KR20080103189A - Metal(iv)-silicate-phosphate and use of the same - Google Patents

Abstract

Metal(IV)-silicate-phosphate having high performance under low humidity condition is provided to provide the metal(IV)-silicate-phosphate having the high conductivity of hydrogen under low humidity condition. Metal(IV) alkoxide, legand covalent-bonding with the metal and acid are mixed together. Metal(IV)-silicate precursor solution is prepared for by adding silicon alkoxide and acid are added in mixture. Phosphoric acid or polyphosphoric acid is added in the metal(IV)-silicate precursor solution and mixed. The metal(IV)- silicate-phosphate (MSP) indicated as the organic polymer or less chemical formula 1 is included. The metal(IV)-silicate-phosphate (MSP) is dispersed in the organic matrix separator. The organic polymer is polymer selected first group consisting of polyaryleneether(PAE), polyether-ether-ketone(PEEK), polyetherethersulfone(PEES), polytetrafluoroethylene(PTFE), polyvinylidenefluoride(PVDF), nafion, and polyazole.

Description

Metal (IV) -silicate-phosphate and its use {METAL (IV) -SILICATE-PHOSPHATE AND USE OF THE SAME}

1 is a graph of the crystal structure of the zirconium silicate phosphate powder prepared in Example 1 using an X-ray diffraction spectrometer (X-ray Diffraction, equipment name: Bruker D4 Endeavor, Cuk radiation).

FIG. 2 compares the performance under low-humidity conditions (relative humidity of 40% and cell temperature of 70 ° C.) of the fuel cell including the organic / inorganic composite electrolyte membrane of Example 3 and the organic electrolyte membranes of Comparative Examples 1 and 2, respectively. It is a graph.

The present invention is formula M (IV) SiO ₂ (HPO ₄ ) ₂ ㆍ n Metal (IV) -silicate-phosphate represented by H ₂ O (Metal (IV) Silicate Phosphate (MSP) and the use thereof, and more specifically, an organic / inorganic composite electrolyte membrane comprising the same, an electrode comprising the same, A membrane electrode assembly (MEA) comprising the organic / inorganic composite electrolyte membrane and / or the electrode, and a fuel cell including the membrane electrode assembly.

Recently, due to the rapid spread of portable electronic devices and wireless communication devices, a lot of interest and research has been progressed in the development of a fuel cell as a battery as a portable power supply source, a fuel cell for a pollution-free automobile and a fuel cell for power generation as a clean energy source.

A fuel cell is an energy conversion device that converts chemical energy of a fuel directly into electrical energy. In other words, the fuel cell is a power generation method that uses fuel gas (hydrogen, methanol, or other organic material) and oxidizing agent (oxygen or air), and generates electric power by using electrons generated during the redox reaction. It is being researched and developed as the next generation energy source due to the eco-friendly features with low emission of pollutants and pollutants.

For low humidity polymer electrolyte fuel cell using hydrogen as a fuel (P olymer E lectrolyte M embrane F uel C ell, PEMFC), capable of operating over a wide temperature range because the use of simplified cooling system and the sealing parts, a low humidified hydrogen to the fuel Therefore, it has been spotlighted as a vehicle and home power supply because of the advantages of using a humidifier and fast driving. In addition, it is a high output fuel cell with a higher current density than other types of fuel cells. It operates at a wide range of temperatures, has a simple structure, and has fast startup and response characteristics.

Such a fuel cell has a membrane electrode assembly (MEA) having a hydrogen ion exchange membrane interposed between an anode and a cathode, and a bipolar plate that collects and supplies fuel for electricity generated. It consists of a continuous composite of plates. At the anode, hydrogen or methanol, which is a fuel, is supplied and reacts on the electrode catalyst to generate hydrogen ions (H +, protons). At the cathode, hydrogen ions and oxygen that pass through the hydrogen ion exchange membrane combine to form pure water. Create

The anode and the cathode each consist of a catalyst layer in which oxidation / reduction reactions of reactants occur and a support layer (or gas diffusion layer) supporting the catalyst layer. Porous carbon paper or carbon cloth is widely used as a support layer. In addition to supporting the catalyst layer, the support layer serves as a gas diffusion layer for diffusing the reactants into the catalyst layer, a current collector for moving currents generated from the catalyst layer to the separator plate, a role for passage of the generated water out of the catalyst layer, and a hydrogen ion exchange membrane. It also plays a role in ensuring that adequate moisture is present.

The hydrogen ion exchange membrane uses a polymer electrolyte membrane made of a polymer electrolyte, and its thickness is usually 20 to 300 µm. As a representative polymer electrolyte membrane, a Nafion membrane is known. While sulfonated polymer electrolyte membranes, such as conventional Nafion membranes, exhibit high conductivity and fuel cell performance under sufficient humidification, they are more pronounced in low-humidity conditions due to a drastic decrease in conductivity of hydrogen ions as the moisture in the membrane decreases. The performance degradation is caused. Therefore, use at high temperatures (above 100 ° C.) requires strict water management and requires complex systems.

Currently, researches on various types of organic / inorganic composite electrolyte membranes in which an inorganic conductive material (Proton Conducting Filler) showing high hydrogen ion conductivity and hygroscopicity are added to an organic polymer to supplement the above-mentioned problems.

P. Costamagna (Electrochimica Acta 2002, Vol 47, 1023) prepared an organic / inorganic composite electrolyte membrane in which Zirconium Phosphate was added to Nafion 115. In the case of the composite electrolyte membrane prepared in the above document, it was four times higher (1000 mA / cm ² @ 0.45 V) than the performance of the electrolyte membrane made of pure Nafion 115 at 130 ° C. (3 bar, H ₂ / O ₂ ) at 100% relative humidity.

According to US patent US 2005/0227135 A1, when α-Zirconium Phosphate is added to Nafion, 1000 mA / cm ² only at 50% relative humidity under high temperature pressurization (120 ° C., 2 bar, H ₂ / O ₂ ) (@ 0.6 V) performance (about five times higher than pure Nafion).

According to US Pat. No. 7,008971 B2, a composite electrolyte membrane in which Montmorillonite and TEOS is added to a sulfonated polyether ether ketone is prepared at 7 × 10 ⁻ at 90 ° C. under 100% relative humidity. The hydrogen ion conductivity value of ² S / cm level was shown. However, this does not meet the demand characteristics of fuel cells that must satisfy high hydrogen ion conductivity at low humidity conditions.

G. M, Anilkumar (Electrochemistry Communications 2006, Vol. 8, 133), when the composite electrolyte membrane was prepared by adding α-Zirconium Phosphate to sulfonated polyethersulfone, a temperature of 90 ° C. and a relative humidity of 90% Time, 0.19 High hydrogen ion conductivity values of S / cm, but low levels of 1.9 x 10 ^-2 S / cm at 3.7 x 10 ^-3 S / cm and 50% relative humidity at the same temperature Indicates conductivity value.

As such, the conventional electrolyte membranes are not practical due to deterioration in performance under low-humidity conditions.

The present invention aims to provide a novel metal (IV) -silicate-phosphate (MSP) having high hydrogen ion conductivity even under low humidity conditions.

In addition, an object of the present invention is to provide an organic / inorganic composite electrolyte membrane that realizes a high performance improvement under low humidity conditions by forming a stable hydrogen ion conduction channel between the organic polymer and MSP.

It is another object of the present invention to provide an electrode which induces formation of a hydrogen ion conducting channel between the catalyst and the MSP, thereby achieving a high performance improvement under low humidity conditions.

In addition, an object of the present invention is to provide a fuel cell having an improved organic / inorganic composite electrolyte membrane and / or a membrane electrode assembly (MEA) including the electrode and the membrane electrode assembly.

The present invention provides a metal (IV) -silicate-phosphate (MSP) represented by the following formula (1).

[Formula 1]

M (Ⅳ) SiO ₂ (HPO ₄ ) ₂ ㆍ n H ₂ O

In Formula 1, M is at least one metal selected from the group consisting of Group IVA and Group IVB metals.

The present invention also provides an organic / inorganic composite electrolyte membrane including an organic polymer and a metal (IV) -silicate-phosphate (MSP) represented by Chemical Formula 1.

The present invention also provides an electrode having a catalyst layer including metal (IV) -silicate-phosphate (MSP) represented by Formula 1 on one or both surfaces of a gas diffusion layer.

In addition, the present invention is a cathode; Anode; And an electrolyte membrane positioned between the cathode and the anode.

(i) the electrolyte membrane is an organic / inorganic composite electrolyte membrane according to the present invention; Or (ii) the cathode, or anode, or both, according to the present invention; Or it provides a membrane electrode assembly (MEA) characterized in that both (i) and (ii).

In addition, the present invention provides a fuel cell having the membrane electrode assembly.

Hereinafter, the present invention will be described in detail.

<Metal (IV) -silicate-phosphate (MSP)>

The metal (IV) -silicate-phosphate (MSP) of the present invention is represented by the formula M (IV) SiO ₂ (HPO ₄ ) ₂ · n As a novel substance represented by H ₂ O, phosphate attracts moisture to form hydrogen bonds, and metal (IV) and silicates (SiO ₂ ) form polyhedral network clusters through sol-gel reactions It can draw water channels (hydrogen transfer channels). Therefore, the metal (IV) -silicate-phosphate (MSP) exhibits high hydrogen ion conductivity even at low humidity conditions of 40% or less, for example, and can form stable morphology upon reaction with organic polymers. It can be used suitably for electrochemical elements, such as a battery.

The metal may be selected from Group IVA metals such as Ti, Zr, Hf, and Rf, and Group IVB metals such as Si, Ge, Sn, and Pb, and in some cases, may be included as a combination of two or more of them. have. Especially, Zr is preferable.

Metal (IV) -silicate-phosphate (MSP) of this invention,

(a) metal (IV) alkoxides or metal (IV) salts; Ligands that coordinate with metals; And mixing an acid;

(b) silicon alkoxide in the mixture of step (a); And adding an acid to prepare a metal (IV) -silicate precursor solution; And

(c) adding and mixing phosphoric acid or polyphosphoric acid to the metal (IV) -silicate precursor solution.

Step (a) may be carried out in the presence of alcohol and / or water. The alcohol is not particularly limited, but it is preferable to use the same kind as the alkoxy of the metal alkoxide.

In addition, as the ligand for coordinating with the metal, conventional compounds known as ligands capable of σ-bonding and / or π-bonding with metal can be used. Non-limiting examples of the ligand include acetone, acetyl acetone and the like, but is not particularly limited. In addition, the acid may be hydrochloric acid, phosphoric acid, sulfuric acid, etc., but is not limited thereto.

The metal (IV) alkoxide and metal (IV) salt are not particularly limited as long as they are salts of alkoxides and metals of metals selected from Group IVA metals and Group IVB metals.

In the case of using an electrolyte membrane or an electrode as a raw material described later and a liquid phase, the poly (phosphate) -silicate may be added by using an excessive amount of a polyphosphoric acid solution or a phosphoric acid solution during the production process, or by adding an additional phosphoric acid solution after the reaction. It may also be prepared as a phosphate (MSP) solution.

In addition, the metal (IV) -silicate-phosphate (MSP) may be prepared by performing a process of forming an electrolyte membrane or an electrode using the metal (IV) -silicate precursor solution, followed by phosphoric acid treatment.

Organic / Inorganic Composite Electrolyte Membrane

The electrolyte membrane of the present invention is an organic / inorganic composite electrolyte membrane, and includes an organic polymer and a metal (IV) -silicate-phosphate (MSP) represented by Chemical Formula 1, and the metal (IV) -silicate-phosphate (MSP) It may be dispersed in the organic polymer matrix.

As described above, the organic / inorganic composite electrolyte membrane of the present invention exhibits a high hydrogen ion conductivity under low-humidity conditions and forms a metal (IV) -silicate-phosphate (MSP) that can form a stable morphology upon reaction with organic polymers. As a result, stable hydrogen ion conduction channels are formed between the organic polymer-metal (IV) silicate phosphate (MSP) and the electrolyte membrane exhibits high hydrogen ion conductivity at low humidity conditions. In fact, it can be seen that the organic / inorganic composite electrolyte membrane of the present invention shows better hydrogen ion conductivity than the conventional Nafion membrane under low humidity (40% relative humidity) conditions (see Table 1). It can also provide excellent chemical and thermal stability.

In the organic / inorganic composite electrolyte membrane of the present invention, the organic polymer is not particularly limited as long as it is generally used as an electrolyte membrane polymer.

Non-limiting examples of such organic polymers are polyaryleneether (PAE), polyetheretherketone (PEEK), polyetherethersulfone (polyetherethersulfone, PEES), polytetrafluoroethylene (PTFE), poly Polyvinylidenefluoride (PVDF), Nafion, polyazole, polyvinylalcohol (PVA), polyphenylene oxide, polyphenylene sulfide, polyphenyl Sulfones, polycarbonates, polystyrenes, polyimides, polyamides, polyquinoxalines, (phosphated) polyphosphazenes, or polybenzimidazoles, and the like, either alone or in combination of two or more thereof. Can be used.

In particular, in order to form a more stable hydrogen ion conducting channel between organic polymer-metal (IV) silicate phosphate (MSP), the organic polymer is at least one hydrogen ion selected from the group consisting of sulfonic acid groups, phosphoric acid groups, hydroxyl groups and carboxylic acid groups. Organic polymers having exchange groups are preferred, and sulfonated polyetheretherketone (PEEK) is more preferred.

In the organic / inorganic composite electrolyte membrane of the present invention, the content range of the metal (IV) -silicate-phosphate (MSP) is not particularly limited as long as it is a range capable of exhibiting high hydrogen ion conductivity while forming a membrane. 0.1 to 1000 parts by weight, preferably 1 to 100 parts by weight, based on 100 parts by weight of the organic polymer.

The organic / inorganic composite electrolyte membrane of the present invention may include other components, additives, and the like that are known in the art, in addition to the aforementioned components. In addition, the thickness of the organic / inorganic composite electrolyte membrane is not particularly limited and can be adjusted within a range to improve the performance and safety of the fuel cell.

The organic / inorganic composite electrolyte membrane according to the present invention can be prepared according to conventional methods known in the art. For example, (i) the organic polymer or a solution thereof; And mixing the metal (IV) -silicate-phosphate (MSP) or a solution thereof to prepare a mixture thereof. And (ii) forming a film using the mixture.

As another example, (i) the organic polymer or a solution thereof; And mixing the metal (IV) -silicate precursor solution to prepare a mixture thereof; And (ii) molding the membrane using the mixture, followed by phosphoric acid treatment. The process of phosphoric acid treatment may be performed by putting a molded membrane into the phosphoric acid solution, washing.

In this case, the metal (IV) -silicate precursor solution may include (a) a metal (IV) alkoxide or metal (IV) salt; Ligands that coordinate with metals; And mixing an acid; And (b) a silicon alkoxide in the mixture of step (a); And addition of an acid.

In the preparation of the metal (IV) -silicate precursor solution, step (a) may be performed in the presence of alcohol and / or water. The alcohol is not particularly limited, but it is preferable to use the same kind as the alkoxy of the metal alkoxide. In addition, as the ligand for coordinating with the metal, conventional compounds known as ligands capable of σ-bonding and / or π-bonding with metal can be used. Non-limiting examples of the ligand include acetone, acetyl acetone and the like, but is not particularly limited. In addition, the acid may be phosphoric acid, sulfuric acid, etc., but is not limited thereto.

The solvent for dissolving the organic polymer, the solubility index is similar to the organic polymer to be used in order to facilitate uniform mixing and subsequent solvent removal, it is preferable that the boiling point (boiling point) is low. However, the present invention is not limited thereto, and conventional solvents known in the art may be used. Non-limiting examples of the solvent for dissolving the organic polymer include N, N-dimethylacetamide (DMAc), N-methylpyrrolidone (NMP), dimethyl sulfoxide (dimethylsulfoxide, DMSO), or N, N-dimethylformamide (N, N-dimethylformamide, DMF), phosphoric acid, polyphosphoric acid, and the like.

Molding the membrane using the mixture may proceed by coating and drying the mixture on a substrate and then separating the electrolyte membrane from the substrate. Non-limiting examples of the substrate include glass plates, polymer films, stainless steel plates and the like.

The method of coating the mixture on a substrate may use conventional coating methods known in the art, for example, dip coating, die coating, roll coating, comma coating, Various methods, such as a doctor blade or a mixing method thereof, can be used.

<Electrode>

In the electrode of the present invention, a catalyst layer including metal (IV) -silicate-phosphate (MSP) represented by Formula 1 is formed on one or both surfaces of a gas diffusion layer, and a fuel inducing an electrochemical reaction by the action of a catalyst. As the battery electrode, there are a cathode and an anode.

Since the electrode of the present invention includes a metal (IV) -silicate-phosphate (MSP), a stable hydrogen ion conduction channel is formed between the catalyst-metal (IV) silicate phosphate (MSP) and thus high hydrogen ion conductivity at low humidity conditions. Indicates.

The catalyst layer of the electrode is a binder component for fixing and connecting the catalyst and the metal (IV) -silicate-phosphate (MSP) on the gas diffusion layer, and may include a conventional hydrogen ion conductive organic polymer known in the art. The hydrogen ion conductive organic polymer is not particularly limited as long as it is a polymer electrolyte that may be included as a component of the electrolyte membrane. Examples thereof are the same as the examples of the organic polymer described above as a component of the electrolyte membrane, but are not limited thereto.

In particular, the organic polymer is at least one hydrogen ion exchange group selected from the group consisting of sulfonic acid groups, phosphoric acid groups, hydroxy groups, and carboxylic acid groups to form mutually stable hydrogen ion conducting channels between the catalyst-polymer-metal silicate phosphate (MSP). Preference is given to organic polymers having

The metal (IV) -silicate-phosphate (MSP) content in the catalyst layer is not particularly limited as long as it can form an electrode due to the coating on the gas diffusion layer and exhibits excellent physical properties as described above. 0.1 to 1000 parts by weight, preferably 1 to 100 parts by weight, based on 100 parts by weight of the organic polymer used in the.

Electrodes of the present invention can be prepared according to conventional methods known in the art. For example, a catalyst layer may be formed by applying and drying a mixed solution including a catalyst, an organic polymer, a solvent for enhancing catalyst dispersion, and a metal (IV) -silicate-phosphate (MSP) to the gas diffusion layer. The electrode can be produced by the above method.

As another example, a mixed solution including a catalyst, an organic polymer, a solvent for enhancing catalyst dispersion, and a metal (IV) -silicate precursor solution may be applied to a gas diffusion layer and dried, followed by phosphoric acid treatment. In this case, the metal (IV) -silicate precursor solution may be prepared by the same method as described above in the preparation of the organic / inorganic composite electrolyte membrane. In addition, the process of the phosphoric acid treatment may be performed by putting the electrode formed through the drying process in a phosphoric acid solution, washing.

The method of coating the mixed solution on the gas diffusion layer includes, but is not limited to, printing, spraying, rolling, or brushing.

The gas diffusion layer is not particularly limited as long as it is a substrate having conductivity and porosity of 80% or more, and examples thereof include porous carbon paper or carbon cloth.

The catalyst used in the cathode catalyst layer of the electrode may be in the form of a noble metal catalyst powder, such as Pt, W, Ru, Mo, Pd or a combination thereof evenly supported on the surface of the conductive carbon powder, increasing the specific surface area of the catalyst In order to improve the reaction efficiency, carbon powder in a very finely divided form, such as carbon black, carbon nanotubes, and carbon nanohorns, may be used. In addition, the catalyst used in the catalyst layer of the anode may generally use a powder of platinum or a platinum-based alloy such as Pt / Ru. However, it is not limited thereto.

Non-limiting examples of solvents used to enhance the catalyst dispersion in electrode preparation include water, butanol, isopropyl alcohol (IPA), methanol, ethanol, n-propanol, n-butyl acetate, ethylene glycol, and the like. In addition, these solvent can be used individually or in mixture of 2 or more types.

<Membrane Electrode Assembly and Fuel Cell>

The membrane electrode assembly (MEA) of the present invention is a cathode; Anode; And an electrolyte membrane positioned between the cathode and the anode, wherein (i) the electrolyte membrane includes the organic / inorganic composite electrolyte membrane of the present invention; Or (ii) the cathode, or anode, or both of the electrodes of the invention described above; Or (i) and (ii) above.

A membrane electrode assembly (MEA) refers to a conjugate of electrodes (cathodes and anodes) in which an electrochemical catalytic reaction between fuel and air occurs and a polymer membrane in which hydrogen ions are transferred, and a single electrode bonded to an electrode (cathodes and anodes) and an electrolyte membrane. It is an integrated unit of. The present invention includes the metal (IV) -silicate-phosphate (MSP) in at least one of the electrolyte membrane and the electrode, thereby constituting a membrane electrode assembly having excellent operating characteristics under low humidity conditions.

The membrane electrode assembly of the present invention is in a form such that the catalyst layer of the anode and the catalyst layer of the cathode contact the electrolyte membrane, and can be prepared according to conventional methods known in the art. In one example, the cathode; Anode; And it may be prepared by thermal compression at 100 to 400 ℃ in the state in which the electrolyte membrane located between the cathode and the anode in close contact.

In addition, the present invention provides a fuel cell including the membrane electrode assembly (MEA).

The fuel cell may be manufactured according to conventional methods known in the art using the membrane electrode assembly (MEA) of the present invention. For example, it may be prepared by configuring a membrane electrode assembly (MEA) and a bipolar plate (bipolar plate) prepared above.

The fuel cell may be a polymer electrolyte fuel cell, a direct liquid fuel cell, a direct methanol fuel cell, a direct formic acid fuel cell, a direct ethanol fuel cell, or a direct dimethyl ether fuel cell.

Hereinafter, described in detail through preferred embodiments to help understand the present invention. However, the following examples are merely to illustrate the present invention and the present invention is not limited by the following examples.

Example 1 Zirconium Silicate Precursor Solution and Zirconium Silicate Phosphate [ZrSiO ₂ (HPO ₄ ) ₂ NH ₂ O] Manufacture

In ethyl alcohol, Zr (O (CH ₂ ) ₃ CH ₃ ) ₄ and Si (OC ₂ H ₅ ) ₄ and acetyl acetone were converted into Zr (O (CH ₂ ) ₃ CH ₃ ) ₄ : Si (OC ₂ H ₅ ) ₄ : A zirconium silicate precursor solution was prepared by adding a mole ratio of acetyl acetone: water = 1: 1: 1: 4 and adding 35% hydrochloric acid.

Specifically, first, 5 g of Zr (O (CH ₂ ) ₃ CH ₃ ) ₄ is added to a mixed solution of acetyl acetone and 10 g of ethyl alcohol in an amount corresponding to the aforementioned molar ratio, and 0.5 ml of 35% hydrochloric acid is added. After the addition, the mixture was stirred at room temperature for one day. Subsequently, Si (OC ₂ H ₅ ) ₄ in an amount corresponding to the aforementioned molar ratio was added to the mixture, and then slowly added 0.5 ml of 35% hydrochloric acid and water in an amount corresponding to the aforementioned molar ratio. Stirring about to prepare a zirconium silicate precursor solution.

An excess of phosphoric acid was added to the prepared zirconium silicate precursor solution and mixed to prepare a zirconium silicate phosphate solution. The zirconium silicate phosphate solution was then dried at 80 ° C. for 5 hours to obtain zirconium silicate phosphate powder.

Manufactured The crystal structure of the zirconium silicate phosphate powder was analyzed by using an X-ray diffraction spectrometer (X-ray Diffraction, equipment name: Bruker D4 Endeavor, Cuk radiation), and the graph is shown in FIG. 1. In Fig. 1, θ of the horizontal axis is an angle between the X-ray and the crystal plane, and the vertical axis is Intensity. In addition, as a result of inputting the chemical formula Zr (IV) SiO ₂ (HPO ₄ ) ₂ using EVA, which is an application of XRD, a graph coinciding with the peak value shown in FIG. Referring to FIG. 1, the space group has a monoclinic form and shows Lattice constants (a = 9.097 Å, b = 5.307 Å, c = 16.284 Å).

Example 2 Preparation of a Composite Solution (40-60 wt%) of Sulfonated Polyether Ether Ketone / Zirconium Silicate Precusor

8 g of sulfonated polyether ether ketone was added to the 8 g zirconium silicate precursor solution prepared during the process of Example 1, and stirred at room temperature for 3 hours to give a solution of the composite of sulfonated polyether ether ketone / zirconium silicate precursor. Was prepared.

Example 3 Preparation of Organic / Inorganic Composite Electrolyte Membrane (Sample 1) Containing Sulfonated Polyether Ether Ketone / Zirconium Silicate Phosphate

A film of the composite solution of the sulfonated polyether ether ketone / zirconium silicate precursor prepared in Example 2 was prepared by solution pouring. The solution was poured onto a glass plate or a polymer film used as a support for film production, and then the solution was applied to a predetermined thickness using a doctor blade. The coated glass plate was kept in a constant temperature and humidity chamber at 80 ° C. for about 8 hours to widen the solution, and then the formed composite electrolyte membrane was separated from the support. The separated composite electrolyte membrane was placed in 2 M phosphoric acid, stirred at 80 ° C. for 6 hours, and then washed with distilled water to prepare an organic / inorganic composite electrolyte membrane (Sample 1) including sulfonated polyether ether ketone / zirconium silicate phosphate. It was.

Example 4: Preparation of Zirconium Silicate Phosphate-Containing Electrode

The catalyst (Pt / C), distilled water, sulfonated polyether ether ketone electrolyte solution (5%), the zirconium silicate (MS) precursor solution prepared in Example 1, and IPA (Isopropylalcohol) were prepared using Pt / C: H ₂ O: 5% Ionomer solution: MS : IPA = 1: 3: 6: 1: after stirring to mix together with 100 weight ratio, was applied to a gas diffusion layer (G as D iffusion L ayer, GDL) of the carbon cloth, Phosphoric acid treatment prepared the electrode.

Example 5 Preparation of Membrane Electrode Assembly

The catalyst (Pt / C), distilled water, sulfonated polyether ether ketone electrolyte solution (5%), and IPA (Isopropylalcohol) were added with Pt / C: H ₂ O: 5% Ionomer solution: IPA = 1: 3: 6: after stirring to mix together in a weight ratio of 100, it was applied to a gas diffusion layer (G as D iffusion L ayer, GDL) of the carbon cloth, and dried to prepare an electrode.

A membrane electrode assembly (MEA) was manufactured by bonding the prepared electrode and the electrolyte membrane prepared in Example 3.

Comparative Example 1: Preparation of membrane electrode assembly using Nafion electrolyte membrane (Sample 2)

A Nafion 112 membrane manufactured by Dupont was used, and the membrane electrode assembly was prepared by bonding the membrane to the electrode prepared in Example 5.

Comparative Example 2: Preparation of sulfonated polyether ether ketone electrolyte membrane (Sample 3) and membrane electrode assembly

A pure organic polymer electrolyte membrane (sample) was prepared in the same manner as in Example 3, except that sulfonated polyether ether ketone was used instead of the composite solution of sulfonated polyether ether ketone / zirconium silicate precursor prepared in Example 2. 3) was prepared.

In addition, the sulfonated polyether ether ketone electrolyte membrane was bonded to the electrode prepared in Example 5 to prepare a membrane electrode assembly.

Experimental Example 1: Ion Exchange Capacity Measurement

0.5 g of each of Nafion 112 electrolyte membrane of Comparative Example 1 (Dupont) and sulfonated polyether ether ketone electrolyte membrane of Comparative Example 2 was hydrated in ultrapure water at 100 ° C. for 2 hours, and then, It was supported for more than time to replace hydrogen ions (H ⁺ ) with sodium ions (Na ⁺ ). The substituted hydrogen ions (H ⁺ ) were titrated with 0.1 N NaOH standard solution, and the IEC value of the polymer membrane was calculated according to Equation 1 as the amount of NaOH used for the titration, and the results are shown in Table 1 below. .

[Equation 1]

IEC (-SO ₃ H mequiv./g)

= (Consumed NaOH standard solution (mL) × 0.1N) / weight of dried thin film (g)

Experimental Example 2: Measurement of hydrogen ion conductivity

A ZAHNER IM-6 Impedance Analyzer was used and by the Potentio-Static Four-Probe method in the frequency range of 1 Hz to 1 MHz, a temperature of 70 ° C. and a relative humidity of 40%, or a temperature of 70 ° C. and a relative humidity of 100% In each of the specimens 1 to 3 hydrogen ion conductivity was measured and the results are shown in Table 1.

Experimental Example 3: Methanol Permeability (MeOH crossover)

Organic / inorganic composite electrolyte membrane (Sample 1) comprising the sulfonated polyether ether ketone / zirconium silicate phosphate prepared in Example 3, Nafion 112 electrolyte membrane (Dupont) of Comparative Example 1 (Sample 2), and The methanol permeability of each sulfonated polyether ether ketone electrolyte membrane (Sample 3) of Comparative Example 2 was measured using a diffusion cell apparatus.

First, put 10 M aqueous methanol solution in the left cell, pure water in the right cell, insert the electrolyte membrane in the middle of the cell, and then measure the methanol concentration ( C ) in the right cell according to the time ( t ) obtained by sampling the solution in the right cell. _The methanol permeability was calculated from the change in _i ( t )). At this time, the methanol permeability (D _i and K _i) is to the electrolyte thickness (L) with the film exposure area (A) value, the volume (V), and methanol to the initial concentration (C _i0) value of the left cell of the right cell expression It was calculated by 2, the results are shown in Table 1 below.

[Equation 2]

_{C i (t) = {(} A and D _i and K _i and C _io) / V and L} × t

Electrolyte membrane IEC (meq / g) Hydrogen ion conductivity (S / cm) Methanol Permeability (㎠ / S) Relative Humidity 100% Relative Humidity 40% Specimen 1 (Example 3) 1.08 0.311 0.08 2.47 * 10 ^-7 Psalm 2 (Comparative Example 1) 0.91 0.139 0.02 2.67 * 10 ^-6 Psalm 3 (Comparative Example 2) 1.52 0.162 0.01 0.97 * 10 ^-6

According to Table 1, hydrogen of the organic / inorganic composite electrolyte membrane (Example 3) in which zirconium silicate phosphate was added to sulfonated polyether ether ketone when the electrolyte membranes of Example 3, Comparative Example 1 and Comparative Example 2 were compared It was confirmed that the ionic conductivity was greatly improved. In addition, it was confirmed that the organic / inorganic composite electrolyte membrane according to the present invention (Example 3) improved methanol permeability at a high temperature as compared to Nafion used in the conventional polymer membrane.

Experimental Example 4: Cell Performance Analysis

Performance was confirmed by constructing a unit battery cell from the membrane electrode assembly (MEA) prepared in Example 5, Comparative Example 1 and Comparative Example 2.

Arbin's PEMFC test station was used. The cell temperature was 70 ° C, the cell effective area was 25cm ² , the flow rate of hydrogen was 200cc / m, and the flow rate of air was 1000cc / m. The cell was operated at atmospheric pressure, and the cell performance was confirmed at a relative humidity of 40% and a cell temperature of 70 ° C., and the results are shown in FIG. 2.

2, it can be seen that the fuel cell including the organic / inorganic composite electrolyte membrane of the present invention exhibits excellent performance even under high temperature and low humidity conditions through high hydrogen ion conductivity retention.

The organic / inorganic composite electrolyte membrane according to the present invention not only has high hydrogen ion conductivity but also excellent chemical resistance and thermal stability, and includes a membrane electrode assembly composed of the organic / inorganic composite electrolyte membrane and / or the electrode according to the present invention. Fuel cells can achieve improved performance under low humidity conditions.

Although described in detail above with reference to the specific embodiments of the present invention, it will be apparent to those skilled in the art that various changes and modifications can be made within the scope and spirit of the present invention, and such modifications and modifications belong to the appended claims. It is also natural.

Claims (22)

Metal (IV) -silicate-phosphate (MSP) represented by the following formula (1). [Formula 1] M (Ⅳ) SiO ₂ (HPO ₄ ) ₂ ㆍ n H ₂ O In Formula 1, M is at least one metal selected from the group consisting of Group IVA and Group IVB metals. 2. Metal (IV) -silicate-phosphate according to claim 1, wherein M is Zr. 2. A compound according to claim 1 comprising: (a) a metal (IV) alkoxide or metal (IV) salt; Ligands that coordinate with metals; And mixing an acid; (b) silicon alkoxide in the mixture of step (a); And adding an acid to prepare a metal (IV) -silicate precursor solution; And (c) a metal (IV) -silicate-phosphate, which is prepared by adding and mixing phosphoric acid or polyphosphoric acid to the metal (IV) -silicate precursor solution. An organic / inorganic composite electrolyte membrane comprising an organic polymer and a metal (IV) -silicate-phosphate (MSP) represented by Formula 1 below. [Formula 1] M (Ⅳ) SiO ₂ (HPO ₄ ) ₂ ㆍ n H ₂ O In Formula 1, M is at least one metal selected from the group consisting of Group IVA and Group IVB metals. The organic / inorganic composite electrolyte membrane according to claim 4, wherein the metal (IV) -silicate-phosphate (MSP) is dispersed in the organic polymer matrix. The method of claim 4, wherein the organic polymer is polyaryleneether (PAE), polyetheretherketone (PEEK), polyetherethersulfone (polyetherethersulfone, PEES), polytetrafluoroethylene (PTFE), Polyvinylidenefluoride (PVDF), Nafion, polyazole, polyvinylalcohol (PVA), polyphenylene oxide, polyphenylene sulfide, At least one polymer selected from the group consisting of polysulfone, polycarbonate, polystyrene, polyimide, polyamide, polyquinoxaline, (phosphated) polyphosphazene and polybenzimidazole Organic / inorganic composite electrolyte membrane. The organic / inorganic composite electrolyte membrane of claim 6, wherein the organic polymer is an organic polymer having at least one hydrogen ion exchange group selected from the group consisting of a sulfonic acid group, a phosphoric acid group, a hydroxyl group, and a carboxylic acid group. The organic / inorganic composite electrolyte membrane of claim 4, wherein the metal (IV) -silicate-phosphate is included in an amount of 0.1 to 1000 parts by weight based on 100 parts by weight of the organic polymer. According to claim 4, (i) the organic polymer or a solution thereof; And mixing the metal (IV) -silicate-phosphate or a solution thereof to prepare a mixture thereof. And (ii) an organic / inorganic composite electrolyte membrane, characterized in that it comprises the step of forming a membrane using the mixture. According to claim 4, (i) the organic polymer or a solution thereof; And mixing the metal (IV) -silicate precursor solution to prepare a mixture thereof; And (ii) forming an membrane using the mixture, followed by phosphoric acid treatment. The method of claim 10, wherein the metal (IV) -silicate precursor solution is (a) metal (IV) alkoxides or metal (IV) salts; Ligands that coordinate with metals; And mixing an acid; And (b) silicon alkoxide in the mixture of step (a); And adding an acid to the organic / inorganic composite electrolyte membrane. An electrode having a catalyst layer including metal (IV) -silicate-phosphate (MSP) represented by the following Chemical Formula 1 on one or both surfaces of a gas diffusion layer. [Formula 1] M (Ⅳ) SiO ₂ (HPO ₄ ) ₂ ㆍ n H ₂ O In Formula 1, M is at least one metal selected from the group consisting of Group IVA and Group IVB metals. The electrode of claim 12, wherein the catalyst layer comprises a hydrogen ion conductive organic polymer that fixes and couples a catalyst and a metal (IV) -silicate-phosphate (MSP) onto a gas diffusion layer. The electrode according to claim 13, wherein the organic polymer is an organic polymer having at least one hydrogen ion exchange group selected from the group consisting of sulfonic acid groups, phosphoric acid groups, hydroxyl groups, and carboxylic acid groups. The electrode of claim 12, wherein the metal (IV) -silicate-phosphate is included in an amount of 0.1 to 1000 parts by weight based on 100 parts by weight of the organic polymer used in the catalyst layer. The electrode according to claim 12, wherein the electrode is prepared by applying and drying a mixed solution comprising a catalyst, an organic polymer, a solvent, and the metal (IV) -silicate-phosphate to a gas diffusion layer. The electrode according to claim 12, wherein a mixed solution comprising a catalyst, an organic polymer, a solvent, and a metal (IV) -silicate precursor solution is applied to a gas diffusion layer and dried, followed by phosphoric acid treatment. 18. The method of claim 17, wherein the metal (IV) -silicate precursor solution is (a) metal (IV) alkoxides or metal (IV) salts; Ligands that coordinate with metals; And mixing an acid; And (b) silicon alkoxide in the mixture of step (a); And adding an acid. Cathode; Anode; And an electrolyte membrane positioned between the cathode and the anode. (i) the electrolyte membrane is an organic / inorganic composite electrolyte membrane according to any one of claims 4 to 11; Or (ii) the cathode, or anode, or both of which comprise the electrode of any one of claims 12-18; Or a membrane electrode assembly (MEA), characterized in that both (i) and (ii). 20. The device of claim 19, further comprising: the cathode; Anode; And a membrane electrode assembly which is manufactured by thermal compression at 100 to 400 ° C. in a state in which an electrolyte membrane positioned between the cathode and the anode is in close contact. A fuel cell comprising the membrane electrode assembly of claim 19. 22. The fuel cell of claim 21, wherein the fuel cell is a polymer electrolyte fuel cell, a direct liquid fuel cell, a direct methanol fuel cell, a direct formic acid fuel cell, a direct ethanol fuel cell, or a direct dimethyl ether fuel cell.

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