Modified metal organic framework material composite polymer electrolyte as well as preparation method and application thereof
By combining modified metal-organic framework materials with polymers, open functional groups and lithium-ion transport channels are provided, solving the problem of low lithium-ion conductivity in polymer electrolytes and enabling the application of lithium batteries with high safety and high energy density.
Patent Information
- Application Number
- CN202511741199.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2026-02-17
AI Technical Summary
The low lithium-ion conductivity, poor mechanical properties, and poor flame retardant properties of existing polymer electrolytes limit the improvement of lithium battery energy density and large-scale application.
By combining modified metal-organic framework materials with polymers, organic molecules are grafted onto the organic ligands of the two-dimensional metal-organic framework materials, providing open functional groups and abundant lithium-ion transport channels, enhancing the interaction between lithium salts and polymers, and promoting lithium-ion transport.
It significantly improves lithium-ion conductivity and battery cycle life, suppresses lithium dendrite growth, and enhances battery safety and energy density.
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Figure CN121546142A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of secondary lithium batteries, specifically relating to a modified metal-organic framework composite polymer electrolyte, its preparation method, and its application. Background Technology
[0002] Polymer electrolytes, as a core component of all-solid-state or semi-solid-state batteries, have seen their technological development stem from the need to overcome the safety defects of traditional liquid electrolytes. Liquid electrolytes, due to their flammability, volatility, and the risk of short circuits caused by lithium dendrites penetrating the separator, severely limit the energy density improvement and large-scale application of lithium-ion batteries. Polymer solid-state electrolytes, by dissolving lithium salts in a polymer matrix to form a solid medium with both ion conduction and mechanical isolation functions, fundamentally eliminate the risk of electrolyte leakage. Furthermore, flexible thin-film design can suppress lithium dendrite growth, providing a key solution for high-safety, high-energy-density battery systems. However, polymer electrolytes are still hampered by the low lithium-ion conductivity, poor mechanical properties, and flame retardant properties of polymers. Therefore, improving the electrochemical performance of polymer electrolytes has become a crucial factor affecting the further development and application of lithium batteries.
[0003] Currently, the method of combining nanoparticles with polymers to enhance lithium-ion transport by utilizing the interaction between the two materials has been widely studied due to its significant effects, simplicity, and high selectivity. However, most nanofillers have few surface functional groups, or most of the functional groups are already coordinated, resulting in a small number of open functional groups and weak interactions with the polymer. Summary of the Invention
[0004] To address the above problems, this invention aims to provide a modified metal-organic framework composite polymer electrolyte, its preparation method, and its applications.
[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by this invention is as follows: In a first aspect, the present invention provides a modified metal-organic framework composite polymer electrolyte, comprising: a polymer having lithium-ion conduction capability, an organic lithium salt, and an additive, wherein the additive is a modified metal-organic framework material; the modified metal-organic framework material is formed by grafting organic molecules onto an organic ligand of a two-dimensional metal framework material.
[0006] The modified metal-organic framework material has abundant open functional groups and abundant intramolecular voids. These open functional groups can enhance the interaction between it and polymer molecules, and the abundant voids can serve as lithium-ion transport channels. At the same time, the metal sites on the outer layer of its molecules can interact with lithium salt anions, promote lithium salt dissociation, and effectively improve the electrochemical performance of the polymer electrolyte.
[0007] Furthermore, the polymer with lithium-ion conduction capability may be selected from one or both of polyvinylidene fluoride-hexafluoropropylene and polypropylene oxide.
[0008] Furthermore, the mass of the additives in the electrolyte is 1%-10% of the polymer mass.
[0009] Furthermore, the two-dimensional metal-organic framework material is obtained by ultrasonic exfoliation of layered metal-organic framework material, and no organic ligands are connected to one side of the metal site.
[0010] In a second aspect, the present invention provides a method for preparing the modified metal-organic framework composite polymer electrolyte described in the first aspect, comprising the following steps: S1: Metal salt and 1,3,6,8-tetrakis(3-amino-4-carboxyphenyl)pyrene were added to a mixed solution and dissolved. After hydrothermal treatment, the precipitate was collected and dispersed in ascorbic acid solution. After ultrasonic treatment, the precipitate was collected by centrifugation and freeze-dried to obtain nanosheets, i.e., two-dimensional metal-organic framework materials. S2: Dissolve 1,4,5,8-naphthalenetetracarboxylic anhydride and the obtained two-dimensional metal-organic framework material in acetic acid, stir the mixture and heat it to react, cool it, wash it, centrifuge it to collect and freeze dry it to obtain the modified metal-organic framework material. S3: The polymer is uniformly dissolved and dispersed in a solvent. Then, the modified metal-organic framework material and lithium salt are added to the polymer and uniformly dispersed. The slurry is then stretched and dried to obtain a solid polymer electrolyte.
[0011] Furthermore, the mixed solution in step S1 is prepared by mixing DMF, water, and dioxane in a volume ratio of 2:1:1; the concentration of the ascorbic acid solution is 100 mol / L, which is prepared by dissolving ascorbic acid in a methanol solution, wherein the methanol solution is prepared by mixing methanol and water in a volume ratio of 9:1; and the metal salt is zinc sulfate.
[0012] Furthermore, in step S1, after sonication for 10 minutes, the nanosheets are collected by centrifugation and freeze-dried; in step S2, the mixture is stirred and heated to 119°C for 16 hours.
[0013] Furthermore, the solvent in step S3 is selected from one or more of acetonitrile, N,N-dimethylformamide, and acetone; the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium dioxaborate.
[0014] Furthermore, in step S3, after the slurry is cast and leveled, it is vacuum dried at 70~100℃ to obtain a solid polymer electrolyte; the thickness of the solid polymer electrolyte is 50~200 micrometers.
[0015] In a third aspect, the present invention provides the application of the modified metal-organic framework composite polymer electrolyte as described in the first aspect or the modified metal-organic framework composite polymer electrolyte prepared by the preparation method described in the second aspect in solid-state or semi-solid-state lithium batteries.
[0016] This invention differs significantly from polymer-metal-organic framework composites disclosed in some existing literature. In this invention, organic matter is grafted into the metal-organic framework, resulting in open functional group sites. Unlike the already coordinated organic ligands in the metal-organic framework, these open functional group sites can interact better with the polymer, which is beneficial for enhancing lithium-ion conductivity. Furthermore, in the metal-organic framework material synthesized in this invention, no organic ligands are connected to one side of the outer metal sites. These metal sites can interact with lithium salt anions, inhibiting lithium-ion solvation and promoting lithium-ion transport.
[0017] Compared with the prior art, the present invention has the following significant advantages: (1) The present invention utilizes the uncoordinated functional groups in organic ligands to graft organic molecules, which can provide a large number of open functional groups, which helps the interaction between polymers and lithium ions, and promotes lithium ion transport.
[0018] (2) In the metal-organic framework material synthesized in this invention, the outer metal sites are not connected to organic ligands. These metal sites can interact with lithium salt anions, inhibit lithium ion solvation, and promote lithium ion transport.
[0019] (3) The abundant voids between molecules of the modified metal-organic framework material provided by the present invention can provide abundant lithium-ion transport channels and accelerate lithium-ion transport.
[0020] (4) The preparation process provided by the present invention can be operated using conventional heating and stirring equipment, and has the characteristics of simple operation and simple process. Attached Figure Description
[0021] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below.
[0022] Figure 1 This is a schematic diagram illustrating the synthesis of the modified metal-organic framework material in Example 1; Figure 2 Electrochemical impedance spectroscopy of polymer electrolytes with and without modified metal-organic framework materials in Example 1; Figure 3 The cycling stability of lithium-symmetric batteries with and without modified metal-organic framework materials in Example 1 is compared. Figure 4 The cycling stability of the lithium symmetric battery with polymer electrolyte containing modified metal-organic framework material in Example 2. Detailed Implementation
[0023] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be particularly noted that the following embodiments are for illustrative purposes only and do not limit the scope of the invention. Similarly, the following embodiments are only some, not all, embodiments of the present invention, and all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0024] This invention provides a modified metal-organic framework (MOF) composite polymer electrolyte, comprising: a polymer (selected as one or both of polyvinylidene fluoride-hexafluoropropylene and polypropylene oxide) with lithium-ion conductivity as the main matrix, an organolithium salt, and additives (the mass of the additives is 1%-10% of the polymer mass), wherein the additives are modified MOFs; the modified MOF is formed by grafting organic molecules onto organic ligands of a two-dimensional metal-organic framework material; wherein the two-dimensional MOF is obtained by ultrasonically exfoliating a layered MOF material, and has the characteristic that the metal site side is not connected to an organic ligand. The highly exposed metal site layer of the two-dimensional MOF can interact with the fluorine- or oxygen-containing functional groups in the polymer to promote lithium-ion decoupling and conduction, while the grafted organic molecules can strengthen the interaction with the polymer, enhancing the effect of the additives on lithium ions and improving the mechanical properties of the polymer.
[0025] The preparation method of the modified metal-organic framework composite polymer electrolyte includes the following steps: S1: Metal salts (such as zinc sulfate) and 1,3,6,8-tetra(3-amino-4-carboxyphenyl)pyrene were added to a mixed solution (DMF:water:dioxane=2:1:1) and dissolved. After hydrothermal treatment, the precipitate was collected and dispersed in an ascorbic acid solution (the ascorbic acid solution was prepared by dissolving ascorbic acid in a methanol solution, which was made by mixing methanol and water in a volume ratio of 9:1). After sonication for 10 minutes, the precipitate was collected by centrifugation and freeze-dried to obtain nanosheets, i.e., two-dimensional metal-organic framework materials.
[0026] S2: Dissolve 1,4,5,8-naphthalenetetracarboxylic anhydride and the obtained two-dimensional metal-organic framework material in acetic acid. Stir the mixture vigorously and heat it to 119°C for 16 hours. After cooling, wash, centrifuge, collect and freeze dry to obtain the modified metal-organic framework material.
[0027] S3: The polymer is uniformly dissolved and dispersed in a solvent. Then, the modified metal-organic framework material and lithium salt are added to the polymer and uniformly dispersed. The slurry is then drawn and leveled and vacuum dried at 70~100℃ to obtain a solid polymer electrolyte. The thickness of the solid polymer electrolyte is 50~200 micrometers.
[0028] The solvent can be one or more of acetonitrile, N,N-dimethylformamide, and acetone; the lithium salt can be one or more of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, and lithium dioxaborate.
[0029] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Example 1 This embodiment provides a method for preparing a modified metal-organic framework composite polymer electrolyte, the steps of which are as follows: (1) Preparation of modified metal-organic framework materials 86.3 mg of zinc sulfate and 150 mg of 1,3,6,8-tetra(3-amino-4-carboxyphenyl)pyrene were dissolved in 8 mL of a mixed solution (DMF:water:dioxane = 2:1:1), followed by hydrothermal treatment at 150 °C for 72 hours. After centrifugation and washing, the powder was dispersed in a 100 mol / L ascorbic acid solution (prepared by dissolving ascorbic acid in a methanol solution, which was a mixture of methanol and water at a volume ratio of 9:1), sonicated for 10 minutes, and then collected by centrifugation and lyophilized to obtain nanosheets, i.e., two-dimensional metal-organic framework materials. 1,4,5,8-naphthalenetetracarboxylic anhydride (268.2 mg) and the obtained metal-organic framework material (200 mg) were dissolved in 10 mL of acetic acid. Subsequently, the mixture was vigorously stirred and heated to 119 °C for 16 hours. After cooling, the resulting solid was washed with DMF, methanol, and water, then collected by centrifugation and lyophilized to obtain modified metal-organic framework materials.
[0030] Combination Figure 1 The synthetic route shown demonstrates that, in addition to the already coordinated carboxylic acid ligands, the modified metal-organic framework (MOF) materials utilize grafted organic molecules that provide open oxygen-containing functional groups. These uncoordinated oxygen-containing functional groups can interact with the polymer and lithium ions, promoting lithium-ion transport. Simultaneously, the metal side of the outer layer of the MOF molecule, lacking organic ligands, can interact with lithium ion anions, promoting lithium salt dissociation and accelerating lithium-ion transport.
[0031] (2) Preparation of composite polymer electrolyte 0.5 g of modified metal-organic framework material, 1 g of PVDF-HFP (polyvinylidene fluoride-hexafluoropropylene) and 0.2 g of polyoxypropylene were added to 10 mL of DMF and stirred to form a slurry. Then, 0.5 g of lithium salt LiTFSI was added and stirred at 55 °C for 2 hours. The resulting polymer solution was then poured into a mold and dried under vacuum at 80 °C for 12 hours to obtain the composite polymer electrolyte.
[0032] Performance testing To facilitate comparison of the performance differences between composite polymer electrolytes prepared with modified metal-organic framework materials and polymers without modified metal-organic framework materials.
[0033] The present invention uses the same preparation steps as in Example 1, but omits the step of adding modified metal-organic framework materials to obtain a polymer electrolyte without the addition, which serves as a control group.
[0034] Impedance spectroscopy was performed on the polymer electrolytes obtained in Example 1 and the control group, respectively. The results (e.g.) were obtained from the tests. Figure 2 As shown, the polymer electrolyte with the added additive (modified metal-organic framework material) exhibits lower electrochemical impedance and a significantly improved lithium-ion conductivity, calculated to be 1.5 mS / cm, far exceeding the 0.96 mS / cm conductivity of the polymer electrolyte without the modified metal-organic framework material. This is because the uncoordinated oxygen-containing functional groups of the modified metal-organic framework material can interact with the polymer and lithium ions, promoting lithium-ion transport. Simultaneously, the lack of organic ligands on the metal side of the outer layer of the metal-organic framework molecule allows it to interact with lithium-ion anions, promoting lithium salt dissociation and accelerating lithium-ion transport.
[0035] Further assembly of lithium-symmetric cells was conducted to test the battery's cycle stability. Figure 3 The results show that the polymer electrolyte with modified metal-organic framework material has significantly improved battery performance, achieving a battery efficiency of 1 mA / cm². 2 The battery achieved stable cycling for over 900 hours, significantly exceeding the cycle life of the unmodified polymer electrolyte (comparative sample) (only 250 hours). Furthermore, the overpotential of the polymer electrolyte with the modified metal-organic framework was considerably lower than that of the unmodified polymer electrolyte. This indicates that the modified metal-organic framework composite polymer electrolyte possesses strong lithium-ion conductivity, effectively suppressing lithium dendrite formation and growth, and extending cycle life.
[0036] Example 2 This embodiment provides a method for preparing a modified metal-organic framework composite polymer electrolyte, which is largely the same as that in Example 1, except that the amount of modified metal-organic framework material added in this embodiment is 0.1g.
[0037] Performance testing Assemble lithium-symmetric batteries and test their cycle stability.
[0038] Tested (as attached) Figure 4 As shown in the figure, the polymer electrolyte with the added modified metal-organic framework exhibits significantly improved performance. This polymer electrolyte demonstrates a lower cyclic overpotential and a cycle life exceeding 800 hours compared to the unmodified polymer electrolyte.
[0039] In summary, this invention utilizes the abundant open functional groups and rich intramolecular voids of modified metal-organic framework materials to enhance their interaction with polymer molecules. At the same time, the metal sites on the outer layer of the intermolecular layer can interact with lithium salt anions (facilitating lithium salt dissociation) and provide abundant lithium ion transport channels, effectively improving the electrochemical performance of polymer electrolytes. In terms of processing, the preparation process provided by this invention is simple to operate and suitable for industrial production.
[0040] The above description is only a part of the embodiments of the present invention and does not limit the scope of protection of the present invention. Any equivalent device or equivalent process transformation made based on the content of the present invention specification and drawings, or direct or indirect application in other related technical fields, are similarly included within the patent protection scope of the present invention.
Claims
1. A modified metal organic framework material composite polymer electrolyte, characterized in that, The application relates to a modified metal organic framework material composite polymer electrolyte and a preparation method thereof. The modified metal organic framework material is a modified metal organic framework material obtained by grafting organic molecules on the organic ligand of a two-dimensional metal organic framework material. The polymer with lithium ion conduction capacity is selected from one or both of polyvinylidene fluoride-hexafluoropropylene and polypropylene oxide.
2. The modified metal organic framework material composite polymer electrolyte of claim 1, wherein, The mass of the additive in the electrolyte is 1%-10% of the mass of the polymer.
3. The modified metal organic framework material composite polymer electrolyte of claim 1, wherein, The two-dimensional metal organic framework material is obtained by ultrasonic exfoliation of a layered metal organic framework material, and the metal site on one side of the layered metal organic framework material is not connected with an organic ligand.
4. The modified metal organic framework material composite polymer electrolyte of claim 1, wherein, The application further discloses a preparation method of the modified metal organic framework material composite polymer electrolyte.
5. A method of preparing a modified metal organic framework material composite polymer electrolyte according to any one of claims 1 to 4, characterized in that, S1: metal salt and 1,3,6,8-tetrakis(3-amino-4-carboxylphenyl)pyrene are added into a mixed solution for dissolution, a precipitate is collected after hydrothermal treatment and is dispersed in an ascorbic acid solution, and nanosheets are obtained after centrifugal collection and freeze-drying, namely the two-dimensional metal organic framework material; S2: 1,4,5,8-naphthalene tetracarboxylic anhydride and the obtained two-dimensional metal organic framework material are dissolved in acetic acid, the mixture is stirred and heated for reaction, and the modified metal organic framework material is obtained after washing, centrifugal collection and freeze-drying; S3: the high-molecular polymer is uniformly dissolved and dispersed in a solvent, then the modified metal organic framework material and a lithium salt are added into the polymer for uniform dispersion, and the solid-state polymer electrolyte is obtained after the slurry is cast and dried. The mixed solution in S1 is prepared from DMF, water and dioxane in a volume ratio of 2:1:1; the ascorbic acid solution has a concentration of 100 mol / L, is prepared by dissolving ascorbic acid in a methanol solution, and the methanol solution is prepared by mixing methanol and water in a volume ratio of 9:1; and the metal salt is selected from zinc sulfate.
6. The method of claim 5, wherein the modified metal-organic framework composite polymer electrolyte is prepared by the steps of: (a) providing a metal-organic framework; (b) modifying the metal-organic framework with a functional group; (c) providing a polymer electrolyte; and (d) mixing the modified metal-organic framework and the polymer electrolyte. The nanosheets are obtained after centrifugal collection and freeze-drying after ultrasonic treatment for 10 minutes in S1; and the mixture is stirred and heated to 119 DEG C for 16 hours in S2.
7. The method for preparing the modified metal-organic framework composite polymer electrolyte according to claim 5, characterized in that, The solvent in S3 is selected from one or more of acetonitrile, N, N-dimethylformamide and acetone; and the lithium salt is selected from one or more of lithium hexafluorophosphate, lithium bisfluorosulfonylimide and lithium bis(oxalato)borate.
8. The method of claim 5, wherein the modified metal-organic framework composite polymer electrolyte is prepared by the steps of: (a) providing a metal-organic framework; (b) modifying the metal-organic framework with a functional group; (c) providing a polymer electrolyte; and (d) mixing the modified metal-organic framework and the polymer electrolyte. The solid-state polymer electrolyte is obtained after the slurry is cast and dried in a vacuum at 70-100 DEG C, and the thickness of the solid-state polymer electrolyte is 50-200 microns.
9. The method of claim 5, wherein the modified metal-organic framework composite polymer electrolyte is prepared by the steps of: (a) providing a metal-organic framework; (b) modifying the metal-organic framework with a functional group; (c) providing a polymer electrolyte; and (d) mixing the modified metal-organic framework and the polymer electrolyte.
10. The modified metal organic framework material composite polymer electrolyte prepared by the method in any one of claims 1-4 or the method in any one of claims 5-9 is applied to a solid-state or semi-solid-state lithium battery.