Kinetic characteristics of mixed conductive electrodes for lithium ion batteries

The rate performances of four mixed conductive electrodes (Li4/3Ti5/3O4, LiFePO4, LiCoO2 and LiCo1/3Ni1/3Mn1/3O2) were investigated using alvanostatic charge/discharge, electrochemical impedance Spectroscopy (EIS) and galvanostatic intermittent titration (GITT). These four electrode aterials can be roughly divided into two groups according to the structure change during Li intercalation/extraction, i.e. the phase transition aterials (Li4/3Ti5/3O4 and LiFePO4) and mixed phase transformation and solid solution materials (LiNi1/3Mn1/3Co1/3O2 and LiCoO2). Both the onic conductivity and phase transition kinetics have a strong impact on the rate capability of the electrode material in addition to the generally ccepted factors such as particle size and electronic conductivity. The rate capabilities of Li4/3Ti5/3O4 and LiFePO4, which have an extended flat egion in the charge/discharge curves, mainly depended on their phase transition kinetics. The rate performance of the solid solution materials were ontrolled by the ionic conductivity, with some influence from the electronic conductivity. 2006 Elsevier B.V. All rights reserved.