal abuse tolerance of battery packs is estimated based on the exothermic behavior of a single cell and an energy balance than accounts for radiative, conductive, and convective heat transfer modes of the pack. For the specific example of a notebook computer pack containing eight 18650-size cells, the effects of cell position, heat of reaction, and heat-transfer coefficient are explored. Thermal runaway of the pack is more likely to be induced by thermal runaway of a single cell when that cell is in good contact with other cells and is close to the pack wall.     

面向碳中和目标的小型车载动力电池可持续发展研究

当前我国各行业均关注“碳中和”目标,电动汽车作为新能源材料和器件在交通行业实现节能环保目标的代表性载体之一,对我国实现碳中和目标有着重要意义。动力电池是电动汽车的重要组成部分,迫切需要解释其“碳中和”特性。将锂离子电池组在生产阶段的各类环境影响作为研究对象,采用生命周期评价方法,分析生产锂离子电池的过程中,成分组成对环境的综合影响。结果表明,硫化铁固态电池组（FeS₂SS）在足迹家族、资源耗竭和毒性损害的11类三级指标中环境潜值都较小,说明FeS₂SS电池组在生产阶段产生的综合环境影响较小,而磷酸铁锂-石墨电池（LFPy-C）、三元锂-硅纳米管电池（NMC-SiNT）、三元锂-硅纳米线电池（NMC-SiNW）在各项环境影响值中贡献程度均较高。为实现碳中和目标,减少碳排放,NMC-SiNW、LFPy-C、NMC-C三种电池组的生产应进行优化。     

Plate flat heat pipe and liquid‐cooled coupled multistage heat dissipation system of Li‐ion battery

A thermal management system with the capability of achieving excellent heat dissipation is essential to the development of battery pack for transportation devices. To meet the temperature uniformity requirements of the battery pack, the plate flat heat pipe and liquid‐cooled coupled multistage heat dissipation system had been introduced. In this article, the research status of thermal management systems in battery pack was introduced. And the heat generation and heating power of the Li‐ion cell were studied. Then, the structure model of plate flat heat pipe system was proposed. Finally, the enhanced heat conduction effect of the thermal management system proposed in this article was comprehensively analyzed. Through the analysis of the results, in high discharge rates, the thermal management system proposed in this article could meet the temperature uniformity requirements of battery pack; also, the internal difference would reduce by 30.20%.     

动力汽车用锂电池热管理系统仿真分析

为了研究动力汽车用锂电池温度场分布,建立了单体电池及电池组仿真模型,通过实验与FLUENT软件模拟验证的方式分析单体电池温度场。通过仿真分析讨论电池组温度场,采用三种不同的进出风方式进行空气强制冷却电池组,分析了进出风口有倾角与无倾角的不同温度控制效果,结果表明带有倾角的进出风方式有利于降低电池组最高温度。采用电池组壳体侧面开孔方式进行电池组热管理,可有效改善电池组放电过程的温度分布均匀性。     

汽车空调制冷剂直冷动力电池热管理系统的PID控制研究

电池热管理对电动汽车的安全和寿命至关重要。本文采用铝翅片铜管作为基础结构,设计一种结构紧凑、轻量型的18650型锂离子电池模组,采用基于PID原理的算法作为电动汽车空调系统电子膨胀阀的控制方案,实验研究R134a制冷剂直接气液两相流冷却电池模组的换热性能。结果表明：所提出的电池热管理系统能够快速响应温度的变化,并降低电池模组的温度。此外,当控制方案为动态温度PID算法时,电池模组以1 C倍率放电过程中电池之间的最大温差小于4℃,并且电池模组的最高温度低于36℃。     

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。     

Dynamic behaviour of Li batteries in hydrogen fuel cell power trains

A Li ion polymer battery pack for road vehicles (48 V, 20 Ah) was tested by charging/discharging tests at different current values, in order to evaluate its performance in comparison with a conventional Pb acid battery pack. The comparative analysis was also performed integrating the two storage systems in a hydrogen fuel cell power train for moped applications. The propulsion system comprised a fuel cell generator based on a 2.5 kW polymeric electrolyte membrane (PEM) stack, fuelled with compressed hydrogen, an electric drive of 1.8 kW as nominal power, of the same typology of that installed on commercial electric scooters (brushless electric machine and controlled bidirectional inverter). The power train was characterized making use of a test bench able to simulate the vehicle behaviour and road characteristics on driving cycles with different acceleration/deceleration rates and lengths. The power flows between fuel cell system, electric energy storage system and electric drive during the different cycles were analyzed, evidencing the effect of high battery currents on the vehicle driving range. The use of Li batteries in the fuel cell power train, adopting a range extender configuration, determined a hydrogen consumption lower than the correspondent Pb battery/fuel cell hybrid vehicle, with a major flexibility in the power management.     

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.