Electrochemical reactor

Abstract

An electrochemical reactor is provided. The electrochemical reactor includes a plurality of bipolar plates, a plurality of electrochemical reaction layers, each of which is disposed between a pair of bipolar plates among the plurality of bipolar plates, a pair of end plates disposed at both opposite outer sides of a stack formed by interleaving the plurality of bipolar plates and the plurality of electrochemical reaction layers, and a liquid inlet / outlet port fitting passing through a first hole formed in the end plate and installed in a second hole in an outermost bipolar plate among the plurality of bipolar plates located at the outermost side of the stack.

Description

Technical Field

[0001] This application relates generally to the field of electrochemical reactors, and more particularly to an electrolyzer. Background Technology

[0002] There are two main types of fluid inlet and outlet fittings for electrochemical reactors: flanged and pipe-fitted. Flange-fitting fittings are sometimes internally coated with ceramic materials and are typically used in larger systems. Pipe-fitting fittings are usually connected to the end plates by welding or threading, depending on the system's flow rate, and are generally suitable for smaller or modular systems. Since there is no current flowing through the end plates of an electrochemical reactor, the inlet and outlet fittings are primarily made of stainless steel or similar materials. These end plates incorporate numerous functions, and the design of each functional component is very complex, making assembly cumbersome. For example, the need for a sealing layer within the end plate further complicates the assembly process.

[0003] Therefore, simplifying the design of the end plates is an important issue, and thus there is a need to propose an electrochemical reactor that can solve these problems. Utility Model Content

[0004] This application provides an electrochemical reactor that, by rearranging the fluid inlet and outlet fittings of the electrochemical reactor stack, provides a simple, easy-to-assemble, lightweight design for the end plates.

[0005] The electrochemical reactor provided in this application includes: Multiple bipolar plates; Multiple electrochemical reaction layers, each electrochemical reaction layer being disposed between a pair of bipolar plates in the plurality of bipolar plates; A pair of end plates are disposed on opposite outer sides of a stack, the stack being formed by alternating stacking of the plurality of bipolar plates and the plurality of electrochemical reaction layers; and The inlet / outlet fitting passes through the first hole of the end plate and is installed in the second hole of the outermost bipolar plate, wherein the outermost bipolar plate is the outermost bipolar plate among the plurality of bipolar plates located in the stack.

[0006] Optionally, the electrochemical reactor further includes an insulating coating applied to the second hole wall in the outermost bipolar plate where the second hole is formed, or to the portion of the inlet / outlet fitting that contacts the second hole wall.

[0007] Optionally, the electrochemical reactor further includes a first sleeve disposed in the second hole and having a first channel for accommodating the inlet / outlet fittings.

[0008] Optionally, the first sleeve is made of a dielectric material or an insulating material.

[0009] Optionally, the first sleeve includes a first insulating coating applied to a first surface of the first sleeve, and the first surface includes a first inner wall forming the first channel in the first sleeve, or a first outer wall of the first sleeve.

[0010] Optionally, the electrochemical reactor further includes: A connector is inserted into the second hole of the outermost bipolar plate and has an inner channel communicating with the second hole; The second sleeve has a second channel communicating with the inner channel of the connector, and has an enlarged portion for accommodating the inlet / outlet fittings; and Fasteners are used to secure the second sleeve to the connector.

[0011] Optionally, the second sleeve includes a second insulating coating applied to a second surface of the second sleeve, and the second surface includes a second inner wall forming the second channel in the second sleeve, or a second outer wall of the second sleeve.

[0012] Optionally, the second sleeve or the connector may be made of a dielectric material or an insulating material.

[0013] Optionally, the electrochemical reactor further includes: A current collector is disposed between the end plate and the outermost bipolar plate; and An insulating plate is disposed between the end plate and the current collector plate; The insulating plate and the collector plate are respectively provided with through holes for the liquid inlet and outlet fittings to pass through.

[0014] Optionally, the electrochemical reactor is one of an electrochemical water electrolyzer, a fuel cell, or a flow battery. Each of the electrochemical reaction layers includes a pair of electrodes and at least one of a separator layer, a catalyst layer, an electrolyte layer, or a transport layer sandwiched between the electrodes. The thickness of the outermost bipolar plate is greater than the thickness of the bipolar plate located inside the outermost bipolar plate in the stack. Attached Figure Description

[0015] The technical solution and other beneficial effects of this application will become apparent from the following detailed description of specific embodiments in conjunction with the accompanying drawings.

[0016] Figure 1 This is a cross-sectional schematic diagram of an electrochemical reactor stack provided according to relevant embodiments of this application.

[0017] Figure 2 This is a partial cross-sectional schematic diagram of an electrochemical reactor stack provided according to an embodiment of this application.

[0018] Figure 3a This is another partial cross-sectional schematic diagram of an electrochemical reactor stack provided according to an embodiment of this application.

[0019] Figure 3b This is another partial cross-sectional schematic diagram of an electrochemical reactor stack provided according to an embodiment of this application.

[0020] Figure 4a This is another partial cross-sectional schematic diagram of an electrochemical reactor stack provided according to an embodiment of this application.

[0021] Figure 4b Provided according to embodiments of this application Figure 4a The diagram shows an enlarged cross-sectional view of the first sleeve.

[0022] Figure 5a This is another partial cross-sectional schematic diagram of an electrochemical reactor stack provided according to an embodiment of this application.

[0023] Figure 5b Provided according to the embodiments of this application Figure 5a The diagram shows an enlarged cross-sectional view of the second sleeve. Detailed Implementation

[0024] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0025] It should be understood that although the terms first, second, etc., may be used herein to describe various components, these components should not be limited to these terms. These terms are used to distinguish one component from another. For example, a first component may be referred to as a second component, and similarly, a second component may be referred to as a first component, without departing from the scope of this application.

[0026] It should be understood that when a component is said to be "on" or "connected" to another component, it can be directly on or connected to the other component, or there may be an inserted component. Other terms used to describe relationships between components should be interpreted in a similar manner.

[0027] It should be noted that the illustrations provided in the embodiments of this application are only schematic representations of the basic concept of this application. Although the illustrations only show the components related to this application and are not drawn according to the actual number, shape and size of the components, the form, quantity and proportion of each component in actual implementation can be arbitrarily changed, and the layout of the components may also be more complex.

[0028] Proton exchange membrane (PEM) water electrolyzers, a type of electrochemical reactor, are key components in modern hydrogen production systems. These electrolyzers utilize proton-conducting membranes to efficiently split water into hydrogen and oxygen, providing a clean and sustainable method for hydrogen fuel production. Their compact design, high efficiency, and adaptability make them ideal for a variety of applications, from industrial uses to renewable energy integration. These electrochemical reactors are characterized by the input and output of fluids during the electrochemical reaction; examples include water electrolyzers, fuel cells, and flow batteries.

[0029] First, please refer to Figure 1 , Figure 1 This is a schematic diagram of the structure of an electrochemical reactor provided according to relevant embodiments of this application. The electrochemical reactor described herein includes an electrolytic cell, or electrolytic cell stack, which is a container for carrying out electrochemical reactions. It typically contains a positive electrode and a negative electrode to achieve the exchange of electrical and chemical energy, while also allowing for fluid input and output. Such containers are usually rectangular or cylindrical and made of corrosion-resistant materials such as glass, plastic, or metal to ensure the stability and safety of the reaction.

[0030] Electrochemical reactors have a wide range of applications, including water electrolysis, fuel cells, and flow batteries. As a water electrolyzer, it electrolyzes water to produce hydrogen and oxygen; as a fuel cell, it generates electricity through the reaction of hydrogen and oxygen; and as a flow battery, it stores energy or generates electricity through the redox reactions of chemicals in a fluid. Therefore, an electrochemical reactor can include one of the following: an electrochemical water electrolyzer (PEM, AEM, ALK), a fuel cell, or a flow battery. Each electrochemical reaction layer in the electrochemical reactor includes a pair of electrodes and at least one of the following functional layers sandwiched between the electrodes: a separator layer, a catalyst layer, an electrolyte layer, or a transport layer. The applications shown above are merely examples, and this application is not limited thereto. This document will primarily use water electrolyzers as examples.

[0031] like Figure 1 As shown, Figure 1The electrochemical reactor 1 shown includes: a plurality of bipolar plates (BPPs) 100; a plurality of electrochemical reaction layers 200 as membrane electrode assemblies (MEAs), each electrochemical reaction layer 200 being disposed between two adjacent bipolar plates among the plurality of bipolar plates; a pair of end plates 300a disposed on two opposite outer sides of a stack formed by the plurality of bipolar plates 100 and the plurality of electrochemical reaction layers 200 stacked alternately; at least one inlet / outlet fitting 400 mounted on at least one end plate 300a; an insulating plate 500 and a current collector plate (current collector plate) 600, both disposed between the end plates 300a and the bipolar plates 100; and fastening components, including bolts 700 and nuts 701, for fastening all components between the end plates 300a to form an electrochemical reactor stack. It is understood that the components of the electrochemical reactor listed herein are merely examples and not limitations. The design of these fasteners and other auxiliary components, such as inlet / outlet fittings, is not limited to the illustrations and can be varied and added according to actual needs. Each electrochemical reaction layer 200 includes a pair of electrodes 201, which includes an anode and a cathode electrode, and at least one of the functional layers sandwiched between the pair of electrodes, such as a separator layer, catalyst, electrolyte layer, or transport layer. The electrolyte layer can be a proton exchange membrane (PEM), an anion exchange membrane (AEM), or an alkaline electrolysis membrane (ALK), etc., to constitute the aforementioned electrochemical water electrolyzer. Furthermore, if the end plate 300a shown in Figure 1 is made of a non-conductive material, the insulating plate 500 can be omitted. The inlet / outlet fitting 400 can be an inlet / outlet sleeve or any suitable inlet / outlet connector.

[0032] The bipolar plate (BPP) 100 has multiple functions, including uniformly distributing the reactant fluid on the electrochemical reaction layer 200, transferring the reaction product fluid out of the electrochemical reaction layer, conducting heat and electricity for the electrochemical layer 200, and providing structural support. In this embodiment, the BPP 100 is made of metal or composite material and has complex fluid channels to optimize battery performance.

[0033] Electrochemical reactor 1 also includes gaskets and a sealing system (not shown) to ensure no fluid leakage and maintain the overall integrity of the system. The gaskets and sealing system are designed to maintain a tight seal while meeting the demands of real-world operating conditions, such as withstanding high pressure and high temperature, and resisting fluid corrosion to prevent it from affecting the electrochemical reaction, especially when circulating fluids are used. End plates help hold the electrolyzer stack together, applying uniform pressure to ensure optimal contact between components and stack performance. They typically also house inlet and outlet fittings for gas and water flows. Together, these components constitute a highly efficient and durable electrolyzer stack capable of meeting the needs of modern electrochemical reaction systems.

[0034] End plate 300a and fastening devices (e.g., nuts 701 and bolts 700) provide structural support for electrochemical reactor 1, securing all components (bipolar plate 100, electrochemical reaction layer 200, etc.) in the correct positions to ensure uniform pressure and prevent fluid leakage. This configuration provides a highly efficient and durable water electrolyzer stack (or electrochemical reactor stack) capable of meeting the needs of modern hydrogen production systems. Therefore, end plate 300a is very thick and must be rigid.

[0035] Since no current flows through the endplate 300a, the inlet / outlet fittings 400 are primarily made of stainless steel or similar materials. Considering the numerous functions of the endplate 300a, the design of the component is highly complex and assembly cumbersome. Many studies have focused on applying topology optimization or numerical simulation techniques to design lightweight endplates while ensuring consistent pressure distribution, finding this very challenging. Reducing the endplate size offers significant advantages for modular stack design and its assembly. Another important function of commercial endplate designs is the supply or distribution of reactants (e.g., water). To supply / remove reactants and products, the endplate 300a needs to be larger / thicker to accommodate the inlet / outlet fittings (as shown in Figure 1), further increasing the weight and complexity of the component. Furthermore, seals are required between each component between the outermost bipolar plate and the endplate at the fluid inlet / outlet locations, such as… Figure 1 In the range of 100 and 600, 600 and 500, and 500 and 300, more auxiliary components are required, leading to a more complex sealing design. Furthermore, the more sealing materials used, the greater the likelihood of seal failure or fluid contamination due to performance degradation or corrosion. Additionally, the abundance of sealing materials increases assembly difficulty. According to one embodiment of this application, a further provision is provided... Figure 2 The electrochemical reactor 2 is shown. In Figure 2 In the electrochemical reactor 2 shown, the endplates are simplified by removing the functions of supplying and removing reactants and products, thereby achieving a simple, easy-to-assemble, lightweight design.

[0036] like Figure 2As shown, the electrochemical reactor 2 mainly includes: multiple bipolar plates (BPP) 100; multiple electrochemical reaction layers 200, each electrochemical reaction layer 200 being disposed between a pair of adjacent bipolar plates in the multiple bipolar plates; a pair of end plates 300, disposed on the two opposite outer sides of a stack formed by the multiple bipolar plates 100 and the multiple electrochemical reaction layers 200 stacked alternately; and inlet / outlet fittings 400, passing through a first hole 301 formed on one of the end plates and installed in a second hole 101 on the outermost bipolar plate 100a located at the outermost end of the stack in the multiple bipolar plates.

[0037] and Figure 1 Similar to the electrochemical reactor 1 shown, the electrochemical reactor 2 also includes an insulating plate 500 and a current collector 600 disposed between the end plate 300a and the bipolar plate 100; and fastening components including bolts 700 and nuts 701. Each electrochemical reaction layer 200 also includes a pair of electrodes 201 including an anode and a cathode, and at least one of a functional layer sandwiched between the pair of electrodes, such as a separator layer, a catalyst, an electrolyte layer, or a transport layer, wherein the electrolyte layer can be a proton exchange membrane (PEM), an anion exchange membrane (AEM), or an alkaline electrolytic membrane (ALK). Similarly, if the end plate 300a shown in FIG. 1 is made of a non-conductive material, the insulating plate 500 can be omitted. Furthermore, the insulating plate 500 and the current collector 600 are generally required for the electrochemical reactor 2, but can also be achieved by plating an insulating layer on the surface of the current collector. Furthermore, in some embodiments, if the current collector is directly grounded, i.e., at a potential of around 0V, an insulating plate may not be necessary, or the outermost bipolar plate may be used directly as the current collector, eliminating the need for an additional current collector. Therefore, the insulating plate 500 and the current collector 600 are not absolutely essential and can be varied in many ways.

[0038] By separating the end plate from the function of supplying / distributing fluid inlet and outlet, that is, by directly connecting the inlet / outlet fittings 400 used for supplying / distributing fluid to the outermost bipolar plate 100a, the sealing requirements between the components located outside the outermost bipolar plate are eliminated, while reducing the weight of the end plate and the difficulty of assembly.

[0039] 400 bypasses end plate 300, insulating plate 500, and current collector plate 600, and connects directly to the outermost BPP 100a. The thickness of the outermost BPP 100a is adjustable according to the size and flow rate of the inlet / outlet fitting 400 to accommodate it. Therefore, in some embodiments, the thickness of the outermost bipolar plate 100a is greater than the thickness of the other bipolar plates 100 in the electrochemical reactor stack, i.e., the thickness of the bipolar plates 100 inside the outermost bipolar plate 100a.

[0040] The inlet / outlet fitting 400 can be installed into the second hole 101 on the outermost bipolar plate 100a in any known manner. For example, it can be glued, threaded, welded, extruded, or any other available method.

[0041] pass Figure 2 The structure shown eliminates the need for sealing at the interfaces between the end plate 300 and the insulating plate 500, the insulating plate 500 and the current collector plate 600, and the current collector plate 600 and the outermost BPP plate 100a, thereby reducing loose components and seals in the system and potentially lowering the likelihood of leakage during operation.

[0042] Figure 3a shows an enlarged cross-sectional view of the inlet / outlet fittings 400 in the electrochemical reactor 2 and the periphery of the second hole 101 formed on the outermost bipolar plate 100a. As shown in Figure 3a, the insulating plate 500 and the current collector plate 600 are also provided with through holes 501 / 601 for the inlet / outlet fittings 400 to pass through. The areas on the insulating plate 500 and the current collector plate 600 that intersect with the inlet / outlet fittings have larger holes / gap sizes to prevent interference with the inlet / outlet fittings.

[0043] As previously mentioned, since the materials of the general inlet / outlet fittings 400 and end plate 300 are mainly stainless steel or similar materials, directly connecting the general inlet / outlet fitting 400 to the outermost BPP 100a would cause current to flow through the inlet / outlet fitting, potentially leading to corrosion, battery contamination, and unnecessary current in other components of the PEM electrolyzer system. Therefore, if the inlet / outlet fitting 400 is not made of a non-conductive material, a dielectric coating or electrically insulating layer must be formed in certain parts or areas of the inlet / outlet fitting 400, or on the second hole wall used to accommodate the inlet / outlet fitting 400, to insulate the inlet / outlet fitting 400, as further explained below.

[0044] Figure 3b An embodiment of this application is shown, in which the outermost bipolar plate 100 of the electrochemical reactor 2a further includes an insulating coating 102 coated on the second hole wall 101a forming the second hole 101 in the outermost bipolar plate 100a, so as to electrically insulate the inlet / outlet fitting 400 from the outermost bipolar plate 100a. Furthermore, it is understood that the insulating coating 102 may also be coated on the portion of the inlet / outlet fitting 400 that comes into contact with the second hole wall 101a when inserted into the second hole 101 (not shown). Various methods are acceptable as long as electrical insulation between the outermost bipolar plate 100a and the inlet / outlet fitting 400 can be achieved, and this is not a limitation.

[0045] In addition, any coating material that can shield and protect electrical equipment from environmental factors such as moisture, chemicals, and extreme temperatures can be used. This protection is crucial for maintaining system reliability and lifespan under harsh operating conditions. Selecting a specific insulation formulation for a particular application requires not only ideal dielectric properties but also consideration of many other characteristics, such as physical and mechanical strength, chemical resistance, operating temperature range and thermal cycling, dimensional stability, and resistance to shock and vibration.

[0046] Furthermore, in order to electrically insulate the inlet / outlet fittings 400 from the outermost bipolar plate 100a, Figure 4a An alternative structure according to another embodiment of this application is shown. For example... Figure 4a As shown, with Figure 3a Compared to the structure in the previous one, the electrochemical reactor 3 also includes a first sleeve 10, which is disposed in the second hole 101 of the outermost bipolar plate 100a, that is, disposed between the inlet / outlet fitting 400 and the second hole wall 101a that forms the second hole 101 in the outermost bipolar plate 100a, and is provided with a first channel 11 to accommodate the inlet / outlet fitting 400.

[0047] As previously mentioned, in order to electrically insulate the inlet / outlet fitting 400 from the outermost bipolar plate 100a, the first sleeve 10 can be made of a dielectric or insulating material. When the first sleeve 10 itself is non-conductive, the structure between the inlet / outlet fitting 400 and the second hole wall 101a of the outermost bipolar plate 100a can be as follows: Figure 4a As shown.

[0048] However, in some embodiments, the first sleeve may be made of titanium (or any non-corrosive material) because of its high corrosion resistance. For example... Figure 3b and Figure 4b As shown, if the material of the first sleeve 10' is conductive, then it is necessary to apply a conductive coating to the outer surface of the first sleeve 10'. Figure 4b ), or on the second hole wall 101a in the outermost bipolar plate 100a forming the second hole 101 ( Figure 3b Alternatively, an insulating coating may be added to the surface of the inlet / outlet fitting 400 that contacts the second hole wall 101a. The outer surface of the first sleeve 10' may be the first inner wall (11a) forming the first channel 11 in the first sleeve 10', or the first outer wall (11b) of the first sleeve 10. In short, various insulation methods can be used as long as electrical isolation can be achieved between the inlet / outlet fitting 400 and the outermost bipolar plate 100a, and are not limited to the aforementioned methods.

[0049] exist Figure 4a The first sleeve 10 is added as shown. Figure 4bIn the embodiment shown with the addition of the first sleeve 10', damage to the second hole wall 101a forming the second hole 101 in the outermost BPP 100a can be avoided when operating the inlet / outlet fitting 400, thereby increasing the service life of the outermost BPP 100a.

[0050] Figure 5a An electrochemical reactor 4 according to yet another embodiment of this application is shown. (As shown) Figure 5a As shown, electrochemical reactor 4 and Figure 3a Compared to the electrochemical reactor 2 shown, between the outermost bipolar plate 100a and the inlet / outlet fittings 400, it also includes: Connector 20, inserted into the second hole, and having an inner channel (21) communicating with the second hole; The second sleeve 30 has a second channel 31, which communicates with the inner channel 21 of the connector, and has an enlarged portion 31-1 for accommodating the inlet / outlet fitting 400; and Fastener 40 secures the second sleeve to the connector. (twenty one); Specifically, the second sleeve 30 is used to accommodate the inlet / outlet fitting 400, and the fastener 7 can fix the second sleeve 30 to the connector 20. By fixing the connector 20 to the outermost BPP 100a and fixing the inlet / outlet fitting 400 to the enlarged portion 31-1 of the second channel 31 of the second sleeve 30, the inlet / outlet fitting 400 can be connected to the second hole 101 of the outermost BPP 100a, thereby achieving the purpose of fixing the inlet / outlet fitting 400 to the outermost BPP 100a.

[0052] By using this three-piece fitting consisting of connector 20, second sleeve 30, and fastener 40, when the inlet / outlet fitting 400 is fixed to the second hole 101 on the outermost BPP 100a, damage to the outermost BPP 100a can be avoided when operating the inlet / outlet fitting 400 because the connector 20 extends away from the outermost BPP 100a.

[0053] As with the first sleeve 10 described in the previous embodiment, various insulation methods can be implemented as long as the inlet / outlet fitting 400 can achieve electrical insulation with the outermost BPP 100a. That is, a second insulating coating 32 can be applied to the second surface of the second sleeve 30', and the second surface includes the second inner wall 31a in which the second channel 31 is formed in the second sleeve 30', or the second outer wall 31b of the second sleeve 30'. Figure 5bThe example shown is particularly an example of applying a second insulating coating 32 to the second inner wall 31a forming the second channel 31. In this example, the second sleeve 30' can be made of the same material as the first sleeve 10, such as titanium, or any non-corrosive material.

[0054] As shown in the first sleeve 10 above, the second sleeve 30 or connector 20 can also be made of dielectric or insulating material, thus eliminating the need for an insulating coating. Figure 5a As shown.

[0055] The aforementioned insulating coating, or the single-piece first sleeve 10, or the three-piece connector 20 + second sleeve 30 + fastener 40, all constitute an insulating component between the second hole wall 101a of the outermost BPP 100a and the inlet / outlet fitting 400, and can achieve the purpose of insulation in various ways.

[0056] The electrochemical reactor disclosed in this application facilitates easier assembly of the electrochemical reactor stack because the inlet / outlet fittings or sleeves are directly connected to the BPP. Furthermore, the inlet / outlet fittings pass through the end plates, reducing the size and weight of the end plates and thus the overall weight of the PEM electrolyzer. Since the end plates no longer need to accommodate the inlet / outlet fittings, their thickness can be reduced, further reducing the overall weight of the PEM electrolyzer and allowing for a smaller overall size of the PEM electrolyzer system, which is beneficial for modular stack design. Moreover, the inlet / outlet fittings are independent of the end plates, simplifying the operation during the compaction of the electrochemical reactor stack.

[0057] Furthermore, by eliminating one function of the endplate—the need to supply / remove reactants and products—there are fewer interfaces between components outside the BPP (endplate-insulator, insulation-current collector, and current collector-BPP), simplifying the sealing design and reducing the amount of sealing material required. This reduces the contamination of the stack by the sealing material, thereby potentially reducing the likelihood of leakage during operation and reducing the electrical activity bypass.

[0058] In embodiments with a coating, the coated input / output connector fittings can be used in all ranges of PEM electrolyzers (high-voltage to low-voltage electrolyzers) depending on the coating thickness and dielectric properties.

[0059] The above description of the embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application; those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. An electrochemical reactor, characterized in that... include: Multiple bipolar plates (100); Multiple electrochemical reaction layers (200), each electrochemical reaction layer being disposed between a pair of bipolar plates in the plurality of bipolar plates; A pair of end plates (300) are disposed on the two opposite outer sides of a stack, the stack being formed by alternating stacking of the plurality of bipolar plates and the plurality of electrochemical reaction layers; as well as The inlet / outlet fitting (400) passes through the first hole (301) of the end plate and is installed in the second hole (101) of the outermost bipolar plate (100a), the outermost bipolar plate being the outermost one of the plurality of bipolar plates located in the stack.

2. The electrochemical reactor as described in claim 1, characterized in that, The electrochemical reactor further includes an insulating coating (102) applied to the second hole wall (101a) forming the second hole in the outermost bipolar plate, or to the portion of the inlet / outlet fitting that contacts the second hole wall.

3. The electrochemical reactor as described in claim 1, characterized in that, The electrochemical reactor further includes a first sleeve (10) disposed in the second hole and having a first channel (11) for accommodating the inlet / outlet fittings.

4. The electrochemical reactor as described in claim 3, characterized in that, The first sleeve (10) is made of dielectric material or insulating material.

5. The electrochemical reactor as described in claim 3, characterized in that, The first sleeve (10) includes a first insulating coating (12) applied to a first surface of the first sleeve, and the first surface includes a first inner wall (11a) forming the first channel in the first sleeve, or a first outer wall (11b) of the first sleeve.

6. The electrochemical reactor as described in claim 1, characterized in that, The electrochemical reactor also includes: A connector (20) is inserted into the second hole of the outermost bipolar plate and has an inner channel (21) communicating with the second hole; The second sleeve (30) has a second channel (31) communicating with the inner channel (21) of the connector, and has an enlargement (31-1) for accommodating the inlet / outlet fitting (400); and Fastener (40) secures the second sleeve to the connector.

7. The electrochemical reactor as described in claim 6, characterized in that, The second sleeve (30) includes a second insulating coating (32) applied to a second surface of the second sleeve, and the second surface includes a second inner wall (31a) forming the second channel in the second sleeve, or a second outer wall (31b) of the second sleeve.

8. The electrochemical reactor as described in claim 6, characterized in that, The second sleeve (30) or the connector (20) is made of a dielectric material or an insulating material.

9. The electrochemical reactor as described in claim 1, characterized in that, The electrochemical reactor also includes: A current collector (600) is disposed between the end plate (300) and the outermost bipolar plate (100a); and An insulating plate (500) is disposed between the end plate (300) and the current collector plate (600); The insulating plate and the collector plate are respectively provided with through holes for the liquid inlet and outlet fittings to pass through.

10. The electrochemical reactor as claimed in claim 1, characterized in that, The electrochemical reactor is one of an electrochemical water electrolyzer, a fuel cell, or a flow battery. Each of the electrochemical reaction layers (200) includes a pair of electrodes and at least one of a separator layer, a catalyst layer, an electrolyte layer, or a transport layer sandwiched between the electrodes. The thickness of the outermost bipolar plate (100a) is greater than the thickness of the bipolar plate located inside the outermost bipolar plate in the stack.

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