Cathode solid electrolyte interface's function originated from salt type additives in lithium ion batteries

- Our chemical analysis determines the important functional groups of cathode's solid electrolyte interface originated from salt type additives.
- Our quantum chemical calculation reveals the redox character of the additives and their candidate chemical components of the solid electrolyte interface.
- Our molecular dynamics simulation reproduces the selective lithium ion translocation and protective layer formation as the solid electrolyte interface function.

This is the study about the cathode's solid electrolyte interface (SEI) formation mechanism of salt type additives (STAs) and its function. To address this issue, we performed several types of chemical analysis and computer simulation techniques. In order to reveal the redox nature and oxidative decomposition dynamics, the electrolyte (EL) solution dynamics by Quantum mechanics and Molecular mechanics (QM/MM) method was applied. The estimation of SEI chemical components agrees with our chemical analyses data and other group's reports. The molecular dynamics simulation of sub micro second sampling indicates that the SEI phase induced from STAs functions as a lithium ion selective translocation media and protective coating layer against the degradation of the solvent molecules. The results give us an insight how to design additive's chemical structure to improve longevity of the cell in the high voltage regime.