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

Density functional theory (DFT) calculations and classical molecular dynamics (MD) simulations have been performed to gain insight into the difference in cycling behaviors between the ethylene carbonate (EC)-based and the propylene carbonate (PC)-based electrolytes in lithium-ion battery cells. DFT calculations for the ternary graphite intercalation compounds (Li+(S)(i)C-n: S=EC or PC), in which the solvated lithium ion Li+(S)(i) (i=1 similar to 3) was inserted into a graphite cell, suggested that Li+(EC)(i)C-n was more stable than Li+(PC)(i)C-n in general. In addition, MD simulations were carried out to examine the solvation structures at a high salt concentration: 2.45 mol kg(-1). The results showed that the solvation structure was significantly interrupted by the counter anions, having a smaller solvation number than that at a lower salt concentration (0.83 mol kg(-1)). The results from both DFT calculations and MD simulations are consistent with the recent experimental observations.