Application of pulse methods to the determination of the electrochemical characteristics of lithium intercalates

The transfer processes proceeding in insertion electrodes with surface control on the application of a potential or current step are considered theoretically. The theoretical relationships have been verified by the determination of the kinetic and diffusion parameters of electrochemical lithium intercalation into thin carbon films. The overall electrode polarization is divided, both theoretically and experimentally, into the kinetic component, related to hindered ion transfer in the passive surface layer, and the diffusion one, related to decelerated lithium diffusion in the carbon matrix. The polarization dependence of kinetic current is shown to obey the same regularities that the current-potential function of the lithium electrode. The concentration dependences of the surface layer parameters and the diffusion coefficient of lithium in carbon have been determined. (C) 2003 Elsevier Ltd. All rights reserved.