锂离子动力电池低温加热策略研究进展

随着新能源产业飞速发展,纯电动汽车的市场渗透率迅速上升。而制约电动汽车使用的一大关键因素,就是环境温度。在低温下,动力电池的功率特性衰减、电池内阻增大、电池可用容量降低。这些负面因素将直接影响电动汽车的续航里程与安全性。基于动力电池低温加热策略的主要产热区域,将目前锂离子电池低温加热策略划分为电池内部加热策略和电池外部加热策略两个大类。分别对这两个大类进行更详细的梳理,对目前的锂离子电池低温加热策略进行了系统的研究。分析了各种加热策略的优点与弊端,并针对存在的问题提出了解决意见。可为后续电动汽车动力电池低温加热策略的研究、锂离子电池低温下热管理系统的设计提供参考。     

锂离子电池低温快速加热方法研究进展

锂离子电池的性能直接影响电动汽车的续航、安全性和可靠性.低温环境下,锂离子电池功率特性变差、循环寿命衰减、可用容量降低,同时面临低温充电难、充电易析锂等问题,这些因素阻碍了电动汽车的发展.低温加热技术是电池热管理系统的核心技术之一,是缓解动力电池在低温环境下性能衰减的关键.本文综述了包括内部自加热法、MPH加热法、自加...     

低温环境下电池热管理系统研究进展

随着电动汽车应用范围的不断扩大,人们越来越重视电池组的性能及对电池的管理。有效的热管理能极大提升电池的性能。在低温环境下,使用不加热的电池严重破坏了电池的性能和预期寿命。本文总结了电池受低温的影响,综述了包括内部和外部加热电池等热管理技术的研究进展,对电池升温热管理作出了展望,提出了集中在减小电池体积与质量、尽量减少自身电量消耗和帕尔贴元件与相变材料耦合热管理技术方面的研究方向。     

重卡辅助动力电池加热系统能耗对比及优化北大核心CSCD

清洁能源的重卡汽车因其零排放、长续航等特性近年来得到了迅速发展,其动力驱动配置多采用燃料电池为主动力电池为辅的形式。低温环境下,重卡辅助动力电池性能衰减不足以承担辅助动力源削峰填谷的重担。因此,加热辅助动力电池使其恢复充电放电性能对重卡汽车应对寒冷环境显得尤为重要。本工作以方形磷酸铁锂电池组为研究对象,通过实验测试单体磷酸铁锂电池−10℃、0℃、10℃、20℃的放电工况,得出电池的低温热特性,建立单体电池的热模型并验证其模型有效性。基于该模型提出了一种以石墨烯加热膜为主要热源,整车车载热源余热为辅助热源的加热升温系统。同时,为了降低该加热系统能耗,基于传热原理建立了电池加热系统线性时变模型预测控制器(MPC)。结果表明,重卡在C-WTVC的行驶工况下,电池加热系统通过换热器利用车载热源余热能够提升动力电池组升温速率,使用加热膜和换热器的加热系统比传统PTC加热系统能耗降低了30%。采用MPC控制策略的加热系统比PID控制的加热系统能耗降低了14%。     

服役工况下车用锂离子动力电池散热方法综述

随着电动汽车的广泛使用,锂离子动力电池俨然成为纯电动汽车首选的动力来源,然而其热安全性问题也日益突出.基于此,本文针对车用锂离子动力电池在服役工况下尤其高温时存在的安全性差、工作不可靠及循环寿命短等热问题,根据电池的动态散热特性着重介绍了车用锂离子动力电池常用的冷却方法,包括空冷散热、液冷散热、相变材料冷却、热管冷却和耦合散热,说明了集多种冷却方式耦合的热管理系统与单一散热方法相比不仅能提高散热效率,还可以改善电池的均温性.并结合上述散热方法的研究进展及关键技术,主要在空冷通道优化、液冷结构设计及冷却液介质分析、相变材料应用特性、热管的冷却特性及热特性等方面进行了具体综述.最后,针对目前常用的动力电池散热方法中存在的问题提出了合理化建议,展望了电池热管理系统与汽车乘员热舒适性、电动机舱热管理及车辆热环境相耦合,形成整车热管理系统的开发,以期为电池热管理系统设计开发等相关领域的研究提供一定参考.     

电动汽车动力电池冷却技术的研究进展

新能源汽车在运行时,如何冷却动力电池使其维持在最佳的工作温度是需要重视的问题。合适的冷却技术可以有效提高动力电池的效率,并随着时间的推移降低动力电池老化的速度,延长其使用寿命。综述了几种电池热管理冷却系统,包括传统冷却技术中空气冷却系统、液体冷却系统和直接冷却系统。新型冷却技术中基于相变材料冷却系统、采用热管技术冷却系统和电子元件冷却系统提高汽车动力电池的性能。根据不同技术分析各自的优缺点、适合的工作工况以及经济效益。未来动力电池热管理的发展方向应是无论选择何种技术冷却动力电池,都应保证动力电池处于最佳工作温度,冷却系统稳定、可靠并且能够稳定提高动力电池的转换效率,以期为电池热管理的实际应用提供一定的参考价值。     

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。     

基于空调的有轨电车动力电池热管理控制北大核心CSCD

新能源有轨电车的动力电池间歇性工作、充放电时发热量大,一般需要配置各种形式的散热装置。采用变频空调设计电池箱的热管理系统,其热泵功能在高温或低温环境时可将箱内温度控制在合理范围之内。本工作提出一种适用于此热管理系统空调的多温融合温区控制方法,主要包括压缩机频率计算和动态温度区间控制两方面。用环境温度和电池温度修正回风温度,兼顾提高空调运行效率和响应速度,并以修正后的温度参数参与计算压缩机频率。箱内温度控制为较宽范围的温度区间,并以回风温度的变化趋势动态调整区间范围,减少空调制冷/制热时间的同时抑制回风温度异常上升。还介绍了通风机和冷凝风机的变频调速控制方法。对应用此方法的电池箱(及空调)进行试验测试,空调能耗下降约4%,电池最高温度降低近2℃。结果表明,所述方法既能实现电池箱温度调控需求、优化电池环境,又能降低热管理系统的运行能耗。应用所述热管理系统的动力电池箱经过试验考核后已装车运用。     

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。     

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。     

Thermal management system of lithium‐ion battery module based on micro heat pipe array

Temperature affects the performance of electric vehicle battery. To solve this problem, micro heat pipe arrays are utilized in a thermal management system that cools and heats battery modules. In the present study, the heat generation of a battery module during a charge‐discharge cycle under a constant current of 36 A (2C) was computed. Then, the cooling area of the condenser was calculated and experimentally validated. At rates of 1C and 2C, the thermal management system effectively reduced the temperature of the module to less than 40°C, and the temperature difference was controlled less than 5°C between battery surfaces of the module. A heating plate with 30‐W power effectively improved charge performance at low temperature within a short heating time and with uniform temperature distribution. Charge capacity obviously increased after heating when battery temperature was below 0°C. This study presents a new way to enhance the stability and safety of a battery module during the continuous charge‐discharge cycle at high temperatures and low temperatures accordingly.     

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.     

Performance assessment of a passive core cooling design for cylindrical lithium‐ion batteries

Battery thermal management (BTM) system is an indispensable component for large‐sized lithium‐ion battery packs used in aerospace and automotive applications. Besides providing a proper temperature range for batteries to operate, thus improving their efficiency, lifespan, and safety, the BTM system also needs to be well designed with considering the cost, weight, and practicability. In this paper, an internal passive BTM system is proposed for the cylindrical Li‐ion batteries. The design embeds a phase change material (PCM) filled mandrel inside the battery to achieve the cooling effect. A thermal test cell is first fabricated and tested in a wind tunnel under different cooling scenarios, and it is also used to verify a numerical thermal model. The proposed BTM system is further examined through the model and found to be able to create a preferable environment for batteries to operate. Specifically, the core BTM system consumes less PCM and achieves lower temperature rises and more uniform temperature distributions than an external BTM system. The proposed design can also exert its full latent heat to manage the heat generated from the battery without having a thermally conductive matrix, which is usually composite with PCM in external BTM systems. In addition, experiments show that the battery equipped with the proposed BTM system is ready for intensive cycling tests.     

Temperature characteristics of lithium iron phosphatepower batteries under overcharge

High-capacity LiFePO₄ batteries are widely used in public transportation in China. However, overcharge causes serious safety issues, and the nature of the process requires further research. This study investigates an overcharge-induced thermal runaway of 20 and 24 Ah LiFePO₄ batteries under different initial states of charge (SOC) and charging rates. Chemical reactions inside the battery are influenced by the capacity of the battery, that is, a higher capacity induces faster heating and a higher maximal surface temperature than the lower capacity under the same conditions. The temperature curve of low initial SOC battery at low chargingratedoes not change notably. Under other conditions, the thermal runaway exhibits two stages, an initial slow temperature increase (stage I) followed by a rapid temperature increase (stage II). The initial SOC and charging rate are relevant only for the rate of temperature increase in stage I, with little effect in stage II. The study on the temperature characteristics of overcharge-induced thermal runaway can promotethe safety research of LiFePO₄ power batteries.     

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。     

Preheating strategy of variable-frequency pulse for lithium battery in cold weather

Aiming to the issue of charging difficulty and capacity fading for lithium-ion battery at low temperature, this study proposes a preheating strategy using variable-frequency pulse. The innovation of this paper is to propose the thermo-electric coupling model based on the electrochemical impedance spectroscopy of battery at different temperatures, integrated with variable frequency changing for pulse method to develop an effective inner pre-heating strategy. Meanwhile, the evaluating method of impact of this strategy on capacity fading of battery has also been proposed to examine its effectiveness, to find the optimal strategy. First, temperature rise model and the thermo-electric coupling model at different temperatures according to the equivalent circuit model of battery are presented. Further, optimal heating frequency of current pulse at different temperatures is calculated according to the changing of internal impedance. The results show that the optimal variable-frequency pulse pre-heating strategy can heat the lithium-ion battery from −20°C to 5°C in 1000 seconds. Meanwhile, it brings less damage to the battery health and improves the performance of battery in cold weather based on the views of power consumption, capacity attenuation, and internal impedance changes.     

大功率锂离子动力电池组散热特性数值模拟

大功率锂离子动力电池具有较高的功率密度和能量密度,在纯电动汽车和混合动力汽车中具有很大的应用价值。本文采用数值模拟的方法,建立了大功率非均匀产热动力电池组三维模型,模拟分析了基于空气单向流动冷却和往复流动冷却的LiFePO₄动力电池组（4 × 6）的散热性能。结果表明,对于大功率电池正负极产热不均匀的情况,为了降低电池模块的局部温差,电池采用正负极交叉式排列组合是必要的;随着入口风速的增大,角度大小对散热性能的影响增大;周期较长时的往复通风方式不利于减小电池组局部温差,甚至在长时间内会增加局部温差。     

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.     

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.