We are excited to share our newest paper where we study surface lithium ion mobility in a solid-state electrolyte using extreme ultraviolet second-harmonic generation spectroscopy (XUV-SHG). This work was published in Nature Materials.
In this work, we investigate a prototypical solid-state electrolyte using linear and nonlinear extreme-ultraviolet spectroscopies. Leveraging the surface sensitivity of extreme-ultraviolet-second-harmonic-generation spectroscopy, we obtained a direct spectral signature of surface lithium ions, showing a distinct blueshift relative to bulk absorption spectra. First-principles simulations attributed the shift to transitions from the lithium 1 s state to hybridized Li-s/Ti-d orbitals at the surface. Our calculations further suggest a reduction in lithium interfacial mobility due to suppressed low-frequency rattling modes, which is the fundamental origin of the large interfacial resistance in this material. Our findings pave the way for new optimization strategies to develop these electrochemical devices via interfacial engineering of lithium ions.
This work was done in collaboration with researchers from UC San Diego, University of Tokio, Argonne National Laboratory, UC San Diego, and the University of Nevada Las Vegas. The measurements were conducted at the SACLA free-electron laser at RIKEN in Japan.
Open-access to the research paper at Nature Materials:
College of Chemistry press release: