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Method for preparing sub-micrometer lithium iron phosphate (LiFePO4)

A lithium iron phosphate, sub-micron technology, applied in chemical instruments and methods, phosphorus compounds, inorganic chemistry, etc., can solve the problems of increased lithium iron phosphate trivalent iron content, danger, difficulty in process operation, etc., to achieve environmental benefits. protection, excellent electrochemical performance, and the effect of improving economic efficiency

Active Publication Date: 2010-11-24
CHENGDU CHEMPHYS CHEM IND
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Publication Nos. CN101007630, CN101117216, CN101121509 and other invention patents all adopt the hydrothermal or solvothermal method to prepare lithium iron phosphate, mainly using lithium hydroxide, ferrous sulfate, and phosphoric acid as raw materials. The common problems in these methods are: (1) The use of high-temperature and high-pressure equipment in the reaction process increases the investment cost of the equipment, and brings certain difficulties and dangers to the process operation; (2) the possibility of forming iron hydroxide and ferric iron is increased during the reaction, resulting in the production of lithium iron phosphate The increase of ferric iron content will bring harm to the electrochemical performance of the material
(3) The use of excessive and expensive lithium-containing raw materials (Li:Fe:P molar ratio is 3.0-3.15:1:1.0-1.15) requires additional subsequent lithium recovery processes, increasing industrial production costs

Method used

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  • Method for preparing sub-micrometer lithium iron phosphate (LiFePO4)
  • Method for preparing sub-micrometer lithium iron phosphate (LiFePO4)
  • Method for preparing sub-micrometer lithium iron phosphate (LiFePO4)

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0037] In this example, LiFePO 4 and LiFePO 4 The processing steps of the / C preparation method are as follows:

[0038] (1) Ingredients to synthesize LiFePO 4

[0039] Iron source: FeSO 4 ·7H 2 O 55.61 grams or 0.2 mol of iron;

[0040] Phosphorus source: (NH 4 ) 2 HPO 4 26.40 grams or 0.2 mol of phosphorus;

[0041] Lithium source: LiOH·H 2 O 7.98 grams or lithium 0.19mol;

[0042] Compounds containing dopant ions: NH 4 VO 3 1.17 grams is the doping ion vanadium 0.01mol

[0043] The operation is:

[0044] FeSO 4 ·7H 2 O plus 50mL deionized water to prepare iron source solution, LiOH·H 2 O adds 50mL deionized water to be mixed with lithium source solution, (NH 4 ) 2 HPO 4 and NH 4 VO 3 Add 150mL of deionized water to prepare phosphorus and doping ion source solution, then drop the phosphorus and doping ion source solution into the lithium source solution at room temperature, normal pressure, and stir, and then add the iron source solution to the lithium ...

Embodiment 2

[0050] In this example, LiFePO 4 and LiFePO 4 The processing steps of the / C preparation method are as follows:

[0051] (1) Ingredients to synthesize LiFePO 4

[0052] Iron source: FeSO 4 ·7H 2 O 55.61 grams or 0.2 mol of iron;

[0053] Phosphorus source: (NH 4 ) 2 HPO 4 26.40 grams or 0.2 mol of phosphorus;

[0054] Lithium source: LiOH·H 2 O 7.55 grams or lithium 0.18mol;

[0055] Compounds containing dopant ions: MgSO 4 · 7H204.94g is doped ion magnesium 0.02mol

[0056] Organic solvent: ethylene glycol 200mL.

[0057] The operation is basically the same as that of Example 1, except that the timing is started when the reaction temperature reaches 190° C., and the temperature is kept at 190° C. for 10 hours.

[0058] (2) Calcination

[0059] The LiFePO prepared in step (1) 4 Weigh 20 grams, add 2 grams of sucrose, and use a ball mill to grind LiFePO 4 Mix well with sucrose, then LiFePO 4 The mixture with sucrose was placed in a tube furnace and heated to 6...

Embodiment 3

[0061] In this example, LiFePO 4 and LiFePO 4 The processing steps of the / C preparation method are as follows:

[0062] (1) Ingredients to synthesize LiFePO 4

[0063] Iron source: Fe(Ac) 2 4H 2 O 46.74 grams or iron 0.19mol;

[0064] Phosphorus and lithium sources: LiH 2 PO 4 10.393 grams, that is, 0.2 mol of phosphorus and 0.2 mol of lithium;

[0065] Compounds containing dopant ions: Mn(Ac) 2 4H 2 O 2.45 grams that is doped ion manganese 0.01mol

[0066] Organic solvent: tetraethylene glycol 250mL.

[0067] The operation is:

[0068] Fe(Ac) 2 4H 2 O and Mn(Ac) 2 4H 2 O is added 50mL deionized water to prepare iron source and doping ion source solution, LiH 2 PO 4 Add 100mL deionized water to be mixed with lithium source solution, iron source-doping ion source solution and lithium source solution are added in 250mL tetraethylene glycol under stirring to form the mixed solution containing lithium, iron, phosphorus and dopant ion; The stirring speed was set...

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Abstract

The invention discloses a method for preparing sub-micrometer lithium iron phosphate (LiFePO4). The method comprises the following steps of: mixing an iron source, a lithium source, a phosphorous source and a doping ion-containing compound according to a molar ratio of (lithium + doping ions) to iron to phosphorus of 1:1:1, or a molar ratio of lithium to (iron + doping ions) to phosphorus of 1:1:1, and then adding the mixture into an organic solvent, wherein the mole ratio of the doping ions to the phosphorus is 0.01-0.15:1, and the solid-to-liquid ratio after the reaction generates a precipitate is 1:10-1:2; reacting at a constant temperature of between 190 and 320 DEG C under the normal temperature to prepare a LiFePO4 material of which the particle diameter is 0.1 to 0.9 mu m; mixing the LiFePO4 powder material and an organic carbon source; after ball milling and uniform mixing, putting the mixture into a calcining furnace and heating the mixture under the protection of an inert gas and maintaining the temperature; and cooling the mixture to the room temperature to obtain a LiFePO4 / C cathode material of which the surface is wrapped with carbon and the particle diameter is 0.1 to 0.9 mu m. In the method of the invention, normal-pressure equipment can be used, and energy consumption is saved and the cost is low.

Description

Technical field: [0001] The invention belongs to lithium iron phosphate (LiFePO 4 ) preparation field, especially a kind of LiFePO prepared in an organic solvent under normal pressure with a particle size of 0.1-0.9 μm, a spherical shape, and an olivine crystal structure. 4 , and then doped with carbon to prepare LiFePO 4 / C's submicron lithium iron phosphate preparation method. Background technique: [0002] Due to the increasingly prominent environmental and energy issues, the development of hybrid and pure electric vehicles has received widespread attention. The key to the development of hybrid and pure electric vehicles lies in power batteries, and the key to successful power battery technology lies in battery materials. In recent years, Power lithium-ion battery materials are also constantly improving, and the representative of its positive electrode material is lithium manganese oxide. Lithium iron phosphate (LiFePO 4 ) due to its excellent thermal stability, high ...

Claims

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Application Information

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IPC IPC(8): C01B25/45
Inventor 蔡荣富刘恒刘建
Owner CHENGDU CHEMPHYS CHEM IND
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