An ultrathin quasi-solid-state electrolyte membrane, a preparation method thereof and a lithium metal battery

Abstract

The present application relates to the technical field of lithium battery, especially to an ultrathin quasi-solid-state electrolyte film, a preparation method thereof and a lithium metal battery, the ultrathin quasi-solid-state electrolyte film is formed by scraping coating of quasi-solid-state electrolyte slurry; the quasi-solid-state electrolyte slurry comprises a binder and a non-binder component, the non-binder component comprises aramid nanofiber, metal organic framework nanoparticles, a solvent and an electrolyte; the ultrathin quasi-solid-state electrolyte film of the present application realizes the improvement of ion conductivity through the synergistic effect of aramid nanofiber, MOF nanoparticles, the solvent and the electrolyte, realizes ultrathin design (4-10 mu m), rigidity improvement, and further enhances the anti-dendrite performance of the quasi-solid-state lithium metal battery, realizes higher energy density, solves the mutual exclusion problem of 'rigidity-thickness-safety' of the traditional quasi-solid-state electrolyte film, and makes it have better application prospect in the lithium metal battery.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery, and particularly relates to an ultrathin quasi-solid-state electrolyte film and a preparation method thereof and a lithium metal battery. BACKGROUND

[0002] Lithium metal battery (LMB) is considered as the core carrier of the next generation of high energy density energy storage system due to its extremely high theoretical energy density (3860 mAhg -1 ) and low redox potential (-3.04 V vs. SHE). However, the uncontrollable growth of lithium dendrites in the traditional liquid electrolyte system causes battery short circuit, interface side reaction and thermal runaway, which seriously hinders its practical application. Although solid-state electrolyte (SSE) can inhibit dendrites through physical barrier, the high interface impedance, low ionic conductivity (especially <0.1 mS cm -1 ) and poor mechanical flexibility of solid-state materials generally existing, make it difficult to balance the design of ultrathin and long-term cycle stability. In recent years, quasi-solid-state electrolyte (QSE) partially alleviates the interface problem by introducing plasticized ion transport medium (such as ionic liquid, polymer gel), but its mechanical strength (usually <1 GPa) is still insufficient to effectively resist lithium deposition stress, and the use of flammable organic solvents brings safety hazards. In addition, the thickness of the existing QSE is more than 20 µm, which significantly reduces the volume energy density of the battery, and the ultrathin design (<10 µm) often sacrifices the mechanical properties, forming a mutual exclusion dilemma of "rigidity-thickness-safety". SUMMARY

[0003] The present application provides an ultrathin quasi-solid-state electrolyte film and a preparation method thereof and a lithium metal battery, to solve the problem that the quasi-solid-state electrolyte film in the prior art cannot balance rigidity, thickness and safety.

[0004] According to a first aspect of the present application, the present application provides an ultrathin quasi-solid-state electrolyte film formed by blade coating of a quasi-solid-state electrolyte slurry; the quasi-solid-state electrolyte slurry includes a binder and a non-binder component, and the non-binder component includes aramid nanofiber, metal organic framework nanoparticle, solvent and electrolyte.

[0005] The aramid nanofiber in the quasi-solid electrolyte slurry of the present application can serve as a mechanical reinforcing framework due to its high modulus (~100 GPa) and thermal stability, the metal-organic framework (MOF) nanoparticles can be used to guide the directional transport of lithium ions due to their adjustable nanopore channels and surface chemical properties, the solvent can improve the performance of the electrolyte membrane by adjusting the rheological properties of the slurry, dispersing solid particles, controlling the microstructure of the membrane, improving the interfacial compatibility, controlling the thickness of the membrane, and affecting the drying process of the membrane, and the electrolyte serves as an ion transport carrier. The ultra-thin quasi-solid electrolyte membrane of the present application realizes the improvement of ion conductivity through the synergistic effect of aramid nanofiber, MOF nanoparticles, solvent and electrolyte, ultra-thin design (4-10 μm), rigidity improvement, and further enhancement of the dendrite resistance of quasi-solid lithium metal batteries, realizing high energy density, and solving the mutual exclusion problem of "rigidity-thickness-safety" of traditional quasi-solid electrolyte membranes.

[0006] Further, the aramid nanofiber is selected from one or more of para-aramid nanofiber or meta-aramid nanofiber. The para-aramid nanofiber or meta-aramid nanofiber has higher modulus and stability, and can form a synergistic effect with the metal-organic framework nanoparticles to improve the performance of the ultra-thin quasi-solid electrolyte membrane.

[0007] Further, the aramid nanofiber is preferably poly-p-phenylene terephthalate nanofiber. The poly-p-phenylene terephthalate nanofiber has ultra-high modulus and thermal stability, and can significantly improve the mechanical strength and dendrite puncture resistance of the ultra-thin quasi-solid electrolyte membrane.

[0008] Further, the metal-organic framework nanoparticles are one or more of UIO-66, MOF-801, MOF-808, MNNU-5, MIL-101, HKUST-1, and MOF-5.

[0009] Further, the metal-organic framework nanoparticles are preferably UIO-66. UIO-66 has a stable zirconium-oxygen cluster structure and adjustable pore size (0.8-1.2 nm) to efficiently guide the directional transport of lithium ions, and can form a better synergistic effect with the aramid nanofiber of the present application to improve the ionic conductivity of the ultra-thin quasi-solid electrolyte membrane to 0.33-0.47 mS / cm.

[0010] Further, the mass percentage content K% of the aramid nanofiber in the non-binder component and the length L and diameter D1 of the aramid nanofiber satisfy: K=M*(L*D1) 2 / 3 wherein M is a correction factor, and is 1.1.

[0011] Further, the binder is one or more of polyacrylonitrile (PAN), polyethylene oxide (PEO), polyethylene glycol (PEG), polyvinyl alcohol (PVA), styrene butadiene rubber (SBR), polyvinylidene fluoride-hexafluoropropylene (P(VDF-HFP)), polyacrylic acid, polytetrafluoroethylene (PTFE), polyvinylidene fluoride (PVDF), polymethyl methacrylate (PMMA), polytetraethylene glycol diacrylate, sulfur-nitrogen polymer (SN), pentaerythritol tetraacrylate (PETEA), and copolymers or combinations thereof.

[0012] Further, the solvent is one or more of water, dimethylacetamide, N,N-dimethylformamide (DMF), acetonitrile, chloroform, dimethyl sulfoxide, dichloromethane, nitrogen methyl pyrrolidone, acetone.

[0013] Preferably, the mass percentage content K% of the aramid nanofiber in the non-binder component is 1-21%. The mass percentage content in the above range can better balance the rigidity and ionic conductivity of the ultra-thin quasi-solid electrolyte membrane. If the content is too low, it is not conducive to the formation of fiber network, and thus not conducive to the formation of an effective mechanical skeleton. If the content is too high, the excess fiber will block the ion channel, thereby causing the ionic conductivity to decrease.

[0014] Further, the mass percentage content X% of the metal-organic framework nanoparticles in the non-binder component and the average particle size D2 of the metal-organic framework nanoparticles satisfy: 0.3*K≤X≤D2 / 5.

[0015] Preferably, the mass percentage content X% of the metal-organic framework nanoparticles in the non-binder component is 5-13%.

[0016] Limiting the mass percentage content of the metal-organic framework nanoparticles (5%-13%) can make the nanoparticles uniformly dispersed in the electrolyte membrane and form suitable ion transmission channels. This not only ensures efficient transmission of lithium ions, but also avoids excessive particles causing a decrease in the compactness of the membrane or too few particles failing to fully play their role in guiding ion transmission, further optimizing the ionic conductivity and interface stability of the electrolyte membrane.

[0017] Further, the length L of the aramid nanofiber ranges from 4 to 10 pm, and the diameter D1 ranges from 5 to 15 nm; the diameter D2 of the metal-organic framework nanoparticle ranges from 50 to 100 nm. By limiting the size of the aramid nanofiber and the metal-organic framework nanoparticle within a reasonable range, the optimal performance of these components in the electrolyte membrane can be ensured. The length and diameter of the aramid nanofiber within the specified range can form an effective mechanical reinforcement framework, without affecting the flexibility and ion transmission performance of the membrane due to excessive size. The particle size of the metal-organic framework nanoparticle between 50 and 100 nm can ensure that it has sufficient specific surface area and porosity to promote lithium ion transmission, and can be uniformly dispersed in the membrane to avoid particle agglomeration affecting the uniformity and electrical performance of the membrane.

[0018] Further, the solvent is selected from one or more of NMP, DMF, DMAc. These solvents have good solubility and volatility, which can fully mix the components in the slurry and form a stable slurry system, facilitating the subsequent coating process. At the same time, the appropriate solvent helps to control the drying speed and forming quality of the membrane, thereby affecting the microstructure and performance of the electrolyte membrane.

[0019] Further, the electrolyte includes one or more of a first electrolyte and a second electrolyte; the first electrolyte is an ionic liquid containing a metal salt; and the second electrolyte is formed by dissolving a metal salt in a non-aqueous solvent.

[0020] The metal salt can be LiTFSI or LiPF6, etc. The non-aqueous solvent can be one or more of DMC, EC, EMC, DOL, DEC.

[0021] Preferably, in the second electrolyte, the concentration of the metal salt is 1-2 mol / L.

[0022] Preferably, the mass percentage of the electrolyte in the non-binder component is 10-90%. Limiting the mass percentage of the electrolyte within a reasonable range is beneficial for adjusting the porosity of different membrane compositions to ensure the full utilization of the pores.

[0023] Further, the thickness of the ultra-thin quasi-solid-state electrolyte membrane is 4-10 pm. At this thickness, the ultra-thin design of the membrane can be realized while ensuring that the electrolyte membrane has sufficient mechanical strength and ion transmission performance. The ultra-thin electrolyte membrane can reduce the internal resistance of the battery, improve the power density and energy density of the battery, and also help to shorten the transmission path of lithium ions, further improving the charge and discharge rate and cycle performance of the battery, meeting the requirements of high-energy-density lithium metal batteries for the thickness of the electrolyte membrane.

[0024] According to a second aspect of the present application, the present application also provides a preparation method of the above-mentioned ultra-thin quasi-solid-state electrolyte film, comprising the following steps:

[0025] The aramid nanofiber, the metal organic framework nanoparticles, the solvent and the electrolyte are mixed to obtain a quasi-solid-state electrolyte slurry; the obtained quasi-solid-state electrolyte slurry is coated on the positive electrode side of a lithium metal battery, and dried to obtain an ultra-thin quasi-solid-state electrolyte film.

[0026] The preparation method is simple and efficient, and the ultra-thin quasi-solid-state electrolyte film can be obtained by directly coating and drying the slurry obtained by mixing the components, which is easy to operate and mass-produced. This preparation method can ensure uniform distribution of the components in the film, form an electrolyte film with good mechanical properties and ion transmission performance, and is suitable for the assembly and practical application of lithium metal batteries, thereby providing a feasible way for the industrial production of the ultra-thin quasi-solid-state electrolyte film.

[0027] Further, the drying is performed at 70-80℃ for 6-12h. The special limitation of the drying condition can ensure that the solvent in the slurry is fully volatilized, so that the electrolyte film is completely dried and formed, while avoiding the performance damage of the film caused by high temperature or long time, such as thermal decomposition of aramid nanofiber or structural damage of metal organic framework nanoparticles. Suitable drying conditions help to obtain an ultra-thin quasi-solid-state electrolyte film that is uniform, dense and stable in performance, thereby ensuring the performance and safety of the battery during use.

[0028] According to a third aspect of the present application, the present application also provides a lithium metal battery comprising the above-mentioned ultra-thin quasi-solid-state electrolyte film or an ultra-thin quasi-solid-state electrolyte film prepared by the above-mentioned preparation method of the ultra-thin quasi-solid-state electrolyte film.

[0029] The application of the above-mentioned ultra-thin quasi-solid-state electrolyte film in lithium metal batteries can fully exert its excellent performance, effectively solve the problems of traditional liquid electrolytes and solid electrolytes in lithium metal batteries, such as safety hazards caused by lithium dendrite growth, high interfacial impedance, low ionic conductivity, poor mechanical properties, etc. The electrolyte film can improve the dendrite resistance of the battery, enhance the cycle stability, rate performance and safety of the battery, realize the high performance and high energy density of the lithium metal battery, and promote the development and practical application of lithium metal battery technology.

[0030] The ultra-thin quasi-solid-state electrolyte film provided by the present application improves the ionic conductivity through the synergistic effect of aramid nanofiber, MOF nanoparticles, solvent and electrolyte, realizes ultra-thin design (4-10μm), improves the rigidity of the quasi-solid-state electrolyte film, and further enhances the dendrite resistance of the quasi-solid-state lithium metal battery, realizes high energy density, solves the mutual exclusion problem of “rigidity-thickness-safety” of traditional quasi-solid-state electrolyte film, and has better application prospect in lithium metal batteries. BRIEF DESCRIPTION OF DRAWINGS

[0031] In order to more clearly illustrate the technical solutions of the present application or the prior art, the drawings required to be used in the following embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can also be obtained by those skilled in the art without creative labor on the basis of these drawings.

[0032] Figure 1 is a schematic diagram of the cross-section structure of the ultra-thin quasi-solid-state electrolyte film provided by the embodiment 1 of the present application.

[0033] Figure 2 is a scanning electron microscope image of the cross-section of the ultra-thin quasi-solid-state electrolyte film provided by the embodiment 1 of the present application. DETAILED DESCRIPTION

[0034] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0035] Embodiment 1

[0036] The present embodiment provides an ultra-thin quasi-solid-state electrolyte film, which is formed by doctor-blade coating of a quasi-solid-state electrolyte slurry; the quasi-solid-state electrolyte slurry comprises a binder and a non-binder component, the non-binder component comprises 8.1% poly-p-phenylene terephthalate nanofibers (diameter D1 is 5 nm, length L is 4 μm), 5.4% metal organic framework nanoparticles UIO-66 (particle size D2 is 50 nm), and 86.5% electrolyte, in terms of mass fraction. The polymer binder is PVDF, and the mass ratio of the above-mentioned non-binder component to the polymer binder is 5:100. The electrolyte is formed by dissolving LiTFSI in a non-aqueous solvent, the non-aqueous solvent is composed of EC and DEC in a volume ratio of 1:1, and the concentration of LiTFSI is 1 mole / liter.

[0037] The preparation method of the ultra-thin quasi-solid-state electrolyte film comprises the following steps:

[0038] The poly-p-phenylene terephthalate nanofibers, the binder, the metal organic framework nanoparticles UIO-66, the DMF solvent and the 1 mole / liter LiTFSI EC / DEC electrolyte are mixed, and the slurry is uniformly mixed by high-speed stirring to obtain a quasi-solid-state electrolyte slurry. The obtained quasi-solid-state electrolyte slurry is directly doctor-blade coated on the cathode surface of a lithium metal battery, and dried at 80°C for 4h.

[0039] The overall thickness of the obtained ultra-thin quasi-solid electrolyte film sample S1 is 4 pm.

[0040] The schematic diagram of the cross-sectional structure of the obtained ultra-thin quasi-solid electrolyte film sample S1 of this example is shown in Figure 1 The cross-sectional scanning electron microscope image is shown in Figure 2

[0041] Example 2

[0042] This example provides an ultra-thin quasi-solid electrolyte film, which differs from Example 1 in that:

[0043] The non-binder component includes 20.4% poly-p-phenylene terephthalate nanofibers (8 nm in diameter and 10 pm in length), 12.3% metal organic framework nanoparticles UIO-66 (100 nm in particle size), and 67.3% electrolyte. The polymer binder is PVDF / PEO, and the mass ratio of the binder to the above non-binder component is 12:100. The electrolyte is formed by dissolving LiPF6 in a non-aqueous solvent, the non-aqueous solvent is composed of EC and DEC in a volume ratio of 1:1, and the concentration of LiPF6 is 1 mole / liter.

[0044] The preparation method of the ultra-thin quasi-solid electrolyte film differs from that of Example 1 in that the drying is performed at 70°C for 6 h.

[0045] The overall thickness of the obtained ultra-thin quasi-solid electrolyte film sample S1 is 5 pm.

[0046] Example 3

[0047] This example provides an ultra-thin quasi-solid electrolyte film, which differs from Example 1 in that:

[0048] The non-binder component includes 20.4% poly-p-phenylene terephthalate nanofibers (8 nm in diameter and 10 pm in length), 12.3% metal organic framework nanoparticles UIO-66 (100 nm in particle size), and 67.3% electrolyte. The polymer binder is PVDF / PEO, and the mass ratio of the binder to the above non-binder component is 12:100. The electrolyte is formed by dissolving LiPF6 in a non-aqueous solvent, the non-aqueous solvent is composed of EC and DEC in a volume ratio of 1:1, and the concentration of LiPF6 is 1 mole / liter.

[0049] The preparation method of the ultra-thin quasi-solid electrolyte film differs from that of Example 1 in that the drying is performed at 80°C for 3 h.

[0050] The overall thickness of the obtained ultra-thin quasi-solid electrolyte film sample S1 is 10 pm.

[0051] ​Example 4

[0052] This example provides a kind of ultra-thin quasi-solid electrolyte film, different from the embodiment 1, it is that:

[0053] Non-adhesive component includes 12.9% poly (p-phenylene terephthalate) nanofiber (diameter is 5nm, length is 8 μm), 8.9% metal organic framework nanoparticles UIO-66 (particle size 90nm), 78.2% electrolyte.The polymer binder is PVDF, and the mass ratio of the above-mentioned non-adhesive component is 10:100.Electrolyte is formed by dissolving LiTFSI in non-aqueous solvent, and the non-aqueous solvent is composed of DOL and DME in a volume ratio of 1:1, and the concentration of LiTFSI is 1 mol / L.

[0054] The preparation method of the ultra-thin quasi-solid electrolyte film is the same as that of example 1.

[0055] The overall thickness of the obtained ultra-thin quasi-solid electrolyte film sample S1 is 6 μm.

[0056] Example 5

[0057] This example provides a kind of ultra-thin quasi-solid electrolyte film, different from the embodiment 1, it is that:

[0058] Non-adhesive component includes 12.9% poly (p-phenylene terephthalate) nanofiber (diameter is 5nm, length is 8 μm), 8.9% metal organic framework nanoparticles UIO-66 (particle size 90nm), 78.2% electrolyte.The polymer binder is PVDF, and the mass ratio of the above-mentioned non-adhesive component is 10:100.Electrolyte is formed by dissolving LiTFSI in non-aqueous solvent, and the non-aqueous solvent is composed of DOL and DME in a volume ratio of 1:1, and the concentration of LiTFSI is 1 mol / L.

[0059] The preparation method of the ultra-thin quasi-solid electrolyte film is different from that of example 1, and the drying is dried at 70 DEG C for 3h.

[0060] The overall thickness of the obtained ultra-thin quasi-solid electrolyte film sample S1 is 6 μm.

[0061] Example 6

[0062] This example provides a kind of ultra-thin quasi-solid electrolyte film, different from the embodiment 1, it is that:

[0063] The non-binder component includes 10.1% poly-p-phenylene terephthalate nanofiber (7 nm in diameter and 4 μm in length), 7.8% metal organic framework nanoparticles UIO-66 (80 nm in particle size), and 72.1% electrolyte. The electrolyte is formed by dissolving LiPF6 in a non-aqueous solvent, the non-aqueous solvent is composed of DMC and EC in a volume ratio of 1:1, and the concentration of LiPF6 is 1 mole / liter.

[0064] The preparation method of the ultrathin quasi-solid-state electrolyte film differs from that of Example 1 in that the drying is performed at 80°C for 4 h.

[0065] The overall thickness of the obtained ultrathin quasi-solid-state electrolyte film sample S1 is 5 μm.

[0066] Example 7

[0067] This example provides an ultrathin quasi-solid-state electrolyte film, which differs from Example 2 in that an equal amount of cellulose acetate is used to replace the poly-p-phenylene terephthalate nanofiber.

[0068] Example 8

[0069] This example provides an ultrathin quasi-solid-state electrolyte film, which differs from Example 2 in that an equal amount of MOF-5 is used to replace UIO-66.

[0070] Example 9

[0071] This example provides an ultrathin quasi-solid-state electrolyte film, which differs from Example 2 in that the mass percentage content K% of the poly-p-phenylene terephthalate nanofiber in the non-binder component is 5%.

[0072] Example 10

[0073] This example provides an ultrathin quasi-solid-state electrolyte film, which differs from Example 2 in that the mass percentage content X% of the metal organic framework nanoparticles in the non-binder component is 3%.

[0074] Comparative Example 1

[0075] This comparative example provides a quasi-solid-state electrolyte film, which differs from Example 2 in that bacterial cellulose is used to replace the poly-p-phenylene terephthalate nanofiber.

[0076] The rigidity of the ultra-thin quasi-solid electrolyte films of the test examples and the comparative examples was tested by nanoindentation, and the test results are shown in Table 1 below. The ultra-thin quasi-solid electrolyte films of the examples and the comparative examples were applied to lithium metal batteries, and the lithium metal batteries were assembled in the following manner: the assembly of all the batteries was carried out in an argon atmosphere glove box (H2O < 0.1 ppm, O2 < 0.1 ppm). The lithium metal symmetric battery was assembled in a sandwich configuration, using a high-purity lithium foil (99.9%) with a diameter of 14 mm and a thickness of 0.45 mm as the double electrode, and the pre-pressed electrolyte disc (Φ16 mm) was placed between the two lithium foils to form a Li| electrolyte| Li sandwich structure, which was then packaged in a CR2032 type button cell shell to form a closed system.

[0077] The performance of the assembled lithium metal batteries was tested by performing constant current cyclic polarization test on the Li||Li symmetric battery system, and each cycle period included one hour of lithium deposition / stripping process.

[0078] The test results are shown in Table 1 below.

[0079] Table 1

[0080]

[0081] The experimental data of Examples 1-10 and Comparative Example 1 show that the ultra-thin quasi-solid electrolyte films of the present application have significant performance advantages in rigidity, ionic conductivity, ion transference number, and cycle life of lithium symmetric batteries. Specifically, the rigidity of the ultra-thin quasi-solid electrolyte films of Examples 1-10 is between 3.4-5.4 GPa, the ionic conductivity is between 0.32-0.48 mS cm -1 , the ion transference number is between 0.54-0.76, and the cycle life of the lithium symmetric battery is between 320-1000 hours at a current density of 2 mA / cm². Among them, Example 2 performs the best, with a rigidity of 5.4 GPa, an ionic conductivity of 0.47 mS cm -1 , an ion transference number of 0.76, and a lithium symmetric battery cycle life of 1000 hours. After replacing the poly-para-phenylene terephthalate nanofiber with bacterial cellulose in Comparative Example 1, the rigidity, ionic conductivity, ion transference number, and cycle life of the lithium symmetric battery are all lower than those of Examples 1-10, indicating that the poly-para-phenylene terephthalate nanofiber and other components used in the present application play a key role in improving the performance of the ultra-thin quasi-solid electrolyte film, effectively solving the mutual exclusion problem of "rigidity-thickness-safety" of traditional quasi-solid electrolyte films, and making it have better application prospects in lithium metal batteries.

[0082] It should be pointed out finally that the above embodiments are only used to illustrate the technical solutions of the present application, but not to limit the same; and although the present application has been described in detail with reference to the foregoing embodiments, it should be appreciated by those skilled in the art that the technical solutions recorded in the foregoing embodiments can be modified, or some technical features thereof can be replaced equivalently; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. An ultrathin quasi-solid-state electrolyte membrane, characterized in that, It is formed by coating a quasi-solid electrolyte slurry; the quasi-solid electrolyte slurry includes binder and non-binder components, the non-binder components include aramid nanofibers, metal-organic framework nanoparticles, solvent and electrolyte; the thickness of the ultrathin quasi-solid electrolyte membrane is 4~10μm; The mass percentage K% of the aramid nanofibers in the non-binder component satisfies the following relationship between the length L and diameter D1 of the aramid nanofibers: K = M * (L * D1) 2 / 3 Where M is a correction coefficient of 1.1; the mass percentage X% of the metal-organic framework nanoparticles in the non-binder component and the average particle size D2 of the metal-organic framework nanoparticles satisfy: 0.3*K≤X≤D2 / 5.

2. The ultrathin quasi-solid-state electrolyte membrane according to claim 1, characterized in that, The aramid nanofibers are selected from one or more of para-aramid nanofibers or meta-aramid nanofibers. And / or, the metal-organic framework nanoparticles are one or more of UIO-66, MOF-801, MOF-808, MNNU-5, MIL-101, HKUST-1, and MOF-5.

3. The ultrathin quasi-solid-state electrolyte membrane according to claim 2, characterized in that, The aramid nanofibers are poly(p-phenylene terephthalate) nanofibers.

4. The ultrathin quasi-solid-state electrolyte membrane according to claim 2, characterized in that, The metal-organic framework nanoparticles are UIO-66.

5. The ultrathin quasi-solid-state electrolyte membrane according to claim 1 or 2, characterized in that, The aramid nanofibers have a mass percentage (K%) of 1-21% in the non-binder component.

6. The ultrathin quasi-solid-state electrolyte membrane according to claim 1, characterized in that, The metal-organic framework nanoparticles constitute 5-13% by mass in the non-binder component.

7. The ultrathin quasi-solid-state electrolyte membrane according to claim 1, characterized in that, The aramid nanofibers have a length L ranging from 4 to 10 μm and a diameter D1 ranging from 5 to 15 nm; the metal-organic framework nanoparticles have a diameter D2 ranging from 50 to 100 nm.

8. The ultrathin quasi-solid-state electrolyte membrane according to claim 1, characterized in that, The solvent is selected from one or more of NMP, DMF, and DMAc; And / or, the electrolyte includes one or more of a first electrolyte and a second electrolyte; the first electrolyte is an ionic liquid containing a metal salt; The second electrolyte is formed by dissolving a metal salt in a non-aqueous solvent.

9. The ultrathin quasi-solid-state electrolyte membrane according to claim 8, characterized in that, The electrolyte comprises 10-90% by mass in the non-binder component.

10. The method for preparing the ultrathin quasi-solid-state electrolyte membrane according to any one of claims 1-9, characterized in that, Includes the following steps: Aramid nanofibers, metal-organic framework nanoparticles, binder, solvent and electrolyte are mixed to obtain a quasi-solid electrolyte slurry; the obtained quasi-solid electrolyte slurry is coated on the cathode side of a lithium metal battery and dried to obtain an ultrathin quasi-solid electrolyte membrane.

11. The method for preparing an ultrathin quasi-solid-state electrolyte membrane according to claim 10, characterized in that, The drying process involves drying at 70-80℃ for 6-12 hours.

12. A lithium metal battery, characterized in that, Includes the ultrathin quasi-solid electrolyte membrane according to any one of claims 1-9 or the ultrathin quasi-solid electrolyte membrane prepared by the preparation method of the ultrathin quasi-solid electrolyte membrane according to claim 10 or 11.

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