14-05-2012, 01:21 PM
Nanostructured Carbons: Double-Layer Capacitance and More
[attachment=21985]
Types of Nanocarbons Used for
EDLCs.—Many different carbon forms
can be used as active materials in EDLC
electrodes and only a few examples,
which are thought to be the most
representative, are given below. A
recent and exhaustive review has been
recently published by Pandolfo, et al.
and that paper can be consulted for
more detailed information.3
Electrode Design Considerations.—
As indicated in , the construction
of an electrochemical capacitor is
much like that of a battery in that it
consists of two active layers with a
separator between them wetted with an
electrolyte.
The electrodes in the capacitors are
in general thin coatings applied to a
metallic current collector. The active
material is mixed with a binder to
form a slurry that can be applied at a
controlled thickness, rolled, and dried
to form the thin, porous electrode. The
thickness of the electrode is generally
in the range of 100-300 microns and it
has a high porosity of 65-75%.
Simon and Burke
(continued from previous page)
Table III. Projected characteristics of advanced electrochemical capacitors using
carbon electrodes.
Graphitic carbon/organic 3.4-1.8 18 30 2.0 1.8
* unpackaged-active materials only
* neglecting contact and pore resistances
power densities are given for both
matched impedance and 95% efficiency
pulses. For most applications with
electrochemical capacitors, the high
efficiency power density is the
appropriate measure of the power
capability of the device. For the
large devices, the energy density for
the available devices is between
3.5-4.5 Wh/kg and the 95% power
density is between 800-1200 W/kg.
[attachment=21985]
Types of Nanocarbons Used for
EDLCs.—Many different carbon forms
can be used as active materials in EDLC
electrodes and only a few examples,
which are thought to be the most
representative, are given below. A
recent and exhaustive review has been
recently published by Pandolfo, et al.
and that paper can be consulted for
more detailed information.3
Electrode Design Considerations.—
As indicated in , the construction
of an electrochemical capacitor is
much like that of a battery in that it
consists of two active layers with a
separator between them wetted with an
electrolyte.
The electrodes in the capacitors are
in general thin coatings applied to a
metallic current collector. The active
material is mixed with a binder to
form a slurry that can be applied at a
controlled thickness, rolled, and dried
to form the thin, porous electrode. The
thickness of the electrode is generally
in the range of 100-300 microns and it
has a high porosity of 65-75%.
Simon and Burke
(continued from previous page)
Table III. Projected characteristics of advanced electrochemical capacitors using
carbon electrodes.
Graphitic carbon/organic 3.4-1.8 18 30 2.0 1.8
* unpackaged-active materials only
* neglecting contact and pore resistances
power densities are given for both
matched impedance and 95% efficiency
pulses. For most applications with
electrochemical capacitors, the high
efficiency power density is the
appropriate measure of the power
capability of the device. For the
large devices, the energy density for
the available devices is between
3.5-4.5 Wh/kg and the 95% power
density is between 800-1200 W/kg.