Electrochemical device, method for deoxidizing and humidifying gas and application of electrochemical device

Abstract

The invention provides an electrochemical device, a method for deoxidizing and humidifying gas and application thereof, and the method for deoxidizing and humidifying gas comprises the following steps: introducing water into the anode side of the electrochemical device containing a proton exchange membrane, and introducing oxygen-containing gas into the cathode side; under the driving of external voltage, oxygen evolution reaction is carried out on the anode side to generate protons; and the protons migrate to the cathode side through the proton exchange membrane and are subjected to an oxygen reduction reaction with oxygen in the oxygen-containing gas, water is generated and discharged along with unreacted gas, and deoxygenization and humidification of the gas on the cathode side are synchronously achieved.

Description

Technical Field

[0001] The present disclosure relates to the technical field of food preservation and controlled atmosphere storage, and in particular to an electrochemical device, a method for gas deoxygenation and humidification, and applications thereof, and more specifically to an electrochemical device, a method for gas deoxygenation and humidification, and applications thereof in extending the shelf life of food. Background Art

[0002] Modified Atmosphere Packaging (MAP) is a packaging technology that extends the shelf life of food by adjusting the gas composition in the package. Its core principle is to use a specific gas environment to inhibit the natural aging process of food, reduce the oxygen content in the package, reduce oxidation reactions, and slow down the growth of microorganisms, thereby maintaining the freshness and nutritional value of food.

[0003] Traditional deoxygenation methods include nitrogen replacement and commercial oxygen absorbers. Nitrogen replacement uses nitrogen cylinders to transport high-concentration nitrogen to expel oxygen, but its equipment is large, heavy, and has high pressure, which poses risks in transportation, storage, and use, limiting its scope of application. Commercial oxygen absorbers such as reduced iron powder, sulfite, and ascorbic acid are suitable for small-scale deoxygenation, but they have slow reaction rates and high costs, making them difficult to apply on a large scale and unable to accurately control the deoxygenation concentration.

[0004] The deoxygenation technology widely used in the current industry is pressure swing adsorption (PSA). The PSA device contains two adsorption tanks filled with molecular sieve adsorbents. It utilizes the difference in the adsorption capacity of molecular sieves for different gases, and alternately adsorbs and desorbs through multiple adsorption-desorption cycles to remove oxygen molecules and achieve efficient deoxygenation. However, the startup time of PSA equipment is long, and the purity of the separated nitrogen can only reach about 97%, which cannot meet the lower oxygen concentration requirements. In addition, the water vapor generated in the environment will reduce the performance of the adsorbent, making PSA only suitable for low-humidity gas deoxygenation. The dry, low-oxygen gas generated may cause serious dehydration of vegetables, which is not conducive to freshness preservation. Summary of the invention

[0005] In view of this, it is urgent to develop a gas deoxygenation and humidification method and device with simple device and integrated deoxygenation and humidification functions, so as to achieve efficient regulation of food storage environment and extend food shelf life, while avoiding the problems of complex equipment, high energy consumption, insufficient humidity control, etc. in traditional methods. The present disclosure provides an electrochemical device, a method for gas deoxygenation and humidification, and its application, in order to at least partially solve at least one of the above-mentioned technical problems.

[0006] To achieve the above purpose, the technical solution of the present invention is as follows:

[0007] In one aspect of the present disclosure, there is provided a method for deoxygenating and humidifying gas, comprising:

[0008] Water is introduced into the anode side of an electrochemical device including a proton exchange membrane, and oxygen-containing gas is introduced into the cathode side;

[0009] Driven by an applied voltage, an oxygen evolution reaction occurs on the anode side to generate protons;

[0010] Protons migrate to the cathode side through the proton exchange membrane, undergo an oxygen reduction reaction with the oxygen in the oxygen-containing gas, generate water and discharge it with the unreacted gas, thereby simultaneously achieving deoxygenation and humidification of the cathode side gas.

[0011] In another aspect of the present disclosure, an electrochemical device is provided for implementing the above method, wherein the electrochemical device comprises a reaction chamber and a power supply module for providing voltage to the reaction chamber.

[0012] The reaction chamber includes: a membrane electrode assembly, an anode side assembly, a cathode side assembly and an end plate. The anode side assembly and the cathode side assembly are located on opposite sides of the membrane electrode assembly. The end plates are respectively located at one end of the anode side assembly and the cathode side assembly away from the membrane electrode assembly. The end plates, the anode side assembly and the cathode side assembly are all provided with channels for gas and liquid to flow.

[0013] The membrane electrode assembly is used to conduct protons and catalyze reactions. The membrane electrode assembly includes a proton exchange membrane, and an anode catalyst layer and a cathode catalyst layer coated on both sides of the proton exchange membrane respectively.

[0014] The anode side assembly is used to pass pure water and generate oxygen evolution reaction, and the anode side assembly includes an anode diffusion layer and an anode flow channel plate in sequence along the membrane electrode assembly outward;

[0015] The cathode side assembly is used to introduce air and generate oxygen reduction reaction, and the cathode side assembly includes a cathode diffusion layer and a cathode flow channel plate in sequence along the membrane electrode assembly outward;

[0016] The power supply module is electrically connected to the anode flow channel plate and the cathode flow channel plate through wires.

[0017] In another aspect of the present disclosure, there is provided an application of the above-mentioned method or the above-mentioned electrochemical device in extending the shelf life of food, comprising: placing the food to be preserved in a closed environment on the cathode side of the electrochemical device, passing the gas in the closed environment into the cathode side of the electrochemical device, passing water into the anode side of the electrochemical device, and using a method for gas deoxygenation and humidification to deoxygenate and humidify the closed environment, thereby extending the shelf life of the food.

[0018] According to an embodiment of the present disclosure, a method for gas deoxygenation and humidification is provided. An electrochemical device based on a proton exchange membrane is provided by introducing water into the anode side of the device and introducing an oxygen-containing gas into the cathode side. Under the action of an applied voltage, an oxygen evolution reaction occurs on the anode side to generate protons. The protons are conducted to the cathode side through the proton exchange membrane, and an oxygen reduction reaction occurs with the oxygen on the cathode side to generate water, which is discharged from the device along with the remaining gas. The present disclosure achieves the in-situ generation of water vapor on the cathode side by coupling the oxygen evolution reaction and the oxygen reduction reaction, thereby effectively reducing the oxygen concentration in the gas and increasing the ambient humidity, thereby simultaneously achieving gas deoxygenation and humidification. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 is a structural diagram of the electrochemical device disclosed in the present invention;

[0020] Figure 2 This is a schematic diagram of the operating principle of the device disclosed in the present invention;

[0021] Figure 3 This is a diagram of the optional structures of the anode flow channel plate and the cathode flow channel plate disclosed in the present invention;

[0022] Figure 4a This is a graph showing the deoxygenation and humidification performance of the electrochemical device in Example 1;

[0023] Figure 4b This is a graph showing the deoxygenation and humidification performance of the electrochemical device in Example 2;

[0024] Figure 4c This is a graph showing the deoxygenation and humidification performance of the electrochemical device in Example 3;

[0025] Figure 5 This is a comparison chart of the deoxygenation and humidification performance of the electrochemical devices in Examples 1 to 3 of the present disclosure;

[0026] Figure 6 Schematic diagram of three flow channel mass transfer modes in the electrochemical device in Examples 1 to 3;

[0027] Figure 7 The inlet and outlet pressure drop test diagrams of three cathode flow channel plates in the electrochemical devices of Examples 1 to 3 of the present disclosure;

[0028] Figure 8a This is a test diagram of deoxygenation performance of the electrochemical devices of Examples 1 to 3 of the present disclosure under different voltages and gas flow rates in an air environment;

[0029] Figure 8b This is a test diagram of the deoxygenation performance of the electrochemical devices of Examples 1 to 3 of the present disclosure at different voltages and gas flow rates under an 8% oxygen concentration environment;

[0030] Figure 8cThis is a test diagram of the deoxygenation performance of the electrochemical devices of Examples 1 to 3 of the present disclosure at different voltages and gas flow rates under an oxygen concentration of 3%;

[0031] Figure 9a This is an electrochemical impedance spectrum test diagram of the electrochemical device of Examples 1 to 3 of the present disclosure;

[0032] Figure 9b This is a diagram of the impedance fitting results of the electrochemical devices of Examples 1 to 3 of the present disclosure;

[0033] Fig.10 Stability test diagram of the electrochemical device of Examples 1 to 3 of the present disclosure;

[0034] Fig.11 This is a stability test diagram of the electrochemical device in Example 4 of the present disclosure;

[0035] Fig.12a This is a diagram showing the deoxygenation effect of Comparative Example 1 of the present disclosure. Figure 12b This is a diagram showing the deoxygenation effect of Example 5 of the present disclosure;

[0036] Fig.13 This is a diagram showing the preservation effect of spinach in Example 5 and Comparative Example 1 of the present disclosure;

[0037] Fig.14 It is a graph of the water loss rate of spinach in Example 5 and Comparative Example 1 of the present disclosure. DETAILED DESCRIPTION

[0038] In order to make the objectives, technical solutions and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in conjunction with specific embodiments.

[0039] The endpoints and any values ​​of the ranges disclosed in this disclosure are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, and these numerical ranges should be regarded as specifically disclosed in this disclosure.

[0040] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0041] At present, the spoilage and waste of foods that are difficult to store for a long time, such as vegetables, due to improper storage is very serious. Every year, a large amount of food is lost during storage and transportation. At present, the industry mainly delays spoilage by reducing the oxygen content in the food storage environment. The main deoxygenation technology used is pressure swing adsorption (PSA) technology. However, the effect of PSA technology in reducing oxygen concentration is limited. The water vapor generated in food will seriously reduce the absorption capacity and long-term stability of the adsorbent in PSA technology, resulting in PSA technology can only be used for deoxygenation of low-humidity gases. In addition, the adsorbent may also absorb water vapor in the air, causing serious dehydration of stored food, which is not conducive to freshness preservation. These limitations restrict the development of food preservation technology.

[0042] The present disclosure proposes a method for gas deoxygenation and humidification, which can simultaneously achieve the removal of oxygen in the gas and the increase of environmental humidity through a single electrochemical device, and can break through the limitations of traditional step-by-step treatment of deoxygenation and humidification. By introducing water into the anode side of the electrochemical device, water molecules undergo oxygen precipitation reaction at the anode under the drive of an applied voltage to generate oxygen and protons. Since the proton exchange membrane has good proton conductivity and gas barrier properties, the generated protons can be directed to migrate to the cathode side through the proton exchange membrane, while blocking the generated oxygen. An oxygen-containing gas (such as air) is introduced into the cathode side, and the protons migrated to the cathode undergo an oxygen reduction reaction with oxygen to generate water, which is discharged through the gas outlet with the unreacted inert gas. The reaction uses water as the electrolyte raw material, has no chemical additives or by-products, and is environmentally friendly. By adjusting the applied voltage or current density, the deoxygenation rate and humidification amount can be controlled to meet the needs of different application scenarios. Compared with the traditional deoxygenation and humidification method, the method disclosed in the present disclosure is simple and easy to implement, and shows significant advantages in energy consumption and noise, providing a new solution for the fields of food preservation and storage that is efficient, environmentally friendly and economical.

[0043] According to an embodiment of one aspect of the present disclosure, a method for gas deoxygenation and humidification is proposed, comprising:

[0044] Water is introduced into the anode side of an electrochemical device including a proton exchange membrane, and an oxygen-containing gas is introduced into the cathode side; driven by an external voltage, an oxygen evolution reaction occurs on the anode side to generate protons; the protons migrate to the cathode side through the proton exchange membrane, undergo an oxygen reduction reaction with oxygen in the oxygen-containing gas, generate water and discharge it with the unreacted gas, thereby simultaneously achieving deoxygenation and humidification of the cathode side gas.

[0045] According to an embodiment of the present disclosure, a method for gas deoxygenation and humidification is provided. Water is introduced into the anode side as an electrolyte, and under the action of an applied voltage, water molecules undergo an oxygen evolution reaction (OER) to generate oxygen and protons. The specific reaction is as follows:

[0046] Anode OER reaction:

[0047] The generated protons (H + ) migrates to the cathode side through the proton exchange membrane, while blocking the reverse diffusion of oxygen. On the cathode side, oxygen-containing gas is introduced, and the protons that migrate to the cathode react with the oxygen in the oxygen-containing gas to produce water. The reaction equation is as follows:

[0048] Cathode ORR reaction:

[0049] The generated water is then mixed with the unreacted gas and discharged together. Since oxygen is reduced to water at the cathode, the oxygen content in the gas on the cathode side is significantly reduced, thereby achieving a deoxygenation effect. At the same time, the generated water increases the humidity of the gas, achieving a humidification function.

[0050] According to an embodiment of the present disclosure, the applied voltage is a DC voltage of 0.8~2.8V, for example, it can be 0.8V, 1V, 1.6V, 2V, 2.8V, etc. The higher the applied voltage, the faster the reaction rate and the higher the deoxygenation efficiency. By adjusting the applied voltage, it is possible to adapt to environments with different oxygen concentrations, thereby optimizing the deoxygenation effect. The concentration of oxygen in the oxygen-containing gas is greater than or equal to 3%, and the concentration of oxygen can be, for example, 3%, 5%, 8%, 15%, 20%, 25%, etc. The deoxygenation and humidification method disclosed in the present disclosure can perform efficient deoxygenation and humidification in environments with different oxygen contents. The flow rate of the oxygen-containing gas is 30 ml·min -1 ~3 L min -1 , for example, 30 ml·min -1 、50 ml·min -1 、100 ml·min -1 , 1 L min -1 , 2 L min -1 、3 L·min -1 The higher the gas flow rate, the faster the reaction rate, which is suitable for large-scale applications; the lower the flow rate, the more suitable for small-scale or low-flow scenarios. By controlling the gas flow rate, the reaction rate can be adjusted to suit different application scenarios.

[0051] According to another aspect of the present disclosure, an electrochemical device is provided for implementing the above method. Figure 1 FIG. 4 is a structural diagram of the electrochemical device disclosed in the present invention.

[0052] like Figure 1 As shown, the electrochemical device includes: a reaction chamber 201 and a power supply module 101 for providing voltage to the reaction chamber.

[0053] The reaction chamber 201 includes: a membrane electrode assembly 202, an anode side assembly 203, a cathode side assembly 204 and an end plate 205. The anode side assembly 203 and the cathode side assembly 204 are located on opposite sides of the membrane electrode assembly 202, and the end plate 205 is respectively located at one end of the anode side assembly 203 and the cathode side assembly 204 away from the membrane electrode assembly 202. The end plate 205, the anode side assembly 203 and the cathode side assembly 204 are all provided with channels for gas and liquid circulation.

[0054] Specifically, the membrane electrode assembly 202 is used to conduct protons and catalyze reactions. The membrane electrode assembly 202 includes a proton exchange membrane, and an anode catalyst layer and a cathode catalyst layer respectively coated on both sides of the proton exchange membrane; the anode side assembly 203 is used to pass pure water and cause oxygen evolution reaction. The anode side assembly 203 includes an anode diffusion layer 206 and an anode flow channel plate 207 in sequence along the membrane electrode assembly outward; the cathode side assembly 204 is used to pass air and cause oxygen reduction reaction. The cathode side assembly 204 includes a cathode diffusion layer 208 and a cathode flow channel plate 209 in sequence along the membrane electrode assembly outward; the power supply module 101 is electrically connected to the anode flow channel plate 207 and the cathode flow channel plate 209 through wires.

[0055] According to the embodiment of the present disclosure, the end plate 205 is installed at the outermost side of the reaction chamber and is fixed by bolts. The end plate material can be epoxy resin, and the end plate 205 is reserved with air inlet, air outlet, liquid inlet, liquid outlet and bolt holes, respectively installed with matching interfaces and bolts. In addition, the inner side of the end plate is provided with a groove, in which a sealing ring is installed to prevent liquid leakage.

[0056] According to an embodiment of the present disclosure, the electrochemical device further includes a gasket 210, and the gasket material can be, for example, polytetrafluoroethylene propylene. The gasket 210 is located between the end plate 205 and the flow channel plate and / or between the diffusion layer and the flow channel plate, and is used to increase the pressure between the end plate 205 and the flow channel plate and / or between the diffusion layer and the flow channel plate, so that the various parts of the device fit more closely. Among them, the flow channel plate includes an anode flow channel plate 207 and a cathode flow channel plate 209, and the diffusion layer includes an anode diffusion layer 206 and a cathode diffusion layer 208.

[0057] According to an embodiment of the present disclosure, the entire electrochemical device is fixed and tightened with bolts covered with heat shrink tubing, and each bolt is applied with the same torque with a torque wrench. It is able to ensure the structural stability of the device, so that each component fits tightly, and avoids poor contact or damage caused by looseness or uneven force. At the same time, the uniform torque distribution can ensure that the anode and cathode maintain a consistent contact pressure during operation, thereby ensuring uniform current distribution and improving the overall performance and efficiency of the device. In addition, the use of heat shrink tubing can effectively prevent liquid leakage, protect bolts from corrosion, and enhance the sealing and service life of the device. Through standardized torque control, installation errors caused by human factors can also be reduced, significantly improving the safety and reliability of the device in long-term operation.

[0058] According to the embodiments of the present disclosure, the membrane electrode assembly in the electrochemical device can efficiently conduct protons and catalyze reactions through the synergistic effect of the proton exchange membrane, the anode catalyst layer and the cathode catalyst layer. Among them, the proton exchange membrane provides an efficient ion transmission channel as an electrochemical reaction, while the anode and cathode catalyst layers catalyze the oxygen evolution reaction and the oxygen reduction reaction, respectively, significantly reducing the activation energy of the reaction, thereby increasing the reaction rate. At the same time, the anode flow channel plate and the cathode flow channel plate cooperate with the anode diffusion layer and the cathode diffusion layer, respectively, to evenly distribute the reaction gas and liquid, ensuring that the reactants fully contact the catalyst layer. Under the action of the external voltage of the power supply module, the device can achieve the coupling of the oxygen evolution reaction and the oxygen reduction reaction, and simultaneously achieve deoxygenation and humidification of the gas.

[0059] Figure 2 The figure is a schematic diagram of the operating principle of the device disclosed in the present invention.

[0060] like Figure 2 As shown, water is introduced into the anode side of the electrochemical device, and oxygen evolution reaction occurs under the action of electrochemical reaction. In this process, water molecules are decomposed into oxygen and protons. The generated oxygen is discharged out of the device through the gas outlet, while the protons migrate to the cathode side through the proton exchange membrane. Oxygen-containing gas is introduced into the cathode side. When the protons migrate from the anode side to the cathode side, they react with the oxygen on the cathode side to generate water. The generated water is then mixed with the unreacted gas and discharged through the gas outlet. Thus, deoxygenation and humidification of the cathode side gas are achieved.

[0061] According to an embodiment of the present disclosure, the proton exchange membrane can conduct protons at a relatively fast speed while isolating gas and other ion penetration, so that the protons generated by the anode oxygen precipitation reaction are transferred to the cathode in time to combine with oxygen, and the service life is relatively long. For example, the cation exchange membrane can be selected from Fumasep FS-990-PK membrane, Nafion N115 membrane, Nafion N117 and Nafion N212 membrane, etc., preferably Fumasep FS-990-PK membrane, Fumasep FS-990-PK membrane has a thinner thickness, lower resistance, and excellent tensile and anti-swelling properties relative to other cation exchange membranes, which can significantly improve the stability of the electrochemical device. The thickness of the proton exchange membrane is 85~150μm, for example, it can be 85μm, 90μm, 100μm, 120μm, 150μm, etc. The thickness of the membrane directly affects its resistance and proton transfer efficiency. Thinner proton exchange membranes usually have lower resistance and higher proton transfer rate.

[0062] According to an embodiment of the present disclosure, the catalyst of the anode catalyst layer includes any one of a platinum carbon catalyst (Pt / C), a platinum single atom catalyst, and a platinum alloy catalyst, and the loading amount of platinum metal in the catalyst is 0.2-1 mg·cm -2 , for example, 0.2 mg·cm -2 , 0.5mg·cm -2 , 0.7mg·cm -2 , 0.9mg·cm -2 , 1mg·cm -2 etc.; the catalyst of the cathode catalyst layer comprises a metal oxide, the metal oxide is selected from iridium dioxide (IrO 2 ), ruthenium dioxide (RuO 2 ) in any one of the above. In practical applications, multi-element oxides can also be selected as cathode catalysts. The loading amount of metal elements in metal oxides is 0.2~1 mg·cm -2 , for example, 0.2 mg·cm -2 , 0.5mg·cm -2 , 0.7mg·cm -2 , 0.9mg·cm -2 , 1mg·cm -2 The catalysts at the cathode and anode have high catalytic activity for oxygen reduction reaction and oxygen evolution reaction, and good stability, ensuring that the electrochemical device can maintain high efficiency and stable performance during long-term operation, and are suitable for various gas deoxygenation and humidification application scenarios.

[0063] According to the embodiments of the present disclosure, the catalysts of the anode catalyst layer and the cathode catalyst layer are preferably coated on both sides of the proton exchange membrane using a coating membrane method (CCM) to prepare a membrane electrode assembly (MEA). The CCM method makes the contact between the catalyst layer and the proton exchange membrane closer. Compared with the method of spraying the catalyst on the membrane, the mass transfer resistance between the catalyst layer and the proton exchange membrane is significantly reduced, and the utilization rate of the catalyst is effectively improved. In addition, the present disclosure also performs edge sealing around the MEA to provide better structural support and sealing for the MEA, so as to facilitate the subsequent assembly between the various components.

[0064] According to an embodiment of the present disclosure, the anode diffusion layer is a first porous material including a corrosion-resistant metal coating, and the first porous material includes titanium felt; the hydrophobic porous material includes any one of hydrophobic carbon paper and hydrophobic carbon cloth. The material of the corrosion-resistant metal coating includes any one of platinum, gold, ruthenium, and iridium. In actual application, the anode diffusion layer material can be selected as 0.25 mm thick titanium felt with a 0.5 μm platinum coating. The corrosion-resistant metal coating enhances the corrosion resistance of the anode diffusion layer, and also improves its conductivity and stability, ensuring that the gas and liquid on the anode side can be evenly diffused to the anode catalyst layer, effectively promoting the mass transfer process between the flow channel and the catalyst layer.

[0065] According to the embodiments of the present disclosure, the cathode diffusion layer is a hydrophobic porous material. In practical applications, for example, a hydrophobic carbon paper with a microporous layer, such as SGL Carbon Sigracet 28BC, can be selected. The use of a hydrophobic porous material can effectively prevent water flooding on the cathode side and blockage of gas transmission channels, thereby ensuring that the device can continue to operate stably at a high reaction rate.

[0066] According to the embodiments of the present disclosure, the anode diffusion layer and the cathode diffusion layer can make the fluid in the flow channel plate diffuse evenly to the catalyst layer, effectively promoting the mass transfer of gas and liquid between the flow channel and the catalyst layer.

[0067] According to an embodiment of the present disclosure, the number of anode flow plates and cathode flow plates is one or more. When the number of flow plates is multiple, the multiple flow plates are connected in series. The materials of the anode flow plate and the cathode flow plate are both metal materials, wherein the surface of the anode flow plate comprises a corrosion-resistant metal coating. Due to the external reduction potential and the oxygen reduction reaction, the cathode flow plate has less corrosion to the flow plate. In actual use, for example, a polished titanium plate can be used. The positive flow plate is extremely affected by the local acidity generated by the external oxidation potential and the oxygen precipitation reaction, and requires external metal material for coating protection to prevent it from being oxidized and corroded. In actual application, for example, a platinum-plated titanium plate can be used, and the thickness of the platinum coating can be 0.5 μm.

[0068] According to the embodiments of the present disclosure, both the anode flow channel plate and the cathode flow channel plate include specially designed flow channels for gas and liquid circulation, and pole ears for connecting to an external power source are left on the side, which can be electrically connected to the power supply module of the electrochemical device through wires.

[0069] According to an embodiment of the present disclosure, the anode flow channel plate and the cathode flow channel plate include one or more of a straight flow channel structure, a serpentine flow channel structure, and a finger-shaped flow channel structure. Figure 3 1 is a diagram of the structure of the anode flow channel plate and the cathode flow channel plate that can be selected in the present invention. Figure 3 As shown, the straight flow channel is where the fluid flows from the inlet to the outlet in a straight line; the serpentine flow channel is where the fluid flows back to the outlet to obtain a longer flow; the finger-shaped flow channel is where the inlet and outlet are not connected and are staggered with each other.

[0070] According to an embodiment of another aspect of the present disclosure, there is provided an application of the above-mentioned method or the above-mentioned electrochemical device in extending the shelf life of food, comprising: placing the food to be preserved in a closed environment on the cathode side of the electrochemical device, passing the gas in the closed environment into the cathode side of the electrochemical device, passing water into the anode side of the electrochemical device, and using a method for gas deoxygenation and humidification to deoxygenate and humidify the closed environment, thereby extending the shelf life of the food.

[0071] According to an embodiment of the present disclosure, based on an electrochemical reaction device that couples oxygen reduction reaction and oxygen evolution reaction, the gas of a closed environment for storing food is directly introduced into the cathode side of the electrochemical device, and the method for gas deoxygenation and humidification disclosed in the present disclosure is used to achieve deoxygenation and humidification of the closed environment through electrochemical reaction. The contact surface between the electrochemical device and the closed environment is relatively closed and controllable, which effectively prevents contamination by external dust and microorganisms, and provides a high degree of purity and stability for the preservation environment. A low-oxygen environment can inhibit the respiration of food and the growth of microorganisms, while a high-humidity environment helps maintain the moisture balance of food, thereby significantly extending the shelf life of food.

[0072] In order to make the purpose, technical scheme and advantages of the present disclosure clearer, the present disclosure is further described in detail below in conjunction with specific examples and drawings. Specific techniques or conditions not specified in the examples are all conventional methods, which can be carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. It should be noted that the methods provided in the present disclosure are all conventional methods unless otherwise specified, and the reactants and reagents can be obtained from public commercial channels unless otherwise specified.

[0073] Embodiment 1:

[0074] This embodiment 1 provides an electrochemical device for achieving gas deoxygenation and humidification, including a reaction chamber and a power supply module for providing voltage to the reaction chamber.

[0075] The reaction chamber includes: a membrane electrode assembly, an anode side assembly, a cathode side assembly and an epoxy resin end plate. The anode side assembly and the cathode side assembly are located on opposite sides of the membrane electrode assembly. The end plates are respectively located at one end of the anode side assembly and the cathode side assembly away from the membrane electrode assembly. Channels for gas and liquid circulation are provided on the end plates, the anode side assembly and the cathode side assembly. The power supply module is electrically connected to the anode flow channel plate and the cathode flow channel plate through wires.

[0076] The membrane electrode assembly includes a Fumasep FS-990-PK proton exchange membrane and catalyst layers coated on both sides: the anode is an iridium dioxide catalyst layer with a metal iridium loading of 1.0 mg cm -2 ; The cathode is a platinum-carbon catalyst layer with a platinum loading of 0.4 mg cm -2 .

[0077] The anode side components include the anode diffusion layer and the anode flow plate from the membrane electrode assembly outward. The anode diffusion layer is composed of 0.25 mm thick titanium felt with 0.5 μm platinum coating. The anode flow plate is made of titanium plate that has been processed, ground and polished, and a serpentine flow plate is selected for the flow of pure water. The pure water flow rate is set to 30 ml min -1 .

[0078] The cathode side components include cathode diffusion layer and cathode flow channel plate from the membrane electrode assembly outward. The cathode diffusion layer uses hydrophobic carbon paper with a microporous layer (SGL Carbon Sigracet 28BC, area 7×7 cm²). The cathode flow channel plate uses a titanium plate with a 0.5 μm platinum coating, and selects a finger-type flow channel plate.

[0079] Example 2

[0080] Comparative Example 2 provides an electrochemical device for achieving gas deoxygenation and humidification, which differs from Example 1 in that the cathode flow channel plate is a straight flow channel plate.

[0081] Example 3

[0082] Comparative Example 2 provides an electrochemical device for achieving gas deoxygenation and humidification, which differs from Example 1 in that the cathode flow channel plate is a serpentine flow channel plate.

[0083] The electrochemical devices in Examples 1 to 3 were connected to a 15 L sealed empty box to test their deoxygenation and humidification performance. During the experiment, the power supply module applied a constant voltage of 1.23 V to the device, and the pure water flow rate on the anode side was set to 30 ml min -1 , driving the oxygen evolution reaction on the anode side. -1The gas in the sealed box is circulated and pumped into the cathode side of the device at a flow rate for oxygen reduction reaction, and the gas after the reaction flows back to the sealed box. In addition, an atomization device is installed at the air inlet of the sealed box to quickly convert the water blown out of the cathode into water mist and blow it into the sealed box, thereby quickly increasing the humidity in the box. Oxygen sensors and humidity sensors are also installed in the box to monitor the changes in oxygen concentration and humidity in real time, ensuring accurate evaluation of the deoxygenation and humidification effects during the experiment.

[0084] Figure 4a This is a graph showing the deoxygenation and humidification performance of the electrochemical device in Example 1; Figure 4b This is a graph showing the deoxygenation and humidification performance of the electrochemical device in Example 2; Figure 4c This is a diagram of the deoxygenation and humidification performance of the electrochemical device in Example 3.

[0085] like Figure 4a~4c As shown, by comparing the deoxygenation time and the time when the humidity is raised to near saturation (85%), it can be observed that in the electrochemical device using the finger-shaped flow channel in Example 1, during the reaction process, the current intensity generated on the cathode side is the largest, the deoxygenation rate is the fastest, and the humidification effect is the best; in the electrochemical device using the straight flow channel in Example 2, during the reaction process, the current intensity generated on the cathode side is the smallest, the deoxygenation rate is the slowest, and the humidification effect is also poor; in the electrochemical device using the serpentine flow channel in Example 3, the current intensity, deoxygenation rate and humidification effect are between Example 1 and Example 2.

[0086] Figure 5 This is a comparison chart of the deoxygenation and humidification performance of the electrochemical devices in Examples 1 to 3 of the present disclosure.

[0087] like Figure 5 As shown, the electrochemical device using the finger-pass channel in Example 1 has the best deoxygenation and humidification performance.

[0088] Figure 6 Schematic diagrams of three flow channel mass transfer modes in the electrochemical devices in Examples 1 to 3, wherein a is a schematic diagram of the straight flow channel mass transfer mode in Example 2; b is a schematic diagram of the serpentine flow channel mass transfer mode in Example 3; and c is a schematic diagram of the finger-shaped flow channel mass transfer mode in Example 1.

[0089] like Figure 6 As shown, it can be observed that the finger-joint channel has a forced convection effect compared with the other two flow channels, and therefore has stronger mass transfer and drainage capabilities.

[0090] Serpentine flow channels and straight flow channels mainly rely on diffusion mass transfer, but due to the limited diffusion speed, the concentration of reactants often forms a concentration gradient on the electrode surface, resulting in a decrease in the local reaction rate. The design of the finger-type flow channel forces the airflow not only to move in the mainstream direction, but also to penetrate laterally in the porous layer of the electrode through the staggered distribution of air inlets and outlets. After the gas enters the flow channel, it must flow through the diffusion layer to contact the catalyst, and then flow back to the flow channel with the product and be discharged. It can ensure that oxygen is evenly distributed on the surface of the catalytic layer, so that more oxygen molecules can contact the active sites of the catalyst at a higher rate, thereby reducing the concentration polarization phenomenon, significantly expanding the effective contact area of ​​the solid-liquid-gas three-phase interface, reducing the appearance of local oxygen transfer restricted areas, and improving the uniformity and overall activity of the catalytic reaction. In addition, the finger-type flow channel also significantly improves the supply efficiency of reactants on the electrode surface, promoting the current density and reaction rate of the oxygen reduction reaction.

[0091] In addition, the forced convection of the finger-crossing channel increases the contact area of ​​the water-gas mass transfer channel, so that the generated liquid water or water vapor can be carried away by the high-velocity airflow more quickly, reducing the retention in the pores of the catalyst layer or diffusion layer. In the cathode oxygen reduction reaction, if the product water cannot be discharged in time, it is easy to accumulate in the micropores of the catalyst layer or diffusion layer, causing local blockage and weakening gas transmission. The finger-crossing channel, due to its more uniform pressure distribution and "cross-flow" layout, significantly improves the gas's ability to carry water, effectively avoids local surges and water accumulation, and ensures that the reaction interface is continuously exposed to fresh gas. At the same time, the finger-crossing channel design makes the concentration of water vapor higher at the outlet of the flow channel, thereby increasing the relative humidity of the exhaust gas.

[0092] The finger-shaped channel improves fluid distribution and enhances convective mass transfer. The efficient mass transfer kinetics not only accelerates the reaction rate of the oxygen reduction reaction, but also indirectly leads to an increase in the water generation rate, which is quickly carried out under the forced convection of the flow channel, thereby further increasing the humidity of the exhaust gas. It enables moisture to leave the electrode interface more promptly, enter the gas phase and be discharged to the outside of the system. The synergistic effect of this rapid drainage and continuous evaporation increases the water vapor content in the exhaust gas, so that under the same working conditions, the finger-shaped channel can increase the relative humidity of the fresh-keeping environment faster and more significantly. Compared with the serpentine flow channel, the straight flow channel has a shorter process, the efficiency of oxygen molecules diffusing to contact the catalyst is lower, and its deoxygenation and humidification performance is also reduced.

[0093] The inlet and outlet pressure drop tests were performed on the three cathode flow channel plates in the electrochemical devices of Examples 1 to 3 of the present disclosure. Figure 7 These are test diagrams of the inlet and outlet pressure drops of three cathode flow channel plates in the electrochemical devices of Examples 1 to 3 of the present disclosure.

[0094] like Figure 7As shown in the figure, compared with the straight flow channel, the serpentine flow channel and the finger-shaped flow channel produce a higher pressure drop due to the increase in flow paths and more complex flow patterns. Specifically, the pressure drop of the finger-shaped flow channel is generally higher than that of the serpentine flow channel, and the pressure drop of the serpentine flow channel is higher than that of the straight flow channel. In addition, the pressure drop of the three flow channels increases with the increase of flow velocity. This trend is closely related to the effect of the geometry of the flow channel on the fluid flow. Due to the slightly higher and evenly distributed pressure difference, the finger-shaped flow channel can promote the gas to penetrate along the electrode thickness (perpendicular to the flow field), thereby making the gas and electrolyte inside the catalyst layer more evenly distributed. Not only does it reduce local dead zones and stagnant areas, but it also optimizes the stability of the microenvironment, which helps to continuously stimulate the active sites of the catalyst and reduce the probability of side reactions.

[0095] The deoxygenation performance of the electrochemical devices of Examples 1 to 3 of the present disclosure was tested under different gas environments, voltages and gas flow rates. Figure 8a This is a test diagram of deoxygenation performance of the electrochemical devices of Examples 1 to 3 of the present disclosure under different voltages and gas flow rates in an air environment; Figure 8b This is a test diagram of the deoxygenation performance of the electrochemical devices of Examples 1 to 3 of the present disclosure at different voltages and gas flow rates under an 8% oxygen concentration environment; Figure 8c This is a test diagram of the deoxygenation performance of the electrochemical devices of Examples 1 to 3 of the present disclosure at different voltages and gas flow rates in an environment of 3% oxygen concentration.

[0096] like Figure 8a~Figure 8c As shown, in the measured 2 L·min -1 、2.5 L·min -1 、3 L·min -1 At an air flow rate of 1.4 V, the current of the electrochemical device with the finger-shaped channel structure in Example 1 is greater than that of the electrochemical device with the serpentine channel structure in Example 3, and the electrochemical device with the serpentine channel structure in Example 3 is greater than that of the electrochemical device with the straight channel structure in Example 2. Moreover, when the applied potential is low (0.8 V), the reaction driving force of the oxygen reduction reaction is weak, the reaction rate is slow, and the difference between the three electrochemical devices is not obvious. As the applied potential gradually increases to 1.4 V, the current difference between the electrochemical device in Example 1 and the electrochemical devices in Examples 2 and 3 becomes larger and larger, and the mass transfer advantage becomes more and more obvious.

[0097] The deoxygenation performance of the electrochemical device was tested using low oxygen concentration gases of 8% oxygen and 3% oxygen (the rest was nitrogen). The results show that at lower oxygen contents, the mass transfer advantage of the electrochemical device with the finger-passage structure in Example 1 is more obvious. This is because under higher oxygen contents such as air, the oxygen supply is sufficient, and the main factor limiting the rate of the cathode oxygen reduction reaction is the rate at which the proton exchange membrane conducts protons. In a low oxygen concentration environment, the diffusion capacity of oxygen molecules is subject to certain restrictions and cannot reach the active sites of the catalyst in time, and gas mass transfer becomes the main factor limiting the rate of the oxygen reduction reaction. However, the forced convection of the finger-passage helps to increase the contact frequency between oxygen and the solid electrode surface through the kinetic action of the airflow, thereby enhancing the oxygen transfer efficiency, thereby showing a more obvious mass transfer advantage at low oxygen concentrations.

[0098] The electrochemical impedance spectroscopy (EIS) of the electrochemical devices of Examples 1 to 3 of the present disclosure when operating at a potential of 0.64 V was tested, and the ohmic impedance (R ohm )、charge transfer impedance(R ct ) and mass transfer impedance (R mt )data.

[0099] Figure 9a This is an electrochemical impedance spectrum test diagram of the electrochemical device of Examples 1 to 3 of the present disclosure, Figure 9b This is a diagram of the impedance fitting results of the electrochemical devices of Examples 1 to 3 of the present disclosure.

[0100] like Figure 9a As shown, the EIS graphs of the three electrochemical devices are composed of two arcs, and the curves are similar in the high-frequency region. In the low-frequency region, the impedance spectra of the electrochemical device using the finger-shaped flow channel in Example 1 and the electrochemical device using the serpentine flow channel in Example 3 show a smaller arc diameter, especially Example 1, which has a smaller arc diameter in the low-frequency region.

[0101] like Figure 9b As shown, R of the electrochemical devices of Examples 1 to 3 ohm , R ct There is no obvious difference. mt The smallest, followed by Example 2, and the R of Example 3 mt The maximum is consistent with the aforementioned deoxygenation performance test results, indicating that the electrochemical device using the finger-type channel in Example 1 can balance the oxygen concentration distribution on the catalyst layer surface (three-phase interface), avoid local excessive polarization, and reduce the influence of mass transfer resistance, further proving that its performance advantage is due to the improved mass transfer capacity.

[0102] The operating stability of the electrochemical devices of Examples 1 to 3 of the present disclosure was tested for 100 h. Fig.10 Stability test diagram of the electrochemical devices of Examples 1 to 3 of the present disclosure.

[0103] like Fig.10 As shown, the electrochemical device of Example 1 has better performance and more superior stability, while the current of the electrochemical device of Example 2 has more obvious fluctuations. This is because the straight flow channel on the cathode side in Example 2 has a shorter flow path and lacks the driving force of forced convection. The water generated during the cathode reaction may accumulate in the flow channel and cannot be discharged in time, thereby affecting the stability of the entire device. Similarly, the stability of the serpentine flow channel in the electrochemical device of Example 3 is also worse than that of the finger-shaped flow channel.

[0104] Example 4

[0105] This comparative example 4 provides an electrochemical device for achieving gas deoxygenation and humidification, which is different from the example 1 in that the electrochemical device of the example 4 of the present disclosure includes: two sets of components connected in series and epoxy resin end plates. Each set of components includes a membrane electrode assembly, an anode side assembly and a cathode side assembly, wherein the cathode flow channel plate in the anode side assembly is a finger-shaped flow channel plate, and the anode flow channel plate in the cathode side assembly is a serpentine flow channel plate.

[0106] The electrochemical device in Example 4 was tested for stability. Fig.11 This is a stability test diagram of the electrochemical device in Example 4 of the present disclosure.

[0107] like Fig.11 As shown in the figure, the deoxygenation and humidification efficiency of the electrochemical device composed of multi-layer flow channel plates is improved compared with that of a single layer. After 400 hours of continuous operation, the performance decay is kept within 10%, indicating that the device has a long service life and high practical application value.

[0108] Example 5

[0109] This embodiment 1 provides an application of an electrochemical device for gas deoxygenation and humidification to extend the shelf life of vegetables.

[0110] The spinach was placed in a 15 L sealed box to simulate the sealed storage environment of vegetables in a warehouse. The air inlet and outlet on the cathode side of the electrochemical device were connected to the sealed box, and a constant voltage of 1.23 V was applied to the power module. At the same time, the pure water flow rate on the anode side was set to 30 ml min -1 , which is used to drive the oxygen evolution reaction (OER) on the anode side. -1 The gas in the sealed box is circulated and pumped into the cathode side of the device at a flow rate for oxygen reduction reaction (ORR). The gas after the reaction then flows back to the sealed box to complete the cycle and keep the spinach in the sealed box fresh.

[0111] Comparative Example 1

[0112] Pressure swing adsorption (PSA) technology was used to preserve the spinach in sealed boxes.

[0113] The O of the sealed box in Example 5 and Comparative Example 1 2 The concentration was reduced to 3%, and then the box was sealed and stored in a constant temperature room at 15°C. Every 24 hours, the box was opened to simulate the opening of a storage warehouse and the vegetables were taken out for photographing and weighing, and then the vegetables were returned to the box for deoxygenation and continued storage.

[0114] Fig.12a This is a diagram showing the deoxygenation effect of Comparative Example 1 of the present disclosure. Figure 12b This is a diagram showing the deoxygenation effect of Example 5 of the present disclosure.

[0115] like Fig.12a and Figure 12b As shown in FIG. 1 , before and after deoxygenation using the PSA technology, the relative humidity in the sealed box decreased from 61% to 36%, while before and after deoxygenation using the electrochemical device disclosed in the present invention, the relative humidity in the sealed box increased from 62% to 89%.

[0116] The best storage conditions for spinach leafy vegetables are humidity 85-95% (RH), O 2 The concentration is 3~5%. Too high oxygen concentration cannot inhibit metabolism and microbial activity, while too low oxygen concentration will cause anaerobic respiration of vegetables to produce alcohol, affecting quality. Therefore, the oxygen concentration and humidity in the sealed box will greatly affect the transpiration rate of spinach leaves, resulting in huge differences in water loss rate during the preservation process.

[0117] Fig.13 This is a diagram showing the preservation effect of spinach in Example 5 and Comparative Example 1 of the present disclosure. Fig.14 It is a graph of the water loss rate of spinach in Example 5 and Comparative Example 1 of the present disclosure.

[0118] like Fig.13 As shown, it can be observed that the spinach preserved by PSA technology after 2-3 days of deoxygenation showed obvious curling and shriveling, and the color became dark. After 5 days, the edges of the leaves had become burnt yellow and the shrinkage was more serious. The spinach preserved by Example 5 of the present disclosure had a better visual preservation effect. The leaves were still full and stretched for 2-3 days, and the color was bright. It was not until 5 days that it became more obvious that it shriveled, and the subsequent shrinkage speed was also slower. After 10 days, the freshness of the vegetables was equivalent to that of the vegetables preserved by PSA technology for 3 days.

[0119] like Fig.14As shown, after 5 days of preservation, the water loss rate of spinach preserved by deoxygenation using PSA technology is as high as over 80%. Under the same time, the water loss rate of spinach preserved by deoxygenation in Example 5 of the present disclosure is only about 40%. After 10 days of deoxygenation preservation, the water loss rate of spinach is still only about 60%, which is significantly lower than the water loss rate of deoxygenation preservation using PSA technology. This shows that compared with the atmosphere-controlled preservation technology using PSA deoxygenation, the deoxygenation and humidification electrochemical device disclosed in the present disclosure can effectively reduce the water loss rate of vegetables and extend the shelf life.

[0120] The above specific embodiments further illustrate the purpose, technical solutions and beneficial effects of the present disclosure in detail. It should be understood that the above are only specific embodiments of the present disclosure and are not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A method for deoxygenating and humidifying gas, characterized in that: The method comprises: Water is introduced into the anode side of an electrochemical device including a proton exchange membrane, and oxygen-containing gas is introduced into the cathode side; Under the driving of an external voltage, an oxygen evolution reaction occurs on the anode side to generate protons; The protons migrate to the cathode side through the proton exchange membrane, undergo an oxygen reduction reaction with the oxygen in the oxygen-containing gas, generate water and discharge it with the unreacted gas, thereby simultaneously achieving deoxygenation and humidification of the cathode side gas.

2. The method according to claim 1, characterized in that The external voltage is a DC voltage of 0.8 to 2.8 V. The concentration of oxygen in the oxygen-containing gas is greater than or equal to 3%, The flow rate of the oxygen-containing gas is 30 ml·min -1 ~3 L min -1 .

3. An electrochemical device for implementing the method for gas deoxygenation and humidification as claimed in claim 1 or 2, characterized in that: The electrochemical device comprises a reaction chamber and a power supply module for providing voltage to the reaction chamber. The reaction chamber comprises: a membrane electrode assembly, an anode side assembly, a cathode side assembly and an end plate, wherein the anode side assembly and the cathode side assembly are located at opposite sides of the membrane electrode assembly, and the end plate is respectively located at one end of the anode side assembly and the cathode side assembly away from the membrane electrode assembly, and the end plate, the anode side assembly and the cathode side assembly are all provided with channels for gas and liquid to flow. Wherein, the membrane electrode assembly is used for conducting protons and catalyzing reactions, and the membrane electrode assembly comprises a proton exchange membrane, and an anode catalyst layer and a cathode catalyst layer respectively coated on both sides of the proton exchange membrane; The anode side assembly is used to pass pure water and generate oxygen evolution reaction, and the anode side assembly includes an anode diffusion layer and an anode flow channel plate in sequence from the membrane electrode assembly outward; The cathode side assembly is used to introduce air and generate oxygen reduction reaction, and the cathode side assembly includes a cathode diffusion layer and a cathode flow channel plate in sequence from the membrane electrode assembly outward; The power supply module is electrically connected to the anode flow channel plate and the cathode flow channel plate through wires.

4. The electrochemical device according to claim 3, characterized in that The proton exchange membrane comprises a cation exchange membrane having a thickness of 85 to 150 μm; The catalyst of the anode catalyst layer includes any one of a platinum carbon catalyst, a platinum single atom catalyst, and a platinum alloy catalyst, and the loading amount of platinum metal in the catalyst is 0.2-1 mg·cm -2 ; The catalyst of the cathode catalyst layer comprises a metal oxide, wherein the metal oxide is selected from any one of iridium dioxide and ruthenium dioxide, and the loading amount of the metal element in the metal oxide is 0.2-1 mg·cm -2 .

5. The electrochemical device according to claim 3, characterized in that The anode diffusion layer is a first porous material including a corrosion-resistant metal coating layer, The cathode diffusion layer is a hydrophobic porous material.

6. The electrochemical device according to claim 5, characterized in that The material of the corrosion-resistant metal coating includes any one of platinum, gold, ruthenium and iridium; The first porous material comprises titanium felt; The hydrophobic porous material includes any one of hydrophobic carbon paper and hydrophobic carbon cloth.

7. The electrochemical device according to claim 3, characterized in that The number of the anode flow channel plate and the cathode flow channel plate is one or more, The materials of the anode flow channel plate and the cathode flow channel plate are both metal materials, wherein the surface of the anode flow channel plate includes a corrosion-resistant metal coating.

8. The electrochemical device according to claim 3, characterized in that The anode channel plate and the cathode channel plate include one or more of a straight channel structure, a serpentine channel structure, and a finger-shaped channel structure.

9. The electrochemical device according to claim 3, characterized in that The electrochemical device also includes a gasket located between the end plate and the flow plate, and / or between the diffusion layer and the flow plate, and the gasket is used to increase the pressure between the end plate and the flow plate and / or between the diffusion layer and the flow plate, wherein the flow plate includes the anode flow plate and the cathode flow plate, and the diffusion layer includes the anode diffusion layer and the cathode diffusion layer.

10. An application of the method according to any one of claims 1 to 2 or the electrochemical device according to any one of claims 3 to 9 to extend the shelf life of food, comprising: The food to be preserved is placed in a closed environment on the cathode side of the electrochemical device, the gas in the closed environment is passed into the cathode side of the electrochemical device, water is passed into the anode side of the electrochemical device, and the closed environment is deoxygenated and humidified using the method for gas deoxygenation and humidification, thereby extending the preservation time of the food.

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