Catalysis in lithium-oxygen batteries has attracted significant attention due to high theoretical energy density of these battery systems. While promising, the complexity of the electrochemistry at the cathode where solid lithium-oxygen species are formed and dissociated on a solid catalyst has been an obstacle in achieving the desired theoretical capacities to unable their commercialization. Therefore, the understanding of the solid-solid interfacial electrochemistry at the cathode-discharge product is key at advancing their performance. We have combined well-controlled synthesis, with theoretical calculations, electrochemical studies and detailed characterization, to show that potential-dependent discharge product distribution on oxide cathode electrocatalysts significantly effects the charge overpotentials, consequently the cell performance. We find that nanostructured oxides provide a platform to stabilize Li-deficient oxide species during discharge, consequently lowering overpotential losses associated with their oxidation during charge, leading to enhanced performance. Quantum chemical modeling of the solid-solid interface between the oxide and lithium-discharge products suggests that stabilization of the Li-deficient products is due to formation of a lithiated oxide surface with enhanced electronic conductivity. These findings provide a framework for elucidating the role of potential on discharge product distribution and the effect on charge overpotentials and cell cyclability.

Controlling discharge product distribution in Li-oxygen cathodes through electrode surface discharge mechanism

ACS Spring Meeting 2021

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.