Computational Insights to Charge Transfer Kinetics at the Cathode/Electrolyte Interface

The charge transfer reaction is the fundamental reaction for rechargeable batteries. The energy landscape of this reaction depicts the equilibrium and kinetics of the electrochemical process. Many transition metal oxide surfaces in a high oxidation state have been found to be unstable against common Li-ion electrolytes. It undergoes a spontaneous reduction upon immersion in the electrolyte in open circuit. This process involves the reduction of the cathode surface and degradation of the electrolyte to form a cathode electrolyte interphase (CEI), forming a complex cathode/CEI/electrolyte interface. However, the mechanism of this interaction remains unclear. In this work, a modeling framework was developed to predict the energy landscape of the charge transfer reaction at a LiCoO2/LiF/EC-electrolyte interface, with combined density functional theory (DFT) and molecular dynamics (MD) calculations. The energy profile of this reaction was simulated under different voltage. The mechanism of the interaction between LiCoO2 and EC-electrolyte would be discussed.