A lithium sulfonate covalent organic framework solid-state electrolyte, a solid-state battery and a preparation method
By using lithium sulfonate covalent organic framework solid electrolyte and in-situ polymerization synthesis process, the problems of complex solid-state battery preparation and low-temperature capacity decay have been solved, realizing the preparation and application of efficient and low-cost solid-state batteries.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- YUNNAN UNIV
- Filing Date
- 2026-04-09
- Publication Date
- 2026-05-29
AI Technical Summary
Existing solid-state battery manufacturing processes are complex and costly, suffer from severe capacity decay at low temperatures, and require high investment in traditional solid-state battery equipment with long production cycles.
A stable lithium sulfonate covalent organic framework solid electrolyte is prepared by combining a covalent organic framework (COF) substrate with lithium sulfonate groups through an in-situ polymerization synthesis process. This simplifies the preparation process, reduces production costs, and allows for the assembly of battery cells using standardized interfaces to form a solid-state battery.
It achieves high room temperature conductivity, excellent lithium-ion transference number, and stable low-temperature performance, reducing production costs, adapting to various energy storage scenarios, meeting different needs, and improving battery safety and charge transfer efficiency.
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Figure CN122118065A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of electrochemical technology, specifically relating to a lithium sulfonate covalent organic framework solid electrolyte, a solid battery, and a preparation method thereof. Background Technology
[0002] In consumer electronics, energy storage power stations, and other fields, safety accidents caused by liquid batteries due to electrolyte leakage, thermal runaway, and other issues are commonplace. The market demand for highly safe and environmentally friendly energy storage products continues to surge, and solid-state batteries, with their electrolyte-free, high-temperature resistant, and non-flammable / explosive characteristics, are becoming the inevitable trend to replace traditional liquid batteries. However, the manufacturing process of traditional solid-state batteries is complex, requiring multiple steps such as slurry coating, high-temperature sintering, and vacuum encapsulation. This not only results in a long production cycle but also requires expensive production equipment, such as vacuum sintering furnaces and high-precision coating machines, leading to high equipment investment costs. Furthermore, existing solid-state batteries suffer from significant capacity decay at low temperatures. Summary of the Invention
[0003] In order to overcome the shortcomings of existing technologies and solve the technical problems of complex manufacturing processes, high costs, and poor low-temperature capacity stability of existing solid-state batteries, this invention provides a lithium sulfonate covalent organic framework solid electrolyte, a solid-state battery, and a preparation method thereof.
[0004] The present invention is achieved through the following technical solutions.
[0005] The present invention provides a lithium sulfonate covalent organic framework solid electrolyte, comprising a covalent organic framework (COF) substrate and lithium sulfonate groups bonded to the COF substrate.
[0006] Furthermore, the COF substrate is an amino-functionalized COF.
[0007] Furthermore, a method for preparing a lithium sulfonate covalent organic framework solid electrolyte includes the following steps: S1. Preparation of COF substrate; S2. The COF substrate was mixed with lithium sulfonate groups and vacuum dried at 80°C and -0.095MPa for 24 h to obtain the COF precursor. S3. Add the COF precursor, catalyst, and deionized water to a four-necked flask at a solid-liquid ratio of 1:5. Place the four-necked flask in a constant temperature water bath and control the temperature gradient by maintaining it at 60°C for 1 hour, raising it to 70°C for 2 hours, and raising it to 80°C for 2 hours. Stir the reaction at a rate of 150 r / min for 4-6 hours. Filter and dry the mixture using a vacuum filter to obtain lithium sulfonate covalent organic framework solid electrolyte.
[0008] Furthermore, the catalyst in step S3 is 2.5% triethylamine.
[0009] Furthermore, a solid-state battery containing a lithium sulfonate covalent organic framework solid electrolyte includes several battery cells, wherein the battery cells include a positive electrode, a first composite film, a COF-lithium sulfonate gel film, a second composite film, and a negative electrode, which are stacked sequentially from bottom to top.
[0010] Furthermore, the positive electrode includes LiFePO4 and lithium sulfonate covalent organic framework solid electrolyte, the first composite film and the second composite film have the same structure, the first composite film and the second composite film use polyethylene material as base film, and the surface is grafted with functional groups that can introduce proton and lithium ion conduction ability and load lithium conduction sites; the negative electrode includes lithium metal foil and COF protective layer.
[0011] Furthermore, the COF-lithium sulfonate gel membrane is prepared using a lithium sulfonate covalent organic framework solid electrolyte, and the preparation method is as follows: A. Prepare and pretreat lithium sulfonate covalent organic framework solid electrolyte, polyethylene oxide, lithium bis(trifluoromethanesulfonyl)imide and additives in quantities of 20-30 parts, 60-70 parts, 10-15 parts and 1-3 parts by weight. B. Add 60-70 parts of polyethylene oxide and 10-15 parts of lithium bis(trifluoromethanesulfonyl)imide to anhydrous solvent and stir magnetically in an oil bath at 60°C for 12 hours until completely dissolved to form a transparent and homogeneous solution; then add 20-30 parts of lithium sulfonate covalent organic framework solid electrolyte, stir for 6 hours and ultrasonically disperse for 30 minutes, and continue to add 1-3 parts of additive and ultrasonically disperse for 15 minutes. C. Place the slurry mixed in step B in a vacuum drying oven and evacuate it at 60°C for 30 minutes; D. Form a film from the slurry obtained in step C by scraping or casting. E. The membrane prepared in step D is subjected to gradient vacuum drying, which involves drying at 60°C for 8 hours, then at 80°C for 6 hours, and then at 100-120°C for 12 hours, to obtain a COF-lithium sulfonate gel membrane.
[0012] Furthermore, a method for preparing a solid-state battery containing a lithium sulfonate covalent organic framework solid electrolyte includes the following steps: S11. Preparation of positive electrode sheet: LiFePO4, lithium sulfonate covalent organic framework solid electrolyte and PVDF are mixed in a mass ratio of 8:1:1 to form a positive electrode slurry. The positive electrode slurry is coated onto aluminum foil by a doctor blade coating method and dried in a vacuum drying oven at 120°C for 12 hours. The positive electrode sheet is then formed by rolling with a pressure of 5MPa using a roller press. S12. Preparation of negative electrode sheet: After removing the surface oxide layer of lithium metal foil, it is immersed in COF precursor and placed in a constant temperature water bath at 70°C for 3 hours for in-situ polymerization. Then, it is dried in a forced-air drying oven at 80°C for 6 hours to form a COF protective layer with a thickness of 10μm on the surface of lithium metal foil. The negative electrode sheet is then sliced. S13. Preparation of COF-lithium sulfonate gel membrane; S14. Prepare the first composite membrane and the second composite membrane; S15. Battery cell preparation: The positive electrode sheet, the first composite film, the COF-lithium sulfonate gel film, the second composite film and the negative electrode sheet are aligned and stacked from bottom to top using a stacking machine, and then cut into 2cm×2cm×0.5cm using a laser cutting machine. The cells are then sealed at 120℃ and 0.3MPa for 5s using a vacuum heat sealing machine to form a battery cell. S16. Performance testing: The battery cells pass capacity testing, cycle testing, and safety testing, and are then put into storage after passing the tests. S17. Solid-state battery preparation: Several battery cells from the warehouse are connected in series or in parallel through standardized interfaces to form a solid-state battery.
[0013] The beneficial effects achieved by this invention are: 1. This invention uses lithium sulfonate covalent organic framework solid electrolyte. The amino groups on the surface of the COF substrate form stable covalent bonds with lithium sulfonate, solving the problem of high interfacial impedance between solid electrolytes and electrodes. The room temperature conductivity reaches 1.0 × 10⁻⁻⁻⁶. 4 The S / cm ratio is more than 30% better than similar products in the industry; the lithium-ion transference number is 0.85, which is much higher than the 0.3-0.4 of liquid electrolytes, and the charge transfer efficiency is improved by 50%; moreover, the lithium sulfonate covalent organic framework solid electrolyte maintains stable performance in the temperature range of -40℃ to 80℃, which solves the problem of low temperature failure of existing solid batteries. 2. The present invention uses a solid-state battery with a lithium sulfonate covalent organic framework solid electrolyte. In terms of preparation process, industrial-grade raw materials are used and in-situ polymerization is carried out. The process is simple and does not require expensive production equipment, which greatly reduces the production cost. 3. This invention selects several battery cells and connects them in series or in parallel through a standardized interface to form a solid-state battery. Series connection increases the battery voltage, and parallel connection increases the battery capacity. It can flexibly form batteries with full power specifications of 10-1000kWh, and give rise to various types such as micro energy storage, low-temperature special, and distributed energy storage. It is widely applicable to consumer electronics, medical equipment, energy storage power stations, low-altitude economy, new energy vehicles and other fields, and accurately meets the energy storage needs of different scenarios. The interface adopts a standardized interface, which can support the mixed splicing of different series of products.
[0014] Compared with existing technologies, the present invention has the advantages of simple process, low cost, high low temperature capacity stability and wide applicability. Attached Figure Description
[0015] Figure 1 This is a scanning electron microscope image of the lithium sulfonate covalent organic framework in Example 1 of the present invention; Figure 2 yes Figure 1 Enlarged image; Figure 3 This is the XRD pattern of the lithium sulfonate covalent organic framework in Example 1 of the present invention; Figure 4 This is a discharge specific capacity diagram of the solid-state battery in Embodiment 2 of the present invention; Figure 5 This is the electrochemical impedance spectroscopy of the solid-state battery in Example 2 of the present invention; Figure 6 This is a cycle performance diagram of the solid-state battery in Embodiment 2 of the present invention; Figure 7 This is a scanning electron microscope image of the negative electrode of a traditional battery; Figure 8 This is a scanning electron microscope image of the negative electrode sheet of the solid-state battery in Embodiment 2 of the present invention. Detailed Implementation
[0016] The present invention will now be described in further detail with reference to the accompanying drawings and embodiments. Example 1
[0017] A lithium sulfonate covalent organic framework solid electrolyte comprises a covalent organic framework (COF) substrate and lithium sulfonate groups bonded to the COF substrate. The COF substrate is an amino-functionalized COF.
[0018] A method for preparing a lithium sulfonate covalent organic framework solid electrolyte includes the following steps: S1. Preparation of COF substrate: 0.1 mmol of 1,3,5-tris(4-aminophenyl)benzene (TAPB) and 0.15 mmol of 2,5-dimethoxyterephthalaldehyde (DMTP) in a molar ratio of 1:1.5 were added to a beaker. The purity of TAPB and DMTP was controlled to be greater than 98%. TAPB needed to be purified by recrystallization from ethanol and vacuum drying before use to remove residual amine impurities and moisture interference. DMTP needed to be purified by silica gel column chromatography before use. Continue to add 6 ml of trimethylbenzene / dioxane mixed solvent, 3 ml of each, to the beaker, and place it in an ultrasonic cleaner to ultrasonically disperse until the solution is light yellow and transparent. After transferring the solution to a Schlenk tube, 0.5 ml of 6 mol / L glacial acetic acid was added dropwise. The tube was then subjected to a freeze-vacuum cycle three times before being sealed. The addition of glacial acetic acid was mainly to promote the condensation of amino and aldehyde groups. The sealed Schlenk tube was placed in a constant temperature oil bath and reacted at 120℃ for 72 hours. It was observed that the initial liquid was light yellow and transparent. After 12 hours, an orange-yellow flocculent precipitate gradually appeared. After 48 hours, the precipitate aggregated into lumps. After the reaction was completed, the mixture was transferred to a centrifuge tube, 10 ml of tetrahydrofuran was added, and the mixture was ultrasonically dispersed for 5 min. It was then centrifuged at 4000 r / min for 10 min. The centrifugation operation was repeated 3 times. The precipitate was transferred to a Soxhlet extractor and extracted with tetrahydrofuran as the extractant. The mixture was heated and refluxed for 24 hours, with refluxes occurring ≥6 times per hour. After extraction, the mixture was placed in a vacuum drying oven and dried at 60°C and -0.095 MPa for 12 hours to obtain the COF substrate, which is an orange-yellow powder of amino-functionalized COF, with a yield of approximately 85%.
[0019] S2. The COF substrate is mixed with lithium sulfonate groups and vacuum dried at 80°C and -0.095MPa for 24 hours to remove moisture and volatile impurities, thereby obtaining the COF precursor. S3. Add the COF precursor, catalyst, and deionized water to a four-necked flask at a solid-liquid ratio of 1:5. The catalyst is 2.5% triethylamine. Place the four-necked flask in a constant temperature water bath and control the temperature gradient by maintaining it at 60°C for 1 hour, raising it to 70°C for 2 hours, and raising it to 80°C for 2 hours. Stir the reaction at a rate of 150 r / min for 4-6 hours. Filter and dry the mixture using a vacuum filter to obtain lithium sulfonate covalent organic framework solid electrolyte.
[0020] Figure 1 This is a schematic diagram of a lithium sulfonate covalent organic framework under a scanning electron microscope. Figure 2 The magnified image reveals that the lithium sulfonate covalent organic framework solid electrolyte exhibits a distinct spherical particle aggregation structure resembling grape clusters or chains. Figure 2 The magnified image shows that the surface of the lithium sulfonate covalent organic framework solid electrolyte is covered with nanoscale protrusions, exhibiting a cauliflower or coral-like morphology, which significantly increases the specific surface area.
[0021] Figure 3 The XRD pattern of the lithium sulfonate covalent organic framework shows that the extremely strong sharp peak at 3-4° indicates a significant layered ordered structure and good long-range order in the lithium sulfonate covalent organic framework solid electrolyte. The lithium sulfonate groups are uniformly and orderly distributed in the lithium sulfonate covalent organic framework solid electrolyte without obvious phase separation or disordered stacking. The secondary peaks at 7-8° indicate that the secondary diffraction peaks of the lithium sulfonate covalent organic framework solid electrolyte are clear and the structure is highly uniform. The flattening peaks after 10° indicate that the lithium sulfonate covalent organic framework solid electrolyte has high purity and little random interference.
[0022] The lithium sulfonate covalent organic framework solid electrolyte solves the problem of high interfacial impedance between solid electrolytes and electrodes by forming stable covalent bonds between the amino groups on the COF substrate surface and lithium sulfonate, achieving a room temperature conductivity of 1.0 × 10⁻⁻⁻⁴. 4 The S / cm ratio is more than 30% better than similar products in the industry; the lithium-ion transference number is ≥0.85, which is much higher than the 0.3-0.4 of liquid electrolytes, and the charge transfer efficiency is improved by 50%; moreover, the lithium sulfonate covalent organic framework solid electrolyte maintains stable performance in the temperature range of -40℃ to 80℃, which solves the problem of low-temperature failure of existing solid batteries. Example 2
[0023] A solid-state battery containing a lithium sulfonate covalent organic framework solid electrolyte includes several battery cells. Each battery cell comprises, from bottom to top, a positive electrode, a first composite film, a COF-lithium sulfonate gel film, a second composite film, and a negative electrode. The positive electrode comprises LiFePO4 and lithium sulfonate covalent organic framework solid electrolyte in a mass ratio of 8:2, and a lithium phosphate covalent organic framework solid electrolyte. The active particles in the lithium sulfonate covalent organic framework solid electrolyte are at the nanoscale, possessing a large specific surface area, and exhibiting a certain pore structure and pore volume within the material. The first and second composite films have identical structures, both using polyethylene material with a certain strength as the base film, with functional groups capable of introducing proton and lithium-ion conductivity grafted onto the surface, and lithium conductive sites loaded. The negative electrode comprises a lithium metal foil and a COF protective layer. The lithium metal foil has high purity, and the COF protective layer possesses certain porosity characteristics.
[0024] The COF-lithium sulfonate gel membrane was prepared using a lithium sulfonate covalent organic framework solid electrolyte, and the preparation method was as follows: A. Prepare and pretreat lithium sulfonate covalent organic framework solid electrolyte, polyethylene oxide, lithium bis(trifluoromethanesulfonyl)imide, and additives in weight quantities of 20-30 parts, 60-70 parts, 10-15 parts, and 1-3 parts, respectively. The lithium sulfonate covalent organic framework solid electrolyte serves as an ion-conducting filler and single-ion conductor. Pretreatment of the lithium sulfonate covalent organic framework solid electrolyte requires vacuum drying at 120℃ for 12 hours to remove adsorbed water and residual solvent. Polyethylene oxide provides mechanical flexibility. Pretreatment of the polyethylene oxide and lithium bis(trifluoromethanesulfonyl)imide requires vacuum drying at 80℃ for 8 hours to avoid moisture introduction leading to side reactions. Nano-LLZTO / Al2O3 can be selected as an additive to improve mechanical strength and electrochemical stability. B. Add 60-70 parts of polyethylene oxide and 10-15 parts of lithium bis(trifluoromethanesulfonyl)imide to an anhydrous solvent and stir magnetically in an oil bath at 60°C for 12 hours until completely dissolved to form a transparent and homogeneous solution. The anhydrous solvent can be anhydrous N-methylpyrrolidone or acetonitrile. Then add 20-30 parts of lithium sulfonate covalent organic framework solid electrolyte, stir for 6 hours and ultrasonically disperse for 30 minutes. Continue to add 1-3 parts of additive and ultrasonically disperse for 15 minutes to ensure the slurry is uniform. C. Place the slurry mixed in step B in a vacuum drying oven at 60°C and evacuate for 30 minutes to remove air bubbles introduced by stirring. D. Form a film from the slurry obtained in step C using either a blade coating method or a casting method. In the blade coating method, aluminum foil or polytetrafluoroethylene is fixed on the coating table, the blade height is selected to be 200-300μm, and the film is formed by uniformly coating the slurry at a speed of 5-10mm / s with the blade, wherein the humidity is controlled to be less than 30% and the temperature is controlled to be 25±2℃. In the casting method, the slurry is poured into a customized casting tank, the liquid level is controlled, and the substrate is slowly tilted to allow the slurry to flow and form a film naturally. E. The membrane prepared in step D is subjected to gradient vacuum drying, which involves drying at 60°C for 8 hours, then at 80°C for 6 hours, and finally at 100-120°C for 12 hours, to prepare a COF-lithium sulfonate gel membrane. The 60°C vacuum drying for 8 hours is mainly to remove most of the residual solvent. The 80°C vacuum drying for 6 hours is to further remove the solvent and adsorbed water. The 100-120°C vacuum drying for 12 hours is to completely eliminate the residual moisture and solvent and avoid side reactions at the lithium metal anode.
[0025] A method for preparing a solid-state battery containing a lithium sulfonate covalent organic framework solid electrolyte includes the following steps: S11. Preparation of positive electrode sheet: LiFePO4, lithium sulfonate covalent organic framework solid electrolyte and PVDF are mixed in a mass ratio of 8:1:1 to form a positive electrode slurry. The positive electrode slurry is coated onto aluminum foil by a doctor blade coating method and dried in a vacuum drying oven at 120°C for 12 hours. The positive electrode sheet is then formed by rolling with a pressure of 5MPa using a roller press. By utilizing the pore confinement effect of lithium sulfonate covalent organic framework solid electrolyte to encapsulate LiFePO4 particles, the volume expansion rate during charge and discharge processes was suppressed from 6.8% to 2.1%, the cycle life was increased from 1000 cycles for traditional LiFePO4 to over 2000 cycles, and the capacity retention rate at 1C rate was increased from 85% to 92%.
[0026] S12. Preparation of negative electrode sheet: After removing the surface oxide layer of lithium metal foil, it is immersed in COF precursor and placed in a constant temperature water bath at 70°C for 3 hours for in-situ polymerization. Then, it is dried in a forced-air drying oven at 80°C for 6 hours to form a COF protective layer with a thickness of 10μm on the surface of lithium metal foil. The negative electrode sheet is then sliced. The dense channels of the COF protective layer physically block lithium dendrites from penetrating the film, reducing dendrite growth length from 15 μm to less than 3 μm. Simultaneously, the -NH2 polar functional groups within the channels accelerate Li⁺ diffusion, increasing the Li⁺ diffusion coefficient from 1.2 × 10⁻⁻⁻⁶. 8 cm² / s increased to 8.5×10⁻ 8 cm² / s.
[0027] S13. Preparation of COF-lithium sulfonate gel membrane; S14. Preparation of the first composite membrane and the second composite membrane: The high mechanical strength of the polyethylene material as the base membrane physically inhibits the growth of lithium dendrites, and the grafted functional groups assist the lithium sulfonate covalent organic framework solid electrolyte in realizing ion conduction, thereby increasing the critical current density for lithium dendrite piercing from 1 mA / cm² to 3 mA / cm², and reducing the interfacial impedance with the lithium sulfonate covalent organic framework solid electrolyte by 15%.
[0028] S15. Battery cell preparation: The positive electrode sheet, the first composite film, the COF-lithium sulfonate gel film, the second composite film and the negative electrode sheet are aligned and stacked from bottom to top using a stacking machine, and then cut into 2cm×2cm×0.5cm using a laser cutting machine. The cells are then sealed at 120℃ and 0.3MPa for 5s using a vacuum heat sealing machine to form a battery cell. S16. Performance testing: The battery cells pass capacity testing, cycle testing, and safety testing, and are then put into storage after passing the tests. S17. Solid-state battery preparation: Several battery cells from the warehouse are connected in series or in parallel through standardized interfaces to form a solid-state battery.
[0029] Figure 4The discharge specific capacity graph of the solid-state battery shows that at 0.1C, the discharge specific capacity is approximately 170 mAh g⁻¹, increasing to 175–180 mAh g⁻¹ during cycling, indicating that the solid-state battery can fully utilize its activity at low currents. At 0.3C, the discharge specific capacity stabilizes at approximately 170–175 mAh g⁻¹, with a gradual decline. At 0.5C, the discharge specific capacity further decreases to 165–170 mAh g⁻¹, indicating good structural stability of the solid-state battery at medium rates. At 1C, the discharge specific capacity is approximately 145–150 mAh g⁻¹, still maintaining a considerable level, and at 2C, the discharge specific capacity is approximately 95–105 mAh g⁻¹, still able to output stably under high currents, demonstrating good rate tolerance. When the current is switched back to 0.1C, the discharge specific capacity quickly recovers to 170–175 mAh g⁻¹ and remains stable, showing that the solid-state battery structure does not suffer irreversible damage after high-rate charge and discharge, demonstrating excellent reversibility.
[0030] Figure 5 The image shows the electrochemical impedance spectroscopy of a solid-state battery. The horizontal axis represents the real impedance, and the vertical axis represents the negative imaginary impedance. The interfacial impedance is approximately 12-14 ohms at 30℃, which is the highest, indicating that the solid-state battery has greater resistance to ion transport at low temperatures. From 40-80℃, the interfacial impedance decreases as the temperature increases.
[0031] Figure 6 The figure shows the cycle performance of the solid-state battery. At 1C, the discharge specific capacity is 145 Ah g⁻¹. After the first 50 cycles, the capacity slowly increases to a plateau and enters a stable decay stage. At 450 cycles, the discharge specific capacity is about 129.6 Ah g⁻¹, which is 90.4% of the initial capacity, showing excellent long-term cycle stability. The coulombic efficiency remains stable at 100% throughout the cycle, and the interface compatibility is excellent.
[0032] Figure 7 This is a scanning electron microscope (SEM) image of the negative electrode of a conventional battery. Figure 8 This is a scanning electron microscope image of the negative electrode of a solid-state battery. In traditional batteries, lithium dendrites accumulate severely on the negative electrode, while in the solid-state battery of this invention, only fine lithium dendrites are generated on the negative electrode, thus improving battery safety and battery life.
[0033] Solid-state batteries with lithium sulfonate covalent organic framework solid electrolytes utilize industrial-grade raw materials and are synthesized through in-situ polymerization. The process is simple and does not require expensive production equipment, significantly reducing production costs. The all-solid-state electrolyte-free structure eliminates the risks of leakage, thermal runaway, and combustion and explosion at the source, thus improving the safety factor.
[0034] Several battery cells are connected in series or parallel through standardized interfaces to form a solid-state battery. Series connection increases the battery voltage, and parallel connection increases the battery capacity. It can be flexibly configured into batteries with full power specifications of 10-1000kWh, giving rise to various types such as micro energy storage, cryogenic special, and distributed energy storage. It is widely applicable to consumer electronics, medical equipment, energy storage power stations, low-altitude economy, new energy vehicles and other fields, accurately meeting the energy storage needs of different scenarios. The interface adopts a standardized interface, IP67 waterproof and dustproof design, and the contact resistance at the splicing point is ≤5mΩ, ensuring the stability of the system after combination, and supporting the mixed splicing of different series of products.
[0035] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, modifications can still be made to the embodiments. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.
Claims
1. A lithium sulfonate covalent organic framework solid electrolyte, characterized in that: It includes a COF substrate and lithium sulfonate groups bonded to the COF substrate.
2. The lithium sulfonate covalent organic framework solid electrolyte according to claim 1, characterized in that: The COF substrate is an amino-functionalized COF.
3. A method for preparing a lithium sulfonate covalent organic framework solid electrolyte as described in any one of claims 1-2, characterized in that: Includes the following steps: S1. Preparation of COF substrate; S2. The COF substrate was mixed with lithium sulfonate groups and vacuum dried at 80°C and -0.095MPa for 24 h to obtain the COF precursor. S3. Add the COF precursor, catalyst, and deionized water to a four-necked flask at a solid-liquid ratio of 1:
5. Place the four-necked flask in a constant temperature water bath and control the temperature gradient by maintaining it at 60°C for 1 hour, raising it to 70°C for 2 hours, and raising it to 80°C for 2 hours. Stir the reaction at a rate of 150 r / min for 4-6 hours. Filter and dry the mixture using a vacuum filter to obtain lithium sulfonate covalent organic framework solid electrolyte.
4. The method for preparing a lithium sulfonate covalent organic framework solid electrolyte according to claim 3, characterized in that: The catalyst in step S3 is 2.5% triethylamine.
5. A solid-state battery containing a lithium sulfonate covalent organic framework solid-state electrolyte, using the lithium sulfonate covalent organic framework solid-state electrolyte prepared according to any one of claims 3-4, characterized in that: It includes several battery cells, each battery cell comprising a positive electrode, a first composite film, a COF-lithium sulfonate gel film, a second composite film, and a negative electrode, which are stacked sequentially from bottom to top.
6. A solid-state battery with a lithium sulfonate covalent organic framework solid electrolyte according to claim 5, characterized in that: The positive electrode comprises LiFePO4 and lithium sulfonate covalent organic framework solid electrolyte. The first composite film and the second composite film have the same structure. The first composite film and the second composite film use polyethylene material as the base film, and the surface is grafted with functional groups that can introduce proton and lithium ion conduction capabilities and load lithium conductive sites. The negative electrode comprises lithium metal foil and COF protective layer.
7. A solid-state battery with a lithium sulfonate covalent organic framework solid electrolyte according to claim 5, characterized in that: The COF-lithium sulfonate gel membrane was prepared using a lithium sulfonate covalent organic framework solid electrolyte, and the preparation method was as follows: A. Prepare and pretreat lithium sulfonate covalent organic framework solid electrolyte, polyethylene oxide, lithium bis(trifluoromethanesulfonyl)imide and additives in quantities of 20-30 parts, 60-70 parts, 10-15 parts and 1-3 parts by weight. B. Add 60-70 parts of polyethylene oxide and 10-15 parts of lithium bis(trifluoromethanesulfonyl)imide to anhydrous solvent and stir magnetically in an oil bath at 60°C for 12 hours until completely dissolved to form a transparent and homogeneous solution; then add 20-30 parts of lithium sulfonate covalent organic framework solid electrolyte, stir for 6 hours and ultrasonically disperse for 30 minutes, and continue to add 1-3 parts of additive and ultrasonically disperse for 15 minutes. C. Place the slurry mixed in step B in a vacuum drying oven and evacuate it at 60°C for 30 minutes; D. Form a film from the slurry obtained in step C by scraping or casting. E. The membrane prepared in step D is subjected to gradient vacuum drying, which involves drying at 60°C for 8 hours, then at 80°C for 6 hours, and then at 100-120°C for 12 hours, to obtain a COF-lithium sulfonate gel membrane.
8. A method for preparing a solid-state battery containing a lithium sulfonate covalent organic framework solid electrolyte as described in any one of claims 5-6, characterized in that: Includes the following steps: S11. Preparation of positive electrode sheet: LiFePO4, lithium sulfonate covalent organic framework solid electrolyte and PVDF are mixed in a mass ratio of 8:1:1 to form a positive electrode slurry. The positive electrode slurry is coated onto aluminum foil by a doctor blade coating method and dried in a vacuum drying oven at 120°C for 12 hours. The positive electrode sheet is then formed by rolling with a pressure of 5MPa using a roller press. S12. Preparation of negative electrode sheet: After removing the surface oxide layer of lithium metal foil, it is immersed in COF precursor and placed in a constant temperature water bath at 70°C for 3 hours for in-situ polymerization. Then, it is dried in a forced-air drying oven at 80°C for 6 hours to form a COF protective layer with a thickness of 10μm on the surface of lithium metal foil. The negative electrode sheet is then sliced. S13. Preparation of COF-lithium sulfonate gel membrane; S14. Prepare the first composite membrane and the second composite membrane; S15. Battery cell preparation: The positive electrode sheet, the first composite film, the COF-lithium sulfonate gel film, the second composite film and the negative electrode sheet are aligned and stacked from bottom to top using a stacking machine, and then cut into 2cm×2cm×0.5cm using a laser cutting machine. The cells are then sealed at 120℃ and 0.3MPa for 5s using a vacuum heat sealing machine to form a battery cell. S16. Performance testing: The battery cells pass capacity testing, cycle testing, and safety testing, and are then put into storage after passing the tests. S17. Solid-state battery preparation: Several battery cells from the warehouse are connected in series or in parallel through standardized interfaces to form a solid-state battery.