ELECTROCHEMICAL DEVICE AND METHOD FOR OPERATING AN ELECTROCHEMICAL DEVICE

Abstract

An electrochemistry device, in particular an electrolysis device, in particular a polymer electrolyte membrane electrolysis device, has at least one cell unit, which includes at least one first electrochemical cell and at least one second electrochemical cell, and has at least one fluid supply unit for supplying the cell unit with at least one fluid, in particular with water, which at least one fluid supply unit includes at least one first fluid supply path extending at least section-wise through the first electrochemical cell, and at least one second fluid supply path extending at least section-wise through the second electrochemical cell,

the fluid supply unit is designed in such a way that, in at least one normal operating state, a volume flow of the fluid through the first electrochemical cell and through the second electrochemical cell is at least substantially identical.

Claims

1. An electrochemistry device, in particular electrolysis device, in particular polymer electrolyte membrane electrolysis device, having at least one cell unit, which comprises at least one first electrochemical cell and at least one second electrochemical cell, and having at least one fluid supply unit for supplying the cell unit with at least one fluid, in particular with water, which at least one fluid supply unit comprises at least one first fluid supply path extending at least section-wise through the first electrochemical cell, and at least one second fluid supply path extending at least section-wise through the second electrochemical cell, wherein the fluid supply unit is designed in such a way that, in at least one normal operating state, a volume flow of the fluid through the first electrochemical cell and through the second electrochemical cell is at least substantially identical.

2. The electrochemistry device as claimed in claim 1, wherein, in the normal operating state, a pressure loss in the first fluid supply path at least substantially corresponds to a pressure loss in the second fluid supply path.

3. The electrochemistry device as claimed in claim 1, wherein the first fluid supply path and the second fluid supply path are at least substantially of equal length.

4. The electrochemistry device as claimed in claim 1, wherein the first fluid supply path and the second fluid supply path lead from a common inlet to the electrochemical cells and/or from the electrochemical cells to a common outlet.

5. The electrochemistry device as claimed in claim 1, wherein the fluid supply unit has at least one inlet channel and at least one outlet channel, which are provided for conducting the fluid, in the normal operating state, in an inlet flow direction and in an outlet flow direction which run at least substantially parallel to one another.

6. The electrochemistry device as claimed in claim 1, wherein a sum of a length of a first inlet portion and of a length of a first outlet portion of the first fluid supply path at least substantially corresponds to a sum of a length of a second inlet portion and a length of a second outlet portion of the second fluid supply path.

7. The electrochemistry device as claimed in claim 6, wherein a pressure loss in the first inlet portion is greater than a pressure loss in the second inlet portion, and a pressure loss in the first outlet portion is smaller than a pressure loss in the second outlet portion.

8. The electrochemistry device as claimed in claim 5, wherein a sum of a length of a first inlet portion and of a length of a first outlet portion of the first fluid supply path at lease substantially corresponds to a sum of a length of a second inlet portion and a length of a second outlet portion of the second fluid supply path, and wherein the inlet channel at least partially forms the first inlet portion and the second inlet portion and/or the outlet channel at least partially forms the first outlet portion and the second outlet portion.

9. The electrochemistry device as claimed in claim 1, wherein the first electrochemical cell has at least one functional element which forms at least a section of the first fluid supply path and at least a section of the second fluid supply path.

10. The electrochemistry device as claimed in claim 9, wherein the functional element is a functional cell stack element.

11. The electrochemistry device as claimed in claim 1, wherein the cell unit comprises at least one cell stack with a plurality of electrochemical cells arranged in a stacked manner, each of which is assigned a fluid supply path.

12. An electrolyzer having at least one electrochemistry device as claimed in claim 1.

13. A method for operating an electrochemistry device, in particular an electrolysis device, in particular a polymer electrolyte membrane electrolysis device, in particular as claimed in claim 1, having at least one cell unit, which comprises at least one first electrochemical cell and at least one second electrochemical cell, wherein the first electrochemical cell and the second electrochemical cell are flowed through by a fluid in such a way that a volume flow of the fluid through the first electrochemical cell and through the second electrochemical cell is at least substantially identical.

14. The electrochemistry device as claimed in claim 5, wherein a pressure loss in the first inlet portion is greater than a pressure loss in the second inlet portion, and a pressure loss in the first outlet portion is smaller than a pressure loss in the second outlet portion, and wherein a sum of a length of a first inlet portion and of a length of a first outlet portion of the first fluid supply path at least substantially corresponds to a sum of a length of a second inlet portion and a length of a second outlet portion of the second fluid supply path, and wherein the inlet channel at least partially forms the first inlet portion and the second inlet portion and/or the outlet channel at least partially forms the first outlet portion and the second outlet portion.

Description

DRAWINGS

[0029] Further advantages emerge from the following description of the drawings. The drawings illustrate exemplary embodiments of the invention. The drawings, the description and the claims contain numerous features in combination. A person skilled in the art will expediently also consider the features individually and combine these to form further meaningful combinations.

[0030] In the drawings:

[0031] FIG. 1 shows an electrolyzer with an electrochemistry device in a schematic side view,

[0032] FIG. 2 shows a functional element of an electrochemical cell of the electrochemistry device in a schematic plan view,

[0033] FIG. 3 shows the electrochemistry device in a schematic frontal view,

[0034] FIG. 4 shows a first alternative electrochemistry device in a schematic side view,

[0035] FIG. 5 shows a second alternative electrochemistry device in a schematic side view, and

[0036] FIG. 6 shows a third alternative electrochemistry device in a schematic side view.

DESCRIPTION OF THE EXEMPLARY EMBODIMENTS

[0037] FIG. 1 shows an electrolyzer 48a with an electrochemistry device 10a in a schematic side view. The electrolyzer 48a is in the present case shown merely schematically, and may comprise components which are not illustrated, such as for example electrical connections, a housing, a water circuit, an open-loop and/or closed-loop control unit, or the like. The electrochemistry device 10a is, in the present case, designed as an electrolyzer device. In particular, the electrolysis device 10a is a hydrogen electrolysis device. As mentioned above, it is however also conceivable for the electrochemistry device 10a to be designed as a fuel cell device, a measuring unit device, an electroplating device or the like.

[0038] The electrochemistry device 10a has a cell unit 12a, which comprises at least one first electrochemical cell 14a and at least one second electrochemical cell 16a. In the present case, the cell unit 12a has a multiplicity of electrochemical cells 14a, 16a, of which, for the sake of clarity, only five are schematically illustrated, and which are not all denoted by reference designations. Furthermore, the electrochemical cells 14a, 16a of the cell unit 12a are not illustrated true to scale in FIG. 1. In particular, the electrochemical cells 14a, 16a of the cell unit 12a may be of much flatter design than in the schematic illustration of FIG. 1. For example, the cell unit 12a may comprise 20 or 30 or 50 or 100 or 150 or 200 electrochemical cells.

[0039] The cell unit 12a has a cell stack 46a which comprises a multiplicity of electrochemical cells 14a, 16a arranged in a stacked manner. In the present case, all electrochemical cells 14a, 16a of the cell unit 12a are stacked to form the cell stack 46a. Furthermore, in the present case, the electrochemical cells 14a, 16a of the cell unit 12a are of at least substantially identical design with respect to one another. In the present case, the cell stack 46a is an electrolysis stack. The electrochemical cells 14a, 16a of the cell unit 12a are stacked in a stack direction 50a. The stack direction 50a corresponds to a stack thickness direction of the cell stack 46a. In the present case, the stack direction 50a runs perpendicular to a main extent plane of the first electrochemical cell 14a. Furthermore, in the present case, main extent planes of the electrochemical cells 14a, 16a of the cell unit 12a are arranged parallel to one another.

[0040] The cell unit 12a has a first end plate 52a and a second end plate 54a. The first end plate 52a and the second end plate 54a delimit the electrochemical cells 14a, 16a of the cell stack 46a toward opposite sides of the cell stack 46a. The end plates 52a, 54a are for example connected to one another by means of connecting struts and exert a pressure force on the electrochemical cells 14a, 16a of the cell stack 46a, which pressure force in particular counteracts a pressure owing to a formation of hydrogen gas and/or oxygen gas, or in particular effects or at least contributes to leak-tightness of the electrochemical cells 14a, 16a, which are pressed against one another, with respect to one another and/or leak-tightness of the respective electrochemical cell 14a, 16a.

[0041] The electrochemistry device 10a has contact elements (not shown) for connection to a power supply. In a normal operating state, the cell unit 12a is supplied with electrical power via the contact elements. Here, an overall voltage prevails between a foremost electrochemical cell 56a, which bears in particular against the first end plate 52a, and a rearmost electrochemical cell 58a, which bears in particular against the second end plate 54a. In the normal operating state, a voltage of between approximately 1 V and approximately 2.5 V prevails in each case across individual electrochemical cells 14a, 16a, 56a, 58a of the cell unit 12a, as has in particular also been mentioned above.

[0042] The electrochemistry device 10a has a fluid supply unit 18a. The fluid supply unit 18a is in the present case provided for supplying the cell unit 12a, in particular the cell stack 46a, with a fluid. In the present case, the fluid is water, in particular deionized water. The fluid serves as a starting product for an electrolytic reaction. Furthermore, in the present case, the fluid additionally serves as coolant. It is however basically conceivable for the electrochemistry device 10a to have multiple different fluid supply units 18a which are provided for separate supply with, in particular, different fluids, for example with reaction gases, coolants, reactant fluids or the like.

[0043] The fluid supply unit 18a has at least one first fluid supply path 20a extending at least section-wise through the first electrochemical cell 14a. Furthermore, the fluid supply unit 18a has at least one second fluid supply path 22a, which extends at least section-wise through the second electrochemical cell 16a. Courses of the first fluid supply path 20a and of the second fluid supply path 22a are schematically illustrated as lines in FIG. 1. The first fluid supply path 20a and the second fluid supply path 22a each comprise a volume that can be flowed through by the fluid.

[0044] The fluid supply unit 18a is designed such that, in the normal operating state, a volume flow of the fluid through the first electrochemical cell 14a and through the second electrochemical cell 16a is at least substantially identical. In particular, in the normal operating state, the electrochemistry device 10a produces hydrogen gas. Furthermore, in the normal operating state, the cell unit 12a is supplied continuously with a fluid flow, for example by means of a fluid circuit (not shown) and/or a pump (not shown). In the present case, the first electrochemical cell 14a and the second electrochemical cell 16a are of at least substantially identical design. In particular, the first electrochemical cell 14a and the second electrochemical cell 16a have an interior space of at least substantially identical design, and/or an inner cross section of at least substantially identical design, which is in particular flowed through by the fluid in the normal operating state. In the present case, a volume flow through each of the electrochemical cells 14a, 16a, 56a, 58a of the cell unit 12a is at least substantially identical. The electrochemical cells 14a, 16a, 56a, 58a of the cell stack 46a are, in the normal operating state, flowed through uniformly and/or equally and/or with identical volume flows.

[0045] In a method for operating the electrochemistry device 10a, the first electrochemical cell 14a and the second electrochemical cell 16a are flowed through by the fluid such that a volume flow of the fluid through the first electrochemical cell 14a and through the second electrochemical cell 16a is at least substantially identical.

[0046] Furthermore, in the normal operating state, a pressure loss in the first fluid supply path 20a at least substantially corresponds to a pressure loss in the second fluid supply path 22a. In the present case, a pressure loss in each of the electrochemical cells 14a, 16a, 56a, 58a of the cell unit 12a is at least substantially identical. Furthermore, in the present case, the cell stack 46a is free from a pressure gradient extending across multiple electrochemical cells in the stack direction 50a. In particular, a pressure loss in the foremost electrochemical cell 56a at least substantially corresponds to a pressure loss in the rearmost electrochemical cell 58a.

[0047] The first fluid supply path 20a and the second fluid supply path 22a are at least substantially of equal length. In the present case, the fluid supply unit 18a comprises in each case one fluid supply path 20a, 22a for each electrochemical cell 14a, 16a, 56a, 58a, wherein the fluid supply paths 20a, 22a are in particular uniquely assigned to in each case one electrochemical cell 14a, 16a, 56a, 58a. For the sake of clarity, in FIG. 1, only five fluid supply paths 20a, 22a are illustrated, analogously to the electrochemical cells 14a, 16a, 56a, 58a, and only two are denoted by reference designations. Furthermore, in the present case, all of the fluid supply paths 20a, 22a are at least substantially of equal length.

[0048] The first fluid supply path 20a and the second fluid supply path 22a lead from a common inlet 24a to the electrochemical cells 14a, 16a. Furthermore, the first fluid supply path 20a and the second fluid supply path 22a lead from the electrochemical cells 14a, 16a to a common outlet 26a. The inlet 24a and the outlet 26a are connected to the fluid circuit (not shown). In the normal operating state, the fluid circulates from the inlet 24a through the cell stack 46a to the outlet 26a, from there through a return line and/or a fluid reservoir and/or a filter and/or a pump or the like, and back to the inlet 24a. The inlet 24a is connected to the first end plate 52a and/or is at least partially formed by the latter. The outlet 26a is connected to the second end plate 54a and/or is at least partially formed by the latter. The inlet 24a and the outlet 26a are arranged offset with respect to one another, in particular as viewed parallel to the stack direction 50a.

[0049] The fluid supply unit 18a has at least one inlet channel 28a and at least one outlet channel 30a, which are provided for conducting the fluid, in the normal operating state, in an inlet flow direction 32a and in an outlet flow direction 34a which run at least substantially parallel to one another. In the present case, the inlet flow direction 32a runs parallel to the outlet flow direction 34a. The inlet flow direction 32a runs parallel to the stack direction 50a. The outlet flow direction 34a runs parallel to the stack direction 50a.

[0050] A sum of a length of a first inlet portion 36a and of a length of a first outlet portion 38a of the first fluid supply path 20a at least substantially corresponds to a sum of a length of a second inlet portion 40a and of a length of a second outlet portion 42a of the second fluid supply path 22a. In particular, the first inlet portion 36a and the second inlet portion 40a respectively extend in each case from the inlet 24a to the first electrochemical cell 14a and to the second electrochemical cell 16a respectively. Furthermore, in the present case, the first outlet portion 38a and the second outlet portion 42a respectively extend in each case from the first electrochemical cell 14a and from the second electrochemical cell 16a respectively to the outlet 26a. In the present case, the first inlet portion 36a is shorter than the second inlet portion 40a. Furthermore, in the present case, the first outlet portion 38a is longer than the second outlet portion 42a, in particular by exactly the same extent.

[0051] A pressure loss in the first inlet portion 36a is greater than a pressure loss in the second inlet portion 40a. Furthermore, a pressure loss in the first outlet portion 38a is smaller than a pressure loss in the second outlet portion 42a. In particular, a sum of partial pressure losses in the first inlet portion 36a, in the first electrochemical cell 14a and in the first outlet portion 38a at least substantially corresponds to a sum of partial pressure losses in the second inlet portion 40a, in the second electrochemical cell 16a and in the second outlet portion 42a.

[0052] The inlet channel 28a at least partially, in particular completely, forms the first inlet portion 36a and the second inlet portion 40a. The outlet channel 30a at least partially, in particular completely, forms the first outlet portion 38a and the second outlet portion 42a. In the present case, in each case one fluid supply path 20a, 22a of the fluid supply unit 18a extends at least section-wise through the inlet channel 28a to in each case one electrochemical cell 14a, 16a, 56a, 58a of the cell unit 12a. Furthermore, in each case one fluid supply path 20a, 22a of the fluid supply unit 18a extends section-wise from in each case one electrochemical cell 14a, 16a, 56a, 58a of the cell unit 12a through the outlet channel 30a.

[0053] In the present case, that which has been described here by way of example for the first fluid supply path 20a and the second fluid supply path 22a applies analogously to all fluid supply paths 20a, 22a of the electrochemical cells 14a, 16a, 56a, 58a of the cell unit 12a.

[0054] FIG. 2 shows a functional element 44a of the first electrochemical cell 14a in a schematic plan view. In the present case, the functional element 44a is designed as a cell stack element. The functional element 44a is of plate-like form. The functional element 44a may for example be a bipolar plate, a pressure pad, perforated plate, a screen plate, a membrane or the like. As described above, the first electrochemical cell 14a is formed from a plurality of different functional elements 44a, in particular different functional cell stack elements, which are not individually illustrated in the figures. Furthermore, as described above, the cell stack 46a comprises a multiplicity of repeating units of different cell stack elements, which form the cell stack 46a and the electrochemical cells 14a, 16a, 56a, 58a thereof.

[0055] The functional element 44a forms at least a section of the first fluid supply path 20a and at least a section of the second fluid supply path 22a. A length of said portions at least substantially corresponds to a thickness of the functional element 44a, which lies in particular in a range from approximately 0.1 mm to several millimeters.

[0056] The functional element 44a has a first recess 60a which, in the present case, is designed as a leadthrough. The first recess 60a is provided for being arranged in a line, in particular in alignment, with other recesses, which are in particular of analogous design, of other functional elements, and/or for forming the inlet channel 28a together with said other recesses. The inlet channel 28a extends in particular through multiple different functional elements 44a of different electrochemical cells 14a, 16a, 56a, 58a. In the present case, the functional element 44a has three first recesses 60a, 62a, 64a of analogous design. Correspondingly, the fluid supply unit 18a has, in the present case, three inlet channels 28a which are of analogous design and which in particular run parallel.

[0057] The functional element 44a has a second recess 66a which, in the present case, is designed as a leadthrough. The second recess 66a is provided for being arranged in a line, in particular in alignment, with other recesses, which are in particular of analogous design, of other functional elements, and/or for forming the outlet channel 30a together with said other recesses. The outlet channel 30a extends in particular through multiple different functional elements 44a of different electrochemical cells 14a, 16a, 56a, 58a. In the present case, the functional element 44a has three second recesses 66a, 68a, 70a of analogous design. Correspondingly, the fluid supply unit 18a has, in the present case, three outlet channels 30a which are of analogous design and which in particular run parallel.

[0058] The recesses 60a, 62a, 64a, 66a, 68a, 70a are open toward an interior of the first electrochemical cell 14a, such that the first fluid supply path 20a can lead through the first electrochemical cell 14a. In particular, the first fluid supply path 20a branches off from the inlet channel 28a into an interior space of the first electrochemical cell 14a, and/or from the interior space of the first electrochemical cell 14a into the outlet channel 30a. The functional elements 44a of the cell stack 46a form the electrochemical cells 14a, 16a, 56a, 58a and the fluid supply paths 20a, 22a of the fluid supply unit 18a. The recesses 60a, 62a, 64a, 66a, 68a, 70a are arranged such that, together, they extend over at least a predominant part of a width of the functional element 44a, whereby it is advantageously possible for pressure gradients in a transverse direction to be avoided and/or for a uniform fluid throughflow to be achieved.

[0059] It is conceivable that the inlet channels 28a are cross-connected or that the fluid supply unit 18a has a single inlet channel 28a, which in particular extends over at least a predominant part of a width of the functional element 44a. The outlet channels 30a may analogously be cross-connected. Likewise, the fluid supply unit 18a may analogously have a single, wide outlet channel 30a.

[0060] FIG. 3 shows the electrochemistry device 10a in a schematic frontal view as viewed in the stack direction 50a. In the present case, the inlet 24a is designed as a multiply branched line, wherein in each case one line branch is connected to one of the inlet channels 28a. Analogously, the outlet 26a is designed as a multiply branching line, wherein in each case one line branch is connected to one of the outlet channels 30a. In particular, it is thus the case that any fluid supply paths 20a, 22a are of equal length proceeding from a main line of the inlet 24a to a main line of the outlet 26a, analogously to the fluid supply paths 20a, 22a within the cell unit 12a.

[0061] FIGS. 4 to 6 show three further exemplary embodiment of the invention. The following descriptions and the drawings are substantially restricted to the differences between the exemplary embodiments, wherein, with regard to identically designated components, in particular with regard to components with the same reference designations, reference may basically also be made to the drawings and/or to the description of the other exemplary embodiments, in particular of FIGS. 1 to 3. To distinguish the exemplary embodiments, the alphabetic character a has been added as a suffix to the reference designations of the exemplary embodiment in FIGS. 1 to 3. In the exemplary embodiments of FIGS. 4 to 6, the alphabetic character a has been replaced by the alphabetic characters b to d.

[0062] FIG. 4 shows a first alternative electrochemistry device 10b in a schematic side view. The first alternative electrochemistry device 10b has a cell unit 12b which comprises at least one first electrochemical cell 14b and at least one second electrochemical cell 16b. Furthermore, the first alternative electrochemistry device 10b has a fluid supply unit 18b for supplying the cell unit 12b with at least one fluid. The fluid supply unit 18b comprises at least one first fluid supply path 20b extending at least section-wise through the first electrochemical cell 14b, and at least one second fluid supply path 22b extending at least section-wise through the second electrochemical cell 16b. The fluid supply unit 18b is designed such that, in at least one normal operating state, a volume flow of the fluid through the first electrochemical cell 14b and through the second electrochemical cell 16b is at least substantially identical. In the present case, the first fluid supply path 20b and the second fluid supply path 22b are at least substantially of equal length.

[0063] The fluid supply unit 18b comprises at least one inlet channel 28b, which is arranged outside the electrochemical cells 14b, 16b and/or outside the cell unit 12b. The inlet channel 28b is a common inlet channel for the fluid supply paths 20b, 22b of the fluid supply unit 18b. Furthermore, the fluid supply unit 18b comprises at least one outlet channel 30b, which is arranged outside the electrochemical cells 14b, 16b and/or outside the cell unit 12b. The outlet channel 30b is a common outlet channel for the fluid supply paths 20b, 22b.

[0064] In the present case, the first electrochemical cell 14b and the second electrochemical cell 16b are, in particular uniquely, assigned in each case one feed portion 72b, 74b arranged outside the cell unit 12b. The feed portions 72b, 74b lead laterally into the electrochemical cells 14b, 16b. The electrochemical cells 14b, 16b are supplied with fluid individually and/or independently of one another. The feed portions 72b, 74b open into the common inlet channel 28b. Analogously, the fluid supply unit 18b comprises corresponding discharge portions 76b, 78b. In the present case, each electrochemical cell 14b, 16b of the cell unit 12b is uniquely assigned in each case at least one individual feed portion 72b, 74b and/or in each case at least one individual discharge portion 76b, 78b.

[0065] By means of the illustrated geometry of the fluid supply unit 18b, it is in particular also possible for arbitrarily arranged electrochemical cells to analogously be supplied uniformly with a fluid, in particular electrochemical cells which are not arranged in a stack and/or in a row.

[0066] FIG. 5 shows a first alternative electrochemistry device 10c in a schematic side view. The first alternative electrochemistry device 10c has a cell unit 12c which comprises at least one first electrochemical cell 14c and at least one second electrochemical cell 16c. Furthermore, the first alternative electrochemistry device 10c has a fluid supply unit 18c for supplying the cell unit 12c with at least one fluid. The fluid supply unit 18c comprises at least one first fluid supply path 20c extending at least section-wise through the first electrochemical cell 14c, and at least one second fluid supply path 22c extending at least section-wise through the second electrochemical cell 16c. The fluid supply unit 18c is designed such that, in at least one normal operating state, a volume flow of the fluid through the first electrochemical cell 14c and through the second electrochemical cell 16c is at least substantially identical. In the present case, the first fluid supply path 20c and the second fluid supply path 22c are at least substantially of equal length.

[0067] In the present case, the cell unit 12c comprises a plurality of cell stacks 46c, 80c, 82c, for example three cell stacks 46c, 80c, 82c, wherein any other desired number is conceivable. The first electrochemical cell 14c and the second electrochemical cell 16c are arranged in different cell stacks 46c, 80c of the cell unit 12c. The cell stacks 46c, 80c, 82c are connected electrically in series, wherein a parallel connection would however also be conceivable. The cell stacks 46c, 80c, 82c are hydraulically connected such that they are in each case assigned fluid supply paths of identical length. In the present case, volume flows through the individual cell stacks 46c, 80c, 82c are at least substantially identical to one another. In particular, the cell stacks 46c, 80c, 82c are hydraulically connected analogously to the electrochemical cells 14a, 16a of the exemplary embodiment of FIGS. 1 to 3.

[0068] FIG. 6 shows a first alternative electrochemistry device 10d in a schematic side view. The first alternative electrochemistry device 10d has a cell unit 12d which comprises at least one first electrochemical cell 14d and at least one second electrochemical cell 16d. Furthermore, the first alternative electrochemistry device 10d has a fluid supply unit 18d for supplying the cell unit 12d with at least one fluid. The fluid supply unit 18d comprises at least one first fluid supply path 20d extending at least section-wise through the first electrochemical cell 14d, and at least one second fluid supply path 22d extending at least section-wise through the second electrochemical cell 16d. The fluid supply unit 18d is designed such that, in at least one normal operating state, a volume flow of the fluid through the first electrochemical cell 14d and through the second electrochemical cell 16d is at least substantially identical. In the present case, the first fluid supply path 20d and the second fluid supply path 22d are at least substantially of equal length.

[0069] The cell unit 12d comprises a multiplicity of cell stacks 46d, 80d, 82d. The cell stacks 46d, 80d, 82d are hydraulically connected analogously to the electrochemical cells 14b, 16b of the exemplary embodiment of FIG. 4. The electrochemical cells 14d, 16d of the individual cell stacks 46d, 80d, 82d are hydraulically connected in each case in series with one another. It is also conceivable for each of the cell stacks 46d, 80d, 82d, as shown, to be supplied with fluid by the fluid supply unit 18d, but the individual electrochemical cells 14d, 16d of each stack are supplied with fluid in a non-uniform manner. For example, it is conceivable that, in the case of each cell stack 46d, 80d, 82d, an inlet and an outlet are arranged on the same side, and/or an inlet direction runs oppositely to an outlet direction, such that, in particular, different volume flows flow through individual electrochemical cells 14d, 16d of each cell stack 46d, 80d, 82d, but electrochemical cells 14d, 16d with analogous numbering in their cell stack 46d, 80d, 82d are in each case flowed through at least substantially identically.