Transmission layer beneficial to gas-liquid transmission, electrolytic tank monomer and electrolytic tank

Abstract

The invention relates to a transmission layer beneficial to gas-liquid transmission, an electrolytic tank monomer and an electrolytic tank, the transmission layer comprises a transmission layer main body adopting a porous structure, one side of the transmission layer main body is provided with a first convex ridge area and a first flow channel area which are adjacently arranged, and the other side of the transmission layer main body is of a plane structure; wherein the bottom width of the first flow channel area is equal to or smaller than the opening width of the first flow channel area. A flow channel structure with a special section shape is arranged in a transmission layer, so that the thickness of the position below a flow channel in the transmission layer is reduced, oxygen generated on the two sides and below the flow channel is easier to diffuse into the flow channel, accumulation of gas on the surface of a catalyst layer is reduced, meanwhile, the thickness of the position below the flow channel is reduced, and water in the flow channel can flow towards the catalyst layer conveniently; therefore, stable supply of reactants is ensured, and the efficiency of the electrolytic cell is effectively improved.

Description

Technical Field

[0001] This invention relates to the field of electrolytic cell technology, specifically to a transport layer that facilitates gas-liquid transport, an electrolytic cell unit, and an electrolytic cell. Background Technology

[0002] In traditional PEM electrolyzers, reactants flow through the channels on the anode side of the bipolar plates, reaching the catalyst layer via the anode side of the transport layer to participate in the electrolysis reaction. The generated byproduct, oxygen, diffuses through the anode side of the transport layer to the same side of the bipolar plates and is carried away. Therefore, the anode side of the transport layer plays a crucial role in transferring electrons to the catalyst layer, transferring reactants to the catalyst layer, and removing the generated oxygen from the catalyst layer. Since PEM electrolyzers typically operate in oxygen-rich and acidic environments, the transport layer often uses corrosion-resistant porous titanium materials such as titanium fiber felt, sintered titanium, and titanium mesh. These porous materials, after sintering and other processes, have a relatively uniform overall thickness. However, when using a transport layer with this structure in an electrolyzer, more oxygen is generated at the points where the transport layer contacts the bipolar plate channels. Because the transport layer thickness at these points is relatively large, it hinders the discharge (diffusion) of oxygen into the bipolar plate channels and also impedes the transport of water from the channels into the interior of the transport layer, severely reducing the efficiency of the electrolyzer and potentially causing it to fail. Therefore, it is necessary to design a structure that facilitates gas-liquid transport within the transport layer of the electrolytic cell, so as to improve gas-liquid transport efficiency and increase the efficiency of the electrolytic cell. Summary of the Invention

[0003] To overcome the shortcomings of the prior art, the present invention provides a transport layer that facilitates gas-liquid transport, as well as an electrolytic cell and an electrolytic cell, specifically adopting the following technical solution:

[0004] A transport layer that facilitates gas-liquid transport includes a transport layer body with a porous structure. One side of the transport layer body has an adjacent first ridge region and a first flow channel region, and the other side of the transport layer body has a planar structure. The bottom width of the first flow channel region is equal to or less than the opening width of the first flow channel region.

[0005] Optionally, the cross-sectional shape of the first flow channel region can be one or more of the following: arc, rectangle, triangle, stepped, or trapezoid.

[0006] Preferably, the cross-sectional shape of the first flow channel region is triangular.

[0007] Optionally: the opening width of the first flow channel region is 0.1mm-3mm; the width of the first ridge region is 0.1mm-3mm.

[0008] Optional: The bottom width of the first flow channel region is 0mm-3mm.

[0009] Optionally, the distance between the bottom of the first flow channel region and the other side of the main body of the transport layer is 0.01 to 4.9 mm.

[0010] Optionally, the thickness of the main body of the transmission layer is 0.01 to 5 mm.

[0011] The present invention also discloses an electrolytic cell unit, which includes a bipolar plate and a transport layer, wherein the transport layer is a gas transport layer as described above, and the anode side of the bipolar plate is in close contact with the side of the transport layer body in which a first flow channel region is provided.

[0012] Optionally, the bipolar plate has a second ridge region and a second flow channel region arranged adjacent to each other on the anode side, and the second flow channel region corresponds to the first flow channel region of the transport layer body, and the second ridge region corresponds to the first ridge region of the transport layer body.

[0013] The present invention further discloses an electrolytic cell, which is composed of two or more electrolytic cell units as described above connected in series.

[0014] Beneficial effects

[0015] The technical solution of the present invention achieves the following beneficial effects:

[0016] (1) The present invention sets a flow channel structure with a special cross-sectional shape in the transport layer of the electrolytic cell. It adopts one or more combinations of arc, rectangle, triangle, stepped or trapezoidal shapes to reduce the thickness of the lower part of the flow channel in the transport layer, so that the oxygen generated on both sides and below the flow channel can diffuse into the flow channel more easily, thereby reducing the accumulation of gas on the surface of the catalyst layer. At the same time, reducing the thickness of the lower part of the flow channel is conducive to the flow of water in the flow channel to the catalyst layer, thereby ensuring a stable supply of reactants and effectively improving the efficiency of the electrolytic cell.

[0017] (2) The electrolytic cell of the present invention employs a transport layer with a flow channel structure, which achieves a stable supply of reactants during electrolysis, thereby eliminating the need for the flow channel structure of the bipolar plate. Based on the above structure, at the same thickness, the transport layer with the flow channel structure requires less raw material to be processed and manufactured, resulting in lower manufacturing costs. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the gas and current flow in the transport layer of a traditional electrolytic cell, in which... Figure 1 (a) is a schematic diagram of the gas flow in the transport layer; Figure 1 (b) is a schematic diagram of the current flow in the transport layer.

[0019] Figure 2 This is a schematic diagram of the assembly of the transmission layer with a rectangular cross-section and the bipolar plate in Embodiment 1 of the present invention, wherein... Figure 2(a) is a schematic diagram of the assembly of a bipolar plate with flow channels and a transport layer with a rectangular cross-section; Figure 2 (b) is a schematic diagram of the assembly of a channelless bipolar plate and a transmission layer with a rectangular cross-section.

[0020] Figure 3 This is a schematic diagram of the transmission layer cross-section using a triangular cross-section in Embodiment 2 of the present invention.

[0021] Figure 4 This is a schematic diagram of the transmission layer cross-section using a stepped cross-section in Embodiment 2 of the present invention.

[0022] Figure 5 This is a schematic diagram of the transmission layer cross-section using an arc-shaped cross-section in an embodiment of the present invention.

[0023] Figure 6 This is a schematic diagram of the cross-section of the transmission layer using a trapezoidal cross-section in an embodiment of the present invention.

[0024] Figure 7 This is a schematic diagram of the analysis region of the transmission layer with a rectangular cross-section in Embodiment 1 of the present invention.

[0025] Figure 8 This is a schematic diagram of the analysis region of the transport layer with a triangular cross-section in Embodiment 2 of the present invention.

[0026] Figure 9 This is a schematic diagram of the analysis region of the transmission layer with a stepped cross-section used in Embodiment 3 of the present invention.

[0027] Figure 10 This is a schematic diagram of the analysis area using a planar transport layer in the comparative example of this invention.

[0028] Figure 11 This is a schematic diagram of the current density distribution of different types of transmission layers in an embodiment of the present invention.

[0029] Figure 12 This is a schematic diagram of the liquid supply distribution of different types of transport layers in an embodiment of the present invention.

[0030] Figure 13 This is a schematic diagram of the pressure distribution of different types of transmission layers in an embodiment of the present invention.

[0031] The specific meanings of the reference numerals in the attached figures are as follows:

[0032] 1-Bipolar plate; 2-Transmission layer. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be construed as limiting the scope of protection of the present invention. It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of this application.

[0034] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings. They are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0035] 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 technical features indicated. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature.

[0036] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0037] In a traditional electrolyzer, water, as a reactant, flows through the anode side of the bipolar plate. The water passes through the anode side of the transport layer to the catalyst layer below, where it participates in electrolysis as a reactant. The resulting oxygen byproduct diffuses through the anode transport layer into the flow channel and is carried away. For example... Figure 1 As shown, in traditional electrolytic cells, the transport layer has a uniform thickness, while a flow channel structure for water flow is set on the bipolar plate. During electrolysis, the ridges on both sides of the bipolar plate flow channel are in direct contact with the transport layer. Therefore, the current distribution near the ridges in the transport layer is relatively high, meaning that more water is needed for the reaction in this area, and more oxygen is generated there. Furthermore, water, as a reactant, generally seeps downwards from the bipolar plate flow channel into the transport layer first, and then diffuses to both sides. However, because the oxygen generation rate near the ridges in the transport layer is faster, and the distance the gas below the ridges travels to the flow channel is longer than that below the flow channel, gas tends to accumulate below the ridges more easily. Oxygen cannot be quickly expelled, and the gas occupies the internal space of the transport layer pores, hindering water transport and reducing the reaction area, thus decreasing the effective reaction area. Based on the above analysis, it can be seen that because the gas and liquid transport directions are opposite in traditional electrolytic cells, they interfere with each other. Therefore, effectively promoting the expulsion of gas below the ridges plays a crucial role in improving the performance of the electrolytic cell.

[0038] Specifically, such as Figure 2-10 As shown in the illustration, this application specifically discloses a transport layer that facilitates gas-liquid transport. It includes a transport layer body with a porous structure, preferably made of metals such as titanium or stainless steel. One side of the transport layer body has an adjacently arranged first ridge region and a first flow channel region, while the other side of the transport layer body has a planar structure. The bottom width of the first flow channel region is equal to or less than the opening width of the first flow channel region. It should be understood that this application essentially relocates the flow channel structure, either entirely or partially, from the original bipolar plate to the transport layer. By setting a flow channel structure with a special cross-sectional shape on the transport layer, the thickness of the transport layer below the bipolar plate flow channel is reduced. This allows oxygen generated on both sides and below the flow channel to diffuse more easily into the flow channel, thereby reducing gas accumulation inside the transport layer. Furthermore, reducing the thickness of the transport layer below the flow channel also facilitates faster water flow to both sides of the flow channel, ensuring a stable supply of reactants and effectively improving the efficiency of the electrolyzer.

[0039] The embodiments of this application, through analysis of the structure of existing electrolytic cells, reveal that during the current distribution process from the bipolar plate to the transport layer, the closer the transport layer is to the center of the bipolar plate channel, the smaller the current that can be distributed at the corresponding position in the transport layer. This means that the required thickness of the transport layer at that position can be smaller. Simultaneously, regarding the mechanical support performance of the transport layer, the closer the transport layer is to the center of the bipolar plate channel, the lower the mechanical support effect at that position, meaning that the required thickness of the transport layer at that position can be reduced without affecting the overall mechanical support of the transport layer. Therefore, the embodiments of this application, by reducing the thickness of the transport layer at the position corresponding to the bipolar plate channel, reduce the distance that gas diffuses from the position corresponding to the bipolar plate ridge in the transport layer to the bipolar plate channel region. Simultaneously, it also reduces the transport distance of water in the bipolar plate channel to the transport layer below the ridge, thereby preventing gas accumulation in the transport layer below the bipolar plate ridge.

[0040] More specifically, in order to reduce the thickness of the bipolar plate flow channel in the transmission layer, this embodiment takes into account the different ways of reducing the thickness of the corresponding position of the transmission layer, such as direct reduction, step reduction, and smooth reduction. The cross-sectional shape of the first flow channel region of the transmission layer in this application adopts one or more combinations of arc shape, rectangle, triangle, stepped shape or trapezoid.

[0041] Furthermore, such as Figure 2-6 As shown, in this application, the opening width b of the first flow channel region is 0.1mm-3mm; the surface width a of the first ridge region is 0.1mm-3mm. It should be noted that the width dimensions of the first flow channel region and the first ridge region can be adjusted according to the overall size of the transmission layer and the density design of the flow channels. Generally, the larger the size of the transmission layer, the larger the width dimension of the first flow channel region; the denser the flow channel design, the smaller the width dimension of the first ridge region.

[0042] More specifically, in this embodiment, the bottom width f of the first flow channel region is preferably 0mm-3mm. It should be understood that the bottom width of the first flow channel region should be determined based on its opening width, and its bottom width should not exceed its opening width. This structure allows for a greater volume of water near the ridge surface of the transport layer (where current is distributed more), while the volume of water closer to the bottom of the flow channel is smaller (where current is distributed less). This structure effectively ensures the supply of reactants during electrolysis and improves electrolysis efficiency. Furthermore, the distance c between the bottom of the first flow channel region and the other side of the transport layer body (near the catalyst layer) is 0.01-4.9mm. The thickness d of the transport layer body is 0.01-5mm.

[0043] Example 1:

[0044] like Figure 2 and Figure 7 As shown, this embodiment 1 discloses a transport layer that facilitates gas-liquid transport, which includes a transport layer body with a porous structure. One side of the transport layer body is provided with an adjacent first ridge region and a first flow channel region, and the other side has a planar structure. Preferably, in this embodiment 1, the cross-sectional shape of the first flow channel region is rectangular.

[0045] The surface width 'a' of the first ridge region and the opening width 'b' of the first flow channel region in the main body of the transmission layer are both set to 1 mm. The thickness 'd' of the main body of the transmission layer is 0.2 mm, and the depth 'e' of the first flow channel region is 0.1 mm.

[0046] Example 2:

[0047] like Figure 3 and Figure 8 As shown, this embodiment 2 discloses a transport layer that facilitates gas-liquid transport, which includes a transport layer body with a porous structure. One side of the transport layer body is provided with an adjacent first ridge region and a first flow channel region, and the other side has a planar structure. Preferably, in this embodiment 2, the cross-sectional shape of the first flow channel region is triangular.

[0048] The surface width 'a' of the first ridge region and the opening width 'b' of the first flow channel region in the main body of the transmission layer are both set to 1 mm. The thickness 'd' of the main body of the transmission layer is 0.2 mm, and the depth 'e' of the first flow channel region is 0.1 mm.

[0049] Example 3:

[0050] like Figure 4 and Figure 9As shown, this embodiment 3 discloses a transport layer that facilitates gas-liquid transport, which includes a transport layer body with a porous structure. One side of the transport layer body is provided with an adjacent first ridge region and a first flow channel region, and the other side has a planar structure. Preferably, in this embodiment 3, the cross-sectional shape of the first flow channel region is stepped.

[0051] The surface width 'a' of the first ridge region and the maximum opening width 'b' of the first flow channel region in the main body of the transmission layer are both set to 1 mm. The thickness 'd' of the main body of the transmission layer is 0.2 mm, the maximum depth 'e' of the first flow channel region is 0.1 mm, the thickness of each step decreases by 0.05 mm, and the width of one side of the middle step is 0.25 mm.

[0052] Comparative example:

[0053] like Figure 10 As shown, this comparative example discloses a transport layer, which includes a flat transport layer body. The anode side of the corresponding bipolar plate has ridges and channels. The ridges of the bipolar plate are 1 mm wide, and the channel openings are 1 mm wide. The ridges and channels are spaced apart. The thickness of the transport layer body is 0.2 mm.

[0054] This application analyzes the performance of the flat, triangular, rectangular, and stepped transport layers used in the above embodiments when applied to electrolytic cells.

[0055] Since the flow channels of the transport layer in each embodiment are symmetrical structures, the analysis region of this application is half ridge region and half flow channel region. The ridges of the transport layer contact the ridges / planes of the bipolar plate. The ridges in the transport layer are responsible for power supply, and the current is conducted through the transport layer to the underlying catalyst layer, such as... Figure 11 As shown, it is a comparison diagram of the current density of the catalyst layer (lower surface of the transport layer) corresponding to the analysis area. 100% is the maximum value of the current density of the planar transport layer at each position, that is, the current density at the leftmost position in the figure. The other positions are based on this.

[0056] Depend on Figure 11 It can be seen that all types of transport layers exhibit high current density at the ridge positions, while the current density decreases rapidly after transitioning to the flow channel. The rectangular cross-section transport layer shows the largest decrease, followed by the stepped cross-section, while the triangular cross-section and the flat cross-section transport layer are closest. Through integration, the total current density of the triangular, stepped, and rectangular cross-section transport layers is 98.9%, 91.0%, and 87.6% of that of the flat cross-section, respectively. In summary, compared to the flat cross-section, the triangular cross-section has only a 1.1% reduction in total current density, and its corresponding electrolytic cell exhibits the best current density performance.

[0057] Further analysis reveals that the ridges of the transport layer contact the ridges / planes of the bipolar plate, and the flow channels of the transport layer contact the flow channels / planes of the bipolar plate. The flow channels of the transport layer are used for liquid supply, allowing liquid to be transported to the underlying catalyst layer. For example... Figure 12 As shown, it is a comparison chart of the liquid supply of the catalyst layer (lower surface of the transport layer) corresponding to the analysis area. 100% is the maximum value of the liquid supply capacity of the flat plate transport layer at each position, that is, the liquid supply at the rightmost position. The other positions are based on this.

[0058] Depend on Figure 12 It can be seen that all types of transport layers exhibit a high current density at the flow channel location, followed by a rapid decrease in liquid supply after transitioning to the ridge location. Since the flat plate type has the greatest thickness at the flow channel location, it has the smallest liquid supply at that location compared to other types of transport layers. The rectangular type has the largest liquid supply, followed by the stepped type, and the triangular type has the smallest, but the liquid supply of all the aforementioned types is greater than that of the flat plate type. Through integral calculations, it was found that the total current density of the triangular, stepped, and rectangular cross-section transport layers is 136%, 171%, and 205% of that of the flat plate type, respectively, showing a very significant increase.

[0059] In the case of gas transport, the gas flows into the transport layer channel in the opposite direction to the liquid flow. The ridges of the transport layer contact the ridges / planes of the bipolar plate, and the bipolar plate applies pressure to the transport layer. This pressure is then conducted through the transport layer to the lower catalyst layer, such as... Figure 13 As shown, it is a pressure comparison diagram of the catalyst layer (lower surface of the transport layer) corresponding to the analysis area. 100% is the maximum pressure of the flat plate transport layer at each position, that is, the pressure at the leftmost position. The pressure at other positions is based on this.

[0060] Depend on Figure 13 It can be seen that different types of transport layers all show a trend of gradually decreasing pressure from the center of the ridge to the center of the channel. The pressure is highest at the center of the ridge, while it is relatively uniform at other locations on the ridge. The pressure drops rapidly after transitioning to the center of the channel. The pressure distribution of the triangular, stepped, and flat types is relatively similar, while the pressure drop is more obvious at the transition position of the rectangular type from the ridge to the channel.

[0061] Furthermore, by analyzing the volume of the transmission layer in the above embodiments and comparative examples, it was found that compared with the flat plate transmission layer, the triangular, stepped, and rectangular cross-section transmission layers can save 12.5%, 18.8%, and 18.8% of materials, respectively.

[0062] In summary, the results show that, compared to a flat transport layer, the transport layers with different shaped channels in this embodiment can significantly save material and significantly improve liquid supply without significantly reducing the total current density. Furthermore, due to the reduced thickness at the channel locations, channels of different shapes can all significantly improve gas-liquid transport capacity.

[0063] Furthermore, this application also discloses an electrolytic cell unit, which includes a bipolar plate and a transport layer, wherein the transport layer adopts a gas transport layer as described in the above embodiment, and the anode side of the bipolar plate is closely attached to the side of the transport layer body in which a first flow channel region is provided.

[0064] It should be noted that in this embodiment, a second ridge region and a second flow channel region may be provided adjacently on the anode side of the bipolar plate, and the second flow channel region corresponds to the first flow channel region of the transport layer body, and the second ridge region corresponds to the first ridge region of the transport layer body. The above structure can retain the flow channel of the bipolar plate to increase the liquid supply capacity. However, in this embodiment, the flow channel of the bipolar plate can also be eliminated to reduce the processing difficulty and assembly difficulty. It should be emphasized that in this embodiment, when a second flow channel region is provided on the anode side of the bipolar plate, when the first flow channel region is provided on the transport layer body, it should be ensured that the sum of the opening width of the adjacent first flow channel region and the surface width of the first ridge region on the transport layer body is the same as the sum of the opening width of the adjacent second flow channel region and the surface width of the second ridge region on the bipolar plate. Preferably, the difference between the surface opening width of the adjacent first ridge region on the transport layer body and the surface width of the second ridge region on the bipolar plate is within ±1 mm.

[0065] It should be understood that the flow channels of the transport layer in this application embodiment can be processed by rolling, etching, scraping, etc., and the specific method can be selected according to actual needs. After the transport layer is processed, before assembly, surface treatment steps such as polishing, pickling, platinum (Pt) plating, iridium (Ir) plating, and hydrophilic / hydrophobic modification can be performed on the surface of the transport layer, which will not be described in detail here.

[0066] Furthermore, this application also discloses an electrolytic cell, which is composed of two or more electrolytic cell units as described above connected in series.

[0067] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A transport layer that facilitates gas-liquid transport, characterized in that, The system includes a transmission layer body with a porous structure. One side of the transmission layer body has a first ridge region and a first flow channel region arranged adjacent to each other, and the other side of the transmission layer body has a planar structure. The bottom width of the first flow channel region is equal to or less than the opening width of the first flow channel region.

2. The transport layer according to claim 1, characterized in that, The cross-sectional shape of the first flow channel region adopts one or more combinations of circular arc, rectangle, triangle, stepped or trapezoid.

3. The transport layer according to claim 1, characterized in that, The cross-sectional shape of the first flow channel region is triangular.

4. The transport layer according to claim 1, characterized in that, The opening width of the first flow channel region is 0.1mm-3mm; the width of the first ridge region is 0.1mm-3mm.

5. The transport layer according to claim 1, characterized in that, The bottom width of the first flow channel region is 0mm-3mm.

6. The transport layer according to claim 1, characterized in that, The distance between the bottom of the first flow channel region and the other side of the main body of the transport layer is 0.01 to 4.9 mm.

7. The transport layer according to claim 6, characterized in that, The thickness of the main body of the transmission layer is 0.01 to 5 mm.

8. A single electrolytic cell, comprising bipolar plates and a transport layer, characterized in that, The transport layer is the transport layer as described in any one of claims 1-7, and the anode side of the bipolar plate is in close contact with the side of the transport layer body in which the first flow channel region is provided.

9. The single electrolytic cell according to claim 8, characterized in that, The bipolar plate has a second ridge region and a second flow channel region arranged adjacent to each other on the anode side, and the second flow channel region corresponds to the first flow channel region of the transport layer body, and the second ridge region corresponds to the first ridge region of the transport layer body.

10. An electrolytic cell, characterized in that, The electrolytic cell is composed of two or more electrolytic cell units as described in claim 8 or 9 connected in series.

Images