CN115020770A

CN115020770A - Composite proton exchange membrane and preparation method and application thereof

Info

Publication number: CN115020770A
Application number: CN202210599305.3A
Authority: CN
Inventors: 蒋仲杰; 李金阳
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2022-05-30
Filing date: 2022-05-30
Publication date: 2022-09-06

Abstract

The invention discloses a composite proton exchange membrane, which comprises a substrate and a filler; the matrix comprises sulfonated polyether ether ketone; the filler comprises sulfonated ZIF derived porous carbon material and sulfonated white carbon black. The composite proton exchange membrane provided by the invention has the advantages of low methanol permeability and high proton conductivity, and the proton conductivity of the composite proton exchange membrane can be improved and the permeation of fuel can be blocked by filling the sulfonated ZIF derived porous carbon material; according to the invention, the zinc-based ZIF is carbonized, so that the defect of instability in an acidic environment is overcome, and the zinc-based ZIF is suitable for preparing a composite proton exchange membrane; the preparation method of the composite proton exchange membrane is simple and efficient, has low cost and has the advantage of industrial production; the composite proton exchange membrane can be widely applied to fuel cells.

Description

Composite proton exchange membrane and preparation method and application thereof

Technical Field

The invention belongs to the field of fuel cells, and particularly relates to a composite proton exchange membrane and a preparation method and application thereof.

Background

A Proton Exchange Membrane Fuel Cell (PEMFC) is an electrochemical energy conversion system that can directly convert chemical energy in fuel and oxygen into electrical energy. The efficiency of energy conversion between chemical energy and electric energy of the fuel can reach 60 percent because the fuel is not limited by the Carnot cycle. The continuous supply of fuel can generate electric energy continuously, and the occurrence of the electric energy greatly relieves the dependence of the industry on traditional energy sources. The fuel generally used in the proton exchange membrane fuel cell is hydrogen gas, methanol, or the like. During the operation of the cell, fuel is delivered to the anode to generate an oxidation reaction, generated protons are transmitted to the cathode through the proton exchange membrane, and lost electrons reach the cathode through an external circuit, so that electric energy is continuously generated. The Proton Exchange Membrane (PEM), one of the most critical components in the PEMFC, plays a role in transporting protons in the fuel cell, and also plays an important role in blocking fuel permeation and isolating electron transfer, so the performance and service life of the cell are determined by the performance of the PEM. The excellent proton exchange membrane can bring high enough proton conductivity, and simultaneously can well obstruct fuel permeation, thereby avoiding the fuel from diffusing from an anode to a cathode to cause cathode catalyst poisoning. Currently, a commercially available proton exchange membrane is a perfluorosulfonic acid membrane (Nafion), which has good proton conductivity and chemical stability, but is expensive and has high fuel permeability, which seriously hinders the commercial application of PEMFCs. Therefore, it is very important to develop a proton exchange membrane with low cost and high performance to replace the Nafion membrane.

Sulfonated polyether ether ketone (SPEEK) is one of the most promising substitutes in the application of commercial proton exchange membranes currently recognized, and the SPEEK has great application potential in the field of proton exchange membranes due to the advantages of good high thermal stability, high proton conductivity, low fuel permeability, no fluorine, no pollution, low production cost and the like. However, the proton conductivity characteristics of SPEEK are affected by the Degree of Sulfonation (DS), and in fact a high DS SPEEK base membrane grafts high density sulfonic acid functional groups, which produce high proton conductivity, into the polymer backbone, which results in a decrease in the stability of the size and chemical properties of the proton exchange membrane, thereby affecting the performance and service life of the proton exchange membrane cell. In order to enhance the competitive advantage of the SPEEK material in Proton Exchange Membrane Fuel Cells (PEMFCs), the prior art optimizes the proton exchange membrane structure and performance by introducing inorganic materials into the SPEEK material. The filler introduced into the SPEEK membrane is inorganic material, such as Carbon Nano Tubes (CNTs), White Carbon Black (WCB), Graphene Oxide (GO) and metal organic framework Material (MOF), and the inorganic filler can obviously reduce the swelling rate and the fuel permeability of the SPEEK membrane, and improve the mechanical strength and the chemical stability of the SPEEK membrane, thereby improving the comprehensive performance of the SPEEK-based proton exchange membrane.

White Carbon Black (WCB) is a common inorganic filler that has attracted considerable attention due to its hygroscopic and multifunctional properties. By adjusting the shape, size and distribution of the white carbon black, various technical requirements of the proton exchange membrane for the fuel cell can be met, such as improving the thermodynamic stability of the membrane, enhancing the proton conductivity of the membrane and reducing the methanol permeability. A large number of active-OH groups on the surface of the WCB can provide various chemical modification sites to adapt to different use conditions of the composite membrane. In the reported literature, sulfonation of white carbon black by chemical modification has been widely used for organic-inorganic nanocomposite Polymer Electrolyte Membrane (PEM) fillers. The prior art discloses that the thermal stability and proton conductivity of a composite membrane can be improved by introducing phosphoric acid or sulfonic acid modified white carbon black into a polymer membrane, and the methanol permeability is reduced at the same time, so that the sulfonated modified SWCB is an ideal filler for filling and modifying a proton exchange membrane.

The metal organic framework Material (MOF) is a novel material formed by self-assembly of central metal ions and organic ligands, and has the characteristics of adjustable structure, high porosity, large specific surface area and convenient functionalization. Among them, Zeolite Imidazolate Frameworks (ZIFs) based on imidazolate rings to which tetrahedral divalent metal cations are coordinated are used as fillers in composite polymer electrolyte membranes due to their characteristics in proton transport. However, the prior art discloses that MOF materials used as proton exchange membrane fillers must be stable in acidic environment, but zinc-based ZIF MOF materials are difficult to apply to proton exchange membranes due to poor stability in acidic environment, which greatly limits the application of zinc-based ZIF materials in proton exchange membranes. Therefore, the unstable characteristic of the ZIF material under the acidic condition is an urgent problem to be solved while utilizing the advantages of the ZIF material of high specific surface area and easy functionalization. Aiming at the technical problems of high methanol permeability and low proton conductivity of the SPEEK proton exchange membrane in the prior art and the unstable characteristic of the ZIF material under the acidic condition, the application of the ZIF material in the proton exchange membrane is limited, so that a new proton exchange membrane needs to be developed.

Disclosure of Invention

In order to overcome the problems of high methanol permeability and low proton conductivity of a SPEEK proton exchange membrane and instability of a ZIF material under an acidic condition in the prior art, the invention aims to provide the proton exchange membrane with low methanol permeability and high proton conductivity; the second purpose of the invention is to provide a preparation method of the proton exchange membrane; the invention also aims to provide the application of the proton exchange membrane.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

in a first aspect, the present invention provides a composite proton exchange membrane comprising a matrix and a filler; the matrix comprises sulfonated polyetheretherketone; the filler comprises a sulfonated ZIF-derived porous carbon material.

Preferably, the mass ratio of the sulfonated polyether ether ketone to the sulfonated ZIF derived porous carbon material is (10-100): 1; further preferably, the mass ratio of the sulfonated polyether ether ketone to the sulfonated ZIF-derived porous carbon material is (11-99): 1.

preferably, the sulfonated polyether ether ketone contains a repeating unit shown as a formula (I);

in the formula (I), x is selected from a positive integer of 5-50, y is selected from a positive integer of 20-60, and y/x is selected from 0.8-5; further preferably, in formula (I), x is a positive integer from 10 to 40, y is a positive integer from 30 to 50, and y/x is from 1 to 4.

Preferably, the sulfonated ZIF-derived porous carbon material is prepared by a preparation method comprising the following steps:

1) mixing dimethyl imidazole and zinc salt, and reacting to obtain a zinc-based ZIF material;

2) calcining a zinc-based ZIF material in an inert atmosphere or in vacuum to obtain a ZIF-derived porous carbon material;

3) mixing the ZIF-derived porous carbon material with a mercapto-containing silane coupling agent to obtain a mercapto-silane-grafted ZIF-derived porous carbon material;

4) oxidizing the ZIF-derived porous carbon material grafted by mercaptosilane to obtain the sulfonated ZIF-derived porous carbon material.

Preferably, the molar ratio of the dimethyl imidazole to the zinc salt is (5-12): 1; further preferably, the molar ratio of the dimethylimidazole to the zinc salt is (6-10): 1.

preferably, the zinc salt comprises at least one of zinc nitrate, zinc acetate and zinc chloride; further preferably, the zinc salt is zinc nitrate.

Preferably, in the step 3), the mass ratio of the ZIF-derived porous carbon material to the mercapto group-containing silane coupling agent is 1: (10-30); further preferably, in the step 3), the mass ratio of the ZIF-derived porous carbon material to the mercapto group-containing silane coupling agent is 1: (12-20).

Preferably, the particle size of the sulfonated ZIF-derived porous carbon material is 70nm to 220 nm; further preferably, the particle size of the sulfonated ZIF-derived porous carbon material is 80nm to 200 nm.

Preferably, the sulfonated ZIF-derived porous carbon material has an average particle size of 120nm to 140 nm; further preferably, the sulfonated ZIF-derived porous carbon material has an average particle size of 120nm to 130 nm.

Preferably, the temperature of the calcination is 800 ℃ to 1000 ℃.

Preferably, the calcination time is 2h to 4 h.

Preferably, the filler further comprises sulfonated white carbon black.

Preferably, the mass ratio of the sulfonated polyether ether ketone to the sulfonated ZIF derived porous carbon material to the sulfonated white carbon black is (30-32): 1: (0.3-3); further preferably, the mass ratio of the sulfonated polyether ether ketone to the sulfonated ZIF derived porous carbon material to the sulfonated white carbon black is (31-32): 1: (0.3-2).

Preferably, the sulfonated white carbon black is prepared by a preparation method comprising the following steps:

1) mixing the white carbon black with a silane coupling agent containing sulfydryl to obtain sulfydryl silane grafted white carbon black;

2) oxidizing the white carbon black grafted by mercaptosilane to obtain the sulfonated white carbon black.

Preferably, the mass ratio of the white carbon black to the mercapto-containing silane coupling agent is 1: (5-30).

Preferably, the average particle size of the sulfonated white carbon black is 15nm-25 nm.

Preferably, the thickness of the composite proton exchange membrane is 80-120 μm; more preferably, the thickness of the composite proton exchange membrane is 90-110 μm.

Preferably, the methanol permeability of the composite proton exchange membrane is 3 x 10 ^-7 cm ² s ^-1 -6×10 ^-7 cm ² s ^-1 (ii) a More preferably, the methanol permeability of the composite proton exchange membrane is 3.07 x 10 ^-7 cm ² s ^-1 -5.98×10 ^-7 cm ² s ^-1 。

Preferably, the proton conductivity of the composite proton exchange membrane at 20 ℃ is 0.046mScm ^-1 -0.058mScm ^-1 。

Preferably, the proton conductivity of the composite proton exchange membrane at 40 ℃ is 0.064mScm ^-1 -0.085mScm ^-1 。

Preferably, the proton conductivity of the composite proton exchange membrane at 60 ℃ is 0.13mScm ^-1 -0.17mScm ^-1 。

In a second aspect, the present invention provides a method for preparing a composite proton exchange membrane according to the first aspect of the present invention, comprising the following steps:

mixing the components, and drying to obtain the composite proton exchange membrane.

Preferably, the solvent of the mixing step includes at least one of dimethyl sulfoxide, N-dimethylformamide, N-methylpyrrolidone, and N, N-dimethylacetamide; further preferably, the solvent of the mixing step includes at least one of N, N-dimethylformamide and N, N-dimethylacetamide.

Preferably, the drying step includes primary drying and secondary drying.

Preferably, the temperature of the primary drying is 60-80 ℃.

Preferably, the time for primary drying is 6h-24 h.

Preferably, the temperature of the secondary drying is 90-150 ℃.

Preferably, the time for the secondary drying is 6h-24 h.

In a third aspect, the present invention provides the use of a composite proton exchange membrane according to the first aspect of the present invention in a fuel cell.

The invention has the beneficial effects that:

the composite proton exchange membrane provided by the invention has the advantages of low methanol permeability and high proton conductivity, and the proton conductivity of the composite proton exchange membrane can be improved and the permeation of fuel can be blocked by filling the sulfonated ZIF derived porous carbon material; according to the invention, the zinc-based ZIF is carbonized, so that the defect of instability in an acidic environment is overcome, and the zinc-based ZIF is suitable for preparing a composite proton exchange membrane; the preparation method of the composite proton exchange membrane is simple and efficient, has low cost and has the advantage of industrial production; the composite proton exchange membrane can be widely applied to fuel cells.

Specifically, the invention has the following advantages:

1. the sulfonated ZIF-derived porous carbon material filled with the composite proton exchange membrane can greatly improve the proton conductivity of the composite membrane, and simultaneously solves the problem that the ZIF material is unstable in an acidic environment; the sulfonated white carbon black is an ideal filler capable of effectively inhibiting methanol permeation of a proton exchange membrane, and when the sulfonated white carbon black and a sulfonated ZIF derived porous carbon material are filled into a SPEEK matrix together, a high-efficiency proton transmission network can be established in the composite proton exchange membrane, so that the proton conductivity of the composite membrane is improved, the permeation of fuel is blocked, and the problems of low proton conductivity and high methanol permeability of a pure SPEEK membrane are effectively solved.

2. The sulfonated polyether ether ketone used in the invention is used as the matrix of the proton exchange membrane, and has the advantages of low cost and simple synthesis; the zinc-based ZIF used in the invention has uniform particle size and controllable particle size, and the prepared ZIF-derived porous carbon material has the advantages of uniform particle size, large specific surface area and easy functionalization; by carbonizing the zinc-based ZIF, the defect of instability in an acidic environment is overcome, and the zinc-based ZIF is suitable for preparing a composite proton exchange membrane.

Drawings

FIG. 1 is a flow chart of the preparation of sulfonated polyetheretherketone.

FIG. 2 is a flow chart of the preparation of sulfonated white carbon black.

FIG. 3 is a flow chart of the preparation of sulfonated ZIF derived porous carbon materials.

FIG. 4 is a nuclear magnetic resonance hydrogen spectrum of sulfonated polyetheretherketone.

Fig. 5 is an SEM image of sulfonated ZIF-derived porous carbon material.

Fig. 6 is a particle size distribution diagram of a sulfonated ZIF-derived porous carbon material.

FIG. 7 is a TEM test chart of sulfonated silica.

FIG. 8 is a particle size distribution diagram of sulfonated white carbon black.

FIG. 9 is a SEM image of the surface of a composite proton exchange membrane prepared in example 5.

Figure 10 is a high-magnification cross-sectional SEM image of the composite proton exchange membrane prepared in example 5.

Figure 11 is a cross-sectional SEM image of a composite proton exchange membrane prepared in example 5.

FIG. 12 is a photograph of an embodiment of the composite proton exchange membrane prepared in example 5.

Detailed Description

The following examples are presented to further illustrate the practice of the invention, but the practice and protection of the invention is not limited thereto. It is noted that the processes described below, if not specifically described in detail, are all realizable or understandable by those skilled in the art with reference to the prior art. The reagents or apparatus used are not indicated to the manufacturer, and are considered to be conventional products available through commercial purchase.

The preparation method of the sulfonated polyether ether ketone comprises the following steps: polyetheretherketone (PEEK) (molecular weight: 4000-21800) was dried in a vacuum oven at 80 ℃ for 24 hours. A reaction flask was assembled in a water bath apparatus, 100mL of 98% concentrated sulfuric acid was added, and 5g of dried PEEK was dissolved in the concentrated sulfuric acid with stirring. The reaction was carried out for 3 hours at 50 ℃ with vigorous stirring. A large amount of ice-water mixed liquid is prepared in advance, and after the reaction is finished, a sulfuric acid solution of sulfonated polyether ether ketone (SPEEK) is slowly poured into ice water under mechanical stirring to be pulled into filaments. Washing with pure water for several times to neutral, filtering to collect SPEEK, and drying in oven at 60 deg.C for 24 hr to obtain sulfonated polyether ether ketone with sulfonation degree of 50-80% (sulfonation degree is obtained according to published literature). FIG. 1 is a flow chart of the preparation of sulfonated polyetheretherketone.

The preparation steps of the sulfonated white carbon black are as follows: commercially available White Carbon Black (WCB) (available from Michelin reagent official network, model S861577, specification 99.5%, 20 + -5 nm) was mixed with ethanol and 3-mercaptopropyltrimethoxysilane in a ratio of 1:70:15, and mixing. The resulting mixture is reacted at 80 ℃ to 120 ℃ under reflux for 2 to 24 hours. After the reaction, a mercaptosilane-grafted WCB (WCB-SH) was obtained by filtration. Using hydrogen peroxide (H) ₂ O ₂ ) The solution is used as an oxidant to oxidize the mercapto (-SH) functional group of WCB-SH into a sulfonate (-SO) ₃ H) And obtaining the Sulfonated White Carbon Black (SWCB). FIG. 2 is a flow chart of the preparation of sulfonated white carbon black.

Sulfonated ZIF-derived porous carbon material (C-ZIF-SO) ₃ H) The preparation steps are as follows:

1) preparation of zinc-based ZIF: the dimethylimidazole and zinc nitrate hexahydrate are dissolved in 100mL-150mL of methanol respectively, and after complete dissolution, the methanol solution containing dimethylimidazole is poured into the zinc nitrate solution rapidly with stirring. The resulting mixed solution was vigorously stirred for 5 to 10 minutes and then allowed to stand for 1 to 2 hours. After the reaction was completed, the product was separated by a centrifuge and washed with methanol. And (3) drying the product in an oven at 60-100 ℃ to obtain the zinc-based ZIF material (ZIF-8).

2) Preparation of ZIF-derived porous carbon material: and (3) placing the obtained zinc-based ZIF material (ZIF-8) in a tube furnace, and calcining for 2-4 hours at the temperature of 800-1000 ℃ in a nitrogen atmosphere to obtain the ZIF-derived carbon material (C-ZIF).

3) Sulfonated ZIF-derived porous carbon materials (C-ZIF-SO) ₃ H) The preparation of (1): will be provided withThe above-obtained ZIF-derived carbon material (C-ZIF) was mixed with toluene and 3-mercaptopropyltrimethoxysilane in a mass ratio of 1:70: 15. Preparing into uniform mixed liquid under the action of ultrasonic wave. The mixed liquid thus produced was transferred to a condensing reflux reaction apparatus. Heat to 80 ℃ and reflux for 4 h. After the reaction was completed, the product was collected by filtration and washed several times with anhydrous ethanol to remove the residual silane. The product is mercaptosilane grafted C-ZIF (C-ZIF-SH). Dispersing the collected C-ZIF-SH in 30% H under the action of ultrasound ₂ O ₂ And reacting in the solution for 5 hours at normal temperature under the stirring action. H ₂ O ₂ The solution is used as an oxidant for oxidizing-SH functional groups in C-ZIF-SH to sulfonate (-SO) ₃ H) To obtain the sulfonated ZIF derived porous carbon material (C-ZIF-SO) ₃ H) The product is obtained by filtration, washed and filtered several times with ethanol and water, and finally dried in an oven for use. FIG. 3 is a flow chart of the preparation of sulfonated ZIF derived porous carbon materials.

Example 1

The preparation steps of the composite proton exchange membrane are as follows:

1) first, a SPEEK solution in N, N-Dimethylacetamide (DMAC) is prepared, and the prepared SPEEK is dissolved in DMAC solution, usually 10 mL/g of SPEEK in DMAC solution.

2) Adding C-ZIF-SO with the aid of ultrasound ₃ H is dispersed in DMAC solution to form a homogeneous mixture, usually per 100mg of C-ZIF-SO ₃ H10 mL DMAC solution was used.

3) Collecting the SPEEK solution and C-ZIF-SO ₃ The H dispersion was mixed with stirring and further mixed well under the action of ultrasound. SPEEK and C-ZIF-SO ₃ The mass ratio of H is 1: 99. After obtaining a homogeneous solution, it was cast onto a glass plate and dried continuously using a vacuum oven at 80 ℃ for 12 h. Subsequently, the membrane was further dried at 100 ℃ for 12h to further remove the residual DMAC solution. Finally, the C-ZIF-SO with the filling mass percentage of 1.0 percent is obtained ₃ H SPEEK composite proton exchange membrane, noted as C-ZIF-SO ₃ H _1.0 wt.% @ SPEEK. The thickness of the film is about 100 μm.

Example 2

The preparation steps of the composite proton exchange membrane are as follows:

3) Collecting the SPEEK solution and C-ZIF-SO ₃ The H dispersion was mixed with stirring and further mixed well under the action of ultrasound. SPEEK and C-ZIF-SO ₃ The mass ratio of H is 3: 97. After obtaining a homogeneous solution, it was cast onto a glass plate and dried continuously for 12h at 80 ℃ using a vacuum oven. Subsequently, the membrane was further dried at 100 ℃ for 12h to further remove the residual DMAC solution. Finally, the C-ZIF-SO with the filling mass percentage of 1.0 percent is obtained ₃ H, SPEEK composite proton exchange membrane, marked as C-ZIF-SO ₃ H — 3.0 wt.% @ SPEEK. The thickness of the film is about 100 μm.

Example 3

The preparation steps of the composite proton exchange membrane are as follows:

3) Collecting the SPEEK solution and C-ZIF-SO ₃ The H dispersion was mixed with stirring and further mixed well under the action of ultrasound. SPEEK and C-ZIF-SO ₃ The mass ratio of H is 5: 95. After obtaining a homogeneous solution, it was cast onto a glass plate and dried continuously using a vacuum oven at 80 ℃ for 12 h. Subsequently, the membrane was further dried at 100 ℃ for 12h to further remove the residual DMAC solution. Finally, the C-ZIF-SO with the filling mass percentage of 5.0 percent is obtained ₃ SPEEK complexes of HProton exchange Membrane, denoted C-ZIF-SO ₃ H — 5.0 wt.% @ SPEEK. The thickness of the film is about 100 μm.

Example 4

The preparation steps of the composite proton exchange membrane are as follows:

3) Collecting the SPEEK solution and C-ZIF-SO ₃ The H dispersion was mixed with stirring and further mixed well under the action of ultrasound. SPEEK and C-ZIF-SO ₃ The mass ratio of H is 7: 93. After obtaining a homogeneous solution, it was cast onto a glass plate and dried continuously using a vacuum oven at 80 ℃ for 12 h. Subsequently, the membrane was further dried at 100 ℃ for 12h to further remove the residual DMAC solution. Finally, C-ZIF-SO with the filling mass percentage of 7.0 percent is obtained ₃ H, SPEEK composite proton exchange membrane, marked as C-ZIF-SO ₃ H — 7.0 wt.% @ SPEEK. The thickness of the film is about 100 μm.

Example 5

The preparation steps of the composite proton exchange membrane are as follows:

sulfonated ZIF-derived porous carbon material (C-ZIF-SO) ₃ H) Preparation of SPEEK composite proton exchange membrane co-filled with Sulfonated White Carbon Black (SWCB):

3) The SWCB is dispersed in DMAC solution with the aid of sonication to form a homogeneous mixture, typically 10mL of DMAC solution per 100mg of SWCB.

4) Collecting the SPEEK solution, and adding C-ZIF-SO ₃ The H dispersion and the SWCB dispersion were mixed with stirring and further mixed well under the action of ultrasound. SPEEK, C-ZIF-SO ₃ The mass ratio of H to SWCB was 96:3: 1. After obtaining a homogeneous solution, it was cast onto a glass plate and dried continuously using a vacuum oven at 80 ℃ for 12 h. Subsequently, the membrane was further dried at 100 ℃ for 12h to further remove the residual DMAC solution. Finally, 3.0 percent of C-ZIF-SO is obtained ₃ H and 3.0 mass percent SWCB co-filled SPEEK composite proton exchange membrane named as C-ZIF-SO ₃ H-3.0 wt.%/SWCB-1.0 wt.% @ SPEEK. The thickness of the film is about 100 μm.

Example 6

The sulfonated ZIF-derived porous carbon Material (C-ZIF-SO) of this example ₃ H) In the preparation step of the SPEEK composite proton exchange membrane co-filled with Sulfonated White Carbon Black (SWCB), SPEEK and C-ZIF-SO ₃ The mass ratios of H and SWCB were 94:3:3, respectively, and the rest of the procedure was the same as in example 5. The prepared composite proton exchange membrane is named as C-ZIF-SO ₃ H-3.0wt.％/SWCB-3.0wt.％@SPEEK。

Example 7

The sulfonated ZIF-derived porous carbon material (C-ZIF-SO) was prepared by ₃ H) In the preparation step of the SPEEK composite proton exchange membrane co-filled with Sulfonated White Carbon Black (SWCB), SPEEK and C-ZIF-SO ₃ The mass ratios of H and SWCB were 92:3:5, respectively, and the rest of the procedure was the same as in example 5. The prepared composite proton exchange membrane is named as C-ZIF-SO ₃ H-3.0wt.％/SWCB-5.0wt.％@SPEEK。

Example 8

The sulfonated ZIF-derived porous carbon Material (C-ZIF-SO) of this example ₃ H) In the preparation step of the SPEEK composite proton exchange membrane co-filled with Sulfonated White Carbon Black (SWCB), SPEEK and C-ZIF-SO ₃ The mass ratio of H and SWCB was 90:3:7, respectively, and the remaining steps were the same as in example 5. The prepared composite proton exchange membrane is named as C-ZIF-SO ₃ H-3.0wt.％/SWCB-7.0wt.％@SPEEK。

Comparative example 1

Preparation of SPEEK proton exchange membrane of this example:

2) The SPEEK solution obtained above was cast onto a glass plate and dried continuously for 12h at 80 ℃ using a vacuum oven. Subsequently, the membrane was further dried at 100 ℃ for 12h to further remove the residual DMAC solution. Finally obtaining the SPEEK proton exchange membrane. The thickness of the film is about 100 μm.

Performance test

The prepared sulfonated polyether ether ketone is subjected to nuclear magnetic resonance hydrogen spectrum test, and fig. 4 is a nuclear magnetic resonance hydrogen spectrum of the sulfonated polyether ether ketone. As can be seen from fig. 4, the sulfonated polyetheretherketone structure prepared in the examples is as follows;

the prepared sulfonated ZIF-derived porous carbon material is subjected to scanning electron microscope testing and particle size analysis (particle size is statistically analyzed according to SEM pictures), fig. 5 is an SEM image of the sulfonated ZIF-derived porous carbon material, and fig. 6 is a particle size distribution diagram of the sulfonated ZIF-derived porous carbon material. As can be seen from fig. 6, the average particle size of the sulfonated ZIF-derived porous carbon material was 127..6 nm.

The prepared sulfonated white carbon black is subjected to transmission electron microscope test and particle size analysis, fig. 7 is a TEM test picture of the sulfonated white carbon black, and fig. 8 is a particle size distribution diagram of the sulfonated white carbon black. As can be seen from FIG. 8, the average particle size of sulfonated white carbon black was 18.9 nm.

FIG. 9 is a SEM image of the surface of a composite proton exchange membrane prepared in example 5. FIG. 10 is a large-magnification SEM image of the cross section of the composite proton exchange membrane prepared in example 5. Figure 11 is a cross-sectional SEM image of a composite proton exchange membrane prepared in example 5. FIG. 12 is a photograph of an embodiment of the composite proton exchange membrane prepared in example 5.

The composite proton exchange membranes prepared in examples 1 to 8 and comparative example 1 were subjected to ion exchange capacity, water absorption and swelling rate, conductivity and methanol permeability tests, and the water absorption (WU%), swelling rate (SR%), Ion Exchange Capacity (IEC), conductivity and methanol permeability test methods were as follows:

the water absorption rate is the percentage of the mass difference of the full wet-state and dry-state membrane materials in the dry-state membrane material. Placing an acid type polymer membrane in distilled water, soaking for 24 hours at a set temperature, quickly wiping the surface water of the membrane to weigh when the water absorption rate and the water desorption rate of the membrane material reach balance, repeating the experiment for 3-5 times until the weight is a constant, and taking an average value as W _w Finally, drying the mixture in a vacuum oven at 100 ℃ for 24 hours, and weighing the dried mixture to obtain W _d . The water absorption value can be obtained from formula (1).

In formula (1): w _d Denotes the film weight (g), W in the dry state _w The weight of the film in the wet state (g) is shown.

And the swelling rate test is to soak the acid type polymer membrane in deionized water at a set temperature for 24 hours, quickly wipe dry the surface of the membrane when the water absorption rate and the water desorption rate of the membrane material reach balance, measure the size of the membrane, repeat the experiment for 3-5 times until the size of the membrane is a constant, and then place the membrane in a vacuum oven to be dried for 24 hours at 100 ℃ and measure the size of the membrane. The swelling ratio value can be obtained from formula (2).

In the formula (2), L _w And L _d The dimensions (cm) of the film were respectively in the fully wet state and in the fully dry state.

The ion exchange capacity reflects the proton group density in the proton exchange membrane, which is also one of the important indicators of the proton conductivity of the reaction membrane. The IEC of the membrane can be determined by acid-base titration. Putting the pretreated proton exchange membrane into a weighing bottle, drying the proton exchange membrane in a vacuum oven to constant weight, and accurately weighing the proton exchange membrane by using an analytical balance, wherein the dry weight of the membrane to be measured is that the plasma polymerization proton exchange membrane is put into 50mL of saturated NaCl solution to be soaked for 48 hours, so that H in the membrane ⁺ All are replaced. The membrane was removed and rinsed 3 times with deionized water, the rinsed water also being poured into the original NaCl solution. Then using phenolphthalein as an indicator, titrating to pink by using a previously calibrated NaOH solution with the concentration of about 0.01mol/L, and using phenolphthalein as an indicator. The Ion Exchange Capacity (IEC) calculated value can be obtained from equation (3).

Wherein, C _NaOH The concentration (mol/L) of the NaOH solution; v _NaOH Volume of NaOH solution consumed (mL); w is a group of _d Is the mass (g) of the dry proton exchange membrane.

The proton conductivity is the most important parameter of the performance of the reaction membrane, and the proton conductivity test of the proton exchange membrane adopts a three-electrode alternating current impedance test method. In this test, the horizontal proton transport rate of the membrane material was tested and analyzed using an electrochemical workstation of Solatron 1260. The film is first cut into a long strip (e.g., 1 cm. times.5 cm), the working electrode (WC) and the auxiliary electrode (CE) are connected to both ends in the longitudinal direction, respectively, and the Reference Electrode (RE) is connected to the central portion of the film, and the impedance of the film in the horizontal direction is measured. The impedance spectrum of the film was measured under the conditions of a frequency of 1MHz to 100MHz and an amplitude of 10mV, and the resistance value of the film was obtained by fitting. According to the membrane resistance (R) _res ) The proton conductivity of the membrane is calculated from the equation (4) by the distance (d) between the working electrode and the counter electrode and the cross-sectional area (S) of the membrane.

Methanol permeability (P) is one of the key parameters affecting membrane performance. The methanol permeability of the composite membrane is tested by adopting a three-electrode system of an electrochemical workstation (Shanghai CHI-760E), and three electrode systems of a Pt sheet, a saturated Ag/AgCl and a Pt/C gas diffusion electrode are respectively used as an auxiliary electrode, a reference electrode and a working electrode. The membrane to be tested is placed between the supply chamber and the receptor chamber and is fixedly sealed by a rubber ring. Of the film to be testedThe active area is about 1.70cm ² . 10 vt.% methanol and 0.5mol/L H ₂ SO ₄ The resulting solution was fed to a donor cell, 0.5mol/L H ₂ SO ₄ Are sent to a receiver chamber having the same volume of solution. In the experimental process, the solution in the two chambers is continuously stirred, and pure O ₂ Steadily and continuously passing near the working electrode. The permeation of methanol through the membrane is caused by the difference in methanol concentration on both sides, which results in a drop in the potential of the working electrode. The methanol concentration in the receptor compartment can then be determined from the calibration curve. Methanol permeability P (cm) ² S) is calculated from the equation of formula (5).

Wherein S represents the osmotically active area of the membrane and C _A And C _B Denotes the methanol concentration in the donor and acceptor compartments, V _B Represents the volume of the solution in the acceptor compartment and D represents the diffusion coefficient of methanol.

Table 1 shows the ion exchange capacity, water absorption and swelling ratio test data of the composite proton exchange membrane.

Table 1 ion exchange capacity, water absorption and swelling ratio test data for composite proton exchange membranes

As can be seen from Table 1, when C-ZIF-SO was filled ₃ When H is added to SPEEK matrix, C-ZIF-SO is added with the increase of filling amount ₃ Both the water absorption and swelling ratio of the H @ SPEEK film showed a decreasing trend. This is because the presence of inorganic particles occupies free space within the membrane and the interaction with the organic polymer matrix limits the free movement of the SPEEK molecular chains, thereby reducing the swelling ratio and water absorption of the composite membrane. This is favorable to improving the structural stability of the composite membrane under the high temperature and high humidity environment. When being filled with C-ZIF-SO ₃ On the basis of H, when the sulfonated white carbon black is continuously added, the water absorption rate and the swelling rate of the composite film are further reduced along with the increase of the content of the white carbon black filler. This is also because the more inorganic particles introduced into the membrane occupy more free space in the membrane to limit the free movement of the SPEEK polymer, which is advantageous for increasing the structural stability of the composite membrane under high temperature and high humidity environment. Whether C-ZIF-SO ₃ H, and also SWCB, the Ion Exchange Capacity (IEC) of the composite membrane all showed a tendency to decrease with increasing filler loading. This is because the filled inorganic particles dilute the local density of sulfonic acid groups in the composite membrane.

Table 2 shows conductivity and methanol permeability test data for the composite proton exchange membrane.

Table 2 conductivity and methanol permeability test data for composite proton exchange membranes

As can be seen from Table 2, with C-ZIF-SO ₃ Increased filling of H, C-ZIF-SO ₃ The proton conductivity of the H @ SPEEK membrane showed a tendency to increase first and then decrease, and at a loading of 3.0 wt.% (example 2), C-ZIF-SO ₃ The proton conductivity of the H @ SPEEK membrane reaches a maximum, much higher than the pure SPEEK membrane (comparative example 1). In SPEEK matrix, appropriate amount of C-ZIF-SO ₃ H (less than or equal to 3.0 wt.%) can reduce the swelling ratio of the membrane, so that the spacing distance between sulfonic acid groups is shortened, and continuous hydrophilic ion clusters are easier to form in a membrane water absorption state, thereby creating conditions for constructing continuous proton transmission channels in the membrane. Furthermore, C-ZIF-SO ₃ The rich pore structure of H and the hydrophilic sulfonic acid group on the surface are also favorable for constructing an additional proton transport channel, thereby improving the C-ZIF-SO ₃ Proton conductivity of H @ SPEEK membrane. When C-ZIF-SO ₃ Methanol permeability of H @ SPEEK membranes is the same as C-ZIF-SO ₃ The H filling rate is regulated to decrease and then increase, and the H filling rate reaches the lowest when the H filling rate reaches 3.0 wt%Values slightly lower than SPEEK membranes. This is due to the relatively SPEEK, dense C-ZIF-SO ₃ The H filler blocks the methanol permeation path, thereby inhibiting the methanol permeability of the composite membrane. The membrane is filled with excessive C-ZIF-SO ₃ H(>3.0 wt.%), C-ZIF-SO in the film ₃ H is agglomerated to destroy the compact structure of the membrane, so that the effective ion cluster structure is not favorably formed with the sulfonic acid group of SPEEK, and the proton conductivity of the composite membrane is reduced. When the filler is filled with 3.0 wt.% of C-ZIF-SO ₃ When the SWCB is further filled on the basis of the H, the proton conductivity of the composite membrane is slightly reduced along with the increase of the filling amount of the SWCB. But at the same time, the methanol permeability of the composite membrane is greatly reduced and reaches a minimum value at a filling amount of 3.0 wt.%, which is far lower than that of the SPEEK membrane. This indicates that SWCB filling can maintain high proton conductivity of the composite membrane while large size C-ZIF-SO ₃ The combination of the H particles and the small size SWCB particles can block the permeation of methanol, thereby greatly reducing the methanol permeability of the composite membrane. From the above results, it can be seen that the best embodiment of the present invention is the C-ZIF-SO of example 5 ₃ H-3.0 wt.%/SWCB-1.0 wt.% @ SPEEK membrane.

The mass ratio of C-ZIF to toluene and 3-mercaptopropyltrimethoxysilane in the above examples is not limited to 1:70:15, but may be other ratios, and a thiolated ZIF-derived porous carbon material may be obtained as well. The toluene solvent used may be replaced by other organic solvents such as ethanol, and should not be construed as limited to toluene.

The concentration of the hydrogen peroxide concentrated solution used in the above embodiment is not limited to 30%, and other concentrations of hydrogen peroxide concentrated solutions may be used.

The solvent used in the preparation of the SPEEK composite proton exchange membrane according to the above examples is not limited to N, N-dimethylacetamide, but an organic solvent capable of dissolving SPEEK, such as N, N-dimethylformamide or dimethylsulfoxide, may be used instead.

The above examples are preferred embodiments of the present invention, but the present invention is not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and they are included in the scope of the present invention.

Claims

1. A composite proton exchange membrane characterized by: the composite proton exchange membrane comprises a matrix and a filler; the matrix comprises sulfonated polyetheretherketone; the filler comprises a sulfonated ZIF-derived porous carbon material.

2. The composite proton exchange membrane according to claim 1 wherein: the mass ratio of the sulfonated polyether ether ketone to the sulfonated ZIF derived porous carbon material is (10-100): 1.

3. the composite proton exchange membrane according to claim 2 wherein: the sulfonated polyether ether ketone contains a repeating unit shown as a formula (I);

in the formula (I), x is selected from a positive integer of 5-50, y is selected from a positive integer of 20-60, and y/x is selected from 0.8-5.

4. The composite proton exchange membrane according to claim 2 wherein: the sulfonated ZIF-derived porous carbon material is prepared by a preparation method comprising the following steps of:

5. The composite proton exchange membrane according to any one of claims 1 to 4 wherein: the filler also comprises sulfonated white carbon black.

6. The composite proton exchange membrane according to claim 5 wherein: the mass ratio of the sulfonated polyether ether ketone to the sulfonated ZIF derived porous carbon material to the sulfonated white carbon black is (30-32): 1: (0.3-3).

7. The composite proton exchange membrane according to claim 6 wherein: the sulfonated white carbon black is prepared by the preparation method comprising the following steps:

2) and oxidizing the white carbon black grafted by the mercaptosilane to obtain the sulfonated white carbon black.

8. The composite proton exchange membrane according to any one of claims 1 to 7 wherein: the thickness of the composite proton exchange membrane is 80-120 μm.

9. A process for the preparation of a composite proton exchange membrane according to any one of claims 1 to 8, characterized in that: the method comprises the following steps:

10. Use of a composite proton exchange membrane according to any one of claims 1 to 8 in a fuel cell.