Dresden 2020 – scientific programme

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O: Fachverband Oberflächenphysik

O 20: Oxides II: Structures, Interactions and Reducibility

O 20.9: Talk

Monday, March 16, 2020, 17:45–18:00, WIL B321

First-Principles Study of Lithium Oxide Surfaces and Crystallites for Lithium-Oxygen Batteries — •Behnaz Rahmani Didar and Axel Gross — Institut für Theoretische Chemie, Universität Ulm, 89069 Ulm, Germany

Li-O₂ batteries are a promising alternative to Li-ion batteries as they theoretically provide the highest possible specific energy density. In this type of battery, O₂ anions produced in the cathode react with Li cations produced from the oxidation of the Li anode, thus forming LiO₂, and more prominently, Li₂O₂, as discharge products. Li₂O₂ is an electronic insulator and its precipitation on the cathode is thought to be the main limiting factor in achieving high capacities. SEM and TEM observations reveal crystallite morphologies of Li₂O₂ compounds, rather than uniform layers covering the electrode surface. The shapes and crystallite morphologies of LiO₂ and Li₂O₂ particles, may all affect the capacity, rechargeability and generally the electrochemistry of the cell. The precise morphologies and their effects, however, remain largely undetermined. We use DFT calculations and ab initio thermodynamics to study the stability of these oxide surfaces, and their crystallite morphologies. Surface-state analyses are also employed to gain insight into the electronic structure of these oxides.