Grain Boundary Orientation Impacts on Internal Resistance in Solid State Lithium Ion Conductors

让美国摆脱对化石燃料的依赖对国家安全和经济繁荣至关重要。从化石燃料到电力的高效过渡将需要在几分钟内快速安全地为电池充电的能力，而不是几个小时。固态电池因其固有的安全性而有望完成这项任务，但目前它们无法以足够的速度充放电。这个项目将研究固态电池中阻碍充放电速度的电解液的特性。所获得的知识将使改进电解液的工程实现更快的速度。该项目还将开发旨在说明科学过程的教育宣传材料，并将重点放在实验失败上。他们将展示失败的实验是如何成为科学过程的关键组成部分，以及社会的知识是如何随着时间的推移建立在所学到的经验教训的基础上的。这一基础研究项目的目标是确定导致钙钛矿结构锂离子导体中跨晶界离子传导电阻的特征，并根据特定的晶界取向对离子电阻进行分类。采用脉冲激光沉积技术在单晶、双晶和大颗粒多晶绝缘衬底上制备锂离子外延导电膜。将通过电子背散射衍射和使用微接触电化学阻抗谱测量单个晶界的离子电导率来评估晶界和晶界的取向。将对离子传导阻力的性质进行评估，以确定其来源是结构性的还是电子性的。在确定了不同晶界取向的离子电导率后，将使用横截面扫描电子显微镜来测量局部化学成分和结构。这些参数将被用来确定在固态锂离子导体中导致晶界电阻的机制。利用这些信息，将建立导致穿过晶界的高和低离子电导率的特征和颗粒排列，然后可以用来设计使导电路径中的高阻晶界的布居最小化的微结构。最终结果将是朝着实现高功率快速充放电固态锂离子电池迈出的一步。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Freeing the U.S. from reliance on fossil fuels is important for national security and economic prosperity. Efficient transition from fossil fuels to electricity will require the ability to rapidly and safely charge batteries in minutes rather than hours. Solid-state batteries have promise to accomplish this task because of their inherent safety, but they are currently unable to charge and discharge at sufficient rates. This project will study the features of electrolytes in solid-state batteries that hinder charge and discharge rates. The knowledge gained will allow engineering of improved electrolytes to achieve faster rates. The project also will develop educational outreach materials designed to illustrate the scientific process and will focus on experimental failures. They will show how failed experiments are a key component of the scientific process and that society’s knowledge is built over time upon the lessons learned.The goal of this fundamental research project is to determine the features that lead to resistance in ionic conduction across grain boundaries in perovskite-structured lithium ion conductors and to categorize ionic resistances by specific grain boundary orientations. Epitaxial lithium ion conducting films will be prepared by pulsed laser deposition on single crystal, bicrystal, and large-grained polycrystalline insulating substrates. The grain and grain boundary orientations will be assessed via electron backscatter diffraction and the ion conductivity measured across the individual grain boundaries using microcontact electrochemical impedance spectroscopy. The nature of resistance to ionic conduction will be assessed to determine whether the origin is structural or electronic in nature. With the ionic conductivity of different grain boundary orientations determined, cross-sectional scanning transmission electron microscopy will be employed to measure the local chemical compositions and structures. These parameters will then be used to determine the mechanisms that lead to grain boundary resistances in solid-state lithium ion conductors. Using this information, the features and grain alignments that lead to high and low ion conductivities across grain boundaries will be established, which may then be used to design a microstructure that minimizes the populations of high resistivity boundaries in the conduction path. The end result will be a step toward realizing high power fast charge and discharge solid-state lithium ion batteries.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.