Electrochemical device

Abstract

The present invention belongs to the technical field of electrochemistry. Disclosed is an electrochemical device. The electrochemical device comprises an electrochemical stack and a first hydrogen generating device, wherein the electrochemical stack has a first reaction zone inlet, a first reaction zone and a first reaction zone outlet, and the first reaction zone inlet and the first reaction zone outlet are in communication with the first reaction zone; the first reaction zone inlet of the electrochemical stack is connected to an outlet of the first hydrogen generating device; and the first hydrogen generating device is filled with a first hydrogen generating material. In the present invention, the first hydrogen generating material filling the first hydrogen generating device is used to react with water vapor to consume the water vapor, and at the same time, hydrogen produced by the reaction enters the electrochemical stack to serve as a protective gas that can protect a catalyst in the electrochemical stack; and the oxidized first hydrogen generating material can be reduced by means of a reductive fluid, such that the first hydrogen generating material can be recycled, thereby achieving a long service life and low cost.

Description

An electrochemical device Technical Field

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

[0002] The mutual conversion between electrical energy and chemical energy is achieved through a variety of electrochemical devices, such as fuel cells and electrolyzers. Common fuel cells include alkaline fuel cells (AFC), phosphoric acid fuel cells (PAFC), molten carbonate fuel cells (MCFF), proton exchange membrane fuel cells (PEMFC), direct methanol fuel cells (DMFC), solid oxide fuel cells (SOFC), etc.; common electrolyzers include alkaline electrolyzers (AWE), proton exchange membrane water electrolyzers (PEMWE), anion exchange membrane water electrolyzers (AEMWE), solid oxide electrolyzers (SOEC), etc. Among them, solid oxide fuel cells (SOFC) and solid oxide electrolyzers (SOEC) can be collectively referred to as solid oxide cells (SOC). Solid oxide cells (SOC) are advanced electrochemical energy conversion devices with broad application prospects in the fields of clean energy generation and CO2 conversion. Solid oxide fuel cell (SOFC) is an energy conversion device that can directly convert the chemical energy stored in fuel and oxidant into electrical energy. It has a high operating temperature, usually in the range of 700-1000℃, so its waste heat can be used to achieve combined heat and power while generating electricity, and the energy utilization efficiency can be as high as 90%. Solid oxide electrolyzer (SOEC) is an electrochemical energy conversion device that converts electrical energy and thermal energy into chemical energy. Its reaction is the reverse reaction of solid oxide fuel cell. As one of the main technical routes for hydrogen production by electrolysis of water today, SOEC usually operates at 700-850℃, with an electrolysis efficiency of up to 85-95%. Solid oxide fuel cells and solid oxide electrolyzers can use the same electrochemical stack for reaction. The difference is that the anode side of the solid oxide fuel cell serves as the cathode side in the solid oxide electrolyzer. For example, on the anode side of the solid oxide fuel cell, hydrogen molecules (H2) lose electrons (e - ) is oxidized to H + , while hydrogen ions (H + ) obtains electrons (e - ) is reduced to hydrogen (H2).

[0003] In SOFCs, when using fuels other than hydrogen, the fuel must be reformed through steam reforming, partial oxidation, catalytic cracking, and other methods before entering the anode. In SOECs, water vapor and hydrogen are passed together as reactant gases to the SOEC cathode. The catalysts in the SOFC anode and SOEC cathode are typically easily oxidized metals or alloys (such as nickel). During normal operation of the electrochemical stack, the catalysts remain in a reduced state due to being in a reducing atmosphere (H2). However, when the system stops supplying the reducing fluid (here, the reducing fluid refers to the fuel flowing to the anode side in SOFCs and the hydrogen flowing to the cathode side in SOECs, the same below) due to an emergency stop or failure, the catalysts in the electrochemical stack will inevitably be invaded by external gases, causing the catalysts to fail. Currently, existing technologies generally adopt methods such as sacrificial metals, rapid cooling, and inert gas flow to prevent the electrochemical stack from being invaded by external gases and causing catalyst failure. However, existing technologies still have many problems: 1. Complex operation and high cost; 2. Inadequate utilization of water vapor; 3. Insufficient consideration of the hazards and effects of water vapor. Water vapor can cause certain intrusion and damage to the electrochemical stack, for example, oxidizing the catalyst on the anode side of the SOFC or the catalyst on the cathode side of the SOEC.

[0004] Therefore, it is very necessary to develop an electrochemical device that can make full use of water vapor while avoiding catalyst failure caused by water vapor oxidation. Summary of the Invention

[0005] Based on the defects of the prior art, the object of the present invention is to provide an electrochemical device.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is:

[0007] An electrochemical device includes an electrochemical stack and a first hydrogen generating device. The electrochemical stack has a first reaction zone inlet, a first reaction zone, and a first reaction zone outlet. The first reaction zone inlet and the first reaction zone outlet are respectively connected to the first reaction zone. The first reaction zone inlet of the electrochemical stack is connected to the outlet of the first hydrogen generating device. The first hydrogen generating device has a structure that is hollow inside and open at both ends. The inlet of the first hydrogen generating device is used to receive a reducing fluid and / or water vapor. The first hydrogen generating device is filled with a first hydrogen generating material. The material of the first hydrogen generating material is a reducing metal or a reducing alloy. The first hydrogen generating material is used to react with water vapor.

[0008] As a preferred embodiment of the present invention, the first hydrogen generating material has a porous structure, and the porosity of the first hydrogen generating material is 10-300 ppi.

[0009] As a preferred embodiment of the present invention, the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the first hydrogen generating material in the first hydrogen generating device is P1, and the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the catalyst in the first reaction zone is P2. When the electrochemical device is operating normally, the hydrogen partial pressure in the first hydrogen generating device is P3, where P3>P1. When the inlet of the first hydrogen generating device does not receive a reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack is P4, where P4>P2. If P3<P1 during normal operation of the electrochemical device, the first hydrogen generating material in the first hydrogen generating device has been oxidized. If the inlet of the first hydrogen generating device does not receive a reducing fluid due to an emergency stop or failure of the electrochemical device, the first hydrogen generating material no longer has the ability to react with water vapor to generate hydrogen protective gas. If P4<P2 when the inlet of the first hydrogen generating device does not receive a reducing fluid, the catalyst in the first reaction zone of the electrochemical stack 1 is oxidized, causing irreversible damage.

[0010] As a preferred embodiment of the present invention, the electrochemical stack is a solid oxide fuel cell, and the electrochemical device further includes a reformer, wherein the outlet of the reformer, the first hydrogen generating device and the inlet of the first reaction zone of the electrochemical stack are connected in sequence.

[0011] As a preferred embodiment of the present invention, the electrochemical stack is a solid oxide electrolysis cell, and the electrochemical device further includes a mixer, wherein the outlet of the mixer, the first hydrogen generation device and the inlet of the first reaction zone of the electrochemical stack are connected in sequence.

[0012] As a preferred embodiment of the present invention, the outlet of the first reaction zone of the electrochemical stack is connected to a second hydrogen generating device. The second hydrogen generating device is a structure that is hollow inside and open at both ends. A second hydrogen generating material is arranged in the second hydrogen generating device. The material of the second hydrogen generating material is a reducing metal or a reducing alloy. The second hydrogen generating material is used to react with water vapor.

[0013] Furthermore, the second hydrogen generating material has a porous structure, and the porosity of the second hydrogen generating material is 10-300 ppi.

[0014] Furthermore, the electrochemical stack is a solid oxide fuel cell, and the electrochemical device further includes a burner. The outlet of the first reaction zone of the electrochemical stack, the second hydrogen generation device, and the inlet of the burner are connected in sequence.

[0015] Furthermore, the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the second hydrogen generating material in the second hydrogen generating device is P5, and the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the catalyst in the first reaction zone is P2. When the electrochemical device is operating normally, the hydrogen partial pressure in the second hydrogen generating device is P6, where P6>P5. When the inlet of the first hydrogen generating device does not receive the reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack is P4, where P4>P2. If P6<P5 during normal operation of the electrochemical device, the second hydrogen generating material in the second hydrogen generating device has been oxidized. If the inlet of the first hydrogen generating device does not receive the reducing fluid due to an emergency stop or failure of the electrochemical device, the second hydrogen generating material cannot consume the refluxed water vapor and provide sufficient hydrogen, thus losing its protective effect on the electrochemical stack. If P4<P2 when the inlet of the first hydrogen generating device does not receive the reducing fluid, the catalyst in the first reaction zone of the electrochemical stack 1 is oxidized, causing irreversible damage.

[0016] It can be understood that in the present invention, the hydrogen partial pressure in the first reaction zone of the electrochemical stack and the hydrogen partial pressure in the hydrogen generation device are tested as follows: the concentration of hydrogen in the gas in the corresponding area is obtained by electron bombardment mass spectrometry, and then the hydrogen partial pressure is calculated according to the following formula: hydrogen partial pressure = hydrogen concentration * standard atmospheric pressure.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] The present invention provides a first hydrogen generating device at the entrance of the first reaction zone of the electrochemical stack. When the electrochemical device loses its supply of reducing fluid, the first hydrogen generating material contained within the first hydrogen generating device reacts with water vapor, consuming the water vapor. The hydrogen produced by the reaction simultaneously enters the electrochemical stack as a shielding gas, protecting the catalyst within the electrochemical stack. This prevents catalyst failure caused by water vapor oxidation while fully utilizing the water vapor. When the electrochemical device resumes its supply of reducing fluid, the oxidized first hydrogen generating material can be reduced by the reducing fluid, making the first hydrogen generating material recyclable, extending its service life, and reducing costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] FIG1 is a schematic structural diagram of an electrochemical device provided in one embodiment of the present invention;

[0020] FIG2 is a schematic structural diagram of an electrochemical device provided in another embodiment of the present invention;

[0021] FIG3 is a graph showing a voltage variation trend of the fuel cell provided by the present invention before and after the supply of the reducing fluid is stopped.

[0022] In the figure, 1-electrochemical stack, 2-first hydrogen generating device, 3-first hydrogen generating material, 4-reformer, 5-mixer, 6-second hydrogen generating device, 7-second hydrogen generating material, 8-burner, 9-pressurized storage system. DETAILED DESCRIPTION

[0023] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below with reference to specific embodiments and comparative examples. The purpose is to provide a detailed understanding of the content of the present invention, but not to limit the present invention. All other embodiments obtained by those of ordinary skill in the art without creative work are within the scope of protection of the present invention.

[0024] Referring to Figures 1-2, the present invention provides an electrochemical device comprising an electrochemical stack 1 having a first reaction zone inlet, a first reaction zone, and a first reaction zone outlet, the first reaction zone inlet and the first reaction zone outlet respectively communicating with the first reaction zone. A first hydrogen generator 2 is a hollow structure with two open ends. The first reaction zone inlet of the electrochemical stack 1 is connected to the outlet of the first hydrogen generator 2. The inlet of the first hydrogen generator 2 is used to receive a reducing fluid and / or water vapor. The reducing fluid and / or water vapor flows through the first hydrogen generator 2 and the first reaction zone of the electrochemical stack 1 in sequence before flowing out of the first reaction zone outlet. The first hydrogen generator 2 is filled with a first hydrogen generating material 3, which is made of a reducing metal or a reducing alloy and can react with water vapor.

[0025] When the electrochemical device fails and the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the water vapor is not stopped in time, resulting in a rapid increase in the water content of the fluid entering through the inlet of the first reaction zone of the electrochemical stack 1, which will cause certain damage to the electrochemical stack 1. The present invention sets the first hydrogen generating device 2 to be connected to the inlet of the first reaction zone of the electrochemical stack 1, and utilizes the first hydrogen generating material 3 filled in the first hydrogen generating device 2 to react with the water vapor, thereby consuming the water vapor. The general reaction formula is: xJ+yH2O(g)→J x O y +yH2(g), where J represents the first hydrogen generating material 3; the hydrogen generated by the reaction enters the electrochemical stack 1 as a protective gas to protect the catalyst in the electrochemical stack 1. When the electrochemical device resumes the supply of reducing fluid, J x O y The first hydrogen generating material 3 can be reduced by the reducing fluid, and can be recycled, has a long service life, and is low in cost.

[0026] In one embodiment, the first hydrogen generating material 3 has a porous structure, and the porosity of the first hydrogen generating material 3 is 10-300 ppi.

[0027] The inventors have discovered that the porous structure of the first hydrogen generating material 3 has a large specific surface area, which can accelerate the reaction rate between the first hydrogen generating material 3 and water vapor. If the porosity of the first hydrogen generating material 3 is less than 10 ppi, the specific surface area of ​​the first hydrogen generating material 3 is too small, the reaction rate between the first hydrogen generating material 3 and water vapor is too slow, and sufficient hydrogen cannot be generated, resulting in poor protection for the electrochemical stack 1. If the porosity of the first hydrogen generating material 3 is greater than 300 ppi, the pore path within the first hydrogen generating material 3 is tortuous and long, increasing the pressure drop at the entrance of the first reaction zone of the electrochemical stack 1, making the gas supply at the entrance of the first reaction zone of the electrochemical stack 1 more difficult and increasing the energy consumption of the gas supply device.

[0028] It should be understood that the reducing fluid described in the present invention can be hydrogen, or a mixture of hydrogen and methane; if the electrochemical stack is a solid oxide fuel cell, the first reaction zone is the anode reaction zone; if the electrochemical stack is a solid oxide electrolysis cell, the first reaction zone is the cathode reaction zone.

[0029] In one embodiment, the thermodynamic equilibrium hydrogen partial pressure during the oxidation reaction of the first hydrogen-generating material 3 within the first hydrogen-generating device 2 is P1, and the thermodynamic equilibrium hydrogen partial pressure during the oxidation reaction of the catalyst within the first reaction zone of the electrochemical stack 1 is P2. When the electrochemical device is operating normally, the hydrogen partial pressure within the first hydrogen-generating device 2 is P3, where P3>P1. When the inlet of the first hydrogen-generating device 2 does not receive a reducing fluid, the hydrogen partial pressure within the first reaction zone of the electrochemical stack 1 is P4, where P4>P2. The thermodynamic equilibrium hydrogen partial pressure is the partial pressure of hydrogen in the gas phase within the reaction device when the redox reaction of the hydrogen-generating material reaches equilibrium. When P3>P1, the redox reaction proceeds in the direction of reduction; when P3<P1, the redox reaction proceeds in the direction of oxidation.

[0030] Research has found that the present invention regulates the loading position and loading amount of the first hydrogen generating material 3 so that P3>P1 and P4>P2, thereby ensuring that the first hydrogen generating material 3 remains in a reduced state during normal operation of the device. When the inlet of the first hydrogen generating device 2 does not receive the reducing fluid due to an emergency stop or failure of the electrochemical device, the first hydrogen generating material 3 can continue to react with water vapor to generate a hydrogen shielding gas. If P3<P1 during normal operation of the electrochemical device, the first hydrogen generating material 3 in the first hydrogen generating device 2 has been oxidized. When the inlet of the first hydrogen generating device 2 does not receive the reducing fluid due to an emergency stop or failure of the electrochemical device, the first hydrogen generating material 3 no longer has the ability to react with water vapor to generate a hydrogen shielding gas. If P4<P2 when the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the catalyst in the first reaction zone of the electrochemical stack 1 will oxidize, causing irreversible damage.

[0031] In one embodiment, the electrochemical stack 1 is a solid oxide fuel cell, and the electrochemical device further includes a reformer 4 , wherein the outlet of the reformer 4 , the first hydrogen generating device 2 , and the inlet of the first reaction zone of the electrochemical stack 1 are connected in sequence.

[0032] If the electrochemical stack 1 is a solid oxide fuel cell, the inlet of the first reaction zone of the electrochemical stack 1 is the anode inlet, and the outlet of the first reaction zone of the electrochemical stack 1 is the anode outlet. The reaction gas in the reformer 4 usually includes water vapor and a reducing fluid. Once the electrochemical device stops suddenly or fails, the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, and the water vapor in the reformer 4 flows directly to the anode of the solid oxide fuel cell, causing certain damage to the anode structure of the fuel cell. The present invention sets a first hydrogen generating device 2 between the outlet of the reformer 4 and the inlet of the first reaction zone of the electrochemical stack 1. When the electrochemical device stops suddenly or fails, the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the first hydrogen generating material 3 can consume the water vapor and generate hydrogen at the same time. The generated hydrogen enters the anode of the fuel cell, which can play a good protective role.

[0033] In one embodiment, the electrochemical device is a solid oxide electrolysis cell, and the electrochemical device further comprises a mixer 5 , wherein an outlet of the mixer 5 , the first hydrogen generation device 2 , and an inlet of the first reaction zone of the electrochemical stack 1 are connected in sequence.

[0034] If the electrochemical stack 1 is a solid oxide electrolytic cell, the inlet of the first reaction zone of the electrochemical stack 1 is the cathode inlet of the solid oxide electrolytic cell, and the outlet of the first reaction zone of the electrochemical stack 1 is the cathode outlet of the solid oxide electrolytic cell. The reaction gas of the mixer 5 usually includes water vapor and a reducing fluid. Once the electrochemical device stops suddenly or stops due to a fault, the inlet of the first hydrogen generating device 2 does not receive the reducing fluid. The water vapor in the mixer 5 flows through the first hydrogen generating device 2 to the cathode of the solid oxide electrolytic cell, which will cause certain damage to the cathode structure of the electrolytic cell. The present invention provides a first hydrogen generating device 2 filled with a first hydrogen generating material 3 between the outlet of the mixer 5 and the inlet of the first reaction zone of the electrochemical stack 1. When the electrochemical device stops suddenly or stops due to a fault, the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the first hydrogen generating material 3 can consume water vapor and generate hydrogen at the same time. The generated hydrogen enters the cathode of the electrolytic cell, which can play a good protective role.

[0035] Specifically, the electrochemical device also includes a pressurized storage system 9. The outlet of the first reaction zone of the electrochemical stack 1, the second hydrogen generation device 6, and the inlet of the pressurized storage system 9 are connected in sequence. The pressurized storage system 9 is used to store the gas output by the second hydrogen generation device 6.

[0036] In one embodiment, the outlet of the first reaction zone of the electrochemical stack 1 is connected to a second hydrogen generating device 6. The second hydrogen generating device 6 is a structure that is hollow inside and open at both ends. A second hydrogen generating material 7 is arranged in the second hydrogen generating device 6. The material of the second hydrogen generating material 7 is a reducing metal or a reducing alloy. The second hydrogen generating material 7 can react with water vapor.

[0037] When a malfunction in the electrochemical device prevents the inlet of the first hydrogen generator 2 from receiving the reducing fluid, water vapor is susceptible to backflow at the outlet of the first reaction zone of the electrochemical stack 1, which can cause certain damage to the electrochemical stack 1. The present invention provides a second hydrogen generator 6 connected to the outlet of the first reaction zone of the electrochemical stack 1. The second hydrogen generating material 7 contained in the second hydrogen generator 6 reacts with the backflowing water vapor, consuming the water vapor and reacting with it to produce a hydrogen shielding gas, thereby preventing the water vapor from backflowing into the electrochemical stack 1 and preventing damage to the electrochemical stack 1.

[0038] Specifically, the second hydrogen generating material 7 has a porous structure, and the porosity of the second hydrogen generating material 7 is 10-300 ppi.

[0039] The inventors have discovered that the porous structure of the second hydrogen generating material 7 has a large specific surface area, which can accelerate the reaction rate of the second hydrogen generating material 7 with water vapor. If the porosity of the second hydrogen generating material 7 is less than 10 ppi, the specific surface area of ​​the second hydrogen generating material 7 is too small, and the reaction rate of the second hydrogen generating material 7 with water vapor is too slow to quickly consume the refluxed water vapor, unable to provide sufficient hydrogen, and the protection effect on the electrochemical stack 1 is poor. If the porosity of the second hydrogen generating material 7 is greater than 300 ppi, the path within the pores of the second hydrogen generating material 7 is tortuous and long, increasing the pressure drop at the outlet of the first reaction zone of the electrochemical stack 1. This not only increases the energy consumption of the gas supply device, but also increases the operating pressure of the electrochemical stack 1, which can easily lead to its sealing failure.

[0040] Specifically, the electrochemical stack is a solid oxide fuel cell, and the electrochemical device further includes a burner 8. The outlet of the first reaction zone of the electrochemical stack 1, the second hydrogen generation device 6, and the inlet of the burner 8 are connected in sequence.

[0041] Specifically, the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the second hydrogen generating material 7 in the second hydrogen generating device 6 is P5, and the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the catalyst in the first reaction zone of the electrochemical stack 1 is P2; when the electrochemical device operates normally, the hydrogen partial pressure in the second hydrogen generating device 6 is P6, and P6>P5; when the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack 1 is P4, and P4>P2.

[0042] Research has found that by regulating the loading position and loading amount of the second hydrogen generating material 7 so that P6>P5 and P4>P2, the present invention can ensure that the second hydrogen generating material 7 remains in a reduced state during normal operation of the device. When the inlet of the first hydrogen generating device 2 does not receive a reducing fluid, the second hydrogen generating material 7 can continue to react with water vapor to generate hydrogen protective gas. If P6<P5 during normal operation of the electrochemical device, the second hydrogen generating material 7 in the second hydrogen generating device 6 has already been oxidized. If the inlet of the first hydrogen generating device 2 does not receive a reducing fluid due to an emergency stop or failure of the electrochemical device, the second hydrogen generating material 7 cannot consume the refluxed water vapor and provide sufficient hydrogen, thus losing its protective effect on the electrochemical stack 1. If P4<P2 when the inlet of the first hydrogen generating device 2 does not receive a reducing fluid, the catalyst in the first reaction zone of the electrochemical stack 1 will oxidize, causing irreversible damage.

[0043] In the present invention, the reducing metal may be any one of iron, nickel, and cobalt, and the reducing alloy comprises at least two of the iron, nickel, and cobalt.

[0044] The present invention provides the following examples and comparative examples to facilitate understanding of the present invention. These examples are not intended to limit the scope of the claims. Unless otherwise specified, the experimental reagents and instruments involved in the practice of the present invention are commonly used reagents and instruments.

[0045] Example 1

[0046] This embodiment provides an electrochemical device, the structure of which is shown in FIG1 .

[0047] The electrochemical device includes an electrochemical stack 1, a first hydrogen generating device 2, a reformer 4, a second hydrogen generating device 6 and a burner 8. The electrochemical stack 1 has a first reaction zone inlet, a first reaction zone and a first reaction zone outlet. The first reaction zone inlet and the first reaction zone outlet are respectively connected to the first reaction zone. The electrochemical stack 1 is a solid oxide fuel cell, and the first reaction zone is an anode reaction zone; the first hydrogen generating device 2 is a structure with a hollow interior and open at both ends, and the second hydrogen generating device 6 is a structure with a hollow interior and open at both ends; the outlet of the reformer 4, the first hydrogen generating device 2 and the first reaction zone inlet of the electrochemical stack 1 are connected in sequence; the first reaction zone outlet of the electrochemical stack 1, the second hydrogen generating device 6 and the inlet of the burner 8 are connected in sequence; the first hydrogen generating device 2 is filled with a first hydrogen generating material 3, and the second hydrogen generating device 6 is filled with a second hydrogen generating material 7.

[0048] The thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the first hydrogen generating material 3 in the first hydrogen generating device 2 is P1, and the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the catalyst in the first reaction zone of the electrochemical stack 1 is P2; when the electrochemical device operates normally, the hydrogen partial pressure in the first hydrogen generating device 2 is P3, P3>P1; when the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack 1 is P4, P4>P2.

[0049] The thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the second hydrogen generating material 7 in the second hydrogen generating device 6 is P5; when the electrochemical device operates normally, the hydrogen partial pressure in the second hydrogen generating device 6 is P6, P6>P5; when the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack 1 is P4, P4>P2.

[0050] The first hydrogen generating material 3 is made of iron, and the porosity of the first hydrogen generating material 3 is 110 ppi; the second hydrogen generating material 7 is made of iron, and the porosity of the second hydrogen generating material 7 is 110 ppi.

[0051] Example 2

[0052] This embodiment provides an electrochemical device, the structure of which is shown in FIG2 .

[0053] The electrochemical device includes an electrochemical stack 1, a first hydrogen generating device 2, a mixer 5, a second hydrogen generating device 6 and a pressurized storage system 9. The electrochemical stack 1 has a first reaction zone inlet, a first reaction zone and a first reaction zone outlet. The first reaction zone inlet and the first reaction zone outlet are respectively connected to the first reaction zone. The electrochemical stack 1 is a solid oxide electrolysis cell, and the first reaction zone is a cathode reaction zone; the first hydrogen generating device 2 is a structure with a hollow interior and open at both ends, and the second hydrogen generating device 6 is a structure with a hollow interior and open at both ends; the outlet of the mixer 5, the first hydrogen generating device 2 and the first reaction zone inlet of the electrochemical stack 1 are connected in sequence; the first reaction zone outlet of the electrochemical stack 1, the second hydrogen generating device 6 and the inlet of the pressurized storage system 9 are connected in sequence; the first hydrogen generating device 2 is filled with a first hydrogen generating material 3, and the second hydrogen generating device 6 is filled with a second hydrogen generating material 7.

[0054] The thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the first hydrogen generating material 3 in the first hydrogen generating device 2 is P1, and the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the catalyst in the first reaction zone of the electrochemical stack 1 is P2; when the electrochemical device operates normally, the hydrogen partial pressure in the first hydrogen generating device 2 is P3, P3>P1; when the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack 1 is P4, P4>P2.

[0055] The thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the second hydrogen generating material 7 in the second hydrogen generating device 6 is P5; when the electrochemical device operates normally, the hydrogen partial pressure in the second hydrogen generating device 6 is P6, P6>P5; when the inlet of the first hydrogen generating device 2 does not receive the reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack 1 is P4, P4>P2.

[0056] The material of the first hydrogen generating material 3 is iron-nickel alloy (the mass ratio of iron and nickel is 1:1), and the porosity of the first hydrogen generating material 3 is 60ppi; the material of the second hydrogen generating material 7 is iron-nickel alloy (the mass ratio of iron and nickel is 1:1), and the porosity of the second hydrogen generating material 7 is 60ppi.

[0057] Comparative Example 1

[0058] The difference between this comparative example and Example 1 is that the first hydrogen generating material is not loaded into the first hydrogen generating device 2 and the second hydrogen generating material is not loaded into the second hydrogen generating device 6.

[0059] The functions of the first hydrogen generating device 2 and the second hydrogen generating device 6 in the electrochemical devices of Example 1 and Comparative Example 1 were verified. Before the verification, the electrochemical devices were applied to a solid oxide fuel cell (SOFC) system. The verification steps were as follows:

[0060] The SOFC system was in its normal operating, heat-insulating state (660°C). The reducing fluids supplied were natural gas and water vapor, corresponding to a molar flow ratio of 1:3. The reformer outlet temperature was 440°C. The internal temperature of the first hydrogen generator 2 was 790°C, and the corresponding internal fluid composition was H2O (54.24%), CH4 (15.55%), H2 (23.94%), CO2 (5.95%), and CO (0.31%). This resulted in a hydrogen partial pressure P3 within the first hydrogen generator 2 of 0.24 bar, while the thermodynamic equilibrium hydrogen partial pressure P1 for the oxidation reaction of the first hydrogen generating material 3 was 0.03 bar. P3 > P1, indicating that the first hydrogen generating material 3 was in a reduced state.

[0061] An emergency stop command was issued to the SOFC system, automatically cutting off the reducing fluid supply and allowing the system to cool naturally. A DC-DC converter was used to detect the open-circuit voltage of electrochemical stack 1. The test results are shown in Figure 3.

[0062] As can be seen from Figure 3, after the supply of the reducing fluid is stopped, the open circuit voltage value of Example 1 is significantly greater than that of Comparative Example 1. Since the open circuit voltage is directly related to the hydrogen partial pressure in the first reaction zone, at the same temperature, a higher open circuit voltage indicates a higher hydrogen partial pressure in the first reaction zone. This shows that in Example 1, the hydrogen generated by the reaction between the first hydrogen generating material 3 and water vapor enters the anode of the fuel cell, thereby increasing the hydrogen partial pressure at the anode and protecting the anode structure of the electrochemical stack 1.

[0063] The following tests were performed on the devices of Examples 1-2 above:

[0064] 1. Install a first hydrogen generating device filled with a first hydrogen generating material or a second hydrogen generating device filled with a second hydrogen generating material in a furnace and connect it to a gas supply line with a humidification function. Set the furnace temperature to 800°C and introduce 2 L / min of dry H2 for 2 hours. Then, switch the gas flow to 2 L / min of a dry hydrogen-nitrogen mixture (4 vol% H2) and cool the furnace to room temperature. Remove the first hydrogen generating material or the second hydrogen generating material and weigh it to obtain its initial mass.

[0065] 2. Reinstall the removed first hydrogen generating material or the second hydrogen generating material into the furnace, and raise the furnace temperature to 800°C in an atmosphere of 2 L / min dry hydrogen and nitrogen mixed gas (4 vol% H2);

[0066] 3. Switch the gas to 2 L / min N2 (water content 20 vol%) for 2 hours to force oxidation of the first hydrogen generating material or the second hydrogen generating material;

[0067] 4. Switch the gas to 2 L / min dry H2 for 2 hours to reduce the first hydrogen generating material or the second hydrogen generating material;

[0068] 5. Repeat steps 3 and 4 20 times, then switch the gas to 2 L / min dry hydrogen-ammonia mixture (4 vol% H2), cool the furnace to room temperature, take out the first hydrogen generating material or the second hydrogen generating material and weigh it to obtain its final mass.

[0069] The test results show that after the device of Example 1-2 repeated steps 3 and 4 20 times (ie, after cutting off and restoring the reducing fluid supply 20 times), the mass loss of the first hydrogen generating material and the second hydrogen generating material were both ≤1%.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An electrochemical device, characterized in that It includes an electrochemical stack and a first hydrogen generating device, the electrochemical stack has a first reaction zone inlet, a first reaction zone and a first reaction zone outlet, the first reaction zone inlet and the first reaction zone outlet are respectively connected to the first reaction zone, the first reaction zone inlet of the electrochemical stack is connected to the outlet of the first hydrogen generating device, the inlet of the first hydrogen generating device is used to receive a reducing fluid and / or water vapor, the first hydrogen generating device is filled with a first hydrogen generating material, and the material of the first hydrogen generating material is a reducing metal or a reducing alloy.

2. The electrochemical device according to claim 1, wherein The first hydrogen generating material has a porous structure, and the porosity of the first hydrogen generating material is 10-300 ppi.

3. The electrochemical device according to claim 1, wherein The thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the first hydrogen generating material in the first hydrogen generating device is P1, and the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the catalyst in the first reaction zone is P2; when the electrochemical device operates normally, the hydrogen partial pressure in the first hydrogen generating device is P3, and P3>P1.

4. The electrochemical device according to claim 3, wherein: When the inlet of the first hydrogen generating device does not receive the reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack is P4, and P4>P2.

5. The electrochemical device according to claim 1, wherein The electrochemical stack is a solid oxide fuel cell. The electrochemical device further includes a reformer. The outlet of the reformer, the first hydrogen generating device and the inlet of the first reaction zone of the electrochemical stack are connected in sequence.

6. The electrochemical device according to claim 1, wherein: The electrochemical device is a solid oxide electrolysis cell, and further comprises a mixer, wherein an outlet of the mixer, a first hydrogen generating device and an inlet of a first reaction zone of the electrochemical stack are connected in sequence.

7. The electrochemical device according to claim 1, wherein: The outlet of the first reaction zone of the electrochemical stack is connected to a second hydrogen generating device. A second hydrogen generating material is provided in the second hydrogen generating device. The material of the second hydrogen generating material is a reducing metal or a reducing alloy.

8. The electrochemical device according to claim 7, wherein: The second hydrogen generating material has a porous structure, and the porosity of the second hydrogen generating material is 10-300 ppi.

9. The electrochemical device according to claim 7, wherein: The electrochemical stack is a solid oxide fuel cell. The electrochemical device further includes a burner. The outlet of the first reaction zone of the electrochemical stack, the second hydrogen generation device, and the inlet of the burner are connected in sequence.

10. The electrochemical device according to claim 7, wherein: The thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the second hydrogen generating material in the second hydrogen generating device is P5, and the thermodynamic equilibrium hydrogen partial pressure of the oxidation reaction of the catalyst in the first reaction zone is P2; when the electrochemical device operates normally, the hydrogen partial pressure in the second hydrogen generating device is P6, P6>P5; when the inlet of the first hydrogen generating device does not receive the reducing fluid, the hydrogen partial pressure in the first reaction zone of the electrochemical stack is P4, P4>P2.

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