# US 9,437,868 B2 · Iron (III) orthophosphate-carbon composite

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- Number: US 9,437,868 B2
- Document ID: US9437868B2
- Status: Granted
- Kind: B2
- Application number: 13/981,369
- Filed: 2012-01-23
- Published: 2014-05-29
- Granted: 2016-09-06
- Earliest claimed: 2011-01-25
- Assignees: Chemische Fabrik Budenheim KG
- Applicants: Gunnar Buehler; Killian Schwarz; Andreas Jazdanian; Christian Graf; Michael Rapphahn
- Inventors: Gunnar Buehler; Killian Schwarz; Andreas Jazdanian; Christian Graf; Michael Rapphahn
- Web page: https://patentgrep.com/patent/US9437868B2

## CPC

- H01M 4/364: {as mixtures}
- B82Y 30/00: Nanotechnology for materials or surface science, e.g. nanocomposites
- C01B 25/375: {of iron}
- C01B 25/45: containing plural metal, or metal and ammonium
- H01M 4/131: Electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
- H01M 4/1391: of electrodes based on mixed oxides or hydroxides, or on mixtures of oxides or hydroxides, e.g. LiCoOx
- H01M 4/5825: {Oxygenated metallic salts or polyanionic structures, e.g. borates, phosphates, silicates, olivines}
- H01M 4/625: {Carbon or graphite}
- H01M 10/0525: Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
- C01P 2002/72: by d-values or two theta-values, e.g. as X-ray diagram
- C01P 2002/85: by XPS, EDX or EDAX data
- C01P 2004/03: obtained by SEM
- C01P 2004/62: Submicrometer sized, i.e. from 0.1-1 micrometer
- C01P 2004/64: Nanometer sized, i.e. from 1-100 nanometer
- C01P 2006/12: Surface area
- C01P 2006/40: Electric properties
- Y02E 60/10: Energy storage using batteries
- Y02P 70/50: Manufacturing or production processes characterised by the final manufactured product
- H01M: PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
- B82Y: SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- C01P: INDEXING SCHEME RELATING TO STRUCTURAL AND PHYSICAL ASPECTS OF SOLID INORGANIC COMPOUNDS
- Y02E: REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS

## Abstract

A method for producing an iron(III)orthophosphate-carbon composite which contains iron(III)orthophosphate of the general formula FePO4×nH2O (n≦2.5), a carbon source being dispersed in a phosphoric aqueous Fe2+ ion-containing solution and orthophosphate-carbon composite being precipitated and removed from the aqueous solution when an oxidant is added to the dispersion.

## Claims

### Claim 1

A method for the production of an iron(III) orthophosphate-carbon composite that contains iron(III) orthophosphate-carbon composite that contains iron(III) orthophosphate of the general formula FePO4×nH2O (n<2.5) comprising: dispersing a carbon source in a phosphoric acid aqueous Fe2+ ion-containing aqueous solution to obtain a dispersion, wherein the aqueous Fe2+ ion-containing solution is prepared by adding iron(II), iron(III) or mixed iron(II,III) compounds, selected from the group consisting of hydroxides, oxides, oxide-hydroxides, hydrated oxides, carbonates, hydroxide carbonates and mixtures thereof, together with elementary iron, to a phosphoric acid-containing aqueous medium to bring Fe2+ ions into solution and to convert Fe3+ with the elementary Fe, by a comproportionation reaction, to Fe2+ and then separating solids from the phosphoric acid aqueous Fe2+solution, adding an oxidizing agent to the dispersion to precipitate the iron(III) orthophosphate-carbon composite from the aqueous solution, and separating the iron(III) orthophosphate-carbon composite precipitate from the aqueous solution, wherein the iron(III) orthophosphate-carbon composite contains iron(III) orthophosphate of the general formula FePO4×nH2O (n<2.5).

### Claim 2 (depends on 1)

A method according to claim 1 wherein the aqueous Fe2+ ion-containing solution is prepared by adding iron(II), iron(III) or mixed iron(II,III) compounds, selected from the group consisting of hydroxides, oxides, oxide-hydroxides, hydrated oxides, carbonates, hydroxide carbonates and mixtures thereof, together with elementary iron, to a phosphoric acid-containing aqueous medium to bring Fe2+ ions into solution and to convert Fe3+ with the elementary Fe, by a comproportionation reaction, to Fe2+ and then separating solids from the phosphoric acid aqueous Fe2+ solution.

### Claim 3 (depends on 1)

A method according to claim 1 wherein the carbon source comprises elementary carbon selected from the group consisting of graphite, expanded graphite, soots, carbon black, smoke black carbon nanotubes (CNT), fullerenes, graphene, glassy carbon, carbon fibres, activated charcoal and mixtures thereof.

### Claim 4 (depends on 1)

A method according to claim 1 wherein the carbon source is elementary carbon and carbon compound.

### Claim 5 (depends on 1)

A method according to claim 1 wherein the carbon source comprises elementary carbon and organic carbon compound selected from the group consisting of hydrocarbons, alcohols, aldehydes, carboxylic acids, surfactants, oligomers, polymers, carbohydrates and mixtures thereof.

### Claim 6 (depends on 1)

A method according to claim 1 wherein the dispersion of the carbon source in the phosphoric acid aqueous Fe2+ ion-containing solution contains the carbon source in an amount of 1 to 10 wt. % carbon by weight of precipitated iron(III) orthophosphate.

### Claim 7 (depends on 1)

A method according to claim 1 wherein the dispersion of the carbon source in the phosphoric acid aqueous Fe2+ ion-containing solution contains the carbon source in an amount of 1.5 to 5 wt. % carbon by weight of precipitated iron(III) orthophosphate.

### Claim 8 (depends on 1)

A method according to claim 1 wherein the dispersion of the carbon source in the phosphoric acid aqueous Fe2+ ion-containing solution contains the carbon source in an amount of 1.8 to 4 wt. % carbon by weight of precipitated iron(III) orthophosphate.

### Claim 9 (depends on 6)

A method of claim 6 wherein the carbon source is an electrically conductive carbon source.

### Claim 10 (depends on 1)

A method according to claim 1 wherein the phosphoric acid aqueous Fe2+ ion-containing solution used for the preparation of the dispersion contains the Fe2+ ions in a concentration of 0.8 to 2.0 mol/l.

### Claim 11 (depends on 1)

A method according to claim 1 wherein the phosphoric acid aqueous Fe2+ ion-containing solution used for the preparation of the dispersion contains the Fe2+ ions in a concentration of 1.0 to 1.7 mol/l.

### Claim 12 (depends on 1)

A method according to claim 1 wherein the phosphoric acid aqueous Fe2+ ion-containing solution used for the preparation of the dispersion
n contains the Fe2+ ions in a concentration of 1.1 to 1.3 mol/l.

### Claim 13 (depends on 1)

A method according to claim 1 wherein the phosphoric acid aqueous Fe2+ ion-containing solution used for the preparation of the dispersion has a pH in the range from 1.5 to 2.5.

### Claim 14 (depends on 1)

A method according to claim 1 wherein the phosphoric acid aqueous Fe2+ ion-containing solution used for the preparation of the dispersion has a pH in the range from 1.8 to 2.3.

### Claim 15 (depends on 1)

A method according to claim 1 wherein the phosphoric acid aqueous Fe2+ ion-containing solution used for the preparation of the dispersion has a pH in the range from 2.0 to 2.1.

### Claim 16 (depends on 1)

A method according to claim 1 wherein the oxidizing agent that is added to the dispersion is an aqueous solution of hydrogen peroxide, air, oxygen or ozone.

### Claim 17 (depends on 1)

A method according to claim 1 wherein the iron(III) orthophosphate-carbon composite is washed after the precipitation and separation of the aqueous solution.

### Claim 18 (depends on 17)

A method according to claim 17 wherein the washed precipitate is dried.

### Claim 19 (depends on 17)

A method according to claim 17 wherein the washed precipitate is dispersed in an aqueous liquid with solids content of 1 to 90 weight percent.

### Claim 20

Iron(III) orthophosphate-carbon composite produced according to a method comprising:
dispersing a carbon source in a phosphoric acid aqueous Fe2+ ion-containing aqueous solution to obtain a dispersion,wherein the aqueous Fe2+ ion-containing solution is prepared by adding iron (II), iron (III) or mixed iron (II,III) compounds, selected from the group consisting of hydroxides, oxides, oxide-hydroxides, hydrated oxides, carbonates, hydroxide carbonates and mixtures thereof, together with elementary iron, to a phosphoric acid-containing aqueous medium to bring Fe2+ ions into solution and to convert Fe3+ with the elementary Fe, by a comproportionation reaction, to Fe2+ and then separating solids from the phosphoric acid aqueous Fe2+ solution,
adding an oxidizing agent to the dispersion to precipitate the iron(III) orthophosphate-carbon composite from the aqueous solution, and
separating the iron(III) orthophosphate-carbon composite precipitate from the aqueous solution,
wherein the iron(III) orthophosphate-carbon composite contains iron(III) orthophosphate of the general formula FePO4×nH2O (n≦2.5).

### Claim 21 (depends on 20)

Iron(III) orthophosphate-carbon composite produced according to the method of claim 20 wherein the dispersion of the carbon source in the phosphoric acid aqueous Fe2+ ion-containing solution contains the carbon source in an amount of 1.5 to 5 wt. % carbon by weight of precipitated iron(III) orthophosphate.

### Claim 22 (depends on 20)

An Iron(III) orthophosphate-carbon composite produced according to the method of claim 20 containing from 1.5 to 5 weight percent of electrically conductive carbon wherein greater than 80 weight percent is present in the metastrengite II crystal structure.

### Claim 23 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein greater than 90 weight percent is present in the metastrengite II crystal structure.

### Claim 24 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein greater than 80 weight percent is present in the metastrengite II crystal structure.

### Claim 25 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein the iron(III) orthophosphate-carbon composite has a mean particle size of less than 500 nm in at least one dimension.

### Claim 26 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein the iron(III) orthophosphate-carbon composite has a mean particle size of less than 300 nm in at least one dimension.

### Claim 27 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein the iron(III) orthophosphate-carbon composite has a mean particle size of less than 100 nm in at least one dimension.

### Claim 28 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein it has a bulk density >400 g/l.

### Claim 29 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein it has a bulk density >700 g/l.

### Claim 30 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein it has a bulk density >1000 g/l.

### Claim 31 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein it has a compacted bulk density >600 g/l.

### Claim 32 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein it has a compacted bulk density >750 g/l.

### Claim 33 (depends on 20)

Iron(III) orthophosphate-carbon composite according to claim 20 wherein it has a compacted bulk density >1100 g/l.

### Claim 34 (depends on 20)

A method for producing LiFePO4 carbon composite material by converting iron(III) orthophosphate-carbon composite of claim 20.

### Claim 35 (depends on 20)

A LiFePO4 cathode material for Li-ion batteries, produced using iron(III) orthophosphate-carbon composite of claim 20.

### Claim 36 (depends on 35)

A Li-ion battery, containing a LiFePO4 cathode material according to claim 35.