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。它们是储能技术的热门选择，无论是在需要高能量密度，高功率密度和系统简单性的地方。然而，难以捉摸的安全事故，如热失控，已成为一个紧迫的问题。锂离子电池和其他高能电池的失效往往源于微观非均匀性，现有方法难以对其进行监测、分析和预测。通过将单粒子水平的材料行为与设备水平的响应联系起来，在介观尺度上对这些非均匀性进行研究，将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理解，可以使研究生，本科生和K-12学生的教育受益。作为该项目的一部分，将建立一个暑期项目，将针对代表性不足的高中年龄的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电池电极中较少了解的时空异质性，这被假设为是控制电极的理论和实验动力学参数之间的巨大差异的原因流程.该项目将利用可见光和激光拉曼显微镜进行操作性实验，通过直接导数图像分析对实际电极中数百个颗粒之间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，没有假设的限速步骤允许一致的确定真正的局部动力学参数和限速步骤的电极过程，这将解决长期存在的分歧，并改变在这一领域的主流认识。该奖项反映了NSF的法定使命，通过使用基金会的智力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.