Method for preparing lithium iron phosphate nanopowder

Patent metadata

Field	Value
Publication number	US-10581076-B2
Application number	US-201414510495-A
Country	US
Kind code	B2
Filing date	Oct 9, 2014
Priority date	Jan 10, 2013
Publication date	Mar 3, 2020
Grant date	Mar 3, 2020

Abstract

The present invention relates to a method for preparing a lithium iron phosphate nanopowder, including the steps of (a) preparing a mixture solution by adding a lithium precursor, an iron precursor and a phosphorus precursor in a glycerol solvent, and (b) putting the mixture solution into a reactor and heating to prepare the lithium iron phosphate nanopowder under pressure conditions of 10 bar to 100 bar, and a lithium iron phosphate nanopowder prepared by the method. When compared to a common hydrothermal synthesis method and a supercritical hydrothermal synthesis method, a reaction may be performed under a relatively lower pressure. When compared to a common glycothermal synthesis method, a lithium iron phosphate nanopowder having effectively controlled particle size and particle size distribution may be easily prepared.

First claim

What is claimed is:

1. A method for preparing a lithium iron phosphate nanopowder, comprising the steps of:
(a) preparing a mixture solution by adding a lithium precursor, an iron precursor and a phosphorus precursor in a solvent; and
(b) putting the mixture solution into a reactor and heating to prepare the lithium iron phosphate nanopowder under pressure conditions of 10 bar to 100 bar,
wherein the solvent is non-aqueous, and the solvent is glycerol only,
wherein the iron precursor is at least one selected from the group consisting of iron citrate (FeC 6 H 5 O 7 ), iron citrate hydrate (FeC 6 H 5 O 7 .nH 2 O), iron(II) oxalate dihydrate (FeC 2 O 4 .2H 2 O), iron acetyl acetonate (Fe(C 5 H 7 O 2 ) 3 ), iron phosphate dihydrate (FePO 4 .2H 2 O), ferric hydroxide (FeO(OH)), and a mixture thereof,
wherein a mixing ratio of the lithium precursor, the iron precursor and the phosphorus precursor in step (a) is 0.1-1:1:0.1-1 by a molar ratio, and
wherein a particle diameter of the lithium iron phosphate nanopowder is from 30 nm to 300 nm.

2. The method for preparing a lithium iron phosphate nanopowder of claim 1 , further comprising the step of (c) heat treating the lithium iron phosphate nanopowder thus prepared to form a coating layer at a portion or a whole of a surface of an individual particle of the nanopowder.

3. The method for preparing a lithium iron phosphate nanopowder of claim 2 , wherein the heat treating is performed by heating to a temperature range of 400° C. to 900° C.

4. The method for preparing a lithium iron phosphate nanopowder of claim 1 , wherein the lithium iron phosphate nanopowder prepared in Step (b) is sequentially conducted a washing step and a drying step.

5. The method for preparing a lithium iron phosphate nanopowder of claim 4 , wherein the drying is performed at 20° C. to 160° C. for 2 to 40 hours.

6. The method for preparing a lithium iron phosphate nanopowder of claim 1 , wherein Step (b) is performed at a temperature less than or equal to a boiling point of the glycerol solvent.

7. The method for preparing a lithium iron phosphate nanopowder of claim 1 , wherein Step (b) is performed at a temperature range of 150° C. to 290° C.

8. The method for preparing a lithium iron phosphate nanopowder of claim 1 , wherein Step (b) is performed for 1 to 48 hours.

9. The method for preparing a lithium iron phosphate nanopowder of claim 1 , wherein the lithium precursor is at least one selected from the group consisting of lithium acetate dihydrate (CH 3 COOLi.2H 2 O), lithium hydroxide monohydrate (LiOH.H 2 O), lithium hydroxide (LiOH), lithium carbonate (Li 2 CO 3 ), lithium phosphate (Li 3 PO 4 ), lithium phosphate dodecahydrate (Li 3 PO 4 .12H 2 O) and lithium oxalate (Li 2 C 2 O 4 ), or a mixture thereof.

10. The method for preparing a lithium iron phosphate nanopowder of claim 1 , wherein the phosphorus precursor is at least one selected from the group consisting of tri-ammonium phosphate trihydrate ((NH 4 ) 3 PO 4 .3H 2 O), ammonium phosphate ((NH 4 ) 2 HPO 4 ), ammonium dihydrogen phosphate (NH 4 H 2 PO 4 ), phosphoric acid (H 3 PO 4 ), and a mixture thereof.

Assignees

• Lg Chemical Ltd

Inventors

• Jun In Kook
• Cho Seung Beom
• Oh Myoung Hwan

Classifications

• C01G49/009

  Compounds containing iron, with or without oxygen or hydrogen, and containing two or more other elements · CPC title

• H01M4/587

  for inserting or intercalating light metals · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• H01M4/5825 Primary

  Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines · CPC title

• H01M4/366

  as layered products · CPC title