PROCESS OF MANUFACTURING A MEMBRANE ELECTRODE ASSEMBLY
The present invention provides a process of manufacturing a sub-gasketed membrane electrode assembly in which ultrasonic energy is applied to a single face of an intermediate construct to form bonds between the gas diffusion layers and the sub-gaskets.
1 - 17 . (canceled)
18 . A process of manufacturing a sub-gasketed membrane electrode assembly, said process comprising the steps of:
i) providing a sub-gasketed catalyst coated ion-conducting membrane, wherein the sub-gasketed catalyst coated ion-conducting membrane comprises;
a) a catalyst coated ion-conducting membrane comprising an ion-conducting membrane disposed between first and second electrocatalyst layers;
c) a first sub-gasket and a second sub-gasket, each having an aperture defined by inner edges of each respective sub-gasket;
wherein the catalyst coated ion-conducting membrane is disposed between the first and second sub-gaskets and the first and second electrocatalyst layers are exposed through the apertures of the first and second sub-gaskets respectively to provide first and second active areas respectively;
ii) forming an intermediate construct by applying first and second gas diffusion layers to opposite faces respectively of the sub-gasketed catalyst coated ion-conducting membrane over the apertures in the first and second sub-gaskets respectively such that the first gas diffusion layer overlaps the entire first active area and one or more inner edges of the first sub-gasket, and the second gas diffusion layer overlaps the entire second active area and one or more inner edges of the second sub-gasket;
wherein a first adhesive track is provided to bond the first gas diffusion layer to the first sub-gasket and a second adhesive track is provided to bond the second gas diffusion layer to the second sub-gasket;
iii) applying ultrasonic energy to a single face of the intermediate construct from step ii) to flow the adhesive in the first and second adhesive tracks and form the bonds between the first and second gas diffusion layers and the first and second sub-gaskets respectively thus forming the sub-gasketed membrane electrode assembly, wherein the ultrasonic energy is only applied over regions in which the first and second adhesive tracks are present.
19 . The process according to claim 18 , wherein in step iii) the ultrasonic energy is applied by contacting a sonotrode with the first or second gas diffusion layer, wherein the sonotrode follows a path on the first or second gas diffusion layer, wherein the path is aligned in the through-plane direction with the first and second adhesive tracks.
20 . The process according to claim 18 , wherein in step iii) the intermediate construct is supported on a horizontally level surface present on the opposite face to which the ultrasonic energy is applied.
21 . The process according to claim 18 , wherein the adhesive in the first and second adhesive tracks is a hot melt polyolefin adhesive.
22 . The process according to claim 18 , wherein in step i) the sub-gasketed catalyst coated ion-conducting membrane is provided as a single unit.
23 . The process according to claim 1 , wherein the first adhesive track is provided by applying the adhesive directly to the first sub-gasket.
24 . The process according to claim 18 , wherein the second adhesive track is provided by applying the adhesive directly to the second sub-gasket.
25 . The process according to claim 18 , wherein the first adhesive track is provided by applying the adhesive directly to the first gas diffusion layer.
26 . The process according to claim 18 , wherein the second adhesive track is provided by applying the adhesive directly to the second gas diffusion layer.
27 . The process according to claim 18 , wherein the first adhesive track fully surrounds the aperture in the first sub-gasket.
28 . The process according to claim 18 , wherein the second adhesive track fully surrounds the aperture in the second sub-gasket.
29 . The process according to claim 18 , wherein the first and second adhesive tracks comprises beads of adhesive.
30 . The process according to claim 18 , wherein pressure is applied to the sub-gasketed membrane electrode during step iii).
31 . The process according to claim 18 , where the ion-conducting membrane does not extend to one or more peripheral edges of the first and second sub-gaskets.
32 . The process according to claim 18 , wherein the ion-conducting membrane extends to all of the peripheral edges of the first and second sub-gaskets.
33 . The process according to claim 18 , wherein the first and second electrocatalyst layers are disposed within the apertures in the first and second sub-gaskets respectively and do not overlap any of the inner edges of the first and second sub-gaskets.
34 . The process according to claim 18 , wherein the first and second electrocatalyst layers do not extend to one or more peripheral edges of the first and second sub-gaskets respectively.