Capacitor with dual electric layer

Electricity: electrical systems and devices – Electrolytic systems or devices – Double layer electrolytic capacitor

Reexamination Certificate

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C361S508000

Reexamination Certificate

active

06195252

ABSTRACT:

TECHNICAL FIELD
The invention relates to electrical engineering and can find application in producing dual electric layer (DEL) capacitors having high specific power characteristics and capable of storing and putting out electric power at a high rate.
BACKGROUND ART
Known in the art presently are dual electric layer capacitors with liquid electrolyte and electrodes made of diverse materials having high specific surface area (cf., e.g., U.S. Pat. No. 4,313,084 (1982) and U.S. Pat. No. 4,713,734 (1987), and DE U.S. Pat. No. 3,210420 (1983). Best results are attained when using the various activated carbons as the electrode materials. Specific capacitance of such capacitors exceeds 2 F/cu.cm, while use of aprotic electrolytes makes it possible to increase capacitor working voltage to 2-3 V (U.S. Pat. No. 4,697,224 (1987), Nat. Tech. Report, 180, 26, # 2, pp.220-230).
Closest to the proposed invention as to the technical essence and attainable effect is a DEL capacitor comprising two electrodes and liquid electrolyte (i.e., an aqueous alkali-metal hydroxide with a concentration of 3 to 7 mole/lit having a polarizable (negative) electrode made of a carbon fibrous material and a non-polarizable electrode made of nickel oxide. Maximum voltage of said capacitor equals 1.4 V and specific capacitance and specific energy, 46 F/cu.cm and 45 J/cu.cm, respectively (WO 97/07518 dated Feb. 27, 1997).
DISCLOSURE OF THE INVENTION
Despite the presence of a number of technical solutions aimed at improving in DEL capacitors the problem how to enhance their specific characteristics still remains an urgent one. Thus, in particular, the values of specific capacitance and specific energy attainable by the heretofore-known capacitors, as well as their cost place limitation upon their use in electrically driven transport facilities.
Therefore the invention has for its primary and essential object to attain higher energy density and lower cost of DEL capacitors.
The foregoing object is accomplished due to the herein-disclosed invention whose essence resides in that the polarizable capacitor electrode is made of a carbon material and the non-polarizable electrode is made of a material incorporating lead dioxide as the active component.
Though a capacitor having such a combination of electrodes can make use of a variety of electrolytes, it is preferable to use aqueous solutions of inorganic acids and mixtures thereof.
It is due to the solution disclosed before that the specific energy of DEL capacitors is managed to be increased and their cost to be reduced. Increased specific energy is attained due to an increase in the capacitor operating voltage to 2.2-2.6 V, as well as by virtue of a 1.2-1.4 times increase in the electric capacitance of the carbon material attainable in an acid solution compared with an alkali solution.
And the cost of a DEL capacitor made according to the present invention is reduced due to the use of a lead-dioxide electrode which is cheaper than a nickel-oxide one.


REFERENCES:
patent: 4313084 (1982-01-01), Hosokawa et al.
patent: 4674010 (1987-06-01), van den Steen
patent: 4697224 (1987-09-01), Watanabe et al.
patent: 4713734 (1987-12-01), DeKay
patent: 4896249 (1990-01-01), Endo et al.
patent: 5381303 (1995-01-01), Yoshida et al.
patent: 5682288 (1997-10-01), Wani
patent: 1 921 610 (1979-08-01), None
patent: 3 210 420 (1983-09-01), None
patent: 2 052 384 (1971-04-01), None
patent: 2 054 723 (1996-02-01), None
patent: 2 063 085 (1996-06-01), None
patent: WO92/12521 (1992-07-01), None
patent: WO97/07518 (1997-02-01), None

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