Proton exchange membrane prepared from polyacid doped sulfonated polyaryletherketone sulfone

Abstract

The invention relates to preparation and application of a proton exchange membrane which is a core component of a hydrogen-oxygen fuel cell. The invention relates to a polyacid compound doped SPAEKS proton exchange membrane, which is an inorganic-organic hybrid composite material, and belongs to the field of polymer chemistry and inorganic chemistry. The polyacid compound can be uniformly dispersed and stable in a polymer matrix as an inorganic filler, can accommodate more water molecules for proton conduction, and solves the problem of low proton conductivity of the existing original SPAEKS. The proton conductivity of the inorganic-organic hybrid composite proton exchange membrane at 80 DEG C is 0.03-0.062 S cm <-1 >, the inorganic-organic hybrid composite proton exchange membrane has good thermal stability, and the thickness of the membrane is 0.025-0.03 mm.

Description

TECHNICAL FIELD

[0001] The present application relates to a kind of core components of hydrogen-oxygen fuel cell-proton exchange membrane and its application.Preparation of a kind of proton exchange membrane of polyacid compound doped sulfonated polyaryl ether ketone sulfone (SPAEKS), it is by inorganic-organic hybrid composite material. BACKGROUND

[0002] As the core component of PEMFCs, the quality of proton exchange membrane will directly affect the service life of the battery.Although the commercial Nafion membrane has excellent conductivity, its high methanol permeability and poor chemical stability may limit its application.Therefore, it is urgent to develop new proton exchange membranes.

[0003] SPAEKS has become an ideal alternative material due to its excellent proton conduction performance, which is due to the channels provided by a large number of sulfonic acid groups for proton transport.In many polymer membrane materials, SPAEKS is of great concern due to its low cost, low methanol permeability and high thermal stability.Although high sulfonation degree can improve proton conductivity, too high sulfonation degree will lead to increased molecular volume and swelling rate.In recent years, significant progress has been made in the research on monomer synthesis strategy and doping method of SPAEKS.

[0004] Some studies have shown that polyoxometalate can be used as a good filler for proton exchange membrane (PEM), and is an ideal candidate material for providing sufficient proton transfer sites to follow the Grothuss mechanism.In addition, its unique porous structure allows discrete water molecules to freely enter and exit, promoting proton transport through the carrier mechanism.In addition, its porous structure can accommodate more water molecules, which is beneficial to improve the proton conduction performance of the hybrid membrane.

[0005] We choose polyoxometalate Mo cluster inorganic material Mo 74 The reason for choosing polyoxometalate Mo cluster inorganic material Mo

[0006] The sulfonated polyaryl ether ketone sulfone and polyoxometalate composite proton exchange membrane for fuel cells and its preparation method have high proton conductivity and good thermal stability by doping different proportions of fillers, and have good dimensional stability and mechanical properties.The proton exchange membrane has a proton conductivity of 0.03 S / cm to 0.062 S / cm at 80°C.

[0007] Although the existing proton exchange membrane has certain improvement in some aspects compared with other membrane technologies, it still fails to meet the long-term use requirements in other performances such as proton conductivity, dimensional stability, durability, mechanical strength and the like. Therefore, it is urgent to develop a relatively optimal proton exchange membrane for fuel cells. SUMMARY

[0008] In view of the existing situation, the present application provides a proton exchange membrane and a preparation method and application thereof, which at least solve one of the above technical problems.

[0009] The technical scheme provided by the present application is: a low-temperature proton exchange membrane, which is obtained by hybridizing sulfonated polyaryletherketone sulfone based on polyoxometalate.

[0010] The person skilled in the art can select the optimal film-forming solution according to the ratio of the polyacid and the main chain polymer thereof, and the selection criteria are determined according to the improvement of the performance of the polymer film, such as the improvement of the proton conductivity, the improvement of the mechanical performance or the improvement of the dimensional stability of the film.

[0011] Further, the mass ratio of the sulfonated polyaryletherketone sulfone to the hybrid filler is 2:0.01, 2:0.05 or 2:0.15.

[0012] Further, the polyacid is polyoxometalate.

[0013] Further, the structural formula of the polyoxometalate is (C2H8N) 14 (NH4)4H 14 [Mo V 48 Mo VI 26 O 202 (OH) 12 (SO4)6]·46H2O (abbreviated as {Mo 74})

[0014] Further, the polymer matrix is polyaryletherketone sulfone with a sulfonation degree of 30%.

[0015] The technical scheme provided by the present application is: a preparation method of the above-mentioned proton exchange membrane, which comprises the following steps: 1. dissolving the sulfonated polyaryletherketone sulfone and the hybrid filler in a solvent to obtain a film-forming solution; and 2. drying the film-forming solution to form the proton exchange membrane.

[0016] Further, the preparation method of the hybrid filler is: uniformly mixing the polyacid and the solvent.

[0017] Further, the solvent NMP; step 1 is specifically adding the sulfonated polyaryletherketone sulfone into the solvent, stirring at room temperature for at least 12 hours, then adding the hybrid filler to obtain a mixture, and ultrasonic treating the mixture for at least 24 hours to obtain the film-forming solution.

[0018] The second technical solution provided in the application is application of the proton exchange membrane in a hydrogen-oxygen fuel cell.

[0019] The application prepares a proton-conducting inorganic filler based on polyacid, which is used for hybridization with sulfonated polyaryletherketone sulfone (SPAEKS) to solve the problem of high proton conductivity.

[0020] The application forms a favorable chemical microenvironment for improving the proton conductivity of polyaryletherketone sulfone by introducing the inorganic filler polyoxometalate Mo 74 , thereby enhancing the proton conductivity of polyaryletherketone sulfone, and the inorganic filler is uniformly dispersed and stable in the polymer matrix. The filler can promote the continuous hydrogen bond network in the sulfonated polyaryletherketone sulfone (SPAEKS) to form a favorable chemical microenvironment for proton conduction. Compared with the conventional hybrid membrane, this unique hybridization gives changes in microstructure and functions, which helps to reduce the activation energy of the reaction and promote fast proton transfer. This functionalization method provides a multifunctional platform for developing hybrid membrane materials tailored for specific applications of proton exchange membrane systems.

[0021] Compared with the prior art, the application has the following advantages: (1) The synthesis process is simple, and the yield of the synthesized hybrid filler is as high as 85%. (2) The proton conductivity of the original membrane is effectively improved by using the non-water-soluble polyoxometalate. This strategy has wide applicability and can be popularized to other high-conductivity polyacids to enhance the proton conductivity of the proton exchange membrane. (3) Since the polyoxometalate filler and the sulfonated polyaryletherketone sulfone can both be dissolved in general organic solvents, the doping is carried out by physical mixing and stirring, which is convenient to operate and easy to realize. Finally, the composite inorganic-organic proton exchange membrane material with high proton conductivity and good thermal stability can be prepared by the solution casting method. BRIEF DESCRIPTION OF DRAWINGS The accompanying drawings, which are incorporated into and constitute a part of the specification, illustrate embodiments of the application and, together with the description, serve to explain the principles of the application. The drawings described below are some embodiments of the application, rather than all embodiments.

[0022] Figure 1 SEM image of a proton exchange membrane;

[0023] Figure 2TGA graph of the proton exchange membrane is thermal stability test;

[0024] Figure 3 Mechanical property graph of the proton exchange membrane;

[0025] Figure 4 Long-term oxidation stability graph of the proton exchange membrane;

[0026] Figure 5 Proton conductivity of the proton exchange membrane at different temperatures;

[0027] Figure 6 Hydrogen-oxygen fuel cell graph of the proton exchange membrane;

[0028] Figure 7 Swelling test of the proton exchange membrane;

[0029] Figure 8 ATR-FI-IR of the proton exchange membrane;

[0030] Figure 9 Water absorption test of the proton exchange membrane. Specific implementation method:

[0031] In order to make the purpose, technical scheme and advantages of the present application clearer, the technical scheme of the present application will be described clearly and completely below in combination with the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] In the description of the present application, unless otherwise explicitly specified and limited, the terms "connected", "connected", "fixed" should be understood broadly, for example, can be fixedly connected, or can be detachably connected, or integrated; can be mechanically connected, or electrically connected; can be directly connected, or indirectly connected through an intermediate medium, can be the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0033] In the present application, unless specifically defined and limited otherwise, the first feature "on" or "under" the second feature can include that the first and second features are in direct contact, or that the first and second features are not in direct contact but are in contact through another feature between them. Moreover, the first feature "on", "above" and "over" the second feature includes that the first feature is directly above and obliquely above the second feature, or only indicates that the first feature is higher in horizontal height than the second feature. The first feature "under", "below" and "underneath" the second feature includes that the first feature is directly below and obliquely below the second feature, or only indicates that the first feature is lower in horizontal height than the second feature.

[0034] In the description of the present embodiment, the terms "upper", "lower", "left", "right", and the like orientation or positional relationship are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of description and simplification of operation, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0035] Preparation method of SPAEKS (DS = 30%).

[0036] Take a three-necked flask and fill it with an appropriate amount of stirring paddle

[0037] Add bisphenol A, SDCDPS and 4,4-difluorobenzophenone each in several moles.

[0038] Under nitrogen protection, add 22 ml of tosylate and 18 ml of toluene to the flask.

[0039] Heat the mixture to 125°C and keep for 5 hours to remove moisture, and then heat to 175°C.

[0040] Continue stirring until the liquid in the flask becomes viscous, then pour the viscous product into deionized water to obtain a milky white solid product SPAEKS.

[0041] After the product is cut, it is boiled in deionized water at 100°C for three times to ensure complete removal of monomers.

[0042] Finally, the milky white solid is dried at 60°C for 24 hours and collected for use.

[0043] SP-Mo 74 Preparation method of -x.

[0044] Disperse an appropriate amount of SPAEKS uniformly in NMP solvent, and uniformly disperse it by ultrasonic treatment.

[0045] Subsequently, different amounts of Mo 74(2.5 wt%), (5 wt%) and (7.5 wt%) and dissolved into SPAEKS.

[0046] The film forming solution was magnetically stirred at room temperature until complete dissolution.

[0047] The mixed solution was stirred at 60°C for 2 hours to complete the blending.

[0048] The mixed solution was uniformly dispersed on a glass plate and heated in an oven at 80°C for 24 hours to ensure film formation.

[0049] After cooling the oven to room temperature, it was soaked in deionized water for one day to remove excess solvent and ensure complete phase separation.

[0050] Subsequently, the film was immersed in a matching 1M sulfuric acid solution for 24 hours, fully ion exchanged to ensure a normal proton transport path.

[0051] After that, the film was rinsed with water using tweezers, washing away the residual sulfuric acid.

[0052] And stored with clean deionized water.

[0053] The accompanying table illustrates the chemical structure of the material, Figure 1 We used a scanning electron microscope (SEM, Hitachi SU8220) to observe the surface of the film.

[0054] Figure 2 Thermogravimetric analysis (TGA) was performed using a PerkinElmer Pyris 1 TGA device under nitrogen flow, with a temperature range of 30°C to 800°C and a heating rate of 10°C / min.

[0055] Figure 3 Mechanical strength testing was performed using a universal tensile machine (Instron model 5965) at a tensile rate of 2 mm / min.

[0056] Figure 4 For the oxidative stability test of the film, the weight of the dried film was measured, and the film was immersed in Fenton reagent (3% hydrogen peroxide solution containing 2 ppm ferrous sulfate) at 80°C for 1 hour.

[0057] After drying the residue at 60°C, the weight of all films was measured. The resistance to oxidation was calculated as the ratio of the initial weight (W0) to the residual weight (W1). W Ox (%) = W1 / W0 x 100%.

[0058] Impedance testing was done on a Biological SP-300 device.

[0059] The proton conductivity of the membrane was measured using the four-probe method with an SP-300 electrochemical workstation.

[0060] Impedance measurements were performed in a temperature range of 30 to 80°C and a frequency range of 1 Hz to 1 MHz.

[0061] Specifically, the membrane needs to be soaked in water before testing, and the fully hydrated membrane is placed between two polytetrafluoroethylene plates for measurement.

[0062] These boards were cut to a size of 50 mm (length) x 10 mm (width).

[0063] Proton conductivity (σ, S cm) of membrane sample -1 ), where L (cm) is the distance between adjacent electrodes, and S (cm) is the distance between adjacent electrodes. 2 Let σ represent the cross-sectional area of ​​the membrane, and R (Ω) be the membrane resistance. The calculation formula is: σ = L / R·S.

[0064] The activation energy (Ea) of the membrane is calculated using the Arrhenius equation: ln(σ)=ln(σ0)-(Ea / RT), where R is 8.314 kJ mol. -1 σ0 is the pre-exponential factor, and T(K) is the temperature.

[0065] Figure 6 Using an 850 fuel cell testing system and referring to previous methods, the performance of the prepared fuel cell membrane was tested by hot pressing.

[0066] The active area of ​​the sample was 2×2 square centimeters, and the catalyst loading at both the anode and cathode was 0.5 mg / square centimeter.

[0067] The membrane is subjected to hot pressing at a temperature of 140°C and a pressure of approximately 10 MPa.

[0068] The test environment was set to a constant temperature of 80℃ and a relative humidity of 100%.

[0069] Hydrogen (H2) and oxygen (O2) are supplied to the anode and cathode of the fuel cell at flow rates of 300 mL / min and 500 mL / min, respectively.

[0070] Figure 7 , Figure 9 Record the membrane weight (W) after drying for the membrane's water absorption and swelling curve. dry ) and thickness (T) dry The dried membrane was immersed in deionized water at different temperatures (30℃, 40℃, 60℃, 80℃) for 24 hours.

[0071] Measure the weight (W) of the wetted film. wet ) and thickness (T) wet ).

[0072] Calculate WU and SR using the following formula: WU(%) = [(W wet -W dry The formula for calculating SR(%) is SR(%) = [(T) / Wdry] × 100%. wet -T dry ) / T dry ×100%.

[0073] Characterized by Fourier transform infrared spectroscopy (FT-IR, Thermo Fisher Scientific).

[0074] The infrared spectroscopy of the membrane was performed using a total reflectance infrared spectrometer (ATR, Bruker Vector-22, Germany) against an air background.

[0075] The water contact angle test was performed using a DSA 30I droplet analyzer.

[0076] Before the experiment, all membranes were removed from deionized water and any residual moisture on the surface was quickly wiped off.

[0077] To test the weight of the dried membrane, the membrane was immersed in Fenton's reagent (3% hydrogen peroxide solution containing 2 ppm ferrous sulfate) at 80°C for 1 hour.

[0078] After the residue was dried at 60°C, the weight of all membranes was measured.

[0079] Oxidation resistance is calculated as the ratio of initial weight (W0) to residual weight (W1). Ox (%) = W1 / W0 × 100%

[0080] The average membrane thickness is 0.025 mm.

[0081] Legend.

[0082] Implementation Figure 1 The surface of the composite film is shown by scanning electron microscopy. As the doping concentration increases, the surface of the composite film becomes uniform, dense, and free of aggregation.

[0083] Implementation Figure 2 The thermal stability of the composite film was tested, and it was found that it could still maintain a certain degree of thermal stability after being doped with polyoxometalates.

[0084] Implementation Figure 3 To improve the mechanical tensile strength of composite membranes, the introduction of polyoxometalates, due to their inherent structure, can enhance the mechanical properties of the composite membrane. This is consistent with the implementation of... Figure 1 The results are consistent.

[0085] Implementation Figure 4To test the oxidative stability of the membrane, the membrane was immersed in a 2 ppm Fenton solution at 80°C for 12 hours. The test results showed that the composite membrane could still retain a certain amount of mass.

[0086] Implementation Figure 5 For proton conductivity, the conductivity at 80℃ is 62 mS / cm. -1 .

[0087] Implementation Figure 6 The power density diagram for the hydrogen-oxygen fuel cell shows that the power density of the composite membrane is 272 mW / cm². -2 .

[0088] Implementation Figure 7 , Nine The composite membrane exhibits higher water absorption and lower swelling capacity when the doping ratio reaches the optimal level of 5%.

[0089] Implementation Figure 8 The infrared curves of the composite membrane and its original membrane were obtained to verify the synthesis of the membrane and the composite membrane.

[0090] In summary, this invention prepares a proton exchange membrane based on a polyoxometalate hybrid filler supported on sulfonated polyarylether ketone sulfone. By introducing polyoxometalates with high proton conductivity, the proton conductivity of the hybrid membrane is effectively improved. This method creates a favorable chemical microenvironment for proton conduction and is a filler implementation method with high predictability.

[0091] For example, Mo cluster polyoxometalates are introduced into SPAEKS as proton-conducting inorganic fillers in composite membranes to solve the "trade-off" between high proton conductivity and mechanical strength.

[0092] The above-described contents can be implemented individually or in various combinations, and these variations are all within the protection scope of this invention.

[0093] It should be noted that in this paper, relational terms such as first and second are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations.

[0094] Moreover, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0095] In the absence of further restrictions, an element defined by the phrase "includes a..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes the element.

[0096] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific embodiments of the present invention are limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such deductions or substitutions should be considered within the scope of protection of the present invention.

Claims

1. The proton exchange membrane according to claim 1 belongs to an inorganic-organic hybrid material.

2. Claim 1 is a proton exchange membrane for low temperature, notably the main chain is prepared from polyarylether ketone sulfone with a sulfonation degree of 30% and a polyoxometalate with high proton conductivity.

3. The mass ratio of the proton exchange membrane raw material to the filler mentioned in claim 2 is 2:0.

05.

4. The filler in claim 2 is a Mo cluster polyoxometalate.

5. The chemical formula of the filler in claim 4 is (C2H8N). 14 (NH4)4H 14 [Mo V 48 Mo VI 26 O2O2(OH) 12 [(SO4)6]·46H2O (abbreviated as {Mo] 74 }).

6. The solvent involved in claims 1-5 is NMP.

7. Dry the film-forming solution to form the proton exchange membrane.

8. The preparation method according to claim 7, characterized in that, The hybrid filler is prepared by mixing the filler polyacid and the (DS=30%) sulfonated polyaryletherketone sulfone.

9. The application of the proton exchange membrane according to any one of claims 1-7 in a direct hydrogen-oxygen fuel cell.

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