Adsorption and Reaction Branching of Molecular Carbonates on Lithiated C(0001) Substrates

Abstract

The desorption and interactions of ethylene carbonate (EC) and dimethyl carbonate (DMC) with clean and lithiated graphite substrates were measured by temperature-programmed desorption (TPD) and reaction (TPR) methods under UHV conditions. Both EC and DMC interact weakly with the clean C(0001) surface with adsorption energies of 0.60 ± 0.06 and 0.64 ± 0.05 eV, respectively. Addition of Li+ to the C(0001) substrate significantly increases the binding energies of molecular carbonates, and the range of measured values is indicative of EC solvation of lithium ions. EC undergoes complete decomposition on metallic Li films. Organolithium products were quantified by TPR, and the amount of lithium carbonate product was determined by detailed mass balance analysis. Decomposition of 1.5 L of EC resulted in the formation of 0.64 ± 0.12 L of lithium ethylene dicarbonate, 0.40 ± 0.05 L of lithium ethylene glycolate, and 0.5 ± 0.2 L of lithium carbonate. The branching ratio at the immediate EC–metallic lithium interface...