Enhancement of electrochemical ion/electron-transfer reaction at solid|liquid interface by polymer coating on solid surface

Controlling the ion/electron-transfer reaction at the electrode|electrolyte (solid/liquid) interface is a necessary and vitally important point for improving the operation of various electrochemical devices. In this paper, we propose a polymer coating technique which enhances the Li+ ion-transfer reaction at the LiCoO2|electrolyte interface, and confirm the effects of the polymer coating by cyclic voltammetry (CV) and AC impedance techniques. The results from the experiments indicated that the application of an F-introduced polymer on the LiCoO2 (LCO) surface decreased the activation barrier for Li+ ion transfer. Besides the electrochemical studies, the present computational results indicated that the Li+ exchange process between two states, which are both solved with ethylene carbonate (EC) and coordinated with an F-introduced polymer, might occur due to the close energy levels of Li+ stability. Accordingly, we inferred that the transition state of this exchange process promotes the observed decrease in activation energy for the interfacial Li+-transfer reaction.