Electrochemical and Infrared Studies of the Reduction of Organic Carbonates

problematic due to co-intercalation of solvent molecules along with Li+ ion into the graphite and subsequent exfoliation 1. The electrolyte commonly used in commercial lithium-ion cells is based on ethylene carbonate (EC), even though these batteries have poorer low temperature performance.2 Research efforts have, with some success3,4, pursued additives to PC to generate a SEI layer that prevents PC co-intercalation. The mechanism of functioning of these additives is, however, still uncertain. We have performed quantum chemical calculations of the thermodynamic reduction potential of eleven organic molecules at an inert electrode assuming one-electron reduction.5 Here we report our experimental determinations of the reduction potentials of EC, PC, diethylcarbonate (DEC), dimethylcarbonate (DMC) and vinylene carbonate (VC), and compare them with calculated values. The role of VC as an additive was also investigated and the SEI layer resulting from its reduction characterized by infrared spectroscopy. EXPERIMENT