TW201122037A - A proton exchange composite membrane and preparation thereof - Google Patents

Abstract

The present invention relates to a proton-exchange composite membrane with low thickness, low methanol crossover, and low proton transport resistance and its preparation method. The invention comprises of polymer fiber thin film with impregnated proton exchange resin. Wherein the polymer fiber thin film having fiber diameter less than 500 nm, pore sizes less than 30 μ m, and porosity larger than 70%. The thickness of the composite membrane is around 35 to 70 μ m. The invention can be used as a proton exchange membrane for direct methanol fuel cell (DMFC)application with high performance.

Description

201122037 VI. Description of the Invention: [Technical Field] The present invention relates to a proton exchange composite membrane having low film thickness, low sterol penetration and low proton conduction resistance, and a preparation method thereof. In particular, it relates to a proton exchange membrane which is applied to a direct methanol fuel cell, has a low film thickness, a low proton conductivity, a low methanol permeability, and an excellent dimensional stability, and a preparation method thereof. [Prior Art] A fuel cell directly generates electric energy by electrochemically reacting with a fuel such as helium, decyl alcohol, zinc, or the like with oxygen or air. Since it reduces many intermediate conversion procedures such as mechanical and thermal energy, the fuel cell has a very high energy conversion efficiency compared to other conventional electric energy generation programs. The direct methanol fuel cell (DMFC) made of polymer electrolyte membrane (PEM) has low temperature operation (Temp < 100. 〇, small volume and high power density, etc.) It is suitable for general portable power, such as notebook computers, mobile phones, and digital cameras, so it is receiving more and more attention. However, direct sterol fuel cells still have: (1) the electrode catalyst activity is not high enough; (2) the catalyst will be The intermediate product carbon monoxide poisoning; and (3) sterol penetration through the proton exchange membrane and other three issues need to be resolved. In the literature report, Nafion_117 (perfluoro acid resin, film thickness 175μιη; DuPont, USA) proton exchange membrane preparation Membrane electrode assembly (ΜΕΑ). The advantages and disadvantages of Nafion applied to the direct 201122037 methanol fuel cell are as follows: Advantages: (1) excellent proton conductivity; (2) excellent mechanical and chemical properties; (3) long Stable characteristics of time operation. Disadvantages: (1) expensive (about 8〇〇~1〇〇〇us$/m2;); (2) high sterol penetration rate, so it is applied to sterol combustion Battery, the efficiency will be reduced; (3) The operating temperature is higher than 1 〇〇. When 〇 above, the water molecules will be lost, and the proton exchange performance of the proton exchange membrane will drop rapidly. To reduce the sterol penetration rate, improve the DMFC fuel cell. The power generation power is conventionally mixed in a Nafion proton exchange membrane with a polymer which is less soluble in sterol or water, such as polyvinyl alcohol (PVA), PVA, and poly(poly( Acrylonitrile); PAN), polyimide (PIM), etc., or mixed nano inorganic compounds such as: silicate, zirconium oxide, etc. PVA, PAN, i > IM polymer or Although the nano inorganic compound can be mixed with Nafion solution to reduce the sterol permeability, but the sterol and water are mutually soluble substances, the methanol permeability of the general material is proportional to the proton conductivity. PVA, PAN Polymers or inorganic compounds such as PIM have low sterol permeability, but their proton conductivity is lower than Nafion. Therefore, the modified material of Nafion proton exchange membrane applied to DMFC should have: high proton conductivity σ With low The dual nature of the penetration rate, that is, the ratio of [proton conductivity] / [methanol penetration] = σ 。. Current literature [BS Pivovar, Y. Wang, EL Cussler, J. Membr. Sci., 154 ( 1999) 155-162; NW DeLuca, YA Elabd, J. Membr. Sci., 282 (2006) 217-224; NW DeLuca, YA Elabd, J. Power Sources, 163 (2006) 386-391.] 201122037 The polymer material which is suitable for Nafion modification and applied to DMFC is PVA. According to the literature research report, Nafion mixed 5 wt% PVA blended membrane (film thickness > 175 μιη), its DMFC performance is better than Nafion-117 (film thickness ~ 175 μιη), but the PVA blending amount is greater than 10 wt %, Nafon/PVA blended membranes have a DMFC performance that is much lower than that of Nafion-117°PVA. The Nafcm/PVA blended membrane with a DMFC performance of less than 1% by weight is much lower than Nafion-117. PVA and Nafion are not well miscible, so when the pVA content g 1〇wt ° / ' 'PVA is not easy to be uniformly dispersed in the Nafion membrane; (2) sterol / water mixed solution has a small amount of low polymerization degree PVA Solubility, so high pva content will cause traces of PVA to be dissolved by sterol/aqueous solution during DMFC operation; (3) too high PVA content will cause a significant decrease in proton conductivity.

Gore [B. Bahar, A.R. Hobson, J. Kolde, US

Patent 5,547,551,1996.] impregnating a Nafion solution with a microporous polytetrafluoroethylene (pTFE; poly(tetrafluoro ethylene), porosity > 75%) film to fill Nafion to a porous ptfe film to make "Nafion" /PTFE composite film, '(film thickness 20-25 μιη). Because PTFE film has excellent mechanical properties, and PTFE and sterol are incompatible with each other, it has barrier properties to sterol and can reduce the thickness of proton exchange membrane. In turn, the impedance of proton transfer is reduced (the greater the thickness of the proton exchange membrane, the greater the impedance), and the amount of Nafion used is reduced to meet the demand for low cost and high performance. Research Report [HL Lin, TL Yu, LN Huang, LC Chen, KS Shen, GB Chung, J. Power Sources, 150 (2005) 201122037 11-19.] shows that the MFFC performance of the Nafion/PTFE composite membrane (film thickness 20-25 μιη) is better than that of Nafion-117 (film thickness 175). Μηη). However, the chemical structure of PTFE is -(CF2-CF2)-, which does not contain other polar functional groups, so the force between Nafion and the porous PTFE membrane is only a simple physical adsorption force. Therefore, "Nafion/PTFE composite membrane , the disadvantages are: PEMFC or DMFC Under long operation, Nafion and PTFE will have delamination (delamination) phenomenon. SUMMARY OF THE INVENTION As can be seen from the foregoing, in order to solve the problem that the proton exchange membrane is applied to a direct methanol fuel cell and methanol penetrates the proton exchange membrane, resulting in a significant decrease in battery efficiency, the prior literature reports propose two Nafion-modified proton exchange membranes: (1) Preparation of "Nafion/PVA blended membrane" (film thickness 175-200μιη) by Nafion blended with PVA; (2) Preparation of "Nafion/microporous PTFE composite membrane" by impregnating Nafion solution with microporous PTFE membrane as substrate (film thickness 20_25 μιη). Both Nafion-modified proton exchange membranes have low sterol penetration and low proton conduction resistance performance, so both DMFC performance can surpass Nafion-117. However, the protons of the two protons still have their shortcomings. (1) The compatibility of Nafion and PVA is poor. The PVA blending amount of the Nafi〇n/PVA blended film is up to 5 wt%, and the PVA content of the blended blend is greater than 5 At wt%, the proton conductivity is greatly reduced, and the DMFC performance is also greatly reduced; (2) The film thickness of the Nafion/PVA blend film is equivalent to that of Nafion_117 at 175·20〇哗. But because Nafi〇n is expensive, so 201122037

The thickness of Nafion/PVA blended film is comparable to that of Nafion-117, which is higher than Nafion-117 and cannot compete with DuPont's Nafion-117 in the market; (3) Nafion/microporous PTFE composite film has low film Thick (20_25 μιη), low cost, low sterol penetration and low proton conduction resistance 'but PTFE does not contain polar functional groups and Nafion's 'low surface strength' is prone to occur under long-term operation of fuel cells The phenomenon of delamination of PTFE and Nafion. In order to solve the above disadvantages of the Nafion/PVA blend film and the Nafion/PTFE composite film, the present invention provides a method for improving the PVA content of the Nafl〇n/PVA film, reducing the film thickness, reducing the film cost, and having low sterol penetration and low quality. Sub-conductive impedance and proton exchange composite membrane with excellent dimensional stability and preparation method thereof. This proton exchange composite membrane can be applied to a direct sterol fuel cell with excellent performance. The proton exchange composite membrane of the present invention is a proton formed by impregnating a proton exchange resin with a pore diameter of 3 〇 pm or less and a porosity of more than 70%. Exchange the composite membrane. The overall film thickness of the proton exchange composite membrane is 35 to 70 μm. Wherein the polymeric fiber is selected from the group consisting of: PVA, PAN or hydrazine having low sterol penetration and low proton conduction resistance. The proton exchange filling material is selected from at least one of the group consisting of perfluorocarbonated resins, sulfonated polyether ethers, sulfonated poly(phenylene ether ether ketones), perfluoro acid-reducing resins (Nafion), and acidified polyether oximes, etc. A polyelectrolyte with high proton conductivity. 201122037 Victorian film chemical cross-linking treatment of fiber _. Polymer fiber chemical cross-linking treatment of fiber membranes (such as at least 2 brinic functional organic aliphatic or aromatic quinones: etc.) or epoxy resin, or dicarbonate compound, money compounding fine sequence including the following steps: 1) Polymer fiber membrane production

A fiber membrane formed by a diameter of 5 Å was produced by electrospinning, and the rate of the polymer fibers in the pores of the fiber membrane was 70% or more. ^ Under 3〇μηι, the pore (2) polymer fiber membrane chemical cross-linking treatment with H-f or water polymer fiber membrane (such as PVA) must be chemically cross-linked Substance, such as glutaric acid, etc., "or aromatization, etc. Rolling tree, or dicarbonate compound (3) fiber membrane impregnated proton exchange resin membrane) ^ Niu!® step (1) without chemical cross-linking treatment (such as PAN Fiber = 4 = Made by chemical cross-linking treatment (such as pva fiber membrane), two-dimensional membrane impregnation or coating of proton exchange resin solution, so that the two::: resin infiltrated into the pores of the polymer fiber membrane, and then sub-exchange The resin fiber film is annealed at 120 ° for 30 minutes. (3-b) Repeat ((4) impregnation or coating step to achieve %A to 201122037 70 μηι film thickness' and [proton exchange resin]/[ The weight ratio of the polymer fiber membrane] is from 97/3 to 80/20. The annealing step after the completion of the last impregnation/coating step is performed at 120 to 125 ° C for 1.5 to 15 hours of annealing. The method 'can improve the defects of Nafion/PVA blended membrane, and "Nafion/PTFE composite membrane": (1) Improve the modified polymer (such as P VA, PAN, etc.) Percent content of blending: nanofiber membrane (mesh) impregnated with a proton exchange resin filled with polymer to fill the pores of the nanofiber of the polymer, and 0 will produce a similar modified polymer and proton exchange resin mixed The unevenness of the time can improve the content of the modified polymer in the membrane and greatly improve the methanol barrier performance. (2) The PVA fiber can be reduced by the chemical parent to reduce the probability of ργ^ being dissolved by water or sterol, and increase the proton exchange. Membrane stability and reduced sterol penetration. (3) Decrease the thickness of proton exchange membrane: due to the greatly improved content of modified polymer in the membrane 'At the same time cross-linking PVA and PAN polymer Nymphite fiber with alcohol and water solvent Low compatibility, can greatly improve the sterol barrier performance 'thickness of the film can be reduced, thereby reducing the proton exchange resistance of the proton exchange membrane' to improve the performance of the fuel cell. (4) The polymer fiber and proton exchange resin Nafion have a good interface Force·· Due to polymer fibers, such as -OH functional groups on the surface of PVA nanofibers, surface of pan nanofibers 10 201122037 • CN functional groups can be combined with proton exchange resins such as Nafi The -S〇3H functional group of n is bonded, so that the polymer fiber and the proton exchange filling material Naficrn have a good interface force and can enhance the mechanical properties of the composite film. Through the above description, the proton exchange membrane of the present invention has at least the following effects: ', (1) can increase the percentage of modified polymer blending; (2) can reduce the sterol permeability of the proton exchange membrane; (3) can increase the [proton conduction] / [sterol penetration] ratio; 4) It can improve the size stability of proton exchange membrane: crosslinked polymer fiber membrane can reduce the swelling of water and sterol by proton exchange membrane and increase dimensional stability. [Embodiment] The following examples are merely illustrative of the proton exchange membrane of the present invention and the preparation thereof, and are not intended to limit the present invention, and various modifications made by the spirit of the present invention are not included in the scope of the present invention. Covered. [Example 1]

Nafion/PVA nanofiber proton exchange composite crucible preparation 1. PVA electrospun fiber membrane production: Electrospinning equipment installation as shown in Figure 1: including (1) high voltage electricity (1〇), (2) injection syringe and needle (10), solution core 11 Pu, (4) copper electrode fiber collection roller (30). (1.1) PVA electrospun fiber production setting conditions: (The working distance of the magic injection needle to the copper electrode collection plate is 18 cm; (b) The voltage is 18 kV; (c) PVA (poly(vinyl alc〇h〇1) 曰The synthetic chemical 'Z-410, deacetylation degree 97.5~98 5 %) aqueous solution concentration is 12 wt%; (d) PVA aqueous solution flow rate is 1.2 ml / min. PVA electrospinning with fiber diameter below 500 nm is prepared by the above conditions. The fiber membrane has a pore diameter of less than 30 μm and a porosity of less than 80 〇/〇. (1.2) PVA electrospun fiber parent-stay reaction: pva electrospun fiber is filled with glutaraldehyde (Fluka Chemical Co, Inc.) vapor In a closed vessel, the crosslinking reaction was carried out at room temperature for three days, and then the residual unreacted pentane was washed with isopropyl alcohol (Merck Co), and then heated at 603⁄4 for 20 minutes to volatilize residual isopropyl alcohol. Figure 2 is a photograph of a scanning electron microscope (SEM; S-3000N, Shimazu) of PVA crosslinked electrospun fibers.

Preparation of Nafton/PVA nanofiber proton exchange composite membrane: (2.1) Nafion solution preparation: 5.0 wt% Nafion solution (Nafion EW=1100, DuPont, USA) diluted with isopropanol to prepare 3.0 wt% and 4.0 wt% Nafion solution . (2.2) The PVA electrospun fiber membrane produced in the step 1 was immersed in a 3 〇 201122037 wt% Nafion solution for 24 hours, and the film was taken out and annealed at 125 ° C for 20 minutes. (2.3) The composite membrane prepared in the step (2.2) was immersed in a 4.0 wt% Nafion solution for 24 hours, and then heated and quenched at 125 ° C for 20 minutes. (2.4) The composite film prepared in the step (2.3) was immersed in a 5.0 wt〇/0 Nafion solution for 24 hours, and the film was taken out and annealed at 125 ° C for 60 minutes. (2.5) The above steps (2.2) to (2.4) can adjust the concentration of the Nafion solution and the number of times the solution is immersed, and adjust the film thickness and the [Nafion]/[PVA] weight ratio. The final film thickness target is 35 μιη to 70 μπι', preferably 50 μm Nafion/PVA weight ratio 97/3 to 80/20, and preferably Nafion/PVA weight ratio is 90/10. Figure 3 is a SEM electron micrograph of a Nafion/PVA nanofiber proton exchange composite membrane. The Nafion/PVA nanofiber proton exchange composite membrane has a membrane thickness of about 50 pm and a PVA/Nafion weight ratio of 1.0/9.0. 3. Nafion/PVA nanofiber proton exchange composite membrane thermogravimetric analysis (TGA) TGA thermal analysis test sample stored in pure water for at least 48 hours. Before the test, the surface moisture of the membrane was blotted with a mirror paper. The test sample weighed 5 to 10 mg 'TAA instrument TA-Q50, and the temperature rise rate was 10 C/min ′ I gas flow rate was 50 ml/min. For comparison with the pure Naflon film, the film was formed by injecting a volatile solvent into a 20 wt% Nafion solution and annealing at 125 ° C for 90 minutes. Figure 4 is the TGA data of Nafion/PVA nanofiber composite membrane and pure Nafion membrane. Through the analysis of TGA, the pyrolysis temperature and water content of the film (weight loss below 200 ° C) can be measured. It can be seen from the TGA data chart of Fig. 4 that the TGA curve of the general Nafion film has four weight loss temperature intervals, and the TGA weight loss of the sample below 200 ° C is the weight loss of water volatilization at a temperature of 280 to 400 °. C is a branched cleavage of the -S03H functional group of Nafion; and above a temperature above 420 ° C, it is the cleavage of the fluorocarbon backbone of Nafion. Circle 4 is shown at temperatures between 280 and 380 ° C. The weight loss of the Nafion/PVA nanofiber proton exchange membrane is greater than that of the Nafion membrane, possibly due to PVA cracking. Table 1 lists the TGA thermogravimetric loss of Nafion and the Nafion/PVA fiber proton exchange membrane of the present invention from room temperature to 200 ° C. This weight loss can be regarded as the water content of the membrane. It can be seen from Table i that the water content of the Nafion/PVA nanofiber proton exchange membrane is 5.2 wt% higher than that of the Nafion membrane, so that the water uptake of the Nafion/PVA nanofiber proton exchange membrane of the present invention is higher than that of the general pure. Nafion membrane. 201122037 Table 1. TGA of Nafion and Nafion/PVA nanofiber membranes 200°C thermogravimetric loss proton exchange membrane 200°C weight loss (wt%) Nafion 15.2 Nafion/PVA fiber 20.4 4. Nafion/PVA nanofiber proton exchange Membrane proton conduction resistance measurement The impedance R value of the membrane was measured by a frequency response analyzer (Solartron SA1255B) at a temperature of 70 ° C and RH 95%, and substituted into the formula (1) to calculate the proton conduction of the membrane. Rate σ. (l) σ = L / (RxA) where σ = proton conductivity; L = film thickness; A = impedance measurement area (A = 3.14 cm 2 ). • Before the membrane impedance measurement, the Nafion/PVA fiber proton exchange composite membrane and Nafion-117 membrane were placed in a 0.5 Μ sulfuric acid aqueous solution, heated at 85 ° C for one hour, taken out and washed with 85 ° C distilled water for 10 minutes. After washing, conduct AC-impedance measurement. Table 2 shows the impedance value and proton conductivity of the Nafion/PVA fiber composite membrane. It can be seen that although the Nafion-117 proton conductivity is higher than that of the Nafion/PVA fiber proton exchange composite membrane, the Nafion/PVA fiber membrane of the present invention 15 201122037 (film The film thickness of 50 μm thick is lower, so the impedance ratio (L/σ) is lower than that of Nafion-117 (film thickness 175 μm). Table 2. Nafion/PVA fiber membrane proton conduction impedance data (Temp= 70°C; RH= 95%) Proton exchange membrane thickness Μμπι) Impedance K(Q) Conductivity σ (S/cm) Impedance Ι7σ(Ω cm2) Nafion 117 175 0.29 0.0192 0.911 Nafion/PVA fiber 50 0.14 0.0114 0.438 5· Nafion/PVA fiber proton exchange composite membrane sterol permeability coefficient measurement Proton exchange membrane is sandwiched between two glass tanks, both sides of the membrane are filled Concentration 2 曱 曱 曱 (methanol,

MerckCo) a tank of aqueous solution and tank B of pure water. The volume of the A tank and the B tank solution are each 400 m and the test temperature is 7 ° C. The solution of the B tank was extracted 2 ml three times every hour, and the density of the B tank solution was measured by density. The sterol concentration cBW of the B-tank solution can be measured by substituting the value into the previously prepared density of the aqueous methanol solution of known methanol concentration versus the concentration of the sterol concentration. The methanol osmotic coefficient P value can be obtained by plotting the measured sterol concentration Cb(1) versus (t_t〇) and calculating the slope substitution equation (2)'. ', (2) - t0) 201122037 wherein, the film thickness, the film cross-sectional area measured by the permeability coefficient of co-alcohol, to is the starting system _. The initial enthalpy of methanol in the A-slot solution is CA(t〇)=2 Μ ′. Figure 5 is a plot of (10) vs. %, and the sterol permeability coefficient is obtained from the slope, as shown in Table 3. It can be seen from Table 3 that although the film thickness of the proton exchange membrane of Nafion/PVA fiber is thinner than that of Nafion-117, the methanol permeability coefficient is lower than that of Nafi〇n ii7, and the σ/ρ value of the Nafion/PVA fiber composite membrane is higher than that of Nafion ιΐ7. membrane. This proves that the Naflon/PVA nanofiber proton exchange membrane of the present invention has superior methanol resistance characteristics and low proton conduction resistance, and can improve the performance of the DMFC. Table 10 methanol bleed · gluten P production σ / Ρ data (TeniD ^ 70 〇 C, CA (U = 2 M, proton exchange membrane thickness L (pm) methanol permeability coefficient P (cm2 / sec) W z touch σ /Ρ (S sec/cm3) Naflon -117 175 3·31χ1〇·1 5.80xl03 Nafion/PVA Fiber 50 1.73xl〇'1 6.58xl03 1

Preparation of Nafion/PVA fiber proton exchange composite membrane electrode group (MEA) and DMFC cell test 6.1. Electrode assembly (MEA) preparation (1) Proton exchange membrane pretreatment: Put 5 wt% H2〇2 at 85 °C After heating for one hour, it was placed in distilled water and heated at 85 ° C for half an hour, then placed in 0.5 Torr of H 2 SO 4 and heated at 85 ° C for 10 minutes, and finally placed in distilled water and heated at 85 ° C for 10 minutes. (3⁄4 catalyst slurry preparation: anode catalyst formulation [pt_Ru/C (pt 20wt%; RU 20wt%; E-Tek Co)] / [Nafion (© body)] / [water] / [isopropyl alcohol] = 2/ 1/ 10/2 (weight ratio); Cathodic catalyst formulation [Pt/C (Pt 40 wt%; E-Tek) / Nafion (solid) / water / isopropanol = 2/ 1/ 10/2 ( Weight ratio). The catalyst solution is mixed by ultrasonic vibration for 15 min, and then heated at 60 ° C to volatilize the solvent to make the solution viscous. 〇) Catalyst coating and membrane electrode assembly: Yin The anode catalyst solution was coated on carbon paper (SGL-35BC; SGL), the amount of the anode catalyst coating was Pt-Ru = 4 mg/cm2, and the amount of the cathode catalyst coating was Pt = 2 mg/cm2. The catalyst coating area is 5.0 x 5.0 cm2. The electrodes were placed on opposite sides of the proton exchange membrane, respectively, by a hot press at a temperature of 135. (:, pressure 50 Kg/cm2 ' After 30 seconds of hot pressing, heat-press it for 1 minute at 1 〇〇Kg/cm2. The single-cell test cell test system is 5100 series CHINO fuel-electrical 'also measured type 5 糸' oxygen The flow rate was 150 ml/min, the flow rate of methanol water (Merck concentration) was 2.5 ml/min, and the test temperature was 7 〇. (:, the battery/-V curve was measured. Fig. 6 is the Nafion-117 film (臈) =Π6 μιη) and the Nafion/PVA fiber proton exchange composite membrane (film thickness=5〇201122037 μιη) and Nafion/PVA fiber proton exchange membrane (film thickness=35 μηι) of the present invention, respectively, to form MEA DMFC fuel cell iV data Figure 6. It can be seen from Figure 6 that the OCV (open circuit voltage) data size of the three MEAs is: Nafion-117 film (film thickness = 175 μιη) > Nafion/PVA fiber proton exchange composite film (film thickness = 50 μηι) &gt Nafion/PVA fiber proton exchange composite membrane (film thickness = 35 μιη). The OCV of MEA prepared by Nafion/PVA fiber proton exchange composite membrane (film thickness = 35 μηι) is low, probably because the thickness of the membrane is too low, resulting in The higher methanol permeation makes the OCV lower. The iV curve of Figure 6 shows that the battery performance of the three] V1EAs is: Nafion/P VA fiber proton exchange composite membrane (film thickness = 50 μm) > Nafion-117 membrane (film thickness = 175 μιη)> Nafion/PVA fiber proton exchange composite membrane (film thickness = 35 μm). Nafion/PVA fiber of the present invention The membrane thickness of the proton exchange composite membrane (film thickness = 50 μηη) is much lower than that of the Nafion-117 membrane (film thickness = 176 μηη), making the proton conduction resistance of the Nafion/PVA fiber proton exchange composite membrane lower than Nafion-117, plus PVA The high methanol barrier ability makes the MEA performance of the Nafion/PVA fiber proton parent film (film thickness = 50 μιη) of the present invention superior to that of the present invention.

Mafion_l 17 ° Nafion/PVA fiber proton exchange film (film thickness = 35 μιη), because the thickness of the film is too low, resulting in high sterol penetration, so OCV is low and the enthalpy performance is poor. [Embodiment 2] 201122037

Preparation of Nafion/PAN nanofiber proton exchange composite membrane In this example, a PAN nanofiber membrane produced by electrospinning technique was used to impregnate a Nafion solution to prepare a Nafion/PAN fiber proton exchange composite membrane. The preparation procedure is as follows: 1. PAN electrospun fiber membrane production: The electrospinning equipment is shown in Figure 1. It includes: (1) high-voltage power supply (1〇); (2) injection syringe and needle (2〇); 3) solution injection pump; (4) copper electrode fiber collection roller (3 〇). (1·1) PAN electrospun fiber production conditions are set: (4) The working distance of the injection needle to the copper electrode collection plate is 18 cm; (b) The voltage is 18 kV; (c) PAN (polyacrylonitrile) / DMAc (N, N, The dimethyl acetamide) solution has a PAN concentration of 15 wt%; (4) the solution flow rate is i.2 ml/min. A PAN electrospun fiber membrane having a diameter of 500 nm or less was produced by the above conditions. Fig. 7 is a SEM electron micrograph of a PAN nanofiber membrane. 2. Preparation of Nafion/PAN fiber proton exchange composite membrane (2.1) PAN fiber membrane was immersed in 2. 〇 wt% Nafion solution for 6 hours. The fiber membrane was taken out, and after the solvent was slightly dried, it was placed in a baking phase of 125 C for heat annealing for 2 Torr. (2.2) The pan fiber membrane of step (2.1) was immersed in a 3 〇 wt% Nafion solution for 4 hours. The pAN fiber membrane was taken out, and after the solvent was slightly dried, it was placed in an oven at 125 ° C for heat annealing for 20 minutes. 20 201122037 (2.3) The PAN fiber membrane of the step (2.2) was immersed in a 5.0 wt% Nafion solution for 2 hours, and after the solvent was slightly dried, it was placed in an oven at 125 ° C for heat annealing for 1 hour. Fig. 8 is a front SEM photograph (x3000) of the film of the 〇11/?8] fiber after completion of the step (2.3). It can be seen from Fig. 7 and Fig. 8 that the PAN nanofiber membrane can clearly see the interlaced fibers before the Nafion solution is impregnated, and has a considerable number of pores. However, after the step of immersing the Nafion solution in sequence, the PAN nanofibers are sequentially obtained. The pores of the membrane have been densely filled by Nafion. The Nafion/PAN nanofiber membrane has an average membrane thickness of 38 μηη and a Nafion content of about 82.0 wt0/〇. 3. Nafion/PAN fiber proton exchange composite membrane impedance measurement The measurement procedure was as described in Example 1. Before the impedance measurement, the proton exchange membrane was placed in a 0.5 Μ sulfuric acid aqueous solution, heated at 85 ° C for one hour, and then taken out and washed with 85 ° C distilled water for 10 minutes, and then subjected to AC resistance (AC impedance). )Measure. The test environment is: temperature 70 ° C, relative humidity 95%. The impedance value R of the film is measured, and the proton conductivity σ of the film can be calculated by substituting the formula (1). Table 4 shows the impedance and proton conductivity of the Nafion/PAN fiber composite membrane and Nafion-117. It can be seen that the Nafion-117 proton conductivity is higher than the Nafion/PAN fiber proton exchange composite membrane of the present invention, but the low membrane thickness Nafion/PAN The impedance ratio of nanofiber membrane (film thickness 38 μιη) (Ι7(σ) is lower than Nafion-117 (film thickness 175 21 201122037 μπι). Table 4. Nafion/PAN nanofiber proton exchange membrane proton conduction impedance data (Temp = 70°C; RH= 95 %; 3.14 cm2) _ Proton exchange membrane thickness L (μπι) Impedance R(Q) Conductivity σ (S/cm) Impedance ratio L/o(Qcm2) Nafion -117 175 0.290 0.0192 0.911 Nafion/PAN fiber 38 0.114 0.0106 0.243 4. The Nafion/PAN nanofiber proton exchange composite membrane sterol permeation measurement step is as described in Example 1. The measurement temperature is 70 ° C, and the sterol is in the A tank. The initial concentration cA(t〇)= 3 Μ, the measured sterol concentration CB(t) is plotted against (tt.), and the slope of the calculated data map is substituted into the formula (2) to obtain the sterol. The permeability coefficient p value. Figure 9 is cB(t) vs. (Η〇图' The sterol permeability coefficient p value calculated from the slope, as shown in Table 5. As shown in Table 5, Nafion/PAN fiber Although the membrane thickness of the sub-exchange composite membrane (38 μιηη) is thinner than Nafion-ΙΠ (thickness 175 μηη), the permeability coefficient of sterol is lower than that of Nafi〇n_m, and the σ/ρ value of the Nafion/PAN composite membrane is higher than that of Nafl〇. n_U7 film. Shows that the proton exchange membrane of the present invention has superior sterol resistance and low proton conduction resistance characteristics. 22 201122037 Ship and membrane

Nafion -117 Nafion/PAN fiber film thickness L methanol permeability coefficient P (cm2/sec) 3.3UIQ-6 9.18x10'7~~

σ/Ρ (S sec/cm3) 5.80x103 11.5xl03 [Simple description of the drawings] Fig. 1 is an electrospinning apparatus apparatus for producing a polymer fiber according to the present invention. Fig. 2 is a SEM electron micrograph of a PVA crosslinked electrospun fiber membrane (χ3000) ). Figure 3 is a SEM electron micrograph of a Nafion/PVA nanofiber proton exchange composite membrane. Nafion/PVA nanofiber proton exchange composite membrane and membrane thickness of about 50μηι, PVA / Nafion weight ratio of about 1. 〇 / 9. 〇. Figure 4 is a TGA data plot of a Nafion/PVA fiber composite membrane and a pure Nafion membrane. (I) is expressed as a Nafion solution injection film; (-_) is expressed as a Nafion/PVA fiber composite film. Figure 5 shows the methanol permeation measurement of Nafion-117 and Nafion/PVA-f fiber membranes vs. 々. A data plot of the graph; where Temp = 70 ° C, CA (t 〇) = 2 M; (♦) denoted as Nafion-117 membrane; (+) denotes Nafion/PVA fiber composite membrane. Figure 6 is a Nafion-117 film (film thickness = 176 μιη) and a Nafion/PVA fiber proton exchange composite membrane (film thickness = 50 μιη) and a Nafion/PVA fiber proton exchange membrane (film thickness = 35 μιη), respectively. i DMFC fuel cell iV data chart; where [CH3OH] = 2 23 201122037 Μ, sterol solution flow rate is 2.5ml / min, 02 flow rate = i50ml / min, battery temperature is 80 ° C. Fig. 7 is a SEM electron micrograph of a PAN nanofiber membrane (x3000). Fig. 8 is a front SEM photograph (x3000) of a Nafion/PAN fiber composite membrane. Figure 9 is a sterol permeation measurement vs. Nafion-117 and Nafion/PAN fiber membrane (film thickness = 38 μιη) vs. plot data; where Temp = 70 °C 'CA(t〇) = 2 Μ ; () It is expressed as Nafion-117 (film thickness Lu = 175 μιη); (▼) is expressed as Nafion/PAN (film thickness = 38 μιη). [Main component symbol description] (10) High-voltage power supply (20) Injection syringe and needle (3〇) copper electrode fiber collection roller

twenty four

Claims (1)

201122037 VII. Patent application scope: 1. A proton exchange composite membrane comprising: (1) a nano polymer fiber membrane formed by polymer fibers having a diameter of 500 nm or less, the pore diameter of the fiber membrane being less than 30 μηη, and pores The rate is greater than 70%; and (2) impregnating the proton exchange resin filled in the pores of the nanofiber membrane; wherein the overall membrane thickness of the proton exchange composite membrane is 35~70 μηη 〇2. Proton as claimed in claim 1 The composite film is exchanged, wherein the polymer fiber is selected from at least one of the group consisting of polyvinyl alcohol (PVA), polyacrylonitrile (PAN), or polyimide (PIM). 3. The proton exchange composite membrane according to claim 1, wherein the polymer fiber membrane is chemically crosslinked. 4. The proton exchange composite membrane according to claim 3, wherein the crosslinking agent used in the chemical fiber chemical crosslinking treatment is an organic aliphatic or aromatic compound containing at least two aldehyde functional groups, and an epoxy resin. Or a dicarbonate compound. 5. The proton exchange composite membrane according to claim 4, wherein the crosslinking agent used for crosslinking the polymer fibers is glutaraldehyde. 6. The proton exchange composite membrane according to claim 1, wherein the proton exchange resin impregnated in the pores of the nanofiber membrane is selected from the group consisting of at least one of the following groups: perfluoro acid anhydride, perfluorocarbonic acid 25 201122037 Resin, sulfonated polyetheretherketone, sulfonated poly(phenylene ether ether ketone), sulfonated polyether. 7. The proton exchange composite membrane of claim 6, wherein the proton exchange resin is impregnated in the pores of the fibrous membrane. 8. The proton exchange composite membrane according to claim 6, wherein the proton exchange resin is filled in the pores of the fibrous membrane by coating. 9. A proton exchange composite membrane as claimed in claim 6 which is used in a membrane electrode assembly for a direct methanol fuel cell. 10. The proton exchange membrane of claim 1, wherein the [proton exchange resin] / [polymer fiber membrane] has a weight ratio of from 97/3 to 80/20. 11. The proton exchange composite membrane according to claim 10, wherein the proton exchange membrane has an overall membrane thickness of 50 μm. 12. The method for preparing a proton exchange composite membrane comprises the following steps: (1) preparing a polymer fiber membrane having a fiber diameter of 500 nm or less by electrospinning, having a pore diameter of less than 30 μηη and a porosity of more than 70%; (2) The polymer fiber membrane of the foregoing step (1) is impregnated or coated with a proton exchange resin solution, so that the proton exchange resin in the solution penetrates into the pores of the polymer fiber membrane, and the impregnation or coating step is repeated to reach 35. The film thickness of μπι to 70 μηη, and the [proton exchange resin]/[polymer fiber membrane] weight ratio of 97/3 to 80/20. The method of preparing a proton exchange composite membrane according to claim 12, wherein the polymer fiber is selected from the group consisting of at least one of the group consisting of polyvinyl alcohol, polyacrylonitrile or polyamine. 14. The method for preparing a proton exchange composite membrane according to claim 12, wherein the electrospinning process parameter of the electrospinning polymer fiber membrane is set to: the working distance from the injection needle to the copper electrode collection plate is 5 to 20 cm. The operating voltage is 10~30 kV, and the flow rate of the polymer solution is 0.8-1.5 ml/min. 15. The method for preparing a proton exchange composite membrane according to claim 14, wherein the polymer fiber membrane produced by electrospinning is chemically crosslinked. 16. The method for preparing a proton exchange composite membrane according to claim 15, wherein the crosslinking agent used for crosslinking the polymer fibers is an organic aliphatic or aromatic compound having at least two aldehyde functional groups, and an epoxy resin. Or a dicarbonate compound. 17. The proton exchange composite membrane preparation method according to claim 16, wherein the crosslinking agent used for crosslinking the polymer fibers is glutaric acid. 18. The method for preparing a proton exchange composite membrane according to claim 12, wherein the proton exchange filler resin is selected from the group consisting of at least one of the following groups: a perfluorosulfonic acid resin, a perfluorocarbonic resin, and a sulfonated polyetheretherketone. , sulfonated poly(phenylene ether ether ketone), sulfonated polyether sulfone. 19. The method for preparing a proton exchange composite membrane according to claim 12, wherein the proton exchange composite membrane preparation step, the step of each impregnation/coating 27 201122037 cloth step further comprises an annealing step, wherein the proton exchange membrane is at 120~ An annealing step of 20 minutes to 1.5 hours was carried out at 125 °C. 20. The proton exchange membrane preparation method according to claim 12, wherein the final completed proton exchange composite membrane has an overall membrane thickness of 50 μm. 28