Lithium ion battery composite cathode material and preparation method thereof

Abstract

The invention relates to a lithium ion battery composite cathode material which is characterized by being prepared from powder which is formed by uniformly coating amorphous carbon on the surfaces ofin situ composite Li3V2(PO4)3 and LiFePO4, wherein the powder contains the components in percentage by weight: 75.0-74.0 percent of LiFePO4, 21.8-21.8 percent of Li3V2(PO4)3 and 2.3-4.8 percent of amorphous carbon. A preparation process of the composite cathode material adopts a carbothermic reduction solid phase sintering method which comprises the following steps: mixing raw materials of FePO4,Li2CO3, NH4H2PO4 and NH4VO3 according to a stoichiometric ratio; adding petroleum coke accounting for 15-25 percent of the total weight of the raw materials; and after adding acetone to ball mill andmix the raw materials on a ball milling machine, and calcining the raw materials in argon atmosphere at 600-700 DEG C for 8-12 hours. When used as a cathode of a lithium ion battery, the composite cathode material has the advantages of simple preparation method, high charge and discharge capacity, good performance of high multiplying power charge and discharge, good cyclical stability, and the like.

Description

technical field

[0001] The invention relates to a lithium ion battery composite cathode material and a preparation method thereof. Background technique

[0002] Compared with traditional secondary batteries, lithium-ion batteries have the advantages of high platform voltage (about 3.2-3.7V), high energy density, and no memory effect. They are widely used in mobile phones, cameras, notebook computers, and portable appliances, especially It is LiFePO with olivine structure 4 Lithium-ion batteries with positive electrode materials are rich in electrode material resources, environmentally friendly, low in price, and stable in discharge platform (3.45V, vs. Li / Li + ), good cycle performance and high overcharge safety, it is very suitable as a power battery for transportation and vehicles. However, due to LiFePO 4 Has a slightly twisted hexagonal closest-packed structure, belongs to the Pnma space group, and the crystal is composed of MO 6 Octahedron and PO 4 The tetrahedrons...