Preparation And Electrochemical Performance Of LiFePO₄/C Composite Material As Cathode Materials For Lithium-Ion Batteries

In 21 century, with the rapid development of science technology and the environmental degradation problems highlighted increasingly, there is an increasing demand for power battery, so that put forward higher requirements on the performance of the battery materials.Olivine-type LiFePO₄ such as with low cost, environmentally friendly, low self-discharge rate and excellent electrochemical performance and many other advantages, is considered to be one of the most potential of lithium-ion battery materials. However, due to limitations of its own structure of pure lithium ion phosphate ion conductivity and electronic conductivity rate is not high, and lead to its actual capacity is far less than the theoretical capacity, and poor electrochemical performance under high magnification, thereby limiting the lithium iron phosphate materials in the field of hybrid battery application. At present, by reducing the particle size of the material, control the morphology and the coated conductive material and other methods to improve the electrochemical properties of lithium iron phosphate material.The paper adopts the electrostatic spinning technology preparation of LiFePO₄/C nanometer materials. The polyacrylonitrile precursor solution studied solubility and spinning process of spinning temperature effect on the properties of materials morphology and electrochemical, using X-ray diffraction, scanning electron microscope（sem） for morphology characterization of materials;Constant current charge-discharge test, cyclic voltammetric and ac impedance testing of materials for electrochemical performance characterization.Results show that the optimal parameters under the condition of the preparation of material, under 0.1C ratio, the initial discharge capacity of 97.8 m Ah ? g^-1.Under the above basis, to study the adding oxidized graphene and carbon nanotubes of LiFePO₄/C effects of nanomaterials respectively. The results showed that adding oxidized graphene and carbon nanotubes are not change olivine LiFePO₄ crystal structure,advantageous to reduce the fiber diameter size, and more uniform distribution of fibers, the electrochemical properties was improved. LiFePO₄/C/GO discharge capacity of 118.4 m Ah ?g^-1 for the first time in 0.1 C rate. LiFePO₄/C/CNT discharge capacity of 116.2 m Ah ? g^-1 forthe first time in 0.1 C rate.