Electrochemical cell and electrolyzer with a stack of electrochemical cells

Abstract

Electrochemical cell (2) of an electrolyzer, comprising - a cell frame (8) surrounding an interior space (9) of the electrochemical cell (2), - a first electrode (3) and a second electrode (4), - a bipolar separator plate (6) which is arranged in the interior space (9) and, in its outermost edge region (7), is supported on the cell frame (8) and interlockingly connected to the cell frame (8), wherein the cell frame (8) is formed from a fiber-reinforced plastic and has a modulus of elasticity ER, where 15,000 ≤ ER ≤ 20,000 N / mm2, and the bipolar separator plate has a modulus of elasticity EP, where 200,000 ≤ EP ≤ 220,000 N / mm2.

Description

[0001] 24055PW001

[0002] Schaeffler Technologies AG & Co. KG

[0003] 91074 Herzogenaurach (DE)

[0004] Sunfire AG

[0005] 01237 Dresden (DE)

[0006] Fiber-Tech Construction GmbH

[0007] 09116 Chemnitz (DE)

[0008] Sengicon GmbH

[0009] 09116 Chemnitz (DE)

[0010] Electrochemical cell and electrolyzer with a stack of electrochemical cells

[0011] Description:

[0012] The present invention relates to an electrochemical cell and an electrolyzer with a stack of electrochemical cells, in particular an alkaline electrolyzer.

[0013] With the increasing use of renewable energies, technologies for storing the generated electrical energy are gaining in importance. One possibility is storage in the form of hydrogen, which is produced using an electrolyzer. Depending on their design, such electrolyzers can consist of stacks of electrochemical cells. Typically, each cell has a steel frame, which can be circular or rectangular, surrounding the electrochemical cell and holding the bipolar separator plate, also made of steel or ceramic, which separates adjacent cells. Manufacturing and finishing such cell frames, with a diameter of, for example, 1.6 m, requires expensive lathes. Mass production of cell stacks is not yet practical.

[0014] It is an object of the present invention to provide a cell frame for an electrolyzer with a stack of electrochemical cells that is particularly easy to manufacture and also reliably withstands pressure and heat loads.

[0015] This problem is solved by the subject matter of the independent patent claim. Advantageous embodiments and further developments are the subject matter of the dependent claims.

[0016] According to one aspect of the invention, an electrochemical cell of an electrolyzer is provided, comprising a cell frame surrounding an interior space of the cell, as well as a first electrode and a second electrode arranged within the interior space of the cell. Furthermore, the electrochemical cell has a bipolar separator plate arranged within the interior space and held at its outermost edge by the cell frame, forming a positive connection with the cell frame. The cell frame is made of a fiber-reinforced plastic and has a modulus of elasticity ER of 15,000 < ER < 20,000 N / mm². 2 for example, about 17,000 N / mm, and the bipolar separating plate has a modulus of elasticity Ep of 200,000 < Ep < 220,000 N / mm 2 on.

[0017] The electrochemical cell has the advantage that the cell frame is particularly easy to manufacture, as it is made of plastic and can be produced using a casting, winding and / or laminating process and can be mass-produced with little effort.

[0018] Due to fiber reinforcement, the plastic exhibits high stability even under pressure and temperature stress. To withstand the highest loads, its modulus of elasticity is increased to 15,000 < E < 20,000 N / mm² through appropriate material selection and reinforcement. 2 set, while the bipolar separating plate, which is made of a metal, for example steel, has a modulus of elasticity Ep of 200,000 < Ep < 220,000 N / mm². 2 exhibits.

[0019] The elastic modulus of the cell frame can therefore be adjusted by selecting the appropriate plastic, fibers, and filler density, i.e., the proportion of fibers in the composite material. Furthermore, it can be adjusted by choosing the appropriate fiber orientation within the cell frame.

[0020] This ensures that the significantly stiffer bipolar partition plate can stabilize the frame. As it turns out, stress peaks occur particularly in corner areas of non-circular cell frames, which can be absorbed by the bipolar partition plate.

[0021] The electrochemical cell therefore has the advantage that it is particularly easy to manufacture in series and can also withstand high operating pressures and operating temperatures.

[0022] According to one embodiment of the invention, the bipolar partition plate is positively connected to the cell frame. For this purpose, the bipolar partition plate can have a profile for positive anchoring in the cell frame, particularly in its outermost edge region where it is held against the cell frame. This profile can consist of areas of the partition plate bent out of the plane of the partition plate, forming undercuts in the cell frame and thus anchoring the partition plate in the cell frame.

[0023] Such a separating plate can be inserted into the mold during the production of the cell frame and, after the cell frame has been formed, is anchored in the plastic mass of the cell frame by the profile in its outermost edge area.

[0024] This embodiment has the advantage that a particularly robust connection between the partition plate and the cell frame can be created in a simple manner. This allows the bipolar partition plate to stabilize the cell frame.

[0025] According to this embodiment, the separating plate can absorb mechanical stresses in the cell frame even if it exhibits a different thermal expansion behavior than the cell frame.

[0026] According to one embodiment, the cell frame has a non-round, in particular rectangular, shape. Such a shape is possible due to the previously described choice of material, without compromising the high stability of the electrochemical cell.

[0027] The plastic can be in the form of an epoxy resin or vinyl ester. In particular, it can be glass fiber reinforced and incorporate E-glass fibers. So-called E-glass fibers are particularly temperature-resistant and also resistant to many chemicals, which is why they are especially suitable for use in the electrochemical cells of an electrolyzer.

[0028] According to one embodiment, the electrodes are in electrically conductive contact with the bipolar separator plate and are positively connected to the bipolar separator plate, for example by screws or rivets. Alternatively, they can also be materially connected to the bipolar separator plate, for example by a weld.

[0029] Alternatively, a force-fit connection is also possible, which is then advantageously achieved via spring contacts. This embodiment allows for tolerance compensation, which is beneficial for a stable contact because the electrochemical cells are stacked together.

[0030] According to a further aspect of the invention, an electrolyzer with a stack of the described electrochemical cells is provided. The electrolyzer has the advantages already described in connection with the electrochemical cell. Embodiments of the invention are described below by way of example with reference to schematic drawings.

[0031] Figure 1 shows a stack of electrochemical cells according to one embodiment of the invention;

[0032] Figure 2 shows an electrochemical cell of the stack according to Figure 1 and

[0033] Figure 3 shows a section through a cell frame of the electrochemical cell according to Figure 2.

[0034] Figure 1 shows a partial cross-section through a stack 1 of electrochemical cells of an alkaline electrolyzer. A cell is indicated in the figure by the dashed box and designated by reference numeral 2. Each cell 2 comprises a first electrode 3, a second electrode 4, and a membrane 5 arranged between them. A separating plate 6 is arranged between adjacent cells 2. The separating plate 6 has, in particular, the function of conducting the electrolyte flowing in the interior 9 of the cell 2 and distributing it over the entire surface of the electrodes 3 and 4.

[0035] The separating plates 6 each have a first main surface 15 and a second main surface 16. While the first main surface 15 faces one cell 2 and limits it, the second main surface 16 faces the adjacent cell 2 and limits it.

[0036] In the embodiment shown, the separating plate 6 is made of metal, in particular steel.

[0037] In its edge regions 7, the partition plate 6 is held in the cell frame 8. The cell frame 8, which is only partially shown in the figures, can, for example, be annular or rectangular. The cell frame 8 of the electrochemical cells 2 is made of a plastic, in particular a glass fiber reinforced composite material. Adjacent cell frames 8 are connected to each other via seals 10 to create a fluid-tight seal for the interior 9 of the electrolyzer.

[0038] Since the cell frame 8 of the electrochemical cells 2 is made of a plastic and thus an electrically insulating material, the current supply to the electrodes 3, 4 is provided via a separate current distribution structure 13, which extends parallel to the electrodes 3, 4 and parallel to the separating plate 6 and contacts the electrodes 3, 4.

[0039] A contacting element 12 is provided for contacting through the separating plate 6. The contacting element 12 extends through the separating plate 6 from the first main surface 15 to the second main surface 16 and thus from one cell 2 to the adjacent cell 2.

[0040] The contacting element 12 connects the first electrode 3 of one cell 2 to the second electrode 4 of the adjacent cell 2, in order to connect the cells 2 of the stack 1 in series. The contacting element 12 and the current distribution structure 13 can, in particular, be made of metal.

[0041] The contacting element 12 can be connected to the separating plate 6 by a positive-locking or material-locking connection, in particular by screws or welding. A friction-locking connection is also conceivable, which is then preferably achieved using spring elements to ensure permanently good contact.

[0042] Figure 2 schematically shows an electrochemical cell 2 of an alkaline electrolyzer with a cell frame 8. The cell frame 8 is made of fiber-reinforced plastic and, in the embodiment shown, has a rectangular shape. The bipolar separator plate 6, which is made of a metal, in particular steel, is held in the cell frame 8 and serves to separate one electrochemical cell 2 from adjacent cells 2.

[0043] In corner areas 19 of the cell frame 8, through holes 18 are provided to connect the cell frame 8 to adjacent cell frames 8 to form a stack, for example by screwing them together.

[0044] Figure 3 shows a sectional view of a section of the electrochemical cell 2 with the cell frame 8. The cell frame 8 has a frame body that surrounds an interior space 9 of the electrochemical cell 2.

[0045] The bipolar separator plate 6 of the electrochemical cell 2 is mounted on the cell frame 8. The bipolar separator plate 6 has high strength. In contrast, the cell frame 8 has reduced strength. The connection between the cell frame 8 and the bipolar separator plate 6 is designed such that the bipolar separator plate 6 can stabilize the cell frame 8.

[0046] The partition plate 6 is embedded in the cell frame 8 with its edge region 7. The connection between the partition plate 6 and the cell frame 8 is particularly robust because the partition plate 6 has a profile 20 in its edge region 7 for a positive-locking connection with the cell frame 8. Due to the profile 20, the partition plate 6 is positively locked and particularly securely anchored in the cell frame 28.

[0047] The separating plate 6 can be connected to the cell frame 8 during its manufacture. For this purpose, its edge region 7 can be inserted into a mold in which the cell frame 8 is formed, and it can be molded into the plastic.

[0048] Other elements of cell 2, in particular the electrodes, are not shown in Figures 2 and 3 for the sake of clarity. Reference list:

[0049] 1 stack

[0050] 2 cells

[0051] 3 first electrode

[0052] 4 second electrode

[0053] 5 Membran

[0054] 6 Dividing plate

[0055] 7 Edge area

[0056] 8 cell frames

[0057] 9 Interior

[0058] 10 Seal

[0059] 12 Contact element

[0060] 13 Power distribution structure 15 First main surface 16 Second main surface 18 Through hole

[0061] 19 Corner area

[0062] 20 Profile

Claims

24055PW001 Patent claims:

1. Electrochemical cell (2) of an electrolyzer, comprising - a cell frame (8) surrounding an interior space (9) of the electrochemical cell (2), - a first electrode (3) and a second electrode (4), - a bipolar partition plate (6) which is arranged in the interior (9) and is held in its outermost edge region (7) on the cell frame (8) and is positively connected to the cell frame (8), wherein the cell frame (8) is made of a fiber-reinforced plastic and has a modulus of elasticity ER of 15,000 < ER < 20,000 N / mm 2 exhibits and the bipolar separating plate has a modulus of elasticity Ep of 200,000 < Ep < 220,000 N / mm² 2 exhibits.

2. Electrochemical cell (2) according to claim 1 , wherein the bipolar separating plate (6) has a profile (20) in its outermost edge region (7) for a form-fitting anchoring in the cell frame (8).

3. Electrochemical cell (2) according to claim 1 or 2, wherein the cell frame (8) has a substantially rectangular shape.

4. Electrochemical cell (2) according to one of claims 1 to 3, wherein the plastic is designed as an epoxy resin or vinyl ester.

5. Electrochemical cell (2) according to any one of claims 1 to 4, wherein the plastic is glass fiber reinforced and has E-glass fibers.

6. Electrochemical cell (2) according to any one of claims 1 to 5, wherein the electrodes (3, 4) are in electrically conductive contact with the bipolar separator plate (6) via a current distribution structure (13) and a contacting element (12) of the current distribution structure (13) is positively connected to the bipolar separator plate (6).

7. Electrochemical cell (2) according to any one of claims 1 to 5, wherein the electrodes (3, 4) are in electrically conductive contact with the bipolar separator plate (6) via a current distribution structure (13) and a contacting element (12) of the current distribution structure (13) is materially connected to the bipolar separator plate (6).

8. Electrochemical cell (2) according to one of claims 1 to 5, wherein the electrodes (3, 4) are in electrically conductive contact with the bipolar separating plate (6) via a current distribution structure (13) and a contacting element (12) of the current distribution structure (13) is force-fitted to the bipolar separating plate (6) via spring contacts.

9. Electrolyzer with a stack (1) of electrochemical cells (2) according to any one of claims 1 to 8.

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