Lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte and preparation method and application thereof

Abstract

This invention belongs to the field of functional materials technology, specifically disclosing a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte, its preparation method, and its application. The invention involves thoroughly mixing polyethylene oxide, polyacrylate-polyethylene glycol, a three-dimensional covalent organic framework lithium salt (Q-COFs) containing cage-like silsesquioxanes, lithium salt, and a photoinitiator in acetonitrile. The mixture is then poured into a mold, irradiated with ultraviolet light, and vacuum dried to obtain the lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte. The quasi-solid-state electrolyte provided by this invention exhibits significantly improved flame retardancy compared to pure liquid electrolytes, increasing safety. The ordered channels of its covalent organic framework facilitate lithium ion migration during charging and discharging, while also promoting uniform lithium ion deposition, forming a stable solid electrolyte interface, and inhibiting lithium dendrite growth. It exhibits excellent electrochemical performance and can improve the cycle performance of lithium metal batteries.

Description

Technical Field

[0001] This invention belongs to the field of lithium metal battery polymer electrolyte preparation, specifically relating to a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte, its preparation method, and its application. Background Technology

[0002] With the development of portable mobile devices and electric vehicles, the demand for energy storage devices has increased accordingly. Lithium metal batteries have attracted widespread attention due to their wide operating temperature range, high electrochemical potential, and high energy density. However, traditional lithium metal batteries typically use large amounts of flammable liquid electrolytes, posing safety hazards such as electrolyte leakage, combustion, and even fires. Furthermore, commercially available liquid electrolytes, such as ether-based electrolytes, have poor oxidation stability, are unsuitable for high-voltage environments, and are prone to side reactions with metallic lithium, forming lithium dendrites, which also pose safety risks, severely hindering their further development and diversified applications. To fundamentally solve this problem, researchers have developed all-solid-state electrolytes that contain no liquid electrolyte. However, all-solid-state lithium metal batteries face challenges such as low capacity and difficulty in long-term cycling at room temperature.

[0003] By combining the properties of all-solid-state electrolytes and liquid electrolytes, a gel electrolyte, or quasi-solid-state electrolyte, is constructed to improve the safety performance of lithium metal batteries while achieving long-term stable operation at room temperature. Summary of the Invention

[0004] To overcome the shortcomings and deficiencies of existing technologies, the primary objective of this invention is to provide a method for preparing a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte (QSSE). This method uses polyethylene oxide and acrylate polyethylene glycol as substrates, adding a three-dimensional covalent organic framework lithium salt (Q-COFs) containing cage-like silsesquioxanes. Because the open channels of the covalent organic framework's mesopore size provide excellent pathways for lithium-ion transport, lithium ions are uniformly deposited, forming a stable solid electrolyte interface and inhibiting lithium dendrite growth. This results in a safer lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte with superior electrochemical performance.

[0005] The second objective of this invention is to provide a three-dimensional covalent organic framework quasi-solid-state electrolyte for lithium metal batteries prepared by the above-described preparation method.

[0006] A third objective of this invention is to provide the application of a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte in the preparation of lithium metal batteries.

[0007] The primary objective of this invention is achieved through the following technical solution:

[0008] A method for preparing a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte.

[0009] Includes the following steps:

[0010] (1) Sonicate Q-COFs with acetonitrile and stir thoroughly to obtain mixed solution I;

[0011] (2) Under light-protected conditions, polyethylene oxide, acrylate polyethylene glycol, lithium salt and photoinitiator were thoroughly stirred in acetonitrile to obtain mixed solution II;

[0012] (3) Mix the two solutions I and II together and continue stirring under light-protected conditions to obtain a mixture;

[0013] (4) The mixture was poured into a polytetrafluoroethylene mold, reacted under ultraviolet light, and dried under vacuum to obtain a three-dimensional covalent organic framework quasi-solid electrolyte for lithium metal batteries.

[0014] Preferably, the mass fraction of Q-COFs in the mixed solution I is 5-15%; the combined mass fraction of polyethylene oxide, polyethylene glycol dimethacrylate, polyethylene glycol methyl ether methacrylate, and photoinitiator in the mixed solution II is 10-20%, and the molar fraction of lithium salt relative to polyethylene oxide is 5-15%.

[0015] Preferably, the mass fraction of Q-COFs in the mixed solution I is 10%; the mass fraction of polyethylene oxide in the mixed solution II is 10%, the mass fraction of polyethylene glycol dimethacrylate is 5%, the mass fraction of polyethylene glycol methyl ether methacrylate is 1%, the mass fraction of photoinitiator is 1%, and the molar fraction of lithium salt relative to polyethylene oxide is 10%.

[0016] Preferably, the lithium salt is one of lithium bis(trifluoromethanesulfonyl)imide, lithium hexafluorophosphate, lithium hypochlorite, and lithium chloride; and the photoinitiator is azobisisobutyronitrile or benzophenone.

[0017] Preferably, the lithium salt is lithium bis(trifluoromethanesulfonyl)imide; and the photoinitiator is azobisisobutyronitrile.

[0018] Preferably, the stirring time in step (1) is 3-4 hours; the stirring time in step (2) is 7-10 hours; the stirring time in step (3) is 2-4 hours; the reaction time in step (4) is 0.5-1 hours; and the vacuum drying temperature is 30°C.

[0019] Preferably, the structural formula of the three-dimensional covalent organic framework lithium salt (Q-COFs) containing cage-like silsesquioxane in step (1) is as follows:

[0020]

[0021] Preferably, the preparation method of the three-dimensional covalent organic framework lithium salt (Q-COFs) containing cage-like silsesquioxane includes the following steps:

[0022] a. Mix decaphenylaminosilsesquioxane (DAPS) with 1-butyl-3-methylimidazolium bisfluoromethanesulfonylimide salt ([BMIm]NTf2) at a mass ratio of 1:1 to 2.5 to obtain a clear solution I;

[0023] b. Mix terephthalaldehyde (TPA) with [BMIm]NTf2 at a mass ratio of 1:1 to 2.5 to obtain a clear solution II;

[0024] c. After mixing and sonicating the clear solution I and the clear solution II, react at high temperature to obtain a mixed solution;

[0025] d. The mixed solution obtained in step (3) is added with lithium styrene sulfonylimide, boron trifluoride diethyl ether and 2,3-dichloro-5,6-dicyanobenzoquinone in a molar ratio of 10-15:1:1 and reacted at high temperature to obtain a crude product of a three-dimensional organic covalent framework lithium salt containing cage-type silsesquioxane. After separation and purification, a three-dimensional organic covalent framework lithium salt containing cage-type silsesquioxane is obtained.

[0026] Preferably, the ultrasound time in step c is 1 to 10 minutes.

[0027] Preferably, the high-temperature reaction in step c is carried out at a temperature of 120°C for 3 to 4 days.

[0028] Preferably, the high-temperature reaction in step d is carried out at a temperature of 120°C for 3 to 7 days.

[0029] Preferably, the specific steps of separation and purification in step d are as follows: anhydrous ethanol is added to the crude product of the three-dimensional organic covalent framework lithium salt containing cage-like silsesquioxanes, and the solid precipitate is collected by centrifugation. The solid product is washed with ethanol and acetone, soaked in tetrahydrofuran, and a yellow powdery product is collected, which is the three-dimensional organic covalent framework lithium salt containing cage-like silsesquioxanes.

[0030] Preferably, the lithium styrenesulfonylimide is at least one of lithium 4-styrene (trifluoromethylsulfonyl)sulfonylimide, lithium bis(4-vinylphenyl)sulfonylimide, or lithium 4-styrene (trifluoromethyl(N-methanesulfonylimide))sulfonylimide.

[0031] The second objective of this invention is achieved through the following technical solution:

[0032] A lithium metal three-dimensional covalent organic framework quasi-solid electrolyte prepared by the above preparation method.

[0033] The third objective of this invention is achieved by the following technical solution:

[0034] Application of a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte in the preparation of lithium metal batteries.

[0035] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0036] (1) The present invention obtains a three-dimensional covalent organic framework quasi-solid electrolyte through chemical cross-linking. The reaction is carried out at room temperature and pressure, which is safe and the experimental process is relatively simple and convenient.

[0037] (2) The three-dimensional covalent organic framework quasi-solid electrolyte prepared by the present invention can reduce the safety hazards of lithium metal batteries.

[0038] (3) The three-dimensional covalent organic framework quasi-solid electrolyte prepared by the present invention facilitates the uniform migration of lithium ions and uniform deposition at the negative electrode, and effectively inhibits the growth of lithium dendrites.

[0039] (4) The successful implementation of this invention and its application in lithium metal batteries will help improve the cycle performance of lithium metal batteries. Attached Figure Description

[0040] Figure 1 Electrochemical window curves of the QSSE-1 assembled lithium steel battery prepared in Example 1;

[0041] Figure 2 Temperature-conductivity curve of lithium-ion battery assembled with QSSE-1 prepared in Example 1;

[0042] Figure 3 Arrhenius-ion conductivity curves of the lithium-lithium symmetric battery assembled with QSSE-1 prepared in Example 1 at different temperatures;

[0043] Figure 4 Cycle life test of QSSE-1 prepared in Example 1 in lithium-ion battery;

[0044] Figure 5 Cyclic performance of QSSE-1 prepared in Example 1 in LiFPO4 / Li batteries. Detailed Implementation

[0045] The present invention will be further described in detail below with reference to the embodiments, but the implementation of the present invention is not limited thereto.

[0046] All reagents and instruments used in this embodiment are commercially available.

[0047] The preparation steps of the decaphenylaminosilsesquioxane (DAPS) described in Examples 1 to 3 are as follows:

[0048] (1) Acid-catalyzed hydrolysis of phenylsiloxane monomer: 5 g of phenyltrimethoxysilane was added to 100 mL of toluene and 3.52 mL of hydrochloric acid aqueous solution (10% w%) was added. The mixture was polymerized at 80 °C for 8 hours, cooled to room temperature, washed with saturated sodium chloride solution until neutral, dried overnight with anhydrous magnesium sulfate, filtered and rotary evaporated to obtain the hydrolysis product.

[0049] (2) Synthesis of decaphenylsilsesquioxane (DPS): The hydrolysis product in step (1) was dissolved in dichloromethane (100 mL), 1.0 M tetrabutylammonium fluoride solution (0.2 mL) was added, and the reaction was carried out at room temperature for 48 hours. After cooling to room temperature, the product was washed with saturated sodium chloride solution until neutral, dried overnight with anhydrous magnesium sulfate, filtered and rotary evaporated to obtain DPS.

[0050] (3) Synthesis of decaphenylnitrososilsesquioxane (DNPS): Take an appropriate amount of nitric acid (15 mL) into the reaction flask, and put the entire reaction flask in an ice bath. Add the decaphenylnitrososilsesquioxane (5 g) from step (2) into the reaction flask in small amounts several times. React for 30 min under ice bath conditions, and then react at room temperature for 8 hours. Take an appropriate amount of crushed ice into a 1 L beaker, and pour the reaction solution into the ice while stirring. Place it in a fume hood overnight, filter and dry to obtain a light yellow solid, i.e., DNPS.

[0051] (4) Synthesis of decaphenylaniline silsesquioxane (DAPS): Decaphenylnitrosilsesquioxane (3g) was dissolved in tetrahydrofuran (24mL), triethylamine (24mL) and palladium on carbon (10% w%, 0.180g) were added, the temperature was raised to 80℃, formic acid was added, and the reaction was carried out for 8 hours. After cooling to room temperature, tetrahydrofuran aqueous solution was added, filtered, ethyl acetate (50mL) was added, and the mixture was extracted with deionized water. After drying with anhydrous magnesium sulfate overnight, the polymerized mixture was poured into petroleum ether to precipitate the polymer, yielding DAPS.

[0052] Example 1

[0053] (1) Mix and grind decaphenylaminosilsesquioxane (DPAS), transfer it into a centrifuge tube, add 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide salt ([BMIm]NTf2), sonicate for 1 min to obtain clear solution I; the [BMIm]NTf2 and decaphenylaminosilsesquioxane are mixed in a mass ratio of 1:1 (g / g);

[0054] (2) Transfer p-diphenylformaldehyde into a centrifuge tube, add [BMIm]NTf2, sonicate for 1 min to obtain clear solution II; the [BMIm]NTf2 and p-diphenylformaldehyde are mixed at a mass ratio of 1:1 (g / g);

[0055] (3) Mix clear solution I and clear solution II, sonicate, and react at 120℃ for 3 to 4 days;

[0056] (4) Add lithium 4-styrene (trifluoromethylsulfonyl)sulfonylimide, boron trifluoride diethyl ether, and 2,3-dichloro-5,6-dicyano-p-benzoquinone to the mixed solution in step (3), and react at a high temperature of 120°C to obtain a crude product of a three-dimensional organic covalent framework lithium salt containing cage-type silsesquioxane. The lithium 4-styrene (trifluoromethylsulfonyl)sulfonylimide, boron trifluoride diethyl ether, and 2,3-dichloro-5,6-dicyano-p-benzoquinone are mixed in a mass ratio of 10:1:1.

[0057] (5) After the reaction was completed, the product was cooled to room temperature. 10 mL of anhydrous ethanol was added to the crude product of the three-dimensional organic covalent framework lithium salt containing cage-type silsesquioxane. The solid precipitate was collected by centrifugation. The solid product was washed several times with ethanol and acetone, and soaked in tetrahydrofuran three times. Fresh tetrahydrofuran was replaced after 8 hours. The product was collected as a yellow powder, namely Q-COF-1.

[0058] (6) Sonicate Q-COF-1 with acetonitrile and stir for 3-4 hours to form mixed solution I, wherein the mass fraction of Q-COFs is 10%; (7) Stir polyethylene oxide, polyethylene glycol acrylate, lithium bis(trifluoromethanesulfonyl)imide and azobisisobutyronitrile in acetonitrile for 7-10 hours under light-protected conditions to form mixed solution II. In mixed solution II, the mass fraction of polyethylene oxide is 10%, the mass fraction of polyethylene glycol dimethacrylate is 5%, the mass fraction of polyethylene glycol methyl ether methacrylate is 1%, the mass fraction of azobisisobutyronitrile is 1%, the molar fraction of lithium bis(trifluoromethanesulfonyl)imide relative to polyethylene oxide is 10%, and the remainder is acetonitrile;

[0059] (8) Mix the two solutions I and II together and continue stirring for 2-4 hours in the dark to obtain a mixture;

[0060] (9) The mixture was poured into a polytetrafluoroethylene mold and reacted under ultraviolet light for 0.5 to 1 h. It was then dried under vacuum at 30 °C to obtain the quasi-solid electrolyte QSSE-1.

[0061] Figure 1 The electrochemical window curve of the QSSE-1 assembled lithium steel battery prepared in Example 1 is shown. The electrochemical window is about 5.1V, indicating that QSSE-1 has good electrochemical stability and can be used in high-voltage batteries.

[0062] Figure 2The figure shows the temperature-conductivity curves of the lithium-ion battery assembled with QSSE-1 prepared in Example 1. The ionic conductivity of QSSE-1 increases with increasing temperature. The ionic conductivity at 303K, 313K, 323K, 333K, 343K, and 353K is 0.351, 0.437, 0.496, 0.545, 0.615, and 0.727 mS / cm, respectively, which is superior to most reported quasi-solid-state electrolytes.

[0063] Figure 3 The Arrhenius-ion conductivity curves of the lithium-lithium symmetric battery assembled with QSSE-1 prepared in Example 1 at different temperatures were obtained, and the activation energy (E) of QSSE-1 was calculated using the Nernst-Einstein formula. a The value is approximately 0.34 eV, indicating that ion transport is fast and independent of the operating environment temperature.

[0064] Figure 4 The QSSE-1 prepared in Example 1 was tested for cycle life in a lithium-ion battery at a current density of 1 mA / cm². 2 The areal density is 1 mAh / cm³. 2 Under the conditions tested, the QSSE-1 assembled battery exhibited a stable voltage plateau and low voltage hysteresis, and continued cycling for nearly 800 hours, demonstrating that QSSE-1 plays an excellent role in accelerating ion transport, constructing a stable SEI, and achieving uniform lithium ion deposition to achieve lithium dendrite formation-free operation.

[0065] Figure 5 The cycling performance of QSSE-1 prepared in Example 1 in LiFPO4 / Li battery was as follows: after 300 cycles at 0.2C, the discharge specific capacity was still 132 mAh / g and the coulombic efficiency was 96.5%. This indicates that the lithium deposition and stripping behavior of the battery assembled by QSSE-1 is reversible during cycling, so the battery capacity loss is small. Therefore, QSSE-1 battery has excellent performance.

[0066] Example 2

[0067] (1) Mix and grind decaphenylaminosilsesquioxane (DPAS), transfer it into a centrifuge tube, add [BMIm]NTf2, sonicate for 1 min, and obtain clear solution I; the [BMIm]NTf2 and decaphenylaminosilsesquioxane are mixed in a mass ratio of 1:1 (g / g);

[0068] (2) Transfer p-xylbenzaldehyde into a centrifuge tube, add [BMIm]NTf2, and sonicate for 1 min to obtain clear solution II. The [BMIm]NTf2 and p-xylbenzaldehyde are mixed at a mass ratio of 1:1 (g / g).

[0069] (3) Mix the two solutions, Clarified Solution I and Clarified Solution II, and sonicate them. React at 120℃ for 3 to 4 days.

[0070] (4) Lithium bis(4-vinylphenyl)sulfonylimide, boron trifluoride ether, and 2,3-dichloro-5,6-dicyano-p-benzoquinone were added and reacted at a high temperature of 120°C to obtain a crude product of a three-dimensional organic covalent framework lithium salt containing cage-type silsesquioxane. The lithium bis(4-vinylphenyl)sulfonylimide, boron trifluoride ether, and 2,3-dichloro-5,6-dicyano-p-benzoquinone were mixed in a mass ratio of 10:1:1.

[0071] (5) After the reaction was completed, the mixture was cooled to room temperature, 10 mL of anhydrous ethanol was added, and the solid precipitate was collected by centrifugation. The solid product was washed several times with ethanol and acetone, and soaked in tetrahydrofuran three times. Fresh tetrahydrofuran was replaced after 8 hours, and a yellow powdery product, namely Q-COF-2, was collected.

[0072] (6) Sonicate Q-COF-2 with acetonitrile and stir for 3-4 hours to obtain mixed solution I, in which the mass fraction of Quiline-COFs is 10%;

[0073] (7) Under light-protected conditions, polyethylene oxide, polyethylene glycol acrylate, lithium bis(trifluoromethanesulfonyl)imide and azobisisobutyronitrile are stirred in acetonitrile for 7-10 hours to obtain mixed solution II, wherein the mass fraction of polyethylene oxide is 10%, the mass fraction of polyethylene glycol dimethacrylate is 5%, the mass fraction of polyethylene glycol methyl ether methacrylate is 1%, the mass fraction of azobisisobutyronitrile is 1%, and the molar fraction of lithium bis(trifluoromethanesulfonyl)imide relative to polyethylene oxide is 10%;

[0074] (8) Mix the two solutions I and II to form a mixture, and continue stirring for 2-4 hours under light-protected conditions;

[0075] (9) The mixture was poured into a polytetrafluoroethylene mold and reacted under ultraviolet light for 0.5 to 1 hour. It was then dried under vacuum at 30°C to obtain the quasi-solid electrolyte QSSE-2.

[0076] Example 3

[0077] (1) Mix and grind decaphenylaminosilsesquioxane (DPAS), transfer it into a centrifuge tube, add [BMIm]NTf2, sonicate for 1 min, and obtain clear solution I; the [BMIm]NTf2 and decaphenylaminosilsesquioxane are mixed in a mass ratio of 1:1 (g / g);

[0078] (2) Transfer p-diphenylformaldehyde into a centrifuge tube, add [BMIm]NTf2, sonicate for 1 min to obtain clear solution II; the [BMIm]NTf2 and p-diphenylformaldehyde are mixed at a mass ratio of 1:1 (g / g);

[0079] (3) Mix the two solutions, Clarity Solution I and Clarity Solution II, and sonicate them. React at 120℃ for 3 to 4 days.

[0080] (4) Add N-(trifluoromethylsulfonyl)trifluoromethanesulfonylimide fluoride, boron trifluoride ether, and 2,3-dichloro-5,6-dicyano-p-benzoquinone, and react at a high temperature of 120°C to obtain a crude product of a three-dimensional organic covalent framework lithium salt containing cage-type silsesquioxane. The bis(4-vinylphenyl)sulfonylimide lithium, boron trifluoride ether, and 2,3-dichloro-5,6-dicyano-p-benzoquinone are mixed in a mass ratio of 10:1:1.

[0081] (5) After the reaction was completed, the mixture was cooled to room temperature, 10 mL of anhydrous ethanol was added, and the solid precipitate was collected by centrifugation. The solid product was washed several times with ethanol and acetone, and soaked in tetrahydrofuran three times. Fresh tetrahydrofuran was replaced after 8 hours. A yellow powdery product, namely Q-COF-3, was collected.

[0082] (6) Sonicate Q-COF-3 with acetonitrile and stir for 3-4 hours to obtain mixed solution I, in which the mass fraction of Q-COFs is 10%;

[0083] (7) Under light-protected conditions, polyethylene oxide, polyethylene glycol acrylate, lithium bis(trifluoromethanesulfonyl)imide and azobisisobutyronitrile are stirred in acetonitrile for 7-10 hours to obtain mixed solution II, wherein the mass fraction of polyethylene oxide is 10%, the mass fraction of polyethylene glycol dimethacrylate is 5%, the mass fraction of polyethylene glycol methyl ether methacrylate is 1%, the mass fraction of azobisisobutyronitrile is 1%, and the molar fraction of lithium bis(trifluoromethanesulfonyl)imide relative to polyethylene oxide is 10%;

[0084] (8) Mix the two solutions and continue stirring for 2-4 hours in the dark to obtain a mixture;

[0085] (9) The mixture was poured into a polytetrafluoroethylene mold and reacted under ultraviolet light for 0.5 to 1 hour. It was then dried under vacuum at 30°C to obtain the quasi-solid electrolyte QSSE-3.

[0086] The above embodiments are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above embodiments. Any changes, modifications, substitutions, combinations, or simplifications made without departing from the spirit and principle of the present invention shall be considered equivalent substitutions and shall be included within the protection scope of the present invention.

Claims

1. A method of preparing a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte, characterized in that, The method comprises the following steps: (1) ultrasonicating a cage silsesquioxane-containing three-dimensional covalent organic framework lithium salt Q-COFs with acetonitrile, fully stirring to uniform, to obtain a mixed solution I; (2) fully stirring polyethylene oxide, acrylate polyethylene glycol, a lithium salt and a photoinitiator in acetonitrile to uniform under light shielding conditions, to obtain a mixed solution II; (3) mixing the mixed solution I and the mixed solution II, continuously stirring under light shielding conditions, to obtain a mixture; (4) pouring the mixture on a polytetrafluoroethylene mold, reacting under ultraviolet light, vacuum drying, to obtain a three-dimensional covalent organic framework quasi-solid electrolyte for lithium metal batteries; The Q-COFs in step (1) has the following structural formula: The preparation method of the Q-COFs comprises the following steps: a. mixing decaphenylamine silsesquioxane DAPS with a mass ratio of 1:1-2.5 and 1-butyl-3-methyl imidazole bisfluoromethyl sulfonimide salt [BMIm] NTf2 to obtain a clear solution I; b. mixing p-phenylenedimethylene formaldehyde TPA with [BMIm] NTf2 to obtain a clear solution II; c. mixing the clear solution I and the clear solution II, ultrasonicating and then high-temperature reacting to obtain a mixed solution; the high-temperature reaction is carried out at a temperature of 120 DEG C for 3-4 days; d. adding styrene sulfonimide lithium, boron trifluoride ether and 2,3-dichloro-5,6-dicyano p-benzoquinone with a molar ratio of 10-15:1:1 to the mixed solution obtained in step c., high-temperature reacting to obtain a Q-COFs crude product, and separating and purifying to obtain the Q-COFs; the high-temperature reaction is carried out at a temperature of 120 DEG C for 3-7 days.

2. The method for preparing a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte according to claim 1, characterized in that, The mass fraction of the Q-COFs in the mixed solution I is 5-15%; the sum of the mass fractions of the polyethylene oxide, the polyethylene glycol dimethacrylate, the polyethylene glycol methyl ether methacrylate and the photoinitiator in the mixed solution II is 10-20%, and the molar fraction of the lithium salt relative to the polyethylene oxide is 5-15%.

3. The method of claim 2, wherein the method is characterized by: The mass fraction of the Q-COFs in the mixed solution I is 10%; the mass fraction of the polyethylene oxide in the mixed solution II is 10%, the mass fraction of the polyethylene glycol dimethacrylate is 5%, the mass fraction of the polyethylene glycol methyl ether methacrylate is 1%, the mass fraction of the photoinitiator is 1%, and the molar fraction of the lithium salt relative to the polyethylene oxide is 10%.

4. The method for preparing a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte according to claim 1, characterized in that, The lithium salt is one of lithium bistrifluoromethylsulfonimide, lithium hexafluorophosphate, lithium hypochlorite and lithium chloride; and the photoinitiator is azobisisobutyronitrile or benzophenone.

5. The method for preparing a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte according to claim 1, characterized in that, The stirring time in step (1) is 3-4 h, the stirring time in step (2) is 7-10 h, the stirring time in step (3) is 2-4 h, and the reaction time in step (4) is 0.5-1 h, and the vacuum drying temperature is 30 DEG C.

6. The method for preparing a lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte according to claim 1, characterized in that, The styrene sulfonimide lithium is at least one of 4-styryl(trifluoromethylsulfonyl)sulfonimide lithium, bis(4-vinylphenyl)sulfonimide lithium or 4-styryl(trifluoromethyl(N-methylsulfonimide))sulfonimide lithium.

7. A lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte prepared according to the preparation method of any one of claims 1 to 6.

8. Use of the lithium metal three-dimensional covalent organic framework quasi-solid-state electrolyte according to claim 7 for the preparation of a lithium metal battery.

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