采用阳极预锂化技术的锂离子电池高倍率老化容量衰减机理研究

通过阳极预锂化技术,可以补充锂离子电池在化成以及后续循环过程中活性锂的损失,由此提高锂离子电池的能量密度以及循环寿命.然而阳极预锂化后锂离子电池衰减机理如何变化,一直没有明确的研究结论.本文研究了经阳极预锂化的石墨-磷酸铁锂电池在高倍率老化过程中,充放电电位、电池容量、电池健康状态(SOH)、电化学阻抗等的演变过程,并...     

锂离子电池容量衰减机理研究进展

容量衰减与电池循环寿命直接相关。导致锂离子电池容量衰减的原因主要包括：固体电解质界面膜（SEI）的增长、电解液的分解、电极材料结构破坏、活性物质的溶解和相转变等。过充过放电、不良的储存或使用温度等外部因素也会导致电池容量衰减。本文综述了近年来锂离子电池容量衰减机理的研究进展。     

锂离子电池石墨负极材料衰减机理研究

石墨负极材料因具有比容量高、价格低廉以及环境友好等特性在锂电池领域得到广泛的应用.但材料在循环过程中也显露出缺陷,如在循环过程中体积不断变化导致微裂纹、石墨化度降低、接触损失、SEI膜变化、金属锂析出、不均匀性等缺点导致其在锂电池的循环中容量衰减.本文对负极材料循环过程中容量衰减有关机理进行总结,并提出各种衰减机理的简...     

三元富镍锂离子电池不同充放电策略下的老化特性研究

在各种设备的日常使用过程中,伴随着设备老化一同到来,电池老化同样限制了设备主体的功能应用。文中针对三元高镍锂离子电池单体的老化特性进行实验测试,并通过混合脉冲功率性能测试法(HPPC)测量了电池处于不同老化阶段时的内阻值。基于锂离子电池长期充放电循环老化实验的测试数据,本文对其老化过程的容量衰减与内阻变化进行研究,并得出在2 C高倍率充电条件下,锂离子电池的容量衰减速率明显高于0.5 C与1 C倍率充电条件;荷电状态低于30%和高于60%的区间内,电池的内阻值偏大,且随着循环次数的增加,电池内阻值整体呈现上升趋势。     

锂离子电池补锂技术

锂离子电池在化成过程中,负极SEI膜的形成会消耗大量活性锂,特别是在添加部分高容量硅基负极材料的情况下,导致电池首周库仑效率和电池容量低.补充活性锂是解决这一问题的有效手段,目前已报道的补充活性锂的途径很多,主要是负极补锂和正极极补锂两大类.负极补锂包括金属锂物理混合锂化,如在负极中添加金属锂粉或在极片表面辊压金属锂箔...     

基于光学显微镜的锂离子电池材料老化衰减原位研究进展

先进锂离子电池的发展需要更高性能的电池材料或更优化的电池结构,深入了解电池材料的老化衰减机理是提高电池性能的前提。原位光学显微镜方法具有操作简便、原位反应池模拟环境真实,以及从介观到宏观的大范围尺度进行表征的特点,是目前最适合开展原位研究的表征方法。本文综述了原位光学显微镜方法在锂离子电池材料老化衰减方面的研究进展,介绍了原位光学显微镜方法中原位反应池的典型结构,阐述了该方法应用于锂离子浓度及其分布、析锂、电池材料体积膨胀与开裂和应力应变演化等方面的研究进展。最后,提出了原位光学显微镜方法在光学显微镜分辨率、原位反应池功能性、多表征方法联用以及先进图像处理和分析方法等方面的未来关注方向。     

锂离子电池低温电解液研究进展CSCD

锂离子电池低温存储技术是智慧城市发展的关键之一。商用电解液在低温下易凝固、阻抗高限制了锂离子电池的进一步应用。因此电解液的优化成为改善锂离子电池低温性能的研究热点之一。本文介绍了低温电解液的研究进展。综述了温度对锂离子电池充放电影响,提出电解液改性是提高锂离子电池低温性能的关键。低温电解液的改性主要包括锂盐、溶剂和添加剂等方面,并对锂离子电池低温性能的下一步研究进行了展望。低温电解液锂盐的研究重点在于发展具有低电荷转移阻抗和宽温范围的新体系锂盐,低温电解液溶剂的研究重点在于发展具有高介电常数的EC溶剂与低熔点的PC溶剂混合体系,低温电解液添加剂的研究重点在于传统添加剂与新型添加剂的联用。     

软包锂离子电池真空环境下循环性能特性

为研究飞行器和轨道空间站等低气压真空环境下,锂离子电池的循环安全性能。实验采用商用Li(NiCoMn)O2软包锂电池,在球舱近似真空压力下,进行0.5 C倍率循环充放电实验,并与常压环境下进行对比分析。研究发现：真空循环后,电池出现严重的大面积不可恢复形变和褶皱且厚度增加。随着循环次数增加,容量加速衰减,循环10次后容量低于80%。但恢复常压后,出现少部分容量的恢复;真空下扩大了充放电过程中的膨胀与收缩效应,加速了容量的衰减同时也造成部分容量的假性损失;电池周期性升温和降温速率加快,周期内温度不均匀性加剧,最大温差可达12.9℃,充放电的热稳定性和安全性变差,同时潜在的热灾害危害性变大。通过微分容量分析发现,低压真空环境下,所产生的活性锂的损耗和电极材料结构的损伤是降低电池循环充放性能的重要因素。     

Electrochemical analysis for cycle performance and capacity fading of a lithium-ion battery cycled at elevated temperature

Laboratory-size LiNi_0.8Co_0.15Al_0.05O₂/graphite lithium-ion pouch cells were cycled over 100% DOD at room temperature and 60 °C in order to investigate high-temperature degradation mechanisms of this important technology. Capacity fade for the cell was correlated with that for the individual components, using electrochemical analysis of the electrodes and other diagnostic techniques. The high-temperature cell lost 65% of its initial capacity after 140 cycles at 60 °C compared to only a 4% loss for the cell cycled at room temperature. Cell ohmic impedance increased significantly with a elevated temperature cycling, resulting in some of loss of capacity at the C/2 rate. However, as determined with slow rate testing of the individual electrodes, the anode retained most of its original capacity, while the cathode lost 65%, even when cycled with a fresh source of lithium. Diagnostic evaluation of cell components including X-ray diffraction (XRD), Raman, CSAFM and suggest capacity loss occurs primarily due to a rise in the impedance of the cathode, especially at the end-of-charge. The impedance rise may be caused in part by a loss of the conductive carbon at the surface of the cathode and/or by an organic film on the surface of the cathode that becomes non-ionically conductive at low lithium content.     

Patent technology development trend analysis of lithium-ion battery energy storage system

锂离子电池是目前最具发展前景的高效二次电池和发展最快的化学储能电源，已成为各国竞相竞争的技术热点。专利技术能够反映某一技术领域创新发展的现状和历程，已成为开展竞争情报的重要信息源。本文从专利角度出发，通过对锂离子电池储能系统领域专利的分析，发现和了解锂离子储能系统的发展态势，以期为我国政府与企业的战略决策提供参考与借鉴。     

Effect of the formation temperature on lithium-ion battery performance

为缩短锂电池生产工艺时间、节约成本,高温压力化成受到工艺人员的关注,本文以钴酸锂-石墨体系的软包装锂离子电池为研究对象,研究了高温压力化成工艺中温度对化成效果的影响。在某一压力作用下,采用不同化成温度,分析了不同化成温度对应的实际化成时间、化成电压、电压降以及电池倍率放电与高温处理的性能,结果显示化成温度越高,化成时间越长;在不同的温度下化成,对电池的循环性能及倍率性能影响不同。     

Simulation and verification of lithium-ion battery temperature changing process

针对软包锂离子电池放电过程中温度变化过程进行研究,依据电池产热基本理论,通过内阻实验及0.5 C放电倍率下的温升实验计算出瞬态生热率曲线,得出电池熵热系数,建立生热速率随放电深度不断变化的瞬态生热模型,基于该模型进行不同放电倍率的温度仿真模拟,并与实验进行对比。结果表明,温度变化模拟结果与实验相吻合,生热率变化模拟结果与实验计算值相符合,模型可以很好地模拟电池在不同放电倍率下的温度变化,对电池温升过程分析及电池热管理过程控制具有指导意义。     

The degradation analysis of lithium-ion storage battery with Li4Ti5O12 anode

钛酸锂作为储能电池负极材料,在长循环和安全性上有突出的表现。通过对室温1C和2C倍率下循环的三元+钴酸锂/钛酸锂储能电池拆解,结合SEM、FTIR、XRD和EIS等分析手段,发现造成容量衰减和阻抗增大的原因出现在正极,由于正极与电解液发生反应,在表面生成界面膜,并且循环过程中界面膜不稳定,进一步消耗活性锂离子导致。另外,对这款电池的产气分析发现,所产生气体的主要成分为CO2和C2H6,原因可能是在制备电池过程中严格控制水分以及在电解液添加剂方面做了改进。     

Novel composite separator for high power density lithium-ion battery

High power density is essential for next-generation lithium-ion batteries. However, it is a great challenge to achieve high-power density and safety lithium-ion batteries due to the lack of reliable separators with uniform porosity, strong mechanical flexibility, and superior electrolyte uptake. Herein, a poly (vinylidene fluoride-co-hexafluoropropylene)/graphene oxide separator with uniform porosity, strong mechanical flexibility, and superior electrolyte uptake is prepared. The incorporation of graphene oxide into a poly (vinylidene fluoride-co-hexafluoropropylene) separator provides a large number of uniform diffusion channels for lithium ions to pass through by reducing the degree of crystallinity and increasing the pore uniformity of separator. In addition, the separator has superior mechanical property and thermal stability in comparison to commercial Celgard 2325 and pure poly (vinylidene fluoride-co-hexafluoropropylene) separators. This LiFePO₄/Li cell with the prepared poly (vinylidene fluoride-co-hexafluoropropylene)/graphene oxide separator delivers a high capacity up to 160 mAh g⁻¹ at 0.5C at room temperature and can be fully charged/discharged in 6 min (10C).     

Capacity fading of the acid-treated lithium manganese oxides in high-temperature storage

We have studied capacity fadings of acid-treated lithium manganese oxides in high-temperature storage. The amounts of dissolved lithium and manganese ions and consumed acids were determined in the reaction of lithium manganese oxides with acids. Discharge capacities of the acid-treated samples were measured and the small capacity fadings were observed. X-ray diffraction patterns of the acid-treated samples were almost the same as the one before the acid-treatment.After the acid-treated samples were stored in the EC/DMC solutions without Mn and Li ions at 80 °C for 24 h, they gave no further capacity fadings. On the other hand, after the storage under the same condition but in the EC/DMC solution containing both Mn and Li ions, the same acid-treated samples as above showed large capacity fadings. Thus, the following mechanism is deduced; the acid-treated lithium manganese oxide would react with Mn and Li ions in the solution, and its spinel structure would partly be fractured to result in the severe capacity fading.     

Instantaneous estimation of internal temperature in lithium-ion battery by impedance measurement

Due to the various drawbacks of collecting temperature using embedded or patch thermocouple sensor, the internal temperature estimation is getting more and more attention in the field of lithium power battery. In this paper, the commercial 18650 LiFePO4 battery is selected to analyze the characteristic of Electrochemical Impedance Spectroscopy (EIS) from 0°C to 55°C of 0.1 to 10 000 Hz. The results reveal that there exists intrinsic relationship between the alternating current (AC) impedance phase shift and the internal temperature in the range of 10 to 100 Hz from 5 to 55°C. And the intrinsic relationship is not interfered with the State-of-Charge (SOC) and the State-of-Health (SOH). Subsequently, the relationship is described with a modified Arrhenius equation under the excitation frequency of 12, 44, and 79 Hz. Finally, a novel internal temperature estimation method is proposed by the AC impedance phase shift. The applicability and accuracy of the method are further verified via 10 temperature points. The results indicate that the estimation error is within 1°C in the common operating temperature range (15-45°C), suggesting that the proposed method can be applied to estimate battery internal temperature. Finally, the implementation system of real-time estimation for engineering application is constructed.     

锂离子电池系统低温充电策略

新能源汽车行业正迅猛发展,电动汽车的销量也屡创新高,而电动汽车在冬季低温下如何高效且经济地进行充电,仍是一个亟待解决的问题.基于充电时电池自身内阻产热的原理,提出了一种锂电池系统低温充电的策略,并在此基础上进行了改进.以最小单体电池温度为判断条件,使用多阶段恒流充电技术可以有效缩短充电时间,并保证一定的充电容量.通过研...     

动力汽车用锂电池热管理系统仿真分析

为了研究动力汽车用锂电池温度场分布,建立了单体电池及电池组仿真模型,通过实验与FLUENT软件模拟验证的方式分析单体电池温度场。通过仿真分析讨论电池组温度场,采用三种不同的进出风方式进行空气强制冷却电池组,分析了进出风口有倾角与无倾角的不同温度控制效果,结果表明带有倾角的进出风方式有利于降低电池组最高温度。采用电池组壳体侧面开孔方式进行电池组热管理,可有效改善电池组放电过程的温度分布均匀性。