Novel bipolar plate and PEM electrolytic bath

Abstract

The utility model discloses a novel bipolar plate and a PEM electrolytic bath, which relates to the technical field of electrolytic baths, and comprises two veneers with the same structure, a flow field area is arranged in the middle of the front side of each veneer, and a cooling water flow field area with the same flow channel arrangement mode as the flow field area is arranged in the middle of the back side of each veneer. The back surfaces of the two single plates are oppositely welded and connected to form an integrated bipolar plate, a cooling water flow field area in the bipolar plate forms an independent cooling cavity, and a flow channel inlet and a flow channel outlet which are communicated with the flow field area and the cooling cavity are formed in the two ends of the bipolar plate respectively. And meanwhile, the design requirement for light weight can be met.

Description

Technical Field

[0001] This utility model relates to the field of hydrogen production technology, and in particular to a novel bipolar plate and PEM electrolyzer. Technical Background

[0002] In a PEM electrolyzer, bipolar plates serve both a supporting and conductive function, collecting hydrogen from the cathode and oxygen from the anode while simultaneously conducting electrons. Bipolar plates must possess high mechanical stability, chemical stability, and good electrical conductivity to ensure effective gas separation and smooth current conduction.

[0003] As electrolyzers continue to expand towards larger area and larger volume technologies, electrolyzer development faces a serious challenge: the contradiction between heat dissipation of the bipolar plates and the pressure drop in the bipolar plate flow channels. Specifically, with the increase in the volume of a single cell, the heat generated by the entire cell surges, and the required water volume also increases significantly. However, for the existing bipolar plate and flow channel designs, a large water volume inevitably leads to a greater pressure drop loss. This has a significant impact on related components and structures at both the overall cell and system levels. Existing bipolar plates cannot meet the requirements of good heat dissipation and low pressure drop loss in electrolyzers operating under large area and large volume conditions.

[0004] Chinese invention patent application CN201910726946.9 discloses a metal bipolar plate for a proton exchange membrane fuel cell, which achieves heat dissipation and reduces pressure drop loss by setting up a separate cooling medium cavity. However, because its cooling medium cavity is arranged on both sides of the active region's width direction, and this metal bipolar plate scheme with cooling medium cavity channels is applied to all flow channel combinations with cooling ports located on both sides of the flow field's width direction, this structure only produces a localized cooling effect at both ends of the active region, resulting in poor cooling performance and difficulty in meeting practical requirements. Furthermore, it is only suitable for flow channel combinations with cooling ports located in the active region's width direction, which increases the size of the bipolar plate in the width direction, making it heavier and unfavorable for lightweight design requirements. Utility Model Content

[0005] The problem solved by this invention is to design a novel bipolar plate that can be applied to large-area, large-scale electrolytic cells, meet the requirements of bipolar plate heat dissipation and flow channel pressure drop, and at the same time meet the design requirements of lightweight design.

[0006] In a first aspect, this utility model provides a novel bipolar plate, characterized in that it comprises two identical single plates, a flow field region is provided in the center of the front side of the single plate, and a cooling water flow field region with the same flow channel arrangement as the flow field region is provided in the center of the back side of the single plate. The two single plates are welded together with their back sides facing each other to form an integral bipolar plate. The cooling water flow field region inside the bipolar plate forms a separate cooling cavity. The two ends of the bipolar plate are respectively provided with a flow channel inlet and a flow channel outlet communicating with the flow field region and the cooling cavity.

[0007] The back of the single plate is also provided with a bridge flow channel area. The bridge flow channel area is located between the flow channel inlet and the flow field area opening corresponding to its front side. The bridge flow channel area is also provided with a through flanged flow channel opening at the position corresponding to the flow field area opening. After the backs of the two single plates are welded together, the bridge flow channel area of ​​one single plate is sealed through the back of the other single plate to form a bridge channel.

[0008] The back of the single board is also provided with an inner sinking groove, which is arranged symmetrically with the center line of the bridge flow channel area relative to the length direction of the single board. The length of the inner sinking groove is less than the length of the bridge flow channel area.

[0009] The flow channel inlet includes an anode flow channel inlet, a cooling water inlet, and a cathode flow channel inlet. The cooling water inlet is located between the anode flow channel inlet and the cathode flow channel inlet. The flow channel outlet includes an anode flow channel outlet, a cooling water outlet, and an anode flow channel outlet. The cooling water outlet is located between the anode flow channel outlet and the cathode flow channel outlet.

[0010] The back of the single plate is provided with a welding step area. The welding sealing step area includes the outer periphery of the cooling water flow field area, as well as the outer periphery areas of the flow field area's inlet and outlet. At the same time, the welding step area covers the ridge surface of the bridge flow field area.

[0011] The front of the single board is provided with a sealing groove, which is located on the outer periphery of the front of the single board and surrounds the flow channel inlet and flow channel outlet that communicate with the flow field area and the cooling cavity. The sealing groove is provided with a matching sealing glue line inside.

[0012] The flow channels in the flow field region are distributed in a centrally symmetrical manner. The flow field region includes an inlet flow field, an inlet distribution flow field, a diffusion flow field, an outlet distribution flow field, and an outlet flow field. The ratio of the number of flow channel ridges in the inlet distribution flow field to the number of flow channel ridges in the inlet flow field is 1:1 to 3:1, and the ratio of the number of flow channel ridges in the diffusion flow field to the number of flow channel ridges in the inlet distribution flow field is 1:1 to 2:1.

[0013] Secondly, this utility model provides a PEM electrolytic cell, which includes any of the novel bipolar plates mentioned above.

[0014] The beneficial effects of the bipolar plate and electrolytic cell of this invention are:

[0015] By welding two identical single plates together on their backs, a bipolar plate with an independent cooling chamber is formed. The fluid flow direction in the cooling chamber is consistent with the fluid flow direction in the flow field region. This ensures the uniformity of temperature distribution and the effectiveness of heat dissipation in the flow field region during operation. It also greatly reduces the pressure drop loss in the flow channel by diverting the flow. At the same time, the inlet and outlet of the flow channel, which are connected to the flow field region and the cooling chamber, are located at both ends of the bipolar plate. This makes the bipolar plate compact and meets the design requirements for lightweight design. Attached Figure Description

[0016] Figure 1 This is an exploded view of the bipolar plate of this utility model;

[0017] Figure 2 This is a schematic diagram of the front structure of the single-layer board of this utility model;

[0018] Figure 3 This is a schematic diagram of the back structure of the single-layer board of this utility model;

[0019] Figure 4 This is a schematic diagram of the back structure of the single-layer plate of this utility model (the shaded area in the figure represents the welding step area);

[0020] Figure 5 This is a partial cross-sectional view of the bipolar plate of this utility model;

[0021] Figure 6 This is a partial cross-sectional view of the anode flow channel inlet of the bipolar plate of this utility model.

[0022] Explanation of reference numerals in the attached figures

[0023] 1. Single board; 11. Bridge flow channel area; 12. Flanged flow channel opening; 13. Inner settling tank; 14. Sealing groove; 2. Flow field area; 3. Cooling flow field area; 4. Cooling water inlet; 5. Cooling water outlet; 6. Welding step area. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0025] In this specification, identical components are represented by the same reference numerals. It should be noted that the terms "front," "rear," "left," "right," "upper," and "lower" used in the following description refer to directions in the accompanying drawings, while the terms "bottom surface," "top surface," "inner," and "outer" refer to directions towards or away from a specific component, respectively. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this specification, "multiple" means two or more.

[0026] The present application will be further described below with reference to the accompanying drawings and embodiments.

[0027] Example 1

[0028] like Figure 1 , 2 As shown, a novel bipolar plate includes two identical single plates 1. A flow field region 2 is provided in the center of the front side of the single plate 1, and a cooling water flow field region 3 with the same flow channel arrangement as the flow field region 2 is provided in the center of the back side of the single plate 1. The back sides of the two single plates 1 are connected to form an integrated bipolar plate. One side of the flow field region 2 of the bipolar plate is the anode flow field region, and the other side of the flow field region 2 of the bipolar plate is the cathode flow field region. The cooling water flow field regions of the two single plates 1 inside the bipolar plate form a separate cooling chamber. The two ends of the bipolar plate are respectively provided with a flow channel inlet and a flow channel outlet that communicate with the flow field region and the cooling chamber.

[0029] This invention utilizes two identical single-plate bipolar plates, which are connected back-to-back to form an integrated bipolar plate. This integrated structure not only minimizes contact resistance between components but also facilitates the subsequent integration and assembly of the electrolytic cell. Furthermore, the bipolar plate contains a separate cooling chamber, allowing cooling water to flow in and out. The fluid flow direction in the cooling chamber aligns with the fluid flow direction in the flow zone of the single-plate, providing primary cooling. This cooling water is not particularly demanding in terms of quality, thus reducing the amount of pure water used in the electrolytic cell and lowering operating costs. Pure water can simultaneously enter the anode and cathode flow fields on both sides of the bipolar plate. For the pure water in the anode flow field, only a small portion participates in the electrolysis reaction; the majority primarily serves to dissipate heat and evenly distribute reactants and products on the anode side. Similarly, the pure water in the cathode flow field does not participate in the electrolysis reaction but mainly serves to dissipate heat and evenly distribute reactants and products on the cathode side. Therefore, the pure water in the flow field can provide auxiliary heat dissipation. With this design, compared to existing bipolar plate designs where the cooling medium cavity is arranged on both sides of the active region and can only produce a local cooling effect, the bipolar plate of this application has excellent heat dissipation performance. Moreover, by using the cooling cavity to divide the flow, the pressure drop loss in the flow channel can be greatly reduced, making it suitable for high flow rate and high electrical density operating conditions. At the same time, the flow channel inlet and flow channel outlet, which are connected to the flow field region and the cooling cavity, are located at both ends of the bipolar plate. Compared to existing bipolar plates where the cooling port is located on both sides of the width direction of the active region, the structure of the bipolar plate of this application is more compact and can meet the design requirements of lightweight design.

[0030] Preferably, the two single plates 1 can be made of titanium plates or stainless steel plates and are manufactured by CNC machining, stamping or other methods. At the same time, the two single plates 1 that constitute an integral bipolar plate in this application have the same structure. Thus, when processing the bipolar plate, a sealing structure with the same structure can be formed on the cathode side and the anode side, avoiding the need to open two sets of molds, reducing the processing cost of the bipolar plate, and solving the problem of high processing cost of bipolar plates in the prior art.

[0031] Specifically, one end of the bipolar plate is provided with various flow channel inlets communicating with the anode-side flow field region, the cathode-side flow field region, and the cooling chamber. These flow channel inlets include an anode flow channel inlet, a cooling water inlet 4, and a cathode flow channel inlet, with the cooling water inlet 4 located between the anode and cathode flow channel inlets. The other end of the bipolar plate is provided with various flow channel outlets communicating with the anode-side flow field region, the cathode-side flow field region, and the cooling chamber. These flow channel outlets include an anode flow channel outlet, a cooling water outlet 5, and an anode flow channel outlet, with the cooling water outlet 5 located between the anode and cathode flow channel outlets. In this application, all the aforementioned flow channel inlets and outlets adopt a semi-circular opening of the same size. The flow channel inlets and outlets can also adopt square or rectangular openings. Since the flow field regions on both sides of the bipolar plate have identical structures, one of the flow field regions on each side can be defined as the anode side and the other as the cathode side, depending on the actual application. Therefore, the anode flow channel inlet and cathode flow channel inlet are defined according to the actual situation, and the corresponding anode flow channel outlet and cathode flow channel outlet are set accordingly to correspond to the aforementioned anode flow channel inlet and cathode flow channel inlet.

[0032] Specifically, such as Figure 3 As shown, the back of the single plate 1 is also provided with a bridge flow channel area 11. The bridge flow channel area 11 is a parallel flow channel formed by parallel ridges. The bridge flow channel area 11 is located between the inlet of the flow field area 2 on the front side and the opening of the flow field area 2. The bridge flow channel area 11 has a through flanged flow channel opening 12 at the position corresponding to the opening of the flow field area 2. After the back sides of the two single plates 1 are welded together, the bridge flow channel area 11 of one single plate 1 is sealed through the back side of the other single plate 1 to form a bridge channel. With the setting of this bridge channel, one single plate 1 is set as the anode side and the other single plate 1 is set as the cathode side. The fluid entering from the anode flow channel inlet must pass through the bridge channel to enter the flow field area for anode-side electrolysis reaction. The fluid after electrolysis reaction then flows out from the anode flow channel outlet through another bridge channel. The working principle of the cathode side is the same, so it will not be described in detail.

[0033] Preferably, such as Figure 2As shown, the flow channels in flow field region 2 are distributed in a centrosymmetric manner, and therefore the flow channel inlet and outlet corresponding to flow field region 2 are also distributed in a centrosymmetric manner. Flow field region 2 includes an inlet flow field, an inlet distribution flow field, a diffusion flow field, an outlet distribution flow field, and an outlet flow field connected in sequence. The inlet flow field and the inlet distribution flow field are distributed in a centrosymmetric manner with the center of the diffusion flow field and the outlet distribution flow field and outlet flow field. In this application, the inlet flow field, the inlet distribution flow field, the diffusion flow field, the outlet distribution flow field, and the outlet flow field adopt a parallel flow field composed of mutually parallel flow channel ridges. The parallel flow field has better uniformity, and at the same time, because the resistance of gas flow in the flow field is small, the pump power consumption of the parallel flow field is low. This flow field region 2 can also adopt a serpentine flow field, a mesh flow field, a point flow field, a cross flow field, or a composite flow field combining multiple different flow fields, etc.

[0034] Specifically, the ratio of the number of channel ridges in the inlet distribution flow field to the number of channel ridges in the inlet flow field is 1:1 to 3:1, and the ratio of the number of channel ridges in the diffusion flow field to the number of channel ridges in the inlet distribution flow field is 1:1 to 2:1. The inlet flow field and diffusion flow field are horizontally arranged parallel flow fields, while the inlet distribution flow field is vertically arranged parallel flow field. With this configuration, in flow field region 2, the fluid enters horizontally through the inlet flow field and is uniformly distributed, then further distributed through the vertical inlet distribution flow field, and finally enters the diffusion flow field horizontally to participate in the electrolysis reaction. This allows for both longitudinal and lateral transport of gas and water in the flow field region, improving uniformity. Simultaneously, by increasing the number of channel ridges in different flow fields, the gas and water are further diverted, effectively reducing pressure drop losses within the flow channels and also contributing to uniform distribution.

[0035] Preferably, such as Figure 3As shown, the cooling flow field region 3 is arranged in the same direction as the flow field region, along the length of the single plate 1. It also includes a sequentially connected inlet flow field, inlet distribution flow field, diffusion flow field, outlet distribution flow field, and outlet flow field. The inlet flow field and inlet distribution flow field are symmetrically distributed with respect to the vertical axis (Y-axis direction in the figure) of the diffusion flow field and the outlet distribution flow field and outlet flow field, respectively. Simultaneously, the inlet flow field and outlet flow field are directly connected to the cooling water inlet 4 and cooling water outlet 5, respectively. All flow fields in the cooling flow field region 3 adopt parallel flow fields. The inlet flow field and diffusion flow field are horizontal parallel flow fields, while the inlet distribution flow field is a vertically directed flow field. The number of channel ridges in the inlet distribution flow field is 1 to 3 times that of the inlet flow field, and the number of channel ridges in the diffusion flow field is 1 to 2 times that of the inlet distribution flow field. During operation, the cooling water in the cooling chamber enters horizontally from the inlet flow field and is then evenly distributed vertically upwards and downwards through the inlet distribution flow field before entering the horizontal diffusion flow field. Since the cooling flow field area is arranged horizontally and occupies most of the area on the back of the single panel 1, it can achieve excellent cooling effect on the front of the single panel 1. At the same time, it has low requirements for water quality and low cost.

[0036] Preferably, the back of the single plate 1 is also provided with an inner recess 13 corresponding to the bridge flow channel area 11. The inner recess 13 and the flanged flow channel opening 12 are arranged symmetrically with respect to the center line of the length direction of the single plate 1 (in the X direction in the figure). The length of the inner recess 13 is less than the length of the bridge flow channel area 11. In the length direction of the inner recess 13 (in the X direction in the figure), one end of the inner recess 13 is provided with a certain distance from the flow channel inlet or flow channel outlet, while the other end of the inner recess 13 is flush with the flanged flow channel opening 12. In the length direction of the inner recess 13, the width of the inner recess 13 is less than or equal to the width of the bridge flow channel area 11. After the backs of the two single plates 1 are welded together, the inner recess 13 on one single plate 1 is opposite to and connected to the bridge flow channel area 11 on the other single plate 1, thus increasing the flow cross-sectional area of ​​the bridge channel.

[0037] Preferably, such as Figure 4 , 5As shown, the back of the single plate 1 is also provided with a welding step area 6. This welding sealing step area 6 includes the outer periphery of the cooling water flow field area 3 and the outer periphery of the anode flow channel inlet and outlet and the cathode flow channel inlet and outlet of the flow field area 2. At the same time, the welding step area 6 covers the ridge surface of the bridge flow channel area 11. By using diffusion welding, the welding step areas 6 on the opposite backs of the two single plates 1 are welded together, thereby forming an integrated bipolar plate with excellent sealing performance. The inner groove 13 is not within the sealing welding step area 6. Since the inner groove 13 is part of the bridge channel itself, it cannot be welded. At the same time, due to the high requirements of the diffusion welding process, in order to ensure the flatness of the welding surface, the local welding area at this location is reduced, which can ensure the welding quality and further ensure the sealing effect of the bipolar plate.

[0038] Preferably, such as Figure 2 As shown, a sealing groove 14 is provided on the front side of the single plate 1. The sealing groove 14 is located on the outer periphery of the front side of the single plate 1 and surrounds the inlets and outlets of the flow channels that communicate with the flow field area 2 and the cooling cavity. A matching sealing adhesive line (not shown in the figure) is provided inside the sealing groove 14. The setting of the sealing groove 14 and the sealing adhesive line facilitates integration and assembly with other components. Since the structure of the single plate 1 constituting the bipolar plate is exactly the same, the sealing structure is also the same, which can ensure better sealing performance. At the same time, since there are spaced protrusions inside the sealing groove 14, the sealing adhesive line that cooperates with the sealing groove 14 is a double-layer sealing adhesive line. The double-layer sealing adhesive line is connected by a short adhesive line, which is located at the interval of the protrusions. By using a double-layer sealing adhesive line, a double-layer sealing effect can be achieved.

[0039] Preferably, see Figure 6 As shown in the diagram, the fluid inflow path of the anode-side plate 1 of this application is described in detail (the fluid is indicated by hollow arrows in the figure). Pure water enters from the anode channel inlet, flows downward into the bridge channel area 11 on the back of the plate 1, and then flows out through the flanged channel opening 12 of the bridge channel area 11 into the anode-side flow field area 2 on the front. This ingenious layout eliminates the need for additional components to form the bridge channel on the bipolar plate of this application, reducing processing costs. Simultaneously, the front sealing of the plate 1 remains unaffected, facilitating subsequent component integration and ensuring good sealing performance.

[0040] Example 2

[0041] This utility model provides a PEM electrolytic cell that includes the novel bipolar plate described above. Its advantages are the same as those of the bipolar plate, and will not be repeated here.

[0042] The novel bipolar plate and electrolytic cell comprising the bipolar plate of this invention have the following advantages compared with existing bipolar plates:

[0043] 1. By combining two identical single plates, three independent flow channel cavities are formed (anode flow field area, cathode flow field area, and cooling cavity). The middle cooling cavity is fed with water separately to absorb and remove most of the heat generated by the electrolytic cell. The cathode and anode flow field areas can also be fed with water to provide the necessary water volume for the electrolytic reaction, and also to remove the gas generated by the reaction and provide auxiliary heat dissipation.

[0044] 2. This new type of bipolar plate has fewer components and lower material costs. The bipolar plate adopts diffusion welding to weld the two single plates into an integrated structure, which can ensure the sealing performance of the internal cooling cavity. At the same time, the integrated design results in lower contact resistance, which facilitates the subsequent assembly of the electrolytic cell.

[0045] 3. The intermediate cooling chamber of the bipolar plate has a separate water inlet, which does not have high requirements for water quality. This can reduce the amount of pure water used in the system, reduce system costs, and at the same time, it can also play a role in diverting the flow and reducing the pressure drop loss in the flow field area.

[0046] 4. The intermediate cooling chamber of the bipolar plate is the main cooling chamber, and the hot water produced can be recycled as waste heat to improve the energy utilization rate of the system. At the same time, it can be used as insulation for the entire tank during transportation and shutdown in cold regions.

Claims

1. A novel bipolar plate, characterized in that, It includes two identical single plates. The front center of the single plate has a flow field area, and the back center of the single plate has a cooling water flow field area with the same flow channel arrangement as the flow field area. The backs of the two single plates are welded together to form an integral bipolar plate. The cooling water flow field area inside the bipolar plate forms a separate cooling chamber. The two ends of the bipolar plate are respectively provided with a flow channel inlet and a flow channel outlet that communicate with the flow field area and the cooling chamber.

2. The novel bipolar plate according to claim 1, characterized in that, The back of the single plate is also provided with a bridge flow channel area. The bridge flow channel area is located between the flow channel inlet and the flow field area opening corresponding to its front side. The bridge flow channel area is also provided with a through flanged flow channel opening at the position corresponding to the flow field area opening. After the backs of the two single plates are welded together, the bridge flow channel area of ​​one single plate is sealed through the back of the other single plate to form a bridge channel.

3. A novel bipolar plate according to claim 2, characterized in that, The back of the single board is also provided with an inner sinking groove, which is arranged symmetrically with the center line of the bridge flow channel area relative to the length direction of the single board. The length of the inner sinking groove is less than the length of the bridge flow channel area.

4. A novel bipolar plate according to claim 3, characterized in that, The flow channel inlet includes an anode flow channel inlet, a cooling water inlet, and a cathode flow channel inlet. The cooling water inlet is located between the anode flow channel inlet and the cathode flow channel inlet. The flow channel outlet includes an anode flow channel outlet, a cooling water outlet, and an anode flow channel outlet. The cooling water outlet is located between the anode flow channel outlet and the cathode flow channel outlet.

5. A novel bipolar plate according to claim 4, characterized in that, The back of the single plate is provided with a welding step area. The welding sealing step area includes the outer periphery of the cooling water flow field area, as well as the outer periphery areas of the flow field area's inlet and outlet. At the same time, the welding step area covers the ridge surface of the bridge flow field area.

6. A novel bipolar plate according to claim 5, characterized in that, The front of the single board is provided with a sealing groove, which is located on the outer periphery of the front of the single board and surrounds the flow channel inlet and flow channel outlet that communicate with the flow field area and the cooling cavity. The sealing groove is provided with a matching sealing glue line inside.

7. A novel bipolar plate according to claim 6, characterized in that, The flow channels in the flow field region are distributed in a centrally symmetrical manner. The flow field region includes an inlet flow field, an inlet distribution flow field, a diffusion flow field, an outlet distribution flow field, and an outlet flow field. The ratio of the number of flow channel ridges in the inlet distribution flow field to the number of flow channel ridges in the inlet flow field is 1:1 to 3:1, and the ratio of the number of flow channel ridges in the diffusion flow field to the number of flow channel ridges in the inlet distribution flow field is 1:1 to 2:

1.

8. A PEM electrolytic cell, characterized in that, A novel bipolar plate comprising any one of claims 1 to 7.

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