KR101150210B1 - Fibershaped hollow electrode, membrane-electrode assembly comprising the same, and its preparation method - Google Patents

Abstract

The present invention relates to a fibrous pupil having a hollow support, and a fibrous pupil electrode comprising an active catalyst supported on the surface of the fibrous carrier, a membrane-electrode assembly including the same, an electrolytic device or a fuel cell, and a method of manufacturing the same. It is about. The pupil electrode according to the present invention shows very excellent physical properties in terms of catalyst introduction yield, by-product generation amount, catalyst layer uniformity, electrode durability, electrochemical properties, and electrolytic ability.

Fibrous pupil, electrode-electrolyte assembly, hydroelectrolyzer, fuel cell

Description

Fiber-shaped pupil electrode, membrane-electrode assembly including the same and method for manufacturing the same {Fibershaped hollow electrode, membrane-electrode assembly comprising the same, and its preparation method}

The present invention relates to a fibrous pupil having a hollow support, and a fibrous pupil electrode comprising an active catalyst supported on the surface of the fibrous carrier, a membrane-electrode assembly including the same, an electrolytic device or a fuel cell, and a method of manufacturing the same. It is about.

An electrochemical cell is an energy conversion device that is divided into an electrolysis cell that produces oxygen or hydrogen gas using a reactant such as water and a fuel cell that generates electricity using oxygen and hydrogen fuel.

In general, an electrochemical cell includes an ion exchange membrane separating an reactant produced by an electrochemical reaction at an anode and a cathode, an anode oxidizing a reactant, a cathode reducing a reactant, a separator separating other unit cells, and sealing purposes. It consists of a gasket.

The electrode, which is a key component of the electrochemical cell, has an electrode catalyst layer supported on a carrier positioned on a substrate, and the electrode catalyst layer is generally a platinum group or a group thereof as an electrochemical catalyst suitable for oxidation and reduction reactions. Consists of alloys or oxides. The most representative industrial electrode is DSE (Dimensionally Stable Electrode) coated with an electrode catalyst / carrier such as RuO2 / TiO2 or (RuO2, IrO2) / TiO2 on a titanium substrate. Due to its high electrode catalytic activity, it has been applied to brine electrolysis or water electrolysis processes. Here, the base material does not participate in the electrode reaction and functions to fix the electrode catalyst layer.

In addition, the electrode base material is determined in consideration of the bonding with the electrode catalyst applied on the base material, mainly titanium (tanitanium), tantalum (montal), monel (nickel), stainless steel (stainless steel), etc. Is being used. The shape of the electrode base material has a two-dimensional or three-dimensional porous structure to facilitate the inflow and outflow of the reactant electrolyte and the product gas. The two-dimensional shape includes a punched, expanded, mesh, diamond shape hole, the three-dimensional shape by laminating the two-dimensional electrode, There are three-dimensional shapes of fibrous, granular, and particulate powders.

The existing representative method for forming an electrode catalyst / carrier on a base material is wet processing. This is because the homogeneous liquid catalyst mixture consisting of chloride, alkoxide, and chloride of the electrocatalyst precursor is dispersed on the base material by painting, brushing, or dipping on the base material, and then thermally decomposing it. That's how.

In the electrolysis industry, in recent years, in order to maximize productivity and operability, a large area of ² m ² or more and a high current density operation of 10 kA / m ² or more have been pursued. As a result, the demand for improving performance and durability (for example, high electrocatalyst loading per unit area and uniform catalyst loading) is increasing.

With a large area of more than 2m ² , a suitable catalyst loading of 10kA / m ² for current density operation is required to be more than 2,400μg / cm ² , but the conventional method requires that the amount of electrode catalyst loading per unit area is 240μg / cm ² . In the current density operating conditions of 10kA / m ² or more, the life of the electrode is reduced, the electrochemically active capacity is disadvantageous. S. Pizzini (S. Pizzini, G. Buzzanca, C. Mari, L. Rossi and S. Torchio, Mat. Res. Bull., 7, 449 (1972)), G. Barrel (G. Barrel, J. Guitton, C. Montella, and F. Vergara, Surface Technology), 6, 39 (1977)), K. Kameyama, K. Tsukada, K. Yahikozawa, and Y. Takasu, J. Electrochem. Soc., 140, 966 (1993), etc., reported that the electrode catalyst formation method applying the conventional liquid phase liquid catalyst mixture is greatly affected by the pretreatment process, and the electrode performance is not constant.

In addition, in the conventional technology, there are few examples showing improved physical properties in terms of catalyst introduction yield, by-product generation amount, catalyst layer uniformity, electrode durability, electrochemical properties, and electrolytic ability, and thus, there is a situation in which technology development is required.

Therefore, in order to solve such a conventional problem, the present invention is to provide an electrode, and a method for producing the same, which shows overall improved physical properties in terms of catalyst introduction yield, catalyst layer uniformity, electrochemical properties, and electrolytic performance.

In order to solve the above problems, the present invention provides a fibrous pupil electrode comprising an empty fibrous carrier, and an active catalyst supported on the surface of the fibrous carrier.

According to one embodiment, the fibrous pupil electrode has a thickness of 1 ~ 50 μm.

According to another embodiment, the electrochemical catalyst is uniformly distributed in the thickness of 100 ~ 300 nm on the pupil mother material.

According to another embodiment, the loading amount of the electrochemical catalyst per unit area of the pupil electrode is 2,400 μg / cm ² or more.

According to another embodiment, the pupil carrier is selected from gold, silver, chromium, iron, titanium, manganese, cobalt, nickel, molybdenum, tungsten, aluminum, silicon, zinc, tin, mixtures thereof and oxides thereof. In particular, the use of a titanium-niobium composite oxide as a material for the carrier constituting the pupil electrode is preferable in further maximizing the physical properties exemplified by the effects of the present invention.

According to another embodiment, the active catalyst is selected from Ta, Pb, Ru, Ir, Sn, Ba, Ag, Pt, Pb, mixtures thereof and oxides thereof.

According to another aspect, the present invention

(a) obtaining a fibrous carrier by aging by adding a carrier precursor to a polymer solution in which a fibrous polymer, a pH adjuster, and an emulsifier are dissolved,

(b) obtaining a fibrous electrode by adding and dispersing an active catalyst precursor in a solution containing the fibrous carrier,

(c) providing a fibrous pupil electrode manufacturing method comprising pyrolyzing the fibrous electrode to obtain a fibrous pupil electrode. According to one embodiment, the fibrous polymer is PS fiber, polyamide fiber, poly It is selected from ester fiber. According to another embodiment, the pH adjusting agent is selected from hydrochloric acid, nitric acid, sulfuric acid.

According to another embodiment, the active catalyst precursor is selected from SnCl ₂ , H ₂ PtCl ₆ , H ₂ IrCl ₆ , RuCl ₄ , H ₂ IrCl ₆ and RuCl ₄ .

According to another embodiment, the emulsifier uses cetyltrimethylammonium.

According to another embodiment, the carrier precursor is Ti (SO ₄ ) ₂ .

According to another embodiment, titanium alkoxide may be further used in the step (a) of the method of manufacturing a fibrous pupil electrode of the present invention.

Titanium alkoxide may be further used in the step (a) of the method for producing a fibrous pupil electrode of the present invention. According to another embodiment, the carrier precursor may be used by mixing titanium alkoxide and niobium alkoxide.

According to another aspect, the present invention provides a fibrous pupil electrode made according to the present invention.

According to another aspect, the present invention provides a membrane-electrode assembly, a hydroelectrolyzer, and a fuel cell including the fibrous pupil electrode of the present invention.

The pupil electrode according to the present invention shows very excellent physical properties in terms of catalyst introduction yield, by-product generation amount, catalyst layer uniformity, electrode durability, electrochemical properties, and electrolytic ability. In addition, the performance is consistent and the performance deviation is small, so the reproducibility is excellent.

Manufacturing example : PS  Textile manufacturing

Polystyrene having a weight average molecular weight of 190,000 was dissolved in dimethylformamide (DMF) to prepare a mixed solution of polystyrene / dimethylformamide. Polystyrene fibers (PS fibers) having a diameter were prepared by spinning a mixed solution of polystyrene / dimethylformamide into an electrospinning apparatus by a conventional method. By adjusting spinning conditions and the like, the diameter of the polystyrene fiber was adjusted in the range of 1 to 50 μm.

compare Manufacturing example Spherical PS  Particle manufacturing

0.2 g of potassium persulfate was added to 160 ml of distilled water, and the mixture was stirred at 300 rpm while maintaining at 80 ° C. 54 ml of styrene and 2 ml of methacrylic acid were added to the solution and reacted for 24 hours in a nitrogen atmosphere to prepare spherical PS particles having a diameter of 10 to 50 µm.

Example  1: fiber type SnO ₂  Electrode manufacturing

PS  On fiber Base material  fixing

As a precursor of TiO ₂ , 32 ml of distilled water, 0.8 ml hydrochloric acid and 1.98 ml of cetyltrimethylammonium chloride were added to 1.0 ml of the solution of the fibrous polymer prepared in Preparation Example using Ti (SO ₄ ) ₂ solution. After addition and dispersion by ultrasonic for 30 minutes, 0.18 ml of Ti (SO ₄ ) ₂ solution is added dropwise to the solution. The solution was aged for 12 hours at 70 ℃, cooled to room temperature and centrifuged to obtain a solid sample.

Active catalyst SnO ₂  fixing

In the above-described fibrous TiO ₂ , the content of Sn was carried up to 20, 40, and 60 wt% to prepare a fibrous electrode of the pupil. The precursor of Sn used here was used as SnCl ₂ . 32 ml of distilled water, 0.8 ml hydrochloric acid, and 1.98 ml tin chloride (SnCl ₂ ) were added to the fibrous TiO ₂ prepared above to uniformly distribute the catalyst on the support, followed by dispersion for 30 minutes with ultrasonic waves. The solution was dried at 70 ° C. for 12 hours and then centrifuged to obtain a solid sample. And a solid sample is thermally decomposed at 200-300 degreeC (1 degree-C / min) for 4 hours, and a fibrous electrode is manufactured.

Electrode or Fuel Cell Electrode Manufacturing

In addition, the fibrous pupil electrode, iridium chloride, tin chloride, and titanium isopropoxide were used as starting materials in a weight ratio of 0.3: 0.2: 0.2: 0.3, and the amount of the pupil electrode was approximately 240 μg / cm ² (0.24 mg / cm). cm ² ). First, dilute titanium isopropoxide in alcohol at a molar ratio of 50 to 100 times, and then add a fibrous pupil electrode, iridium chloride, and tin chloride to the alcohol. Ultrapure water and hydrochloric acid were added thereto to perform a hydrolysis reaction and a polycondensation reaction to prepare a catalyst slurry. The catalyst slurry was dispersed in a 3 cm wide and 3 cm long titanium matrix, dried at 100 ° C. using a hot air blower, and calcined at 450-600 ° C. for 10 minutes. This was repeated 10 times to obtain an electrode on which a catalyst 2,400 μg / cm ² (2.4 mg / cm ² ) was supported. Then, the mixture was calcined at 450-600 ° C. for 2 hours to prepare an electrode for a hydroelectrolyte or a fuel cell.

Example  2-5: Fibrous Electrode Fabrication

Example 2-5 was conducted according to Example 1, but instead of Ti (SO ₄ ) ₂ as a catalyst precursor, H ₂ PtCl ₆ , H ₂ IrCl ₆ , RuCl ₄ and H ₂ IrCl ₆ and RuCl _{4 in the} same weight ratio Using respectively, a fibrous Pt electrode, a fibrous IrO ₂ electrode, a RuCl ₄ electrode, and a fibrous IrO ₂ -RuO ₂ electrode were prepared.

Example  6: titanium Alkoxide  Using fibrous electrode manufacturing

The experiment was carried out according to Example 1, but using a titanium methoxide in the step of fixing the carrier to the PS fibers to prepare a fibrous electrode.

Comparative example  1: Manufacture of spherical electrode of pupil

The experiment was conducted in the same manner as in Example 1, but instead of using PS fibers, spherical PS particles prepared in Comparative Preparation Example were used to prepare a pupil instead of a fibrous electrode.

Comparative example  2-3

The experiment was conducted in the same manner as in Example 1, but instead of Ti (SO ₄ ) ₂ , titanium methoxide and titanium ethoxide were used as precursors to prepare a fibrous electrode.

Comparative example  4

The experiment was conducted as in Example 1, but a fibrous electrode was prepared using ammonium lauryl sulfate instead of cetyltrimethylammonium chloride as an emulsifier (surfactant).

Experimental Example  1-5

It was confirmed that about 2,500 µg / cm 2 of catalyst was introduced to the pupil electrode surface prepared in Example 1, and some by-products were produced. It was confirmed that the catalyst was introduced relatively uniformly with a thickness of about 150-180 nm.

An electrochemical evaluation was performed to investigate the performance of the electrode. It was found that the voltage-to-current density was about 10 mA / cm 2 at 1.7 V, indicating excellent electrochemical properties.

The electrode was used as a positive electrode, and the platinum electrode was used as the negative electrode, and the membrane between the positive electrode and the negative electrode was Nafion 117, and water was electrolyzed under 50 ° C. temperature and the gap between the positive electrode and the negative electrode under zero gap conditions. As a result of measuring the current density versus the electrolytic voltage, it was confirmed that the slope of the current density versus the voltage curve was relatively low, such as showing an electrolytic voltage of about 1.5 V at a current density of 10 mA / cm 2, and thus showed excellent electrolytic ability.

Similar evaluation results were obtained for the pupil electrodes prepared in Examples 2 to 5.

Experimental Example  6

As a result of evaluating the physical properties of the fibrous pupil electrode prepared in Example 6 as in Experimental Example 1, a current of 15 mA / cm 2 at a yield of 2,700 ㎍ / ㎠, catalyst layer thickness of 160-180 nm, and 1.7 V was introduced. The electrolytic voltage of about 1.3 V was obtained at the density and current density of 10 mA / cm 2, resulting in improved physical properties.

Comparative Experimental Example  One

As a result of evaluating the physical properties of the fibrous pupil electrode prepared in Comparative Example 1 as in Experimental Example 1, a current of 7 mA / cm 2 at a yield of 2,400 ㎍ / ㎠, catalyst layer thickness 140-200 nm, and 1.7 V was introduced. It was confirmed that an electrolytic voltage of about 2 V was observed at the density and the current density of 10 mA / cm 2.

Comparative Experimental Example  2-3

As a result of evaluating the physical properties of the fibrous pupil electrode prepared in Comparative Example 2 as in Experimental Example 1, a current of 5 mA / cm 2 at a yield of 1,900 µg / cm 2, catalyst layer thickness of 80-150 nm and 1.7 V was introduced. It was confirmed that the electrolyte voltage of about 2.4 V was observed at the density and current density of 10 mA / cm 2. Similar results were confirmed for the electrode prepared in Comparative Example 3.

Comparative Experimental Example  4

As a result of evaluating the physical properties of the fibrous pupil electrode prepared in Comparative Example 4 as in Experimental Example 1, a current of 3 mA / cm 2 at a yield of 1,800 µg / cm 2, catalyst layer thickness of 60-250 nm, and 1.7 V was introduced. It was confirmed that an electrolytic voltage of about 2.5 V was observed at a density and a current density of 10 mA / cm 2.

1 is a schematic diagram of a fibrous pupil electrode prepared using polystyrene fibers as a base material, and FIG. 2 is a schematic diagram of an active catalyst coated on the surface of the fibrous pupil electrode.

3 and 4 are actual pictures of a fibrous pupil electrode and a fibrous pupil electrode coated with a catalyst, respectively.

Claims (13)

delete delete delete delete delete (a) obtaining a fibrous carrier by aging by adding Ti (SO ₄ ) ₂ , a precursor of the carrier, to a polymer solution in which a fibrous polymer, a pH adjuster, and an emulsifier are dissolved, (b) obtaining a fibrous electrode by adding and dispersing an active catalyst precursor in a solution containing the fibrous carrier, (C) a method of producing a fibrous pupil electrode comprising the step of obtaining a fibrous pupil electrode by thermal decomposition of the fibrous electrode. The method of claim 6, wherein the fibrous polymer is selected from PS fibers, polyamide fibers, polyester fibers; The pH adjusting agent is selected from hydrochloric acid, nitric acid, sulfuric acid; The active catalyst precursor is selected from SnCl 2, H 2 PtCl 6, H 2 IrCl 6, RuCl 4, H 2 IrCl 6 and RuCl 4; The emulsifier is a fibrous pupil electrode manufacturing method characterized by using cetyltrimethylammonium. delete 7. The method of claim 6, wherein the titanium alkoxide is further used in the step (a). delete delete delete delete

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