CN114262909B

CN114262909B - Proton exchange membrane water electrolyzer, system and method

Info

Publication number: CN114262909B
Application number: CN202210066378.6A
Authority: CN
Inventors: 宗卫峰; 田丰
Original assignee: Hydrogen Hong Hangzhou Technology Co ltd
Current assignee: Suzhou Platinum Hydrogen New Energy Technology Co ltd
Priority date: 2022-01-20
Filing date: 2022-01-20
Publication date: 2024-09-10
Anticipated expiration: 2042-01-20
Also published as: CN114262909A

Abstract

The present invention provides a proton exchange membrane water electrolyzer, system and method. The electrolyzer includes a membrane electrode, an end plate, a positive flow field assembly and a negative flow field assembly, wherein the positive flow field assembly and the negative flow field assembly are located on opposite sides of the membrane electrode, and the end plates are respectively located at one end of the positive flow field assembly and the negative flow field assembly away from the membrane electrode, and an opening is provided on the end plate, and both the positive flow field assembly and the negative flow field assembly are provided with a flow guide hole, and the positive flow field assembly and the negative flow field assembly are provided with a diffusion structure layer, a bipolar plate, a flow channel plate and a flow channel frame, wherein the bipolar plate is provided with a long hole, a short hole and a through groove, and the flow channel plate is provided with a first slot and a second slot, and the through groove is interconnected through the gap between the long hole, the flow channel plate and the flow channel frame to form a water storage and exhaust chamber. The present invention can greatly reduce the processing difficulty of the flow field structure of the water electrolyzer, reduce the processing cost, help to extend the service life of the electrolyzer, and realize the pump-free operation of the water electrolyzer.

Description

Proton exchange membrane water electrolytic cell, system and method

Technical Field

The invention relates to the technical field of electrolytic water, in particular to a proton exchange membrane water electrolytic tank, a system and a method.

Background

The bottleneck in the current hydrogen production by PEM (polymer electrolyte membrane, also called proton exchange membrane) water electrolysis is the lifetime and cost of the electrolyzer. The lifetime of the membrane electrode is a major factor in determining the lifetime of the cell. The life of the existing membrane electrode is practically limited in two aspects, one is the life of the catalyst, but the life of the catalyst has been greatly advanced in recent years. Another problem that affects the life of the membrane electrode is that the geometry of the electrolyzer, particularly the flow field structure, and poor flow field design can cause critical defects such as water starvation, overheating, etc. of the membrane electrode, thereby causing premature failure of the membrane electrode.

In the traditional PEM electrolytic cell, parts such as a titanium bipolar plate, a titanium felt current collector, a proton membrane electrode coated with a catalyst and the like are tightly pressed together after being stacked in series in multiple layers through bolts by two end plates. The electrolytic tank is usually provided with a water outlet at the upper part and a water inlet at the lower part, and continuous water supply is completed through a water pump. The bipolar plate needs to be engraved with complex narrow channels (typically about 1mm wide and 0.3mm deep or more) on both sides or on one side. The current method of the runner is that one is etched by electric spark machining, the other is engraved by an engraving and milling machine, and the other is that titanium foil with the thickness of about 0.05-0.8mm is punched to form the runner, and then frames are welded or glued on two sides so as to seal and separate the gases on two sides. However, the first two methods usually process a bipolar plate with a flow field area of 100 square centimeters, which requires tens of hours on a high-speed CNC machine or an electric spark machine, and it is difficult to ensure consistency of processing quality over the whole area, not to mention a bipolar plate with thousands of square centimeters used on a large-scale electrolytic cell, which is time-consuming, difficult to ensure in terms of yield, and extremely high in processing cost. In the latter stamping method, because of the characteristics of titanium, the stamped runner cannot provide enough supporting force when the titanium is too thin, the runner collapses when the titanium foil is too thick, and the deep runner with flat and small spacing (less than 1 mm) cannot be stamped, so that the realizability and the electrical performance of the bipolar plate are often not good.

More fatal problems are that when the electrode area is large, the flow channel depth is insufficient (the narrow and deep flow channel is very difficult to process), and when the electrolytic cell is operated at a high current density (> 1A cm ^-2), generated air flow can occupy the water channel, thereby causing local part, particularly water shortage at the upper part of the electrolytic cell, overheating and seriously affecting the service life of the electrolytic cell.

Patent CN211556044U discloses an electrolytic cell and an anode bipolar plate structure, wherein 2 to 100 strip-shaped grooves are reserved on an anode electrode plate (i.e. a bipolar plate), meanwhile, a water guide plate is arranged on the anode side, and the vertical use mode of the water guide plate can still lead to gas accumulation on the upper part of the electrolytic cell to cause partial water shortage. The large-scale electrolytic tank is usually connected in series by multiple units, the electrode plates simultaneously play roles of providing a flow field and isolating gases on two sides, and meanwhile, the multiple units are connected in series into a whole, so that the severe sealing requirement is met, and the patent is only applicable to the situation when a single electrolytic tank is used, and cannot realize the connection of multiple units. And the water path and gas path management of the cathode hydrogen outlet side in a large-scale electrolytic tank is also extremely important, and obviously, the patent does not improve the cathode side.

It is therefore critical to develop an electrolyzer structure that can be used in multiple series connections while providing a smooth flow path. Meanwhile, bipolar plates (commonly referred to as bipolar plates) account for about 48% of the cell cost, so it is important to find a new flow field structure and improve the processing of bipolar plates to reduce the cost and improve the workability.

Disclosure of Invention

In view of the above-mentioned drawbacks of the prior art, the present invention aims to provide a proton exchange membrane water electrolyzer, a system and a method, which are used for solving the problems of the prior art that the bipolar plate of the PEM electrolyzer is difficult to process, the processing cost is high, the flow field problems of unsmooth water path and gas path, water shortage and the like exist in the electrolyzer, and the electrolyzer is easy to locally lack water and overheat, so that the service life of the electrolyzer is shortened.

In order to achieve the above and other related objects, the present invention provides a proton exchange membrane water electrolyzer, including a membrane electrode, an end plate, an anode flow field assembly and a cathode flow field assembly, wherein the anode flow field assembly and the cathode flow field assembly are located at two opposite sides of the membrane electrode, the end plate is located at one end of the anode flow field assembly and the cathode flow field assembly, which is away from the membrane electrode, respectively, at least one end plate is provided with an opening for discharging gas and water, the anode flow field assembly and the cathode flow field assembly are both provided with a diversion hole communicated with the opening, and the anode flow field assembly and the cathode flow field assembly are provided with a diffusion structure layer, a bipolar plate, a flow channel plate and a flow channel frame along the direction away from the membrane electrode, wherein the bipolar plate is provided with long holes, short holes and through grooves, the positions and structures of the long holes and the short holes are different, the flow channel plate is provided with a first slot and a second slot, the through groove of the bipolar plate, and the first slot and the second slot of the flow channel plate are communicated with each other through the long holes, and the flow channel plate and the gap between the two slots and the flow channel frame form a water storage cavity.

Optionally, the first slot and the second slot of the runner plate are disposed in a crossing manner and are communicated with each other.

Optionally, the plurality of through grooves of the bipolar plate form a comb tooth structure, and the through grooves on the same comb tooth structure are mutually communicated.

Alternatively, the tooth width of the through groove on the same comb tooth structure is 0.1-3mm, and the groove width of the through groove is 0.5-5mm.

Optionally, the plurality of through slots of the bipolar plate have a shape selected from a plurality of bar, H-shaped, circular, beaded, and zigzagged shapes, and at least some of the through slots are in communication with one another.

Optionally, the diffusion structure layer includes a soft pad and a current collector.

Optionally, the material of the runner frame and the runner plate is non-titanium material, and the runner plate is made of elastic material.

Optionally, the proton exchange membrane water separator further comprises a blind plate for preventing the end plate from polluting water quality, and the blind plate is positioned between the negative flow field assembly and the end plate.

Optionally, the proton exchange membrane water electrolytic tank comprises a plurality of positive flow field components, negative flow field components and oxyhydrogen separation plates, wherein the positive flow field components and the negative flow field components are alternately arranged to form a plurality of electrolytic water units which are mutually connected in series, the oxyhydrogen separation plates are provided with guide holes, the oxyhydrogen separation plates do not participate in conduction, and the adjacent electrolytic water units are separated by the oxyhydrogen separation plates.

Optionally, the proton exchange membrane water electrolysis cell further comprises a conductive sheet, and the bipolar plate of each water electrolysis unit extends outwards to be electrically connected with the conductive sheet.

The invention also provides a proton exchange membrane water electrolysis system, which comprises a water tank and the proton exchange membrane water electrolysis tank in any scheme, wherein the proton exchange membrane water electrolysis tank is horizontally arranged below the water tank in a way that the oxygen evolution surface of the anode faces upwards and is communicated with the water tank.

The invention also provides a proton exchange membrane water electrolysis method, which comprises the steps of horizontally placing the proton exchange membrane water electrolysis tank in any scheme in a way that the oxygen evolution surface of the positive electrode faces upwards below a water tank, communicating a water-gas inlet and a water-gas outlet of the proton exchange membrane water electrolysis tank with the water tank, and realizing continuous water electrolysis operation under the condition of no pump.

As described above, the proton exchange membrane water electrolytic cell, system and method of the present invention have the following beneficial effects: the invention can greatly reduce the processing difficulty of the flow field structure of the water electrolytic tank, reduce the processing cost, obviously improve the water flow smoothness in the electrolytic tank, avoid the phenomenon of water shortage and overheating of the membrane electrode, be beneficial to prolonging the service life of the electrolytic tank, reduce the complexity of the system and realize the pumpless operation of the large-scale proton exchange membrane water electrolytic tank by improving the structural design.

Drawings

Fig. 1 is a schematic diagram of an assembly structure of a proton exchange membrane water electrolyzer according to an embodiment of the invention.

Fig. 2 shows an exploded view of fig. 1.

Fig. 3 is a schematic view showing a use state of the proton exchange membrane water electrolyzer provided by the invention.

Fig. 4 shows a schematic flow field diagram of the proton exchange membrane water electrolysis tank in the water electrolysis process.

Fig. 5 is a schematic structural diagram of a bipolar plate of a proton exchange membrane water separator according to an embodiment of the present invention.

Fig. 6 is a schematic cross-sectional view of fig. 5 along line AA.

Fig. 7 is a schematic structural diagram of a bipolar plate of a proton exchange membrane water separator according to another embodiment of the present invention.

Fig. 8 shows a schematic view of the partial flow field of fig. 4.

Fig. 9 and 10 are enlarged schematic views of portions I and II of fig. 8, respectively.

Fig. 11 is a schematic view showing an exemplary structure of a flow field plate of a proton exchange membrane water separator according to the present invention.

Fig. 12 is a schematic view showing a cross-sectional structure along the BB line in fig. 11.

Fig. 13 is a schematic diagram showing an assembly structure of a proton exchange membrane water electrolysis cell according to a second embodiment of the present invention.

Fig. 14 shows an exploded view of fig. 13.

Description of element reference numerals

100. Proton exchange membrane water electrolytic tank

1. Membrane electrode

2. End plate

3. Oxyhydrogen partition plate

41. Current collector

42. Cushion for soft mattress

43. Bipolar plate

431. Long hole

432. Short hole

433. Through groove

44. Flow passage plate

441. First grooving

442. Second grooving

45. Flow channel frame

51. Current collector

52. Cushion for soft mattress

53. Bipolar plate

54. Flow passage plate

55. Flow channel frame

6. Blind plate

7. Conductive sheet

8. Water tank

81. Hydrogen tank

82. Oxygen tank

83. Communication hole

Detailed Description

Other advantages and effects of the present invention will become apparent to those skilled in the art from the following disclosure, which describes the embodiments of the present invention with reference to specific examples. The invention may be practiced or carried out in other embodiments that depart from the specific details, and the details of the present description may be modified or varied from the spirit and scope of the present invention. As described in detail in the embodiments of the present invention, the cross-sectional view of the device structure is not partially enlarged to a general scale for convenience of explanation, and the schematic drawings are only examples, which should not limit the scope of the present invention. In addition, the three-dimensional dimensions of length, width and depth should be included in actual fabrication.

For ease of description, spatially relative terms such as "under", "below", "beneath", "above", "upper" and the like may be used herein to describe one element or feature's relationship to another element or feature as illustrated in the figures. It will be understood that these spatially relative terms are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. Furthermore, when a layer is referred to as being "between" two layers, it can be the only layer between the two layers or one or more intervening layers may also be present.

In the context of the present application, a structure described as a first feature being "on" a second feature may include embodiments where the first and second features are formed in direct contact, as well as embodiments where additional features are formed between the first and second features, such that the first and second features may not be in direct contact.

It should be noted that, the illustrations provided in the present embodiment merely illustrate the basic concept of the present invention by way of illustration, and only the components related to the present invention are shown in the drawings and are not drawn according to the number, shape and size of the components in actual implementation, and the form, number and proportion of the components in actual implementation may be arbitrarily changed, and the layout of the components may be more complex. In order to make the illustration as concise as possible, not all structures are labeled in the drawings.

The traditional multistage PEM electrolytic cell is formed by stacking components such as a titanium electrode plate, a titanium felt current collector, a proton membrane electrode coated with a catalyst and the like in a multistage manner through bolts by two end plates and then tightly pressing the components together. The upper part of the electrolytic bath is usually provided with a water outlet, the lower part is provided with a water inlet, and the continuous supply of water in the reaction is completed through a water pump. The electrode plates are commonly called bipolar plates because the electrode plates serve as the positive and negative electrodes of adjacent units when being connected in series in multiple stages, and the bipolar plates also play a role in separating oxyhydrogen gas. The bipolar plate is engraved with complex flow channels. Since the flow channels on bipolar plates are typically elongated and narrow (flow channels are typically about 1mm wide and no more than 1mm deep non-through grooves), either engraving or electroetching is very difficult. In this regard, the inventors of the present application have made long-term studies and have proposed an improvement.

Please refer to fig. 1 to 14.

Example 1

As shown in fig. 1 to 12, the present invention provides a proton exchange membrane water electrolytic cell 100, which comprises a membrane electrode 1, an end plate 2, an anode flow field assembly and a cathode flow field assembly, wherein the anode flow field assembly and the cathode flow field assembly are positioned at two opposite sides of the membrane electrode 1, the end plate 2 is positioned at one end of the anode flow field assembly and the cathode flow field assembly, which is away from the membrane electrode 1, respectively (referring to fig. 2, two end plates 2 can be respectively defined as an upper end plate and a lower end plate), the membrane electrode 1, the anode flow field assembly and the cathode flow field assembly are arranged between the two end plates 2, and the upper end plate, the anode flow field assembly, the membrane electrode 1, the anode flow field assembly and the lower end plate are sequentially stacked and then can be locked by bolts to form the structure shown in fig. 1, however, in other examples, each structure can be fixed by other modes, and the structure is not strictly limited; In an example, the proton exchange membrane water separator may further include an oxyhydrogen separator 3, the oxyhydrogen separator 3 is located between the anode flow field assembly and the end plate, the oxyhydrogen separator 3 is provided with a flow guiding hole, and the oxyhydrogen separator 3 is used for separating hydrogen and oxygen, as the name implies, and does not participate in electrolysis and conduction, and thus may be made of an insulating material, for example, a polymer material plate such as a polyethylene plate, and of course may also be made of other materials; At least one of the end plates 2 is provided with openings for discharging gas and water in and out, for example, in this embodiment, a first opening including discharging hydrogen and water in and out and a second opening including discharging oxygen and water in and out are provided in the upper end plate ("first" and "second" are for convenience of description only and are not meant to be limiting in nature), and in this embodiment, the positive flow field assembly and the negative flow field assembly are each single, so that only the end plate adjacent to the positive flow field assembly may be provided with the first opening and the second opening (both the first opening and the second opening, for example), and the end plate 2 adjacent to the negative flow field assembly is not provided with the opening for water to pass through; The anode flow field component and the cathode flow field component are respectively provided with a flow guide hole communicated with the first opening and the second opening, the anode flow field component and the cathode flow field component are sequentially provided with a diffusion structure layer, a bipolar plate 43/53, a flow channel plate 44/54 and a flow channel frame 45/55 along the direction far away from the membrane electrode 1, the flow channel frame is of a structure with an accommodating groove inside, the flow channel plate is embedded in the accommodating groove of the flow channel frame, a gap with a certain width is reserved between two protruding ends of the flow channel plate and the flow channel frame, the bipolar plate 43/53 and the flow channel plate 44/54 are provided with through grooves, the gap between a long hole 431 on the bipolar plate and the flow channel plate/flow channel frame is in cross communication, To enable the water flow to flow into the water storage and drainage chamber formed by the through grooves of the bipolar plate and the through grooves of the runner plate, more specifically, referring to fig. 5-7, the bipolar plate 43 is provided with a long hole 431, a short hole 432 and a through groove 433, the runner plate 44 is provided with a first slot 441 and a second slot 442, one of the first slot 441 and the second slot 442 is a through groove (i.e. a through runner plate), the other is a non-through groove, the through groove 433 of the bipolar plate 43, the first slot 441 and the second slot 442 of the runner plate 44 are formed by the long hole 431 on the bipolar plate 43, the short holes 432, the flow channel plates 44/54 and the gaps between the flow channel frames 45/55 are mutually communicated to form a water storage and drainage cavity (namely, the water storage and drainage cavity is communicated with the flow guide holes through the long holes of the bipolar plates).

As shown in fig. 3, the exemplary working process of the proton exchange membrane water electrolyzer 100 provided in this embodiment is that the electrolyzer is horizontally placed in operation, so that the anode (oxygen separation side) is on, a plurality of (e.g. 4) water gas inlets and outlets of the electrolyzer are directly communicated with the water tank, the water tank 8 is placed above the electrolyzer, the water tank 8 may include a hydrogen tank 81 and an oxygen tank 82, and the two tanks may be separated by a plate provided with a communication hole 83, which is helpful for water level balance; the direct current voltage is applied to the bipolar plate, at this time, hydrogen and oxygen are respectively separated out from the two surfaces of the membrane electrode 1 coated with the catalyst, the separated hydrogen and oxygen rapidly pass through a loose current collector (the oxygen passes through the current collector 41 of the positive electrode flow field assembly, the hydrogen passes through the current collector 51 of the negative electrode flow field assembly), enter a water storage and exhaust cavity formed by a through groove (which can also be defined as a diversion groove, but penetrates through the bipolar plate) on the bipolar plate and a through groove of the flow channel plate, and a gap between the flow channel frame and the flow channel plate, and are discharged from an inlet and an outlet to the water tank through long holes 431. The volume of the through groove of the flow channel plate can be made large enough by adjusting the thickness of the flow channel plate, so that the discharged gas can have enough buffer storage space. As shown in fig. 4, water entering the positive electrode side of the electrolytic tank from the water tank 8 is left at the lower part of the water storage and exhaust cavity under the combined action of gravity and pressure of separated oxygen, so that the oxygen separation surface of the whole membrane electrode 1 is always immersed in the water, and the electrolytic reaction is distributed on the membrane surface more uniformly; the structure of the water storage exhaust cavity of the hydrogen evolution side is similar to that of the oxygen evolution side. Although the hydrogen evolution side does not need water supplementing, the water storage and exhaust cavity is also arranged on the hydrogen evolution side, so that the reaction heat can be taken away by more effectively utilizing the flow of water, the overheating failure of the membrane electrode is prevented, and the service life of the membrane electrode is prolonged. According to the invention, the flow channel plate is additionally arranged behind the bipolar plate, the through groove is carved on the flow channel plate, the through groove on the bipolar plate, the through groove on the flow guide plate and the gap between the flow channel frame and the flow channel plate jointly form a large-volume water storage and exhaust cavity, so that the efficiency of water-gas exchange between the electrolytic tank and the outside can be greatly improved, and good conditions are provided for water flow heat dissipation and gas exhaust. Compared with the structure of a non-through groove in the prior art, the through groove of the bipolar plate forming the water storage and exhaust cavity can be processed in a plurality of modes such as laser cutting, ion cutting, water knife, wire cutting and the like, the original flow field (0.5 mm wide flow channel) of 100 square centimeters needs 10 hours by using a CNC high-speed machine tool, the flow field structure of the invention can be processed by using laser for 2 minutes, the processing efficiency is greatly improved, the processing cost is reduced, and the width and depth of the through groove can be far larger than those of the flow channel of the traditional engraving and milling, so the flow resistance can be greatly reduced. The runner plate can be produced in a machining or injection molding mode, and the cost is low. Compared with the traditional vertical placing mode, the electrolytic tank is horizontally placed in a mode that the bipolar plate is parallel to the ground, the positive electrode oxygen-separating surface is arranged on the upper part of the electrolytic tank, the electrolytic tank is directly connected with the electrolytic tank, gas separated during operation naturally rises to enter the water storage and exhaust cavity, pure water stays at the bottom of the water storage and exhaust cavity under the combined action of gravity and air pressure, so that the membrane electrode is immersed in the pure water at all times, the problem of water shortage of the membrane electrode is thoroughly solved, the pump-free operation of the electrolytic tank is realized, the complexity of a system is greatly simplified, and the reliability of the system is improved. The proton exchange membrane water electrolytic tank provided by the invention can stably operate for thousands of hours under the current density of 2A.cm ^-2 under the condition of no pump, and is still in stable operation at present.

As shown in fig. 5-7, the long holes 431 and the short holes 432 of the bipolar plate 43 are both in communication with the flow guiding holes of the flow channel frame, and two groups of the long holes 431 and the short holes 432 are located at opposite ends of the bipolar plate 43, i.e., opposite ends are respectively provided with one long hole 431 and one short hole 432. The long holes 431 of the bipolar plate of the positive flow field component and the short holes 432 of the bipolar plate of the negative flow field component are coaxially stacked and form a common flow channel with the diversion holes of the flow channel frame and the like. The short holes 432 of the bipolar plate of the positive flow field assembly and the long holes 431 of the bipolar plate of the negative flow field assembly are also coaxial at this time. Because the long holes and the short holes have shapes and positions different, namely, one hole position difference d (shown by referring to fig. 5) exists between the two types of holes, the short holes cannot be communicated with the water storage exhaust cavity after being stacked and pressed, and the long holes extend to gaps between the convex block runner frames on the runner plates due to the existence of the hole position difference, so that the long holes are communicated with the water storage exhaust cavity (shown by referring to fig. 8-10). When in electrolysis, oxyhydrogen gas respectively enters a common flow channel through a gas channel formed by long holes 431 positioned on a bipolar plate of the positive flow field component and long holes 431 positioned on a bipolar plate of the negative flow field component and flows back to the water tank. Because the short holes are not communicated with the water storage exhaust cavity, only one gas can flow through each common flow channel (the gas on the positive electrode side or the gas on the negative electrode side), so that oxyhydrogen is isolated. In the process of water electrolysis, a partition plate is arranged in the water tank 8 to separate oxyhydrogen gas, and a communication hole can be arranged at the bottom of the partition plate so as to keep the water levels at two sides balanced.

As shown in fig. 5 to 6, in an example, the through grooves 433 of the bipolar plate 43 may be distributed in a comb-like shape, that is, a plurality of through grooves 433 thereof constitute a comb-like structure, and the through grooves 433 located on the same comb-like structure communicate with each other. Referring to fig. 5, it can be seen that a plurality of parallel through slots 433 spaced apart from each other are connected to a through slot perpendicular thereto to form a comb-tooth structure, and thus one end of the parallel through slots is a free end (i.e., has a certain flexibility), which allows the portion of the bipolar plate 43 corresponding to the through slot to swing back and forth in a vertical plane, which contributes to compression fixation of the entire electrolytic cell, in particular, to improvement of compression fixation of the bipolar plate and the membrane electrode 1. The through grooves on the same comb tooth structure form a communicated closed structure in the horizontal plane. In the present embodiment, only one comb structure is illustrated, but the present invention is not limited thereto. If the bipolar plate is applied to an oversized electrolytic tank, the bipolar plate can be split at the moment because the comb tooth structure is too large and difficult to process and install, for example, the bipolar plate is divided into a plurality of electrodes with square meters, the number of through grooves can be thousands, and at the moment, the through grooves can be arranged into a plurality of comb tooth structures for improving the structural stability, so long as the through grooves on the same comb tooth structure are mutually communicated. When the through grooves of the comb structure design are adopted, the tooth width of the through grooves on the same comb structure is preferably 0.1-3mm, for example, 0.1mm,1mm,2mm,3mm or any value in the interval, the groove width of the through grooves is 0.5-5mm, for example, 0.5mm,1mm,2mm,3mm,4mm,5mm or any value in the interval, and the workability of the through grooves is greatly improved, so that compared with the case that the depth of the flow guide groove of the bipolar plate in the prior art is only as deep as 1mm, the depth of the flow guide groove can be more selected, and particularly, the depth of the flow guide groove can be far more than 1 mm.

In other examples, as shown in fig. 7, the plurality of through grooves 433 of the bipolar plate 43 may have a shape selected from a plurality of shapes such as a bar shape, an H shape, a circular shape, a bead shape (i.e., including a plurality of circular portions and a straight portion connecting the circular portions) and a zigzag shape, and at least a portion of the through grooves 433 are connected to each other to form an inner closed region.

The bipolar plates in fig. 5 and 7 have different through grooves, but the design of the flow guide holes is the same, and the flow guide holes comprise long holes and short holes, so that the bipolar plates are particularly applied to the electrolytic cell in fig. 1, the flow field structure is the same, and reference is particularly made to fig. 4 and 8, and fig. 9 and 10 correspond to the flow directions of the part I and the part II in fig. 4 and 8 respectively.

It should be noted that, although only the bipolar plate of the positive flow field assembly is taken as an example in this embodiment, the bipolar plate structure of the negative flow field assembly may be identical to the bipolar plate structure of the positive flow field assembly, and the thickness of the bipolar plate of the negative flow field assembly (i.e., the thickness of the through slot) may be identical to or different from the thickness of the bipolar plate of the positive flow field assembly.

As shown in fig. 11 and 12, in the present embodiment, the through slot of the flow channel plate 44 includes a first slot 441 and a second slot 442 that are disposed to intersect each other, and the first slot 441 and the second slot 442 are in communication with each other. More specifically, for example, the first slot 441 is a horizontal slot and the second slot 442 is a vertical slot, the extending directions of the horizontal slot and the vertical slot are perpendicular to each other, and the extending directions of the horizontal slot are parallel to each other and vertically correspond to the through slots of the bipolar plate. By the design, the hydraulic resistance is reduced, and the water and air flow is smoother. Meanwhile, the width and depth of the through groove on the runner plate can be far larger than those of the runner engraved and milled on the traditional polar plate, so that the flow resistance can be greatly reduced.

It should be noted that, although only the flow channel plate of the positive flow field assembly is taken as an example in the present embodiment, the flow channel plate structure of the negative flow field assembly may be identical to the flow channel plate structure of the positive flow field assembly, and the thickness of the flow channel plate of the negative flow field assembly (i.e., the thickness of the through slot) may be identical to or different from the thickness of the flow channel plate of the positive flow field assembly.

As an example, the diffusion structure layer comprises a soft cushion and a current collector, i.e. the diffusion structure layer of the positive flow field assembly comprises a soft cushion 42 and a current collector 41, and the negative flow field assembly likewise comprises a current collector 51 and a soft cushion 52. The soft pad is for example a flexible pad of silicone, and the current collector is for example a titanium felt or a titanium mesh, which serves to distribute the charge evenly over the membrane electrode 1 and to reduce the contact resistance.

The material of the runner frame and the runner plate is usually a non-titanium cheap material, and the runner plate is preferably made of an elastic material, such as polyethylene, polypropylene or other high-performance polymer materials, but not limited thereto, but may be other materials. The oxyhydrogen separator 3 may be an insulating plate, but may be made of other materials, so long as the oxyhydrogen separator does not participate in the electric conduction in the water electrolysis process.

In an example, the proton exchange membrane water separator 100 further includes a blind plate 6 for preventing the end plate 2 from polluting water, and is located between the negative flow field assembly (refer to fig. 2, which is the negative flow field assembly nearest to the end plate) and the end plate 2, where the blind plate 6 is a planar plate with no diversion holes on the surface, and the blind plate 6 is made of an insulating material with smooth surface, so as to prevent the end plate 2 (i.e. the lower end plate) located at one end of the negative flow field assembly from contacting water to pollute water.

In the schematic view of the present embodiment, although the oxyhydrogen outlet is provided on the same side, in practice, the water inlet+oxyhydrogen outlet may be provided on both the upper and lower end plates 2, in which case the blind plate 6 needs to be replaced with the oxyhydrogen separator 3.

Example two

As shown in fig. 13 and 14, the present embodiment provides a proton exchange membrane water separator of another structure. The main difference between this embodiment and the first embodiment is that in the first embodiment, only a single positive flow field component and a single negative flow field component are provided, while in this embodiment, the proton exchange membrane water electrolytic tank includes a plurality of positive flow field components, a plurality of negative flow field components and a plurality of oxyhydrogen separator plates 3, the positive flow field components and the negative flow field components are alternately arranged to form a plurality of electrolyzed water units a connected in series with each other, the single electrolyzed water unit a includes a positive flow field component and a negative flow field component, the oxyhydrogen separator plates 3 are provided with diversion holes, the oxyhydrogen separator plates 3 do not participate in conduction, the adjacent electrolyzed water units are separated by the oxyhydrogen separator plates 3 (i.e., the oxyhydrogen separator plates 3 are located between the positive flow field components and the negative flow field components, and the oxyhydrogen separator plates 3 can be also arranged between the positive flow field components and the separator plates at the top, and the specific structures of the positive flow field components and the negative flow field components are the same as in the first embodiment, and the specific reference is made to the first embodiment for brevity. The plurality of electrolytic water units are connected in series, so that the electrolytic water efficiency is improved, the system structure is further simplified, the occupied space of the electrolytic tank is reduced, and the electrolytic cost is reduced.

In one example, the proton exchange membrane water electrolytic cell further comprises a conductive sheet 7, and the bipolar plate of each electrolytic water unit extends outwards, so that after the structures are pressed and fastened, the outwards extending part of the bipolar plate of each electrolytic water unit is in contact with the conductive sheet 7 to realize electric connection, and the conductive sheet comprises but is not limited to copper sheets. Such a design is helpful to improve the convenience of disassembly and assembly of the proton exchange membrane water electrolyzer. Of course, in other examples, the electrical connection may be achieved by wires or welding, and the respective electrolytic water cells may be connected in series, which is not strictly limited.

Example III

As shown in fig. 3, the present invention further provides a proton exchange membrane water electrolysis system, which includes a water tank 8 and a proton exchange membrane water electrolysis cell 100 as described in the first or second embodiment, wherein the proton exchange membrane water electrolysis cell 100 is horizontally disposed below the water tank 8 in such a manner that the oxygen evolution surface of the positive electrode faces upwards, and is in communication with the water tank 8. The water tank 8 includes, for example, a hydrogen tank 81 and an oxygen tank 82, which may be spaced apart by a plate provided with communication holes 83, which facilitate water level balancing. As shown in fig. 4, water entering the positive electrode side of the electrolytic tank from the water tank 8 is left at the lower part of the water storage and exhaust cavity under the combined action of gravity and pressure of separated oxygen, so that the oxygen separation surface of the whole membrane electrode 1 is always immersed in the water, and the electrolytic reaction is distributed on the membrane surface more uniformly; the structure of the water storage exhaust cavity of the hydrogen evolution side is similar to that of the oxygen evolution side. Although the hydrogen evolution side does not need water supplementing, the water storage and exhaust cavity is also arranged on the hydrogen evolution side, so that the reaction heat can be taken away by more effectively utilizing the flow of water, the overheating failure of the membrane electrode is prevented, and the service life of the membrane electrode is prolonged. For further description of the proton exchange membrane water electrolyzer, reference is made to the foregoing, and details are omitted for the sake of brevity. The proton exchange membrane water electrolysis system provided by the embodiment adopts the proton exchange membrane water electrolysis tank, so that continuous water electrolysis operation can be realized without using a pump, namely the proton exchange membrane water electrolysis system provided by the embodiment has no pump.

Example IV

The present embodiment provides a method for hydrolyzing proton exchange membrane water, which includes horizontally placing the proton exchange membrane water electrolyzer described in any one of the above schemes with the positive electrode oxygen-evolving face facing upwards below the water tank (that is, the proton exchange membrane water electrolysis system described in embodiment three is adopted), communicating the water inlet and outlet of the proton exchange membrane water electrolyzer with the water tank, and implementing continuous water electrolysis operation under the condition of no pump. Specifically, as shown in fig. 3, water entering the positive electrode side of the electrolytic cell from the water tank 8 is left at the lower part of the water storage and exhaust cavity under the combined action of gravity and pressure of oxygen precipitation, after direct-current voltage is applied to the bipolar plate, hydrogen and oxygen are respectively precipitated on two sides of the membrane electrode 1 coated with the catalyst at the time, the precipitated hydrogen and oxygen rapidly pass through loose current collectors (the oxygen passes through the current collector 41 of the positive electrode flow field assembly and the hydrogen passes through the current collector 51 of the negative electrode flow field assembly), enter the water storage and exhaust cavity formed by mutually communicating through the through grooves of the bipolar plate, the first grooves of the runner plate and the second grooves of the runner plate through gaps among the long holes on the bipolar plate, the runner plate and the runner frame, and are discharged into the water tank from the inlet and the outlet to realize continuous water electrolysis operation in a non-pump state. The proton exchange membrane water electrolysis method provided by the embodiment can effectively avoid overheating of the membrane electrode due to the adoption of the proton exchange membrane water electrolysis tank, and can reduce electrolysis cost and improve electrode efficiency without using a pump.

In summary, the present invention provides a proton exchange membrane water electrolysis cell, system and method. The electrolytic tank comprises a membrane electrode, an end plate, an anode flow field component and a cathode flow field component, wherein the anode flow field component and the cathode flow field component are positioned on two opposite sides of the membrane electrode, the end plate is respectively positioned at one ends of the anode flow field component and the cathode flow field component, which deviate from the membrane electrode, openings for discharging gas and water are formed in the end plate, diversion holes communicated with the openings are formed in the anode flow field component and the cathode flow field component, a diffusion structure layer, a bipolar plate, a flow channel plate and a flow channel frame are arranged in the direction away from the membrane electrode, the bipolar plate is provided with long holes, short holes and through grooves, the positions and structures of the long holes and the short holes are different, and the through grooves of the bipolar plate, the first grooves and the second grooves of the flow channel plate are mutually communicated through long holes on the bipolar plate, the flow channel plate and a gap between the flow channel plate and the flow channel frame to form an air discharging cavity. The invention can greatly reduce the processing difficulty of the flow field structure of the water electrolytic tank, reduce the processing cost, obviously improve the water flow smoothness in the electrolytic tank, avoid the phenomenon of water shortage and overheating of the membrane electrode, be beneficial to prolonging the service life of the electrolytic tank, reduce the complexity of the system and realize the pumpless operation of the large-scale proton exchange membrane water electrolytic tank by improving the structural design. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The above embodiments are merely illustrative of the principles of the present invention and its effectiveness, and are not intended to limit the invention. Modifications and variations may be made to the above-described embodiments by those skilled in the art without departing from the spirit and scope of the invention. Accordingly, it is intended that all equivalent modifications and variations of the invention be covered by the claims, which are within the ordinary skill of the art, be within the spirit and scope of the present disclosure.

Claims

1. The utility model provides a proton exchange membrane water electrolyzer, its characterized in that includes membrane electrode, end plate, anodal flow field subassembly and negative pole flow field subassembly are located the opposite both sides of membrane electrode, the end plate is located respectively anodal flow field subassembly and negative pole flow field subassembly deviate from the one end of membrane electrode, be provided with the trompil that is used for exhaust gas and business turn over water on at least one end plate, anodal flow field subassembly and negative pole flow field subassembly all be provided with the guiding hole that the trompil is linked together, and anodal flow field subassembly and negative pole flow field subassembly are provided with diffusion structure layer, bipolar plate, runner plate and runner frame along the direction of keeping away from the membrane electrode, wherein, be provided with slot hole, short hole and link up the groove on the bipolar plate, slot hole and short hole's position and structure are different, be provided with first fluting and second fluting on the runner plate, one of first fluting and second fluting is the link up groove, and the other is the non-link up groove, the first fluting of bipolar plate and the runner plate and the second fluting is through the slot hole on the bipolar plate and runner plate and the runner is linked together with the water storage cavity of the water chamber through the clearance between the runner and the runner.

2. The pem water electrolyzer of claim 1 wherein said first and second slots of said flow field plates are disposed crosswise and in communication with one another.

3. The pem water electrolyzer of claim 1 wherein said plurality of through slots of said bipolar plates form a comb structure, said through slots on the same comb structure being in communication with one another.

4. A proton exchange membrane water electrolytic cell according to claim 3, wherein the through grooves on the same comb tooth structure have a tooth width of 0.1-3mm and a groove width of 0.5-5mm.

5. The pem water electrolyzer of claim 1 wherein said plurality of through slots of said bipolar plate are shaped in a variety of shapes selected from the group consisting of bar, H, circle, beaded and zig-zag, and at least some of the through slots are in communication with one another.

6. The pem water electrolyzer of claim 1 wherein said diffusion structure layer comprises a soft pad and a current collector.

7. The pem water electrolyzer of claim 1 wherein said flow frames and plates are of a non-titanium material and said flow plates are made of an elastomeric material.

8. The pem water electrolyzer of claim 1 further comprising a blind plate for preventing end plates from contaminating water quality, located between said negative flow field assembly and end plates.

9. The proton exchange membrane water electrolytic cell according to any one of claims 1 to 8, wherein the proton exchange membrane water electrolytic cell comprises a plurality of positive flow field components, negative flow field components and oxyhydrogen separation plates, the positive flow field components and the negative flow field components are alternately arranged to form a plurality of electrolytic water units connected in series, the oxyhydrogen separation plates are provided with diversion holes, the oxyhydrogen separation plates do not participate in conduction, and adjacent electrolytic water units are separated by oxyhydrogen separation plates.

10. The pem water electrolyzer of claim 9 further comprising conductive strips, the bipolar plates of each electrolyzed water unit extending outwardly to make electrical connection with said conductive strips.

11. A proton exchange membrane water electrolysis system, characterized in that the proton exchange membrane water electrolysis system comprises a water tank and the proton exchange membrane water electrolysis cell according to any one of claims 1 to 10, wherein the proton exchange membrane water electrolysis cell is horizontally arranged below the water tank in a way that the oxygen evolution surface of the anode is upwards, and is communicated with the water tank.

12. A method for hydrolyzing a proton exchange membrane water, characterized in that the method for hydrolyzing a proton exchange membrane water comprises horizontally placing the proton exchange membrane water electrolyzer according to any one of claims 1 to 10 below a water tank in such a manner that the oxygen evolution surface of the positive electrode faces upwards, communicating a water-gas inlet and a water-gas outlet of the proton exchange membrane water electrolyzer with the water tank, and realizing continuous water electrolysis operation under the condition without a pump.