CN116970277A - Sulfonated polysulfone-based composite material and preparation method and application thereof - Google Patents

Abstract

The invention relates to the technical field of proton exchange membrane fuel cells, and particularly discloses a sulfonated polysulfone-based composite material and a preparation method and application thereof. The sulfonated polysulfone based composite includes sulfonated polysulfone to assemble at the sulfonic acid via intermolecular hydrogen bondingModifying black phosphorus on polysulfone molecules; the modified black phosphorus is diazonium salt modified black phosphorus; the diazonium salt is a diazonium sulfonate or diazonium carboxylate. The sulfonated polysulfone-based composite material provided by the invention has higher proton conductivity, lower fuel permeability and excellent stability, the proton exchange capacity can reach more than 1.2mmol/g, the proton conductivity can reach more than 0.076S/cm, and the methanol permeability is 8.1 multiplied by 10 ^{‑ 7} cm ² ·s ^‑1 The nano proton exchange membrane can be effectively replaced, and has wide application prospect in the field of fuel cells.

Description

A sulfonated polysulfone-based composite material and its preparation method and application

Technical field

The invention relates to the technical field of proton exchange membrane fuel cells, and in particular to a sulfonated polysulfone-based composite material and its preparation method and application.

Background technique

Proton exchange membrane fuel cell (PEMFC) is an energy conversion device that can directly convert chemical energy into electrical energy. As long as it is continuously supplied with oxidant and reducing agent, it can continuously output electrical energy because of its high battery energy efficiency, It has attracted widespread attention due to its good CO tolerance and simple water and heat management system. The key membrane electrode assembly of the proton exchange membrane fuel cell is composed of a gas diffusion layer, a catalyst layer and a proton exchange membrane. Among them, the main functions of the proton exchange membrane are proton conductivity, electronic insulation and flame retardant fuel penetration. At present, the widely commercialized proton exchange membrane for fuel cells is Nafion membrane. It has excellent thermal stability, chemical stability and good proton conductivity, and is currently the preferred membrane material for fuel cells. However, since Nafion is a perfluorinated proton exchange membrane, the preparation cost is high, and the proton conductivity becomes poor under conditions of low relative humidity and high temperature. At the same time, the proton exchange membrane also has fuel gas permeability when used in hydrogen fuel cells. These shortcomings are It seriously affects the application of proton exchange membranes in fuel cells.

Non-fluorine proton exchange membrane is a new technology proposed in recent years to replace the nafion series proton exchange membrane. It is a sulfonated polymer with a rigid main chain structure, such as sulfonated polyetheretherketone, sulfonated polysulfone, and sulfonated polyacyl. Imines, etc. have received full attention. However, the current main problem with non-fluorine proton exchange membranes is that it is difficult to form a microphase separation structure in the system, and it is easy to form a dead zone structure between hydrophilic and hydrophobic phases, resulting in poor proton conductivity. In order to construct a microphase separation structure in a non-fluorine proton exchange membrane system, currently, other positively charged or weakly positively charged compounds are generally blended with sulfonic acid groups to form acid-base ion pairs to reduce proton exchange caused by dehydration at high temperatures. Loss. However, proton exchange membranes have high requirements on membrane uniformity. Therefore, the compatibility of the blend material and the matrix material is also one of the important things to consider. In addition, proton exchange membranes also have high requirements for proton conductivity and gas barrier permeability. Therefore, how to prepare non-fluorine proton exchange membranes with high proton exchange properties, proton conductivity and fuel barrier properties, thereby improving the overall performance of fuel cells, has become an urgent problem to be solved.

Contents of the invention

Aiming at the problems that existing non-fluorine proton exchange membranes have existing problems such as proton exchange properties, electrical conductivity and fuel barrier properties that need to be further improved, the present invention provides a sulfonated polysulfone-based composite material and its preparation method and application.

In order to solve the above technical problems, the technical solution 1 provided by the embodiment of the present invention is:

A sulfonated polysulfone-based composite material, comprising sulfonated polysulfone and modified black phosphorus assembled on the sulfonated polysulfone molecules through intermolecular hydrogen bonds;

Wherein, the modified black phosphorus is diazonium salt modified black phosphorus; the diazonium salt is diazosulfonate or diazocarboxylate.

Compared with the existing technology, the sulfonated polysulfone-based composite material provided by the present invention introduces black phosphorus material into the sulfonated polysulfone matrix. The lamellar structure of black phosphorus can build a continuous proton transfer channel in the sulfonated polysulfone membrane. , improve proton conductivity, and the lone pair of electrons in black phosphorus has strong nucleophilicity, which can have a strong interaction with the H ⁺ produced by membrane electrode catalysis, thereby allowing the proton exchange membrane to combine with more H ⁺ , further Improve proton conductivity; further, the present invention uses diazonium salts containing sulfonic acid groups or carboxyl groups to modify black phosphorus, and introduces sulfonic acid groups or carboxyl groups into the black phosphorus molecular chain. The modified black phosphorus not only interacts with sulfonic acid groups but also The sulfonated polysulfone has better compatibility and can be well dispersed in the sulfonated polysulfone matrix, thereby enhancing the stability of the proton exchange membrane; more importantly, it increases the proton groups in the sulfonated polysulfone, and The sulfonic acid group or carboxyl group in black phosphorus and the sulfonic acid group in sulfonated polysulfone form a continuous proton transport network through hydrogen bonding, which significantly improves the proton conductivity of sulfonated polysulfone. In addition, through hydrogen bonding, The introduction of black phosphorus containing sulfonic acid groups or carboxyl groups into the sulfonated polysulfone molecular chain increases the stacking density of the sulfonated polysulfone molecular chain, making the molecular chains stack more closely. In conjunction with the two-dimensional lamellar structure of black phosphorus, it significantly improves The fuel barrier properties of proton exchange membranes have broad application prospects in the field of proton exchange membrane fuel cells.

Further, the diazonium salt is 4-diazobenzenesulfonic acid, 3-diazobenzenesulfonic acid, 4-diazobenzenesulfonic acid fluoroborate, 4-diazobenzoic acid, 3-diazobenzoic acid Or at least one of 6-nitro-1-diazo-2-naphthol-4-sulfonic acid.

Taking 4-diazobenzenesulfonic acid as an example, the reaction equation for modified black phosphorus is as follows:

Modification of black phosphorus by preferred diazoates can enhance the compatibility between black phosphorus and sulfonated polysulfone, and can also increase the tightness of the molecular chain stacking of sulfonated polysulfone. The density of protons in sulfone significantly improves the proton conductivity, fuel barrier and mechanical stability of the sulfonated polysulfone membrane.

In a second aspect, the invention also provides a method for preparing sulfonated polysulfone-based composite materials, which includes the following steps:

Step 1: Disperse black phosphorus in an organic solvent to obtain a black phosphorus dispersion;

Dissolve polysulfone in an organic solvent to obtain a polysulfone solution;

Mix the black phosphorus dispersion liquid and the polysulfone solution evenly to obtain a mixed solution;

Step 2: Add a sulfonating agent to the mixed solution to perform a sulfonation reaction, then add a diazonium salt, and react at 0°C-20°C for 0.5h-10h. After the reaction, add a precipitant to the reaction system and separate the solid and liquid. , washed and dried to obtain sulfonated polysulfone-based composite material. The reaction equation is as follows:

Among them, .

It should be noted that a hydrogen bond is formed between the sulfonic acid group in X and the sulfonic acid group in the sulfonated polysulfone.

Compared with the existing technology, the preparation method of sulfonated polysulfone-based composite materials provided by the present invention is a one-pot synthesis of black phosphorus modification and polysulfone sulfonation, which is beneficial to the sulfonation of modified black phosphorus and sulfonated polysulfone. The acid groups are combined, thereby improving the uniformity of black phosphorus in sulfonated polysulfone and avoiding the problem of performance degradation of sulfonated polysulfone materials caused by direct doping of black phosphorus materials. Through the combination of modified black phosphorus and sulfonated polysulfone The synergistic effect achieves the purpose of simultaneously improving proton conductivity, fuel barrier properties and stability.

Further, in step one, the concentration of the black phosphorus dispersion is 0.1wt%-2wt%.

Further, in step one, the concentration of the polysulfone solution is 1wt%-20wt%.

Further, in step one, the mass ratio of black phosphorus and polysulfone is 1:10-100.

Further, in step one, the organic solvent is at least one of concentrated sulfuric acid, N-methylpyrrolidone, methylene chloride or ethyl chloride.

Further, in step two, the sulfonating agent is at least one of concentrated sulfuric acid, fuming sulfuric acid or chlorosulfonic acid.

Further, in step two, the temperature of the sulfonation reaction is 0°C-5°C, and the reaction time is 1h-2h.

Further, in step two, the precipitating agent is at least one of water, methanol or ethanol.

For example, in step 2, the volume ratio of the reaction solution to the precipitant is 1:5-30.

Further, the mass ratio of the sulfonating agent to polysulfone is 1:0.5-10.

Further, the mass ratio of the modifier to black phosphorus is 1:0.5-10.

The preparation method of the sulfonated polysulfone-based composite material provided by the invention has easy-to-obtain raw materials and a simple process. The prepared sulfonated polysulfone-based composite material has good uniformity and low cost, and can easily realize the production of the sulfonated polysulfone-based composite material. Large-scale production, and the prepared sulfonated polysulfone-based composite material has good proton conductivity and excellent fuel barrier properties. It can effectively replace the nafion series proton exchange membrane and has broad application prospects in the field of fuel cells.

In a third aspect, the present invention also provides the application of the above-mentioned sulfonated polysulfone-based composite material in a proton exchange membrane fuel cell.

A proton exchange membrane: including the above-mentioned sulfonated polysulfone-based composite material.

Exemplarily, the preparation method of the above-mentioned proton exchange membrane includes the following steps:

The above sulfonated polysulfone-based composite material is dispersed in a solvent, then poured into a polytetrafluoroethylene mold and dried to obtain a proton exchange membrane.

As a specific embodiment of the present invention, N-methylpyrrolidone can be used as the above solvent, with a concentration of 8wt%-12wt%.

Specifically, the drying temperature is 90°C-110°C, and the drying time is 20h-25h.

A fuel cell membrane electrode includes the above-mentioned proton exchange membrane.

A proton exchange membrane fuel cell includes the above-mentioned fuel cell membrane electrode.

The sulfonated polysulfone-based composite material provided by the invention has high proton conductivity, low fuel permeability and excellent stability. The proton exchange capacity can reach more than 1.2mmol/g, and the proton conductivity can reach 0.076S. /cm and above, and the methanol permeability is below 8.1×10 ^-7 cm ² ·s ^-1 . It has broad application prospects in the field of proton exchange membrane fuel cells.

Description of the drawings

Figure 1 is an infrared spectrum of the sulfonated polysulfone-based composite material prepared in Example 1 of the present invention;

Figure 2 is a schematic diagram of an H-type electrolytic cell for testing methanol permeability according to an embodiment of the present invention.

Detailed ways

In order to make the purpose, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with examples. It should be understood that the specific embodiments described here are only used to explain the present invention and are not intended to limit the present invention.

In order to better illustrate the present invention, further examples are provided below.

Example 1

The embodiment of the present invention provides a method for preparing a sulfonated polysulfone-based composite material, which includes the following steps:

S1, add 0.1g black phosphorus and 10mL N-methylpyrrolidone into a three-necked bottle, and conduct ultrasonic treatment for 0.5h under the conditions of 10Hz and 100W to obtain a black phosphorus dispersion;

S2, dissolve 2.0g polysulfone in 20mL N-methylpyrrolidone to obtain a polysulfone solution;

S3, mix the above-mentioned black phosphorus dispersion liquid and polysulfone solution evenly to obtain a mixed solution;

S4, add the mixed solution to the water bath, control the temperature to 5°C, add 2mL of chlorosulfonic acid, react for 1 hour, then add 0.1g of 4-diazobenzenesulfonic acid, continue the reaction at 5°C for 3 hours, and then pour the reaction solution into the deionized In water, filter, wash and dry to obtain sulfonated polysulfone-based composite material.

The infrared spectrum of the sulfonated polysulfone-based composite material prepared in this example is shown in Figure 1.

Example 2

The embodiment of the present invention provides a method for preparing a sulfonated polysulfone-based composite material, which includes the following steps:

S1, add 0.1g black phosphorus and 10mL ethyl chloride into a three-necked flask, and ultrasonic treat it for 0.5h under the conditions of 10Hz and 100W to obtain a black phosphorus dispersion;

S2, dissolve 1.0g polysulfone in 20mL ethyl chloride to obtain a polysulfone solution;

S3, mix the above-mentioned black phosphorus dispersion liquid and polysulfone solution evenly to obtain a mixed solution;

S4, add the mixed solution into the water bath, control the temperature at 5°C, add 5mL of chlorosulfonic acid, react for 1 hour, then add 0.3g of 6-nitro-1-diazo-2-naphthol-4-sulfonic acid, and heat at 5°C Continue the reaction for 3 hours, then pour the reaction solution into deionized water, filter, wash, and dry to obtain a sulfonated polysulfone-based composite material.

Example 3

The embodiment of the present invention provides a method for preparing a sulfonated polysulfone-based composite material, which includes the following steps:

S1, add 0.1g black phosphorus and 5mL concentrated sulfuric acid into a three-necked flask, and ultrasonically treat it for 0.5h under conditions of 10Hz and 100W to obtain a black phosphorus dispersion;

S2, dissolve 4.0g polysulfone in 20mL concentrated sulfuric acid to obtain a polysulfone solution;

S3, mix the above-mentioned black phosphorus dispersion liquid and polysulfone solution evenly to obtain a mixed solution;

S4, add the mixed solution to the water bath, control the temperature to 5°C, add 2 mL of fuming sulfuric acid, react for 1 hour, then add 0.1g of 4-diazobenzene sulfonate fluoroborate, continue the reaction at 5°C for 3 hours, and then add the reaction solution Pour into deionized water, filter, wash and dry to obtain sulfonated polysulfone-based composite material.

Example 4

The embodiment of the present invention provides a method for preparing a sulfonated polysulfone-based composite material, which includes the following steps:

S1, add 0.02g black phosphorus and 10mL methylene chloride into a three-necked flask, and ultrasonically treat it for 0.5h under conditions of 10Hz and 100W to obtain a black phosphorus dispersion;

S2, dissolve 2.0g polysulfone in 20mL methylene chloride to obtain a polysulfone solution;

S3, mix the above-mentioned black phosphorus dispersion liquid and polysulfone solution evenly to obtain a mixed solution;

S4, add the mixed solution to the water bath, control the temperature to 5°C, add 2mL of chlorosulfonic acid, react for 1 hour, then add 0.1g 4-diazobenzoic acid, continue the reaction at 5°C for 3 hours, and then pour the reaction solution into deionized water. , filter, wash and dry to obtain sulfonated polysulfone-based composite material.

Comparative example 1

This comparative example provides a preparation method of sulfonated polysulfone, which includes the following steps:

S1, dissolve 2.0g polysulfone in 20mL N-methylpyrrolidone to obtain a polysulfone solution;

S2, add the polysulfone solution into the water bath, control the temperature to 5°C, add 2 mL of chlorosulfonic acid, react for 1 hour, then pour the reaction solution into deionized water, filter, wash, and dry to obtain sulfonated polysulfone.

Comparative example 2

This comparative example provides a method for preparing sulfonated polysulfone-based composite materials, including the following steps:

S1, add 0.1g black phosphorus and 10mL N-methylpyrrolidone into a three-necked bottle, and conduct ultrasonic treatment for 0.5h under the conditions of 10Hz and 100W to obtain a black phosphorus dispersion;

S2, dissolve 2.0g polysulfone in 20mL N-methylpyrrolidone to obtain a polysulfone solution;

S3, mix the above-mentioned black phosphorus dispersion liquid and polysulfone solution evenly to obtain a mixed solution;

S4, add the mixed solution to the water bath, control the temperature to 5°C, add 2 mL of chlorosulfonic acid, and react for 1 hour. Then pour the reaction solution into deionized water, filter, wash, and dry to obtain a sulfonated polysulfone-based composite material.

Performance Testing

The sulfonated polysulfone-based composite materials prepared in the above-mentioned Examples 1-4, the sulfonated polysulfone-based composite material prepared in Comparative Example 1, and the sulfonated polysulfone-based composite material prepared in Comparative Example 2 were respectively dispersed in N-methylpyrrolidone, A dispersion with a mass concentration of 10 wt% was prepared. Each dispersion was poured into a polytetrafluoroethylene mold and dried at 100°C for 24 hours to obtain the corresponding proton exchange membrane.

(1)Proton exchange capacity (IEC) test

Approximately 0.5g of the proton exchange membrane was dried under vacuum at 80°C for 10 hours and then weighed, recorded as M (g). Then the proton exchange membrane was placed in 30mL of sealed 1mo/L sodium chloride solution and soaked at 25°C for 24h. , add 1-2 drops of phenolphthalein as an indicator, and titrate with a sodium hydroxide solution with a concentration of 0.01mol/L (C _NaOH ). When the solution appears pink and does not fade for 30 seconds, record the volume of the sodium hydroxide solution consumed at this time. V _NaOH (mL), and then calculate the proton exchange capacity (IEC) by the following formula:

(2)Proton conductivity

Cut the proton exchange membrane into 1cm×3cm strips, measure the width W (cm) and thickness D (cm) of the dry strips, soak the strips in 0.5 mol/L sulfuric acid solution for 6 hours, and wash with deionized water. to neutral, then place the spline on two parallel platinum electrodes with a distance of L (cm), and use an electrochemical workstation to measure the impedance R (Ω) of the film between the platinum electrodes. The measurement temperature is 70°C, and the proton conductivity σ ( S/cm) is calculated by the following formula:

(3) Methanol permeability

The methanol permeability was tested using cyclic voltammetry. The proton exchange membrane was placed in an H-type electrolytic cell, as shown in Figure 2, and the cyclic voltammetry test was performed. The calculation formula for methanol permeability (P _CH3OH ) is as follows:

In the formula, P _CH3OH is the methanol permeability (cm ² ·s ^-1 ); C _A and C _B represent the methanol concentration (mol/L) of pool A and pool B respectively, where the initial concentration of methanol in pool A is 5 mol /L, the methanol concentration in Pool B is the concentration of methanol on the permeate side at a certain moment (mol/L), which can be calculated through the relationship between the standard methanol concentration and the current value of the cyclic voltammetry oxidation peak; V _B represents the solution in Pool B The volume (L); L represents the effective penetration area of the membrane 4.9cm ² ; t is the penetration time (s).

The results are shown in Table 1.

Table 1

To sum up, the sulfonated polysulfone-based composite material in the embodiments of the present invention has excellent proton conductivity and fuel barrier properties, can be used as a material for preparing proton exchange membranes, and has broad application prospects in the field of fuel cells.

The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions or improvements made within the spirit and principles of the present invention shall be included in the protection of the present invention. within the range.

Claims (10)

1. A sulfonated polysulfone-based composite material, characterized in that it includes sulfonated polysulfone and modified black phosphorus assembled on the sulfonated polysulfone molecules through intermolecular hydrogen bonds; Wherein, the modified black phosphorus is diazonium salt modified black phosphorus; the diazonium salt is diazosulfonate or diazocarboxylate. 2. The sulfonated polysulfone-based composite material as claimed in claim 1, wherein the diazonium salt is 4-diazobenzenesulfonic acid, 3-diazobenzenesulfonic acid, or 4-diazobenzenesulfonic acid. At least one of fluoroborate, 4-diazobenzoic acid, 3-diazobenzoic acid or 6-nitro-1-diazo-2-naphthol-4-sulfonic acid. 3. The preparation method of the sulfonated polysulfone-based composite material according to claim 1 or 2, characterized in that it includes the following steps: Step 1: Disperse black phosphorus in an organic solvent to obtain a black phosphorus dispersion; Dissolve polysulfone in an organic solvent to obtain a polysulfone solution; Mix the black phosphorus dispersion liquid and the polysulfone solution evenly to obtain a mixed solution; Step 2: Add a sulfonating agent to the mixed solution to perform a sulfonation reaction, then add a diazonium salt, and react at 0°C-20°C for 0.5h-10h. After the reaction, add a precipitant to the reaction system and separate the solid and liquid. , washed and dried to obtain sulfonated polysulfone-based composite material. 4. The preparation method of sulfonated polysulfone-based composite materials as claimed in claim 3, characterized in that, in step one, the concentration of the black phosphorus dispersion is 0.1wt%-2wt%; and/or In step one, the concentration of the polysulfone solution is 1wt%-20wt%. 5. The preparation method of sulfonated polysulfone-based composite materials as claimed in claim 3, characterized in that, in step one, the mass ratio of black phosphorus and polysulfone is 1:10-100; and/or In step one, the organic solvent is at least one of concentrated sulfuric acid, N-methylpyrrolidone, methylene chloride or ethyl chloride. 6. The preparation method of sulfonated polysulfone-based composite materials as claimed in claim 3, characterized in that, in step 2, the sulfonating agent is at least one of concentrated sulfuric acid, fuming sulfuric acid or chlorosulfonic acid; and /or In step two, the precipitating agent is at least one of water, methanol or ethanol; and/or The mass ratio of the sulfonating agent to polysulfone is 1:0.1-1; and/or The mass ratio of the modifier to black phosphorus is 1:0.1-1. 7. Application of the sulfonated polysulfone-based composite material according to claim 1 or 2 in proton exchange membrane fuel cells. 8. A proton exchange membrane, characterized by comprising the sulfonated polysulfone-based composite material according to claim 1 or 2. 9. A fuel cell membrane electrode, characterized by comprising the proton exchange membrane according to claim 8. 10. A proton exchange membrane fuel cell, characterized by comprising the fuel cell membrane electrode according to claim 9.