Double-ion-channel synergetic enhanced conduction anion exchange membrane for hydrogen production by alkaline electrolysis of water and preparation method of double-ion-channel synergetic enhanced conduction anion exchange membrane

Abstract

The invention relates to the technical field of anion exchange membranes, in particular to a dual-ion-channel synergistic enhanced conduction anion exchange membrane for alkaline water electrolysis hydrogen production and a preparation method of the dual-ion-channel synergistic enhanced conduction anion exchange membrane for alkaline water electrolysis hydrogen production, and the dual-ion-channel synergistic enhanced conduction anion exchange membrane for alkaline water electrolysis hydrogen production is prepared by blending and crosslinking quaternized polyether-ether-ketone and carboxylated polyether sulfone, the carboxylated polyethersulfone provides a cation channel to form a double-ion synergistic conduction structure; the preparation process of the anion exchange membrane comprises the steps of quaternized polyether-ether-ketone synthesis, carboxylated polyether sulfone synthesis, membrane casting solution preparation, tape casting drying, crosslinking treatment and alkali liquor ion exchange. By constructing a double-ion channel structure, the synergistic conduction of anions and cations is realized, and the total ion conduction efficiency of the membrane is remarkably improved. The two polymer components form a continuously interlaced channel network, so that the defect that the conduction path of the traditional single ion channel membrane is isolated is avoided.

Description

Technical Field

[0001] This invention relates to the field of anion exchange membrane technology, specifically to a dual-ion-channel synergistic enhanced conduction anion exchange membrane for alkaline water electrolysis to produce hydrogen and its preparation method. Background Technology

[0002] Driven by energy transition and the "dual carbon" goal, alkaline water electrolysis hydrogen production technology has become an important direction for green hydrogen production due to its advantages such as readily available raw materials and low cost. As the core component of alkaline water electrolysis hydrogen production devices, the anion exchange membrane's ion conduction efficiency, alkali resistance, and stability directly determine the hydrogen production performance and equipment lifespan.

[0003] Traditional anion exchange membranes often employ a single-ion-channel design, focusing solely on enhancing anion conductivity while neglecting the synergistic effects in ion transport. Single-anion-channel membranes frequently suffer from isolated channel structures and discontinuous ion transport paths, resulting in low overall conductivity. Furthermore, in long-term high-temperature, concentrated alkaline environments, the polymer backbone is susceptible to alkali corrosion, leading to chemical structural degradation and a rapid decline in ion conductivity and mechanical strength, making it difficult to meet the demands of stable hydrogen production over extended periods.

[0004] Some improved membrane materials have attempted to optimize performance through blending modification, but due to the lack of an effective dual-ion synergistic conduction network, or poor compatibility of the blended components leading to phase separation and the inability to form continuous ion channels, they not only fail to improve conduction efficiency but may also further reduce the membrane's alkali resistance and stability due to structural defects. Furthermore, existing membrane materials often exhibit high ohmic polarization and high cell voltage in alkaline water electrolysis for hydrogen production, limiting hydrogen yield and Faraday efficiency and hindering the large-scale application of alkaline water electrolysis for hydrogen production. Therefore, developing an anion exchange membrane with high-efficiency dual-ion synergistic conduction capability, excellent alkali resistance, and long-term stability is crucial to overcoming current technological bottlenecks. Summary of the Invention

[0005] The primary objective of this invention is to provide a dual-ion-channel synergistically enhanced anion exchange membrane for alkaline water electrolysis to produce hydrogen, and its preparation method.

[0006] A further objective of this invention is to provide a dual-ion-channel synergistic enhanced conduction anion exchange membrane for alkaline water electrolysis to produce hydrogen. This membrane is prepared by crosslinking quaternized polyetheretherketone (PEEK) and carboxylated polyethersulfone (PES). The quaternized PEEK provides anion channels, and the carboxylated PES provides cation channels, forming a dual-ion synergistic conduction structure. The preparation process of the anion exchange membrane includes the synthesis of quaternized PEEK, the synthesis of carboxylated PES, the preparation of casting solution, casting and drying, crosslinking treatment, and alkaline ion exchange steps.

[0007] Preferably, the degree of quaternization of the quaternized polyether ether ketone is 60%-80%, and it is obtained by polyether ether ketone through chloromethylation, amination, dialysis purification and drying; the chloromethylation reaction uses chloromethyl methyl ether as the chloromethylating agent and anhydrous aluminum trichloride as the catalyst, the reaction temperature is 60°C and the reaction time is 4h-6h; the amination reaction uses 25% trimethylamine aqueous solution, the reaction temperature is 40°C and the reaction time is 6h.

[0008] Preferably, the carboxyl content of the carboxylated polyethersulfone is 5 mmol / g, and it is prepared by reacting polyethersulfone with phthalic anhydride in concentrated sulfuric acid at a reaction temperature of 80°C for 5 hours. After the reaction, the polyethersulfone is precipitated with ice water, washed until neutral, and dried.

[0009] Preferably, the mass ratio of the quaternized polyether ether ketone to the carboxylated polyether sulfone is 7:3-8:2; the casting solution uses N,N-dimethylacetamide as a solvent, the total mass fraction of the quaternized polyether ether ketone and the carboxylated polyether sulfone in the casting solution is 15%, the casting solution preparation temperature is 50°C, and the stirring time is 6 hours.

[0010] Preferably, the casting drying step is as follows: the casting solution after standing and degassing for 2 hours is uniformly cast onto a clean glass plate, dried at 60°C for 4 hours, and then transferred to an 80°C vacuum drying oven for 6 hours; the crosslinking treatment uses a 1 mol / L epichlorohydrin solution and crosslinks at 50°C for 2 hours.

[0011] Preferably, the alkaline ion exchange step is as follows: the cross-linked membrane is immersed in a 1 mol / L potassium hydroxide solution for 24 hours, and then rinsed with deionized water to remove residual alkaline solution from the surface.

[0012] Preferably, the mixture also includes hydroxylated titanium dioxide nanoparticles, which are added to the casting solution at 1 wt% of the total mass of quaternized polyether ether ketone and carboxylated polyether sulfone, and then participate in the casting and drying step after ultrasonic dispersion for 30 min; the hydroxylated titanium dioxide is prepared by reacting titanium dioxide in sulfuric acid solution, washing it, and then reacting it with ammonia water, and then drying it after the reaction.

[0013] Preferably, the preparation process of the hydroxylated titanium dioxide is as follows: titanium dioxide powder is added to a 0.5 mol / L sulfuric acid solution, stirred at 80°C for 4 hours, washed until neutral, mixed with 25% ammonia water, stirred at 60°C for 3 hours, and finally vacuum dried at 80°C for 12 hours.

[0014] A method for preparing a dual-ion-channel synergistically enhanced anion exchange membrane for alkaline water electrolysis to produce hydrogen includes the following steps:

[0015] (1) Synthesis of quaternized polyether ether ketone: Polyether ether ketone powder was added to anhydrous ethanol and swollen at 30°C for 2 hours. Chloromethyl methyl ether and anhydrous aluminum trichloride were added and stirred at 60°C for 4-6 hours to obtain chloromethylated polyether ether ketone. The chloromethylated polyether ether ketone was soaked in 25% trimethylamine aqueous solution and amination was carried out at 40°C for 6 hours. After dialysis with deionized water for 3 days, it was vacuum dried at 80°C for 12 hours to obtain quaternized polyether ether ketone.

[0016] (2) Synthesis of carboxylated polyethersulfone: Polyethersulfone was added to concentrated sulfuric acid and phthalic anhydride, stirred at 80°C for 5 hours, the reaction solution was poured into ice water to precipitate, washed with deionized water until the filtrate was neutral, and dried under vacuum at 80°C for 12 hours to obtain carboxylated polyethersulfone.

[0017] (3) Preparation of casting solution: Quaternized polyether ether ketone and carboxylated polyether sulfone are added to N,N-dimethylacetamide at a mass ratio of 7:3-8:2 and stirred at 50°C for 6 hours to form a casting solution with a mass fraction of 15%.

[0018] (4) Casting and drying: Let the casting solution stand to degas for 2 hours, cast it evenly on a clean glass plate, dry it at 60°C for 4 hours, and then transfer it to an 80°C vacuum drying oven for 6 hours.

[0019] (5) Crosslinking treatment: The dried membrane was immersed in a 1 mol / L epichlorohydrin solution and crosslinked at 50°C for 2 h;

[0020] (6) Alkaline ion exchange: The cross-linked membrane is immersed in 1 mol / L potassium hydroxide solution for 24 h, and the surface residual alkali is rinsed with deionized water to obtain an anion exchange membrane.

[0021] Preferably, in step (3), when preparing the casting solution, hydroxylated titanium dioxide nanoparticles are added at 1 wt% of the total mass of quaternized polyether ether ketone and carboxylated polyether sulfone, ultrasonically dispersed for 30 min, and then allowed to stand to remove bubbles; the hydroxylated titanium dioxide nanoparticles are obtained by reacting titanium dioxide in sulfuric acid solution, washing, reacting with ammonia water, and then drying.

[0022] Compared with the prior art, the present invention has the following significant advantages:

[0023] 1. This invention constructs a dual-ion channel structure to achieve synergistic conduction of anions and cations, significantly improving the overall ion conduction efficiency of the membrane. The two polymer components form a continuous, interwoven channel network, avoiding the isolated conduction paths of traditional single-ion channel membranes, effectively reducing ion transport resistance, providing a highly efficient ion transport channel for the alkaline water electrolysis hydrogen production process, and helping to reduce battery ohmic polarization and lower cell voltage.

[0024] 2. The dual-ion channel membrane prepared by this invention exhibits excellent alkali resistance. The dense dual-channel cross-linked network structure effectively inhibits the erosion of the polymer backbone by alkali solutions. Simultaneously, the introduction of hydroxylated nanoparticles can form multiple hydrogen bonds with functional groups in the polymer, further reducing the alkali permeation rate and significantly improving the membrane's conductivity and tensile strength retention under long-term high-temperature, concentrated alkali conditions. This solves the problem of performance degradation in traditional membrane materials over long-term operation and extends the membrane's service life.

[0025] 3. When the dual-ion-channel membrane of this invention is applied to alkaline water electrolysis for hydrogen production, it can significantly improve hydrogen production performance. The efficient ion-coordinated conduction reduces the cell internal resistance, resulting in a significantly lower cell voltage compared to traditional single-channel membranes. Simultaneously, its excellent structural stability and alkali resistance ensure stable performance during long-term operation, achieving higher hydrogen yield and Faraday efficiency, thus meeting the needs for efficient, stable, and large-scale application of alkaline water electrolysis for hydrogen production.

[0026] 4. The preparation method of the present invention is simple and highly controllable. By adjusting the proportion of polymer components, optimizing the content of functional groups, and introducing nanoparticles, the channel structure and performance of the membrane can be flexibly controlled to meet the needs of alkaline water electrolysis for hydrogen production under different working conditions. Moreover, the raw materials are readily available, the preparation process is environmentally friendly, and it is convenient for industrial production and promotion. Attached Figure Description

[0027] Figure 1 A schematic diagram of the microstructure of the anion exchange membrane with synergistic enhancement of conduction by dual ion channels in this invention. Detailed Implementation

[0028] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1: Preparation of a basic dual-ion channel membrane (M1)

[0030] (1) Synthesis of Quaternized Polyetheretherketone

[0031] 10g of polyetheretherketone powder was added to 50mL of anhydrous ethanol and swollen at 30℃ for 2h. Then, 15mL of chloromethyl methyl ether and 5g of anhydrous aluminum trichloride were added and stirred at 60℃ for 4h to obtain chloromethylated polyetheretherketone. The chloromethylated polyetheretherketone was soaked in 25% trimethylamine aqueous solution and amination was carried out at 40℃ for 6h. After dialysis with deionized water for 3 days to remove unreacted impurities, it was vacuum dried at 80℃ for 12h. The content of quaternary ammonium groups was determined by acid-base titration, and QPEEK with a quaternization degree of 60% was finally obtained.

[0032] (2) Synthesis of carboxylated polyethersulfone (C-PES)

[0033] Take 10g of polyethersulfone, add 40mL of concentrated sulfuric acid and 8g of phthalic anhydride, and stir at 80℃ for 5h. Slowly pour the reaction solution into ice water to precipitate, wash repeatedly with deionized water until the filtrate is neutral, and vacuum dry at 80℃ for 12h. Determine the carboxyl content by potentiometric titration, and finally obtain C-PES with a carboxyl content of 5mmol / g.

[0034] (3) Preparation of dual-ion channel membranes

[0035] QPEEK and C-PES were added to N,N-dimethylacetamide at a mass ratio of 8:2 and stirred at 50°C for 6 hours to form a casting solution with a mass fraction of 15%. After standing for 2 hours to remove bubbles, the casting solution was uniformly cast onto a clean glass plate and dried at 60°C for 4 hours to remove most of the solvent. Then, it was transferred to a vacuum drying oven at 80°C for 6 hours. The dried membrane was then immersed in a 1 mol / L epichlorohydrin solution and crosslinked at 50°C for 2 hours. Finally, the crosslinked membrane was immersed in a 1 mol / L KOH solution for 24 hours for ion exchange. After removal, the surface residual alkali was rinsed with deionized water to obtain the basic dual-ion channel membrane M1.

[0036] The chemical structural formula of quaternized polyether ether ketone is shown in Formula 1 below:

[0037]

[0038] The polyethersulfone (PES) backbone introduces carboxyl groups onto the benzene ring through a reaction with phthalic anhydride in concentrated sulfuric acid. The chemical structure of its repeating unit is shown in Formula 2 below:

[0039] -O-Ph-C6H4-COOH-Ph-O-Ph-C6H4-SO2-Ph -

[0040] Formula 2

[0041] Carboxyl groups can provide sites for the conduction of cations such as potassium ions through dissociation and other processes, making them a key structure for cation channels.

[0042] After quaternized polyether ether ketone and carboxylated polyether sulfone are crosslinked with epichlorohydrin, a crosslinked network segment containing ether bonds is formed (partial schematic diagram) as shown in Equation 3 below:

[0043] -O-Ph-CH2-N + (CH3)3-O-CH2-CH(OH)-CH2-O - Ph-COOH-

[0044] Formula 3

[0045] Example 2: Preparation of a cation channel ratio optimized membrane (M2)

[0046] (1) Based on the formulation and steps of Example 1, only the mass ratio of QPEEK to C-PES was adjusted to 7:3. All other synthesis parameters, including the degree of quaternization of QPEEK, the carboxyl content of C-PES, the casting temperature, the crosslinking time, and the alkali treatment conditions, were completely consistent with those of Example 1, and a dual-ion channel membrane M2 with an increased proportion of cation channels was prepared. This example explores the correlation between the dual-channel ratio and the synergistic ion conduction efficiency by changing the proportion of cation channel components.

[0047] Example 3: Preparation of anion channel density-enhanced membrane (M3)

[0048] Synthesis of QPEEK with high quaternization

[0049] (1) Based on the QPEEK synthesis steps of Example 1, the chloromethylation reaction time was extended to 6h, while the swelling temperature, amination time, dialysis conditions and other parameters remained unchanged; the acid-base titration method was used to verify the increase in quaternary ammonium group content, and finally QPEEK with quaternization degree of 80% was obtained.

[0050] (2) Preparation of dual-ion channel membranes

[0051] Following the QPEEK to C-PES 8:2 mass ratio in Example 1, and using the aforementioned high-quaternization degree QPEEK, the remaining casting, crosslinking, and alkali treatment steps were completely consistent with Example 1, resulting in the preparation of a dual-ion channel membrane M3 with enhanced anion channel density. This example addresses the insufficient anion conduction efficiency in Example 1 by increasing the quaternization degree of QPEEK to enhance OH- conduction.

[0052] Example 4: Preparation of a nanoparticle synergistic stabilizing film (M4)

[0053] (1) Preparation of hydroxylated TiO2 (TiO2-OH)

[0054] 2g of titanium dioxide powder was added to 50mL of 0.5mol / L sulfuric acid solution and stirred at 80℃ for 4h. The solution was washed with deionized water until the filtrate was neutral, and then mixed with 10mL of 25% ammonia solution and stirred at 60℃ for 3h. The solution was then dried under vacuum at 80℃ for 12h. The presence of hydroxyl functional groups was verified by X-ray photoelectron spectroscopy, and hydroxylated titanium dioxide was finally obtained.

[0055] (2) Preparation of dual-ion channel membranes

[0056] Based on the casting solution formulation of Example 3, 1 wt% hydroxylated TiO2 was added according to the total mass of QPEEK and C-PES, and ultrasonically dispersed for 30 min to ensure uniform distribution of nanoparticles. The remaining casting, crosslinking, and alkali treatment steps were completely consistent with those of Example 1, resulting in the preparation of a nanoparticle-synergistically stable dual-ion channel membrane M4. This example, building upon the high anion conductivity of Example 3, further enhances channel stability and alkali resistance by forming a hydrogen bond network between hydroxylated nanoparticles and the polymer.

[0057] Comparative Example 1: Single Anion Channel Membrane (D1)

[0058] (1) Only QPEEK single-channel membranes were prepared. The QPEEK synthesis steps were completely consistent with those in Example 1, and the degree of quaternization was 60%. Without adding C-PES, QPEEK was directly dissolved in N,N-dimethylacetamide to form a 15% mass fraction casting solution. The subsequent casting, crosslinking, and alkali treatment steps were the same as in Example 1, resulting in a single anion channel membrane D1. This comparative example was used to verify the necessity of cation channels for synergistic ion conduction.

[0059] Comparative Example 2: Single-cation channel membrane (D2)

[0060] (2) Only C-PES single-channel membranes were prepared. The C-PES synthesis steps were exactly the same as in Example 1, and the carboxyl content was 5 mmol / g. Without adding QPEEK, C-PES was directly dissolved in N,N-dimethylacetamide to form a 15% (w / w) casting solution. Subsequent casting, crosslinking, and alkali treatment steps were the same as in Example 1, yielding a single-cation channel membrane D2. This comparative example was used to verify the crucial role of anion channels in hydrogen production performance.

[0061] Comparative Example 3: Cation Channel-Free Blend Membrane (D3)

[0062] (3) Pure polyethersulfone was used to replace C-PES in Example 1. A blend membrane was prepared by using QPEEK and pure polyethersulfone at a mass ratio of 8:2. The remaining synthesis steps, including QPEEK synthesis, casting, crosslinking, and alkali treatment, were completely consistent with those in Example 1, resulting in a blend membrane D3 without cation channels. This comparative example was used to verify the core significance of the carboxyl functional group in C-PES for constructing cation channels.

[0063] Performance testing and results analysis

[0064] Ion conductivity testing (AC impedance method)

[0065] Test conditions: The membrane sample was immersed in a 1 mol / L KOH solution for 24 hours at a constant temperature of 25℃. The AC impedance was measured using an electrochemical workstation within a frequency range of 10 Hz. -2 -10 5 Hz, calculate OH- conductivity and K + Conductivity.

[0066] Test results:

[0067]

[0068] Results analysis: The overall conductivity of the dual-ion-channel membrane (M1-M4) was significantly higher than that of the single-channel membrane (D1-D2) and the cation-channel-free blend membrane (D3). Among them, M2 showed a higher Kc due to the increased proportion of cation channels. + The conductivity was 40.6% higher than that of M1; due to the enhanced anion channel density, the OH- conductivity of M3 was 19.9% ​​higher than that of M1; and due to the hydrogen bond network constructed by hydroxylated TiO2, the total conductivity of M4 was further improved by 13.1% compared with M3, which promoted dual-channel ion transport, thus verifying the advantages of dual-ion channel synergistic conduction.

[0069] Alkali resistance test

[0070] Test conditions: The membrane sample was immersed in a 60℃, 6mol / L KOH solution for 1000h. It was taken out periodically to measure the ionic conductivity and tensile strength. The tensile rate was set to 5mm / min. The performance retention rate was calculated.

[0071] Test results:

[0072] Sample number Conductivity retention rate (%) Tensile strength retention rate (%) M1 72 68 M2 69 65 M3 78 75 M4 85 82 D1 65 60 D2 58 52 D3 62 58

[0073] Results Analysis: The alkali resistance of dual-channel membranes is generally better than that of single-channel membranes because the dual-channel cross-linked network is denser and can inhibit the erosion of the polymer backbone by alkali solutions. In M4, hydroxylated TiO2 forms multiple hydrogen bonds with the quaternary ammonium groups of QPEEK and the carboxyl groups of C-PES, which significantly reduces the alkali permeation rate. The conductivity retention rate and tensile strength retention rate are improved by 9.0% and 9.3% respectively compared with M3, solving the problem of membrane performance degradation under long-term alkaline environment.

[0074] Performance testing of hydrogen production via alkaline water electrolysis (single-cell system)

[0075] Test conditions: The membrane sample was used as the electrolyte membrane; the anode used NiFe2O4 catalyst; the cathode used Pt / C catalyst; the electrolyte was 6 mol / L KOH solution; and the current density was 1 A / cm². 2 The cell pressure, hydrogen yield (collected by water displacement method), and Faraday efficiency were measured.

[0076] Test results:

[0077] Sample number Slot pressure (V) Hydrogen yield (%) Faraday efficiency (%) M1 1.98 95.2 94.5 M2 2.02 94.8 93.8 M3 1.90 97.0 96.2 M4 1.85 98.5 97.8 D1 2.10 92.0 90.0 D2 2.35 88.5 86.3 D3 2.15 91.5 89.7

[0078] Results Analysis: The dual-ion-channel membrane can reduce ohmic polarization of the battery through synergistic conduction, and the cell voltage is significantly lower than that of the single-channel membrane. Due to its high ion conductivity and excellent alkali resistance, M4 has a cell voltage that is 0.05V lower than that of M3, and its hydrogen yield and Faraday efficiency are increased by 1.5% and 1.6%, respectively. Moreover, its performance showed no significant degradation after 1000 hours of long-term operation, meeting the requirements for high efficiency and stability in alkaline water electrolysis for hydrogen production.

[0079] Microstructure characterization

[0080] Characterization conditions: The cross-sectional morphology of the film sample was observed using field emission scanning electron microscopy with an accelerating voltage of 10 kV. The sample was sputter-coated with gold to improve conductivity.

[0081] Characterization results:

[0082]

[0083]

[0084] Results analysis: The uniform phase distribution of dual-ion channel membranes is the structural basis for achieving synergistic conduction. Hydroxylated TiO2 in M4 can act as a channel "bridge" to further optimize the continuity of ion transport paths. However, single-channel membranes or membranes without cation channels cannot form an efficient conduction network due to structural defects.

[0085] This invention focuses on the prepared dual-ion-channel synergistic enhanced conduction anion exchange membrane, conducting tests from three core dimensions: ion conduction efficiency, alkali resistance, and alkaline water electrolysis hydrogen production performance. Combined with microstructure characterization, the performance advantages of the membrane material are comprehensively verified, as detailed below:

[0086] (1) Ion conduction efficiency test

[0087] The ion conductivity of different membrane samples was measured by AC impedance spectroscopy. The results showed that the total conductivity of dual-ion channel membranes (including basic dual-ion channel membranes, cation channel ratio optimized membranes, anion channel density enhanced membranes, and nanoparticle synergistic stabilization membranes) was significantly better than that of single anion channel membranes, single cation channel membranes, and cation-free blend membranes.

[0088] In the dual-ion channel membrane series, adjusting the ratio of cation channel components can enhance potassium ion conductivity; extending the chloromethylation reaction time to increase the degree of quaternization can enhance anion conductivity; and introducing hydroxylated nanoparticles to construct a hydrogen bond network can further optimize the dual-channel ion transport effect, fully demonstrating the advantages of synergistic conduction of dual ion channels.

[0089] (2) Alkali resistance test

[0090] Membrane samples were immersed in a high-temperature, concentrated alkali environment for an extended period, and the retention of ion conductivity and tensile strength was periodically monitored. Test results showed that the alkali resistance of dual-channel membranes was generally superior to that of single-channel membranes. This is attributed to the denser dual-channel cross-linked network, which effectively inhibits the erosion of the polymer backbone by the alkali solution.

[0091] Among them, the dual-ion channel membrane with added hydroxylated nanoparticles significantly reduces the alkaline solution permeation rate due to the formation of multiple hydrogen bonds between the nanoparticles and the functional groups in the polymer. It also exhibits better performance in terms of conductivity retention and tensile strength retention, effectively solving the problem of membrane performance degradation under long-term alkaline conditions.

[0092] (3) Alkaline water electrolysis hydrogen production performance test

[0093] Single-cell systems were constructed using various membrane samples as electrolyte separators, and the cell voltage, hydrogen yield, and Faraday efficiency were measured. The results show that the dual-ion-channel membrane can reduce ohmic polarization of the cell through synergistic conduction, and the cell voltage is significantly lower than that of the single-channel membrane and the blend membrane without cation channels.

[0094] The dual-ion channel membrane with added hydroxylated nanoparticles, with its high ion conductivity and excellent alkali resistance, not only has a lower cell voltage but also achieves higher hydrogen yield and Faraday efficiency. Moreover, its performance does not significantly degrade after long-term operation, meeting the requirements of alkaline water electrolysis for high efficiency and stability of membrane materials.

[0095] (4) Microstructure characterization

[0096] Field emission scanning electron microscopy was used to observe the cross-sectional morphology of the membrane sample. It was found that the dual-ion channel membrane exhibited a uniform phase distribution with no obvious phase separation, and the two polymer components could form a continuous interwoven channel structure.

[0097] The dual-ion channel membrane with added hydroxylated nanoparticles exhibits uniform nanoparticle dispersion without aggregation, tight interfacial bonding, and superior channel continuity. In contrast, single-channel membranes or blended membranes without cation channels exhibit significant structural defects. For example, single-anion channel membranes contain only isolated anion channels without a continuous network, while single-cation channel membranes suffer from component aggregation and channel breakage, failing to form an efficient conduction network. This microstructural improvement confirms the rationale for the dual-ion channel design.

[0098] The accompanying diagram illustrates a network structure comprising a polymer backbone (e.g., "SEBSbackbone," analogous to the backbone structure formed by quaternized polyether ether ketone and other polymers in this invention), alkyl spacer chains, quaternary ammonium cations, and water. This type of structure reflects the microscopic environment in which ions are conducted within channels constructed from polymer components, aided by the synergistic effects of quaternary ammonium cations and water. This aligns with the core technical essence of this invention's "dual-ion-channel synergistic enhanced conduction" anion exchange membrane (forming ion channels through polymers and achieving efficient ion conduction using functional groups and water), and can help elucidate the structure of ion channels within the membrane and the microscopic mechanism of ion conduction.

[0099] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only to the claims and their full scope and equivalents.

Claims

1. A dual-ion-channel synergistic enhanced conduction anion exchange membrane for alkaline water electrolysis to produce hydrogen, characterized in that, The anion exchange membrane is made by crosslinking quaternized polyether ether ketone (PEEK) and carboxylated polyether sulfone (PES), wherein the quaternized PEEK provides anion channels and the carboxylated PES provides cation channels, forming a dual-ion synergistic conduction structure. The preparation process of the anion exchange membrane includes the synthesis of quaternized PEEK, the synthesis of carboxylated PES, the preparation of casting solution, casting and drying, crosslinking treatment, and alkaline ion exchange steps.

2. The anion exchange membrane according to claim 1, characterized in that, The quaternized polyether ether ketone has a degree of quaternization of 60%-80%, and is obtained by polyether ether ketone through chloromethylation, amination, dialysis purification and drying. The chloromethylation reaction uses chloromethyl methyl ether as the chloromethylating agent and anhydrous aluminum trichloride as the catalyst, the reaction temperature is 60℃ and the reaction time is 4h-6h. The amination reaction uses 25% trimethylamine aqueous solution, the reaction temperature is 40℃ and the reaction time is 6h.

3. The anion exchange membrane according to claim 1, characterized in that, The carboxylated polyethersulfone has a carboxyl content of 5 mmol / g and is prepared by reacting polyethersulfone with phthalic anhydride in concentrated sulfuric acid at a reaction temperature of 80°C for 5 hours. After the reaction, the polyethersulfone is precipitated in ice water, washed until neutral, and then dried.

4. The anion exchange membrane according to claim 1, characterized in that, The mass ratio of the quaternized polyether ether ketone to the carboxylated polyether sulfone is 7:3-8:2; the casting solution uses N,N-dimethylacetamide as a solvent, the total mass fraction of the quaternized polyether ether ketone and the carboxylated polyether sulfone in the casting solution is 15%, the casting solution preparation temperature is 50℃, and the stirring time is 6h.

5. The anion exchange membrane according to claim 1, characterized in that, The casting drying step is as follows: the casting liquid, after standing and degassing for 2 hours, is uniformly cast onto a clean glass plate, dried at 60°C for 4 hours, and then transferred to an 80°C vacuum drying oven for 6 hours. The crosslinking treatment was performed using a 1 mol / L epichlorohydrin solution at 50°C for 2 hours.

6. The anion exchange membrane according to claim 1, characterized in that, The alkaline ion exchange step is as follows: the cross-linked membrane is immersed in a 1 mol / L potassium hydroxide solution for 24 hours, and then rinsed with deionized water to remove residual alkaline solution from the surface.

7. The anion exchange membrane according to claim 1, characterized in that, It also includes hydroxylated titanium dioxide nanoparticles, which are added to the casting solution at 1 wt% of the total mass of quaternized polyether ether ketone and carboxylated polyether sulfone, and then participate in the casting and drying step after ultrasonic dispersion for 30 min; the hydroxylated titanium dioxide is prepared by reacting titanium dioxide in sulfuric acid solution, washing it, and then reacting it with ammonia water, and then drying it after the reaction.

8. The anion exchange membrane according to claim 7, characterized in that, The preparation process of the hydroxylated titanium dioxide is as follows: titanium dioxide powder is added to a 0.5 mol / L sulfuric acid solution, stirred at 80°C for 4 hours, washed until neutral, mixed with 25% ammonia water, stirred at 60°C for 3 hours, and finally vacuum dried at 80°C for 12 hours.

9. A method for preparing a dual-ion-channel synergistically enhanced anion exchange membrane for alkaline water electrolysis to produce hydrogen, characterized in that, Includes the following steps: (1) Synthesis of quaternized polyether ether ketone: Polyether ether ketone powder was added to anhydrous ethanol and swollen at 30°C for 2 hours. Chloromethyl methyl ether and anhydrous aluminum trichloride were added and stirred at 60°C for 4-6 hours to obtain chloromethylated polyether ether ketone. The chloromethylated polyether ether ketone was soaked in 25% trimethylamine aqueous solution and amination was carried out at 40°C for 6 hours. After dialysis with deionized water for 3 days, it was vacuum dried at 80°C for 12 hours to obtain quaternized polyether ether ketone. (2) Synthesis of carboxylated polyethersulfone: Polyethersulfone was added to concentrated sulfuric acid and phthalic anhydride, stirred at 80°C for 5 hours, the reaction solution was poured into ice water to precipitate, washed with deionized water until the filtrate was neutral, and dried under vacuum at 80°C for 12 hours to obtain carboxylated polyethersulfone. (3) Preparation of casting solution: Quaternized polyether ether ketone and carboxylated polyether sulfone are added to N,N-dimethylacetamide at a mass ratio of 7:3-8:2 and stirred at 50°C for 6 hours to form a casting solution with a mass fraction of 15%. (4) Casting and drying: Let the casting solution stand to degas for 2 hours, cast it evenly on a clean glass plate, dry it at 60°C for 4 hours, and then transfer it to an 80°C vacuum drying oven for 6 hours. (5) Crosslinking treatment: The dried membrane was immersed in a 1 mol / L epichlorohydrin solution and crosslinked at 50°C for 2 h; (6) Alkaline ion exchange: The cross-linked membrane is immersed in 1 mol / L potassium hydroxide solution for 24 h, and the surface residual alkali is rinsed with deionized water to obtain an anion exchange membrane.

10. The preparation method according to claim 9, characterized in that, In step (3), when preparing the casting solution, hydroxylated titanium dioxide nanoparticles are added at 1 wt% of the total mass of quaternized polyether ether ketone and carboxylated polyether sulfone, ultrasonically dispersed for 30 min, and then allowed to stand to remove bubbles. The hydroxylated titanium dioxide nanoparticles are obtained by reacting titanium dioxide in sulfuric acid solution, washing, reacting with ammonia water, and then drying.

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