Crystal structure and lithium electrochemical extraction properties of olivine type LiFePO4

Highlights: → Carbon gel has an important influence on the electrochemical properties of the LiFePO4 materials. → By using the carbon gel, the lithium ion diffusion was enhanced due to the increase of the Li-O interatomic distance and the cross section area of the lithium ion one-dimension tunnel. → In addition, the electric conductivity was obviously increased due to the small grains and good grain contact. - Abstract: Lithium iron phosphate (LiFePO4) cathode material has been synthesized by a solid-state reaction. The XRD patterns and SEM images of the samples show that the LiFePO4 compounds prepared at 650 deg. C by using carbon gel in reaction have a single-phase, small grain-size and regular shapes. By using Rietveld refinement method, we calculated the Li-O interatomic distance in LiO6 octahedra and the cross section area of the lithium ion one-dimension tunnel, and analyze the reason of the improvement of the Lithium ion diffusion. The electrochemical test results of the sample show the LiFePO4 prepared by using carbon gel exhibits excellent electrochemical properties. Such a significant improvement in electrochemical performance should be partly related to the enhanced Lithium ion diffusion and electric conductivity due to the use of carbon gel.