Patent Application
20240222673
This application claims the priority benefit of Taiwan application serial no. 111150085, filed on Dec. 27, 2022. The entirety of the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.
The disclosure relates to a high-efficiency bipolar membrane and a manufacturing method thereof.
In order to meet the goal of net zero carbon emissions by 2050, traditional energy-intensive industries (such as petrochemical industry, steel industry, semiconductor industry, cement industry, etc.) urgently need corresponding strategies to cope with and transform towards low-carbon or zero-carbon processes. Applications related to electrical grid regulation, alternative energy or renewable energy must also focus on their green power storage and electrical grid security, or the use of low-carbon energy chemicals. Among them, hydrogen can not only promote low-carbon industries, but also improve the competitiveness of products in the face of international carbon fees.
However, at this stage, there are still many challenges in the key technologies of hydrogen energy breakthroughs, such as effectively improving conversion efficiency and reducing costs. Although the bipolar membrane is commercially available at present, there is still a need for improvement in the overall electrochemical properties and interface stability.
A bipolar membrane of the disclosure includes a porous support material, a cation exchange membrane and an anion exchange membrane. The porous support has opposing first and second sides. The cation exchange membrane is disposed on the first side of the porous support material, wherein a material of the cation exchange membrane penetrates into pores of the first side and combines with the porous support material. The anion exchange membrane is disposed on the second side of the porous support material, wherein a material of the anion exchange membrane penetrates into pores of the second side and combines with the porous support material. The cation exchange membrane is not in contact with the anion exchange membrane.
A method of manufacturing a bipolar membrane of the disclosure includes the following steps. An anion exchange membrane is formed on a substrate, and then a porous support material having opposing first and second sides covers on the anion exchange membrane, and a material of the anion exchange membrane is allowed to penetrate and fill into pores of the second side of the porous support material. Then, a cation exchange membrane is formed on the first side of the porous support material, and allowing a material of the cation exchange membrane to penetrate and fill into pores of the first side of the porous support material, wherein the material of the cation exchange membrane is not in contact with the material of the anion exchange membrane. Afterwards, the substrate is removed.
In order to make the above-mentioned features and advantages of the disclosure more comprehensible, the following specific embodiments are described in detail together with the accompanying drawings.
Embodiments are listed below and described in detail with accompanying drawings, but the provided embodiments are not intended to limit the scope of the disclosure. In addition, the dimensions of the components in the drawings are drawn for the convenience of description, and do not represent their actual size ratios.
Referring to
The porous support material 102 includes a glass fiber cloth, an electrospun polyvinylidene fluoride (PVDF) nanofiber membrane, a non-woven graphite cloth, or a polymer fabric. The porous support material 102 contains pores 102p. These pores 102p are exposed at the first side 102a and the second side 102b, and the pores 102p in the porous support material 102 are communicated with each other. The material of the polymer fabric is, for example, polyetheretherketone (PEEK), polyester, polypropylene, perfluoroalkoxy (PFA), or a combination thereof.
The ratio (t2/t1) of the thickness t2 of the anion exchange membrane AEM to the thickness t1 of the cation exchange membrane CEM can be 0.3-1. For example, the thickness t2 of the anion exchange membrane AEM can be 12-40 μm, and the thickness t1 of the cation exchange membrane CEM can be 40-80 μm. In one embodiment, t2/t1 is 0.3-0.5.
In one embodiment, the material of the cation exchange membrane includes a polymer represented by formula 1,
in formula 1, n is 5-14, m is 1-2, and x is 200-1000.
In another embodiment, the material of the cation exchange membrane includes a polymer having repeating units represented by formula 2, formula 3 and formula 4,
in formula 2, R1 represents C1-C8 alkyl group, C1-C8 cycloalkyl group, C1-C8 alkoxy group, or C1-C8 alkoxyalkyl group, and n is 0 or an integer of 1-5; and in formula 3, R2 represents C6-C16 arylene group, C1-C8 alkylene group, C1-C8 cycloalkylene group, or C1-C8 alkoxy alkylene group, A1− represents SO3−, NO3−, or COO−, and R1+ represents H+, Li+, Na+, K+, or NH4+.
For example, the material of the cation exchange membrane includes a polymer represented by formula 5,
in formula 5, the ratio of a to (b+c) is between 60:40 and 85:15.
In one embodiment, the material of the anion exchange membrane includes a polymer having repeating units represented by formula 6 and formula 7,
in formula 6, X represents CH2
Y
CH2
, i and j are each independently 0 or an integer of 1-6, and Y is —O—, —S—, —CH2—, or —NH—; A2 represents F−, Cl−, Br−, I−, OH−, HCO3−, HSO4−, SbF6−, BF4−, H2PO4−, H2PO3−, or H2PO2−; and R2+ represents
wherein R4 and R5 are independently hydrogen or C1-C8 alkyl group; and in formula 7, R3 represents a C1-C8 alkyl group.
For example, the material of the anion exchange membrane includes a polymer represented by formula 8,
in formula 8, o is 0.1-0.99
In another embodiment, the anion exchange membrane includes a polymer polymerized by a styrene-based monomer, an ammonium-containing heterocyclic monomer, and a monomer having conjugated double bonds or an acrylate ester monomer.
For example, the material of the anion exchange membrane includes a polymer represented by formula 9,
in formula 9, a ratio of z to x is between 1:10 and 50:1, and a ratio of z to y is between 1:10 and 50:1.
In
Since the first interface additive 202 can improve the water balance and/or ion transport balance of the cation exchange membrane CEM, the conductivity of the cation exchange membrane CEM will increase. In order to cope with the conductivity change of the cation exchange membrane CEM, it can be needed to thin or thicken the thickness t2′ of the anion exchange membrane AEM, so that the time for anions and cations to reach the center of the porous support material 102 is the same. In some embodiments, when the conductivity of the cation exchange membrane CEM increases, the ratio (t2′/t1′) of the thickness t2′ of the anion exchange membrane AEM to the thickness t1′ of the cation exchange membrane CEM can be 0.3-0.5.
In
In another embodiment, the bipolar membrane in
Referring to
Then, referring to
Next, referring to
Then, referring to
Then, referring to
Next, referring to
Several experiments are listed below to verify the effect of the disclosure, but these experiments and their results are not intended to limit the scope of application of the disclosure.
Analysis Method
The bipolar membrane was cut into a size of 6.5 cm×8.5 cm and was fixed in the test fixture, and the active area was 5 cm×5 cm.
The anion exchange membrane AEM side of the bipolar membrane was disposed faced the anode, and the cation exchange membrane CEM side of the bipolar membrane was disposed faced the cathode. The electrode nets were correspondingly placed on both sides of the bipolar membrane, a distance between the electrode net and the bipolar membrane was 0.5 cm, and the anode electrode net and the cathode electrode net were respectively an iridium-tantalum-titanium net and a platinum-titanium net.
The anolyte and the catholyte were 2M KOH(aq), 1M H2SO4(aq), respectively.
The final current-voltage curve of the bipolar membrane was obtained by using a potentiostatic ammeter (Autolab PGSTAT30/Booster 10A) with the settings of voltage scanning range of 0.3V-2.0V.
The specific surface area (BET) of the interface additive was measured using a specific surface area analyzer (BET) (Micromeritics ASAP 2020). The steps of the measurement were: (1) weighing the weight of the empty sample tube; (2) filling the sample tube with the sample and weighing; (3) after degassing by the machine, weighing and calculating to obtain the sample weight; and (4) measuring and analyzing the specific surface area by the analyzer.
The steps for preparing the bipolar membrane were as follows.
First, the material of AEM was added into a solvent (dimethylacetamide, DMAc) to prepare a polymer solution.
Then, 10 wt % Al2O3 was added to the polymer solution, and an anion exchange membrane was formed by coating the solution with a doctor blade. After that, a glass fiber cloth (having thickness of 40 μm) was put on the anion exchange membrane, and the formed membrane was dried with an infrared (IR) light source and then cooled down for later use.
A cation exchange membrane was formed by coating a Nafion/DMAc solution on the surface of the glass fiber cloth with the doctor blade, and the cation exchange membrane was dried with the IR light source, a bipolar membrane of Experimental Example 1 was obtained. In the formed bipolar membrane, the anion exchange membrane has a thickness of 45 μm, and the cation exchange membrane has a thickness of 50 μm.
After analysis, the current density at 1.2V was 86 mA/cm2.
The same materials of AEM and CEM as Experimental Example 1 were used, but there was no porous support material.
The material of AEM was added into a solvent (DMAc) to prepare a polymer solution, and an anion exchange membrane was formed by coating the polymer solution with a doctor blade. Then, the formed membrane was dried with an IR light source and then cooled down for later use.
Next, a cation exchange membrane was formed on the surface of AEM by coating a Nafion/DMAc solution with the doctor blade, and dried with the IR light source, a bipolar membrane of Comparative Example 1 was obtained. In the formed bipolar membrane, the anion exchange membrane has a thickness of 30 μm, and the cation exchange membrane has a thickness of 60 μm.
After analysis, the current density at 1.2V was 63 mA/cm2. Thus, the bipolar membrane of Comparative Example 1 without a porous support material is significantly lower than the bipolar membrane of the disclosure in terms of current density.
The same raw materials as Experimental Example 1 were used, but the anion exchange membrane (AEM) was replaced with the polymer represented by formula 9 and prepared according to the embodiment of patent application of TW I612089B.
The steps for preparing the bipolar membrane were as follows.
First, the material of AEM was added into a solvent (dimethylacetamide, DMAc) to prepare a polymer solution.
Then, an anion exchange membrane was formed by coating the solution with a doctor blade, and a glass fiber cloth (having thickness of 40 μm) was put on the anion exchange membrane. After that, the formed membrane was dried with an infrared (IR) light source and then cooled down for later use.
A cation exchange membrane was formed on the surface of the glass fiber cloth by coating a Nafion/DMAc solution with the doctor blade, and was dried with the IR light source, a bipolar membrane of Experimental Example 2 was obtained. In the formed bipolar membrane, the anion exchange membrane has a thickness of 40 μm, and the cation exchange membrane has a thickness of 90 μm.
After analysis, the current density at 1.2V was 85 mA/cm2.
The same raw materials as Experimental Example 1 were used. The steps for preparing the bipolar membrane were as follows.
First, the material of AEM was added into a solvent (DMAc) to prepare a polymer solution.
Then, an anion exchange membrane was formed by coating the solution with a doctor blade, and a glass fiber cloth (having thickness of 40 μm) was put on the anion exchange membrane. After that, the formed membrane was dried with an IR light source to a suitable degree of dryness and then cooled down for later use. The drying procedure was maintaining the temperature at 80-90° C. for 10 minutes, raising the temperature to 100° C.-110° C. and maintaining for 10 minutes, and then raising the temperature to 140-150° C. and maintaining for 10 minutes.
In addition, a Nafion/DMAc solution was coated on a surface of a polyethylene terephthalate (PET) substrate with the doctor blade, and the coating was dried with the IR light source to form a cation exchange membrane layer for later use.
Afterwards, the above cation exchange membrane was placed on the surface of the anion exchange membrane/glass fiber cloth composite, so that the order thereof was cation exchange membrane/glass fiber cloth/anion exchange membrane. Then, the formed membranes were hot pressing with a hot-pressing machine at 130° C. for 3 minutes, a bipolar membrane was obtained. In the formed bipolar membrane, the anion exchange membrane has a thickness of 15 μm, and the cation exchange membrane has a thickness of 50 μm.
After analysis, the current density at 1.2V was 112 mA/cm2. Therefore, the bipolar membrane produced by hot pressing has a better current density than the bipolar membrane produced by coating (Experimental Example 1).
The same materials of AEM and porous support material as Experimental Example 1 were used. However, the material of CEM was replaced with the polymer represented by formula 5 and prepared according to the embodiment of patent application of TW I717789B, and in formula 5, a is 0.24, b is 0.16, and c is 0.6.
The steps for preparing the bipolar membrane were as follows.
First, the material of AEM was added into a solvent (DMAc) to prepare a polymer solution.
Then, an anion exchange membrane was formed by coating the solution with a doctor blade, and a surface of the formed membrane was dried with an IR light source to a suitable degree of dryness as described in Experimental Example 3. After that, a glass fiber cloth (having thickness of 40 μm) was put on the anion exchange membrane, and the glass fiber cloth and the anion exchange membrane were laminated by rolling at 100° C.
In addition, a mixed solution of the material of CEM and DMAc was coated on the surface of a PET substrate with the doctor blade, and the coating was dried with the IR light source to form an anion exchange membrane layer for later use.
Afterwards, the above cation exchange membrane was placed on the surface of the anion exchange membrane/the glass fiber cloth composite, so that the order thereof was cation exchange membrane/glass fiber cloth/anion exchange membrane. Then, the formed membranes were laminated by rolling at 100-105° C., to form a bipolar membrane as shown in
After analysis, the current density at 1.2V can be as high as 203 mA/cm2.
A bipolar membrane was prepared in the same manner as Experimental Example 4, but the thickness of the anion exchange membrane is 20 μm, and the thickness of the cation exchange membrane is 45 μm.
After analysis, the current density at 1.2V was 171 mA/cm2.
A bipolar membrane was prepared in the same manner as Experimental Example 4, but with the following two differences. The first one was that the material of CEM was also the polymer represented by formula 5, but in formula 5, a is 0.32, b is 0.17, and c is 0.42. The second one was to adjust the coating gap formed by the doctor blade in the step of coating the anion exchange membrane, so that the thickness of the dried membrane of the anion exchange membrane is 15 μm, 20 μm, and 25 μm respectively. The thickness of the cation exchange membrane remains 50 μm. In Experimental Examples 6-8, the distance between the anion exchange membrane and the cation exchange membrane is 30 μm.
Table 1 shows the results obtained after analysis.
It can be obtained from Table 1 that the current density is excellent when the ratio of thickness is between 0.3 and 0.5.
The same analysis method as other Experimental Examples was adopted, and it was obtained that the current density of Comparative Example 2 at 0.97V was 77 mA/cm2, and the current density of Comparative Example 3 at 1.2V was 0.64 mA/cm2. It is noted that due to detection limitation of the electrochemical test, the actual current density of Comparative Example 2 at 1.2V can't be measured, so only the highest current density and its corresponding potential were recorded.
Therefore, the bipolar membrane of the disclosure is significantly better than the commercially available membrane in terms of current density.
The bipolar membrane of Experimental Example 1 and the BP-1E bipolar membrane of Comparative Example 2 were analyzed in electrolytes with different concentrations, and the results were obtained and shown in
From the comparison of
In addition, from the visual observation, it was observed that the BP-1E bipolar membrane of Comparative Example 2 reacted at a high electrolyte solution concentration, and foaming and interfacial peeling occurred.
Therefore, compared with the commercially available membrane of Comparative Example 2, the bipolar membrane of Experimental Example 1 has more stable operating property.
The same raw materials as Experimental Example 6 were used, and an acidified conductive carbon material serving as the first interface additive was additionally prepared in the following manner.
15 g of conductive carbon material was added to 600 ml of concentrated nitric acid (HNO3, 60˜70%), and the mixture was stirred at 100° C. for 8 hours and then cooled down to room temperature. The steps of adding water (1 L deionized water), pumping air, and filtering were repeated to obtain a solid carbon material.
Then, the solid carbon material was mixed with deionized water, and then the pH value of the solution was adjusted to 7.0 with ammonia water (NH3, 35%). After stirring, the solution was pumped and filtered. Then, the steps of adding water (1 L deionized water), pumping air, and filtering were repeated, to obtain an acidified conductive carbon material.
The acidified conductive carbon material was placed in an 80° C. hot air circulation oven to dry for 24 hours, and then was cooled down, grinded and stored. The acidified conductive carbon material was sieved (with 150 mesh sieve) before use.
The acidified conductive carbon material is represented by HECP300 and HECP600, and the hydrophilic degree of the surface and BET of HECP300 and HECP600 are as follows,
The steps for preparing the bipolar membrane were as follows.
First, the material of AEM was added into a solvent (DMAc) to prepare a polymer solution. Then, an anion exchange membrane was formed by coating the polymer solution with a doctor blade, and the formed membrane was dried with an IR light source to a suitable degree of dryness as described in Experimental Example 3. After that, a glass fiber cloth (having thickness of 40 μm) was put on the anion exchange membrane, and the glass fiber cloth and the anion exchange membrane were laminated by rolling at 100° C. The thickness of the anion exchange membrane is 15 μm.
Then, a coating slurry containing a first interface additive was prepared, and the type and content of the first interface additive were respectively recorded in Table 2 below. The coating slurry includes the first interface additive, a solvent (DMAc), and material of CEM serving as an adhesive. After mixing and dispersing, the coating slurry was coated on the surface of the glass fiber cloth with a doctor blade, and then the coating was dried with an IR light source. After that, the first interface additive was weighed to calculate the content.
Next, a mixed solution of the material of CEM and DMAc was coated on the surface of a PET substrate with the doctor blade, and the coating was dried with an IR light source to a suitable degree of dryness as described in Experimental Example 3.
Afterwards, the above cation exchange membrane was placed on the surface of the anion exchange membrane/the glass fiber cloth with the first interface additive composite, so that the order thereof was anion exchange membrane/glass fiber cloth/cation exchange membrane. Then, the above membranes were combined by rolling, a bipolar membrane was obtained. The cation exchange membrane has a thickness of 50 μm.
After analysis, the current density was also recorded in Table 2 below.
Due to the detection limitation of the electrochemical test, the actual current density of Experimental Example 13 at 1.2V can't be measured, so only the highest current density and its corresponding potential were recorded.
It can be obtained from Table 2 that the addition of the acidified conductive carbon material as the first interface additive can improve the current density, and with the increase of the hydrophilic degree of the surface of the first interface additive or the increase of the content of the first interface additive, the current density can be further improved.
A bipolar membrane was prepared in the same manner as Experimental Example 13, but the first interface additive was replaced with the metal oxide powder in Table 3 below.
The current densities obtained after the analysis are also described in Table 3 below.
Due to the detection limitation of the electrochemical measuring equipment, the actual current densities of Experimental Examples 15, 16 and 18 at 1.2V can't be measured, so only the highest current densities and their corresponding potentials are recorded.
It can be obtained from Table 3 that addition of the metal oxide powder as the first interface additive can also improve the current density.
The same raw materials as Experimental Example 6 were used, but the porous support material was replaced with electrospun polyvinylidene fluoride (PVDF) nanofiber membrane. The detailed preparation parameters and methods of the electrospun PVDF nanofiber membrane was as follows.
The electrospinning time was 7 minutes, and the thickness of the PVDF-HFP nanofiber membrane was 7 to 10 μm.
The steps for preparing the bipolar membrane were as follows.
First, the material of AEM was added into a solvent (DMAc) to prepare a polymer solution. Then, an anion exchange membrane was formed by coating the polymer solution with a doctor blade, and the formed membrane was dried with an IR light source to a suitable degree of dryness as described in Experimental Example 3. After that, a PVDF-HFP nanofiber membrane was put on the anion exchange membrane, and the PVDF-HFP nanofiber membrane and the anion exchange membrane were laminated by rolling at 100° C. The thickness of the anion exchange membrane is 15 μm.
Next, a mixed solution of the material of CEM and DMAc was coated on the surface of a PET substrate with the doctor blade, and the coating was dried with the IR light source to a suitable degree of dryness as described in Experimental Example 3.
Afterwards, the above cation exchange membrane was placed on the surface of the anion exchange membrane/the PVDF-HFP nanofiber membrane composite, so that the order thereof is cation exchange membrane/PVDF-HFP nanofiber membrane/anion exchange membrane. Then, the above membranes were combined by rolling to form a bipolar membrane. The cation exchange membrane has a thickness of 50 μm.
After analysis, the current density at 1.2V was 61 mA/cm2.
The same preparation method and raw materials as Experimental Example 6 were used, but the porous support material was replaced with a non-woven graphene fabric having a thickness of 95-105 μm (purchased from Xincai Industrial Co., Ltd.).
After analysis, the current density at 1.2V was 132 mA/cm2.
Therefore, it can be obtained from Experimental Examples 19-20 that the use of different porous support materials also has an improvement.
In summary, the bipolar membrane of the disclosure includes the cation exchange membrane and the anion exchange membrane separated by the porous support material, and the cation exchange membrane and the anion exchange membrane penetrate into the pores of both sides of the porous support material. Thus, the electrochemical properties of the membrane and interface stability are improved, and the strength of the bipolar membrane is also improved. In addition, by adding the interface additives, the water balance and/or ion transport balance of the cation exchange membrane and/or the anion exchange membrane can be improved, thereby improving conductivity.
Although the disclosure has been disclosed above with the embodiments, it is not intended to limit the disclosure. Anyone with ordinary knowledge in the technical field can make some changes and modifications without departing from the spirit and scope of the disclosure. The scope of protection of the disclosure should be defined by the scope of the appended patent application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 111150085 | Dec 2022 | TW | national |
