Li K edge EXAFS via X-ray Raman spectroscopy

KELLER, LEVI; HONKANEN, ARI-PEKKA; RASOLA, MIKKA; PAREDES MELLONE, OSCAR ARIEL; HUOTARI, SIMO JOOSEPPI

Workshop; EBS workshop on X-ray Raman scattering spectroscopy; 2019

Lithium is the backbone of today?s high-capacity battery technology. As a highly mobile,light, and rather abundant element, it is well suited for an ionic charge carrier for energystorage purposes. Its lightness can also be a complication as its small scattering cross-section and spectral overlap of Li K edge with valence-electron excitations, such as theplasmon, make it an elusive element to study. For example, X-ray absorption fine-structure(XAFS) measurements commonly used to derive the oxidation state and the localenvironment of an element have limited bulk-sensitivity and are restricted to simple sampleenvironments due to the low energy of the photons. However, in order to gaincomprehensive understanding of kinetics of Li in realistic electrochemical situations, in situinvestigation methods are essential.X-ray Raman spectroscopy (XRS) is a unique method giving the access to low energyexcitations using hard x-rays allowing the study of light elements in complex environments[1-3]. Therefore it is a suitable candidate for in situ Li studies [4]. We investigated theutilization of XRS as a practical method to obtain high quality extended X-ray absorptionfine structure (EXAFS) of Li K edge at ID20 at multiple momentum transfers from variousLi compounds.References[1] - T.T. Fister et al., AIP Conference Proceedings, 882, 156 (2007).[2] - S. Huotari et al., J. Synchrotron Rad. 19, 106-113 (2012).[3] - Ch. Sahle et al., Proceedings fo the National Academy of Sciences 110, 6301-6306 (2013).[4] - T.T. Fister et al., The Journal of Chemical Physics 135, 224513 (2011).