Testing of the performance and energy-storage applied for retired LiFePO4 batteries

针对某电动公交车退役LiFePO₄动力电池,测试了电池的容量、直流内阻、常温下的储存性能,进而测试电池的倍率充放电性能、高低温特性和循环性能,分析了新旧电池相关参数的差异及变化规律;在此基础上,重组电池模组,测试其循环性能;最后集成了1MW·h梯次利用电池储能系统并参与风电平滑。结果显示,该动力电池容量衰退初始容量75%左右时,直流内阻只有小幅增加,电池常温下的储存性能、倍率性能、高低温性能下降不显著,电池单体和模块的循环性能良好,显示出该退役LiFePO₄电池具有较好的梯次利用价值。     

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。     

Influence of cycling current and power profiles on the cycle life of lead/acid batteries

Batteries are assembled with positive plates of the novel strap grid tubular (SGTP) design described in a previous paper [1]. These batteries are subjected to four tests: (i) Peukert dependence determinations; (ii) classical galvanostatic cycling (5 h charge and 1 h discharge); (iii) EV-SFUDS, and (iv) EV-ECE-15 cycling tests. It has been established that the Peukert dependence curve of SGTP batteries is very close in profile to that for SLI batteries. This guarantees SGTP's batteries high power performance. These batteries endure over 950 cycles on galvanostatic cycling. When cycled according to the SFUDS power profile under a current load of 320 A/kg positive active mass during the 15th SFUDS step, SGTP batteries exhibit a cycle life of 350–450 cycles. If the current density during the 15th step is 190 A/kg PAM, the batteries endure over 600 charge/discharge cycles. The life of positive SGT plates is limited by power loss, but not by capacity. Similar results have also been obtained from ECE-15 cycle-life tests. On cycling SGTP batteries with a current load of 210 A/kg PAM during the 23rd ECE-15 step (the step during which maximum power output is demanded from the battery), they endure between 550 and 650 charge/discharge cycles. A summary of the test results obtained for two batches of experimental batteries indicates that there is a direct dependence between the SGTP battery cycle life and the maximum current density on discharge. Increasing the discharge current density decreases the battery life. It has also been established that the capacity on SFUDS (ECE-15) discharge declines gradually on cycling in favour of the residual galvanostatic capacity at 5 h rate of discharge (100% depth-of-discharge) which increases. This implies that two types of structures are formed in the positive plates on cycling: the first type ensuring high power output and the second type yielding low power but long cycle life. The higher the power delivered by the positive plate, the faster the conversion of the structure supporting this high power output into such yielding low power performance. EV-SFUDS: A simplified version of the Federal urban driving schedule for electric vehicle battery testing, US Department of Energy, USA, 1988, and ECE-15: a standard European test cycle, speed versus time.     

Review of research on heat generation characteristics during charging and discharging of lithium ion batteries

电动车辆的性能和成本很大程度上取决于动力电池组的性能和使用寿命,而电池组的性能和使用寿命又受到电池单体产热的影响。研究锂离子电池充放电过程中的产热特性及影响因素,对锂电池的开发及使用具有指导意义。本文从环境温度、充放电倍率、电池材料、荷电状态和老化程度五个方面入手,综述了各因素对锂离子电池产热的影响。     

Thermal behavior of a weatherproof power supply system with built-in nickel-metal hydride batteries developed for stationary use

The thermal design of weatherproof power supply system has been evaluated by experiments and simulation. Nickel-metal hydride batteries developed for stationary use were employed in the system due to their high charge/discharge performance in high-temperature environments. As the weatherproof power supply system has a sealed cabinet, we evaluated the temperature characteristics of the battery in a 40 °C environment. In order to predict the temperature of the power system, it was necessary to obtain the rate of heat generation from the battery. For this purpose, we developed an estimation method in which the measured temperature of the battery is approximated as a function of cubic spline interpolation. The temperatures of critical items mounted in the system were calculated on the basis of the experimental results. This paper describes the procedure for estimating the heat generation rate of the battery and the temperature of the system. Our results show that the weatherproof power system is useful for operation in high-temperature environments.     

Calculation of temperature rise in lithium polymer batteries of Sandia conceptual designs during USABC Dynamic Stress Test

Based on reported galvanostatic charge and discharge data of a Li/P(EO)₈LiClO₄/TiS₂ cell, heat generation rates within a battery during the USABC Dynamic Stress Test (DST) were calculated and compared with those during the Simplified Federal Urban Driving Schedule (SFUDS) dynamic power profile. Also, calculations of temperature rise in the C/Polymer electrolyte/LiMn₂O₄ batteries of Sandia conceptual designs for a Ford van and GM Impact, during a DST/Fast Charge/DST/Full Charge cycle were conducted with a three-dimensional thermal model.     

Electrical‐thermal behaviors of a cylindrical graphite‐NCA Li‐ion battery responding to external short circuit operation

Large amount of heat generated during an external short circuit (ESC) process may cause battery safety events. An experimental platform is established to explore the battery electrothermal characteristics during ESC faults. For 18650‐type nickel cobalt aluminum (NCA) batteries, ESC fault tests of different initial state of charge (SOC) values, different external resistances, or different ambient temperatures are carried out. The test case of a smaller external resistance is characterized by a shorter ESC duration with a faster cell temperature rise, whereas the case of a larger external resistance will last for a longer duration, discharge more electricity, and terminate in a slightly higher temperature. The tested batteries of high initial SOCs generally have higher temperature rise rates, smoother changes at the output current/voltage curves, but a smaller discharged capacity. The batteries of low initial SOCs can be overdischarged by the ESC operations. At low temperatures, say 0°C, the ESC process outputs much less electricity than the process at high temperatures, eg, 30°C. The initial low temperature has little effect on reducing the battery overheat due to ESC operations. The battery thermal behavior is of hysteresis property; analysis of heat generations reveals the subsequent increase of battery surface temperature after the completion of ESC discharge is due to the battery material abusive reaction heats. It is found from analytical and numerical analyses that there can have approximately 30°C temperature difference between the battery core and its surface during ESC operations. The interruption of ESC operation is very probably caused by the high battery core temperature, which leads to the destruction of solid‐electrolyte interface (SEI) film.     

Hydrogen-absorbing alloys for the NICKEL–METAL hydride battery

In recent years, owing to the rapid development of portable electronic and electrical appliances, the market for rechargeable batteries has increased at a high rate. The nickel-metal hydride battery (Ni/MH) is one of the more promising types, because of its high capacity, high-rate charge/discharge capability and non-polluting nature. This type of battery uses a hydrogen storage alloy as its negative electrode. The characteristics of the Ni/MH battery, including discharge voltage, high-rate discharge capability and charge/discharge cycle lifetime are mainly determined by the construction of the negative electrode and the composition of the hydrogen-absorbing alloy. The negative electrode of the Ni/MH battery described in this paper was made from a mixture of hydrogen-absorbing alloy, nickel powder and polytetrafluoroethylene (PTFE). A multicomponent MmNi₅-based alloy (Mm_0.95Ti_0.05Ni_3.85 Co_0.45Mn_0.35Al_0.35) was used as the hydrogen-absorbing alloy. The discharge characteristics of the negative electrode, including discharge capacity, cycle lifetime, and polarization overpotential, were studied by means of electrochemical experiments and analysis. The decay of the discharge capacity for the Ni/MH battery (AA size, 1 Ah) was about 1% after 100 charge/discharge cycles and 10% after 500 charge/discharge cycles.     

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.     

Characterization of MnO2 positive electrode for Fuel Cell/Battery (FCB)

The use of manganese dioxide (MnO₂) as a positive electrode material in Fuel Cell/Battery (FCB) systems is described. A positive electrode containing MnO₂ was fabricated and its performance was evaluated for charge/discharge behavior in three different systems: (i) secondary battery positive electrode, (ii) positive electrode in an alkaline fuel cell, and (iii) positive electrode performance in an FCB system by performing half cell tests. MnO₂ was observed to possess redox capabilities as the positive electrode of a secondary battery when it was subject to charge/discharge cycles. It was found that Mn₃O₄, which inhibits the discharge reaction, was produced during charge/discharge cycles. The I–V characteristics of MnO₂ material were measured to check the feasibility of the fuel cell system by supplying H₂ into the negative electrode and O₂ into the MnO₂ positive electrode, respectively. The MnO₂ electrode showed similar performance to Ni electrode, which was fabricated by using a similar method to the MnO₂ electrode. The MnO₂ electrode also showed that it functioned as an FCB positive electrode, which was confirmed by continued production of current when the O₂ supply was terminated. These results suggest that MnO₂ is a good candidate for an FCB positive electrode material.     

基于伪二维电化学-热耦合模型的锂电池热特性研究

锂电池放电过程中的产热受电池内部电化学反应和欧姆效应影响,电池产热由电池化学与动力学决定,而电池动力学依赖于电池运行条件和设计参数。锂电池的六个温度依赖性参数对锂电池的放电过程中的产热速率具有影响,包括固相活性颗粒和电解液中的锂离子扩散系数、反应速率常数、电极开路电压、电解液离子电导率、热力学因子和阳离子迁移数。基于LiFePO_4圆柱形电池建立了伪二维电化学-热耦合模型,研究电池在恒流放电过程中的产热速率,以及正极、隔膜和负极各部分的产热速率和所占比例。结果表明,总产热功率随反应热的波动而变化,其中正极电极层中反应热占比最大,负极电极层中极化产热所占比例高于正极,而隔膜中的产热主要来源自欧姆热。不同对流传热系数条件下,电池的表面温度和内部温度差都不同,因此要合理的采取电池热管理措施。     

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。     

Voltage and capacity stability of the Hubble telescope nickel-hydrogen battery

The power system of the Hubble Space Telescope includes two orbital replacement units, each containing three nickel-hydrogen (NiH₂) batteries of 88 Ah capacity. Since launch in April 1990, the batteries have completed 23 000 charge and discharge cycles and continue to meet the power demands of the satellite. The voltage, capacity, and pressure characteristics of all six batteries were analyzed to determine the state of health of the battery and to identify any signs of performance degradation. The battery pressures have changed to varying degrees. The end-of-charge pressure for battery 4 increased by 96 psi, while that for battery 3 decreased by 37 psi. The voltages of the individual cells show a decay rate of 0.69 mV per 1000 cycles, and the capacity of the batteries has apparently decreased, possibly due to the system being operated at a lower stage of charge. Autonomous battery operation involving charge termination at a preselected voltage continues to restore the energy dissipated during each orbit. The accumulated data on voltages and recharge ratios can be used to design new temperature-compensated voltage levels for similar missions that employ NiH₂ batteries.     

Thermal analysis and management of lithium-titanate batteries

Battery electric vehicles and hybrid electric vehicles demand batteries that can store large amounts of energy in addition to accommodating large charge and discharge currents without compromising battery life. Lithium-titanate batteries have recently become an attractive option for this application. High current thresholds allow these cells to be charged quickly as well as supply the power needed to drive such vehicles. These large currents generate substantial amounts of waste heat due to loss mechanisms arising from the cell's internal chemistry and ohmic resistance. During normal vehicle operation, an active cooling system must be implemented to maintain a safe cell temperature and improve battery performance and life. This paper outlines a method to conduct thermal analysis of lithium-titanate cells under laboratory conditions. Thermochromic liquid crystals were implemented to instantaneously measure the entire surface temperature field of the cell. The resulting temperature measurements were used to evaluate the effectiveness of an active cooling system developed and tested in our laboratory for the thermal management of lithium-titanate cells.     

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.     

Thermal behaviors of Ni-MH batteries using a novel impedance spectroscopy

In this paper, a novel impedance spectroscopy was used to describe the thermal behaviors of Ni-MH batteries. The impedance functions were derived similarly to electric impedance functions. The square of current was treated as a current equivalent and heat-flow as a voltage equivalent. The impedance spectra of batteries during charge showed that the combination of hydrogen and oxygen increased rapidly when charge rate was higher than 0.5 C. Thermal runaway might happen when battery was charged at temperature above 348 K even at a low charge rate. The cycling test showed that the charge efficiency of battery was the highest after cycling at high-rate for 10–100 cycles and decreased after more cycles. Different batteries showed different thermal behaviors which may be caused by the different structures of batteries.     

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.     

Effects of electrolyte agitation on the performance of lead—acid traction batteries at various temperatures

A detailed study of electrolyte concentration gradients within a commercial lead—acid battery showed that performance could be improved by disturbing the stratification which builds up during discharge—charge cycles. A simple, low-cost pumping device, which operates on pulsed air, without any moving parts was developed. A 96 V lead—acid traction battery was modified and tested at various temperatures. The performances of agitated and unagitated batteries are compared.     

Modeling of the capacity loss of a 12 V automotive lead-acid battery due to ageing and comparison with measurement data

One-dimensional modeling was carried-out to predict the capacity loss of a 12 V automotive lead-acid battery due to ageing. The model not only accounted for electrochemical kinetics and ionic mass transfer in a battery cell, but also considered the anodic corrosion of lead in sulfuric acid. In order to validate the modeling, modeling results were compared with the measurement data of the cycling behaviors of the lead-acid batteries having nominal capacity of 68 Ah that are mounted on the automobiles manufactured by Hyundai Motor Company. The cycling was performed under the protocol of the constant-current discharge and the constant-voltage charge. The discharge rate of C/3 was used. The range of state of charge was between 1 and 0.85. The voltage was kept constant at the gassing voltage until the charge current tapered to 10 mA. The retention capacity of the battery was measured with C/3 discharge rate before the beginning of cycling and after every 40 cycles of cycling. The modeling results were in good agreement with the measurement data.     

基于深度神经网络的梯次利用电池健康状态评估

随着大量退役电池梯次利用,对退役动力电池健康状态的准确估计是保障电池梯次利用安全高效运行的前提。针对上述问题,提出基于深度神经网络学习的梯次利用电池健康状态评估方法。根据不同循环次数下梯次利用电池充放电性能的差异性,从梯次利用电池物理特性角度挖掘影响梯次利用电池老化特征的主要参数,利用皮尔逊法计算电池老化特征与梯次利用电池健康状态的相关系数,选取较高相关度特征作为深度神经网络的输入,建立基于深度神经网络学习的梯次利用电池健康状态评估模型。通过美国国家航空航天局Ames卓越预测中心的锂离子电池测试数据仿真实例验证了该文方法的有效性。仿真结果表明,与传统神经网络相比,深度神经网络学习可明显提高梯次利用电池健康状态的预测精度,为退役动力电池健康状态评估提供理论依据。