CAREER: Analytical Investigation of the Spatiotemporal Heterogeneities in Particulate Porous Electrodes toward Precision Electrochemical Kinetics

锂离子电池（lib）通过实现变革性的电子设备、便携式电源和电动汽车，彻底改变了人们的生活方式。在需要高能量密度、高功率密度和系统简单性的地方，它们是储能技术的热门选择。然而，难以捉摸的安全事故，如热失控，已成为迫切关注的问题。锂离子电池和其他高能电池的失效往往源于微观的非均质性，这是现有方法难以监测、分析和预测的。通过将单颗粒级材料行为与器件级响应联系起来，在中尺度上研究这些异质性，将使人们能够更准确地理解和更有效地管理电池。从这项研究中产生的见解和知识将有助于设计更安全的电池，从而避免严重的早期退化和事故。该项目将产生对电化学能源系统的新认识，有利于研究生、本科生和K-12学生的教育。作为该项目的一部分，将建立一个暑期课程，针对代表性不足的高中年龄学生和高中教师，使用平衡和动力学的工程概念。这个基础工程科学研究项目的重点是研究电池电极中鲜为人知的时空异质性，这被认为是控制电极过程的理论和实验动力学参数之间存在巨大差异的原因。该项目将利用可见光和激光拉曼显微镜进行operando实验，通过直接导数图像分析，对现实电极中数百个粒子的异质性进行动态量化，以评估真实的局部电流密度。基于物理的模型没有对限速步骤的假设，可以一致地确定真正的局部动力学参数和电极过程的限速步骤，这将解决长期存在的差异，并改变该领域的普遍理解。深度整合的实验和理论方法允许多点校准以保证可靠的框架，这可以为电池材料和电极的整体设计提供更有效的指导。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Lithium-ion batteries (LIBs) have revolutionized the way people live by enabling transformative electronic devices, portable power, and electric vehicles. They are popular choices of energy storage technologies, wherever high energy density, high power density and system simplicity are required. However, elusive safety accidents, such as thermal runaways, have become an urgent concern. Failures of LIBs and other high-energy batteries always originate from microscopic heterogeneities, which are difficult to be monitored, analyzed, and predicted by existing methods. Investigations of these heterogeneities at the mesoscale by connecting the single-particle level materials behaviors with the device-level responses, will enable more accurate understanding and more effective management of batteries. The insights and knowledge generated from this study will help to design safer batteries, in which severe early degradation and accidents can be avoided. This project will generate new understanding of electrochemical energy systems that can benefit the education of graduate, undergraduate and K-12 students. As part of the project, a summer program will be established that will target underrepresented high school age students and high school teachers using engineering concepts of equilibrium and dynamics.This fundamental engineering science research project focuses on the less understood spatiotemporal heterogeneities in battery electrodes, which are hypothesized to be responsible for the large discrepancies between the theoretical and the experimental kinetic parameters that control the electrode processes. The project will utilize operando experiments using visible light and laser Raman microscopes allow the dynamic quantification of heterogeneities among hundreds of particles in realistic electrodes to evaluate the true local current densities via direct derivative image analysis. Physics-based models without presumptions on the rate-limiting step allow consistent determination of the true local kinetic parameters and the rate-limiting step of the electrode processes, which will resolve the long-standing discrepancies and change the prevailing understandings in this field. The deeply integrated experimental and theoretical approaches allow multiple-point calibrations to warrant a reliable framework, which can provide more effective guidance for the holistic design of battery materials and electrodes.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.