A Theoretical Study on Initial Processes of Li-Ion Transport at the Electrolyte/Cathode Interface: A Quantum Chemical Molecular Dynamics Approach

Abstract

Initial processes of Li-ion transport at the electrolyte/cathode interface of a Li-ion battery were investigated using an ultra-accelerated quantum chemical molecular dynamics (UA-QCMD) simulator. This simulator was based on our in-house tight-binding quantum chemical (TB-QC) simulator and MD simulator. The parameterization for LiCoO2 crystal and ethylene carbonate (EC) molecule in UA-QCMD was first carried out to show the fine agreement of their electronic structures and interaction energies, with the values determined by first-principles calculations. Li-ion movements in the electrolyte and at the interface between the electrolyte and cathode were simulated. It was found that in the electrolyte, a solvation, that corresponds to the formation of bonds between the Li and surrounded EC molecules was formed. When the Li-ion was moved to the cathode surface, it was observed that the interaction energies of Li-EC molecules was decreased. In such a case, the Li-ion was bound to the oxygen atoms of the cathode.