High-crystalline carbon black and method for producing the same

Abstract

The present invention relates to highly crystalline carbon black and a method for producing the same. More specifically, the present invention relates to highly crystalline carbon black that can be used as a catalyst support for fuel cells that require a high level of durability, and as a conductive material for various batteries, including secondary batteries, and a method for producing the same. More specifically, the present invention relates to highly crystalline carbon black having a microcrystal size (Lc) of 4.0 nm or more and a specific surface area (BET) of 50 to 150 m 2 and an oil absorption number (OAN) of 150 ml / 100 g or more, and a method for producing the same.

Description

Technical Field

[0001] The present invention relates to highly crystalline carbon black and a method for producing the same, and more specifically, to highly crystalline carbon black that can be used as a catalyst support for fuel cells and a conductive material for various batteries including secondary batteries, which require a high level of durability, and a method for producing the same.

Background Art

[0002] Carbon black means an aggregate of ultrafine spherical particles obtained by incomplete combustion of hydrocarbons or compounds containing carbon. Carbon black forms primary particles in a reactor, and these primary particles fuse with each other to form grape-like aggregates. On the other hand, carbon black can be roughly classified into acetylene black and furnace black. Among them, furnace black has the advantage of low cost, but has the disadvantage of being difficult to achieve high crystallinity compared to acetylene black.

[0003] Carbon black affects the quality of the materials used depending on the characteristics of its physical properties. The physical properties include crystallinity, specific surface area, structure, particle size, etc. The characteristics of carbon black can be adjusted by various post-treatments. Carbon black is used in various fields such as industrial paints, coating compositions, and various printed materials, and since it can have electrical properties, it is also used as a conductive material.

[0004] On the one hand, in recent years, fuel cells have been popularized with environmentally friendly energy. As a catalyst support for carrying a fuel cell catalyst (for example, a platinum catalyst) in a fuel cell, carbon black, which is a carbon material, is widely used. On the other hand, when driving a fuel cell electric vehicle, if the supply of hydrogen, which is the fuel, to the anode (also referred to as the "fuel electrode" or "hydrogen electrode") of the fuel cell is insufficient, the potential of the anode rises, and a reverse voltage (reverse voltage or reverse potential) phenomenon occurs in which the voltage of the entire fuel cell shows a negative value. As a result, the carbon black used as the catalyst support oxidizes gradually or rapidly, causing the electrode structure to collapse, thereby reducing the efficiency and lifespan of the fuel cell.

[0005] Therefore, it is necessary to improve the durability of the fuel cell anode against the reverse voltage phenomenon. For this reason, there is a need for technological development to improve the physical properties such as crystallinity, purity, and specific surface area of carbon black, which is the catalyst support.

Summary of the Invention

Problems to be Solved by the Invention

[0006] Focusing on the above-mentioned technical problems, an object of the present invention is to provide highly crystalline and highly pure carbon black and a method for producing the same.

[0007] Another object of the present invention is to provide a manufacturing apparatus and a manufacturing method capable of efficiently producing highly crystalline and highly pure carbon black.

[0008] Another object of the present invention is to provide a fuel cell anode formed of highly crystalline and highly pure carbon black, particularly a membrane electrode assembly (MEA) including the same, and a fuel cell including the same, which have significantly improved durability against the reverse voltage phenomenon.

Means for Solving the Problems

[0009] From the perspective of solving the above technical problems, according to one aspect of the present invention, the microcrystalline size (Lc) is 4.0 nm or more; the specific surface area (BET) is 50 to 150 m 2 / g; and an oil absorption number (OAN) of 150 ml / 100 g or more, high-crystalline carbon black can be provided. The high-crystalline carbon black may have a d-spacing (002) value, which is the average lattice spacing calculated from X-ray diffraction data, of 0.350 nm or less.

[0010] According to another aspect of the present invention, (a) a step of manufacturing furnace black with a microcrystalline size (Lc) of 1.0 to 2.0 nm; a specific surface area (BET) of 50 to 150 m 2 / g; and an oil absorption number (OAN) of 150 ml / 100 g or more, and (b) a step of subjecting the furnace black to high-temperature heat treatment at 1800 °C or higher to obtain high-crystalline carbon black, a manufacturing method of high-crystalline carbon black can be provided. According to the above manufacturing method, high-crystalline carbon black with a microcrystalline size (Lc) of 4.0 nm or more; a specific surface area (BET) of 50 to 150 m 2 / g; and an oil absorption number (OAN) of 150 ml / 100 g or more can be manufactured.

[0011] The furnace black in the above step (a) includes (i) at least one supply unit having an air supply unit and a fuel supply unit; (ii) a reaction unit into which the high-temperature combustion gas introduced through the supply unit flows; (iii) a discharge part (throat) formed by extending from the reaction unit and having a diameter smaller than that of the reaction unit; (iv) a neck part formed by extending from the discharge part and having a diameter larger than that of the discharge part; and (v) a casing formed by extending from the neck part and having a diameter larger than that of the neck part, and can be manufactured by a carbon black manufacturing apparatus that satisfies the following conditions (1) and (2).

[0012] (1): [(Length L of the neck) / (Diameter D of the neck)] > 3 (2): [(Diameter D' of the discharge part) / (Diameter D of the neck)] < 0.6

[0013] According to still another aspect of the present invention, there is provided an electrode comprising a catalyst support formed of highly crystalline carbon black having a microcrystalline size (Lc) of the present invention of 4.0 nm or more, a specific surface area (BET) of 50 to 150 m 2 / g, and an oil absorption number (OAN) of 150 ml / 100 g or more, and a catalyst supported on the catalyst support, and a membrane electrode assembly including an electrolyte membrane (membrane).

Advantages of the Invention

[0014] The highly crystalline carbon black of the present invention has very high crystallinity and purity and can have an appropriate specific surface area.

[0015] By applying the highly crystalline carbon black of the present invention as a catalyst support of a membrane electrode assembly for a fuel cell, the reverse voltage phenomenon of the fuel cell can be reduced or suppressed, and the durability of the fuel cell can be improved.

[0016] According to the method for producing highly crystalline carbon black of the present invention, carbon black having a very high level of crystallinity and purity can be efficiently produced. When the carbon black production apparatus of the present invention is applied, highly crystalline carbon black can be produced even when furnace black is used as a raw material.

[0017] The above-described advantages and the specific advantages of the present invention will be described and described while explaining the embodiments for carrying out the following invention.

Brief Description of the Drawings

[0018]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

[0019] The above-described objects, features, and advantages will be described in detail below with reference to the accompanying drawings, whereby those having ordinary knowledge in the technical field to which the present invention pertains can easily implement the technical idea of the present invention. In the description of the present invention, when it is determined that a specific description of a known technique related to the present invention obscures the gist of the present invention, the detailed description will be omitted. Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings. The same reference numerals in the drawings are used to indicate the same or similar components.

[0020] Among the contents not described in this specification, those that can be technically sufficiently analogized by an ordinary technician in this technical field will be omitted from the description.

[0021] When any configuration is arranged "above (or below)" a component in this specification or "on (or under)" a component, it means that not only is any configuration arranged in contact with the upper surface (or lower surface) of the above component, but other configurations may also be interposed between the above component and any configuration arranged "above (or below)" the above component.

[0022] As used herein, singular expressions include plural expressions unless the context clearly indicates otherwise. Terms such as "comprising," "having," or "including" in this application should not be construed as necessarily including all of the various components described in the specification. Some of these components may not be included, or additional components may be included.

[0023] Hereinafter, the highly crystalline carbon black according to the present invention will be described in detail.

[0024] Highly crystalline carbon black The highly crystalline carbon black of the present invention has a microcrystalline size (Lc) of 4.0 nm or more; a specific surface area (BET) of 50 to 150 m 2 / g; and an oil absorption number (OAN) of 150 ml / 100 g or more. The highly crystalline carbon black may have a d-spacing (002) value, which is the average lattice spacing calculated from X-ray diffraction data, of 0.350 nm or less, and the smaller the value, the more preferable.

[0025] <Crystallinity - Microcrystalline Size (Lc) and d-spacing (002) Which is the Average Lattice Spacing> The microcrystalline size (Lc) (which has the same meaning as "crystallite size," "crystal size," "longitudinal size of crystallite," "crystallite size in the c-axis direction," etc.), which is one factor indicating the crystallinity of a carbon material having a crystal structure, can be calculated by the Scherrer equation of the following [Equation 1] based on the X-ray diffraction data analyzed by X-ray diffraction (XRD) (analysis equipment: Panalytical Empyrean Alpha1).

[0026] [Equation 1] Scherrer equation: Lc = 0.89λ / (β·Cosθ)

[0027] 0.89 in the above [Equation 1] is the Scherrer constant, λ is the wavelength, θ is the angle at the peak of d-spacing (002), and β is the full width at half maximum (FWHM(002)) at the peak of d-spacing (002). The said d-spacing (002) means the average lattice spacing calculated from X-ray diffraction data and is measured from the data of X-ray diffraction (XRD).

[0028] On the other hand, although the target crystallinity varies depending on the application in which carbon black is used, since the carbon black of the present invention is preferably used as a catalyst support for use in a membrane electrode assembly of a fuel cell, a very high level of crystallinity is required for the catalyst support so as to have excellent durability even for repeated use and long-term use of the fuel cell.

[0029] Conventionally, the Lc value of carbon black used as a catalyst support is about 0.5 to 2.0 nm, and although it has a certain degree of crystallinity, there is a limit to achieving a very high level of crystallinity. Furthermore, it was very difficult to achieve these high crystallinities by using furnace black as a raw material. Therefore, the fact that the Lc value of the carbon black of the present invention has a value of 4.0 nm or more means that it has very excellent crystallinity compared to conventional carbon black, and in terms of using furnace black as a raw material, it can have advantages in terms of cost and process.

[0030] Therefore, the Lc of the highly crystalline carbon black of the present invention, which can exhibit excellent durability as a catalyst support for fuel cells, is preferably 4.0 nm or more, and although the upper limit is not particularly limited, it is preferably 10.0 nm or less.

[0031] Also, the value of d-spacing (002), which is the average lattice spacing, is preferably 0.350 nm or less.

[0032] <Specific surface area (BET)> As a carbon black serving as a catalyst support of the present invention, although it is required to have a high specific surface area so that a catalyst such as platinum (Pt) can be well supported and exhibit excellent catalytic activity, if the specific surface area is too high, the Lc value becomes small, resulting in low crystallinity and being in a trade-off relationship. Therefore, it is important to appropriately adjust the specific surface area and crystallinity according to the physical properties required for the product to which the carbon black is applied so that both can be achieved.

[0033] In particular, for application as a catalyst support that requires high durability, such as the anode electrode of a PEMFC or the cathode electrode of a PAFC, it is important that the specific surface area has an appropriate value and the Lc value is increased to achieve high crystallinity. From this perspective, the specific surface area (BET) is preferably in the range of 50 to 150 m 2 / g, more preferably in the range of 70 to 120 m 2 / g, and most preferably in the range of 70 to 100 m 2 / g.

[0034] On the other hand, the above specific surface area (BET) value can be measured by analyzing the specific surface area by nitrogen adsorption using the Brunauer-Emmett-Teller (BET) mathematical formula (analysis equipment: Micromeritics ASAP2460).

[0035] <Oil Absorption Number (OAN)> The oil absorption number (OAN) of carbon black means that the higher the value, the higher-dimensional structure the carbon black has. Carbon black particles with a high-dimensional structure can usually have excellent crystallinity. The oil absorption number is measured according to the analysis method based on ASTM D2414 (measuring the amount (ml / 100 g) of dibutyl phthalate oil adsorbed by 100 g of carbon black).

[0036] The higher the oil absorption number (OAN), the higher the electrical conductivity of carbon black and the lower the surface resistance. Therefore, in order to be used as a catalyst support or a conductive material for fuel cells, it is preferable to use carbon black having a high OAN.

[0037] From this perspective, the oil absorption number (OAN) of the carbon black of the present invention is preferably 150 ml / 100 g or more, and most preferably 180 ml / 100 g or more.

[0038] Hereinafter, the manufacturing method and manufacturing apparatus of the highly crystalline carbon black of the present invention will be described in detail.

[0039] Manufacturing Method and Manufacturing Apparatus of Highly Crystalline Carbon Black The manufacturing method of the highly crystalline carbon black of the present invention includes: (a) a step of manufacturing furnace black having a microcrystalline size (Lc) of 1.0 to 2.0 nm, a specific surface area (BET) of 50 to 150 m 2 / g, and an oil absorption number (OAN) of 150 ml / 100 g or more; and (b) a step of subjecting the furnace black to high-temperature heat treatment at 1800 °C or higher to obtain highly crystalline carbon black.

[0040] In order to improve the crystallinity of carbon black, a method of performing post-treatment such as high-temperature heat treatment is used. However, in the case of existing furnace black, usually, even when heat treatment is performed on the raw material carbon black, there is a limit point in significantly improving the crystallinity, particularly the microcrystalline size (Lc) value.

[0041] Therefore, as a result of intensive research, the present inventor has devised a manufacturing method that includes a step of subjecting furnace black to high-temperature heat treatment at 1800 °C or higher in order to improve the microcrystalline size (Lc) value, which is an important factor indicating crystallinity, and can significantly improve the crystallinity.

[0042] At this time, the furnace black before high-temperature heat treatment preferably has a specific surface area (BET) of 50 to 150 m 2 / g, which is the target physical property value in the present invention; and an oil absorption number (OAN) of 150 ml / 100 g or more, and those having a microcrystalline size (Lc) in the range of 1.0 to 2.0 nm can be used. By performing high-temperature heat treatment on these carbon blacks before heat treatment, the microcrystalline (Lc) value can be significantly improved.

[0043] Furthermore, the carbon black (the carbon black as the raw material) before the above heat treatment is preferably furnace black having advantages in process efficiency. The furnace black can be produced by introducing air, fuel oil, and hydrocarbon feedstock at a temperature of 1500 °C or higher under incomplete combustion conditions. The flow rate and type of each of the air, fuel oil, and hydrocarbon feedstock can be appropriately selected and adjusted. As long as the physical properties of the furnace black as the raw material of the present invention are satisfied, an ordinary technician can appropriately adjust the process conditions as needed.

[0044] Hereinafter, each stage of the production method of the present invention will be described.

[0045] <(a) stage> Specifically, in order to produce carbon black that simultaneously satisfies excellent crystallinity and appropriate specific surface area characteristics, the carbon black before heat treatment has a microcrystalline size (Lc) of 1.0 to 2.0 nm; a specific surface area (BET) of 50 to 150 m 2 / g, and an oil absorption number (OAN) of 150 ml / 100 g or more is preferable. Since the crystallinity mainly increases by high-temperature heat treatment (the specific surface area also increases slightly), it is advantageous that the specific surface area and the oil absorption number are within a range that satisfies the physical properties of the finally produced highly crystalline carbon black even before high-temperature heat treatment.

[0046] In order to easily produce furnace black having these physical properties, a carbon black production apparatus as shown in the production apparatus 10 of FIG. 1 can be used, which includes: (i) at least one supply unit 11 having an air supply unit 11a and a fuel supply unit 11b; (ii) a reaction unit 12 into which the high-temperature combustion gas introduced through the supply unit 11 flows; (iii) a throat 13 that extends from the reaction unit 12 and has a smaller diameter than the reaction unit; (iv) a neck 14 that extends from the throat 13 and has a larger diameter than the throat 13; and (v) a casing 15 that extends from the neck 14 and has a larger diameter than the neck 14, and satisfies the following conditions (1) and (2).

[0047] -Condition (1): [(Length L of the neck) / (Diameter D of the neck)] > 3 -Condition (2): [(Diameter D' of the throat) / (Diameter D of the neck)] < 0.6

[0048] If the ratio of [(Length L of the neck) / (Diameter D of the neck)] is 3 or less and condition (1) is not satisfied, or if [(Diameter D' of the throat) / (Diameter D of the neck)] exceeds 0.6 and condition (2) is not satisfied, the oil absorption number of the furnace black will be low, the specific surface area will also be somewhat low, and even if heat treatment is performed, it will be difficult to produce the physical properties of the final carbon black as intended in the present invention.

[0049] Also, the carbon black before the heat treatment in step (a) as described above can be produced by introducing air, fuel oil, and a hydrocarbon supply raw material and reacting them at a temperature of 1500 °C or higher, preferably 1500 to 1800 °C, under incomplete combustion conditions.

[0050] <(step (b))> The furnace black produced in the (a) stage can be heat-treated at a high temperature of 1800 °C or higher in an inert gas (nitrogen, argon, etc.) atmosphere to produce highly crystalline carbon black. Usually, when the Lc of the carbon black before heat treatment is approximately 1.0 to 2.0 nm, it is treated as having a certain degree of crystallinity, and heat treatment is usually carried out at a temperature of approximately 500 to 1000 °C.

[0051] However, in the present invention, even for carbon black with an Lc in the range of 1.0 to 2.0 nm, in order to significantly improve the crystallinity, a heat treatment scheme at a high temperature of 1800 °C or higher is adopted.

[0052] When the heat treatment temperature of the carbon black is 1800 °C or lower, it is difficult to produce carbon black with an Lc of 5.0 nm or more. As a result, when used as a catalyst support of the membrane electrode assembly of a fuel cell, it is difficult to prevent the reverse voltage phenomenon. Therefore, the heat treatment temperature of the carbon black of the present invention is preferably 1800 °C or higher, and more preferably 2000 °C or higher, but it can be selected in consideration of the efficiency of the process.

[0053] Hereinafter, an electrode including a catalyst support formed of the highly crystalline carbon black of the present invention and a catalyst supported on the catalyst support, and a membrane electrode assembly including an electrolyte membrane (membrane) will be described.

[0054] Membrane Electrode Assembly (MEA) Containing Highly Crystalline Carbon Black In recent years, as the interest in new renewable energy and environmental issues has been increasing, secondary batteries applying lithium ions and fuel cells that operate on the principle of converting chemical energy generated when hydrogen and oxygen combine to form water into electrical energy to obtain energy have become widely popular. These fuel cells can be classified into phosphoric acid fuel cells (PAFCs), alkaline fuel cells (AFCs), molten carbonate fuel cells (MCFCs), solid oxide fuel cells (SOFCs), proton exchange membrane fuel cells (PEMFCs), direct methanol fuel cells (DMFCs), etc. according to the electrolyte, type of fuel, and operating temperature.

[0055] The membrane electrode assembly (MEA) corresponding to the electrode unit of a fuel cell means an assembly of an electrode and an electrolyte membrane. The electrode includes an anode and a cathode, and each electrode is formed in a form in which a catalyst for a fuel cell is supported on a catalyst support. The anode and the cathode are adhered via an electrolyte membrane to form a membrane electrode assembly.

[0056] Depending on the type of fuel cell, the physical properties required for the anode and the cathode are different. For example, in the case of PEMFCs, very high durability is required for the anode, and in the case of PAFCs, very high durability is required for the cathode. Since the carbon black according to the present invention has high crystallinity, it has high resistance to corrosion and damage of the catalyst support generated during the operation of the fuel cell. Overall, the catalyst durability in the fuel cell MEA is also improved. In particular, the reverse voltage phenomenon can be prevented or suppressed, and as a result, the efficiency and life of the fuel cell can be increased.

[0057] Therefore, the highly crystalline carbon black according to the present invention can be applied to the catalyst support of the anode in the case of PEMFC and the cathode in the case of PAFC. Furthermore, it can also be used as a conductive material that requires high conductivity, high crystallinity, and high purity in secondary batteries using lithium ions, lead-acid batteries, alkaline batteries, etc.

[0058] The fuel cell catalyst of the MEA of the present invention can use those conventionally used. For example, it is preferably selected from platinum or a platinum alloy. When using a platinum alloy, the stability and activity as an electrode catalyst can be further imparted. The platinum alloy is preferably an alloy of platinum and one or more metals selected from the group consisting of platinum group metals (for example, ruthenium, rhodium, palladium, osmium, and iridium), gold, silver, chromium, iron, titanium, manganese, cobalt, nickel, molybdenum, tungsten, aluminum, silicon, zinc, and tin, and the platinum alloy can contain an intermetallic compound of a metal alloyed with platinum and platinum.

[0059] The electrolyte membrane of the MEA of the present invention is excellent in hydrogen ion conductivity, must not have electron conductivity, must have less fuel and water movement compared to ion movement, must have low or suppressed gas permeability, and requires physical properties with high shape stability and stability against oxidation-reduction.

[0060] Although the types of electrolyte membranes used vary depending on the type of fuel cell, for PEMFC fuel cells, a commercially available Nafion (trademark of Dupont) membrane such as a sulfonate perfluoropolymer can be used using a polymer electrolyte membrane. In particular, the type of electrolyte membrane in the present invention is not limited.

[0061] In particular, in the present invention, when used as a catalyst support for the anode of PEMFC, the demand for which has increased in recent years, it has been confirmed from experiments that it is excellent in suppressing the reverse voltage phenomenon and exhibits excellent results in the performance of MEA.

Mode for Carrying Out the Invention

[0062] Hereinafter, the structure and operation of the present invention will be described in more detail by way of preferred embodiments of the present invention. However, this is presented as a preferred exemplification of the present invention and is not to be construed as limiting the present invention in any way.

[0063] Example 1 and Comparative Example 1 - Production of Carbon Black before Heat Treatment In a production apparatus having the same structure as FIG. 1 of the present invention and having an L / D value of 3.3 and a D' / D value of 0.53 as shown in Table 1 below, air, fuel oil, and hydrocarbon supply raw materials, which are raw materials, were introduced and reacted under incomplete combustion conditions and at a temperature of 1500 °C to produce furnace black. At this time, the air flow rate was 4700 Nm 3 / hr, the fuel oil flow rate was 287 kg / hr, and the hydrocarbon supply raw material flow rate was 1910 kg / hr.

[0064] Although furnace black was produced under the same conditions and method as in Example 1 above, it differed in that a production apparatus having an L / D value of 1.9 and a D' / D value of 0.72 as shown in Table 1 below of the present invention was used.

[0065]

Table 1

[0066] For the furnace black of Example 1 and Comparative Example 1 above, the specific surface area, OAN, d-spacing (002), Lc, and surface resistance were measured by the following methods, and the results are shown in Table 2 below.

[0067]

Table 2

[0068] 1) Specific surface area: Analysis of specific surface area by nitrogen adsorption using the Brunauer - Emmett - Teller (BET) formula (Analysis equipment: Micromeritics ASAP2460) 2) OAN: Analyzed based on ASTM D2414: Measure the amount (ml / 100g) of dibutyl phthalate oil adsorbed by 100 g of carbon black 3) d - spacing (002) and Lc: Analyzed by X - ray diffraction (XRD) (Analysis equipment: Panalytical Empyrean Alpha1), and calculated using the Scherrer equation of [Equation 1] below [Equation 1] Scherrer equation: Lc = 0.89λ / (β·Cosθ). At this time, λ = 1.540598, β = 4.98, and θ = 24.74 (rad) 4) Measurement of surface resistance: After dispersing the carbon black with a content of 10 wt% in isopropyl alcohol (IPA) solvent using ultrasonic, the prepared slurry is coated to a thickness of 50 μm on an aluminum electrode plate using a doctor blade. The coated electrode is dried at about 100 °C for 1 hour to volatilize the solvent, and then the surface resistance of the electrode surface coated with carbon black is measured using a resistance measuring instrument (Mitsubishi MCP - T610).

[0069] As can be seen from Table 1 and Table 2 above, even when the same process conditions and methods are applied, the physical properties of the carbon black produced depend on the value of [(length L of the neck) / (diameter D of the neck)] (= condition (1)) and the value of [(diameter D' of the discharge part) / (diameter D of the neck)] (= condition (2)) of the manufacturing apparatus. It was confirmed that the furnace black before heat treatment of the present invention can be easily manufactured by a manufacturing apparatus that satisfies conditions (1) and (2).

[0070] Experimental Examples 1 - 3 and Comparative Experimental Example 1 - MEA Experiment (1) Fabrication of MEA What was used in Comparative Experimental Example 1 was the carbon black of Example 1 above without heat treatment.

[0071] The carbon black of commercially available Vulcan XC 72R (Lc: 2.2 nm) was used in Comparative Experimental Example 2.

[0072] The carbon black that was heat-treated at high temperature under the temperature shown in Table 3 below and in an inert gas (N2) atmosphere but with different heat treatment temperatures and then post-treated (heat-treated) was used in Comparative Experimental Example 3 and Experimental Examples 1 to 3, and the MEA was fabricated as follows.

[0073] ◎ Anode: For each of the carbon blacks, the same amount of platinum (Pt) catalyst was supported based on the weight of each carbon black for production. ◎ Cathode: The 10F50E catalyst of Tanaka Co., Ltd. was used. ◎ Electrolyte membrane: Nafion211 of Gore Co., Ltd. was used. ◎ Fabrication of MEA: The materials prepared above were thermocompression bonded at a temperature of 130 °C and a pressure of 30 kgf / cm 2 to fabricate a membrane electrode assembly (MEA).

[0074]

Table 3

[0075] (2) MEA evaluation For the MEAs fabricated in Experimental Examples 1 to 3 and Comparative Experimental Example 1 above, the performance and reverse voltage durability were evaluated by the following methods, and the results are shown in Table 4 below.

[0076] ◎ MEA performance evaluation: It was evaluated at a temperature of 65 °C, RH (Relative humidity) of 100%, and an operating pressure of 1 bar, and the current value at a voltage of 0.6 V in the I-V curve was measured. ◎ Reverse voltage durability: Using the above MEA, the supply of hydrogen to the anode was interrupted, and after applying a current of 1.2 A / cm 2 the voltage drop rate after 5 hours was measured.

[0077]

Table 4

[0078] As shown in Table 4 above, in Experimental Examples 1 to 3 where high-temperature heat treatment was performed according to the production method of the present invention, Lc could have excellent crystallinity of 4.0 nm or more, and the specific surface area and OAN value could also achieve the target physical property values of the present invention. It is suitable for use in electrodes that require durability. In fact, it also has excellent MEA performance, the absolute value of the reverse voltage drop rate is low, and it has been found to have an excellent effect of preventing the reverse voltage phenomenon.

[0079] Although it varies depending on the specifications and experimental conditions of the fuel cell, in the present invention, it can be evaluated that the absolute value of the reverse voltage drop rate is preferably 20% or less, more preferably 15% or less, and most preferably 10% or less.

[0080] On the other hand, in Comparative Experimental Example 1, since Lc was particularly low, in fact, even though the current value in the MEA was similar to that in Experimental Example 1, the reverse voltage drop rate was high.

[0081] In Comparative Experimental Example 2, as a carbon black material conventionally used, although Lc is somewhat high, such carbon black with a high Lc tends to have a high specific surface area as well. Therefore, carbon black with a very high specific surface area has weak durability. In fact, in the MEA experiment, the absolute value of the reverse voltage drop rate was shown to be high.

[0082] In Comparative Experimental Example 3, as a result of heat treatment at 1500°C, which is a temperature lower than the high-temperature heat treatment temperature of the present invention, the Lc value did not reach 4.0 nm. As a result, it was confirmed that the absolute value of the reverse voltage drop rate was high.

[0083] As described above, the present invention has been described with reference to the exemplary drawings. However, the present invention is not limited by the embodiments and drawings disclosed herein, and it is obvious that various modifications can be made by those of ordinary skill in the art within the scope of the technical idea of the present invention. Further, even if the effects of the present invention by the configuration are not explicitly described while describing the embodiments of the present invention, it is natural that the effects predictable by the configuration should also be recognized.

Explanation of Reference Numerals

[0084] 10 Carbon black production apparatus 11 Supply unit 11a Air supply unit 11b Fuel supply unit 12 Reaction unit 13 Discharge unit 14 Neck 15 Casing L Length of neck D Diameter of neck D’ Diameter of discharge unit

Claims

**Claim 1** A method for producing highly crystalline carbon black, wherein the microcrystalline size (Lc) is 4.0 nm or more; the specific surface area (BET) is 50 to 150 m2 / g; and the oil absorption number (OAN) is 150 ml / 100 g or more, comprising: (a) The microcrystalline size (Lc) is 1.0 to 2.0 nm; the specific surface area (BET) is 50 to 150 m ２ / g; and the oil absorption number (OAN) is 150 ml / 100 g or more, the step of manufacturing furnace black; and (b) subjecting the furnace black to high-temperature heat treatment at a temperature of 1800 °C or higher to obtain highly crystalline carbon black; and step (a) is carried out under the conditions of a temperature of 1500 to 1800 °C and incomplete combustion. A method for producing highly crystalline carbon black. **Claim 2** The high-temperature heat treatment in step (b) is carried out at a temperature of 2000 °C or higher. The method for producing highly crystalline carbon black according to claim 1. **Claim 3** The furnace black in step (a) is (i) at least one supply unit having an air supply unit and a fuel supply unit; (ii) a reaction unit into which the high-temperature combustion gas introduced through the supply unit flows; (iii) a discharge part (throat) that extends from the reaction part and has a diameter smaller than that of the reaction part; (iv) a neck part that extends from the discharge part and has a diameter larger than that of the discharge part; and (v) a casing that extends from the neck part and has a diameter larger than that of the neck part; and is produced by a carbon black production apparatus that satisfies the following conditions (1) and (2). The method for producing highly crystalline carbon black according to claim 1: - Condition (1): [(length L of the neck) / (diameter D of the neck)] > 3 - Condition (2): [(diameter D' of the discharge part) / (diameter D of the neck)] < 0.6 **Claim 4** The microcrystalline size (Lc) is 5.0 nm or more and 10 nm or less. The method for producing highly crystalline carbon black according to claim 1. **Claim 5** The specific surface area (BET) is 70 to 100 m2 / g. The method for producing highly crystalline carbon black according to claim 1. **Claim 6** The oil absorption number (OAN) is 180 ml / 100 g or more. The method for producing highly crystalline carbon black according to claim 1. **Claim 7** The d-spacing (002) value, which is the average lattice spacing calculated from the X-ray diffraction data, is 0.350 nm or less. The method for producing highly crystalline carbon black according to claim 1. **Claim 8** An electrode comprising a catalyst support formed of highly crystalline carbon black and a catalyst supported on the catalyst support, and an electrolyte membrane (membrane). The carbon black has a microcrystalline size (Lc) of 4.0 nm or more; a specific surface area (BET) of 50 to 150 m2 / g; and an oil absorption number (OAN) of 150 ml / 100 g or more, Membrane electrode assembly.

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