Preparation process of flow battery diaphragm
By using a blade-type cast film coater and a multi-stage drying system, using PET film as the substrate and controlling the coating and drying parameters, the problems of uneven film thickness and deformation of finished products during storage of liquid flow battery separators were solved, achieving low-cost industrial production.
Patent Information
- Application Number
- CN202510780363.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-06-12
- Publication Date
- 2025-09-23
AI Technical Summary
The existing liquid flow battery membrane preparation technology has problems such as pores or uneven thickness on the membrane surface, easy wrinkling and deformation of the finished membrane after peeling, wasteful hot air discharge and high membrane production costs, making it difficult to achieve large-scale production.
Adopting a doctor blade cast film coater and a multi-stage drying system, using PET film as the substrate, controlling the coating parameters, drying temperature and air volume, and combining the heat recovery of fresh air and circulating air, the film thickness uniformity and the flat preservation of the finished film are achieved.
The results have improved the apparent quality of the flow battery separator, reduced costs and enabled industrialized production, solved the problems of uneven membrane thickness and deformation of finished products during storage, and reduced production costs.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of manufacturing ion exchange resin molding structures, and in particular relates to a preparation process of a liquid flow battery diaphragm. Background Art
[0002] Among the various components of energy storage flow batteries, proton exchange membranes (diaphragms) play a crucial role. They not only act as electronic insulators but also as a barrier to reactants, effectively separating reactants and transporting protons. Currently, the most commonly used proton exchange membranes are perfluorosulfonic acid-based membranes, such as DuPont's Nafion membranes. However, in recent years, problems with DuPont's Nafion series of membranes, such as their high price, poor ion selectivity, and severe cross-contamination, have become increasingly prominent, severely hindering the commercial development of flow battery membranes. Therefore, it is crucial to develop a new, safe, reliable, low-cost, and high-performance flow battery membrane material to promote the commercialization of my country's flow battery industry.
[0003] At present, there is a lot of research on proton exchange membranes for liquid flow batteries in China, such as resin materials such as polybenzimidazole (PBI), polyetheretherketone (PEEK), and polysulfone (PSF). The present invention is a new industrial production technology for proton exchange membranes made of sulfonated polyetheretherketone (SPEEK) material, including slurry preparation, coating, and drying process technologies.
[0004] In laboratory preparation of sulfonated polyetheretherketone (SPEEK) proton exchange membranes, the substrate is typically glass. After the slurry is prepared, it is poured into a glass mold and self-leveled. Alternatively, a laboratory doctor blade coater is used to apply the coating to the glass substrate. After coating, the glass mold or glass plate is placed in a forced-air drying oven for drying. After drying, the proton exchange membrane is peeled off.
[0005] Existing laboratory film-making technology, whether using self-leveling glass plate molds or experimental scraper coating machines, has the following technical disadvantages: 1. When the prepared wet film is placed in a blower drying oven for drying, due to the influence of the slurry's own fluidity and the levelness of the mold, the surface of the finished film after drying may have pores or uneven film thickness; 2. The finished film needs to be peeled off from the glass plate mold or glass plate before storage. If the peeled finished film is stored for a long time, wrinkles and deformation will occur; 3. The hot air from the blower drying box is directly discharged, resulting in large heat loss and increased production costs; 4. The preparation cost of glass plate molds or glass plates is high, they occupy a large space, and the overall film-making efficiency is low, making them impossible to produce on a large scale. Summary of the Invention
[0006] In response to the problems existing in the prior art, the present invention provides a preparation process for a liquid flow battery membrane to achieve the following invention objectives: to provide a liquid flow battery membrane material with good apparent quality, low cost and good performance.
[0007] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows: A preparation process for a flow battery diaphragm, comprising: slurry preparation, coating, and drying; The slurry is prepared by ball-milling sulfonated polyetheretherketone to obtain a powder with a particle size of 10 to 20 μm, then adding the powder to hexafluoroisopropanol, stirring at 60 to 90° C. until the powder becomes clear, then adding γ-aminopropyltriethoxysilane and zirconium phosphate, mixing evenly, and standing for 1 to 2 hours to obtain a slurry. The mass ratio of the sulfonated polyetheretherketone, hexafluoroisopropanol, γ-aminopropyltriethoxysilane, and zirconium phosphate is 0.8-1.2:10-14:0.005-0.07:0.009-0.011; The stirring rate is 30-50 r / min.
[0008] The coating method comprises the following steps: sieving the slurry and conveying it to a blade-type cast coating machine; selecting a PET film as the coating substrate; controlling the coating width to be 800-1200 mm, the wet film thickness to be 300-500 μm, the coating speed to be 0.5-2 m / min, and the slurry density to be 1.2-1.3 g / cm 3 ; In the coating method, the sieve is 50-200 mesh; The blade-type casting coater model is HDTF1200-20; The coating machine scraper height is set to 300-500 μm; The thickness of the PET film is 100 to 200 μm.
[0009] The drying method is to sequentially draw the wet film to 1#, 2#, 3#, 4#, 5#, and 6# drying ovens for drying, and then roll it up after cooling to obtain a sulfonated polyetheretherketone membrane, i.e., a liquid flow battery separator; In the drying method, 1# oven: temperature is 40~70℃; 2# oven: temperature is 50~75℃; 3# oven: temperature is 60~80℃; 4# oven: temperature is 70~90℃; 5# oven: temperature is 80~100℃; 6# oven: temperature is 70~90℃; The oven is constructed such that the air inlet is located at the top of the oven, and the air inlet is divided into fresh air and circulating air. There are two air outlets, located at the top and bottom of the oven respectively. Part of the hot air discharged from the oven is circulated back into the oven, and part is discharged to the exhaust gas recovery system to ensure that the interior of the oven is in a slightly negative pressure state, with a value of -5 to -20 kPa. The oven air volume is set to, 1# Oven: Total air flow rate 300~400Nm 3 / h, of which 20% to 40% is fresh air and 60% to 80% is circulating air; 2# Oven: Total air flow rate 300~500Nm 3 / h, of which 30% to 50% is fresh air and 50% to 70% is circulating air; 3# Oven: Total air flow rate 400~600Nm 3 / h, of which fresh air is 35% to 55% and circulating air is 45% to 65%; 4# oven: total air flow rate 500~700Nm 3 / h, of which fresh air is 45% to 65% and circulating air is 35% to 55%; 5# oven: total air flow rate 600~800Nm 3 / h, of which fresh air accounts for 50% to 70% and circulating air accounts for 30% to 50%; 6# oven: total air flow rate 500~700Nm 3 / h, of which 45% to 65% is fresh air and 35% to 55% is circulating air.
[0010] Compared with the prior art, the present invention has the following beneficial effects: 1. The use of cast film coating mechanism has achieved industrialized mass production. PET film is used as the film substrate, replacing the glass plate mold or glass plate. The PLC system can control the line speed of cast film coating, the residence time of each oven section, and the surface tension of the film. At the same time, the appropriate drying temperature and air volume are set to solve the problems of uneven film thickness and pores. 2. The finished film and the PET substrate are rolled up and stored together, and the finished film is peeled off when in use, which solves the problem of wrinkles and deformation of the finished film after long-term storage; 3. The hot air discharged from the oven can be partially recycled back to the oven, realizing the secondary utilization of heat and reducing production costs.
[0011] 4. By adjusting the temperature and air volume of each oven section, and the ratio of fresh air to circulating hot air, the optimal process parameters are obtained. At the same time, using PET film as the substrate reduces the cost of membrane production, realizes the industrial mass production of sulfonated polyetheretherketone proton exchange membrane, and promotes the commercialization process of domestic liquid flow batteries. DETAILED DESCRIPTION
[0012] Example 1 A process for preparing a flow battery diaphragm, comprising: 1. Slurry preparation Sulfonated polyetheretherketone was ball-milled to obtain a powder with a particle size of 15 μm, which was then added to hexafluoroisopropanol and stirred at 75°C until clear. γ-aminopropyltriethoxysilane and zirconium phosphate were then added, mixed evenly, and allowed to stand for 1.5 hours to obtain a slurry. The mass ratio of the sulfonated polyetheretherketone, hexafluoroisopropanol, γ-aminopropyltriethoxysilane, and zirconium phosphate is 1:12:0.006:0.01; The stirring rate is 40 r / min.
[0013] 2. Coating After sieving, the slurry was transported to a blade-type cast coating machine. The coating substrate was PET film. The coating width was controlled to be 1000 mm, the wet film thickness was 400 μm, the coating speed was 1.3 m / min, and the slurry density was 1.25 g / cm 3 ; The sieve is 140 mesh; The blade-type casting coater model is HDTF1200-20; The coating machine blade height is set to 400 μm; The PET film had a thickness of 150 μm.
[0014] 3. Drying The wet film is sequentially pulled to the 1#, 2#, 3#, 4#, 5#, and 6# drying ovens for drying, and then rolled up after cooling to obtain a sulfonated polyetheretherketone membrane, i.e., a liquid flow battery separator; In the drying method, 1# oven: temperature is 55℃; 2# oven: temperature is 65℃; 3# oven: temperature is 70℃; 4# oven: temperature is 80℃; 5# oven: temperature is 90℃; 6# oven: temperature is 80℃; The oven is constructed such that the air inlet is located at the top of the oven, and the air inlet is divided into fresh air and circulating air. There are two air outlets, located at the top and bottom of the oven respectively. Part of the hot air discharged from the oven is circulated back into the oven, and part is discharged to the exhaust gas recovery system to ensure that the interior of the oven is in a slightly negative pressure state, with a value of -10KPa. The oven air volume is set to, 1# Oven: total air flow rate 350Nm 3 / h, of which 30% is fresh air and 70% is recycled air; 2# Oven: total air flow rate 400Nm 3 / h, of which 40% is fresh air and 60% is recycled air; 3# Oven: total air flow rate 500Nm 3 / h, of which 45% is fresh air and 55% is circulating air; 4# oven: total air flow rate 600Nm 3 / h, of which 55% is fresh air and 45% is circulating air; 5# oven: total air flow rate 700Nm 3 / h, of which 60% is fresh air and 40% is recycled air; 6# Oven: total air flow rate 600Nm 3 / h, of which 55% is fresh air and 45% is recycled air.
[0015] Example 2 A process for preparing a flow battery diaphragm, comprising: 1. Slurry preparation The sulfonated polyetheretherketone was ball-milled to obtain a powder with a particle size of 10 μm, which was then added to hexafluoroisopropanol and stirred at 60°C until it became clear. γ-aminopropyltriethoxysilane and zirconium phosphate were then added, mixed evenly, and allowed to stand for 1 hour to obtain a slurry. The mass ratio of the sulfonated polyetheretherketone, hexafluoroisopropanol, γ-aminopropyltriethoxysilane, and zirconium phosphate is 0.8:10:0.005:0.009; The stirring rate is 30 r / min.
[0016] 2. Coating After sieving, the slurry was transported to a blade-type cast coating machine. The coating substrate was PET film. The coating width was controlled to be 800 mm, the wet film thickness was 300 μm, the coating speed was 0.5 m / min, and the slurry density was 1.2 g / cm 3 ; The sieve is 50 mesh; The blade-type casting coater model is HDTF1200-20; The coating machine blade height is set to 300 μm; The PET film had a thickness of 100 μm.
[0017] 3. Drying The wet film is sequentially pulled to the 1#, 2#, 3#, 4#, 5#, and 6# drying ovens for drying, and then rolled up after cooling to obtain a sulfonated polyetheretherketone membrane, i.e., a liquid flow battery separator; In the drying method, 1# oven: temperature is 40℃; 2# oven: temperature is 50℃; 3# oven: temperature is 60℃; 4# oven: temperature is 70℃; 5# oven: temperature is 80℃; 6# oven: temperature is 70℃; The oven is constructed such that the air inlet is located at the top of the oven, and the air inlet is divided into fresh air and circulating air. There are two air outlets, located at the top and bottom of the oven respectively. Part of the hot air discharged from the oven is circulated back into the oven, and part is discharged to the exhaust gas recovery system to ensure that the interior of the oven is in a slightly negative pressure state, with a value of -5Kpa. The oven air volume is set to, 1# Oven: total air flow rate 300Nm 3 / h, of which 20% is fresh air and 60% is recycled air; 2# Oven: total air flow rate 300Nm 3 / h, of which 30% is fresh air and 50% is recycled air; 3# Oven: total air flow rate 400Nm 3 / h, of which 35% is fresh air and 45% is recycled air; 4# oven: total air flow rate 500Nm 3 / h, of which 45% is fresh air and 35% is circulating air; 5# oven: total air flow rate 600Nm 3 / h, of which 50% is fresh air and 30% is recycled air; 6# Oven: total air flow rate 500Nm 3 / h, of which 45% is fresh air and 35% is recycled air.
[0018] Example 3 A process for preparing a flow battery diaphragm, comprising: 1. Slurry preparation The sulfonated polyetheretherketone was ball-milled to obtain a powder with a particle size of 20 μm, which was then added to hexafluoroisopropanol and stirred at 90°C until it became clear. γ-aminopropyltriethoxysilane and zirconium phosphate were then added, mixed evenly, and allowed to stand for 2 hours to obtain a slurry. The mass ratio of the sulfonated polyetheretherketone, hexafluoroisopropanol, γ-aminopropyltriethoxysilane, and zirconium phosphate is 1.2:14:0.07:0.011; The stirring rate is 50 r / min.
[0019] 2. Coating After sieving, the slurry was transported to a blade-type cast coating machine. The coating substrate was PET film. The coating width was controlled to be 1200 mm, the wet film thickness was 500 μm, the coating speed was 2 m / min, and the slurry density was 1.3 g / cm 3 ; The sieve has a mesh size of 50 to 200; The blade-type casting coater model is HDTF1200-20; The coating machine blade height is set to 500 μm; The PET film has a thickness of 200 μm.
[0020] The drying method is to sequentially draw the wet film to 1#, 2#, 3#, 4#, 5#, and 6# drying ovens for drying, and then roll it up after cooling to obtain a sulfonated polyetheretherketone membrane, i.e., a liquid flow battery separator; In the drying method, 1# oven: temperature is 70℃; 2# oven: temperature is 75℃; 3# oven: temperature is 80℃; 4# oven: temperature is 90℃; 5# oven: temperature is 100℃; 6# oven: temperature is 90℃; The oven is constructed such that the air inlet is located at the top of the oven, and the air inlet is divided into fresh air and circulating air. There are two air outlets, located at the top and bottom of the oven respectively. Part of the hot air discharged from the oven is circulated back into the oven, and part is discharged to the exhaust gas recovery system to ensure that the interior of the oven is in a slightly negative pressure state, with a value of -20Kpa. The oven air volume is set to, 1# Oven: total air flow rate 400Nm 3 / h, of which 40% is fresh air and 80% is recycled air; 2# Oven: total air flow rate 500Nm 3 / h, of which 50% is fresh air and 70% is recycled air; 3# Oven: total air flow rate 600Nm 3 / h, of which 55% is fresh air and 65% is circulating air; 4# oven: total air flow rate 700Nm 3 / h, of which 65% is fresh air and 55% is circulating air; 5# oven: total air flow rate 800Nm 3 / h, of which 70% is fresh air and 50% is recycled air; 6# Oven: Total air flow rate 700Nm 3 / h, of which 65% is fresh air and 55% is recycled air.
[0021] Example 4 A preparation process for a liquid flow battery separator is provided. Based on Example 1, the addition of γ-aminopropyltriethoxysilane and zirconium phosphate in step 1 is omitted, and the remaining steps remain unchanged.
[0022] Example 5 A preparation process for a liquid flow battery membrane is disclosed. Based on Example 1, step 2 is changed to sieving the slurry and then pouring it onto a glass plate, and then drying it by the method of step 3 to obtain the liquid flow battery membrane.
[0023] Test example 1. For the flow battery separators prepared in Examples 1 to 5, 10 locations were selected for each flow battery separator, and the thickness thereof was measured using a micrometer, and the deviation value was calculated.
[0024] The flow battery separators prepared in Examples 1 to 5 were stored for 2 months and then observed for wrinkles and deformation.
[0025] The test results are shown in Table 1: Table 1
[0026] 2. The flow battery membranes prepared in Examples 1 to 5 were tested for the following properties.
[0027] The test results are shown in Table 2: Table 2
[0028] From the above results, it can be seen that in Example 4, γ-aminopropyltriethoxysilane and zirconium phosphate were not added during the slurry preparation process, resulting in poor adhesion to the substrate PET film. The resulting flow battery separator was wrinkled during the later storage process. At the same time, the proton conductivity and tensile strength of the zirconium phosphate decreased. In Example 5, a glass plate is used as a substrate, and the prepared flow battery separator needs to be peeled off from the glass plate for storage, which makes it easy for the edge to shrink, wrinkle, and deform.
Claims
1. A process for preparing a flow battery diaphragm, characterized in that: The preparation method includes slurry preparation, coating, and drying; The slurry preparation method comprises the following steps: ball-milling sulfonated polyetheretherketone to obtain a powder with a particle size of 10 to 20 μm, adding the powder to hexafluoroisopropanol, stirring at 60 to 90° C. until the powder is clarified, and then adding γ-aminopropyltriethoxysilane and zirconium phosphate, mixing the mixture evenly, and standing the mixture for 1 to 2 hours to obtain a slurry.
2. The process for preparing a flow battery membrane according to claim 1, wherein: In the method for preparing the slurry, the mass ratio of sulfonated polyetheretherketone, hexafluoroisopropanol, γ-aminopropyltriethoxysilane, and zirconium phosphate is 0.8-1.2:10-14:0.005-0.07:0.009-0.011; The stirring rate is 30-50 r / min.
3. The process for preparing a flow battery membrane according to claim 1, wherein: The coating method comprises the following steps: sieving the slurry and conveying it to a blade-type cast coating machine; selecting a PET film as the coating substrate; controlling the coating width to be 800-1200 mm, the wet film thickness to be 300-500 μm, the coating speed to be 0.5-2 m / min, and the slurry density to be 1.2-1.3 g / cm 3 .
4. The process for preparing a flow battery membrane according to claim 3, wherein: In the coating method, the sieve is 50-200 mesh; The blade-type cast film coater model is HDTF1200-20; The coating machine blade height is set to 300-500 μm; The thickness of the PET film is 100 to 200 μm.
5. The process for preparing a flow battery membrane according to claim 1, wherein: The drying method is to sequentially pull the wet film to 1#, 2#, 3#, 4#, 5# and 6# drying ovens for drying, and then roll it up after cooling to obtain a sulfonated polyetheretherketone membrane, i.e., a liquid flow battery separator.
6. The process for preparing a flow battery membrane according to claim 5, characterized in that: In the drying method, the temperature of oven 1# is 40-70°C; 2# oven: temperature is 50~75℃; 3# oven: temperature is 60~80℃; 4# oven: temperature is 70~90℃; 5# oven: temperature is 80~100℃; 6# Oven: temperature is 70~90℃.
7. The process for preparing a flow battery membrane according to claim 5, wherein: In the drying method, the structure of the oven is as follows: the air inlet is located at the upper part of the oven, the air inlet types are divided into fresh air and circulating air, and there are two air outlets, located at the upper and lower parts of the oven respectively. Part of the hot air discharged from the oven is circulated back to the oven, and part is discharged to the exhaust gas recovery system to ensure that the interior of the oven is in a slightly negative pressure state, with a value of -5 to -20Kpa.
8. The process for preparing a flow battery membrane according to claim 5, wherein: In the drying method, the oven air volume is set to, 1# Oven: Total air flow rate 300~400Nm 3 / h, of which 20% to 40% is fresh air and 60% to 80% is circulating air; 2# Oven: Total air flow rate 300~500Nm 3 / h, of which 30% to 50% is fresh air and 50% to 70% is circulating air; 3# Oven: Total air flow rate 400~600Nm 3 / h, of which fresh air is 35% to 55% and circulating air is 45% to 65%; 4# oven: total air flow rate 500~700Nm 3 / h, of which fresh air is 45% to 65% and circulating air is 35% to 55%; 5# oven: total air flow rate 600~800Nm 3 / h, of which fresh air accounts for 50% to 70% and circulating air accounts for 30% to 50%; 6# oven: total air flow rate 500~700Nm 3 / h, of which 45% to 65% is fresh air and 35% to 55% is circulating air.