Polar plate, single cell and alkaline electrolytic cell

Abstract

The invention discloses a polar plate, a single cell and an alkaline electrolytic bath, and relates to the technical field of electrolytic baths, a matched cover plate assembly is arranged on a manifold opening of the polar plate, the cover plate assembly is made of an insulating and corrosion-resistant material, and the cover plate assembly comprises an upper cover plate and a lower cover plate; the lower cover plate is provided with an opening part matched with the opening part of the manifold opening, the lower cover plate is embedded in the position of the manifold opening, a gap bridge area is arranged in the area, located between the manifold opening and the flow channel area, of the lower cover plate, the upper cover plate is arranged on the lower cover plate in a covering mode to form a closed gap bridge channel, and the upper cover plate covers the lower cover plate. And fluid entering and exiting from the manifold opening is communicated with the flow channel area of the polar plate body through the gap bridge channel. According to the invention, the generation of bypass current can be greatly reduced, the loss of effective current in the polar plate is reduced, and the current efficiency of the electrolytic cell is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of electrolytic cells, and in particular to a polar plate, a single cell and an alkaline electrolytic cell. Background Art

[0002] In recent years, the global green hydrogen industry has exploded, and the demand for water electrolysis hydrogen production equipment has soared. Since alkaline water electrolysis hydrogen production technology can produce hydrogen on a large scale and at a low cost, it currently occupies the vast majority of market orders and is considered to be the most mature technology at present. However, the rapid development of the hydrogen energy industry has put forward higher requirements for electrolyzer products. There is still a lot of room for optimization in the design of the structure, materials, etc. of alkaline electrolyzers. Square alkaline electrolyzers are an important branch of alkaline electrolyzers. At present, the electrical density of known square alkaline electrolyzers can basically exceed 10,000A / m2, and some can even reach 15,000A / m2. Compared with the 5,000A / m2 of traditional electrolyzers, its advantages are very obvious.

[0003] However, during the operation of the square alkaline electrolytic cell, there is a bypass current, which leads to adverse effects such as energy loss, equipment corrosion, shortened life and decreased electrolytic cell performance. Bypass current refers to the current conducted along a low-resistance path different from the electrolysis path. Bypass current is one of the most important factors restricting the current efficiency of the electrolytic cell. The manifold design of the electrode plate of the electrolytic cell will affect the distribution of current. Improper design will cause current shunting and generate bypass current. The main reason is that the metal area around the manifold port of the electrode plate is exposed to the alkaline solution during operation and is conductive. In this way, part of the current is directly introduced into the interior of the electrode plate through the alkaline solution at the manifold port, and does not participate in the electrolysis reaction, forming an invalid bypass current, which leads to a significant loss of effective current inside the electrode plate and reduces the overall current efficiency of the electrolytic cell. Summary of the Invention

[0004] The present invention provides a pole plate, which can greatly reduce the occurrence of bypass current at the manifold port, reduce the loss of effective current inside the pole plate, and improve the current efficiency of the electrolytic cell.

[0005] In a first aspect, the present invention provides an electrode plate comprising an electrode plate body, wherein flow channel regions are respectively provided in the middle of two side surfaces of the electrode plate body, the two flow channel regions being an anode flow channel region and a cathode flow channel region, and manifold ports are respectively provided at both ends of the electrode plate body, characterized in that:

[0006] A matching cover plate assembly is provided on the manifold port, and the cover plate assembly is made of insulating and corrosion-resistant materials. The cover plate assembly includes an upper cover plate and a lower cover plate. The lower cover plate is provided with an opening that matches the opening of the manifold port. The lower cover plate is embedded in the manifold port. A bridge area is provided on the lower cover plate between the manifold port and the flow channel area. The upper cover plate is installed on the lower cover plate to form a closed bridge channel. The fluid entering and exiting the manifold port is connected to the flow channel area of the electrode body through the bridge channel.

[0007] The electrode body is provided with an inner sinking groove which cooperates with the cover plate assembly, and the cover plate assembly is placed inside the inner sinking groove and embedded in the groove.

[0008] The upper cover plate is installed above the bridge area of the lower cover plate.

[0009] The bottom of the lower cover plate is provided with a boss corresponding to the manifold port; the top of the upper cover plate is provided with a cover plate sealing groove corresponding to the sealing groove of the plate body.

[0010] In a second aspect, the present invention provides a single cell comprising a plate as described in any one of the first aspects above.

[0011] The single cell also includes a sealing gasket, an anode nickel foam, a cathode nickel foam and a composite diaphragm. The anode side of the electrode plate is press-fitted and connected to one of the sealing gaskets and the anode nickel foam, and the cathode side of the electrode plate is press-fitted and connected to another of the sealing gaskets, the cathode nickel foam and the composite diaphragm in sequence. A support layer is respectively provided between one of the sealing gaskets and the anode nickel foam and between another of the sealing gaskets and the cathode nickel foam.

[0012] The support layer is a nickel mesh support layer, the thickness of the nickel mesh support layer is 0.15 mm to 0.2 mm, and the pore size of the nickel mesh support layer is 1 mm to 3 mm.

[0013] The sealing gasket is provided with a sealing area on the side facing the electrode plate, and the sealing area corresponds to the circumference of the electrode plate and the circumference of its manifold port. The sealing area includes an outer ring boss, a middle ring boss and an inner ring boss from inside to outside, wherein the height of the inner ring boss is smaller than the height of the middle ring boss.

[0014] In a third aspect, the present invention provides an alkaline electrolytic cell comprising any single cell described in the second aspect.

[0015] The beneficial effect of the electrode plate of the present invention is that a cover plate assembly with insulating and corrosion-resistant properties is provided at the manifold port of the electrode plate, and a bridge area channel is formed on the cover plate assembly between the manifold port and the flow channel area, so that the manifold port of the electrode plate can be prevented from contacting the alkaline solution of the electrolytic cell, thereby greatly reducing the occurrence of bypass current, reducing the loss of effective current inside the electrode plate, and improving the current efficiency of the electrolytic cell.

[0016] The single cell and electrolytic cell of the present invention have the following beneficial effects: support layers are provided between the electrode plate and the anode nickel foam, and between the electrode plate and the cathode nickel foam, respectively. Compared with the traditional single cell structure, in which the electrode plate is in direct contact with the anode nickel foam and the cathode nickel foam, there is poor pressure resistance, which affects the sealing and fastening effects. By providing the support layer, the present invention can withstand high-pressure sealing force and ensure the sealing and fastening effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Schematic diagram of the overall structure of the electrode plate according to the first embodiment of the present invention;

[0018] Figure 2 This is an exploded view of the electrode plate according to the first embodiment of the present invention;

[0019] Figure 3 The front side of the lower cover plate of the first embodiment of the present invention;

[0020] Figure 4 This is a rear view of the lower cover plate according to the first embodiment of the present invention;

[0021] Figure 5 A partial cross-sectional view of the manifold opening on the electrode plate of the first embodiment of the present invention;

[0022] Figure 6 This is an exploded view of a single cell according to the second embodiment of the present invention;

[0023] Figure 7 This is a schematic diagram of the overall structure of a sealing gasket according to a second embodiment of the present invention;

[0024] Figure 8 This is a schematic diagram of the partial structure of the sealing gasket according to the second embodiment of the present invention;

[0025] Figure 9 This is a partial cross-sectional view of a single tank according to the second embodiment of the present invention.

[0026] Description of Reference Numerals

[0027] 1. Plate body; 11. Inner sink; 2. Flow channel area; 3. Manifold port; 4. Cover plate assembly; 41. Upper cover plate; 42. Lower cover plate; 421. Port; 422. Bridge area; 4221. First parallel flow channel; 4222. First parallel flow channel; 4223. Point flow channel; 423. Boss; 5. Sealing gasket; 51. Outer ring boss; 52. Middle ring boss; 53. Inner ring boss; 6. Anode nickel foam; 7. Cathode nickel foam; 8. Composite diaphragm; 9. Support layer. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of this application to clearly and completely describe the technical solutions in the embodiments of this application. Obviously, the embodiments described are only part of the embodiments of this application, not all of the embodiments. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of this application.

[0029] Among them, the same parts are represented by the same figure marks. It should be noted that the words "front", "rear", "left", "right", "up" and "down" used in the following description refer to the directions in the drawings of the present application specification, and the words "bottom" and "top", "inside" and "outside" refer to directions toward or away from specific parts, respectively. In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present application specification, the meaning of "multiple" is two or more.

[0030] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0031] Example 1

[0032] This embodiment provides a plate, such as Figure 1 The overall structure diagram of the plate shown in Figure 2As can be seen from the exploded view of the electrode plate shown, the electrode plate includes a square electrode plate body 1, and flow channel areas 2 are respectively provided in the middle of the two sides of the electrode plate body 1. The two flow channel areas 2 are respectively an anode flow channel area and a cathode flow channel area. Manifold openings 3 are respectively provided at both ends of the electrode plate body 1, and a matching cover plate assembly 4 is provided on the manifold opening 3. The cover plate assembly 4 is made of insulating and corrosion-resistant material. The cover plate assembly 4 includes an upper cover plate 41 and a lower cover plate 42. The lower cover plate 42 is provided with a mouth 421 matching the mouth of the manifold opening 3. The lower cover plate 42 is embedded in the position of the manifold opening 3. A bridge area 422 is provided on the lower cover plate 42 between the manifold opening 3 and the flow channel area 2. The upper cover plate 41 is covered on the lower cover plate 42 to form a closed bridge channel, so that the fluid entering and exiting the manifold opening 3 is connected to the flow channel area 2 of the electrode body 1 through the bridge channel.

[0033] In this embodiment, by adopting the setting of the cover plate assembly 4, a closed bridge channel is formed between the manifold port 3 and the flow channel area of the electrode body 1. Since the manifold port 3 is made of insulating and alkali-resistant material, compared with the existing alkaline electrolytic cell in which the mouth of the electrode plate is directly exposed to the alkaline solution, in this embodiment, the fluid entering and exiting each manifold port and the flow channel area does not directly contact the metal area at the manifold port 3, but is connected through the cover plate assembly 4, thereby avoiding corrosion of the manifold port and avoiding the formation of a current path connected to the flow channel area at the manifold port, reducing the generation of bypass current, reducing the loss of effective current inside the electrode plate, and improving the current efficiency of the electrolytic cell.

[0034] Preferably, on the anode side of the plate body 1, the cover plate assembly 4 is provided on the two manifold openings communicating with the anode flow channel area, and on the cathode side of the plate body 1, the cover plate assembly 4 is provided on the two manifold openings communicating with the cathode flow channel area. Meanwhile, the cover plate assembly 4 is provided only at the manifold opening communicating with the flow channel area.

[0035] Specifically, the manifold opening 3 can be a square, circular, or semicircular shape. In this embodiment, the manifold opening 3 is a long, rectangular through-hole. The lower cover plate 42 of the cover plate assembly 4 is installed around the manifold opening 3. The side of the lower cover plate 42 near the flow channel area is connected to the inlet and outlet of the flow channel area. The lower cover plate 42 of the cover plate assembly 4 is provided with a long, rectangular opening 421 that matches the opening of the manifold opening 3. This allows the lower cover plate 41 to cover the periphery of the opening of the manifold opening 3 and the bridge area, effectively preventing direct contact between the manifold opening 3 and the alkali solution, thereby reducing the generation of bypass current.

[0036] Preferably, the electrode body 1 is provided with an inner sinking groove 11 that cooperates with the cover plate assembly 4, and the cover plate assembly 4 is placed inside the inner sinking groove 11 for embedding connection. The cover plate assembly 4 can be installed inside the inner sinking groove 11 by dispensing glue, laser welding or interference fit connection. Through the provision of the inner sinking groove 11, after the cover plate assembly 4 is placed in the inner sinking groove 11, its surface height is flush with the height of the electrode body 1. In this way, when the electrode body 1 is connected to other sealing components, the sealing components do not require a special design structure and can be used directly, so that the manifold port 3 can be normally sealed and connected to ensure the sealing effect. At the same time, it also facilitates the installation and positioning of the cover plate assembly 4, and the positioning is accurate and the connection is firm.

[0037] Specifically, if Figure 3 、 4 As shown in the front and back views of the lower cover plate, the bridge area 422 at the upper end of the lower cover plate 42 forms a gradually expanding flow channel region extending from the manifold opening 3 to the bridge area 2. This gradually expanding flow channel region connects the manifold opening 3 with the inlet and outlet of the flow channel region 2. When fluid flows in, it enters the flow channel region 2 from the manifold opening 3, where it is evenly distributed within the gradually expanding flow channel region before flowing into the flow channel region 2. The gradually expanding flow channel region features a composite flow channel design. Specifically, the gradually expanding flow channel region comprises spaced first ridges near the manifold opening 3, forming first parallel flow channels 4221. Spaced second ridges are also provided near the flow channel region 2, forming second parallel flow channels 4222. Spaced protrusions are provided between the first and second parallel flow channels 4221 and on either side of the second parallel flow channel 4222, forming dot-shaped flow channels 4223. The gradually diverging flow channel region thus forms a composite flow channel composed of point-shaped flow channels and parallel flow channels. When fluid flows in, it enters the manifold port 3 through the first parallel flow channel 4221, experiencing low flow resistance and pressure loss. It then flows through the point-shaped flow channels 4223, where the fluid is turbulently distributed evenly. Finally, the majority of the fluid flows through the second parallel flow channel 4222, where it is distributed to the flow channel region 2.

[0038] Preferably, the first parallel flow channels 4221 and the second parallel flow channels 4222 are parallel to each other, and the projections of the projections on the electrode body 1 are strip-shaped. Alternatively, wavy projections can be used to further increase the contact area between the fluid and the bridge area 422. The protrusions used in the point-shaped flow channels 4223 can be cylindrical, truncated cone, square, or other shapes. The point-shaped flow channels 4223 create turbulent flow in the fluid bridge area, making the fluid distribution more uniform. Furthermore, the point-shaped flow channels provide a larger fluid area, which can balance the pressure distribution in the bridge area 422.

[0039] Preferably, a boss 423 that matches the bottom of the lower cover 42 is provided at the position of the manifold port 3 of the corresponding plate body 1; the provision of the boss 423 facilitates the engagement and installation of the lower cover 42 and the plate body 1, and at the same time, the lower cover 42 is buckled at the mouth of the manifold port 3, which can completely wrap the mouth and effectively prevent the mouth of the manifold port 3 from direct contact with the alkali solution.

[0040] Preferably, the shape of the upper cover plate 41 matches the bridge area 422 of the lower cover plate 42, and the bridge area 422 of the lower cover plate 42 is provided with a mounting groove. The upper cover plate 41 is installed above the bridge area 422 of the lower cover plate 42, and its surface height is the same as the surface height of the plate body 1. After the bridge area 422 on the lower cover plate 42 is covered with the upper cover plate 41, a bridge channel closed on both sides can be formed. The top of the upper cover plate 41 away from the side connected to the lower cover plate 42 is provided with a matching cover sealing groove 411 at the position of the sealing groove on the plate body 1. In this way, the plate body 1 can be connected to the sealing component matched with it without changing the existing sealing component structure, and an excellent sealing effect can also be achieved. Figure 5 As can be seen from the partial cross-sectional view of the manifold opening on the electrode plate shown, the upper cover plate 41 and the lower cover plate 42 cooperate to form a complete bridge area. When the fluid flows in, the alkaline solution flows from the manifold opening 3 through the closed bridge area on the cover plate assembly 4 into the flow channel area 2 for electrolysis reaction. In this way, the contact between the manifold opening 3, the bridge area 2 and the alkaline solution in the flow channel area 2 can be avoided, which greatly reduces the generation of bypass current and improves the current efficiency of the electrolytic cell.

[0041] Preferably, the upper cover 41 and the lower cover 42 are made of insulating and corrosion-resistant materials, such as PSU or PPSU, and can be formed by machining or injection molding. The plate body 1 is often made of nickel mesh or nickel foam, which has excellent conductivity.

[0042] Example 2

[0043] This embodiment provides a single cell, including the electrode plate in the above embodiment 1, specifically, as Figure 6 As can be seen from the exploded view of the single cell shown, the single cell also includes a sealing gasket 5, an anode nickel foam 6, a cathode nickel foam 7 and a composite diaphragm 8. The anode side of the electrode plate is press-fitted and connected with a sealing gasket 5 and the anode nickel foam 6, and the cathode side of the electrode plate is press-fitted and connected with another sealing gasket 5, the cathode nickel foam 7 and the composite diaphragm 8 in sequence. A supporting layer 9 is also provided between one sealing gasket 5 and the anode nickel foam 6 and between the other sealing gasket 5 and the cathode nickel foam 7, respectively.

[0044] In the prior art, in terms of electrolytic materials, the plates of single alkaline electrolytic cells usually use nickel-based materials, such as nickel foam, and the combination of nickel foam and composite diaphragm is used to support the high electrical density performance output of square alkaline cells. However, in large-plate electrolytic cells, there are many problems with the material combination of nickel foam and composite diaphragm, such as the melting phenomenon of nickel foam under high current. In addition, since the sealing structure of the alkaline electrolytic cell still uses the traditional electrolytic cell, that is, PTFE sheet is used for hard pressure sealing, and the alkaline electrolytic cells currently on the market basically use normal pressure or low pressure (less than or equal to 0.5MPa) sealing, and hard pressure sealing requires an extremely large packaging force to achieve the sealing and fastening effect, this has a great impact on the nickel foam and composite diaphragm of the alkaline electrolytic cell, such as component breakage, size mismatch, sealing failure and other defects.

[0045] In the single cell of this embodiment, a support layer is added between the anode side of the plate and the anode nickel foam 6, and between the cathode side of the plate and the cathode nickel foam 7, which can protect the nickel foam plate and prevent the nickel foam plate from being damaged due to overpressure during packaging; in addition, the support layer can increase the contact area between the nickel foam and the plate, which is more conducive to the passage of large current. It is suitable for the working conditions of electrolytic cells with large plate types and high electrical density, and greatly reduces the melting of the nickel foam plate.

[0046] Preferably, the support layer 9 is a nickel mesh support layer, the thickness of the nickel mesh support layer is 0.15mm to 0.2mm, the pore size of the nickel mesh support layer is 1 to 3mm, and the pores of the nickel mesh support layer can be diamond-shaped or circular through holes, etc., wherein if it is a diamond through hole, the pore size refers to the length of the diagonal, and the length of the diagonal is 1mm to 3mm. If it is a circular through hole, its diameter is 1mm to 3mm. The support layer 9 uses an ultra-thin nickel mesh layer, which not only ensures that the components of the single cell can withstand the ultra-large sealing force when pressed together, but also reduces the contact resistance when the components are tightly connected. At the same time, the pore size of the nickel mesh support layer is small, and the ridge structure of the flow channel area of the plate will not be damaged due to excessive local pressure.

[0047] Preferably, if Figure 7 、 8 As shown in the schematic structural diagram of the sealing gasket, the sealing gasket 5 is provided with a sealing area on the side facing the electrode plate. The sealing area corresponds to the circumference of the electrode plate and the circumference of the manifold port. The sealing area includes, from inside to outside, an outer ring boss 51, a middle ring boss 52, and an inner ring boss 53. When the sealing gasket 5 is connected to the anode and cathode sides of the electrode plate, since its sealing area adopts a three-layer boss arrangement, it forms a three-layer seal, which can more effectively seal the high-pressure gas in the flow channel area and prevent the occurrence of abnormalities such as poor sealing such as leakage. At the same time, it can ensure that the alkaline electrolytic cell can protect the components in contact with it under the condition of sealing high pressure (≥1.6MPa) and prevent them from being damaged by the high pressure.

[0048] Preferably, the sealing gasket 5 is an EPDM sealing gasket. Compared with the traditional hard pressure sealing using PTFE sheet as the sealing material, it has high temperature resistance, corrosion resistance and aging resistance, and can be applied to medium pressure or high pressure sealing force working conditions.

[0049] Preferably, the cross-sections of the outer ring boss 51, the middle ring boss 52 and the inner ring boss 53 are strip-shaped. At the same time, the cross-section of the boss can also be a trapezoidal, triangular or other shape with a narrow upper end and a wide lower end, wherein the height of the inner ring boss 53 is less than the height of the middle ring boss 52. Figure 9 It can be seen from the partial cross-sectional view of the single cell shown that after the single cell of this embodiment is press-assembled, the edge of the composite diaphragm 8 corresponds to the position of the inner ring boss 53 of the sealing gasket 5. If the height of the inner ring boss 53 is too high, there will be excessive local stress, which will damage the edge of the composite diaphragm. That is, considering that the composite diaphragm 8 may be over-pressurized when it is press-assembled and packaged, by reducing the height of the inner ring boss 53, it is possible to prevent abnormal over-pressure of the composite diaphragm 8 while ensuring the sealing performance of the composite diaphragm 8.

[0050] Example 3

[0051] The present invention provides an alkaline electrolytic cell, comprising the single cell and the electrode plate in the above-mentioned embodiment 2. The advantages of the electrolytic cell are the same as those of the single cell and the electrode plate, which will not be repeated here.

Claims

1. A plate comprising a plate body, wherein a flow channel region is provided in the middle of two sides of the plate body, the two flow channel regions being an anode flow channel region and a cathode flow channel region, respectively; and manifold ports are provided at both ends of the plate body, characterized in that: A matching cover plate assembly is provided on the manifold port, and the cover plate assembly is made of insulating and corrosion-resistant materials. The cover plate assembly includes an upper cover plate and a lower cover plate. The lower cover plate is provided with an opening that matches the opening of the manifold port. The lower cover plate is embedded in the manifold port. A bridge area is provided on the lower cover plate between the manifold port and the flow channel area. The upper cover plate is installed on the lower cover plate to form a closed bridge channel. The fluid entering and exiting the manifold port is connected to the flow channel area of the electrode body through the bridge channel.

2. A plate according to claim 1, characterized in that: The electrode body is provided with an inner sinking groove which cooperates with the cover plate assembly, and the cover plate assembly is placed inside the inner sinking groove and embedded in the groove.

3. A plate according to claim 2, characterized in that: The upper cover plate is installed above the bridge area of the lower cover plate.

4. The electrode plate according to claim 3, characterized in that: The bottom of the lower cover plate is provided with a boss corresponding to the manifold port; the top of the upper cover plate is provided with a cover plate sealing groove corresponding to the sealing groove of the plate body.

5. A single pool, characterized in that A polar plate comprising any one of claims 1 to 4.

6. A single pool according to claim 5, characterized in that: It also includes a sealing gasket, an anode nickel foam, a cathode nickel foam and a composite diaphragm. The anode side of the electrode plate is press-fitted with one of the sealing gaskets and the anode nickel foam, and the cathode side of the electrode plate is press-fitted with another of the sealing gaskets, the cathode nickel foam and the composite diaphragm in sequence. A support layer is provided between one of the sealing gaskets and the anode nickel foam and between another of the sealing gaskets and the cathode nickel foam, respectively.

7. A single pool according to claim 6, characterized in that: The support layer is a nickel mesh support layer, the thickness of the nickel mesh support layer is 0.15 mm to 0.2 mm, and the pore size of the nickel mesh support layer is 1 mm to 3 mm.

8. A single pool according to claim 7, characterized in that: The sealing gasket is provided with a sealing area on the side facing the electrode plate, and the sealing area corresponds to the circumference of the electrode plate and the circumference of its manifold port. The sealing area includes an outer ring boss, a middle ring boss and an inner ring boss from inside to outside, wherein the height of the inner ring boss is smaller than the height of the middle ring boss.

9. An alkaline electrolytic cell, characterized in that: A single cell comprising any one of claims 6 to 8.

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