Topic 01-11 - Solid electrolyte/cathode interfaces in ceramic all solid state batteries

Proposed PhD research project will be devoted to investigating the processes on the interface of solid cathode materials and solid electrolytes in solid state cells, with a special focus on understanding the degradations mechanisms in solid-state ceramic cathodes.

The project will deal with two important classes of oxide and phosphate-based ceramic electrolytes, such as Li7La3Zr2O12 (LLZO) and LiAlxTi2-x(PO4)3 (LATP), and respective oxide- and phosphate-based cathode active materials. Expected contributions to the solid electrolyte/cathode impedance such as slow kinetics of charge transfer across the electrolyte/cathode interface; the formation of high impedance reaction phases during processing; the electrochemical degradation of electrode components during operation and/or the mechanical degradation of the electrode due to the bias-induced volume changes will be investigated on the planar model electrode systems as well as on 3D-cathode structures with different morphologies. PhD project will be conducted mainly in JÜLICH. The research tasks will involve fabrication of ceramic planar and 3D-cathode structures with varying microstructure and density, their electrochemical characterization and physico-chemical characterization of their bulk, interfacial and microstructure properties for different fabrication and electrochemical operation conditions.

This research will be supported by theoretical calculations on the atomic and system levels performed in JÜLICH and TU Delft. During 6 months, PhD student will work in Twente on fabrication of model planar electrodes with the defined interfaces, followed by structural analysis of local atomic ordering at the interfaces. In-depth investigation of structure, chemical composition and generic electrochemical properties of solid cathode/electrolyte interfaces in planar electrodes will be performed during additional 6-9 months stay in TU Delft using several neutron analytical tools, such as neutron depth analysis and neutron reflectommetry (Li-distribution and transport), neutron diffraction (structure), solid state NMR (local chemical environment and Li-ion mobility) but also positron annihilation (defects) and operando atomic force/scanning electrochemical microscopy coupled to an electrochemical impecance spectrometer (local electrochemistry).