Preparation method of graphene-based lithium iron phosphate positive electrode material

Abstract

The invention discloses a preparation method of a graphene-based lithium iron phosphate positive electrode material, and belongs to the technical field of manufacturing of power type lithium ion batteries. The preparation method comprises the following steps: by using graphene oxide as a graphene source, uniformly mixing the graphene oxide with an iron source solution for preparing iron phosphate in the preparation process of iron phosphate, carrying out a co-precipitation reaction with phosphoric acid, ammonium phosphate or ammonium dihydrogen phosphate, washing, filtering and drying a reaction product, and then calcining and grinding to prepare the graphene oxide-iron phosphate composite material; the preparation method comprises the following steps: taking graphene as an iron source for producing a lithium iron phosphate positive electrode material, grinding and uniformly dispersing the iron source, lithium carbonate and glucose in a ball mill, drying to prepare a precursor of lithium iron phosphate, pre-sintering for 3-6 hours at 250-500 DEG C in a reducing atmosphere of H2 / Ar / N2 and the like, heating to 600-800 DEG C, continuously sintering for 6-12 hours, and cooling along with a furnace to obtain the graphene-based lithium iron phosphate positive electrode material. According to the preparation method, the dispersity and uniformity of graphene in the positive electrode material can be improved, and the defect that graphene is difficult to disperse in water in the preparation process of the positive electrode material is overcome.

Description

technical field [0001] The invention relates to a preparation method of a graphene-based lithium iron phosphate cathode material, which is used in the technical field of manufacturing power lithium ion batteries. Background technique [0002] With the expansion of lithium-ion batteries in practical applications, the performance of cathode materials directly determines the development of lithium-ion batteries. LiFePO with olivine structure 4 Cathode materials, due to the wide source of raw materials, low price, environmental friendliness, high specific capacity and voltage platform, have gradually become the protagonists of lithium-ion battery cathode materials. Compared with other cathode materials, LiFePO 4 It has relatively high safety and is more suitable as a power source for large power batteries. But LiFePO 4 As the application of large-scale power ion battery materials, there are still the following problems to be solved: [0003] 1) LiFePO 4 The electronic cond...

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Problems solved by technology

[0003] 1) LiFePO 4 The electronic conductivity of (10 -9 S / cm) is low, much smaller than LiCoO 2 (10 -3 S / cm) and LiMnO 2 (10 - 5 S / cm) conductivity, which seriously affects the diffusion of lithium ions

[0004] 2) In LiFePO 4 In the process of preparation and synthesis, it is easy to produce Fe 2+ Oxidation of the active material reduces the mass of the effective active material, resulting in high irreversible capacity and poor cycle performance of the material.

[0005] 3) Industrial production is mainly based on the solid phase method. The disadvantage of this method is that the prepared material has a large particle size and uneven shape, which is not conducive to the infiltration of the electrolyte and the diffusion of lithium ions.

However, these studies are limited to the use of graphene as a raw material, which is added when the lithium iron phosphate cathode material is used to prepare the precursor, which cannot solve the problems inherent in the production of graphene products, such as complex preparation processes, high energy consumption, and difficulty in dispersing in the precursor.

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