Distributor arrangement for distributing operating media in an electrochemical energy converter and its manufacture

Abstract

The invention presented relates to a distributor arrangement (100) for distributing operating media in an electrochemical energy converter, wherein the distributor arrangement (100) comprises: - a first transport layer (101) which consists at least partially of a carbon-containing material, - a second transport layer (103) which consists at least partially of a titanium-containing material, - a bipolar plate (105) which consists at least partially of a carbon-containing material, wherein the first transport layer (101) is integrally connected to both the bipolar plate (105) and the second transport layer (103) at least in regions.

Description

[0001] The presented invention relates to a distributor arrangement for distributing operating media in an electrochemical energy converter, a manufacturing method for producing a distributor arrangement for distributing operating media in an electrochemical energy converter and a cell for a cell stack of an electrochemical energy converter according to the appended claims. State of the art

[0002] It is known to use primarily titanium-based materials on the anode side of a PEM electrolysis cell of a PEM electrolysis stack, apart from a catalyst layer. This applies to porous transport layers (PTLs), which typically consist of sintered titanium particles and / or titanium fibers and / or titanium chips, as well as to flow distribution structures, such as titanium expanded metals or other open-pore structures, and a separating plate between an anode of one cell and a cathode of a neighboring cell of an electrolysis stack, also referred to as a bipolar plate.

[0003] A flow distribution structure can be embossed into the separating plate, e.g. in the form of channels, the negative of which simultaneously forms a flow distribution structure of the cathode.

[0004] Titanium-based materials are used in an anode because it is typically assumed that electrochemical potentials (compared to NHE) of > 1.3 V are present throughout the anode during electrolysis operation, at which graphite-based materials or stainless steels are not corrosion-resistant.

[0005] In addition, precious metal coatings such as gold or platinum group metals such as platinum or iridium are used as corrosion protection coatings due to their intrinsic high electrical conductivity and electrochemical stability within the operating window in order to minimize the formation of titanium dioxide over the operating period.

[0006] Since titanium-based materials and their standard coatings are extremely expensive and very difficult to process, e.g. due to very high tool wear when stamping titanium sheets, an at least partial replacement of titanium and electrically conductive corrosion protection layers with other materials is desirable in order to be able to produce PEM energy converters more cost-efficiently. Disclosure of the invention

[0007] Within the scope of the invention presented, a distributor assembly, a manufacturing method, and a cell for a cell stack of an electrochemical energy converter are presented. Further features and details of the invention emerge from the respective subclaims, the description, and the drawings. Features and details described in connection with the manufacturing method according to the invention naturally also apply in connection with the distributor assembly or the cell according to the invention, and vice versa, so that with regard to the disclosure of the individual aspects of the invention, reference is always made to each other.

[0008] The invention presented serves in particular to provide a possibility for the cost-efficient production of an electrochemical energy converter.

[0009] Thus, according to a first aspect of the invention presented, a distributor arrangement for distributing operating media in an electrochemical energy converter is presented.

[0010] The presented distributor arrangement comprises a first transport layer which consists at least partially of a carbon-containing material, a second transport layer which consists at least partially of a titanium-containing material, and a bipolar plate which consists at least partially of a carbon-containing material, wherein the first transport layer is integrally connected to both the bipolar plate and the second transport layer, at least in some regions.

[0011] The presented invention is based on a distributor arrangement for distributing operating media in an electrochemical energy converter, such as an electrolysis system or a fuel cell system, which comprises several layers, namely a bipolar plate which consists at least partially of carbon-containing material, in particular graphite-containing material, a first transport layer which consists at least partially of carbon-containing material, in particular graphite-containing material, and a second transport layer which consists at least partially of a titanium-containing material.

[0012] The three layers mentioned are at least partially bonded together and form a unit that is particularly mechanically stable and rigid and can therefore be easily further processed, e.g., supplemented to form a cell for an energy converter.

[0013] The first transport layer is arranged as an intermediate layer between the bipolar plate and the second transport layer and, due to the material-locking connections to the bipolar plate and the second transport layer, ensures a flat material connection with reduced contact resistance, media tightness and corrosion stability of the presented distributor arrangement.

[0014] The bonded connections between the first transport layer and the bipolar plate or the second transport layer can be achieved through a welding process or thermal joining. This significantly reduces the electrical contact resistance compared to purely mechanically connected layers, resulting in particularly low electrical voltage losses in the distribution arrangement, which leads to increased performance for an energy converter during cell operation.

[0015] The first transport layer and / or the second transport layer may comprise porous structures.

[0016] The first transport layer and / or the second transport layer can be coated on at least one side with a carbon-containing layer, in particular a graphite layer.

[0017] The first transport layer can be a structured film or layer or a flat body.

[0018] Due to the second transport layer, which consists at least partially of a carbon-containing material, the use of titanium for the production of the presented distributor arrangement can be minimized.

[0019] It may be intended that the carbonaceous material contains graphite.

[0020] In particular, the first transport layer can consist of a compacted carbon or a polymer matrix filled with carbon particles, in particular graphite particles or mixtures of graphite and other carbons, such as carbon black or hard carbon. The fill level can be >60%, preferably between 75% and 92%, particularly preferably at least 85%.

[0021] In particular, the first transport layer can be designed as a compacted layer with the same or different carbon particle sizes or particle fractions and, optionally, additionally with open porosity. The open porosity is preferably between 35 and 55%.

[0022] It can further be provided that the bipolar plate comprises a graphitic surface layer, via which the bipolar plate is integrally connected to the first transport layer at a plurality of interrupted regions with a structured surface of the first transport layer.

[0023] By means of a structured surface of the first transport layer, a plurality of channels, such as water supply channels, can be formed between the first transport layer and the bipolar plate.

[0024] It can further be provided that the first transport layer is integrally connected over its entire surface to a flat surface of the second transport layer.

[0025] By fully connecting the first transport layer to the second transport layer, a particularly strong and electrically and thermally conductive connection is achieved.

[0026] It can further be provided that the first transport layer is between 100 µm and 2000 µm thick and / or the second transport layer is between 200 µm and 1000 µm thick.

[0027] For example, the first transport layer can consist of graphite particles or fibers of 10-100 µm length or thickness and be stably compacted with a preferably open porosity of 35 - 55%.

[0028] It may further be provided that the thickness of the second transport layer is selected such that when using type 1 or type 2 DI water, an electrochemical potential within the second transport layer is below 1.1 V, measured against a standard hydrogen electrode.

[0029] It can further be provided that the first transport layer forms a conductive structure for conducting a medium on a side facing the bipolar plate and / or a side facing the second transport layer.

[0030] In particular, a surface of the first transport layer facing the bipolar plate can be structured with sufficiently large channel structures between 50 µm and 1000 µm thick and with a depth of up to 850 µm. Such structures can be created, for example, by an embossing process and / or by mechanical or thermal material removal, thus ensuring sufficient mechanical stability while still providing a sufficient water supply for catalytic conversion.

[0031] It can further be provided that the first transport layer has a perforation on a side facing the second transport layer.

[0032] For example, perforation can be achieved by embossing more rounded shapes such as semicircles or ellipses, or by embossing draft angles of > 11° for easy demolding. Alternatively, linear or vertical structures can be created through mechanical or thermal material removal. This allows channels to be formed that can be regular or irregular on the surface, two-dimensionally laterally, or three-dimensionally vertically in depth, with larger or smaller channels, angle-independent, or even in a wave shape.

[0033] Alternatively, the perforation can comprise, for example, round holes, which are configured in particular perpendicular to the body plane of the first transport layer or at an angle of < 20° to a vertical axis of the first transport layer. The holes can preferably occupy 30% to 80% of the surface of the first transport layer and can have a diameter between 30 µm and 500 µm. The holes can either be randomly distributed over the surface of the conductive structure or the first transport layer or can be formed in a regular pattern, e.g., at the corners of a hexagonal grid or at the corners of a square grid. The holes can all be the same size or different sizes.

[0034] It may further be provided that the bipolar plate is reinforced by a number of metal elements incorporated into the carbon-containing material.

[0035] A number of metal elements, such as a perforated plate or a plurality of metal plates, mechanically support the bipolar plate and, consequently, the distributor arrangement.

[0036] According to a second aspect, the presented invention relates to a manufacturing method for producing a distributor arrangement for distributing operating media in an electrochemical energy converter.

[0037] The presented manufacturing method comprises providing a material-to-material connection between a first transport layer, which consists at least partially of a carbon-containing material, and a second transport layer, which consists at least partially of a titanium-containing material, and providing a material-to-material connection between a bipolar plate, which consists at least partially of a carbon-containing material, and the first transport layer, wherein the respective material-to-material connections are provided by a resistance welding process.

[0038] The resistance welding process provided by the invention requires a materially bonded connection between the bipolar plate, the first transport layer, and the second transport layer. To this end, the resistance welding process can be carried out with a current between 5 A and 1000 A for a time period between 5 ms and 1000 ms, with continuous force tracking.

[0039] For example, a pre-welding ramp and a main welding ramp with 2x 1500ms for 2x 250ms can be used with a force adjustment of F=5N and an electrode contact speed of 5%.

[0040] It can be provided that the first transport layer forms a conductive structure for conducting a medium on a side facing the bipolar plate and / or a side facing the second transport layer and that electrodes are used in the resistance welding process which at least partially have a structured surface.

[0041] Electrodes, such as CuBe electrodes, which have an at least partially structured surface, enable a region-by-region connection or welding of a structured surface of the first transport layer to the bipolar plate, so that welding occurs only in the areas where the structured surface exhibits local maxima. Accordingly, the electrodes can have a surface structured corresponding to the first transport layer.

[0042] Furthermore, a large number of electrodes can be used to weld a large number of areas in parallel or sequentially.

[0043] It can further be provided that a proportion of a surface of the first transport layer, at which the first transport layer is integrally connected to the bipolar plate and / or the second transport layer, is between 30% and 90%.

[0044] The portion of the surface of the first transport layer at which the first transport layer is integrally connected to the bipolar plate and / or the second transport layer is determined by a width and length of local maxima of a structured surface of the first transport layer.

[0045] According to a third aspect, the presented invention relates to a cell for a cell stack of an electrochemical energy converter, wherein the cell comprises a possible embodiment of the presented distribution arrangement.

[0046] The cell presented can be, for example, a fuel cell or an electrolysis cell.

[0047] Advantages that are described in detail for the distributor arrangement for distributing operating media in an electrochemical energy converter according to the first aspect of the invention apply equally to the manufacturing method for producing a distributor arrangement for distributing operating media in an electrochemical energy converter according to the second aspect of the invention and the cell for a cell stack of an electrochemical energy converter according to the third aspect of the invention.

[0048] Further advantages, features, and details of the invention will become apparent from the following description, which describes exemplary embodiments of the invention in detail with reference to the drawings. The features mentioned in the claims and in the description may be essential to the invention individually or in any combination.

[0049] They show schematically: Fig. 1 a representation of a possible embodiment of the presented cell, which includes a possible embodiment of the presented distribution arrangement, and Fig. 2 a possible design of the presented manufacturing process.

[0050] In Fig. 1 shows a cell 200 for a cell stack of an electrochemical energy converter. The cell 200 includes a distribution assembly 100 for distributing operating media within the energy converter, an anode-side catalyst layer 201, a membrane 203, a cathode-side catalyst layer 205, a cathode-side gas diffusion layer 207, and an optional cathode flow distribution structure 209.

[0051] The distributor arrangement 100 comprises a first transport layer 101, which is integrally connected to a second transport layer 103 and a bipolar plate 105.

[0052] The first transport layer is in this case a graphitic porous plate which forms a structured surface 107 in the direction of the bipolar plate 105, so that water supply channels 109 are formed between the bipolar plate 105 and the first transport layer 101.

[0053] The bipolar plate 105 is a graphitic plate that is mechanically reinforced by metal elements 111.

[0054] The second transport layer 103 is a porous plate made of titanium or a titanium alloy and forms a flat boundary layer 113 to the first transport layer 101.

[0055] In Fig. 2 shows a manufacturing method 300 for producing a distributor arrangement for distributing operating media in an electrochemical energy converter.

[0056] The manufacturing method 300 comprises a first provision step 301 in which a material-locking connection is provided between a first transport layer, which consists at least partially of a carbon-containing material, and a second transport layer, which consists at least partially of a titanium-containing material.

[0057] Furthermore, the manufacturing method 300 comprises a second provision step 303 in which a material-locking connection is provided between a bipolar plate, which consists at least partially of a carbon-containing material, and the first transport layer.

[0058] The respective material connections are provided by a resistance welding process.

Claims

[1] Distribution arrangement (100) for distributing operating media in an electrochemical energy converter, the distribution arrangement (100) comprising: - a first transport layer (101) which consists at least partially of a carbon-containing material, - a second transport layer (103) which consists at least partially of a titanium-containing material, - a bipolar plate (105) which consists at least partially of a carbon-containing material, wherein the first transport layer (101) is integrally connected to both the bipolar plate (105) and the second transport layer (103) at least in regions. [2] Distributor arrangement (100) according to claim 1, characterized by that the carbonaceous material contains graphite. [3] Distributor arrangement (100) according to claim 1 or 2, characterized byin that the bipolar plate (105) comprises a graphitic surface layer, via which the bipolar plate (105) is materially connected to the first transport layer (101) at a plurality of interrupted regions with a structured surface of the first transport layer (101). [4] Distributor arrangement (100) according to one of the preceding claims, characterized by that the first transport layer (101) is integrally connected over its entire surface to a flat surface of the second transport layer (103). [5] Distributor arrangement (100) according to one of the preceding claims, characterized by that the first transport layer (101) is between 100 µm and 2000 µm thick and / or the second transport layer (103) is between 200 µm and 1000 µm thick. [6] Distributor arrangement (100) according to one of the preceding claims, characterized by that the first transport layer (101) is a film or a plate. [7] Distributor arrangement (100) according to one of the preceding claims, characterized by that the first transport layer (101) forms a conductive structure for conducting a medium on a side facing the bipolar plate (105) and / or a side facing the second transport layer (103). [8] Distributor arrangement (100) according to one of the preceding claims, characterized by that the bipolar plate (105) is reinforced by a number of metal elements (111) introduced into the carbon-containing material. [9] Manufacturing method (300) for producing a distributor arrangement (100) for distributing operating media in an electrochemical energy converter, the manufacturing method (300) comprising: - providing (301) a material-to-material connection between a first transport layer (101), which consists at least partially of a carbon-containing material, and a second transport layer (103), which consists at least partially of a titanium-containing material, - Providing (303) a material-to-material connection between a bipolar plate (105) which consists at least partially of a carbon-containing material and the first transport layer (101), wherein the respective material-to-material connections are provided by a resistance welding process. [10] Manufacturing method (300) according to claim 9, characterized bythat the first transport layer (101) forms a conductive structure for conducting a medium on a side facing the bipolar plate (105) and / or a side facing the second transport layer (103), and that electrodes which at least partially have a structured surface are used in the resistance welding process. [11] Manufacturing method (300) according to claim 10, characterized by that a proportion of a surface of the first transport layer (101) at which the first transport layer (101) is integrally connected to the bipolar plate (105) and / or the second transport layer (103) is between 30% and 90%. [12] Cell (200) for a cell stack of an electrochemical energy converter, wherein the cell (200) comprises a distribution arrangement (100) according to one of claims 1 to 8.

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