Electrochemical device, electrochemical system, and gas manufacturing process

Abstract

The invention discloses an electrochemical device, an electrochemical system and a gas manufacturing process, and belongs to the technical field of electrochemistry. The electrochemical device comprises two electrode assemblies, each electrode assembly comprises an electrode and a separator connected to one side of the electrode, the two electrode assemblies are arranged in a spaced mode, the two separators are oppositely arranged, a flow channel is defined between the two separators, the flow channel is used for flowing of electrolyte, and the flow channel is used for flowing of the electrolyte. The wall face, used for being connected with the isolation piece, of the electrode is set to be a first wall face, the wall face, used for being connected with the electrode, of the isolation piece is set to be a second wall face, any one of the first wall face and the second wall face is provided with at least one concave part, and the other one of the first wall face and the second wall face is provided with at least one protruding part; the first wall face and the second wall face are arranged in an attached mode, and the protruding part is located in the concave part. The electrochemical device can significantly improve the reaction rate by increasing the reaction area.

Description

Technical Field

[0001] The present invention relates to the field of electrochemical technology, and in particular to an electrochemical device, an electrochemical system and a gas manufacturing process. Background Art

[0002] Electrochemistry has been widely used in chemical engineering, medicine, materials, energy, metal corrosion and protection, environmental science and other scientific and technological fields. Gas-liquid-solid reaction is a reaction process in which three different phases of gas, liquid and solid exist at the same time. It is a common reaction in electrochemical reactions, such as electrochemical electrolysis to produce hydrogen, electrochemical reduction of carbon dioxide, and electrocatalytic preparation of ammonia using helium and water as raw materials (electrochemical nitrogen reduction reaction), all of which realize electrocatalytic reactions by forming a gas-liquid-solid three-phase interface.

[0003] Electrochemical reactions are often accompanied by electrode reactions such as hydrogen evolution, oxygen evolution, and chlorine evolution on the electrode surface. These evolved gases are usually adsorbed on the electrode surface in the form of bubbles, resulting in a reduction in the electrode active area and uneven microscopic distribution of the electrode surface potential and current density, which in turn affects the energy consumption and reaction rate of the electrochemical reaction. To increase the reaction rate, researchers have continuously improved the electrocatalytic catalysts, gas or liquid raw materials, and other means to increase the gas-liquid-solid three-phase interface reaction rate. However, at present, the electrochemical reaction rate is still relatively low, which greatly limits the economic feasibility of industrialization. Summary of the invention

[0004] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, the present invention provides an electrochemical device, wherein the electrodes and the separator of the electrochemical device have a larger contact area, thereby having a larger reaction area, thereby improving the efficiency of the reaction.

[0005] The present invention also provides an electrochemical system having the electrochemical device.

[0006] The invention also provides a gas manufacturing process.

[0007] An electrochemical device according to a first aspect of the present invention comprises:

[0008] Two electrode assemblies, each comprising an electrode and a separator connected to one side of the electrode, the two electrode assemblies being arranged at a distance from each other, the two separators being arranged opposite to each other, and defining a flow channel for circulating an electrolyte between the two separators;

[0009] Among them, the wall surface of the electrode used to connect with the isolation member is set as the first wall surface, and the wall surface of the isolation member used to connect with the electrode is set as the second wall surface, either one of the first wall surface and the second wall surface is provided with at least one recessed portion, and the other is provided with at least one raised portion, the first wall surface and the second wall surface are arranged in close contact, and the raised portion is located in the recessed portion.

[0010] The electrochemical device according to the embodiment of the present invention has at least the following beneficial effects:

[0011] During the electrochemical reaction, the electrolyte in the flow channel penetrates through the separator and reacts with the electrode to form bubbles on the first wall surface of the electrode. Since the interface between the electrode and the separator in the embodiment of the present application is not a plane but an uneven interface, the electrode and the separator have a larger contact area compared to a plane structure, thereby having a larger reaction area, providing more attachment points for the formation of bubbles, thereby improving the efficiency of the reaction.

[0012] On the other hand, the electrode of the embodiment of the present application adopts porous materials, and the gas generated on the electrode surface can be discharged through the electrode penetration. By collecting and storing the gas discharged from the two electrodes separately, the gas mixing phenomenon in the electrochemical reaction can be effectively avoided, thereby reducing the risk of explosion and improving the purity of the gas. Since the bubbles are continuously diffused and discharged from the electrode, it is possible to avoid the bubbles adhering to the electrode surface to form a gas blockage phenomenon, thereby improving the efficiency of the electrochemical reaction from another perspective.

[0013] In addition, the separator of the embodiment of the present application also adopts porous materials. The interlocking design of the protrusion and the depression can disperse the local high pressure generated by the bubbles. Through the combined effect of the pore size, porosity and thickness of the separator, the bubble point pressure is increased and the permeation direction of the gas is limited, so that the gas can only diffuse out through the electrode in one direction and cannot flow back into the flow channel through the separator, thereby reducing the probability of gas and electrolyte mixing and contact. Experiments show that the gas mixing degree of the electrochemical device of the embodiment of the present application can be reduced to 0.01% under high current density conditions. As a result, the purity of the electrolyte in the flow channel is also guaranteed, effectively improving the reliability of the long-term operation of the electrochemical device.

[0014] According to some embodiments of the present invention, the second wall surface is provided with the protrusion, the interior of the protrusion is provided with a wetting channel, and one end of the wetting channel is connected to the flow channel.

[0015] According to some embodiments of the present invention, the number of the recessed portions and the number of the raised portions are both plural; wherein a single recessed portion is in any one of an arc, a triangle, and a square shape, and the raised portion is in a shape that matches the recessed portion;

[0016] Alternatively, a single recessed portion is in a plug-in structure, and along a direction away from the first wall surface, an inner diameter of the plug-in structure gradually increases and then gradually decreases, and the protruding portion is in a shape that matches the recessed portion.

[0017] According to some embodiments of the present invention, the maximum depth of the recessed portion is 1 um to 5 mm, and the maximum width of the recessed portion is 1 um to 5 mm.

[0018] According to some embodiments of the present invention, the electrode is a gas evacuation structure, and the gas evacuation structure is capable of conducting gas generated on the first wall surface in a direction away from the isolation element.

[0019] According to some embodiments of the present invention, the isolation member is a microfluidic liquid conducting structure, and the microfluidic liquid conducting structure can guide the electrolyte in the flow channel to the second wall surface.

[0020] According to some embodiments of the present invention, the porosity of the separator is 30% to 90%.

[0021] According to some embodiments of the present invention, the pore size of the isolation member is 1 μm to 5 μm, the electrode or the isolation member is provided with a plurality of the recessed portions arranged at intervals, and the interval between adjacent recessed portions is 50 μm to 200 μm.

[0022] According to some embodiments of the present invention, the separator is attached to the first wall surface of the electrode by a liquid phase in-situ synthesis process.

[0023] According to some embodiments of the present invention, the flow channel is a through structure, and the electrolyte can flow from one end of the flow channel to the other end of the flow channel;

[0024] Alternatively, a partition structure is provided in the flow channel, the partition structure divides the flow channel into a plurality of chambers, and the electrolyte can enter the chambers through the partition structure;

[0025] Alternatively, a filling structure is provided in the flow channel, and the fluid permeability of the filling structure is higher than the fluid permeability of the isolation element.

[0026] The electrochemical system according to the second aspect of the present invention comprises:

[0027] An electrochemical device as described in any one of the above embodiments;

[0028] A power source is electrically connected to the two electrodes respectively.

[0029] According to the gas manufacturing process of the third aspect of the present invention, the process comprises the following steps:

[0030] S100, preparing an electrochemical device, wherein the electrochemical device comprises two electrode assemblies, wherein the electrode assemblies comprise electrodes and a separator connected to one side of the electrodes, wherein the two electrode assemblies are spaced apart, and the two separators are arranged opposite to each other, and a flow channel is defined between the two separators, wherein the flow channel is used for the flow of an electrolyte; wherein a wall surface of the electrode used to connect with the separator is set as a first wall surface, and a wall surface of the separator used to connect with the electrode is set as a second wall surface, wherein either the first wall surface or the second wall surface is provided with at least one recessed portion, and the other is provided with at least one raised portion, and the first wall surface and the second wall surface are arranged in close contact with each other, and the raised portion is located in the recessed portion;

[0031] S200, transporting electrolyte to the flow channel;

[0032] S300, collecting generated gas from a side of the electrode assembly away from the flow channel.

[0033] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The present invention will be further described below with reference to the accompanying drawings and embodiments, wherein:

[0035] Figure 1 A schematic diagram of the structure of a system for water electrolysis in the related art;

[0036] Figure 2 is a schematic structural diagram of an electrochemical device according to an embodiment of the present invention;

[0037] Figure 3 for Figure 2 A schematic diagram of a further improved structure of the embodiment;

[0038] Figure 4 Another schematic diagram of the structure of the electrochemical device according to an embodiment of the present invention (the recessed portion is a triangle);

[0039] Figure 5 Another schematic diagram of the structure of the electrochemical device according to an embodiment of the present invention (the recessed portion is arc-shaped);

[0040] Figure 6 Another schematic diagram of the structure of the electrochemical device according to an embodiment of the present invention (the recessed portion is a plug-in structure);

[0041] Figure 7 Another schematic diagram of the structure of the electrochemical device according to an embodiment of the present invention (a separation structure is provided in the flow channel);

[0042] Figure 8It is another schematic diagram of the structure of the electrochemical device according to an embodiment of the present invention (a filling structure is provided in the flow channel).

[0043] Reference numerals:

[0044] First chamber 10; anode 11; second chamber 20; cathode 21; diaphragm 30;

[0045] Electrode assembly 100; electrode 110; first wall surface 111; recessed portion 112; separator 120; second wall surface 121; raised portion 122; wetting channel 123;

[0046] Flow channel 200; separation structure 210; filling structure 220; DETAILED DESCRIPTION

[0047] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0048] In the description of the present invention, it should be understood that descriptions involving orientations, such as up, down, front, back, left, right, etc., and orientations or positional relationships indicated are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0049] In the description of the present invention, "several" means more than one, "many" means more than two, "greater than", "less than", "exceed" etc. are understood to exclude the number itself, and "above", "below", "within" etc. are understood to include the number itself. If there is a description of "first" or "second", it is only used for the purpose of distinguishing the technical features, and cannot be understood as indicating or implying the relative importance or implicitly indicating the number of the indicated technical features or implicitly indicating the order of the indicated technical features.

[0050] In the description of the present invention, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in the present invention based on the specific content of the technical solution.

[0051] In the description of the present invention, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0052] Electrochemistry has been widely used in chemical engineering, medicine, materials, energy, metal corrosion and protection, environmental science and other scientific and technological fields. Gas-liquid-solid reaction is a reaction process in which three different phases of gas, liquid and solid exist at the same time. It is a common reaction in electrochemical reactions, such as electrochemical electrolysis to produce hydrogen, electrochemical reduction of carbon dioxide, and electrocatalytic preparation of ammonia using helium and water as raw materials (electrochemical nitrogen reduction reaction), all of which realize electrocatalytic reactions by forming a gas-liquid-solid three-phase interface.

[0053] Electrochemical reactions are often accompanied by electrode reactions such as hydrogen evolution, oxygen evolution, and chlorine evolution on the electrode surface. These evolved gases are usually adsorbed on the electrode surface in the form of bubbles, resulting in a reduction in the electrode active area and uneven microscopic distribution of the electrode surface potential and current density, which in turn affects the energy consumption and reaction rate of the electrochemical reaction. To increase the reaction rate, researchers have continuously improved the electrocatalytic catalysts, gas or liquid raw materials, and other means to increase the gas-liquid-solid three-phase interface reaction rate. However, at present, the electrochemical reaction rate is still relatively low, which greatly limits the economic feasibility of industrialization.

[0054] To facilitate understanding of the structure of a system for carrying out an electrochemical reaction, Figure 1 The specific application scenario of water electrolysis to produce hydrogen is shown as an example. Water electrolysis to produce hydrogen is an important means of producing hydrogen based on electrochemical reactions. Among them, alkaline water electrolysis is widely used in industry due to its low cost and high technical maturity. In the traditional scheme for alkaline water electrolysis, the following is usually used: Figure 1 The system for performing an electrochemical reaction (also known as an alkaline electrolyzer) is shown.

[0055] Figure 1 A schematic diagram of a system for performing an electrochemical reaction is shown. Figure 1As shown, the system includes an anode 11, a cathode 21 and a diaphragm 30, wherein the diaphragm 30 divides the system into a first chamber 10 and a second chamber 20. In the process of using the system for water electrolysis, an electrolyte (such as potassium hydroxide, sodium hydroxide, etc.) is passed into the first chamber 10 and the second chamber 20, and the anode 11 and the cathode 21 are completely immersed in the electrolyte, so that oxygen and hydrogen can be formed on the surface of the anode 11 and the cathode 21, respectively. In the process of the electrochemical reaction of water electrolysis, an oxygen evolution reaction shown in the following formula (1) occurs at the anode 11.

[0056] 4OH-→2H2O+O2+4e- (1);

[0057] A hydrogen evolution reaction as shown in the following formula (2) occurs at the cathode 21 .

[0058] 2H2O+4e-→H2+2OH- (2);

[0059] However, if Figure 1 As shown, hydrogen and oxygen are formed on the surface of the corresponding electrodes in the form of bubbles, which easily causes gas blocking, thereby hindering the occurrence of electrochemical reactions and reducing the efficiency of hydrogen production. Secondly, although a diaphragm 30 (such as an asbestos diaphragm, a polyphenylene sulfide (PPS) diaphragm, a composite diaphragm or other diaphragms) is provided in the system to prevent the mixing of hydrogen and oxygen, given that the production ratio of hydrogen and oxygen is 2:1, the pressure of the first chamber 10 and the second chamber 20 on both sides of the diaphragm 30 must be kept balanced at all times, otherwise, once the pressure of the two chambers is unbalanced, excessive hydrogen will pass through the diaphragm 30 and mix with oxygen, thereby causing an explosion risk.

[0060] To solve the above problems, the present application proposes an electrochemical device that can significantly increase the rate of electrochemical reactions and reduce the probability of gas mixing. Specifically, the electrochemical device includes two electrode assemblies 100, each of which includes an electrode 110 and an isolating member 120 connected to one side of the connection. It should be noted that it can be understood that the electrodes 110 of the two electrode assemblies 100 are made of different materials and have different polarities in the electrochemical reaction. The two electrode assemblies 100 are arranged at intervals, and the two isolating members 120 are respectively arranged on the two opposite walls of the two electrodes 110, and a flow channel 200 is defined between the two isolating members 120, and the flow channel 200 is used for the flow and diffusion of the electrolyte to facilitate the electrolyte to enter the electrode assembly 100.

[0061] It should be noted that, in order to increase the reaction rate of the electrochemical reaction, the wall surface where the electrode 110 and the separator 120 of the present application intersect is not a plane. Figures 2 to 5As shown, for the convenience of subsequent description, the wall surface on the electrode 110 used for connecting with the separator 120 is named as the first wall surface 111, and the wall surface on the separator 120 used for connecting with the electrode 110 is named as the second wall surface 121. Either one of the first wall surface 111 and the second wall surface 121 is provided with at least one recessed portion 112, and the other is provided with at least one raised portion 122. The first wall surface 111 and the second wall surface 121 are arranged in close contact, and the raised portion 122 is located in the recessed portion 112.

[0062] Specifically, in Figures 2 to 5 In the illustrated embodiment, a recessed portion 112 is provided on the first wall surface 111, and a raised portion 122 is provided on the second wall surface 121. The number of recessed portions 112 may be one or more, and the number of raised portions 122 is consistent with that of recessed portions 112. The recessed portion 112 may be arc-shaped, and the depth of the recessed portion 112 gradually increases and then gradually decreases. The recessed portion 112 may also be square, and the depth of the recessed portion 112 increases sharply to a set depth and then remains unchanged. The recessed portion 112 may also be triangular or other irregular complex shapes. The shapes of the various recessed portions 112 may be consistent or inconsistent, and may be determined according to specific needs.

[0063] During the electrochemical reaction, the electrolyte in the flow channel 200 penetrates through the separator 120 and reacts with the electrode 110 to form bubbles on the first wall surface 111 of the electrode 110. Since the interface between the electrode 110 and the separator 120 in the embodiment of the present application is not a plane but an uneven interface, the electrode 110 and the separator 120 have a larger contact area than a plane structure, thereby having a larger reaction area, providing more attachment points for the formation of bubbles, and thus improving the efficiency of the reaction.

[0064] On the other hand, the electrode 110 of the embodiment of the present application is made of porous material, and the gas generated on the surface of the electrode 110 can be discharged through the electrode 110. By collecting and storing the gas discharged from the two electrodes 110 respectively, the gas mixing phenomenon in the electrochemical reaction can be effectively avoided, thereby reducing the risk of explosion and improving the purity of the gas. Since the bubbles are continuously diffused and discharged from the electrode 110, it is possible to avoid the bubbles adhering to the surface of the electrode 110 to form a gas blockage phenomenon, thereby improving the efficiency of the electrochemical reaction from another perspective.

[0065] In addition, the separator 120 of the embodiment of the present application also adopts a porous material. The interlocking design of the protrusion 122 and the recess 112 can disperse the local high pressure generated by the bubbles. Through the combined effect of the pore size, porosity and thickness of the separator 120, the bubble point pressure is increased and the permeation direction of the gas is limited, so that the gas can only diffuse out through the electrode 110 in one direction and cannot flow back to the flow channel 200 through the separator 120, thereby reducing the probability of gas and electrolyte mixing and contact. Experiments show that the gas mixing degree of the electrochemical device of the embodiment of the present application can be reduced to 0.01% under high current density conditions. As a result, the purity of the electrolyte in the flow channel 200 is also guaranteed, effectively improving the reliability of the long-term operation of the electrochemical device.

[0066] In some embodiments, Figure 3 As shown, the second wall 121 is provided with a protrusion 122. It can be understood that due to the provision of the protrusion 122, the penetration path of the electrolyte from the flow channel 200 to the second wall 121 will be increased. To this end, in the embodiment of the present application, an infiltration channel 123 is provided inside the protrusion 122. The infiltration channel 123 is manufactured by laser drilling, machining drilling, etc. One end of the infiltration channel 123 is connected to the flow channel 200, and the other end of the infiltration channel 123 extends into the protrusion 122 but is not connected to the second wall 121. The inner diameter of the infiltration channel 123 is larger than the pore diameter of the porous material of the separator 120, and the electrolyte can flow from the flow channel 200 to the infiltration channel 123, and then penetrate into the pores of the separator 120 through the infiltration channel 123.

[0067] It can be understood that the provision of the wetting channel 123 shortens the penetration path of the electrolyte so that the electrolyte can reach the position close to the electrode 110 more quickly, and then the electrolyte therein can penetrate through the separator 120 to reach the electrode 110. One or more wetting channels 123 may be provided in each protrusion 122, and the wetting channel 123 may be a pipe with an inner diameter greater than 1 mm, and the electrolyte flows freely into the wetting channel 123 under the action of the internal hydraulic pressure. The wetting channel 123 may also be a capillary channel with an inner diameter less than 1 mm, and the electrolyte in the flow channel 200 flows into the wetting channel 123 under the attraction of the capillary action.

[0068] In some embodiments, based on the foregoing, the number of the recessed portion 112 and the raised portion 122 can be multiple. Figure 2 and Figure 3 In the embodiment shown, each recessed portion 112 is in the shape of a square, and adjacent recessed portions 112 are arranged at intervals, thereby forming a wall structure as shown in the figure. Figure 4In the embodiment shown, each recessed portion 112 is in the shape of a triangle, and adjacent recessed portions 112 are arranged at intervals, thereby forming a sawtooth structure as shown in the figure. Figure 5 In the embodiment shown, each recessed portion 112 is in an arc shape, and further, in a semicircular shape, and adjacent recessed portions 112 are arranged at intervals, thereby forming a wave structure as shown in the figure. The raised portion 122 is adapted to the shape of the recessed portion 112. When the recessed portion 112 is a square groove, the raised portion 122 is a square protrusion. When the recessed portion 112 is a triangular groove, the raised portion 122 is a triangular protrusion, and so on. The uneven structure on the first wall 111 and the second wall 121 expands the specific surface area of ​​the electrode 110, increases the reaction rate per unit volume, and significantly improves the electrochemical performance.

[0069] In addition, if Figure 6 As shown, the recessed portion 112 may also be a plug-in structure similar to a puzzle, and the inner diameter of the plug-in structure gradually increases and then gradually decreases in the direction away from the first wall 111, that is, in the direction from the isolating member 120 to the electrode 110. The plug-in structure forms a necked opening on the first wall 111, and the protruding portion 122 is located in the recessed portion 112 and is adapted to the shape of the recessed portion 112. That is, in the direction from the isolating member 120 to the electrode 110, the outer diameter of the protruding portion 122 gradually increases and then gradually decreases.

[0070] It is understood that the maximum depth of the recessed portion 112 is 1 μm to 5 mm, and the maximum width of the recessed portion 112 is 1 μm to 5 mm. Preferably, the maximum depth of the recessed portion 112 is 100 μm to 1 mm, and the maximum width of the recessed portion 112 is 100 μm to 1 mm. Within this range, the manufacturing difficulty of the recessed portion 112 and the raised portion 122 is relatively low, and the surface areas of the first wall surface 111 and the second wall surface 121 are relatively large.

[0071] In some embodiments, the electrode 110 is a gas evacuation structure. It should be noted that the gas evacuation structure includes a porous structure, a woven structure, etc., and has good gas conduction ability. When the electrochemical device of the present application is used for hydrogen production from alkaline water, the electrode 110 can be made of materials such as nickel-iron, nickel-cobalt alloy, nickel-molybdenum, etc.; when the electrochemical device of the present application is used for a proton exchange membrane electrolyzer (PEM electrolyzer), the electrode 110 can also be made of ruthenium oxide (RuO2), iridium oxide (IrO2), platinum carbon catalyst (Pt / C) and other precious metals. It is understandable that the material selection of the electrode 110 is not limited to the listed examples, as long as it meets the characteristics of loose porosity, high corrosion resistance, and high strength, it can be applied.

[0072] Taking the example of the electrode 110 as a porous structure, there are multiple holes inside the electrode 110, and the adjacent holes are connected in sequence, so that the electrode 110 defines multiple first pore channels. It can be understood that, unlike the infiltration channel 123 formed by artificial manufacturing, the first pore channel is naturally formed by the porous characteristics of the material. One end of the intricate first pore channel in the electrode 110 extends to the wall of the electrode 110 away from the separator 120, and the other end extends to the first wall 111 of the electrode 110, so that the gas generated on the first wall 111 of the electrode 110 can be discharged in a direction away from the separator 120, thereby preventing the gas from penetrating through the separator 120 into the flow channel 200 to contaminate the electrolyte.

[0073] In some embodiments, the separator 120 is a microfluidic liquid conduction structure, which includes a porous structure, a fiber structure, etc., and has good liquid conduction ability. The separator 120 can be made of ceramic materials, metal foam materials, polymer materials, composite materials, etc. Take the example of the separator 120 being a porous structure for illustration. There are multiple holes inside the separator 120, and adjacent holes are connected in sequence to define multiple second pore channels in the separator 120. The second pore channels are naturally formed by the porous properties of the material. One end of the second pore channel extends to communicate with the flow channel 200, and the other end extends to the second wall 121 of the separator 120, so that the electrolyte in the flow channel 200 can penetrate into the second wall 121.

[0074] In some embodiments, the pore size of the separator 120 is 1 μm to 5 μm. It should be explained that according to the Laplace equation, bubble penetration needs to overcome the bubble point pressure of the porous material:

[0075]

[0076] Among them, when the pore size d is small, the bubble point pressure increases significantly, and it is difficult for bubbles to penetrate the porous material. However, if the pore size d is too small, liquid penetration will be blocked, which will affect the reaction efficiency of the entire electrochemical device. For this reason, it is necessary to optimize the pore size to balance the bubble point pressure and the liquid penetration rate. Preferably, the pore size of the separator 120 is set to 1μm to 5μm. Within this range, the separator 120 can provide a larger bubble point pressure to limit the gas from penetrating toward the separator 120, and within this pore size range, the electrolyte in the flow channel 200 can also infiltrate the second wall 121 of the separator 120 through capillary action.

[0077] In some embodiments, the porosity of the isolation member 120 is 30% to 90%. It should be explained that the porosity refers to the proportion of the pore volume in the porous material to the total volume, which has an important influence on the liquid permeability and gas barrier ability. When the porosity is too low, the liquid circulation is restricted, which may cause uneven distribution of the liquid in the isolation member 120. When the porosity is too high, the bubble point pressure will decrease, and bubbles will more easily penetrate into the isolation member 120. Therefore, preferably, the porosity of the isolation member 120 is controlled within 30% to 90%. Within this range, it can not only ensure uniform penetration of the liquid, but also effectively prevent bubble penetration.

[0078] In some embodiments, any one of the electrode 110 and the separator 120 has a plurality of recessed portions 112, and each recessed portion 112 is arranged at intervals, and the spacing between adjacent recessed portions 112 is 50 μm to 200 μm, and the convex portion 122 is arranged correspondingly. It can be understood that the smaller the spacing, the larger the surface area of ​​the first wall 111 and the second wall 121, but it may cause bubbles to gather too densely, affecting the gas diffusion efficiency. Therefore, preferably, the spacing between adjacent recessed portions 112 is 50 μm to 200 μm.

[0079] In some embodiments, the separator 120 can be attached to the first wall 111 of the electrode 110 by a liquid phase in-situ synthesis process. The basic principle of the liquid phase in-situ synthesis process is to select the corresponding reactants under appropriate liquid phase conditions according to the design requirements of the material, and to generate a small-sized and uniformly distributed reinforcing phase or functional phase in situ on the matrix or carrier through chemical reactions. This process avoids the presence of intermediates or additives, improves the efficiency of material preparation, and the obtained material structure is purer, uniform and stable. In addition, this process is suitable for generating new coatings on more complex three-dimensional structures, such as generating the separator 120 on the first wall 111 of the electrode 110 of the present application.

[0080] The in-situ synthesis technology greatly reduces the manufacturing cost, realizes the tightness and high strength of the combination of the electrode 110 and the separator 120, reduces the probability of poor adhesion of the separator 120, has good scalability, and can be applied to large-scale production. In addition, high-precision manufacturing of complex geometric structures on the electrode 110 or the separator 120 can be achieved through 3D printing, CNC cutting and other technologies.

[0081] Based on the above, the two electrode assemblies 100 are spaced apart to define the flow channel 200. In some embodiments, the flow channel 200 is a through structure, that is, there is no other physical structure in the flow channel 200, and the electrolyte flows from one end of the flow channel 200 to the other end. Figure 7As shown, a partition structure is provided in the flow channel 200, and the partition structure may be a structure integrally formed with the separators 120 on both sides, or a structure independent of the separators 120 and connected to the separators 120 on both sides to play a supporting role. The partition structure has good fluid permeability, and although the partition structure divides the flow channel 200 into multiple chambers, the electrolyte can penetrate the partition structure into each chamber.

[0082] In other embodiments, Figure 8 As shown, a filling structure is provided in the flow channel 200, and the filling structure fills the flow channel 200. In order to realize regular penetration of the electrolyte in the flow channel 200, the fluid permeability of the filling structure is required to be higher than the fluid permeability of the isolation member 120. It should be noted that fluid permeability refers to the characteristic of the amount of liquid or gas passing through a porous body per unit time measured under specified conditions, that is, compared with the isolation member 120, the electrolyte is easier to infiltrate and penetrate into the filling structure, so that the electrolyte can first be stably and evenly penetrated in the flow channel 200, and then evenly penetrate from the filling structure into the isolation member 120.

[0083] It is understood that the above device can be used for traditional alkaline water hydrogen production, and water decomposition hydrogen production is carried out by alkaline electrolytes such as potassium hydroxide (KOH), which is suitable for industrial large-scale hydrogen production. In addition, the above device can also be used for proton exchange membrane electrolyzers (PEM electrolyzers) and anion exchange membrane electrolyzers (AEM electrolyzers), industrial wastewater treatment, chemical electrolysis production, fuel cells, etc.

[0084] The electrochemical device of the present application is used as a fuel cell as an example for specific description. For the convenience of distinction, the above two electrodes 110 are named as the first electrode and the second electrode respectively. The first electrode and the second electrode can be set to have catalytically active materials, such as platinum carbon (Pt / C) catalytic electrode, iridium oxide (IrO2) catalytic electrode, and any other electrode 110 suitable for fuel cells. By introducing hydrogen and oxygen into the first electrode and the second electrode respectively, corresponding electrochemical reactions occur at the first electrode and the second electrode, and current is generated.

[0085] Taking the first electrode as the positive electrode and the second electrode as the negative electrode as an example, when the electrochemical device is used as a fuel cell, oxygen is introduced into the first electrode to perform an oxygen reduction reaction (Oxygen Reduction Reaction, ORR) at the first electrode, and hydrogen is introduced into the second electrode to perform a hydrogen oxidation reaction (HOR) at the second electrode. The hydroxide ions generated at the first electrode react with the hydrogen ions at the second electrode to generate water, and accordingly, electrons flow out from the second electrode and flow into the first electrode via conductive devices such as cables to form an electric current.

[0086] The second aspect of the present application further proposes an electrochemical system, which includes a power source and the electrochemical device mentioned in any of the above embodiments, and the power source is electrically connected to the two electrodes 110. When the electrochemical system is used in the electrolysis of water, the electrochemical system also includes a gas collection device, which is connected to the two electrodes 110, respectively, for collecting and storing the gases generated by the two electrodes 110, so as to obtain relatively pure oxygen and hydrogen.

[0087] The third aspect of the present application provides a gas manufacturing process, which applies the above-mentioned electrochemical device or electrochemical system to the field of gas manufacturing, such as hydrogen manufacturing, ammonia manufacturing, etc. Specifically, the gas manufacturing process includes the following steps:

[0088] S100, prepare an electrochemical device, the electrochemical device includes two electrode assemblies 100, the electrode assemblies 100 include electrodes 110 and separators 120 connected to one side of the electrodes 100, the two electrode assemblies 100 are arranged at intervals, the two separators 120 are arranged on the opposite sides of the two electrodes 110, and a flow channel 200 is defined between the two separators 120, and the flow channel 200 is used for the flow of electrolyte. Among them, any one of the first wall 111 and the second wall 121 is provided with at least one recessed portion 112, and the other is provided with at least one raised portion 122, the first wall 111 and the second wall 121 are arranged in close contact, and the raised portion 122 is located in the recessed portion 112.

[0089] S200, delivering electrolyte to the flow channel 200. Specifically, the electrolyte may be delivered by an electric pump, or the electrochemical device may be placed vertically so that the flow channel 200 extends in the vertical direction, thereby placing the electrolyte storage and release mechanism above the flow channel 200, and the electrolyte flows spontaneously from top to bottom due to its own gravity.

[0090] S300, collecting generated gas from a side of the electrode assembly away from the flow channel.

[0091] It is understandable that the electrochemical system or electrochemical device may also include a gas collection mechanism, which is covered on the side of the electrode 110 facing away from the isolation member 120, so that when the gas penetrates from the first wall 111 to the outside of the electrode 110, the gas collection mechanism can collect and store the gas in time to reduce the probability of gas contamination.

[0092] The embodiments of the present invention are described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in the relevant technical field without departing from the purpose of the present invention. In addition, the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict.

Claims

1. An electrochemical device, characterized in that include: Two electrode assemblies, each comprising an electrode and a separator connected to one side of the electrode, the two electrode assemblies being spaced apart, the two separators being arranged opposite to each other, and defining a flow channel between the two separators, the flow channel being used for the flow of an electrolyte; Among them, the wall surface of the electrode used to connect with the isolation member is set as the first wall surface, and the wall surface of the isolation member used to connect with the electrode is set as the second wall surface, either one of the first wall surface and the second wall surface is provided with at least one recessed portion, and the other is provided with at least one raised portion, the first wall surface and the second wall surface are arranged in close contact, and the raised portion is located in the recessed portion.

2. The electrochemical device according to claim 1, characterized in that The second wall surface is provided with the protrusion, the interior of the protrusion is provided with a wetting channel, and one end of the wetting channel is communicated with the flow channel.

3. The electrochemical device according to claim 1, characterized in that The number of the recessed parts and the number of the raised parts are both multiple; Wherein, the single concave portion is in any one of an arc, a triangle, and a square shape, and the convex portion is in a shape that matches the concave portion; Alternatively, a single recessed portion is in a plug-in structure, and along a direction away from the first wall surface, an inner diameter of the plug-in structure gradually increases and then gradually decreases, and the protruding portion is in a shape that matches the recessed portion.

4. The electrochemical device according to claim 1, characterized in that The maximum depth of the recessed portion is 1 um to 5 mm, and the maximum width of the recessed portion is 1 um to 5 mm.

5. The electrochemical device according to claim 1, characterized in that The electrode is a gas evacuation structure, and the gas evacuation structure can guide the gas generated on the first wall surface in a direction away from the isolation element.

6. The electrochemical device according to claim 1, characterized in that The isolating member is a microfluidic liquid conducting structure, and the microfluidic liquid conducting structure can guide the electrolyte in the flow channel to the second wall surface.

7. The electrochemical device according to claim 6, characterized in that The porosity of the separator is 30% to 90%.

8. The electrochemical device according to claim 6, characterized in that The pore size of the separator is 1 μm to 5 μm, the electrode or the separator is provided with a plurality of recessed portions arranged at intervals, and the interval between adjacent recessed portions is 50 μm to 200 μm.

9. The electrochemical device according to claim 1, characterized in that The separator is attached to the first wall surface of the electrode by a liquid phase in-situ synthesis process.

10. The electrochemical device according to claim 1, characterized in that The flow channel is a through structure, and the electrolyte can flow from one end of the flow channel to the other end of the flow channel; Alternatively, a partition structure is provided in the flow channel, the partition structure divides the flow channel into a plurality of chambers, and the electrolyte can enter the chambers through the partition structure; Alternatively, a filling structure is provided in the flow channel, and the fluid permeability of the filling structure is higher than the fluid permeability of the isolation element.

11. An electrochemical system, characterized in that include: The electrochemical device according to any one of claims 1 to 10; A power source is electrically connected to the two electrodes respectively.

12. A gas manufacturing process, characterized in that The following steps are involved: S100, preparing an electrochemical device, wherein the electrochemical device comprises two electrode assemblies, wherein the electrode assemblies comprise electrodes and a separator connected to one side of the electrodes, wherein the two electrode assemblies are spaced apart, and the two separators are arranged opposite to each other, and a flow channel is defined between the two separators, wherein the flow channel is used for the flow of an electrolyte; wherein a wall surface of the electrode used to connect with the separator is set as a first wall surface, and a wall surface of the separator used to connect with the electrode is set as a second wall surface, wherein either the first wall surface or the second wall surface is provided with at least one recessed portion, and the other is provided with at least one raised portion, and the first wall surface and the second wall surface are arranged in close contact with each other, and the raised portion is located in the recessed portion; S200, transporting electrolyte to the flow channel; S300, collecting generated gas from a side of the electrode assembly away from the flow channel.

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