Bipolar plate and electrolytic cell

Abstract

The present disclosure provides a bipolar plate and an electrolytic cell, wherein the bipolar plate includes: a water inlet area, a water outlet area, and a flow field area connecting the water inlet area and the water outlet area, and the reaction water in the water inlet area flows through the flow field area and the water outlet area in sequence; a flow channel is provided in the flow field area, and the flow channel has a first end and a second end along the flow direction of the reaction water; in the direction perpendicular to the bipolar plate, the cross-sectional area of ​​the first end of the flow channel is S1, and the cross-sectional area of ​​the second end of the flow channel is S2, wherein S1<S2. The flow channel design in the present disclosure matches the gradient water vapor distribution field where bubbles gradually accumulate, so as to improve the uniformity in the flow direction, further reduce concentration polarization, and improve the electrolysis efficiency.

Description

Technical Field

[0001] The present disclosure relates to the technical field of hydrogen production by electrolysis of water, and in particular to a bipolar plate and an electrolytic cell. Background Art

[0002] At present, water electrolysis is widely used as a low-cost method for producing hydrogen. Taking the proton exchange membrane (PEM) electrolyzer as an example, as a device that converts electrical energy into hydrogen energy, it uses proton exchange membrane as electrolyte, which has the advantages of small size and wide power operating range. Among them, the bipolar plate is the key component of the electrolyzer, which mainly plays the role of mass transfer, conductivity and fixed support.

[0003] The water supply method of the existing electrolyzer generally adopts anode water flow, that is, on the anode side of the bipolar plate, deionized water is supplied from the inlet, and circulating water and generated oxygen flow out from the outlet together.

[0004] In the flow field area of ​​the bipolar plate, the oxygen produced by electrolysis gradually accumulates along the direction of the flow channel, resulting in a gradient distribution pattern of materials in the field, that is, in the front end area, the oxygen accumulation degree is low, the bubbles are small, and the transmission resistance to the reactant water is low, so no concentration polarization will be generated; while in the rear end area, since the oxygen at the front end also flows here, it is easy to accumulate to form large bubbles, thereby generating larger concentration polarization, which will significantly affect the hydrogen production rate of the electrolyzer and aggravate the attenuation of the equipment life. Summary of the invention

[0005] The embodiments of the present disclosure at least provide a bipolar plate and an electrolytic cell to reduce concentration polarization and improve electrolysis efficiency.

[0006] In a first aspect, an embodiment of the present disclosure provides a bipolar plate, comprising: a water inlet region, a water outlet region, and a flow field region connecting the water inlet region and the water outlet region, wherein reaction water in the water inlet region flows through the flow field region and the water outlet region in sequence;

[0007] A flow channel is arranged in the flow field area, and the flow channel has a first end and a second end along the flow direction of the reaction water; in a direction perpendicular to the bipolar plate, the cross-sectional area of ​​the first end of the flow channel is S1, and the cross-sectional area of ​​the second end of the flow channel is S2, wherein S1<S2.

[0008] In a possible implementation manner, there are a plurality of flow channels, and the plurality of flow channels are arranged in parallel and perpendicular to the flow direction of the reaction water.

[0009] In a possible implementation manner, the cross-sectional width of the first end of each of the flow channels is W1, and the cross-sectional width of the second end of each of the flow channels is W2, wherein W1<W2.

[0010] In a possible implementation manner, a cross-sectional depth of the first end of each of the flow channels is D1, and a cross-sectional depth of the second end of each of the flow channels is D2, wherein D1<D2.

[0011] In a possible implementation, the flow channel includes a first sub-flow channel and a second sub-flow channel;

[0012] The first sub-flow channel is connected to the second sub-flow channel in the flow direction of the reaction water.

[0013] In a possible implementation manner, there are a plurality of first sub-channels, and a plurality of second sub-channels, and the plurality of first sub-channels are arranged in parallel and perpendicular to the flow direction of the reaction water, and the plurality of second sub-channels are arranged in parallel and perpendicular to the flow direction of the reaction water;

[0014] Two adjacent first sub-flow channels are connected to a corresponding one of the second sub-flow channels.

[0015] In a possible implementation manner, the number of the first sub-flow channels is N1, and the number of the second sub-flow channels is N2, wherein N1>N2.

[0016] In a possible implementation manner, a cross-sectional width of the first sub-channel is W11, and a cross-sectional width of the second sub-channel is W21, wherein W11<W21.

[0017] In a possible implementation manner, a cross-sectional depth of the first sub-channel is D11, and a cross-sectional depth of the second sub-channel is D21, wherein D11<D21.

[0018] In a possible implementation manner, the flow channel includes a third sub-flow channel and a fourth sub-flow channel, and a first distribution area is provided between the third sub-flow channel and the fourth sub-flow channel;

[0019] The third sub-flow channel, the first distribution area and the fourth sub-flow channel are connected in the flow direction of the reaction water.

[0020] In a possible implementation manner, there are a plurality of the third sub-channels, there are a plurality of the fourth sub-channels, the plurality of the third sub-channels are arranged in parallel in a direction perpendicular to the flow direction of the reaction water, and the plurality of the fourth sub-channels are arranged in parallel in a direction perpendicular to the flow direction of the reaction water;

[0021] Each of the third sub-flow channels is connected to at least one of the fourth sub-flow channels through the first distribution area.

[0022] In a possible implementation manner, the number of the third sub-flow channels is N3, and the number of the fourth sub-flow channels is N4, wherein N3>N4.

[0023] In a possible implementation manner, a cross-sectional width of the third sub-channel is W31, and a cross-sectional width of the fourth sub-channel is W41, wherein W31<W41.

[0024] In a possible implementation manner, a cross-sectional depth of the third sub-channel is D31, and a cross-sectional depth of the fourth sub-channel is D41, wherein D31<D41.

[0025] In a possible implementation, the water inlet region is provided with a water inlet and a second distribution region for the reaction water to flow in, the water outlet region is provided with a water outlet and a third distribution region for the reaction water to flow out, and the second distribution region and the third distribution region are centrally symmetrically arranged;

[0026] The second distribution area is arranged between the water inlet and the first end of the flow channel, and the third distribution area is arranged between the second end of the flow channel and the water outlet.

[0027] In a second aspect, the present disclosure further provides an electrolytic cell, comprising: a bipolar plate as described in any one of the first aspect and various embodiments thereof.

[0028] The above-mentioned bipolar plate and electrolytic cell are adopted, and the bipolar plate includes a flow field area connecting the water inlet area and the water outlet area, and the reaction water in the water inlet area flows through the flow field area and the water outlet area in sequence; a flow channel is arranged in the flow field area here, and the flow channel has a first end and a second end along the flow direction of the reaction water; in the direction perpendicular to the bipolar plate, the cross-sectional area of ​​the first end of the flow channel is smaller than the cross-sectional area of ​​the second end of the flow channel. In other words, the present disclosure adopts a flow channel design with a smaller flow area for the first end of the flow channel (corresponding to the front end area of ​​the flow field), and adopts a flow channel design with a larger flow area for the second end of the flow channel (corresponding to the rear end area of ​​the flow field). Such a flow channel design is matched with the gradient water vapor distribution field where bubbles gradually accumulate, thereby improving the uniformity in the flow direction, further reducing concentration polarization, and improving the electrolysis efficiency.

[0029] Other advantages of the present disclosure will be explained in more detail in conjunction with the following description and drawings.

[0030] It should be understood that the above description is only an overview of the technical solution of the present disclosure, so that the technical means of the present disclosure can be generally understood and then implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present disclosure more obvious and easy to understand, the specific implementation methods of the present disclosure are specifically described below with examples. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the drawings required for use in the embodiments will be briefly introduced below. The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and are used together with the specification to illustrate the technical solutions of the present disclosure. It should be understood that the drawings only illustrate certain embodiments of the present disclosure and therefore should not be regarded as limiting the scope of protection. For ordinary technicians in this field, other relevant drawings can be obtained based on these drawings without creative work. Moreover, the same reference numerals are used to represent the same components throughout the drawings. In the drawings:

[0032] Figure 1 A front view of the anode side of a bipolar plate provided by an embodiment of the present disclosure is shown;

[0033] Figure 2 A front view of the anode side of another bipolar plate provided by an embodiment of the present disclosure is shown;

[0034] Figure 3a A front view of the anode side of another bipolar plate provided by an embodiment of the present disclosure is shown;

[0035] Figure 3b Shows Figure 3a A partial view of the bipolar plate shown;

[0036] Figure 3c Shows Figure 3b A cross-sectional view and corresponding partial views of the bipolar plate shown;

[0037] Figure 3d Shows Figure 3b Another cross-sectional view and corresponding partial view of the bipolar plate shown;

[0038] Figure 4 A front view of the anode side of another bipolar plate provided by an embodiment of the present disclosure is shown.

[0039] Illustration Description:

[0040] 10-water inlet area; 20-water outlet area; 30-flow field area; 40-first distribution area; 11-water inlet; 12-second distribution area; 21-water outlet; 22-third distribution area; 31-flow channel; 31a-first end; 31b-second end; 51-first hydrogen outlet; 52-second hydrogen outlet; 311-first sub-flow channel; 312-second sub-flow channel; 313-third sub-flow channel; 314-fourth sub-flow channel. DETAILED DESCRIPTION

[0041] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0042] In the description of the embodiments of the present disclosure, it should be understood that terms such as "including" or "having" are intended to indicate the presence of the disclosed features, numbers, steps, behaviors, components, parts, or a combination thereof in the specification, and do not exclude the possibility of the presence of one or more other features, numbers, steps, behaviors, components, parts, or a combination thereof.

[0043] Unless otherwise specified, “ / ” means or. For example, A / B can mean A or B. The “and / or” in this article is merely a way to describe the association relationship of associated objects, indicating that three relationships can exist. For example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone.

[0044] The terms "first", "second", etc. are used only to distinguish the same or similar technical features for the convenience of description, and should not be understood as indicating or implying the relative importance or quantity of these technical features. Thus, the features defined by "first", "second", etc. may explicitly or implicitly include one or more of such features. In the description of the embodiments of the present disclosure, unless otherwise specified, the term "plurality" means two or more than two.

[0045] Research has found that the water supply method of existing electrolyzers generally adopts anode water flow, that is, on the anode side of the bipolar plate, deionized water is supplied from the inlet, and circulating water and generated oxygen flow out from the outlet together.

[0046] In the flow field area of ​​the bipolar plate, the oxygen produced by electrolysis gradually accumulates along the direction of the flow channel, resulting in a gradient distribution pattern of materials in the field, that is, in the front end area, the oxygen accumulation degree is low, the bubbles are small, and the transmission resistance to the reactant water is low, so no concentration polarization will be generated; while in the rear end area, since the oxygen at the front end also flows here, it is easy to accumulate to form large bubbles, thereby generating larger concentration polarization, which will significantly affect the hydrogen production rate of the electrolyzer and aggravate the attenuation of the equipment life.

[0047] The existing structure only focuses on the flow uniformity in the cross-sectional direction of the flow field area of ​​the bipolar plate, and does not consider the upstream and downstream flow unevenness caused by the bubble accumulation effect in the water flow direction. Therefore, the existing flow field design does not match the gradient water vapor distribution field where bubbles gradually accumulate.

[0048] In order to at least partially solve one or more of the above-mentioned problems and other potential problems, the present disclosure provides a bipolar plate and an electrolytic cell, which adds consideration of uniformity in the flow direction on the basis of cross-sectional flow uniformity, thereby further reducing concentration polarization, improving electrolysis efficiency, and avoiding the increased attenuation of the electrolytic cell life.

[0049] To facilitate understanding of the present disclosure, the specific structure of the above-mentioned bipolar plate will be explained in conjunction with the following embodiments.

[0050] Embodiment 1

[0051] Taking into account that in the related art, due to the continuous reaction, oxygen bubbles will accumulate on the anode side in the flow field area from the front end area to the rear end area of ​​the bipolar plate, and the water-oxygen volume flow rate in the front end area is smaller than that in the rear end area. Especially in the rear end area, since the oxygen at the front end also flows here, it is easy to accumulate to form large bubbles, thereby generating a large concentration polarization. Based on this, the embodiment of the present disclosure provides a gradient flow channel design scheme for the anode side, so that the flow area of ​​the flow channel corresponding to the front end area is smaller, while the flow area of ​​the flow channel corresponding to the rear end area is larger, thereby achieving uniformity in the flow direction.

[0052] like Figure 1 An exemplary bipolar plate structure schematic diagram (corresponding to the anode side front view) is shown, the bipolar plate mainly includes: a water inlet area 10, a water outlet area 20, and a flow field area 30 connecting the water inlet area 10 and the water outlet area 20, and the reaction water of the water inlet area 10 flows through the flow field area 30 and the water outlet area 20 in sequence; wherein:

[0053] A flow channel 31 is provided in the flow field area 30, and the flow channel 31 has a first end 31a and a second end 31b along the flow direction of the reaction water; in a direction perpendicular to the bipolar plate, the cross-sectional area of ​​the first end 31a of the flow channel 31 is S1, and the cross-sectional area of ​​the second end 31b of the flow channel 31 is S2, wherein S1<S2.

[0054] Here, the first end 31a of the flow channel 31 corresponds to the front end area closer to the water inlet area 10, and the second end 31b of the flow channel 31 corresponds to the rear end area closer to the water outlet area 20. In other words, for the front section area, since the amount of oxygen generated is relatively small, it is not easy to produce concentration polarization, and the overall flow speed of the water vapor in this section is slow. The embodiment of the present disclosure can use a narrow flow channel with a smaller flow area (corresponding to the cross-sectional area of ​​the first end 31a) in the front end area; similarly, for the rear section area, since the front end oxygen will also flow through here, resulting in local bubble accumulation, if it is not removed in time, it will lead to insufficient raw water supply of the catalyst (CL) layer, resulting in extremely large concentration polarization. Therefore, a wide flow channel with a larger flow area (corresponding to the cross-sectional area of ​​the second end 31b) can be used in the rear end area.

[0055] The sizes of the two cross-sectional areas can be determined by changing the cross-sectional width, or by changing the cross-sectional depth, or by changing both the cross-sectional width and the cross-sectional depth. The embodiments of the present disclosure do not impose any specific restrictions on this.

[0056] In an actual bipolar plate structure, the water inlet area 10, the water outlet area 20, and the flow field area 30 provided with the flow channel 31 may be provided on the bipolar plate substrate. In addition, a sealing line is provided around the substrate to make the entire bipolar plate in a relatively sealed state.

[0057] Embodiment 2

[0058] like Figure 1 As shown, there are multiple flow channels 31 in the bipolar plate provided in the embodiment of the present disclosure, and the multiple flow channels 31 are arranged in parallel in a direction perpendicular to the flow direction of the reaction water.

[0059] Here, the cross-sectional width of the first end 31 a of each of the flow channels 31 is W1 (not shown), and the cross-sectional width of the second end 31 b of each of the flow channels 31 is W2 (not shown), wherein W1<W2.

[0060] It is known that the embodiment of the present disclosure provides a flow channel design that is narrow in front and wide in the back. Since the gas generated by the electrolysis reaction in the flow field area 30 gradually accumulates along the flow direction, a narrow flow channel is used in the front area, and a wide flow channel is used in the rear area to provide an escape space for bubbles escaping from the catalyst layer, thereby preventing bubbles from accumulating on the surface of the catalyst layer, thereby reducing mass transfer polarization. The specific design structure can be determined in combination with actual conditions.

[0061] For example, a design structure in which the cross-sectional width changes gradually from the first end 31a of the flow channel 31 to the second end 31b of the flow channel 31 may be adopted (eg Figure 1For example, a flow channel structure of the example may be adopted, and a design structure in which the cross-sectional width changes uniformly from the first end 31a of the flow channel 31 to the second end 31b of the flow channel 31 (such as a trumpet-shaped flow channel structure) may be adopted. Other design structures may also be adopted, and the embodiments of the present disclosure do not make specific restrictions on this.

[0062] It should be noted that Figure 1 The number of flow channels in the example is only a specific example. In actual applications, the specific number of flow channels can be determined in combination with the width of the bipolar plate and the demand for hydrogen production by electrolysis of water. No specific limitation is made here.

[0063] Embodiment 3

[0064] like Figure 2 As shown, there are also multiple flow channels 31 in the bipolar plate, and the multiple flow channels 31 are arranged in parallel and perpendicular to the flow direction of the reaction water.

[0065] Here, the cross-sectional depth of the first end 31 a of each of the flow channels 31 is D1 (not shown), and the cross-sectional depth of the second end 31 b of each of the flow channels 31 is D2 (not shown), wherein D1<D2.

[0066] It can be seen that the embodiment of the present disclosure provides a flow channel design that is shallow in the front and deep in the back. Since the gas generated by the electrolysis reaction in the flow field area 30 gradually accumulates along the flow direction, a shallow flow channel with a relatively small depth of the flow channel 31 is used in the front end area, and a deep flow channel with a relatively large depth of the flow channel 31 is used in the rear end area. This can provide an escape space for bubbles escaping from the catalyst layer, avoid the accumulation of bubbles on the surface of the catalyst layer, and thus reduce mass transfer polarization. The specific design structure can be determined in combination with actual conditions.

[0067] For example, a design structure in which the cross-sectional depth changes gradually from the first end 31a of the flow channel 31 to the second end 31b of the flow channel 31 may be adopted (eg Figure 2 The example flow channel structure) may also adopt other design structures, and the embodiments of the present disclosure do not make specific limitations on this.

[0068] It should be noted that Figure 2 The number of flow channels in the example is only a specific example. In actual applications, the specific number of flow channels can be determined in combination with the width of the bipolar plate and the demand for hydrogen production by electrolysis of water. No specific limitation is made here.

[0069] Embodiment 4

[0070] The embodiment of the present disclosure also provides a flow channel design structure with multiple sub-flow channels, where the sub-flow channels can be two, three, four, etc., which can be determined in combination with actual application requirements in practical applications. Next, the flow channel design structure with two sub-flow channels will be described in detail.

[0071] like Figure 3a As shown, it is a schematic diagram of an exemplary bipolar plate structure (corresponding to the front view of the anode side). In addition to the water inlet area 10, the water outlet area 20 and the flow field area 30, the flow channel 31 arranged in the flow field area 30 includes two sub-channels (i.e., the first sub-channel 311 and the second sub-channel 312); in the flow direction of the reaction water, the first sub-channel 311 and the second sub-channel 312 are connected. In other words, the two sub-channels are directly connected.

[0072] Among them, there are multiple first sub-channels 311 and multiple second sub-channels 312, multiple first sub-channels 311 are arranged in parallel and perpendicular to the flow direction of the reaction water, and multiple second sub-channels 312 are arranged in parallel and perpendicular to the flow direction of the reaction water; two adjacent first sub-channels 311 are connected to a corresponding second sub-channel 312.

[0073] In actual applications, since the gas generated by the electrolytic reaction in the flow field area 30 gradually accumulates along the flow direction, the flow channels in the front flow field area are relatively densely arranged, corresponding to a larger number N1 of first sub-channels 311, while the flow channels in the rear flow field area are relatively sparsely arranged, corresponding to a smaller number N2 of second sub-channels 312.

[0074] The specific number of the two sub-flow channels can be determined based on actual application requirements and is not specifically limited here.

[0075] The cross-sectional width of the first sub-channel 311 in the embodiment of the present disclosure is W11, and the cross-sectional width of the second sub-channel 312 is W21, wherein W11<W21. The cross-sectional widths of the two sub-channels can be determined based on actual application requirements and are not specifically limited herein.

[0076] The cross-sectional depth of the first sub-channel 311 in the embodiment of the present disclosure is D11, and the cross-sectional depth of the second sub-channel 312 is D21, wherein D11<D21. The cross-sectional depths of the two sub-channels can be determined based on actual application requirements and are not specifically limited herein.

[0077] In order to further understand the flow channel design of the twin flow channels provided in the embodiment of the present disclosure, Figure 3b to Figure 3d Let's expand the explanation.

[0078] like Figure 3b for Figure 3a A partial view I of the front view shown, the direction pointed by the arrow is the flow direction of the reaction water; Figure 3c As shown, it is a cross-sectional view AA and a partial view II of the first sub-channel 311; Figure 3d , a cross-sectional view BB and a partial view III thereof are shown for the second sub-channel 312 .

[0079] Here, the number N1 of the first sub-channels 311 can be determined by the interval period T1 of the first sub-channels 311. The larger T1 is, the smaller N1 is. Conversely, the smaller T1 is, the larger N1 is. In practical applications, the value range of T1 here can be [1,2] mm; the cross-sectional width W11 of the first sub-channel 311 can be determined based on actual application requirements. For example, the cross-sectional width W11 can be set within the value range of [30%, 70%] of T1; the cross-sectional depth D11 of the first sub-channel 311 can also be determined based on actual application requirements. For example, the cross-sectional depth D11 can be set within the value range of [50%, 60%] of W11.

[0080] Similarly, the number N2 of the second sub-channels 312 can be determined by the interval period T2 of the second sub-channels 312. The larger T2 is, the smaller N2 is. Conversely, the smaller T2 is, the larger N2 is. In practical applications, the value range of T2 here can be [3,6] mm; the cross-sectional width W21 of the second sub-channel 312 can be determined based on actual application requirements. For example, the cross-sectional width W21 can be set within the value range of [40%, 60%] of T2; the cross-sectional depth D21 of the second sub-channel 312 can also be determined based on actual application requirements. For example, the cross-sectional depth D21 can be set within the value range of [20%, 30%] of W21.

[0081] For the bipolar plate provided in the embodiment of the present disclosure, the amount of oxygen generated in the front end region (corresponding to the first sub-channel 311) is relatively small, and concentration polarization is not easy to occur. In addition, the overall flow speed of water vapor in this section is relatively slow, so a fine channel with a high ridge-groove ratio is adopted, which can bring the following technical advantages:

[0082] 1. Increase the contact area with the porous transport layer (PTL) and the gas diffusion layer (GDL) to reduce the contact resistance in this area;

[0083] 2. The fine flow field is more likely to produce uniform distribution, improve reaction consistency, and further reduce mass transfer polarization;

[0084] 3. The total velocity of water vapor in this section of the flow channel is slow and will not cause excessive increase in pressure drop in this area.

[0085] In addition, in the rear end region (corresponding to the second sub-channel 312), since the front oxygen also flows through here, local bubbles accumulate, which will produce a huge concentration polarization. Therefore, a relatively sparse wide channel is used, which can bring the following technical advantages:

[0086] 1. The wide flow channel provides escape space for bubbles escaping from the catalyst layer, preventing bubbles from accumulating on the surface of the catalyst layer, thereby reducing mass transfer polarization;

[0087] 2. The total friction wall brought by the sparse flow channel is reduced, the total tension of the bubble attachment is reduced, and the bubble is more easily carried away by the water flow, and it is not easy to form local accumulation, which indirectly reduces the mass transfer polarization;

[0088] 3. The mixed flow rate of oxygen and water in the latter stage gradually decreases, and it is necessary to increase the flow area to reduce the flow resistance, thereby reducing the overall pressure drop and improving the working efficiency of the electrolyzer.

[0089] Embodiment 5

[0090] The embodiment of the present disclosure further provides a flow channel design structure with multiple sub-flow channels, where the sub-flow channels can be two, three, four, etc., and in practical applications, the number can be determined in combination with actual application requirements. Next, the flow channel design structure with two sub-flow channels will be described in detail.

[0091] like Figure 4 As shown, it is a schematic diagram of an exemplary bipolar plate structure (corresponding to the front view of the anode side), in addition to the water inlet area 10, the water outlet area 20 and the flow field area 30, the flow channel 31 arranged in the flow field area 30 includes two sub-channels (i.e., the third sub-channel 313 and the fourth sub-channel 314); a first distribution area 40 is arranged between the third sub-channel 313 and the fourth sub-channel 314; in the flow direction of the reaction water, the third sub-channel 313, the first distribution area 40 and the fourth sub-channel 314 are connected.

[0092] Among them, there are multiple third sub-channels 313 and multiple fourth sub-channels 314, and the multiple third sub-channels 313 are arranged in parallel perpendicular to the flow direction of the reaction water, and the multiple fourth sub-channels 314 are arranged in parallel perpendicular to the flow direction of the reaction water; each of the third sub-channels 313 is connected with at least one of the fourth sub-channels 314 through the first distribution area 40, that is, the flow field connection between the third sub-channel 313 and the fourth sub-channel 314 can be carried out through the first distribution area 40, thereby ensuring the consistency of flow distribution of the gradient flow field during the connection process.

[0093] The first distribution area 40 may be provided with a lattice structure, and the flow field may be better connected through the lattice structure.

[0094] In actual applications, since the gas generated by the electrolytic reaction in the flow field area 30 gradually accumulates along the flow direction, the flow channels in the front flow field area are relatively densely arranged, corresponding to a larger number N3 of third sub-channels 313, while the flow channels in the rear flow field area are relatively sparsely arranged, corresponding to a smaller number N4 of fourth sub-channels 314.

[0095] The specific number of the two sub-flow channels can be determined based on actual application requirements and is not specifically limited here.

[0096] The cross-sectional width of the third sub-channel 313 in the embodiment of the present disclosure is W31 (not shown), and the cross-sectional width of the fourth sub-channel 314 is W41 (not shown), wherein W31<W41. The cross-sectional widths of the two sub-channels can be determined based on actual application requirements and are not specifically limited herein.

[0097] The cross-sectional depth of the third sub-channel 313 in the embodiment of the present disclosure is D31 (not shown), and the cross-sectional depth of the fourth sub-channel 314 is D41 (not shown), wherein D31<D41. The cross-sectional depths of the two sub-channels can be determined based on actual application requirements and are not specifically limited herein.

[0098] In actual applications, the specific setting data of the number N3, cross-sectional width W31, and cross-sectional depth D31 of the third sub-channel 313 can be determined by referring to the relevant description of the first sub-channel 311, which will not be repeated here; similarly, the specific setting data of the number N4, cross-sectional width W41, and cross-sectional depth D41 of the fourth sub-channel 314 can be determined by referring to the relevant description of the second sub-channel 312, which will not be repeated here.

[0099] It can be seen that the channel structure formed by the third sub-channel 313 and the fourth sub-channel 314 still conforms to the design principle of setting fine channels in the front end area and relatively sparse wide channels in the rear end area. For relevant technical advantages, please refer to the above description, which will not be repeated here.

[0100] Embodiment 6

[0101] In the bipolar plate structure involved in the first to sixth embodiments, the water inlet region 10 is provided with a water inlet 11 and a second distribution area 12 for the reaction water to flow in, the water outlet region 20 is provided with a water outlet 21 and a third distribution area 22 for the reaction water to flow out, and the second distribution area 12 and the third distribution area 22 are centrally symmetrically arranged; wherein:

[0102] The second distribution area 12 is disposed between the water inlet 11 and the first end 31 a of the flow channel 31 , and the third distribution area 22 is disposed between the second end 31 b of the flow channel 31 and the water outlet 21 .

[0103] Similar to the first distribution area 40, the second distribution area 12 and the third distribution area 22 may both be provided with a lattice structure, and the flow field may be better connected through the lattice structure.

[0104] In addition, the second distribution area 12 and the third distribution area 22 are centrally symmetrically arranged, thereby ensuring uniformity of resistance distribution and improving consistency of the flow field in the flow field area 30 .

[0105] In actual applications, the reaction water enters the second distribution area 12 from the water inlet 11. Due to the flow resistance of the lattice of the second distribution area 12, the water flow will be redistributed to make it flow more evenly into the flow field area 30. Similarly, the water passing through the flow field area 30 will converge at the water outlet 21. Since the flow field area 30 has a targeted flow channel design for the bubble accumulation effect, the entire reaction process is more complete, which significantly improves the electrolysis efficiency. In addition, since the concentration polarization problem is avoided as much as possible, the possibility of life degradation of the electrolytic cell equipment is greatly reduced.

[0106] For any bipolar plate provided in the above-mentioned embodiments 1 to 6, both the flow channel 31 itself and each sub-flow channel included in the flow channel 31 can adopt a groove-type structural design, that is, the parameters such as the groove width and groove depth of the groove opened inward can achieve a gradient flow field effect from front to back. A convex structure design can also be adopted, that is, the gradient flow field effect can be achieved by the corresponding groove parameters formed by the convexities opened outward. In addition, other structural designs can also be adopted, and no specific restrictions are made here.

[0107] In addition, it can be seen from the anode side front view of any bipolar plate provided in the above-mentioned embodiments 1 to 6 that the bipolar plate here is also provided with two hydrogen outlets, namely a first hydrogen outlet 51 and a second hydrogen outlet 52, for discharging the hydrogen generated by electrolysis to the outside.

[0108] Based on any bipolar plate provided in the above-mentioned embodiments 1 to 6, the embodiments of the present disclosure also provide an electrolytic cell, which has higher electrolysis efficiency, longer service life, and wider applicability.

[0109] It should be noted that the electrolyzer here can be not only the above-mentioned bipolar plate (Bipolar Plate, BPP) electrolyzer, but also a proton exchange membrane (Proton Exchange Membrane, PEM) electrolyzer.

[0110] Here, the PEM electrolyzer also has a flow field area 30 with a continuous or discontinuous gradient, and the flow channel width, depth and other dimensional parameters of these flow field areas 30 are distributed in a gradient along the water flow direction. Considering that the gas generated by the electrolysis reaction in the flow field area 30 gradually accumulates along the flow direction, the flow channel of the front flow field area can be set to be relatively dense or small in depth, and the flow channel of the rear flow field area can be set to be relatively sparse or large in depth. The specific implementation process will not be repeated here.

[0111] In the description of this specification, the description with reference to the terms "some possible embodiments", "some embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure, and the above terms do not necessarily represent the same embodiment or example. Moreover, the described specific features, structures, materials or characteristics may be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art may combine and combine the different embodiments or examples described in this specification and the features of the different embodiments or examples, unless they are contradictory.

[0112] Although the spirit and principle of the present disclosure have been described above with reference to several specific embodiments, it should be understood that the present disclosure is not limited to the disclosed specific embodiments, and the division of various aspects does not mean that the features in these aspects cannot be combined. The present disclosure is intended to cover various modifications and equivalent arrangements included in the spirit and scope of the attached claims.

Claims

1. A bipolar plate, characterized in that: It comprises: a water inlet area, a water outlet area, and a flow field area connecting the water inlet area and the water outlet area, and the reaction water in the water inlet area flows through the flow field area and the water outlet area in sequence; A flow channel is arranged in the flow field area, and the flow channel has a first end and a second end along the flow direction of the reaction water; in a direction perpendicular to the bipolar plate, the cross-sectional area of ​​the first end of the flow channel is S1, and the cross-sectional area of ​​the second end of the flow channel is S2, wherein S1<S2.

2. The bipolar plate according to claim 1, characterized in that: There are multiple flow channels, and the multiple flow channels are arranged in parallel and perpendicular to the flow direction of the reaction water.

3. The bipolar plate according to claim 2, characterized in that: The cross-sectional width of the first end of each of the flow channels is W1, and the cross-sectional width of the second end of each of the flow channels is W2, wherein W1<W2.

4. The bipolar plate according to claim 2, characterized in that: The cross-sectional depth of the first end of each of the flow channels is D1, and the cross-sectional depth of the second end of each of the flow channels is D2, wherein D1<D2.

5. The bipolar plate according to claim 1, characterized in that: The flow channel includes a first sub-flow channel and a second sub-flow channel; The first sub-flow channel is connected to the second sub-flow channel in the flow direction of the reaction water.

6. The bipolar plate according to claim 5, characterized in that: There are a plurality of the first sub-channels, and a plurality of the second sub-channels, wherein the plurality of the first sub-channels are arranged in parallel and perpendicular to the flow direction of the reaction water, and the plurality of the second sub-channels are arranged in parallel and perpendicular to the flow direction of the reaction water; Two adjacent first sub-flow channels are connected to a corresponding one of the second sub-flow channels.

7. The bipolar plate according to claim 5, characterized in that: The number of the first sub-flow channels is N1, and the number of the second sub-flow channels is N2, wherein N1>N2.

8. The bipolar plate according to any one of claims 5 to 7, characterized in that: The cross-sectional width of the first sub-channel is W11, and the cross-sectional width of the second sub-channel is W21, wherein W11<W21.

9. The bipolar plate according to any one of claims 5 to 7, characterized in that: The cross-sectional depth of the first sub-channel is D11, and the cross-sectional depth of the second sub-channel is D21, wherein D11<D21.

10. The bipolar plate according to claim 1, characterized in that: The flow channel comprises a third sub-flow channel and a fourth sub-flow channel, and a first distribution area is arranged between the third sub-flow channel and the fourth sub-flow channel; The third sub-flow channel, the first distribution area and the fourth sub-flow channel are connected in the flow direction of the reaction water.

11. The bipolar plate according to claim 10, characterized in that: There are a plurality of the third sub-channels, there are a plurality of the fourth sub-channels, the plurality of the third sub-channels are arranged in parallel and perpendicular to the flow direction of the reaction water, and the plurality of the fourth sub-channels are arranged in parallel and perpendicular to the flow direction of the reaction water; Each of the third sub-flow channels is connected to at least one of the fourth sub-flow channels through the first distribution area.

12. The bipolar plate according to claim 11, characterized in that: The number of the third sub-flow channels is N3, and the number of the fourth sub-flow channels is N4, wherein N3>N4.

13. The bipolar plate according to any one of claims 10 to 12, characterized in that: The cross-sectional width of the third sub-channel is W31, and the cross-sectional width of the fourth sub-channel is W41, wherein W31<W41.

14. The bipolar plate according to any one of claims 10 to 12, characterized in that: The cross-sectional depth of the third sub-channel is D31, and the cross-sectional depth of the fourth sub-channel is D41, wherein D31<D41.

15. The bipolar plate according to any one of claims 1 to 7 and 10 to 12, characterized in that: The water inlet area is provided with a water inlet and a second distribution area for the reaction water to flow in, the water outlet area is provided with a water outlet and a third distribution area for the reaction water to flow out, and the second distribution area and the third distribution area are centrally symmetrically arranged; The second distribution area is arranged between the water inlet and the first end of the flow channel, and the third distribution area is arranged between the second end of the flow channel and the water outlet.

16. An electrolytic cell, characterized in that: include: The bipolar plate according to any one of claims 1 to 15.

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