Interpreting Electrochemical Processes in Energy Storage Materials with In situ S/TEM Techniques

Friday, March 12, 2021: 10:30 AM - 11:05 AM

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Description

Recent advances in the development and implementation of in situ/operando S/TEM techniques have resulted in new research opportunities, where it is now feasible to image dynamic chemical and electrochemical processes at high spatial resolution and under external stimuli. In this talk, I’ll demonstrate how in situ electrochemical S/TEM (ec-S/TEM) can be utilized for energy storage research and in particular, to probe the mechanisms and kinetics of solid electrolyte interphase formation and Li electrodeposition in batteries. In this work, annular dark field (ADF) S/TEM imaging is used to quantify the thickness of the SEI and account for the dark contrast observed for Li during electrodeposition. In addition to the high spatial resolution imaging, we also apply electron energy loss spectroscopy (EELS) to identify metallic Li and components of the SEI (e.g. LiF, Li2O, LiOH) while still intact within the liquid electrochemical cell. Furthermore, we provide a framework for obtaining and analyzing quantitative EELS measurements to directly determine the oxidation state of battery electrodes (LiMn2O4 and Li4Ti5O12) using the “white-lines” of the L2,3 core loss ionization edges of Mn and Ti. By simultaneously acquiring low-loss and core-loss EEL spectra, we are able to remove plural scattering effects caused by scattering through the electrolyte and quantify the oxidation state of Mn and Ti using the white-line intensity ratio method. The information obtained from these studies can help provide a deeper understanding of materials transformations for energy storage and conversion applications.

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Track(s)

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  Energy

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Additional Info

Keywords: Please select up to 4 keywords ONLY:
Materials Characterization,Microscopy