新型AB5储氢合金表面修饰方法及机理研究

探索了一种储氢合金表面修饰的新方法. 在HF和CuSO₄的混合溶液中对MH/Ni电池负极材料AB₅型储氢合金进行表面处理, 研究了HF含量对反应的影响；考察了铜颗粒沉积量对表面修饰的影响；测试了修饰后合金电极的电化学性能；应用交流阻抗分析了表面修饰对合金性能影响的作用机理. 电化学测试结果表明, 表面修饰后合金电极具有更好的高倍率放电能力和循环稳定性. EIS分析结果表明, 表面修饰使合金的活性增强, 导电性提高, 欧姆阻抗及电化学阻抗显著降低. 因此, 这种新型表面修饰方法可以有效地改善合金的电化学性能, 使之更好地满足电动车用动力型电源的要求.     

卷绕式铅酸蓄电池板栅材料的研究

0引言制作高功率的卷绕式铅酸蓄电池,目前日益受到广泛关注。薄型极板是卷绕式铅酸蓄电池的显著特点之一。很薄的极板决定着卷绕式铅酸电池的优良性能。制造薄极板的前提是要先制得薄板栅。卷绕式铅酸蓄电池的板栅一方面要起到传统板栅支撑活物质与作为导电电极的作用,另一方面要求这种合金制成板栅后可以卷绕,所以硬度与脆性不能太大。此板栅一般要加工成厚度为0.2￣0.5mm的铅箔。而有报道制得更薄的板栅,厚度达到0.05￣0.08mm,可以说做到了薄如纸[1]。制作这样薄的板栅一般采用压延的方式,首先的问题就是选择何种合金材料,然后是其电化学…     

Understanding the effects of diffusion coefficient and exchange current density on the electrochemical model of lithium-ion batteries

The diffusion coefficient and exchange current density are the two dominant parameters that determine the electrochemical characteristics of the electrochemical battery model. Nevertheless, both parameter values are generally adopted from well-known literature or experimental data measured under limited conditions and are sometimes overfitted to match actual electrochemical behaviors without full consideration. Herein, the diffusion coefficients and exchange current densities of a LiNi_0·4Mn_0·3Co_0·3O₂/Li cell are measured and applied to the electrochemical model (based on Newman's model) using four different electrochemical methods: galvanostatic intermittent titration technique (GITT), potentiostatic intermittent titration technique (PITT), electrochemical impedance spectroscopy (EIS), and cyclic voltammetry (CV). Without any fitting, the model adopting the diffusion coefficient and exchange current density measured from PITT and EIS, respectively, simulates the actual voltage–capacity profiles well. Thus, this case study provides a valuable opportunity to understand the advantages and disadvantages of each measurement method in obtaining key experimental parameters for electrochemical battery models.     

锂离子电池的电化学阻抗谱分析

电化学阻抗谱(EIS)是研究电极/电解质界面发生的电化学过程的最有力工具之一,广泛应用于研究锂离子在锂离子电池嵌合物电极活性材料中的嵌入和脱出过程。本文从分析嵌合物电极的EIS谱特征入手,探讨了电化学阻抗谱中各时间常数的归属问题,重点讨论了与锂离子嵌脱过程相关的动力学参数,如电荷传递电阻、活性材料的电子电阻、扩散以及锂离子扩散迁移通过固体电解质相界面膜(SEI膜)的电阻等,对电极极化电位和温度的依赖关系。     

Technology of electrochemical impedance spectroscopy for an energy-sustainable society

Electrochemical impedance spectroscopy has been widely used to understand the chemistry and physics of battery systems. This review covers electrochemical impedance spectroscopy used for the interpretation of impedance data of lithium-ion batteries (LIBs) from advanced equivalent circuit models to the mathematical model, which is developed by John Newman. In addition, as a method to realize an energy-sustainable society using diagnostics based on the combination of LIBs and electrochemical impedance spectroscopy, on-board diagnostics of battery packs are achieved based on an input signal generated by a power controller in a battery management system instead of the conventionally used frequency response analyzer. The diagnostic system is applicable to energy management systems which are installed in homes, buildings, and communities, accumulating the impedance data on state of health of LIBs. Finally, a future possibility regarding the diagnostics of battery packs coupled with the machine learning of impedance data is introduced.     

KSCN对钒电池正极反应动力学及电池性能的影响

应用循环伏安、交流阻抗(EIS)等方法,研究了硫氰酸钾(KSCN)添加剂对石墨电极上(正极)钒电池电对(VO2+/VO2+)动力学特征及电池性能的影响.结果表明:1)KSCN的添加提高了VO2+/VO2+电对氧化峰的峰电流,但对还原峰的影响很小;2)添加KSCN,增加了充放电电量,提高了钒电池中活性物质的利用效率;3)VO2+/VO2+电对的速率常数K0,随着KSCN浓度的增加而逐渐增大.     

Impedance simulation of a solid oxide fuel cell anode in time domain

The purpose of the current study is to simulate the behavior of a solid oxide fuel cell (SOFC) anode under sinusoidal excitation. The obtained harmonic response is used as a base for electrochemical impedance spectra simulation. The electrochemical impedance spectroscopy (EIS) is a powerful non-destructive tool for SOFC researches. In order to evaluate the EIS experimental results, efforts are devoted to develop EIS numerical simulation tools. In this study, a planar SOFC is modeled, and the steady state behavior and frequency response, as well as the electrochemical spectra of the anode, are obtained. The developed model couples the electrochemical kinetics with mass transport. The Butler–Volmer equation is used for the anode electrochemistry, and the species equations are used for gas transport in the anode channel. In order to solve the system of the nonlinear equations, an in-house code based on finite difference method is developed and utilized. A parametric study is also carried out, and the results are discussed. The simulation results are in good agreement with published data. Results show a capacitive semicircle in the Nyquist plot, which is identical to the gas diffusion impedance as reported in literatures.     

电化学阻抗谱弛豫时间分布基础

电化学阻抗谱（EIS）是一种高效的原位/非原位电化学表征技术,已在电化学能源领域得到广泛应用,如用于锂离子电池、超级电容器、燃料电池等材料及器件性能的诊断和优化. 弛豫时间分布（DRT）是一种不依赖于研究对象先验知识的EIS解析技术,可用于分离和解析EIS中高度重叠的物理化学过程. 为了促进DRT解析技术的应用和推广,本文详细阐述了如下问题： 1） DRT解析原理、实现算法及重要扩展; 2） 典型电路基元的DRT解析分析; 3） DRT的具体实现及在电化学能源中的典型应用举例; 4）DRT解析技术研究进展、存在问题及发展趋势.     

Use of EIS for the evaluation of the protective properties of coatings for metallic cultural heritage: a review

The best way to reduce the degradation of metallic cultural heritage is through preventive conservation measures but, in many cases, it is not possible to obtain adequate environmental conditions, and it is necessary to apply coatings to the artefacts in order to protect them against corrosion. There is a continuous search in the metal conservation community for new and improved coatings that provide a better protection to the objects whilst respecting the special requirements of the conservation–restoration ethics. Whilst electrochemical techniques have a long tradition in conservation–restoration treatments for metallic cultural heritage, the evaluation of protective coatings using electrochemical impedance spectroscopy (EIS) has only been used very recently. EIS is a very well-established method to investigate metal coatings for general purposes and has many advantages that make it especially suitable for testing coatings for metallic works of art. This paper makes a review of the use of EIS for testing coatings for metallic cultural heritage from the first publications in the mid-1990s to the last papers. The experimental setup used, the types of coatings and metals investigated and the interpretation of the results are reviewed and compared with the use of EIS for testing general purpose anti-corrosive coatings.     

Analysis of large experimental datasets in electrochemical impedance spectroscopy

An approach for the analysis of large experimental datasets in electrochemical impedance spectroscopy (EIS) has been developed. The approach uses the idea of successive Bayesian estimation and splits the multidimensional EIS datasets into parts with reduced dimensionality. Afterwards, estimation of the parameters of the EIS-models is performed successively, from one part to another, using complex nonlinear least squares (CNLS) method. The results obtained on the previous step are used as a priori values (in the Bayesian form) for the analysis of the next part. To provide high stability of the sequential CNLS minimisation procedure, a new hybrid algorithm has been developed. This algorithm fits the datasets of reduced dimensionality to the selected EIS models, provides high stability of the fitting and allows semi-automatic data analysis on a reasonable timescale. The hybrid algorithm consists of two stages in which different zero-order optimisation strategies are used, reducing both the computational time and the probability to overlook the global optimum. The performance of the developed approach has been evaluated using (i) simulated large EIS dataset which represents a possible output of a scanning electrochemical impedance microscopy experiments, and (ii) experimental dataset, where EIS spectra were acquired as a function of the electrode potential and time. The developed data analysis strategy showed promise and can be further extended to other electroanalytical EIS applications which require multidimensional data analysis.     

硫酸溶液中的铋对铅酸蓄电池负极性能的影响

电解液;硫酸溶液中的铋对铅酸蓄电池负极性能的影响     

环氧树脂涂覆LY12铝合金在NaCl溶液中的阻抗模型

分别研究了裸LY12铝合金及涂覆环氧树脂涂层后合金在3.5％NaCl溶液中的电化学阻抗谱（EIS）.结果表明,LY12铝合金在点蚀电位以下阻抗谱上出现两个容抗弧,高频段对应Cl－参与的成膜阻抗,低频段对应铝阳极溶解的电化学反应阻抗.合金发生点蚀后出现低频感抗弧.合金/电极在NaCl溶液中先发生涂层吸水,当水及O2抵达基体后建立起电化学反应界面,合金遭受腐蚀；受涂层阻挡的影响,腐蚀产物的扩散逐渐成为控制步骤；当扩散速度较慢的Cl－抵达涂层/金属界面后,与界面处聚集的腐蚀产物间发生化学反应,完成成膜过程,阻抗谱上出现盐膜的阻抗,而扩散阻抗消失.提出了不同浸泡失效阶段涂层电极体系的阻抗模型.     

新型锂盐LiBC2O4F2在EC＋DMC溶剂中的电化学行为

采用差热-热重(TG-DTA)、恒电流充放电和交流阻抗(EIS)分析了二氟草酸硼酸锂(LiODFB)的热稳定性,研究了LiODFB/碳酸乙烯酯(EC)+碳酸二甲酯(DMC)电解液的电化学性能及界而特征.实验结果表明,LiODFB不仅具有更高的热稳定性,而且在EC+DMC溶剂中具有较好的电化学性能.与使用LiPF6/EC+DMC的电解液相比,锂离子电池应用LiODFB基电解液在55℃的高温具有更好的容量保持能力;以0.5C、1C(1C=250 mA·g-1)倍率循环放电,两种电池间的倍率性能差别较小;LiODFB能够在1.5 V(vs Li/Li+)左右在石墨电极表面还原形成一个优异稳定的保护性固体电解质相界面膜(SEI膜);交流阻抗表明,使用LiODFB基电解液的锂离子电池仅具有稍微增加的界面阻抗.因此LiODFB是一种非常有希望替代LiPF6用作锂离子电池的新盐.     

新型锂盐LiBC2O4F2在EC+DMC溶剂中的电化学行为

采用差热-热重(TG-DTA)、恒电流充放电和交流阻抗(EIS)分析了二氟草酸硼酸锂(LiODFB)的热稳定性, 研究了LiODFB/碳酸乙烯酯(EC)+碳酸二甲酯(DMC)电解液的电化学性能及界面特征. 实验结果表明, LiODFB不仅具有更高的热稳定性, 而且在EC+DMC溶剂中具有较好的电化学性能. 与使用LiPF6/EC+DMC的电解液相比, 锂离子电池应用LiODFB基电解液在55 ℃的高温具有更好的容量保持能力; 以0.5C、1C(1C=250 mA·g-1)倍率循环放电, 两种电池间的倍率性能差别较小; LiODFB能够在1.5 V(vs Li/Li+)左右在石墨电极表面还原形成一个优异稳定的保护性固体电解质相界面膜(SEI膜); 交流阻抗表明, 使用LiODFB基电解液的锂离子电池仅具有稍微增加的界面阻抗. 因此LiODFB是一种非常有希望替代LiPF6用作锂离子电池的新盐.     

二氟草酸硼酸钠作为电解液添加剂对石墨负极性能的影响

锂离子电池日益广泛的应用对其性能提出越来越高的要求,而在电解液中加入适当的添加剂能够显著提升电极材料的电化学性能. 本文首次在1 mol·L^-1 LiPF₆/EC + DMC + EMC（体积比1:1:1）的电解液中添加一定量的二氟草酸硼酸钠(NaDFOB),并通过循环伏安（CV）、电化学阻抗图谱（EIS）和扫描电子显微镜（SEM）等分析考察了其对石墨负极材料性能的具体影响. 结果显示,添加NaDFOB的电解液显著提高了石墨材料在常温下的可逆充放电容量和循环性能,同时明显改善了石墨材料的高温循环性能. 其机理在于NaDFOB的阴阳离子同时参与了石墨表面固体电解质界面膜（SEI）的形成,形成高稳定性的电解液/电极界面.     

Understanding Complex Electrochemical Impedance Spectroscopy in Corrosion Systems Using in‐situ Synchrotron Radiation Grazing Incidence X‐ray Diffraction

The difficulty in interpreting electrochemical impedance spectroscopy (EIS) data has limited the potential of the method despite its utility as an electrochemical method for studies of electrode reactions and interfacial structures. Taking the test case of the carbon dioxide corrosion of carbon steel, in‐situ synchrotron radiation grazing incidence X‐ray diffraction (SR‐GIXRD) has been demonstrated to be a powerful technique for validating and understanding the interfacial structures associated with complex EIS data. Carbon dioxide corrosion was found to occur in several steps, which may only be surmised by EIS, but the use of SR‐GIXRD in conjunction with EIS has enabled the establishment of a link between EIS time constants and structural changes associated with the evolution of corrosion products with time. By comparison to previous studies by the authors and others in this field, this communication provides the first direct experimental evidence linking SR‐GIXRD surface compositional data to otherwise indistinctive EIS time constants.     

全钒氧化还原液流电池用石墨毡电极的分步氧化活化

石墨毡电极是组成钒电池的关键材料,其较低的电化学活性是造成钒电池功率密度较低的关键因素之一. 本论文采用一种简便的石墨毡电极分步氧化活化法,先将石墨毡在高锰酸钾溶液中进行氧化,后置于活化溶液中激发其反应活性. 通过对处理后的石墨毡进行循环伏安、交流阻抗测试、XPS以及SEM表征,发现氧化时间和活化溶液组成是影响电极性能的因素,在本文中,先经过3天氧化时间,后在配比为3:1的活化溶液中处理的电极,较其他方法处理的电极,电荷传递电阻明显降低,其与溶液之间的接触电阻最低,为7.33 Ω·cm ²,氧化还原峰值比更接近于1,有效提高了反应的活性与可逆性,经X射线光电子能谱分析发现性能提高的原因与表面含氧官能团数目增加有关. 单电池性能测试结果进一步证实,利用该方法处理的石墨毡为电极的单电池,较未经处理的电池相比性能更优,有更高的放电容量和能量效率,在100 mA·cm ^-2电流密度下,能量效率较未处理电极高出7.47%. 与热处理法、酸处理法及电化学氧化法相比较,该方法不需要辅助设备,不消耗能源.     

有机涂层失效过程的电化学阻抗和电位分布响应特征

结合使用电化学阻抗谱(EIS)和扫描Kelvin探针(SKP)技术研究了在质量分数为3.5%的NaCl溶液中的铁基有机涂层劣化过程特征. 结果表明, 根据EIS和SKP的响应特征, 可将涂层劣化过程分为3个主要阶段: (Ⅰ) 涂层渗水阶段. 此时, 涂层渗水阶段的EIS阻抗持续减小, 但保持单容抗弧特征, SKP特征是电位持续降低, 但分布保持均匀; (Ⅱ) 基底金属腐蚀发生阶段. 此时, EIS阻抗快速下降, 并产生第二时间常数; SKP特征为表面电位差增大; (Ⅲ) 基底金属腐蚀发展与涂层失效阶段. 此时, EIS出现扩散尾, SKP电位差保持较大数值. 实验结果表明, 在研究有机涂层劣化过程中, EIS和SKP的结合使用能够互相补充完善, 获得涂层劣化过程中更为准确\, 可靠的变化信息.     

LiV3O8在Li2SO4水溶液中的电化学性能

采用低温固相法合成了具有纳米结构的LiV₃O₈材料.扫描电子显微镜（SEM）及透射电子显微镜（TEM）测试显示该材料具有纳米结构.X射线衍射（XRD）表明该材料属于单斜晶系,P2₁Im空间群.并采用循环伏安法（CV）及电化学阻抗谱图测试对该材料在1、2 mol·L^-1Li₂SO₄水溶液及饱和Li₂SO₄水溶液中的电化学行为进行了研究.结果表明,LiV₃O₈在饱和Li₂SO₄水溶液中具有最好的电化学性能.以LiV₃O₈作为负极材料,LiNi_1/3Co_1/3Mn_1/3O₂作为正极材料,饱和Li₂SO₄水溶液作为电解液组成了水性锂离子电池,进行恒流充放电测试,结果表明,在0.5C(1C=300 mA·g^-1)的充放电倍率下,该水性锂离子电池的首次放电比容量为95.2 mAh·g^-1,循环100次后仍具有37.0 mAh·g^-1的放电比容量.     

纯铝在KOH-乙醇溶液中的电化学行为

研究纯铝在KOH 乙醇溶液中的电化学行为,腐蚀失重、极化曲线、EIS和恒电流放电实验表明,该体系纯铝的腐蚀速率极小,因而有可能应用于密闭电池,并可在相当宽的电位范围内保持一定的活性.放电的终止可能是由于放电产物在电极表面堆积引起的.