Analysis of high rate performance of nanoparticled lithium cobalt oxides prepared in molten KNO 3 for rechargeable lithium-ion batteries

Abstract

Nanoparticled lithium cobalt oxides (LiCoO 2) were easily prepared using low-melting KNO 3 as reaction media and investigated using X-ray diffraction (XRD), scanning electron microscope (SEM) and galvanostatic charge–discharge cycling. The LiCoO 2 sample heating at 700 °C 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 LiCoO 2 sample heating at 800 °C and commercial LiCoO 2, 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.