Preparation method and application of sp2 carbon conjugated covalent organic framework-based solid electrolyte
By preparing sp2 carbon conjugated covalent organic framework-based solid electrolytes, the problems of ionic conductivity and interface stability in solid lithium batteries over a wide temperature range were solved, and higher lithium-ion migration and mechanical properties were achieved.
Patent Information
- Application Number
- CN202511333610.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-09-18
- Publication Date
- 2025-12-23
AI Technical Summary
Existing solid-state lithium batteries suffer from low room-temperature ionic conductivity, insufficient interface stability and mechanical properties, which limit their application over a wide temperature range.
Using sp2 carbon conjugated covalent organic framework material as a matrix, compound 3 was synthesized through Knoevenagel condensation reaction, and nanofiber membranes were prepared by electrospinning technology. Combined with lithium salt solution impregnation, sp2 carbon conjugated covalent organic framework-based solid electrolyte was formed.
It improves lithium-ion transference number and ionic conductivity, enhances interface compatibility and mechanical properties, and achieves stability and efficient ion conduction over a wide temperature range.
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Figure CN121192245A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of solid-state lithium battery technology, specifically relating to a SP... 2 Preparation methods and applications of carbon conjugated covalent organic framework-based wide-temperature-range solid electrolytes. Background Technology
[0002] Against the backdrop of continuously growing global energy demand and increasing environmental awareness, efficient and safe energy storage technologies have become a research focus. Lithium-ion batteries, due to their high energy density and long cycle life, are widely used in portable electronic devices, electric vehicles, and large-scale energy storage systems. However, traditional liquid lithium-ion batteries suffer from numerous problems, such as the risk of leakage of the liquid electrolyte, flammability, and safety hazards caused by lithium dendrite growth. These issues severely restrict the further development and application of lithium-ion batteries.
[0003] Solid-state lithium batteries use solid electrolytes instead of traditional liquid electrolytes, fundamentally solving the problems of leakage and flammability associated with liquid electrolytes. They also effectively suppress lithium dendrite growth, significantly improving battery safety. Furthermore, solid electrolytes offer advantages such as simplified packaging processes and increased energy density, making them a research hotspot in the energy storage field in recent years. Solid electrolytes are mainly divided into two categories: inorganic solid electrolytes and solid polymer electrolytes. While inorganic solid electrolytes possess high ionic conductivity, they suffer from complex manufacturing processes, high cost, brittleness, and poor compatibility with electrode interfaces. Solid polymer electrolytes, on the other hand, have become a highly promising candidate material due to their strong designability, ease of processing, and flexibility. However, the low room-temperature ionic conductivity of solid polymer electrolytes is a key limitation to their large-scale application. To improve the overall performance of solid polymer electrolytes, preparing composite solid polymer electrolytes by filling the polymer matrix with functional materials is one of the key technologies for solving these problems.
[0004] Two-dimensional vinylidene (sp) 2 C=C linked covalent organic frameworks (COFs), as novel crystalline porous organic polymers, possess advantages such as highly ordered pore structures, tunable chemical composition and functional groups, and good chemical and thermal stability, demonstrating great application potential in the field of solid-state electrolytes. COFs with strongly polar groups can interact with lithium salts, promoting lithium salt dissociation and generating more freely moving lithium ions, thereby improving ionic conductivity. Simultaneously, their ordered pore structure provides a fast channel for lithium ion transport, which helps reduce ion transport resistance. Furthermore, the strongly polar groups can enhance the interaction between COFs and the polymer matrix, improving the interfacial stability and mechanical properties of the composite material. Therefore, developing a COF with strongly polar groups is a promising approach. 2Carbon conjugated covalent organic framework-based solid-state electrolysis is of great theoretical significance and practical application value in addressing issues such as ion conduction, interface stability, and mechanical properties of solid-state lithium batteries over a wide temperature range. Summary of the Invention
[0005] This invention provides an sp containing a strongly polar group 2 Carbon conjugated covalent organic framework-based wide-temperature-range solid electrolytes are developed to further improve the ionic conductivity and lithium-ion transference number of COF materials to meet the needs of practical applications; optimize the composite process of COF and polymer matrix to achieve uniform dispersion of COF in polymer and avoid agglomeration; and improve the interfacial compatibility between COF-based solid electrolytes and electrodes, thereby reducing interfacial resistance.
[0006] The technical solution of the present invention is as follows:
[0007] a kind of sp 2 The preparation method of carbon conjugated covalent organic framework-based solid electrolytes includes the following steps:
[0008] Step 1: Using compounds 1 and 2 as raw materials, compound 3, i.e., sp, is synthesized via a Knoevenagel condensation reaction. 2 Carbon conjugated covalent organic framework material; compound 1 is terephthalonitrile, and compound 2 is 1,3,5-tris(3-fluoro-4-formylphenyl)benzene;
[0009] Step 2: Compound 3, polyvinylpyrrolidone and polyacrylonitrile are dissolved in N,N-dimethylformamide, and nanofiber membranes are prepared by electrospinning.
[0010] Step 3: Prepare a precursor solution consisting of ethylene glycol dimethyl ether, 1,3-dioxolane and lithium salt;
[0011] Step 4: Wet the nanofiber membrane from Step 2 in the precursor solution from Step 3 to obtain the sp. 2 Carbon conjugated covalent organic framework-based solid electrolyte.
[0012] Furthermore: In step one, the molar ratio of compound 1 to compound 2 is 2:1 to 6, the reaction temperature is 60 to 150°C, the reaction time is 1 to 7 days, the entire reaction is carried out under vacuum and closed conditions, and contact with oxygen is avoided during the reaction to prevent the product from being oxidized.
[0013] Furthermore, in step two, the mass fraction of compound 3 is 0.5-3% of polyacrylonitrile.
[0014] Furthermore: In step three, the volume ratio of ethylene glycol dimethyl ether to 1,3-dioxolane is 1:1.
[0015] Furthermore: In step three, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide, with a concentration of 0.5–1 mol / L. -1 .
[0016] Furthermore, in step four, the soaking time is 2 to 24 hours.
[0017] a kind of sp 2 The application of carbon conjugated covalent organic framework-based solid electrolytes is in the preparation of solid-state lithium metal batteries, using the aforementioned sp... 2 Carbon conjugated covalent organic framework-based solid electrolytes are used as electrolytes in lithium batteries, with lithium iron phosphate as the positive electrode material and lithium metal as the negative electrode material.
[0018] Beneficial effects:
[0019] 1. The sp constructed by this invention 2 Carbon-conjugated covalent organic framework-based solid electrolytes possess multiple strongly polar groups and exhibit high ionic conductivity (4.96 × 10⁻⁶) in lithium metal batteries. -4 S cm -1 The assembled Li||Li symmetric cell exhibits good stability, lithium-ion transference number (0.87), and good performance at 0.1 mA / cm². -2 It can be stably cycled for 4000 hours at a current density.
[0020] 2. By sp 2 The Li||LiFePO4 battery assembled with a carbon conjugated covalent organic framework-based solid electrolyte exhibited good electrochemical performance, maintaining a capacity retention of 72.6% after more than 4000 cycles under a high current of 10C.
[0021] 3. By sp 2 The Li||LiFePO4 battery assembled with a carbon-conjugated covalent organic framework-based solid electrolyte exhibited good electrochemical stability under both high and low temperature conditions. At 60℃ and a 5C current density, it achieved a current density of 150 mAh g⁻¹. -1 The capacity is around 120 mAh / g. At -20°C, it exhibits a current density of 0.5C. -1 The specific capacity of the left and right sides.
[0022] 4. The sp of the present invention 2 Carbon conjugated covalent organic framework-based solid electrolytes are easy to prepare, low in cost, exhibit outstanding electrochemical performance, and are easy to mass-produce. Attached image description:
[0023] Figure 1 For sp 2 FTIR diagram of carbon conjugated covalent organic framework;
[0024] Figure 2 For sp 2 XRD pattern of a carbon conjugated covalent organic framework;
[0025] Figure 3 For sp 2 SEM image of a carbon-conjugated covalent organic framework;
[0026] Figure 4 For sp 2 SEM image of a carbon conjugated covalent organic framework-based wide-temperature-range solid electrolyte;
[0027] Figure 5 For sp 2 Lithium-ion transport number plot of carbon conjugated covalent organic framework-based wide-temperature-range solid electrolyte;
[0028] Figure 6 For sp 2 Impedance plots of carbon conjugated covalent organic framework-based wide-temperature-range solid electrolytes at different temperatures;
[0029] Figure 7 For sp 2 Conductivity diagram of broad-temperature-range solid electrolytes based on carbon conjugated covalent organic frameworks; inset diagram is the interfacial activation energy diagram.
[0030] Figure 8 For sp 2 Time-voltage curves of Li||Li symmetric cells assembled with carbon conjugated covalent organic framework-based wide-temperature-range solid electrolytes;
[0031] Figure 9 For sp 2 Cycling diagram of Li||LiFePO4 battery assembled with carbon conjugated covalent organic framework based wide-temperature-range solid electrolyte at 10C current density;
[0032] Figure 10 For sp 2 Rate capability diagram of Li||LiFePO4 battery assembled with carbon conjugated covalent organic framework based wide-temperature-range solid electrolyte;
[0033] Figure 11 For sp 2 Cycling diagram of Li||LiFePO4 battery assembled with carbon conjugated covalent organic framework based wide-temperature-range solid electrolyte at 60℃ and 5C current density;
[0034] Figure 12 For sp 2 Cyclic graph of Li||LiFePO4 battery assembled with carbon conjugated covalent organic framework based wide-temperature-range solid electrolyte at -20℃ and 0.5C current density. Detailed Implementation
[0035] The technical solution of the present invention will be further described in detail below with reference to specific embodiments, in order to enable those skilled in the art to have a clearer understanding and knowledge of this application. The following specific embodiments should not be construed or interpreted in any way as limiting the scope of protection claimed in the claims of this application.
[0036] All reagents and instruments used in this embodiment are commercially available.
[0037] Example 1
[0038] This invention provides a sp 2 Carbon-conjugated covalent organic framework-based solid electrolytes, possessing strongly polar groups, can be used as solid electrolyte fillers. 2 The synthetic route for carbon conjugated covalent organic frameworks is as follows:
[0039] In a Pyrex tube, terephthalonitrile (11.7 mg, 0.075 mmol), 1,3,5-tris(3-fluoro-4-formylphenyl)benzene (23.0 mg, 0.05 mmol), 25% wt sodium methoxide, methanol (1 mL), and 1,4-dioxane (1 mL) were added. After three cycles of freeze-de-freeze-charge, the tube was sealed and reacted at 120 °C for 72 h. After cooling to room temperature, the mixture was poured into DMF, filtered, and washed successively with DMF, water, and tetrahydrofuran. The resulting yellow solid (denoted as compound 3) was collected, which is SP. 2 Carbon-conjugated covalent organic framework. The obtained material was characterized by FTIR, XRD, and SEM, and the results are as follows. Figures 1-3 As shown, prove sp 2 A carbon conjugated covalent organic framework was successfully synthesized.
[0040] Example 2
[0041] sp synthesized in Example 1 2 Adding carbon conjugated covalent organic frameworks to polymer substrates: sp 2 A carbon-conjugated covalent organic framework, polyacrylonitrile, and polyvinylpyrrolidone (dissolved in DMF at a ratio of 1:50:50) were used to prepare nanofiber membranes via electrospinning. The membranes were then washed with a large amount of deionized water to obtain porous nanofiber membranes. After drying, the membranes were immersed in a 1M LiTFSI solution of ethylene glycol dimethyl ether and 1,3-dioxolane (volume ratio 1:1) for 12 hours. The solvent was then removed by repeated wiping with filter paper to obtain sp... 2 A carbon-conjugated covalent organic framework-based solid electrolyte was characterized by SEM and electrochemical characterization, including lithium-ion transference number and ionic conductivity. The results are as follows: Figures 4-7 As shown, sp 2The carbon-conjugated covalent organic framework-based wide-temperature-range solid electrolyte has a porous structure and an ionic conductivity of 4.96 × 10⁻⁶. -4 S cm -1 The lithium-ion transference number is 0.87.
[0042] Example 3
[0043] The sp synthesized in Example 2 2 Carbon-conjugated covalent organic framework-based solid electrolytes as solid electrolytes for lithium metal batteries: assembling Li||Li symmetric cells: sp 2 Carbon-conjugated covalent organic framework-based solid electrolytes were cut into circular electrode sheets with a diameter of 16 mm for later use; using the 2032 type coin cell standard, lithium sheets and sp... were sequentially placed in the negative electrode shell. 2 A carbon-conjugated covalent organic framework-based solid electrolyte, lithium sheet, gasket, spring, and positive electrode shell were encapsulated to obtain a lithium metal 2032 coin cell. Cycle stability testing was then performed using the Blue Electric / Newway battery testing system. The results are as follows: Figure 8 As shown, the assembled Li||Li symmetric cell at 0.1 mA cm⁻¹ -2 It can be stably cycled for 4000 hours at a current density.
[0044] Example 4
[0045] The sp synthesized in Example 2 2 Solid-state lithium metal batteries were prepared using carbon-conjugated covalent organic framework-based solid electrolytes as the solid electrolyte for lithium metal batteries: LiFePO4, Super P, and PVDF were added to the solvent N-methylpyrrolidone in a mass ratio of 8:1:1 and ground into a uniform slurry. This slurry was then coated onto aluminum foil using a coating machine. After being placed in an oven at 50°C for 12 hours to remove residual solvent, the foil was cut into circular electrode sheets with a diameter of 12 mm for later use. Using the 2032 coin cell standard, the circular electrode sheets and super P were sequentially placed in the negative electrode shell. 2 A carbon conjugated covalent organic framework-based solid electrolyte, lithium sheet, pad, spring, and positive electrode shell are packaged to obtain a lithium metal 2032 coin cell battery, which is then subjected to constant current charge-discharge testing using the Blue Electric / Newway battery testing system.
[0046] Depend on Figure 9 The charge-discharge curves show that the battery prepared in this invention maintains a capacity retention of 72.6% after more than 4000 cycles under a high current of 10C. Meanwhile, Figure 10 The rate performance of the battery at different current densities is presented. Even at a current density of 10C, the capacity still reaches 106 mAh g⁻¹. -1When the current density returns to 1C, the capacity returns to its initial capacity. Further testing was conducted on the electrochemical performance of the Li||LiFePO4 battery under high-temperature conditions. Figure 11 The cycling curves show that it exhibits a current density of 150 mAh g at 60℃ and 5C. -1 The specific capacity was measured. Furthermore, the cycle performance of the Li||LiFePO4 battery under low-temperature conditions was tested. Figure 12 It can be seen that the battery exhibits a current density of 120mAh g at -20℃ and 0.5C. -1 It has a high specific capacity and can be stably cycled for 1000 times.
Claims
1. A kind of sp 2 The preparation method of carbon conjugated covalent organic framework-based solid electrolytes includes the following steps: Step 1: Using compounds 1 and 2 as raw materials, compound 3, i.e., sp, is synthesized via a Knoevenagel condensation reaction. 2 Carbon conjugated covalent organic framework material; compound 1 is terephthalonitrile, and compound 2 is 1,3,5-tris(3-fluoro-4-formylphenyl)benzene; Step 2: Compound 3, polyvinylpyrrolidone and polyacrylonitrile are dissolved in N,N-dimethylformamide, and nanofiber membranes are prepared by electrospinning. Step 3: Prepare a precursor solution consisting of ethylene glycol dimethyl ether, 1,3-dioxolane and lithium salt; Step 4: Wet the nanofiber membrane from Step 2 in the precursor solution from Step 3 to obtain the sp 2 Carbon conjugated covalent organic framework-based solid electrolyte.
2. The sp according to claim 1 2 A method for preparing a carbon-conjugated covalent organic framework-based solid electrolyte, characterized in that, In step one, the molar ratio of compound 1 to compound 2 is 2:1 to 6, the reaction temperature is 60 to 150°C, the reaction time is 1 to 7 days, and the entire reaction is carried out under vacuum and closed conditions. During the reaction, contact with oxygen is avoided to prevent the product from being oxidized.
3. A sp according to claim 1 2 A method for preparing a carbon-conjugated covalent organic framework-based solid electrolyte, characterized in that, In step two, the mass fraction of compound 3 is 0.5-3% of polyacrylonitrile.
4. A sp according to claim 1 2 A method for preparing a carbon-conjugated covalent organic framework-based solid electrolyte, characterized in that, In step three, the volume ratio of ethylene glycol dimethyl ether to 1,3-dioxopentane is 1:
1.
5. A sp according to claim 1 2 A method for preparing a carbon-conjugated covalent organic framework-based solid electrolyte, characterized in that, In step three, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide, with a concentration of 0.5–1 mol / L. -1 .
6. A sp according to claim 1 2 A method for preparing a carbon-conjugated covalent organic framework-based solid electrolyte, characterized in that, In step four, the soaking time is 2 to 24 hours.
7. A sp as described in claim 1 2 The application of carbon conjugated covalent organic framework-based solid electrolytes is in the preparation of solid-state lithium metal batteries, using the aforementioned sp... 2 Carbon conjugated covalent organic framework-based solid electrolytes are used as electrolytes in lithium batteries, with lithium iron phosphate as the positive electrode material and lithium metal as the negative electrode material.