Effect of safety valve types on the gas venting behavior and thermal runaway hazard severity of large-format prismatic lithium iron phosphate batteries

The safety valve is an important component to ensure the safe operation of lithium-ion batteries(LIBs).However,the effect of safety valve type on the thermal runaway(TR)and gas venting behavior of LIBs,as well as the TR hazard severity of LIBs,are not known.In this paper,the TR and gas venting behavior of three 100 A h lithium iron phosphate(LFP)batteries with different safety valves are investigated under overheating.Compared to previous studies,the main contribution of this work is in studying and evaluating the effect of gas venting behavior and TR hazard severity of LFP batteries with three safety valve types.Two significant results are obtained:(Ⅰ)the safety valve type dominates over gas venting pressure of battery during safety venting,the maximum gas venting pressure of LFP batteries with a round safety valve is 3320 Pa,which is one order of magnitude higher than other batteries with oval or cavity safety valve;(Ⅱ)the LFP battery with oval safety valve has the lowest TR hazard as shown by the TR hazard assessment model based on gray-fuzzy analytic hierarchy process.This study reveals the effect of safety valve type on TR and gas venting,providing a clear direction for the safety valve design.

Process for recycle of spent lithium iron phosphate battery via a selective leaching-precipitation method

Applying spent lithium iron phosphate battery as raw material,valuable metals in spent lithium ion battery were effectively recovered through separation of active material,selective leaching,and stepwise chemical precipitation.Using stoichiometric Na2S2O8 as an oxidant and adding low-concentration H2SO4 as a leaching agent was proposed.This route was totally different from the conventional methods of dissolving all of the elements into solution by using excess mineral acid.When experiments were done under optimal conditions(Na2S2O8-to-Li molar ratio 0.45,0.30 mol/L H2SO4,60℃,1.5 h),leaching efficiencies of 97.53% for Li^+,1.39%for Fe^3+,and 2.58% for PO4^3−were recorded.FePO4 was then recovered by a precipitation method from the leachate while maintaining the pH at 2.0.The mother liquor was concentrated and maintained at a temperature of approximately 100℃,and then a saturated sodium carbonate solution was added to precipitate Li2CO3.The lithium recovery yield was close to 80%.

Hydrometallurgical recovery of lithium carbonate and iron phosphate from blended cathode materials of spent lithium-ion battery

The recycling of cathode materials from spent lithium-ion battery has attracted extensive attention,but few research have focused on spent blended cathode materials.In reality,the blended materials of lithium iron phosphate and ternary are widely used in electric vehicles,so it is critical to design an effective recycling technique.In this study,an efficient method for recovering Li and Fe from the blended cathode materials of spent LiFePO_(4)and LiNi_(x)Co_(y)Mn_(1-x-y)O_(2)batteries is proposed.First,87%A1 was removed by alkali leaching.Then,91.65%Li,72.08%Ni,64.6%Co and 71.66%Mn were further separated by selective leaching with H_(2)SO_(4)and H_(2)O_(2).Li,Ni,Co and Mn in solution were recovered in the form of Li_(2)CO_(3)and hydroxide respectively.Subsequently,98.38%Fe was leached from the residue by two stage process,and it is recovered as FePO_(4)·2H_(2)O with a purity of 99.5%by precipitation.Fe and P were present in FePO_(4)·2H_(2)O in amounts of 28.34%and 15.98%,respectively.Additionally,the drift and control of various components were discussed,and cost-benefit analysis was used to assess the feasibility of potential application.

Perspective on cycling stability of lithium-iron manganese phosphate for lithium-ion batteries

Lithium-iron manganese phosphates(LiFex Mn_(1-x)PO_(4),0.1<x<0.9)have the merits of high safety and high working voltage.However,they also face the challenges of insufficient conductivity and poor cycling stability.Some progress has been achieved to solve these problems.Herein,we firstly summarized the influence of different electrolyte systems on the electrochemical performance of LiFexMn_(1-x)PO_(4),and then discussed the effect of element doping,lastly studied the influences of conductive layer coating and morphology control on the cycling stability.Finally,the prospects and challenges of developing high-cycling LiFexMn_(1-x)PO_(4) were proposed.

Accurate Modeling of Prismatic Type High Current Lithium-Iron-Phosophate (LiFePO4) Battery for Automotive Applications

With accurate battery modeling, circuit designers and automotive control algorithms developers can predict and optimize the battery performance. In this paper, an experimental verification of an accurate model for prismatic high current lithium-iron-phosphate battery is presented. An automotive TSLFP160AHA lithium-iron-phosphate battery bank is tested. The different capacity GBDLFMP60AH battery bank is used to validate the model extracted from the former battery. Effect of current, stacking and SOC upon the battery parameters performance is investigated. Six empirical equations are obtained to extract the prismatic type LiFePO4 model as a function of SOC. Based on comparing the measured and simulated data, a well accuracy of less than 50mV maximum error voltage with 1.7% operating time error referred to the measured data is achieved. The model can be easily modified to simulate different batteries and can be extended for wide ranges of different currents.

Highly selective and green recovery of lithium ions from lithium iron phosphate powders with ozone

Since lithium iron phosphate cathode material does not contain high-value metals other than lithium,it is therefore necessary to strike a balance between recovery efficiency and economic benefits in the recycling of waste lithium iron phosphate cathode materials.Here,we describe a selective recovery process that can achieve economically efficient recovery and an acceptable lithium leaching yield.Adjusting the acid concentration and amount of oxidant enables selective recovery of lithium ions.Iron is retained in the leaching residue as iron phosphate,which is easy to recycle.The effects of factors such as acid concentration,acid dosage,amount of oxidant,and reaction temperature on the leaching of lithium and iron are comprehensively explored,and the mechanism of selective leaching is clarified.This process greatly reduces the cost of processing equipment and chemicals.This increases the potential industrial use of this process and enables the green and efficient recycling of waste lithium iron phosphate cathode materials in the future.

液氮抑制32650型磷酸铁锂电池组热失控传播特性试验研究

文章从磷酸铁锂电池组热失控危险特性出发,通过试验研究32650型磷酸铁锂电池单体热失控特征及其电池组间热失控传播过程。探究利用液氮喷淋阻断电池组间热失控传播,分析液氮对磷酸铁锂电池的防灭火效能。结果表明:单体锂电池热失控可划分为被动加热、安全阀泄压、自反应、喷射火、明火熄灭等5个阶段,单体电池温度变化曲线呈倒“V”形。液氮可有效阻断电池组间的热失控传播,能够大幅降低喷射火阶段的电池峰值温度。且喷淋时间越长,阻止电池组热失控传播越明显。30 s液氮喷淋条件下,除电池A1外,其他电池未进入安全阀泄压阶段。

失效锂萃取剂中Fe(Ⅲ)的回收及制备电池级磷酸铁的工艺研究

盐湖卤水萃取法提锂的工艺中,磷酸三丁酯-FeCl_(3)-煤油协萃体系在多次循环使用后萃取能力会下降甚至失效。将失效锂萃取剂中的Fe(Ⅲ)回收利用对盐湖提锂行业的持续发展具有重要意义。在高浓度盐酸体系中模拟失效锂萃取剂,以其中的Fe(Ⅲ)为铁源,NH_(4)H_(2)PO_(4)溶液为磷源,在非均相体系中制备电池级磷酸铁。研究了反应时间、氨水加入量、NH_(4)H_(2)PO_(4)溶液浓度、反应温度和搅拌速率对产品产率、粒径(D_(50))和铁磷物质的量比的影响。结果表明,在优化的工艺条件下,可制得高纯度的单斜晶系二水磷酸铁,产率为89.43%、铁磷物质的量比为0.98、D_(50)为1.81μm、比表面积为37.38 m^(2)/g、含水量为19.64%,符合电池级磷酸铁的行业标准。以自制的磷酸铁为前驱体制备的Li Fe PO_(4)/C性能良好,在0.1C倍率下的首次放电比容量为146.58 m A·h/g,首次充放电效率为94.90%,恒流充放电循环80圈后的容量保持率为91.72%。研究表明,采用NH_(4)H_(2)PO_(4)溶液反萃沉淀法可有效回收失效锂萃取剂中的Fe(Ⅲ)并制备出电池级磷酸铁。

基于铁锈红和废锂箔制备LiFePO_(4)/C正极材料的储锂性能

磷酸铁锂电池的需求大、市场垄断而导致原材料价格日益高涨。以铁锈红和废锂箔为原材料,采用磷酸铁工艺制备了LiFePO_(4)/C粉末,并测试其电化学储锂性能。结果表明:LiFePO_(4)/C粉末由粒径尺寸为110~400nm的颗粒组成,在1.0C循环350圈后的可逆比容量和容量保持率分别为129.7mAh/g和98.0%,与商业LiFePO_(4)正极材料性能相当。可见,该结果降低了LiFePO 4的制备成本,有利于循环经济和可持续发展。

基于电热耦合模型的宽温域锂离子电池SOC/SOP联合估计

准确的状态估计对于锂离子电池安全可靠运行具有重要意义,但由于非线性强,多参数耦合,实现宽温域多参数联合在线估计难度较大。考虑到温度影响,建立电热耦合模型,采用扩展卡尔曼滤波算法(EKF)在线辨识电池参数,通过电压及温度仿真验证了模型的准确性;然后针对无迹卡尔曼滤波算法(UKF)历史数据利用率低的问题,引入多新息理论(MI)改进UKF,改进后的算法在非电压平台区荷电状态(SOC)估计均方根误差不超过1.2%,相较于改进前误差降低了30%以上,并结合安时积分法设计切换算法,解决了MIUKF算法在磷酸铁锂电池电压平台区无法通过电压反馈修正SOC估计误差的问题,实现了宽温域复杂工况下全区间SOC的准确估计,在不同SOC初始值条件下验证了结合算法的准确性,均方根误差不超过3%,为峰值功率(SOP)估计提供了可靠的SOC值;最后将温度约束引入到SOP估计中,提出多约束条件下的SOP估计方法,结果表明在高温条件下,温度起到关键限制作用,可以防止电池温升过大,减少安全隐患。

退役磷酸铁锂电池的回收利用技术研究进展

随着新能源行业的快速发展,具有高安全性、低成本、循环寿命长等优点的磷酸铁锂电池逐步占据较大的市场份额。然而,如何在保障生态环保的前提下实现退役磷酸铁锂电池的资源化利用成为了重要的课题本文概述了退役磷酸铁锂电池的现状及回收政策,综述了退役磷酸铁锂电池的梯级利用及其正极材料回收技术研究现状,最后展望了退役磷酸铁锂电池未来的资源回收发展方向。

从废旧电池中回收二水磷酸铁再生LiFePO_(4)/C

使用酸浸—加热回流法从废旧磷酸铁锂电池中回收得到二水磷酸铁,将其作为原料并添加一定量的锂源和碳源,通过高温固相法再生了LiFePO_(4)/C,并研究了温度对再生LiFePO_(4)/C电化学性能的影响。首先采用酸浸—加热回流法对废旧磷酸铁锂正极片进行处理生成FePO_(4)·2H_(2)O,洗涤烘干后研磨得到FePO_(4)·2H_(2)O粉末,XRD表征和ICP测试结果显示回收得到的FePO_(4)·2H_(2)O结构完整、纯度较高。然后在FePO_(4)·2H_(2)O粉末中添加碳源,在高温下制备LiFePO_(4)/C材料,对其进行结构与形貌表征以及电化学测试,发现以葡萄糖为碳源、温度为700℃、葡萄糖量为理论生成磷酸铁锂质量的17%时再生的LiFePO_(4)/C电化学性能最佳,0.3 C倍率下再生的LiFePO_(4)/C首周放电比容量可达141.8 mAh/g,循环100周后容量保持率可维持在94.3%。通过与商用LiFePO_(4)/C进行电化学性能对比,进一步验证了该工艺再生的LiFePO_(4)/C有着优良的电化学性能。

退役磷酸铁锂电池负极石墨的预锂化再生

对退役磷酸铁锂(LiFePO_(4))电池的负极石墨进行预锂化,使石墨变为锂碳化合物并进行热处理,从而实现石墨的晶型转变.将预锂化后的LiFePO_(4)电池热处理,回收得到的石墨经不同处理,所得样品分别与导电炭黑和黏结剂等物质进行混合制成新的电极,组装成电池后进行电池的性能测试.结果表明,在电流为0.1C的条件下,预锂化热处理的石墨样品经酸浸后所制成的纽扣电池平均放电比容量为322.3 mAh·g^(-1),远远高于其他对比组,其循环稳定性也强于人造石墨.说明退役电池负极石墨通过预锂化、热处理和酸浸处理后能够得到优质再生石墨.

基于集成聚类的退役锂电池直接分组

针对退役电池筛选分组效率低的问题,提出了一种基于加权表决集成聚类算法的退役锂离子电池直接分组方法。提取充电电压片段特征,对特征进行降维,并使用集成聚类算法直接对特征进行分组,实现退役锂离子电池分组。该方法只需要得到部分恒流充电曲线便可实现退役锂离子电池的按容量分组,提高了筛选效率。搭建了磷酸铁锂电池仿真和实验平台,对所提的电池筛选、分组策略进行仿真和实验分析。从退役电池分组容量精度和分组效率的角度验证了所提策略的正确性和有效性。

优先提锂湿法工艺回收废旧磷酸铁锂电池

文章详细介绍了一种优先提锂湿法回收碳酸锂的工艺流程,先用碱除铝,再酸浸分离磷酸铁,除杂后沉锂,工艺流程简化、试剂消耗量小、锂浸出选择性较高,工艺经济效益相对更好,可以为磷酸铁锂电池回收企业提供一种工艺流程简化、试剂消耗量小、锂浸出选择性较高、工艺经济效益相对更好的工艺技术路线。

高温固相修复再生磷酸铁锂正极材料研究进展

磷酸铁锂电池作为广泛应用的锂离子电池之一,其关键电极材料的高效回收循环利用在资源、环境、经济等方面具有重要的战略意义。高温固相修复技术能够实现磷酸铁锂正极材料短流程、低成本、高效率、绿色环保的循环利用,获得了广泛的关注和研究。针对高温固相修复再生磷酸铁锂正极材料,介绍了此类材料的电化学性能失效机理,从锂补充、缺陷修复和强化锂的迁移等方面对磷酸铁锂正极材料的修复机理进行了分析;阐述了焙烧温度、保温时间、补锂量等修复再生工艺参数对高温固相法修复磷酸铁锂正极材料的影响;分析了表面包覆和离子掺杂对提升磷酸铁锂正极材料电化学性能的影响和机理;并对高温固相修复法修复磷酸铁锂正极材料的可控制备、杂质控制和材料改性等方面的未来前景进行了展望。

废旧磷酸铁锂电池机械化学固相氧化回收锂机理

采用K_(2)S_(2)O_(8)作为氧化剂,分别通过氧化浸出、机械活化联合氧化浸出、机械固相氧化联合水浸三种方法对废旧磷酸铁锂(LiFePO_(4))电池正极粉末进行处理。结果表明,在三种方式最优条件下,氧化浸出方式的Li浸出率为89.03%(质量分数)、机械活化联合氧化浸出方式的Li浸出率为92.36%(质量分数),机械固相氧化联合水浸方式的效果最佳,Li浸出率为98.26%(质量分数),此时Fe化合物与Li完全分离,选择性较高。通过添加K_(3)PO_(4)将浸出的锂离子以Li_(3)PO_(4)沉淀的形式提取回收,经电感耦合等离子体质谱仪检测,纯度可达98.67%(质量分数)。X射线衍射和X射线光电子能谱分析浸出机理,结果表明,在机械化学固相氧化过程中,机械力不仅诱导了LiFePO_(4)粒度的减小,还作为氧化反应的驱动力,使得Li^(+)迁出,Fe(Ⅱ)被氧化为Fe(Ⅲ),为之后的水浸过程提供了良好条件,实现了Li和Fe的选择性分离。

气凝胶灭火剂抑制锂离子储能电池热失控特性研究

通过对比试验探究了气凝胶灭火剂对锂离子储能电池热失控的抑制效果。研究满荷电状态下的100 Ah磷酸铁锂储能电池热失控演变过程特征参数,识别出3个灾害演变特征拐点作为灭火剂施加的指导节点。在相同节点分别施加灭火参数一致的气凝胶灭火剂与细水雾开展灭火对比测试。结果表明:触发明火前施加灭火剂均可有效阻断电池内部放热副反应,两者表现出相似的冷却效能;电池起火后,气凝胶灭火剂展现出更为出色的明火抑制效果,其接触电池表面形成的致密泡沫可有效阻隔氧气,实现快速灭火;对于已经触发热失控的情形,气凝胶灭火剂凭借预热覆盖效果,显著缩短电池射流火持续时间,可大幅降低电池火灾危害。

磷酸锰铁锂正极材料改性研究进展

正极材料是决定锂离子电池性能的关键材料之一,直接影响电池的能量密度、循环寿命、倍率性能及安全性能。橄榄石型LiMnFePO4具有能量密度高、成本低、环境友好、安全稳定等优点,被认为是一种很有前途的锂离子电池正极材料。然而,LiMnFePO4具有橄榄石结构磷酸盐基化合物电子电导率低、Li+一维扩散速率慢等固有缺陷,严重阻碍了其在高性能锂离子电池中的大规模应用。如何提升LiMnFePO4的导电子/离子性能,是当前需要解决的关键问题。本文全面综述了LiMnFePO4正极材料的结构特征、合成方法及其导电性能提升的研究进展,着重介绍了表面包覆、形貌控制和离子掺杂等方法对提升LiMnFePO4正极材料导电性能的效果及其作用机理,虽然上述三类改性方法均可一定程度地优化材料颗粒间电子/离子传输路径,实现LiMnFePO4正极材料导电性能的提升。但是单独采用这些方法依然难以从根本上解决LiMnFePO4导电性差的问题。为进一步提升LiMnFePO4正极材料的综合性能,本文在总结当前研究进展的基础上,对LiMnFePO4未来的研究思路和发展方向进行了展望。提出了通过杂原子掺杂优质碳材料包覆、短b轴形貌控制以及离子掺杂等方法联合改性的策略。该策略有望进一步提升LiMnFePO4正极材料的导电性能,获得高容量、高倍率、高稳定性的LiMnFePO4正极材料。

高性能磷酸铁锂电池补锂技术及机制

本工作采用正极磷酸铁锂(LiFePO_(4),LFP)搭配高容量石墨掺硅负极体系,以商业化富锂镍酸锂(Li_(2)NiO_(2),LNO)作为正极补锂添加剂,探究补锂技术对磷酸铁锂电池性能的影响及作用机制。通过对LNO的电化学性能、脱锂前后的结构组成与微观形貌变化进行测试与分析,发现LNO的不可逆容量可达212.1 mAh/g,而且脱锂后的LNO主要以仍具活性的Li_(0.63)Ni_(1.02)O_(2)形式存在。然后,将一定量的LNO添加至LFP正极浆料中制作成32 Ah软包电池,并进行容量、倍率、电化学阻抗和循环寿命等性能的测试与研究。结果表明:与基准组相比,添加质量分数3%的LNO补锂剂可以显著提升磷酸铁锂电池的性能,补锂组的能量密度和循环寿命分别提高4.9%和50%。此外,结合三电极测试方法,阐明了补锂技术对循环性能提升的作用机制。添加过量的正极补锂剂可促使部分活性锂预存于负极侧,在循环过程中进行缓慢释放,确保长期稳定的锂损失补偿,从而改善锂离子电池的循环寿命。该研究有助于推动正极补锂技术在储能电池中的应用,不仅为高性能磷酸铁锂电池的设计与开发提供理论和实验依据,也为硅基负极材料的商业化应用奠定基础。