Characterization of nanocrystalline HT-LiCoO2 cathode materials for secondary lithium batteries

Abstract

Comparative analysis of two LiCoO2 powders with mean grain size 3-5 mum and 50-60 nm, obtained by freeze drying synthesis, is performed. Both samples belong to high temperature (HT) hexagonal modification of LiCoO2 and display good crystallinity by XRD while local electron diffraction patterns indicate the traces of disorder in the nanocrystalline powder. Differential capacity versus voltage curves of nanosized LiCoO2 demonstrate perfect reproducibility of Li intercalation since 1st cycle. Electrochemical capacity of nanomaterial is decreased to 115 mAh/g during first cycles with little or no further changes. Dependence of the electrochemical performance on the grain size is referred to the existence of distorted areas in the nanocrystalline sample. (C) 2004 Elsevier Ltd. All rights reserved.