Modified lithium iron phosphate positive electrode material, preparation method and application thereof

Abstract

The application belongs to the technical field of battery preparation, and particularly relates to a preparation method and application of modified lithium iron phosphate positive electrode material, and the preparation method comprises the following steps: S1, mixing lithium iron phosphate positive electrode material, composite carbon source and water to prepare mixed slurry; the composite carbon source comprises glucose and porous graphene; S2, grinding and spray drying the mixed slurry to obtain composite powder; S3, calcining the composite powder to obtain modified lithium iron phosphate positive electrode material; the total mass of the composite carbon source in the step S1 is 2%-5% of the mass of the lithium iron phosphate positive electrode material, and the mass ratio of the porous graphene in the composite carbon source is 10%-30%. The positive electrode material has low resistivity, as low as 17.1 omega*cm, and good electrochemical performance.

Claims

1. A method for preparing a modified lithium iron phosphate cathode material, characterized in that, It includes: S1. A mixed slurry is prepared by mixing lithium iron phosphate cathode material, composite carbon source and water; the composite carbon source includes glucose and porous graphene. S2. The mixed slurry is ground and spray-dried to obtain composite powder; S3. The composite powder is calcined to obtain modified lithium iron phosphate cathode material; In step S1, the total mass of the composite carbon source is 2%-5% of the mass of the lithium iron phosphate cathode material, and the mass percentage of porous graphene in the composite carbon source is 10%-30%.

2. The preparation method according to claim 1, characterized in that, The mass percentage of porous graphene in the composite carbon source is 20%.

3. The preparation method according to claim 1 or 2, characterized in that, The porous graphene is one or both of ZBF-45 or ZBF-50.

4. The preparation method according to claim 1 or 2, characterized in that, In step S3, the calcination temperature is 700℃-900℃, the heating rate is 3℃ / min-5℃ / min, and the holding time is 3h-5h.

5. The preparation method according to claim 3, characterized in that, In step S3, the secondary calcination temperature is 700℃-900℃, the heating rate is 3℃ / min-5℃ / min, and the holding time is 3h-5h.

6. The preparation method according to claim 1, 2, or 5, characterized in that, The preparation method of lithium iron phosphate cathode material in step S1 satisfies one or more of the following conditions: The raw materials used in the preparation include lithium, iron, phosphorus, and carbon sources; The carbon source is glucose, which accounts for 2%-5% of the total mass. Lithium iron phosphate cathode material was obtained by calcination under inert gas protection.

7. A modified lithium iron phosphate cathode material, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 6.

8. A positive electrode for a lithium iron phosphate battery, characterized in that, It is prepared from the modified lithium iron phosphate cathode material as described in claim 7.

9. A lithium iron phosphate battery, characterized in that, Includes the lithium iron phosphate battery cathode as described in claim 8.

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