Graphene-based nanocomposite cathodes architecture with palladium and alpha-MnO2 for high cycle life lithium-oxygen batteries

Abstract

High-efficiency electrocatalysts of palladium and alpha-MnO2 nanowires supported on reduced graphene oxide (rGO) sheets are developed through an effective process to enhance the electrochemical performance of current lithium-oxygen batteries. Palladium is known as an oxygen evolution reaction (OER) electrocatalyst in Li-O-2 cathode to reduce the charge overpotential and exhibit stable cycling performance. On the other hand, MnO2 is an attractive, functional transition metal oxide catalyst in Li-O-2 batteries due to its low cost, high catalytic activity, and good oxygen reduction behavior. This study integrates the synergic effects of alpha-MnO2 nanowires and palladium nanoparticles by decorating on graphene sheets to improve cyclability and capacity to obtain highly efficient performance of Li-O-2 cells. As-prepared rGO/Pd/alpha-MnO2 hybrid nanocomposite cathode indicates an initial discharge capacity of 7500 mA h g(-1) and stable cycle life for 50 cycles at a limited capacity of 800 mA h g(-1). As a result, although the polarization of the cell dramatically decreases and stable capacity behavior is observed with the contribution of alpha-MnO2 and Pd catalysts, the limited stable cycle life of 50 is obtained due to the consumption of lithium metal which causes total capacity failure after 60 cycles. (C) 2020 Elsevier B.V. All rights reserved.