Highly conductive ion-conducting a / b composite membranes for flow batteries and methods of making the same

Abstract

The application belongs to the technical field of separators for energy storage liquid flow batteries, and relates to a high-conductivity ion-conducting A / B composite membrane for liquid flow batteries and a preparation method thereof. The application is characterized in that different types of functional additives are uniformly dispersed into a high-molecular polymer solution, an electrostatic spinning method is used to prepare different functional porous reinforcing layers, the surface of the porous reinforcing layer is treated, and finally a high-conductivity film-forming resin solution and the modified porous supporting layer are compounded to prepare the high-conductivity ion-conducting A / B composite membrane. The composite membrane prepared by the application has good activity-substance blocking capacity, low swelling rate and high conductivity.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of separators for energy storage flow batteries, and particularly relates to a high-conductivity ion-conducting A / B composite membrane for flow batteries and a preparation method thereof. BACKGROUND

[0002] Fossil energy (such as coal, oil and natural gas) as an important part of the energy structure is facing resource depletion due to long-term exploitation, which leads to serious environmental problems. In order to seek the sustainable development of human beings and realize the diversified use of energy, the development of green renewable energy has become the primary energy issue of each country. Renewable energy represented by solar energy, tidal energy and wind energy is derived from nature and provides infinite energy for human beings. However, the discontinuity and intermittency of renewable energy such as solar energy and wind energy make it an unstable power source, which does not match the stable power demand. In order to ensure the stable and reliable operation of the power grid system, a series of reliable measures such as energy storage technology must be adopted to balance the power generation and real-time power demand and ensure the safe operation of the power grid.

[0003] Among many energy storage technologies, electrochemical energy storage is favored due to its environmental friendliness, high energy storage efficiency and mature technology. Electrochemical energy storage technology has short-term and long-term discharge capacity, high energy density and high efficiency, making it an ideal choice for energy storage applications in different scenarios.

[0004] Among electrochemical energy storage batteries, flow batteries (RFB) are considered as one of the ideal choices for large-scale energy storage due to their high safety, high reliability and long cycle life. At present, some flow batteries such as all-vanadium flow batteries, chromium-iron flow batteries, zinc-bromine flow batteries and zinc-based flow batteries are in the demonstration stage and close to commercialization. Flow batteries have their unique design, which realizes the independent regulation of battery capacity and power. Since the active material is stored in the flowing electrolyte, it shows incomparable capacity advantage and can realize true long-time energy storage (>4 hours), which is suitable for large-scale energy storage scenarios such as renewable energy grid connection.

[0005] As a key material of flow batteries, the separator plays an important role in blocking the positive and negative electrodes, preventing short circuit and cross contamination. At the same time, the separator also plays a role in conducting carriers to form an electronic circuit, ensuring the rapid completion of the oxidation-reduction reaction of the positive and negative active materials, etc. The performance of the separator directly affects the working efficiency and capacity retention ability of the battery. An ideal separator should have the following characteristics: good active material blocking ability, low capacity decay; high proton conductivity, high mechanical strength, low cost, good chemical stability, which ensures the long-term stable operation of the battery. However, the commercialized Nafion membrane has poor ion selectivity due to the water swelling of sulfonic acid groups, which affects the battery performance.

[0006] Therefore, how to balance the conductivity and the ability of blocking active substances of the membrane, and reduce the swelling rate under the premise of ensuring basic performance has been the focus of membrane material research in liquid flow batteries. SUMMARY

[0007] In view of the above technical problems, the present application provides a high-conductivity ion-conducting A / B composite membrane for a liquid flow battery and a preparation method thereof. The present application uniformly disperses different types of functional additives into a high-molecular polymer solution, uses an electrospinning method to prepare different functional porous reinforcing layers, then processes the surface of the porous reinforcing layer, and finally composites a high-conductivity film-forming resin solution with the modified porous support layer to prepare a high-conductivity ion-conducting A / B composite membrane. The composite membrane prepared by the present application has good ability to block active substances, low swelling rate, and high conductivity.

[0008] In order to achieve the above-mentioned purpose, the following technical solutions are adopted.

[0009] A preparation method of a high-conductivity ion-conducting A / B composite membrane for a liquid flow battery, comprising the following steps:

[0010] Step 1: dispersing a high-molecular polymer in a solvent to prepare a high-molecular polymer dispersion solution A, dispersing a functional additive containing an anion exchange group in a solvent to prepare an additive dispersion solution B, and finally uniformly mixing the high-molecular polymer solution A and the additive dispersion solution B to prepare a high-molecular polymer solution C.

[0011] Step 2: dispersing a functional additive containing a cation exchange group in a solvent to prepare an additive dispersion solution D, and uniformly mixing the high-molecular polymer solution A and the additive dispersion solution D to prepare a high-molecular polymer solution E.

[0012] Step 3: using an electrospinning method to spin the high-molecular polymer solution C prepared in step 1.

[0013] Step 4: spinning the high-molecular polymer solution E prepared in step 2 on the spun layer of step 3 to prepare an A / B porous reinforcing layer F with different pore structures.

[0014] Step 5: surface treating the A / B porous reinforcing layer prepared in step 4 to prepare an A / B porous reinforcing layer H.

[0015] Step 6: dissolving a high-conductivity film-forming resin in a solvent, the dissolution condition being to heat in a 140-250℃ reaction kettle for 4-24 hours, stirring and dissolving, and naturally cooling after heat preservation to obtain a film-forming resin solution J.

[0016] Step 7, the A / B porous reinforced layer H prepared in step 5 is immersed into the film-forming resin solution J prepared in step 6 and is ultrasonically treated for 2-24 hours, is taken out after being kept at a certain temperature for a certain time, is taken out after the solution is shaped, and is then hot-pressed to prepare a high-conductivity ion-conducting A / B composite film with a certain thickness.

[0017] Further, in step 1, the high-molecular polymer is one or more combinations of polyimide (PI), polypropylene (PEI), polyvinylidene fluoride (PVDF), poly-m-phenylene isophthalamide (PMIA), etc.

[0018] Further, in step 1, the solvent is one or more combinations of anhydrous ethanol, deionized water, methanol, isopropyl alcohol, dimethylbenzene, n-propanol, N, N-dimethylformamide, N, N-dimethylacetamide, dimethyl sulfoxide, N-Base pyrrolidone, etc.

[0019] Further, in step 1, the functional additive containing an anion exchange group is one or more combinations of quaternary ammonium chitosan, quaternary ammonium polyvinyl alcohol, quaternary ammonium ethylene pyrrolidone polymer, quaternary ammonium polyether ether ketone, quaternary ammonium polyimide, quaternary ammonium polyether sulfone, etc.

[0020] Further, in step 1, the concentration of the high-molecular polymer dispersion liquid A is 1wt%-15wt%; the concentration of the additive dispersion liquid B is 0.2wt%-5wt%; the high-molecular polymer solution C contains the functional additive with an anion exchange group: the mass ratio of the high-molecular polymer is 1:10-1:100.

[0021] Further, in step 2, the functional additive containing a cation exchange group is one or more combinations of sulfonated graphene, sulfonated carbon black, sulfonated nanocarbon tube, sulfonated mesoporous carbon dioxide, sulfonated polyether ether ketone, sulfonated polyimide, sulfonated polyether sulfone, etc.

[0022] Further, in step 2, the concentration of the additive dispersion liquid D is 0.2wt%-5wt%; the functional additive containing a cation exchange group in the high-molecular polymer solution E: the mass ratio of the high-molecular polymer is 1:10-1:100.

[0023] Further, in steps 3, 4, the spinning process parameters are: voltage 10-20kV, solution flow rate 0.9-1.3mL / h, needle distance 10-15cm, solution concentration 2wt%-25wt%; the diameter of the fiber is between 100nm-900nm.

[0024] Further, in step 5, the surface treatment is one or more combinations of etching method, oxidation method, plasma treatment method, ultraviolet radiation method, laser irradiation method, etc.

[0025] Further, in step 6, the high-conductivity film-forming resin is a perfluorosulfonic acid resin, a sulfonated polyether sulfone, a sulfonated polyether ketone, a perfluorocarboxylic acid resin, a sulfonated polyimide, a sulfonated polysulfone, or the like.

[0026] Further, in step 6, the solvent is one or a combination of deionized water, anhydrous ethanol, isopropyl alcohol, n-propanol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-methyl pyrrolidone, or the like.

[0027] Further, in step 6, the concentration of the film-forming resin solution J is 2wt%-25wt%.

[0028] Further, in step 7, the temperature is between 80°C and 170°C, preferably between 100°C and 120°C.

[0029] Further, in step 7, the time is between 0.5h and 24h, preferably between 2h and 8h.

[0030] Further, in step 7, the thickness is between 25µm and 100µm.

[0031] Compared with the prior art, the present application has the following advantages.

[0032] 1. The present application prepares a porous layer of A / B different functional polymer, adds an additive containing different types of exchange groups to the polymer, gives the porous layer different functions, uses the advantages of cation exchange groups in electrical properties, and the characteristics of higher selectivity of anion exchange groups due to Dannon effect, and improves the performance of the composite membrane.

[0033] 2. The polymer porous layer is modified again by using different surface treatment methods, and finally the high-conductivity film-forming solution is hot-pressed with the porous membrane after surface treatment. The combination of the treated porous layer surface greatly improves the bonding force between the layers of the composite membrane, reduces the stress concentration between the matrix and the reinforcing phase, and avoids the delamination phenomenon between the layers caused by long-term erosion of the liquid during long-term operation of the liquid flow battery.

[0034] 3. For ion-conducting membranes, the transport of charge carriers mainly occurs in the hydrophilic channels formed after the hydrophilic swelling of the membrane. In fact, the hydrophilic channel is a microphase separation structure formed by the hydrophobic rigid main chain of the polymer and the hydrophilic group. In the present application, the support layer uses a porous layer with different pore sizes and pore structures, and additives are added to the porous support layer, so that the composite membrane forms more microphase separation structures, providing more hydrophilic channels for the transport of charge carriers in the membrane, and improving the conductivity of the composite membrane. DETAILED DESCRIPTION

[0035] The technical solutions of the present application will be further described in detail through the following examples.

[0036] A method for preparing a high-conductivity ion-conducting A / B composite membrane for a flow battery, comprising the following steps:

[0037] Step 1, preparing a high-molecular polymer dispersion solution A by dispersing a high-molecular polymer in a solvent, preparing an additive dispersion solution B by dispersing a functional additive containing an anion exchange group in a solvent, and finally preparing a high-molecular polymer solution C by uniformly mixing the high-molecular polymer solution A and the additive dispersion solution B.

[0038] Step 2, preparing an additive dispersion solution D by dispersing a functional additive containing a cation exchange group in a solvent, and preparing a high-molecular polymer solution E by uniformly mixing the high-molecular polymer solution A and the additive dispersion solution D.

[0039] Step 3, spinning the high-molecular polymer solution C prepared in step 1 by using an electrospinning method.

[0040] Step 4, spinning the high-molecular polymer solution E prepared in step 2 on the spinning layer of step 3 to prepare an A / B porous reinforced layer F with different pore structures.

[0041] Step 5, surface treating the A / B porous reinforced layer prepared in step 4 to prepare an A / B porous reinforced layer H.

[0042] Step 6, dissolving a high-conductivity film-forming resin in a solvent, the dissolving condition being to heat at 140-250°C in a reaction kettle for 4-24 hours, stirring and dissolving, naturally cooling after heating, and obtaining a film-forming resin solution J.

[0043] Step 7, immersing the A / B porous reinforced layer H prepared in step 5 in the film-forming resin solution J prepared in step 6 and performing ultrasonic treatment for 2-24 hours, heating at a certain temperature for a certain time after taking out, taking out after the solution is shaped, and performing hot-pressing to prepare a high-conductivity ion-conducting A / B composite membrane with a certain thickness.

[0044] Further, in step 1, the high-molecular polymer is one or more combinations of polyimide (PI), polypropylene (PEI), polyvinylidene fluoride (PVDF), and poly-m-phenylene isophthalamide (PMIA).

[0045] Further, in step 1, the solvent is one or more combinations of anhydrous ethanol, deionized water, methanol, isopropyl alcohol, dimethylbenzene, n-propyl alcohol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, and N-methyl pyrrolidone.

[0046] Further, in step 1, the functional additive containing anion exchange group is one or more combinations of quaternary ammonium chitosan, quaternary ammonium polyvinyl alcohol, quaternary ammonium vinylpyrrolidone polymer, quaternary ammonium polyether ether ketone, quaternary ammonium polyimide, quaternary ammonium polyether sulfone, etc.

[0047] Further, in step 1, the concentration of the high molecular polymer dispersion solution A is 1wt%-15wt%; the concentration of the additive dispersion solution B is 0.2wt%-5wt%; the functional additive containing anion exchange group in the high molecular polymer solution C: the mass ratio of high molecular polymer is 1:10-1:100.

[0048] Further, in step 2, the functional additive containing cation exchange group is one or more combinations of sulfonated graphene, sulfonated carbon black, sulfonated nanotube, sulfonated mesoporous carbon dioxide, sulfonated polyether ether ketone, sulfonated polyimide, sulfonated polyether sulfone, etc.

[0049] Further, in step 2, the concentration of the additive dispersion solution D is 0.2wt%-5wt%; the functional additive containing cation exchange group in the high molecular polymer solution E: the mass ratio of high molecular polymer is 1:10-1:100.

[0050] Further, in steps 3, 4, the spinning process parameters: voltage 10-20kV, solution flow rate 0.9-1.3mL / h, needle distance 10-15cm, solution concentration 2wt%-25wt%; the diameter of the fiber is between 100nm-900nm.

[0051] Further, in step 5, the surface treatment is one or more combinations of etching method, oxidation method, plasma treatment method, ultraviolet radiation method, laser irradiation method.

[0052] Further, in step 6, the high conductivity film-forming resin is perfluorosulfonic acid resin, sulfonated polyether sulfone, sulfonated polyether ether ketone, perfluorocarboxylic acid resin, sulfonated polyimide, sulfonated polysulfone, etc.

[0053] Further, in step 6, the solvent is one or more combinations of anhydrous ethanol, deionized water, isopropanol, n-propanol, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, N-Base pyrrolidone, etc.

[0054] Further, in step 6, the concentration of the film-forming resin solution J is 2wt%-25wt%.

[0055] Further, in step 7, the temperature is between 80℃-170℃, preferably between 100℃-120℃.

[0056] Further, in step 7, the time is between 0.5h-24h, preferably between 2h-8h.

[0057] Further, in step 7, the thickness is between 25 µm and 100 µm.

[0058] Example 1.

[0059] In this embodiment, the specific experimental steps are as follows:

[0060] Step 1, weigh 6 g of high molecular polymer polyvinylidene fluoride and disperse it in 50 ml of dimethylacetamide solvent to prepare a high molecular polymer dispersion liquid A, and disperse 0.5 g of quaternary ammonium polyether ether ketone in dimethylacetamide solvent to prepare an additive dispersion liquid B; finally, mix the high molecular polymer dispersion liquid A and the additive dispersion liquid B, stir for 24 h to uniformly mix to prepare a high molecular polymer solution C.

[0061] Step 2, disperse 0.5 g of sulfonated graphene into dimethylacetamide to prepare an additive dispersion liquid D, and uniformly mix the high molecular polymer solution A and the additive dispersion liquid D to prepare a high molecular polymer solution E.

[0062] Step 3, use the electrospinning method to change the diameter of the fiber (100 nm-900 nm) by adjusting the voltage to 14 kV, the solution flow rate to 1.0 mL / h, the needle distance to 14 cm, and the solution concentration to 12 wt% of the process parameters of the high molecular polymer solution C prepared in step 1 to prepare a porous layer.

[0063] Step 4, spin the high molecular polymer solution E prepared in step 2 on the spinning layer of step 3, with the spinning parameters being voltage 14 kV, solution flow rate 1.0 mL / h, needle distance 14 cm, and solution concentration 12 wt%; to prepare an A / B porous reinforcing layer F with different pore structures.

[0064] Step 5, surface treat the A / B porous reinforcing layer F prepared in step 4 (Fenton solution surface treatment, add Fenton reagent, ensure that the porous layer is completely immersed, in a 50°C environment, constant temperature for 3 h) to prepare an A / B porous layer H.

[0065] Step 6, dissolve 10 g of high-conductivity perfluorosulfonic acid resin film-forming resin in 100 ml of dimethylacetamide solvent, with the dissolution conditions being to heat in a 240°C reaction kettle for 6 hours, stir to dissolve, naturally cool after heating, and take out to obtain a film-forming resin solution J.

[0066] Step 7, immerse the A / B porous reinforcing layer H prepared in step 5 in the film-forming resin solution J prepared in step 6 and perform ultrasonic treatment for 24 hours, take it out and heat it at 110°C for 6 h, take it out after the solution is shaped, and then perform hot pressing to prepare a high-conductivity ion-conducting A / B composite membrane.

[0067] The relevant performance data of this example are as follows: the thickness of the ion-conducting A / B composite membrane obtained is 40 pm, and the composite membrane is uniformly compounded. The linear swelling rate of the composite membrane is measured to be 2%, and the conductivity is 0.046 s / cm.

[0068] Example 2.

[0069] The difference from Example 1 is that:

[0070] Step 1, weigh 6 g of high molecular polymer polyimide and disperse it in 50 ml of dimethyl sulfoxide solvent to prepare a high molecular polymer dispersion solution A, weigh 0.5 g of quaternary ammonium polyimide and disperse it in dimethyl sulfoxide solvent to prepare an additive dispersion solution B, and finally mix the high molecular polymer solution with the additive dispersion solution, stir for 24 h to uniformly mix to prepare a high molecular polymer solution C.

[0071] Step 2, prepare an additive dispersion solution D by dispersing 0.5 g of sulfonated polyimide in dimethyl sulfoxide, and uniformly mix the high molecular polymer solution A with the additive dispersion solution D to prepare a high molecular polymer solution E.

[0072] The remaining steps are the same as Example 1.

[0073] The relevant performance data of this example are as follows: the thickness of the ion-conducting A / B composite membrane obtained is 45 pm, and the composite membrane is uniformly compounded. The linear swelling rate of the composite membrane is measured to be 1.8%, and the conductivity is 0.05 s / cm.

[0074] Example 3.

[0075] The difference from Example 1 is that:

[0076] Step 6, dissolve 6 g of high-conductivity sulfonated polyether ether ketone resin in 50 ml of dimethylacetamide solvent, the dissolution condition is to keep the reaction kettle at 240°C for 6 hours, and stir to dissolve, then naturally cool after keeping warm, and take out to obtain a film-forming resin solution J.

[0077] The remaining steps are the same as Example 1.

[0078] The relevant performance data of this example are as follows: the thickness of the ion-conducting composite membrane obtained is 41 pm, and the composite membrane is uniformly compounded. The linear swelling rate of the composite membrane is measured to be 1.9%, and the conductivity is 0.048 s / cm.

[0079] Example 4.

[0080] The difference from Example 1 is that:

[0081] Step 5, modify the A / B porous reinforcing layer F prepared in Step 4 by alkali chemical treatment method, and then perform plasma surface etching treatment to prepare a porous reinforcing layer H with high surface roughness.

[0082] The remaining steps are the same as in Example 1.

[0083] The relevant performance data of this example are as follows: the thickness of the obtained ion-conducting composite membrane is 41 pm, and the composite membrane is uniformly compounded. The linear swelling rate of the composite membrane is measured to be 1.8%, and the conductivity is 0.049 s / cm.

[0084] Comparative Example 1.

[0085] The difference from Example 1 is that:

[0086] Step 5, no surface treatment modification is made to the A / B porous reinforcing layer F prepared in Step 4 to prepare a porous reinforcing layer H.

[0087] The remaining steps are the same as in Example 1.

[0088] The relevant performance data of this example are as follows: the thickness of the obtained ion-conducting composite membrane is 40 pm, and the composite membrane is uniformly compounded. The linear swelling rate of the composite membrane is measured to be 2%, and the conductivity is 0.04 s / cm.

[0089] The experimental results show that: the electrospinning method is used to spin the polymer solution to prepare a porous reinforcing layer with different pore structures, the surface of the porous reinforcing layer is treated, and finally the high-conductivity film-forming resin solution is compounded with the treated porous supporting layer to prepare a high-conductivity ion-conducting composite membrane. The composite membrane prepared by the present application has low swelling, good bonding force between layers of the composite membrane, high conductivity, and is suitable for the field of flow batteries.

Claims

1. A method for preparing a high conductive ion conducting A / B composite membrane for flow batteries, characterized by, The method comprises the following steps: Step 1: preparing a high-molecular polymer solution A by dispersing a high-molecular polymer in a solvent, preparing an additive dispersion B by dispersing a functional additive containing an anion exchange group in a solvent, and finally uniformly mixing the high-molecular polymer solution A and the additive dispersion B to prepare a high-molecular polymer solution C; Step 2: preparing an additive dispersion D by dispersing a functional additive containing a cation exchange group in a solvent, and uniformly mixing the high-molecular polymer solution A and the additive dispersion D to prepare a high-molecular polymer solution E; Step 3: spinning the high-molecular polymer solution C prepared in step 1 by using an electrostatic spinning method; Step 4: spinning the high-molecular polymer solution E prepared in step 2 on the spinning layer of step 3 to prepare an A / B porous reinforcing layer F with different pore structures; Step 5: surface treating the A / B porous reinforcing layer prepared in step 4 to prepare an A / B porous reinforcing layer H; Step 6: dissolving a high-conductivity film-forming resin in a solvent, the dissolving condition being that the solution is kept in a 140-250 DEG C reaction kettle for 4-24 hours, stirring is performed for dissolving, and the solution is naturally cooled after keeping warm, thereby obtaining a film-forming resin solution J; Step 7: immersing the A / B porous reinforcing layer H prepared in step 5 into the film-forming resin solution J prepared in step 6 and performing ultrasonic treatment for 2-24 hours, keeping warm at a certain temperature for a certain time after taking out, taking out after the solution is shaped, and performing hot-pressing compounding to prepare a high-conductivity ion-conducting A / B composite film with a certain thickness; In step 1, the high-molecular polymer is one or a combination of polyimide, polypropylene, polyvinylidene fluoride, and poly-m-phenylene isophthalamide; the functional additive containing an anion exchange group is one or a combination of quaternary ammonium chitosan, quaternary ammonium polyvinyl alcohol, quaternary ammonium ethylene pyrrolidone polymer, quaternary ammonium polyether ether ketone, quaternary ammonium polyimide, and quaternary ammonium polyether sulfone; In step 2, the functional additive containing a cation exchange group is one or a combination of sulfonated graphene, sulfonated carbon black, sulfonated nanometer carbon tube, sulfonated polyether ether ketone, sulfonated polyimide, and sulfonated polyether sulfone; In step 6, the high-conductivity film-forming resin is one of perfluorosulfonic acid resin, sulfonated polyether sulfone, sulfonated polyether ether ketone, perfluorocarboxylic acid resin, sulfonated polyimide, and sulfonated polysulfone.

2. The method for preparing a high conductive ion conducting A / B composite membrane for liquid flow battery according to claim 1, characterized in that, In step 1, the solvent is one or a combination of anhydrous ethanol, deionized water, methanol, isopropanol, dimethylbenzene, n-propanol, N,N-dimethylformamide, and N,N-dimethylacetamide.

3. The method of claim 1, wherein the method is characterized by: In step 1, the concentration of the high-molecular polymer solution A is 1wt%-15wt%; the concentration of the additive dispersion B is 0.2wt%-5wt%; the mass ratio of the high-molecular polymer to the functional additive containing an anion exchange group in the high-molecular polymer solution C is 1:10-1:

100.

4. The method of claim 1, wherein the method is characterized by: In step 2, the concentration of the additive dispersion D is 0.2wt%-5wt%; the mass ratio of the high-molecular polymer to the functional additive containing a cation exchange group in the high-molecular polymer solution E is 1:10-1:

100.

5. The method of claim 1, wherein the high conductive ion conducting A / B composite membrane for liquid flow battery is prepared by the steps of: In steps 3, 4, the spinning process parameters are: voltage 10-20 kV, solution flow rate 0.9-1.3 mL / h, needle distance 10-15 cm, and solution concentration 2 wt%-25 wt%; the fiber diameter is between 100 nm and 900 nm.

6. The method of claim 1, wherein the high conductive ion conducting A / B composite membrane for liquid flow battery is prepared by the steps of: In step 6, the concentration of the film-forming resin solution J is 2 wt%-25 wt%.

7. The method of claim 1, wherein the method is characterized by: In step 7, the temperature is between 80°C and 170°C; the time is between 0.5 h and 24 h; and the thickness is between 25 µm and 100 µm.