Membrane electrode assemblies and method for manufacture
Reel-to-Reel method for making membrane electrode assemblies. A first catalyst is deposited in a repeating cell pattern on a first side of a proton exchange membrane film. A second catalyst is deposited on the back side of the proton exchange membrane. An electron conductor material is deposited on a support film which is adhered by means of an adhesive film to the proton exchange membrane film. The various layers are aligned and laminated together to form the membrane electrode assembly.
Membrane electrode assemblies (MEA) are the core of fuel cells such as proton exchange media fuel cells which are well known. See, for example, “Fuel Cell Systems Explained,” Larminie & Dicks, John Wylie & Sons, Ltd. (2000), the contents of which are incorporated herein by reference. Membrane electrode assemblies contain the electron collectors, the catalyst, and the proton exchange medium. Current methods of production of MEAs focus on individual units in which the catalysts are chemically deposited or inked on an electron collector and proton exchange medium. The elements of the unit are then sandwiched together with the application of heat and pressure to produce a single MEA. This prior art method is both costly and not easily scaled up to high volume production.
SUMMARY OF THE INVENTIONIn one aspect, the invention is a method for making a membrane electrode assembly including providing an elongate proton exchange membrane film having a front and a back side. A first catalyst material is deposited in a repeating cell pattern on the front side of the film to form cathode regions of a plurality of unit cells. A second catalyst material is deposited in the repeating pattern on the back side of the film to form anode regions of the unit cells. An elongate support film perforated in the repeating cell pattern is provided and electron conductor material is deposited onto the support film in the repeating cell pattern along with electrical contact nubs. An adhesive film precut in the repeating cell pattern is also provided and the support and adhesive films are assembled on the front and back sides of the proton exchange membrane film with the repeating patterns of the respective films aligned and with the unit cells connected electrically. The assembled films are passed through hot rollers to laminate the films to produce the assembly.
BRIEF DESCRIPTION OF THE DRAWING
As set forth above, the method for making a membrane electrode assembly includes providing an elongate proton exchange membrane film having a front and back side. A first catalyst material is deposited in a repeating cell pattern on the front side of the film to form cathode regions of a plurality of unit cells. A second catalyst material is deposited in the repeating pattern on the back side of the film to form anode regions of the unit cells. An elongate support film- perforated in the repeating cell pattern is provided and electron conductor material is deposited onto the support film in the repeating cell pattern along with electrical contact nubs. An adhesive film pre-cut in the repeating cell pattern is also provided and the support and adhesive films are assembled on the front and back sides of the proton exchange membrane film with the repeating patterns of the respective films aligned and with the unit cells connected electrically.
A suitable proton exchange membrane film is Nafion® available from Dupont Chemical Corporation. Nafion is basically sulphonated polytetrafluoroethylene. A suitable first catalyst material is platinum and a suitable second catalyst material is platinum-ruthenium.
In a preferred embodiment, a suitable support film is Kapton. Suitable electronic conductor materials are thin film carbon and thin film metals. The unit cells made according to the present invention may be connected electrically in series or in parallel.
It is preferred that the proton exchange membrane, the support film, and the adhesive film be fed from respective rolls and that the completed membrane electrode assembly is in the form of a continuous roll of material.
In another aspect, the invention is a fuel cell including a Z-folded strip including a plurality of electrically connected membrane electrode assemblies as described above. A pair of endplates support the Z-folded strip to create alternating anode and cathode chambers. Alternating fuel and air manifolds are provided in the endplates to complete a fuel cell.
The present invention thus produces membrane electrode assemblies in a reel-to-reel process. The method according to the invention allows MEAs to be constructed in a continuous process wherein each cell is connected electrically to the next either in series or in parallel as desired. With a series connection the desired voltage is proportional to the number of cells so that one simply chooses the appropriate number of cells and cuts them from the reel to form them into a stack. Alternatively, stacks themselves may be connected in series or parallel. The continuous production process of the invention is low cost and scalable to very high volume. The cells are internally connected, in series or in parallel, and any desired voltage may be selected by-using the appropriate number of cells.
With reference to
With reference to
With reference to
With reference to
The overall process is shown in general terms in
As shown in
An alternative process referred to as a roll transfer lamination process is shown in
The process illustrated in
The roll transfer lamination process of
With reference now to
Modifications and variations of the invention disclosed herein will occur to those skilled in the art and it is intended that all such modifications and variations be included within the scope of the appended claims.
Claims
1-14. (canceled)
15. A membrane electrode assembly, comprising:
- an elongate proton exchange membrane (“PEM”) film having first and second sides;
- a plurality of spaced cathodes on the first side of the PEM film;
- a plurality of spaced anodes on the second side of the PEM film respectively substantially aligned with the plurality of spaced cathodes such that the substantially aligned anodes and cathodes and portions of the PEM film therebetween define a plurality of spaced unit cells; and
- conductive material electrically connecting adjacent unit cells.
16. A membrane electrode assembly as claimed in claim 15, wherein the spaced unit cells are connected in series.
17. A membrane electrode assembly as claimed in claim 15, wherein the spaced unit cells are connected in parallel.
18. A membrane electrode assembly as claimed in claim 15, wherein the conductive material comprises a plurality of contact nubs.
19. A membrane electrode assembly as claimed in claim 18, wherein
- wherein each unit cell has at least one of the contact nubs connected thereto;
- the PEM film includes a plurality of contact nub apertures; and
- the contact nubs of adjacent unit cells are connected to one another by way of the PEM film contact nub apertures.
20. A membrane electrode assembly as claimed in claim 15, wherein the PEM film comprises sulphonated polytetravluoroethylene film.
21. A membrane electrode assembly as claimed in claim 15, wherein
- the plurality of spaced cathodes comprise a plurality of spaced cathode catalyst material regions on the PEM film and a plurality of cathode conductor regions associated with the cathode catalyst material regions; and
- the plurality of spaced anodes comprise a plurality of spaced anode catalyst material regions on the PEM film and a plurality of anode conductor regions associated with the anode catalyst material regions.
22. A membrane electrode assembly as claimed in claim 21, wherein the cathode catalyst material comprises platinum.
23. A membrane electrode assembly as claimed in claim 21, wherein the anode catalyst material comprises platinum-ruthenium.
24. A membrane electrode assembly as claimed in claim 21, wherein the anode and cathode conductor regions comprise thin film carbon regions.
25. A membrane electrode assembly as claimed in claim 21, wherein the anode and cathode conductor regions comprise thin film metal regions.
26. A membrane electrode assembly as claimed in claim 21, wherein
- the plurality of spaced cathode conductor regions are carried on a support film having a plurality of spaced perforation regions associated with the spaced cathode conductor regions; and
- the plurality of spaced anode conductor regions are carried on a support film having a plurality of spaced perforation regions associated with the spaced anode conductor regions.
27. A membrane electrode assembly as claimed in claim 26, wherein the support film comprises polyimide film.
28. A membrane electrode assembly as claimed in claim 15, wherein the PEM film includes a plurality of folds shaped and positioned such that anodes face one another across respective gaps that define fuel chambers and cathodes face one another across respective gaps that define oxidant chambers.
29. A membrane electrode assembly as claimed in claim 28, wherein the spaced unit cells are connected in series.
30. A membrane electrode assembly as claimed in claim 28, further comprising wicking material located within the fuel chambers.
Type: Application
Filed: Mar 29, 2006
Publication Date: Aug 3, 2006
Inventor: Marzio Leban (Corvallis, OR)
Application Number: 11/391,973
International Classification: H01M 4/88 (20060101); B05D 5/12 (20060101); H01M 8/10 (20060101); H01M 8/24 (20060101);