Effect of Mg doping and MgO-surface modification on the cycling stability of LiCoO2 electrodes

Two synthetic routes including Mg doping and MgO-surface modification were applied to the preparation of LiCoO2 showing enhanced reversible cycling be haviour as cathode material in lithium ion batteries. Mg-doped LiCoO2 was o btained by the citrate precursor method in the temperature range 750-900 de greesC. The surface of LiCoO2 was modified by coating with Mg(CH3COO)(2) an d subsequent heating at 600 degreesC. XRD, chemical oxidative analysis and electron paramagnetic resonance (EPR) of Ni3+ spin probes were used to char acterize the Mg distribution in LiCoO2. Substitution of Co by Mg in the CoO 2-layers was found to have a positive effect on the cycling stability, whil e Mg dopants in LiO2-layers did not influence the capacity fade. The accumu lation of MgO on the surface of LiCoO2 improves the cycling stability witho ut loss of initial capacity. (C) 2001 Elsevier Science BY. All rights reser ved.