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首页> 外文学位 >Chemical and morphological effects on the electrochemical properties of carbon aerogels and ruthenium dioxide/carbon aerogel nanocomposites.
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Chemical and morphological effects on the electrochemical properties of carbon aerogels and ruthenium dioxide/carbon aerogel nanocomposites.

机译：化学和形态对碳气凝胶和二氧化钌/碳气凝胶纳米复合材料电化学性能的影响。

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摘要

The development of high performance electrode materials for electrochemical capacitors has been an active area of research over the past ten years due to the demand for high power portable energy storage devices. One class of material which has shown promising capacitive characteristics in aqueous electrolytes is carbon aerogels. These unique materials exhibit low resistivity, high surface area, and a controllable open microstructure. In this work, the interrelationships between the electrochemical characteristics of the carbon aerogel materials in sulfuric acid electrolytes and the chemical and physical nature of the aerogels have been identified. Specifically, this study examines the influence of surface chemistry and microstructure on the voltammetric response of the carbon aerogel electrodes.; Carbon aerogels exhibit a specific capacitance greater than 80 F/g in 1.0 M {dollar}rm Hsb2SOsb4.{dollar} This value is is dependent upon the specific surface area of each sample but is relatively independent of the bulk density of the aerogel. The density of the material does, however, influence the charging time of the electrode due to distributed capacitance effects. The surface of the carbon aerogels can be electrochemically activated to supplement the double-layer charging of the surface with a pseudocapacitive charge storage mechanism at redox-active surface functionalities.; A second aspect of this work addresses improving the capacitance of the carbon aerogel materials by chemically modifying the surface of the aerogels. Hydrous ruthenium dioxide, which has shown exceptional pseudocapacitance {dollar}rm ({lcub}>{rcub} 750 F/g)sp3,{dollar} was deposited onto the surface of the carbon aerogel materials by two approaches: chemical vapor impregnation and electrodeposition. Ruthenium metal loadings of greater than 50 wt.% could be achieved using chemical vapor impregnation. Transmission electron microscopy revealed 20A metal particles uniformly distributed on the large interior surface of the aerogels. These modified carbon aerogels exhibit capacitances as high as 250 F/g in sulfuric acid. The electrodeposition and oxidation of hydrous ruthenium dioxide onto non-porous polycrystalline graphite demonstrates the feasibility of this modification technique for increasing the capacitance of the carbon/electrolyte interface. When applied to carbon aerogels, however, the tortuous nature of the aerogel structure limits the practicality of this approach.
机译：由于对大功率便携式储能装置的需求，过去十年来，用于电化学电容器的高性能电极材料的开发一直是研究的活跃领域。在水性电解质中显示出令人鼓舞的电容特性的一类材料是碳气凝胶。这些独特的材料具有低电阻率，高表面积和可控的开放微结构。在这项工作中，已经确定了硫酸电解质中碳气凝胶材料的电化学特性与气凝胶的化学和物理性质之间的相互关系。具体而言，这项研究检查了表面化学和微观结构对碳气凝胶电极的伏安响应的影响。碳气凝胶在1.0 M {h} Hsb2SOsb4中表现出大于80 F / g的比电容。该值取决于每个样品的比表面积，但相对独立于气凝胶的堆积密度。然而，由于分布的电容效应，材料的密度确实会影响电极的充电时间。碳气凝胶的表面可以被电化学活化，以在氧化还原活性的表面官能度下用假电容电荷存储机制来补充表面的双层电荷。这项工作的第二方面致力于通过化学修饰气凝胶的表面来改善碳气凝胶材料的电容。表现出优异的假电容{USD} rm（{lcub}> {rcub} 750 F / g）sp3的含水二氧化钌，{dollar}通过两种方法沉积在碳气凝胶材料的表面：化学蒸汽浸渍和电沉积。使用化学气相浸渍可以实现大于50重量％的钌金属负载。透射电子显微镜显示20A金属颗粒均匀分布在气凝胶的大内表面上。这些改性的碳气凝胶在硫酸中的电容高达250 F / g。水合二氧化钌在无孔多晶石墨上的电沉积和氧化表明，这种改性技术可提高碳/电解质界面的电容。然而，当应用于碳气凝胶时，气凝胶结构的曲折性质限制了该方法的实用性。

著录项

  • 作者

    Miller, John Martin.;

  • 作者单位

    University of California, Los Angeles.;

  • 授予单位 University of California, Los Angeles.;
  • 学科 Engineering Materials Science.; Engineering Electronics and Electrical.
  • 学位 Ph.D.
  • 年度 1997
  • 页码 205 p.
  • 总页数 205
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 工程材料学;无线电电子学、电信技术;
  • 关键词

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