Electrolysis cell

Abstract

The invention relates to a polymer electrolyte membrane (PEM) water electrolysis cell for producing hydrogen, the cell comprising a proton exchange membrane (11), an anode compartment (12) in contact with the membrane, a cathode compartment (13) in contact with the proton exchange membrane (11) and a first conductive plate (6) in contact with the anode compartment (12) and a second conductive plate (7) in contact with the cathode compartment (13), the proton exchange membrane (11), the anode compartment (12) and the cathode compartment (13) being kept clamped between the first conductive plate (6) and the second conductive plate (7), the first and second conductive plates (6, 7) being monopolar, the cell (1) comprising a peripheral frame (8) that is attached to the first and second conductive plates (6, 7) to keep the first and second conductive plates (6, 7) clamped together, the frame (8) comprising at least two openings which open into the anode compartment (12) and into two respective channels (20) and at least two openings that open into the cathode compartment (13) and into two other respective channels (20), the channels (20) being parallel to each other.

Description

Description Title of the invention: Electrolysis cell

[0001] The invention relates to the field of electrolysis, in particular for the production of hydrogen.

[0002] The invention relates to an electrolysis cell and an electrolysis installation with several stacked cells.

[0003] To industrially produce hydrogen in a decentralized and environmentally friendly manner, water electrolysis is preferred to reforming. Current electrolyzer devices comprise a plurality of electrochemical cells, supplied with water, and each comprising a pair of electrodes. For reasons of cost and size in particular, the cells are generally flat and grouped into one or more stacks, so that two superimposed cells each have a common electrode.

[0004] To reduce costs, particularly related to the manufacturing and operation of stacks, we generally seek to maximize the number of cells per stack. By applying a direct current between the anode and cathode of each cell, using a generator whose output voltage can be adjusted, the electrolysis reaction of water is triggered. Dihydrogen H2 and dioxygen O2 are thus produced.

[0005] Joints have been proposed that allow stacking a large number of cells, for example up to 300 cells. The cells are capable of withstanding high clamping forces and internal pressures of approximately 45 bar. Such joints are described, for example, in WO 2015 / 004378.

[0006] When such seals are used under even higher pressures and / or with significant pressure differences between two compartments of the same cell, deformations may occur. In addition, seals fitted in pairs for each cell require careful assembly of the cell otherwise they may malfunction.

[0007] FR3062856 provides a spacer to wedge the bipolar plates and the cell membrane.

[0008] The Applicant sought to increase the load factor of a stacked multi-cell electrolysis plant.

[0009] The invention improves the situation.

[0010] The invention provides a water electrolysis cell with a PEM polymer electrolytic membrane for the production of hydrogen, comprising a proton exchange membrane, an anode compartment in contact with the membrane, a cathode compartment in contact with the proton exchange membrane, and a first plate conductive in contact with the anode compartment and a second conductive plate in contact with the cathode compartment, characterized in that the proton exchange membrane, the anode compartment and the cathode compartment are held clamped between the first plate and the second conductive plate. The first and second conductive plates are monopolar. The cell comprises a peripheral frame fixed to the first and second conductive plates and holding the first and second conductive plates clamped. The frame comprises at least two openings opening into the anode compartment and into two respective channels and at least two openings opening into the cathode compartment and into two other respective channels. The channels are parallel. Thanks to the invention, each cell has a constructive independence allowing individual disassembly.Thus, a cell from a stack of cells can be removed while maintaining the mechanical integrity of the other cells in the stack of cells. In addition, each cell can be manipulated individually. Each cell can be tested individually.

[0011] In one embodiment, the first and second conductive plates have parallel surfaces, opposite each other and opposite the frame. Electrical contact can be established between adjacent cells.

[0012] In one embodiment, the frame is made of an insulating material. The first and second conductive plates are electrically insulated from each other.

[0013] In one embodiment, the first and second conductive plates are secured to the frame. The cell maintains its integrity when outside of a cell stack.

[0014] In one embodiment, at least four communication openings are provided in each of said first and second conductive plates in communication with said respective channels. Increasing the number of communication openings increases the efficiency of the cells and their lifespan. The rigidity of the stack is improved. Alignment is facilitated.

[0015] In one embodiment, the first conductive plate is made of a material selected from titanium, aluminum, coated mild steel, coated copper, coated stainless steel, zirconium, niobium, tantalum, tungsten or one of their alloys and the second conductive plate is made of a material selected from titanium, aluminum, coated mild steel, coated copper, coated stainless steel, zirconium, niobium, tantalum, tungsten or one of their alloys, or a carbon material such as graphite, the coating of the coated materials being made of chromium carbide or titanium carbide. The performance of the cell is improved and its production is facilitated.

[0016] In one embodiment, the channels are perpendicular to the openings of communication. The footprint is reduced and the stacking is optimized. This increases the power density of the stack.

[0017] In one embodiment, a plurality of first fixing holes are provided in the first and second conductive plates opposite the frame and a plurality of projections integral with the frame comprising a body passing through the first fixing holes of the first and second conductive plates and a head with a diameter greater than the diameter of the body, thus fixing the first and second conductive plates to the frame. The monopolar plates are held uniformly around the periphery of the cell. The mechanical strength is improved and the resistance to internal pressure is optimized. The mounting of the monopolar plates is facilitated.

[0018] In one embodiment, a plurality of second holes are provided in said first and second conductive plates opposite the frame, said second holes having a diameter greater than the diameter of said heads, said second holes being alternated with the first fixing holes. The projections of a cell of the previous or next row in a stack are housed in the second holes. The second holes of a cell of the previous or next row in a stack house the projections of the cell in question.

[0019] In one embodiment, the frame has a step for positioning the proton exchange membrane, the anode compartment comprises two porous transport layers of different porosities, the cathode compartment comprises two porous transport layers of different porosities. The step allows precise positioning of the proton exchange membrane and control of the boundary between the cathode compartment and the anode compartment.

[0020] In one embodiment, the first and second conductive plates are sealed with the frame. The seal between the frame and the monopolar plates ensures the proper flow of water and gases into the appropriate cavities. The risk of introducing impurities and dust into the cells is reduced.

[0021] In one embodiment, a water electrolysis installation for the production of hydrogen comprises a stack of a plurality of cells and has aligned channels, the first conductive plate of one of the cells being in contact with the second conductive plate of another of said cells. The installation can be dismantled, cell by cell, at the hydrogen production site. A return of the installation to the factory is avoided. A defective cell can be returned to the factory while the other cells, whether or not replenished with a replacement cell, can be put back into service. The duration of a production shutdown is greatly reduced. The installation remains in place.

[0022] In one embodiment, a method of maintaining a water electrolysis device includes loosening a stack of a plurality of cells, removing of at least one electrolysis cell from the stack of a plurality of cells and tightening the stack. Maintenance whereby defective cells can be replaced without compromising the integrity of the device makes it possible to avoid a return to the factory to carry out a repair of the electrolysis device

[0023] In one embodiment, prior to tightening the stack, at least one electrolysis cell is inserted to replace at least one removed electrolysis cell. Power is retained.

[0024] In one embodiment, assembly of an electrolysis cell, testing of the electrolysis cell, and, if the test is satisfactory, mounting of the electrolysis cell in a stack of a plurality of cells are performed. The risk of having to disassemble a complete stack that proves defective at the end of manufacture is reduced.

[0025] Other characteristics and advantages of the invention will appear on examining the detailed description below, and the appended drawings, in which:

[0026] [Fig.1] schematically illustrates a water electrolysis cell in top view.

[0027] [Fig.2] schematically illustrates a water electrolysis cell in exploded view.

[0028] [Fig.3] schematically illustrates in perspective and in section a water electrolysis cell.

[0029] [Fig.4] illustrates schematically and in section, an enlargement of [Fig.3] at the level of the anode and cathode compartments.

[0030] [Fig.5] illustrates the frame of a water electrolysis cell in top view equipped with seals.

[0031] [Fig.6] illustrates the frame of a water electrolysis cell seen from below.

[0032] [Fig.7] is a detailed sectional view of an electrolysis cell.

[0033] [Fig.8] is a sectional view of a stack of three electrolysis cells.

[0034] [Fig.9] illustrates the frame of an electrolysis cell equipped with a seal.

[0035] [Fig.10] illustrates a sectional view of a stack of two electrolysis cells.

[0036] [Fig.11] illustrates an electrolysis cell in top view, anode side.

[0037] [Fig.12] illustrates a detailed view of an electrolysis cell from above, anode side.

[0038] The attached drawings may not only serve to complete the invention, but also contribute to its definition, where appropriate.

[0039] The figures represent a water electrolysis cell according to one aspect of the invention.

[0040] WO2019228616 gives an example of a stack of electrolysis cells clamped together by bolts.

[0041] W02014060198 gives an example of a mixed stack of fuel cell and supercapacitors.

[0042] The Applicant observed that at the end of production of a stack, a test of a stack producing an unsatisfactory result involved disassembly, identification of the defect, then reassembly of the stack.

[0043] When in use, dismantling such stacks for maintenance was carried out upon return to the factory and proved tedious and expensive. Production was interrupted for a period of several days to several weeks.

[0044] In both cases, disassembly and reassembly cause parts of other cells to move and create risks of fouling or the introduction of unwanted elements. A controlled environment and careful recalibration were then required.

[0045] The Applicant then developed mechanically independent cells forming a manipulable and sufficiently protected sub-assembly. A stack of such cells can be dismantled at the hydrogen production site while preserving the integrity of the cells. For this purpose, the cells are provided with monopolar plates.

[0046] In the following, the terms "anode", "cathode" and their derivatives are used in accordance with what is shown in the figures. However, the proposed electrolyzer structures can operate in an inverse manner compared to what is shown. For example, by reversing the polarization and exchanging the assignments of the fluid inlets and outlets, the anode compartment can become the cathode compartment and vice versa. However, the materials are optimized for the anode on the one hand, for the cathode on the other hand.

[0047] Electrolysis cells comprise a plurality of bipolar plates, see WO2019228616. The bipolar plates are used for current collection, distribution and separation of gases at the anode and cathode. The bipolar plates are made of a material having high electrical conductivity and lower gas permeability than the proton exchange membrane. The bipolar plates have good chemical inertness. The bipolar plates are generally made of titanium. The first side of the plate acts as the anode of a first cell and the second side acts as the cathode of the second adjacent cell.

[0048] The gases are produced by electrolysis of water, namely oxygen and hydrogen.

[0049] The Applicant sought to increase the charging rate of a stacked electrolysis cell installation. The Applicant observed an increase in maintenance requirements for existing installations. Furthermore, the demand for hydrogen is growing, resulting in an equally increasing unit power of the installations. Currently, there are installations of a few MW.

[0050] In the event of a fault in an installation, it is dismantled and identified of the defective element, its replacement and reassembly. The downtime is from a few days to a few weeks.

[0051] The Applicant has designed and developed a monopolar plate cell with internal clamping. Each cell has its own polar plates. Said own polar plates are designed to come into electrical contact with adjacent cells through their own polar plates. Each cell is riveted. The riveting ensures that the cell components are held in place in the absence of external clamping. The cell can be handled and tested.

[0052] Polar plates are monopolar plates.

[0053] The electrochemical aspect of a water electrolysis stack is illustrated in [Fig.l] of patent FR3062856.

[0054] As illustrated in [Fig.l], the water electrolysis cell 1 is rectangular in shape with two long sides 4 in length, two short sides 5 in width, a first surface 2 and a second surface 3. The first surface 2 and second surface 3 are parallel and opposite. The electrolysis cell 1 has a small thickness from the first surface 2 to the second surface 3, at least by a factor of ten, preferably by a factor of one hundred, relative to the length of the short sides 5.

[0055] The cell 1 comprises a first monopolar plate 6 forming the first surface 2 and a second monopolar plate 7 forming the second surface 3. The first and second monopolar plates 6, 7 are conductive.

[0056] In one embodiment, the plates are monopolar and identical.

[0057] Between the first monopolar plate 6 and the second monopolar plate 7, the cell 1 comprises a frame 8 having the same length and width as the monopolar plates. The frame 8 comprises a body 9. The body 9 of the frame 8 has a frame shape with a cavity 10. The cavity 10 is rectangular. The cavity 10 is central. The cavity 10 is through. The body 9 of the frame 8 has a thickness less than or equal to the distance between the monopolar plates. The body 9 of the frame 8 has a thickness less than the thickness of the frame 8. The frame 8 is made of insulating material.

[0058] Alternatively, the dimensions of the monopolar plates 6, 7 may differ from those of the frame 8.

[0059] The cell 1 comprises a proton exchange membrane, or PEM membrane. The proton exchange membrane 11 is mounted in the cavity 10 of the body 9 of the frame 8. The proton exchange membrane 11 is arranged at a distance from the monopolar plates. The proton exchange membrane 11 fits the edge of the cavity 10, i.e. the inner periphery of the body. The proton exchange membrane 11 covers the surface of the cavity 10. The contact between the proton exchange membrane 11 and the body 9 of the frame 8 is sealed.

[0060] The proton exchange membrane 11 forms within cell 1, two corn- separate compartments, a cathode compartment 13 and an anode compartment 12. The anode compartment 12 is delimited along two parallel planes by the proton exchange membrane 11 and the first monopolar plate 6, and the inner periphery of the body. The cathode compartment 13 is delimited along two parallel planes by the proton exchange membrane 11 and the second monopolar plate 7, and the inner periphery of the body.

[0061] In the illustrated embodiment, the anode compartment 12 houses at least one porous anode transport layer 14. In the illustrated embodiment, the cathode compartment 13 houses at least one porous cathode transport layer 114.

[0062] The anode porous transport layer 14 or the cathode porous transport layer 114 is compressed between the proton exchange membrane 11 and the first or second monopolar plate. The anode porous transport layer 14 or the cathode porous transport layer 114 is configured to press on the major part of the proton exchange membrane 11. The anode porous transport layer 14 or the cathode porous transport layer 114 ensures uniform support of the proton exchange membrane 11. The rigidity of the porous transport layers 14, 114 ensures flatness of the membrane, especially when the pressure difference between the anode compartment 12 and the cathode compartment 13 is high.

[0063] In one embodiment, the positioning and holding of the proton exchange membrane 11 can be achieved using a step 15 provided on the body 9 of the frame 8. The step 15 can have a radial annular surface for the proton exchange membrane 11.

[0064] In the illustrated embodiment, at least one porous spacer 16 may be disposed between the porous transport layer 14 and the first monopolar plate 6 and at least one porous spacer 16 may be disposed between the porous transport layer 14 and the second monopolar plate 7. The porous spacer 16 improves the diffusion of water on the active surface of the proton exchange membrane 11.

[0065] The materials of the parts of the anode compartment 12 are resistant to acidic and oxidizing environments. The materials of the parts of the cathode compartment 13 are resistant to acidic and reducing environments. The materials of the parts of the cathode compartment 13 are resistant to the phenomenon of hydriding by hydrogen.

[0066] The first and second monopolar plates 6, 7 may be made independently of a conductive material chosen from titanium, aluminum, coated mild steel, coated copper, coated stainless steel, zirconium, niobium, tantalum, tungsten or one of their alloys.

[0067] The coating may comprise CrC or TiC or a mixture of both. The re- The garment protects surfaces in contact with fluids. The CrC and / or TiC coating improves resistance.

[0068] Thus, the use of a CrC and / or TiC coating makes it possible to reduce the use of titanium. However, in addition to its high cost, the production of titanium parts is complex.

[0069] On the other hand, titanium supply is complex due to the rarity of the material.

[0070] The porous transport layers 14 of the anode compartments 12 and the porous transport layers 114 of the cathode compartments 13 may have different thicknesses of between 0.5 and 3 mm. The porous transport layers 14 of the anode compartments 12 may be made of a conductive material resistant to acidic and oxidizing media such as titanium. The porous transport layers 114 of the cathode compartments 13 may be made of a conductive material resistant to acidic and reducing media such as carbon or titanium. The porous transport layers 14 of the anode compartments 12 have a porosity of between 20% and 70%. The porous transport layers 114 of the cathode compartments 13 may have porosities of between 20% and 70%.

[0071] The porous spacers 16 of the anode compartments 12 and the porous spacers 116 of the cathode compartments 13 may have different thicknesses of between 0.5 and 3 mm. The porous spacers 16 of the anode compartments 12 can be made of a conductive material resistant to acidic and oxidizing environments such as titanium. The porous spacers 116 of the cathode compartments 13 can be made of a conductive material resistant to acidic and reducing environments such as carbon or titanium. The porous spacers 16 of the anode compartments 12 have a porosity of between 30% and 80%. The porous spacers 116 of the cathode compartments 13 have a porosity of between 30% and 80%.

[0072] In another embodiment, the monopolar plates 6, 7 are different. The monopolar cathode plate 7 may be made of titanium or titanium alloy, or of a dense graphite material, to prevent hydrogen diffusion through the monopolar plate 7. A graphite and metal mixture may be considered. The monopolar anode plate 6 may be made of titanium or another conductive material such as copper or aluminum or a copper or aluminous alloy. A material having high electrical conductivity will be preferred. The monopolar anode plate 6 cannot be made of graphite. Contact between a metal monopolar plate 6 and a graphite monopolar plate 7 is possible.

[0073] Parallel to the short sides 5 of each monopolar plate, two rows of openings 17 are provided in each monopolar plate 6, 7. The openings 17 of plate are, here, rectangular. The plate openings 17 have a closed contour. The rows of plate openings 17 6, 7 are distant from each other and adjacent to the short sides 5 respectively. The plate openings 17 6, 7 are through the thickness of each monopolar plate 6, 7. In the embodiment of [Fig.l], five plate openings 17 6, 7 are provided per row. Through said plate openings 17 6, 7, the water and the gases generated by the electrolysis circulate. Between the two rows of plate openings 17 6, 7, a flat and solid rectangular surface 18 is formed. Said rectangular surface 18 forms a sealed cover. Said rectangular surface 18 forms an electrical terminal of cell 1. The cavity 10 has a length and a width less than the length and the width of said rectangular surface 18. The plate openings 17 have a closed edge.

[0074] Parallel to the short sides 5 of the body 9 of the frame 8, two rows of openings 19 are provided in the body 9 of the frame 8. The openings 19 have an arch shape opposite the cavity 10 and a straight segment opposite the cavity 10. The rows of openings 19 are spaced apart from each other and adjacent to the short sides 5 respectively. The openings 19 are formed at a distance from the cavity 10. The openings 19 are formed at a distance from the short sides 5. The openings 19 pass through the thickness of the body. In the embodiment of [Fig.l], five openings 2 are provided per row. Through said openings 19, the water and the gases generated by the electrolysis circulate. The openings 19 have a closed edge. The openings 19 pass through.

[0075] Within a row of openings 19 of the body, at least one opening of the body 9 of the frame 8 is in communication with the anode compartment 12 by at least one channel 20. Here, said channel 20 is planar. The channel 20 has a dimension along the width of the frame 8 greater than its dimension along the length of the frame 8. The channel 20 has a dimension along the thickness of the frame 8 less than the thickness of the body. The channel 20 is open on one of the monopolar plates. The channel 20 is defined on three sides by the body. The channel 20 is open at its ends towards the cavity 10 and towards said opening of the body. The channels 20 are perpendicular to the communication openings 19.

[0076] Within a row of openings 19 of the body, at least one opening 19 of the body 9 of the frame 8 is in communication with the cathode compartment 13 by at least one channel 20. Here, said channel 20 is planar. The channel 20 has a dimension along the width of the frame 8 greater than its dimension along the length of the frame 8. The channel 20 has a dimension along the thickness of the frame 8 less than the thickness of the body. The channel 20 is open on one of the monopolar plates. The channel 20 is defined on three sides by the body. The channel 20 is open at its ends towards the cavity 10 and towards said opening of the body. The frame 8 has as many communication openings 19 than the monopolar plate. Each opening of the body 9 of the frame 8 is arranged opposite an opening of said monopolar plate. Each channel 20 intersects with an opening 19.

[0077] For each anode 12 or cathode 13 compartment, the communication openings 19 located on one side of the cavity 10 are supply openings 21. The communication openings 19 located on the other side of the cavity 10 are discharge openings 22.

[0078] The channels 20 are made in the frame 8. The channels 20 connect the communication openings 19 and the anode or cathode compartments. In order to optimize the water and gas flows, on a row of communication openings 19, the channels 20 open alternately into the anode and cathode compartments 12, 13. In the embodiment shown, the channels 20 to the cathode compartment 13 and the channels 20 to the anode compartment 12 have an identical shape.

[0079] The channels between the feed openings 21 and the anode compartments 12 are feed channels 37. The channels between the feed openings 21 and the cathode compartments 13 are feed channels 37. The channels between the discharge openings 22 and the anode compartments 12 are discharge channels 38. The channels between the discharge openings 22 and the cathode compartments 13 are discharge channels 38.

[0080] The openings 19 are in communication with the plate openings 17.

[0081] The openings 19 of the body are inscribed in the openings 17 of the plates. The edges of the openings 17 of the plate and the edges of the openings 19 of the body may comprise a portion tangent to the other, namely the portion located at the outlet of the channels 20. The remainder of the edge of the openings 17 of the plate is located at a distance from the remainder of the edge of the openings 19 of the body. The perimeter of each opening 19 of the body is less than the perimeter of the openings 17 of the plate.

[0082] Each opening 19 has a perimeter inscribed in the perimeter of the corresponding opening 17 of the first and second monopolar plates 6, 7.

[0083] In one embodiment, each monopolar plate 6, 7 comprises a single opening 17 per side. Each row of openings 19 is inside each of the openings 17.

[0084] In the embodiment shown, the openings 17 have a rectangular shape. The openings 17 have a surface area greater than the openings 19. The openings 19 are included in the openings 17.

[0085] The rectangular shape facilitates the production of 6, 7 monopolar plates and reduces the amount of titanium required to produce 6, 7 monopolar plates.

[0086] In an embodiment not shown, the monopolar plates 6, 7 have a polygonal shape. The monopolar plates 6, 7 are provided with at least two opposite openings 17. Each opening 17 is in communication with at least two openings 19 of the frame. In this embodiment, the frame 8 is also of polygonal shape.

[0087] Through the monopolar plates 6, 7, first holes 23 and second holes 24 are provided. The first holes 23 and the second holes 24 are through holes. The first holes 23 and the second holes 24 are alternated. The first holes 23 are smaller than the second holes 24. The first holes 23 and the second holes 24 are arranged along the long sides 4 and the short sides 5. The first holes 23 and the second holes 24 have centers defining a rectangle. The first holes 23 and the second holes 24 have centers at a constant distance from the long sides 4 and the short sides 5. A portion of the first holes 23 and the second holes 24 are arranged between the short sides 5 and the communication openings 19.

[0088] The first holes 23 and the second holes 24 are, here, circular. Each first hole 23 is, here, equidistant from the neighboring second holes 24. Each first hole 23 is, here, equidistant from the nearest first holes 23.

[0089] Each monopolar plate 6, 7 is fixed to the frame 8 by projections 25 forming rivets. The projections 25 are integral with the body. The projections 25 have a projection body 26 and a head. The head is wider than the projection body 26. The projection bodies 26 pass through the first holes 23. The heads protrude from the monopolar plate 6, 7. Here, the diameter of the projection bodies 26 is equal to the diameter of the first holes 23.

[0090] In another embodiment, the fixing of the monopolar plates 6, 7 are screwed onto the frame 8 by fixing elements. The fixing elements are made of insulating material or are electrically insulated in the case where said fixing elements are in electrical contact with the monopolar plates 6, 7. The fixing elements engaged in one of the monopolar plates 6, 7 and the frame 8, while being at a distance from the other of the plates 6, 7, may be made of conductive material, the frame 8 being made of insulating material. The fixing elements may comprise screws.

[0091] The monopolar plates 6, 7 can be mounted on slides made of insulating material.

[0092] Bonding of the monopolar plates 6, 7 on the frame 8 can be carried out.

[0093] The projections 25 have an annular surface in contact with the first surface 2 of the cell, formed by the first monopolar plate 6, or outer face of the first monopolar plate 6.

[0094] The sum of the thicknesses of the proton exchange membrane 11 and the porous transport layers 14 is greater than the distance between the first and second monopolar plates 6, 7. Thus, a compressive force of the membranes is provided by the first and second monopolar plates 6, 7. The compressive force has a direction normal to the main surface of the first and second monopolar plates 6, 7. The compressive force is oriented towards the inside of the cell 1. The first and second monopolar plates 6, 7 are held in place in said normal direction by the inner faces of the protruding heads 27 of the frame 8. The first and second monopolar plates 6, 7 are held in place in the plane of the main surface of the first and second monopolar plates 6, 7 by the protruding bodies 26 of the frame 8.

[0095] Thus, the components of the cell 1 are mounted tightly between the projection heads 27 of the frame 8. The frame 8 resists the internal pressure of the cells generated by the circulation of the water and the compression of the components. The riveting of the first and second monopolar plates 6, 7 can be done by hot plastic deformation of the projections 25 for example.

[0096] The protrusion heads protrude from the first and second monopolar plates 6, 7. Then, the cells 1 are stacked one after the other, the second monopolar plate 7 of a cell 1 is in contact with the first monopolar plate 6 of a neighboring cell 1. The first monopolar plate 6 of said cell 1 is in contact with the second monopolar plate 7 of another neighboring cell 1. The second holes 24 of the second monopolar plate 7 of said cell 1 serve as a housing for the protrusion heads 27 protruding from the first monopolar plate 6 of the neighboring cell 1. The second holes 24 of the first monopolar plate 6 of said cell 1 serve as a housing for the protrusion heads 27 protruding from the second monopolar plate 7 of the other neighboring cell 1. The electrical contact between a cell 1 and the two neighboring cells 1 is ensured.

[0097] The projections 25 of a cell 1 are offset relative to the projections 25 of a neighboring cell 1. For this purpose, the projections 25 of the first surface 2 of a cell 1 and the projections 25 of the second surface 3 of said cell 1 are offset. The first holes 23 of the first monopolar plate 6 and the first holes 23 of the second monopolar plate 7 are offset. The second holes 24 of the first monopolar plate 6 and the second holes 24 of the second monopolar plate 7 are offset. A stack of identical cells 1 can be produced.

[0098] The first and second monopolar plates 6, 7 have an inverted distribution of holes, see [Fig. 2]. The first and second monopolar plates 6, 7 are distinct. The first monopolar plate 6 is fixed on one side of the body 9 of the frame 8 while the second monopolar plate 7 is fixed on the opposite side of the body 9 of the frame 8.

[0099] In an embodiment not shown, the first and second plates 6, 7 monopolar are identical. First holes 23 are arranged along one diagonal while second holes 24 are arranged along the other diagonal. First and second holes 24 are arranged so as to have plates mounted on both sides of the frame 8 by turning one of the monopolar plates 6, 7 relative to the other. By construction, there is a keying device which prevents incorrect mounting. Alternatively, a hexagonal cell 1 is provided.

[0100] In another embodiment not shown, the cell 1 is circular in shape. The first and second monopolar plates 6, 7 are then identical.

[0101] Seals 28 are arranged on the periphery of each opening 19. Seals 48 are arranged around the rectangular cavity 10 of the frame 8 and at least one opening 19. The seals 28 and 48 are installed on each side of the frame 8. The seals 28 and 48 have closed contours.

[0102] The seals 28 have two opposite flat surfaces. The seals 28 are arranged inside the edge of the openings 17. The seals 28 are symmetrical by central symmetry. The seals 28 are housed in seal grooves formed in the body 9 of the frame 8, cf. Figures 2 and 3. One of the opposite flat surfaces of a seal 28 is in contact with a bottom of the groove and the other of the opposite flat surfaces projects out of the groove. The seals 28 project relative to the body 9 of the frame 8. The seals 28 project relative to the corresponding first and second monopolar plates 6, 7.

[0103] The seals 28 comprise a first part 39 and a second part 40, cf [Fig. 5]. The first part 39 is rectilinear. The first part 39 is housed in a groove formed in the body 9 of the frame 8 opposite the channel 20 relative to a transverse plane of the frame 8 in the thickness direction. The first part 39 has a rectangular section. The first part 39 is proximal to the anode compartment 12 and the second part 40 is distal to the anode compartment 12. The second part 40 has a rectangular section. The second part 40. Here, the second part 40 is rounded. In one embodiment, the section of the first part 39 is wider than the section of the second part 40.

[0104] In an embodiment not shown, the seal 28 fits the edge of one of the openings 17. Thus, the seal 28 protects the edge of the plate opening 17.

[0105] In one embodiment, the seal 28 is close to the edge of one of the openings 19. Indeed, to reduce pressure losses, it is advantageous to have seals 28 close to the edge of the openings 19 of the frame 8. This makes it possible to avoid having areas of water stagnation between the frame 8 and the monopolar plates 6, 7.

[0106] The grooves are formed in excess thicknesses of the frame 8 projecting relative to the body, from a flat top of the excess thicknesses. One of the excess thicknesses is located inside each opening 17 and is flush with one of the openings 19. Said excess thickness thickness is flush with an inner surface of one of the monopolar plates 6, 7 or forms a projection over a portion of the thickness of the monopolar plate 6, 7. The grooves are delimited by an inner rib and an outer rib. The inner ribs and the outer ribs form said flat top. The inner ribs and the outer ribs have a constant width. The grooves are of constant width. The grooves are of constant depth. The grooves form a closed contour.

[0107] The seals 28 are one per opening 19. The seals 28 are distributed in half on each side of the frame 8.

[0108] There are two seals 48, one on each side of the frame 8. One of the seals 48 seals the anode compartment 12 and the other of the seals 48 seals the cathode compartment 13. The seals 48 have a constant thickness. The seals 48 here have a rectangular section. The seals 48 comprise a first portion, at least one second portion and a pair of connecting ramps per second portion. The connecting ramps join the first portion and the second portion.

[0109] The first portion has two opposite flat surfaces. The second portions have two opposite flat surfaces. Each pair of connecting ramps has two opposite flat surfaces.

[0110] The first portion or main portion is arranged around the cavity 10. The first portion has a discontinuous rectangular general shape. The discontinuity of the rectangular general shape coincides with the channels 20. On the cathode side, the discontinuity of the rectangular general shape coincides with the channels 20 communicating with the cathode compartment. On the anode side, the discontinuity of the rectangular general shape coincides with the channels 20 communicating with the anode compartment.

[0111] The first portion is clamped between the frame body and one of the first and second plates 6, 7. The first portion is housed in seal grooves formed in the body 9 of the frame 8. One of the opposite flat surfaces of a seal 28 is in contact with a bottom of the groove and the other of the opposite flat surfaces is in contact with one of the first and second plates 6, 7. The seals 28 project relative to the body 9 of the frame 8 before mounting the first and second plates 6, 7.

[0112] The grooves are formed in the excess thicknesses of the frame projecting from the body, from a flat top of the excess thicknesses. The excess thicknesses are located around the cavity 10. The excess thicknesses are flush with the cavity 10. The excess thicknesses are arranged between the monopolar plates 6, 7. The excess thicknesses are arranged on one side and the other of the frame body. The grooves are delimited by an inner rib and an outer rib. The inner ribs and the outer ribs form the said flat top. The inner ribs and the outer ribs have a constant width. The grooves are of constant width. The grooves are of constant depth. The grooves form a discontinuous outline.

[0113] The second portions of the seals 48 are arranged inside the edge of the openings 17. The second portions of the seals 48 are symmetrical by central symmetry. The second portions of the seals 48 are housed in seal grooves formed in the body 9 of the frame 8, cf. Figures 2 and 3. One of the opposite flat surfaces of the second portions of the seals 48 is in contact with a bottom of the groove and the other of the opposite flat surfaces projects out of the groove. The second portions of the seals 48 here have a rectangular section. The second portions of the seals 48 project relative to the body 9 of the frame 8. The second portions of the seals 48 project relative to the corresponding first and second monopolar plates 6, 7.

[0114] The second portions of the seals 48 have a discontinuous outline. The discontinuity of the outline coincides with the channels 20 communicating with either the cathode or anode compartment. For the rest, the second portions of the seals 48 are identical to the seals 28.

[0115] In an embodiment not shown, the second portions of the seals 48 fit the edge of one of the openings 17 with the exception of the side facing the channels 20. Thus, the second portions of the seals 48 protect the edge of the plate opening 17.

[0116] In one embodiment, the second portions of the seals 48 are close to the edge of one of the openings 19. Indeed, to reduce pressure losses, it is advantageous to have second portions of the seals 48 close to the edge of the openings 19 of the frame 8. This makes it possible to avoid having areas of water stagnation between the frame 8 and the monopolar plates 6, 7.

[0117] The grooves are made in the excess thicknesses of the frame, such as the grooves of the joints 28. The grooves and the excess thicknesses are interrupted at the right of the channel 20. Here, the grooves and the excess thicknesses have a general semi-circular shape.

[0118] The second portions of the two seals 48 number one per opening 19. The second portions of the two seals 48 are distributed in half on each side of the frame 8. The second portions of the two seals 48 are alternated with the seals 28. Opposite each second portion of seal 48 is one of the seals 28. In a plane, between two seals 28 is one of the second portions of seal 48. In said plane, between two second portions of seal 48 is one of the seals 28.

[0119] The second portions of the two seals 48 are located inside the openings of the monopolar plates 6, 7 and outside the edges of the openings 19.

[0120] In the plate openings 17, the seals 28 and the second portions of the seals 48 on the anode compartment side extend beyond the first surface 2 of the cell and to the frame 8. The seals 28 and the second portions of the seals 48 on the cathode compartment side extend beyond the second surface 3 of the cell and to the frame 8.

[0121] The pairs of connecting ramps comprise two joint segments. The pairs of connecting ramps connect the first portion to the second portions. The connecting ramps are oriented longitudinally. The connecting ramps are, in projection in the plane of the second portions of the joints 48, tangent to the second portions of the joints 48. The connecting ramps are, in projection in the plane of the first portion of the joints 48, perpendicular to the first portion of the joints 48 which extends transversely in the vicinity of said connecting ramps. Starting from the first portion of the joints 48, the connecting ramps move away from the frame body, in the direction of the thickness of the cell. The connecting ramps have a constant slope.

[0122] The anode and cathode compartments are sealed. The communications between the anode compartment 12 and the exterior of the cell 1 on the one hand, and the cathode compartment 13 and the exterior of the cell 1 on the other hand, are formed by the channels 20. The risk of introduction of impurities and dust is reduced. The seals 28 make it possible to compensate for the cumulative assembly tolerances. The thickness of the body 9 of the frame 8 is less than or equal to the distance between the monopolar plates 6, 7. The seals 28 are mounted between the frame 8 and the monopolar plates 6, 7. During assembly, the seals 28 are compressed. The compression ratio of the seals varies according to the cumulative assembly tolerances within a range of compression ratios of said seal.

[0123] In an embodiment illustrated in [Fig.9], the joints 28 and the joint 48 are made in one piece in a joint 58. Said joint 58 comprises the union of the joints 28 and the joint 48 and an additional joint portion between each first portion 39 of the joints 28 and the second portion of the joint 48. The additional joint portion is oriented along the width of the frame 8. The additional joint portions connect the joints 28 and the joint 48.

[0124] On the anode side, illustrated in [Fig. 11], the openings 17 comprise openings 171 belonging to cathode supply lines 30, openings 172 belonging to anode supply lines 30, openings 173 belonging to cathode discharge lines 31, and openings 174 belonging to anode discharge lines 31.

[0125] The openings 171 and 173 of the plate 6 arranged opposite the joints 28 have a width greater than the openings 172 and 174 arranged opposite the joint 48. Thus, the joints 28 are entirely contained inside the openings 171 and 173. The difference in width between the openings 171 and 173 and the openings 172 and 174 is at least equal to the width of the first part 39 of the joint 28, see [Fig. 12],

[0126] Once mounted, the first parts 39 of the joints 28 come into contact with the plate 7 of the neighboring cell.

[0127] When assembling two cells, the second portions of one of the seals 48 of one of the cells come into contact with the second parts 40 of the seals 28 of the other of the cells and the second portions of one of the seals 48 of the other of the cells come into contact with the second parts 40 of the seals 28 of said one of the cells. The first parts 39 of the seals 28 of one of the cells come into contact with the plate 7 of the other of the cells and the first parts 39 of the seals 28 of the other of the cells come into contact with the monopolar plate 7 of said one of the cells as illustrated in [Fig.10].

[0128] Since the seals 28 and the second portions of the seals 48 protrude from the monopolar plates 6, 7, the seals 28 and the second portions of the seals 48 are compressed when two cells are tightened, thus contributing to the sealing of the openings 19.

[0129] A membrane seal 29 is arranged in a groove on the positioning step 15 of the proton membrane 11. The groove of the seal 29 forms a continuous contour. The seal 29 has a constant thickness. The seal 29 here has a rectangular section. The membrane seal 29 provides sealing between the anode compartment 12 and the cathode compartment 13. The membrane seal 29 is continuous.

[0130] A seal 68 is arranged on the periphery of the cell. The seal 68 has two opposite flat surfaces. The seal 68 is housed in a seal groove formed in an excess thickness of the body 9 of the frame 8, see Figures 2 and 3. One of the opposite flat surfaces of a seal 68 is in contact with a bottom of the groove and the other of the opposite flat surfaces projects out of the groove. The seals 68 here have a rectangular section. The seal 68 projects relative to the body 9 of the frame 8.

[0131] A water electrolysis device comprises a stack 35 of electrolysis cells 1, two power supply plates 33, clamping flanges 32, clamping rods 36 and insulating plates 34. The electrolysis cells 1 are stacked in the same direction, for example cathodes oriented in one direction of the stacking direction and anodes oriented in the opposite direction of the stacking direction.

[0132] In another embodiment, the insulating plates 34 are replaced by an insulating coating on the outer faces of the electrical power supply plates 33, the outer faces being opposite the faces in contact with the cells 1.

[0133] The cells 1 are stacked with a first monopolar plate 6 of a cell 1 of rank n in contact with the second monopolar plate 7 of a cell 1 of rank n+1 and the second monopolar plate 7 of the cell 1 of rank n in contact with the first monopolar plate 6 of a cell 1 of rank n-1. At the ends of the stack, the first monopolar plate 6 of cell 1 of rank 1 and the second monopolar plate 7 of cell 1 of maximum rank.

[0134] In a single 35 stack, all 1 cells are identical. The order of the 1 cells in a 35 stack is indifferent. Thus, a defective cell can be easily replaced.

[0135] The direction of assembly of the cells 1 with each other is imposed by the arrangement of the projections 25 of the frame 8 and of the second holes 24 of the first and second monopolar plates 6, 7. The assembled cells 1 are held tight by the clamping flanges 32. The first and second monopolar plates 6, 7 of the cells 1 are in contact.

[0136] The supply openings 21 of each cell 1 are opposite each other, forming the supply pipes 30. The discharge openings 22 of each cell 1 are opposite each other, forming the discharge pipes 31. Hydraulic connections are provided with the supply pipes 30 and the discharge pipes 31.

[0137] The supply lines 30 and the discharge lines 31 are produced by stacking the frames 8 and the seals 18 of each cell. Thus, each supply line 30 and each discharge line 31 has a wall in the material of the seals 18 and in the material of the frame 8. The edge of the plate openings 17 being distant from the edge of the openings 19 of the body, a wide-tolerance positioning of the monopolar plates 6, 7 is sufficient.

[0138] A stack 35 of cells 1 is shown in [Fig.8]. Here, a stack of three cells 1 is shown for understanding. In practice, the stacks comprise several hundred cells, for example 400. The cells 1 are stacked between the two power supply plates 33. Holes are provided in the power supply plates to communicate fluidically with the supply lines 30 and the discharge lines 31. The power supply plates 33 are connected to a positive terminal and a negative terminal of a power supply. The power supply plate 33 connected to the positive terminal is in contact with the first anode compartment 12 of the stack 35 and the power supply plate 33 connected to the negative terminal is in contact with the last cathode compartment 13 of the stack 35. The stack 35 of cells 1 is held tight by the clamping flanges 32. The clamping flanges 32 are held by the clamping rods 36.Between the clamping flanges 32 and the feed plates 33, the insulating plates 34 are arranged. The insulating plates 34 electrically isolate the stack 35 from the external environment.

[0139] In use, water enters the anode compartments 12 and the cathode compartments 13 of all the cells 1 of the device through the water supply lines 30. The water then passes through the porous transport layers 14 to come into contact proton exchange membranes. Water is discharged through the discharge pipes, opposite the supply pipes 30. A power supply is connected to both ends of the water electrolysis device. The positive terminal is connected to the anode of cell 1 of rank 1 while the negative terminal is connected to the cathode of cell 1 of maximum rank. Current flows from the anode of cell 1 of rank 1 to the cathode of cell 1 of maximum rank through each electrolysis cell 1, creating an electrolysis reaction in each cell 1.

[0140] In the cell, the water comes into contact with the main faces of the monopolar plates 6, 7 and the supply and discharge pipes.

[0141] During electrolysis, water molecules separate into ions. The H+ ions pass through the proton exchange membrane 11. The ions form oxygen at the anode and hydrogen at the cathode. The hydrogen is discharged through the discharge lines 31 from the cathode compartments, while the oxygen is discharged through the discharge lines 31 from the anode compartments. A mixture of water and oxygen circulates in the discharge lines 31 from the anode compartments. Hydrogen is discharged from the cathode compartment 13 through the discharge lines 31 from the cathode compartments. A mixture of water and hydrogen circulates in the discharge openings 22 of the cathode compartment 13. The produced oxygen and hydrogen are separated from the water and sent to the outlet of the water electrolysis device.

[0142] Maintenance of such a device is facilitated. When a cell 1 is defective, it is removed without having to dismantle the entire stack of cells 1. A replacement cell 1 can be installed in its place. The stack can also be restored to working order without replacing said cell 1. Such maintenance is possible at the hydrogen production site and a return to the factory is avoided.

[0143] Such a device also facilitates the initial assembly of an electrolysis stack. Each cell 1 is tested individually before being stacked. Thus, a cell 1 with a manufacturing defect is immediately identified. This avoids having to dismantle an entire stack in the event that a cell 1 is defective.

Claims

Claims

1. A water electrolysis cell with a PEM polymer electrolytic membrane for hydrogen production, comprising a proton exchange membrane (11), an anode compartment (12) in contact with the membrane, a cathode compartment (13) in contact with the proton exchange membrane (11), and a first conductive plate (6) in contact with the anode compartment (12) and a second conductive plate (7) in contact with the cathode compartment (13), characterized in that the proton exchange membrane (11), the anode compartment (12) and the cathode compartment (13) are held clamped between the first plate (6) and the second plate (7) conductive, said first and second conductive plates (6, 7) being monopolar, said cell (1) comprising a frame (8) device fixed to the first and second conductive plates (6, 7) and holding said first and second conductive plates (6, 7) tight, the frame (8) comprising at least two openings opening into the anode compartment (12) and into two respective channels (20) and at least two openings opening into the cathode compartment (13) and into two other respective channels (20), the channels (20) being parallel.

2. A water electrolysis cell according to claim 1, wherein said first and second conductive plates (6, 7) have parallel surfaces, opposite each other and opposite the frame (8), the frame (8) being made of an insulating material, wherein the first and second conductive plates (6, 7) are fixed to the frame (8) and wherein at least four communication openings (19) are provided in each of said first and second conductive plates (6, 7) in communication with said respective channels (20).

3. Water electrolysis cell according to one of the preceding claims, in which the first conductive plate (6) is made of a material chosen from titanium, aluminum, coated mild steel, coated copper, coated stainless steel, zirconium, niobium, tantalum, tungsten or one of their alloys and in which the second conductive plate (7) is made of a material chosen from titanium, aluminum, coated mild steel, coated copper, coated stainless steel, zirconium, niobium, tantalum, tungsten or one of their alloys, or a carbon material such as graphite, the coating of the materials coated with chromium carbide or titanium carbide.

4. Water electrolysis cell according to one of the preceding claims, wherein said channels (20) are perpendicular to said communication openings (19).

5. Water electrolysis cell according to one of the preceding claims, in which a plurality of first fixing holes (23) are provided in said first and second conductive plates (6, 7) facing the frame (8) and a plurality of projections (25) integral with the frame (8) comprising a body (26) passing through said first fixing holes (23) of said first and second conductive plates (6, 7) and a head (27) of diameter greater than the diameter of the body (26), thus fixing said first and second conductive plates (6, 7) to the frame (8).

6. Water electrolysis cell according to claim 5, in which a plurality of second holes (24) are provided in said first and second conductive plates (6, 7) facing the frame (8), said second holes (24) having a diameter greater than the diameter of said heads, said second holes (24) being alternated with the first fixing holes (23).

7. Water electrolysis cell according to one of the preceding claims, in which the frame (8) has a step (15) for positioning the proton exchange membrane (11), the anode compartment (12) comprises two porous transport layers (14) of different porosities, the cathode compartment (13) comprises two porous transport layers (14) of different porosities.

8. Water electrolysis cell according to one of the preceding claims, in which said first and second conductive plates (6, 7) have a seal with the frame (8).

9. Water electrolysis installation for the production of hydrogen comprising a stack of a plurality of cells (1) according to one of the preceding claims, having aligned channels (20), the first conductive plate (6) of one of said cells (1) being in contact with the second conductive plate (7) of another of said cells (1).

10. A method of maintaining a water electrolysis device, comprising loosening a stack of a plurality of cells (1) according to one of claims 1 to 8, removing at least one electrolysis cell (1) from said stack of a plurality of cells (1), tightening of said stacking.

11. A method according to claim 10, comprising before tightening said stack, inserting at least one electrolysis cell (1) replacing the at least one removed electrolysis cell (1).

12. A method of manufacturing a water electrolysis device, comprising assembling an electrolysis cell (1) according to one of claims 1 to 8, testing said electrolysis cell (1), and, if the test is satisfactory, mounting said electrolysis cell (1) in a stack of a plurality of cells (1).

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