Method of making membrane-electrode assemblies for electrochemical cells and assemblies made thereby
First Claim
1. A method of making a combination electrolyte and electrode structure for an electrochemical cell having an electrolyte membrane of solid polymer proton conductive material with first and second spaced apart opposed surfaces and first and second electrodes at the respective first and second surface, comprising:
- a) forming a slurry of proton conductive material and at least one group of finely divided carbon particles and very finely divided catalytic particles supported on and in the carbon particles;
b) applying the slurry onto a first surface of the membrane;
c) applying the slurry onto a second surface of the membrane; and
d) heating while pressing the applied slurry for a time and at a temperature and compressive load sufficient to embed at least a portion of the particles in, respectively, the surfaces of the membrane to thereby form the first and second electrodes.
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Abstract
A method of making a combination, unitary, membrane and electrode assembly having a solid polymer electrolyte membrane, and first and second electrodes at least partially embedded in opposed surfaces of the membrane. The electrodes each comprise a respective group of finely divided carbon particles, very finely divided catalytic particles supported on internal and external surfaces of the carbon particles and a proton conductive material intermingled with the catalytic and carbon particles. A first group of finely divided carbon particles forming the first electrode has greater water attraction and retention properties, and is more hydrophilic than a second group of carbon particles forming the second electrode. In a preferred method, the membrane electrode assembly of the invention is prepared by forming a slurry of proton conductive material and at least one group of the carbon and catalyst particles. The slurry is applied to the opposed surfaces of the membrane and heated while being pressed to the membrane for a time and at a temperature and compressive load sufficient to embed at least a portion of the particles into the membrane.
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Citations
17 Claims
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1. A method of making a combination electrolyte and electrode structure for an electrochemical cell having an electrolyte membrane of solid polymer proton conductive material with first and second spaced apart opposed surfaces and first and second electrodes at the respective first and second surface, comprising:
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a) forming a slurry of proton conductive material and at least one group of finely divided carbon particles and very finely divided catalytic particles supported on and in the carbon particles; b) applying the slurry onto a first surface of the membrane; c) applying the slurry onto a second surface of the membrane; and d) heating while pressing the applied slurry for a time and at a temperature and compressive load sufficient to embed at least a portion of the particles in, respectively, the surfaces of the membrane to thereby form the first and second electrodes. - View Dependent Claims (2, 3, 4, 5)
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6. A method of making a combination electrolyte and electrode structure for an electrochemical cell having an electrolyte membrane of solid polymer proton conductive material with first and second spaced apart opposed surfaces and first and second electrodes at the respective first and second surfaces, comprising:
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a) forming a first slurry of proton conductive material and a first group of finely divided carbon particles and very finely divided catalytic particles supported on and in the carbon particles; b) forming a second slurry of proton conductive material and a second group of finely divided carbon particles and very finely divided catalytic particles supported on and in the carbon particles, the second group being less acidic than the first group; c) applying the first slurry onto a first surface of the membrane; d) applying the second slurry onto a second surface of the membrane; and e) heating while pressing the applied slurry for a time and at a temperature and compressive load sufficient to embed at least a portion of the particles in, respectively, the surfaces of the membrane to thereby form the first and second electrodes. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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Specification