Lithium iron phosphate composite material, preparation method and use

Patent metadata

Field	Value
Publication number	US-2025304446-A1
Application number	US-202418719409-A
Country	US
Kind code	A1
Filing date	Jun 13, 2024
Priority date	Dec 16, 2021
Publication date	Oct 2, 2025
Grant date	—

Abstract

The present application provides a lithium iron phosphate composite material, a preparation method and use. The lithium iron phosphate composite material includes a core and a shell coated on the core, in particular, the core is Li 6 MnO 4 , and the shell is carbon-coated lithium iron phosphate. The lithium iron phosphate composite material provided by the present application adopts Li 6 MnO 4 as the positive electrode lithium supplement material, and solves problems of active lithium loss and capacity depletion under high-rate charge and discharge of lithium iron phosphate positive electrode, thereby improving the rate performance of the lithium iron phosphate materials and the cycle life of batteries at high rates.

First claim

What is claimed is:

1 . A preparation method for a lithium iron phosphate composite material, wherein the lithium iron phosphate composite material comprises a core and a shell coated on the core, the core is Li 6 MnO 4 , and the shell is carbon-coated lithium iron phosphate;
the preparation method for the lithium iron phosphate composite material comprises: preparing a carbon-coated lithium iron phosphate precursor sol is prepared by adopting a sol-gel process, mixing a Li 6 MnO 4 precursor and the carbon-coated lithium iron phosphate precursor sol under stirring until a solvent is completely evaporated to obtain a wet material, and calcining the wet material to obtain the lithium iron phosphate composite material.

2 . The preparation method according to claim 1 , wherein a mass ratio of the core to the shell is (0.005-0.05):1.

3 . The preparation method according to claim 1 , wherein a preparation process for the Li 6 MnO 4 precursor comprises:
weighing a manganese source and a first lithium source according to a stoichiometric ratio in Li 6 MnO 4 , respectively, mixing the manganese source and the first lithium source, ball milling and pre-calcining in sequence to obtain the Li 6 MnO 4 precursor.

4 . The preparation method according to claim 3 , wherein the first lithium source comprises any one or a combination of at least two selected from the group consisting of lithium hydroxide, lithium carbonate, lithium acetate, and lithium nitrate.

5 . The preparation method according to claim 3 , wherein the manganese source comprises any one or a combination of at least two selected from the group consisting of manganese hydroxide, manganese acetate, and manganese monoxide.

6 . The preparation method according to claim 3 , wherein the ball milling is performed at a rotation speed of 1000-3500 r/min, and the ball milling is performed for a period of 0.5 to 2 hours.

7 . The preparation method according to claim 3 , wherein the pre-calcining is performed at a temperature of 300-400° C., the pre-calcining is performed for a period of 1 to 3 hours, and the pre-calcining is performed in a nitrogen atmosphere or an argon atmosphere.

8 . The preparation method according to claim 1 , wherein a preparation process for the carbon-coated lithium iron phosphate precursor sol comprises:
mixing an iron source and a solvent, stirring and dispersing to obtain a dispersion solution, adding a carbon source, a chelating agent, a phosphorus source and a second lithium source under stirring, and warming for a period of time, to obtain the carbon-coated lithium iron phosphate precursor sol.

9 . The preparation method according to claim 8 , wherein the iron source comprises any one or a combination of at least two selected from the group consisting of ferric nitrate, ferrous sulfate and ferrous oxalate.

10 . The preparation method according to claim 8 , wherein the solvent comprises deionized water.

11 . The preparation method according to claim 8 , wherein the carbon source comprises any one or a combination of at least two selected from the group consisting of glucose, sucrose, and polyethylene glycol.

12 . The preparation method according to claim 8 , wherein the chelating agent comprises polyethylene glycol and/or citric acid.

13 . The preparation method according to claim 8 , wherein the phosphorus source comprises any one or a combination of at least two selected from the group consisting of lithium dihydrogen phosphate, ammonium dihydrogen phosphate, and diammonium hydrogen phosphate.

14 . The preparation method according to claim 8 , wherein the second lithium source comprises any one or a combination of at least two selected from the group consisting of lithium hydroxide, lithium acetate, lithium nitrate, and lithium dihydrogen phosphate.

15 . The preparation method according to claim 8 , wherein a molar ratio of Li element in the second lithium source, to Fe element in the iron source, to P element in the phosphorus source is (1.001-1.01):1:1.

16 . The preparation method according to claim 8 , wherein a mass ratio of a total of the second lithium source, the iron source and the phosphorus source to the carbon source is 1:(0.01-0.05).

17 . The preparation method according to claim 8 , wherein a mass ratio of a total of the second lithium source, the iron source and the phosphorus source to the chelating agent is 1:(0.01-0.05).

18 . The preparation method according to claim 8 , wherein a temperature for the warming is 50-70° C., and the period of time for the warming is 5 to 10 hours.

19 . The preparation method according to claim 1 , wherein the mixing and stirring are performed at a temperature of 70-90° C.

20 . The preparation method according to claim 1 , wherein the calcining is a gradient calcining, a process of the gradient calcining comprises:
heating materials to a temperature of T 1 and maintaining the temperature of T 1 for a period of time H 1 , and then heating materials to a temperature of T 2 and maintaining the temperature of T 2 for a period of time H 2 , wherein the T 1 is 350-390° C. the H 1 is 12 to 25 minutes, the T 2 is 600-770° C. and the H 2 is 0.5-5h.

Assignees

• Svolt Energy Tech Co Ltd

Inventors

• Wan Ning
• Yang Hongxin
• Liu Jing

Classifications

• C01P2006/40

  Electric properties · CPC title

• C01P2004/84

  one phase coated with the other · CPC title

• C01P2004/04

  obtained by TEM, STEM, STM or AFM · CPC title

• C01P2004/03

  obtained by SEM · CPC title

• C01G45/1214

  containing alkali metals · CPC title