High energy resolution X-ray emission spectroscopy (XES), probing the valence occupied electronic states below the Fermi level, can be used to provide information on local electronic structure and bonding configuration of atoms within different technologically relevant bulk materials. Generally, XES spectra are independent on the excitation mode and different laboratory sources of ionizing radiation can be used to produce the initial core hole state. Using dedicated in-vacuum tender X-ray emission spectrometer, XES can be successfully applied to perform electronic structure analysis of bulk materials (solid and liquid phase) with emission energies in the tender X-ray range, which is experimentally slightly specific. Within this project we will try to develop and establish sulfur XES as a laboratory tool used to characterize the structure and chemistry of sulfur cathode within high energy density metal-sulfur batteries. Batteries based on sulfur cathode materials theoretically provide an order of magnitude higher energy density than currently available lithium-ion batteries and are considered as one of the most promising options for high energy density applications. In order to reach the capacities required for commercial applications, fundamental understanding of the complex sulfur redox mechanism needs to be improved. For that purpose, operando analytical techniques capable to perform non-destructive analysis of bulk cathode material in an operating environment are essential. At the moment, X-ray absorption spectroscopy (XAS) performed at synchrotron facilities is most commonly applied to address sulfur electrochemistry within the working battery cell. The restricted access to synchrotron beamlines represents a bottleneck for routine sulfur XAS analysis across the electrochemical community. In this project, experimental and methodological concept based on the laboratory operando XES will be developed and used to address sulfur electrochemical conversion within next generation sulfur-based battery systems aiming for increased capacity and stability.
Prof. Dr. Matjaž Kavčič
Dr. Matjaž Kavčič‘s work is focused on the development and application of X-ray spectroscopic methods using synchrotron radiation, particularly “photon-in/photon-out” techniques that combine excitation with monochromatic X-ray light and detection of emitted or scattered radiation with high energy resolution. This experimental approach is used to study fundamental properties of isolated atoms and molecules and analyze the electronic structure of advanced bulk materials.
Research programme: Studies of atoms, molecules and structures by photons and particles
Training topic: Developing laboratory tender X-ray emission spectroscopy to characterize next-generation lithium-sulfur batteries