Electrolysis Cell

Abstract

The invention comprises (i) two metallic half-cells forming an anode chamber and a cathode chamber, (ii) an anode and a cathode arranged in the anode chamber and the cathode chamber, respectively, (iii) a separator membrane separating the two electrodes, (iv) at least one inlet and one outlet for reactants and products for each half-cell, and (v) optionally a spacer for placing the two electrodes in their respective electrode chambers, the two metallic half-cells being connected around their periphery but electrically insulated, and having a wall thickness of 0.05 mm to 0.15 mm, in particular 0.070 mm to 0.1 mm.

Description

[Technical Field]

[0001] The present invention is in the field of electrolysis technology and relates to a novel electrolysis cell, an electrolysis stack comprising cells connected in series, a method for manufacturing the stack, and the use of the cells in the manufacture of the stack. [Background technology]

[0002] Achieving a greenhouse gas-free economy within the next 30 years is Europe's declared goal to combat climate change. Renewable energy sources will replace fossil fuels such as oil, coal and gas. Hydrogen will play a key role as part of the sustainable energy supply reform.

[0003] Whether for clean mobility, efficient supply of electricity and heat, as a reserve to offset fluctuating renewable energies, as an alternative fuel or as a process gas in industry, hydrogen is highly versatile as an energy carrier, can be used across sector boundaries, offers great potential for synergies and contains three times the energy density of gasoline by mass.

[0004] Sustainably and economically produced hydrogen is a central element in the fight against climate change, significantly reducing emissions in the energy, transport and industry sectors, especially of the harmful greenhouse gas CO2. Because of the wide variety of uses for hydrogen, the development of a global, cross-sectoral hydrogen economy, wherever possible, would also open up enormous opportunities for new technologies and business models. In industry, hydrogen-powered gas turbines are currently being researched. In fuel cells, it can be used in cars and buses. Hydrogen not only allows for emissions-free driving, but also allows for longer ranges and quicker refueling, in contrast to electric vehicles.

[0005] From an environmental point of view, hydrogen production by water electrolysis is of particular interest, hence the term "green hydrogen" is also used in this context. This method, also known as chlor-alkali electrolysis, is carried out in a combined electrolysis cell, a so-called electrolyzer.

[0006] The electrolysis cell is already known from Patent Document 1 and comprises a housing containing at least one pair of electrodes, i.e., a positive electrode and a negative electrode, a current collector and a membrane, and further comprises an electrically conductive, hydraulically permeable, resilient mattress arranged substantially flush with the current collector and in contact with the current collector on one side, and also extending flush with the electrodes and in contact with the electrode on the other side.

[0007] US Patent No. 5,949,999 describes a current collector for an electrochemical cell, which consists of a "sandwich" layer of compressible, elastic metal wires, which provides a predetermined mechanical load over a wide range of compression.

[0008] Patent document 3 provides a conventional electrolysis cell with a sealed system consisting of individual elements each containing two electrodes separated from each other by a membrane. The proportion of the inactive membrane area is minimized by the flanges so that the ratio between the area of ​​the flanges of the half shells and the active membrane area can be set to less than 0.045.

[0009] According to Patent Document 4, the elastic pressure in the electrolysis cell is transmitted by a coil or woven nickel mat or a tough nickel alloy. The number of turns in the case of the coil or the number of superposed layers in the case of the mat increases stepwise from top to bottom, so that finally, on the anode side, a pressure profile is obtained which increases in the same direction and is at least similar to a hydrostatic pressure.

[0010] Patent Document 5 describes an electrolysis cell with a separator and a planar, flexible cathode held in contact with the separator by an elastic conductive element pressed by a current distributor. The cell further includes an anode made of a punched sheet or mesh that supports the separator. This cell can be arranged modularly for use as an electrolytic cell, with only the end cells connected to a power source. Electrical continuity between adjacent cells is ensured by a conductive contact strip fixed to the outer anode wall of the shell that separates each cell. The rigidity of the cathode current distributor and anode structure, combined with the elasticity of the conductive element, ensures uniform pressure distribution and maintains uniform cathode-separator contact while also ensuring appropriate mechanical load on the contact strip. This allows the use of an elastic element to avoid electrode spacing.

[0011] Patent document 6 comprises a filter press type module for an electrolyzer, consisting of at least one closed frame defining at least one first opening, and a sealing and electrical insulating material, which material at least partially covers the surface of the frame.

[0012] Patent Document 7 proposes an electrolysis cell including an anode compartment having an anode and a cathode gas compartment having a gas diffusion cathode, the two electrodes being separated from each other by an ion exchange membrane, and further including a metallic elastic element clamped in a compressed state between a rear wall of the cathode gas compartment and the gas diffusion cathode, the elastic element being clamped to the cathode gas compartment so that the distance between the element and the rear wall increases in the direction of gravity.

[0013] Patent Document 8 proposes an insulating frame for an electrolysis cell having a geometric shape with corners. The frame has a flat design, an anode side, a cathode side, an outer end face, and an inner end face. The insulating frame has an end region directly adjacent to the inner end face, which has openings in the form of cutouts in the area of ​​the corners.

[0014] According to Patent Document 9, cell stabilization is achieved by a metal zigzag profile installed in the cathode gas chamber. However, this configuration of the electrolysis cell poses a problem. Physics dictates that the hydrostatic pressure in the anode compartment is not constant, but actually increases in the direction of gravity. Therefore, it is desirable, and quite sufficient for the purpose to be achieved, for the pressure exerted by the elastic internal parts to adapt to the hydrostatic pressure, i.e., increase in the direction of gravity. [Prior art documents] [Patent documents]

[0015] [Patent Document 1] U.S. Patent No. 5,599,430 [Patent Document 2] European Patent No. 1451389 [Patent Document 3] European Patent No. 1766104 [Patent Document 4] European Patent Publication No. 1882758 [Patent Document 5] European Patent No. 2356266 [Patent Document 6] European Patent No. 2734658 [Patent Document 7] European Patent Publication No. 2746429 [Patent Document 8] European Patent No. 2872675 [Patent Document 9] JP 2003-041388 A Summary of the Invention [Problem to be solved by the invention]

[0016] Schematically, an electrolytic cell consists of an anode chamber and a cathode chamber (AR, KR) that house an anode (A) and a cathode (K), respectively. The two electrodes are separated from each other by a diaphragm or separator membrane (S) on the one hand, and are fixed to the corresponding housing part, the "half cell," by elastic or rigid spacers (X1, X2) on the other hand, as shown diagrammatically in Figure 1. The figure also shows a seal (D) that connects the two surrounding electrode chambers, electrically insulating them and sealing them from the outside.

[0017] The anode and cathode chambers must be electrically isolated from each other to prevent short circuits. For optimal performance, it is further necessary that the electrodes lie flat, i.e., without gaps, on the separator membrane over their entire surface. This is achieved by one or more resilient spacers (X1, X2) within the cell. Furthermore, since the electrolysis cell is under slight excess pressure relative to the atmosphere, the seals must be both chemically and pressure resistant.

[0018] According to the prior art, electrolysis half-cells are manufactured from metal sheets with a thickness of at least 0.5 mm to provide the cells with sufficient stability and to prevent breakage during transportation or installation of the electrolyzer or electrolysis stack. However, this has the disadvantage that the cells are very heavy and rigid, which creates installation problems and of course increases the material cost.

[0019] In a first embodiment, the present invention provides a method for manufacturing a semiconductor device comprising: (i) two metallic half-cells forming the anode and cathode chambers; (ii) an anode and a cathode disposed in the anode chamber and the cathode chamber, respectively; (iii) a separator membrane separating the two electrodes; (iv) for each half-cell, at least one inlet and one outlet for reactants and products; and (v) optionally, a spacer for placing the two electrodes in their respective electrode chambers; It comprises or consists solely of: Here, two metallic half-cells are connected around their periphery but are electrically insulated and have a wall thickness of 0.05 mm to 0.15 mm, in particular 0.070 mm to 0.1 mm.

[0020] Preferably, the electrolysis cells are subjected to a slight low pressure, for example 0.5 to 0.15 bar, which makes the electrolysis cells vacuum-proof and particularly easy and safe to transport and subsequently stack.

[0021] Surprisingly, and contrary to scientific opinion, it has been found that it is readily possible to manufacture electrolytic cells which fully meet the requirements set out at the outset using very thin metal sheets, preferably metal foils. [Brief explanation of the drawings]

[0022] [Figure 1] FIG. 1 is a schematic diagram illustrating an electrolysis cell. [Figure 2] FIG. 2 is a schematic cross-sectional view of a periphery (P) in which a sealing composition (D) is distributed. [Figure 3] FIG. 1 shows the inlet and outlet of the plastic material used in the electrolysis cell. [Figure 4] FIG. 1 illustrates a typical electrolysis stack containing multiple electrolysis cells. DETAILED DESCRIPTION OF THE INVENTION

[0023] Electrolysis Cell

[0024] The anode and cathode are preferably arranged in a cell as shown schematically in Figure 1. That is, the two electrodes are arranged flatly with no gaps between them over their entire surfaces, and are in direct contact only with the separator membrane.

[0025] The half-cells are preferably made of stainless steel, nickel, titanium and corresponding alloys, which may contain other dissimilar metals such as vanadium.

[0026] Spacers can be resilient elements such as coils, rings, foams, or mattresses, or rigid structures, as discussed earlier in the prior art review. They can be static or resilient, and it is desirable to equip at least one electrode chamber with a resilient spacer to ensure that the electrode is flat.

[0027] The two half-cells must be connected to each other around their periphery, but must also be electrically insulated from each other. This can be preferably achieved by introducing a sealing composition. Figure 2 shows a schematic cross-section of the periphery (P) where the sealing composition (D) is distributed. In the center, the separator membrane (S) is visible, which is also surrounded on both sides by the sealing composition. In this way, the separator membrane is simultaneously fixed and stabilized within the cell.

[0028] The plastic composition can be introduced by conventional methods of plastics processing, i.e., direct thermal bonding, adhesive bonding, hot melt, or lamination. Direct thermal bonding is particularly preferred because it is not technically demanding. This method functions similarly to injection molding: the plastic material is melted and injected onto the sealing surface. Upon cooling, the polymer transforms back into a solid state, sealing the two half-cells. Suitable electrically insulating plastic materials are primarily thermoplastics, with perfluoroalkoxy polymers (PFA) and polyphenylsulfide (PPS) being preferred due to their high chemical resistance.

[0029] In a further preferred embodiment of the present invention, inlets and outlets for the products and reactants are arranged at the junction between the two half-cells. In particular, connections known from the food industry, such as the welded spout made of injection-moldable plastic material shown in FIG. 3, are considered. A corresponding connection or spout is disclosed in EP 2 644 530, the disclosure of which regarding the properties of the spout is incorporated by reference. The connection or spout has a neck (3) with a pouring channel (2) having a vertical central longitudinal axis (1) and two outer side surfaces connected thereto, preferably provided with a weld line, which are provided for welding to the seals of the electrolysis cell, and the associated side walls have a number of reinforcing webs arranged on the inside.

[0030] The aforementioned outlet or pouring spout generally has a base, also called a "boat," whose side walls have outer sidewall surfaces that merge into each other at their end regions. The sidewalls are connected, particularly by welding, between the two foil walls of the container. A collar-like region that merges into a neck with a flow channel having a vertical central longitudinal axis is formed in the boat or sidewall and is typically integral with the neck. Such necks often have threads attached to their exterior to secure the filled pouch with the cap before emptying it through the channel. Alternatively, the neck can merge at least partially directly into the boat. The sides of the boat can be flat, roughened, ribbed or not, and / or have weld lines. Furthermore, the neck can have guide webs that can be used to guide the filling or sealing system.

[0031] According to EP 2 644 530 the connection or spout is generally connected to the seal by ultrasonic welding. In the present invention, the welded spout is preferably introduced directly in the joining process. Electrolysis stack and method of manufacturing the same

[0032] The individual electrolysis cells can be grouped together into groups called "electrolyzers" or "electrolysis stacks." Accordingly, the present invention further provides an electrolysis stack comprising: (i) at least two electrolytic cells as described above; (ii) two (metal) pressure plates, and (iii) Comprising or consisting solely of at least two tension rods. where: (a) Two pressure plates face each other and are movably or rigidly spaced apart by at least two tension rods, and the connections by the tension rods preferably have high electrical resistance or insulation. (b) At least two electrolytic cells are arranged or stacked relative to one another between two pressure plates, in each case the cathode rear wall of the first electrolytic cell contacts the anode rear wall of the next electrolytic cell. (c) a pressure plate, together with at least two vacuum-enhanced electrolytic cells, spaced apart from one another in fixed relation;

[0033] The electrolysis stack of the present invention preferably comprises 3, 4, 5 or up to about 200 of the aforementioned electrolysis cells, preferably from about 40 to about 150, especially from about 60 to about 120, electrolysis cells.

[0034] A typical electrolysis stack is shown in FIG. 4, where the electrolysis cells shown each have a structure according to FIG.

[0035] Similarly, a method for manufacturing an electrolysis stack may include: (i) providing at least two electrolysis cells according to claim 1; (ii) providing two pressure plates; and (iii) providing at least two tension rods. where (a) At least two electrolytic cells are vacuum-backed with a low pressure applied to them. (b) The vacuum-stiffened electrolytic cells from step (a) are arranged or stacked relative to one another and electrically connected in series such that the cathode back wall of a first electrolytic cell contacts the anode back wall of the next electrolytic cell. (c) The vacuum-stiffened electrolytic cells connected in series according to step (b) are placed between two pressure plates by at least two tension rods to create a fixed relationship. (d) The vacuum in the electrolytic cell, having been generated, is released again.

[0036] The construction of the present invention allows the conventional single cell design to be adapted to cells with small wall thicknesses. According to the present invention, these thin sheets or foils are used as the shell, electrically isolated from each other by joints and separators, and the internal components are introduced during the manufacturing process. After the manufacturing process, the cell is subjected to low pressure, which pre-compresses the internal elastic element or mattress. At the same time, this operation vacuum-stiffens the cell, which has the following advantages, previously unavailable in the prior art: - Reinforcement of flexible components - Unassisted transportability achieved through vacuum lifting systems and mechanical gripper systems - Airtightness test - detection of damage caused by transport, and - Preloading of elastic elements of the system.

[0037] As a result of the preloading of the elements, the cells can be introduced into a stack that does not need to include clamping devices, but which press the resilient elements together and provide the possibility of compression, including displacement of the pressure plate. The metal pressure plate can be held together simply by tension rods and simply brought into contact with the vacuum-stiffened elements during initial assembly. By releasing the vacuum, the resilient elements are no longer loaded by external pressure and are now held in place by the pressure plate.

[0038] The resulting stack can be used, for example, in chlor-alkali electrolysis, but is preferably used for the production of hydrogen by water electrolysis. Industrial Applicability

[0039] The present invention further provides the use of an electrolysis cell according to the present invention in the manufacture of an electrolysis stack.

Claims

1. (i) two metallic half-cells forming the anode and cathode chambers; (ii) an anode and a cathode disposed in the anode chamber and the cathode chamber, respectively; (iii) a separator membrane separating the two electrodes; (iv) for each half-cell, at least one inlet and one outlet for reactants and products; and (v) spacers that position the two electrodes flat against the separator within the anode and cathode chambers; An electrolysis cell comprising or consisting of: An electrolysis cell, wherein the two metallic half-cells are connected around their periphery and electrically insulated, and have a wall thickness of 0.05 mm to 0.15 mm.

2. 10. The electrolysis cell of claim 1, wherein the half-cells are made of stainless steel, nickel, titanium, or their corresponding alloys, or the alloys contain other dissimilar metals.

3. 3. The electrolysis cell of claim 1 or claim 2, wherein the spacer is a resilient element.

4. 4. An electrolysis cell according to any one of claims 1 to 3, wherein the two half-cells are connected to each other at the periphery with an electrically insulating plastic.

5. 5. The electrolysis cell of claim 1, wherein the inlet and the outlet are spouts of plastic material located at the junction between the two half-cells.

6. 6. The electrolytic cell of any one of claims 1 to 5, wherein the electrolytic cell is subjected to a low pressure of 0.5 to 0.15 bar.

7. (i) at least two electrolytic cells according to claim 1; (ii) two pressure plates; and (iii) at least two tension rods, (a) the two pressure plates face each other and are movably or rigidly spaced apart by at least two tension rods; (b) at least two of said electrolytic cells are positioned or stacked relative to one another between two pressure plates such that the cathode back wall of a first electrolytic cell contacts the anode back wall of a next electrolytic cell; (c) an electrolysis stack, wherein the pressure plate, together with at least two electrolysis cells, are spaced apart in fixed relation to one another;

8. 8. The electrolysis stack of claim 7, wherein the electrolysis stack comprises between 2 and 150 electrolysis cells.

9. (i) providing at least two electrolysis cells according to claim 1; (ii) providing two pressure plates; and (iii) providing at least two tension rods, (a) at least two of said electrolytic cells are subjected to a low pressure; (b) the electrolytic cells to which the low pressure has been applied in step (a) are arranged or stacked relative to one another and electrically connected in series such that the cathode rear wall of a first electrolytic cell contacts the anode rear wall of a second electrolytic cell; (c) the electrolytic cells connected in series according to step (b) are placed between two pressure plates by at least two tension rods to create a fixed relationship; (d) A method for manufacturing an electrolysis stack, in which the vacuum of the electrolysis cells in which a certain association has been created is released again.

10. Use of an electrolysis cell according to at least one of claims 1 to 6 in the manufacture of an electrolysis stack.

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