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

High-efficiency electrocatalysts of palladium and α-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–O₂ 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–O₂ batteries due to its low cost, high catalytic activity, and good oxygen reduction behavior. This study integrates the synergic effects of α-MnO₂ nanowires and palladium nanoparticles by decorating on graphene sheets to improve cyclability and capacity to obtain highly efficient performance of Li–O₂ cells. As-prepared rGO/Pd/α-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 α-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.