# US 8,541,338 B2 · Highly porous activated carbon with controlled oxygen content

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- Number: US 8,541,338 B2
- Document ID: US8541338B2
- Status: Granted
- Kind: B2
- Application number: 12/264,568
- Filed: 2008-11-04
- Published: 2010-05-06
- Granted: 2013-09-24
- Earliest claimed: 2008-11-04
- Assignees: Corning Incorporated
- Applicants: Kishor Purushottam Gadkaree; Jia Liu
- Inventors: Kishor Purushottam Gadkaree; Jia Liu
- Web page: https://patentgrep.com/patent/US8541338B2

## CPC

- B01J 20/20: comprising free carbon; comprising carbon obtained by carbonising processes
- C01B 32/336: characterised by gaseous activating agents
- C01B 32/342: characterised by non-gaseous activating agents
- H01G 11/34: characterised by carbonisation or activation of carbon
- B01J: CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
- C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C}
- H01G: CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE (selection of specified materials as dielectric H01B3/00; capacitors having potential barriers H10D1/62, H10K10/10)

## Abstract

Nanoporous activated carbon material having a high specific capacitance in EDLCs and controlled oxygen content, and methods for making such activated carbon material. Reduction of oxygen content is achieved by (a) curing a carbon precursor/additive mixture in an inert or reducing environment, and/or (b) refining (heating) activated carbon material after synthesis in an inert or reducing environment. The inert or reducing environment used for curing or refining is preferably substantially free of oxygen.

## Claims

### Claim 1

A method of forming a porous activated carbon material having controlled oxygen content, comprising:
forming a mixture of a carbon precursor selected from the group consisting of a synthetic polymer thermosetting resin and a synthetic polymer thermoplastic resin and an inorganic compound selected from the group consisting of KOH, K2CO3, KCl, NaOH, Na2CO3, NaCl, P2O5, AlCl3, MgCl2, ZnCl2 and H3PO4;
heating the mixture at a first temperature to cure the carbon precursor;
heating the cured carbon precursor at a second temperature higher than the first temperature to carbonize the carbon precursor and produce an activated carbon material, wherein the method further comprises:
(a) heating the mixture at the first temperature in a nitrogen environment, and
(b) washing the activated carbon to remove the inorganic compound and then heating the washed activated carbon material at a third temperature ranging from about 450° C. to 1000° C. in an environment that is substantially free of oxygen to refine the activated carbon material.

### Claim 2 (depends on 1)

The method according to claim 1, wherein the porous activated carbon material has an oxygen content of less than 10 wt. %.

### Claim 3 (depends on 1)

The method according to claim 1, wherein the carbon precursor is selected from the group consisting of phenolic resins, poly(vinyl alcohol), and polyacrylonitrile.

### Claim 4 (depends on 1)

The method according to claim 1, wherein step (a) or step (b) are both performed in an inert or reducing environment.

### Claim 5 (depends on 1)

The method according to claim 1, wherein heating at the first temperature comprises heating the mixture to a temperature in a range of about 100-300° C. for a period of about 1-48 hours.

### Claim 6 (depends on 1)

The method according to claim 1, wherein heating at the second temperature comprises heating the cured carbon precursor at a heating rate of about 10-600° C./hr to a temperature in a range of about 650-900° C. for a period of about 0.5-10 hours.

### Claim 7 (depends on 1)

The method according to claim 1, wherein heating at the third temperature comprises heating the activated carbon material at a heating rate of about 10-600° C./hr to a temperature in a range of about 450-1000° C. for a period of about 0.5-10 hours.

### Claim 8 (depends on 1)

The method according to claim 1, wherein the activated carbon material is exposed to a N2/water vapor purge prior to heating at the third temperature.

### Claim 9 (depends on 1)

The method according to claim 1, further comprising grinding the refined activated carbon material.