Method for preparing lithium iron phosphate nanopowder

Patent metadata

Field	Value
Publication number	US-9543582-B2
Application number	US-201414510356-A
Country	US
Kind code	B2
Filing date	Oct 9, 2014
Priority date	Jan 10, 2013
Publication date	Jan 10, 2017
Grant date	Jan 10, 2017

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 triethanolamine solvent, and (b) putting the mixture solution into a reactor and heating to prepare the lithium iron phosphate nanopowder under pressure conditions of 1 bar to 10 bar, and a lithium iron phosphate nanopowder prepared by the method. When compared to a common hydrothermal synthesis method, a supercritical hydrothermal synthesis method and a glycothermal synthesis method, a reaction may be performed under a relatively lower pressure. Thus, a high temperature/high pressure reactor is not necessary and process safety and economic feasibility may be secured. In addition, a lithium iron phosphate nanopowder having uniform particle size and effectively controlled 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 triethanolamine solvent, which is a non-aqueous solvent; and
(b) putting the mixture solution into a reactor and heating to prepare the lithium iron phosphate nanopowder under pressure conditions of 1 bar to 10 bar and at a temperature range of 150 to 335° C.

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 1 , wherein the lithium iron phosphate nanopowder prepared in Step (b) is sequentially conducted a washing step and a drying step.

4. 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 triethanolamine solvent.

5. The method for preparing a lithium iron phosphate nanopowder of claim 1 , wherein Step (b) is performed for 1 to 72 hours.

6. 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), lithium oxalate (Li 2 C 2 O 4 ), and a mixture thereof.

7. The method for preparing a lithium iron phosphate nanopowder of claim 1 , 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), ferrous sulfate heptahydrate (FeSO 4 .7H 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.

8. 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.

9. 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.

10. The method for preparing a lithium iron phosphate nanopowder of claim 3 , wherein the drying is performed at 20° C. to 160° C. for 2 to 40 hours.

Assignees

• Lg Chemical Ltd

Inventors

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

Classifications

• H01M4/5825 Primary

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

• C01P2002/72

  by d-values or two theta-values, e.g. as X-ray diagram · CPC title

• H01M4/625

  Carbon or graphite · CPC title

• Y10T428/2982

  Particulate matter [e.g., sphere, flake, etc.] · CPC title

• H01M4/136

  Electrodes based on inorganic compounds other than oxides or hydroxides, e.g. sulfides, selenides, tellurides, halogenides or LiCoFy · CPC title