Activated carbon for use in electric double layer capacitors

• US 20020114126A1
• Filed: 01/09/2002
• Published: 08/22/2002
• Est. Priority Date: 05/09/2000
• Status: Active Grant

• Current Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Mitsubishi Chemical Corporation (Mitsubishi Chemical Group Corp.)
• Inventors: Toki, Kazuyuki, Takeda, Yoshitaka, Hirahara, Satoshi
• Granted Patent: US 7,091,156 B2
• Time in Patent Office: Days
• US Class Current: 361/302
• CPC Class Codes: C01B 32/324 from waste materials, e.g. tyres or spent sulfite pulp liquor
• CPC Class Codes: C01B 32/336 characterised by gaseous activating agents
• CPC Class Codes: H01G 11/24 characterised by structural features of the materials making up or comprised in the electrodes, e.g. form, surface area or porosity; characterised by the structural features of powders or particles used therefor
• CPC Class Codes: H01G 11/34 characterised by carbonisation or activation of carbon
• CPC Class Codes: H01G 11/38 Carbon pastes or blends; Binders or additives therein
• CPC Class Codes: H01G 11/42 Powders or particles, e.g. composition thereof
• CPC Class Codes: Y02E 60/13 Energy storage using capacitors
• CPC Class Codes: Y02T 10/70 Energy storage systems for electromobility, e.g. batteries

Abstract

Activated carbon adapted for electric double layer capacitors is provided, which capacitors can give a large power density per unit volume and which capacitors, even when charge-and-discharge cycle is repeated under a large current or a constant voltage is continuously applied for a long time, undergo less decrease in output density.

That is, the present invention relates to the activated carbon manufactured by carbonization of coconut shell, which has a BET specific surface area of 2000 m²/g to 2500 m²/g, an average pore diameter of 1.95 nm (19.5 Å to 2.20 nm (22 Å) and a pore volume of pores having a pore diameter calculated according to a Cranston-Inkley method of 5.0 nm (50 A) to 30.0 nm (300 Å), of 0.05 cm³/g to 0.15 cm³/g.

Claims

1. An activated carbon for electric double layer capacitors produced by carbonization of coconut shell, wherein a BET specific surface area is 2000 m²/g to 2500m²/g, an average pore diameter is 1.95 nm (19.5 Å

) to 2.20 nm (22 Å

) and a pore volume of pores having a pore diameter calculated according to a Cranston-Inkley method of 5.0 nm (50 Å

) to 30.0 nm (300 Å

) is 0.05 cm³/g to 0.15 cm³/g.

2. The activated carbon for electric double layer capacitors as claimed in claim 1, wherein the amount of oxygen contained per g of the activated carbon is 1 mg to 20 mg, and a spontaneous potential vs a lithium electrode is 2.85 V to 3.03 V in a nonaqueous electrolytic solution.

3. The activated carbon for electric double layer capacitors as claimed in claim 1 or 2, wherein the activated carbon is obtained by subjecting a coconut shell carbonization product to steam activation.

4. The activated carbon for electric double layer capacitors as claimed in claim 1, wherein the BET specific surface area is 2000 m²/g to 2400 m²/g.

5. The activated carbon for electric double layer capacitors as claimed in claim 1, wherein the BET specific surface area is 2050 m²/g to 2250 m²/g.

6. The activated carbon for electric double layer capacitors as claimed in claim 1, wherein the pore volume of pores having a pore diameter calculated according to a Cranston-Inkley method of 5.0 nm (50 Å

) to 30.0 nm (300 Å

) is 0.07 cm³/g to 0.13 cm³/g.

7. The activated carbon for electric double layer capacitors as claimed in claim 1, wherein the pore volume of pores having a pore diameter calculated according to a Cranston-Inkley method of 5.0 nm (50 Å

) to 30.0 nm (300 Å

) is 0.08 cm³/g to 0.12 cm³/g.

8. The activated carbon for electric double layer capacitors as claimed in claim 1, wherein the average pore diameter is 2.00 nm to 2.15 nm.

9. The activated carbon for electric double layer capacitors as claimed in claim 1, wherein the average pore diameter is 2.02 nm to 2.15 nm.