Two-Dimensional Crystal Phases of Graphene Monoxide & Interaction of Lithium with Graphene Monoxide

Abstract

This work explores the possible existence, properties, and potential applications of different polytypes of graphene monoxide (GmO) - two-dimensional crystalline monolayers composed of equal numbers of O and C atoms. In addition to previously experimentally discovered and theoretically modeled α phase, prediction and discovery of the second phase - β-GmO - is reported along with evaluation of six other possible phases. Structural parameters, electronic and mechanical properties of all the phases, including α-GmO, are determined using density functional calculations and compared. It is suggested that multiple phases of GmO can co-exist in the same composite, and developing a synthesis process for single-phase GmO may be experimentally challenging. The interaction of Li atoms with monolayers of the two experimentally discovered phases - α and β - is investigated in various LixCyOy structures to determine if these monolayers can bind Li atoms and to predict an upper limit for the maximum theoretical capacity of these potentially new anode materials for Li-ion batteries. Present research concludes that α-GmO has some desirable properties for this application but undergoes breaking of C-O bonds in a range of lithiated configurations, while β-GmO is systematically being damaged at high Li concentrations.