Chemistry: electrical current producing apparatus – product – and – With pressure equalizing means for liquid immersion operation
Reexamination Certificate
2001-09-27
2004-01-27
Kalafut, Stephen (Department: 1745)
Chemistry: electrical current producing apparatus, product, and
With pressure equalizing means for liquid immersion operation
C429S066000
Reexamination Certificate
active
06682845
ABSTRACT:
BACKGROUND
The present invention relates to a method and apparatus for maintaining compression within the active area of an electrochemical cell.
Electrochemical cells are energy conversion devices, usually classified as either electrolysis cells or fuel cells. A proton exchange membrane electrolysis cell can function as a hydrogen generator by electrolytically decomposing water to produce hydrogen and oxygen gas, and can function as a fuel cell by electrochemically reacting. hydrogen with oxygen to generate electricity. Referring to
FIG. 1
, which is a partial section of a typical anode feed electrolysis cell
100
, process water
102
is fed into cell
100
on the side of an oxygen electrode (anode)
116
to form oxygen gas
104
, electrons, and hydrogen ions (protons)
106
. The reaction is facilitated by the positive terminal of a power source
120
electrically connected to anode
116
and the negative terminal of power source
120
connected to a hydrogen electrode (cathode)
114
. The oxygen gas
104
and a portion of the process water
108
exit cell
100
, while protons
106
and water
110
migrate across a proton exchange membrane
118
to cathode
114
where hydrogen gas
112
is formed.
Another typical water electrolysis cell using the same configuration as is shown in
FIG. 1
is a cathode feed cell, wherein process water is fed on the side of the hydrogen electrode. A portion of the water migrates from the cathode across the membrane to the anode where hydrogen ions and oxygen gas are formed due to the reaction facilitated by connection with a power source across the anode and cathode. A portion of the process water exits the cell at the cathode side without passing through the membrane.
A typical fuel cell uses the same general configuration as is shown in FIG.
1
. Hydrogen gas is introduced to the hydrogen electrode (the anode in fuel cells), while oxygen, or an oxygen-containing gas such as air, is introduced to the oxygen electrode (the cathode in fuel cells). Water can also be introduced with the feed gas. The hydrogen gas for fuel cell operation can originate from a pure hydrogen source, hydrocarbon, methanol, or any other hydrogen source that supplies hydrogen at a purity suitable for fuel cell operation (i.e., a purity that does not poison the catatlyst or interfere with cell operation). Hydrogen gas electrochemically reacts at the anode to produce protons and electrons, wherein the electrons flow from the anode through an electrically connected external load, and the protons migrate through the membrane to the cathode. At the cathode, the protons and electrons react with oxygen to form water, which additionally includes any feed water that is dragged through the membrane to the cathode. The electrical potential across the anode and the cathode can be exploited to power an external load.
In other embodiments, one or more electrochemical cells can be used within a system to both electrolyze water to produce hydrogen and oxygen, and to produce electricity by converting hydrogen and oxygen back into water as needed. Such systems are commonly referred to as regenerative fuel cell systems.
Electrochemical cell systems typically include one or more individual cells arranged in a stack, with the working fluids directed through the cells via input and output conduits formed within the stack structure. The cells within the stack are sequentially arranged, each including a cathode, a proton exchange membrane, and an anode (hereinafter “membrane electrode assembly”, or “MEA”). Each cell typically further comprises a first flow field in fluid communication with the cathode and a second flow field in fluid communication with the anode. The MEA may be supported on either or both sides by screen packs or bipolar plates disposed within the flow fields, and which may be configured to facilitate membrane hydration and/or fluid movement to and from the MEA.
In order to maintain intimate contact between cell components under a variety of operational conditions and over long time periods, uniform compression is applied to the cell components. Pressure pads or other compression means are often employed to provide even compressive force from within the electrochemical cell. Some pressure pads are fabricated from materials incompatible with system fluids and/or the cell membrane, thereby requiring the pressure pads to be disposed within a protective encasing or otherwise isolated from the system fluids.
Even in the absence of a protective casing or a separator plate, it nonetheless remains difficult to manufacture pressure pad that provide even compression, especially at high pressures, for example greater than about 150 pounds per square inch (psi). There accordingly remains a need in the art for an improved pressure pad that maintains uniform compression, can be utilized for extended periods at high pressures, and that is compatible with the electrochemical cell environment.
SUMMARY OF THE INVENTION
The above-described drawbacks and disadvantages are overcome by an electrochemical cell comprising a first electrode; a second electrode; a membrane disposed between said first and second electrodes; and a unitary, electrically conductive pressure pad disposed adjacent to the first or second electrode, wherein the pressure pad comprises an integral blend of electrically conductive material and polymeric material. In a preferred embodiment, the pressure pad is formed of materials compatible with the electrochemical cell environment and is in at least partial fluid communication with the first or second electrode.
REFERENCES:
patent: 4011360 (1977-03-01), Walsh
patent: 4225654 (1980-09-01), Tajima et al.
patent: 4317864 (1982-03-01), Strasser
patent: 4732660 (1988-03-01), Plowman et al.
patent: 4844992 (1989-07-01), Strasser
patent: 4912286 (1990-03-01), Clarke
patent: 5009968 (1991-04-01), Guthrie et al.
patent: 5082596 (1992-01-01), Fukuda et al.
patent: 5281496 (1994-01-01), Clarke
patent: 5296570 (1994-03-01), Earls et al.
patent: 5324565 (1994-06-01), Leonida et al.
patent: 5366823 (1994-11-01), Leonida et al.
patent: 5466354 (1995-11-01), Leonida et al.
patent: 5472801 (1995-12-01), Mattejat et al.
patent: 5547777 (1996-08-01), Richards
patent: 5580672 (1996-12-01), Zagala, III et al.
patent: 5585038 (1996-12-01), Kirmanen
patent: 5656690 (1997-08-01), Pradl et al.
patent: 5824199 (1998-10-01), Simmons et al.
patent: 6096450 (2000-08-01), Walsh
patent: 6171719 (2001-01-01), Roy et al.
patent: 2002/0022173 (2002-02-01), Molter et al.
patent: 200 08 539 (2000-08-01), None
patent: 966407 (1964-08-01), None
patent: 58164170 (1983-09-01), None
patent: 2160371 (1990-06-01), None
patent: 5101836 (1993-04-01), None
patent: 5166523 (1993-07-01), None
patent: WO 98/23794 (1998-06-01), None
patent: WO 98/40537 (1998-09-01), None
patent: WO 98/57384 (1998-12-01), None
patent: WO 99/27599 (1999-06-01), None
patent: WO 00/39362 (2000-07-01), None
patent: WO 02/50339 (2002-06-01), None
T.G. Coker, et al.—“Industrial and Government Applications of SPE Fuel Cell and Electrolyzers”, The Case western Symposium, May 17-19, 1982, Cleveland, Ohio. 23 pages.
English Translation of JP 10162842 Abstract Only (Japan), 1 page.
English Translation of JP 02160371 Abstract Only (Japan), 1 page.
English Translation of JP 05166523 Abstract Only (Japan), 1 page.
English Translation of JP 58164170 Abstract Only (Japan), 1 page.
English Translation of JP 05101836 Abstract Only (Japan), 1 page.
International Search Report, International Application No. PCT/US01/30207; International Filing Date: Sep. 27, 2001, 7 pages.
International Search Report, International Application No. PCT/US01/30251; International Filing Date: Sep. 27, 2001.
“Conductive Ceramic Technology”, The Ebonix Company, http://www.netcontex.com/atraverda/index.htm; Jan. 15, 2002, 11 pages.
Hanlon Greg A.
Shiepe Jason K.
Cantelmo Gregg
Cantor & Colburn LLP
Kalafut Stephen
Proton Energy Systems, Inc.
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