Catalysed membrane
View Patent ↗The present invention provides a catalysed ion-conducting membrane comprising an ion-conducting membrane, an electrocatalyst layer having two opposing faces, and a layer A comprising an ion-conducting material and a carbon containing material. Also provided are methods for preparing the catalysed ion-conducting membrane.
1. A catalysed ion-conducting membrane comprising an ion-conducting membrane, an electrocatalyst layer having two opposing faces, and a layer A, wherein:
the layer A and the ion-conducting membrane are adjacent to opposite faces of the electrocatalyst layer;
the layer A comprises an ion-conducting material I A and a carbon containing material C A ;
the electrocatalyst layer comprises an ion-conducting material I B and an electrocatalyst; wherein
the layer A does not comprise an electrocatalyst; and
the layer A has a permeability, k 1 , of greater than 20 nm 2 ; and
the electrocatalyst layer has a permeability, k 2 , of no more than 20 nm 2 ; and
the weight ratio of ion-conducting material I A to carbon containing material C A in layer A is in the range of and including 2:1 to 1:2.
2. The catalysed ion-conducting membrane according to claim 1 , wherein the layer A is hydrophobic.
3. The catalysed ion-conducting membrane according to claim 1 , wherein the electrocatalyst is supported.
4. The catalysed ion-conducting membrane according to claim 3 , wherein the electrocatalyst is supported on a carbon containing material C B .
5. The catalysed ion-conducting membrane according to claim 1 , wherein the electrocatalyst layer is a cathode electrocatalyst layer.
6. A membrane electrode assembly comprising the catalysed ion-conducting membrane according to claim 1 .
7. A fuel cell comprising the membrane electrode assembly according to claim 6 .
8. A fuel cell comprising the catalysed ion-conducting membrane according to claim 1 , or a membrane electrode assembly comprising an ion-conducting membrane, an electrocatalyst layer having two opposing faces, and a layer A, wherein:
the layer A and the ion-conducting membrane are adjacent to opposite faces of the electrocatalyst layer;
the layer A comprises an ion-conducting material I A and a carbon containing material C A ;
the electrocatalyst layer comprises an ion-conducting material I B and an electrocatalyst; wherein
the layer A does not comprise an electrocatalyst; and
the layer A has a permeability, k 1 , of greater than 20 nm 2 ; and the electrocatalyst layer has a permeability, k 2 , of no more than 20 nm 2 ; and
the weight ratio of ion-conducting material I A to carbon containing material C A in layer A is in the range of and including 2:1 to 1:2.
9. A method of preparing the catalysed ion-conducting membrane according to claim 1 , the method comprising the steps of:
i) applying an electrocatalyst layer ink onto an ion-conducting membrane and then drying the ink to form an electrocatalyst layer; then
ii) applying a layer A ink onto the electrocatalyst layer then drying the ink to form a layer A.
10. A method of preparing the catalysed ion-conducting membrane according to claim 1 , the method comprising the steps of:
i) applying a layer A ink onto a substrate then drying the ink to form a layer A; then
ii) applying an electrocatalyst layer ink onto the layer A formed in step i) then drying the ink to form an electrocatalyst layer;
iii) combining the layers with an ion-conducting membrane such that the electrocatalyst layer is adjacent to the ion-conducting membrane;
wherein the substrate is a decal transfer substrate and step iii) is carried out by transferring the combined layers onto an ion-conducting membrane by decal transfer from the transfer substrate.