Electrolysis cell

Abstract

The invention relates to a water electrolysis cell having a polymer electrolyte membrane PEM for producing hydrogen, the cell comprising a proton exchange membrane (11), a cathode compartment (7), an anode compartment (9), a first conductive plate (30), a second conductive plate (7), and a frame (31) supporting the proton exchange membrane (11). The cathode compartment (7) is delimited by the proton exchange membrane (11) and the first conductive plate (30). The cathode compartment (7) is laterally delimited by the frame (31). The frame (31) is provided with at least two first openings (43) that each communicate with the cathode compartment (7) via an anode channel (47), and at least two second openings (45) that each communicate with the anode compartment (9) via a cathode channel (48). The first and second conductive plates (30) are provided with first and second plate openings (37, 39). The openings (37, 39) in the conductive plate (30) are each delimited by a plate edge. The frame (31) comprises a rigid core (49) covered at least in part by a flexible insulating layer (51). The rigid core (49) has a constant thickness. The flexible insulating layer (51) covers the edges of the openings (43, 45) in the frame (31). The flexible insulating layer (51) has at least first surfaces and second surfaces. The first surfaces and the second surfaces are spaced apart from the rigid core by a first thickness and a second thickness, respectively, the first thickness being greater than the second thickness.

Description

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] For the decentralized and environmentally friendly industrial production of hydrogen, water electrolysis is preferred to reforming. Current electrolyzer devices comprise a plurality of electrochemical cells, fed with water, each containing a pair of electrodes. For reasons of cost and space, among others, the cells are generally flat and grouped in one or more stacks, so that any two stacked cells share a common electrode.

[0004] To reduce costs, particularly those related to the manufacturing and operation of the stacks, the general aim is to maximize the number of cells per stack. By applying a direct current between the anode and cathode of each cell, using a generator with an adjustable output voltage, the electrolysis of water is triggered. This produces hydrogen (H2) and oxygen (O2).

[0005] In a stack of electrolysis cells, water circulates through pipes made by layering numerous components. The large number of interfaces between components made of different materials increases the risk of leakage.

[0006] Electrolysis cells are described in FR3062856. The cells comprise conductive plates separated by a spacer. These cells are assembled to form an electrolysis stack. Openings in the various cell components form water supply and discharge channels. Each cell includes a proton exchange membrane, two separate compartments, an anode compartment, and a cathode compartment. The proton exchange membrane is supported by an electrically insulating frame. The anode and cathode compartments are delimited by the proton exchange membrane, the frame, and a bipolar plate. The frame has a complex shape with numerous functional surfaces and a plurality of seals to ensure the anode and cathode compartments are watertight.Furthermore, each frame must withstand high pressures without deforming, in order to allow good fluid flow and prevent leaks.

[0007] However, each electrolysis plant comprises as many frames as cells, generally several hundred. The manufacturing process for each frame is complex, lengthy, and expensive.

[0008] The Applicant sought to design a frame that was simple to manufacture, limiting the machining steps, the number of parts composing the frame, and reducing manufacturing time. The Applicant sought to limit the number of manufacturing steps, particularly manual ones, such as the individual installation of seals on the frame surfaces.

[0009] The invention improves the situation.

[0010] The invention provides a PEM polymer electrolytic membrane water electrolysis cell for hydrogen production. The water electrolysis cell comprises a proton exchange membrane, a cathode compartment in contact with the proton exchange membrane, an anode compartment in contact with the proton exchange membrane, a first conductive plate in contact with the cathode compartment, forming one end of the cell along its thickness, and a second conductive plate in contact with the cathode compartment, forming the other end of the cell along its thickness. The first conductive plate may be shared with a front cell. The second conductive plate may be shared with a rear cell. The water electrolysis cell includes a frame supporting the proton exchange membrane.The cathode compartment is delimited along two parallel planes by the proton exchange membrane and the first conductive plate. The cathode compartment is laterally delimited by the frame. The anode compartment is delimited along two parallel planes by the proton exchange membrane and the second conductive plate. The anode compartment is laterally delimited by the frame. The frame is provided with at least two first openings, each communicating with the cathode compartment via an anodic channel, and at least two second openings, each communicating with the anode compartment via a cathodic channel. The cathodic and anodic channels are arranged within the frame. Each of said cathodic and anodic channels intersects with one of said first and second openings. The first and second conductive plates are provided with first and second plate openings, respectively.The first and second plate openings are through-holes and communicate with at least one of the first and second openings in the frame. Each of the first and second openings in the frame is delimited by an edge of the frame. The openings in the conductive plate are also delimited by an edge of the plate. The frame comprises a rigid core covered at least partially by a flexible insulating layer. The rigid core has a constant thickness. The flexible insulating layer covers the edges of the frame openings. The flexible insulating layer has at least two first and two surfaces. These first and second surfaces are spaced from the rigid core by a first and second thickness, respectively, with the first thickness being greater than the second thickness. The frame is simple to manufacture and very robust.

[0011] In one embodiment, the rigid core consists of a flat sheet metal plate. Productivity is high.

[0012] In one embodiment, the rigid core comprises two opposing parallel faces, forming two sides. The frame includes at least first and second surfaces on one side and at least third and fourth surfaces on the other side of the rigid core. The third and fourth surfaces are distanced from the rigid core by a third and fourth thickness, respectively. The sealing is of a high standard.

[0013] In one embodiment, the openings in the conductive plate have a shape matching the openings in the frame and are mounted opposite each other. Openings are provided in the rigid core. The openings in the rigid core have a shape matching the openings in the frame. Pressure losses are low.

[0014] In one embodiment, the flexible insulating layer ensures the sealing of the cathode and anode compartments. Reliability is high.

[0015] In one embodiment, the frame includes a step supporting the membrane. The flexible insulating layer forms a membrane joint positioned on the step. The structure is robust.

[0016] In one embodiment, the flexible insulating layer comprises a cathode seal that fluidly insulates the cathode compartment, an anode seal that fluidly insulates the anode compartment, and opening seals that insulate the second openings of the frame on the cathode side and the first openings of the frame on the anode side. The sealing is of a high standard.

[0017] In one embodiment, the flexible insulating layer includes an additional anode seal that fluidly insulates the anode compartment, the anode seal and the additional anode seal being positioned opposite the cathode seal and the membrane seal relative to the frame. The sealing is of a high standard.

[0018] In one embodiment, the channels of the frame are each partially formed by the flexible insulating layer. Corrosion is reduced.

[0019] In one embodiment, the first and second conductive plates rest on the flexible insulating layer, respectively on each side of the frame. The compressive forces are distributed.

[0020] In one embodiment, the frame comprises a portion of flexible insulating layer disposed around one perimeter of the cathode compartment at a distance from the cathode compartment, and a portion of flexible insulating layer disposed around one perimeter of the anode compartment at a distance from the anode compartment. The flexible insulating layer includes walls connecting these portions of flexible insulating layer to the cathode seal and the anode seal, respectively. The walls form fluid conduits to the outside of the cell. The construction is robust.

[0021] The invention also relates to a water electrolysis plant for the production of hydrogen comprising a stack of a plurality of cells, numbered from 1 to N, having aligned apertures. The first conductive plate of one of said cells, of rank k between 2 and N-1, is common with the cell of rank k-1. The second conductive plate of one of said cells, of rank k between 2 and N-1, is common with the cell of rank k+1. Assembly is quick.

[0022] Other features and advantages of the invention will become apparent from the examination of the detailed description below, and the accompanying drawings, in which: a schematic illustration of a water electrolysis device is shown; a schematic perspective cross-sectional view of a cell of the water electrolysis device according to one aspect of the invention is shown; a schematic exploded view of a cell according to one aspect of the invention is shown; a schematic top view of the frame of a cell according to one aspect of the invention is shown; a schematic bottom view of the frame of a cell according to one aspect of the invention is shown; a schematic perspective cross-sectional view of the frame of a cell of the water electrolysis device according to one aspect of the invention is shown; a schematic perspective cross-sectional view of the frame of a cell of the water electrolysis device according to one aspect of the invention is shown;illustrates schematically the rigid core of the frame of a cell according to a top view aspect of the invention; illustrates schematically the rigid core of the frame of a cell according to a bottom view aspect of the invention.

[0023] The attached drawings may not only serve to complete the invention, but also contribute to its definition, if necessary.

[0024] The figures represent a water electrolysis cell according to one aspect of the invention.

[0025] WO2019228616 gives an example of stacking electrolysis cells clamped together by bolts.

[0026] WO2014060198 gives an example of a mixed stack of fuel cell and supercapacitors.

[0027] In the following, the terms "anode," "cathode," and their derivatives are used as shown in the figures. However, the proposed electrolyzer structures can operate in a reversed manner compared to what is depicted. For example, by reversing the polarization and swapping the fluid inlet and outlet connections, the anodic compartment can become the cathodic compartment, and vice versa. Nevertheless, the materials and dimensions are optimized for the anode on the one hand, and for the cathode on the other.

[0028] Electrolysis cells comprise a plurality of bipolar plates (see WO2019228616). The function of these bipolar plates is to collect current, distribute it, and separate gases at the anode and cathode. The bipolar plates are made of a material with high electrical conductivity and lower gas permeability than the proton exchange membrane. The bipolar plates also possess good chemical inertness. They are generally made of titanium. One side of the plate acts as the anode for the first cell, and the other side acts as the cathode for the adjacent cell.

[0029] The gases are produced by the electrolysis of water, namely dioxygen and dihydrogen.

[0030] The electrochemical aspect of a water electrolysis stack is illustrated on patent FR3062856.

[0031] Bipolar plates are generally made of titanium. The electrochemical properties of titanium are particularly well-suited for performing water electrolysis.

[0032] To be able to carry out water electrolysis, in the absence of bipolar titanium plates, it is possible to use plates made of another electrically conductive material provided that their main faces are coated with a conductive and water-resistant coating, in particular CrC or TiC.

[0033] A water electrolysis device 1, illustrated in Figure 1, comprises a stack 3 of electrolysis cells 5, two power supply plates 17, clamping flanges 19, clamping rods 21, and insulating plates 23. Each cell 5 includes a proton exchange membrane 11, cf, or PEM membrane. Each electrolysis cell 5 comprises a cathode compartment 7 and an anode compartment 9 separated by the proton exchange membrane 11.

[0034] The 5 electrolysis cells are stacked in the same direction, e.g. cathodes oriented in one direction of the stacking direction and anodes oriented in the opposite direction of the stacking direction.

[0035] In another embodiment, the insulating plates 23 are replaced by an insulating coating on the outer faces of the power supply plates 17, said outer faces being opposite the faces in contact with the cells 5.

[0036] In practice, stacks of 3 include several hundred cells 5, for example 400.

[0037] The stack 3 includes water supply lines 13 and water, oxygen, and hydrogen discharge lines 15. The cells 5 are stacked between two power supply plates 17. Openings are provided in the power supply plates 17 for fluid communication with the supply lines 13 and the discharge lines 15. The power supply plates 17 are connected to a positive and a negative terminal of a power supply. The power supply plate 17 connected to the positive terminal is in contact with the first cathode compartment 7 of the stack 3, and the power supply plate 17 connected to the negative terminal is in contact with the last anode compartment 9 of the stack 3. The stack 3 of cells 5 is held tightly together by clamping flanges 19. The clamping flanges 19 are held in place by clamping rods 21.Insulating plates 23 are arranged between the clamping flanges 19 and the power supply plates 17. The insulating plates 23 electrically isolate the stack 3 from the external environment.

[0038] During operation, water enters the cathode compartments 7 and the anode compartments 9 of all the cells 5 of the device through the water supply lines 13. The water comes into contact with the proton exchange membranes 11. The water is discharged through the discharge lines 15, opposite the supply lines 13. A power supply is connected to both ends of the water electrolysis device 1. The positive terminal is connected to the anode of the first-rank cell 5, while the negative terminal is connected to the cathode of the highest-rank cell 5. Current flows from the anode of the first-rank cell 5 to the cathode of the highest-rank cell 5, passing through each electrolysis cell 5 and initiating an electrolysis reaction in each cell 5.

[0039] 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 cathode compartment drain lines 15, while the oxygen is discharged through the anode compartment drain lines 15. A mixture of water and oxygen circulates in the anode compartment drain lines 15. The hydrogen is discharged from the anode compartment 9 through the cathode compartment drain lines 15. A mixture of water and hydrogen circulates in the drain lines 15. The oxygen and hydrogen produced are separated from the water and sent to the outlet of the water electrolysis unit.

[0040] The water electrolysis cell 5 is rectangular in shape, with two long sides, two short sides, a first surface 27, and a second surface 29. The first surface 27 and the second surface 29 are parallel and opposite. The first surface 27 and the second surface 29 are separated by a thickness of the electrolysis cell 5. The electrolysis cell 5 has a small thickness from the first surface 2 to the second surface 3, at least a factor of ten, preferably a factor of one hundred, compared to the dimension of the short sides.

[0041] Each cell 5 comprises a first and a second bipolar plate 30, a frame 31, and a proton exchange membrane 11 (see Figures 2 and 3). The bipolar plate 30 is electrically conductive. The first bipolar plate 30 of a cell 5 forms one end of the cell 5 along its thickness. The second bipolar plate 30 of cell 5 forms the second end of cell 5 along its thickness. The second bipolar plate 30 may be shared with a subsequent cell. In an electrolysis device 1, the cells 5 are numbered from 1 to N. The first bipolar plate 30 of a cell of rank k between 2 and N-1 is shared with the cell of rank k-1. The second bipolar plate of a cell of rank k between 2 and N-1 is shared with the cell of rank k+1.The first bipolar plate 30 of the rank 1 cell and the second bipolar plate of the rank N cell are identical to the others and functionally monopolar.

[0042] Each bipolar plate 30 comprises a first face 20 and a second face 22 opposite the first face 20. The bipolar plates 30 here have a rectangular outline. The bipolar plates 30 have two opposing short sides 24 and two long sides 26. The bipolar plates 30 have a thin profile. Once the stack 3 is assembled, each first face 20 is in contact with one of the anode compartments 9 and each second face 22 is in contact with one of the cathode compartments 7.

[0043] Parallel to the short sides 24 of each bipolar plate 30, two rows of openings are provided in each bipolar plate 30. Each row of openings comprises at least one first opening 37 and at least one second opening 39. Here, each row of openings comprises a pair of first openings 37 and a pair of second openings 39. The first openings 37 and the second openings 39 may have different areas. Here, the first openings 37 have a smaller area than the second openings 39. Alternatively, the first openings 37 have an area substantially equal to that of the second openings 39.

[0044] Here, the first openings 37 are arranged at both ends of each row of openings. The second openings 39 are arranged between the first openings 37. Alternatively, the first openings 37 and the second openings 39 are arranged alternately.

[0045] The first openings 37 and the second openings 39 are rectangular with two rounded corners, for example, semicircular or tunnel-shaped. The first openings 37 and the second openings 39 have a closed contour. The rows of openings are spaced apart and close to their short sides 24, respectively. The first openings 37 and the second openings 39 pass through the thickness of each bipolar plate 30. Water and gases generated by electrolysis flow through these first openings 37 and the second openings 39. A flat, solid rectangular surface 42 is formed between the two rows of openings. This rectangular surface 42 forms a sealed cover. This rectangular surface 42 forms an electrical terminal for cell 5. The first openings 37 and the second openings 39 have a closed contour.

[0046] The bipolar plates 30 can be made from a conductive material chosen from titanium, aluminum, coated mild steel, coated copper, coated stainless steel, zirconium, niobium, tantalum, tungsten or one of their alloys.

[0047] The coating may consist of CrC or TiC, or a mixture of both. The coating protects surfaces in contact with fluids. The CrC and / or TiC coating improves resistance.

[0048] Thus, the use of a CrC and / or TiC coating reduces the use of titanium. However, in addition to its high cost, manufacturing titanium parts is complex.

[0049] The frame 31 here has the same length and width as the bipolar plate 30. The frame 31 has a rectangular shape with two long sides, two short sides, a first face 28 and a second face 38 opposite the first face 28. When the stack 3 is assembled, the first face 28 of the frame 31 is in contact with the second face 22 of the bipolar plate 30. The second face 38 of the frame 31 is in contact with the first face 20 of another of the bipolar plates 30.

[0050] As illustrated in Figures 4 and 5, the frame 31 has a frame-like shape with a cavity 18 extending through the first face 28 to the second face 38. The cavity 18 is rectangular and centrally located. The frame 31 has a thickness greater than or equal to the distance between the bipolar plates 30 of one of the cells 5.

[0051] Alternatively, the dimensions of the bipolar plates 30 may differ from those of the frame 31.

[0052] Parallel to the short sides of the frame 31, two rows of openings are provided in the frame 31. Each row of openings comprises at least one first opening 43 of the frame 31 and at least one second opening 45 of the frame 31. Here, each row of openings comprises a pair of first openings 43 and a pair of second openings 45. Here, the first openings 43 are arranged at both ends of each row of openings. The second openings 45 are arranged between the first openings 43. Alternatively, the first openings 43 and the second openings 45 are arranged alternately. The openings 43 and the openings 45 are through openings from the first face 28 to the second face 38.

[0053] The first openings 43 of the frame 31 have a correspondence in shape with the first openings 37 of the bipolar plate 30. The second openings 45 of the frame 31 have a correspondence in shape with the second openings 39 of the bipolar plate 30.

[0054] Each first opening 43 of the frame 31 is arranged opposite a first opening 37 of the bipolar plate 30. Each second opening 45 of the frame 31 is arranged opposite a second opening 39 of the bipolar plate 30. The first openings 43 and the second openings 45 of the frame 31 are fluidly connected respectively to the first openings 37 and the second openings 39 of the bipolar plate 30.

[0055] The first openings 43 and the second openings 45 of the frame 31 have an arched shape opposite the cavity 18 and a straight segment opposite the cavity 18. The rows of openings in the frame 31 are spaced apart and close to the short sides of the frame 31, respectively. The first openings 43 and the second openings 45 of the frame 31 are formed at a distance from the cavity 18. The first openings 43 and the second openings 45 of the frame 31 are formed at a distance from the short sides of the frame 31. The first openings 43 and the second openings 45 of the frame 31 are through the thickness of the frame 31. Water and gases generated by electrolysis circulate through these first openings 43 and the second openings 45 of the frame 31. The first openings 43 and the second openings 45 of the frame 31 have a closed edge. The first openings 43 and the second openings 45 of the frame 31 are through openings.

[0056] At least one first opening 43 of the frame 31 communicates with the cathode compartment 7 via at least one cathode channel 47. Here, said cathode channel 47 is planar. The cathode channel 47 has a dimension along the width of the frame 31 greater than its dimension along the length of the frame 31. The cathode channel 47 has a dimension along the thickness of the frame 31 less than the thickness of the frame 31. The cathode channel 47 opens onto the bipolar plate 30 in contact with the frame 31. The cathode channel 47 is defined on three sides by the frame 31. The cathode channel 47 opens at its extremities towards the cavity 18 and towards said first opening 43 of the frame 31. The cathode channels 47 are perpendicular to the first communication openings 43. Each cathode channel 47 intersects with a first opening 43 of the frame 31.

[0057] At least one second opening 45 of the frame 31 communicates with the anode compartment 9 via at least one anode channel 48. Here, said anode channel 48 is planar. The anode channel 48 has a dimension along the width of the frame 31 greater than its dimension along the length of the frame 31. The anode channel 48 has a dimension along the thickness of the frame 31 less than the thickness of the frame 31. The anode channel 48 opens onto one of the monopolar plates. The anode channel 48 is defined on three sides by the body. The anode channel 48 opens at its extremities towards the cavity 18 and towards said second opening 45 of the frame 31. The anode channels 48 are perpendicular to the second openings 45 of the frame 31. Each anode channel 48 intersects a second opening 45 of the frame 31.

[0058] For each cathode compartment 7, the first openings 43 located on one side of the cavity 18 are supply openings. The first openings 43 located on the other side of the cavity 18 are drain openings.

[0059] For each anode compartment 9, the second openings 45 located on one side of the cavity 18 are supply openings. The second openings 45 located on the other side of the cavity 18 are drain openings.

[0060] The cathode or anodic channels 47, 48 are made in the frame 31. The cathode or anodic channels 47, 48 connect the openings and the cathode 7 or anode 9 compartments. In order to optimize the flow of water and gas, on a row of communication openings, the anodic or cathodic channels 47, 48 open alternately into the cathode 7 and anode 9 compartments. In the embodiment shown, the cathode or anodic channels 47, 48 to the anode 9 compartment and the cathode or anodic channels 47, 48 to the cathode 7 compartment have a similar shape.

[0061] The anodic or cathodic channels 47, 48 located between the feed openings and the cathode compartments 7 are feed channels. The cathodic or anodic channels 47, 48 located between the feed openings and the anode compartments 9 are feed channels. The cathodic or anodic channels 47, 48 located between the drain openings and the anode compartments 9 are drain channels. The cathodic or anodic channels 47, 48 located between the drain openings and the anode compartments 9 are drain channels.

[0062] The first and second openings 43, 45 of the frame 31 are inscribed within the first and second openings 37, 39 of the bipolar plates 30. The edges of the first and second openings 37, 39 of the bipolar plates 30 and the edges of the first and second openings 43, 45 of the frame 31 may include a portion tangent to the other, namely the portion located at the outlet of the cathode or anodic channels 47, 48. The remainder of the edge of the first and second openings 37, 39 of the bipolar plates 30 may be located at a distance from the remainder of the edge of the first and second openings 43, 45 of the frame 31. The perimeter of each of the first and second openings 43, 45 of the frame 31 is smaller than the perimeter of the first and second openings 37, 39 of the bipolar plates 30.

[0063] Each opening in the frame 31 has a perimeter inscribed within the perimeter of the opening of the corresponding bipolar plate 30.

[0064] The frame 31 comprises a rigid core 49 and a flexible insulating layer 51 covering at least part of the rigid core 49. The rigid core 49 may have a rectangular shape with two long sides, two short sides, a first face 53 and a second face 55, opposite the first face 53.

[0065] As illustrated in 9, the rigid core 49 includes an open cavity 181 having a shape analogous to the cavity 18 of the frame 31. The cavity 181 is provided from the first face 53 to the second face 55. The cavity 181 of the rigid core 49 has inner edges along short sides and long sides. The long sides are greater than those of cavity 18 of frame 31. Cavity 18 of frame 31 is inscribed and centered in cavity 181 of rigid core 49. Rigid core 49 includes first openings 57 and second openings 59 analogous to first openings 43 and second openings 45 of frame 31. The first openings 57 and second openings 59 of rigid core 49 here have an arched shape opposite cavity 181 and a straight segment opposite cavity 181, i.e. near cavity 181.The straight segment is located at a non-zero distance from the cavity 181 so as to form a portion of channel, here rectangular, between each first or second opening 57, 59 and the cavity 181. The portion of channel corresponds to the surface of the rigid core separating the cavity 181 and each first or second opening 57, 59. Cathode channel portions 601 are formed by the channel portions between the first openings 57 and the cavity 181. Anode channel portions 602 are formed by the channel portions between the second openings 59 and the cavity 181.

[0066] The rigid core 49 may have a constant thickness. Alternatively, portions of the rigid core 49 may have different thicknesses. For example, the anodic or cathodic channel portions 601, 602 may have a thickness less than or equal to the thickness of the rigid core 49. Here, the anodic channel portions 602 have a thinner thickness.

[0067] The first openings 57 and the second openings 59 of the rigid core 49 have inner edges. The first openings 57 and the second openings 59 of the rigid core 49 have a perimeter greater than the first openings 43 and the second openings 45 of the frame 31. The first openings 57 and the second openings 59 of the rigid core 49 are inscribed and centered within the first openings 43 and the second openings 45 of the frame 31. The first openings 57 and the second openings 59 of the rigid core 49 are positioned at a distance from the cavity 181.

[0068] Here, the rigid core 49 is made of perforated sheet metal. The rigid core 49 can be a metallic core. Here, the rigid core 49 is made of steel.

[0069] The flexible insulating layer 51 covers at least part of the rigid core 49 so as to form functional surfaces of the frame 31. The rigid core 80 may include holes 80 provided at a distance from the cavity 181 allowing the rigid core 49 to be positioned during the manufacture of the rigid core 49.

[0070] The flexible insulating layer 51 covers the inner edges of the cavity 181 so as to form the cavity 18 of the frame 31. The flexible insulating layer 51 covers the inner edges of the first openings 57 and the second openings 59 of the rigid core 49 so as to form the first openings 43 and the second openings 45 of the frame 31.

[0071] On the first face 53 of the rigid core 49, as illustrated in, the flexible insulating layer 51 covers each portion of the anodic channel 601 between the first openings 57 and the cavity 181 according to a first thickness so as to form the bottom of the channels 47 of the frame 31.

[0072] The flexible insulating layer 51 can cover the perimeter of the cavity 18 of the frame 31, extending from the edges of the cavity 18 outwards, to form a step 41 of the frame 31. The step 41 extends from the edge of the cavity 18 to an outer edge of the step. The step 41 can support the proton membrane 11. The step 41 is formed around the perimeter of the cavity 18 of the frame 31. On the step 41, the flexible insulating layer 51 has an additional thickness corresponding to a second layer, forming a membrane joint 62. The proton membrane 11 is compressed against the membrane joint 62. The membrane joint 62 is continuous. The membrane seal 62 ensures the seal of the proton membrane 11 between the cathode compartment 7 and the anode compartment 9. The first layer is thicker than the second layer. Here, once the proton membrane 11 is mounted, it is flush with the bottom of the channels 47.Alternatively, the bottom of the channels 47 is above the proton membrane 11 relative to the rigid core 49.

[0073] On the first face 53 of the rigid core 49, the flexible insulating layer 51 covers the rigid core 49 with a third thickness so as to form a cathode seal 63. The cathode seal 63 surrounds the cavity 181, the first openings 57 and the cathode channel portions 601, with the exception of the common edges between the first openings 57 and the cathode channel portions 601 on the one hand, and the common segments between the cavity 181 and the cathode channel portions 601 on the other hand. The cathode seal 63 follows the inner edges of the cavity 181 and the first openings 57. The cathode seal 63 extends at a distance from the edges of the cavity 18 of the frame 31. The cathode seal 63 extends at least from the outer contour of the step 41. The cathode seal 63 surrounds the step 41. The cathode seal 63 may extend at a distance from, or from, the edges of the first openings 57.The third layer is greater than the first layer, so as to form the edges of the channels 47.

[0074] The cathode seal 63 forms a closed contour of the cathode compartment 7.

[0075] On the first face 53 of the rigid core 49, the flexible insulating layer 51 also covers the rigid core 49 around the second openings 45 of the frame 31 along the third thickness, forming second opening joints 64. The second opening joints 64 may be tangent to the inner edges of the second openings 45 of the frame 31 and extend outwards from these inner edges. The second opening joints 64 may extend at a distance from the edges of the second openings 45 as illustrated in the figures. Each second opening joint 64 forms a closed contour around one of the second openings 45.

[0076] On the second face 55 of the rigid core 49, as illustrated in, the flexible insulating layer 51 covers each portion of cathode channel 602 between the second openings 59 and the cavity 181 with a fourth thickness so as to form the bottom of the channels 48 of the frame 31, cathode side 9.

[0077] On the second face 55 of the rigid core 49, the flexible insulating layer 51 covers the rigid core 49 with a fifth thickness so as to form an anode seal 65. The anode seal 65 surrounds the cavity 181, the second openings 59 and the anodic channel portions 602, with the exception of the common edges between the second openings 59 and the anodic channel portions 602 on the one hand, and the common segments between the cavity 181 and the anodic channel portions 602 on the other hand. The anode seal 65 follows the inner edges of the cavity 181 and the second openings 59. The anode seal 65 extends away from the edges of the cavity 18 of the frame 31. The anode seal 65 surrounds cavity 18. The anode seal 65 can extend away from or from the edges of the second openings 59. The fifth thickness is greater than the fourth thickness, so as to form the edges of the channels 48.

[0078] The anode seal 65 forms a closed contour of the anode compartment 9.

[0079] As shown in the figures, the flexible insulating layer 51 may include an additional anode seal 651 arranged around the cavity 18 to improve sealing and better distribute the pressure exerted on the rigid core 49. Here, the anode seal 65 is arranged on the second face 55 of the rigid core 49 opposite the membrane seal 62. The additional cathode seal 651 is arranged on the second face 55 of the rigid core 49 opposite the cathode seal 63.

[0080] On the second face 55 of the rigid core 49, the flexible insulating layer 51 also covers the rigid core 49 around the first openings 43 of the frame 31 according to the fifth thickness, forming first opening joints 66. The first opening joints 66 may be tangent to the inner edges of the first openings 43 of the frame 31 and extend outwards from these inner edges. The first opening joints 66 may extend at a distance from the edges of the first openings 43. Each first opening joint 66 forms a closed contour around one of the first openings 43.

[0081] Once the stack 3 is assembled, the cathode gasket 63, the second opening gaskets 64, the anode gasket 65 and the first opening gaskets 66, and where applicable the additional cathode gasket 651 are compressed against one of the bipolar plates 30 so as to form the seal of the cathode compartments 7 and anode compartments 9, the first openings 37, the second openings 39 and the channels 47.

[0082] Here, the third thickness and the fifth thickness define respectively the height of the cathode compartment 7 and the anode compartment 9.

[0083] Alternatively, the step 41 is made on the second face 38 of the frame 31, anode side.

[0084] The flexible insulating layer 51 may include a plurality of studs 67 arranged on the bottom of the channels 48 of the frame 31, on the anode side 9. Here, the studs 67 are elongated in shape according to the direction of fluid flow. The studs 67 are arranged so as to distribute the pressure exerted on the rigid core 49 near the channels 48 and to promote homogeneous fluid flow. The studs 67 here have a sixth thickness, less than the fifth thickness. Once the stack 3 is assembled, the bipolar plate 30 is in contact with the studs 67. The pressure exerted on the bipolar plate 30 is lower in the vicinity of the studs 67 compared to the pressure exerted near the anode seal 65, limiting the risk of deformation of the frame 31 or the bipolar plate 30 and thus reducing the risk of leakage.

[0085] In an embodiment not shown, the flexible insulating layer 51 may include a plurality of additional studs similar to the studs 67, arranged on the bottom of the channels 47 on the anode side.

[0086] The flexible insulating layer 51 may include a first outer contour 681 on the first face 53 of the rigid core 51 and a second outer contour 682 on the second face 55 of the rigid core 51. The first outer contour 681 and the second outer contour 682 are intended to occupy a space in the rigid core 49 devoid of functional areas.

[0087] The first outer contour 681 and the second outer contour 682 each have a straight portion 683 along the long sides of the frame 31 and curved portions 684 connecting the straight portions 683 to the openings provided at the ends of the short sides of the cavity 18, here the first openings 43. The first outer contour 681 and the second outer contour 682 also include bridges 685 connecting the straight portions 683 respectively to the cathode joint 63 and anode joint 65, or where applicable to the additional cathode joint 651, so as to form internal cavities 686.

[0088] The first outer contour 681 has a seventh thickness, less than the third thickness. The second outer contour 682 has the same thickness as the studs 67, namely the sixth thickness.

[0089] On the cathode side, the bipolar plate 30 rests partly on the first outer contour 681. On the cathode side, the bipolar plate 30 rests partly on the second outer contour 682.

[0090] Each bridge 685 and each curved section 684 has a groove 687 to fluidly connect each internal cavity 686. The grooves 687 of the curved sections 684 allow the internal cavities 686 to be fluidly connected to the outside. Thus, in the event of any gas leakage from the cathode 7 or anode 9 compartments, the gas can escape to the outside without generating internal overpressure.

[0091] The first to seventh thicknesses are dimensioned according to the desired thickness of the cathode or anodic channels 47, 48 of the cathode compartments 7 and anode compartments 9 as well as the pressures exerted on the frame 31 and on the bipolar plates 30.

[0092] The proton exchange membrane 11 is mounted in the cavity 18 of the frame 31. The proton exchange membrane 11 is positioned away from the bipolar plates 30. The proton exchange membrane 11 fits snugly around the edge of the cavity 18, i.e., the inner periphery of the frame 31. The proton exchange membrane 11 covers the surface of the cavity 18. The contact between the proton exchange membrane 11 and the frame 31 is sealed.

[0093] The proton exchange membrane 11 forms within cell 5 the two distinct compartments, the anode compartment 7 and the anode compartment 9. The cathode compartment 7 is delimited along two parallel planes by the proton exchange membrane 11 and the bipolar plate 30, and the inner periphery of the cavity 18. The anode compartment 9 is delimited along two parallel planes by the proton exchange membrane 11 and the bipolar plate 30 of the adjacent cell, and the inner periphery of the cavity 18.

[0094] In the illustrated embodiment, the cathode compartment 7 houses at least one porous transport layer 32 of cathode 7. In the illustrated embodiment, the anode compartment 9 houses at least one porous transport layer 34 of anode 9.

[0095] The porous transport layer 32 of the cathode or the porous transport layer 34 of the anode is compressed between the proton exchange membrane 11 and one of the bipolar plates 30. The porous transport layer 32 of the cathode or the porous transport layer 34 of the anode is configured to press against most of the proton exchange membrane 11. The porous transport layer 32 of the cathode or the porous transport layer 34 of the anode ensures uniform support of the proton exchange membrane 11. The rigidity of the porous transport layers 32 and 34 ensures the flatness of the membrane, especially when the pressure difference between the cathode compartment 7 and the anode compartment 9 is high. In operation, water enters the cathode compartments 7 and the anode compartments 9 of all the cells 5 of the device through the water supply lines 13.The water then passes through the porous transport layers 14 to come into contact with the proton exchange membranes.

[0096] In one embodiment, the positioning and retention of the proton exchange membrane 11 can be achieved using the step 41 provided on the frame 31. The step 41 may have a radial annular surface for the proton exchange membrane 11.

[0097] In the illustrated embodiment, at least one porous spacer 33 of cathode 7 can be arranged between the porous transport layer 32 and the bipolar plate, and at least one porous spacer 35 of anode 9 can be arranged between the porous transport layer 34 of anode 9 and the bipolar plate of the adjacent cell. The porous spacer 33 enhances water diffusion on the active surface of the proton exchange membrane 11.

[0098] The materials used in the cathode compartment 7 components are resistant to acidic and oxidizing environments. The materials used in the anode compartment 9 components are resistant to acidic and reducing environments. The materials used in the anode compartment 9 components are resistant to hydrogen hydration. However, the supply of titanium is subject to uncertainty due to the scarcity of the material.

[0099] The porous transport layers 32 of the cathode compartments 7 and the porous transport layers 34 of the anode compartments 9 can have different thicknesses ranging from 0.5 to 3 mm. The porous transport layers 32 of the cathode compartments 7 can be made of a conductive material resistant to acidic and oxidizing media, such as titanium. The porous transport layers 34 of the anode compartments 9 can be made of a conductive material resistant to acidic and reducing media, such as carbon or titanium. The porous transport layers 32 of the cathode compartments 7 have a porosity ranging from 20% to 70%. The porous transport layers 34 of the anode compartments 9 can have porosities ranging from 20% to 70%.

[0100] The porous spacers 33 of the cathode compartments 7 and the porous spacers 35 of the anode compartments 9 can have different thicknesses ranging from 0.5 to 3 mm. The porous spacers 33 of the cathode compartments 7 can be made of a conductive material resistant to acidic and oxidizing media, such as titanium. The porous spacers 35 of the anode compartments 9 can be made of a conductive material resistant to acidic and reducing media, such as carbon or titanium. The porous spacers 33 of the cathode compartments 7 have a porosity ranging from 30% to 80%. The porous spacers 35 of the anode compartments 9 have a porosity ranging from 30% to 80%.

[0101] In an embodiment not shown, the bipolar plates have a polygonal shape. The bipolar plates are provided with at least two opposing openings. Each opening communicates with at least two openings in the frame. In this embodiment, the frame is also polygonal in shape.

[0102] The sum of the thicknesses of the proton exchange membrane 11 and the porous transport layers 14 is greater than the distance between two consecutive bipolar plates 30. Thus, a compressive force on the membranes is exerted by the bipolar plates 30. This compressive force is normal to the main surface of the bipolar plates 30 and is directed inwards towards the cell 1. The bipolar plates 30 are held in place along this normal direction by the compression of the stack 3 of cells 5.

[0103] The cathode compartment 7 and the anode compartment 9 are sealed. The connections between the cathode compartment 7 and the outside of cell 5, and between the anode compartment 9 and the outside of cell 5, are formed by channels 47 and 48. The risk of the introduction of impurities and dust is reduced. The flexible insulating layer 51 compensates for cumulative assembly tolerances. The thickness of the frame 31 is greater than the distance between the bipolar plates 30. The compression ratio of the flexible insulating layer 51 varies according to the cumulative assembly tolerances within a range of compression ratios for said seal.

[0104] The supply lines 13 and the drain lines 15 are formed by the superposition of openings arranged opposite each other. Each supply line 13 and drain line 15 is made by a succession of first openings 37 of bipolar plate 30 and first openings 43 of frame 31 or by a succession of second openings 39 of bipolar plate 30 and second openings 45 of frame 31.

[0105] The supply lines 13 and the discharge lines 15 formed by a succession of first openings 37 of bipolar plate 30 and first openings 43 of frame 31 form cathode supply lines 13 and discharge lines 15. The supply lines 13 and the discharge lines 15 formed by a succession of second openings 39 of bipolar plate 30 and second openings 45 of frame 31 form cathode supply lines 13 and discharge lines 15.

[0106] Each cathode 7 or anode 9 compartment includes at least one fluidic connection with a supply line 13 and at least one fluidic connection with a discharge line 15, opposite each other with respect to the cavity 18. Here, each fluidic connection is made by a cathode or anode channel 47, 48. Here, each cathode 7 or anode 9 compartment includes one fluidic connection with two supply lines 13 and one fluidic connection with two discharge lines 15.

[0107] Hydraulic connections are provided with the supply lines 13 and the discharge lines 15 so as to fluidly connect the electrolysis device 1 with an external water supply and external devices for recovering dihydrogen and, where applicable, dioxygen.

[0108] The supply lines 13 and the discharge lines 15 are made by stacking the frames 31 and bipolar plates 30 of each cell 5. Thus, each supply line 13 and each discharge line 15 has a wall in the material of the flexible insulating layer 51 and in the material of the bipolar plates 30.

[0109] In the cell, the water comes into contact with the main faces of the bipolar plates 30 and with the supply 13 and discharge 15 pipes.

[0110] In other words, an electrolysis plant comprises a plurality of electrolysis cells. Each cell includes an anode compartment and a cathode compartment separated by a proton exchange membrane housed in a frame. Each compartment is delimited by the frame, the membrane, and a bipolar plate. The frame electrically isolates the two compartments. Each bipolar plate forms the boundary between two consecutive cells. In an electrolysis device, the cells are numbered from 1 to N and have aligned apertures. The first bipolar plate of a cell of rank k between 2 and N-1 is shared with the cell of rank k-1. The second bipolar plate of a cell of rank k between 2 and N-1 is shared with the cell of rank k+1. The frame includes a rigid core made from a flat sheet. The rigid core has a constant thickness. The rigid core is overmolded.The overmolding is made of a flexible insulating material. The overmolding, or flexible insulating layer, covers at least part of the rigid core. The flexible insulating layer forms all the functional surfaces of the frame and isolates the frame from contact with a fluid such as water, hydrogen, or oxygen. The flexible insulating layer forms the bearing surface of the membrane as well as all the seals of each cell, ensuring that each compartment is watertight. The flexible insulating layer is arranged to distribute the internal pressure forces within the cells.

Claims

Water electrolysis cell with a PEM polymer electrolytic membrane for the production of hydrogen, comprising a proton exchange membrane (11), a cathode compartment (7) in contact with the proton exchange membrane (11), an anode compartment (9) in contact with the proton exchange membrane (11), a first conductive plate (30) in contact with the cathode compartment (7), forming a first end of the cell in the thickness direction, a second conductive plate (7) in contact with the cathode compartment (7), forming a second end of the cell in the thickness direction, the first conductive plate (30) being able to be common with an anterior cell, the second conductive plate (30) being able to be common with a posterior cell, and a frame (31) supporting the proton exchange membrane (11),the cathode compartment (7) being delimited along two parallel planes by the proton exchange membrane (11) and the first conductive plate (30), the cathode compartment (7) being laterally delimited by the frame (31), the anode compartment (9) being delimited along two parallel planes by the proton exchange membrane (11) and the second conductive plate (30), the anode compartment (9) being laterally delimited by the frame (31), the frame (31) being provided with at least two first openings (43) each communicating with the cathode compartment (7) by an anodic channel (47) and at least two second openings (45) each communicating with the anode compartment (9) by a cathodic channel (48), said cathodic and anodic channels (47, 48) being disposed in the frame (31), each of said cathodic and anodic channels (47, 48) being intersecting with one of the said first and second openings (43, 45),the first and second conductive plates (30) being provided with first and second plate openings (37, 39), said first and second plate openings (37, 39) being through and in communication with at least one of the first and second openings (43, 45) of the frame (31), the first and second openings (43, 45) of the frame (31) each being delimited by an edge of the frame, the openings (37, 39) of the conductive plate (30) each being delimited by a plate edge, the frame (31) comprising a rigid core (49) covered at least in part by a flexible insulating layer (51), the rigid core (49) having a constant thickness, the flexible insulating layer (51) covering the edges of the openings (43, 45) of the frame (31), the flexible insulating layer (51) having at least first and second surfaces,the first and second surfaces being at a distance from the rigid core according to a first and second thickness respectively, the first thickness being greater than the second thickness. Water electrolysis cell according to claim 1, wherein the rigid core (49) consists of a flat sheet metal plate. Water electrolysis cell according to any one of claims 1 or 2, wherein the rigid core (49) comprises two opposite parallel faces (53, 55), forming two sides and the frame (31) comprises at least first and second surfaces on one of the sides and at least third and fourth surfaces on the other side of the rigid core (49), the third and fourth surfaces being at a distance from the rigid core (49) by a third thickness and a fourth thickness respectively. Water electrolysis cell according to any one of the preceding claims, wherein the openings (37, 39) of the conductive plate (30) have a form correspondence with the openings (43, 45) of the frame (31) and are mounted opposite each other, and openings (57, 59) are provided in the rigid core (49), the openings (57, 59) of the rigid core (49) having a form correspondence with the openings (43, 45) of the frame (31). Water electrolysis cell according to any one of the preceding claims, wherein the flexible insulating layer (51) ensures the sealing of the cathode (7) and anode (9) compartments. Water electrolysis cell according to any one of the preceding claims, wherein the frame (31) comprises a step (41) supporting the membrane (11), the flexible insulating layer forming a membrane seal (62) disposed on the step (41). Water electrolysis cell according to any one of the preceding claims, wherein the flexible insulating layer (51) comprises a cathode seal (63) fluidly insulating the cathode compartment (7), an anode seal (65) fluidly insulating the anode compartment (9) and opening seals (66, 64) insulating the second openings (45) of the frame (31) on the cathode side and the first openings (43) of the frame (31) on the anode side. Water electrolysis cell according to claims 6 and 7, wherein the flexible insulating layer (51) includes an additional anode seal (651) fluidly insulating the anode compartment (9), the anode seal (65) and the additional anode seal (651) being arranged opposite the cathode seal (63) and the membrane seal (62) relative to the frame (31). Water electrolysis cell according to any one of the preceding claims, wherein the channels (47, 48) of the frame (31) are each partly formed by the flexible insulating layer (51). Water electrolysis cell according to any one of the preceding claims, wherein the first and second conductive plate (30) rest on the flexible insulating layer (51), respectively on each side of the frame (31). Water electrolysis cell according to any one of the preceding claims, wherein the frame (31) comprises a portion (682) of flexible insulating layer (51) disposed on a periphery of the cathode compartment (7) at a distance from the cathode compartment (7) and a portion (683) of flexible insulating layer (51) disposed on a periphery of the anode compartment (9) at a distance from the anode compartment (9), the flexible insulating layer (51) comprising walls connecting said portions (682, 683) of flexible insulating layer (51) respectively to the cathode joint (63) and to the anode joint (65), the walls forming fluidic conduits to the outside of the cell (5). Water electrolysis installation for the production of hydrogen comprising a stack of a plurality of cells (5) according to any one of the preceding claims, classified from 1 to N, having aligned openings, the first conductive plate (30) of one of said cells of rank k between 2 and N-1 being common with the cell of rank k-1 and the second conductive plate (30) of one of said cells of rank k between 2 and N-1 being common with the cell of rank k+1.

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