A method for functionalizing lithium battery separators based on COFs by regulating catalyst concentration

Abstract

The application discloses a kind of based on catalyst concentration regulation lithium battery separator COFs functionalization method, belong to lithium battery separator field, the application a kind of based on catalyst concentration regulation lithium battery separator COFs functionalization method, comprising: S1, preparation solution: in dichloromethane dissolves trimesic aldehyde, obtains solution A;Catalyst is dissolved in deionized water, obtains solution B;In N, N-dimethylformamide dissolves tri (4-amino phenyl) amine, obtains solution C;S2, in-situ COFs functionalization: sequentially superimposed solution A, solution B, solution C form three-layer system, lithium battery commercial separator is placed in solution A and solution B interface and is reacted, after reaction, after drying, COFs functionalization separator is prepared, solve the uneven distribution of functional material in the prior art, internal pore size filling is less, high content functional material load difficult and so on.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of lithium battery separator, in particular to a method for regulating COFs functionalization of lithium battery separator based on catalyst concentration. BACKGROUND

[0002] The growth mode of COFs in the existing technology is difficult to regulate, and there are problems such as uneven distribution of functional materials, insufficient internal pore filling, and difficulty in loading high content of functional materials: (1) uneven distribution of functional materials: traditional methods cannot control the penetration depth of COFs particles, resulting in insufficient internal pore filling of the separator; (2) catalyst concentration influence is ambiguous: there is no theoretical basis for regulating the layered growth and mechanical strength of COFs through catalyst concentration; (3) high loading performance is insufficient: low concentration of catalyst leads to surface modification, and high concentration causes the separator to float or the structure to be loose.

[0003] Chinese patent with publication number CN119241789A discloses a BrCOFs material, a preparation method thereof, and a preparation method of a lithium metal battery covalent organic framework material interface film. The method dissolves 1,3,5-tris(4-aminophenyl)benzene and 2,5-dibromobenzene-1,4-dimethyl formaldehyde in an organic solvent, then adds acetic acid dropwise, and makes the reaction mixture react under stirring. After the reaction is completed, filtration, washing, and centrifugal separation and drying are performed to obtain Br-COFs. However, the above method coats the prepared Br-COFs slurry on the surface of a copper foil to obtain a Br-COFs film covered Cu electrode. The modified material cannot penetrate into the interior of the separator, the penetration depth of COFs particles cannot be controlled, and the internal pore filling of the separator is insufficient. Therefore, a precise regulation method is needed to optimize the pore filling degree of the separator and the COFs functionalization of the separator. SUMMARY

[0004] To alleviate or partially alleviate the above technical problems, the solution of the present application is as follows:

[0005] A method for regulating COFs functionalization of lithium battery separator based on catalyst concentration, comprising the following steps:

[0006] S1, solution preparation: dissolving trimesic acid in dichloromethane to obtain solution A; dissolving catalyst in deionized water to obtain solution B; dissolving tris(4-aminophenyl)amine in N,N-dimethylformamide to obtain solution C;

[0007] S2, in-situ COFs functionalization: sequentially superimposing solution A, solution B, and solution C to form a three-layer system, placing a commercial lithium battery separator at the interface between solution A and solution B for reaction, washing after reaction, and drying to obtain a COFs functionalized separator.

[0008] This method constructs an oil-water-oil three-layer system, and then controls the nucleation mode and reaction rate of COFs on the membrane based on the catalyst concentration. This allows COFs to uniformly fill the membrane pores in a layered, penetrating growth manner, achieving uniform COFs formation in the membrane bulk phase and improving the mechanical strength of the membrane. It has the advantages of simple method, low cost and high efficiency.

[0009] Preferably, the catalyst in solution B of step S1 is formic acid, acetic acid, or propionic acid.

[0010] More preferably, the catalyst in solution B of step S1 is acetic acid.

[0011] Adding water-soluble organic acids as catalysts can accelerate the reaction.

[0012] Preferably, the concentration of acetic acid in solution B in step S1 is 1-9 mol / L. -1 .

[0013] The correspondence between acetic acid concentration and COF growth mode is: 1-5 mol L -1 At that time, COFs formed a non-uniform layer on the membrane surface, with an internal pore filling rate of 40-60%; 6 mol L -1 At that time, COFs form a dense layer on the membrane surface and uniformly fill the internal pores of the membrane through a layer-by-layer growth mode, with a filling rate of 80-90%; 7-9 mol L -1 When COFs form a loose layer, the membrane is easy to float, and the internal pore filling rate is <50%.

[0014] Preferably, the concentration of acetic acid in solution B in step S1 is 6 mol / L. -1 The concentration of pyromellitic aldehyde in solution A in step S1 is 4.2 mmol / L. -1 The concentration of tris(4-aminophenyl)amine in solution C in step S1 is 4.2 mmol / L. -1 .

[0015] Preferably, the commercial lithium battery separator in step S2 is selected from one of polypropylene separator (PP), polyethylene separator (PE), or PP / PE composite separator.

[0016] Preferably, the reaction time in step S2 is 5-10 days.

[0017] Preferably, the washing in step S2 is performed by sequentially washing with dichloromethane, ethanol, acetone and N,N-dimethylformamide.

[0018] Preferably, the reaction time in step S2 is 7 days; the drying temperature in step S2 is 60 °C and the drying time is 12 h; the volume ratio of solution A, solution B and solution C in step S2 is 8:2:5.

[0019] The technical solution of this invention has one or more of the following beneficial technical effects:

[0020] (1) By precisely controlling the concentration of acetic acid catalyst, a quantitative correlation mechanism between concentration and COF growth mode was established, which solved the problem of uncontrollable growth mode of functional materials in traditional methods.

[0021] (2) At 6 mol L -1 At certain concentrations, COFs uniformly fill the internal pores of the membrane in a layered penetration mode, increasing the filling rate by 40-50% compared to traditional surface modification methods, forming a "continuous functional network of surface and pores," which can significantly enhance the electrochemical performance of the membrane; using 6 mol L... -1 The optimal growth mode at acetic acid concentration shows a synergistic effect between the chemisorption of tertiary amine groups (-N⁻) in the COF structure and the physical confinement of narrow pores, which has the potential to improve the adsorption of polysulfides in lithium-sulfur batteries and reduce interfacial diffusion resistance. A balance between functionalization and mechanical strength is achieved through catalyst concentration control, with 6 mol L⁻¹ being the optimal growth mode. -1 The COFs functionalized separator prepared at the concentration still maintains structural integrity and high mechanical strength after bending and scratching, breaking through the bottleneck of insufficient mechanical properties of interfacial self-assembled membranes and meeting the stringent requirements of battery assembly for the mechanical properties of separators.

[0022] (3) This method uses Lewis acid acetic acid catalyst, the raw materials are readily available and the process is simple. It is compatible with commercial membranes such as polypropylene and polyethylene. Furthermore, the performance can be optimized from low load to high load through concentration gradient control, providing a low-cost and easily scalable technical path for the industrial production of functional membranes.

[0023] Furthermore, other beneficial effects of the present invention will be mentioned in the specific embodiments. Attached Figure Description

[0024] Figure 1 The images show the morphology of the diaphragm before and after modification in this scheme.

[0025] Figure 2 Field emission scanning electron microscope image of COF-functionalized septum;

[0026] Figure 3 The diagram shows the mechanical strength test results of the COFs-functionalized diaphragm in Example 2. Detailed Implementation

[0027] In order to make the objects, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor fall within the scope of protection of the present application.

[0028] In order to clearly describe the technical solutions of the embodiments of the present application, in the embodiments of the present application, the terms "first", "second" and the like are used to distinguish the same items or similar items with basically the same functions and effects. Those skilled in the art can understand that the terms "first", "second" and the like do not limit the quantity and execution order.

[0029] In the prior art, there are problems such as uneven distribution of functional materials, less internal pore filling, and difficulty in loading high content of functional materials. To solve the above problems, the present scheme provides a method for functionalizing COFs of lithium battery separators based on catalyst concentration control, comprising the following steps:

[0030] S1, solution preparation: dissolving trimesic aldehyde in dichloromethane to obtain solution A; dissolving a catalyst in deionized water to obtain solution B; dissolving tris(4-aminophenyl)amine in N,N-dimethylformamide to obtain solution C;

[0031] In the illustrated embodiment, the catalyst in solution B is acetic acid, and the catalyst can also be selected from water-soluble organic acids such as formic acid or propionic acid. The organic acid can catalyze the reaction of trimesic aldehyde and tris(4-aminophenyl)amine to proceed faster.

[0032] The concentration of the catalyst is 1-9 mol / L -1 In the illustrated embodiment, the concentration of the catalyst is 3 mol / L -1 , 6 mol / L -1 or 9 mol / L -1 .

[0033] In the illustrated embodiment, the concentration of trimesic aldehyde in solution A is 4.2 mmol / L -1 ; and the concentration of tris(4-aminophenyl)amine in solution C is 4.2 mmol / L -1 .

[0034] S2, in-situ COFs functionalization: sequentially superimpose solution A, solution B and solution C to form a three-layer system, place a lithium battery commercial separator at the interface between solution A and solution B for reaction, wash after reaction, and dry to obtain a COFs functionalized separator.

[0035] In the illustrated embodiment, the lithium battery commercial separator in step S2 is selected from one of a polypropylene separator, a polyethylene separator, or a PP / PE composite separator.

[0036] In the illustrated embodiment, the reaction time is 5-10 days, the drying temperature in step S2 is 60 °C, and the drying time is 12 h.

[0037] In the illustrated embodiment, the washing is sequentially washing with dichloromethane, ethanol, acetone, and N,N-dimethylformamide.

[0038] The amounts of solution A, solution B, and solution C can be adjusted according to the reaction. In the illustrated embodiment, the volume ratio of solution A, solution B, and solution C is 8:2:5.

[0039] Hereinafter, examples of the present application will be described. The examples described below are exemplary and are for the purpose of explaining the present application only and are not to be understood as limiting the present application. In the examples, specific techniques or conditions not noted are performed in accordance with techniques or conditions described in the literature in the field or in accordance with product instructions. The reagents or instruments not noted for the manufacturer are all conventional products that can be obtained commercially.

[0040] Example 1

[0041] Preparation of solution: triformylphloroglucin was dissolved in dichloromethane to obtain solution A with a concentration of 4.2 mmol L -1 ; acetic acid was dissolved in deionized water to obtain solution B with a concentration of 3 mol L -1 ; and tris(4-aminophenyl)amine was dissolved in N,N-dimethylformamide to obtain solution C with a concentration of 4.2 mmol L -1 ;

[0042] In-situ COFs functionalization: solution A, solution B, and solution C were sequentially superimposed in a volume ratio of 8:2:5 to form a three-layer system, a polypropylene (PP) separator was placed at the interface between solution A and solution B, after 7 days of reaction, the separator was sequentially washed with dichloromethane, ethanol, acetone, and N,N-dimethylformamide, and dried at 60 °C for 12 h to obtain a COFs functionalized separator.

[0043] Example 2

[0044] The difference between this example and Example 1 is only that the concentration of acetic acid in solution B used is 6 mol L -1 , and the rest of the preparation process is the same as that of Example 1.

[0045] Example 3

[0046] The difference between this example and Example 1 is only that the concentration of acetic acid in solution B used is 9 mol L-1 The rest of the preparation process is the same as that of Example 1.

[0047] Example 4

[0048] The difference between this example and Example 2 is that the reaction time in step S2 is 10 days, and the rest of the preparation process is the same as that of Example 2.

[0049] Example 5

[0050] The difference between this example and Example 2 is that the reaction time in step S2 is 10 days, and the rest of the preparation process is the same as that of Example 2.

[0051] Example 6

[0052] The difference between this example and Example 2 is that the polypropylene (PP) film is replaced by a polyethylene (PE) film for the modification reaction, and the rest of the preparation process is the same as that of Example 2.

[0053] Example 7

[0054] The difference between this example and Example 2 is that the polypropylene (PP) film is replaced by a PP / PE composite separator for the modification reaction, and the rest of the preparation process is the same as that of Example 2.

[0055] Figure 1 are morphology diagrams of the separators of Examples 1-3, wherein, Figure 1 (a) is a morphology diagram of polypropylene (PP); Figure 1 (b) is a morphology diagram of the COFs functionalized separator in Example 1; Figure 1 (c) is a morphology diagram of the COFs functionalized separator in Example 2; Figure 1 (d) is a morphology diagram of the COFs functionalized separator in Example 3; from which Figure 1 it can be seen that after modification, the PP separator is successfully COFs functionalized;

[0056] Figure 2 are field emission scanning electron microscope (SEM) diagrams of the COFs functionalized separators, wherein, Figure 2 (a) is an SEM diagram of the COFs functionalized separator in Example 1; Figure 2 (b) is an SEM diagram of the COFs functionalized separator in Example 2; Figure 2 (c) is an SEM diagram of the COFs functionalized separator in Example 3; 3 mol L -1 , the COFs form an uneven layer on the surface of the separator, and the internal pore filling rate is 40-60%; 6 mol L -1 , the COFs form a dense layer on the surface of the separator, and uniformly fill the internal pores of the separator through a lamellar penetration growth mode, with a filling rate of 80-90%; 9 mol L-1 When the concentration of COFs is 6 mol L

[0057] When the concentration of COFs is 6 mol L -1 When the concentration of COFs is 6 mol L -1 When the concentration of COFs is 6 mol L

[0058] Figure 3 For the mechanical strength test of the COFs functionalized separator in Example 2, FIG. 1 shows that, Figure 3 (a) is a bending test; Figure 3 (b) is a scratch test; the balance between the functionalization degree and the mechanical strength is achieved by adjusting the catalyst concentration, and the COFs functionalized separator prepared at a concentration of 6 mol L -1 The COFs functionalized separator prepared at a concentration of 6 mol L

[0059] Examples 4-7 adjust the reaction time and modify the raw materials to perform experiments, and similar modification effects can be achieved, which shows that the method of the present application is compatible with commercial separators such as polypropylene (PP) and polyethylene (PE), and the present application provides a low-cost and easily scalable technical path for the industrial production of functionalized separators for lithium-sulfur batteries.

[0060] In order to better illustrate the present application, a large number of specific details are given in the above specific embodiments. Those skilled in the art should understand that the present application can also be implemented without some specific details. In some examples, methods, means, elements and circuits familiar to those skilled in the art are not described in detail, in order to highlight the main idea of the present application.

[0061] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto, and any person skilled in the art can easily think of changes or replacements within the technical range disclosed by the present application, which should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for regulating COFs functionalization of lithium battery separators based on catalyst concentration, characterized by, Comprising the following steps: S1, preparing solutions: dissolving trimesic acid in dichloromethane to obtain solution A; dissolving catalyst in deionized water to obtain solution B; dissolving tris(4-aminophenyl)amine in N,N-dimethylformamide to obtain solution C; the catalyst in solution B is acetic acid; the concentration of the catalyst in solution B is 6 mol L -1 ; S2, in-situ COFs functionalization: sequentially superimpose solution A, solution B, solution C to form a three-layer system, place the lithium battery commercial separator at the interface of solution A and solution B for reaction, wash after reaction, dry to obtain COFs functionalized separator.

2. The method for functionalization of lithium battery separators COFs based on catalyst concentration regulation according to claim 1, characterized in that, The concentration of the triformylbenzene in solution A of step S1 is 4.2 mmol L -1 ; the concentration of the tris(4-aminophenyl)amine in solution C of step S1 is 4.2 mmol L -1 .

3. The method for functionalization of lithium battery separators COFs based on catalyst concentration regulation according to claim 1, characterized in that, The lithium battery commercial separator in step S2 is selected from one of polypropylene separator, polyethylene separator or PP / PE composite separator.

4. The method for functionalization of lithium battery separators COFs based on catalyst concentration regulation according to claim 1, characterized in that, The reaction time in step S2 is 5-10 days.

5. The method for functionalization of lithium battery separators COFs based on catalyst concentration regulation according to claim 1, characterized in that, The washing in step S2 is sequentially cleaning with dichloromethane, ethanol, acetone and N,N-dimethylformamide.

6. The method for functionalization of lithium battery separators COFs based on catalyst concentration regulation according to claim 1, characterized in that, The reaction time in step S2 is 7 days; the drying temperature in step S2 is 60 ℃, and the drying time is 12h.

7. The method for functionalization of lithium battery separators COFs based on catalyst concentration regulation according to claim 1, characterized in that, The volume ratio of solution A, solution B, solution C in step S2 is 8:2:5.

Images