Efficient Li2O2 oxidation kinetics of perovskite-type lanthanum chromium-based oxide by promoter interface formation for lithium-oxygen batteries

초록

The development of oxygen evolution reaction (OER) catalysts for the decomposition of discharge products, Li2O2, is important in terms of energy efficiency because of the significant overpotentials during the charging process. In this study, the perovskite, ABO3, has been synthesized as an important functional material that exhibits various stoichiometries and crystal structures. They can accommodate metals entirely or partially at the A and/or B sites without destroying the crystal structure owing to their structural features. Therefore, perovskites provide a way to correlate solid-state chemistry with catalytic properties. Herein, we design a series of La0.8Sr0.2CrOx as practical OER catalysts by controlling the oxidation states and ionic/electron conductivities using the crystallization modulation method. In-situ Raman spectroscopy confirms that the perovskite-type La0.8Sr0.2CrO3 nanowires actively oxidize Li2O2 and increases the OER activity. The La0.8Sr0.2CrO3 nanowires exhibit OER activity by providing an electron acceptor or donor (Cr3+-Cr6+) that is modulated as an OER-active site (Li2CrO4) capable of favorable interaction with Li-deficient solid solution (Li2-xO2) during the charging process. This study provides fundamental insights into OER mechanisms and understanding of OER catalysts properties. These are essential for designing effective electrodes with high-energy efficiency, which is one of the key challenges for rechargeable Li-O2 batteries.

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