Preparation method for iron lithium phosphite anode material simultaneously doped with fluorine ion and metallic ion

Abstract

The invention provides a preparation method used for lithium iron phosphate anode material mixed with Fl ions and iron ions. In order to achieve the object, the technical proposal adopted by the invention is that reaction compositions consisting of lithium salt, ferrite, P2O5 or P2O3 and fluorinc source are weighed and uniformly mixed according to the mol ratio of x: y: z: k: m of Li ion, ferrous iron, P ion, Fl ion and mixed ion. Carbon compound or carbon powder, with the mass equal to 1 to 20 percent of that of lithium iron phosphate, which is calculated according to the mass of reaction matter, and wet grinding matter with the volume equal to 1 / 10 to 10 of that of the reaction mixture, are added into the mixture and ball-grinded for 3 to 15 hours under the rotation ranging from 100 to 1000 r / min, and are dried in vacuum condition under the pressure of 10 to 10132Pa and any temperature ranging from 70 to 120 DEG C. The dried powder is used for preparing the composite sample containing the mixing iron phosphate by a program temperature increasing-sintering method or a combination sintering method.

Description

technical field [0001] The invention belongs to the technical field of lithium ion battery electrode materials, and relates to a preparation method of a lithium iron phosphate cathode material that can be used for lithium ion batteries, lithium batteries, polymer lithium ion batteries and supercapacitors. technical background [0002] As a cathode material for lithium-ion batteries, lithium iron phosphate has the advantages of good safety, stable cycle performance, and low price. The theoretical discharge capacity can reach 170mA h / g, and it is an important candidate material for lithium-ion battery cathode materials. However, there are still many difficulties in applying lithium iron phosphate to lithium-ion batteries. For example, the material has low electronic conductivity, low ion conductivity, small tap density and true density, and poor low temperature performance. In order to overcome the deficiency of lithium iron phosphate, extensive research has been carried out ...

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Problems solved by technology

However, in the latter preparation method, only the research on simultaneous doping of fluorine and silicon or rare earth elements has been carried out, and the discharge voltage platform of the prepared product is relatively low, and the platform of the discharge voltage is near 3.4V. Lithium cobalt oxide and lithium manganese oxide cathode materials commonly used in batteries have a much lower discharge voltage platform. In the use of mobile electronic products, there are problems such as electronic adjustment difficulties or the need to modify the circuits of original electronic equipment.