Activated carbon for use in electric double layer capacitors

• US 20060240979A1
• Filed: 06/21/2006
• Published: 10/26/2006
• 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.), Toyota Jidosha Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Toki, Kazuyuki, Hirahara, Satoshi, Takeda, Yositaka
• Granted Patent: US 7,625,839 B2
• Time in Patent Office: Days
• US Class Current: 502/416
• 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 Å) to 30.0 nm (300 Å), of 0.05 cm³/g to 0.15 cm³/g.

Claims

1-9. -9. (canceled)

10. A method of making an activated carbon, which comprises the steps of:

a) carbonizing coconut shell, thereby producing a carbonization product; and

b) activating the carbonization product.

11. The method of claim 10, wherein said activating is effected by gas activation.

12. The method of claim 10, wherein said activating is effected by chemical activation.

13. The method of claim 11, wherein said gas activation is effected by steam activation.

14. The method of claim 10, which further comprises prior to said step a), pulverizing said coconut shell.

15. The method of claim 10, wherein said carbonizing in step a) is effected under an inert atmosphere.

16. The method of claim 10, wherein said activating in step b) is effected by heat-treating the carbonization product of step a) at a temperature of 800°

C. to 1,300°

C. in an inert gas comprising nitrogen, argon or a combustion exhaust gas containing steam.