Composite solid electrolyte membrane with three-dimensional intertransmission network structure and preparation method of composite solid electrolyte membrane

Abstract

The invention belongs to the technical field of lithium ion batteries, and particularly relates to a preparation method of a composite solid electrolyte membrane with a three-dimensional mutual transmission network structure. The preparation method comprises the following steps: firstly, adding PVDF-HFP and PVDF into DMF (Dimethyl Formamide) for fully dissolving, then adding lithium salt for fully dissolving, and introducing an initiator to form a solution A; adding solid electrolyte powder and triazine monomers into DMF (Dimethyl Formamide), and fully stirring to form a solution B; uniformly stirring the solution A and the solution B again to form a glue solution C; and dripping the glue solution C on a glass plate for blade coating, placing the glass plate in a drying box for thermal insulation polymerization, and then vacuumizing and drying to obtain the composite solid electrolyte diaphragm. The triazine monomers are added to form a three-dimensional mutual transmission network structure, the flame retardance and cohesiveness of the three-dimensional mutual transmission network structure are improved, finally, the composite solid electrolyte diaphragm with great commercial value is obtained, and the diaphragm has good effects in the aspects of improving the ionic conductivity, the flame retardance, the viscosity after hot pressing and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium-ion batteries, and particularly relates to a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure and a preparation method thereof. Background Art

[0002] With the accelerating progress of the global carbon neutrality process, solid-state batteries, with their non-flammable characteristics and potential for adapting to high-activity electrode materials, have become a key path to break through the bottlenecks of existing lithium battery technologies. However, problems such as large solid-solid interface contact impedance between the solid electrolyte and the electrode and high lithium-ion migration barriers severely restrict the release of their electrochemical performance. Summary of the Invention

[0003] To solve the problem of low ionic conductivity caused by the ion concentration difference at the contact interface between the solid electrolyte and the colloid in the above-mentioned prior art, the present invention provides a preparation method of a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure, aiming to prepare an organic-inorganic composite solid electrolyte membrane with high viscosity, high flame retardancy, and high ionic conductivity.

[0004] To achieve the above object, the technical solution adopted by the present invention is as follows: A preparation method of a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure, the specific steps are as follows: Step 1, first weigh 1.5 parts of PVDF-HFP and 1.5 parts of PVDF, add them to 10 parts of DMF, stir overnight to fully dissolve them. After observing no large particles, add 0.3 parts of lithium salt, heat and stir until dissolved, and finally add 0.1 part of initiator to form solution A.

[0005] Step 2, weigh 2 parts of solid electrolyte powder and 1 part of triazine monomer, add them to 10 parts of DMF, stir overnight, so that the triazine monomer is adsorbed in the pores of the solid electrolyte powder and dispersed evenly to form solution B.

[0006] Step 3, add the above two solutions, namely solution A and solution B, to a sealed glass bottle, stir again for 12 h to make the mixed solution dispersed evenly to form colloidal solution C.

[0007] Step 4, drop the mixed colloidal solution C on a glass plate, then use a scraper to scrape it, place it in a drying oven, keep it warm at a temperature of 80 °C for 2 h, ensure that the triazine monomer is fully polymerized, and then vacuum dry for 12 h to obtain a composite solid electrolyte diaphragm with a thickness of 30-40 μm.

[0008] Further, the triazine monomer is one of 2,4,6-tris(2-propynyloxy)-1,3,5-triazine, 2,4,6-tris(allyloxy)-1,3,5-triazine, 1,3,5-triacryloylhexahydro-1,3,5-triazine, and tris-2-acrylate [2,4,6-trioxo-1,3,5-triazine-1,3,5(2H,4H,6H)-subunit] tris-2,1-ethylene ester.

[0009] Preferably, the initiator is AIBN or AVBN.

[0010] Preferably, the solid electrolyte powder is LLZO or LAGP.

[0011] Further, the lithium salt is one of LiTFSI, LiFSI, LiPF6, LiClO4, and LiBF4.

[0012] The composite solid electrolyte separator prepared by the above method is used to assemble a lithium-ion battery.

[0013] The composite solid electrolyte separator prepared by the above method has a three-dimensional interpenetrating network structure under electron microscopy.

[0014] The beneficial effects of the present invention are as follows: 1. In the present invention, through liquid-phase mixing, the triazine compound is adsorbed on the surface of the solid electrolyte particles through an organic solvent as a medium, reducing the lithium ion concentration gradient difference at the solid-solid contact interface between the surface of the solid electrolyte particles and the PVDF-HFP colloid, which is beneficial to the transfer of lithium ions from the solid electrolyte particles to the PVDF-HFP colloid. At the same time, the multi-hydrogen bond structure of the triazine compound is also beneficial to the transfer of lithium ions. Finally, the added triazine compound forms a three-dimensional interpenetrating network structure with the chain-like PVDF-HFP. Under the electron microscope, the three-dimensional interconnected structure is tight, which can increase its flame retardancy and adhesiveness. Finally, a composite solid electrolyte separator with great commercial value is obtained. The ionic conductivity of this separator is as high as 5.36*10-4 S / cm at room temperature. By assembling an NCM‖CPE‖Li battery with NCM and a lithium metal negative electrode, a reversible capacity of 201.5 mAh / g can be obtained under the condition of 0.1C.

[0015] 2. In the present invention, through the synergistic design of the organic polymer matrix and the inorganic filler in the composite solid electrolyte, a "rigid-flexible combination" structure with both flexible interface fitting ability and high ionic conduction characteristics is constructed. The composite solid electrolyte membrane cured by adding different triazine monomers in the present invention has good effects in terms of flame retardancy, ionic conductivity, and improved viscosity after hot pressing.

[0016] 3. The solid electrolyte powder of the present invention, LLZO or LAGP, as an inorganic active filler can reduce the crystallinity of the PVDF matrix. It can be observed by SEM that there are no large colloidal particles on the surface of the separator. At the same time, the solid electrolyte particles can conduct lithium, and cooperate with the lithium salt to increase the ionic conductivity of the separator.

[0017] 4. The organic-inorganic composite solid electrolyte membrane with high viscosity, high flame retardancy and high ionic conductivity prepared by the present invention is applied in lithium-ion batteries, which can increase the mechanical strength, use safety and thermal safety performance of lithium-ion batteries, and enhance the electrical performance of lithium-ion batteries. Description of the Drawings

[0018] Figure 1 It is the scanning electron microscope picture in Example 1, also known as the SEM image.

[0019] Figure 2 It is the scanning electron microscope picture in Comparative Example 1, also known as the SEM image.

[0020] Figure 3 It is the first cycle voltage-capacity curve of Example 1 and Comparative Example 1 at 0.1C.

[0021] Figure 4 It is the first cycle voltage-capacity curve of Examples 2-5 at 0.1C.

[0022] Figure 5 It is the first cycle voltage-capacity curve of Examples 6-10 at 0.1C.

[0023] Figure 6 It is the EIS test chart in Example 1.

[0024] Figure 7 It is the EIS test chart in Comparative Example 1.

[0025] Figure 8 It is the optical picture before and after ignition of Example 1, which is the result display of the flame retardancy test.

[0026] Figure 9 It is the optical picture before and after ignition of Comparative Example 1, which is the result display of the flame retardancy test.

[0027] Figure 10 It is the optical picture after hot pressing of Example 1, which is the result display of the viscosity test.

[0028] Figure 11 It is the optical picture after hot pressing of Comparative Example 1, which is the result display of the viscosity test. Detailed Embodiments

[0029] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0030] The present invention provides a method for preparing a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure, and the specific steps are as follows: Step 1: First, weigh PVDF-HFP and PVDF, add them to DMF, and stir overnight to fully dissolve them. After observing that there are no large particles, add a lithium salt and heat and stir until dissolved. Finally, add AIBN or AVBN as an initiator to form Solution A. Preferably, the materials used in Step 1 are weighed by mass, that is, 1.5 parts of PVDF-HFP, 1.5 parts of PVDF, 10 parts of DMF, 0.3 part of lithium salt, and 0.1 part of initiator.

[0031] Step 2: Take solid electrolyte powder and triazine monomer, add them to DMF, and stir overnight to make the triazine monomer adsorb in the pores of the solid electrolyte powder and disperse evenly to form Solution B. Preferably, the materials used in Step 2 are weighed by mass, that is, 2 parts of solid electrolyte powder and 1 part of triazine monomer are added to 10 parts of DMF.

[0032] Step 3: Add the above two solutions, namely Solution A and Solution B, to a sealed glass bottle, and stir for another 12 h to make the mixed solution disperse evenly to form Glue C.

[0033] Step 4: Drop the mixed Glue C on a glass plate, then use a scraper to scrape it, place it in a drying oven, keep it warm at a temperature of 80 °C for 2 h to ensure that the triazine monomer is fully polymerized, and then vacuum dry it for 12 h to obtain a composite solid electrolyte separator with a thickness of 30-40 μm.

[0034] After mixing Solution B and Solution A in the above preparation method, stirring overnight to obtain Glue C is carried out in a glove box; the composite solid electrolyte separator prepared by the above method can be assembled into a button cell in a glove box with an argon atmosphere and the contents of water and oxygen both lower than 0.01 ppm; the performance of the composite solid electrolyte separator is tested by scanning electron microscopy, charge-discharge capacity test, EIS test, flame retardancy test, and viscosity test.

[0035] Example 1 A method for preparing a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure, and the specific steps are as follows: S1. First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF, and stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiTFSI, heat and stir until dissolved, and finally add 0.1 g of AIBN as an initiator to form Solution A.

[0036] S2. Weigh 2 g of LLZO solid electrolyte powder and 1 g of 2,4,6-tris(2-propynyloxy)-1,3,5-triazine, and add them to 10 g of DMF, stir overnight to make them fully dispersed and uniform, and then form Solution B.

[0037] S3. Add the above two solutions, namely Solution A and Solution B, to a sealed glass bottle, stir for another 12 h to make the mixed solution dispersed and uniform to form Colloid C.

[0038] S4. Drop the mixed Colloid C on a glass plate, then use a scraper to scrape and coat it, place it in a drying oven, keep it at 80 °C for 2 h, and then vacuum dry for 12 h to obtain a composite solid electrolyte membrane with a thickness of 30 - 40 μm.

[0039] In the above preparation method, after mixing Solution B and Solution A, stirring overnight to obtain Colloid C is carried out in a glove box; in order to detect the performance of the composite solid electrolyte membrane prepared by the above method, a button cell is assembled in a glove box under an argon atmosphere with the water and oxygen contents both lower than 0.01 ppm, the electrolyte is 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte membrane therein is tested. The test results are as follows: The SEM image is as Figure 1 shown. It can be observed that the solid electrolyte particles on the diaphragm surface are dispersed evenly and there is no obvious lithium salt precipitation on the surface, and its dense morphology provides continuous Li+ transport.

[0040] The charge-discharge capacity curve is as shown. Under the condition of 0.1C, a reversible capacity of 201.5 mAh / g can be achieved, and there is no large voltage polarization. This is because the addition of triazine monomers increases the adhesion force after hot pressing and increases the lithium ion transport channels.

[0041] The EIS test is as Figure 3 shown. The ionic conductivity is in the order of 5*10 -4 S / cm, and the lithium ions can be transported stably. The addition of the new monomer increases the flexibility of the diaphragm to a certain extent, and further increases the interface contact through hot pressing.

[0042] The flame retardancy test is as Figure 6 shown. After being ignited by a flame, it automatically goes out and there is no combustion phenomenon, showing a flame retardant effect.

[0043] Adhesion test Figure 8 As shown, there are stainless steel gaskets on both sides. After hot pressing at high temperature, the diaphragm shows a certain adhesiveness and can firmly fix both sides.

[0044] Example 2 A preparation method of a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure is as follows: S1. First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF, and stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiTFSI, heat and stir until dissolved, and finally add 0.1 g of AIBN as an initiator to form solution A.

[0045] S2. Weigh 2 g of LLZO solid electrolyte powder and 1 g of triallyl cyanurate, and add them to 10 g of DMF, stir overnight to make them fully dispersed and uniform to form solution B.

[0046] S3. Add the above two solutions, namely solution A and solution B, to a sealed glass bottle, and stir again for 12 h to make the mixed solution dispersed and uniform to form colloidal solution C.

[0047] S4. Drop the mixed colloidal solution C on a glass plate, then use a scraper to scrape it, place it in an oven, keep it at 80 °C for 2 h, and then vacuum dry for 12 h to obtain a composite solid electrolyte diaphragm with a thickness of 30 - 40 μm.

[0048] In the above preparation method, after mixing solution B and solution A, stirring overnight to obtain colloidal solution C is carried out in a glove box; in order to detect the performance of the composite solid electrolyte diaphragm prepared by the above method, a button battery is assembled in a glove box under an argon atmosphere with the water and oxygen contents both lower than 0.01 ppm, and the electrolyte is 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte diaphragm is tested. The test results are as follows: The charge-discharge capacity curve is as Figure 10 shown, showing a reversible capacity of 171.8 mAh / g.

[0049] Example 3 A preparation method of a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure is as follows: S1. First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF, and stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiTFSI, heat and stir until dissolved, and finally add 0.1 g of AVBN as an initiator to form solution A.

[0050] S2, Weigh 2 g of LLZO solid electrolyte powder and 1 g of 1,3,5-triacryloyl hexahydro-1,3,5-triazine, and add them to 10 g of DMF and stir overnight. After fully dispersing and homogenizing them, a solution B is formed.

[0051] S3, Add the above two solutions, namely solution A and solution B, to a sealed glass bottle, and stir for another 12 h to make the mixed solution disperse evenly to form a colloidal solution C.

[0052] S4, Drop the mixed colloidal solution C on a glass plate, then use a scraper to scrape it, place it in a drying oven, keep it at a temperature of 80 °C for 2 h, and then vacuum dry it for 12 h to obtain a composite solid electrolyte membrane with a thickness of 30 - 40 μm.

[0053] In the above preparation method, after mixing solution B and solution A, stirring overnight to obtain colloidal solution C is carried out in a glove box; in order to detect the performance of the composite solid electrolyte membrane prepared by the above method, a button cell is assembled in a glove box under an argon atmosphere with the water and oxygen contents both lower than 0.01 ppm, the electrolyte is 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte membrane therein is tested. The test results are as follows: The charge-discharge capacity curve is as Figure 4 shown, and a reversible capacity of 197.5 mAh / g appears.

[0054] Example 4 A preparation method of a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure is as follows: S1, First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF and stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiTFSI and heat and stir until dissolved, and finally add 0.1 g of AVBN as an initiator to form solution A.

[0055] S2, Weigh 2 g of LLZO solid electrolyte powder and 1 g of tris(2-acryloyloxyethyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, and add them to 10 g of DMF and stir overnight. After fully dispersing and homogenizing them, a solution B is formed.

[0056] S3, Add the above two solutions, namely solution A and solution B, to a sealed glass bottle, and stir for another 12 h to make the mixed solution disperse evenly to form a colloidal solution C.

[0057] S4. Drop the mixed glue solution C onto a glass plate, then use a scraper to scrape and coat it, place it in a drying oven, keep it at 80 °C for 2 h, and then vacuum dry it for 12 h to obtain a composite solid electrolyte membrane with a thickness of 30 - 40 μm.

[0058] In the above preparation method, after mixing solution B and solution A, stirring overnight to obtain glue solution C is carried out in a glove box; in order to detect the performance of the composite solid electrolyte membrane prepared by the above method, an in - button battery is assembled in a glove box under an argon atmosphere with water and oxygen contents both lower than 0.01 ppm, the electrolyte is 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte membrane therein is tested. The test results are as follows: The charge - discharge capacity curve is as Figure 4 shown, showing a reversible capacity of 198.8 mAh / g.

[0059] Example 5 A preparation method of a composite solid electrolyte membrane with a three - dimensional interpenetrating network structure is as follows: S1. First, weigh 1.5 g of PVDF - HFP and 1.5 g of PVDF, add them to 10 g of DMF and stir overnight to dissolve them fully. After observing no large particles after full dissolution, then add 0.3 g of LiTFSI, heat and stir to dissolve it, and finally add 0.1 g of AIBN as an initiator to form solution A.

[0060] S2. Weigh 2 g of LLZO solid electrolyte powder and 1 g of 2,4,6 - tris(allyloxy) - 1,3,5 - triazine, and add them to 10 g of DMF and stir overnight to make them fully dispersed and uniform to form solution B.

[0061] S3. Add the above two solutions, namely solution A and solution B, into a sealed glass bottle, and stir for another 12 h to make the mixed solution dispersed and uniform to form glue solution C.

[0062] S4. Drop the mixed glue solution C onto a glass plate, then use a scraper to scrape and coat it, place it in a drying oven, keep it at 80 °C for 2 h, and then vacuum dry it for 12 h to obtain a composite solid electrolyte membrane with a thickness of 30 - 40 μm.

[0063] In the above preparation method, after mixing solution B and solution A, stirring overnight to obtain glue solution C is carried out in a glove box; in order to detect the performance of the composite solid electrolyte membrane prepared by the above method, an in - button battery is assembled in a glove box under an argon atmosphere with water and oxygen contents both lower than 0.01 ppm, the electrolyte is 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte membrane therein is tested. The test results are as follows: The charge - discharge capacity curve is as Figure 4As shown, a reversible capacity of 199.2 mAh / g appears.

[0064] Example 6 A method for preparing a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure is as follows: S1. First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF, and stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiFSI, heat and stir until dissolved, and finally add 0.1 g of AIBN as an initiator to form Solution A.

[0065] S2. Weigh 2 g of LLZO solid electrolyte powder and 1 g of 2,4,6-tris(2-propynyloxy)-1,3,5-triazine, and add them to 10 g of DMF, stir overnight, and after fully dispersing and homogenizing, form Solution B.

[0066] S3. Add the above two solutions, namely Solution A and Solution B, to a sealed glass bottle, stir for another 12 h to make the mixed solution disperse evenly to form Colloid C.

[0067] S4. Drop the mixed Colloid C on a glass plate, then use a scraper to scrape and coat it, place it in an oven, keep it at 80 °C for 2 h, and then vacuum dry for 12 h to obtain a composite solid electrolyte separator with a thickness of 30 - 40 μm.

[0068] In the above preparation method, after mixing Solution B and Solution A, stirring overnight to obtain Colloid C is carried out in a glove box; in order to detect the performance of the composite solid electrolyte separator prepared by the above method, a button cell is assembled in a glove box under an argon atmosphere with the water and oxygen content both lower than 0.01 ppm, the electrolyte is 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte separator is tested. The test results are as follows: The charge-discharge capacity curve is as Figure 4 As shown, a reversible capacity of 198.5 mAh / g appears.

[0069] Example 7 A method for preparing a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure is as follows: S1. First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF, and stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiPF6, heat and stir until dissolved, and finally add 0.1 g of AVBN as an initiator to form Solution A.

[0070] S2, Weigh 2 g of LLZO solid electrolyte powder and 1 g of 2,4,6-tris(2-propynyloxy)-1,3,5-triazine, and add them to 10 g of DMF. Stir overnight to form a homogeneous dispersion, and then a solution B is obtained after sufficient dispersion and uniformity.

[0071] S3, Add the above two solutions, namely solution A and solution B, to a sealed glass bottle, and stir for another 12 h to make the mixed solution disperse evenly to form a colloidal solution C.

[0072] S4, Drop the mixed colloidal solution C onto a glass plate, then use a scraper to scrape and coat it. Place it in an oven, keep it at 80 °C for 2 h, and then vacuum dry for 12 h to obtain a composite solid electrolyte membrane with a thickness of 30 - 40 μm.

[0073] In the above preparation method, after mixing solution B and solution A, stirring overnight to obtain colloidal solution C is carried out in a glove box; in order to detect the performance of the composite solid electrolyte membrane prepared by the above method, a button cell is assembled in a glove box under an argon atmosphere with the water and oxygen content both lower than 0.01 ppm. The electrolyte is 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte membrane is tested. The test results are as follows: The charge-discharge capacity curve is as Figure 5 shown, and a reversible capacity of 199.1 mAh / g appears.

[0074] Example 8 A preparation method of a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure is as follows: S1, First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF, and stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiClO4 and heat and stir until dissolved. Finally, add 0.1 g of AVBN as an initiator to form solution A.

[0075] S2, Weigh 2 g of LLZO solid electrolyte powder and 1 g of 2,4,6-tris(2-propynyloxy)-1,3,5-triazine, and add them to 10 g of DMF. Stir overnight to form a homogeneous dispersion, and then a solution B is obtained after sufficient dispersion and uniformity.

[0076] S3, Add the above two solutions, namely solution A and solution B, to a sealed glass bottle, and stir for another 12 h to make the mixed solution disperse evenly to form a colloidal solution C.

[0077] S4, Drop the mixed colloidal solution C onto a glass plate, then use a scraper to scrape and coat it. Place it in an oven, keep it at 80 °C for 2 h, and then vacuum dry for 12 h to obtain a composite solid electrolyte membrane with a thickness of 30 - 40 μm.

[0078] In the above preparation method, after mixing solution B and solution A, stirring overnight to obtain the colloidal solution C was carried out in a glove box; in order to detect the performance of the composite solid electrolyte membrane prepared by the above method, a button cell was assembled in a glove box under an argon atmosphere with the water and oxygen contents both lower than 0.01 ppm, the electrolyte was 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte membrane therein was tested. The test results are as follows: The charge-discharge capacity curve is as Figure 5 shown, and a reversible capacity of 198.5 mAh / g appears.

[0079] Example 9 A preparation method of a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure is as follows: S1. First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF, stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiBF4, heat and stir until dissolved, and finally add 0.1 g of AIBN as an initiator to form solution A.

[0080] S2. Weigh 2 g of LLZO solid electrolyte powder and 1 g of 2,4,6-tris(2-propyn-1-yloxy)-1,3,5-triazine, and add them to 10 g of DMF, stir overnight to make them fully dispersed and uniform to form solution B.

[0081] S3. Add the above two solutions, namely solution A and solution B, to a sealed glass bottle, stir for another 12 h to make the mixed solution dispersed and uniform to form the colloidal solution C.

[0082] S4. Drop the mixed colloidal solution C on a glass plate, then use a scraper to scrape it, place it in a drying oven, keep it at 80 °C for 2 h, and then vacuum dry for 12 h to obtain a composite solid electrolyte membrane with a thickness of 30 - 40 μm.

[0083] In the above preparation method, after mixing solution B and solution A, stirring overnight to obtain the colloidal solution C was carried out in a glove box; in order to detect the performance of the composite solid electrolyte membrane prepared by the above method, a button cell was assembled in a glove box under an argon atmosphere with the water and oxygen contents both lower than 0.01 ppm, the electrolyte was 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte membrane therein was tested. The test results are as follows: The charge-discharge capacity curve is as Figure 5 shown, and a reversible capacity of 197.5 mAh / g appears.

[0084] Example 10 A preparation method of a composite solid electrolyte membrane with a three-dimensional interpenetrating network structure is as follows: S1. First, weigh 1.5 g of PVDF-HFP and 1.5 g of PVDF, add them to 10 g of DMF, and stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiBF4, heat and stir until dissolved, and finally add 0.1 g of AIBN as an initiator to form solution A.

[0085] S2. Weigh 2 g of LAGP solid electrolyte powder and 1 g of 2,4,6-tris(2-propynyloxy)-1,3,5-triazine, and add them to 10 g of DMF, stir overnight, and after fully dispersing and homogenizing, form solution B.

[0086] S3. Add the above two solutions, namely solution A and solution B, to a sealed glass bottle, stir for another 12 h to make the mixed solution disperse evenly to form glue solution C.

[0087] S4. Drop the mixed glue solution C on a glass plate, then use a scraper to scrape it, place it in a drying oven, keep it at 80 °C for 2 h, and then vacuum dry for 12 h to obtain a composite solid electrolyte diaphragm with a thickness of 30 - 40 μm.

[0088] In the above preparation method, after mixing solution B and solution A, stirring overnight to obtain glue solution C is carried out in a glove box; in order to detect the performance of the composite solid electrolyte diaphragm prepared by the above method, an in-button battery is assembled in a glove box with an argon atmosphere and the water and oxygen contents both lower than 0.01 ppm, the electrolyte is 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte diaphragm therein is tested. The test results are as follows: The charge-discharge capacity curve is as Figure 5 shown, and a reversible capacity of 200.1 mAh / g appears.

[0089] Comparative Example 1 A preparation method of a composite solid electrolyte membrane is as follows: S1. First, weigh 2.5 g of PVDF-HFP and 1.5 g of PVDF, and add them to 10 g of DMF, stir overnight to fully dissolve them. After observing no large particles, add 0.3 g of LiTFSI, heat and stir until dissolved.

[0090] S2. Weigh 2 g of LLZO solid electrolyte powder, add it to 10 g of DMF, and stir overnight to fully disperse and homogenize it.

[0091] S3. Add the solution obtained in step S1 and the solution obtained in step S2 together to a sealed glass bottle, stir for 12 h until dispersed evenly to form a mixed glue solution.

[0092] S4. Drop the mixed glue solution onto a glass plate, then use a scraper to scrape and coat it, place it in a drying oven, keep it at 80 °C for 2 h, and then vacuum dry it for 12 h to obtain a solid electrolyte membrane with a thickness of 30 - 40 μm.

[0093] In order to detect the performance of the solid electrolyte membrane prepared by the above method, an in - button battery was assembled in a glove box with an argon atmosphere and the contents of water and oxygen both lower than 0.01 ppm. The electrolyte was 1 M LiTFSI PC / FEC (vol%: 0.5), and the performance of the solid electrolyte membrane was tested. The test results are as follows: The SEM image is as Figure 5 shown. It can be observed that the distribution of the surface solid electrolyte particles is not very uniform, and the colloid fails to completely coat the solid electrolyte.

[0094] The charge - discharge capacity curve is as Figure 2 shown. The comparative example exhibits a reversible capacity of 177.2 mAh / g, which is due to the low ionic conductivity affecting the transport of lithium ions.

[0095] The EIS test is as Figure 3 shown. The ionic conductivity of the comparative example is on the order of 1×10−4 S / cm, which may be due to the lack of addition of triazine monomers, resulting in inevitable rigid contact between the membrane and the electrode during the hot - pressing process.

[0096] The flame - retardancy test is as Figure 7 shown. After being ignited by a lighter, the membrane burns and no flame - retardant effect is produced.

[0097] The adhesion test is as Figure 9 Figure 11 shown. With stainless - steel gaskets on both sides, the two sides of the membrane are not bonded together after hot - pressing at high temperature.

Claims

1. A preparation method of a composite solid electrolyte membrane with a three-dimensional mutual transmission network structure, characterized in that The specific steps are as follows: Step 1: First, weigh 1.5 parts of PVDF-HFP and 1.5 parts of PVDF, add them to 10 parts of DMF, and stir overnight to fully dissolve them. Then add 0.3 parts of lithium salt, heat and stir until dissolved, and finally add 0.1 part of initiator to form Solution A; Step 2: Weigh 2 parts of solid electrolyte powder and 1 part of triazine monomer, add them to 10 parts of DMF, and stir overnight to make them disperse evenly to form Solution B; Step 3: Add the above two solutions, namely Solution A and Solution B, to a sealed glass bottle, and stir for another 12 h to make the mixed solution disperse evenly to form Colloid C; Step 4: Drop the mixed Colloid C on a glass plate, then use a scraper to scrape it, place it in a drying oven, keep it warm at 80 °C for 2 h, and then vacuum dry for 12 h to obtain a composite solid electrolyte membrane with a thickness of 30 - 40 μm.

2. The preparation method of a composite solid electrolyte membrane with a three-dimensional mutual transmission network structure according to claim 1, characterized in that, The triazine monomer is one of 2,4,6-tris(2-propynyloxy)-1,3,5-triazine, 2,4,6-tris(allyloxy)-1,3,5-triazine, 1,3,5-triacryloylhexahydro-1,3,5-triazine, and tris-2-acrylate [2,4,6-trioxo-1,3,5-triazine-1,3,5(2H,4H,6H)-subunit] tris-2,1-ethylene ester.

3. The preparation method of a composite solid electrolyte membrane with a three-dimensional mutual transmission network structure according to claim 1, characterized in that, The initiator is AIBN or AVBN.

4. The preparation method of a composite solid electrolyte membrane with a three-dimensional mutual transmission network structure according to claim 1, characterized in that, The solid electrolyte powder is LLZO or LAGP.

5. The preparation method of a composite solid electrolyte membrane with a three-dimensional mutual transfer network structure according to claim 1, characterized in that, The lithium salt is one of LiTFSI, LiFSI, LiPF6, LiClO4, and LiBF4.

6. The preparation method of a composite solid electrolyte membrane with a three-dimensional mutual transmission network structure according to any one of claims 1 to 5, characterized in that, The prepared composite solid electrolyte membrane is used to assemble a lithium-ion battery.

7. The preparation method of a composite solid electrolyte membrane with a three-dimensional mutual transmission network structure according to any one of claims 1 to 5, characterized in that, The prepared composite solid electrolyte membrane has a three-dimensional interconnected network structure under electron microscopy scanning.

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