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Electrical and dielectric behavior of manganese-dioxide electrochemical electrodes.

机译：二氧化锰电化学电极的电和介电行为。

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摘要

Manganese dioxide (MnO2) is widely used in battery electrodes. The dielectric and electrical conduction properties of MnO2 electrochemical electrodes with and without carbon black (CB, an electrically conductive additive), with and without an electrolyte (15 vol.% sulfuric acid), have been studied for various volume fractions of MnO2 and CB. The case without the electrolyte pertains to MnO2 particle compacts (40-75 vol.% MnO2). The case with the electrolyte pertains to MnO2 particle pastes (30-83 vol.% MnO2).;As the MnO2 volume fraction increases from 40% to 75%, the relative dielectric constant increases from 58 to 72 for the MnO2 compact and from 61 to 75 for the MnO2 solid in the compact, and the resistivity decreases from 18000 to 11000 Ω.cm for the compact and from 9700 to 8100 Ω.cm for the MnO2 solid in the compact. Increase in the MnO2 volume fraction increases the relative dielectric constant of the MnO2 solid in both compacts and pastes, due to the increasing dielectric connectivity of the MnO2 particles. However, it decreases the resistivity of the MnO2 solid in compacts and increases this resistivity in pastes. The presence of the electrolyte has negligible effect on the relative dielectric constant of the MnO 2 solid, but significantly decreases the resistivity of the MnO 2 solid. The interparticle interface enhances the compact resistivity, but reduces the paste resistivity. The compacts are effectively modeled as MnO2 and air in parallel electrically, whereas the pastes are effectively modeled as MnO2 and the electrolyte in series.;The CB resistivity is significantly decreased and the CB relative dielectric constant is increased by the presence of the electrolyte, indicating that the electrolyte helps the CB electrical/dielectric connectivity. The CB resistivity in the presence of MnO2 is higher than that in the absence of MnO 2, indicating that the CB electrical connectivity is reduced by the presence of MnO2. The resistivity of CB in an MnO2 compact (without electrolyte) decreases from 236 to 165 O.cm as the CB volume fraction increases from 13.5 to 29.5% and the MnO2 volume fraction decreases from 68.6% to 58.7%, indicating increasing CB electrical connectivity. This is accompanied by decrease of the relative dielectric constant of CB from 53 to 12, suggesting decreasing CB polarizability as the CB is less squished by the lesser amount of MnO2. For similar reasons, the resistivity of CB in the MnO2 paste (with electrolyte) decreases from 49 to 34 O.cm and the relative dielectric constant of CB decreases from 29 to 22 as the CB volume fraction increases from 18% to 25%.;This thesis research has provided new information on the effects of the MnO2 volume fraction, the CB volume fraction and the presence of the electrolyte, and has provided decoupling and determination of the contributions from the MnO2, CB and electrolyte to the electrical resistance and capacitance. The decoupled information on the MnO2 and CB and the effect of the electrolyte on the properties of MnO2 and CB have not been previously reported. The new information strengthens the science base needed for the design of electrode materials. The methodology demonstrated in this thesis may be applied to the study of a large variety of electrochemical devices.
机译：二氧化锰（MnO2）广泛用于电池电极。对于不同体积分数的MnO2和CB，已经研究了带有或不带有炭黑（CB，一种导电添加剂），带有和不带有电解质（15％（体积）硫酸）的MnO2电化学电极的介电和导电性能。没有电解质的情况属于MnO2颗粒压块（40-75 vol。％MnO2）。带有电解质的情况属于MnO2颗粒糊状物（30-83％（体积）MnO2）;随着MnO2体积分数从40％增加到75％，MnO2压块的相对介电常数从58增加到72，从61增加到61对于压块中的MnO2固体为75至75，电阻率从压块的18000降至11000Ω.cm，对于压块中的MnO2固体从9700降至8100Ω.cm。由于MnO2颗粒的介电连接性增加，因此MnO2体积分数的增加会增加压坯和糊料中MnO2固体的相对介电常数。但是，它降低了压块中MnO2固体的电阻率，并增加了浆料中的该电阻率。电解质的存在对MnO 2固体的相对介电常数的影响可忽略不计，但是显着降低了MnO 2固体的电阻率。粒子间的界面增强了致密电阻率，但降低了浆料电阻率。压实模型有效地建模为MnO2和空气并联，而糊剂有效模型化为MnO2和电解质串联。;由于电解质的存在，CB电阻率显着降低，CB相对介电常数提高，表明电解质有助于CB的电/电连接。存在MnO2时的CB电阻率高于不存在MnO2时的CB电阻率，表明MnO2的存在会降低CB的电连通性。随着CB体积分数从13.5增加到29.5％，MnO2压块（无电解质）中CB的电阻率从236降低到165 O.cm，而MnO2体积分数从68.6％降低到58.7％，表明CB的电连通性增加。这伴随着CB的相对介电常数从53降低到12，这表明CB极化率降低，因为CB被较少量的MnO2压扁了。出于类似的原因，随着CB体积分数从18％增加到25％，MnO2浆料（含电解质）中CB的电阻率从49降低到34 O.cm，CB的相对介电常数从29降低到22。这项研究为MnO2体积分数，CB体积分数和电解质的存在提供了新的信息，并提供了去耦和确定MnO2，CB和电解质对电阻和电容的贡献的方法。先前尚未报道过有关MnO2和CB的解耦信息以及电解质对MnO2和CB的性能的影响。新信息加强了电极材料设计所需的科学基础。本文所论证的方法学可以应用于多种电化学装置的研究。

著录项

  • 作者

    Moalleminejad, Morteza.;

  • 作者单位

    State University of New York at Buffalo.;

  • 授予单位 State University of New York at Buffalo.;
  • 学科 Materials science.;Polymer chemistry.
  • 学位 M.S.
  • 年度 2015
  • 页码 81 p.
  • 总页数 81
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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