Integration of an electrical diode within a fuel cell
First Claim
1. A fuel cell comprising:
- a first bipolar plate;
a second bipolar plate;
an MEA positioned between the first and second bipolar plates; and
a thin-sheet diode positioned adjacent to the MEA and being electrically coupled to the first and second bipolar plates, wherein the diode is non-conductive when a potential between the first bipolar plate and the second bipolar plate is within a predetermined voltage range, and wherein the diode becomes conductive when the potential between the first and second bipolar plates is slightly negative so that the potential between the first and second bipolar plate does not go significantly below zero.
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Abstract
A fuel cell system that employs a diode electrically coupled between bipolar plates in a fuel cell of a fuel cell stack for preventing the fuel cell between the plates from reversing its polarity. The diode is a thin-sheet p-n diode including doped semiconductor layers and has a thickness relative to the thickness of the MEA in the fuel cell so that the overall stack thickness does not increase. When the fuel cell is operating properly the diode does not conduct and all of the current through the fuel cell goes through the MEA. If the electric load on the stack increases to a level beyond the capability of the fuel cell, where the potential across the fuel cell goes significantly below zero, the diode will begin to conduct so that any current that cannot travel through the MEA with the cell voltage less than one negative forward diode voltage drop is able to go around the MEA through the diode.
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Citations
21 Claims
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1. A fuel cell comprising:
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a first bipolar plate;
a second bipolar plate;
an MEA positioned between the first and second bipolar plates; and
a thin-sheet diode positioned adjacent to the MEA and being electrically coupled to the first and second bipolar plates, wherein the diode is non-conductive when a potential between the first bipolar plate and the second bipolar plate is within a predetermined voltage range, and wherein the diode becomes conductive when the potential between the first and second bipolar plates is slightly negative so that the potential between the first and second bipolar plate does not go significantly below zero. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A fuel cell comprising:
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a first bipolar plate;
a second bipolar plate;
an MEA positioned between the first and second bipolar plates; and
a thin-sheet p-n diode positioned adjacent to the MEA and being electrically coupled to the first and second bipolar plates, said p-n diode including doped InAs semiconductor layers, wherein the diode is non-conductive when a potential between the first bipolar plate and the second bipolar plate is within a predetermined voltage range, and wherein the diode becomes conductive when the potential between the first and second bipolar plates is near −
0.1 V so that the potential between the first and second bipolar plate does not go significantly below zero. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A fuel cell stack for a vehicle, said stack including a plurality of fuel cells, each fuel cell comprising:
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a top bipolar plate;
a bottom bipolar plate;
an MEA positioned between the top and bottom bipolar plates so as to define an anode flow channels between the top bipolar plate and the MEA and a cathode flow channels between the bottom bipolar plate and the MEA; and
a thin-sheet p-n diode positioned adjacent to the MEA and being electrically coupled to the first and second bipolar plates, said p-n diode including doped InAs semiconductor layers, wherein the p-n diode is non-conductive between a potential of about zero and about +1 volts across the top and bottom bipolar plates, and wherein the diode becomes conductive when the potential across the top and bottom bipolar plates is slightly negative so that the potential across the top and bottom bipolar plates does not go significantly below zero. - View Dependent Claims (19, 20, 21)
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Specification