Relationship between calorimetric and structural characteristics of lithium-ion cells - II. Determination of Li transport properties

The effective chemical diffusion coefficient of Li (DLi+) and related kinetic properties for lithium intercalation/deintercalation in LixCoO2 were determined by the galvanostatic intermittent titration technique (GITT). DLi+ values reached a peak at ca. x = 0.5 in LixCoO2, and this maximum correlates with phase transitions in the lithium host electrode which were indicated by the enhancement factor (W) and area-specific impedance (<ASI(t)>) variations. The phase dependence of the DLi+ values at about x = 0.5 was investigated, and a decrease of DLi+ value with increasing temperature was found. The DLi+ behavior during cycling confirms that the phase transition is reversible. (C) 2000 The Electrochemical Society. S0013-4651 (00)02-008-5. All rights reserved.