Reliable battery operation — a challenge for the battery management system

Advanced batteries, like lithium-ion batteries, are more sensitive in case of irregular operation than conventional batteries. Therefore, the operation of such batteries must be controlled by a management system. The features of a battery management system depend on the application, but in most cases, features like battery state determination, electrical management and safety management are necessary. This paper describes these functions of a battery management system. The use of a battery management system will lead to an increased lifetime and a safer operation of the battery.     

锂离子电池热管理和安全性研究

温度是影响锂离子电池性能、寿命和安全性的重要因素,电池热管理系统能使电池的工作温度维持在适宜范围,保障电池安全、高效和长寿命使用。因此,电池热管理系统对动力和储能设备在不同工况和环境下的运行至关重要。本文介绍了锂离子电池热模型的发展和应用,对热管理和安全性的研究进行了归纳;总结了本课题组的相关工作进展;在此基础上,指出了锂离子电池热管理和安全性进一步的研究方向。     

Review of lithium-ion battery state of charge estimation

The technology deployed for lithium-ion battery state of charge (SOC) estimation is an important part of the design of electric vehicle battery management systems. Accurate SOC estimation can forestall excessive charging and discharging of lithium-ion batteries, thereby improving discharge efficiency and extending cycle life. In this study, the key lithium-ion battery SOC estimation technologies are summarized. First, the research status of lithium-ion battery modeling is introduced. Second, the main technologies and difficulties in model parameter identification for lithium-ion batteries are discussed. Third, the development status and advantages and disadvantages of SOC estimation methods are summarized. Finally, the current research problems and prospects for development trends are summarized.     

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.     

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。     

基于加速寿命试验的锂离子电池可靠性分析方法

为了有效地提高锂离子电池寿命评估的准确性,延长储能系统在配电网中运行年限,文章提出了基于加速寿命试验的锂离子电池可靠性分析方法。综合考虑不同放电深度对锂离子电池寿命影响,建立了锂离子电池的寿命衰退模型;确定了荷电状态(SOC)与健康度(SOH)的关联特性关系;提出了基于逆幂率方程的储能系统加速寿命试验方法;基于情景分析法对锂离子电池的可靠性进行了分析。研究结果表明,文章所提出的试验方法能够准确地对不同运行状态下的锂离子电池储能系统进行可靠性评估,保证储能系统并网运行过程中的调控准确性。     

Brief analysis the safety of solid-state lithium ion batteries

锂二次电池因其具有能量密度高、循环寿命长、无记忆效应、无污染等优点,使得其在便携式消费电子产品、电动汽车、能量储存等领域具有广泛的应用前景。目前,锂二次电池的能量密度和安全性是当今世界的研究热点。但对于传统液态电解质的锂离子电池而言,尽管从材料、模组、电源管理、热管理、系统设计等各个层面均采取了多种改进措施,然而高能量密度电芯的安全性问题依然突出,热失控问题难以彻底避免。因此,为了提高锂电池的安全性,发展理论上不易燃的固态锂电池是解决锂电池安全问题的必由途径。本工作比较了传统液态锂离子电池与固态锂电池结构特征,总结了其各自优缺点,进一步深入剖析了传统液态锂离子电池安全问题产生的根本原因,提出了解决锂离子电池安全性问题的最佳方案,并通过对自主研发的系列容量固态锂（离子）电池的安全性能进行测试,证实了固态锂电池的高安全特性。     

The progress in fault diagnosis techniques for lithium-ion batteries

实施精准、可靠的故障诊断,是确保电池系统安全、稳定、可靠运行的关键,并为电池系统的精准运营维护提供理论、方法与技术支撑。本文首先在总结电池系统故障类型与表现形式的基础上,重点分析了在电池制造、成组筛选和使用各个阶段的本体故障引发机制。其次,对现有研究发展的电池系统故障诊断方法进行了分类,大致分为基于电池模型的故障诊断方法和无模型的故障诊断方法。之后,针对不一致故障诊断、短路故障诊断、热故障诊断、传感器故障诊断、连接组件故障诊断和多故障联合诊断,对现有文献提出的解决策略及应用案例进行了全面综述。最后,以全面文献调研为基础,提出了电池系统故障诊断研究面临的主要挑战和未来的研究方向。     

A comprehensive review on inconsistency and equalization technology of lithium-ion battery for electric vehicles

The rapid growth of transportation demand has been enlarged strongly which has promoted electric vehicles powered by lithium-ion batteries. However, the inconsistencies within the battery pack will deteriorate over the lifecycle and affect the performance of electric vehicles. Therefore, various thermal management systems and equalization systems have been applied in battery management system to deal with the inconsistencies, extend battery service life, and improve safety performance. This review summarizes the origination of inconsistency within lithium-ion batteries from production to usage process, and then introduces the classification methods and application scenarios of the balance management system in detail. Based on the circuit topology, equalization systems can be classified into passive and active topologies. Active topologies are widely researched due to the advantages of high equalization efficiency and high speed, and the state-of-art innovations are presented and compared from the prospective of circuit, energy flow, efficiency and system complexity. In addition, this review focuses on the mainstream equalization strategies based on the analysis of balancing variables and control algorithms in terms of efficiency, complexity and stability, especially in the areas of variables optimal selection and advanced control algorithms. It is expected that innovations such as cloud control methods and hybrid balancing systems equipped with thermal management will become the future direction of lithium-ion equalization technologies.     

Simulation of passive thermal management system for lithium-ion battery packs

A passive thermal management system that uses a phase change material (PCM) is designed and simulated for a lithium-ion (Li-ion) laptop battery pack. The problem of low thermal conductivity of the PCM was significantly improved by impregnating an expanded graphite (EG) matrix with the PCM. The heat generation rate for a commercial 186502.2 Ah Li-ion battery was experimentally measured for various constant power discharges. Simulation of the battery pack, composed of six Li-ion batteries, shows that safe operation of the battery pack during the most extreme case requires the volume of the battery pack be almost doubled to fit sufficient PCM in the pack. Improving the properties of the PCM composite have the potential to significantly reduce the volume increase in comparison to the original battery pack volume.     

Recent progress on evolution of safety performance of lithium-ion battery during aging process

安全性是制约锂离子电池规模应用的重要技术问题。锂离子电池的安全性能不仅仅与材料体系、电芯设计相关,还会随着使用过程而发生变化。锂离子电池安全性能在全生命周期内的演变规律需要重点展开研究,以保障电池在使用过程中的安全性。本文对锂离子电池全生命周期安全性演变问题的国内外研究进展进行了综述,分析了国内外关于电池安全性能在循环老化和储存老化两种工况下的演变规律的研究,总结了电池老化衰减机理与安全性能变化之间的关系,指出负极析锂是影响电池全生命周期安全性能的重要因素,最后对锂离子电池全生命周期安全性演变研究进行了展望。     

Use of lithium-ion batteries in electric vehicles

An account is given of the lithium-ion (Li-ion) battery pack used in the Northern Territory University's solar car, Fuji Xerox Desert Rose, which competed in the 1999 World Solar Challenge (WSC). The reasons for the choice of Li-ion batteries over silver–zinc batteries are outlined, and the construction techniques used, the management of the batteries, and the battery protection boards are described. Data from both pre-race trialling and race telemetry, and an analysis of both the coulombic and the energy efficiencies of the battery are presented. It is concluded that Li-ion batteries show a real advantage over other commercially available batteries for traction applications of this kind.     

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.     

Solar photovoltaic charging of lithium-ion batteries

Solar photovoltaic (PV) charging of batteries was tested by using high efficiency crystalline and amorphous silicon PV modules to recharge lithium-ion battery modules. This testing was performed as a proof of concept for solar PV charging of batteries for electrically powered vehicles. The iron phosphate type lithium-ion batteries were safely charged to their maximum capacity and the thermal hazards associated with overcharging were avoided by the self-regulating design of the solar charging system. The solar energy to battery charge conversion efficiency reached 14.5%, including a PV system efficiency of nearly 15%, and a battery charging efficiency of approximately 100%. This high system efficiency was achieved by directly charging the battery from the PV system with no intervening electronics, and matching the PV maximum power point voltage to the battery charging voltage at the desired maximum state of charge for the battery. It is envisioned that individual homeowners could charge electric and extended-range electric vehicles from residential, roof-mounted solar arrays, and thus power their daily commuting with clean, renewable solar energy.     

Research on early warning system of lithium ion battery energy storage power station

研究锂离子电池储能电站消防预警技术对于储能系统的安全运行具有重要意义。本文通过对电池热失控及热扩散特征识别展开讨论,由于锂离子电池发生热失控时会伴随着可燃气体缓慢释放,如果能够提取电池热失控早期气体参数并对其进行研究分析,可以在此基础上建立电池系统的热失控预警机制。本文采用加热方式和过充方式诱发电池热失控气体提取试验,通过采气试验进行气体成分含量分析,确定了将一氧化碳和温度作为典型的侦测依据来实现锂电池热失控的早期预警。并将这种电池热失控早期预警判断应用到了储能电站消防预警系统中,同时结合多级预警及防护机制和安全联动策略做了深入研究,确定了锂离子电池储能电站消防预警系统的设计架构,从系统部件、联动通信、人员安全3个方面对系统设计做了简要说明,在保证快速有效的检测出电池热失控状态的同时快速联动消防设施,极大提高了储能系统运行的可靠性。     

Safety test and evaluation method of lithium ion battery

对锂离子电池的机械滥用、热滥用和电滥用安全性测试与评价方法的原理进行了分析,对具有代表性的锂离子电池安全测试标准GB/T 31467.3/31485和SAE J2464/UN 38.3的相关试验方法进行了对比分析。应用X射线三维CT技术,测试了安全性试验前后锂离子电池内部结构的变化,对X射线三维CT应用于锂离子电池安全性测试分析的前景进行了展望。为锂离子电池安全失效模式分析指明了方向。     

Patent analysis of lithium ion power battery recycling technology

锂离子动力电池的回收是当前储能产业关注的焦点之一,为了解锂离子动力电池的回收现状,以CNABS和DWPI专利数据库中的检索结果为分析样本,对锂离子动力电池回收技术的专利申请量趋势、全球分布区域、国内外主要申请人、全球重点技术分布以及国内重点技术进行全面分析,结果表明,虽然锂离子动力电池回收技术是目前全球尤其是中国争相布局的产业对象,但目前各个企业的专利申请量均较小且技术布局零散,总体来说锂离子动力电池回收技术仍处于摸索阶段,产业前景不明,本文以期给锂离子动力电池回收技术未来的布局和发展提供一定的借鉴。     

Overview of research on thermal safety of lithium-ion batteries

随着锂离子电池在生活和工作中的普及,锂离子电池的安全事故逐年增加,锂离子电池的安全研究逐渐引起学术界的关注。研究锂离子电池的热安全性,可以有效分析锂离子电池发生起火和爆炸的内在原因,指导锂离子电池安全性研究的开展。本文介绍了锂离子电池工作过程中产热的来源和影响因素,以及锂离子电池热失控发生时的内部反应和反应对应的温度,并对电池热失控时的热特性参数进行了总结。     

Design modeling of lithium-ion battery performance

A computer design modeling technique has been developed for lithium-ion batteries to assist in setting goals for cell components, assessing materials requirements, and evaluating thermal management strategies. In this study, the input data for the model included design criteria from Quallion, LLC for Gen-2 18650 cells, which were used to test the accuracy of the dimensional modeling. Performance measurements on these cells were done at the electrochemical analysis and diagnostics laboratory (EADL) at Argonne National Laboratory. The impedance and capacity related criteria were calculated from the EADL measurements. Five batteries were designed for which the number of windings around the cell core was increased for each succeeding battery to study the effect of this variable upon the dimensions, weight, and performance of the batteries. The lumped-parameter battery model values were calculated for these batteries from the laboratory results, with adjustments for the current collection resistance calculated for the individual batteries.     

Research progress on capacitive lithium-ion battery

锂离子电池具有高的能量密度,而超级电容器则以高功率密度和长循环寿命为突出优势。电容型锂离子电池是在锂离子电池的正极中加入部分电容炭材料,在不显著降低能量密度的情况下,大幅度改善锂离子电池的功率特性和循环寿命,从而实现电容与电池技术的融合。本文综述了国内外近年来在电容型锂离子电池领域的最新研究进展,介绍了主要的电容型锂离子电池体系及其性能特点,并对其未来发展方向进行了展望。