Metal organic gel material for lithium metal battery negative electrode interface layer and preparation method thereof

Abstract

This invention belongs to the field of metal-organic gel materials technology, and discloses a metal-organic gel material for the interface layer of lithium metal battery anodes and its preparation method. The material uses a cerium-based metal-organic gel as its core, is prepared through a heating reaction, and an artificial interface layer is constructed on the surface of the lithium metal anode using a spin-coating method. This gel material possesses abundant metal open sites and a three-dimensional network microstructure, effectively adsorbing anions and solvent molecules, promoting lithium-ion dissociation and desolvation, while simultaneously accommodating deposited lithium metal. Symmetrical batteries based on this interface layer exhibit excellent cycle stability, operating stably for over 1000 hours with an overpotential below 20 mV, and effectively suppressing lithium dendrite growth. This invention provides a reliable material basis and technical solution for constructing high-energy-density, high-safety lithium metal batteries.

Description

Technical Field

[0001] This application relates to the field of materials synthesis technology, specifically to a metal-organic gel material for the interface layer of a lithium metal battery anode and its preparation method. Background Technology

[0002] Lithium metal anodes are known for their ultra-high theoretical specific capacity (3860 mAh g). -1 Lithium metal anodes, with their high ionic conductivity and extremely low electrochemical potential, are considered key materials for achieving high-energy-density batteries. However, their practical application is limited by problems such as uncontrolled lithium dendrite growth, severe interfacial side reactions, and significant volume changes during cycling, leading to low coulombic efficiency, short cycle life, and serious safety hazards. Traditional solid-state electrolyte interphase (SEI) films often have poor mechanical properties and non-uniform structures, making it difficult to effectively suppress dendrite penetration. Therefore, developing novel interfacial protective layers that simultaneously achieve high ionic conductivity, good mechanical flexibility, and excellent electrochemical stability has become an urgent need for the practical application of lithium metal anodes.

[0003] Metal-organic gels (MOGs) are three-dimensional porous gel materials formed by the self-assembly of metal ions and organic ligands through coordination interactions. They possess high specific surface area, tunable chemical composition, and a unique dynamic gel network. Their porous structure facilitates rapid ion transport, while the flexibility of the gel itself can adapt to the volume deformation of the electrode during cycling. In recent years, MOGs have shown potential in catalysis, sensing, and other fields, but their application in lithium metal battery interface layers is still limited. By rationally selecting the metal center and organic ligands, the pore size, mechanical strength, and affinity for lithium ions of MOGs can be precisely controlled, thus providing a novel material platform for constructing stable and adaptive artificial interface layers.

[0004] Current lithium metal anode protective layer materials (such as inorganic ceramics and polymer composites) often struggle to simultaneously achieve high ionic conductivity, interfacial compatibility, and ease of fabrication. Metal-organic gels (MOGs), due to their designable structure, porous flexibility, and interfacial self-adaptive properties, hold promise for overcoming these limitations, achieving uniform lithium-ion flow distribution, suppressing dendrite growth, and improving interfacial stability. However, the design of MOG materials specifically addressing the interfacial protection requirements of lithium metal battery anodes and their scalable fabrication methods remain scarce. Therefore, developing a metal-organic gel material for lithium metal anode interfacial layers and establishing a corresponding simple and controllable fabrication process is of significant scientific and engineering application value for promoting the development of high-safety, long-cycle lithium metal batteries. Summary of the Invention

[0005] To address the aforementioned problems, the present invention aims to provide a cerium-based metal-organic gel material and its controllable preparation method. This material forms an artificial interface layer on the surface of a lithium metal anode using a spin-coating method. Due to the incomplete coordination of the metal centers in this material, it possesses abundant open metal sites. Furthermore, the material exhibits a three-dimensional network structure, which can effectively regulate lithium-ion flow, suppress lithium dendrite growth, and promote lithium-ion desolvation and uniform deposition, thereby achieving high safety and long-life lithium metal cycling. Therefore, this interface layer possesses excellent electrochemical stability and interfacial compatibility, demonstrating significant application potential in next-generation high-energy-density batteries.

[0006] The objective of this invention can be achieved through the following technical solutions.

[0007] This invention provides a method for preparing a metal-organic gel material for the interface layer of a lithium metal battery anode, which is synthesized in one step using a monobasic inorganic strong base as a nucleation regulator. The specific steps are as follows: (1) Preparation of solution A: Under vigorous stirring, the nucleation regulator solution is added to the (NH4)2Ce(NO3)6 aqueous solution to form solution A; (2) Preparation of solution B: Dissolve terephthalic acid or its derivative in an organic solvent to form solution B; wherein: the terephthalic acid derivative is terephthalic acid having amino, hydroxyl, carboxyl or halogen substituents or disubstituents; (3) Mix solution A and solution B and react under heating conditions. After the reaction is completed, the solid and liquid are separated to obtain a solid sample. Then wash, remove impurities and dry in sequence to obtain cerium-based metal organogel material Ce-MOG.

[0008] In this invention, in step (1), the nucleation regulator is lithium hydroxide, sodium hydroxide, or potassium hydroxide, and the molar concentration of the nucleation regulator solution is 0.5-2 mol L. -1 The molar concentration of the (NH4)2Ce(NO3)6 aqueous solution is 0.5-1 mol / L; the molar ratio of the nucleating regulator to (NH4)2Ce(NO3)6 is 1:1.5-1:2.

[0009] In this invention, in step (2), the organic solvent is N,N'-dimethylformamide DMF, and the molar concentration of solution B is 0.2-0.3 mol / L.

[0010] In this invention, the molar ratio of (NH4)2Ce(NO3)6 to terephthalic acid or a terephthalic acid derivative is 0.95:1-1.05:1.

[0011] In this invention, in step (3), the reaction temperature is 95-105℃ and the reaction time is 20-40 minutes; filtration or centrifugation is used for solid-liquid separation; the solid sample is washed several times with DMF and acetone respectively, and then soaked in ethanol overnight to remove impurities; vacuum drying is used, and the drying temperature is 60-80℃.

[0012] The present invention also provides a metal-organic gel material for use as an interface layer of a lithium metal battery anode, prepared by the above preparation method.

[0013] Furthermore, this invention also provides an application of the above-mentioned metal-organic gel material in constructing the interface layer of a lithium metal battery anode. In application, the lithium metal battery anode interface layer is prepared using a slurry drop-coating method; the specific steps are as follows: First, the metal-organic gel material Ce-MOG and PVDF were uniformly mixed in N,N-dimethylacetamide DMAc at a mass ratio of 3:2. The above slurry was then drop-coated onto the surface of lithium foil, and then vacuum dried in a glove box to remove the solvent.

[0014] The present invention has developed a simple synthetic strategy for synthesizing cerium-based metal-organic gels (Ce-MOGs) for use as the interface layer of lithium metal battery anodes. Compared with the prior art, the advantages of the present invention are as follows: (1) The metal-organic gel material provided by the present invention can effectively protect the negative electrode of lithium metal battery.

[0015] (2) The metal-organic gel material provided by the present invention is simple to synthesize and can be completed in one step. Attached Figure Description

[0016] Figure 1 This is a scanning electron microscope image of Ce-MOG, the metal-organic gel material in Example 1.

[0017] Figure 2 This is the Fourier transform infrared spectrum of Ce-MOG, the metal-organic gel material in Example 1.

[0018] Figure 3 This is a schematic diagram of the structure of a metal-organic gel and the preparation method of the interface layer.

[0019] Figure 4 This is a comparison of lithium stripping / deposition cycling curves for symmetric cells assembled using lithium foils with and without Ce-MOG interface layers.

[0020] Figure 5 This is a comparison chart of long-cycle curves of lithium iron phosphate full cells assembled using lithium foil with and without a Ce-MOG interface layer. Detailed Implementation

[0021] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0022] The synthesis method of the cerium-based metal organogel material employs a one-step synthesis using a monobasic inorganic strong base as a nucleation regulator. The specific steps are as follows: Example 1: Synthesis of Ce-MOG, a metal-organic gel material (1) Preparation of solution A: Under vigorous stirring, add 2 mL of NaOH solution (1.0 mol L) -1 Slowly add to 6 mL of (NH4)2Ce(NO3)6 (0.533 mol L) -1 In an aqueous solution, solution A is formed; (2) Preparation of solution B: Dissolve 0.5310 g of 1,4-phthalic acid (H2BDC, 3.20 mmol) in 12 mL of DMF to form solution B; (3) Solutions A and B were mixed in a glass vial and reacted at 100 °C for 30 minutes. After the reaction was completed, a solid sample was obtained by centrifugation at 8000 rpm for 3 minutes. The solid sample was then washed three times with DMF and acetone, and then soaked in ethanol overnight to remove impurities. Finally, it was vacuum dried at 70 °C to prepare the cerium-based metal organogel material Ce-MOG.

[0023] By scanning electron microscopy ( Figure 1 , Figure 2 The morphology and structure of the metal frame material were confirmed.

[0024] like Figure 1 As shown, Ce-MOG possesses a microstructure of a three-dimensional interconnected network. In the FTIR spectra of Ce-MOG and H2BDC ( Figure 2 The characteristic peaks (1683-1720 cm⁻¹) corresponding to the non-ionized groups of the carboxylic acid linker -1 The ) disappearance, and new bands for the asymmetric and symmetric stretching vibrations of the carboxyl functional group appear at approximately 1558 and 1384 cm⁻¹, respectively. -1 The locations further indicate that the Ce ion is coordinated with the carboxylate ligand. (671 and 748 cm⁻¹) -1 The peaks at the point can be attributed to the OH bending vibration and the Ce-O mode, respectively, indicating the coordination of the carboxyl functional group with the inorganic node and the successful formation of Ce-MOG.

[0025] I. Lithium Metal Symmetric Cell Testing like Figure 3 As shown, the preparation method of lithium foil with Ce-MOG interface layer (Ce-MOG@Li) for assembling symmetrical batteries is as follows: Lithium foil with Ce-MOG interface layer is prepared by slurry drop coating. First, Ce-MOG and PVDF are uniformly mixed in 2 mL of N,N-dimethylacetamide (DMAc) at a mass ratio of 3:2. The slurry is then drop-coated onto the surface of the lithium foil, and then vacuum dried in a glove box for 48 hours to remove the solvent.

[0026] Symmetric cells were assembled using lithium foils with and without Ce-MOG interface layers to test lithium stripping / deposition cycle stability.

[0027] like Figure 4 As shown, the symmetric cell based on the Ce-MOG interface layer exhibits excellent cycle stability, operating stably for over 1000 hours with an overpotential below 20 mV. However, the overpotential of the symmetric cell without the Ce-MOG interface layer continuously increases during cycling and becomes unstable after approximately 80 hours.

[0028] II. Lithium Metal Full Battery Testing The preparation method of Ce-MOG@Li is the same as above. The preparation method of lithium iron phosphate cathode is as follows: LiFePO4 powder, conductive carbon black and PVDF powder are uniformly mixed in a certain amount of N-methylpyrrolidone (NMP) at a mass ratio of 8:1:1 and ground to form a slurry. The slurry is coated onto aluminum foil, dried under vacuum at 80°C and cut into round pieces with a diameter of 12 mm.

[0029] Full cells were assembled by pairing lithium foils with and without Ce-MOG interface layers with lithium iron phosphate cathodes to test capacity utilization and cycle stability.

[0030] like Figure 5 As shown, the lithium iron phosphate full cell based on the Ce-MOG interface layer exhibits excellent cycle stability, running stably for 500 cycles with stable coulombic efficiency. However, the full cell without the Ce-MOG interface layer shows a significant decrease in specific capacity and unstable coulombic efficiency.

[0031] Example 2: Synthesis of Ce-MOG, a metal-organic gel material (1) Preparation of solution A: Under vigorous stirring, add 1 mL of KOH solution (2.0 mol L) -1 Slowly add to 6 mL of (NH4)2Ce(NO3)6 (0.533 mol L) -1 In an aqueous solution, solution A is formed; (2) Preparation of solution B: Dissolve 0.5310 g of 1,4-phthalic acid (H2BDC, 3.20 mmol) in 12 mL of DMF to form solution B; (3) Solutions A and B were mixed in a glass vial and reacted at 100 °C for 30 minutes. After the reaction was completed, a solid sample was obtained by centrifugation at 8000 rpm for 3 minutes. The solid sample was then washed three times with DMF and acetone, and then soaked in ethanol overnight to remove impurities. Finally, it was vacuum dried at 70 °C to prepare the cerium-based metal organogel material Ce-MOG.

[0032] Example 3: Synthesis of Ce-MOG, a metal-organic gel material (1) Preparation of solution A: Under vigorous stirring, add 1 mL of LiOH solution (2.0 mol L) -1 Slowly add to 6 mL of (NH4)2Ce(NO3)6 (0.533 mol L) -1 In an aqueous solution, solution A is formed; (2) Preparation of solution B: Dissolve 0.5310 g of 1,4-phthalic acid (H2BDC, 3.20 mmol) in 12 mL of DMF to form solution B; (3) Solutions A and B were mixed in a glass vial and reacted at 100 °C for 30 minutes. After the reaction was completed, a solid sample was obtained by centrifugation at 8000 rpm for 3 minutes. The solid sample was then washed three times with DMF and acetone, and then soaked in ethanol overnight to remove impurities. Finally, it was vacuum dried at 70 °C to prepare the cerium-based metal organogel material Ce-MOG.

[0033] Example 4: Synthesis of Ce-MOG-NH2, a metal-organic gel material (1) Preparation of solution A: Under vigorous stirring, add 1 mL of NaOH solution (2.0 mol L) -1 Slowly add to 6 mL of (NH4)2Ce(NO3)6 (0.533 mol L) -1 In an aqueous solution, solution A is formed; (2) Preparation of solution B: Dissolve 0.5792 g of 2-aminoterephthalic acid (3.20 mmol) in 12 mL of DMF to form solution B; (3) Solutions A and B were mixed in a glass vial and reacted at 100 °C for 30 minutes. After the reaction, a solid sample was obtained by centrifugation at 8000 rpm for 3 minutes. The solid sample was then washed three times with DMF and acetone, and then soaked in ethanol overnight to remove impurities. Finally, it was vacuum dried at 70 °C to prepare the cerium-based metal organogel material Ce-MOG-NH2.

[0034] Example 5: Synthesis of Ce-MOG-OH, a metal-organic gel material (1) Preparation of solution A: Under vigorous stirring, add 1 mL of NaOH solution (2.0 mol L) -1 Slowly add to 6 mL of (NH4)2Ce(NO3)6 (0.533 mol L) -1 In an aqueous solution, solution A is formed; (2) Preparation of solution B: Dissolve 0.5824 g of 2-hydroxyterephthalic acid (3.20 mmol) in 12 mL of DMF to form solution B; (3) Solutions A and B were mixed in a glass vial and reacted at 100 °C for 30 minutes. After the reaction was completed, a solid sample was obtained by centrifugation at 8000 rpm for 3 minutes. The solid sample was then washed three times with DMF and acetone respectively, and then soaked in ethanol overnight to remove impurities. Finally, it was vacuum dried at 70 °C to prepare the cerium-based metal organogel material Ce-MOG-OH.

[0035] Example 6: Synthesis of Ce-MOG-COOH, a metal-organic gel material (1) Preparation of solution A: Under vigorous stirring, add 1 mL of NaOH solution (2.0 mol L) -1 Slowly add to 6 mL of (NH4)2Ce(NO3)6 (0.533 mol L) -1 In an aqueous solution, solution A is formed; (2) Preparation of solution B: Dissolve 0.6720 g of 1,2,4-benzenetricarboxylic acid (3.20 mmol) in 12 mL of DMF to form solution B; (3) Solutions A and B were mixed in a glass vial and reacted at 100 °C for 30 minutes. After the reaction, a solid sample was obtained by centrifugation at 8000 rpm for 3 minutes. The solid sample was then washed three times with DMF and acetone, and then soaked in ethanol overnight to remove impurities. Finally, it was vacuum dried at 70 °C to prepare the cerium-based metal organogel material Ce-MOG-COOH.

[0036] Example 7: Synthesis of the metal-organic gel material Ce-MOG-2OH (1) Preparation of solution A: Under vigorous stirring, add 1 mL of NaOH solution (2.0 mol L) -1 Slowly add to 6 mL of (NH4)2Ce(NO3)6 (0.533 mol L) -1 In an aqueous solution, solution A is formed; (2) Preparation of solution B: Dissolve 0.6336 g of 2,5-dihydroxyterephthalic acid (3.20 mmol) in 12 mL of DMF to form solution B; (3) Solutions A and B were mixed in a glass vial and reacted at 100 °C for 30 minutes. After the reaction was completed, a solid sample was obtained by centrifugation at 8000 rpm for 3 minutes. The solid sample was then washed three times with DMF and acetone respectively, and then soaked in ethanol overnight to remove impurities. Finally, it was vacuum dried at 70 °C to prepare the cerium-based metal organogel material Ce-MOG-2OH.

[0037] Example 8: Synthesis of Ce-MOG-2COOH, a metal-organic gel material (1) Preparation of solution A: Under vigorous stirring, add 1 mL of NaOH solution (2.0 mol L) -1 Slowly add to 6 mL of (NH4)2Ce(NO3)6 (0.533 mol L) -1 In an aqueous solution, solution A is formed; (2) Preparation of solution B: Dissolve 0.8182 g of 1,2,4,5-benzenetetracarboxylic acid (3.20 mmol) in 12 mL of DMF to form solution B; (3) Solutions A and B were mixed in a glass vial and reacted at 100 °C for 30 minutes. After the reaction, a solid sample was obtained by centrifugation at 8000 rpm for 3 minutes. The solid sample was then washed three times with DMF and acetone, and then soaked in ethanol overnight to remove impurities. Finally, it was vacuum dried at 70 °C to prepare the cerium-based metal organogel material Ce-MOG-2COOH.

Claims

1. A method for preparing a metal-organic gel material for the interface layer of a lithium metal battery anode, comprising a one-step synthesis using a monobasic inorganic strong base as a nucleation regulator, the specific steps of which are as follows: (1) Preparation of solution A: Under stirring, the nucleation regulator solution is added to the (NH4)2Ce(NO3)6 aqueous solution to form solution A; (2) Preparation of solution B: Dissolve terephthalic acid or its derivatives in an organic solvent to form solution B; wherein: Terephthalic acid derivatives are terephthalic acids having amino, hydroxy, carboxyl, or halogen substituents or disubstituents; (3) Mix solution A and solution B in a glass vial and react under heating conditions. After the reaction is complete, separate the solid and liquid to obtain a solid sample. Then wash, remove impurities and dry in sequence to obtain cerium-based metal organogel material Ce-MOG.

2. The preparation method according to claim 1, characterized in that, In step (1), the nucleation regulator is lithium hydroxide, sodium hydroxide, or potassium hydroxide, and the molar concentration of the nucleation regulator solution is 0.5-2 mol L. -1 The molar concentration of the aqueous solution of (NH4)2Ce(NO3)6 is 0.5-1 mol / L; the molar ratio of nucleating regulator to (NH4)2Ce(NO3)6 is 1:1.5-1:

2.

3. The preparation method according to claim 1, characterized in that, In step (2), the organic solvent is N,N'-dimethylformamide (DMF), and the molar concentration of solution B is 0.2-0.3 mol / L.

4. The preparation method according to claim 1, characterized in that, The molar ratio of (NH4)2Ce(NO3)6 to terephthalic acid or its derivatives is 0.95:1 to 1.05:

1.

5. The preparation method according to claim 1, characterized in that, In step (3), the reaction temperature is 95-105℃ and the reaction time is 20-40 minutes; filtration or centrifugation is used for solid-liquid separation; the solid sample is washed several times with DMF and acetone, and then soaked in ethanol overnight to remove impurities; vacuum drying is used and the drying temperature is 60-80℃.

6. A metal-organic gel material for use as an interface layer of a lithium metal battery anode, prepared by the method according to any one of claims 1-5.

7. The application of the metal-organic gel material according to claim 6 in constructing the interface layer of the negative electrode of a lithium metal battery.

8. The application according to claim 7, characterized in that, In application, the negative electrode interface layer of lithium metal batteries is prepared by slurry drop coating method.

9. The application according to claim 8, characterized in that, The specific application method is as follows: First, the metal-organic gel material Ce-MOG and PVDF were uniformly mixed in N,N-dimethylacetamide DMAc at a mass ratio of 3:

2. The above slurry was then drop-coated onto the surface of lithium foil, and then vacuum dried in a glove box to remove the solvent.

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