Solid electrolyte membrane and preparation method and application thereof
By combining a non-woven fabric substrate with a composite electrolyte, a solid electrolyte membrane with high ionic conductivity, large tensile strength and good flexibility was prepared, which solved the problems of low mechanical strength and high interface impedance in the existing technology and realized the possibility of large-scale production.
Patent Information
- Application Number
- CN202510659447.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-21
- Publication Date
- 2025-09-12
AI Technical Summary
Existing solid-state electrolytes have low mechanical strength, high interfacial impedance, difficulty in balancing high ionic conductivity and high flexibility, uncontrollable porosity and pore size, and difficulty in large-scale production.
A combination of non-woven fabric substrate and composite electrolyte is used. The composite electrolyte consists of vinylidene fluoride-hexafluoropropylene copolymer, sulfide electrolyte, lithium salt, titanium dioxide nanoparticles and carbon nanotubes. The solid electrolyte membrane is prepared by wet molding and hot pressing.
It achieves high ionic conductivity, large tensile strength and good flexibility, with adjustable porosity and pore size, making it suitable for large-scale industrial production.
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Figure CN120637571A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of solid-state batteries, and in particular to a solid-state electrolyte membrane and a preparation method and application thereof. Background Art
[0002] Solid-state batteries, which use solid electrolytes, are safer than batteries using liquid electrolytes (liquid electrolytes pose safety risks such as flammability and leakage) and have broader application prospects. However, existing solid-state electrolytes generally suffer from low mechanical strength, high interfacial impedance, difficulty balancing high ionic conductivity and high flexibility, uncontrollable porosity and pore size, and difficulties in large-scale production, which greatly restricts their practical application.
[0003] Therefore, it is of great significance to develop a solid electrolyte membrane with high ionic conductivity, large tensile strength, good flexibility, and flexible porosity and pore size. Summary of the Invention
[0004] The purpose of the present invention is to provide a solid electrolyte membrane and a preparation method and application thereof.
[0005] The technical solution adopted by the present invention is:
[0006] A solid electrolyte membrane comprises a non-woven fabric substrate and a loaded composite electrolyte; the composite electrolyte comprises a vinylidene fluoride-hexafluoropropylene copolymer, a sulfide electrolyte, a lithium salt, titanium dioxide nanoparticles and carbon nanotubes.
[0007] Preferably, the non-woven fabric substrate has a thickness of 20 μm to 40 μm, a porosity of 60% to 80%, and an average pore size of 3 μm to 8 μm.
[0008] Preferably, the nonwoven fabric substrate comprises the following fiber percentages by mass:
[0009] Microfiber: 50% to 60%;
[0010] Bonding fiber: 30% to 40%;
[0011] Nanofiber: 10%~20%.
[0012] Preferably, the ultrafine fiber is at least one of ultrafine polyester (PET) fiber, ultrafine polypropylene (PP) fiber, ultrafine nylon (PA) fiber, and ultrafine polyethylene (PE) fiber.
[0013] Preferably, the ultrafine fibers have a diameter of 0.1 μm to 5 μm and a length of 5 mm to 20 mm.
[0014] Preferably, the bonding fiber is at least one of polyester fiber having a melting point of 110°C to 130°C and polyolefin fiber having a melting point of 110°C to 130°C.
[0015] Preferably, the bonding fibers have a diameter of 5 μm to 10 μm and a length of 2 mm to 5 mm.
[0016] Preferably, the nanofiber is at least one of aramid nanofiber, carbon nanofiber, and nanoglass fiber.
[0017] Preferably, the nanofiber has a diameter of 500 nm to 1000 nm and a length of 1 μm to 5 μm.
[0018] Preferably, the non-woven fabric substrate is made by a preparation method comprising the following steps: dispersing ultrafine fibers, bonding fibers and nanofibers with a solvent, wet-forming the fibers, and then drying and hot-pressing the fibers to obtain the non-woven fabric substrate.
[0019] Preferably, the solvent is water.
[0020] Preferably, the forming equipment used in the wet forming is an inclined wire paper machine.
[0021] Preferably, the drying is carried out at a temperature of 80°C to 120°C.
[0022] More preferably, the drying is performed at a temperature of 90°C to 110°C.
[0023] Preferably, the hot pressing is performed at a temperature of 130° C. to 180° C. and a pressure of 5 MPa to 10 MPa.
[0024] More preferably, the hot pressing is performed at a temperature of 150° C. to 170° C. and a pressure of 7 MPa to 9 MPa.
[0025] Preferably, the mass ratio of the vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), sulfide electrolyte, lithium salt, titanium dioxide nanoparticles, and carbon nanotubes is 1:2-6:0.5-3:0.05-0.5:0.025-0.2.
[0026] Preferably, the number average molecular weight of the vinylidene fluoride-hexafluoropropylene copolymer is 50,000 g / mol to 200,000 g / mol.
[0027] Preferably, the sulfide electrolyte is Li3PS4, Li7P3S 11 , Li6PS5Cl.
[0028] Preferably, the lithium salt is at least one of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI), lithium hexafluorophosphate (LiPF6), lithium tetrafluoroborate (LiBF4), and lithium bis(oxalatoborate) (LiBOB).
[0029] Preferably, the particle size of the titanium dioxide nanoparticles is 10 nm to 100 nm.
[0030] Preferably, the carbon nanotubes have a diameter of 50 nm to 200 nm and a length of 1 μm to 10 μm.
[0031] Preferably, the solid electrolyte membrane has a thickness of 25 μm to 60 μm.
[0032] A method for preparing the solid electrolyte membrane as described above comprises the following steps: dispersing vinylidene fluoride-hexafluoropropylene copolymer, sulfide electrolyte, lithium salt, titanium dioxide nanoparticles and carbon nanotubes in a solvent to form a composite electrolyte slurry, then coating the composite electrolyte slurry on the surface of a non-woven fabric substrate and drying it to obtain a solid electrolyte membrane.
[0033] Preferably, the solvent is at least one of acetone, toluene, benzene, dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane, trichloroethane, and petroleum ether.
[0034] Preferably, the coating method is one of blade coating and dipping.
[0035] Preferably, the mass concentration of the composite electrolyte slurry is 20% to 40%.
[0036] Preferably, the coating amount of the composite electrolyte slurry on the surface of the non-woven fabric substrate is 5g / m 2 ~10g / m 2 .
[0037] A solid-state battery comprising the solid-state electrolyte membrane.
[0038] The beneficial effects of the present invention are: the solid electrolyte membrane of the present invention has the advantages of high ionic conductivity, large tensile strength, good flexibility, and flexible adjustment of porosity and pore size, and its preparation method is simple, the raw materials are cheap and easily available, and the production cost is low, and it is suitable for large-scale industrial production and application. BRIEF DESCRIPTION OF THE DRAWINGS
[0039] Figure 1 This is a micrograph of the solid electrolyte membrane of Example 1. DETAILED DESCRIPTION
[0040] The present invention will be further explained and illustrated below with reference to specific embodiments.
[0041] Example 1:
[0042] A solid electrolyte membrane, the preparation method of which is as follows:
[0043] Vinylidene fluoride-hexafluoropropylene copolymer (number average molecular weight of 100000 g / mol to 150000 g / mol), Li3PS4 (particle size of 50 nm to 150 nm), lithium bis(trifluoromethylsulfonyl imide), titanium dioxide nanoparticles (particle size of 10 nm to 100 nm) and carbon nanotubes (diameter of 50 nm to 200 nm, length of 1 μm to 10 μm) are added to acetone, and the mass ratio of vinylidene fluoride-hexafluoropropylene copolymer, Li3PS4, lithium bis(trifluoromethylsulfonyl imide), titanium dioxide nanoparticles and carbon nanotubes is 20:40:10:1:0.5. The mixture is stirred at room temperature for 24 h to prepare a composite electrolyte slurry with a mass concentration of 20%. The composite electrolyte slurry is then coated on the surface of a non-woven fabric substrate twice using a scraper, and the single coating amount is 2.5 g / m 2 , the scraper gap is 0.1 mm, the coating speed is 2 m / min, and then dried at 80°C for 5 min and then dried at 105°C for 10 min to obtain a solid electrolyte membrane (thickness is 25 μm).
[0044] The preparation method of the non-woven fabric substrate in this embodiment is as follows:
[0045] Ultrafine polyester fibers (diameter of 2 μm to 3 μm, length of 10 mm to 15 mm), polyester fibers with a melting point of 120°C (diameter of 8 μm to 9 μm, length of 3 mm to 4 mm) and aramid nanofibers (diameter of 800 nm to 1000 nm, length of 2 μm to 3 μm) were added into deionized water in a mass ratio of 5:3:2 to ultrafine polyester fibers, polyester fibers with a melting point of 120°C and aramid nanofibers. The mixture was stirred at a rate of 500 r / min for 2 h. min, and stirred for 30 minutes to prepare a slurry with a fiber mass concentration of 1.5%, and then wet-formed by an inclined wire paper machine to form wet paper, which was diluted to a slurry concentration of 0.01%, and the dehydration speed of the wire was controlled at 0.8 m / s. The wet paper was dried with hot air at 100° C. for 5 minutes, and then hot-pressed at a temperature of 160° C. and a pressure of 8 MPa for 45 seconds to obtain a non-woven fabric substrate (with a thickness of 20 μm, a porosity of 60%, and an average pore size of 3 μm).
[0046] The micrograph of the solid electrolyte membrane of this embodiment is shown in FIG. Figure 1 (a is a micrograph of the surface, b is a micrograph of the side).
[0047] Depend on Figure 1It can be seen that the composite electrolyte on the surface of the solid electrolyte membrane is evenly distributed without obvious agglomeration; the side shows that the non-woven fabric substrate is tightly bonded to the composite electrolyte, with a clear pore structure and an average pore size of about 3μm. The composite electrolyte is fully filled into the pores of the substrate to form a continuous ion conduction path, indicating that the porosity and pore size design of the substrate and the coating process are reasonable.
[0048] Example 2:
[0049] A solid electrolyte membrane, the preparation method of which is as follows:
[0050] Vinylidene fluoride-hexafluoropropylene copolymer (number average molecular weight of 100000 g / mol to 150000 g / mol), Li3PS4 (particle size of 50 nm to 150 nm), lithium bis(trifluoromethylsulfonyl imide), titanium dioxide nanoparticles (particle size of 10 nm to 100 nm) and carbon nanotubes (diameter of 50 nm to 200 nm, length of 1 μm to 10 μm) are added to acetone, and the mass ratio of vinylidene fluoride-hexafluoropropylene copolymer, Li3PS4, lithium bis(trifluoromethylsulfonyl imide), titanium dioxide nanoparticles and carbon nanotubes is 20:40:10:1:0.5. The mixture is stirred at room temperature for 24 h to prepare a composite electrolyte slurry with a mass concentration of 40%. The non-woven fabric substrate is then immersed in the composite electrolyte slurry for 30 s and then taken out. The coating amount is 10 g / m 2 , and then hot air dried at 150°C for 8 minutes to obtain a solid electrolyte membrane (thickness of 60 μm).
[0051] The preparation method of the non-woven fabric substrate in this embodiment is as follows:
[0052] Ultrafine polypropylene fibers (diameter of 2 μm to 3 μm, length of 10 mm to 15 mm), polyester fibers with a melting point of 120°C (diameter of 8 μm to 9 μm, length of 3 mm to 4 mm) and aramid nanofibers (diameter of 800 nm to 1000 nm, length of 2 μm to 3 μm) were added to deionized water in a mass ratio of 6:3:1. The mixture was stirred at a rate of 500 r / min. / min for 30 minutes to prepare a slurry with a fiber mass concentration of 1.5%, then a slant wire paper machine was used for wet forming to form wet paper, which was diluted to a slurry concentration of 0.01%, and the dehydration speed of the wire was controlled at 0.8 m / s. The wet paper was dried with hot air at 100°C for 5 minutes, and then hot-pressed at a temperature of 160°C and a pressure of 8 MPa for 45 seconds to obtain a non-woven fabric substrate (with a thickness of 40 μm, a porosity of 80%, and an average pore size of 8 μm).
[0053] Example 3:
[0054] A solid electrolyte membrane, the preparation method of which is as follows:
[0055] The non-woven fabric substrate (same as Example 1) was immersed in the composite electrolyte slurry (same as Example 2) for 30 seconds and then taken out. The coating amount was 10 g / m 2 , and then hot air dried at 150°C for 8 minutes to obtain a solid electrolyte membrane (thickness of 40 μm).
[0056] Example 4:
[0057] A solid electrolyte membrane, the preparation method of which is as follows:
[0058] The composite electrolyte slurry (same as in Example 1) was coated on the surface of the non-woven fabric substrate (same as in Example 2) twice using a scraper, with a single coating amount of 2.5 g / m 2 , the scraper gap is 0.1 mm, the coating speed is 2 m / min, and then dried at 80°C for 5 min and then dried at 105°C for 10 min to obtain a solid electrolyte membrane (thickness is 45 μm).
[0059] Example 5:
[0060] A solid electrolyte membrane, the preparation method of which is as follows:
[0061] The composite electrolyte slurry (same as in Example 1) was scraped onto the surface of the non-woven fabric substrate twice using a scraper, with a single coating amount of 2.5 g / m 2 , the scraper gap is 0.1 mm, the coating speed is 2 m / min, and then dried at 80°C for 5 min and then dried at 105°C for 10 min to obtain a solid electrolyte membrane (thickness is 35 μm).
[0062] The preparation method of the non-woven fabric substrate in this embodiment is as follows:
[0063] Ultrafine polyester fibers (diameter of 2 μm to 3 μm, length of 10 mm to 15 mm), polyester fibers with a melting point of 120°C (diameter of 8 μm to 9 μm, length of 3 mm to 4 mm) and aramid nanofibers (diameter of 800 nm to 1000 nm, length of 2 μm to 3 μm) were added into deionized water in a mass ratio of 5:4:1 to ultrafine polyester fibers, polyester fibers with a melting point of 120°C and aramid nanofibers. The mixture was stirred at a rate of 500 r / min for 2 h. min, and stirred for 30 minutes to prepare a slurry with a fiber mass concentration of 1.5%, which was then wet-formed using an inclined wire paper machine to form wet paper, diluted to a slurry concentration of 0.01%, and the wire dewatering speed was controlled at 0.8 m / s. The wet paper was dried with hot air at 100° C. for 5 minutes, and then hot-pressed at a temperature of 160° C. and a pressure of 8 MPa for 45 seconds to obtain a non-woven fabric substrate (with a thickness of 30 μm, a porosity of 70%, and an average pore size of 5 μm).
[0064] Comparative Example 1:
[0065] A solid electrolyte membrane, the preparation method of which is as follows:
[0066] The non-woven fabric substrate was immersed in the composite electrolyte slurry (same as in Example 1) for 30 seconds and then taken out. The coating amount was 5 g / m 2 , and then hot air dried at 150°C for 8 minutes to obtain a solid electrolyte membrane (thickness of 35 μm).
[0067] The preparation method of the non-woven fabric substrate in this comparative example is as follows:
[0068] Ultrafine polyester fibers (with a diameter of 2 μm to 3 μm and a length of 10 mm to 15 mm) were added to deionized water and stirred for 30 minutes at a stirring rate of 500 r / min to prepare a slurry with a fiber mass concentration of 1.5%. The slurry was then wet-formed using an inclined wire paper machine to form wet paper, which was diluted to a slurry concentration of 0.01%. The dehydration speed of the wire was controlled at 0.8 m / s. The wet paper was dried with hot air at 100°C for 5 minutes and then hot-pressed at a temperature of 160°C and a pressure of 8 MPa for 45 seconds to obtain a non-woven fabric substrate (with a thickness of 30 μm, a porosity of 70%, and an average pore size of 5 μm).
[0069] Comparative Example 2:
[0070] A solid electrolyte membrane, the preparation method of which is as follows:
[0071] Vinylidene fluoride-hexafluoropropylene copolymer (number average molecular weight of 100000 g / mol to 150000 g / mol), Li3PS4 (particle size of 50 nm to 150 nm), lithium bis(trifluoromethylsulfonyl imide) and carbon nanotubes (diameter of 50 nm to 200 nm, length of 1 μm to 10 μm) were added to acetone, and the mass ratio of vinylidene fluoride-hexafluoropropylene copolymer, Li3PS4, lithium bis(trifluoromethylsulfonyl imide) and carbon nanotubes was 20:40:10:0.5. The mixture was stirred at room temperature for 24 h to prepare a composite electrolyte slurry with a mass concentration of 20%. The composite electrolyte slurry was then scraped onto the surface of a non-woven fabric substrate (same as in Example 1) twice using a scraper, and the single coating amount was 2.5 g / m 2 , the scraper gap is 0.1 mm, the coating speed is 2 m / min, and then dried at 80°C for 5 min and then dried at 105°C for 10 min to obtain a solid electrolyte membrane (thickness is 25 μm).
[0072] Comparative Example 3:
[0073] A solid electrolyte membrane, the preparation method of which is as follows:
[0074] Vinylidene fluoride-hexafluoropropylene copolymer (number average molecular weight of 100,000 g / mol to 150,000 g / mol), Li3PS4 (particle size of 50 nm to 150 nm), lithium bis(trifluoromethylsulfonyl imide) and titanium dioxide nanoparticles (particle size of 10 nm to 100 nm) were added to acetone, and the mass ratio of vinylidene fluoride-hexafluoropropylene copolymer, Li3PS4, lithium bis(trifluoromethylsulfonyl imide) and titanium dioxide nanoparticles was 20:40:10:1. The mixture was stirred at room temperature for 24 h to prepare a composite electrolyte slurry with a mass concentration of 20%. The composite electrolyte slurry was then scraped onto the surface of a non-woven fabric substrate (same as in Example 1) twice using a scraper, and the single coating amount was 2.5 g / m 2 , the scraper gap is 0.1 mm, the coating speed is 2 m / min, and then dried at 80°C for 5 min and then dried at 105°C for 10 min to obtain a solid electrolyte membrane (thickness is 25 μm).
[0075] Performance testing:
[0076] The performance test data of the solid electrolyte membranes of Examples 1 to 5 and Comparative Examples 1 to 3 are shown in the following table:
[0077] Table 1 Performance test data of solid electrolyte membrane
[0078] Test items Ionic conductivity (S / cm) Tensile strength (MPa) Flexibility (bending radius / number of cycles) Example 1 4.53 28 ≤2mm / 1000 times Example 2 1.26 20 ≤3mm / 500 times Example 3 2.33 18 ≤4mm / 300 times Example 4 0.97 25 ≤3mm / 600 times Example 5 0.32 28 ≤3mm / 800 times Comparative Example 1 2.13 15 Brittle fracture (unable to bend) / 50 times Comparative Example 2 3.19 28 ≤2mm / 500 times Comparative Example 3 3.38 28 ≤2mm / 600 times
[0079] Note:
[0080] Ionic conductivity: The solid electrolyte membrane was cut into discs with a diameter of 16 mm and then assembled with a stainless steel disc (SS) with a diameter of 16 mm to form a symmetrical cell with an SS / solid electrolyte membrane / SS structure. The bulk resistance was then tested using electrochemical impedance spectroscopy, and the ionic conductivity was calculated using the formula: Ionic conductivity = d / (s × Ω), where d is the membrane thickness, s is the effective contact area, and Ω is the bulk resistance.
[0081] Tensile strength: Tested in accordance with GB / T 1040.3-2006 Plastics—Determination of tensile properties—Part 3: Test conditions for films and sheets and ASTM D882-10 Standard test method for tensile properties of thin plastic sheets.
[0082] Flexibility: Tested in accordance with ASTM D2176: MIT Folding Endurance of Paper and Paperboard.
[0083] From Table 1 we can see that:
[0084] 1) The solid electrolyte membranes of Examples 1 to 5 not only have sufficiently large tensile strength (greater than conventional polymer electrolytes, solving the pain point of solid electrolytes being "brittle"), but also have an ionic conductivity that is improved to the industry-leading level (>4×10 -4 S / cm), the overall performance is very excellent;
[0085] 2) The solid electrolyte membranes of Examples 1 to 5 can withstand high-frequency bending, meeting the stringent requirements of flexible batteries for the flexibility of the electrolyte membrane;
[0086] In summary, the solid electrolyte membrane of the present invention has the advantages of high ionic conductivity, high tensile strength, good flexibility, and flexible adjustment of porosity and pore size. In addition, its preparation method is simple, the raw materials are cheap and easily available, and the production cost is low, making it suitable for large-scale industrial production and application.
[0087] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.
Claims
1. A solid electrolyte membrane, characterized in that The composition includes a non-woven fabric substrate and a loaded composite electrolyte; the composite electrolyte includes a vinylidene fluoride-hexafluoropropylene copolymer, a sulfide electrolyte, a lithium salt, titanium dioxide nanoparticles and carbon nanotubes.
2. The solid electrolyte membrane according to claim 1, wherein: The non-woven fabric substrate has a thickness of 20 μm to 40 μm, a porosity of 60% to 80%, and an average pore size of 3 μm to 8 μm.
3. The solid electrolyte membrane according to claim 1 or 2, characterized in that: The nonwoven fabric substrate comprises the following fibers in percentage by mass: Microfiber: 50% to 60%; Bonding fiber: 30% to 40%; Nanofiber: 10%~20%.
4. The solid electrolyte membrane according to claim 3, wherein: The ultrafine fiber is at least one of ultrafine polyester fiber, ultrafine polypropylene fiber, ultrafine nylon fiber, and ultrafine polyethylene fiber; the diameter of the ultrafine fiber is 0.1 μm to 5 μm, and the length is 5 mm to 20 mm; the bonding fiber is at least one of polyester fiber with a melting point of 110°C to 130°C and polyolefin fiber with a melting point of 110°C to 130°C; the diameter of the bonding fiber is 5 μm to 10 μm, and the length is 2 mm to 5 mm; the nanofiber is at least one of aramid nanofiber, carbon nanofiber, and nanoglass fiber; the diameter of the nanofiber is 500 nm to 1000 nm, and the length is 1 μm to 5 μm.
5. The solid electrolyte membrane according to claim 1 or 2, characterized in that: The mass ratio of the vinylidene fluoride-hexafluoropropylene copolymer, the sulfide electrolyte, the lithium salt, the titanium dioxide nanoparticles, and the carbon nanotubes is 1:2-6:0.5-3:0.05-0.5:0.025-0.
2.
6. The solid electrolyte membrane according to claim 1 or 2, characterized in that: The number average molecular weight of the vinylidene fluoride-hexafluoropropylene copolymer is 50,000 g / mol to 200,000 g / mol.
7. The solid electrolyte membrane according to claim 1 or 2, characterized in that: The sulfide electrolyte is Li3PS4, Li7P3S 11 , Li6PS5Cl; the lithium salt is at least one of lithium bis(trifluoromethylsulfonyl)imide, lithium hexafluorophosphate, lithium tetrafluoroborate, and lithium bis(oxalatoborate).
8. The solid electrolyte membrane according to claim 1 or 2, characterized in that: The particle size of the titanium dioxide nanoparticles is 10 nm to 100 nm; the diameter of the carbon nanotubes is 50 nm to 200 nm, and the length is 1 μm to 10 μm.
9. A method for preparing a solid electrolyte membrane according to any one of claims 1 to 8, characterized in that: The following steps are involved: The vinylidene fluoride-hexafluoropropylene copolymer, sulfide electrolyte, lithium salt, titanium dioxide nanoparticles and carbon nanotubes are dispersed in a solvent to prepare a composite electrolyte slurry, which is then coated on the surface of a non-woven fabric substrate and dried to obtain a solid electrolyte membrane.
10. A solid-state battery, characterized in that: A solid electrolyte membrane according to any one of claims 1 to 8.