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Development of nano-engineered powders of lithium amide - lithium nitride for solid state hydrogen storage.

机译：开发用于固态储氢的氨基锂-氮化锂纳米工程粉末。

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摘要

Solid-state hydrogen storage offers the potential of storing hydrogen onboard vehicles in a volumetrically dense fashion at modest temperatures and pressures. The LiNH2 + LiH system has a 6.5 wt% H2 capacity; however, ammonia emission and kinetic issues currently limit the applicability of this material for onboard storage. These limitations are addressed by using high-energy ball milling to generate powders with crystallite sizes near 20nm and specific surface areas more than 10x larger than commercially available powders. This milling process also causes tremendous mixing of the two phases, thereby preventing the escape of ammonia (an intermediate species of the dehydrogenation reaction) from the system. The kinetics of the dehydrogenation reaction have been analyzed and exhibit diffusion controlled behavior. By developing a low temperature milling technique, the defect concentration in the milled particles is shown to increase, which in turn increases the diffusion constant of NH3 through the Li2NH product layer by 450%. Although this provides a 41% increase in the effective reaction rate, the microstructure generated by low temperature milling would typically not be stable at operating temperatures of 285°C (0.9 Tm of LiNH2). However, due to the fine mixture of independent phases and the low packing density caused by ball milling, substantial microstructural evolution is inhibited. As a result, the kinetic improvements gained from the nano-engineering approach are stable through 60 charge and discharge cycles (approximately 200 hours at 285°C). The significance of this stability extends beyond the LiNH2 + LiH system as stability of nanostructures is a key element in many solid-state hydrogen storage systems.
机译：固态氢存储提供了在适度的温度和压力下以体积密集方式将氢存储在车上的潜力。 LiNH2 + LiH系统的H2容量为6.5 wt％；但是，氨的排放和动力学问题目前限制了这种材料在船上存储中的适用性。通过使用高能球磨来生产微晶尺寸接近20nm，比表面积比市售粉末大10倍以上的粉末，可以解决这些限制。该研磨过程还引起两相的大量混合，从而防止了氨（脱氢反应的中间物质）从系统中逸出。分析了脱氢反应的动力学，并表现出扩散控制行为。通过开发低温研磨技术，显示出研磨颗粒中的缺陷浓度增加，这又使NH3通过Li2NH产物层的扩散常数增加了450％。尽管这将有效反应速率提高了41％，但由低温研磨产生的微观结构通常在285°C（0.9 Tm的LiNH2）工作温度下不稳定。但是，由于独立相的精细混合和球磨导致的低堆积密度，因此抑制了微观组织的实质性发展。结果，通过纳米工程方法获得的动力学改进在60个充放电循环（在285°C约200小时）下是稳定的。这种稳定性的重要性超出了LiNH2 + LiH系统的范围，因为纳米结构的稳定性是许多固态氢存储系统中的关键要素。

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  • 作者

    Osborn, William Alexander.;

  • 作者单位

    University of Connecticut.;

  • 授予单位 University of Connecticut.;
  • 学科 Energy.;Engineering Materials Science.
  • 学位 Ph.D.
  • 年度 2009
  • 页码 124 p.
  • 总页数 124
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 能源与动力工程;工程材料学;
  • 关键词

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