凝胶型离子液体/聚合物电解质的电化学性能

以聚偏氟乙烯-六氟丙烯共聚物[P(VDF-HFP)]为基体,将3-乙基-1-甲基咪唑鎓四氟硼酸盐(EMIBF4)和3-丁基-1-甲基咪唑鎓六氟磷酸盐(BMIPF6)等室温离子液体作为离子源和增塑剂,制备了EMIBF4/P(VDF-HFP)和BMIPF6/P(VDF-HFP)凝胶型离子液体/聚合物电解质;通过核磁共振(1HNMR)谱和热失重方法(TG)分别对其结构和热稳定性进行了表征和热失重分析。由电化学性能测试考察了两类离子液体/P(VDF-HFP)聚合物电解质的分解电压、室温离子电导率及离子液体/P(VDF-HFP)的质量配比、温度等对电导率的影响。结果表明:所制备的离子液体/聚合物电解质在305℃时仍具有较好的热稳定性,其室温离子电导率均达10-3S/cm数量级以上,其中EMIBF4与P(VDF-HFP)的质量比为2∶1时室温电导率可达3.67mS/cm。     

离子液体在电池电解质中的应用现状

离子液体根据阳离子的结构特点，可分为咪唑类、吡咯类、季铵盐类和聚合物类等。离子液体具有很好的理化性质，在电池电解质中应用广泛。结合离子液体应用于金属空气电池电解质、超级电容器电解质、燃料电池电解质的研究实例和离子液体的理化性质，剖析将离子液体应用到各电池电解质中的优缺点，以改善和解决上述电池传统电解质存在的析氢腐蚀、副反应产物、室温下不稳定及环境污染等问题。对于离子液体的发展和改善，提出引入官能团和添加金属盐的设想。     

锂离子电池用离子液体电解质的研究

合成了1-甲基-3-乙基咪唑二(三氟甲基磺酰)亚胺(EMI-TFSI)和1-丁基-3-乙基咪唑二(三氟甲基磺酰)亚胺(BMI-TFSI)两种离子液体,并分别研究了它们的各种电化学性质。结果表明,两种离子液体的电化学窗口分别为4.8V和4.6V,离子液体电解质的室温电导率分别为5.4mS/cm和1.6mS/cm。使用LiCoO2和LiFePO4作为锂离子电池正极材料,分别以EMI-TFSI+1.0mol/LLiTFSI、BMI-TFSI+1.0mol/LLiTFSI为电解质组装半电池,测试其循环性能,结果表明:LiCoO2与两种离子液体电解质的相容性较差,而采用LiFePO4正极,以EMI-TFSI+1.0mol/LLiTFSI为电解质组装的半电池具有较高的比容量,经过20次循环(0.1C)几乎无衰减,比容量仍保持在120mAh/g以上,表现出较好的循环能力。     

原子吸收光谱仪在电池材料分析中的应用

介绍了原子吸收光谱仪在电池工业用金属、粉末、液体和化学试剂等材料的分析与测试中的应用,并提供了可靠的分析方法和测试条件。在电池工业材料分析与测试应用中,用原子吸收光谱仪进行材料的分析适用性强,可靠性高;在进行各类样品的分析中具有较好的灵敏度;杂质离子干扰较少、操作简便快速,以及选择性与重现性好等优点。也对各类材料分析与测试的预处理过程、干扰因素和消除方法进行了阐述。     

离子液体在锂离子电池中的应用

对应用于锂离子电池电解质的离子液体按照阳离子的类型进行分类,并介绍了它们的性质.综述了近年来离子液体作为电解质的应用方式,包括单一的离子液体、离子液体与传统有机电解质混合、离子液体聚合物和离子液体中引入功能基团.讨论了阴、阳离子结构对离子液体性质的影响,离子液体与电极的匹配性.     

超级电容器储能机制研究获重大进展

<正>基于多孔活性炭材料和离子液体电解质的双电层电容器(EDLC)具有快速充放电、良好循环稳定性和宽工作电压窗口等优点,是一种极具前景的电化学储能器件。研究EDLC在离子液体中的储能机理,尤其是表征离子液体阴阳离子各自本征结构对多孔活性炭电容特性的影响作用机制、从微观层面揭示储能机理,对恰当选择离子液体,、进而合理构筑高性能EDLC具有重要指导意义。     

离子液体在锂离子电池电解液中的研究进展

锂离子电池作为新能源具有较大的发展潜力,离子液体具有热稳定性好、安全性好、电导率高、电化学窗口宽、蒸汽压低等特点,作为新一代功能化电解质材料在锂离子电池中的应用成为当前研究的热点。对离子液体在电池体系中的最新研究进展作了阐述,并对其应用前景进行了展望。     

磁性离子液体的物性及其影响因素

磁性离子液体作为一种具有磁性的功能化离子液体,近年来受到广泛关注。讨论了常见磁性离子液体的合成与表征方法,对影响磁性离子液体物性参数(如密度、粘度、磁化率、热性能、离子电导率)的有关因素进行了分析,为进一步深入研究磁性离子液体提供参考。     

离子液体电解质在锂二次电池中的应用研究(下)

<正>(接上期)2季铵类离子液体电解质同咪唑类离子液体相比,季铵类离子液体的电化学稳定性更好,其还原电位常低于0V(vs.Li/Li+),这使其有希望可以承受     

离子液体基质子交换膜的研究进展

以Nafion为代表的全氟磺酸水化膜是目前聚合物电解质膜燃料电池(PEMFCs)中最常用的质子交换膜(PEM),但此类膜的质子导电性能强烈依赖于水,而水的冻结或蒸发会使其失去质子导电性能。离子液体具有接近零的蒸汽压、低熔点、较宽的电化学窗口,将离子液体引入PEM体系可望大大扩展PEM的工作温度范围,提高其电导率。对近年来离子液体在聚合物质子导电材料中的应用进行了综述,并对其研究发展前景作了展望。     

Charging of Polar Versus Nonpolar Liquids During Brief Exposure to Ionic Currents

Experimental results are reported which show the amount of corona charging of polar and nonpolar liquid droplets during brief exposure to ionic currents. They show that the nonpolar materials tested acquired from 10 to 36 percent less charge than equivalent water droplets and that the polar materials acquired from 1 to 15 percent more charge than the water. These differences are not predicted by the Pauthenier theory. The reason for the differences is believed to be due to the relaxation time of the materials and the effect it has on the rate at which the ionic particles may distribute themselves over the surface of the droplet. In particular, the nonpolar materials being highly resistive have long relaxation times and thus acquire fewer charges than the polar materials.     

Ionic Conductor Composites: Theory and Materials

The main theoretical concepts on ionic conduction at interfaces, especially the space charge layer model, are summarized in the first part of this review: ion trapping or redistribution leads to charge carrier accumulation, depletion or inversion and, consequently, to conductivity changes in composite materials. Experimental confirmations of the space charge layer model and the complementary percolation model are discussed. Major developments of ionic conductor composite materials over the last 25 years are presented in the second part, including lithium and other alkaline ion conductors, copper and silver ion conductors, di- and trivalent cation and anion conductors, glass and polymer composites. Some future trends and research needs are indicated in conclusion.     

When two become one: An insight into 2D conductive oxide interfaces

Recent progress has led to conductance confinement at the interface of complex oxide heterostructures, thereby providing new opportunities to explore nano-electronic as well as nano-ionic devices. In this paper we describe how interfacial contiguity between materials can trigger redox reactions inducing metallic conductivity along the interface of SrTiO₃-based heterostructures and create new types of 2 Dimension Electron Gases (2DEG) at the hetero-interface with electron mobility enhancements of more than one order of magnitude higher than those of hitherto investigated perovskite-type interfaces. Furthermore, our recent results, examining strain effects at interfaces, demonstrate the potential of achieving hetero-epitaxial thin films with superior ionic or electronic properties. We also present a novel concept that uncovers a wide variety of possible technological opportunities for materials design utilizing ionic conducting multi-layered heterostructures. These findings hold the potential to pave the way for novel and/or superior all-oxide electronic and ionic devices.     

固体氧化物燃料电池电解质材料的研究进展

介绍了固体氧化物燃料电池(SOFC)用萤石型、钙钛矿型及磷灰石型电解质材料的结构、导电机理、性能及研究进展。存在的离子电导率较低、化学组成及相组成不稳定等问题,主要通过氧化物共掺杂及不同材料之间的复合等方法来改善。材料的复合与电解质层结构的设计,将成为电解质研究的主要方向。     

Experimental analysis of the capacity of electrochemical capacitors operating with AC voltage at a frequency of 50 Hz

The aim of this work was to investigate the properties of electrochemical capacitors under alternating voltage conditions, from the point of view of their possible application to power-factor correction in the power system. The electrochemical capacitors were based on different carbon materials as well as on the following electrolytes: aqueous alkaline, organic salts dissolved in non-aqueous solvents, and room temperature ionic liquids. The capacitors with the electrolytes based on ionic liquids showed the best characteristics. The specific capacity of carbon-based capacitors, filled with ionic liquids, may reach the level of 35 mF/kg at AC voltage of 230 V at 50 Hz.     

A review of thermo-stimulated current

Various areas of application of thermo-stimulated current (TSC) spectroscopy, used for studying insulating materials, are reviewed. The characteristics of this technique are compared with those of the other thermally stimulated spectroscopies. The origins of TSC are briefly cited. Examples of the identification of TSC peaks with ionic or molecular movements (inorganic or organic materials) are given     

掺杂离子半径对LiFePO_4电化学性能的影响

采用固相反应合成了锂离子电池正极材料LiFe0.99Re0.01PO4(Re=La3+、Er3+、Gd3+、Nd3+)。利用X射线衍射、电化学阻抗谱、恒电流充放等方法对试样的微观结构和电化学性能进行测试。结果表明:掺杂没有改变LiFePO4的晶体结构;离子半径越小,晶格畸变越小,结构越稳定,大电流放电性能较好;Er3+掺杂的试样具有最佳的充放电性能,掺杂试样的电子电导率均提高4￣5个数量级。     

Electrochemical strain microscopy of local electrochemical processes in solids: mechanism of imaging and spectroscopy in the diffusion limit

Changes in ionic concentration and electrochemical processes in solids are invariably associated with changes in molar volume. Correspondingly, materials with mobile ions develop strain in response to applied electric bias. This electromechanical coupling mediated by mobile ions lays the foundation for the electrochemical strain microscopy (ESM) of energy storage and conversion materials. Here, we analyze the imaging and spectroscopic mechanism in ESM in the diffusion limit and discuss the similarities between ESM and macroscopic current-based electrochemical measurements. The theoretical challenges in ESM are formulated.     

制备工艺对(ZrO2)0.90-(Y2O3)0.04-(CaO)0.06电解质材料电性能的影响

目前ZrO2基三元系材料的研究是固体电解质材料领域的一个热点.在关于ZrO2-Y2O3-CaO系统电解质材料电性能研究的前期工作的基础上,探讨了不同的制备工艺对(ZrO2)0.90-(Y2O3)0.04-(CaO)0.06材料的电导率的影响问题,发现:对于常规烧结的试样,其电导率随相对密度的提高而增大;与常规烧结相比,微波烧结能使材料具有更均匀的微观结构,更小的晶粒平均尺寸.较小的晶粒尺寸导致的较为显著的晶界效应是微波烧结试样的电导率有所降低的主要原因.由于微波烧结可以改善材料的力学性能,因此认为微波烧结是制备ZrO2-Y2O3-CaO系统电解质材料的一条有效途径.     

Dielectric breakdown in high-ε films for ulsi DRAMs: III. Leakage current precursors and electrodes

Abstract

A somewhat qualitative review of leakage currents J(V,t) in perovskite oxides is presented. It is stressed that space-charge-limited currents (SCLCs) are not alternatives to ionic conduction, Schottky emission, Poole-Frenkel, or Fowler-Nordheim tunneling, but can occur whenever currents due to any of those mechanisms reach a certain threshold and are no longer limited by the details of the metal electrode-ferroelectric interface. Standard metal-semiconductor band models that exclude surface states fail qualitatively to account for the experimental dependences of leakage currents and breakdown voltages on electrode work function; the correct model is metal-n-p-n-metal, with surface donor-state trapping. A discussion of conduction properties in these materials is presented from an ionic conductor viewpoint.