锂离子电池的电化学阻抗谱分析研究进展

锂离子电池的电化学阻抗谱（EIS）是研究电化学系统最有力的实验方法之一,在过去的20多年中,EIS 被广泛应用于锂离子电池研究和生产领域,包括研究电极界面反应机理和容量衰减机制,测定相关电极过程动力学参数和电池的健康状态、荷电状态以及电池的内阻。本文分析了锂离子电池中电极极化过程包含的3 个基本物理化学过程———电子输运、离子输运和电化学反应过程,探讨了每一基本物理化学过程包含的步骤及其EIS 谱特征,详细论述了与电子输运相关的基本物理化学过程———接触阻抗和感抗产生的机制;介绍了多孔电极理论及其在锂离子电池中的应用,阐述了基于多孔电极理论进行阻抗谱数值模拟的建模原理与方法。 综述了石墨、硅、二元3d 过渡金属氧化物、LiCoO₂、尖晶石LiMn2O4、LiFePO4、尖晶石Li4Ti5O12、过渡金属氟化物材料等电极的典型阻抗谱特征和各时间常数的归属问题。最后讨论了EIS现存的问题及未来的发展方向。     

锂离子电池的电化学阻抗谱分析研究进展

锂离子电池的电化学阻抗谱( EIS) 是研究电化学系统最有力的实验方法之一,在过去的20多年中,EIS被广泛应用于锂离子电池研究和生产领域,包括研究电极界面反应机理和容量衰减机制,测定相关电极过程动力学参数和电池的健康状态、荷电状态以及电池的内阻。本文分析了锂离子电池中电极极化过程包含的3个基本物理化学过程——电子输运、离子输运和电化学反应过程,探讨了每一基本物理化学过程包含的步骤及其EIS谱特征,详细论述了与电子输运相关的基本物理化学过程——接触阻抗和感抗产生的机制;介绍了多孔电极理论及其在锂离子电池中的应用,阐述了基于多孔电极理论进行阻抗谱数值模拟的建模原理与方法。综述了石墨、硅、二元3d过渡金属氧化物、LiCoO_2、尖晶石LiMn_2O_4、LiFePO_4、尖晶石Li_4Ti_5O_(12)、过渡金属氟化物材料等电极的典型阻抗谱特征和各时间常数的归属问题。最后讨论了EIS现存的问题及未来的发展方向。     

电容去离子过渡金属基电极设计及应用研究进展北大核心CSCD

电容去离子(Capacitive deionization,CDI)作为一种新兴的水淡化和离子分离方法,由于其离子选择性高、水回收率高和能耗低等优点受到广泛关注。与传统的基于碳电极的CDI相比,新兴的法拉第电极通过离子捕获的法拉第反应,提供了使得CDI的脱盐性能大幅提升的独特机会。而过渡金属基电极由于其高度可逆的法拉第响应,相对较高的导电性以及出色的理论赝电容值等优势,在CDI电极设计领域受到广泛关注。本文系统地归纳和梳理了过渡金属基电极在CDI应用中的材料分类,总结了针对其本征缺陷所进行改性工程,主要包括导电材料耦合、功能结构工程和缺陷工程等,并对其在海水淡化中的性能进行了总结;此外,从离子选择性分离、金属离子去除和营养元素回收等方面介绍了过渡金属基电极在CDI中的特定应用。最后,概述了剩余的挑战和研究方向,为未来的过渡金属基电极的开发与研究提供指导。     

固态电解质锂离子输运机制研究进展

全球环境问题推动了可充电锂电池技术的飞速发展.与液态电解液相比,固态电解质不易燃,构筑所得固态电池的安全性能得以提升.如果能够理解固态电解质中的离子输运行为,就能精准调控固态电池锂的动力学稳定性和倍率性能.随着计算机技术的快速发展,原子尺度模拟技术成为理解材料离子输运的重要手段.针对以上问题,本综合评述首先汇总了固体材料中的常见扩散机制;然后介绍了固态电解质中的锂离子输运机制,着重讨论了影响固态电解质锂离子输运的重要因素(晶体结构、电子结构、外部因素及晶界);最后对固态电解质锂离子输运机制研究进行了总结与展望.     

钒基电极材料研究进展

发展低成本、高性能、高安全的锂离子、钠离子电池是解决能源储存问题的一个重要途径. 由于具有丰富的化学价态,开放式的化学结构和较高的理论容量,钒基材料是一种非常有潜力的锂离子电池、钠离子电池电极材料. 在过去的几年中,钒基电极材料如钒的氧化物、硫化物、磷酸盐等在电池中的应用取得了长足的进展,有必要对相关的研究进展作一个总结. 本文介绍了钒基电极材料的近期研究进展,重点总结了钒基电极材料应用所面临的离子扩散系数低、结构稳定性差等科学问题,并从活性材料本身的改性以及与外部材料复合作用两个角度重点分析了应对这些问题所采用的策略. 一方面,通过对钒元素的化合价态进行调控来提高材料的电导性,并采用异原子掺杂来加快离子扩散系数. 另一方面,借助同/异种纳米结构间的耦合作用增强材料的结构稳定性. 基于基底的骨架作用,实现三维有序阵列结构电极的制备,进而促进材料能量密度与功率密度的共同提升. 最后,讨论了钒基材料进一步发展所面临的挑战,希望能够为将来相关电极材料的研究提供一些参考.     

原子尺度研究固体氧化物池氧电极中氧迁移规律

固体氧化物燃料电池（SOFC）和固体氧化物燃料电解池（SOEC）作为新一代的能源转化装置,凭借其清洁、高效的能源转化优势,非常具有技术吸引力。为了将SOFC和SOEC商业化,操作更加持久、高效和经济,中低温的运行温度成为当前国际上研究的主要方向,其中提高氧电极材料的氧还原反应/氧析出反应（ORR/OER）活性是研究的关键。本文主要阐述了原子尺度分子模拟分析和原位实验测试表征对混合离子电子导体氧电极材料中氧迁移规律和传输机理研究的重要作用,推进传统材料向新型氧电极材料和结构的发展;归纳和综述了近期热点的混合离子电子导体（MIEC）氧电极材料、相应的离子传输路径、各向异性结构及晶格动力学;介绍了当前采用的先进研究手段和方法,并重点介绍了原位X射线光电子能谱（XPS）和俄歇电子光谱（AES）探测材料的表面化学组成和结构,原位的方式可以将致密薄膜中几纳米到十几纳米的结构可视化,在原子层面上研究氧电极材料中带电缺陷的形成和迁移;并基于原子尺度的密度泛函理论（DFT）计算和近期分子动力学模拟（MD）的研究进展对传统材料和新型材料中的氧迁移机理进行解释和分析。最后,简要综述了清华大学核研院在固体氧化物池氧电极方面的研究进展。     

钙钛矿型LaCoO3电化学储锂的形貌调制效应

采用不同方法制备了块状(Bulk)、 纳米球状(NPs)及三维有序多孔(3DPF)钙钛矿型LaCoO₃电极材料, 并考察了材料的形貌、 结构与电化学储锂之间的相关性. 结果表明, 不同形貌的电极材料均呈钙钛矿型晶体结构, 但电化学储锂性能却表现出巨大差异: 在500 mA/g的电流密度下, 块状、 纳米球状及三维有序多孔LaCoO₃电极经350次循环后放电比容量分别为157, 579和648 mA·h/g. 电化学性能的迥异主要归因于所制备的纳米及多孔结构使活性材料与电解液之间的接触面积增大, 反应活性位点明显增多, 传质电阻降低, 从而使电子传输和Li离子的嵌入/脱嵌过程得到显著改善.     

纳米多孔金的单分子层门控离子输运性质研究

生物离子通道能够对环境刺激作出响应,有效地调节细胞内外的物质平衡,保证体内的正常生命活动.研究具有生物离子通道功能的人工离子通道对发展离子开关具有重要的意义.本工作利用电化学去合金法制备了具有三维通道结构的纳米多孔金膜,并将其应用于离子通道,研究其离子输运性质.在电场作用下,纳米多孔金由于发生极化而使通道表现出离子整流性质.在纳米多孔金表面修饰十二烷基硫醇单分子层,利用其疏水效应,通道能够阻止离子的传输,使其处于“关闭”态.溶液中的化学刺激如表面活性剂能够增强电解质溶液在通道表面的浸润,有利于离子的传输,使通道处于“打开”态.这种单分子层修饰的纳米多孔金表现出表面活性剂响应的离子开关特性.     

当前和下一代锂离子电池电解液的原子尺度微观认识和研究进展

电解液及构筑电极电解液界面对于开发和应用高比容量储能系统至关重要。具体来说，电解液的机械（抗压性、粘度）、热（热导率和热容）、化学（溶解性、活度、反应性）、输运和电化学（界面及界面层）等性质，与其所组成的储能器件的性能直接相关。目前，大量的实验研究通过调控电解液的物理和/或化学组成来改善电解液性能，以满足新型电极材料的工作运行。与此同时，理论模拟方法近年来得到了迅速发展，使人们可以从原子尺度来理解电解液在控制离子输运和构筑功能化界面的作用。站在理论模拟研究的前沿上，人们可以利用其所揭示的机理性认识对新型电解液开展理性设计。本文首先总结了传统电解液的组成、溶剂化结构和输运性质以及电极电解液界面层的形成机理，进一步讨论了利用新型电解液设计稳定电极电解液界面层的方法，包括使用电解液添加剂、高浓电解液和固态电解质，并着重讨论了对这些新型电解液体系进行原子尺度模拟的最新进展，为了解和认识电解液提供更为基本的理解，并为未来电解液的设计提供系统的指导。最后，作者对新型电解液的理论筛选进行了展望。     

柱状薄层离子色谱电自生式抑制器

设计一种新型的柱状薄层离子色谱电自生式抑制器.采用多孔电极实现电极-电解液室一体化,消除了电极-电解液室的电压降;柱状薄层的抑制室结构规范了装配工艺并简化了结构,提高其抑制器的性能.     

Electrochemistry and capacitive charging of porous electrodes in asymmetric multicomponent electrolytes

We present porous electrode theory for the general situation of electrolytes containing mixtures of mobile ions of arbitrary valencies and diffusion coefficients (mobilities). We focus on electrodes composed of primary particles that are porous themselves. The predominantly bimodal distribution of pores in the electrode consists of the interparticle or macroporosity outside the particles through which the ions are transported (transport pathways), and the intraparticle or micropores inside the particles, where electrostatic double layers (EDLs) are formed. Both types of pores are filled with electrolyte (solvent plus ions). For the micropores we make use of a novel modified-Donnan (mD) approach valid for strongly overlapped double layers. The mD-model extends the standard Donnan approach in two ways: (1) by including a Stern layer in between the electrical charge and the ions in the micropores, and (2) by including a chemical attraction energy for the ions to go from the macropores into the micropores. This is the first paper where the mD-model is used to model ion transport and electrochemical reactions in a porous electrode. Furthermore we investigate the influence of the charge transfer kinetics on the chemical charge in the electrode, i.e., a contribution to the electrode charge of an origin different from that stemming from the Faradaic reaction itself, e.g. originating from carboxylic acid surface groups as found in activated carbon electrodes. We show that the chemical charge depends on the current via a shift in local pH, i.e. ??current-induced charge regulation.?? We present results of an example calculation where a divalent cation is reduced to a monovalent ion which electro-diffuses out of the electrode.     

Electrochemical Impedance Analysis of Thermogalvanic Cells

Thermogalvanic cells(also known as thermo-electrochemical cells) that convert waste heat energy to electricity are a new type of energy conversion device. However, the electron transfer kinetics and mass transfer of redox couples have not been thoroughly studied. Here, the ion reaction and charge transport in thermogalvanic cells are investigated by electrochemical impedance analysis. We first propose the detailed impedance model followed experimental verification on three types of electrode materials. Parameters including kinetic rate constants and ion diffusion coefficients for the electrodes are obtained by fitting the impedance data. Our study shows explicitly that impedance analysis can provide useful information on selecting suitable electrode materials for thermogalvanic cells.     

Engineering porous electrodes for next-generation redox flow batteries: recent progress and opportunities

Redox flow batteries are a promising electrochemical technology for energy-intensive grid storage applications, but further cost reductions are needed for universal adoption. As porous electrodes are responsible for functions within the flow cell that impact charge transfer, ohmics, and mass transport, improvements in electrode materials and design may yield significant performance and economic benefits. This mini-review summarizes recent developments in the design and characterization of porous electrodes with a focus on understanding and controlling both the microstructure and surface chemistry, which broadly align with mass transport and reaction kinetics. Key opportunities and challenges in the science and engineering of these materials are also presented with the goal of engaging the broader community and accelerating progress towards chemistry-specific flow battery electrodes.     

CR传输线解析EIS表征杯芳烃离子选择电极

电化学阻抗谱(EIS)是表征电化学体系特征及其过程机理的重要技术,但解谱模型不一致限制了其应用.为此,采用CR传输线模型中的8CRR等效电路拟合文献报道的杯[4,8,12]芳烃离子选择电极与Na+、Ca2+及Fe3+作用的EIS;并根据电荷转移电阻、表面吸附、扩散阻力和空间电荷层电容等不同特征,揭示了作用机理的共性与差异.结果表明,所采用的方法可操作性强,结果客观,具有一定的理论和应用价值.     

The Thermodynamics of Insertion Electrochemical Electrodes—A Team Play of Electrons and Ions across Two Separate Interfaces

Insertion electrochemical electrodes exhibit simultaneous electron and ion transfer, with the two transfers proceeding across different interfaces. Herein the thermodynamics of the overall electrochemical electrode reaction is discussed with respect to the thermodynamics of these two charge‐transfer equilibria. This Minireview includes insertion electrochemical systems where the redox centers are in a solid phase and the ions are transferred between that phase and a solution, and also systems where the redox centers are in a liquid phase that is immiscible with another liquid phase and ions are transferred between the two liquid phases. The Minireview is intended to spark similar studies on battery materials to improve their performance.     

Computer modeling of negative electrode operation in lithium-ion battery: Model of equal-sized grains,galvanostatic discharge mode,calculation of characteristic parameters

A computer simulation of the negative electrode (anode) operation in a lithium-ion battery is performed. A complete research program is carried out in accordance with the recommendations of the theory of porous electrodes: the “model of equal-sized grains of two types” was studied, percolation properties of the anode active layer were researched, values of effective coefficients were calculated for charge transfer and mass transport, a complete system of equations describing operation of the anode is presented. Two specific cases of galvanostatic mode of anode discharge are considered in detail: an “ideal” anode and anode with nanosize particles. Working anode parameters are calculated: optimum bulk concentration of graphite in the active layer, active layer thickness, time of complete anode discharge, its specific electric capacitance and final potential on the active/layer interelectrode space interface. Advisability of working with anodes with nanosize grains and electrolyte with enhanced specific conductivity is shown.     

Electrochemical charge transfer mediated by metal nanoparticles and quantum dots

Electron transfer processes mediated by nanostructured materials assembled at electrode surfaces underpin fundamental processes in novel electrochemical sensors, light energy conversion systems and molecular electronics. Functionalisation of electrode surfaces with hierarchical architectures incorporating self-assembling molecular systems and materials, such as metal nanostructures, quantum dots, carbon nanotubes, graphene or biomolecules have been intensively studied over the last 20 years. Important steps have been made towards the rationalisation of the charge transfer dynamics from redox species in solution across molecular self-assembling systems to electrode surfaces. For instance, a unified picture has emerged describing the factors which determine the rate constant for electron transfer processes across rigid self-assembling molecular barriers. An increasing bulk of evidence has recently shown that the incorporation of nanomaterials into self-assembling monolayers leads to an entirely different electrochemical behaviour. This perspective rationalises some of the key observations associated with nanoparticle mediated charge transfer, such as the apparent distance independent charge transfer resistance observed for redox species in solution. This behaviour only manifests itself clearly in the case where the probability of direct charge transfer from the redox probe to the electrode is strongly attenuated by self-assembling molecular barriers. Here we will highlight specific issues concerning self-assembled monolayers as blocking barriers prior to discussing the effect of nanoparticles on the electrochemical response of the system. Selected examples will provide conclusive evidence that the extent of charge transfer mediation is determined by the overlap between the density of states of the nanostructures and the energy levels of redox species in solution. Only in the case where a strong overlap exists between the energy levels of the two components, the nanostructures behave as "electron launchers", allowing efficient charge transfer across insulating molecular layers.     

Colloidal Supercapattery: Redox Ions in Electrode and Electrolyte

Redox chemistry is the cornerstone of various electrochemical energy conversion and storage systems, associated with ion diffusion process. To actualize both high energy and power density in energy storage devices, both multiple electron transfer reaction and fast ion diffusion occurred in one electrode material are prerequisite. The existence forms of redox ions can lead to different electrochemical thermodynamic and kinetic properties. Here, we introduce novel colloid system, which includes multiple varying ion forms, multi‐interaction and abundant redox active sites. Unlike redox cations in solution and crystal materials, colloid system has specific reactivity‐structure relationship. In the colloidal ionic electrode, the occurrence of multiple‐electron redox reactions and fast ion diffusion leaded to ultrahigh specific capacitance and fast charge rate. The colloidal ionic supercapattery coupled with redox electrolyte provides a new potential technique for the comprehensive use of redox ions including cations and anions in electrode and electrolyte and a guiding design for the development of next‐generation high performance energy storage devices.     

粉末多孔镍电极电化学阻抗谱及其数学模型

镍电极反应动力学在大多情况下是受固态质子扩散过程控制的，以此为出发点建立了具有明确物理意义的镍电极电阻抗谱（ＥＩＳ）的数学模型，并以该模型为基础，讨论了一些模型参数如双电层电容Ｃｄ１，质子扩散系数Ｄ及活性物质粒子半径ｒ０等改变，电极的不同荷电状态及多孔镍电极中的传质过程对镍电阻阻抗谱的影响，理论模型较好地解释了一些实验结果。