Karakterizacija strukturnih sprememb v baterijah z ramansko in emisijsko spektrometrijo rentgenskih žarkov

This thesis presents the development and application of novel characterization methodologies for studying structural and chemical changes in next generation battery technologies. This research focuses on the development and application of photon-in/photon-out spectroscopies, in particular X-ray Raman Scattering (XRS) and Laboratory X-ray Emission Spectroscopy (XES), which are used to circumvent certain limitations of the conventional X-ray absorption spectroscopy. XRS is a non-resonant inelastic photon scattering technique that overcomes the shallow probing depth limitations of traditional soft X-ray methods, enabling analysis of light elements in bulk samples and operando measurements. It was implemented for the study of structural changes in carbon anodes during Na-ion battery discharge/charge cycle and to characterize the electrochemical processes in metal-organic batteries. By analyzing the C K-edges, XRS provided information about structural changes in the hard carbon anodes as a result of initial carbonization temperature and Na insertion during cycling. The study of Na K-edges was used for characterization of Na species in the solid electrolyte interface. In the study of metal-organic batteries, XRS was used to record O K-edge spectra to monitor changes in the amount of carbonyl bonds in samples and to provide insight into the redox mechanism and reaction intermediates within the organic cathodes. The interpretation of experimental results was supported by density functional theory calculations of XAS spectra of target elements. XES enables the use of laboratory excitation sources and, when paired with high-resolution crystal Bragg spectrometers, it can achieve chemical characterization comparable to the conventional synchrotron-based XAS. Such laboratory approach improves accessibility of advanced elemental characterization in battery analysis. The feasibility of XES was demonstrated by tracking the chemical state of sulfur and characterizing sulfur species during the charge/discharge cycles of Li-S batteries.