Discrimination of Li-ion batteries based on Hamming network using discharging-charging voltage pattern recognition for improved state-of-charge estimation

Differences in electrochemical characteristics among Li-ion batteries and factors such as temperature and ageing result in erroneous state-of-charge (SoC) estimation when using the existing extended Kalman filter (EKF) algorithm. This study presents an application of the Hamming neural network to the identification of suitable battery model parameters for improved SoC estimation. The discharging-charging voltage (DCV) patterns of ten fresh Li-ion batteries are measured, together with the battery parameters, as representative patterns. Through statistical analysis, the Hamming network is applied for identification of the representative DCV pattern that matches most closely of the pattern of the arbitrary battery to be measured. Model parameters of the representative battery are then applied to estimate the SoC of the arbitrary battery using the EKF. This avoids the need for repeated parameter measurement. Using model parameters selected by the proposed method, all SoC estimates (off-line and on-line) based on the EKF are within ±5% of the values estimated by ampere-hour counting.     

Operation conditions of batteries in PV applications

For a continuous energy supply of photovoltaic operated and off-grid loads, the storage of the solar generated electrical energy is necessary. About 60% of all over the world manufactured solar cells are used for such stand alone systems. In case of photovoltaic systems, mainly electrochemical battery storage systems are used.

The paper describes the requirements for batteries in solar systems. The most important storage systems, such as lead–acid, NiMH and Li-ion batteries are described in detail and further developing trends are discussed.

As it is well known that the operation conditions strongly influence the battery lifetime, this paper reviews photovoltaic operation conditions and experience in performance and lifetime in photovoltaic systems.     

Research progress of high rate Li-ion battery materials

电动汽车行业迅速发展,高倍率的锂离子电池是其关键,因此需要不断开发适用高倍率充放电的电池材料。本文简要综述了高倍率锂离子电池正极材料、负极材料、隔膜和电解液方面的研究进展,并对高倍率锂离子电池材料发展进行了展望。     

A review on prognostics and health monitoring of Li-ion battery

The functionality and reliability of Li-ion batteries as major energy storage devices have received more and more attention from a wide spectrum of stakeholders, including federal/state policymakers, business leaders, technical researchers, environmental groups and the general public. Failures of Li-ion battery not only result in serious inconvenience and enormous replacement/repair costs, but also risk catastrophic consequences such as explosion due to overheating and short circuiting. In order to prevent severe failures from occurring, and to optimize Li-ion battery maintenance schedules, breakthroughs in prognostics and health monitoring of Li-ion batteries, with an emphasis on fault detection, correction and remaining-useful-life prediction, must be achieved. This paper reviews various aspects of recent research and developments in Li-ion battery prognostics and health monitoring, and summarizes the techniques, algorithms and models used for state-of-charge (SOC) estimation, current/voltage estimation, capacity estimation and remaining-useful-life (RUL) prediction.     

Overview and preliminary in orbit behaviour of the lithium-ion batteries used onboard TX-2 satellite

通信技术卫星二号锂离子蓄电池组是我所自主研制的锂离子蓄电池组首次在GEO卫星上应用。卫星对蓄电池组提出了长寿命和高可靠性的技术要求,通过研究分析提出了合理的在轨管理策略和故障隔离技术以满足总体技术要求。同时介绍了通信技术卫星二号锂离子蓄电池组的设计、地面性能测试与考核以及在轨运行验证情况。在轨运行期间,锂离子蓄电池组性能优异,各单体电池之间保持良好的一致性;在轨管理策略合理。遥测数据表明：锂离子蓄电池组在轨运行良好,充分验证了地面设计,为锂离子蓄电池组后续在GEO卫星上的大量应用打下了良好的基础。     

Investigating electrical contact resistance losses in lithium-ion battery assemblies for hybrid and electric vehicles

Lithium-ion (Li-ion) batteries are favored in hybrid-electric vehicles and electric vehicles for their outstanding power characteristics. In this paper the energy loss due to electrical contact resistance (ECR) at the interface of electrodes and current-collector bars in Li-ion battery assemblies is investigated for the first time. ECR is a direct result of contact surface imperfections, i.e., roughness and out-of-flatness, and acts as an ohmic resistance at the electrode-collector joints. A custom-designed testbed is developed to conduct a systematic experimental study. ECR is measured at separable bolted electrode connections of a sample Li-ion battery, and a straightforward analysis to evaluate the relevant energy loss is presented. Through the experiments, it is observed that ECR is an important issue in energy management of Li-ion batteries. Effects of surface imperfection, contact pressure, joint type, collector bar material, and interfacial materials on ECR are highlighted. The obtained data show that in the considered Li-ion battery, the energy loss due to ECR can be as high as 20% of the total energy flow in and out of the battery under normal operating conditions. However, ECR loss can be reduced to 6% when proper joint pressure and/or surface treatment are used. A poor connection at the electrode-collector interface can lead to a significant battery energy loss as heat generated at the interface. Consequently, a heat flow can be initiated from the electrodes towards the internal battery structure, which results in a considerable temperature increase and onset of thermal runaway. At sever conditions, heat generation due to ECR might cause serious safety issues, sparks, and even melting of the electrodes.     

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.     

异型聚合物锂离子电池扭转条件下的电性能有限元分析

基于有限元的思想,将异型聚合物锂离子电池结构能源构件等效为许多块微平板电池的组合,通过研究平板电池纯扭转条件下单位长度扭转角与电性能的关系,结合构件的有限元力学模型,引用材料力学、弹性力学等相关理论,建立了复杂曲面构件扭转承载条件下的电性能有限元分析模型,初步实现了构件扭转条件下,力学性能与电性能的同步校核,为有限元思想应用于复杂结构能源构件的设计及承载条件下的电性能研究做了有益探讨。     

Development of the inorganic composite phase change materials for passive thermal management of Li-ion batteries: material characterization

The battery thermal management system based on phase change materials (PCMs) has proven to be a safe, inexpensive, and high-performance technology, which is currently gaining popularity over the other battery thermal management systems. PCMs are able to absorb heat generated by batteries, prolong battery life, and improve their performance. Organic compounds, such as paraffin, are widely used as phase change materials for the battery thermal management systems; however, there are no published data on the application of inorganic PCMs. Therefore, the main objective of this work is developing of two composite inorganic PCMs based on magnesium chloride hexahydrate and characterizing their properties for passive thermal control of lithium-ion battery packs. Moreover, to have a valid baseline and compare the behavior of two inorganic PCMs with currently commercialized and well investigated organic PCM, paraffin wax was used as reference material for both mixtures. All three PCMs were impregnated into the expanded graphite matrix to enhance their thermal conductivity. The material characterization studies, including thermal properties investigation, density and viscosity measurements, soaking and compression testing, evaluation of thermal expansion, thermal conductivity, and micro X-ray fluorescence analysis, were conducted for all PCMs. The results indicate that both inorganic mixtures are appropriate for thermal management of Li-ion battery packs. Future work with the developed and characterized composite inorganic PCMs will include electrical cycling studies and nail penetration tests to reveal their effectiveness for passive thermal management of Li-ion battery packs.     

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。     

Autonomous health management design for lithium-ion battery in middle and high orbit satellites

针对中高轨卫星蓄电池组在轨管理问题,在分析某型号在轨使用需求和锂离子蓄电池特性的基础上,提出了锂离子蓄电池在轨自主健康管理系统的设计,并在某MEO轨道卫星上进行了验证,通过在轨数据分析,验证了所设计系统的有效性,为后续型号锂离子蓄电池组在轨自主管理提供经验。     

圆柱形锂离子电池热管理实验研究

保持合适的运行温度是锂离子电池高效、安全、长寿命的保证,因而对其进行有效的热管理是非常有必要的。本文针对圆柱形锂离子电池,设计了嵌套电池表面的方形金属外壳,以强化电池散热和单体电池间传热。对比自然对流条件下电池单体加壳和无壳时不同放电倍率的温升情况、多个电池并联的温升情况,以及不同通风功率下多个电池并联时嵌套不同外壳的温升情况,发现加壳可以有效促进电池（组）散热。另外,设计了电池组内不同单体电池出现放电不均衡情况,以检验嵌套外壳对减小电池组内单体电池间温差的效果,结果表明,自然对流条件下,加壳后单体电池间最大温差可以降低10℃以上。     

Progress on high energy density lithium batteries by CAS battery research group

提高动力电池的能量密度将显著延长续航里程,对发展电动汽车具有重要的意义.中国科学院在2013年底部署了中国科学院战略性先导科技专项,通过合作研究,积极探索了第三代锂离子电池,固态锂电池,锂-硫电池和锂-空气电池等电池体系.其中,采用纳米硅碳负极,富锂正极的24 A·h的锂离子电池单体,质量能量密度达到374 W·h/kg,体积能量密度达到577 W·h/L.8 A·h固态聚合物锂电池60 ℃下能量密度达到240 W·h/kg,基于无机陶瓷固态电解质的固态锂电池室温下能量密度达到240 W·h/kg.37 A·h的锂硫电池单体室温能量密度达到566 W·h/kg,50 ℃达到616 W·h/kg.5 A·h锂空气电池单体能量密度达到526 W·h/kg.目前这些样品电池在综合技术指标方面离实际应用还有较大的距离,需要进一步深入细致的进行基础科学与关键技术方面的研究.从长远考虑,电池能量密度的提高必然进一步增加电池安全性风险,因此不同形式的固态锂电池将是未来长续航动力锂电池的发展方向.     

Fundamental scientific aspects of lithium batteries(I)--Thermodynamic calculations of theoretical energy densities of chemical energy storage systems

本文主要讨论电池的能量密度.基于热力学数据,根据能斯特方程,可以计算不同电化学反应体系的理论能量储存密度,从而了解化学储能体系理论能量密度的上限,了解哪些体系能够实现更高的能量密度,哪些材料具有更高的电压.     

An equivalent circuit model of a deformed Li-ion battery with parameter identification

A new equivalent circuit model (ECM) of a Li-ion battery is developed in this study. The developed model is utilized to obtain the dynamic electrical response of the battery when it is deformed under external force. Compared with other models, this model is developed based on a modified Thevenin model, and the parameters of the developed model are relevant to state of charge, the battery surface temperature, and the deformation. In this study, to obtain the real electrical response of the battery when it deformed under external force, batteries that are compressed by different deformations from 0 to 5 mm are studied with pulse discharging tests. Then, the parameters of the circuit elements are identified by a differential evolution algorithm based on the data obtained from these tests. Moreover, the data from the pulse discharging tests of batteries compressed by 3.5, 4.25, and 4.5 mm and the data from the pulse charging tests of batteries compressed by 0 and 1 mm are used to verify the parameters. The results illustrate that the battery capacity should drop significantly when the battery is severely deformed, but the battery still can be charged and discharged. Most importantly, the discharging curves of these tested deformed batteries are similar to those of undeformed ones. Moreover, the developed new ECM can predict the dynamic electrical response of a deformed battery accurately.     

Measurement of heat generation in a 40 Ah LiFePO4 prismatic battery using accelerating rate calorimetry

Accurate characterization of the heat generation behavior of a battery is crucial to a good design of its thermal management system. Concerning the thermal properties, much attention has been paid to small-sized batteries such as the 18650- or button-type and little information is available for large-capacity Li-ion prismatic cells under adiabatic conditions. In this work, heat generation of a commercial 40 Ah prismatic LiFePO₄/C battery is evaluated using an accelerating rate calorimeter under an adiabatic condition. The battery cell is charged or discharged at an initial temperature from ?12.5 to 40 °C and a current rate from 0.2C to 2C. The experiment results show that heat generated in the battery is highly dependent on its operating temperature, state of charge and current rate. Internal resistance and entropy coefficient of the battery cell are also determined by the Hybrid Pulse Power Characterization method and potentiometric method, respectively. Relationship between the internal resistance and the heat generation behavior is highlighted. Entropy coefficient and volumetric heat generation rate of the battery cell obtained in this work are compared with those of other Li-ion batteries reported in literature.     

A critical review on progress of the electrode materials of vanadium redox flow battery

Nowadays, renewable energy sources are taken great attention by the researchers and the investors around the world due to increasing energy demand of today's knowledge societies. Since these sources are non-continuous, the effective storage and re-use of the energy produced from renewable energy sources have great importance. Although classical energy storage systems such as lead acid batteries and Li-ion batteries can be used for this goal, the new generation energy storage system is needed for large-scale energy storage applications. In this point, vanadium redox flow batteries (VRFBs) are shinning like a star for this area. VRFBs consist of electrode, electrolyte, and membrane component. The battery electrodes as positive and negative electrodes play a key role on the performance and cyclic life of the system. In this work, electrode materials used as positive electrode, negative electrode, and both of electrodes in the latest literature were complained and presented. From graphene-coated and heteroatom-doped carbon-based electrodes to metal oxides decorated carbon-based electrodes, a large scale on the modification of carbon-based electrodes is available on the electrode materials of the VRFBs. By the discovering of novel electrode components for the battery system, the using of the VRFBs probably increase in a short time for many industrial and residential applications.     

Directly connected series coupled HTPEM fuel cell stacks to a Li-ion battery DC bus for a fuel cell electrical vehicle

The work presented in this paper examines the use of pure hydrogen fuelled high temperature polymer electrolyte membrane (HTPEM) fuel cell stacks in an electrical car, charging a Li-ion battery pack. The car is equipped with two branches of two series coupled 1 kW fuel cell stacks which are connected directly parallel to the battery pack during operation. This enables efficient charging of the batteries for increased driving range. With no power electronics used, the fuel cell stacks follow the battery pack voltage, and charge the batteries passively. This saves the electrical and economical losses related to these components and their added system complexity. The new car battery pack consists of 23 Li-ion battery cells and the charging and discharging are monitored by a battery management system (BMS) which ensures safe operating conditions for the batteries. The direct connection of the fuel cell stacks to the batteries can only be made if the stacks are carefully dimensioned to the battery voltage. The experimental results of stationary fuel cell charging are presented, showing stable and efficient operation.     

Recycling mobile phone batteries for lighting

The fast evolution of technology and over production of mobile electronic devices leads to their short usage period and therefore may be a source of environmental pollution and contributes to global warming. Fortunately, due to the properties of the lithium ion (Li-ion) battery that powers these mobile devices, there is a lot of life left for the battery when the device is sent to recycle. This e-waste can be valued by giving to the batteries a second life as energy storage for solar lighting. In fact, it can be a real opportunity for access to electricity in remote rural areas of developing countries for low cost and quality lighting. We show that the usage of recycled mobile phone batteries associated with a solar panel and a light emitting diode (LED) lamp can be a good replacement for candles and kerosene lamps that are hazardous and only give poor lighting quality. Such a replacement can be done for a much lower cost than current expenses, better quality of light and contributes to poverty alleviation and jobs creation. This overcomes the challenges of cost and durability in small off-grid photovoltaic systems.     

Illustration of experimental,machine learning,and characterization methods for study of performance of Li-ion batteries

The development of fault diagnosis of Li-ion batteries used in electric vehicles is vital. In this perspective, the present work conducted a comprehensive study for the evaluation of coupled and interactive influence of charging ratio, number of cycles, and voltage on the discharge capacity of Li-ion batteries to predict the life of battery. The charging-discharging experimental tests on Li-ion batteries have been performed. The data such as charging ratio, number of cycles, voltage, and discharge capacity of Li-ion batteries are measured. Machine learning approach of neural networks is then applied on the obtained data to compute the effects, normal distribution, parametric analysis, and sensitivity analysis of the input parameters on the capacity of battery. It can be noticed that discharge capacity increased with an increase in full voltage. Further, it has been observed from the sensitivity analysis that the full voltage is most relevant parameters to the capacity of the battery. Additionally, scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) of the electrodes before and after experiments have been performed, to investigate the elemental dissolution due to the charging/discharging cycles. The findings and analysis from the proposed study shall facilitate experts in making decisions on the remaining life and charging capacity of the battery.