LAYER SYSTEM, FLOW FIELD PLATE HAVING A LAYER SYSTEM OF THIS TYPE, AND FUEL CELL, ELECTROLYZER OR REDOX FLOW CELL

Abstract

A layer system for coating a metal substrate in order to form a flow field plate includes at least one cover layer made of metal oxide; at least one intermediate layer, which supports the cover layer; and a lower layer, which supports the intermediate layer(s). The cover layer is formed of indium tin oxide; wherein the indium tin oxide is optionally doped with at least one element from the group comprising carbon, nitrogen, boron, fluorine, hydrogen, silicon, titanium, tin and zirconium. At least one intermediate layer is formed of titanium nitride and/or titanium carbide and/or titanium carbonitride and/or titanium niobium nitride and/or titanium niobium carbide and/or titanium niobium carbonitride and/or chromium nitride and/or chromium carbide and/or chromium carbonitride. The lower layer is formed of titanium or a titanium-niobium alloy or chromium.

Claims

1. A layer system for coating a metal substrate to form a flow field plate, comprising: at least one cover layer made of metal oxide, at least one intermediate layer supporting the cover layer and a lower layer supporting the intermediate layer, wherein the cover layer is formed from indium tin oxide, wherein the indium tin oxide is doped with at least one element from group comprising carbon, nitrogen, boron, fluorine, hydrogen, silicon, titanium, tin, and zirconium, wherein the at least one intermediate layer is formed from titanium nitride or titanium carbide or titanium carbonitride or titanium niobium nitride or titanium niobium carbide or titanium niobium carbonitride or chromium nitride or chromium carbide or chromium carbonitride, and wherein the lower layer is formed from titanium or a titanium-niobium alloy or chromium.

2. The layer system according to claim 1, wherein the cover layer made of indium tin oxide has an indium content in a range from 70 to 90 vol %.

3. The layer system according to claim 1, wherein the lower layer has a layer thickness in a range from 1 to 300 nm.

4. The layer system according to claim 1, wherein the at least one intermediate layer has a layer thickness in range from 0.1 μm to 3.0 μm.

5. The layer system according to claim 1, wherein the cover layer has a layer thickness in a range from 0.01 μm to 15 μm.

6. The layer system according to claim 1, wherein the cover layer is doped with at least one element from a group comprising carbon, nitrogen, boron, fluorine, hydrogen, silicon, titanium, tin and zirconium of at most 35 at %.

7. A flow field plate comprising a metal substrate and a layer system according to claim 1, having a structure of the flow field plate in the order: metal substrate, lower layer, intermediate layer(s), and cover layer.

8. The flow field plate according to claim 7, wherein the metal substrate is formed from steel.

9. A fuel cell, comprising at least one flow field plate according to claim 7.

10. The fuel cell according to claim 9, comprising at least one polymer electrolyte membrane.

11. The layer system according to claim 1, wherein the cover layer is doped with at least one element from a group comprising carbon, nitrogen, boron, fluorine, hydrogen, silicon, titanium, tin and zirconium in a range from 0.1 to 10 at %.

12. The fuel cell according to claim 9, wherein the fuel cell is an oxygen-hydrogen fuel cell or electrolyzer or redox flow cell.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0029] FIGS. 1 to 3 are intended to explain, by way of example, a layer system according to the disclosure, a flow field plate formed therewith and a fuel cell. In the figures:

[0030] FIG. 1 shows a flow field plate having the layer system;

[0031] FIG. 2 schematically shows a fuel cell system comprising a plurality of fuel cells;

[0032] FIG. 3 shows an enlarged view of a cross section through a layer system shown by way of example.

DETAILED DESCRIPTION

[0033] FIG. 1 shows a flow field plate 2 having a layer system 1, which here has a metal substrate 2a or a metal carrier plate made of austenitic steel. The flow field plate 2 has an inflow region 3a with openings 4 and an outlet region 3b with further openings 4′, which are used to supply a fuel cell with process gases and to remove reaction products from the fuel cell. The flow field plate 2 also has a gas distribution structure 5 on each side, which is provided for contact with a polymer electrolyte membrane 7 (see FIG. 2).

[0034] FIG. 2 schematically shows a fuel cell system 100 comprising a plurality of fuel cells 10. Each fuel cell 10 comprises a polymer electrolyte membrane 7 which is adjacent to both sides of the flow field plates 2, 2′. The same reference signs as in FIG. 1 indicate identical elements.

[0035] FIG. 3 shows a cross section through the layer system 1 according to FIG. 1. It can be seen that a cover layer 1a, an intermediate layer 1b and a lower layer 1c are present. The lower layer 1c is disposed on a side B of the layer system 1 which is arranged facing the substrate 2a of the flow field plate 2. The cover layer 1a is disposed on a side A of the layer system 1 which is arranged facing away from the substrate 2a of a flow field plate 2. Alternatively, the layer system 1 can also have a plurality of intermediate layers 1b.

LIST OF REFERENCE SYMBOLS

[0036] 1 Layer system [0037] 1a Cover layer [0038] 1b Intermediate layer(s) [0039] 1c Lower layer [0040] 2, 2′ Flow field plate [0041] 2a Metal substrate [0042] 3a Inflow region [0043] 3b Outlet region [0044] 4, 4′ Opening [0045] 5 Gas distribution structure [0046] 7 Polymer electrolyte membrane [0047] 10 Fuel cell [0048] 100 Fuel cell system [0049] A Side of the layer system 1 facing away from the substrate 2a [0050] B Side of the layer system 1 facing the substrate 2a