Porous support for water electrolysis

Abstract

The present invention relates to a porous support for water electrolysis, which has constant surface resistance and electrical conductivity due to coating layers uniformly formed inside and outside thereof, wherein the porous support comprises: a porous fabric support formed by intersecting a plurality of fibers with each other; a catalyst layer formed on the porous fabric support; a first coating layer formed on the catalyst layer; and a second coating layer formed on the first coating layer.

Description

Porous support for water electrolysis

[0001] The present invention relates to a porous support for electrolysis.

[0002] AEM (Anion Exchange Membrane) electrolysis has the advantage of low-cost hydrogen production by using non-precious metal cations and hydrocarbon-based anion exchange membranes, but has the disadvantage of lower performance and durability compared to existing PEM (Proton Exchange Membrane) electrolysis or alkaline electrolysis technologies. Among the various components that make up the electrolysis cell, the porous transport layer (PTL) and electrodes can improve electrolysis performance and durability by improving their structures. In the electrode part close to the membrane, the higher the specific surface area, the higher the catalytic activity, and in the part where gas and electrolyte escape, the higher the appropriate pore size and porosity, the higher the activity and durability of the electrolysis cell. Therefore, the porosity and specific surface area of ​​the PTL and electrodes must be able to be adjusted in various ways.

[0003] The most readily available fiber-based materials around us can easily control the porosity and specific surface area depending on the weaving method and material, and are very inexpensive. Therefore, if the surface metal coating of these fiber-based three-dimensional porous materials can be uniformly applied, it is expected that the unit cost of the material can be reduced by lowering the metal content, and the specific surface area and porosity can be adjusted in various ways, thereby improving the electrolysis performance more efficiently.

[0004] The wet plating method is the most efficient method for coating metal on the surface of a porous material in the form of a fiber-based fabric. In order to be used as a water electrolysis material, the metal must be evenly coated on the entire inner and outer fiber strands to reduce surface resistance and achieve high electrical conductivity.

[0005] However, due to the structural limitations of the fabric formed by densely intersecting fiber bundles, it is difficult to coat each individual fiber strand, which makes it difficult to achieve low surface resistance.

[0006] The problem to be solved by the present invention is to provide a porous support for electrolysis of water having a uniform coating layer formed on the inside and outside and having a constant surface resistance and electrical conductivity.

[0007] The present invention is a porous support for water electrolysis, comprising: a porous fabric support formed by intersecting a plurality of fibers; a catalyst layer formed on the porous fabric support; a first coating layer formed on the catalyst layer; and a second coating layer formed on the first coating layer.

[0008] In the present invention, the porous fabric support may have a porosity of 40% or more.

[0009] In the present invention, the porous fabric support may be pretreated with a sodium hydroxide (NaOH) solution.

[0010] In the present invention, the porous fabric support may be composed of one or more components selected from the group consisting of polyethylene terephthalate, nylon, aramid, and cotton.

[0011] In the present invention, the catalyst layer may include Pd and Sn.

[0012] In the present invention, the first coating layer may include Ni-B or Ni-P.

[0013] In the present invention, the second coating layer may include one or more metals selected from the group consisting of Ni, Fe, Co, Mn, and Mo.

[0014] In the present invention, the thickness of the first coating layer may be 0.3 to 0.7 μm, and the thickness of the second coating layer may be 0.3 to 0.7 μm.

[0015] In the present invention, the porous support for electrolysis may have a thickness deviation of 40% or less with respect to the average of the entire coating layer measured by the following measuring method.

[0016] [measurement method]

[0017] Deviation from the average of the entire coating layer: The thickness of the entire coating layer of the porous support for electrolysis is measured by cutting the cross-sections at three locations on both sides and the center, measuring the thickness at five locations inside and outside of each cut cross-section, calculating the average of the entire measurement values ​​and the deviation, and then dividing the deviation by the average value to calculate the deviation %.

[0018] In the present invention, the basis weight of the first coating layer is 5 to 15 mg / cm 2 And the basis weight of the second coating layer is 15 to 35 mg / cm 2 It could be.

[0019] In the present invention, the porosity of the porous support for electrolysis can be reduced by 10% to 30% compared to the porosity of the porous fabric support.

[0020] In the present invention, the surface resistance of the porous support for electrolysis may be less than 0.08 Ω / sq.

[0021] In the present invention, the gas permeability (Gurley No.) of the porous support for water electrolysis may be 0.0005 to 0.005.

[0022] The porous support for electrolysis according to the present invention has a coating layer formed evenly, so that the surface resistance and electrical conductivity can be constant.

[0023] In addition, the porous support for electrolysis according to the present invention has a coating layer formed inside and outside, thereby increasing the reaction area and thus having excellent catalytic activity and high electrical conductivity.

[0024] Figure 1 is a photograph of the surface of a porous support for electrolysis of Example 1 of the present invention taken using SEM.

[0025] Figure 2 is a photograph of the surface of a porous support for electrolysis of Example 1 and Comparative Example 1 of the present invention taken using SEM.

[0026] Hereinafter, the present invention will be described in more detail with reference to exemplary embodiments, examples, etc. so that those skilled in the art can easily implement the present invention. However, the present invention may be implemented in various different forms and is not limited to the embodiments, examples, etc. described herein.

[0027] In the present invention, when it is said that a member is located “on” another member, this includes not only cases where a member is in contact with another member, but also cases where another member exists between the two members.

[0028] The present invention is a porous support for water electrolysis, comprising: a porous fabric support formed by intersecting a plurality of fibers; a catalyst layer formed on the porous fabric support; a first coating layer formed on the catalyst layer; and a second coating layer formed on the first coating layer.

[0029] The porous fabric support is a substrate formed by intersecting multiple fibers, and has multiple pores formed between the fibers. The fibers forming the material of the porous fabric support are long, thin linear objects, and may be composed of one or more components selected from the group consisting of polyethylene terephthalate, nylon, aramid, and cotton, and preferably, polyethylene terephthalate.

[0030] Meanwhile, a representative method for manufacturing a fabric support using a plurality of fibers is a weaving method. However, in the present invention, the scope of rights should not be limited by the method, and any method may be used as long as the fabric support can be formed into a predetermined shape, such as two or three dimensions, including a paper or Korean paper manufacturing method in which fibers are dissolved in water and thinly tangled. The fabric support manufactured using fibers in this way has a large number of microscopic pores, and the pores are connected from the outer surface to the inner surface of the fabric support.

[0031] The plurality of fibers constituting the above fabric support may be yarns, and their diameter may be 400 denier or less, and the above porous fabric support may have a porosity of 40% or more, and preferably a porosity of 50 to 80%.

[0032] If the porosity of the porous fabric support is less than 40%, uniform coating of the entire interior and exterior may be difficult, and thus the reaction area may be reduced. If the porosity of the porous fabric support exceeds 80%, the durability of the porous support for water electrolysis may be reduced, and therefore the above range is preferred.

[0033] The thickness of the above porous fabric support may be 0.05 to 2 mm, and preferably 0.1 to 1 mm.

[0034] The porous fabric support may be pretreated with a sodium hydroxide (NaOH) solution. By pretreating the porous fabric support with a sodium hydroxide solution, the surface roughness of the fabric support may be increased, thereby facilitating catalyst coating on the surface.

[0035] The above sodium hydroxide (NaOH) solution may be a 20 to 40 wt% sodium hydroxide solution at 60 to 70°C.

[0036] In the present invention, the catalyst layer may include Pd (palladium) and tin (Sn), and the catalyst layer may be formed of a Pd-Sn colloidal solution including SnCl2 (tin chloride), PdCl2 (palladium chloride), and hydrochloric acid.

[0037] In the present invention, the first coating layer may be formed on the catalyst layer and may include Ni-B or Ni-P, and the content of B or P may be 5 wt% or less, and preferably more than 0 wt% and 3 wt% or less. In addition, preferably, the first coating layer may include Ni-B.

[0038] The first coating layer may be formed by an electroless plating coating method. The thickness of the first coating layer may be 0.3 to 0.7 μm, and preferably, the thickness of the first coating layer may be 0.35 to 0.65 μm. In addition, the basis weight of the first coating layer may be 5 to 15 mg / cm. 2 It can be, preferably 6 to 14 mg / cm 2 may be, more preferably 8 to 12 mg / cm 2 The thickness or basis weight of the first coating layer may be 0.3 ㎛ or 5 mg / cm 2 If it is less than 0.7㎛ or 15mg / cm, the surface resistance increases and the formation of the second coating layer is uneven or the formation of the second coating layer is not easy, and the thickness or basis weight is 0.7㎛ or 15mg / cm 2 If it exceeds , the first coating layer becomes too thick, making it difficult to form the second coating layer, which may increase the surface resistance.

[0039] The first coating layer may be formed by immersing a porous fabric support having a catalyst layer formed thereon in a solution containing a reducing agent, dimethylamine borane, and NiSO4 (nickel sulfate), at 50 to 80°C for 1 to 30 minutes, or by immersing a porous fabric support having a catalyst layer formed thereon in a solution containing sodium hypophosphite and NiSO4 (nickel sulfate), at 50 to 80°C for 1 to 30 minutes, wherein metal ions are reduced by a chemical oxidation-reduction reaction, and a first coating layer may be rapidly formed on the catalyst layer.

[0040] In the present invention, the second coating layer may be formed on the first coating layer, and may include one or more metals selected from the group consisting of Ni, Fe, Co, Mn, and Mo, and preferably may include Ni.

[0041] The second coating layer may be formed by an electroplating coating method. The thickness of the second coating layer may be 0.3 to 0.7 μm, and preferably, the thickness of the second coating layer may be 0.35 to 0.65 μm. In addition, the basis weight of the second coating layer may be 15 to 35 mg / cm. 2 It can be, preferably 22-28mg / cm 2 The thickness or basis weight of the second coating layer may be 0.3 ㎛ or 15 mg / cm 2 If it is less than 0.7㎛ or 35mg / cm, the coating may not be even, which may result in reduced electrical conductivity or increased surface resistance, and the thickness or basis weight may be less than 0.7㎛ or 35mg / cm. 2 If it exceeds , the second coating layer may become too thick and the porosity may be greatly reduced, which may reduce the diffusion property.

[0042] The second coating layer can be formed by immersing the porous fabric support on which the first coating layer is formed in a solution containing nickel (II) sulfamate, NiCl2 (nickel chloride), and H3BO3 (boric acid) and applying a constant voltage of 2 to 5 V at 40 to 60°C for 10 to 30 minutes.

[0043] In the present invention, the porous support for electrolysis may have a thickness deviation of 40% or less, and preferably 25 to 35%, from the average of the entire coating layer measured by the following measuring method.

[0044] [measurement method]

[0045] Deviation from the average of the entire coating layer: The thickness of the entire coating layer of the porous support for water electrolysis is measured by cutting the cross-sections at three locations on both sides and the center, measuring the thickness at five locations inside and outside of each cut cross-section, calculating the average of the entire measurement values ​​and the deviation, and then calculating the deviation % using the average value as the deviation.

[0046] If the difference in thickness of the entire coating layer exceeds 40%, the surface resistance may differ, and thus it is not suitable for use in electrolysis.

[0047] The porosity of the porous support for electrolysis may be reduced by 10% to 30% compared to the porosity of the porous fabric support, and preferably reduced by 10% to 25%.

[0048] If the porosity of the porous support for electrolysis is reduced by less than 10% compared to the porosity of the porous fabric support, the thickness of the coating layer may be too thin, which may increase surface resistance, and if it is reduced by more than 30%, the pores may be blocked, which may reduce diffusion.

[0049] The surface resistance of the porous support for electrolysis of the present invention may be less than 0.08 Ω / sq, and preferably less than or equal to 0.05 Ω / sq.

[0050] In the present invention, the gas permeability (Gurley No.) of the porous support for water electrolysis may be 0.0005 to 0.005, and preferably 0.0006 to 0.003.

[0051] Hereinafter, the present invention will be described in more detail by way of preferred embodiments thereof.

[0052]

[0053] Examples and Comparative Examples

[0054] A porous fabric support having a thickness of 0.25 mm and a fiber bundle composed of 300 denier yarn is prepared. The porous fabric support is immersed in a 30 wt% NaOH solution at 65°C for 20 minutes to increase the surface roughness.

[0055] Afterwards, the pretreated porous fabric support was washed three times with running water. The washed porous fabric support was immersed in 1 L of a Pd-Sn colloidal solution under ultrasonic conditions of 40 kHz (power output 265 W, <40°C) for 10 minutes to form a Pd-Sn catalyst layer. 1 L of the Pd-Sn colloidal solution is composed of 2.4 g / L of SnCl2 (tin chloride), 0.1 g / L of PdCl2 (palladium chloride), 97 g / L of hydrochloric acid, and the remainder of distilled water.

[0056] Thereafter, the porous fabric support having the catalyst layer formed thereon is immersed in 1 L of a first coating layer forming solution at 65°C for 5 minutes to form a first coating layer. The 1 L of the first coating layer forming solution is composed of 6 g / L of dimethylamine borane, 24 g / L of NiSO4 (nickel sulfate), and the remainder of distilled water.

[0057] Thereafter, the porous fabric support on which the first coating layer was formed was immersed in 1 L of a second coating layer forming solution at 50°C for 10 minutes, and a constant voltage of 4 V was applied to form a second catalyst layer, thereby manufacturing a porous support for water electrolysis. The 1 L of the second coating layer forming solution is composed of 446 g / L of nickel (II) sulfamate, 4 g / L of nickel chloride (NiCl2), 30 g / L of H3BO3 (boric acid), and the remainder of distilled water.

[0058] The composition, porosity, average thickness and basis weight of the first coating layer, and average thickness and basis weight of the second coating layer of the porous fabric support are as shown in Table 1 below (PET: polyethylene terephthalate).

[0059] Classification Porous fabric support system 1 Coating layer 2 Coating layer Porosity (%) Raw material Thickness (㎛) Basis weight (mg / cm) 2 )Thickness (㎛)Basis weight (mg / cm) 2 )Example 161PET0.5100.525Example 261PET0.360.525Example 361PET0.7140.525Example 461PET0.5100.315Example 561PET0.5100.735Comparative Example 134PET0.5100.525Comparative Example 261PET1.0200.525Comparative Example 361PET0.5100.15Comparative Example 461PET0.5101.050Comparative Example 561PET120--Comparative Example 661PET1201.050

[0060]

[0061] Experimental Example 1

[0062] The contact angle of the porous fabric support used in the examples and comparative examples and the surface resistance value and diffusivity of the porous support for water electrolysis were measured, and the results are shown in Table 2 below.

[0063] [measurement method]

[0064] Surface resistance: Measure 6 points on a 5x5cm sized specimen using a 4-probe surface resistance meter and check the average value. A smaller value indicates a higher conductivity of the specimen.

[0065] Gas permeability: Analyzed using a capillary flow porometer (permeability) meter and compared to the average Gurley number (the time it takes for 10 cc of air to pass through 1 square inch of porous membrane in 12.2 inches of water). A smaller value means more pores and faster gas passage.

[0066]

[0067] Surface resistance (Ω / sq) Gas permeability (Gurley No.) Example 10.020.0011 Example 20.030.0008 Example 30.010.0014 Example 40.030.0006 Example 50.010.0013 Comparative Example 120.012 Comparative Example 20.060.04 Comparative Example 30.30.0009 Comparative Example 40.050.06 Comparative Example 50.080.0012 Comparative Example 60.010.1

[0068]

[0069] Referring to Table 2 above, it can be confirmed that the surface resistance value is very low when the porosity of the porous fabric support is 61% (Example 1) compared to when it is less than 40% (Comparative Example 1).

[0070] In addition, it can be confirmed that the gas permeability is 0.0006 to 0.0014 when the thickness of the first coating layer is 0.3 to 0.7 ㎛ and the thickness of the second coating layer is 0.3 to 0.7 ㎛ (Examples 1 to 5), whereas the gas permeability value is 0.04 or 0.06, which is not good, when the thickness of the first coating layer is 1 ㎛ (Comparative Example 2) or the thickness of the second coating layer is 1 ㎛ (Comparative Example 4).

[0071] In addition, it can be confirmed that the surface resistance value is much higher when the thickness of the second coating layer is 0.1 ㎛ (Comparative Example 3) than when the thickness of the second coating layer is 0.3 to 0.7 ㎛ (Examples 1 to 5).

[0072] Meanwhile, it can be confirmed that the gas permeability is not as good in the case where the thicknesses of the first coating layer and the second coating layer are each 1 µm (Comparative Example 6) as in the case where the thicknesses of the first coating layer and the second coating layer are each 0.5 µm (Example 1).

[0073]

[0074] Experimental Example 2

[0075] The porosity, porosity reduction %, and deviation from the average of the entire coating layer of the porous support for electrolysis of the examples and comparative examples were measured, and the results are shown in Table 3 below.

[0076] [measurement method]

[0077] Porosity: Measured by MIP (Mercury Intrusion Porosimetry)

[0078] Porosity reduction %: The difference between the porosity of the porous fabric support and the porosity of the porous support for water electrolysis.

[0079] Deviation from the average of the entire coating layer: The thickness of the entire coating layer of the porous support for electrolysis is measured by cutting cross-sections at three locations on both edges and the center, measuring the thickness at five locations inside and outside of each cut cross-section, calculating the average of the entire measurement values ​​and the deviation, and then dividing the deviation by the average value to calculate the deviation %.

[0080]

[0081] Classification Porosity (%) Porosity reduction % Deviation from the average of the entire coating layer % Example 1 5 2 1 5 3 0 Example 2 5 4 1 2 5 Example 3 5 0 1 8 2 5 Example 4 5 3 1 3 5 Example 5 4 9 2 0 2 5 Comparative Example 1 1 5 5 6 6 0 Comparative Example 2 4 2 3 1 2 7 Comparative Example 3 5 6 9 3 3 Comparative Example 4 4 ​​2 3 1 3 3 Comparative Example 5 5 4 1 1 4 5 Comparative Example 6 4 0 3 5 3 0

[0082]

[0083] Referring to Table 3 above, it can be seen that when the porosity of the porous fabric support is 61% (Example 1), the deviation % from the average of the entire coating layer is very low compared to when the porosity is less than 40% (Comparative Example 1), and the porosity reduction % is also low.

[0084] In addition, it can be confirmed that the porosity reduction % is 12-20% when the thickness of the first coating layer is 0.3 to 0.7 ㎛ and the thickness of the second coating layer is 0.3 to 0.7 ㎛ (Examples 1 to 5), whereas the porosity reduction % is very high at 31% when the thickness of the first coating layer is 1 ㎛ (Comparative Example 2) or when the thickness of the second coating layer is 1 ㎛ (Comparative Example 4).

[0085] Meanwhile, in the case where the thicknesses of the first coating layer and the second coating layer are each 1 µm (Comparative Example 6), it can be confirmed that the porosity reduction % is higher than in the case where the thicknesses of the first coating layer and the second coating layer are each 0.5 µm (Example 1).

[0086] In addition, when the thickness of the first coating layer is 1 µm (Comparative Example 5), it can be confirmed that the deviation % from the average of the entire coating layer is 45% much higher than when the thickness of the first coating layer and the second coating layer are each 0.5 µm (Example 1).

[0087] In general, when electroless plating is formed on a surface, the uniformity of the coating thickness deteriorates as the thickness increases due to the influence of the surface shape and internal pores. Accordingly, when the first coating layer is thickened to 1 ㎛ (Comparative Example 5), it is difficult to maintain a uniform thickness of the coating when the electroless plating layer is formed on the surface of a porous fabric support, and as a result, the thickness deviation across the support increases.

[0088] On the other hand, in Example 1, the first coating layer and the second coating layer are formed in two layers, each 0.5 μm thick, and when electroplating is performed again on the first thin coating layer formed, the second coating layer is formed while the current flows uniformly inward and outward, and accordingly, a coating layer with a uniform thickness can be formed overall, so that the deviation % with respect to the average of the entire coating layer is reduced.

[0089]

[0090] Experimental Example 3

[0091] The surface of the porous support for electrolysis of Example 1 and Comparative Example 1 was photographed using a scanning electron microscope (SEM), and the results are shown in FIGS. 1 and 2.

[0092]

[0093] Referring to FIG. 1, it can be confirmed that the porous support for electrolysis according to the present invention (Example 1) has a first coating layer and a second coating layer formed on the surface.

[0094]

[0095] Porous supports require that the catalyst and metal ions in the solution readily access the interior of the support during the electrolytic coating process to achieve uniform coating. However, Comparative Example 1 has a porosity of 34%, which is lower than the 61% of Example 1. This prevents the coating solution from sufficiently penetrating into the fibers, resulting in limited coating on the surface, preventing uniform coating within the support.

[0096] Referring to FIG. 2, it can be confirmed that the porous support for electrolysis according to the present invention (Example 1) has the surface of the fibers evenly coated, but in the case where the porosity is 34% (Comparative Example 1), it can be confirmed that the inside of the porous support is not evenly coated.

[0097] The porous support for electrolysis according to the present invention has a coating layer formed on the inside and outside, thereby increasing the effective reaction area where an electrode reaction occurs, thereby improving electrochemical catalytic activity and electrical conductivity.

[0098] Due to these characteristics, the support of the present invention can be applied to a hydrogen production process through water decomposition, and can be industrially useful because it can improve the efficiency and durability of a water electrolysis system, and in particular, it can be applied to various water electrolysis technologies such as alkaline water electrolysis (ALK), polymer electrolyte membrane (PEM), and high-temperature water electrolysis (SOEC) for realizing a hydrogen economy, and therefore can be widely utilized in all energy-related industries such as hydrogen production, energy storage, and fuel cell systems.

Claims

1. A porous fabric support formed by crossing multiple fibers; A catalyst layer formed on the porous fabric support; A first coating layer formed on the catalyst layer; and A second coating layer formed on the first coating layer; A porous support for electrolysis, comprising:

2. In paragraph 1, The above porous fabric support is a porous support for electrolysis, having a porosity of 40% or more.

3. In paragraph 1, The above porous fabric support is a porous support for electrolysis, which is pretreated with a sodium hydroxide (NaOH) solution.

4. In paragraph 1, The porous fabric support is a porous support for electrolysis, which is made of at least one component selected from the group consisting of polyethylene terephthalate, nylon, aramid, and cotton.

5. In paragraph 1, A porous support for water electrolysis, wherein the catalyst layer comprises Pd and Sn.

6. In paragraph 1, A porous support for electrolysis, wherein the first coating layer comprises Ni-B or Ni-P.

7. In paragraph 1, A porous support for electrolysis, wherein the second coating layer comprises at least one metal selected from the group consisting of Ni, Fe, Co, Mn, and Mo.

8. In paragraph 1, A porous support for electrolysis, wherein the thickness of the first coating layer is 0.3 to 0.7 μm, and the thickness of the second coating layer is 0.3 to 0.7 μm.

9. In paragraph 1, The porous support for electrolysis is a porous support for electrolysis having a thickness deviation of 40% or less with respect to the average of the entire coating layer measured by the following measuring method: [measurement method] Deviation from the average of the entire coating layer: The thickness of the entire coating layer of the porous support for electrolysis is measured by cutting cross-sections at three locations on both edges and the center, measuring the thickness at five locations inside and outside of each cut cross-section, calculating the average of the entire measurement values ​​and the deviation, and then dividing the deviation by the average value to calculate the deviation %.

10. In paragraph 1, The basis weight of the first coating layer is 5 to 15 mg / cm 2 And the basis weight of the second coating layer is 15 to 35 mg / cm 2 A porous support for electrolysis.

11. In paragraph 1, A porous support for electrolysis, wherein the porosity of the porous support for electrolysis is reduced by 10% to 30% compared to the porosity of the porous fabric support.

12. In paragraph 1, A porous support for electrolysis, wherein the surface resistance of the porous support for electrolysis is less than 0.08 Ω / sq.

13. In paragraph 1, A porous support for water electrolysis, wherein the gas permeability (Gurley No.) of the porous support for water electrolysis is 0.0005 to 0.005.

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