KR101292214B1 - Preparation and characterization of sulfonated polyetheretherketone(SPEEK) nanofibrous membrane for proton exchange membrane fuel cell by electrospinning - Google Patents

Abstract

 The present invention is a polyetheretherketone (PEEK) as a starting material to form a sulfonated functionalized polymer, and further sulfonated polyetheretherketone (Sulfonated Polyetheretherketone, SPEEK through the application of electrospinning and hot press) The present invention relates to a nano ion exchange membrane production method. SPEEK nano ion exchange membrane prepared by the present method is excellent in hydrogen ion conductivity even at high temperature, it can be applied as a polymer electrolyte membrane in a fuel cell.

Description

  Preparation method of sulfonated polyetheretherketone nano ion exchange membrane for fuel cell by electrospinning {Preparation and characterization of sulfonated polyetheretherketone (SPEEK) nanofibrous membrane for proton exchange membrane fuel cell by electrospinning}

  The present invention is a method for preparing a sulfonated polyetheretherketone (SPEEK) nano-ion exchange membrane by introducing a sulfonic acid group to the polyetheretherketone (PEEK) through a sulfonation reaction and electrospinning it and through It relates to a nano ion exchange membrane produced. More specifically, a method for producing a nano-ion exchange membrane for a fuel cell having excellent thermal and mechanical stability by maximizing a specific surface area and improving hydrogen ion conductivity by preparing a nano-ion exchange membrane using an electrospinning method and a nano ion produced by the production method It relates to an exchange membrane.

  The fuel cell is a device that converts fuel directly into electrical energy through electrochemical reactions, and is attracting attention as a renewable energy source because it is more efficient than existing internal combustion engines and does not emit pollutants.

  Depending on the type of electrolyte, the fuel cell may be an alkaline fuel cell (AFC), a phosphate fuel cell (PAFC), a molten carbonate fuel cell (MCFC), or a solid oxide fuel cell. (Solid Oxide Fuel Cell, SOFC), Polymer Electrolyte Membrane Fuel Cell (PEMFC), and Direct Methanol Fuel Cell (DMFC). Among these, PEMFC has the advantages of no electrolyte leakage, operates at low temperature, and produces a wide range of outputs compared to other fuel cells, so that PEMFC has a power source of pollution-free vehicles, on-site power generation, spacecraft power, military power, and mobile power. The scope of application is very wide.

  The conditions for the PEMFC polymer electrolyte membrane as described above should be excellent in high hydrogen ion conductivity, mechanical, chemical and electrical stability, and low cost. Currently, the most widely used electrolyte membranes are perfluorinated polymer electrolyte membranes such as Nafion of DuPont and Asiplex of Asahi Chemical. However, when these membranes are applied as PEMFC, they have problems such as high price, reduced conductivity and reduced catalytic effect when used for a long time, and sudden drop in performance above 80 ° C.

  Therefore, there has been a demand for the development of a polymer electrolyte membrane having excellent performance, high thermal mechanical stability, and capable of operating at a high temperature of 80 ° C or higher. In order to reflect these demands, new hydrocarbon-based polymer electrolyte membranes have been attempted to supplement the problems of the perfluorinated membranes. Among the hydrocarbon polymers, polyetheretherketone (PEEK) is a non-fluorine heat-resistant polymer, which has excellent hydrogen ion conductivity, excellent chemical stability, oxidation stability, and mechanical properties, so it can be applied as a PEMFC polymer electrolyte membrane. It is becoming.

  However, conventional sulfonated polyetheretherketone (SPEEK) membranes manufactured by membrane manufacturing methods such as casting have not shown commercial fuel cell performance while maintaining ionic conductivity at the Nafion level. Therefore, new research is needed to improve the disadvantages of existing membranes.

  Therefore, in the present application, as a method for improving the existing membrane, a sulfonic acid group is functionalized in polyetheretherketone (PEEK), and a method for preparing a nano ion exchange membrane using an electrospinning method and a nano ion exchange membrane manufactured through the same To provide.

  More specifically, a nano ion exchange membrane is prepared by electrospinning to improve hydrogen ion conductivity with high specific surface area to weight ratio, and have excellent thermal and mechanical stability. Sulfonated Polyetheretherketone (SPEEK) nano ion exchange membrane The purpose of the present invention is to provide an improved SPEEK film and a method of manufacturing SPEEK film.

 The present invention provides a sulfonated polyetheretherketone (SPEEK) by adding sulfuric acid and chlorosulfonic acid to introduce a cation exchanger sulfonic acid group to polyetheretherketone (PEEK) in order to achieve the above object.

  Subsequently, it is dissolved in a solvent to prepare a spinning solution having a constant viscosity, and the spinning solution is electrospun at a constant voltage, flow rate and spinning distance. In the electrospinning process of the present invention, the solvent concentration, spinning voltage, flow rate, spinning distance and the like can be appropriately adjusted to suit the purpose, and various applications may be applied. The nanofibers are nanofibers having a diameter of 30 to 200 nm through electrospinning.

  The nano ion exchange membrane is preferably prepared at 10 to 50 ° C., preferably at 20 to 30 ° C. by applying a pressure of 300 to 1000 psi through a hot press, and the application time of the hot press is 30 seconds to 30 minutes, Preferably 2 to 10 minutes, the prepared nano ion exchange membrane is preferably 0.001 ~ 0.05cm thick, preferably 0.006 ~ 0.008 cm.

  To look more specifically at this,

According to the present invention,

a) sulfonated polyetheretherketone (SPEEK) manufacturing step of sulfonating polyetheretherketone (PEEK) with chlorosulfonic acid to sulfonate;

b) SPEEK nanofiber manufacturing step by electrospinning the SPEEK; And

c) SPEEK nano-ion exchange membrane manufacturing step using the SPEEK nanofibers hot press; .

In step a) (FIG. 1), sulfonation of PEEK is prepared by adding a sulfonating agent to a PEEK solution and heating it. For example, the sulfonating agent in the present invention is not limited as long as it adopts compounds known in the art such as sulfonic acid. In addition, the sulfonation of this step can be controlled by the sulfonation rate by reacting for 1 to 30 hours at 60 ~ 150 ℃. To be more specific, for example, PEEK was dried at 100 ° C. for 12 hours to introduce functional groups into PEEK, and then 10 g of PEEK was added to 200 ml of sulfuric acid and stirred at 60 ° C. for 24 hours.

Substitution rate of the sulfone group (-SO ₃ H) of the present invention is not particularly limited as long as the sulfone group is substituted, 1 to 50 parts by weight of sulfonating agent, preferably 2 to 20 parts by weight based on 100 parts by weight of PEEK. And sulfonation reaction at room temperature and nitrogen atmosphere for 1 to 30 hours. In order to terminate the sulfonation reaction after the reaction, the solution is added to a quenching solution such as distilled water to terminate the reaction. For example, the solution may be precipitated by being poured into cooled water and washed repeatedly with distilled water until the pH becomes 7-8.

  Drying to remove moisture of the sulfonated PEEK of the present invention. Although drying is not restrict | limited greatly, For example, manufacturing SPEEK by drying for 24 hours at normal temperature may prevent deterioration etc ..

  In step b), the functionalized polymer prepared in step a) is prepared using SPEEK nanofibers by electrospinning. The method for producing nanofibers is prepared by conventional methods in the art. For example, a normal spinning machine, a means which can substitute a spinning machine, etc. can be used, More preferably, an electrospinning method etc. are mentioned.

The physicochemical characteristics of sulfonated polyetheretherketone (SPEEK) nano ion exchange membranes prepared according to the present invention are as follows. The surface of the membrane produced by Press has a smooth and uniform morphological characteristic. In addition, the hydrophilicity of the membrane is induced by the introduction of sulfonic acid, so that water absorption increases with increasing time of sulfonation reaction, and ion exchange capacity and proton conductivity increase accordingly.

SPEEK nano ion exchange membrane prepared by the present invention has excellent physicochemical properties to be applied as a polymer electrolyte membrane in a fuel cell by increasing the ionic conductivity by the production characteristics of nanofibers as the hydrophilic proton is introduced through the sulfonation reaction .

The nano-ion exchange membrane prepared by the present invention is prepared by electrospinning method and has excellent hydrogen ion conductivity, and shows high hydrogen ion conductivity even at high temperature of 80 ° C., which is excellent in thermal and mechanical stability. It is possible.

1 shows the mechanism of the sulfonation reaction according to the present invention.
Figure 2 shows a Scanning Electron Microscopy (SEM) photograph of sulfonated polyetheretherketone (SPEEK) nanofibers according to the present invention.
Figure 3 shows a schematic diagram illustrating a method for producing a SPEEK nano ion exchange membrane according to the present invention.
4 is a graph showing the water content of the embodiment according to the present invention.
5 is a graph showing the ion exchange capacity of the embodiment according to the present invention.
Figure 6 is a graph showing the hydrogen ion conductivity at 25 ° C of the embodiment according to the present invention.
Figure 7 is a graph showing the hydrogen ion conductivity at 80 ° C of the embodiment according to the present invention.

Hereinafter, the present invention will be described in detail according to each process.

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which are intended only for understanding the constitution and effects of the present invention and are not intended to limit the scope of the present invention.

[Example]

Sulfonation was carried out using the raw materials of the contents listed in Table 1, and physical properties were measured using the same. That is, PEEK was dried at 100 ° C. for 12 hours to introduce functional groups into PEEK, and then 10 g of PEEK was added to 200 ml of sulfuric acid and stirred at 60 ° C. for 24 hours. 6-12 g of chlorosulfonic acid was added to replace the sulfonic group (-SO ₃ H) in the prepared solution, and the sulfonation reaction was performed at room temperature and nitrogen atmosphere for 1 to 5 hours. After the reaction, to terminate the sulfonation reaction, the solution is precipitated in distilled water with ice and washed repeatedly with distilled water until the pH is 7-8. SPEEK was prepared by drying at room temperature for 24 hours to remove moisture of the polymer.

 In step b), the functionalized polymer prepared in step a) was prepared using SPEEK nanofibers by electrospinning. SPEEK nanofibers were prepared by injecting the pre-functionalized polymer solution into a 20 cc syringe, fixing the distance between the syringe nozzle and the connecting roller at 10 cm, and supplying the flow rate at 0.3 ml / hr at 22 kV. The connecting roller was a circular drum made of stainless steel with a length of 20 cm and a circumference of 25 cm, and the rotational speed and the reciprocating speed were fixed at 30 cm / min and 2 cm / min, respectively. The diameter of the ion exchange fiber prepared in this manner was prepared at 80 nm and the prepared SPEEK nanofibers were observed by scanning electron microscopy (Scanning Electron Microscopy, SEM) (Fig. 2).

  In step c), the nanofibers prepared in step b) were prepared by using a hot press. The pressure was fixed at 600 psi, the temperature was 25 ℃ and the application time was set to about 5 minutes.

The physical properties (water content, ion exchange capacity, hydrogen ion conductivity) of the prepared nano ion exchange membrane through step c) (FIG. 3) were measured and the results are shown in Table 1 below.

Moisture content measurement

 To measure the moisture content of the membrane, measure the weight of the sheared membrane (3cm × 3cm) to a certain size, immerse it in distilled water for 24 hours, swell it sufficiently, remove the free water on the surface of the ion exchange membrane, and weigh it. Substituted in Equation (1), the moisture content of the ion exchange membrane was measured.

(1)

(One)

Where W _wet is the weight of the wet membrane and W _dry is the weight of the _dry membrane.

Ion exchange capacity measurement

 The ion exchange capacity of the membrane was measured by the titration method. The ion-exchange membrane cut to a certain size was washed several times with 1 N HCl standard solution, washed with distilled water, placed in a 250 ml Erlenmeyer flask, and 100 ml of 0.1 N NaOH standard solution was added thereto and reacted for 24 hours while stirring to reach equilibrium. An aliquot of the supernatant was added to a 50 ml Erlenmeyer flask, and 2-3 drops of phenolphthalein indicator were added dropwise, titrated with 0.1 N HCl standard solution while stirring, and the ion exchange capacity of the SBS membrane was calculated by Equation (2).

(2)

(2)

Where V _HCl and V _NaOH are the volumes of HCl and NaOH used for the titration, and N _HCl and N _NaOH represent normal concentrations.

Measurement of electric ion conductivity of membrane

Using a membrane electrical resistance to measure the electrical conductivity of the film, the electric conductivity was calculated by the following equation (3).

(3)

(3)

 Where sigma represents the electrical ion conductivity and L represents the thickness of the film. ER is the electrical resistance of the membrane and A is the effective area of the membrane.

In order to measure the electrical resistance of the membrane, a 1.5 cm × 1.5 cm membrane was deposited by dipping 1.5 cm × 1.5 cm membrane into a 2-compartment cell in 0.5M NaCl standard solution for 24 hours using a 3522-50 LCR meter (Japan). After fixing, the 0.5 N NaCl electrolyte was filled, and the electrical resistance of the membrane was measured (R ₁ ). In addition, the resistance of only the NaCl electrolyte solution was measured (R ₂ ) and substituted in Equation (4) to obtain the electrical resistance value of the membrane.

(4)

(4)

Here, R ₁ is the electrical resistance measured after inserting the membrane in the electrochemical cell and R ₂ represents the electrical resistance of the electrolyte only after removing the membrane. In addition, A represents the effective area of the film.

[Comparative Example]

In the above Example was carried out in the same manner as in Example 1 except that the casting method (70 ℃, dried in an oven for 3 days), then dried at 150 ℃ for 5 hours to produce a film of 0.007cm.

Nos. 4 to 7 Example Polyether ether ketone (g) Chlorosulfonic acid (g) Sulfonation time (hr) Moisture content (%) Ion exchange capacity (meq / g) Hydrogen ion
Conductivity (S / cm) (25 ℃) Hydrogen ion
Conductivity (S / cm) (80 ℃) One Example 1 10 6 One 22.5 1.05 0.016 0.036 Example 2 10 6 2 54.6 1.25 0.035 0.052 Example 3 10 6 3 73.8 1.36 0.063 0.091 Example 4 10 6 4 92.3 1.58 0.086 0.110 Example 5 10 6 5 124.7 1.83 0.092 0.120 2 Example 6 10 9 One 35.5 1.12 0.022 0.047 Example 7 10 9 2 64.9 1.34 0.047 0.065 Example 8 10 9 3 75.2 1.49 0.068 0.099 Example 9 10 9 4 101.4 1.62 0.089 0.120 Example 10 10 9 5 135.5 1.98 0.097 0.130 3 Example 11 10 12 One 38.7 1.17 0.025 0.053 Example 12 10 12 2 69.5 1.45 0.053 0.078 Example 13 10 12 3 85.5 1.68 0.075 0.110 Example 14 10 12 4 127.3 1.76 0.093 0.130 Example 15 10 12 5 143.6 2.03 0.099 0.140 Comparative example - - - 72.3 0.87 0.014 0.013

As shown in the above Examples and Comparative Examples, the nanofiber spinning according to the present invention and the exchange membrane obtained by pressing the same have very excellent characteristics in ion exchange capacity, and the hydrogen ion conductivity is more excellent at higher temperatures. It can be seen that this has a very improved effect.

Claims (8)

a) sulfonated polyether ether ketone by reacting with chlorosulfonic acid at room temperature for 1 to 30 hours, and sulfonated polyether ether ketone drying at room temperature;
b) sulfonated polyether ether ketone electrospinning to produce sulfonated polyether ether ketone nanofibers; And
c) sulfonated polyether ether ketone nanofibers using a hot press to form a sulfonated polyether ether ketone nano ion exchange membrane;
Sulfonated polyether ether ketone nano ion exchange membrane production method comprising a. The method of claim 1,
Sulfonated polyether ether ketone nano ion exchange membrane production method characterized in that the pressure is 300 ~ 1000 psi, the temperature is 10 ~ 50 ℃ under the conditions of the hot press of step c). The method of claim 1,
Method for producing a sulfonated polyether ether ketone nano ion exchange membrane, characterized in that the thickness of the nano ion exchange membrane in the manufacturing of the nano ion exchange membrane using the hot press of step c) 0.006 ~ 0.008 cm.
delete delete delete Nano ion exchange membrane prepared by the method according to any one of claims 1 to 3. A fuel cell comprising the nano ion exchange membrane according to claim 7.

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