锂离子电池健康状态估算方法研究进展

随着锂离子电池(Lithium-ion batteries,LIB)在电动汽车、储能电站和备用电源等领域的广泛应用,准确、及时地估计电池健康状态(State of health, SOH)是确保电池系统运行可靠性和安全性的关键因素。锂离子电池内部复杂的电化学反应和多变的外部使用条件,使得实现精准的健康状态估计具有挑战。随着人工智能、大数据分析等技术的快速发展,电池SOH评估的方法也逐渐多样化。首先介绍电池的老化机理和SOH概念,随后介绍了实验法、基于模型、数据驱动和融合方法,详细分析了每种方法的特点,并比较了在实际应用中相应的优势和局限性。最后,对SOH估算的未来趋势进行了展望。     

有机溶剂浸泡法回收再利用锂离子电池钛酸锂负极材料

利用有机溶剂法回收了废旧锂离子电池中的钛酸锂负极材料,并对回收的钛酸锂材料的结构、形貌和电化学性能进行了测试。XRD结果表明,材料除炭后添加适量锂源进一步合成得到的产物具有尖晶石结构,且不含其他的杂质。SEM图像显示,其颗粒分布均匀、无团聚现象。EIS结果表明,最终回收的钛酸锂电极材料比未添加锂源进行煅烧处理的材料具有较小的电荷转移阻抗和较高的锂离子扩散系数。在0.1 C倍率下,经过100次循环后其容量保持率为92.4%,具有优异的循环稳定性和可逆性,可以实现循环利用。     

锂离子电池健康状态预测研究现状

对目前主要的锂离子电池健康状态（SOH）预测方法进行分类和评价,包括基于模型法、数据驱动法、混合法和其他方法四个大类。分析了每种方法的特点及其在应用中的优势和不足,并结合实际应用,对不同方法的适应性进行评价并探讨其未来发展方向。     

薄膜锂离子电池负极材料的研究进展

全固态薄膜锂离子电池是锂离子电池的最新研究领域,其能量密度高、厚度薄、循环寿命长、可靠度高。薄膜化的负极材料是锂离子电池的重要组成部分,负极薄膜材料制备方法的研究取得了较大的进展,未来研究重点是低成本、低能耗、高综合电化学性能的负极薄膜材料以及可批量生产的薄膜制备技术。对薄膜化的硅负极材料、金属或合金薄膜材料、氧化物薄膜材料和复合薄膜材料近几年来的研究状况进行了综述,并对其发展前景进行了展望。     

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...     

基于温度变化率曲线的锂离子电池健康状态评估算法

锂离子电池技术的日益成熟为新能源发电和电动汽车等产业发展提供了重要支撑作用。锂离子电池采用有机电解液,发生故障后极易触发电池材料的放热副反应,导致电池热失控,最终可能演化成燃烧爆炸等重大事故。电池健康状态(State of health,SOH)是锂离子电池储能系统故障诊断和安全预警的重要参数,精确估计SOH是提升电池系统安全性的有效方法。提出一种基于温度变化率(DT)曲线的锂离子电池健康状态评估算法,充分提取反映电池健康状态的锂离子电池表面温度信息,以电池充电过程中的DT曲线的极大值点和两极值间的电压差作为电池SOH估计的特征量,进而搭建了基于反向传播(Back propagation,BP)神经网络的SOH估计模型。结合试验数据和仿真,测试结果最终表明,所提出的方法可有效提升锂离子电池SOH的估计精度。     

钛铌氧化物用于锂离子电池负极的研究进展

钛铌氧化物(TNO)负极材料因其具有较高的比容量、安全的嵌锂电位、快速嵌锂通道和稳定的嵌锂结构已成为当前高功率、长寿命锂离子动力电池负极首选材料之一.然而,其较低的电子电导率限制了TNO负极材料高倍率性能的发挥.本文通过对近期相关研究的探讨,综述了TNO的结构特点、制备方法及改性策略,着重讨论了几种不同Ti/Nb比例材料的晶体结构及其氧化还原与插层赝电容的协同嵌锂机制,阐明其快速导锂机理;同时介绍了固相反应法、溶胶凝胶法、静电纺丝法、模板法和溶剂热法等几种TNO材料先进制备工艺及各自优势;重点分析了元素掺杂、缺陷设计以及与导电材料复合等改性方案对TNO电子传导特性的影响和对电化学性能的改善效果.最后,本文还对TNO作为负极材料在锂离子全电池和混合锂离子电容器两种储能体系中的研究现状、存在问题及应用前景进行了分析和阐述.综合分析表明,在TNO的改性方案中,元素掺杂和缺陷设计可以改变TNO的电子结构,导电材料复合结构设计可为其构建多维电子通路,而多种改性方案的迭代可明显提高TNO材料的倍率性能和循环稳定性,有望使其在高功率储能器件中获得良好应用.     

基于卷积Fastformer的锂离子电池健康状态估计

锂离子电池的健康状态（state of health,SOH）是电池管理系统的重要功能,对于电池的可靠运行和使用寿命具有重要意义。为了进一步提高数据驱动方法对锂离子电池SOH估计的精度,提出一种卷积Fastformer模型的SOH估计方法。首先,提取锂离子电池多个充电阶段的每次循环电压曲线、电流曲线,每个阶段各个曲线转换为统计健康特征来表征锂离子电池老化特性,并使用Pearson相关系数对所选统计特征进行了相关性分析,筛选出与容量相关性高的健康特征,消除特征冗余性。随后,融合卷积神经网络和具有线性复杂度的Fastformer神经网络的特点,使用卷积神经网络强大的特征提取能力挖掘健康特征的局部信息,利用Fastformer的多头附加注意力机制可以更高效地在复杂的长序列中总结全文信息。然后,为减少模型训练时间,利用正交实验法对模型超参数进行优化。最后,采用公开数据集将所提方法与CNN、GRU、RNN模型进行对比,验证卷积Fastformer模型的准确性,结果表明,平均绝对误差、均方根误差最大仅为0.25%,0.29%,相对误差在0.8%以内,具有较高的估计精度和稳定性。     

基于TWP-SVR的锂离子电池健康状态估计

健康状态(state of health,SOH)是评估锂离子电池老化程度和剩余使用寿命的重要指标。然而,SOH无法通过直接测量获得,本工作提出了一种基于时间规整图(time warp profile,TWP)提取间接健康特征参数,使用支持向量机回归(vector machine regression,SVR)模型估计SOH的方法。首先,通过TWP将锂离子电池不同循环充放电压曲线转换为相位差异曲线。然后,从相位差异曲线中提取出4个间接健康特征。接着,采用线性核函数的SVR模型估计SOH。最后,以美国航空航天局(National Aeronautics and Space Administration,NASA)、美国保险商实验室公司和普渡大学(Underwriters Laboratories Inc.-Purdue University,UL-PUR)的开源数据集和储能电站实测数据进行验证。其中,储能电站数据实验结果表明,TWP-SVR模型的均方根误差(root mean square error,RMSE)、平均绝对误差(mean absolute error,MAE)的样本标准差...     

Facile controlled synthesis of hierarchically structured mesoporous Li4Ti5O12/C/rGO composites as high-performance anode of lithium-ion batteries

In this paper, a facile strategy is proposed to controllably synthesize mesoporous Li₄Ti₅O₁₂/C nanocomposite embedded in graphene matrix as lithium-ion battery anode via the co-assembly of Li₄Ti₅O₁₂ (LTO) precursor, GO, and phenolic resin. The obtained composites, which consists of a LTO core, a phenolic-resin-based carbon shell, and a porous frame constructed by rGO, can be denoted as LTO/C/rGO and presents a hierarchical structure. Owing to the advantages of the hierarchical structure, including a high surface area and a high electric conductivity, the mesoporous LTO/C/rGO composite exhibits a greatly improved rate capability as the anode material in contrast to the conventional LTO electrode.     

Rb掺杂Li4Ti5O12作为锂离子电池负极材料的合成及电化学性能

合成了不同Rb掺杂量的钛酸锂（Li_4-xRb_xTi₅O₁₂; x = 0.010, 0.015, 0.020）作为锂离子电池的负极材料。测试结果显示,Rb离子掺杂有效增强了钛酸锂的电子电导率。相同的测试条件下,相比于未掺杂样品和高Rb含量掺杂样品（x = 0.015, 0.020）,适量的Rb掺杂钛酸锂（Li_3.99Rb_0.01Ti₅O₁₂; x = 0.010）表现出最优的电化学性能。Li_3.99Rb_0.01Ti₅O₁₂材料表现出161.2 mA∙h/g的初始容量,且在1 C下经过1000次循环后容量保持率可达90.9%。此外,全电池Li_3.99Rb_0.01Ti₅O₁₂ // LiFePO₄在0.5 C条件下首次放电容量为144 mA∙h/g,经过150次循环后,容量保持率为78.8%。     

Preparation and rate capability of Li4Ti5O12 hollow-sphere anode material

Spinel lithium titanate, Li₄Ti₅O₁₂, with novel hollow-sphere structure was fabricated by a sol–gel process using carbon sphere as template. The effect of the hollow-sphere structure as well as the wall thickness on the Li storage capability and high rate performance was electrochemically evaluated. High specific capacity, especially better high rate performance was achieved with this Li₄Ti₅O₁₂ hollow-sphere electrode material with thin wall thickness. It is believed that this macroporous hollow-sphere structure has shortened the Li diffusion distance, increased the contact area between Li₄Ti₅O₁₂ and electrolyte, and also led to better mixing of the active material with AB. All these factors have resulted in the good rate capability of the hollow-sphere structured Li₄Ti₅O₁₂ electrode material.     

High-strength all-solid lithium ion electrodes based on Li4Ti5O12

A Li₄Ti₅O₁₂-Li_0.29La_0.57TiO₃-Ag electrode composite was fabricated via sintering the corresponding powder mixture. The process achieved a final relative density of 97% the theoretical. Relatively thick, ∼100 μm, electrodes were fabricated to enhance the energy density relatively to the traditional solid-state thin film battery electrodes. The sintered electrode composite delivered full capacity in the first discharge at C/40 discharge rate. Full capacity utilization resulted from the 3D percolated network of both solid electrolyte and metal, which provide paths for ionic and electronic transport, respectively. The electrodes retained 85% of the theoretical capacity after 10 cycles at C/40 discharge rate. The tensile strength and the Young's modulus of the sintered electrode composite are the highest reported values to date, and are at least an order of magnitude higher than the corresponding value of traditional tapecast “composite electrodes”. The results demonstrate the concept of utilizing thick all-solid electrodes for high-strength batteries, which might be used as multifunctional structural and energy storage materials.     

Lithium diffusion in Li4Ti5O12 at high temperatures

Synthesis of the spinel lithium titanate Li₄Ti₅O₁₂ by an alkoxide-free sol-gel method is described. This method yields highly pure and crystalline Li₄Ti₅O₁₂ samples at relatively low temperature (850 °C) and via short thermal treatment (2 h). ⁶Li magic angle spinning nuclear magnetic resonance (MAS NMR) measurements on these samples were carried out at high magnetic field (21.1 T) and over a wide temperature range (295-680 K). The temperature dependence of the chemical shifts and integral intensities of the three ⁶Li resonances demonstrates the migration of lithium ions from the tetrahedral 8a to the octahedral 16c sites and the progressive phase transition from a spinel to a defective NaCl-type structure. This defective structure has an increased number of vacancies at the 8a site, which facilitate lithium diffusion through 16c → 8a → 16c pathways, hence providing an explanation for the reported increase in conductivity at high temperatures. Molecular dynamics simulations of the spinel oxides Li_4+xTi₅O₁₂, with 0 ≤ x ≤ 3, were also performed with a potential shell model in the temperature range 300-700 K. The simulations support the conclusions drawn from the NMR measurements and show a significant timescale separation between lithium diffusion through 8a and 16c sites and that out of the 16d sites.     

Nano Li4Ti5O12–LiMn2O4 batteries with high power capability and improved cycle-life

We report the effects of electrode thickness, cathode particle size and morphology, cathode carbon coating matching ratio and laminate structure on the electrochemical characteristics of nanosized Li₄Ti₅O₁₂–LiMn₂O₄ batteries. We show that a correct adjustment of these parameters resulted in significant improvements in power capability and cycle-life of such devices, making them competitive, low-cost and safe battery chemistry for next generation Li-ion batteries. In addition, Li₄Ti₅O₁₂ reversible specific capacity beyond three Li-ions intercalation is reported.     

Electrical conductivity and charge compensation in Ta doped Li4Ti5O12

Ta doping in Li₄Ti₅O₁₂ (Li₄Ti_4.95Ta_0.05O₁₂) as function of different heat-treat atmospheres (oxidizing/reducing) was investigated and compared to Li₄Ti₅O₁₂ to determine its effect on ionic/electronic conductivity and the charge compensating defects. Under oxidizing conditions Li₄Ti_4.95Ta_0.05O₁₂ was primarily an ionic conductor where the extra charge of Ta was compensated by Ti vacancies. Under reducing conditions Li₄Ti_4.95Ta_0.05O₁₂ was primarily an electronic conductor where the extra charge of Ta was compensated by an electron. The charge compensating defects were confirmed by sintering data.     

Electrochemical behaviors of wax-coated Li powder/Li4Ti5O12 cells

The wax-coated Li powder specimen was effectively synthesized using the drop emulsion technique (DET). The wax layer on the powder was verified by SEM, Focused Ion Beam (FIB), EDX and XPS. The porosity of a sintered wax-coated Li electrode was measured by linear sweep voltammetry (LSV) and compared with that of a bare, i.e., un-coated Li electrode. The electrochemical behavior of the wax-coated Li powder anode cell was examined by the impedance analysis and cyclic testing methods. The cyclic behavior of the wax-coated Li powder anode with the Li₄Ti₅O₁₂ (LTO) cathode cell was examined at a constant current density of 0.35 mA cm⁻² with the cut-off voltages of 1.2–2.0 V at 25 °C. Over 90% of the initial capacity of the cell remained even after the 300th cycle. The wax-coated Li powder was confirmed to be a stable anode material.     

Effects of dopant on the electrochemical performance of Li4Ti5O12 as electrode material for lithium ion batteries

The effects of dopant on the electrochemical properties of spinel-type Li_3.95M_0.15Ti_4.9O₁₂ (M = Al, Ga, Co) and Li_3.9Mg_0.1Al_0.15Ti_4.85O₁₂ were systematically investigated. Charge–discharge cycling were performed at a constant current density of 0.15 mA cm⁻² between the cut-off voltages of 2.3 and 0.5 V, the experimental results showed that Al³⁺ dopant greatly improved the reversible capacity and cycling stability over the pristine Li₄Ti₅O₁₂. The substitution of the Ga³⁺ slightly increased the capacity of the Li₄Ti₅O₁₂, but did not essentially alleviate the degradation of cycling stability. Dopants such as Co³⁺ and Mg²⁺ to some extent worsened the electrochemical performance of the Li₄Ti₅O₁₂.