CATALYST-COATED MEMBRANE AND METHOD OF MANUFACTURE

Abstract

Provided is a method of manufacturing a catalyst-coated ion-conducting membrane for an electrochemical cell, the method comprising: providing an ion-conducting membrane, an electrocatalyst layer, and a masking layer between the ion-conducting membrane and the electrocatalyst layer, wherein the masking layer comprises one or more aperture(s) to provide one or more exposed region(s) and one or more non-exposed region(s) of the electrocatalyst layer; and contacting the layers such that the one or more exposed region(s) of the electrocatalyst layer are transferred onto the ion-conducting membrane and the masking layer prevents the one or more non-exposed region(s) of the electrocatalyst layer from being transferred onto the ion-conducting membrane.

Claims

1. A method of manufacturing a catalyst-coated ion-conducting membrane for an electrochemical cell, the method comprising: providing an ion-conducting membrane, an electrocatalyst layer, and a masking layer between the ion-conducting membrane and the electrocatalyst layer, wherein the masking layer comprises one or more aperture(s) to provide one or more exposed region(s) and one or more non-exposed region(s) of the electrocatalyst layer; and contacting the layers such that the one or more exposed region(s) of the electrocatalyst layer are transferred onto the ion-conducting membrane and the masking layer prevents the one or more non-exposed region(s) of the electrocatalyst layer from being transferred onto the ion-conducting membrane.

2. The method of claim 1, further comprising an initial step of providing a masking layer without apertures and a step of cutting the aperture(s) into the masking layer, prior to the step of providing the masking layer between the ion-conducting membrane and the electrocatalyst layer.

3. The method of claim 1, wherein the step of contacting the layers includes pressing the layers together.

4. The method of 3, wherein the layers are pressed together between a pair of rollers in a roll-to-roll lamination process.

5. The method of claim 3, wherein the layers are pressed together by a flatbed press.

6. The method of claim 4, wherein the rollers heat the layers to a temperature in the range of and including 100 to 200 C.

7. The method of claim 1, further comprising a step of removing the masking layer and non-exposed region(s) of the electrocatalyst layer from the ion-conducting membrane after the step of contacting the layers.

8. The method of claim 7, wherein the non-exposed region(s) of the electrocatalyst layer is/are recovered and recycled for further use.

9. The method of claim 1, wherein an electrocatalyst layer is provided on either side of the ion-conducting membrane and a masking layer is provided between the ion-conducting membrane and each respective electrocatalyst layer.

10. The method of claim 1, wherein the ion-conducting membrane is sandwiched between two layers of non-ion-conducting seal material such that it is a membrane-seal assembly, the membrane-seal assembly comprising one or more inner region(s) and one or more border region(s), the inner region(s) being devoid of non-ion-conducting seal material and being ion-conducting and the border region(s) comprising the non-ion-conducting seal material and being non-ion conducting.

11. The method of claim 1, wherein the ion-conducting membrane comprises a polymer electrolyte membrane.

12. The method of claim 1, wherein the electrocatalyst layer and the masking layer are provided together as a pre-formed masked electrocatalyst component, with the masking layer bonded to the electrocatalyst layer.

13. The method of claim 1, further comprising a step of applying sub-gaskets around an active area of the catalyst-coated ion-conducting membrane.

14-15. (canceled)

16. A method of producing a masked electrocatalyst component for use in manufacturing a catalyst-coated ion-conducting membrane, the method comprising: providing an electrocatalyst layer; providing a masking component comprising a masking layer, the masking layer comprising one or more aperture(s); and combining the masking layer with the electrocatalyst layer to form a masked electrocatalyst component.

17. The method of claim 16, wherein the step of combining the masking layer with the electrocatalyst layer to form a masked electrocatalyst component is a step of bonding the masking layer to the electrocatalyst layer to form a masked electrocatalyst component.

18. The method of claim 17, wherein the step of bonding the masking layer to the electrocatalyst layer is performed by a roll-to-roll lamination process, wherein the layers are pressed together between a pair of rollers.

19. The method of claim 17, wherein the masking layer is bonded to the electrocatalyst layer by an adhesive.

20. The method of claim 16, wherein the masking component further comprises a reinforcement layer for stabilising the masking layer during the step of combining the masking layer with the electrocatalyst layer.

21. The method of claim 20, wherein the reinforcement layer comprises a reinforcing polymer film.

22. The method of claim 20, wherein the reinforcement layer is bonded to the masking material by an adhesive.

23. The method of claim 20, further comprising a step of removing the reinforcement layer after the step of bonding the masking layer to the electrocatalyst layer.

24. The method of claim 16, wherein the electrocatalyst layer and the masking component are each provided in the form of continuous webs, with the masking layer comprising a plurality of apertures along a length of the web.

25. The method of claim 24, wherein the masked electrocatalyst component is produced in the form of a continuous web, further comprising a step of cutting the masked electrocatalyst component into discrete patches.

26. The method of claim 25, wherein the masked electrocatalyst component is cut between apertures of the masking layer, such that the masking layer in each patch comprises a single aperture.

27. The method of claim 16, further comprising a step of cutting alignment features into the masked electrocatalyst component, for assisting with aligning the masked electrocatalyst component during a process of manufacturing a catalyst-coated ion-conducting membrane.

28. (canceled)

29. A masked electrocatalyst component for use in manufacturing an electrochemical cell, the masked electrocatalyst component comprising: an electrocatalyst layer having a first surface and an oppositely disposed second surface; a masking layer disposed on the first surface of the electrocatalyst layer, wherein the masking layer comprises one or more aperture(s), thereby providing one or more exposed region(s) and one or more non-exposed region(s) of the first surface of the electrocatalyst layer.

30. The masked electrocatalyst component of claim 29, wherein the masked electrocatalyst component is in roll-good form, with the electrocatalyst layer and the masking layer each being a continuous web, the masking layer comprising a plurality of apertures along a length of the web.

31. The masked electrocatalyst component of claim 29, wherein the masked electrocatalyst component is in the form of a discrete patch.

32. The masked electrocatalyst component of claim 31, wherein the masking layer comprises a single aperture.

33. The masked electrocatalyst component of claim 29, further comprising a carrier layer disposed on the second surface of the electrocatalyst layer.

34. The masked electrocatalyst component of claim 29, wherein the electrocatalyst layer comprises a platinum group metal or an alloy of a platinum group metal.

35. The masked electrocatalyst component of claim 29, wherein the masking layer comprises a polymer film.

36. The masked electrocatalyst component of claim 35, wherein the polymer film comprises a polymer which is thermally stable at temperatures in the range of and including 100 to 200 C.

37. The masked electrocatalyst component of claim 35, wherein the polymer film comprises polyethylene naphthalate (PEN), polyethylenimine (PEI), polyether ether ketone (PEEK), polyphenylene sulfide (PPS), polyimide (PI), polytetrafluoroethylene (PTFE), or mixtures thereof.

38. The masked electrocatalyst component of claim 29, wherein the masking layer is bonded to the electrocatalyst layer by an adhesive.

39. The masked electrocatalyst component of claim 38, wherein the adhesive is thermally stable at temperatures in the range of and including 100 to 200 C.

40. The masked electrocatalyst component of claim 38, wherein the adhesive comprises a silicone pressure-sensitive adhesive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0061] Embodiments of the invention will now be described in more detail with reference to the following drawings, which are illustrative and not limiting of the invention.

[0062] FIG. 1 is a perspective view of a masked electrocatalyst component in accordance with an embodiment of the invention.

[0063] FIG. 2 is a cross-section view of the masked electrocatalyst component shown in FIG. 1.

[0064] FIG. 3 is a perspective view of a masked electrocatalyst component in accordance with an embodiment of the invention.

[0065] FIG. 4 is a cross-section view of the masked electrocatalyst component shown in FIG. 3.

[0066] FIG. 5 is a process flow diagram illustrating a method for manufacturing a catalyst-coated ion-conducting membrane in accordance with an embodiment of the invention.

[0067] FIG. 6 is a process flow diagram illustrating a method for manufacturing a catalyst-coated ion-conducting membrane in accordance with an embodiment of the invention.

[0068] FIG. 7 illustrates a catalyst-coated ion-conducting membrane being manufactured by a roll-to-roll process in accordance with an aspect of the invention.

[0069] FIG. 8 is a process flow diagram illustrating a method for manufacturing a masked electrocatalyst component in accordance with an embodiment of the invention.

[0070] FIG. 9 is a process flow diagram illustrating a method for manufacturing a masked electrocatalyst compound in accordance with an embodiment of the invention.

[0071] FIGS. 10A and 10B illustrate subsystems of a roll-to-roll based system for manufacturing a masked electrocatalyst component in accordance with a method of the present invention.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

[0072] FIGS. 1 and 2 illustrate a masked electrocatalyst component 100 in accordance with an embodiment of the invention. In the illustrated embodiment, the masked electrocatalyst component 100 is in the form of a discrete patch, for use in manufacturing an individual catalyst-coated ion-conducting membrane.

[0073] The masked electrocatalyst component 100 comprises an electrocatalyst layer 2 having a first surface 4 and an oppositely disposed second surface 6. The masked electrocatalyst component 100 further comprises a masking layer 8 disposed on the first surface 4 of the electrocatalyst layer 2. The masking layer 8 comprises an aperture 10 which exposes a region of the electrocatalyst layer 2 disposed underneath the masking layer 8. The region of the electrocatalyst layer 2 corresponding to the aperture 10 can be referred to as an exposed region 12, while the region of the electrocatalyst layer 2 which remains under the masking layer 8 around the aperture 10 can be referred to as a non-exposed region 14. In the illustrated embodiment, the masking layer 8 is bonded to the electrocatalyst layer 2 by a layer of adhesive 16. This is preferred because it facilitates easier handling of the masked electrocatalyst component.

[0074] FIGS. 3 and 4 illustrate a masked electrocatalyst component 200 in accordance with another embodiment of the invention, which is in the form of a continuous web (which can be used in a roll-good) rather than a discrete patch. The same reference numbers are used for components which are common between the embodiment shown in FIGS. 1 and 2 and the embodiment shown in FIGS. 3 and 4.

[0075] In the illustrated embodiment, a carrier layer 18 is provided adjacent to the second surface 6 of the electrocatalyst layer 2, which helps to support and protect the electrocatalyst layer 2. The masking layer 8 is provided as a continuous web comprising a plurality of apertures 10, thereby forming a plurality of exposed regions 12 of the electrocatalyst layer 2.

[0076] In the illustrated embodiment, alignment features 20 are provided to assist in aligning the masked electrocatalyst component 200 with an ion-conducting membrane during manufacture of a catalyst-coated ion-conducting membrane. The alignment features 20 are notches cut into the masked electrocatalyst component 200. Alignment features 20 may also assist in aligning with a second masked electrocatalyst component if two such components are simultaneously applied to an ion-conducting membrane.

[0077] FIG. 5 illustrates a flow diagram of a method for manufacturing a catalyst-coated ion-conducting membrane in accordance with an embodiment of the invention. In a first step, an ion-conducting membrane, an electrocatalyst layer, and a masking layer between the ion-conducting membrane and the electrocatalyst layer are provided 306. The masking layer comprises one or more aperture(s) to provide one or more exposed region(s) and one or more non-exposed region(s) of the electrocatalyst layer. In a second step, the layers are contacted 308, such that the one or more exposed region(s) of the electrocatalyst layer are transferred onto the ion-conducting membrane and the masking layer prevents the one or more non-exposed region(s) of the electrocatalyst layer from being transferred onto the ion-conducting membrane.

[0078] An electrocatalyst decal corresponding to an aperture in the masking layer is therefore transferred onto the ion-conducting membrane, which allows the exact size and shape of the electrocatalyst decal to be precisely controlled by modifying the size and shape of the aperture in the masking layer. The result is a catalyst-coated ion-conducting membrane with a very precisely defined electrocatalyst layer, which does not extend an undesirable distance beyond the intended active area.

[0079] Preferably, the step of contacting the layers 308 includes pressing the layers together. The layers may be pressed together between a pair of rollers in a roll-to-roll lamination process, or between two plates of a flatbed press. The rollers or flatbed press may heat the layers to a temperature in the range of and including 100 to 200 C., to assist in adhering the electrocatalyst decal to the ion-conducting membrane without the need to use a separate adhesive.

[0080] FIG. 6 illustrates a flow diagram of a method for manufacturing a catalyst-coated ion-conducting membrane in accordance with another embodiment of the invention. A masking layer is firstly provided 302, and apertures are cut 304 into the masking layer. The size and shape of the apertures can be tailored to the requirements of the electrocatalyst layer(s) in a catalyst-coated ion-conducting membrane.

[0081] Next, an ion-conducting membrane, an electrocatalyst layer and the masking layer are provided 306, with the masking layer being provided between the ion-conducting membrane and the electrocatalyst layer. The one or more aperture(s) in the masking layer provide one or more exposed region(s) and one or more non-exposed region(s) of the electrocatalyst layer.

[0082] The layers are then contacted 308, such that the one or more exposed region(s) of the electrocatalyst layer are transferred onto the ion-conducting membrane and the masking layer prevents the one or more non-exposed region(s) of the electrocatalyst layer from being transferred onto the ion-conducting membrane. As mentioned previously, contacting the layers 308 may include pressing the layers together. The layers may be pressed together between a pair of rollers in a roll-to-roll lamination process, or between two plates of a flatbed press, and the rollers or flatbed press may heat the layers to a temperature in the range of and including 100 to 200 C.

[0083] In a subsequent step, the masking layer and non-exposed region(s) of the electrocatalyst layer is/are removed 310 from the ion-conducting membrane, leaving only the electrocatalyst decal on the ion-conducting layer. The non-exposed region(s) of the electrocatalyst layer can then be recovered and recycled 312 for further use, for example in a new electrocatalyst layer to be provided 306 at the start of the process.

[0084] As shown in FIG. 7, which illustrates a roll-to-roll process for manufacturing a catalyst-coated ion-conducting membrane in accordance with the present invention, an electrocatalyst layer 2 (shown disposed on a carrier layer or backing liner 18) may be provided on either side of an ion-conducting membrane 22, with a masking layer 8 disposed between the ion-conducting membrane 22 and each respective electrocatalyst layer 2.

[0085] The layers are fed in simultaneously between a pair of laminating rollers 24, which laminate the layers and transfer the exposed regions 12 of electrocatalyst layer 2 (corresponding to the apertures 10 of the masking layer 8) onto the ion-conducting membrane 22. The masking layer 8 and non-exposed regions 14 of the electrocatalyst layer 2 (together with the backing liner 18) are then peeled away from the ion-conducting membrane 22, leaving the exposed region 12 of electrocatalyst layer on the ion-conducting membrane 22 as an electrocatalyst decal. In the roll-to-roll process shown, the respective layers are each provided as continuous webs, so that the resulting catalyst-coated ion-conducting membrane is also produced in the form of a continuous web, i.e. in roll-good form. The catalyst-coated ion-conducting membrane can then either be used directly in a roll-to-roll process for manufacturing a membrane electrode assembly, or wound onto a roll for future use.

[0086] The process of the present invention can therefore provide a highly efficient process for manufacturing catalyst-coated ion-conducting membranes in roll-good form with precisely defined electrocatalyst decals.

[0087] Although the masking layer 8 and the electrocatalyst layer 2 are shown as separate layers which are fed in between the rollers 24, they may also be provided bonded together as a pre-formed masked electrocatalyst component.

[0088] FIG. 8 illustrates a flow diagram of a method for manufacturing a masked electrocatalyst component in accordance with an embodiment of the invention. Firstly, an electrocatalyst layer is provided 402 and a masking component comprising a masking layer is provided 404. The masking layer is then bonded 406 to the electrocatalyst layer to form a masked electrocatalyst component. Bonding is not required, but is preferred because it facilitates easier handling of the masked electrocatalyst material. The masking layer and the electrocatalyst layer may be bonded by, for example, an adhesive. The adhesive should preferably be thermally stable at the lamination temperatures used in a process for manufacturing a catalyst-coated ion-conducting membrane. For example, the adhesive may be a silicone pressure-sensitive adhesive.

[0089] FIG. 9 illustrates a flow diagram of a method for manufacturing a masked electrocatalyst component in accordance with another embodiment of the invention. An electrocatalyst layer is provided 402 and a masking component comprising a masking layer and a reinforcement layer is provided 403. The reinforcement layer helps to stabilise the masking layer and keep its shape while being brought into contact with the electrocatalyst layer. Before bonding 406 the masking layer to the electrocatalyst layer, the reinforcement layer can be removed 405 from the masking component. Alignment features may then be cut 410 into the masked electrocatalyst component.

[0090] Removing the reinforcement layer is not essential, but helps to minimise the thickness of the masking component during a process for manufacturing a catalyst-coated ion-conducting membrane. Removing the reinforcement layer also means that the reinforcement layer can be made from a polymer which does not need to be thermally stable at the lamination temperatures used during a process for manufacturing a catalyst-coated ion-conducting membrane.

[0091] FIGS. 10A and 10B illustrate model subsystems of a roll-to-roll based system for manufacturing a masked electrocatalyst component in accordance with an embodiment of the invention.

[0092] A masking component 60 comprising a masking layer and a reinforcement layer is fed into a rotary die cutter 62, which cuts apertures into the masking layer. A protective layer 64 covering pre-applied adhesive on the masking layer is also removed at this point. The masking component, now comprising apertures in the masking layer, is laid gently on the electrocatalyst layer 2. The masking component and electrocatalyst layer are laminated together between rollers 66. The reinforcement layer 68 is then peeled away from the masking layer by peel bar 70, leaving a masked electrocatalyst component 72 comprising the masking layer and the electrocatalyst layer.

[0093] Alignment features may be cut into the masked electrocatalyst component by a rotary die cutter 74. The masked catalyst component may then be wound onto a roll 76 for later use, if not fed directly into a process for manufacturing a catalyst-coated ion-conducting membrane.

[0094] It will be understood that the drawings used herein to illustrate embodiments of the invention are not made accurately to scale and are provided purely to aid in understanding the invention.