Imaging the Composition and Structure of Battery Materials at High Resolution and Low Dose Using Cryo-Electron Energy Loss Spectroscopy and Ptychography

Battery materials are by design incredibly sensitive to radiation damage by an electron beam – after all they are designed to allow ion motion in response to an applied electric field, and a high-brightness electron beam can certainly provide strong, localized fields. Cryogenically freezing the sample not only reduces the diffusion of radiation-damage products, but makes it possible to prepare site-specific electron-transparent cross-sections of liquid-solid interfaces such as the electrolyte/SEI/electrode [1]. With advances in direct detector technology, more sophisticated image reconstruction methods have been made practical. Multislice Electron ptychography is a highly-dose-efficient approach [2] to imaging the internal arrangement of lithium ions and vacancies at atomic resolution with 3D information inside battery electrodes. Electron energy loss spectroscopy (EELS) provides chemical information, even in disordered materials. As the dose efficiency of EELS is much lower, we apply non-linear dimensionality reduction methods to reveal the structure, reaction products and chemical gradients inside the SEI layer and in contact with the liquid electrolyte and lithium dendrites.<br/><br/>Work in collaboration with Dasol Yoon, Michael Colletta, and in memory of Lena Kourkoutis who started our projects on the cryoEELS of battery materials.<br/><br/>[1] 1. MJ Zachman, Z Tu, S Choudhury, LA Archer, LF Kourkoutis (2018) Cryo-STEM mapping of solid–liquid interfaces and dendrites in lithium-metal batteries. <i>Nature</i>, 560(7718):345–349<br/>[2] Z. Chen, Y. Jiang, Y.-T. Shao, M. E. Holtz, M. Odstrčil, M. Guizar-Sicairos, I. Hanke, S. Ganschow, D. G. Schlom, and D. A. Muller. “Electron Ptychography Achieves Atomic-Resolution Limits Set by Lattice Vibrations” <i>Science</i> <b>372</b>, (2021): 826–831