CAREER: Analytical Cryo-Scanning Transmission Electron Microscopy for Understanding Physical and Chemical Processes at Liquid/Solid Interfaces

非技术概述：界面和表面在合成新材料、实现化学反应、设计电子器件和确定结构材料的机械稳定性方面发挥着特殊的作用。为了实现理解液体和固体界面上的过程的目标，例如决定电池如何工作和如何失效的过程，该项目的目标是开发和应用新的电子显微镜技术，不仅允许在纳米到原子尺度上研究固体/固体，而且允许研究液体/固体和软/硬界面。该项目将通过提供对各种技术感兴趣的材料的高分辨率表征技术对科学和技术产生影响，从而促进科学、材料发现和应用的进步。该项目还将为新生、K-12学生和教师提供刺激和真实的体验，目标是激励新一代科学家。显微镜将在这些努力中发挥核心作用，其中包括为全国K-12教师开发一个新生实验室模块和一个基于显微镜的科学工具包。技术综述：电子显微镜的最新进展开启了固体内原子分辨率成像和光谱分析的新时代。液/固界面尚未以高空间分辨率成像，但在从催化到电化学储能再到生物矿物形成的一系列生物、化学和物理过程中发挥着关键作用。在生物系统电子显微镜的启发下，PI获得了这一职业奖项，开发了新的样品制备技术，使用快速冷冻将复合系统的软和液体组分稳定在玻璃状态，使低温STEM能够进行结构和光谱研究。对于足够薄可以在显微镜下直接分析的材料，如液体电解液中的纳米结构电极材料，无机晶体成分和周围液体的晶体结构和缺陷将同时成像。对于较厚的样品，包括锂-金属电池，将开发低温聚焦离子束提升器，以进入内部液/固界面。这一表征平台将用于研究锂-金属/电解液界面枝晶形成的早期阶段，以获得对其形成和生长机制的基本了解。识别枝晶生长的形核位置的能力将为开发高能可充电金属电池的核心挑战提供新的线索。该项目的目标是创造更广泛、更多样化的劳动力，重点是在早期阶段吸引和招募学生进入科学、技术、工程和数学领域。K-12教师的发展是通过MicroWorld支持的，这是一个基于显微镜的模块，将被调整以满足下一代科学标准的挑战。该单元将为在少数族裔学校工作的K-12教师提供教师讲习班，并将通过CCMR借阅实验图书馆向全国教师提供。新生将从FLAME的发展中受益，FLAME是一个新的新生电子显微镜实验室。因此，该项目将对科学、技术、工程和数学教育产生影响，无论是在K-12阶段还是在大学阶段。

Non-technical summary: Interfaces and surfaces play a special role in synthesizing novel materials, enabling chemical reactions, designing electronic devices, and determining the mechanical stability of structural materials. To realize the goal of understanding processes at interfaces between liquids and solids, processes that for example determine how batteries function and how they fail, the objective of this project is to develop and apply novel electron microscopy techniques that allow not only solid/solid, but also liquid/solid and soft/hard interfaces to be studied at the nanometer to atomic scale. This project will have an impact on science and technology by providing high-resolution characterization techniques of materials that are of interest for a wide range of technologies thereby promoting the progress of sciences, materials discovery and applications. The project will also provide stimulating and authentic experiences for freshmen, K-12 students and teachers with the goal of motivating a new generation of scientists. Microscopy will play a central role in these efforts, which include the development of a freshman laboratory module and a microscopy-based science kit for K-12 teachers nationwide. Technical summary: Recent advances in electron microscopy have opened a new era of atomic resolution imaging and spectroscopy inside solids. Liquid/solid interfaces have yet to be imaged at high spatial resolution but play a critical role in a range of biological, chemical and physical processes from catalysis to electrochemical energy storage to the formation of biominerals. Inspired by electron microscopy of biological systems, with this CAREER award, the PI develops new sample preparation techniques that use rapid freezing to stabilize the soft and liquid components of composite systems in a vitreous state enabling structural and spectroscopic studies by cryo-STEM. Materials that are sufficiently thin for direct analysis in the microscope such as nanostructured electrode materials in liquid electrolytes, the crystal structure and defects of the inorganic crystalline components and the surrounding liquid will be simultaneously imaged. For thicker samples, including lithium-metal batteries, cryo-focused ion beam lift-out will be developed to gain access to the internal liquid/solid interfaces. This characterization platform will be used to study the early stages of dendrite formation at lithium-metal/electrolyte interfaces to gain a fundamental understanding of the mechanisms governing their formation and growth. The ability to identify nucleation sites for dendritic growth will shed new light on a central challenge in developing high-energy rechargeable metal batteries.With the goal of creating a broader, more diverse workforce, this project focuses on attracting and recruiting students into the fields of science, technology, engineering and mathematics at an earlier stage. K-12 teacher development is supported through MicroWorld, a microscopy-based module that will be adapted to meet the challenges of the Next Generation Science Standards. This module will benefit teacher workshops for K-12 teachers who work in minority-serving schools and will also be made available to teachers nationwide through the CCMR Lending Library of Experiments. Freshmen will benefit from the development of FLAME, a new Freshman Lab on Advanced Microscopy with Electrons. This project will therefore impact science, technology, engineering and mathematics education, both at the K-12 and the college level.