KR100804195B1 - Method for preparation of high temperature proton conducting composite membrane and its high temperature operation of polymer electrolyte fuel cell - Google Patents

Abstract

The present invention improves the conductivity of the inorganic nanoparticles to the same or higher level by introducing a sulfonated group into the inorganic nanoparticles, which is then combined with a heat-resistant polymer or a polymer electrolyte and maintains high conductivity while maintaining heat resistance up to 250 ° C. It provides a high-temperature hydrogen ion conductive polymer electrolyte membrane having. The present invention also provides a high temperature polymer electrolyte fuel cell that can operate up to 250 ° C. using the manufactured composite polymer electrolyte membrane.

High temperature fuel cell, polymer electrolyte fuel cell, sulfonic acid group, nanoparticles, high temperature polymer electrolyte, composite membrane

Description

Method for preparing polymer electrolyte membrane capable of conducting hydrogen ion at high temperature and high temperature operation of polymer electrolyte fuel cell using the same {Method for preparation of high temperature proton conducting composite membrane and its high temperature operation of polymer electrolyte fuel cell}

It shows the conductivity according to the temperature of the composite electrolyte membrane. It can be seen that the conductivity of the membrane increases with increasing temperature, and in the case of the polyimide membrane, the conductivity is drastically improved by adding nanoparticles into which sulfone groups are introduced. In addition, it was confirmed that the conductivity of the polyimide membrane was higher than that of the commercial Nafion membrane by the nanoparticles in which the sulfonic acid group was introduced from the thiol group.

Fuel cell is a next generation energy conversion technology that has been researched around the world because it has various advantages such as high energy conversion efficiency, low carbon dioxide emission and ease of facility size selection according to environmental conditions. In particular, the polymer electrolyte fuel cell (PEMFC) has many advantages obtained by using a solid polymer electrolyte and has a low operating temperature compared to other fuel cells, and thus has high practicality and high power density, making it easy to miniaturize.

The electrolyte of the polymer electrolyte fuel cell uses a polymer ion exchange membrane that transfers H +. In this case, the polymer electrolyte membrane should have high conductivity of hydrogen ions, but should have low conductivity of electrons, less movement of the reactant or water than the movement of ions, and high mechanical and chemical stability. The polymer electrolyte membrane currently used in a fuel cell is a polymer having a main chain of fluorocarbon and having a sulfonic acid group chemically bonded thereto. However, these fluorinated sulfonated polymer membranes are very expensive and have the disadvantage of losing hydrogen transfer capability at 100 ° C or higher. At present, all fuel cells using a fluorine sulfonated polymer electrolyte membrane are operated at 80 ° C.

On the other hand, if the electrolyte membrane is chemically stable at high temperature, the hydrogen ion conductivity of the electrolyte membrane is improved as the temperature is increased, and the activity of the electrode catalyst is increased at a high temperature, and thus the performance is much higher than that of the polymer electrolyte fuel cell. . In addition, when the polymer electrolyte-type fuel cell is operated at a high temperature, it is possible to minimize the influence of the anode catalyst on impurities such as carbon monoxide, which can provide many benefits. Despite these advantages, the polymer electrolyte fuel cell cannot operate at high temperatures because the Nafion electrolyte membrane mentioned above loses its conductivity at high temperatures. Therefore, in order to improve the performance of the polymer electrolyte fuel cell, it is essential to develop an electrolyte membrane that is chemically stable at high temperatures, has high conductivity, and has high mechanical strength.

As a method of making a high temperature polymer electrolyte membrane, two methods of providing conductivity by substituting a sulfonic acid group in a heat resistant polymer and an inorganic material in a polymer electrolyte membrane may be used.

U.S. Patent Nos. 5618334, 4644035, 6176984, Japanese Patent No. 2001-233974 and the like disclose a method of imparting conductivity by introducing sulfonic acid groups into a heat resistant polymer. However, since the heat-resistant sulfonated polymers proposed in the patent show too low a level of hydrogen ion conductivity to operate a fuel cell, the possibility of application to a fuel cell is very small. In addition, when the sulfonic acid group is introduced into the polymer structure, the polymer electrolyte membrane becomes fragile and it becomes impossible to construct a membrane-electrode assembly which is the core of the fuel cell. Therefore, most of the polymer electrolyte membranes proposed in the above-listed patents emphasize application to gas separation membranes, and do not mention their use as fuel cells.

Another method of making a high temperature electrolyte membrane is an organic / inorganic composite electrolyte membrane in which a conductive polymer having a sulfonic acid group and an inorganic material are mixed, and a number of patents for application to a polymer electrolyte fuel cell have been disclosed. U.S. Patent No. 5919583, Japanese Patent Nos. 2001-213987, 2001-198067, 2002-289051, 2000-090946 and the like all have mixed hydrogen ion conductive polymer electrolyte membrane and inorganic conductive particles to enhance thermal stability. Inorganic conductive particles used are generally silica, hydrated tungsten or molybdenum oxide, phosphate materials and the like. However, although these inorganic particles have some conductivity, the conductivity of the organic / inorganic composite electrolyte membrane is inevitably reduced since the inorganic particles are significantly lower than the conductive polymer electrolyte. In addition, since most of the polymers used as polymer electrolyte parts are fluorinated sulfonated polymers, it is impossible to exceed 150 ° C even if they can be operated at a high temperature. Therefore, the high temperature mentioned in the above patents is at most 160 ° C, and all patents and articles generally set from 100 ° C to 150 ° C. This temperature is a medium temperature rather than a high temperature, and the advantages obtained from the high temperature operation of the polymer electrolyte fuel cell as described above cannot be fully utilized. In addition, it is unknown whether any of the patents and papers published up to now can be used as an electrolyte membrane of a polymer electrolyte fuel cell because it does not suggest fuel cell performance at a high temperature and only mentions conductivity of an electrolyte membrane.

In general, the properties of the polymer electrolyte membrane in order for the polymer electrolyte fuel cell to operate at high temperature are thermal stability up to about 250 ° C. and high conductivity, and thus the fuel cell performance at high temperature should be exhibited.

As described above, many attempts have been made to operate the polymer electrolyte fuel cell at high temperatures, but there are still many technical limitations.

Accordingly, the present invention can improve the conductivity of the inorganic nanoparticles to the same or higher level of the polymer electrolyte by introducing a sulfonation group to the inorganic nanoparticles, and again complexed with the heat-resistant polymer to maintain high conductivity while maintaining heat resistance up to 250 ° C. To prepare a high temperature hydrogen ion conductive polymer electrolyte membrane having. In addition, the polymer electrolyte fuel cell operable at a high temperature may be configured by using the prepared high temperature hydrogen ion conductive polymer.

The technical problem to be achieved by the present invention is to provide a sulfonic acid group to the conductive inorganic nanoparticles to provide inorganic nanoparticles that are stable at high temperatures and high in conductivity.

In addition, another technical problem to be achieved by the present invention is to provide a polymer electrolyte membrane that can be used up to 250 ℃ by complexing the conductive inorganic nanoparticles with a heat-resistant polymer or polymer electrolyte.

In addition, another technical problem to be achieved by the present invention is to provide a polymer electrolyte fuel cell capable of operating up to 250 ℃ using the polymer electrolyte membrane.

Finally, another technical problem to be achieved by the present invention is to provide a method for producing the conductive inorganic nanoparticles and a method for producing a polymer electrolyte membrane.

Hydrogen-ion conductive inorganic nanoparticles are provided, the size of which ranges from several nanometers to several hundred nanometers, and the sulfonic acid group introduces conductivity similar to that of the conductive polymer, and maintains high conductivity without dropping the sulfonic acid group even at high temperatures. .

According to the present invention for this purpose,

(A) Nanos, ranging from nanometers to hundreds of nanometers, composed of silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), zeolites, mesoporous materials, and combinations thereof Preparing the Particles

(B) dispersing the nanoparticles in a toluene solution

(C) one or more silanes selected from the group of silanes comprising a benzene ring such as phenethyl triethoxy silane, phenethyl trimethoxy silane, benzyl silane and the like; Step to prepare

(D) dissolving the silane containing the benzene ring in the nanoparticle dispersion solution of step (B)

(E) reacting the silane, nanoparticle, and toluene mixed solution containing the benzene ring at 120 ° C. for a long time;

(F) centrifuging the mixed solution to separate only the solids

(G) washing with toluene and centrifuging again to separate only solids

(H) drying the solids at 80 ° C. in vacuo

(I) the step of introducing the inorganic nanoparticles in which the benzene ring is introduced in the vacuum of the vacuum apparatus as shown in Figure 1, Oleum

(J) Open valve ㉢ in the vacuum apparatus of FIG. 1 to make ㉠ vacuum, close 다시 again, cool 로 with liquid nitrogen, open valve 열어, make ㉡ vacuum, then open valves ㉢, ㉣, ㉤ in order. Introducing Oleum in Sodium into Inorganic Nanoparticles in Sodium

(K) repeating step (J) 10 or more times                     

(L) A method for producing hydrogen ion conductive inorganic nanoparticles is provided, comprising the step of recovering inorganic nanoparticles of sulfonate group introduced therein from a vacuum apparatus and drying at 100 ° C.

The present invention provides hydrogen ion conductive inorganic nanoparticles by the sulfonic acid group introduction method in the liquid phase in addition to the gaseous sulfonic acid group introduction method.

According to the present invention for this purpose,

(A) Nanos, ranging from nanometers to hundreds of nanometers, composed of silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), zeolites, mesoporous materials, and combinations thereof Preparing the Particles

(B) dispersing the nanoparticles in a toluene solution

(C) one or more silanes selected from the group of silanes containing a thiol (SH) structure such as mercapto propyl triethoxy silane and mercapto propyl trimethoxy silane; Step to prepare

(D) dissolving the silane containing the thiol structure in the nanoparticle dispersion solution of step (B)

(E) reacting the silane, nanoparticle, and toluene mixed solution containing the thiol structure at 120 ° C. for a long time;

(F) centrifuging the mixed solution to separate only the solids

(G) washing with toluene and centrifuging again to separate only solids                     

(H) drying the solids at 80 ° C. in vacuo

(I) dispersing the inorganic nanoparticles having the thiol structure in a hydrogen peroxide (H ₂ O ₂ ) solution to oxidize for a long time

(J) centrifuging the mixed solution to separate only solids

(K) introducing the sulfonic acid group by dispersing the solid content again in a sulfur solution

(L) centrifuging the mixed solution again to separate only solids

(M) dispersing the inorganic nanoparticles introduced with the sulfonic acid group in distilled water and washing

(N) centrifuging the mixed solution again to separate only inorganic nanoparticles into which a sulfonic acid group of solids is introduced;

(O) The method for producing a hydrogen ion conductive inorganic nanoparticles is provided, comprising the step of drying the inorganic nanoparticles into which the sulfonic acid group is introduced at 80 ° C. in a vacuum.

The present invention also provides a high temperature hydrogen ion conductive polymer electrolyte membrane by mixing the hydrogen ion conductive inorganic particles synthesized above with a heat resistant polymer.

(A) 250 ° C of Naphthalhalenic polyimide, Polybenzimidazole, Polyvinylidene fluoride, Polyimide-amide, Polysulfone, etc. Preparing one or more polymers selected from the group of polymers capable of maintaining thermal stability up to

(B) dissolving the polymer in one or more solvents selected from a suitable solvent group such as dimethylformamide (DMF), enmethyl pyridine (NMP), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc), acetone, etc. Letting step

(C) mixing the inorganic nanoparticles having a sulfonic acid group in the polymer solution

(D) preparing the mixed solution in the form of a thin film using a device such as a doctor blade, a spin coater, and a chaale

(E) The method for producing a high temperature hydrogen ion conductive polymer electrolyte membrane comprising the step of evaporating the solvent under the appropriate temperature and the appropriate atmospheric pressure to the mixed and prepared thin film as a conductive electrolyte membrane.

In the present invention, by introducing a sulfonated group to the inorganic nanoparticles can improve the conductivity of the inorganic nanoparticles to the same or higher level than the polymer electrolyte, it is complexed with the heat-resistant polymer again to maintain the heat resistance up to 250 ℃ while having a high conductivity A high temperature hydrogen ion conductive polymer electrolyte membrane was prepared. In addition, a polymer electrolyte fuel cell operable at a high temperature was constructed using the prepared high temperature hydrogen ion conductive polymer. Hereinafter, a process of manufacturing the high temperature hydrogen ion conductive polymer electrolyte membrane of the present invention and operating the polymer electrolyte fuel cell at high temperature will be described in detail by way of examples, but the present invention is not necessarily limited thereto.

<Example 1>

After dispersing 0.2 g of the silica nanoparticles dried in vacuo in 50 g toluene, 1 g of mercapto propyl triethoxy silane is mixed therein. The solution is left at 120 ° C. for 24 hours, after which the silica is separated from the solution by centrifugation and washed several times with toluene. The silica into which the thiol (SH) group is introduced is dried in a vacuum at 80 ° C. The thiol-group introduced silica was oxidized in hydrogen peroxide for a long time, centrifuged, dried, and dispersed in a sulfuric acid solution to introduce sulfonic acid groups. The silica nanoparticles into which the sulfonic acid group was introduced were washed in distilled water and dried at 80 ° C. in vacuo.

As described above, the silica nanoparticles into which the sulfonic acid group was introduced were mixed with polyimide (Matrimide) dissolved in DMF at a mass ratio of 30% to form a film having a thickness of 30 μm to measure hydrogen ion conductivity.

<Example 2>

After dispersing 0.2 g of silica nanoparticles dried in vacuo in 50 g toluene, 1 g of phenethyl triethoxy silane is mixed thereto. The solution is left at 120 ° C. for 24 hours, after which the silica is separated from the solution by centrifugation and washed several times with toluene. The silica in which the benzene group is introduced is dried in a vacuum at 80 ° C.

Comparative Example 1

Matrimide, a commercially available type of polyimide, was dissolved in DMF at 15% by mass and then formed into a film with a thickness of about 30 μm. Nafion 117 was purchased from DuPont and used by hydrogen substitution in sulfuric acid solution.

The silica nanoparticles in which the sulfonic acid groups prepared in Examples 1 and 2 were introduced were mixed with polyimide (Matrimide) dissolved in DMF at a mass ratio of 30% to form a film having a thickness of 30 μm, and the hydrogen ion conductivity was measured and compared. The conductivity of the membrane prepared in Example 1 was compared.

Table 1 shows the conductivity according to the temperature of the film prepared. It can be seen that the conductivity of the membrane increases with increasing temperature, and in the case of the polyimide membrane, the conductivity is drastically improved by adding nanoparticles into which sulfone groups are introduced. In addition, it was confirmed that the conductivity of the polyimide membrane was higher than that of the commercial Nafion membrane by the nanoparticles in which the sulfonic acid group was introduced from the thiol group.

2 is the conductivity vs. By showing the temperature in the Areneus graph, the conductivity of Example 2 is much higher than that of the Nafion membrane, and it can be seen that the conductivity improves as the temperature increases.

Temperature (℃) Conductivity (S / cm) Example 1 Example 2 Nafion 117 Matrimide 40 0.035 1.27 0.1003 Less than 0.00001 50 0.0389 1.48 0.1086 Less than 0.00001 60 0.0418 1.48 0.1108 Less than 0.00001 70 0.0497 1.5103 0.1165 Less than 0.00001 80 0.0566 1.5373 0.1353 Less than 0.00001 90 0.0680 1.59 0.1496 Less than 0.00001 100 0.0795 1.68 0.1653 Less than 0.00001

Incorporation of sulfonation groups into the inorganic nanoparticles could improve the conductivity of the inorganic nanoparticles to a level equal to or higher than that of the polymer electrolyte. This was again composited with a heat resistant polymer to prepare a high temperature hydrogen ion conductive polymer electrolyte membrane having high conductivity while maintaining heat resistance up to 250 ° C. The prepared high temperature hydrogen ion conductive polymer was used in a polymer electrolyte fuel cell to enable operation at high temperature.

Claims (6)

delete Method for producing a hydrogen ion conductive inorganic nanoparticles comprising the following steps: (A) preparing nanoparticles composed of silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), zeolite, mesoporous material and complexation thereof; (B) dispersing the nanoparticles in a toluene solution; (C) preparing one or more aromatic silanes selected from the group of phenethyl triethoxysilane, phenethyl trimethoxysilane and benzyl silane; (D) dissolving the aromatic silane in the nanoparticle dispersion solution of step (B); (E) heating the mixed solution; (F) centrifuging the mixed solution to separate only solids; (G) washing the centrifuged filtrate with toluene and then centrifuging to separate only the solids; (H) drying the solid obtained by centrifugation in vacuo; (I) introducing an inorganic nanoparticle into which the benzene ring is introduced, and an oleum in the vacuum of the vacuum apparatus as shown in FIG. 1; (J) In the vacuum apparatus of FIG. 1, open valve 만들고 to vacuum 진공, close 다시 again, cool 로 with liquid nitrogen, open valve 열어, make ㉡ vacuum, then open valves ㉢, ㉣, 차례로 in sequence. Introducing oleum in the jar into the inorganic nanoparticles of the jar; (K) repeating step (J) 10 or more times; (L) recovering inorganic nanoparticles having a sulfonic acid group introduced therein from a vacuum apparatus and drying at 100 ° C. Method for producing a hydrogen ion conductive inorganic nanoparticles comprising the following steps: (A) Nanos, ranging from nanometers to hundreds of nanometers, composed of silicon oxide (SiO ₂ ), aluminum oxide (Al ₂ O ₃ ), zirconium oxide (ZrO ₂ ), zeolites, mesoporous materials, and combinations thereof Preparing the particles; (B) dispersing the nanoparticles in a toluene solution; (C) preparing a silane comprising one or more thiol (SH) structures selected from the group of mercaptopropyl triethoxysilane and mercaptopropyl trimethoxysilane; (D) dissolving the silane containing the thiol structure in the nanoparticle dispersion solution of step (B) (E) heating the mixed solution; (F) centrifuging the mixed solution to separate only the solids; (G) washing the centrifuged filtrate with toluene and then centrifuging to separate only the solids; (H) drying the solid obtained by centrifugation in vacuo; (I) dispersing the inorganic nanoparticles having the thiol structure in a hydrogen peroxide (H ₂ O ₂ ) solution to oxidize for a long time; (J) centrifuging the mixed solution to separate only solid content; (K) introducing the sulfonic acid group by dispersing the solid content again in a sulfuric acid solution; (L) centrifuging the mixed solution again to separate only solids; (M) dispersing the inorganic nanoparticles having the sulfonic acid group introduced therein in distilled water and washing them; (N) centrifuging the mixed solution again to separate only inorganic nanoparticles into which a sulfonic acid group of solids is introduced; (O) drying the inorganic nanoparticles into which the sulfonic acid group is introduced at 80 ° C. in a vacuum. Hydrogen-ion conductive inorganic particles synthesized in claim 2 or 3, Naphthalhalenic polyimide, Polybenzimidazole, Polyvinylidene fluoride and Polyimide-amide A high temperature hydrogen ion conductive polymer electrolyte membrane comprising a heat resistant polymer selected from the group consisting of: Method for producing a high temperature hydrogen ion conductive polymer electrolyte membrane comprising the following steps: (A) to prepare a heat resistant polymer selected from the group consisting of Naphyhalenic polyimide, Polybenzimidazole, Polyvinylidene fluoride and Polyimide-amide step ; (B) dissolving the polymer in one or more solvents selected from the group consisting of dimethylformamide (DMF), enmethyl pyridine (NMP), dimethyl sulfoxide (DMSO), dimethylacetamide (DMAc) and acetone ; (C) mixing the polymer solution, the hydrogen ion conductive inorganic particles synthesized in claim 2 or 3; (D) preparing the mixed solution in the form of a thin film using a device selected from a doctor blade, a spin coater and a chaale; (E) drying the thin film to complete the conductive electrolyte membrane. Polymer electrolyte fuel cell manufactured using the conductive polymer electrolyte membrane prepared in claim 5.

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