Electrolyte for electrolyzed water oxyhydrogen instrument and preparation method thereof

Abstract

The invention relates to the technical field of water electrolysis oxygen production, in particular to an electrolyte for a water electrolysis hydrogen-oxygen instrument and a preparation method of the electrolyte. The electrolyte sequentially comprises an oxygen barrier layer, a conductive layer and a hydrogen barrier layer from inside to outside. The electrolyte disclosed by the invention realizes the unification of high gas barrier property, excellent conductivity and long-term stability, and can remarkably improve the purity and efficiency of oxygen production of the water electrolysis instrument after being matched with a hydrogen trapping agent to adsorb and absorb H2 generated by a cathode.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrolytic water oxygen production, in particular to an electrolyte for electrolytic water hydrogen oxygen instrument and a preparation method thereof. BACKGROUND

[0002] Plateau climate is a unique climate system formed due to high altitude. High altitude leads to a decrease in oxygen partial pressure in the air, resulting in thin air in the plateau environment, so that people "pant" for breath. People living in the plateau environment for a long time adapt to the plateau environment, but the plateau environment has great health risks to people temporarily living in the plateau due to work or vacation, especially people with respiratory system diseases and people who cannot adapt to the thin oxygen environment of the plateau in a short time, and in severe cases, the life and health of the people are threatened. Therefore, a portable electrolytic water instrument for producing oxygen by electrolyzing water is very practical for people temporarily living in the plateau climate.

[0003] The electrolytic water technology has a wide application prospect in the fields of energy and chemical industry due to its cleanliness and high efficiency. However, there is a problem of hydrogen-oxygen cross permeation in the traditional electrolytic water process, which leads to low product purity and great safety hazards. The existing technology mainly increases the thickness of the diaphragm or adds a noble metal catalyst to improve the selectivity, but this method increases the system impedance and reduces the energy efficiency. In recent years, researchers have tried to develop a multi-layer composite electrolyte to solve this problem, but it has limited gas barrier effect, cannot truly solve the problem of hydrogen-oxygen cross permeation, and has poor interface compatibility of the composite electrolyte and insufficient long-term stability.

[0004] Therefore, it is of great significance to develop a new type of electrolyte that can effectively block gas permeation and has good electrical conductivity and long-term stability. SUMMARY

[0005] In view of the above technical problems, the present application provides an electrolyte for electrolytic water hydrogen oxygen instrument and a preparation method thereof. The three-layer composite electrolyte of the present application realizes the unity of high gas barrier property, excellent electrical conductivity and long-term stability. After the hydrogen produced in the cathode is adsorbed and absorbed by the hydrogen trapping agent, the purity and efficiency of the oxygen production of the electrolytic water instrument can be significantly improved, so that the H2 content in the gas outlet of the electrolytic water instrument is ≤3%, and the oxygen flow is 1-5l / min.

[0006] To solve the above technical problems, the present application adopts the following technical scheme:

[0007] In a first aspect, the present application provides an electrolyte for electrolytic water hydrogen oxygen instrument, which comprises, from inside to outside: an oxygen barrier layer, an electrical conductivity layer and a hydrogen barrier layer;

[0008] The oxygen barrier layer comprises 70-85 parts of EVOH, 8-10 parts of imidazolium salt, 1-5 parts of inorganic nano filler, 1-3 parts of compatibility agent, and 600-1000 parts of organic solvent.

[0009] The conductive layer comprises: 85-95 parts of an organic polymer matrix, 8-10 parts of an imidazolium salt, 1-5 parts of an inorganic nanofiller, 1-3 parts of a compatibilizer, and 600-1000 parts of an organic solvent.

[0010] The hydrogen barrier layer comprises: 70-85 parts of cross-linked PVA, 20-35 parts of polymeric siloxane, 5-15 parts of nano-Al2O3, and 600-1000 parts of organic solvent.

[0011] The electrolyte of this invention is composed of a three-layer membrane structure.

[0012] The oxygen barrier layer uses highly crystalline EVOH to provide a dense barrier against oxygen permeability. The imidazolium salt not only interacts with the permeating oxygen, preventing further permeation, but also acts as a proton carrier, endowing the oxygen barrier layer with proton resistance. The transport efficiency of the oxygen barrier layer is much higher than that of oxygen, achieving high ion selectivity for protons. The compatibilizer can improve the interfacial compatibility with adjacent conductive layers. The labyrinth effect of inorganic nanofillers further prevents oxygen permeation. The synergistic effect of inorganic nanofillers and EVOH can also inhibit the crystallization and migration of imidazolium salt. Finally, under the synergistic effect of EVOH, imidazolium salt and inorganic nanofillers, the oxygen barrier layer is endowed with superior oxygen barrier performance and high ion selectivity for protons, achieving oxygen barrier without proton barrier.

[0013] The main chain and aliphatic side chains of the organic polymer matrix in the conductive layer form hydrophobic regions, providing mechanical support and basic proton sites. They exhibit excellent electronic insulation, effectively blocking electron flow and achieving physical isolation of electrons. The dense three-dimensional network provided by the organic polymer matrix, in synergy with the inorganic nanofiller with a maze effect, not only further prevents oxygen permeation but also inhibits the crystallization and migration of imidazolium salt. The imidazolium salt added to this conductive layer can not only further interact with oxygen to prevent oxygen diffusion and permeation but also act as a proton carrier, greatly improving conductivity.

[0014] The hydrogen barrier layer utilizes a dense hydrogen bond network formed by cross-linked PVA and polymerized siloxane to effectively block the penetration of small molecule hydrogen gas. (Nanoscale) As a physical cross-linking point, it enhances the mechanical properties of the hydrogen barrier layer and extends the hydrogen diffusion path.

[0015] Finally, through the synergistic effect of the oxygen barrier layer, the conductive layer, and the hydrogen-binding layer, a composite electrolyte is obtained. This electrolyte can strictly separate the oxygen generated at the anode and the hydrogen generated at the cathode, avoiding the mixing of hydrogen and oxygen. This solves the problem of hydrogen-oxygen cross-permeation in the traditional water electrolysis process, prevents explosions, improves the safety factor, and ensures the reliability and lifespan of the equipment. It achieves a balance of high gas barrier properties, excellent conductivity, and long-term stability. When combined with a hydrogen scavenger to adsorb and absorb H2 generated at the cathode, it can significantly improve the purity and efficiency of oxygen production in the water electrolyzer, resulting in an H2 content of ≤3% and an oxygen flow rate of 1-5 L / min at the gas outlet of the water electrolyzer.

[0016] Preferably, the imidazolium salt comprises: 1-butyl-3-methylimidazolium tetrachloroferric acid, 1-allyl-3-methylimidazolium chloride, or 1-ethyl-3-methylimidazolium methane sulfonate;

[0017] The compatibilizer is SEBS-g-MAH;

[0018] The organic solvent is N,N-dimethylformamide.

[0019] Preferably, the organic polymer matrix is ​​prepared by dehydration grafting modification of sulfonated polyether ketone and fatty alcohol polyethylene glycol monoether in a molar ratio of 1-2:1.

[0020] Preferably, the method for preparing the organic polymer matrix includes: dissolving a sulfonated polyether ketone that has been pre-washed and dried in N,N-dimethylformamide to obtain a sulfonated polyether ketone solution;

[0021] Under nitrogen protection, succinic anhydride and anhydrous aluminum trichloride were added to the sulfonated polyetherketone solution in an ice-water bath, and the temperature was raised to room temperature. After reacting for 12-24 hours, the reaction solution was poured into ice-cold ethanol / water to precipitate. The solution was filtered, and the filter cake was washed 2-3 times with dilute sulfuric acid and then washed with pure water until neutral. The solution was then vacuum dried at 50-60°C and ≤-0.095MPa for 24-48 hours to obtain carboxylated sulfonated polyetherketone.

[0022] The carboxylated sulfonated polyether ketone was dissolved in N,N-dimethylformamide, DCC and DMAP were added, and the mixture was reacted at room temperature for 2-4 hours. Then, fatty alcohol polyethylene glycol monoether was added, and the mixture was reacted at 50-70°C for 24-48 hours under nitrogen protection. After precipitation, the mixture was precipitated with diethyl ether, filtered, and the filter cake was extracted with ethanol / water by Soxhlet extraction for 24-48 hours. The cake was then vacuum dried at 50-60°C and ≤-0.095MPa for 24-48 hours to obtain the organic polymer matrix.

[0023] This invention utilizes the dehydration reaction of sulfonic acid groups and hydroxyl groups to graft and modify sulfonated polyether ether ketone copolymers containing aliphatic long side chains as an organic polymer matrix.

[0024] Preferably, the degree of sulfonation of the sulfonated polyether ketone is 65%-70%; and the molecular weight of the fatty alcohol polyethylene glycol monoether is 400-600.

[0025] The mass ratio of the sulfonated polyether ketone to succinic anhydride is 1:1.1-1.5;

[0026] The amount of anhydrous aluminum trichloride used is 1%-5% of the mass of the sulfonated polyetherketone;

[0027] The mass ratio of the carboxylated sulfonated polyether ketone, DCC, and fatty alcohol polyethylene glycol monoether is 1:(1-1.8):(1-1.2).

[0028] The amount of DMAP used is 1%-5% of the mass of the carboxylated sulfonated polyetherketone.

[0029] Preferably, the inorganic nanofiller comprises: modified nano-zirconia and modified graphene in a mass ratio of 1-2:1.

[0030] In this invention, inorganic nanofillers serve as the dispersed phase, imparting mechanical strength and stability to the electrolyte. Simultaneously, the abundant active sites on the surface of the inorganic nanofillers further enhance proton conductivity. Furthermore, the formation of a maze effect within each layer significantly extends the oxygen penetration path, substantially improving oxygen barrier properties, while also enhancing proton H+ resistance. + Interfacial transport along the surface of inorganic nanofillers has a relatively small impact.

[0031] Preferably, the silane coupling agent is dissolved in anhydrous ethanol, acetic acid is added dropwise to adjust the pH to 4-5, and the mixture is stirred at room temperature for 0.5 h to obtain a pre-hydrolyzed silane coupling agent.

[0032] The modified nano-zirconia is prepared by dispersing dried nano-zirconia in a pre-hydrolyzed silane coupling agent, stirring and reacting at 60-80℃ for 4-6 hours, separating the solid and liquid, washing the solid with anhydrous ethanol 3-4 times, and vacuum drying at 70-80℃ for 6-8 hours to obtain modified nano-zirconia.

[0033] Among them, the nano-zirconia powder is vacuum dried at 100-120℃ for 2-4 hours to remove the surface physically adsorbed water and obtain dried nano-zirconia.

[0034] The silane coupling agent was dissolved in anhydrous ethanol, and acetic acid was added dropwise to adjust the pH to 4-5. The mixture was stirred at room temperature for 0.5 h to obtain the pre-hydrolyzed silane coupling agent.

[0035] The dried nano-zirconia accounts for 5%-10% of the mass of the pre-hydrolyzed silane coupling agent;

[0036] The concentration of the silane coupling agent dissolved in anhydrous ethanol is 2% (v / v);

[0037] The modified graphene is prepared by adding dried graphene oxide into anhydrous ethanol, ultrasonically dispersing it for 0.5 h, then adding a pre-hydrolyzed silane coupling agent, stirring the reaction at 70-80℃ for 6-8 h, separating the solid and liquid, washing the solid with anhydrous ethanol 3-4 times, and vacuum drying at 70-80℃ for 6-8 h to obtain the modified graphene.

[0038] In this process, graphene oxide is vacuum dried at 60-80℃ for 2-4 hours to obtain dried graphene oxide.

[0039] The concentration of the dried graphene oxide dissolved in anhydrous ethanol is 1-2 mg / mL;

[0040] The mass ratio of the dried graphene oxide to the pre-hydrolyzed silane coupling agent is 1:1-3.

[0041] The silane coupling agent is any one of 3-aminopropyltriethoxysilane (APTES), etheroxypropyltrimethoxysilane (GPTMS), or 3-isocyanatepropyltriethoxysilane (IPTES).

[0042] The inorganic nanofiller of this invention is obtained by modifying nano-zirconia and graphene oxide with a silane coupling agent. Through silane coupling agent modification, hydrophilic groups, such as sulfonic acid groups, -COOH, and -OH, are grafted onto the surface of the nano-zirconia and graphene oxide. On the one hand, this improves the compatibility of the inorganic nanofiller with the organic polymer matrix and prevents aggregation; on the other hand, the inorganic nanofiller containing hydrophilic groups forms a three-dimensional interconnected proton channel network in the oxygen barrier layer and conductive layer, which can attract bound water molecules and achieve proton (H+) absorption. + or H3O + High electrical conductivity allows for the transmission of protons while maintaining the flexibility and wettability of the proton channel, preventing water from freezing and ensuring a smooth proton transport path.

[0043] Preferably, the crosslinked PVA is T-330 or T-380; the polymeric siloxane is polydimethylsiloxane BYPM-P7266-DMS or organosilicon powder KMP-600 or KMP-601.

[0044] Preferably, the nano-Al2O3 includes: HN-L10Y, WHA-402-3, or N612.

[0045] Secondly, the present invention also provides a method for preparing the above-mentioned electrolyte, comprising:

[0046] S1. Coat the oxygen barrier layer slurry on the PET release film, heat it to 50-65℃ at 5-10℃ / h, and dry and cure it for at least 2 hours. This slow heating rate can prevent the formation of pores in the film due to excessive speed, thus obtaining the oxygen barrier layer.

[0047] S2. After impregnating the surface of the oxygen barrier layer with N,N-dimethylformamide, the oxygen barrier layer is slightly swollen by using a trace amount of solvent on the surface to enhance the interfacial bonding. The conductive layer slurry is then immediately applied, heated to 50-65°C at 5-10°C / h, and slowly dried for 0.5-1h to initially solidify into a conductive layer.

[0048] S3. Next, apply a hydrogen barrier slurry to the conductive layer, heat it to 50-65°C at 5-10°C / h, and dry it for at least 0.5h to initially dry and gel. Then, heat it to 100-120°C at 3-8°C / h for 1-2h to perform deep cross-linking of the cross-linked PVA and condensation curing of the siloxane, thereby obtaining a strong and tough three-layer composite film. Then, peel the composite film off from the PET release film and cure it at 60°C in a vacuum environment for 24h to obtain the electrolyte.

[0049] This invention employs a layer-by-layer coating-in-situ composite technology to prepare the electrolyte, achieving a strong physical / chemical bond between the layers and avoiding peeling. An oxygen barrier layer is coated and fully cured on a PET release film. Then, a layer of conductive layer solvent DMF is lightly impregnated onto the cured oxygen barrier layer surface, causing partial swelling and loosening of the polymer chains on the oxygen barrier layer surface. Immediately afterward, a conductive layer slurry is coated onto the treated oxygen barrier layer surface. At this point, the solvents partially dissolve, forming an interpenetrating network at the interface, achieving strong bonding. Under mild conditions, the conductive layer is slowly dried until it is "touch dry," indicating surface curing, with the interior slightly soft. A hydrogen barrier layer slurry is immediately coated, followed by programmed temperature increases to simultaneously complete the thorough drying of the conductive layer and the deep cross-linking and curing of the hydrogen barrier layer. Finally, the composite film is peeled from the PET release film and aged at 60°C in a vacuum environment for 24 hours to obtain a stable three-layer composite electrolyte.

[0050] Preferably, in S1, the preparation method of the oxygen barrier layer slurry is as follows: at 90-120℃ and 300-400rpm, EVOH is dissolved in N,N-dimethylformamide, cooled to 60℃, and at 1000-1500rpm, imidazolium salt and compatibilizer are added and stirred evenly. Then, inorganic nanofiller is added and ultrasonically treated for at least 0.5h, and ball-milled for at least 6h. No visible agglomeration is observed, thus forming a stable and uniform oxygen barrier layer slurry.

[0051] In S2, the conductive layer slurry is prepared as follows: At 60-80℃ and 300-400 rpm, an organic polymer matrix is ​​dissolved in N,N-dimethylformamide; then, at 1000-1500 rpm, imidazolium salt and a compatibilizer are added and stirred until homogeneous. Next, inorganic nanofillers are added, and the mixture is ultrasonically treated for at least 0.5 h and ball-milled for at least 6 h to obtain the conductive layer slurry; and / or

[0052] In S3, the preparation method of the hydrogen barrier layer slurry is as follows: at 90-120℃, cross-linked PVA is dissolved in N,N-dimethylformamide, the temperature is lowered to 60℃, polymeric siloxane is added and stirred evenly, nano-Al2O3 is added and ultrasonically treated for at least 0.5h, and ball milled for at least 6h to obtain the hydrogen barrier layer slurry.

[0053] Thirdly, the present invention also provides the above-mentioned electrolyte or the electrolyte obtained by the above-mentioned electrolyte preparation method for the preparation of oxygen in a water electrolysis hydrogen-oxygen apparatus, comprising: the electrolyte being installed in the water electrolysis hydrogen-oxygen apparatus to block the permeation of H2 and O2;

[0054] The water electrolysis hydrogen-oxygen apparatus also includes a packed column at the upper end of the cathode; the packed column is filled with a hydrogen scavenging agent; after the hydrogen scavenging agent adsorbs and absorbs the H2 generated by the cathode, the H2 content in the gas outlet is ≤3%, and the oxygen flow rate is 1-5 l / min;

[0055] The hydrogen scavenger is composed of polyvinyl alcohol hydrogel, potassium graphite intercalation compound, and COF material in a mass ratio of 1-5:1:1; the potassium graphite intercalation compound is KC8 powder; and the COF material is COF-1.

[0056] The hydrogen scavenger is prepared by adding KC8 powder with a particle size of <38µm into 5wt% hydrophobic PTFE emulsion, rolling it into Φ0.5mm microspheres, and drying it at 80℃ for 2h to obtain microspheres with a surface hydrophobic angle of 120-125°.

[0057] The microspheres were dispersed in mesitylene, and Tp and Pa-1 monomers were added. The mixture was reacted at 120°C for 12 h to obtain COF@KC8 particles with a shell thickness of 15 µm and a pore size of 1.0 nm.

[0058] The COF@KC8 particles were immersed in a mixed solution of 3% PVA aqueous solution and 5wt% glycerol for 10 seconds, then frozen at -40℃ for 30 minutes, and then vacuum sublimated and dried for 6 hours to obtain a hydrogen scavenger with a skin thickness of 5-10µm. Attached Figure Description

[0059] Figure 1 This is a schematic diagram of the three-layer structure of the electrolyte of the present invention;

[0060] Figure 2 This is a flowchart of the electrolyte preparation process of the present invention;

[0061] Figure 3 This is a schematic diagram of the structure of a water electrolysis hydrogen-oxygen apparatus;

[0062] Figure 4 This figure shows the results of long-term operational stability testing of the electrolyte of this invention installed in a water electrolysis hydrogen-oxygen analyzer. Detailed Implementation

[0063] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0064] Example 1

[0065] (1) Preparation of organic polymer matrix:

[0066] 10g of sulfonated polyether ketone (SPEEK) with a sulfonation degree of 68% was washed with water, dried, and then dissolved in 100ml of LDMF.

[0067] Under nitrogen protection, 11g of succinic anhydride and 0.3g of anhydrous nitrogen were added to an ice-water bath. After reacting at room temperature for 18 hours, the reaction solution was poured into ice-cold ethanol / water (1:1) to precipitate, filtered, washed three times with dilute sulfuric acid, washed with pure water until neutral, and dried under vacuum at 55°C and -0.098 MPa for 36 hours to obtain carboxylated SPEEK.

[0068] 10g of carboxylated SPEEK was dissolved in 100ml of LDM, 12g of DCC and 0.3g of DMAP were added, and the mixture was reacted at room temperature for 3h. Then, 11g of fatty alcohol polyethylene glycol monoether (commercial model: C12 / C16 / C18Ethrt-PEG-SS-600) with a molecular weight of 500 was added. The mixture was reacted at 60°C for 36h under nitrogen protection, ether was added to precipitate the product, and the product was extracted with ethanol / water by Soxhlet for 36h. The product was then vacuum dried at 55°C for 36h to obtain the organic polymer matrix.

[0069] (2) Preparation of inorganic nanofillers:

[0070] Pre-hydrolyzed silane coupling agent: Dissolve APTES in anhydrous ethanol (2% v / v), add acetic acid dropwise to adjust pH to 4.5, stir at room temperature for 0.5 h to obtain the pre-hydrolyzed silane coupling agent.

[0071] Modified nano-zirconia: [The text abruptly ends here, likely due to an incomplete sentence or a formatting error.] Vacuum dry at 110°C for 3 hours, then weigh the dried product. (dry Disperse the pre-hydrolyzed silane coupling agent APTES (7 wt% of the pre-hydrolyzed silane coupling agent), react at 70°C for 5 h, filter, wash the product three times with ethanol, and vacuum dry at 75°C for 7 h to obtain modified nano-zirconia.

[0072] Modified graphene: Graphene oxide was vacuum dried at 70°C for 3 hours to obtain dried graphene oxide; 1.5 g of dried graphene oxide was weighed and added to 1000 mL of ethanol to obtain a 1.5 mg / mL graphene oxide ethanol dispersion, which was sonicated for 0.5 hours. Pre-hydrolyzed silane coupling agent APTES (GO:APTES=1:2) was added to the graphene oxide ethanol dispersion, and the mixture was reacted at 75°C for 7 hours. After filtration, the product was washed three times with ethanol and vacuum dried at 75°C for 7 hours to obtain modified graphene.

[0073] Modified nano-zirconia and modified graphene were mixed at a mass ratio of 1.5:1 to obtain inorganic nanofillers.

[0074] (3) Three-layer composite electrolyte

[0075] The modified three-layer composite electrolyte consists of, from the inside out: an oxygen barrier layer, a conductive layer, and a hydrogen barrier layer.

[0076] The oxygen barrier layer includes: 75 parts of EVOH, 9 parts of 1-butyl-3-methylimidazolium tetrachloroferric acid, 3 parts of inorganic nanofiller, 2 parts of compatibilizer (commercial model: SEBS-g-MAH), and 800 parts of DMF.

[0077] The conductive layer comprises: 90 parts of organic polymer matrix, 9 parts of 1-butyl-3-methylimidazolium tetrachloroferric acid, 3 parts of inorganic nanofiller, 2 parts of compatibilizer (commercial model: SEBS-g-MAH), and 800 parts of DMF.

[0078] The hydrogen barrier layer comprises: 75 parts cross-linked PVA (product model: T-330), 20-35 parts polymeric siloxane (BYPM-P7266-DMS), 5-15 parts nano-Al2O3 (product model: HN-L10Y), and 800 parts DMF.

[0079] (4) Preparation of three-layer composite electrolyte

[0080] Preparation of three-layer slurry:

[0081] Oxygen barrier slurry: At 100°C and 350 rpm, 75 parts of EVOH were completely dissolved in 800 parts of DMF. The temperature was then lowered to 60°C. At 1500 rpm, 9 parts of 1-butyl-3-methylimidazolium tetrachloroferric acid and 2 parts of compatibilizer (commercial model: SEBS-g-MAH) were added and stirred until homogeneous. Then, 3 parts of inorganic nanofiller were added and ultrasonicated for 1 hour to obtain a mixed slurry. The mixed slurry was then placed in a high-energy ball mill and ball-milled for 8 hours to obtain the oxygen barrier slurry.

[0082] Conductive layer slurry: At 70°C and 350 rpm, 90 parts of organic polymer matrix were completely dissolved in 800 parts of DMF. Then, at 1500 rpm, 9 parts of 1-butyl-3-methylimidazolium tetrachloroferric acid and 2 parts of compatibilizer SEBS-g-MAH were added and stirred until uniform. Then, 3 parts of inorganic nanofiller were added and ultrasonicated for 1 hour to obtain a mixed slurry. The mixed slurry was placed in a high-energy ball mill and ball-milled for 8 hours to obtain the conductive layer slurry.

[0083] Hydrogen barrier slurry: At 100°C and 350 rpm, 75 parts of cross-linked PVA (commercial model: T-330) were completely dissolved in 800g DMF. The temperature was lowered to 60°C, and 25 parts of polydimethylsiloxane (BYPM-P7266-DMS) were added and stirred until homogeneous. Then, 10 parts of nano Al2O3 (commercial model: HN-L10Y) were added and ultrasonicated for 1 hour to obtain a mixed slurry. The mixed slurry was then placed in a high-energy ball mill and ball-milled for 8 hours.

[0084] Preparation of three-layer composite electrolyte

[0085] S1. Coat an oxygen barrier layer slurry onto a PET release film, heat it to 60°C at a rate of 7°C / h and dry it for 2.5h to obtain an oxygen barrier layer with a thickness of 50μm.

[0086] S2. After impregnating the surface of the oxygen barrier layer with DMF, immediately apply the conductive layer slurry and dry it at 7°C / h to 60°C for 0.8h to obtain a pre-cured conductive layer with a thickness of 80μm.

[0087] S3. Next, a hydrogen barrier slurry is coated on the surface of the conductive layer, heated to 60°C at 7°C / h and dried for 1h, then heated to 120°C at 5°C / h and heat-treated for 1.5h to obtain a composite film composed of an oxygen barrier layer / conductive layer / hydrogen barrier layer, wherein the hydrogen barrier layer is 60μm thick and the composite film is 190μm thick; the composite film is peeled off from the PET release film and placed in a 60°C vacuum drying oven for vacuum curing for 24h to obtain an electrolyte with a three-layer composite structure.

[0088] (5) Preparation of hydrogen scavengers:

[0089] The hydrogen scavenger is prepared as "dry-wet partitioned" particles, rather than simply mixed into a clump.

[0090] Core: KC8 powder with a particle size of <38µm was added to 5wt% hydrophobic PTFE emulsion, rolled into 0.5mm spheres, and dried at 80℃ for 2h to obtain microspheres with a surface hydrophobic angle of 120-125°.

[0091] Shell: The above microspheres were dispersed in mesitylene, and Tp and Pa-1 monomers were added. The mixture was reacted at 120°C for 12 h to obtain COF@KC8 particles with a shell thickness of 15 µm and a pore size of 1.0 nm.

[0092] Outermost layer: PVA dry gel layer

[0093] The COF@KC8 particles were impregnated in a mixture of 3% PVA and 5% glycerol for 10 seconds, then frozen at -40°C for 30 minutes, and finally vacuum sublimated at 60°C for 6 hours to obtain a thick PVA dry gel layer with a skin thickness of 8 μm.

[0094] The final hydrogen scavenger particles have a water content of <3wt%, but still possess a sufficient hydrogen bond network to temporarily "pin" them together. Microbubbles.

[0095] Hydrogen capture mechanism:

[0096] It must first pass through the PVA dry gel skin, then enter the COF micropores, and finally reach... The interlayer is chemically absorbed; and liquid water is doubly blocked by the hydrophobic PTFE and PVA dry gel skin within 24 hours. Hydrolysis rate <2%.

[0097] Example 2

[0098] The oxygen barrier layer contains 70 parts EVOH, the conductive organic polymer matrix contains 85 parts, the hydrogen barrier layer contains 70 parts crosslinked PVA, and other conditions are the same as in Example 1.

[0099] Example 3

[0100] The oxygen barrier layer contains 85 parts EVOH, the conductive layer contains 95 parts polymer matrix, and the hydrogen barrier layer contains 85 parts crosslinked PVA. Other conditions are the same as in Example 1.

[0101] Comparative Example 1

[0102] The electrolyte in this embodiment is a single-layer conductive film.

[0103] Using only the conductive layer material from Example 1, a single-layer film with a thickness of 190 μm was prepared as the electrolyte.

[0104] Comparative Example 2

[0105] The electrolyte in this embodiment is a bilayer structure without a hydrogen barrier layer.

[0106] Using the oxygen barrier layer and conductive layer from Example 1, a bilayer composite film with a total thickness of 190 μm was prepared.

[0107] Comparative Example 3

[0108] The electrolyte in this embodiment has a three-layer structure, but no inorganic nanofillers are added to each layer, and other conditions are the same as in Example 1.

[0109] Comparative Example 4

[0110] The electrolyte in this embodiment has a three-layer structure, but imidazolium salts are not added to each layer, and other conditions are the same as in Example 1.

[0111] Comparative Example 5

[0112] Commercially available Nafion 117 membrane with a thickness of 180 μm was used as the electrolyte.

[0113] Verification Example

[0114] 1. Hydrogen-oxygen permeability test

[0115] The electrolytes prepared in Examples 1-4 and Comparative Examples 1-4 were tested for gas permeability according to ASTM D1434 at 25°C and 50% RH. The results are shown in Table 1.

[0116] Table 1 Gas Permeability

[0117]

[0118] As shown in Table 1, compared to Comparative Examples 1-5, the three-layer composite electrolytes of Examples 1-3 of the present invention significantly reduced the gas permeability of hydrogen and oxygen. The data from Examples 1-3 and Comparative Examples 3 and 4 show that the addition of inorganic nanofillers and imidazolium salts further improved the gas barrier properties.

[0119] 2. Proton conductivity test

[0120] The three-layer composite electrolytes prepared in Examples 1-3 and the Nafion membrane of Comparative Example 5 were placed at 80°C and 100%RH, and the proton conductivity was tested using the four-electrode AC impedance method. The results are shown in Table 2.

[0121] Table 2 Comparison of Proton Conductivity

[0122]

[0123] As shown in Table 2, the proton conductivity of the three-layer composite electrolytes in Examples 1-3 is above 0.86 S / cm, which is significantly higher than that of the Nafion membrane in Comparative Example 5 (0.061 S / cm). This indicates that the proton conductivity of the electrolyte of the present invention is significantly better than that of the traditional Nafion membrane. This is due to the synergistic proton transfer effect of each component in the conductive layer of the electrolyte of the present invention, which significantly improves the proton conductivity of the electrolyte.

[0124] 3. Electrolysis performance test

[0125] The electrolytes prepared in Examples 1-3, Comparative Example 1, and the Nafion membrane electrolyte in Comparative Example 5 were assembled into a water electrolyzer (effective area 25 cm², current density 1 A / cm², 80°C). A packed column was installed at the upper end of the cathode of the water electrolyzer. The packed column was filled with a hydrogen scavenger to adsorb the H2 generated at the cathode. The results are shown in Table 3.

[0126] Table 3 Comparison of water electrolysis performance

[0127]

[0128] As shown in Table 4, the electrolytes in Examples 1-3 of the present invention significantly improved the oxygen purity at the outlet of the water electrolyzer to be higher than 99.7% and the hydrogen content to be lower than 0.85%, and reduced the electrolysis voltage to below 1.68V. The energy efficiency was increased by 8.7 percentage points compared with Comparative Example 1.

[0129] 4. Long-term stability test

[0130] The electrolyte prepared in Example 1 was assembled and installed in a water electrolysis hydrogen-oxygen analyzer, and continuously operated for 5000 hours at 1 A / cm² and 80°C. The results are as follows. Figure 4 As shown.

[0131] from Figure 4 It can be seen that after 5000 hours of operation, the electrolyte performance retention rate of this invention is above 80%, but the electrolyte operating voltage increases slightly, which may be related to the migration of imidazolium salt. Overall, this indicates that the electrolyte of this invention has excellent long-term stability.

[0132] The electrolyte of this invention can be widely used in: medical oxygen generation equipment to produce high-purity medical oxygen, semiconductor industry to provide ultra-high purity oxygen, and aerospace to provide life support oxygen for confined spaces.

[0133] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. An electrolyte for a water electrolysis hydrogen-oxygen analyzer, characterized in that, The electrolyte consists of, from the inside out, an oxygen barrier layer, a conductive layer, and a hydrogen barrier layer. The oxygen barrier layer comprises: 70-85 parts of EVOH, 8-10 parts of imidazolium salt, 1-5 parts of inorganic nanofiller, 1-3 parts of compatibilizer, and 600-1000 parts of organic solvent. The conductive layer comprises: 85-95 parts of an organic polymer matrix, 8-10 parts of an imidazolium salt, 1-5 parts of an inorganic nanofiller, 1-3 parts of a compatibilizer, and 600-1000 parts of an organic solvent. The hydrogen barrier layer comprises: 70-85 parts of cross-linked PVA, 20-35 parts of polymeric siloxane, 5-15 parts of nano-Al2O3, and 600-1000 parts of organic solvent.

2. The electrolyte according to claim 1, characterized in that, The imidazolium salt comprises: 1-butyl-3-methylimidazolium tetrachloroferric acid, 1-allyl-3-methylimidazolium chloride, or 1-ethyl-3-methylimidazolium methanesulfonate; and / or The compatibilizer is SEBS-g-MAH; and / or The organic solvent is N,N-dimethylformamide.

3. The electrolyte according to claim 1, characterized in that, The organic polymer matrix is ​​formed by dehydration grafting modification of sulfonated polyether ketone and fatty alcohol polyethylene glycol monoether in a molar ratio of 1-2:

1.

4. The electrolyte according to claim 3, characterized in that, The method for preparing the organic polymer matrix includes: dissolving sulfonated polyether ketone, which has been pre-washed and dried, in N,N-dimethylformamide to obtain a sulfonated polyether ketone solution; Under nitrogen protection, succinic anhydride and anhydrous aluminum trichloride were added to the sulfonated polyetherketone solution in an ice-water bath, and the temperature was raised to room temperature. After reacting for 12-24 hours, the reaction solution was poured into ice-cold ethanol / water to precipitate. The solution was filtered, and the filter cake was washed 2-3 times with dilute sulfuric acid and then washed with pure water until neutral. The solution was then vacuum dried at 50-60°C and ≤-0.095 MPa for 24-48 hours to obtain carboxylated sulfonated polyetherketone. The carboxylated sulfonated polyether ketone was dissolved in N,N-dimethylformamide, DCC and DMAP were added, and the mixture was reacted at room temperature for 2-4 hours. Then, fatty alcohol polyethylene glycol monoether was added, and the mixture was reacted at 50-70°C for 24-48 hours under nitrogen protection. After precipitation, the mixture was precipitated with diethyl ether, filtered, and the filter cake was extracted with ethanol / water by Soxhlet extraction for 24-48 hours. The cake was then vacuum dried at 50-60°C and ≤-0.095 MPa for 24-48 hours to obtain the organic polymer matrix.

5. The electrolyte according to claim 3, characterized in that, The sulfonated polyether ketone has a sulfonation degree of 65%-70%; the fatty alcohol polyethylene glycol monoether has a molecular weight of 400-600; and / or The mass ratio of the sulfonated polyetherketone to succinic anhydride is 1:1.1-1.5; and / or The amount of anhydrous aluminum trichloride used is 1%-5% of the mass of the sulfonated polyetherketone; and / or The mass ratio of the carboxylated sulfonated polyetherketone, DCC, and fatty alcohol polyethylene glycol monoether is 1:(1-1.8):(1-1.2); and / or The amount of DMAP used is 1%-5% of the mass of the carboxylated sulfonated polyetherketone.

6. The electrolyte according to claim 1, characterized in that, The inorganic nanofiller comprises: modified nano-zirconia and modified graphene in a mass ratio of 1-2:1; and / or The modified nano-zirconia is prepared by dispersing dried nano-zirconia in a pre-hydrolyzed silane coupling agent, stirring and reacting at 60-80℃ for 4-6 hours, separating the solid and liquid, washing the solid with anhydrous ethanol 3-4 times, and vacuum drying at 70-80℃ for 6-8 hours to obtain modified nano-zirconia. Among them, nano-zirconia powder is vacuum dried at 100-120℃ for 2-4 hours to obtain dried nano-zirconia; The silane coupling agent was dissolved in anhydrous ethanol, and acetic acid was added dropwise to adjust the pH to 4-5. The mixture was stirred at room temperature for 0.5 h to obtain the pre-hydrolyzed silane coupling agent. The dried nano-zirconia accounts for 5%-10% of the mass of the pre-hydrolyzed silane coupling agent; The concentration of the silane coupling agent dissolved in anhydrous ethanol is 2% (v / v); and / or The modified graphene is prepared by adding dried graphene oxide into anhydrous ethanol, ultrasonically dispersing it for 0.5 h, then adding a pre-hydrolyzed silane coupling agent, stirring the reaction at 70-80℃ for 6-8 h, separating the solid and liquid, washing the solid with anhydrous ethanol 3-4 times, and vacuum drying at 70-80℃ for 6-8 h to obtain the modified graphene. In this process, graphene oxide is vacuum dried at 60-80℃ for 2-4 hours to obtain dried graphene oxide. The concentration of the dried graphene oxide dissolved in anhydrous ethanol is 1-2 mg / mL; The mass ratio of the dried graphene oxide to the pre-hydrolyzed silane coupling agent is 1:1-3; The silane coupling agent is any one of 3-aminopropyltriethoxysilane, etheroxypropyltrimethoxysilane, or 3-isocyanatepropyltriethoxysilane.

7. The electrolyte according to claim 1, characterized in that, The crosslinked PVA is T-330 or T-380; the polymeric siloxane is polydimethylsiloxane or organosilicon powder; the nano-Al2O3 includes: HN-L10Y, WHA-402-3 or N612.

8. A method for preparing the electrolyte according to any one of claims 1-7, comprising: S1. Coat the oxygen barrier layer slurry onto the PET release film, heat it to 50-65℃ at 5-10℃ / h, and dry and cure it for at least 2 hours to obtain the oxygen barrier layer. S2. After impregnating the surface of the oxygen barrier layer with N,N-dimethylformamide, immediately apply the conductive layer slurry, heat it to 50-65°C at 5-10°C / h, dry it for 0.5-1h, and initially cure it into a conductive layer. S3. Next, a hydrogen barrier slurry is coated on the conductive layer, heated to 50-65°C at 5-10°C / h, dried for at least 0.5h, and then heated to 100-120°C at 3-8°C / h for 1-2h heat treatment to obtain a composite film composed of an oxygen barrier layer / conductive layer / hydrogen barrier layer; the composite film is peeled off from the PET release film and cured at 60°C in a vacuum environment for 24h to obtain the electrolyte.

9. The method for preparing the electrolyte as described in claim 8, characterized in that, In S1, the preparation method of the oxygen barrier slurry is as follows: EVOH is dissolved in N,N-dimethylformamide at 90-120℃ and 300-400 rpm; the temperature is lowered to 60℃; imidazolium salt and compatibilizer are added at 1000-1500 rpm and stirred until homogeneous; then inorganic nanofiller is added; the mixture is ultrasonically treated for at least 0.5 h and ball-milled for at least 6 h to obtain the oxygen barrier slurry; and / or In S2, the conductive layer slurry is prepared as follows: At 60-80℃ and 300-400 rpm, an organic polymer matrix is ​​dissolved in N,N-dimethylformamide; then, at 1000-1500 rpm, imidazolium salt and a compatibilizer are added and stirred until homogeneous. Next, inorganic nanofillers are added, and the mixture is ultrasonically treated for at least 0.5 h and ball-milled for at least 6 h to obtain the conductive layer slurry; and / or In S3, the preparation method of the hydrogen barrier layer slurry is as follows: at 90-120℃ and 300-400rpm, cross-linked PVA is dissolved in N,N-dimethylformamide, cooled to 60℃, polymeric siloxane is added and stirred evenly, nano-Al2O3 is added and ultrasonically treated for at least 0.5h, and ball-milled for at least 6h to obtain the hydrogen barrier layer slurry.

10. Using the electrolyte according to any one of claims 1-7 or the electrolyte prepared by the method according to claim 8 in a water electrolysis hydrogen-oxygen apparatus to produce oxygen, wherein the electrolyte is installed in the water electrolysis hydrogen-oxygen apparatus; characterized in that, The water electrolysis hydrogen-oxygen apparatus also includes a packed column at the upper end of the cathode; the packed column is filled with a hydrogen scavenging agent; after the hydrogen scavenging agent adsorbs and absorbs the H2 generated by the cathode, the H2 content in the gas outlet is ≤3%, and the oxygen flow rate is 1-5 l / min; The hydrogen scavenger is composed of polyvinyl alcohol hydrogel, potassium graphite intercalation compound, and COF material in a mass ratio of 1-5:1:1; the potassium graphite intercalation compound is KC8 powder; the COF material is COF-1; and / or The hydrogen scavenger is prepared by adding KC8 powder to 5 wt% PTFE emulsion, rolling it into 0.5 mm spheres, and then drying the spheres at 80 °C for 2 h to obtain microspheres with a surface hydrophobic angle of 120-125°. The microspheres were dispersed in mesitylene, and Tp and Pa-1 monomers were added. The mixture was reacted at 120 °C for 12 h to obtain COF@KC8 particles with a shell thickness of 15 µm and a pore size of 1.0 nm. The COF@KC8 particles were immersed in a mixed solution of 3% PVA aqueous solution and 5 wt% glycerol for 10 s, then frozen at -40 ℃ for 30 min, and then vacuum sublimated and dried at 60°C for 6 h to obtain a hydrogen scavenger with a skin thickness of 5-10 µm.

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