A lithium peroxide precursor on the α-MnO2 (100) surface

Abstract

α-MnO₂ is an active electrocatalyst for the cathode of lithium–air batteries, where the main reaction is the reversible formation of lithium peroxide. In this work we study the adsorption of lithium and oxygen on the low-energy (100) surface by atomistic simulations based on the density functional theory, in order to understand the first steps of lithium peroxide formation. Oxygen prefers to adsorb in molecular form both in the presence and in the absence of co-adsorbed lithium. This represents a marked difference with respect to other manganese oxides, where oxygen dissociation takes place, and we argue that this might be of advantage in the formation and dissolution of lithium peroxide. By studying the formation energies of Li₂O₂-like species at the surface we have identified the most probable precursor for the formation of Li₂O₂ nanoparticles on this surface. The possible consequences of these findings for the functionality of the battery are discussed.