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A First Principles Study of Mass Transport in the Dehydrogenation of Lithium Amides and Lithium Alanates.

机译：酰胺锂和丙酸锂脱氢中传质的第一原理研究。

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摘要

The pursuit of competitive alternatives to energy derived from the combustion of fossil fuels, has led to a great variety of new technologies. Exceptional develop- ments in electrochemical storage and production promise to lead to clean burning passenger vehicles. The high chemical density of a hydrogen fuel cell enables it to meet current standards for driving range and weight required of vehicles, making it an excellent candidate for universal application in the automotive industry. One of the biggest obstacles the fuel cell industry has yet to overcome is the means of practical hydrogen storage. Solid state metal hydrides are a class of materials that show potential for both economic and practical hydrogen storage. The search for the ideal metal hydride is defined by thermodynamic and kinetic constraints, since the requirements for a viable system are a rapid release of hydrogen in the temperature range of -40°C, to 80°C.;First-principles density functional theory is an excellent method for gaining insight into the kinetics and thermodynamics of metal hydride solid state reactions. In the work presented here, density functional theory is used to explore formation energies, concentrations and migration barriers of metal hydrides. In particular, the following systems were analyzed: • Li - N - H It is well known that the reactive hydride composite LiNH 2 + LiH reversibly releases a large amount of hydrogen gas, with more favorable thermodynamics than LiNH2 alone. Kinetics of mass transport during the dehydrogenation of LiNH2 + LiH are investigated. A model is developed for determining activation energies of native defects in bulk crystals. In order to establish whether mass transport is the rate-limiting step in the dehydrogenation reaction, results are compared to experimental values. • Li - Al - H Kinetics of mass transport during the dehydrogenation of the metal hydride LiAlH2 are investigated. It is known that LiAlH4 endothermically decomposes via a two step reaction. The kinetics of both steps in the reactions are studied. Results are compared to experiments in order to determine whether mass transport is the rate-limiting process in the reactions.
机译：对源自化石燃料燃烧的能源的竞争性替代品的追求，导致了各种各样的新技术。电化学存储和生产方面的非凡发展有望带来清洁燃烧的乘用车。氢燃料电池的高化学密度使其能够满足当前汽车行驶里程和重量要求的标准，使其成为在汽车工业中普遍应用的极佳候选者。燃料电池行业尚未克服的最大障碍之一是实用的储氢方法。固态金属氢化物是一类具有经济和实用储氢潜力的材料。寻求理想的金属氢化物是由热力学和动力学约束条件定义的，因为可行的系统的要求是在-40°C至80°C的温度范围内快速释放氢。第一原理密度泛函理论是了解金属氢化物固态反应动力学和热力学的一种极好的方法。在这里提出的工作中，使用密度泛函理论来探索金属氢化物的形成能，浓度和迁移壁垒。特别是，分析了以下系统：•Li-N-H众所周知，反应性氢化物复合材料LiNH 2 + LiH可逆地释放大量氢气，比单独的LiNH2具有更好的热力学。研究了LiNH2 + LiH脱氢过程中的质量传输动力学。开发了用于确定块状晶体中天然缺陷的活化能的模型。为了确定传质是否是脱氢反应中的限速步骤，将结果与实验值进行了比较。 •研究了Li-Al-H在金属氢化物LiAlH2脱氢过程中的质量传输动力学。已知LiAlH 4通过两步反应吸热分解。研究了反应中两个步骤的动力学。将结果与实验进行比较，以确定传质是否是反应中的限速过程。

著录项

  • 作者

    Rolih, Biljana.;

  • 作者单位

    University of California, Los Angeles.;

  • 授予单位 University of California, Los Angeles.;
  • 学科 Materials science.;Physical chemistry.
  • 学位 Ph.D.
  • 年度 2014
  • 页码 117 p.
  • 总页数 117
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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