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

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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.