Analysis of high rate performance of nanoparticled lithium cobalt oxides prepared in molten KNO3 for rechargeable lithium-ion batteries

Nanoparticled lithium cobalt oxides (LiCoO2) were easily prepared using low-melting KNO3 as reaction media and investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and galvanostatic charge-discharge cycling. The LiCoO2 sample heating at 700 degreesC for 8 h shows well-crystallized polygons averaged at 200 nm with well-developed layer structure. Due to the shorter diffusion pathways and the larger surface area, the discharge capacity of this sample maintains 97 mAh/g in the 30th cycle at charge-discharge rate of 30 C, which is corresponding to a current density of about 15 mA/cm(2). As to the LiCoO2 sample heating at 800 degreesC and commercial LiCoO2, the slipped layer structure and the cracked particles were firstly observed after cycling at high charge-discharge rate. It indicates the surface of the particles was irreversibly destroyed, thus the capacity fast decreased. (C) 2004 Elsevier B.V. All rights reserved.