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MM: Fachverband Metall- und Materialphysik

MM 37: Materials for Energy Storage and Conversion - Structure of Battery Materials

MM 37.3: Vortrag

Mittwoch, 18. März 2020, 12:15–12:30, IFW D

Highly stable and highly conductive LiCoPO4 olivine-based thin film 5V cathode material. — •Gennady Cherkashinin¹, Robert Eilhardt¹, Silvia Nappini², Igor Píš², Federica Bondino², Simone dal Zilio², Elena Magnano², Matteo Cococcioni³, and Lambert Alff¹ — ¹Technische Universität Darmstadt, Germany — ²IOM CNR Laboratorio TASC, Basovizza, TS, Italy — ³Physics Department, University of Pavia, Italy

Recently, we have discovered high electronic conductivity of the LiCoPO4 olivine 5V cathode thin film material tailored with LiCo2P3O10. The crystal structure of the compound remains stable even if all Li-ions leave the olivine structure, which corresponds to ~5.1V vs. Li+/Li. Here we explore the intrinsic stability of the novel thin film cathode material and the stability of cathode/electrolyte interface upon the charging/discharging potential in the 3.0-5.1V range. We apply the comprehensive in-situ electron spectroscopy approach (XPS and XAS) combined with first principle calculations to study the evolution of the oxidation and valence states, the Co3d-O2p hybridization, the work function, the density of occupied and unoccupied states near the Fermi level, the chemical composition, etc. as a function of the Li-content. We show that the electronic structure/properties of the compound are fully reversible; LiCo2P3O10 stabilizes the olivine structure in its fully delithiated state. First-principles simulations predict ~5.2V redox for LiCo2P3O10. Thus, higher energy density via the involvement of LiCo2P3O10 into the redox reaction is possible. A reason of enhanced conductivity at atomic level is analyzed.