A core-shell MOF, preparation method and application

Abstract

The present invention discloses a core-shell MOF, a preparation method and an application. A core-shell MOF has a core of UiO-66-NH2 and a shell of UiO-67. Since UiO-66-NH2@67 has a high specific surface area and large pore size, this structure provides more active sites and shorter transport paths, which is beneficial to the rapid transport of lithium ions, thus significantly improving the ionic conductivity. The added filler can significantly improve the electrochemical performance of the polymer-based all-solid-state electrolyte, including improving the cycle stability and inhibiting the growth of lithium dendrites. The improvement of these properties can be attributed to the synergistic effect of the components in the composite material, where the MOF structure helps to homogenize the deposition of lithium ions and prevent irregular growth on the electrode surface.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithium ion batteries, and in particular relates to a core-shell MOF, a preparation method and an application thereof. Background Art

[0002] To date, all-solid-state lithium-ion batteries have become a source of increasing attention due to their stable electrochemical performance and high energy density, and have also proven to be an attractive alternative for future generation lithium batteries. Metal-organic frameworks (MOFs), composed of metal ion clusters and organic ligands, can serve as ideal fillers for electrolyte membranes due to their rich porosity and large specific surface area. Nanostructured MOFs can capture anions through Lewis acid-base interactions, providing unique channels for lithium ion migration, thereby acting as lithium ion conductors.

[0003] For example, the invention patent application with publication number CN117712475A discloses an asymmetric composite solid electrolyte membrane and its preparation method and application, in which a composite electrolyte colloid A layer and a composite electrolyte colloid B layer based on MOF material are respectively formed on both sides of a porous support material with high porosity. In this application, the stability to lithium is further enhanced by introducing MOF materials. In addition, the introduction of a high-porosity support material in the composite solid electrolyte enhances the mechanical strength of the membrane while ensuring the flexibility of the electrolyte membrane, thereby reducing the risk of battery short circuit.

[0004] For another example, the invention patent application with publication number CN117728014A discloses a gel polymer solid electrolyte with high ionic conductivity and a preparation method. The chemical formula of the gel polymer solid electrolyte is H-Co / Zn-ZIF / PVDF-HFP, wherein the nanofiller H-Co / Zn-ZIF has a "cage" type dual MOF structure, the polymer PVDF-HFP has a continuous and through-going microporous channel, and the H-Co / Zn-ZIF is in the microporous channel of the PVDF-HFP.

[0005] However, the interfacial compatibility between MOFs and electrodes in the above-mentioned prior art is still a problem to be solved urgently.

[0006] UiO-66-NH2 (CAS No.: 1260119-00-3) is an amino-functionalized metal organic framework, and the coordinated metal can be zirconium, chromium, iron, aluminum, etc.

[0007] UiO-67 (CAS No.: 1072413-83-2) is also a metal organic framework material, coordinated with metal Zr and ligand 4,4'-biphenyldicarboxylic acid. Summary of the invention

[0008] In view of the above-mentioned deficiencies in the prior art, the present invention provides a core-shell MOF, a preparation method and an application. The core-shell MOF material is based on UiO-66-NH2 as the core and UiO-67 as the shell. UiO-67 has the characteristics of high specific surface area and large pore size, which improves the ion conductivity but loses the ion migration number. Compared with UiO-67, UiO-66-NH2 has a smaller pore size, and as a core structure, it can limit the migration of large ions and further promote the transport of lithium ions.

[0009] The present invention first provides a core-shell MOF, wherein the core is UiO-66-NH2 and the shell is UiO-67.

[0010] The present invention further provides a method for preparing the core-shell MOF, comprising the following steps:

[0011] (1) 1-aminoanthraquinone-5-sulfonic acid and biphenyl dicarboxylic acid are dispersed in a solvent;

[0012] (2) adding ZrCl4, catalyst acetic acid and polyvinyl pyrrolidone to the solution obtained in step (1) and dispersing them evenly;

[0013] (3) adding UiO-66-NH2 to the dispersion obtained in step (2), wherein the metal ion in UiO-66-NH2 is Zr, and subjecting the UiO-67 to the generation of UiO-67 on the surface of UiO-66-NH2 by hydrothermal reaction;

[0014] (4) The product obtained in step (3) is vacuum activated to obtain UiO-66-NH2@67 with a core-shell structure.

[0015] Preferably, the addition ratio of UiO-66-NH2, 1-aminoanthraquinone-5-sulfonic acid, biphenyl dicarboxylic acid, and N,N-dimethylformamide is 113.8~124.1 g: 113.1~230.3 g: 181.6~242.23 g: 730~877 mL.

[0016] Preferably, the addition ratio of ZrCl4, acetic acid and polyvinyl pyrrolidone is 442.7~489.3g:1500~2400mL:345.3g~691g.

[0017] Preferably, the temperature of the hydrothermal reaction in step (3) is 100°C to 140°C, and the reaction time is 20 to 30 hours.

[0018] Preferably, the temperature of vacuum activation in step (4) is 120°C to 150°C, and the time is 10 to 14 hours.

[0019] The present invention further provides the use of the core-shell MOF in preparing a composite electrolyte for an all-solid-state lithium metal battery.

[0020] The present invention also provides a method for preparing a core-shell MOF all-solid-state lithium metal battery composite electrolyte membrane, comprising the following steps: dispersing each component in an organic solvent to obtain a mixed slurry, coating the mixed slurry on a substrate, and drying to remove the organic solvent to obtain the core-shell MOF all-solid-state lithium metal battery composite electrolyte membrane;

[0021] The components include LiTFSI, PVDF-HFP, hexafluorobutyl acrylate, ((Z)-1-propenyl)-boric acid pinacol ester, and sodium ethoxide, and the addition ratio of each component is 86.1-143.5: 22.5-202.5: 0.1652-0.236: 2.52-7.08: 20.415-40.83;

[0022] The components also include the core-shell MOF, which accounts for 10% to 30% of the total mass.

[0023] The invention also discloses a core-shell MOF all-solid-state lithium metal battery composite electrolyte membrane prepared by the preparation method.

[0024] Reaction mechanism of the present invention:

[0025] 1. Synthesis of UiO-66-NH2@67:

[0026] The complex of UiO-67 generated between biphenyl dicarboxylic acid (BPDC) and ZrCl4 is used as a precursor. UiO-66-NH2 is used as a core particle, and a UiO-67 precursor is generated on its outer surface.

[0027] A metal complex is generated between 1-aminoanthraquinone-5-sulfonic acid and ZrCl4, which also enters the precursor to introduce anthraquinone functional groups; acetic acid is used as a catalyst; and polyvinyl pyrrolidone is used as a template.

[0028] The precursor undergoes further hydrothermal reaction to generate UiO-67 on the surface of UiO-66-NH2, obtaining UiO-66-NH2@67 with a core-shell structure.

[0029] 2. Introduce hexafluorobutyl acrylate and ((Z)-1-propenyl)-boric acid pinacol ester to carry out amino-propenyl addition reaction, where the amino group is located on the UiO-66-NH2@67 structure, and the propenyl group comes from hexafluorobutyl acrylate and ((Z)-1-propenyl)-boric acid pinacol ester. This step makes the composite material have functional groups such as hexafluoro, borate, and anthraquinone.

[0030] Compared with the prior art, the present invention has the following advantages:

[0031] 1. Improve ion conductivity: Due to the high specific surface area and large pore size of UiO-66-NH2@67, the structure provides more active sites and shorter transmission paths, which is conducive to the rapid transmission of lithium ions, thereby significantly improving ion conductivity.

[0032] 2. Improved electrochemical performance: The added filler can significantly improve the electrochemical performance of polymer-based all-solid-state electrolytes, including improving cycle stability and inhibiting the growth of lithium dendrites. These performance improvements can be attributed to the synergistic effect of the components in the composite material, among which the MOF structure helps to homogenize the deposition of lithium ions and prevent irregular growth on the electrode surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is the discharge capacity test result at 0.1C. DETAILED DESCRIPTION

[0034] Example 1

[0035] A method for preparing a core-shell MOF all-solid-state lithium metal battery composite electrolyte comprises the following steps:

[0036] (1) A core-shell MOF (UiO-66-NH2@67) was synthesized by a simple solvothermal method.

[0037] 172.7 g of 1-aminoanthraquinone-5-sulfonic acid and 205.9 mg of biphenyldicarboxylic acid (BPDC, 4,4'-biphenyldicarboxylic acid) were dissolved in 803 mL of N,N-dimethylformamide (DMF, as solvent) and ultrasonically dispersed for 15 min. 442.7 g of ZrCl4 (Zr as the metal ion for coordination), 1500 mL of acetic acid (CH3COOH) and 518 g of polyvinylpyrrolidone (PVP) were added to the solution respectively and ultrasonically dispersed for 15 min.

[0038] The obtained uniform solution was transferred to a reactor, 118.9 g of UiO-66-NH2 (wherein the metal is Zr. CAS: 1260119-00-3) was added, and heated at 120°C for 24 h. UiO-67 was generated on the surface of UiO-66-NH2 by hydrothermal reaction. The obtained suspension was centrifuged at 10,000 rpm for about 5 min, and washed 6 times with a mixture of 84.8 mL of DMF and 40 mL of alcohol to remove acetic acid; the material was activated at 130°C in vacuum (0.3 mTorr (about 0.04 Pa)) for 12 hours before use. During the vacuum activation process, the core-shell MOF voids will open to obtain the core-shell structure of UiO-66-NH2@67, with the core being UiO-66-NH2 and the shell being UiO-67.

[0039] (2) Then, 114.8 g LiTFSI (lithium bis(trifluoromethanesulfonyl imide), 90 g PVDF-HFP (poly(vinylidene fluoride-co-hexafluoropropylene)), 0.1652 g hexafluorobutyl acrylate, 2.52 g ((Z)-1-propenyl)-boronic acid pinacol ester (CAS No.: 83947-59-5), and 30.6 g sodium ethoxide were dispersed in a mixed solution of 1450 mL acetone and 1089 mL N,N-dimethylacetamide (DMAc), and then magnetically stirred at 70 °C for 3 h until no obvious solid was visible to obtain a mixed slurry. 20% of the total mass (referring to the total mass after adding UiO-66-NH2@67) of UiO-66-NH2@67 was added to the above mixed slurry and stirred at 50 °C overnight. Finally, the slurry was evenly coated on a polytetrafluoroethylene plate with a spatula and vacuum dried. The dried electrolyte membrane was transferred to a glove box and cut into discs with a diameter of 18 mm for further use.

[0040] (3) Assembled into a solid-state battery, the test results show that its lithium ion migration number is 0.68 and its 0.1C discharge capacity is 170.2 mAh / g ( Figure 1 ).

[0041] Example 2

[0042] A method for a core-shell MOF all-solid-state lithium metal battery composite electrolyte, the remaining steps are the same as those in Example 1, and the difference from Example 1 is:

[0043] (1) The masses of BPDC, 1-aminoanthraquinone-5-sulfonic acid and N,N-dimethylformamide (DMF) are 181.6 g, 115.1 g and 730 mL respectively. The masses of ZrCl4, acetic acid (CH3COOH) and polyvinylpyrrolidone (PVP) are 442.7 g, 1200 mL and 345.3 g respectively.

[0044] The mass of UiO-66-NH2 is 113.8 g. The reaction was carried out at 100°C for 20 h. The material was washed 6 times with a mixture of 73.09 mL of DMF and 23 mL of alcohol. The material was activated in vacuum at 0.3 mTorr and 120°C for 10 h before use.

[0045] (2) Then, 143.5 g LiTFSI, 202.5 g PVDF-HFP, 0.236 g hexafluorobutyl acrylate, 5.04 g ((Z)-1-propenyl)-boronic acid pinacol ester, and 40.83 g sodium ethoxide were dispersed in a mixed solution of 1742 mL acetone and 1306 mL N,N-dimethylacetamide (DMAc). The mass of UiO-66-NH2@67 accounted for 10% of the total mass of the mixed solution. The pellets were cut into discs with a diameter of 16 mm.

[0046] (3) Assembled into a solid-state battery, the lithium ion migration number was tested to be 0.46, and the discharge capacity at 0.1C was 167mAh / g ( Figure 1 ).

[0047] Example 3

[0048] A method for a core-shell MOF all-solid-state lithium metal battery composite electrolyte, the remaining steps are the same as those in Example 1, and the difference from Example 1 is:

[0049] (1) The masses of BPDC, 1-aminoanthraquinone-5-sulfonic acid and N,N-dimethylformamide (DMF) are 242.23 g, 230.3 g and 877 mL respectively. The masses of ZrCl4, acetic acid (CH3COOH) and polyvinylpyrrolidone (PVP) are 489.3 g, 2400 mL and 691 g respectively.

[0050] The mass of UiO-66-NH2 is 124.1 g. The reaction was carried out at 140°C for 30 h. The mixture was washed 6 times with 87.7 mL of DMF and 46 mL of alcohol. The material was activated in vacuum at 0.3 mTorr and 150°C for 14 h before use.

[0051] (2) Then, 86.1 g LiTFSI, 22.5 g PVDF-HFP, 0.236 g hexafluorobutyl acrylate, 7.08 g ((Z)-1-propenyl)-boronic acid pinacol ester, and 20.415 g sodium ethoxide were dispersed in a mixed solution of 1161 mL acetone and 871 mL N,N-dimethylacetamide (DMAc). The mass of UiO-66-NH2@67 was 30% of the total mass of the mixed solution. The pellets were cut into discs with a diameter of 19 mm.

[0052] (3) Assembled into a solid-state battery, the lithium ion migration number was tested to be 0.41, and the discharge capacity at 0.1C was 158.8 mAh / g ( Figure 1 ).

[0053] Comparative Example 1

[0054] The remaining steps are the same as those in Example 1, except that:

[0055] (1) The mass of BPDC and N,N-dimethylformamide (DMF) is 205.9 g and 803 mL respectively. The mass of ZrCl4, acetic acid (CH3COOH) and polyvinylpyrrolidone (PVP) is 442 g, 1500 mL and 518 g respectively. React at 140℃ for 30 h. Wash with a mixture of 84.8 mL of DMF and 40 mL of alcohol for 6 times. The material is used after vacuum activation at 130℃ for 12 hours.

[0056] (2) Then, 114.8 g LiTFSI and 90 g PVDF-HFP were dispersed in a mixed solution of 1450 mL acetone and 1089 mL N,N-dimethylacetamide (DMAc) and then magnetically stirred at 70 °C for 3 h until no obvious solid was visible. 20% of the total mass of UiO-66-NH2@67 was added to the slurry and stirred at 50 °C overnight. Finally, the slurry was evenly coated on a polytetrafluoroethylene plate with a spatula and vacuum dried. The dried electrolyte membrane was transferred to a glove box and cut into discs with a diameter of 18 mm for further use.

[0057] (3) Assembled into a solid-state battery, the lithium ion migration number was tested to be 0.35, and the discharge capacity at 0.1C was 143.1 mAh / g ( Figure 1 ).

[0058] The results of Examples 1 to 3 and Comparative Example 1 show that the core-shell MOF structure of the present invention provides more active sites and shorter transmission paths, which is beneficial to the rapid transmission of lithium ions, thereby significantly improving the ionic conductivity.

Claims

1. A method for preparing a core-shell MOF all-solid-state lithium metal battery composite electrolyte membrane, characterized in that: The following steps are involved: Dispersing each component in an organic solvent to obtain a mixed slurry, coating the mixed slurry on a substrate, and drying to remove the organic solvent to obtain the core-shell MOF all-solid-state lithium metal battery composite electrolyte membrane; The components include LiTFSI, PVDF-HFP, hexafluorobutyl acrylate, ((Z)-1-propenyl)-boric acid pinacol ester, and sodium ethoxide, and the addition ratio of each component is 86.1-143.5: 22.5-202.5: 0.1652-0.236: 2.52-7.08: 20.415-40.83; The components also include core-shell MOF, which accounts for 10% to 30% of the total mass; The core-shell MOF has a core of UiO-66-NH2 and an outer shell of UiO-67; The preparation method of the core-shell MOF comprises the following steps: (1) 1-aminoanthraquinone-5-sulfonic acid and biphenyl dicarboxylic acid are dispersed in a solvent; (2) adding ZrCl4, catalyst acetic acid and polyvinyl pyrrolidone to the solution obtained in step (1) and dispersing them evenly; (3) adding UiO-66-NH2 to the dispersion obtained in step (2), wherein the metal ion in UiO-66-NH2 is Zr, and subjecting the UiO-67 to the generation of UiO-67 on the surface of UiO-66-NH2 by hydrothermal reaction; (4) The product obtained in step (3) is vacuum activated to obtain UiO-66-NH2@67 with a core-shell structure; The addition ratio of UiO-66-NH2, 1-aminoanthraquinone-5-sulfonic acid, biphenyl dicarboxylic acid, and N,N-dimethylformamide is 113.8~124.1 g: 113.1~230.3 g: 181.6~242.23 g: 730~877 mL; The addition ratio of ZrCl4, acetic acid and polyvinyl pyrrolidone is 442.7~489.3g:1500~2400mL:345.3g~691g.

2. The method for preparing the core-shell MOF all-solid-state lithium metal battery composite electrolyte membrane according to claim 1, characterized in that: The temperature of the hydrothermal reaction in step (3) is 100°C to 140°C, and the reaction time is 20 to 30 hours.

3. The method for preparing the core-shell MOF all-solid-state lithium metal battery composite electrolyte membrane according to claim 1, characterized in that: The temperature of vacuum activation in step (4) is 120°C to 150°C, and the time is 10 to 14 hours.

4. A core-shell MOF all-solid-state lithium metal battery composite electrolyte membrane prepared by the preparation method according to any one of claims 1 to 3.

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