Nanofluid effect-enhanced lithium negative electrode artificial interface layer and its preparation method and application

Abstract

The present invention discloses a lithium negative electrode artificial interface layer with enhanced nanofluid effect and its preparation method and application, relating to the field of new energy battery technology, including: placing a monomer and a solvent in a container for reaction to prepare a QL-COF material; wherein the monomer includes 1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene and terephthalaldehyde; the QL-COF material is coated on a current collector to obtain a lithium negative electrode artificial interface layer with enhanced nanofluid effect. The beneficial effect of the present invention is that a nanofluid effect can occur inside a pore with a negatively charged interface and an aperture less than the Debye screening length, and the selectivity and diffusion capacity of lithium ions are enhanced by the pores of the QL-COF material, thereby realizing rapid single ion transmission, improving lithium ion transmission kinetics, and effectively improving the lithium ion migration number and lithium ion diffusion coefficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of new energy batteries, and in particular relates to a lithium negative electrode artificial interface layer with enhanced nanofluid effect, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of new energy technologies, especially in the field of new energy vehicles, high specific energy secondary battery energy storage technology has attracted great attention from researchers. The lithium metal negative electrode has a high theoretical specific capacity (3861mAh g -1 ) and extremely low operating potential (-3.04V, compared to the standard hydrogen electrode potential), lithium metal batteries are considered to be the next generation of new electrochemical energy storage technology with great development potential.

[0003] However, lithium metal batteries have serious dendrite growth problems and are difficult to cycle stably. Lithium dendrite growth can cause battery short circuits, which can lead to thermal runaway and potential fire and explosion risks. These safety issues have prevented lithium metal secondary batteries from being commercially applied. However, as an electrode material with extremely high potential energy density, researchers have never stopped their enthusiasm for metallic lithium. In the past decade, a variety of emerging strategies have been developed to inhibit the dendrite growth of metallic lithium negative electrodes and improve the safety and service life of batteries in anticipation of their ultimate practical application. They are mainly divided into the following four types:

[0004] (1) Alloy structures, such as LiAl, LiB, LiSi, LiSn, and LiC. These framework materials bind lithium, allowing it to exist as ions within the framework. This significantly reduces the dendrite problem and high reactivity of metallic lithium. However, alloy negative electrodes experience significant volume expansion, making multiple cycles difficult.

[0005] (2) Organic electrolyte and solid-liquid interface design. By forming a solid electrolyte interface film, metallic lithium can be stably present in a variety of organic solvents. Through the study of lithium salts, solvent additives and artificial interface films, the contact interface between metallic lithium and organic electrolyte has been greatly stabilized. However, it is difficult to completely resist the dendrite growth of metallic lithium anodes by relying solely on the improvement of liquid electrolytes.

[0006] (3) Solid electrolytes. Solid electrolytes include polymer electrolytes, inorganic electrolytes, and their mixtures. These electrolytes have a high mechanical modulus and can effectively inhibit dendrite growth, thereby improving the safety performance of the battery. However, the room temperature ionic conductivity of solid electrolytes is still relatively low, most of which are below 10 -8 ~10 -5 S cm -1 .

[0007] (4) Design of the negative electrode structure of metallic lithium. By designing an efficient negative electrode structure, the distribution of lithium ions on the negative electrode surface can be regulated, thereby inhibiting the growth of dendrites. However, the negative electrode structure regulation of metallic lithium secondary batteries is still in its infancy and preliminary exploration stage, and little is known about the deposition and precipitation behavior of metallic lithium.

[0008] In order to inhibit the growth of lithium dendrites, researchers have summarized a variety of models for the nucleation and growth of lithium dendrites, among which the space charge model is the most widely accepted theory to reveal the growth of lithium dendrites at this stage. Chazalviel et al. proved that the generation of dendrites is mainly caused by the formation of a space charge layer in a dilute solution. At high current density, when the lithium ion concentration on the electrode surface drops to zero, dendrites will appear. The initial time of dendrite growth is called Sand's time, and increasing the diffusion rate and migration number of lithium ions can effectively avoid Li + The emergence of the depletion region prolongs the Sand's time and inhibits the formation of dendrites. Summary of the Invention

[0009] In view of the serious dendrite growth problem of existing lithium metal batteries, which makes stable circulation difficult, the present invention is inspired by ion transport in biological systems and provides a lithium negative electrode artificial interface layer with enhanced nanofluid effect, as well as its preparation method and application.

[0010] The technical solutions adopted by the present invention to solve the above technical problems are as follows:

[0011] In a first aspect, the present invention provides a method for preparing a lithium negative electrode artificial interface layer with enhanced nanofluid effect, comprising placing a monomer and a solvent in a container for reaction to prepare a QL-COF material; wherein the monomer comprises 1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene and terephthalaldehyde;

[0012] The QL-COF material is coated on a current collector to obtain a lithium negative electrode artificial interface layer with enhanced nanofluid effect.

[0013] Preferably, the molar ratio of 1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene and terephthalaldehyde is 1:1-2:1-3.

[0014] Preferably, the solvent comprises n-butanol, pyruvic acid and acetic acid, the volume ratio of n-butanol to pyruvic acid is 1-3:0.1-0.3, and the concentration of acetic acid is 0.1-0.5 mmol / L.

[0015] Preferably, the preparation method further comprises: subjecting the reaction solution formed by the monomer and the solvent to ultrasonic treatment, degassing the solution through a freeze-vacuum-thaw cycle, and then sealing the container to allow the monomer and the solvent to react.

[0016] Preferably, the ultrasonic treatment time is 10 to 30 minutes, the temperature for the reaction of the monomer and the solvent is 100 to 200° C., and the reaction time is 24 to 72 hours.

[0017] Preferably, the preparation method further comprises: after the reaction is completed, cooling the container to room temperature, filtering and collecting the precipitate, and washing the precipitate with ethyl acetate, n-hexane and methanol;

[0018] The volume ratio of ethyl acetate, n-hexane and methanol is 1:1-2:1-3.

[0019] Preferably, the method further comprises: vacuum drying the washed precipitate at 50-80° C. for 12-24 hours to obtain a QL-COF material.

[0020] Preferably, coating the QL-COF material on the current collector includes: mixing the QL-COF material with a binder and then uniformly coating it on the current collector; wherein the mass ratio of the QL-COF material to the binder is 8 to 10:1, and the coating thickness is 1 to 5 microns.

[0021] In the second aspect, the present invention provides a lithium negative electrode artificial interface layer with enhanced nanofluid effect prepared by the above preparation method, wherein the pore size of the QL-COF material is 2.5 to 3.5 nm and the specific surface area is 1000 to 2000 m 2 / g.

[0022] In a third aspect, the present invention provides a lithium negative electrode artificial interface layer with enhanced nanofluid effect obtained by the above-mentioned preparation method or the use of the above-mentioned lithium negative electrode artificial interface layer with enhanced nanofluid effect in a lithium metal battery.

[0023] In the battery system, as the cycle progresses, C0 decreases and I also decreases. Therefore, the channel size h approaches λd, and a "nanofluid effect" occurs in the channel. Lithium ions are transported at a high rate in the channel, and the negatively charged channel repels anions. This selective and high-rate lithium ion transport will extend Sand's time and effectively avoid Li + The emergence of a depletion region enables uniform lithium deposition without dendrite growth.

[0024] The nanofluid effect-enhanced lithium negative electrode artificial interface layer of the present invention utilizes a negatively charged interface and a nanofluid effect inside a pore with an aperture smaller than the Debye screening length, thereby enhancing the selectivity and diffusion capacity of lithium ions through the pores of the QL-COF material, thereby achieving rapid single ion transmission, improving lithium ion transmission kinetics, and effectively increasing the lithium ion migration number and lithium ion diffusion coefficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1is the XRD pattern of the QL-COF provided in Example 1 of the present invention;

[0026] Figure 2 is a SEM image of the QL-COF provided in Example 1 of the present invention;

[0027] Figure 3 is a pore size distribution diagram of the QL-COF provided in Example 1 of the present invention;

[0028] Figure 4 1 is a performance diagram of the lithium-copper battery assembled in Example 1 of the present invention and Comparative Example 1;

[0029] Figure 5 is a SEM image of the QL-COF provided in Example 2 of the present invention;

[0030] Figure 6 This is a performance diagram of a lithium-copper battery assembled with the QL-COF provided in Example 2 of the present invention;

[0031] Figure 7 is a SEM image of the QL-COF provided in Example 3 of the present invention. DETAILED DESCRIPTION

[0032] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0033] The present invention is inspired by ion transport in biological systems and provides a method for preparing a lithium negative electrode artificial interface layer with enhanced nanofluid effect and its application.

[0034] Since the beginning of this century, rapid advances in nanotechnology have brought new opportunities to lithium metal batteries, including the design of lithium metal anode structures and lithium metal surface interface layers. By designing efficient anode structures and lithium metal surface interface layers, the distribution of lithium ions on the anode surface can be regulated, accelerating lithium ion transport and extending the Sand's time, thereby inhibiting dendrite growth. When these strategies are coupled with efficient liquid electrolyte additives and solid-state electrolytes, the coulombic efficiency of lithium metal batteries is expected to be increased to 99.9%, thereby realizing the practical application of lithium metal batteries.

[0035] One embodiment of the present invention provides a method for preparing a lithium negative electrode artificial interface layer with enhanced nanofluid effect, comprising:

[0036] Monomers and a solvent are placed in a container, wherein the monomers include 1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene, and terephthalaldehyde, and the reaction solution is subjected to ultrasonic, degassing, and heating treatment to prepare a QL-COF material;

[0037] The QL-COF material is coated on a current collector to obtain a lithium negative electrode artificial interface layer with enhanced nanofluid effect.

[0038] In some embodiments, the monomers (1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene and terephthalaldehyde, etc.) and the solvent are placed in a Pyrex tube, and the molar ratio of 1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene and terephthalaldehyde is 1:1 to 2:1 to 3; optionally, the molar ratio of 1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene and terephthalaldehyde is (1:1:1), (1:1:2), (1:1:3), (1:2:1), (1:2:2), (1:2:3), (1:1.5:1), (1:1.5:2), (1:1.5:2.5) or (1:1.5:3), etc.

[0039] In some embodiments, the current collector is copper foil.

[0040] In some embodiments, the solvent may be selected from n-butanol, pyruvic acid and acetic acid, etc., the feed volume ratio of n-butanol and pyruvic acid is 1-3:0.1-0.3, and the feed concentration of acetic acid is 0.1-0.5 mmol / L; optionally, the feed volume ratio of n-butanol and pyruvic acid is (1:0.3), (1:0.2), (1:0.1), (2:0.1), (2:0.2), (2:0.3), (3:0.1) or (3:0.2), etc., and the feed concentration of acetic acid is 0.1 mmol / L, 0.2 mmol / L, 0.3 mmol / L, 0.4 mmol / L or 0.5 mmol / L, etc.

[0041] In some embodiments, the process of ultrasonicating, degassing and heating the reaction liquid includes: ultrasonicating the reaction liquid, degassing it through a freeze-vacuum-thaw process after it is evenly dispersed, and then sealing the Pyrex tube and placing it at a certain temperature for reaction.

[0042] The ultrasonic time is 10 to 30 minutes, and specifically 10 minutes, 15 minutes, 20 minutes, 25 minutes or 30 minutes can be selected, and then degassing is performed through three cycles of freezing-vacuuming-thawing.

[0043] The reaction temperature is 100-200° C., and the reaction time is 24-72 hours. Specifically, the reaction temperature can be 100° C., 120° C., 140° C., 150° C., 160° C., 180° C., or 200° C., and the treatment time can be 24 hours, 32 hours, 36 hours, 48 ​​hours, 60 hours, or 72 hours.

[0044] In the above embodiment, if necessary, the reaction system may be subjected to a stirring and dispersion treatment to improve the reaction efficiency and particle dispersibility.

[0045] In some embodiments, after the reaction is completed, the Pyrex tube is cooled to room temperature, the precipitate is collected by filtration, and then the high-boiling point solvent or oligomers are removed by solvent exchange by washing. The washing agent can be ethyl acetate, n-hexane and methanol.

[0046] The volume ratio of ethyl acetate, n-hexane and methanol is 1:1 to 2:1 to 3; optionally, the volume ratio of ethyl acetate, n-hexane and methanol is (1:1:1), (1:1:2), (1:1:3), (1:1.5:1), (1:1.5:2), (1:1.5:3), (1:2:1), (1:2:2) or (1:2:3), etc.

[0047] In some embodiments, the washed precipitate is vacuum dried at a temperature of 50-80°C for a treatment time of 12-24 hours. Possible drying temperatures include 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, or 80°C, and treatment times include 12 hours, 15 hours, 18 hours, 20 hours, or 24 hours.

[0048] In some embodiments, the QL-COF material is coated on the copper foil with a thickness of 1 to 5 microns, and the mass ratio of the QL-COF material to the binder is 8 to 10:1.

[0049] Another embodiment of the present invention provides a lithium negative electrode artificial interface layer with enhanced nanofluid effect obtained by the above preparation method, wherein the pore size of the QL-COF material is 2.5 to 3.5 nm and the specific surface area is 1000 to 2000 m 2 / g, high crystallinity and uniform particles.

[0050] The nanofluidic-enhanced lithium anode artificial interface layer material of the present invention features small pores and a large specific surface area. Its pores are smaller than the Debye screening length, and the transport behavior of lithium ions within the nanochannels differs significantly from that of the electrolyte solution, being affected only by surface charge. Lithium ion transport within the nanochannels exhibits a typical nanofluidic effect, meaning that ionic conductivity remains nearly constant regardless of the ion concentration of the electrolyte solution.

[0051] Another embodiment of the present invention provides the use of the lithium negative electrode artificial interface layer obtained by the above-mentioned preparation method or with the above-mentioned nanofluid effect enhancement in a lithium metal battery.

[0052] The application of the nanofluid effect-enhanced lithium negative electrode artificial interface layer obtained by the present invention in lithium metal batteries will accelerate the transmission of lithium ions and extend the Sand's time. After testing, the lithium ion migration number increased by more than 2 to 4 times, and the lithium ion diffusion coefficient increased by 10 4 ~10 6 times, delaying the appearance of dendrites and achieving stable long-term cycling of lithium metal batteries.

[0053] The present invention is further described below with reference to the following examples.

[0054] Example 1:

[0055] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0056] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (48 mg), o-dichlorobenzene (1.5 mL), a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0057] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 120°C for 72 hours.

[0058] Step 3. After the reaction is completed, the sealed tube is cooled to room temperature, the precipitate is collected by filtration, and then the high-boiling point solvent or oligomers are removed by solvent exchange (ethyl acetate, n-hexane and methanol) by washing. The feed volume of ethyl acetate, n-hexane and methanol is 30mL:30mL:30mL. Finally, the obtained solid is vacuum dried at 60°C for 12h to obtain QL-COF.

[0059] Step 4. The obtained QL-COF is coated on copper foil with a thickness of 3 microns. The mass ratio of QL-COF material to binder is 9:1. The battery is assembled with lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0060] The obtained QL-COF powder was subjected to X-ray diffraction, and the obtained XRD pattern was as follows: Figure 1 As shown, it shows that QL-COF with high crystallinity is obtained.

[0061] The obtained QL-COF powder was observed by scanning electron microscopy, and the obtained SEM photos are as follows: Figure 2 As shown by Figure 2 It can be seen that the formed QL-COF particles are relatively uniform.

[0062] The obtained QL-COF powder was subjected to nitrogen adsorption and desorption experiments, and the pore size distribution diagram was obtained as shown in the figure below. Figure 3 As shown by Figure 3 It can be seen that the pore size of the formed QL-COF is mainly distributed around 3 nm.

[0063] The lithium metal deposition / stripping performance of the obtained QL-COF powder was tested, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The charge and discharge capacity of the battery was tested, and the coulombic efficiency was calculated. The obtained coulombic efficiency ratio curve is shown as follows: Figure 4 As shown, it is 99.7%.

[0064] Example 2:

[0065] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0066] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (1.5 mL), a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0067] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 120°C for 72 hours.

[0068] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0069] Step 4. The obtained QL-COF is coated on copper foil. The thickness of the QL-COF material coated on the copper foil is 2 microns. The mass ratio of QL-COF material to binder is 8.5:1. The battery is assembled with a lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0070] The obtained QL-COF powder was observed by scanning electron microscopy, and the obtained SEM photos are as follows: Figure 5 As shown by Figure 5 It can be seen that the formed QL-COF particles are relatively uniform.

[0071] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The charge and discharge capacity of the battery was tested, and the coulombic efficiency was calculated. The results are as follows: Figure 6 As shown, it is 99.5%.

[0072] Example 3:

[0073] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0074] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (3 mL), and a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0075] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 120°C for 72 hours.

[0076] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0077] Step 4. The obtained QL-COF is coated on copper foil with a thickness of 3 microns. The mass ratio of QL-COF material to binder is 9:1. The battery is assembled with lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0078] The obtained QL-COF powder was observed by scanning electron microscopy, and the obtained SEM photos are as follows: Figure 6 As shown by Figure 7 It can be seen that the formed QL-COF particles are relatively uniform.

[0079] The lithium metal deposition / stripping performance of the obtained QL-COF powder was tested by the following method:

[0080] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The battery's charge and discharge capacity was tested, and the coulombic efficiency was calculated.

[0081] The coulombic efficiency was calculated to be 99.42%.

[0082] Example 4:

[0083] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0084] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (3 mL), and a mixed solution of n-butanol (1.5 mL), pyruvic acid (200 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0085] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 120°C for 72 hours.

[0086] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0087] Step 4. The obtained QL-COF is coated on copper foil. The thickness of the QL-COF material coated on the copper foil is 4 microns. The mass ratio of QL-COF material to binder is 9.5:1. The battery is assembled with a lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0088] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The battery's charge and discharge capacity was tested, and the coulombic efficiency was calculated.

[0089] The coulombic efficiency was calculated to be 99.45%.

[0090] Example 5:

[0091] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0092] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (1.5 mL), a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0093] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 140°C for 48 hours.

[0094] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0095] Step 4. The obtained QL-COF is coated on copper foil. The thickness of the QL-COF material coated on the copper foil is 5 microns. The mass ratio of QL-COF material to binder is 10:1. The battery is assembled with a lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0096] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The battery's charge and discharge capacity was tested, and the coulombic efficiency was calculated.

[0097] The coulombic efficiency was calculated to be 99.41%.

[0098] Example 6:

[0099] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0100] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (1.5 mL), a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0101] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 140°C for 72 hours.

[0102] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0103] Step 4. The obtained QL-COF is coated on copper foil. The thickness of the QL-COF material coated on the copper foil is 1.5 microns. The mass ratio of QL-COF material to binder is 9:1. The battery is assembled with a lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0104] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The battery's charge and discharge capacity was tested, and the coulombic efficiency was calculated.

[0105] The coulombic efficiency was calculated to be 99.43%.

[0106] Example 7:

[0107] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0108] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (1.5 mL), a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0109] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 160°C for 48 hours.

[0110] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0111] Step 4. Coat the obtained QL-COF on copper foil. The thickness of the QL-COF material coated on the copper foil is 2.5 microns. The mass ratio of QL-COF material to binder is 9:1. The battery is assembled with a lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0112] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The battery's charge and discharge capacity was tested, and the coulombic efficiency was calculated.

[0113] The coulombic efficiency was calculated to be 99.6%.

[0114] Example 8:

[0115] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0116] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (1.5 mL), a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0117] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 180°C for 48 hours.

[0118] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0119] Step 4. The obtained QL-COF is coated on copper foil. The thickness of the QL-COF material coated on the copper foil is 3.5 microns. The mass ratio of QL-COF material to binder is 9:1. The battery is assembled with a lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0120] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The battery's charge and discharge capacity was tested, and the coulombic efficiency was calculated.

[0121] The coulombic efficiency was calculated to be 99.65%.

[0122] Example 9:

[0123] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0124] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (1.5 mL), a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube and dissolve to obtain a reaction solution, which is then ultrasonically treated for 10 min.

[0125] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 200°C for 48 hours.

[0126] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0127] Step 4. Coat the obtained QL-COF on copper foil. The thickness of the QL-COF material coated on the copper foil is 4.5 microns. The mass ratio of QL-COF material to binder is 9:1. The battery is assembled with a lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0128] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The battery's charge and discharge capacity was tested, and the coulombic efficiency was calculated.

[0129] The coulombic efficiency was calculated to be 99.43%.

[0130] Example 10:

[0131] This embodiment is used to illustrate the preparation method of the lithium negative electrode artificial interface layer with enhanced nanofluid effect disclosed in the present invention, which includes the following steps:

[0132] Step 1. Place 1,3,5-tris(4-aminophenyl)benzene (48 mg), terephthalaldehyde (96 mg), o-dichlorobenzene (1.5 mL), a mixed solution of n-butanol (1.5 mL), pyruvic acid (100 μL), and acetic acid (50 μL) in a Pyrex tube, dissolve to obtain a reaction solution, and ultrasonicate the reaction solution for 10 min.

[0133] Step 2: After uniform dispersion, degas the mixture by freezing, vacuumizing, and thawing three times. The tube is then sealed and placed in a high-temperature reaction at 200°C for 72 hours.

[0134] Step 3. After the reaction, the sealed tube was cooled to room temperature, and the precipitate was collected by filtration. The high-boiling point solvent or oligomers were removed by washing and solvent exchange (ethyl acetate, n-hexane, and methanol). The feed volumes of ethyl acetate, n-hexane, and methanol were 30 mL: 30 mL: 30 mL. The resulting solid was vacuum dried at a temperature of 60°C for 12 hours to obtain QL-COF.

[0135] Step 4. The obtained QL-COF is coated on copper foil. The thickness of the QL-COF material coated on the copper foil is 1 micron. The mass ratio of QL-COF material to binder is 8:1. The battery is assembled with a lithium sheet as the counter electrode. The electrolyte is a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0136] The obtained QL-COF powder was tested for lithium metal deposition / stripping performance, and the coulombic efficiency of the metal lithium battery was tested using a lithium-copper battery system. The battery's charge and discharge capacity was tested, and the coulombic efficiency was calculated.

[0137] The coulombic efficiency was calculated to be 99.35%.

[0138] Comparative Example 1:

[0139] Ordinary copper foil (not coated with QL-COF material) was used to assemble the battery with lithium sheet as the counter electrode. The electrolyte was a commercial ether electrolyte (1.0 mol / L lithium bis(trifluoromethanesulfonyl)imide dissolved in a mixed solvent of 1,3-dioxolane / 1,2-dimethoxyethane with a volume ratio of 1:1).

[0140] The obtained Coulomb efficiency curve is as follows Figure 4 As shown, the Coulombic efficiency is 99.3%.

[0141] It can be seen from the above test results that compared with the lithium-copper battery before the artificial interface layer is modified (Comparative Example 1), the coulombic efficiency of the lithium-copper battery after the artificial interface layer is modified in Examples 1 to 10 of the present invention is improved, from a maximum of 99.3% to 99.7% and a minimum of 99.35%, indicating that the QL-COF powder prepared in Examples 1 to 10 has excellent lithium deposition / stripping performance.

[0142] Comparative Example 2

[0143] The difference from Example 1 is that 1,3,5-tris(4-aminophenyl)benzene is not added; the other conditions are the same as Example 1.

[0144] The coulombic efficiency obtained was 70%.

[0145] It can be seen from the above test results that the coulombic efficiency of Comparative Example 2 is lower than that of Example 1, indicating that not adding 1,3,5-tris(4-aminophenyl)benzene will affect the performance of the battery, that is, 1,3,5-tris(4-aminophenyl)benzene will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0146] Comparative Example 3

[0147] The difference from Example 1 is that no terephthalaldehyde is added; otherwise, the same as Example 1.

[0148] The coulombic efficiency obtained was 71%.

[0149] The above test results show that the coulombic efficiency of Comparative Example 3 is lower than that of Example 1, indicating that not adding terephthalaldehyde will affect the performance of the battery, that is, terephthalaldehyde will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0150] Comparative Example 4

[0151] The difference from Example 1 is that o-dichlorobenzene is not added; the other steps are the same as Example 1.

[0152] The coulombic efficiency obtained was 73%.

[0153] The above test results show that the coulombic efficiency of Comparative Example 4 is lower than that of Example 1, indicating that not adding o-dichlorobenzene will affect the performance of the battery, that is, o-dichlorobenzene will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0154] Comparative Example 5

[0155] The difference from Example 1 is that the amount of 1,3,5-tris(4-aminophenyl)benzene added is changed to 30 mg; the rest is the same as Example 1.

[0156] The coulombic efficiency obtained was 80%.

[0157] It can be seen from the above test results that the coulombic efficiency of Comparative Example 5 is lower than that of Example 1, indicating that too little addition of 1,3,5-tris(4-aminophenyl)benzene will affect the performance of the battery, that is, too little addition of 1,3,5-tris(4-aminophenyl)benzene will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0158] Comparative Example 6

[0159] The difference from Example 1 is that the amount of 1,3,5-tris(4-aminophenyl)benzene added is changed to 60 mg; the rest is the same as Example 1.

[0160] The resulting coulombic efficiency was 75%.

[0161] It can be seen from the above test results that the coulombic efficiency of Comparative Example 6 is lower than that of Example 1, indicating that too much addition of 1,3,5-tris(4-aminophenyl)benzene will also affect the performance of the battery. This is because too much addition of 1,3,5-tris(4-aminophenyl)benzene will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0162] Comparative Example 7

[0163] The difference from Example 1 is that the amount of terephthalaldehyde added is changed to 30 mg; the other steps are the same as in Example 1.

[0164] The coulombic efficiency obtained was 74%.

[0165] The above test results show that the coulombic efficiency of Comparative Example 7 is lower than that of Example 1, indicating that too little addition of terephthalaldehyde will affect the performance of the battery. In other words, too little addition of terephthalaldehyde will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0166] Comparative Example 8

[0167] The difference from Example 1 is that the amount of terephthalaldehyde added is changed to 110 mg; the other steps are the same as in Example 1.

[0168] The obtained coulombic efficiency was 78.2%.

[0169] The above test results show that the coulombic efficiency of Comparative Example 8 is lower than that of Example 1, indicating that excessive addition of terephthalaldehyde will also affect the performance of the battery. This is because excessive addition of terephthalaldehyde will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0170] Comparative Example 9

[0171] The difference from Example 1 is that the amount of o-dichlorobenzene added is changed to 0.5 mL; the rest is the same as Example 1.

[0172] The obtained coulombic efficiency was 82.4%.

[0173] The above test results show that the coulombic efficiency of Comparative Example 9 is lower than that of Example 1, indicating that too little addition of o-dichlorobenzene will affect the performance of the battery, that is, too little addition of o-dichlorobenzene will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0174] Comparative Example 10

[0175] The difference from Example 1 is that the amount of o-dichlorobenzene added is changed to 5 mL; the rest is the same as Example 1.

[0176] The obtained coulombic efficiency was 84.4%.

[0177] The above test results show that the coulombic efficiency of Comparative Example 10 is lower than that of Example 1, indicating that excessive addition of o-dichlorobenzene will also affect the performance of the battery. This is because excessive addition of o-dichlorobenzene will affect the formation of the nanofluid effect, thereby affecting the selectivity and diffusion capacity of lithium ions.

[0178] Comparative Example 11

[0179] The difference from Example 1 is that no solvent n-butanol is added; the rest is the same as Example 1.

[0180] The resulting coulombic efficiency was 75%.

[0181] It can be seen from the above test results that the coulombic efficiency of Comparative Example 11 is lower than that of Example 1, indicating that adding only pyruvic acid and acetic acid solvents without adding n-butanol solvent will affect the performance of the battery.

[0182] Comparative Example 12

[0183] The difference from Example 1 is that no pyruvic acid solvent is added; the rest is the same as Example 1.

[0184] The coulombic efficiency obtained was 77%.

[0185] It can be seen from the above test results that the coulombic efficiency of Comparative Example 12 is lower than that of Example 1, indicating that adding only n-butanol and acetic acid solvents without adding pyruvic acid solvent will affect the performance of the battery.

[0186] Comparative Example 13

[0187] The difference from Example 1 is that no acetic acid solvent is added; the other aspects are the same as Example 1.

[0188] The coulombic efficiency obtained was 78%.

[0189] It can be seen from the above test results that the coulombic efficiency of Comparative Example 13 is lower than that of Example 1, indicating that adding only n-butanol and pyruvic acid solvents without adding acetic acid solvent will affect the performance of the battery.

[0190] Comparative Example 14

[0191] The difference from Example 1 is that the amount of n-butanol added is changed to 0.5 mL; the rest is the same as Example 1.

[0192] The obtained coulombic efficiency was 81.2%.

[0193] It can be seen from the above test results that the coulombic efficiency of Comparative Example 14 is lower than that of Example 1, indicating that too little addition of n-butanol will affect the performance of the battery.

[0194] Comparative Example 15

[0195] The difference from Example 1 is that the amount of n-butanol added is changed to 5 mL; the rest is the same as Example 1.

[0196] The coulombic efficiency obtained was 80%.

[0197] It can be seen from the above test results that the coulombic efficiency of Comparative Example 15 is lower than that of Example 1, indicating that too much addition of n-butanol will affect the performance of the battery.

[0198] Comparative Example 16

[0199] The difference from Example 1 is that the amount of pyruvic acid added is changed to 50 μL; the rest is the same as Example 1.

[0200] The obtained coulombic efficiency was 81.5%.

[0201] It can be seen from the above test results that the coulombic efficiency of Comparative Example 16 is lower than that of Example 1, indicating that too little addition of pyruvic acid will affect the performance of the battery.

[0202] Comparative Example 17

[0203] The difference from Example 1 is that the amount of pyruvic acid added is changed to 500 μL; the rest is the same as Example 1.

[0204] The obtained coulombic efficiency was 82.6%.

[0205] It can be seen from the above test results that the coulombic efficiency of Comparative Example 17 is lower than that of Example 1, indicating that too much addition of pyruvic acid will affect the performance of the battery.

[0206] Comparative Example 18

[0207] The difference from Example 1 is that the amount of acetic acid added is changed to 10 μL; the rest is the same as Example 1.

[0208] The coulombic efficiency obtained was 85%.

[0209] It can be seen from the above test results that the coulombic efficiency of Comparative Example 18 is lower than that of Example 1, indicating that too little addition of acetic acid will affect the performance of the battery.

[0210] Comparative Example 19

[0211] The difference from Example 1 is that the amount of acetic acid added is changed to 300 μL; the rest is the same as Example 1.

[0212] The coulombic efficiency obtained was 76%.

[0213] It can be seen from the above test results that the coulombic efficiency of Comparative Example 19 is lower than that of Example 1, indicating that too much acetic acid added will affect the performance of the battery.

[0214] In summary, the nanofluid effect-enhanced lithium negative electrode artificial interface layer material of the present invention has the characteristics of small pore size, large specific surface area, high crystallinity and uniform particles. When used in lithium metal batteries, it can improve the lithium ion migration number and lithium ion diffusion coefficient, delay the appearance of dendrites, and achieve stable long-term cycling of lithium metal batteries.

[0215] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a lithium negative electrode for a lithium metal battery, characterized in that: include: The monomers and solvent are placed in a container for reaction, wherein the monomers include 1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene and terephthalaldehyde, and the feeding molar ratio of the 1,3,5-tris(4-aminophenyl)benzene, o-dichlorobenzene and terephthalaldehyde is 1:1-2:1-3; the solvent includes n-butanol, pyruvic acid and acetic acid, and the feeding volume ratio of the n-butanol to the pyruvic acid is 1-3:0.1-0.3, and the feeding concentration of the acetic acid is 0.1-0.5 mmol / L; The step of placing the monomer and the solvent in a container for reaction comprises ultrasonically treating the reaction solution formed by the monomer and the solvent, degassing the solution through a freeze-vacuum-thaw cycle, and then sealing the container to allow the monomer and the solvent to react. The ultrasonic treatment time is 10-30 minutes, the temperature for the reaction of the monomer and the solvent is 100-200° C., and the reaction time is 24-72 hours. After the reaction, the container is cooled to room temperature, the precipitate is collected by filtration, and the precipitate is washed with ethyl acetate, n-hexane and methanol, and the volume ratio of ethyl acetate, n-hexane and methanol is 1:1-2:1-3. The washed precipitate is vacuum dried at 50-80° C. for 12-24 hours to obtain a QL-COF material. The QL-COF material is mixed with a binder and then coated on copper foil to obtain a lithium negative electrode for a lithium metal battery; The mass ratio of the QL-COF material to the binder is 8-10:1, and the coating thickness is 1-5 microns. The pore size of the QL-COF material is 2.5-3.5 nm, and the specific surface area is 1000-2000 m 2 / g.

2. Use of the lithium negative electrode prepared by the method of claim 1 in a lithium metal battery.

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