New Insight into Differences in Cycling Behaviors of a Lithium-ion Battery Cell Between the Ethylene Carbonate- and Propylene Carbonate-Based Electrolytes

It has long been known that a lithium-ion battery cell having graphite as the anode active material in the ECbased electrolyte can be cycled, while charging of a similar cell in the PC-based electrolyte only gives rise to exfoliation of graphite. There have been numerous reports on the electrochemical differences between the two electrolytes. Yet, this observation is not completely understood. Theoretically, exhaustive calculations on the reductive decomposition intermediates of EC and PC have been reported by Balbuena and co-workers in the absence of graphite without conclusive results to explain the striking difference between EC and PC. Recently, Jeong et al. have reported that a cell could be cycled even in a PC only electrolyte if the salt concentration was high. Subsequently, Yamada et al. found a correlation between the lithium solvation structure and the intercalation behavior in a PC-based electrolyte. We believe that the co-intercalation model, developed originally by Besenhard and co-workers, later used to explain the difference between the two solventbased electrolytes by Ogumi’s group, plays a central role in the titled subject. In this report, we attempt to shed light on a series of observations using a combination of density functional theory (DFT) calculations and molecular dynamics (MD) simulations.