Heterometal-doped MOF materials for lithium metal battery quasi-solid-state electrolytes and preparation method and application thereof

Abstract

The application discloses a kind of for lithium metal battery quasi-solid electrolyte hetero-metal doped MOF material and its preparation method and application.The material takes cerium-based metal-organic framework as matrix, it contains cerium ion and hetero-metal ion in its metal node, is prepared by being mixed and heated after being dissolved together with organic ligand solution with the source of cerium and the source of hetero-metal.The hetero-metal doped MOF material has abundant hetero-metal Lewis acidic sites, can effectively anchor anion, promote lithium ion dissociation and transport, with its constructed quasi-solid electrolyte membrane room temperature lithium ion conductivity reaches 1.06×10 ‑4 S cm ‑1 , lithium ion migration number reaches 0.86, and lithium metal full battery can be stably circulated 500 times.The application provides material basis for constructing high ionic conductivity, high safety quasi-solid lithium metal battery.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal battery electrolyte materials technology, specifically relating to a heterometallic doped MOF material for quasi-solid-state electrolytes of lithium metal batteries, its preparation method and application. Background Technology

[0002] Quasi-solid-state electrolytes combine the non-flammability and high mechanical strength of solid-state electrolytes with the high ionic conductivity of liquid electrolytes, and are considered one of the key materials for breaking through the energy density bottleneck of traditional lithium-ion batteries. Metal-organic frameworks (MOFs) are crystalline porous materials formed by the self-assembly of metal nodes and organic ligands through coordination bonds. Their regular nanopores facilitate selective ion transport, and their tunable framework structure can adapt to the recognition and enrichment of guest molecules, attracting widespread attention in the field of electrochemical energy storage in recent years. Among them, cerium-based MOFs, represented by Ce-UiO-66, are highly regarded for their high chemical stability and tunable metal valence state (Ce). 3+ / Ce 4+ It has unique application potential.

[0003] However, current MOF-based quasi-solid-state electrolyte materials still suffer from the following shortcomings: the limited Lewis acid sites in the single-metal node MOF framework result in insufficient anchoring ability for lithium salt anions, leading to low lithium-ion dissociation efficiency; simultaneously, the polarization characteristics of ion transport channels within the pores are difficult to precisely control, making it difficult to meet practical application requirements for lithium-ion conductivity and transport number at room temperature. Existing methods often require complex post-modification processes to introduce functional groups or alter the pore environment, resulting in cumbersome synthesis steps and limited control precision. Summary of the Invention

[0004] The purpose of this invention is to address the aforementioned problems in the prior art by providing a heterometallic doped MOF material for quasi-solid-state electrolytes in lithium metal batteries, along with its preparation method and application. By introducing heterometallic ions into the metal nodes of a cerium-based metal-organic framework, the strong Lewis acidity provided by the heterometallic sites anchors lithium salt anions, promoting lithium ion dissociation and transport, thereby constructing a quasi-solid-state electrolyte membrane with high ionic conductivity and high mobility number.

[0005] To achieve the above-mentioned application objectives, the present invention adopts the following technical solution: a heterometallic doped MOF material for quasi-solid electrolyte of lithium metal battery, wherein the heterometallic doped MOF material uses cerium-based metal-organic framework as matrix, and the metal nodes of the cerium-based metal-organic framework contain cerium ions and heterometallic ions.

[0006] Furthermore, the heterometal ions are selected from Al 3+ Sn4+ and Ti 4+ At least one of them.

[0007] Furthermore, the molar ratio of cerium ions to heterometallic ions is 1:0.1 to 1:0.3.

[0008] Furthermore, the cerium-based metal-organic framework has a Ce-UiO-66 type topology.

[0009] Furthermore, the organic ligand of the cerium-based metal-organic framework is a terephthalic acid ligand with a substituent selected from at least one of amino, hydroxyl, carboxyl, and halogen groups.

[0010] A method for preparing the above-mentioned heterometallic doped MOF material includes the following steps:

[0011] The cerium source and the heterometal source are dissolved in a first solvent to obtain a first solution; The organic ligand is dissolved in a second solvent to obtain a second solution; The first solution and the second solution were mixed and subjected to a coordination reaction under heating conditions. After the reaction was completed, the mixture was separated into solid and liquid components, washed and dried to obtain a heterometallic doped MOF material.

[0012] Furthermore, the cerium source is (NH4)2Ce(NO3)6; the heterometal source is a heterometallic chloride selected from at least one of aluminum trichloride, tin tetrachloride and titanium tetrachloride; the first solvent is water; and the second solvent is N,N'-dimethylformamide.

[0013] Furthermore, the heating temperature is 95°C to 105°C, and the reaction time is 20 to 40 minutes; the drying is vacuum drying at a temperature of 60°C to 80°C.

[0014] Furthermore, the quasi-solid electrolyte membrane comprises the aforementioned heterometallic doped MOF material, a binder, and an electrolyte adsorbed in the heterometallic doped MOF material.

[0015] Furthermore, the mass ratio of the dissimilar metal-doped MOF material to the binder is 9:1; the binder is polytetrafluoroethylene; and the electrolyte is a propylene carbonate solution containing lithium bis(trifluoromethanesulfonyl)imide.

[0016] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention introduces heterogeneous metal ions (such as Al) into the metal nodes of Ce-UiO type MOFs. 3+ Sn 4+ Ti 4+ The heterometallic sites have stronger Lewis acidity than Ce sites, which can effectively anchor lithium salt anions (such as TFSI). -This process promotes the dissociation of lithium ions from ion pairs, allowing them to migrate freely along the MOF channels. The quasi-solid-state electrolyte membrane based on this material achieves a room-temperature lithium-ion conductivity of 1.06 × 10⁻⁶. -4 S cm -1 Compared to the undoped Ce-UiO system (0.38 × 10⁻⁶), -4 S cm -1 It increased by about 2.8 times.

[0017] 2. The strong anchoring effect of heterometallic sites on anions effectively suppresses anion migration, reduces concentration polarization, and increases the lithium-ion transference number from 0.41 in the undoped system to 0.86, an increase of more than 100%. A high transference number helps reduce concentration polarization within the battery, improving rate performance and cycle stability.

[0018] 3. This invention uses heterometallic chloride as a dopant source, and the synthesis of MOF and heterometallic doping can be completed in one step under mild conditions of 95~105°C and 20~40 minutes. There is no need for complicated post-modification steps or high temperature and high pressure conditions. The process is simple, low cost, and conducive to large-scale preparation.

[0019] 4. The lithium iron phosphate (LFP) / lithium metal full cell assembled based on the quasi-solid-state electrolyte membrane of the heterometallic doped MOF material can cycle stably for more than 500 cycles with stable coulombic efficiency, demonstrating excellent cycle stability and interface compatibility, and providing a reliable material solution for high-safety and long-life lithium metal batteries. Attached Figure Description

[0020] Figure 1 The image shows the X-ray diffraction (XRD) pattern of the heterometallic doped cerium-based MOF material Ce-UiO-Al prepared in Example 1, with a comparison of the XRD patterns of Ce-UiO-Al and the simulated Ce-UiO-66.

[0021] Figure 2 This is a scanning electron microscope (SEM) image of the heterometallic doped cerium-based MOF material Ce-UiO-Al prepared in Example 1.

[0022] Figure 3 The images show the transmission electron microscope (TEM) spectra and corresponding elemental distribution spectra of the heterometallic doped cerium-based MOF material Ce-UiO-Al prepared in Example 1, which illustrate the distribution of Ce, Al, C, and O elements.

[0023] Figure 4 This is the X-ray photoelectron spectroscopy (XPS) spectrum of the heterometallic doped cerium-based MOF material Ce-UiO-Al prepared in Example 1, wherein... Figure 4 'a' represents the XPS full spectrum. Figure 4b is the fine spectrum of Al 2p.

[0024] Figure 5 This is a schematic diagram illustrating the structure of the heterometallic doped cerium-based MOF material Ce-UiO-M and the process for preparing a quasi-solid-state electrolyte membrane.

[0025] Figure 6 This is a comparison of the electrochemical impedance spectroscopy (EIS) spectra of Al-doped and undoped Ce-UiO reference solid electrolyte membranes and the calculated lithium-ion conductivity.

[0026] Figure 7 These are electrochemical impedance spectroscopy (EIS) spectra of Al-doped and undoped Ce-UiO reference solid electrolyte membranes before and after polarization. The inset plot is a time-current curve used to calculate the lithium-ion transference number.

[0027] Figure 8 This is a long-cycle curve of a lithium iron phosphate (LiFePO4) / LiMetal metal full cell using a Ce-UiO-Al reference solid electrolyte membrane. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0029] In the description of this invention, the English abbreviations used have clear meanings known in the art: MOF stands for Metal-Organic Framework; DMF stands for N,N'-Dimethylformamide; PTFE stands for Polytetrafluoroethylene; PC stands for Propylene Carbonate; LiTFSI stands for Lithium Bis(trifluoromethanesulfonyl)imide; XRD stands for X-ray diffraction; SEM stands for Scanning Electron Microscopy; TEM stands for Transmission Electron Microscopy; XPS stands for X-ray Photoelectron Spectroscopy; EIS stands for Electrochemical Impedance Spectroscopy.

[0030] This invention provides a heterometallic doped MOF material for quasi-solid-state electrolytes in lithium metal batteries. The material uses a cerium-based metal-organic framework (MOF) as its matrix, and the metal nodes of the cerium-based MOF contain cerium ions and heterometallic ions. The heterometallic ions are strongly Lewis acidic and are introduced into the MOF framework by substituting some coordination sites of the cerium nodes, forming a synergistic effect of bimetallic nodes. These heterometallic sites provide stronger Lewis acidity than single cerium sites, thereby effectively anchoring lithium salt anions and promoting lithium-ion dissociation and transport.

[0031] As a preferred embodiment, the heterometal ions can be selected from Al. 3+ Sn 4+ and Ti 4+ At least one of the following; the molar ratio of cerium ions to heterometallic ions is preferably 1:0.1 to 1:0.3; the cerium-based metal-organic framework is preferably a Ce-UiO-66 type topology; the organic ligand of the cerium-based metal-organic framework is preferably a terephthalic acid ligand with a substituent selected from at least one of amino, hydroxyl, carboxyl and halogen groups.

[0032] This invention also provides a method for preparing the above-mentioned heterometallic doped MOF material, comprising the following steps: dissolving a cerium source and a heterometallic source in a first solvent to obtain a first solution; dissolving an organic ligand in a second solvent to obtain a second solution; mixing the first solution and the second solution, and carrying out a coordination reaction under heating conditions; after the reaction is completed, performing solid-liquid separation, washing, and drying to obtain the heterometallic doped MOF material. The cerium source is preferably (NH4)2Ce(NO3)6; the heterometallic source is preferably a heterometallic chloride; the first solvent is preferably water; and the second solvent is preferably DMF.

[0033] In the above method, the preferred heating temperature is 95°C to 105°C, and the preferred reaction time is 20 to 40 minutes. In the washing step, the mixture can be washed several times with DMF and acetone respectively, followed by soaking in acetone or ethanol overnight to remove impurities. Drying is preferably performed using vacuum drying at a temperature of 60°C to 80°C.

[0034] This invention also provides a quasi-solid-state electrolyte membrane for lithium metal batteries, comprising the aforementioned heterometallic doped MOF material, a binder, and an electrolyte adsorbed in the heterometallic doped MOF material. The binder is preferably PTFE, and the electrolyte is preferably a PC solution containing LiTFSI. The mass ratio of the heterometallic doped MOF material to the binder is preferably 9:1.

[0035] The implementation of the present invention will be described in detail below through specific embodiments.

[0036] Example 1: Preparation of Ce-UiO-Al In this embodiment, the corresponding heterometallic ion is Al³. + The organic ligand is a specific realization of unsubstituted terephthalic acid, and the corresponding preparation method is also specific.

[0037] (1) Preparation of the first solution: Under stirring conditions, 1.7 g (3.1 mmol) (NH4)2Ce(NO3)6 and 0.10 g (0.77 mmol) AlCl3 were dissolved together in 7.2 mL of deionized water to form the first solution. The Ce content in this solution... 4+ With Al3+ The molar ratio is 1:0.25.

[0038] (2) Preparation of the second solution: Dissolve 0.648 g (3.9 mmol) of 1,4-terephthalic acid (H2BDC) in 22.5 mL of DMF to form the second solution.

[0039] (3) Coordination reaction and post-treatment: The first solution was added dropwise to the second solution and mixed in a glass vial. The mixture was sonicated for 10 minutes to ensure uniform dispersion. The reaction was then heated at 100°C for 30 minutes. After the reaction, the solid product was collected by centrifugation at 8000 rpm for 3 minutes. The solid product was washed three times each with DMF and acetone, and then soaked in acetone overnight to remove residual unreacted ligands and solvent impurities. Finally, it was vacuum dried at 70°C to obtain the Al-doped cerium-based MOF material Ce-UiO-Al.

[0040] The obtained Ce-UiO-Al was characterized in terms of structure and morphology. For example... Figure 1 As shown in the XRD pattern, the diffraction peak positions of Ce-UiO-Al are consistent with those of the simulated Ce-UiO-66 XRD pattern, indicating that Al... 3+ Doping did not alter the basic crystal structure of the MOF; the material retained its Ce-UiO-66 topology. For example... Figure 2 As shown, the SEM images reveal that Ce-UiO-Al exhibits a uniform spherical morphology. Figure 3 As shown, the TEM images and corresponding elemental distribution maps reveal that Ce, Al, C, and O are uniformly distributed in the material, confirming that Al... 3+ It has been successfully incorporated into the MOF framework. For example... Figure 4 As shown in part a, the signal peak of Al appears in the full XPS spectrum; as Figure 4 As shown in section b, a distinct Al 2p peak appears at approximately 74.78 eV in the Al 2p fine spectrum, further confirming the successful Al doping.

[0041] Example 2: Preparation of Ce-UiO-Sn In this embodiment, the corresponding heterometallic ion is Sn. 4+ The specific implementation is different from Example 1, except for the different heterogeneous metal source.

[0042] When preparing the first solution, 1.7 g (3.07 mmol) of (NH4)2Ce(NO3)6 and 0.20 g (0.77 mmol) of SnCl4 were dissolved together in 7.2 mL of water. 4+ With Sn 4+The molar ratio was 1:0.25. The subsequent preparation of the second solution, reaction, washing, and drying steps were exactly the same as in Example 1, yielding the Sn-doped cerium-based MOF material Ce-UiO-Sn.

[0043] Example 3: Preparation of Ce-UiO-Ti In this embodiment, the corresponding heterometallic ion is Ti. 4+ The specific implementation is different from Example 1, except for the different heterogeneous metal source.

[0044] When preparing the first solution, 1.7 g (3.07 mmol) of (NH4)2Ce(NO3)6 and 0.15 g (0.77 mmol) of TiCl4 were dissolved together in 7.2 mL of water. 4+ With Ti 4+ The molar ratio was 1:0.25. Subsequent steps were exactly the same as in Example 1, resulting in the Ti-doped cerium-based MOF material Ce-UiO-Ti.

[0045] Example 4: Preparation of Ce-UiO-NH2-Al This embodiment corresponds to the specific implementation of replacing the organic ligand with an amino group. The only difference from Example 1 is that the organic ligand used is 2-aminoterephthalic acid.

[0046] In preparing the second solution, 0.706 g (3.9 mmol) of 2-aminoterephthalic acid was dissolved in 22.5 mL of DMF. The preparation of the first solution and subsequent steps were exactly the same as in Example 1, yielding the amino-substituted Al-doped cerium-based MOF material Ce-UiO-NH2-Al.

[0047] Example 5: Preparation of Ce-UiO-OH-Al This embodiment demonstrates the specific implementation of replacing the organic ligand with a hydroxyl group. The only difference from Embodiment 1 is that the organic ligand used is 2-hydroxyterephthalic acid.

[0048] In preparing the second solution, 0.710 g (3.9 mmol) of 2-hydroxyterephthalic acid was dissolved in 22.5 mL of DMF. The remaining steps were exactly the same as in Example 1, yielding the hydroxylated Al-doped cerium-based MOF material Ce-UiO-OH-Al.

[0049] Example 6: Preparation of Ce-UiO-COOH-Al This embodiment corresponds to the specific implementation of the organic ligand being substituted with a carboxyl group. The only difference from Embodiment 1 is that the organic ligand used is 1,2,4-phenyltricarboxylic acid.

[0050] In preparing the second solution, 0.820 g (3.9 mmol) of 1,2,4-benzenetricarboxylic acid was dissolved in 22.5 mL of DMF. The remaining steps were exactly the same as in Example 1, yielding the carboxyl-substituted Al-doped cerium-based MOF material Ce-UiO-COOH-Al.

[0051] Example 7: Preparation of Ce-UiO-2OH-Al This embodiment corresponds to the specific implementation of replacing the organic ligand with a dihydroxyl group. The only difference from Example 1 is that the organic ligand used is 2,5-dihydroxyterephthalic acid.

[0052] In preparing the second solution, 0.773 g (3.9 mmol) of 2,5-dihydroxyterephthalic acid was dissolved in 22.5 mL of DMF. The remaining steps were exactly the same as in Example 1, yielding the dihydroxy-substituted Al-doped cerium-based MOF material Ce-UiO-2OH-Al.

[0053] Example 8: Preparation of Ce-UiO-2COOH-Al This embodiment corresponds to the specific implementation of the organic ligand being substituted with a dicarboxyl group. The only difference from Example 1 is that the organic ligand is 1,2,4,5-benzenetetracarboxylic acid.

[0054] In preparing the second solution, 0.991 g (3.9 mmol) of 1,2,4,5-benzenetetracarboxylic acid was dissolved in 22.5 mL of DMF. The remaining steps were exactly the same as in Example 1, yielding the dicarboxyl-substituted Al-doped cerium-based MOF material Ce-UiO-2COOH-Al.

[0055] Example 9: Preparation and Electrochemical Performance Testing of Quasi-Solid-State Electrolyte Membranes This embodiment uses the Ce-UiO-Al material prepared in Example 1 as an example for illustration.

[0056] I. Preparation of Quasi-Solid-State Electrolyte Membranes The preparation process of quasi-solid electrolyte membranes is as follows: Figure 5 As shown, the specific steps are as follows: (1) Mix Ce-UiO-Al material and PTFE binder in a mass ratio of 9:1 in a small amount of deionized water to fully disperse them and form a plastic mixture.

[0057] (2) The mixture is rolled into a film of uniform thickness by a roller press.

[0058] (3) Place the roll-formed film in a vacuum oven and perform a first drying treatment at 100°C for 12 hours to completely remove moisture and residual solvent.

[0059] (4) The dried film was immersed in a 1 mol / L LiTFSI PC solution for 3 days to allow the three-dimensional porous structure of the MOF material to fully adsorb the electrolyte.

[0060] (5) Take out the soaked film and dry it in a vacuum oven at 150°C for 48 hours to remove some of the solvent but retain an appropriate amount of electrolyte in the MOF channels to obtain a quasi-solid electrolyte membrane.

[0061] II. Lithium-ion transport performance test The Ce-UiO-Al quasi-solid electrolyte membrane prepared in this embodiment and the undoped Ce-UiO reference solid electrolyte membrane prepared using the same process were compared and tested.

[0062] (1) Lithium-ion conductivity test The quasi-solid-state electrolyte membrane was assembled into a stainless steel||stainless steel (SS||SS) symmetric cell. Its bulk resistance was measured using EIS technology, and the lithium-ion conductivity was calculated according to the following formula:

[0063] in, For the thickness of the membrane, Bulk resistance, This refers to the electrode area. For example... Figure 6 As shown, the room temperature lithium-ion conductivity calculated based on the Ce-UiO-Al quasi-solid-state electrolyte membrane is... Significantly higher than the undoped Ce-UiO reference solid electrolyte membrane. This is due to Al 3+ The site provides stronger Lewis acidity, effectively anchoring TFSI. - Anions promote Li + It dissociates from the ion pair and is rapidly transported along the MOF channels.

[0064] (2) Lithium-ion transference number test A quasi-solid-state electrolyte membrane was assembled into a lithium||lithium(Li||Li) symmetric cell for testing. A small polarization voltage was applied. Record the steady-state current before and after polarization. and and the interfacial impedance before and after polarization and Calculate the lithium-ion transference number using the following formula. :

[0065] like Figure 7 As shown, Figure 7Part a shows that the lithium-ion transference number of the Ce-UiO-Al quasi-solid-state electrolyte membrane is 0.86, which is much higher than that of the standard electrolyte membrane. Figure 7 The undoped Ce-UiO reference solid electrolyte membrane in part b has a lithium-ion transference number of 0.41. This high transference number indicates that the anions are effectively anchored by the Lewis acidic sites of the heterometallic material, which helps suppress concentration polarization.

[0066] III. Lithium Metal Full Cell Testing LiFePO4 powder, conductive carbon black, and PVDF powder were uniformly mixed in an 8:1:1 mass ratio with an appropriate amount of N-methylpyrrolidone (NMP) and ground to form a uniform slurry. The slurry was coated onto an aluminum foil current collector, dried under vacuum at 80°C, and then cut into 12 mm diameter discs to serve as the positive electrode.

[0067] Using lithium foil as the negative electrode and the aforementioned Ce-UiO-Al quasi-solid-state electrolyte membrane as the electrolyte, a coin cell was assembled with a lithium iron phosphate positive electrode and subjected to constant current charge-discharge cycle testing. Figure 8 As shown, the lithium iron phosphate || lithium metal full cell based on Ce-UiO-Al quasi-solid-state electrolyte membrane exhibits excellent cycle stability, can run stably for 500 cycles, and the coulombic efficiency remains stable throughout the cycle.

[0068] The test results of the above embodiments show that the heterometallic doped cerium-based MOF material (Ce-UiO-M) provided by the present invention, as a functional component of the quasi-solid-state electrolyte, can effectively improve lithium-ion conductivity and lithium-ion transference number by anchoring anions through the Lewis acid sites of heterometals and promoting lithium-ion dissociation and transport. At the same time, it can regulate lithium-ion flow and suppress lithium dendrite growth by utilizing the three-dimensional ordered pore structure. This improves the cycle stability and rate performance of lithium metal batteries and has important application potential in next-generation high-energy-density quasi-solid-state lithium metal batteries.

[0069] The parts of this invention not described in detail are prior art, therefore they are not described in detail here.

[0070] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0071] Although this document uses a considerable amount of technical terminology, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would contradict the spirit of the invention.

[0072] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes made to their shape or structure, any technical solution that is the same as or similar to this invention falls within the protection scope of this invention.

Claims

1. A heterometallic doped MOF material for use as a quasi-solid-state electrolyte in lithium metal batteries, characterized in that, The heterometal-doped MOF material uses a cerium-based metal-organic framework as a matrix, and the metal nodes of the cerium-based metal-organic framework contain cerium ions and heterometal ions.

2. The heterometal-doped MOF material according to claim 1, characterized in that, The heterometal ions are selected from Al. 3 + Sn 4+ and Ti 4+ At least one of them.

3. The heterometallic doped MOF material according to claim 1 or 2, characterized in that, The molar ratio of the cerium ions to the heterometallic ions is from 1:0.1 to 1:0.

3.

4. The heterometal-doped MOF material according to claim 1, characterized in that, The cerium-based metal-organic framework has a Ce-UiO-66 type topology.

5. The heterometal-doped MOF material according to claim 1, characterized in that, The organic ligand of the cerium-based metal-organic framework is a terephthalic acid ligand with substituents selected from at least one of amino, hydroxyl, carboxyl and halogen groups.

6. A method for preparing the heterometallic doped MOF material according to any one of claims 1 to 5, characterized in that, Includes the following steps: The cerium source and the heterometal source are dissolved in a first solvent to obtain a first solution; The organic ligand is dissolved in a second solvent to obtain a second solution; The first solution and the second solution are mixed and subjected to a coordination reaction under heating conditions. After the reaction is completed, the mixture is separated into solid and liquid components, washed and dried to obtain the heterometallic doped MOF material.

7. The preparation method according to claim 6, characterized in that, The cerium source is (NH4)2Ce(NO3)6; the heterometal source is a heterometallic chloride selected from at least one of aluminum trichloride, tin tetrachloride and titanium tetrachloride; the first solvent is water; the second solvent is N,N'-dimethylformamide.

8. The preparation method according to claim 6, characterized in that, The heating reaction is carried out at a temperature of 95°C to 105°C for a reaction time of 20 to 40 minutes; the drying is carried out under vacuum at a temperature of 60°C to 80°C.

9. A quasi-solid-state electrolyte membrane for lithium metal batteries, characterized in that, The quasi-solid electrolyte membrane comprises any one of the heterometallic doped MOF materials according to claims 1 to 5, a binder, and an electrolyte adsorbed in the heterometallic doped MOF material.

10. The quasi-solid-state electrolyte membrane for lithium metal batteries according to claim 9, characterized in that, The mass ratio of the heterometal-doped MOF material to the binder is 9:1; the binder is polytetrafluoroethylene; and the electrolyte is a propylene carbonate solution containing lithium bis(trifluoromethanesulfonyl)imide.

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