BIPOLAR PLATE ASSEMBLY, USE OF A BIPOLAR PLATE ASSEMBLY, AND ELECTROLYSIS OR FUEL CELL STACK COMPRISING A PLURALITY OF BIPOLAR PLATE ASSEMBLIES

Abstract

The invention relates to a bipolar plate assembly (1) for forming an electrolysis or fuel cell stack and to the use of a bipolar plate assembly and an electrolysis or fuel cell stack with a plurality of bipolar plate assemblies.

Claims

1. Bipolar plate assembly (1) for forming an electrolysis or fuel cell stack, comprising a metallic separating device (2) adapted to create a fluid-tight seal between the anode side (5) and the cathode side (6), and provided with fluid supply channels (10) and fluid discharge channels (11) on both the anode and cathode sides, respectively, two metallic flow distributor units (3) arranged adjacent to the separating device (2) on the anode and cathode sides, each flow distributor unit (3) being designed to distribute a fluid supplied to it via the separating device (2) between the fluid supply channels (10) and the fluid discharge channels (11), and metallic frame elements (4) which are connected in a fluid-tight manner to the separating device (2) and which each surround one of the flow distributor units (3) circumferentially in a fluid-tight manner, the frame elements (4) having through-openings (12) which are designed to supply a fluid to the fluid supply channels (10) and through-openings (12) which are designed to discharge a fluid discharged via the fluid discharge channels (11).

2. Bipolar plate assembly (1) according to claim 1, wherein the separating device (2) and the frame elements (4) each have a rectangular outer circumference, the outer circumferences being designed in particular to be congruent.

3. Bipolar plate assembly (1) according to claim 1, wherein all through-openings (12) of one frame element (4) are positioned in alignment with the through-openings (12) of the other frame element (4), and wherein the separating device (2) is provided with through-holes (9) positioned in alignment with the through-openings (12) of the frame elements (4) and connecting them with the fluid supply channels (10) and fluid discharge channels (11) of the separating device (2)

4. Bipolar plate assembly (1) according to claim 1, wherein the anode-side fluid supply channels (10) and the anode-side fluid discharge channels (11) are arranged opposite one another, wherein the cathode-side fluid supply channels (10) and the cathode-side fluid discharge channels (11) are arranged opposite one another, and wherein the anode-side fluid supply channels (10) and the cathode-side fluid supply channels (10) are arranged offset by 90° with respect to one another.

5. Bipolar plate assembly (1) according to claim 4, wherein the fluid supply channels (10) and the fluid discharge channels (11) are provided in the form of grooves formed on the anode-side and cathode-side surfaces of the separating device (2) and extending inwardly from the through holes (9).

6. Bipolar plate assembly (1) according to claim 1, wherein the separating device (2) consists of a single separating plate.

7. Bipolar plate assembly (1) according to claim 1, wherein the separating device (2) has two separating plates which are firmly connected to one another, in particular soldered or welded to one another.

8. Bipolar plate assembly (1) according to claim 1, wherein the flow distributor units (3) are made of layers having recurring passages, in particular of layers in the form of expanded metals, fabrics and/or nonwovens.

9. Bipolar plate assembly (1) according to claim 8, wherein the size of the passages of at least one flow distributor unit (3), in particular of both flow distributor units (3), increases in the direction of the separating device (2).

10. Bipolar plate assembly (1) according to claim 1, wherein the separating device (2) and/or at least one of the flow distributor units (3) and/or the frame elements (4) are made of a corrosion-resistant metal or are provided with a corrosion-resistant metal coating.

11. Bipolar plate assembly (1) according to claim 1, wherein the separating device (2), the flow distributor units (3) and the frame elements (4) are soldered or welded together.

12. Bipolar plate assembly (1) according to claim 1, wherein a metallic gas diffusion layer (8) is attached from the outside to one of the flow distributor units (3), in particular by means of soldering or welding, preferably to the flow distributor unit (3) arranged on the anode side.

13. Use of a bipolar plate assembly (1) according to claim 1 to form an electrolysis or fuel cell stack.

14. Electrolysis or fuel cell stack comprising a plurality of bipolar plate assemblies (1) according to claim 1.

15. Bipolar plate assembly (1) according to claim 2, wherein all through-openings (12) of one frame element (4) are positioned in alignment with the through-openings (12) of the other frame element (4), and wherein the separating device (2) is provided with through-holes (9) positioned in alignment with the through-openings (12) of the frame elements (4) and connecting them with the fluid supply channels (10) and fluid discharge channels (11) of the separating device (2)

16. Bipolar plate assembly (1) according to claim 2, wherein the anode-side fluid supply channels (10) and the anode-side fluid discharge channels (11) are arranged opposite one another, wherein the cathode-side fluid supply channels (10) and the cathode-side fluid discharge channels (11) are arranged opposite one another, and wherein the anode-side fluid supply channels (10) and the cathode-side fluid supply channels (10) are arranged offset by 90° with respect to one another.

17. Bipolar plate assembly (1) according to claim 3, wherein the anode-side fluid supply channels (10) and the anode-side fluid discharge channels (11) are arranged opposite one another, wherein the cathode-side fluid supply channels (10) and the cathode-side fluid discharge channels (11) are arranged opposite one another, and wherein the anode-side fluid supply channels (10) and the cathode-side fluid supply channels (10) are arranged offset by 90° with respect to one another.

Description

[0026] Further advantages and features of the present invention will become apparent from the following description of a bipolar plate assembly according to one embodiment of the present invention, with reference to the accompanying drawing. Therein is

[0027] FIG. 1 a perspective exploded view of a bipolar plate assembly according to one embodiment of the present invention;

[0028] FIG. 2 another perspective exploded view of the bipolar plate assembly;

[0029] FIG. 3 a cathode side view of a separation device of the bipolar plate assembly;

[0030] FIG. 4 an anode-side view of the separating device;

[0031] FIG. 5 a perspective exploded view of a cathode-side flow distribution unit shown in FIG. 1;

[0032] FIG. 6 a partial perspective view of the flow distributor unit in the assembled state;

[0033] FIG. 7 a partial side view of the flow distribution unit in the direction of arrow VII in FIG. 6;

[0034] FIG. 8 a partial side view of the flow distribution unit in the direction of arrow VIII in FIG. 6;

[0035] FIG. 9 a sectional view of a portion of the assembled bipolar plate and

[0036] FIG. 10 a sectional view of a portion of the assembled bipolar plate as in FIG. 9 with flow drawn through.

[0037] FIGS. 1, 2 and 9 show a bipolar plate assembly 1 according to one embodiment of the present invention, which has as main components a substantially centrally arranged metallic separating device 2, two metallic flow distributor units 3, which are each arranged adjacent to the separating device 2, and two metallic frame elements 4, which each surround the flow distributor units 3 in a circumferentially gas-tight manner in the assembled state of the bipolar plate assembly 1. The separating device 2 separates the bipolar plate assembly 1 into an anode side 5 and a cathode side 6, the separation being symbolized by a dashed line 7 in FIGS. 1, 2 and 9 respectively. The anode side 5 is located on the left in FIGS. 1 and 2 in each case and above the dashed line 7 in FIG. 9, the cathode side 6 is located on the right in FIGS. 1 and 2 and below the dashed line 7 in FIG. 9. As a further main component, a metallic gas diffusion layer 8 covering the outward-facing surface of the flow distributor unit 3 is provided on the anode side, but is in principle optional and can also represent a component of an associated-membrane-electrode unit.

[0038] The metallic separating device 2 is designed to create a fluid-tight seal between the anode side 5 and the cathode side 6. In the present case, it consists of a single separating plate in the form of a metal sheet. In principle, however, it is also possible to form the separating device 2 from two separating device plates which are then firmly connected to one another, for example by means of soldering or welding. The separating device 2 has a rectangular, in the present case square, outer circumference and is provided along its plate edges with through-holes 9, which are preferably arranged at regular intervals from one another. On two opposite plate edges of one plate side, for example on the plate side facing the anode side 5, additional groove-like channels or blind holes extending inwards in the direction of the plate center are provided starting from the through-holes 9, the channels extending along one plate edge forming fluid supply channels 10 and the channels extending along the opposite plate edge forming fluid discharge channels 11. The depth of the fluid supply channels 10 and fluid discharge channels 11 is in each case less than the plate thickness. On the other side of the plate, these additional channels forming fluid supply channels 10 and fluid discharge channels 11 are also provided, but at those through-holes 9 which extend along the plate edges offset by 90°. Thus, there is never another fluid supply channel 10 or fluid discharge channel 11 on the rear side of a fluid supply channel 10 or fluid discharge channel 11.

[0039] The metallic frame elements 4 are likewise square in shape, analogously to the separating device 2, the outer circumference of the frame elements 4 each being adapted to the outer circumference of the separating device 2. Each frame element 4 is provided along its side edges with through-openings 12, the number and position of which correspond to the number and position of the through-holes 9 of the separating device 2, so that the through-openings 12 of the frame elements 4 and the through-holes 9 of the separating device 2 are aligned with each other as soon as the frame elements 4 are placed on both sides of the separating device 2 in the intended manner.

[0040] The metallic flow distributor units 3 are each formed by a composite of expanded metals, although metallic fabrics, nonwovens or the like can also be used in principle. The expanded metals used each have passages 13 of different sizes and thus different porosities. In the embodiment shown, an expanded metal combination of three different expanded metals is selected. A coarse expanded metal, which is arranged facing the separating device in each case, provides the coarse flow distribution and mechanical support. The medium and fine expanded metal are used to distribute the contact force and flow to the active cell surface. The materials of the flow distribution units 3 are precisely inserted into the inner circumference of the frame elements 4. The structure of the materials for flow distribution on the anode side 5 and cathode side 6 may well be different. In the present case, the expanded metal composite is also rotated 90° to each other for the anode and cathode. The thicknesses of the materials and the associated frame elements 4 are matched to each other, taking into account the subsequent joining process.

[0041] All components are made of titanium, although other metallic materials that meet the subsequent requirements, in particular with regard to corrosion resistance, can also be used.

[0042] To assemble the bipolar plate assembly 1, the individual components are preferably joined using a thermal joining process, in this case using a diffusion bonding process. All components of the bipolar plate assembly 1 are placed on top of each other according to the intended structure and placed in a heatable vacuum furnace. In addition, the furnace contains a pressing device that can be moved by force and path control. The bipolar plate components are welded together at the contact points by a suitable combination of process atmosphere, if necessary inert gas (usually vacuum <10 exp−4 mbar), vacuum, temperature, pressing force and process time. The process parameters to be set essentially depend on the materials of the individual components and their size and design.

[0043] In the electrolysis or fuel cell stack, the bipolar plate assembly 1 forms a repeating unit, as does the membrane electrode unit. To produce an electrolysis or fuel cell stack, the repeating units are stacked accordingly and connected to each other in a manner known in and of itself, for example by using end plates and clamping elements pressed onto each other. Fluid or media is supplied or removed separately for the anode and cathode compartments. Each row of holes extending along a side edge of the assembled electrolytic or fuel cell stack, consisting of through holes 9, through openings 12 and fluid supply or fluid discharge channels 10, 11, represents the fluid supply or fluid discharge for the anode side 5 and cathode side 6, respectively. Supply and discharge always take place via opposite rows of holes. Thus, the connections for the anode compartments are rotated 90° to the connections for the cathode compartments. A cross-flow configuration is formed with respect to the fluids in the anode and cathode compartments. Typically, the fluids are connected to the electrolysis or fuel cell stack by means of a conduit. In this case, an elongated manifold, not shown in detail here, is still to be provided outside or inside the stack to distribute the supplied fluid from the conduit to the individual rows of holes. When fluid is supplied via a row of holes, there is a division into two partial flows when flowing through a bipolar plate assembly 1. The flow through the cross-section of the bipolar plate assembly is indicated in FIG. 10 by corresponding arrows 14. This division is determined by the assembly of the fluid supply channels 10 and the fluid discharge channels 11 of the separating device 2. The partial flow diverted in these channels has access to the flow distribution units 3 and is introduced into the coarse expanded metal from below. This is made possible by the fact that the fluid supply channels 10 extend further into the interior of the plate than the frame elements 4. The outflow of the fluids takes place correspondingly through the opposite fluid discharge channels 11. By rotating the fluid supply channels 10 and fluid discharge channels 11 on the anode side 5 and the cathode side 6 by 90°, the electrochemical cell is operated in cross-flow.

LIST OF REFERENCE SIGNS

[0044] 1 bipolar plate assembly [0045] 2 separating device [0046] 3 flow distributor unit [0047] 4 frame element [0048] 5 anode side [0049] 6 cathode side [0050] 7 dashed line [0051] 8 gas diffusion layer [0052] 9 through-hole [0053] 10 fluid supply channel [0054] 11 fluid discharge channel [0055] 12 through-opening [0056] 13 passage [0057] 14 arrows