Effect of combinations of additives on the performance of lithium ion batteries

Commercial lithium-ion batteries have excellent performance at room temperature for a few years. However, the calendar life and thermal stability (>50 °C) need to be improved for many applications, including electric vehicles. We have conducted an investigation of the effect of thermal stabilizing additives, including dimethyl acetamide, vinylene carbonate, and lithium bis(oxalato) borate, on the performance of lithium ion batteries stored at 70 °C for one month. The reactions of the lithium hexafluorophosphate/carbonate electrolyte, with and without electrolyte additives, with the surface of the electrodes after initial formation cycling have been analyzed via a combination of IR-ATR and XPS.     

Three-dimensional thermal finite element modeling of lithium-ion battery in thermal abuse application

In order to better understand the thermal abuse behavior of high capacities and large power lithium-ion batteries for electric vehicle application, a three-dimensional thermal model has been developed for analyzing the temperature distribution under abuse conditions. The model takes into account the effects of heat generation, internal conduction and convection, and external heat dissipation to predict the temperature distribution in a battery. Three-dimensional model also considers the geometrical features to simulate oven test, which are significant in larger cells for electric vehicle application. The model predictions are compared to oven test results for VLP 50/62/100S-Fe (3.2 V/55 Ah) LiFePO₄/graphite cells and shown to be in great agreement.     

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.     

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.     

Computational battery dynamics (CBD)—electrochemical/thermal coupled modeling and multi-scale modeling

This paper reviews the development of first-principles based mathematical models for batteries developed on a framework parallel to computation fluid dynamics (CFD), herein termed computational battery dynamics (CBD). This general-purpose framework makes use of the similarity in the equations governing different battery systems, and has resulted in the development of robust models in a relatively short time. Here we review this framework, in the context of applications to the coupled modeling of the thermal and electrochemical behavior of cells, and to the modeling at three different scales, namely pore-level, cell-level and stack-level. The similarity and differences of our approach with other research groups are exemplified. Significant results from each of these advanced applications of modeling are highlighted with emphasis on the insights that can be gained from a first-principles model. In addition, we also demonstrate the usefulness of a combined experimental-modeling approach in describing cells. The models reviewed here are expected to be useful in predicting the behavior of advanced batteries used in electric vehicles (EVs) and hybrid electric vehicles (HEVs).     

Metal/air batteries: Their status and potential — a review

Considerable work was carried out on metal/air batteries in the 1960's and early 1970's for a variety of applications. After this time, however, the overall effort was considerably reduced due to materials problems at the air electrode, thermal management, and miscellaneous technical problems associated with the various anodes evaluated. Recent advances in the performance and stability of air cathodes, together with new and improved candidate anodes, make a comparison of metal/air batteries appropriate at this time.This review concentrates on comparing lithium, aluminum, magnesium, zinc and iron/air batteries with particular emphasis on the suitability of each system for electric vehicle propulsion. The relative merits of mechanically and electrically rechargeable batteries are given, together with systems employing static and circulating electrolytes.We conclude that, due to the institutional difficulties associated with the deployment of recharge systems for mechanically rechargeable batteries in electric vehicles, electrically rechargeable systems are more viable for commercialization in the near term. This conclusion makes zinc/air and iron/air batteries major candidates for this application.     

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.     

A full model for simulation of electrochemical cells including complex behavior

This communication presents a model of electrochemical cells developed in order to simulate their electrical, chemical and thermal behavior showing the differences when thermal effects are or not considered in the charge–discharge process. The work presented here has been applied to the particular case of the Pb,PbSO₄|H₂SO₄ (aq)|PbO₂,Pb cell, which forms the basis of the lead-acid batteries so widely used in the automotive industry and as traction batteries in electric or hybrid vehicles.     

All-solid-state lithium-ion batteries:State-of-the-art development and perspective

现有电化学储能锂离子电池系统采用液体电解质,易泄露,易腐蚀,服役寿命短,具有安全隐患.薄膜型全固态锂电池,大容量聚合物全固态锂电池和大容量无机全固态锂电池是一类以非可燃性固体电解质取代传统锂离子电池中液态电解质,锂离子通过在正负极间嵌入-脱出并与电子发生电荷交换后实现电能与化学能转换的新型高安全性锂二次电池.作者综述了各种全固态锂电池的研究和开发现状,包括固态锂电池的构造,工作原理和性能特征,锂离子固体电解质材料与电极/电解质界面调控,固态整电池技术等方面,提出并详细分析了该技术面临的主要科学与技术问题,最后指出了全固态锂电池技术未来的发展趋势.     

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。     

Global energy prospects in the 21st century: a battery-based society

Current energy needs are nearly totally dependent on fossil fuels. This is causing global warming and exhaustion of resources; it is important to switch to more efficient and effective energy use. These circumstances are expanding the role of secondary batteries. Non-fossil fuels such as photovoltaic cells and wind energy are unstable, but combining them with secondary batteries improves their stability as electric power sources. If electrical load leveling between day and night can be achieved by storing electric power, it will be possible to achieve a high capacity utilization rate for generating facilities that have high generating efficiency and produce little CO₂. Depending on the generating mix, the practicalization of electric vehicles will serve not only to alleviate air pollution, but also to limit CO₂ emissions. There are hopes for the development of large-capacity lithium secondary batteries with long cycle life, high energy density, high power density, and high energy efficiency.     

Experimental investigation of thermal management system for lithium ion batteries module with coupling effect by heat sheets and phase change materials

Some potential safety risks for lithium ion battery such as overheating, combustion, and explosion occurred in practical application may cause accidents of electric vehicles. Phase change material (PCM)‐based thermal management system was demonstrated as a feasible approach. However, the batteries have to endure various environment and climate, which would not work normally under cold area. Especially when the surrounding temperature falls to below 10°C, which can bring about the energy and power of Li‐ion batteries rapidly reducing. In this study, a coupling heating strategy of the PCM‐based batteries module with 2 heat sheets at low temperature was proposed for batteries module and cannot only balance the temperature among different batteries in the module but also ensure to pre‐heat the batteries module at low temperature. The experiment displayed that 7% of EG in paraffin‐based composite PCMs was the best proportion for batteries module, considering both fluidity and thermal conductivity factors. In addition, the temperature difference of PCM‐based batteries module was 2.82°C, while that of the air‐based one was 14.49°C, which was 5 times more than former, exhibiting an excellent performance in balancing temperature uniformly, and was beneficial for prolonging the lifespan of batteries. The coupling heating strategy‐based PCM with heat sheets provided as an extremely promising technology for lithium batteries module at low temperature.     

Recent progress of electrode materials for room-temperature sodium-ion stationary batteries

随着风能、太阳能等可再生能源的不断发展,储能作为影响其发展的关键技术越来越受到人们的关注。在储能领域,锂离子电池以高能量密度、长循环寿命、高电压等诸多优点在电子领域已得到广泛的应用,并成为未来电动汽车动力电池的最佳选择。但因锂资源储量有限、分布不均匀,而且原材料成本比较高,所以锂离子电池在电网大规模储能方面的应用遇到了瓶颈。与锂相比,钠不但具有与锂相似的物理化学性质,更具有资源丰富、分布广泛、原料成本低廉等优势。近些年室温钠离子电池再次引起了人们的研究兴趣,特别是在电网储能方面表现出极大的应用潜力。虽然目前已报道了多种钠离子电池电极材料,但大都离实用化以及进一步产业化尚有一定的距离。本文重点介绍一些性能较为突出的室温钠离子电池电极材料,并指出要实现钠离子电池的产业化,需要开发空气中稳定、高安全、高容量、高倍率、循环稳定、低成本的新型正、负极材料。     

One-dimensional dynamic modeling and validation of maintenance-free lead-acid batteries emphasizing temperature effects

Lead acid batteries are still widely used for SLI (Starting-Lighting-Ignition) systems in vehicles because of the cost advantage. The batteries are frequently charged and discharged under different operation conditions, which continuously changes distribution of inner temperature of batteries. Variation of the temperature distributions significantly affects performance and durability of the battery. We developed a one-dimensional dynamic model based on the first principle of thermal dynamics and electrochemistry. The thermal model incorporates control volumes for each of the major constituents of the battery cells that is casing, electrolyte, and electrodes. The model was extended for a six-cell battery and used to analyze effects of discharging currents on the performances and temperature, compared with results from a three-dimensional finite element analysis and tested against experimental results obtained from a thermal chamber and using thermal imaging.     

Fundamental scientific aspects of lithium batteries (Ⅷ)----Anode electrode materials

锂离子电池的成功商业化,起始于石油焦负极材料.负极作为锂离子电池必不可少的关键材料,目前主要集中在碳,钛酸锂以及硅基等合金类负极,采用传统的碳负极可以基本满足消费电子,动力电池,储能电池的要求,采用钛酸锂可以满足高功率密度,长循环寿命的要求,采用合金类负极材料有望进一步提高能量密度.本文小结了目前广泛使用和正在研究的锂离子电池负极材料的性能特点,讨论了下一代锂离子电池负极材料的研究和发展状况.     

Thermal safety study of Li-ion batteries under limited overcharge abuse based on coupled electrochemical-thermal model

Many fire accidents of electric vehicles were reported that happened during the charging process. In order to investigate the reasons that lead to this problem, this paper studies the thermal safety of Li-ion batteries under limited overcharge abuse. A 3D electrochemical-thermal coupled model is developed for modeling thermal and electrochemical characteristics from normal charge to early overcharge state. This model is validated by experiment at charge rates of 0.5C, 1C, and 2C. The simulation results indicate that irreversible heat contributes most to temperature rise during the normal charge process, but the heat induced by Mn dissolution and Li deposition gradually dominates heat generation in the early overcharge period. Based on this, a threshold selection method for multistage warning of batteries overcharge is proposed. Among them, level 1 should be considered as a critical stage during the early overcharge process due to the deposited lithium starts to react with electrolyte at the end of level 1, where temperature rate increases to 0.5°C min⁻¹ for 1C charge. While the thresholds of levels depend on charge rate and composition of battery. Furthermore, several critical parameters are analyzed to figure out their effects on thermal safety. It is found that the temperature at the end of overcharge is significantly influenced by the change of positive electrode thickness and solid electrolyte interface (SEI) film resistance. The final temperature increases by 17.5°C and 7.9°C, respectively, with positive electrode thickness ranging from 50 to 80 μm and SEI film resistance increasing from 0.002 to 0.03 Ω.     

Fuzzy logic modelling of state-of-charge and available capacity of nickel/metal hydride batteries

Ni/MH batteries are playing important roles in many applications such as power tools, and a dominant role in hybrid electric vehicles (HEVs). In the case of HEVs it is particularly important to be able to monitor the state-of-charge (SoC) of the Ni/MH batteries. We have previously reported on the use of a fuzzy logic (FL) methodology to estimate the SoC of various battery chemistries, including lead-acid and lithium sulfur dioxide.In the present work, we have measured electrochemical impedance spectroscopy (EIS) on 2.7 Ah Sanyo Ni/MH cells and two- and three-cell strings of these cells at different SoC’s and over 100 cycles. We have been able to select features in this data to develop fuzzy logic models for both available capacity and SoC estimation, simply by measuring the impedance at three frequencies. The fuzzy logic model estimates the SoC to within ±5%. In this paper we will present the details of the experimental measurements, the details of the fuzzy logic models themselves, and the resulting accuracies of the developed models.     

In situ observation of lithium dendrite on the electrode in a lithium-ion battery

锂离子电池尽管已成为便携式电子设备的主流电源,也是电动汽车、混合动力汽车等电源的主要选择之一,但依然存在使用过程中因形成锂枝晶而发生内短路的安全隐患。本文设计了一个宏微观实验研究商业用锂离子电池电极材料的充放电循环性能。在常温小电流充放电条件下,实时原位地观测锂枝晶的产生、生长、消融以及死锂残留等过程。实验结果揭示了锂枝晶不仅仅只是大电流过充或低温充电状态下的产物,常温常态小电流充电条件下依然能够生成锂枝晶。实验发现：锂枝晶出现在充电后期,随后直线伸长,尖端区域形貌保持不变;放电时,锂枝晶逐渐消融,尖端区域形貌依然不变,放电结束后电极上有死锂残留。     

Thermal safety studies of high energy density lithium-ion batteries under different states of charge

The popularity of lithium-ion batteries in electric vehicles has promoted the increase of its energy density, and battery cathode and anode materials have developed rapidly in recent years. As the next generation of material systems, high-nickel-content Li-Ni-Co-Mn oxide cathode and high-silicon-content Si-C anode material systems have a high potential for further application. However, safety is a key indicator for their use in traction batteries. We thus conducted a thermal safety analysis of the pouch cells of such a system for different states of charge and revealed the key factors for the thermal safety evolution of batteries by analyzing the morphology and thermal stability of cathodes and anodes.     

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.