METHOD FOR PRODUCING A GREEN PAPER FOR PRODUCING A GAS DIFFUSION LAYER FOR A FUEL CELL

Abstract

A method is provided for producing a green paper for producing a gas diffusion layer (GDL) for a fuel cell. A first paper web is formed, and a second paper web is formed, which are brought together with and rigidly connected to the first paper web while still wet. The first paper web and the second paper web are mixed with metal powder and/or metal fibers and together form the green paper, optionally together with additional components and/or coatings. The final GDL is provided after a binding-removal process, a sintering process, a coating process, a (thermal) deposition process (atomic layer deposition process, ALD), and optionally additional process steps.

Claims

1-9. (canceled)

10. A process for producing a green paper for production of a gas diffusion layer (GDL) for a fuel cell, wherein a first paper web is formed and a second paper web is formed, and the latter, in the still-moist state, is combined with and firmly bonded to the first paper web, where the first paper web and the second paper web together form the green paper.

11. The process according to claim 10, wherein the first and/or second paper web is produced in a cylindrical paper machine.

12. The process according to claim 10, wherein the first and/or second paper web is produced in a short former in which the paper stock is jetted onto a cylindrical screen.

13. The process according to claim 10, wherein the first paper web has a higher density than the second paper web, the first paper web having a density of 3 g/cm.sup.3 to 10 g/cm.sup.3, and the second paper web a density of 1 g/cm.sup.3 to 5 g/cm.sup.3.

14. The process according to claim 13, wherein the first paper web is formed by a finer paper stock slurry than the second paper web.

15. The process according to claim 10, wherein the first and/or second paper web includes added metal powders and/or metal fibers.

16. The process according to claim 10, wherein the fuel cell is a proton exchange membrane fuel cell (PEMFC), a proton exchange membrane electrolyzer cell (PEMEC), an electrolyzer cell or another power-to-x technology which requires correspondingly porous conductive material for gas/stream/reactant distribution.

17. The process according to claim 10, wherein the first paper web in the gas diffusion layer (GDL) produced from the green paper forms a diffusion layer for a membrane (CL) coated with catalytic metal, platinum, and the second paper web in the gas diffusion layer (GDL) produced from the green paper forms a distribution layer with a flow field.

18. The process according to claim 10, wherein a watermark is made in the first paper web and in the second paper web, where the structures of the watermark in the first paper web and of the watermark in the second paper web are not identical but have exact mirror symmetry in the plane and in the direction of material thickness.

Description

THE FIGURES SPECIFICALLY SHOW, IN SCHEMATIC FORM

[0026] FIG. 1 a schematic diagram of a double cylinder paper machine for production of a green paper of the invention,

[0027] FIG. 2 a paper machine with a cylindrical paper machine and a short former in a schematic diagram.

[0028] FIG. 1 shows, in a schematic diagram, a double-cylinder paper machine 10, as known, for example, from WO 2006/099971 A2 for the production of security paper. The paper machine 10 contains two cylindrical paper machines 12 and 14, which are connected to one another via a transfer felt 16.

[0029] In the first paper machine 12, a paper web 20 is formed on a cylindrical screen 18. In the second paper machine 14, in parallel, a second, homogeneous paper web 30 is produced, removed from the cylindrical screen 34 by means of the transfer felt 16, and guided to the first paper machine 12, where it is combined with the first paper web 20 in the region of the contact roll 36. The combined paper webs 38 collectively form the GDL and are sent to further processing stations.

[0030] The second paper web 30 may, as shown in FIG. 2, also be produced with a short former 40 in which the paper stock is jetted onto the surface of a cylindrical screen 44 with a headbox nozzle 42. Such a short former can be used to produce particularly thin paper plies, for example with a gram weight of 15 to 25 g/m.sup.2.

[0031] It will be apparent that the paper machines 12, 14, 40 shown can also be used in an analogous manner to produce and combine three or more paper webs.