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首页> 外文学位 >Real-time Investigation of Li Microstructure Formation on Li Anodes for Li Batteries by Solid-state Li NMR, SEM, MRI and X-ray Tomography.
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Real-time Investigation of Li Microstructure Formation on Li Anodes for Li Batteries by Solid-state Li NMR, SEM, MRI and X-ray Tomography.

机译：通过固态Li NMR，SEM，MRI和X射线断层扫描实时研究Li电池在Li阳极上Li的微结构形成。

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摘要

With increasing demands for higher energy storage, Li metal with the highest possible energy density and specific capacity of 3800 mA h g-1 has come back into focus as an attractive candidate for an anode material. However, there are still critical difficulties involving safety issues caused by the growth of Li microstructures (dendrites and moss) during cycling, which prevent its use in practical applications. In order to solve the various problems, fundamental understanding of behavior of Li metal anodes in working batteries and the conditions under which Li microstructures are formed is necessary.;In situ NMR has a demonstrated ability to capture real time structural changes that are not obtainable via ex situ studies, such as the formation of metastable states and microstructural Li. In this research, I provide the first assignments of the Li metal NMR shifts to the different microstructure morphologies observed by SEM. The assignments are supported by susceptibility calculations, the results being critical in the development of a method to monitor cell failure in situ. Magnetic resonance image (MRI) has also been performed to study the change in concentration of the lithium ions in the electrolyte in the vicinity of the electrode interface during current flow. Sand's time theory1 is employed to investigate the relationship between dendrite formation and electrolyte concentration. Non-destructive X-ray phase contrast tomography was applied to further characterize electrochemical Li symmetrical cells. In situ tomography allows examination of microstructure growth in 3D at high resolution. The multiple growth and removal mechanisms reflect the complexity of the lithium electrodeposition and dissolution process in Li batteries.;The ability of the techniques performed here to distinguish between mossy and dendritic-type morphologies lays the groundwork for future investigations of Li depositions aimed at identifying the conditions (e.g., additives, applied current) where microstructural formation is minimized in practical Li metal-based batteries such as Li/S and Li/air.
机译：随着对更高能量存储的需求的增加，具有尽可能高的能量密度和3800 mA h g-1的比容量的锂金属作为负极材料的有吸引力的候选材料而重新受到关注。然而，仍然存在涉及由锂微结构（枝晶和苔藓）在循环过程中生长引起的安全问题的严重困难，这阻碍了其在实际应用中的使用。为了解决各种问题，有必要对工作电池中的锂金属阳极的行为以及形成锂微结构的条件有基本的了解。；原位NMR具有捕获实时结构变化的能力，该结构变化是无法通过微波获得的。异位研究，如亚稳态和微结构锂的形成。在这项研究中，我提供了锂金属NMR转变到SEM观察到的不同微观结构形态的最初分配。敏感性计算支持这些分配，结果对于开发一种就地监测细胞衰竭的方法至关重要。还已经进行了磁共振图像（MRI）以研究在电流流动期间在电极界面附近的电解质中锂离子浓度的变化。利用Sand的时间理论1研究了枝晶形成与电解质浓度之间的关系。应用非破坏性X射线相衬层析成像技术进一步表征电化学Li对称电池。原位层析成像可以高分辨率检查3D的微观结构。多种生长和去除机制反映了锂电池中锂电沉积和溶解过程的复杂性。此处执行的技术区分苔藓型和树突型形态的能力为今后研究锂沉积奠定了基础，旨在研究锂的沉积。在实际的基于锂金属的电池（例如Li / S和Li / air）中使微结构形成最小化的条件（例如，添加剂，施加的电流）。

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  • 作者

    Chang, Hee Jung.;

  • 作者单位

    State University of New York at Stony Brook.;

  • 授予单位 State University of New York at Stony Brook.;
  • 学科 Analytical chemistry.;Organic chemistry.;Physical chemistry.
  • 学位 Ph.D.
  • 年度 2015
  • 页码 164 p.
  • 总页数 164
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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