The study on the effect of hydrothermal temperature on the structure and characteristics of olivine LiCoPO4 cathode materials

Abstract

The experiment was conducted to research and fabricate single phase olivine LiCoPO₄ materials with nano-meter structure by hydrothermal method at different temperatures of 190^oC, 200^oC and 240^oC. Methods of determining the structure and characteristics of materials include: XRD, FTIR, SEM. The ion conductivity of the LiCoPO₄ powder materials suspension was measured on a conductivity meter (Hana Instruments HI2314). The results showed that, when the hydrothermal temperature increased from 190-240^oC, the crystal formation and development gradually increased. The average crystal sizes of the samples were about 23.04 nm, 25.75 nm and 30.19 nm which were gradual increase with hydrothermal temperature. The wave vibrations in the FTIR spectra showed the bounding vibrations of the O-P-O that were of the tetrahedron PO₄^3- and bonding vibrations of metal-O. The ionic conductivity of the olivine LiCoPO₄ powder samples suspension increases when the hydrothermal temperature of samples increases of 190, 200 and 240^oC. The maximum electrical conductivity was ~39.4 mS/cm obtained by olivine LiCoPO₄ sample which was hydrothermal at 200^oC.