Preparation method and application of high-strength flexible ion sieve separation membrane

Abstract

This invention discloses a method for preparing a high-strength flexible ion-sieving membrane and its application, relating to the field of chemical power source technology. The method involves dissolving a metal-organic framework (MOF) material in an organic solvent, adding a compound containing isocyanate groups, and then ultrasonically treating the mixture. The resulting membrane is then uniformly sprayed onto a base membrane surface using ultrasonic spraying technology, effectively bonding with the base membrane to prepare a high-strength flexible ion-sieving membrane. The MOF layer of this invention possesses ion-binding and conductivity capabilities, constructing a highly efficient ion transport channel. This ion-sieving membrane not only exhibits flexibility and strength but also effectively solves the internal short-circuit problem caused by lithium dendrites piercing the separator, significantly improving battery safety.

Description

Technical Field

[0001] This invention relates to the field of chemical power source technology, specifically to a method for preparing and applying a high-strength flexible ion sieving membrane. Background Technology

[0002] The separator is a core component of a battery, playing a crucial role in physically isolating the positive and negative electrodes, effectively preventing internal short circuits, and providing a pathway for unimpeded ion transport. Therefore, the performance of the separator directly affects the overall efficiency and safety of the battery. Currently, microporous polyolefin membranes, especially polyethylene (PE) and polypropylene (PP) or their composites, have become the preferred materials in the field of battery separators due to their excellent electrochemical stability, good mechanical strength, and uniform pore size distribution.

[0003] Despite this, traditional polyolefin separators still face numerous challenges. In particular, insufficient wettability of the liquid electrolyte and unstable mechanical strength can lead to lithium dendrites piercing the separator, causing internal short circuits or even spontaneous combustion, posing a serious threat to battery safety. Solid-state inorganic / polymer electrolytes are considered an ideal solution for improving battery safety and have broad development prospects. However, they also have some problems that urgently need to be solved, such as low ionic conductivity, high manufacturing cost, poor interface stability, and potential expansion during charge and discharge. These problems severely restrict the practical application of solid-state electrolytes.

[0004] Therefore, developing a high-strength, flexible ion-sieving membrane that effectively prevents lithium dendrite puncture and avoids the risk of battery thermal runaway, while also possessing good ionic conductivity, excellent interfacial stability, and low manufacturing cost, is crucial. By introducing this multifunctional membrane material, we can ensure the efficient and safe operation of batteries, laying a solid foundation for further development of battery technology. Summary of the Invention

[0005] The purpose of this invention is to provide a method for preparing and applying a high-strength flexible ion sieving membrane, in order to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a method for preparing a high-strength flexible ion sieving membrane, the specific steps of which are as follows:

[0007] S1, take metal-organic framework (MOF) material, dissolve it in an organic solvent until completely dissolved, add a compound containing isocyanate group to the solution and stir to obtain an emulsion, and sonicate the emulsion to obtain a uniformly dispersed emulsion.

[0008] S2, the uniformly dispersed emulsion described in step S1 is uniformly sprayed onto the surface of the base film using ultrasonic spraying technology, and then dried. The MOF layer and the base film layer are then tightly pressed together using a hot press to obtain a high-strength flexible ion sieving membrane.

[0009] Furthermore, the MOF material in step S1 contains an amino or hydroxyl structure;

[0010] The organic solvent is methanol, dichloromethane, tetrachloroethane, ethanol, chloroform, N-methylpyrrolidone, N,N-dimethylformamide, diethyl ether, or ethylene glycol dimethyl ether; the isocyanate-containing compound is one of monoisocyanate, diisocyanate, polyisocyanate, aromatic isocyanate, aliphatic isocyanate, and alicyclic isocyanate.

[0011] The mass ratio of MOF material to isocyanate compound is (4~100):1;

[0012] The stirring time is 20-600 minutes;

[0013] The revolutions per minute (rpm) are 200-3000.

[0014] The ultrasonic treatment time is 0.5-30 hours.

[0015] Further, the base film material mentioned in step S2 is one of PTFE, PMMA, PVDF, and PI;

[0016] The porosity of the base membrane is 80-98%;

[0017] The thickness of the base film is 1-16 μm;

[0018] The ultrasonic spraying nozzle has a power of 0.1-10W, a liquid output of 0.1-10mL / min, and can be sprayed 3-2000 times.

[0019] The drying temperature is 40-200℃, and the drying time is 0.1-60h;

[0020] The temperature of the hot press is 30-200℃, and the pressure of the hot press is 0.01-5 MPa;

[0021] MOF accounts for more than 80% of the total content of the membrane.

[0022] The present invention also provides a high-strength flexible ion sieving membrane, characterized in that it is prepared by any one of the preparation methods described above.

[0023] Furthermore, it is applied in lithium metal batteries, lithium-ion batteries, sodium-ion batteries, sodium metal batteries, potassium-ion batteries, and potassium metal batteries.

[0024] The beneficial effects of this invention are as follows: By effectively preventing lithium dendrite puncture, the risk of internal short circuits in the battery is reduced, thereby avoiding potential safety accidents such as spontaneous combustion and improving battery safety; the MOF contains amino and hydroxyl groups, which, after isocyanate treatment, improve the processability of the MOF and its interfacial compatibility with the base film; the ion binding and conduction capabilities of the MOF material can construct efficient ion transport channels, thereby giving the battery superior ionic conductivity, enabling the battery to exhibit higher efficiency during charging and discharging, thus comprehensively improving the overall working performance of the battery and bringing users a smoother and more stable power supply experience;

[0025] The manufacturing cost of high-strength flexible ion screening membranes is relatively low. This cost advantage helps reduce the overall manufacturing cost of batteries, making high-performance batteries more economical, promoting the popularization of high-performance batteries in the market, and strongly driving the rapid development of clean energy industries such as electric vehicles, thus contributing to a green and sustainable energy future. Attached Figure Description

[0026] Figure 1 This is a schematic diagram of the electrochemical performance of a Li-SPAN battery matched with a high-strength flexible ion sieving membrane. Detailed Implementation

[0027] In the following description, numerous specific details are set forth in order to provide a more thorough understanding of the invention. However, it will be apparent to those skilled in the art that the invention can be practiced without one or more of these details. In other instances, certain technical features well-known in the art have not been described in order to avoid obscuring the invention. Example

[0028] Reference Figure 1 45g of ZIF-8 containing an amino structure was completely dissolved in methanol, and then 1g of hexamethylene diisocyanate trimer was added to the solution. The mixture was stirred in air for 4 hours at a constant speed of 500 rpm to ensure complete reaction. The solution was then sonicated for 2 hours to ensure complete bonding between the MOF and the isocyanate. Using ultrasonic spraying technology, the emulsion was uniformly sprayed onto an 8μm PTFE substrate membrane. During spraying, the nozzle power was adjusted to 2W, the flow rate to 2mL / min, and 30 passes were performed to ensure the uniformity of the MOF layer. After spraying, the membrane was dried in an 80℃ oven for 2 hours to remove the solvent. The MOF layer and the substrate membrane were then tightly pressed together using a hot press at 80℃ and 1MPa, successfully preparing a high-strength flexible ion-sieving membrane with an ionic conductivity of 6.3 × 10⁻⁶. -3 S∙cm -1The assembled lithium-sulfur battery exhibits a reversible discharge specific capacity of 643 mAh / g at a current density of 0.2C. After 200 charge-discharge cycles, the capacity retention rate is 88%, and the coulombic efficiency remains at 100%. Example

[0029] 55g of MOF-5 containing an amino group was completely dissolved in ethanol, and 1g of IPDI (isophorone diisocyanate) was added as the isocyanate-containing compound. The mixture was stirred in air for 30 minutes at 1000 rpm, followed by 1 hour of ultrasonic treatment. PTFE was selected as the base membrane material, with a thickness of 4μm, providing better chemical resistance and high-temperature resistance. Using ultrasonic spraying technology, the nozzle power was set to 5W, the liquid flow rate to 5mL / min, and 20 coats were applied. The sprayed membrane was dried in an oven at 120℃ for 4 hours. Finally, it was pressed using a hot press at 120℃ and 2MPa, resulting in a high-strength flexible ion-sieving membrane with good ion selectivity and mechanical strength, and an ionic conductivity of 8.1×10⁻⁶. -3 S∙cm -1 The assembled lithium-sulfur battery exhibits a reversible discharge specific capacity of 688 mAh / g at a current density of 0.2C. After 200 charge-discharge cycles, the capacity retention rate is 90%, and the coulombic efficiency remains at 100%. Example

[0030] 60g of MIL-101(Cr) containing an amino group was completely dissolved in chloroform, and 1g of HDI (hexamethylene diisocyanate) was added as the isocyanate-containing compound. The stirring time was 60 minutes at 2000 rpm, and the ultrasonic treatment time was 30 minutes. A 6μm PVDF membrane was selected as the base film. During spraying, the nozzle power was 1W, the liquid flow rate was 1mL / min, and 80 coats were applied. The drying temperature was 100℃ for 6 hours. Finally, the membrane was pressed using a hot press at 150℃ and 0.5MPa. The resulting ion-sieving membrane exhibited excellent performance, with an ionic conductivity of 3.4 × 10⁻⁶. -3 S∙cm -1 The assembled lithium-sulfur battery exhibited a reversible discharge specific capacity of 656 mAh / g at a current density of 0.2C. After 200 charge-discharge cycles, the capacity retention rate was 83%, and the coulombic efficiency remained at 100%.

[0031] As described above, although the invention has been shown and described with reference to specific preferred embodiments, it should not be construed as limiting the invention itself. Various changes in form and detail may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A method for preparing a high-strength flexible ion sieving membrane, characterized in that, The specific steps are as follows: S1, take metal-organic framework (MOF) material, dissolve it in an organic solvent until completely dissolved, add a compound containing isocyanate group to the solution and stir to obtain an emulsion, and sonicate the emulsion to obtain a uniformly dispersed emulsion; S2, the uniformly dispersed emulsion described in step S1 is uniformly sprayed onto the surface of the base membrane using ultrasonic spraying technology, and then dried. The MOF layer and the base membrane layer are then tightly pressed together using a hot press to obtain a high-strength flexible ion sieving membrane. The MOF material in step S1 contains an amino or hydroxyl structure. The mass ratio of MOF material to isocyanate compound is (4~100):

1. The MOF material accounts for more than 80% of the total content of the membrane.

2. The method for preparing the high-strength flexible ion sieving membrane according to claim 1, characterized in that, The organic solvent is methanol, dichloromethane, tetrachloroethane, ethanol, chloroform, N-methylpyrrolidone, N,N-dimethylformamide, diethyl ether, or ethylene glycol dimethyl ether; the isocyanate-containing compound is one of monoisocyanate, diisocyanate, polyisocyanate, aromatic isocyanate, aliphatic isocyanate, and alicyclic isocyanate. The stirring time is 20-600 minutes; The revolutions per minute (rpm) are 200-3000. The ultrasonic treatment time is 0.5-30 hours.

3. The method for preparing the high-strength flexible ion sieving membrane according to claim 1, characterized in that, The base film material mentioned in step S2 is one of PTFE, PMMA, PVDF, and PI; The porosity of the base membrane is 80-98%; The thickness of the base film is 1-16 μm; The ultrasonic spraying nozzle has a power of 0.1-10W, a liquid output of 0.1-10mL / min, and can be sprayed 3-2000 times. The drying temperature is 40-200℃, and the drying time is 0.1-60h; The temperature of the hot press is 30-200℃, and the pressure of the hot press is 0.01-5 MPa.

4. A high-strength flexible ion sieving membrane, characterized in that, It is prepared by the preparation method described in any one of claims 1 to 3.

5. The high-strength flexible ion sieving membrane according to claim 4, characterized in that, It is used in lithium metal batteries, lithium-ion batteries, sodium-ion batteries, sodium metal batteries, potassium-ion batteries, or potassium metal batteries.

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