Carbon aerogels for supercapacitors and method of manufacturing the same

• US 8,480,930 B2
• Filed: 10/09/2008
• Issued: 07/09/2013
• Est. Priority Date: 10/30/2007
• Status: Expired due to Fees

• Current Assignee: Korea Advanced Institute of Science and Technology
• Original Assignee: Korea Advanced Institute of Science and Technology
• Inventors: Suh, Dong Jin, Park, Tae Jin, Suh, Young-Woong, Yoon, Young Hyun, Kim, Hyun-Joong
• Primary Examiner(s): Nguyen, Khanh Tuan
• Application Number:
  US12/740,606
• Publication Number:
  US 20100310847A1
• Time in Patent Office: 1,734 Days
• Field of Search: 252/511, 252/519.1, 252/502, 429/40, 429/53, 502/418, 502/402, 502/416, 521/53, 521/97, 428/220, 516/111
• US Class Current: 252/502
• CPC Class Codes: B01J 13/0091 Preparation of aerogels, e.g. xerogels
• CPC Class Codes: C01B 32/05 Preparation or purification of carbon not covered by groups C01B32/15, C01B32/20, C01B32/25, C01B32/30
• CPC Class Codes: C04B 35/52 based on carbon, e.g. graphite
• CPC Class Codes: C04B 35/524 obtained from polymer precursors, e.g. glass-like carbon material
• CPC Class Codes: C04B 35/62655 Drying, e.g. freeze-drying, spray-drying, microwave or supercritical drying
• CPC Class Codes: C04B 38/00 Porous mortars, concrete, artificial stone or ceramic ware; Preparation thereof treating slag with gases or gas generating material C04B5/06 ; expanded graphite C04B35/536
• CPC Class Codes: H01G 11/32 Carbon-based
• CPC Class Codes: H01G 11/34 characterised by carbonisation or activation of carbon
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors
• CPC Class Codes: Y02P 20/10 Process efficiency

Abstract

A method for preparing carbon aerogels and carbon aerogels obtained therefrom are disclosed. The method for preparing carbon aerogels comprises: mixing organic starting materials including phloroglucinol and furfural with a solvent capable of dissolving the organic materials in a predetermined ratio to form a sol solution; adjusting pH of the sol solution adequately by using an acidic or basic catalyst, gelling the sol solution at room temperature under atmospheric pressure, and aging the resultant gels; substituting the solvent in thus obtained gels with liquid carbon dioxide, followed by drying in a supercritical state, to form organic aerogels; and pyrolyzing the organic aerogels in an electric furnace under inert atmosphere to obtain carbon aerogels. Particularly, the gels are formed at room temperature in a short period of time by adequately adjusting pH of the sol solution. Therefore, the method provides improved time efficiency and energy efficiency as compared to existing methods for preparing gels. Additionally, the method allows supercritical drying while avoiding a need for an additional solvent substitution, thereby simplifying the overall process. Further, the method enables preparation of carbon aerogels for supercapacitors having a high specific surface area and high capacitance even in the absence of additional activation step.

Claims

1. A method for preparing carbon aerogels comprising:

mixing phloroglucinol with furfural wherein the phloroglucinol and the furfural are mixed in a ratio of 1;

3 to 1;

2, and dissolving the resultant mixture in a solvent selected from a group consisting of primary alcohol, secondary alcohol, tertiary alcohol, acetone and tetrahydrofuran to form a sol solution wherein the phloroglucinol and the solvent are mixed in a ratio of 1;

300 to 1;

100, wherein the sol solution is gel at temperature of 20-30°

C. under atmospheric pressure;

substituting the solvent in thus obtained gels with liquid carbon dioxide, followed by drying in a supercritical state, to form aerogels; and

heat treating thus obtained aerogels in an electric furnace under inert atmosphere at a temperature of at least 600°

C. to obtain carbon aerogels having a specific surface area of 700 m²/g to 1,200 m²/g and a capacitance of 200 F/g to 400 F/g.

2. The method as claimed in claim 1 which further comprises adding an acidic or basic catalyst to the sol solution when forming the sol solution.

3. The method as claimed in claim 2 wherein the acidic catalyst is formic acid, acetic acid, phosphoric acid, nitric acid, hydrochloric acid or sulfuric acid, and the basic catalyst is aqueous ammonia, monoethanolamine, triethanolamine, potassium hydroxide, sodium hydroxide or sodium carbonate.

4. The method as claimed in claim 2 wherein the phloroglucinol and the catalyst are mixed in a ratio of 1:

0.1 to 1;

0.0001.

5. The method as claimed in claim 4 wherein the phloroglucinol and the catalyst are mixed in a ratio of 1:

0.02 to 1;

0.001.

6. The method as claimed in claim 2 wherein the heat treatment is carried out at a temperature of 700-1,000°

C.

7. The method as claimed in claim 2 wherein a heating rate to reach the heat treatment temperature is 0.5°

C./min to 10°

C./min.

8. The method as claimed in claim 1 wherein the heat treatment is carried out at a temperature of 700-1,000°

C.

9. The method as claimed in claim 1 wherein a heating rate to reach the heat treatment temperature is 0.5°

C./min to 10°

C./min.

10. The method as claimed in claim 9 wherein a heating rate to reach the heat treatment temperature is 1°

C./min to 5°

C./min.