Method of making a proton exchange membrane using a gas diffusion electrode as a substrate
One embodiment includes a method comprising providing a first catalyst coated gas diffusion media layer, depositing a wet first proton exchange membrane layer over the first catalyst coated gas diffusion media layer to form a first proton exchange membrane layer; providing a second catalyst coated gas diffusion media layer; contacting the second catalyst coated gas diffusion media layer, or second proton exchange membrane layer, with the first proton exchange membrane layer; and hot pressing together the catalyst coated diffusion layers and proton exchange membrane layer(s).
1. A method comprising:
providing a first catalyst coated gas diffusion media layer and a second catalyst coated gas diffusion media layer;
depositing a wet first proton exchange membrane layer over the first catalyst coated gas diffusion media layer and drying the first proton exchange membrane layer to form a first proton exchange membrane layer;
depositing a wet second proton exchange membrane layer over the second catalyst coated gas diffusion media layer and drying the second proton exchange membrane layer to form a second proton exchange membrane layer; and
hot pressing the first proton exchange membrane layer formed over the first catalyst coated gas diffusion media layer and the second proton exchange membrane layer formed over the second catalyst coated gas diffusion media layer together.
2. A method as set forth in claim 1 further comprising, before the hot pressing, interposing a subgasket between the first proton exchange membrane layer and the second proton exchange membrane layer.
3. A method as set forth in claim 2 wherein the subgasket extends past the edge of the first proton exchange membrane layer.
4. A method as set forth in claim 2 wherein the subgasket further comprises an elastomer seal.
5. A method as set forth in claim 1 wherein at least one of the first or second proton exchange membrane layer comprises an ionomer and a support film of expanded polytetrafluoroethylene (ePTFE), wherein the ePTFE is in intimate contact with the catalyst coated gas diffusion media layer as the ionomer is cast into the ePTFE.
6. A method as set forth in claim 1 wherein at least one of the first or second proton exchange membrane layer comprises an ionomer and a support, wherein the ionomer is imbibed into the support prior to contacting the first catalyst coated gas diffusion media layer, and wherein the support comprises one of a porous material less than 30 μm thick, a paper less than 30 μm thick, polyolefins, polyethylene, polypropylene, polyesters, polyphenylene sulfide, or polymers with crystalline melting temperatures which do not dissolve in the coating solvents or dispersants used to imbibe the ionomer into the support material.
7. A method as set forth in claim 1 wherein at least one of the first or second proton exchange membrane layer comprises an ionomer and a support film of expanded polytetrafluoroethylene (ePTFE), wherein the ionomer is imbibed into the ePTFE prior to contacting the first catalyst coated gas diffusion media layer.
8. A method as set forth in claim 1 wherein at least one of the first catalyst coated gas diffusion media layer or the second catalyst coated gas diffusion media layer comprises an at least partially wet catalyst coating layer immediately before depositing the proton exchange membrane layer.
9. A method as set forth in claim 1 wherein at least one of the first catalyst coated gas diffusion media layer or the second catalyst coated gas diffusion media layer comprises a microporous layer interposed between the catalyst coating and the gas diffusion media layer.
10. A method as set forth in claim 1 further comprising cutting into at least two portions at least one of the first catalyst coated gas diffusion media layer with the first proton exchange membrane layer thereon or the second catalyst coated gas diffusion media layer with the second proton exchange membrane layer thereon.