CN216972701U

CN216972701U - Proton exchange membrane water electrolyzer and system

Info

Publication number: CN216972701U
Application number: CN202220153997.4U
Authority: CN
Inventors: 宗卫峰; 田丰
Original assignee: Hydrogen Hong Hangzhou Technology Co ltd
Current assignee: Hydrogen Hong Hangzhou Technology Co ltd
Priority date: 2022-01-20
Filing date: 2022-01-20
Publication date: 2022-07-15
Anticipated expiration: 2032-01-20

Abstract

The utility model provides a proton exchange membrane water electrolyzer and a system. The electrolytic cell includes a membrane electrode, an end plate, a cathode flow field assembly and a cathode flow field assembly. The cathode flow field assembly and the anode flow field assembly are located on opposite sides of the membrane electrode, and the end plates are respectively located at the opposite sides of the anode flow field assembly and the anode flow field assembly. One end of the membrane electrode and the end plate are provided with openings, the positive flow field assembly and the negative flow field assembly are both provided with diversion holes, and the positive flow field assembly and the negative flow field assembly are provided with a diffusion structure layer, a bipolar plate, The flow channel plate and the flow channel frame, wherein the bipolar plate is provided with long holes, short holes and through grooves, the flow channel plate is provided with a first slot and a second slot, and the through slot passes through the long holes, the flow channel plate The gap between the runner frame and the runner frame is communicated with each other to form a water storage and exhaust cavity. The utility model can greatly reduce the processing difficulty of the flow field structure of the water electrolysis cell, reduce the processing cost, help prolong the service life of the electrolysis cell, and realize the pumpless operation of the water electrolysis cell.

Description

Proton exchange membrane water electrolyzer and system

Technical Field

The utility model relates to the technical field of electrolyzed water, in particular to a water electrolyzer with an proton exchange membrane and a system.

Background

The bottleneck of the water electrolysis hydrogen production of the PEM (polymer electrolyte membrane, also called proton exchange membrane) at present is the service life and the cost of an electrolytic cell. The life of the membrane electrode is the main reason for determining the life of the electrolytic cell. The lifetime of existing membrane electrodes is actually limited in two ways, one being the lifetime of the catalyst, but the lifetime of the catalyst has been greatly advanced in recent years. Another problem affecting the life of the membrane electrode is the geometric structure of the electrolyzer, especially the flow field structure, and poor flow field design can cause fatal defects such as water shortage and overheating of the membrane electrode, so that the membrane electrode fails prematurely.

The traditional PEM electrolyzer is formed by stacking and connecting a titanium bipolar plate, a titanium felt collector, a proton membrane electrode coated with a catalyst and other components in a multi-layer manner through bolts by two end plates and then tightly pressing the components together. Usually, a water outlet is arranged at the upper part of the electrolytic bath, a water inlet is arranged at the lower part of the electrolytic bath, and the continuous supply of water is completed by a water pump. Complicated and narrow flow channels (usually about 1mm in width and over 0.3mm in depth) need to be engraved on two sides or one side of the bipolar plate. The method for manufacturing the flow channel comprises the following steps of etching by electric spark machining, engraving and milling by using an engraving and milling machine, forming the flow channel by punching titanium foil with the thickness of about 0.05-0.8mm, and welding or gluing frames on two sides so as to seal and separate gas on the two sides. However, the former two methods usually process a bipolar plate with a flow field area of 100 square centimeters, which requires ten hours and more hours on a high-speed CNC machine tool or an electric spark machine, and it is difficult to ensure the consistency of the processing quality over the whole area, not to mention the thousands of square centimeters of bipolar plates used on a large-scale electrolytic cell, and the processing is time-consuming, the yield is difficult to ensure, and the processing cost is extremely high. In the latter stamping method, due to the characteristics of titanium, when the thickness of the titanium foil is too thin, the stamped runner cannot provide enough supporting force, the runner collapses in use, and when the thickness of the titanium foil is too thick, a flat deep runner with a small distance (less than 1mm) cannot be stamped, so that the realizability and the electrical performance of the bipolar plate are not satisfactory.

The more fatal problem is that when the electrode area is large, the channel depth is not sufficient (the narrow and deep channel is very difficult to process), and the generated air flow can occupy the channel when the electrolytic cell is operated at a large current density (>1A cm < -2 >), so that the water shortage at the upper part of the electrolytic cell, which causes overheating, and the service life of the electrolytic cell is seriously influenced.

Patent CN 211556044U discloses an electrolytic cell and anode bipolar plate structure, wherein 2 to 100 strip-shaped grooves are left on an anode electrode plate (i.e. bipolar plate), and a water guide plate is arranged on the anode side, so that the vertical use mode may still cause gas accumulation on the upper part of the electrolytic cell to cause local water shortage. The large electrolytic cell is usually formed by connecting multiple units in series, the electrode plate simultaneously plays a role in providing a flow field and isolating gas on two sides, and the multiple units are connected in series into a whole with severe sealing requirements. And the water-way gas-way management of the cathode hydrogen-outlet side in a large-scale electrolytic cell is also extremely important, and obviously, the patent does not improve the cathode side.

It is therefore critical to develop an electrolytic cell structure that can be used in a multi-stage series configuration while providing a smooth flow path. Meanwhile, the cost of the electrolytic cell is about 48% of the bipolar plate (commonly called bipolar plate), so it is very important to find a new flow field structure and improve the processing method of the bipolar plate to reduce the cost and improve the processability.

SUMMERY OF THE UTILITY MODEL

In view of the above disadvantages of the prior art, the present invention aims to provide a water electrolyzer with proton exchange membrane and a system thereof, which are used for solving the problems of the PEM water electrolyzer in the prior art, such as high processing difficulty and high processing cost, poor flow field problems of unsmooth water path and gas path, water shortage, etc., existing in the water electrolyzer, and short service life of the water electrolyzer due to easy local water shortage and overheating.

In order to achieve the above and other related objects, the present invention provides an pem water electrolyzer comprising a membrane electrode, end plates, an anode flowfield assembly and a cathode flowfield assembly, wherein the anode flowfield assembly and the cathode flowfield assembly are located on opposite sides of the membrane electrode, the end plates are respectively located at one ends of the anode flowfield assembly and the cathode flowfield assembly, which are away from the membrane electrode, at least one end plate is provided with openings for discharging gas and water, the anode flowfield assembly and the cathode flowfield assembly are both provided with flow guide holes communicated with the openings, the anode flowfield assembly and the cathode flowfield assembly are provided with a diffusion structure layer, a bipolar plate, a runner plate and a runner frame along a direction away from the membrane electrode, wherein the bipolar plate is provided with a long hole, a short hole and a through groove, the long hole and the short hole have different positions and structures, and the runner plate is provided with a first slot and a second slot, the through groove of the bipolar plate, the first open groove and the second open groove of the runner plate are communicated with each other through the long hole on the bipolar plate, the gap between the runner plate and the runner frame to form a water storage and exhaust cavity.

Optionally, the first slot and the second slot of the runner plate are arranged crosswise and are communicated with each other.

Alternatively, the through grooves of the bipolar plate form a comb structure, and the through grooves on the same comb structure are communicated with each other.

Optionally, 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 0.5-5 mm.

Optionally, the plurality of through grooves of the bipolar plate have a shape selected from a plurality of shapes of a strip, an H-shape, a circle, a bead and a zigzag shape, and at least some of the through grooves communicate with each other.

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

Optionally, the flow channel frame and the flow channel plate are made of non-titanium material plates, and the flow channel plate is made of an elastic material plate.

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

Optionally, the proton exchange membrane water electrolyzer comprises a plurality of positive electrode flow field assemblies, negative electrode flow field assemblies and oxyhydrogen separator plates, wherein the positive electrode flow field assemblies and the negative electrode flow field assemblies are alternately arranged to form a plurality of electrolytic water units connected in series, the oxyhydrogen separator plates are provided with flow guide holes, the oxyhydrogen separator plates do not participate in electric conduction, and adjacent electrolytic water units are subjected to gas separation through the oxyhydrogen separator plates.

Optionally, the proton exchange membrane water electrolyzer 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 utility model also provides a proton exchange membrane water electrolysis system, which comprises a water tank and the proton exchange membrane water electrolysis cell in any scheme, wherein the proton exchange membrane water electrolysis cell is horizontally placed below the water tank in a mode that the positive electrode oxygen evolution surface faces upwards, and is communicated with the water tank.

As described above, the proton exchange membrane water electrolyzer and the system of the present invention have the following beneficial effects: through the improved structural design, the processing difficulty of the flow field structure of the water electrolysis bath can be greatly reduced, the processing cost is reduced, the smoothness of water flow in the electrolysis bath can be obviously improved, the phenomenon of water shortage and overheating of a membrane electrode is avoided, the service life of the electrolysis bath is prolonged, the complexity of a system is reduced, and the pumpless operation of a large proton exchange membrane water electrolysis bath is realized.

Drawings

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

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

FIG. 3 is a schematic view showing the use state of the proton exchange membrane water electrolyzer provided by the utility model.

Fig. 4 shows a schematic view of a flow field in the process of electrolyzing water in the proton exchange membrane water electrolyzer provided by the utility model.

Fig. 5 is a schematic structural diagram of a bipolar plate of a pem water electrolyzer according to the present invention in an example.

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

Fig. 7 is a schematic structural diagram of a bipolar plate of a proton exchange membrane water electrolyzer provided by the utility model in another example.

Fig. 8 is a schematic view of the local flow field of fig. 4.

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

Fig. 11 is a schematic view showing an exemplary structure of a flow channel plate of a proton exchange membrane water electrolyzer provided in the utility model.

Fig. 12 is a schematic cross-sectional view along line BB of fig. 11.

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

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

Description of the element reference

100 proton exchange membrane water electrolyzer

1 film electrode

2 end plate

3 oxyhydrogen division board

41 Current collector

42 soft cushion

43 Bipolar plate

431 long hole

432 short hole

433 through groove

44 flow passage plate

441 first slot

442 second slot

45 flow passage frame

51 Current collector

52 cushion

53 bipolar plate

54 flow passage plate

55 flow channel frame

6 blind plate

7 conducting strip

8 Water tank

81 hydrogen tank

82 oxygen tank

83 communication hole

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The utility model is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention. As in the detailed description of the embodiments of the present invention, the cross-sectional views illustrating the device structures are not partially enlarged in general scale for convenience of illustration, and the schematic views 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 the actual fabrication.

For convenience in description, spatial relational terms such as "below," "beneath," "below," "under," "over," "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 terms of spatial relationship are intended to encompass other orientations of the device in use or operation in addition to the orientation depicted in the figures. In addition, 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 this application, a structure described as having a first feature "on" a second feature may include embodiments in which the first and second features are formed in direct contact, and may also include embodiments in which additional features are formed in 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 drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated. In order to keep the drawings as concise as possible, not all features of a single figure may be labeled in their entirety.

The traditional multistage PEM electrolyzer is formed by tightly pressing a titanium electrode plate, a titanium felt current collector, a proton membrane electrode coated with a catalyst and the like together after the components are stacked in multiple stages by two end plates through bolts. Usually, a water outlet is arranged at the upper part of the electrolytic cell, a water inlet is arranged at the lower part of the electrolytic cell, and the continuous supply of water in the reaction is completed through a water pump. The electrode plates are generally called bipolar plates because they serve as the positive and negative electrodes of adjacent units in multi-stage series connection, and the bipolar plates also serve as the separator for oxyhydrogen gas. Complex flow channels are engraved on the bipolar plate. Since the flow channels on a bipolar plate are typically elongated and narrow (the flow channels are typically non-through grooves about 1mm wide, not more than 1mm deep), the process of either engraving or electroetching is very difficult. In contrast, the inventors of the present application have made extensive studies and have proposed an improvement.

Please refer to fig. 1 to 14.

Example one

As shown in fig. 1 to 12, the present invention provides an pem water electrolyzer 100, which comprises a membrane electrode 1, an end plate 2, a positive electrode flow field assembly and a negative electrode flow field assembly, the anode flow field assembly and the cathode flow field assembly are positioned at two opposite sides of the membrane electrode 1, the end plates 2 are respectively positioned at one ends of the anode flow field assembly and the cathode flow field assembly which are far away from the membrane electrode 1, that is, the end plates 2 are two (referring to fig. 2, the two end plates 2 can be respectively defined as an upper end plate and a lower end plate), the membrane electrode 1, the positive flow field assembly and the negative flow field assembly are arranged between the two end plates 2, and the upper end plate, the positive flow field assembly, the membrane electrode 1, the negative flow field assembly and the lower end plate can be sequentially stacked and then locked by bolts to form the structure shown in fig. 1, of course, in other examples, the structures may be fixed by other methods, which is not limited strictly; in one example, the proton exchange membrane water electrolyzer may further include a hydrogen-oxygen separator plate 3, the hydrogen-oxygen separator plate 3 is located between the anode flow field assembly and the end plate, a flow guide hole is formed in the hydrogen-oxygen separator plate 3, and the hydrogen-oxygen separator plate 3 is used for separating hydrogen from oxygen as the name implies, and does not participate in electrolysis and conduction, and therefore may be made of an insulating material, such as a polymer material plate, e.g., a polyethylene plate, or other materials; at least one of the end plates 2 is provided with openings for discharging gas and water, for example, in this embodiment, the upper end plate is provided with a first opening for discharging hydrogen and water and a second opening for discharging oxygen and water ("first" and "second" are merely for convenience of description and have no substantial limiting meaning), and in this embodiment, the positive flow field assembly and the negative flow field assembly are both single, so that the first opening and the second opening (for example, two openings are both provided) may be provided only on the end plate adjacent to the positive flow field assembly, and the end plate 2 adjacent to the negative flow field assembly is not provided with openings for water flow; the anode flow field assembly and the cathode flow field assembly are respectively provided with a flow guide hole communicated with the first open pore and the second open pore, the anode flow field assembly and the cathode flow field assembly 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, and the long holes 431 on the bipolar plate and the gap between the flow channel plate/the flow channel frame are communicated in a crossing manner, so that water can flow into a water storage and exhaust cavity formed by the mutual communication between the through grooves of the bipolar plate and the through grooves of the flow channel plate, more specifically, as shown in fig. 5 to 7, the bipolar plate 43 is provided with a long hole 431, a short hole 432 and a through groove 433, the flow channel plate 44 is provided with a first open groove 441 and a second open groove 442, one of the first open groove 441 and the second open groove 442 is a through groove (i.e., a through flow channel plate), and the other is a non-through groove, and the through groove 433 of the bipolar plate 43 and the first open groove 441 and the second open groove 442 of the flow channel plate 44 are communicated with each other through gaps between the long hole 431, the short hole 432, the flow channel plate 44/54 and the flow channel frame 45/55 of the bipolar plate 43 to form a water storage and exhaust cavity (i.e., the water storage and exhaust cavity is communicated with the flow guide hole through the long hole of the bipolar plate 43).

The exemplary operation process of the pem water electrolyzer 100 provided in this embodiment is, as shown in fig. 3, placing the electrolyzer horizontally during operation with the anode (oxygen evolution side) on top, multiple (e.g. 4) water vapor inlets and outlets of the electrolyzer directly communicating with the water tank, placing the water tank 8 above the electrolyzer, the water tank 8 may include a hydrogen tank 81 and an oxygen tank 82, the two tanks may be separated by a plate with a communication hole 83, and the communication hole is provided to facilitate water level balance; when a direct current voltage is applied to the bipolar plate, hydrogen and oxygen are respectively separated out from two surfaces of the membrane electrode 1 coated with the catalyst, and the separated hydrogen and oxygen rapidly pass through a loose current collector (oxygen passes through the current collector 41 of the anode flow field assembly, and hydrogen passes through the current collector 51 of the cathode flow field assembly), enter a water storage and exhaust cavity formed by a through groove (which can be defined as a flow guide groove, only the flow guide groove passes through the bipolar plate) on the bipolar plate, the through groove of the flow passage plate and a gap between the flow passage frame and the flow passage plate, and are discharged into a water tank from an inlet and an outlet through the long hole 431. The through groove of the runner plate can be made large enough by adjusting the thickness of the runner plate, so that the exhausted gas has enough buffer storage space. As shown in fig. 4, the water entering the anode side of the electrolytic cell from the water tank 8 is retained at the lower part of the water storage and exhaust cavity under the combined action of gravity and the pressure of the precipitated oxygen, so that the oxygen evolution surface of the whole membrane electrode 1 is always soaked in the water, and the electrolytic reaction is more uniformly distributed on the membrane surface; the structure of the water storage and air exhaust cavity at the hydrogen evolution side is similar to that at the oxygen evolution side. Although water is not required to be supplemented to the hydrogen evolution side, the water storage and exhaust cavity is also arranged at the hydrogen evolution side, so that the flow of water can be more effectively utilized to take away reaction heat, the membrane electrode is prevented from being overheated and invalid, and the service life of the membrane electrode is prolongedIts life is long. The utility model adds a runner plate behind the bipolar plate, the runner plate is provided with a through groove, the guide groove penetrating the bipolar plate, the through groove on the guide plate and the gap between the runner frame and the runner plate form a large-volume water storage and exhaust cavity together, which can greatly improve the efficiency of water-gas exchange between the electrolytic tank and the outside, thereby providing good conditions 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 various modes such as laser cutting, ion cutting, water jet cutting, linear cutting and the like, a 100-square-centimeter flow field (0.5mm wide flow channel) needs 10 hours by a CNC high-speed machine tool, the flow field structure can be processed by laser after 2 minutes, the processing efficiency is greatly improved, the processing cost is reduced, and the width and the depth of the through groove can be far larger than those of a flow channel which is milled in the prior art, so that the flow resistance can be greatly reduced. The runner plate can be produced by machining or injection molding, and is low in cost. The utility model is different from the traditional vertical arrangement mode, the electrolytic tank is horizontally arranged in a mode that the bipolar plate is parallel to the ground, the anode oxygen evolution surface is arranged on the upper part of the electrolytic tank, the water tank is arranged on the upper part of the electrolytic tank and is directly connected with the electrolytic tank, the separated gas can naturally rise to enter the water storage and exhaust cavity during operation, and the pure water is left 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 soaked in the pure water at every moment, the problem of water shortage of the membrane electrode is thoroughly solved, the pumpless operation of the electrolytic tank is realized, the system complexity is greatly simplified, and the system reliability is improved. The water electrolyzer with the proton exchange membrane provided by the utility model is adopted to realize 2A cm under the pump-free condition^–2Is in stable operation for thousands of hours at the current density of (c).

As shown in fig. 5 to 7, the long holes 431 and the short holes 432 of the bipolar plate 43 are both communicated with the flow guide holes of the flow channel frame, and two long holes 431 and short holes 432 are respectively arranged at two opposite ends of the bipolar plate 43, namely, the two opposite ends are respectively provided with one long hole 431 and one short hole 432. The long hole 431 of the bipolar plate of the anode flow field assembly and the short hole 432 of the bipolar plate of the cathode flow field assembly are coaxially stacked and form a common flow channel together with the flow guide holes of the flow channel frame. The short bore 432 of the bipolar plate of the positive flow field assembly and the long bore 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 different shapes and positions, namely, the two types of holes have a hole position difference d (shown in figure 5), the short holes cannot be communicated with the water storage and exhaust cavity after being stacked and pressed, and because of the hole position difference, the long holes extend to gaps between the lug flow channel frames on the flow channel plate and are communicated with the water storage and exhaust cavity (shown in figures 8-10). During electrolysis, oxyhydrogen gas respectively enters a common flow channel through a gas path consisting of a long hole 431 on the bipolar plate of the anode flow field assembly and a long hole 431 on the bipolar plate of the cathode flow field assembly and then flows back to the water tank. Because the short hole is not communicated with the water storage and air exhaust cavity, only one gas (gas on the positive electrode side or gas on the negative electrode side) can flow through each common flow channel, and therefore hydrogen and oxygen are isolated. In the process of electrolyzing water, a partition board is arranged in the water tank 8 to separate oxyhydrogen gas, and the bottom of the partition board can be provided with a communication hole so as to keep the water levels at the two sides balanced.

As shown in fig. 5-6, in one example, the through grooves 433 of the bipolar plate 43 may be distributed in a comb shape, that is, a plurality of through grooves 433 form a comb structure, and the through grooves 433 on the same comb structure are connected to each other. As can be seen with reference to fig. 5, a plurality of parallel through grooves 433 arranged at intervals are connected to a through groove perpendicular thereto to present a comb structure, so that one end of these parallel through grooves is a free end (i.e. has a certain flexibility), which allows the portion of the bipolar plate 43 corresponding to the through groove to swing back and forth in the vertical plane, which facilitates the compression fixation of the whole electrolytic cell, in particular 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. It should be noted that, in the embodiment, although only one comb tooth structure is illustrated, the utility model is not limited thereto. If the comb tooth structure is applied to an oversize electrolytic tank, the comb tooth structure is too large and difficult to process and install, the bipolar plate can be split at the moment, for example, the bipolar plate is divided into a plurality of electrodes with one sheet in a plurality of square meters, the through grooves can be thousands of, the through grooves can be arranged into a plurality of comb tooth structures for improving the structural stability, and the through grooves on the same comb tooth structure can be communicated with one another only by ensuring the through grooves. When the through grooves designed by the comb tooth structure are adopted, the tooth width of the through grooves on the same comb tooth structure is preferably 0.1-3mm, such as 0.1mm, 1mm, 2mm, 3mm or any value in the interval, the groove width of the through grooves is 0.5-5mm, such as 0.5mm, 1mm, 2mm, 3mm, 4mm, 5mm or any value in the interval, and as the machinability of the through grooves is greatly improved, compared with the condition that the depth of the diversion grooves of the bipolar plate in the prior art can only be as deep as 1mm, the depth of the utility model can be more selected, and especially the depth can be far larger 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 of a strip, an H-shape, a circle, a bead (i.e., including a plurality of circular portions and straight portions connecting the circular portions) and a zigzag shape, and at least some of the through grooves 433 may be connected to each other to form an inner closed region.

The bipolar plates in fig. 5 and 7 have different through-groove structures, but the design of the flow guiding holes is the same, and both the flow guiding holes comprise long holes and short holes, so that the bipolar plates are specifically applied to the electrolytic cell in fig. 1, the flow field structure is also the same, and specifically refer to fig. 4 and 8, while fig. 9 and 10 correspond to the water flow directions of the parts I and 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 completely the same, and the thickness of the bipolar plate 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 groove) may be the same or different.

As shown in fig. 11 and 12, in the present embodiment, the through grooves of the flow field plate 44 include a first open groove 441 and a second open groove 443 which are disposed to cross each other, and the first open groove 441 and the second open groove 441 are communicated with each other. More specifically, for example, the first open grooves 441 are horizontal grooves and the second open grooves 442 are vertical grooves, the extending directions of the horizontal grooves and the vertical grooves are perpendicular to each other, and the extending directions of the horizontal grooves are, for example, parallel to and up-down corresponding to the through grooves of the bipolar plate. Through such design, help reducing the fluid resistance, make the aqueous vapor flow more smoothly. Meanwhile, the width and the depth of the through groove on the flow passage plate can be far larger than those of a flow passage milled on a traditional pole plate, so that the flow resistance can be greatly reduced.

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

Illustratively, the diffusion structure layer includes a soft pad and a current collector, i.e., the diffusion structure layer of the positive flow field assembly includes a soft pad 42 and a current collector 41, and the negative flow field assembly also includes a current collector 51 and a soft pad 52. The soft pad is, for example, a flexible pad of silica gel, and the current collector is, for example, a titanium felt or a titanium mesh, and the current collector serves to uniformly distribute electric charge throughout the membrane electrode 1 and reduce contact resistance.

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

In an example, the pem water electrolyzer 100 further includes a blind plate 6 for preventing the end plate 2 from polluting water, the blind plate 6 is located between the end plate 2 and the negative electrode flow field assembly (refer to fig. 2, the end portion is the negative electrode flow field assembly most adjacent to the end plate), the blind plate 6 is a flat plate without flow guide holes on the surface, the material of the flat plate can be an insulating material with a smooth surface, and the end plate 2 (i.e. the lower end plate) located at one end of the negative electrode flow field assembly is prevented from polluting water by contacting water by the blind plate 6.

Although the oxyhydrogen outlet is arranged on the same side in the schematic diagram of the embodiment, in practice, the water inlet + oxyhydrogen outlet can be arranged on both the upper and lower end plates 2, and in this case, the blind plate 6 needs to be replaced by the oxyhydrogen separation plate 3.

Example two

As shown in fig. 13 and 14, the present embodiment provides a proton exchange membrane water electrolyzer of another structure. The main difference between the first embodiment and the second embodiment is that the first embodiment only has a single anode flow field assembly and a single cathode flow field assembly, and in the present embodiment, the proton exchange membrane water electrolyzer includes a plurality of anode flow field assemblies, a plurality of cathode flow field assemblies and a plurality of oxyhydrogen separators 3, the anode flow field assemblies and the cathode flow field assemblies are alternately arranged to form a plurality of electrolytic water units a connected in series, each electrolytic water unit a includes one anode flow field assembly and one cathode flow field assembly, the oxyhydrogen separators 3 are provided with flow guide holes, the oxyhydrogen separators 3 do not participate in electric conduction, adjacent electrolytic water units are separated by the oxyhydrogen separators 3 (i.e. the oxyhydrogen separators 3 are located between the anode flow field assembly and the cathode flow field assembly, and the oxyhydrogen separators 3 can also be arranged between the top anode flow field assembly and the separator), the specific structures of the positive electrode flow field assembly and the negative electrode flow field assembly are the same as those in the first embodiment, and reference is made to the description in the first embodiment, which is not repeated for brevity. The plurality of water electrolysis units are connected in series, so that the water electrolysis efficiency is improved, the system structure is further simplified, the occupied space of the electrolytic cell is reduced, and the electrolysis cost is reduced.

In one example, the proton exchange membrane water electrolyzer further comprises a conductive sheet 7, wherein 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 contacted with the conductive sheet 7 to realize electric connection, and the conductive sheet comprises but is not limited to a copper sheet. The design is beneficial to improving the convenience of assembling and disassembling the proton exchange membrane water electrolyzer. Of course, in other examples, the electrolytic water cells may be connected in series by wires or welding, but this 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 placed below the water tank 8 with the positive electrode oxygen evolution surface facing upward, and is communicated 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 a communication hole 83 for facilitating water level balance. As shown in fig. 4, the water entering the anode side of the electrolytic cell from the water tank 8 is retained at the lower part of the water storage and exhaust cavity under the combined action of gravity and the pressure of the precipitated oxygen, so that the oxygen evolution surface of the whole membrane electrode 1 is always soaked in the water, and the electrolytic reaction is more uniformly distributed on the membrane surface; the structure of the water storage and air exhaust cavity at the hydrogen evolution side is similar to that at the oxygen evolution side. Although water is not needed to be supplemented on the hydrogen evolution side, the water storage and exhaust cavity is also arranged on the hydrogen evolution side, so that the reaction heat can be effectively taken away by utilizing the flow of water, the membrane electrode is prevented from being overheated and losing efficacy, and the service life of the membrane electrode is prolonged. For more description of the proton exchange membrane water electrolyzer, please refer to the foregoing, and for brevity, the description is omitted. The proton exchange membrane water electrolysis system provided by the embodiment adopts the proton exchange membrane water electrolysis cell, 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.

The proton exchange membrane water electrolysis method performed by the proton exchange membrane water electrolysis cell comprises the steps of horizontally placing the proton exchange membrane water electrolysis cell in any one of the schemes below a water tank in a mode that a positive electrode oxygen evolution surface faces upwards (namely, adopting the proton exchange membrane water electrolysis system in the third embodiment), communicating a water-gas inlet and a water-gas outlet of the proton exchange membrane water electrolysis cell with the water tank, and realizing continuous water electrolysis operation under a pump-free condition. Specifically, as shown in fig. 3, water entering the anode side of the electrolytic cell from the water tank 8 is retained at the lower part of the water storage and exhaust cavity under the combined action of gravity and the pressure of the separated oxygen, after a direct current voltage is applied to the bipolar plate, hydrogen and oxygen are separated out from both sides of the membrane electrode 1 coated with the catalyst at this time, the separated hydrogen and oxygen rapidly pass through the loose current collector (oxygen passes through the current collector 41 of the anode flow field assembly, and hydrogen passes through the current collector 51 of the cathode flow field assembly), enter the water storage and exhaust cavity formed by the through groove of the bipolar plate, the first open groove and the second open groove of the flow passage plate communicating with each other through the long hole on the bipolar plate, the flow passage plate and the gap between the flow passage frames, and are discharged into the water tank from the inlet and the outlet to realize continuous electrolytic water operation in a pump-free state. The water electrolysis method of the proton exchange membrane provided by the embodiment adopts the water electrolysis tank of the proton exchange membrane, so that the overheating of the membrane electrode can be effectively avoided, a pump is not needed, the electrolysis cost can be reduced, and the electrode efficiency can be improved.

In summary, the present invention provides a water electrolyzer with proton exchange membrane and a system thereof. The electrolytic bath 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 at two opposite sides of the membrane electrode, the end plate is respectively positioned at one end of the anode flow field component and the cathode flow field component which are deviated from the membrane electrode, the end plate is provided with an opening for discharging gas and water, the anode flow field component and the cathode flow field component are respectively provided with a flow guide hole communicated with the opening, and the anode flow field component and the cathode flow field component are provided with a diffusion structure layer, a bipolar plate, a runner plate and a runner frame along the direction far away from the membrane electrode, wherein the bipolar plate is provided with a long hole, a short hole and a through groove, the long hole and the short hole are different in position and structure, the runner plate is provided with a first slot and a second slot, and the through groove of the bipolar plate, the first slot and the second slot of the runner plate pass through the long hole, the short hole and the through groove on the bipolar plate, The gaps between the runner plate and the runner frame are communicated with each other to form a water storage and air exhaust cavity. Through the improved structural design, the processing difficulty of the flow field structure of the water electrolyzer can be greatly reduced, the processing cost is reduced, the smoothness of water flow in the water electrolyzer can be obviously improved, the phenomenon of water shortage and overheating of a membrane electrode is avoided, the service life of the water electrolyzer is prolonged, the complexity of a system is reduced, and the pumpless operation of the large proton exchange membrane water electrolyzer is realized. Therefore, the utility model effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the utility model. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.

Claims

1. A water electrolyzer with proton exchange membrane is prepared as setting positive and negative flow field components at two opposite sides of membrane electrode, setting end plate at one end of said positive and negative flow field components separately, setting at least one end plate on said end plate to be opened for exhausting gas and water, setting flow guide holes on said positive and negative flow field components, setting diffusion structure layer, double polar plate, flow channel plate and flow channel frame on said double polar plate along direction far from said membrane electrode, setting long hole, short hole and through groove on said double polar plate, setting first and second slots on said flow channel plate, one of the first open slot and the second open slot is a through slot, the other is a non-through slot, the through slot of the bipolar plate, the first open slot and the second open slot of the flow passage plate are communicated with each other through gaps among the long holes on the bipolar plate, the flow passage plate and the flow passage frame to form a water storage and exhaust cavity.

2. The pem water electrolyzer of claim 1 wherein said first and second slots of said flow field plate are disposed in intersecting relationship and in communication with each other.

3. The pem water electrolyzer of claim 1 wherein said plurality of through-slots of said bipolar plate form a comb-tooth structure, the through-slots on the same comb-tooth structure communicating with each other.

4. The pem water electrolyzer of claim 3 wherein the through slots on the same comb tooth structure have a tooth width of 0.1-3mm and a slot width of 0.5-5 mm.

5. The pem water electrolyzer of claim 1, wherein said plurality of through-grooves of said bipolar plate are in the shape of a plurality of strips, H-shapes, circles, beads, and zigzags, and at least some of said through-grooves are in communication with each other.

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

7. The pem water electrolyzer of claim 1 wherein said flow-channel frame and flow-channel plate are non-titanium plates and said flow-channel plate is a plate of elastomeric material.

8. The pem water electrolyzer of claim 1 further comprising a blind plate between said negative flow field assembly and said end plate for preventing contamination of water by said end plate.

9. The pem water electrolyzer of any one of claims 1 to 8, wherein said pem water electrolyzer comprises a plurality of positive flow field assemblies, negative flow field assemblies and oxyhydrogen separators, wherein the positive flow field assemblies and the negative flow field assemblies are alternately arranged to form a plurality of electrolytic water units connected in series, said oxyhydrogen separators are provided with flow guide holes, the oxyhydrogen separators do not participate in electric conduction, and adjacent electrolytic water units are separated by oxyhydrogen separators.

10. The pem water electrolyzer of claim 9 further comprising an electrically conductive sheet to which the bipolar plates of each electrolyser cell extend outwardly to make electrical connection.

11. A proton exchange membrane water electrolysis system comprising 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 placed below the water tank with the positive electrode oxygen evolution surface facing upward and is communicated with the water tank.