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MM: Fachverband Metall- und Materialphysik
MM 40: Focus Session: Battery Materials – Experimental Characterisation and Safety Testing (joint session KFM/MM)
MM 40.9: Talk
Wednesday, March 20, 2024, 18:05–18:25, EMH 225
Vacancies on the Lithium-Sublattice in the Solid-State Electrolyte LLZO employing Positron Annihilation Spectroscopy — Dominik Boras1, Andreas Kohrmann1, Daniel Wagner1, Daniel Göbel1, Janez Kosir2, Tanja Kallio2, and •Torsten E.M. Staab1 — 1Institute for Functional Materials and Biofabrication, Julius-Maximilians Universität Würzburg, D-97070 Würzburg, Röntgenring 11 — 2Department of Chemistry, Aalto University, Kemistintie 1, FIN-02015 Espoo
We characterise the electrolyte LLZO for all solid-state batteries. LLZO (Li7La3Zr2O12) samples have been synthesised via the mixed-oxide route, i.e. grinding and calcination, grinding again, then pressing and finally sintering the pellets. We varied the doping (Fe, Al) and the excess Li content. The formed phases (cubic and tetragonal) have been characterised by XRD, while the lattice defects have been investigated by the method of positron annihilation lifetime spectroscopy (PALS). By PALS we were able to see clear differences after calcination when varying the lithium excess. Measuring powder with increasing Li-excess a lifetime component, which could be related to the bulk crystal significantly decreases from 220ps to 190ps. This may be an indication of more and more filled Li-lattice site after the calcination step. Sintered pellets showed two different positron lifetimes (190 / 200ps and 326 / 374ps) for both un-doped / Al-doped samples. This first attempt shows the potential of PALS to characterise all sold-state electrolytes with respect to defects and the occupation of crystal lattice site influencing the mobility of Li ions.
Keywords: All solid-state batteries; LLZO; solid electrolyte; Positron Annihilation