Porous water electrolysis separation membrane using boron nitride compound and manufacturing method thereof

Abstract

The present invention relates to a porous water electrolysis separation membrane using a boron nitride compound. More specifically, the porous water electrolysis separation membrane comprises a porous polymer support and a boron nitride compound inserted into the inside of the porous polymer support or formed on a surface thereof. The water electrolysis separation membrane according to the present invention as described above exhibits excellent heat resistance and stability and has smaller pore sizes, thereby reducing the permeability of hydrogen and oxygen and achieving high hydrogen gas purity. In addition, with a reduced thickness, the water electrolysis separation membrane exhibits low sheet resistance and thus increases current density to improve electrolytic cell efficiency.

Description

Porous water electrolysis membrane using boron nitride compound and method for manufacturing the same

[0001] The present invention relates to a porous water electrolysis membrane using a boron nitride compound, and more specifically, the porous water electrolysis membrane has a technical feature in that it includes a porous polymer support and a boron nitride compound inserted into the interior of the porous polymer support or formed on the surface thereof.

[0002] Water electrolysis is the process of producing hydrogen and oxygen through the electrolysis of water. Water (H2O) is decomposed into hydrogen gas (H2) and oxygen gas (O2) using electrical energy. Water electrolysis is a key technology for producing hydrogen in various industries and energy systems, and is particularly attracting attention as a method of producing hydrogen without carbon dioxide emissions.

[0003] Alkaline Water Electrolysis (AWE) is a type of water electrolysis technology in which two electrodes (an anode and a cathode) are immersed in an alkaline electrolyte solution and separated by a porous membrane. The membrane allows ions to pass through but blocks gases, preventing the hydrogen and oxygen produced from mixing. Alkaline Water Electrolysis (AWE) is currently the most common water electrolysis method and has the advantages of being inexpensive, durable, and easy to maintain compared to other electrolysis methods. However, problems such as electrolyte leakage, limited current density, and possibility of hydrogen / oxygen mixing still remain, and the limited current density and hydrogen / oxygen permeability problems are greatly affected by the characteristics of the membrane.

[0004] Currently, the commercially used membrane comprises a composite of ZrO2 (zirconia) and a polymer resin (PPS, polyphenylene sulfide). Although the ZrO2 (zirconia) and polyphenylene sulfide membranes are excellent commercial membranes, they have problems such as insufficient wettability, risk of hydrogen cross-migration, conflict between membrane thickness and gas permeability, insufficient load fluctuation response, and insufficient alkali resistance. Specifically, the ZrO2 (zirconia) and polyphenylene sulfide-based membranes have a problem in that they do not contribute to the movement of KOH electrolyte due to the low wettability of the polyphenylene sulfide (PPS) mesh, and there is a risk of explosion due to cross-migration of hydrogen dissolved in the KOH electrolyte to the anode zone in the low current partial load region. In addition, although the sheet resistance is lowered when the membrane thickness is reduced, the gas permeability is increased, which reduces the stability of the membrane against differential pressure. In addition, the above ZrO2 (zirconia) and polyphenylene sulfide-based electrolytic membranes have problems in that their operating range is limited to more than 20% load, their gas barrier properties are insufficient in response to load fluctuations, which may cause safety issues, and some materials have poor durability in strong alkaline environments, which may cause problems during long-term use.

[0005] Accordingly, the inventors of the present invention completed the present invention by developing a new porous water electrolysis membrane having a thin thickness and ultrafine porosity using a boron nitride (BN) compound instead of ZrO2 while conducting research to solve the above-mentioned problem.

[0006] In this regard, Korean Patent No. 10-208930 discloses a water electrolysis membrane based on zirconia ceramic fabric.

[0007]

[0008] The present invention has been made to solve the problems of the above-mentioned prior art, and its purpose is to provide a porous water electrolysis separation membrane comprising a porous polymer support; and a boron nitride compound inserted into the interior of the porous polymer support or formed on the surface thereof.

[0009] In addition, the present invention aims to provide an alkaline water electrolysis system including the porous water electrolysis separation membrane.

[0010] In addition, the present invention aims to provide a method for manufacturing a porous water electrolysis membrane, which comprises the steps of: dispersing a boron nitride compound in a solvent to manufacture a boron nitride mixture; and laminating the boron nitride mixture on the surface of a porous polymer support.

[0011]

[0012] As a technical means for achieving the aforementioned technical task, one aspect of the present invention is,

[0013] A porous water electrolysis membrane is provided, comprising a porous polymer support; and a boron nitride compound inserted into the interior of the porous polymer support or formed on the surface thereof.

[0014] The above porous polymer support may be a compound selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, and combinations thereof.

[0015] The above porous polymer support may have a pore size of 0.10 to 0.55 μm.

[0016] The above boron nitride compound may have the form of boron nitride nanosheets (BNNS), boron nitride nanoparticles, boron nitride nanotubes (BNNT), or boron nitride nanoribbons (BNNR).

[0017] The above electrolytic separation membrane may have an average pore size of 90 nm or less.

[0018] The above electrolytic separation membrane may have a thickness of 0.2 to 0.45 mm.

[0019]

[0020] In addition, another aspect of the present invention is

[0021] An alkaline water electrolysis system including the above porous water electrolysis membrane is provided.

[0022]

[0023] In addition, another aspect of the present invention is

[0024] The present invention provides a method for manufacturing a porous water electrolysis membrane, comprising the steps of: preparing a boron nitride mixture by dispersing a boron nitride compound in a solvent; and laminating the boron nitride mixture on the surface of a porous polymer support.

[0025] The above solvent may be NMP (N-methyl-2-pyrrolidone).

[0026] The above boron nitride compound may have the form of boron nitride nanosheets (BNNS), boron nitride nanoparticles, boron nitride nanotubes (BNNT), or boron nitride nanoribbons (BNNR).

[0027] The above porous polymer support may be a compound selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, and combinations thereof.

[0028] The step of laminating the boron nitride mixture on the surface of the porous polymer support is:

[0029] It may be performed by a method of filtering or coating the boron nitride mixture on the surface of the porous polymer support.

[0030] The method for filtering the boron nitride mixture on the surface of the porous polymer support may be to filter the boron nitride mixture on the surface of the porous polymer support under reduced pressure to form a boron nitride film on the surface of the porous polymer support.

[0031] The method for coating the boron nitride mixture on the surface of the porous polymer support may be a dipping coating, spraying coating, drop casting coating, blade coating, or spin coating method.

[0032]

[0033] The electrolytic membrane according to the present invention, as described above, has excellent heat resistance and stability, and has a smaller pore size, thereby reducing hydrogen and oxygen permeability and achieving high hydrogen gas purity. In addition, the electrolytic membrane has a thin thickness, resulting in low surface resistance and thus increased current density, thereby enhancing electrolytic cell efficiency.

[0034]

[0035] Figure 1 is a photograph showing the results of SEM analysis of a comparative example of the present invention.

[0036] Figure 2 is a photograph showing the results of an SEM analysis of a porous electrolytic membrane according to one embodiment of the present invention.

[0037] FIG. 3 is a photograph showing the results of a TEM analysis of boron nitride nanotubes (BNNT) included in a porous water electrolysis membrane according to one embodiment of the present invention.

[0038] FIG. 4 is a spectrum showing the ELLS analysis results of boron nitride nanotubes (BNNT) included in a porous water electrolysis membrane according to one embodiment of the present invention.

[0039] FIG. 5 is a photograph showing the results of EDX analysis of boron nitride nanotubes (BNNT) included in a porous water electrolysis membrane according to one embodiment of the present invention.

[0040] FIG. 6 is a spectrum showing the results of EDX analysis of boron nitride nanotubes (BNNT) included in a porous water electrolysis membrane according to one embodiment of the present invention.

[0041] Figure 7 is a photograph showing the pore size distribution of a water electrolysis membrane according to one embodiment and a comparative example of the present invention.

[0042] Figure 8 is a graph showing the results of thermal stability evaluation of a water electrolysis membrane according to one embodiment of the present invention.

[0043] Figure 9 is a graph showing the results of evaluating the efficiency of an electrolytic cell using a water electrolysis membrane according to one embodiment and one comparative example of the present invention.

[0044] Figure 10 is a graph showing the results of hydrogen permeability evaluation using a water electrolysis membrane according to one embodiment and a comparative example of the present invention.

[0045]

[0046] Hereinafter, the present invention will be described in more detail. However, the present invention may be implemented in various different forms, and the present invention is not limited to the embodiments described herein, but is defined only by the claims set forth below.

[0047] Additionally, the terminology used herein is solely for the purpose of describing specific embodiments and is not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly dictates otherwise. Throughout the specification of the present invention, the term "including" or "comprising" a component does not exclude other components, but rather implies the inclusion of other components, unless specifically stated otherwise.

[0048]

[0049] The first aspect of this article is,

[0050] A porous water electrolysis membrane is provided, comprising a porous polymer support; and a boron nitride compound inserted into the interior of the porous polymer support or formed on the surface thereof.

[0051]

[0052] Hereinafter, a porous electrolytic separation membrane according to the first aspect of the present invention will be described in detail.

[0053] In one embodiment of the present invention, the porous water electrolysis membrane may include a boron nitride compound and may include a porous polymer support to support the boron nitride compound. In this case, the boron nitride compound may be present in the form of a membrane on one side of the porous polymer support, and more specifically, the boron nitride compound may be formed on the surface of the porous polymer support or inserted into the interior, and even more specifically, may be inserted into a pore present on the surface of the porous polymer support.

[0054] In one embodiment of the present invention, the porous polymer support may be made of a compound selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, and combinations thereof, and more preferably, the porous polymer support may be polytetrafluoroethylene.

[0055] In one embodiment of the present invention, the porous polymer support includes pores, and the pore size may be 0.10 to 0.55 μm, preferably the porous polymer support may have a pore size of 0.15 to 0.50 μm, and more preferably 0.20 to 0.45 μm. In this case, when the pore size of the porous polymer support is less than 0.10 μm, the boron nitride compound may not be sufficiently supported, and thus the manufactured electrolysis membrane may not be able to sufficiently perform its role as a membrane, and when the pore size of the porous polymer support exceeds 0.55 μm, the average pore size of the manufactured electrolysis membrane may be large, which may increase the hydrogen gas permeability, and thus cause a problem of lowering the gas purity.

[0056] The above boron nitride compound may have a form of boron nitride nanosheets (BNNS), boron nitride nanoparticles, boron nitride nanotubes (BNNT), or boron nitride nanoribbons (BNNR), and in one embodiment of the present invention, the boron nitride compound may have a form of boron nitride nanotubes (BNNT).

[0057] In one embodiment of the present invention, the water electrolysis membrane may have an average pore size of 90 nm or less, preferably 85 nm or less, and more preferably, the average pore size of the water electrolysis membrane may be 10 to 80 nm. In this case, when the average pore size of the water electrolysis membrane exceeds 90 nm, the hydrogen gas permeability may increase and the gas purity may decrease. That is, the water electrolysis membrane according to the present invention is characterized by having a small pore size, low hydrogen gas permeability, and high gas purity.

[0058] In one embodiment of the present invention, the electrolysis membrane may have a porosity of 56% or less, preferably, the porosity of the electrolysis membrane may be 55% or less, and more preferably, the porosity of the electrolysis membrane may be 54% or less. In this case, if the porosity of the electrolysis membrane exceeds 56%, the conductivity may decrease, or the reaction rate at the electrode surface may decrease, resulting in a problem of decreased electrolysis efficiency.

[0059] In one embodiment of the present invention, the electrolysis membrane may have a thickness of 0.2 to 0.45 mm, preferably, the electrolysis membrane may have a thickness of 0.21 to 0.40 mm, and more preferably, the electrolysis membrane may have a thickness of 0.22 to 0.35 mm. In this case, when the thickness of the electrolysis membrane is less than 0.2 mm, the membrane may be too thin, which may increase gas permeability and lower the stability of the membrane against differential pressure. In addition, when the thickness of the electrolysis membrane exceeds 0.45 mm, the resistance of the membrane may increase, which may cause a problem of decreasing current density.

[0060]

[0061] The second aspect of this article is,

[0062] An alkaline water electrolysis system including the above porous water electrolysis membrane is provided.

[0063]

[0064] Detailed explanations of parts that overlap with the first aspect of the present application have been omitted, but the explanations of the first aspect of the present application may be applied equally even if the explanations are omitted in the second aspect.

[0065]

[0066] Hereinafter, an alkaline water electrolysis system including a porous water electrolysis membrane according to the second aspect of the present invention will be described.

[0067]

[0068] In one embodiment of the present invention, the alkaline water electrolysis system is a technology for producing hydrogen and oxygen by electrolyzing water, and may include an electrolyzer cell, an electrolyte, an anode, a cathode, and a diaphragm as main components.

[0069] In one embodiment of the present invention, the alkaline water electrolysis system may include a porous water electrolysis membrane, and the porous water electrolysis membrane may improve the current density, hydrogen / oxygen permeability performance, and efficiency of the water electrolysis system.

[0070] In one embodiment of the present invention, the porous water electrolysis membrane may include a boron nitride compound and a porous polymer support for supporting the boron nitride compound. In this case, the boron nitride compound may be present in the form of a membrane on one side of the porous polymer support, and more specifically, the boron nitride compound may be formed on the surface of the porous polymer support or inserted into the interior, and even more specifically, may be inserted into a pore present on the surface of the porous polymer support.

[0071] In one embodiment of the present invention, the porous polymer support may be made of a compound selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, and combinations thereof, and more preferably, the porous polymer support may be polytetrafluoroethylene.

[0072] In one embodiment of the present invention, the porous polymer support includes pores, and the pore size may be 0.10 to 0.55 μm, preferably the porous polymer support may have a pore size of 0.15 to 0.50 μm, and more preferably 0.20 to 0.45 μm. In this case, when the pore size of the porous polymer support is less than 0.10 μm, the boron nitride compound may not be sufficiently supported, and thus the manufactured electrolysis membrane may not be able to sufficiently perform its role as a membrane, and when the pore size of the porous polymer support exceeds 0.55 μm, the average pore size of the manufactured electrolysis membrane may be large, which may increase the hydrogen gas permeability, and thus cause a problem of lowering the gas purity.

[0073] The above boron nitride compound may have a form of boron nitride nanosheets (BNNS), boron nitride nanoparticles, boron nitride nanotubes (BNNT), or boron nitride nanoribbons (BNNR), and in one embodiment of the present invention, the boron nitride compound may have a form of boron nitride nanotubes (BNNT).

[0074] In one embodiment of the present invention, the water electrolysis membrane may have an average pore size of 90 nm or less, preferably 85 nm or less, and more preferably, the average pore size of the water electrolysis membrane may be 10 to 80 nm. In this case, when the average pore size of the water electrolysis membrane exceeds 90 nm, the hydrogen gas permeability may increase and the gas purity may decrease. That is, the water electrolysis membrane according to the present invention is characterized by having a small pore size, low hydrogen gas permeability, and high gas purity.

[0075] In one embodiment of the present invention, the electrolysis membrane may have a porosity of 56% or less, preferably, the porosity of the electrolysis membrane may be 55% or less, and more preferably, the porosity of the electrolysis membrane may be 54% or less. In this case, if the porosity of the electrolysis membrane exceeds 56%, the conductivity may decrease, or the reaction rate at the electrode surface may decrease, resulting in a problem of decreased electrolysis efficiency.

[0076] In one embodiment of the present invention, the electrolysis membrane may have a thickness of 0.2 to 0.45 mm, preferably, the electrolysis membrane may have a thickness of 0.21 to 0.40 mm, and more preferably, the electrolysis membrane may have a thickness of 0.22 to 0.35 mm. In this case, when the thickness of the electrolysis membrane is less than 0.2 mm, the membrane may be too thin, which may increase gas permeability and lower the stability of the membrane against differential pressure. In addition, when the thickness of the electrolysis membrane exceeds 0.45 mm, the resistance of the membrane may increase, which may cause a problem of decreasing current density.

[0077]

[0078] The third aspect of this article is,

[0079] A step of preparing a boron nitride mixture by dispersing a boron nitride compound in a solvent;

[0080] A method for manufacturing a porous water electrolysis membrane is provided, comprising the step of laminating the boron nitride mixture on the surface of a porous polymer support.

[0081]

[0082] Detailed explanations of parts that overlap with the first aspect of the present application have been omitted, but the explanations of the first aspect of the present application may be applied equally even if the explanations are omitted in the third aspect.

[0083]

[0084] Hereinafter, a method for manufacturing a porous electrolytic membrane according to the third aspect of the present invention will be described in detail.

[0085]

[0086] In one embodiment of the present invention, the step of preparing a boron nitride mixture by dispersing a boron nitride compound in a solvent may include introducing the boron nitride compound into the solvent and dispersing it using a ball mill, a sand mill, an ultrasonic disperser, a homogenizer, an atriter, etc., and for example, the boron nitride compound may be dispersed through ultrasonic dispersion (Tip sonication = Probe sonication), but is not limited thereto and any conventional dispersion method may be easily applied.

[0087] In one embodiment of the present invention, the solvent is an amide-based polar organic solvent such as water, dimethyl formamide (DMF), diethyl formamide, dimethyl acetamide (DMAc), N-methyl pyrrolidone (NMP); an alcohol such as methanol, ethanol, 1-propanol, 2-propanol (isopropyl alcohol), 1-butanol (n-butanol), 2-methyl-1-propanol (isobutanol), 2-butanol (sec-butanol), 1-methyl-2-propanol (tert-butanol), pentanol, hexanol, heptanol, or octanol; a glycol such as ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, 1,3-propanediol, 1,3-butanediol, 1,5-pentanediol, or hexylene glycol; Polyhydric alcohols such as glycerin, trimethylolpropane, pentaerythritol, or sorbitol; glycol ethers such as ethylene glycol monomethyl ether, diethylene glycol monomethyl ether, triethylene glycol monomethyl ether, tetraethylene glycol monomethyl ether, ethylene glycol monoethyl ether, diethylene glycol monoethyl ether, triethylene glycol monoethyl ether, tetraethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monobutyl ether, triethylene glycol monobutyl ether, or tetraethylene glycol monobutyl ether; ketones such as acetone, methyl ethyl ketone, methyl propyl ketone, or cyclopentanone; Examples thereof include esters such as ethyl acetate, γ-butyl lactone, and ε-propiolactone, and one or a mixture of two or more of these may be used. More preferably, when the solvent is NMP (N-methyl-2-pyrrolidone), the resistance value of the electrolytic cell may be lowered and the efficiency of the electrolytic cell may be increased.

[0088] In one embodiment of the present invention, the porous polymer support may be made of a compound selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, and combinations thereof, and more preferably, the porous polymer support may be polytetrafluoroethylene.

[0089] In one embodiment of the present invention, the porous polymer support includes pores, and the pore size may be 0.10 to 0.55 μm, preferably the porous polymer support may have a pore size of 0.15 to 0.50 μm, and more preferably 0.20 to 0.40 μm. In this case, when the pore size of the porous polymer support is less than 0.10 μm, the pore size may be too small to sufficiently perform the role of a separator that helps the electrolyte solution or water move to the electrode surface, and when the pore size of the porous polymer support exceeds 0.55 μm, the average pore size of the water electrolysis separator manufactured may be large, which may increase the hydrogen gas permeability, and thus, the gas purity may be lowered.

[0090] In one embodiment of the present invention, the step of laminating the boron nitride mixture on the surface of the porous polymer support may be performed by a method of filtering or coating the boron nitride mixture on the surface of the porous polymer support, and more specifically, the method of filtering the boron nitride mixture on the surface of the porous polymer support may be a method of filtering the boron nitride mixture on the surface of the porous polymer support under reduced pressure to form a boron nitride film on the surface of the porous polymer support, and the method of coating the boron nitride mixture on the surface of the porous polymer support may be a dipping coating, spraying coating, drop casting coating, blade coating, or spin coating method, but is not limited thereto.

[0091]

[0092] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0093]

[0094] Example 1. Preparation of a water electrolysis membrane

[0095] Using the ultrasonic dispersion (tip sonication = probe sonication) technique, boron nitride nanotubes (BNNTs) were dispersed in NMP (N-Methyl-2-pyrrolidone), and then the solution in which the boron nitride nanotubes (BNNTs) were dispersed was poured onto a polytetrafluoroethylene (PTFE) membrane filter having a pore size of 0.20 μm, and the solvent was removed by applying reduced pressure, thereby manufacturing the water electrolysis membrane of Example 1.

[0096]

[0097] Example 2. Preparation of a water electrolysis membrane

[0098] A water electrolysis membrane was manufactured in the same manner as in Example 1 above, except that a polytetrafluoroethylene (PTFE) membrane filter having a pore size of 0.45 μm instead of 0.20 μm was used.

[0099]

[0100] Comparative Example 1. Preparation of Polytetrafluoroethylene (PTFE) Membrane Filter

[0101] A polytetrafluoroethylene (PTFE) membrane filter having a pore size of 0.20 μm used for filtering the boron nitride nanotube (BNNT) dispersion in Example 1 was prepared as Comparative Example 1.

[0102]

[0103] Comparative Example 2. Preparation of Zirfon perl UTP500

[0104] Agfa's Zirfon perl UTP500, which is currently commonly used as a commercial water electrolysis membrane, was prepared. Meanwhile, the Zirfon perl UTP500 is a composite of zirconia (ZrO2) and polyphenylene sulfide (PPS) polymer resin.

[0105]

[0106] Comparative Example 3. Manufacturing of a water electrolysis membrane

[0107] A water electrolysis membrane was manufactured in the same manner as in Example 1 above, except that ethanol (EtOH) instead of NMP (N-Methyl-2-pyrrolidone) was used as the solvent.

[0108]

[0109] Comparative Example 4. Manufacturing of a water electrolysis membrane

[0110] A water electrolysis membrane was manufactured in the same manner as in Example 2 above, except that ethanol (EtOH) instead of NMP (N-Methyl-2-pyrrolidone) was used as the solvent.

[0111]

[0112] Comparative Example 5. Preparation of Sustainment

[0113] We prepared Sustainion from Dioxide Materials, which is currently used as a commercial ion exchange membrane.

[0114]

[0115] Experimental Example 1. SEM (Scanning Electron Microscope) Analysis

[0116] SEM analysis was performed on the electrolytic membrane manufactured in Example 1 and the polytetrafluoroethylene (PTFE) membrane filter of Comparative Example 1, and the results are shown in FIGS. 1 and 2. FIGS. 1a to 1d show the surface of Comparative Example 1 photographed at magnifications of X 25, X 1,000, X 1,000, and X 10,000, respectively, and FIGS. 2a to 2d show the surface of Example 1 photographed at magnifications of X 25, X 1,000, X 5,000, and X 10,000, respectively.

[0117] As shown in Fig. 2, it can be confirmed that a dispersion of boron nitride nanotubes (BNNTs) was filtered on a polytetrafluoroethylene (PTFE) membrane filter, and compared to Fig. 1, it can be confirmed that the pore size on the surface was reduced overall. In other words, it was confirmed that the pore size was reduced by forming a film of boron nitride nanotubes inside and on the surface of the pores of the polytetrafluoroethylene (PTFE) membrane filter.

[0118]

[0119] Experimental Example 2. Evaluation of the Structure and Composition of Boron Nitride Nanotubes (BNNTs)

[0120] In order to evaluate the structure and composition of boron nitride nanotubes (BNNTs) in the water electrolysis membrane of Example 1, transmission electron microscopy (TEM) analysis and energy dispersive X-ray spectroscopy (EDX) analysis were performed, and the results are shown in FIGS. 3 to 6, respectively.

[0121] Figure 3 is an observation using a transmission electron microscope (TEM), and Figures 3a to 3f show the morphology of boron nitride nanotubes (BNNTs) observed at sizes of 0.5 μm, 500 nm, 200 nm, 50 nm, 20 nm, and 0.5 nm, respectively, and Figure 4 shows a spectrum obtained by performing electron energy loss spectroscopy (ELLS).

[0122] As shown in Figs. 3a to 3f, it was confirmed that the shape of the boron nitride nanotubes (BNNTs) was well maintained without deformation and without any separate impurities within the water electrolysis membrane. Meanwhile, referring to Fig. 3b, the size of the boron nitride nanotubes (BNNTs) was confirmed to be 0.5 μm in diameter (D) and 18.6 μm in length (L). In addition, referring to Fig. 4, it was confirmed that the BNNTs contained boron nitride (BN) bonds through the peaks of boron and nitrogen that appeared at 188 eV and 401 eV, respectively.

[0123] Figure 5 is an observation using Energy Dispersive X-ray Spectroscopy (EDX), in which Figure 5a shows a Bright Field (BF) image, Figure 5b shows a nitrogen (N) region in the mapping image, and Figure 5c shows a boron (B) region in the mapping image, respectively. In addition, Figure 6 shows the results of Energy Dispersive X-ray Spectroscopy (EDX) analysis as a spectrum, and the results of the analysis are quantified in mass percentage (mass %) and atomic percentage (atomic %) and are shown in Table 1 below.

[0124] As shown in FIG. 5, FIG. 6 and Table 1 below, it was confirmed that boron nitride compounds were present in the electrolytic separation membrane manufactured in Example 1 without any separate impurities.

[0125] ElementsMass %Atomic %B55.3861.76N43.1137.10

[0126]

[0127] Experimental Example 3. Pore Size Evaluation Using a Mercury Porosimeter

[0128] For the above Example 1 and Comparative Example 2, the distribution of pores with a size of 10,000 nm or less on the surface was analyzed using a mercury porosimeter, and the results are shown in Table 2 and Figure 7 below.

[0129] As shown in FIG. 7 and Table 2 below, the electrolysis membrane of Example 1 according to the present invention was found to have a higher pore distribution of 10,000 nm or less in size compared to the Zirfon perl UTP500 electrolysis membrane of Comparative Example 2. That is, it was confirmed that the electrolysis membrane of the present invention had a smaller pore size on average than that of Comparative Example 2. Meanwhile, since the smaller the pore size, the lower the hydrogen gas permeability of the electrolysis membrane, it was confirmed that the hydrogen gas purity can be increased by using the electrolysis membrane of Example 1 according to the present invention.

[0130] Sample Total intrusion volume (mL / g)Total Pore area(m) 2 / g)Average pore diameter(nm)Bulk density (g / mL)Porosity(%)Example 10.724641.66269.570.447452.3181Comparative example 20.504121.52293.701.044256.7744

[0131]

[0132] Experimental Example 4. Thermal Stability Evaluation

[0133] In order to evaluate the thermal stability of the electrolysis membrane of Example 1, thermogravimetric analysis (TGA) was performed, and the results are shown in Fig. 8. At this time, Fig. 8a is a graph showing the thermogravimetric analysis (TGA) results for Example 1, and Fig. 8b is a graph showing the thermogravimetric analysis (TGA) results for Comparative Example 1.

[0134] As shown in Fig. 8a, the results of thermogravimetric analysis showed that the water electrolysis membrane of Example 1 maintained thermal stability below 200°C and showed no mass change. A major mass loss of 59% occurred between 220°C and 450°C, where PTFE was decomposed into tetrafluoroethylene (TFE) and difluorocarbondiradicals (RCF2). An additional 30% mass loss occurred between 500°C and 600°C, where PTFE was generated into TFE, hexafluoropropene (HFP), cyclo-perfluorobutane (c-C4F8), and other fluorocarbons. After 800°C, 10% of the residue remained. Compared with the graph of Fig. 8b, it was clearly confirmed that the 10% residue was boron nitride nanotubes (BNNT). That is, it was confirmed that the water electrolysis membrane of Example 1 according to the present invention had excellent heat resistance.

[0135]

[0136] Experimental Example 5. Evaluation of Electrolyzer Efficiency

[0137] Electrolytic cell efficiency evaluation was performed using the membranes of Example 1, Example 2, Comparative Example 2, Comparative Example 3, Comparative Example 4, and Comparative Example 5, respectively, and the results are shown in Fig. 9 and Table 3 below. At this time, Fig. 9a is a graph showing the results of electrolytic cell efficiency evaluation using the LSV (Linear Sweep Voltammetry) analysis method, and Fig. 9b is a graph showing the results of electrolytic cell efficiency evaluation using the EIS (Electrochemical Impedance Spectroscopy) analysis method.

[0138] As shown in FIG. 9 and Table 3 below, when the membranes of Examples 1 and 2 were used under the same conditions, the voltage at a current density of 500 mA / cm² was lower than that of Comparative Example 4, and Example 1 was the lowest at 2.07 V. That is, it was confirmed that when the electrolysis membrane according to the present invention was used under the same conditions, it had improved performance as an electrolytic cell. In addition, the EI (Electrochemical Impedance Spectroscopy) analysis results confirmed that Example 1 had the lowest resistance value of 0.38 Ω.

[0139] ClassificationAnode(OER)MembraneCathode(HER)Pore size ofPTFE (μm)Thickness(mm)Temperature(℃)Cell Voltage(V)@ 500 mA / cm 2 HFR(Ω)Example 1NiBNNT-NMPNi0.200.26802.070.38Example 2NiBNNT-NMPNi0.450.26802.290.77Comparative Example 2NiZirfonNi-0.54802.350.42Comparative Example 3NiBNNT-EtOHNi0.200.25802.320.55Comparative Example 4NiBNNT-EtOHNi0.450.26802.381.12Comparative Example 5NiSustainionNi-0.16802.480.58

[0140]

[0141] Experimental Example 6. Hydrogen Permeability Evaluation

[0142] Electrochemical hydrogen permeation experiments were conducted for the above Examples 1, 2, Comparative Examples 1, and 2, and the results are shown in Table 4 and Figure 10 below.

[0143] As shown in Table 4 and Figure 10 below, it was confirmed that Example 1 exhibited the lowest hydrogen permeability. In particular, it was confirmed that Example 1 according to the present invention had a significantly lower hydrogen permeability compared to Comparative Example 2 despite having a thickness that was half that of Example 1.

[0144] SampleBreak through Time(sec)Thickness(cm)Diffusion coefficient of hydrogen(x10 -8 cm 2 / s)Current density(mA / cm 2 )Permeability(mol / cm / s)Example 111520.0263.8353.111358.384*10-10Example 29900.0264.4636.036441.627*10-9Comparative Example 18880.0161.8847.169641.189*10-9Comparative Example 210440.05418.2566.05583.389*10-9

Claims

1. Porous polymer support; and A porous water electrolysis separation membrane comprising a boron nitride compound inserted into the interior of the porous polymer support or formed on the surface thereof.

2. In paragraph 1, The above porous polymer support is, A porous water electrolysis membrane characterized by being a compound selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, and combinations thereof.

3. In paragraph 1, The above porous polymer support is, A porous water electrolysis membrane characterized by a pore size of 0.10 to 0.55 μm.

4. In paragraph 1, A porous water electrolysis membrane wherein the boron nitride compound has the form of boron nitride nanosheets (BNNS), boron nitride nanoparticles, boron nitride nanotubes (BNNT), or boron nitride nanoribbons (BNNR).

5. In paragraph 1, The above-mentioned water electrolysis membrane is a porous water electrolysis membrane characterized by an average pore size of 90 nm or less.

6. In paragraph 1, The above-mentioned porous electrolysis membrane is characterized by a thickness of 0.2 to 0.45 mm.

7. An alkaline water electrolysis system comprising the porous water electrolysis membrane of paragraph 1.

8. A step of preparing a boron nitride mixture by dispersing a boron nitride compound in a solvent; and A method for manufacturing a porous water electrolysis membrane, comprising the step of laminating the boron nitride mixture on the surface of a porous polymer support.

9. In paragraph 8, A method for manufacturing a porous water electrolysis separation membrane, characterized in that the solvent is at least one selected from the group consisting of water, amides, alcohols, glycols, polyhydric alcohols, glycol ethers, ketones, and esters.

10. In paragraph 8, A method for manufacturing a porous water electrolysis membrane, wherein the boron nitride compound has a form of boron nitride nanosheets (BNNS), boron nitride nanoparticles, boron nitride nanotubes (BNNT), or boron nitride nanoribbons (BNNR).

11. In paragraph 8, A method for manufacturing a porous water electrolysis separation membrane, characterized in that the porous polymer support is a compound selected from the group consisting of polypropylene, polyethylene, polyethylene terephthalate, polyimide, polytetrafluoroethylene, polyvinylidene fluoride, and combinations thereof.

12. In paragraph 8, The step of laminating the boron nitride mixture on the surface of the porous polymer support is: A method for manufacturing a porous water electrolysis membrane, which is performed by a method of filtering or coating the boron nitride mixture on the surface of the porous polymer support.

13. In paragraph 12, A method for manufacturing a porous water electrolysis separation membrane, characterized in that the method for filtering the boron nitride mixture on the surface of the porous polymer support comprises filtering the boron nitride mixture on the surface of the porous polymer support under reduced pressure to form a boron nitride film on the surface of the porous polymer support.

14. In paragraph 12, A method for manufacturing a porous water electrolysis membrane, characterized in that the method for coating the boron nitride mixture on the surface of the porous polymer support is a dipping coating, spraying coating, drop casting coating, blade coating or spin coating method.

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