THE MECHANISM OF LITHIUM INTERCALATION IN GRAPHITE FILM ELECTRODES INAPROTIC MEDIA .2. POTENTIOSTATIC INTERMITTENT TITRATION AND IN-SITU XRD STUDIES OF THE SOLID-STATE IONIC-DIFFUSION

The potentiostatic intermittent titration technique (PITT) and in situ XRD have been used to measure the dependence of the diffusion coeffic ient D-o of lithium ions in graphite on the intercalation level X. Thi n graphite electrodes provide an excellent opportunity to obtain highl y-resolved data (with respect to X). A non-monotonic peak-shape depend ence of log D-o vs. X has been observed, which correlates well with th e corresponding dependence of the XRD peak intensity and the cyclic vo ltammetric peaks. The results thus obtained have been explained tentat ively within a framework similar to the Daumas and Herold cluster mode l for the staged phase transition. Problems connected with the determi nation of the true values of D-o for porous electrodes are also discus sed.