Reducing Over-Potentials in Lithium-Oxygen Batteries Using Iridium and Reduced Graphene Oxide Cathodes

Abstract

The focus of this dissertation was to characterize the electrochemical mechanisms and discharge products present in Li-O2 batteries containing iridium and reduced graphene oxide (rGO) based cathodes. These novel materials are used to stabilize the lithium superoxide (LiO2) reaction intermediate and prevent chemical disproportionation to the more common lithium peroxide (Li2O2) discharge product. Strong lattice matching between iridium-based catalyst surfaces and LiO2 increases the activation barrier of LiO2 disproportionation to Li2O2. Stabilizing LiO2 as the discharge product results in lower battery charge overpotentials due to the substantially higher electronic conductivity of LiO2, compared to Li2O2, which is a bulk insulator.