Electrode frame for an electrochemical cell stack

Abstract

The invention relates to an electrode frame (100) for an electrochemical cell stack, in particular an electrolysis cell stack or a fuel cell stack, wherein the electrode frame (100) runs around its electrode space through-hole (103) in the circumferential direction (Ur) for the radial (Rr) fluid sealing of an electrode space of the cell stack extending in the axial direction (Ax), wherein the electrode frame (100) comprises an outer frame (120) running around the outside and an inner frame (110) with the electrode space through-hole (103) radially (Rr) therein, wherein a representative volume element of the outer frame (120) is designed to be stiffer than a representative volume element of the inner frame (110) of the same size.

Description

[0001] The invention relates to an electrode frame and a cell layer for an electrochemical cell stack. Furthermore, the invention relates to an electrochemical cell stack, an electrochemical assembly, and an electrochemical system, in particular an electrolyzer system or a fuel cell system. State of the art

[0002] During electrolysis (AEM-EL, PEM-EL, AEL, etc.; see below) using an electrolyzer unit, e.g., an electrolysis system (stationary or mobile) or, if applicable, an electrolysis plant (stationary), water molecules are electrochemically split into hydrogen and oxygen using electrical energy, generating heat. The electrolyzer unit comprises at least one membrane electrode device (membrane with transport layers and electrodes arranged between them), e.g., an AEM (anion exchange membrane), a PEM (proton exchange membrane), or a diaphragm (AEL: alkaline electrolysis). Typically, the electrolyzer unit is configured with a plurality of membrane electrode devices arranged in a stack with bipolar plates arranged between them, the so-called electrolysis cell stack (stack) with a plurality of individual electrolysis cells (individual cells). Task

[0003] Efforts are constantly underway to improve electrolyzer units and fuel cell units and to design them cost-effectively with regard to their materials, manufacturing costs, and / or maintenance costs. It is an object of the invention to provide an improved, particularly cost-effective cell stack layer for an electrochemical cell stack, in particular an electrolysis cell stack or a fuel cell stack. Disclosure of the invention

[0004] The object of the invention is achieved by means of an electrode frame and a cell layer for an electrochemical cell stack; by means of an electrochemical cell stack, in particular an electrolysis cell stack or a fuel cell stack, for an electrochemical unit; by means of an electrochemical unit, in particular an electrolyzer unit or a fuel cell unit; and an electrochemical system, in particular an electrolyzer system or fuel cell system. Advantageous developments, additional features and / or advantages of the invention emerge from the dependent claims and the following description.

[0005] A cell stack, for example, of an electrolyzer, comprises a multitude of stacked individual electrochemical cells, which are secured to the electrolysis cell stack by mechanical bracing. Each individual cell requires an electrode frame for an anode compartment and a cathode compartment of the individual cell. The functions of these electrode frames are: conducting media (water or alkali, hydrogen, oxygen; two-phase mixtures thereof), sealing (between the media paths, from the environment), ensuring the pressure resistance of the electrolysis cell stack (up to over approx. 40 bar operating pressure, approx. 68 bar test pressure, with high-pressure electrolysis up to over 100 bar), electrically insulating a respective individual anode or cathode, and preventing physical contact between hydrogen and metal (metal alloy).

[0006] The electrode frame according to the invention runs circumferentially around its electrode chamber passage recess for radially sealing an electrode chamber of the axially extending cell stack. The electrode frame comprises an outer frame running around the outside and an inner frame with the electrode chamber passage recess radially therein. A representative volume element of the outer frame is designed to be stiffer than a representative volume element of the same size of the inner frame. The electrolysis cell stack can be designed, for example, as a PEM, an AEM, an AEL (alkaline electrolysis), or a CO2 electrolysis cell stack, and the fuel cell stack can be designed, for example, as a PEM or an AEM fuel cell stack. The electrolysis cell stack can be designed, in particular, for high-pressure electrolysis.

[0007] Within the scope of this specification, one or all radial directions (in particular as combinations of the width and transverse directions of the cell stack) are perpendicular to an axial stacking direction (axial direction or vertical direction) of the cell stack, whose electrode frames preferably completely encircle the axial direction in the circumferential direction. - The representative volume element in question is naturally a mathematical object, i.e., a mathematical volume shape, with volume elements of equal size having both the same volume and the same shape. And "representative" is to be understood as meaning that the volume element is a volume element typical of the inner frame or the outer frame and thus, if sufficiently small, is essentially arbitrary.

[0008] The inner frame, preferably in contrast to the outer frame, can serve as a media guide through the electrode frame. This means that the outer frame does not serve as a media guide through the electrode frame. Furthermore, the outer frame can function as a radial thrust bearing for the inner frame. This means that the electrode frame is designed such that its function of media guidance is essentially or exclusively limited to the inner frame, while its function of ensuring, in particular, radial (fluid) pressure resistance is limited to the outer frame.

[0009] As far as the axial mechanical compressive strength of the electrode frame is concerned, this can essentially be achieved either by the outer frame, the inner frame (cf. Fig. 6) or both within the cell stack. In this case, the function of media guidance is essentially physically separated from the function of ensuring (fluid) pressure resistance in the electrode frame, which offers advantages for a cell stack (see below). Furthermore, the inner frame primarily performs the function of electrical insulation within the cell stack.

[0010] The inner frame can have: medium passage recesses, medium channels, sealing recesses, and / or seals. The outer frame can be designed as a solid, essentially homogeneous ring, apart from any existing through-holes for clamping bolts. The inner frame is preferably also designed as an essentially homogeneous ring. The outer frame can have no: medium passage recesses, medium channels, sealing recesses, and / or seals. Within the cell stack, the respective medium passage recesses and medium channels of the electrode frame are in fluid communication.

[0011] The electrode frame can be configured as a circumferentially closed ring. In this case, a mass density of the outer frame can be greater than a mass density of the inner frame. A material of the outer frame can be different from a material of the inner frame. Furthermore, the outer frame can comprise a metal and / or the inner frame can comprise a plastic. The metal can, in particular, be steel or stainless steel. The plastic of the inner frame is preferably a thermoplastic or a thermosetting plastic.

[0012] Furthermore, the electrode frame can have a predominantly or substantially rectangular, square, elliptical, or circular outline. Furthermore, the electrode frame can have exactly one inner frame and exactly one outer frame. Furthermore, the inner frame and / or the outer frame can have a predominantly or substantially rectangular, circumferential cross-section.

[0013] The two axial outer sides of the outer frame and the inner frame can each lie essentially in one plane. This means that the outer frame and the inner frame have essentially the same axial thickness. Furthermore, the inner frame is preferably centered in the outer frame in the axial direction and in the radial direction. The outer frame can be arranged only on one circumferential side of the inner frame. The outer frame and the inner frame can be connected to one another in a form-fitting, material-fitting, or force-fitting manner. A radial extent of the outer frame can be at least approximately: 75%, 70%, 65%, 60%, 50%, 45%, 40%, 35%, 30%, 25%, 20%, each ±2% of a radial extent of the inner frame. And an axial thickness of the electrode frame can be approx.: 1.5mm, 1.75mm, 2mm, 2.25mm or 2.5mm.

[0014] In contrast to the outer frame, the inner frame can preferably serve as a seal carrier, particularly for the actual cell stack. This applies, for example, to the radial sealing of an electrode chamber in the circumferential direction (on both large-area sides) and / or the sealing of relevant medium passage recesses (on none, one, or both large-area sides) in their respective circumferential directions. For a respective seal, the inner frame can have a sealing groove or a sealing recess, into which the respective seal is preferably injection-molded or preferably inserted. In this case, a respective seal can, in particular, comprise an elastomer.

[0015] A positive connection can be established in the circumferential direction between the outer frame and the inner frame. An inner fixing device of the outer frame and an outer fixing device of the inner frame can engage with each other for mutual axial fixing of the frames of the electrode frame. Furthermore, the fixing device of the outer frame can be designed as an inner projection, and the fixing device of the inner space can be designed as an outer recess. The positive connection can be established, for example, by injection molding (primary forming of the positive connection) or inserting (snap-in connection) the inner frame into the outer frame.

[0016] The inner frame, in particular an inner frame of a cathode frame, can have a large-area membrane recess for accommodating a membrane. It is preferred that the recess extends axially into the inner frame to such an extent that, for a given membrane, its outer surface is flush with a radially outer portion of the inner frame. Naturally, the membrane covers the entire electrode chamber through-hole of the inner frame or the electrode frame.

[0017] The inner frame can have at least one positioning device for a membrane of an individual electrochemical cell of the cell stack on / in a first large-area side. In this case, the positioning device can be designed, in particular, as a projection on the inner frame. Furthermore, the inner frame can have at least one positioning device for a bipolar plate of the cell stack on / in a second large-area side. In this case, the positioning device can be designed, for example, as a projection on or a recess in the inner frame.

[0018] The outer frame can be formed as a stamped part and the inner frame as an injection-molded part. The inner frame can be inserted into the outer frame or injected into it. In the latter case, the electrode frame is also formed as an injection-molded part with the outer frame as an injection-molded insert. The outer frame can have through-holes for clamping bolts of the cell stack.

[0019] The outer frame and / or the inner frame can be constructed as a single piece or integrally. A single piece (adhesive) construction refers to a construction of the frame in question in which its individual parts are firmly bonded to one another (injection molding, gluing, lamination, etc.) and the frame in question preferably cannot be separated into individual parts without damaging one of its individual parts. The cohesion of the frame in question can also be achieved by means of a force-fit and / or form-fit connection (not in the case of an integral construction).

[0020] An integral design is understood to mean a design of the frame in question in which there is only a single component that can only be separated by destruction. The frame in question is made from a single original piece and / or a single original mass (molten metal or molten plastic), which in turn is necessarily integral. Internal cohesion is achieved (exclusively) by adhesion and / or cohesion. - The frame in question, in particular the outer frame, can additionally have lamination, coating, integral deposition, etc. in all embodiments.

[0021] The cell layer according to the invention has at least one electrode frame and a fluid transport structure arranged in the electrode space through-hole thereof, wherein the at least one electrode frame is designed according to the invention. The cell layer can further comprise a membrane (see below), in particular a membrane-electrode unit. It is of course possible for the membrane and at least one fluid transport structure (see below) of the cell layer to form a membrane-electrode device, wherein an electrode can be provided on a fluid transport structure or the membrane. The membrane can be arranged between two electrode frames, wherein one or two fluid transport structures can be attached to the membrane. Furthermore, the cell layer can comprise a polar plate, in particular a bipolar plate.

[0022] The electrochemical cell stack according to the invention comprises a plurality of individual electrochemical cells, wherein electrode frames of the cell stack and / or cell layers of the cell stack are designed according to the invention. - In this case, a respective membrane of the cell stack can be arranged between the mutually related inner frames of two electrode frames of an individual cell. The membrane can be designed as a stand-alone membrane, a membrane electrode assembly (MEA, optionally with only a single catalyst layer), a catalyst-coated membrane (CCM, also optionally with only a single catalyst layer), as part of a membrane electrode device, etc. A respective bipolar plate of the cell stack can be arranged only between two mutually related inner frames of two electrode frames of two directly adjacent individual cells.

[0023] A significant axial mechanical force flow within the actual cell stack can be established essentially away from the outer frames of the electrode frames in the actual cell stack. This means that the actual cell stack is mechanically clamped together essentially radially within its outer frames via its inner frames, its bipolar plates, possibly its membranes, and possibly its fluid transport structures. This means that, apart from clamping devices (clamping bolts, nuts, feedthrough recesses, etc.), collector plates, insulating plates, end plates, etc., an axial compressive force in the cell stack is transmitted only via these components of the cell stack beyond its outer frame.

[0024] The outer frames of the electrode frames can essentially only absorb the radial fluid pressures from the actual cell stack. This means that in this case, the outer frames essentially only serve to provide radial fluid pressure resistance for the electrode frames; they therefore serve as circumferential thrust bearings for the inner frames and not to impart an axial force within the cell stack. In this case, the clamping bolts can be guided through the feedthrough recesses into the outer frame. - The electrochemical unit or the electrochemical system according to the invention has at least one electrochemical cell stack and a control device for controlling and / or regulating operation of the cell stack, wherein the electrode frame of the cell stack, cell layers of the cell stack and / or the cell stack is / are designed according to the invention.

[0025] Plastic overmolding as an alternative to the invention is very challenging and cost-intensive in the required size dimension, since a large thermal discrepancy between metal and plastic leads to a high risk of cracking during and after production. According to the invention, these quality risks can be avoided. Supporting seals on a thin-walled plastic overmolding can be avoided. Furthermore, in embodiments, it is possible to avoid plastic in a force line of a mechanical prestressing of the cell stack. Radially inwardly open metal areas and thus their corrosion due in particular to treated water or alkali and / or hydrogen can be avoided. Short description of the characters

[0026] The invention is explained in more detail below using exemplary embodiments with reference to the attached schematic drawing. In the invention, a feature can be configured positively, i.e., present, or negatively, i.e., absent. In this specification, a negative feature is not explicitly explained as a feature unless it is important for the invention to be absent. This means that the invention actually made, and not one constructed by the prior art, consists in omitting this feature. The absence of a feature (negative feature) in an exemplary embodiment indicates that the feature may be optional (to a person skilled in the art). - In the merely exemplary figures (Fig.) of the drawing: The Fig. 1 in a simplified block diagram embodiments of an electrolyzer unit for the AEM-EL, PEM-EL, AEL etc., with an electrochemical electrolysis cell stack for an electrolysis system, the Fig. 2 in a two-dimensional plan view, an embodiment of an electrode frame according to the invention for an electrolysis cell stack, with an inner frame and an outer frame, the Fig. 3 and Fig. 4 in two-dimensional top views, each showing a detail view broken away from two sides compared to the Fig. 1, each showing a further embodiment of the electrode frame, the Fig. 5 in a radially inner (left) broken away, axial-radial half-section, another embodiment of the electrode frame with its inner frame and its outer frame, and the Fig. 6 shows a highly schematic representation of a comparatively small section of an electrolysis cell stack broken away on all sides. Embodiments of the invention

[0027] The invention is described below with reference to an electrode frame 100 (cf. Fig. 2 to 6) for an electrolysis cell stack 10 of an electrolyzer unit 1 (cf. the Fig. 1) with at least one electrolysis cell stack 10 for electrolysis (EL) of a supply medium 3 into hydrogen 6 and oxygen is explained in more detail. The invention is applicable to a variety of electrolysis systems with one or a plurality of electrolyzer units 1, wherein an electrolyzer unit 1 can be designed, for example, for AEM electrolysis (AEM-EL), PEM electrolysis (PEM-EL), alkaline electrolysis (AEL), etc. - Furthermore, the invention is applicable to fuel cell stacks, in particular a PEM fuel cell stack or an AEM fuel cell stack; ie the drawing is analogously transferable to a fuel cell stack.

[0028] The drawing shows only those sections of an electrolyzer unit 1 of an electrolysis system (not shown), for example, an electrolysis plant (not shown), which are necessary for understanding the invention. Although the invention is described and illustrated in detail using preferred embodiments, the invention is not limited to the disclosed embodiments. Other variations can be derived therefrom without departing from the scope of the invention.

[0029] The Fig. 1 shows an electrolyzer unit 1 according to a general embodiment, with at least one, in particular a plurality of, individual electrochemical cells 11 (individual electrolysis cell 11) bundled into an electrolysis cell stack 10, which are accommodated in a preferably fluid-tight stack housing 16 by mechanical bracing between end plates. Each individual cell 11 comprises an electrode chamber 12 designed as an anode chamber 12 and an electrode chamber 13 designed as a cathode chamber 13, which are separated by a membrane 140 (cf. Fig. 6) of a membrane electrode device 15 are spatially and electrically separated from each other.

[0030] A membrane electrode device 15 comprises a membrane 140, two electrodes, and preferably two fluid transport structures 130, wherein at least one electrode is provided on the membrane 140 and / or at least one electrode is provided directly opposite the membrane 140 on a fluid transport structure 130. Of course, both electrodes can also be provided on the membrane 140 (membrane electrode assembly (MEA)) or on the fluid transport structures 130. The membrane 140 or the membrane electrode assembly, including the fluid transport structures 130 provided thereon, can be brought into sealing contact with a bipolar plate 14.

[0031] The membrane electrode device 15 may comprise an AEM or a PEM, e.g., in the form of a CCM (Catalyst Coated AEM / PEM as MEA), or a diaphragm. A fluid transport structure 130 on a large-area side of the membrane electrode device 15 may comprise a transport layer, a PTL (Porous Transport Layer), a GDL (Gas Diffusion Layer), a sintered metal element, a fiber element, a flow structure, and / or a flow field, etc. The Fig. 1 not explicitly shown, are provided or arranged in the anode compartments 12 and the cathode compartments 13 of the electrolysis cell stack 10.

[0032] A bipolar plate 14 is arranged between two directly adjacent membrane electrode devices 15, including a respective anode compartment 12 and a respective cathode compartment 13. A bipolar plate 14 serves, among other things, as a feedthrough and, if necessary, a supply / discharge of media 3, 4 (disposal medium with oxygen), 6 for or from an anode compartment 12 of a first individual cell 11, and for or from a cathode compartment 13 of a directly adjacent second individual cell 11, and furthermore realizes an electrically conductive connection between these two individual cells 11. In addition to a feedthrough, an actual supply / discharge of media 3, 4, 6 from a respective electrode frame 100 (see below) can be realized in the anode compartment 12 of the first individual cell and in the cathode compartment 13 of the second individual cell 13.

[0033] The cathode chambers 13 and, if applicable, their common inflow area or their actual electrodes form a cathode 39 (-); and the anode chambers 12 and, if applicable, their common inflow area or their actual electrodes form an anode 29 (+) of the electrolysis cell stack 10. - The electrolysis system and, of course, also the electrolysis plant (see above) comprises, in addition to the electrolyzer unit 1, peripheral system components, such as: a control unit, a processing device 60 for generating fresh supply medium 3, a hydrogen storage unit 40, if applicable, an oxygen storage unit 50, etc.

[0034] To supply the electrolysis cell stack 10 with the supply medium 3, the electrolyzer unit 1 has a medium supply 20. And to remove the media 4, 6 from the electrolysis cell stack 10, the electrolyzer unit 1 has a media removal 30. The medium supply 20 comprises, in particular, a medium reservoir 23 for the supply medium 3 (flowing in), a supply path 21 (medium path 21), and a conveying device 26, in particular a pump 26, on / in the supply path 21 for the supply medium 3.

[0035] The media removal 30 has at least one anode-side disposal path 31 (medium path 31) for the disposal medium 4, including oxygen, back into the water reservoir 23, optionally with a gas separator for the produced oxygen, and / or in another direction (shown in dashed lines), e.g., into the environment 2. The latter can be realized in particular if the electrolysis cell stack 10 is cooled independently of the supply medium 3.

[0036] Furthermore, an actual product gas 6 of the electrolyzer unit 1, i.e., the produced hydrogen 6, can be transported away through a cathode-side product medium path 32 (medium path 32) of the medium removal 30. A gas / liquid separator 33 with a valve 34 can be installed in the product medium path 32. The medium separated in the gas / liquid separator 34 can be conveyed back into the medium reservoir or in another direction, e.g., into the environment 2, possibly by gravity. The produced hydrogen 6 can be stored, for example, in a hydrogen storage device 40 (collection container 40, storage tank 40, etc.), wherein the product medium path 32 can flow directly into the hydrogen storage device 40. Another method of transporting the hydrogen 6 is, of course, also applicable.

[0037] Depending on the embodiment of the electrolyzer unit 1, a media guide within the electrolysis cell stack 10 can be designed differently. In this case, it is possible to provide a temperature control, in particular cooling, that differs from an electrochemical function of the electrolysis cell stack 10 and / or to implement the temperature control or cooling, preferably together with the electrochemical function of the electrolysis cell stack 10, via the supply medium 3 for the electrolysis.

[0038] In membrane electrode devices 15 with AEMs, it is possible to set up a supply of the supply medium 3 on both the anode and cathode sides, if necessary also as a cooling medium (dotted arrow at anode 29). Furthermore, in membrane electrode devices 15 with PEMs, it is possible to set up a supply of the supply medium 3 on both the anode and cathode sides, if necessary also as a cooling medium (dotted arrow at cathode 39). In the AEL, in addition to a supply of the supply medium 3 on both the anode and cathode sides, if necessary also as a cooling medium (dotted arrow at anode 29).

[0039] In particular, the Fig. 2 to 5 show embodiments of electrode frames 100 for delimiting electrode spaces 12, 13 in electrolysis cell stacks 10, wherein a fluid transport structure 130 (cf. Fig. 5 and above). For this purpose, positional information, i.e. an axial direction Ar (axial), a radial direction Rr (radial) and a circumferential direction Ur of the cell stack 10, the electrode frame 100 etc., to which this specification refers, are only given in the Fig. 2 is shown.

[0040] The electrode frame itself, i.e., the global electrode frame 100, is formed by two frames 110, 120, wherein one frame 110, as an inner frame 110, is arranged radially Rr completely within the other frame 120, as an outer frame 120. The outer frame 120 is formed from a different material than the inner frame 110. In particular, the outer frame 120 is formed essentially from a metal, preferably steel or stainless steel, and the inner frame 110 is formed essentially from a plastic, preferably a thermoplastic or a thermosetting plastic.

[0041] The inner frame 110 is designed and constructed in such a way that it: essentially serves as a media guide in the electrolysis cell stack 10, acts as a carrier for the seals 117, for example, injected or inserted therein, for radially sealing the respective electrode chamber 12, 13, clamping and / or positioning (cf. above) of a membrane 140 in its membrane recess 111 (cf. Fig. 6 and above), serves to position a fluid transport structure 140 in the electrode space through-hole 103 and / or serves to position (cf. above) a bipolar plate 14 of the cell stack 10.

[0042] For media guidance, the inner frame 110, see in particular the Fig. 2, medium passage recesses 112 for the supply medium 3, the disposal medium 4 (including oxygen), and the product gas 6 (including a supply medium 3 to be disposed of). Depending on the side of the inner frame 110, i.e., whether it is a membrane side or a bipolar plate side, and / or depending on the type of inner frame 110, i.e., whether it is an anode inner frame 110 or a cathode inner frame 110, medium channels 113 extend from the medium passage recesses 112 to the electrode chamber passage recess 103, or vice versa.

[0043] The medium channels 113, also referred to as delta channels 113, are configured, for example, as grooves 113 in a respective large-area side of the inner frame 110. In the electrolysis cell stack 10, such groove-shaped media channels 113 are closed at their peripheries by bipolar plates 14 and / or membranes 140. Other forms of the medium channels 113, such as bores, are of course applicable if necessary. In the electrolysis cell stack 10, the respective medium passage recesses 112, which belong to the so-called chimneys 112 of the electrolysis cell stack 10, are in fluid communication with the respective electrode chamber passage recess 103 via respective medium channels 113.

[0044] For radial Rr densities (cf. the Fig. 2 and Fig. 5) one or a plurality of medium passage recesses 112 in their circumferential direction. The inner frame 110 again has corresponding seals 117 depending on one side, i.e., whether it is a membrane side or a bipolar plate side, and / or again depending on the type of inner frame 110, i.e., whether it is an anode inner frame 110 or a cathode inner frame 110. And for radially sealing the respective electrode chamber 12, 13 in the electrolysis cell stack 10, the inner frame 110 has at least one seal 117 on both large-area sides, each completely surrounding its electrode chamber passage recess 103.

[0045] A respective seal 117 can be arranged in a sealing recess 116 arranged in the inner frame 110, wherein the sealing recess 116 is preferably arranged such that it extends from a surface of the inner frame 110 into the frame 110 such that it meets itself and thus closes a periphery. Such a sealing recess 116, which is circumferentially closed, for example, as a sealing groove 116, runs, for example, around one or a plurality of medium passage recesses 112. Of course, no medium channels 113 lead to these medium passage recesses 112.

[0046] Furthermore, the outer frame 120 is designed and configured such that it essentially functions as a thrust bearing for the inner frame 110. This means that an internal fluid pressure in a respective electrode chamber 12, 13 of the inner frame 110 due to operation of the electrolytic cell stack 10 is absorbed by the outer frame 120, which holds the inner frame 110 dimensionally stable in its radial inner region. In this case, the inner frame 110 can, for example, deform elastically.

[0047] Depending on the embodiments of the electrode frames 100 of an electrolysis cell stack 10 or of the electrolysis cell stack 10, the electrode frames 100 can be designed such that the electrolysis cell stack 10 is only connected via the inner frames 110 (cf. Fig. 6), only via the outer frames 120, or via both the inner frames 110 and the outer frames 120, is essentially clamped together or clamped together mechanically axially Ar.

[0048] A preferably positive connection between a radial outer side of the inner frame 110 and a radial inner side of the outer frame 120 preferably serves for mutual axial fastening. In this case, the positive connection can simply be formed in two adjacent sides (cf. Fig. 5) or be designed by a special shaping of mutually related radial sides. For example, a fixing device 124 of the outer frame 120, designed as a radial Rr projection 124 or a radial Rr recess, and a fixing device 124 of the inner frame 110, designed as a radial Rr recess 114 or a radial Rr projection, can form the positive connection (cf. Fig. 6).

[0049] The outer frame 120 can be designed as a solid, in particular closed ring. The outer frame 120 can have through-holes 122 for clamping bolts 150 of the electrolysis cell stack 10 (see FIG. Fig. 4). Alternatively (cf. Fig. 3), the clamping bolts 150 of the electrolytic cell stack 10 can be arranged radially Rr outside the outer frame 120, so that it does not require any through-holes 122 for the clamping bolts 150. Furthermore, the outer frame 120 can, for example, have clearly rounded outer corner areas (cf. Fig. 3), or whose corner areas show a clearly recognizable angle, in particular a right angle (cf. Fig. 4).

[0050] The Fig. Figure 6 shows a section of an electrolysis cell stack 10, clearly showing that the actual electrolysis cell stack 10 is clamped together via the inner frames 110 and not the outer frames 120 of its electrode frames 100. The axial Ar clamping is achieved by means of the clamping bolts 150, which clamp the actual electrolysis cell stack 10 together via axial Ar outer plates 160. These plates 160 act only on the inner frames 110 without directly acting on the outer frames 120. Axial Ar forces on and / or between the outer frames 120 originate from the inner frames 110. Axial Ar forces on and / or between the inner frames 110 originate from the plates 160, the clamping bolts 150, and a closing force of the clamping bolts 150.

[0051] Furthermore, the Fig. 6 environmental seals 170, which are also located in the axial direction Ax between the inner frames 110 and not the outer frames 120 of the electrode frames 100. It is of course possible to install the environmental seals 170 between the outer frames 120. In addition, the Fig. 6 a clamping bolt 150 guided through feedthrough recesses 122 of the outer frame 120 with a clearance. The feedthrough recesses 122 in the outer frame 120 are preferably dimensioned and arranged in the electrolytic cell stack 10 such that feedthrough recesses 122 aligned in the axial direction Ar impose only a slight counterforce on a clamping bolt 150 when inserted through.

Claims

[1] Electrode frame (100) for an electrochemical cell stack (10), in particular an electrolysis cell stack (10) or a fuel cell stack, wherein the electrode frame (100) for the radial (Rr) fluid sealing of an electrode space (12, 13) of the cell stack (10) extending in the axial direction (Ax), runs around its electrode space through-hole (103) in the circumferential direction (Ur), characterized by , that the electrode frame (100) comprises an outer frame (120) running around the outside and an inner frame (110) radially (Rr) therein with the electrode space through-hole (103), wherein a representative volume element of the outer frame (120) is designed to be stiffer than a representative volume element of the inner frame (110) of the same size. [2] Electrode frame (100) according to the preceding claim, characterized bythat the inner frame (110), in contrast to the outer frame (120), serves to guide the media through the electrode frame (100), and / or the outer frame (120) acts as a radial (Rr) thrust bearing for the inner frame (110). [3] Electrode frame (100) according to one of the preceding claims, characterized by , that: • the inner frame (110): has medium passage recesses (112), medium channels (113), sealing recesses (116) and / or seals (117), • the outer frame (120), once of any existing through-holes (122) for clamping bolts (150), is designed as a solid, substantially homogeneous ring, and / or • the outer frame (120) does not have any: medium passage recesses (112), medium channels (113), sealing recesses (116) and / or seals (117). [4] Electrode frame (100) according to one of the preceding claims, characterized by , that: • the electrode frame (100) is designed as a ring closed in the circumferential direction (Ur), • a material of the outer frame (120) is different from a material of the inner frame (110), and / or • the outer frame (120) comprises a metal and / or the inner frame (110) comprises a plastic. [5] Electrode frame (100) according to one of the preceding claims, characterized by , that: • the two axial (Ar) outer sides of the outer frame (120) and the inner frame (110) each lie essentially in one plane, • the outer frame (120) is arranged only on one peripheral side of the inner frame (110), and / or • the outer frame (120) and the inner frame (110) are connected to one another in a form-fitting, material-fitting or force-fitting manner. [6] Electrode frame (100) according to one of the preceding claims, characterized bythat the inner frame (110), in contrast to the outer frame (120), serves as a preferably exclusive seal carrier, in particular for the actual cell stack (10), and / or for a respective seal (117), the inner frame (110) has a sealing groove (116) or a sealing recess into which the respective seal (117) is injected or inserted. [7] Electrode frame (100) according to one of the preceding claims, characterized by that a positive connection is established in the circumferential direction (Ur) between the outer frame (120) and the inner frame (110), wherein a) and a fixing device of the inner frame (110) for mutual axial (Ar) fixing of the frames (110, 120) of the electrode frame (100) engage in each other, and / or the fixing device (124) of the outer frame (120) is designed as an inner projection (124) and the fixing device (114) of the inner space (110) is designed as an outer recess (114). [8] Electrode frame (100) according to one of the preceding claims, characterized by , that: • the inner frame (110), in particular an inner frame (110) of a cathode frame (100), has a large-area membrane recess (111) for receiving a membrane (140), • the inner frame (110) has on / in a first large-area side at least one positioning device for a membrane (140) of an electrochemical single cell (110) of the cell stack (10), • the inner frame (110) has at least one positioning device for a bipolar plate (14) of the cell stack (10) on / in a second large-area side. [9] Electrode frame (100) according to one of the preceding claims, characterized by , that: • the outer frame (120) is formed as a stamped part and the inner frame (110) as an injection-molded part, • the outer frame (120) has through-holes (122) for clamping bolts (150) of the cell stack (10), and / or • the outer frame (120) and / or the inner frame (110) is formed in one piece or integrally. [10] Cell layer for an electrochemical cell stack (10), in particular an electrolysis cell stack (10) or a fuel cell stack, with at least one electrode frame (100) and a fluid transport structure (130) arranged in its electrode space through-hole (103), characterized by that the at least one electrode frame (100) is designed according to one of the preceding claims. [11] Electrochemical cell stack (10), in particular electrolysis cell stack (10) or fuel cell stack, for an electrochemical unit (1), in particular an electrolyzer unit (1) or a fuel cell unit, with a plurality of electrochemical individual cells (11), characterized bythat electrode frames (100) of the cell stack (10) are designed according to one of the preceding claims and / or cell layers of the cell stack (10) are designed according to the preceding claim. [12] Electrochemical cell stack (10) according to the preceding claim, characterized by , that: • a respective membrane (140) is arranged between the respective inner frames (110) of two electrode frames (100) of a single cell (11), • a respective bipolar plate (14) is arranged only between the respective inner frames (110) of two electrode frames (100) of two directly adjacent individual cells (11), • a significant axial (Ar) mechanical force flow within the actual cell stack (10) is arranged substantially away from the outer frames (120) of the electrode frames (100) in the actual cell stack (10), and / or • the outer frames (120) of the electrode frames (100) of the cell stack (10) essentially only absorb the radial (Rr) fluid pressures from the actual cell stack (10). [13] Electrochemical unit (1), in particular electrolyzer unit (1) or fuel cell unit, or electrochemical system, in particular electrolyzer system or fuel cell system, with at least one electrochemical cell stack (10) and a control device for controlling and / or regulating an operation of the cell stack (10), characterized by that electrode frames (100) of the cell stack (10) are designed according to one of the preceding claims, cell layers of the cell stack (10) are designed according to one of the preceding claims and / or the cell stack (10) is designed according to the preceding claim.

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