A dynamic two-dimensional silicone polymer, its preparation method and application

Abstract

The present invention relates to the technical field of silicone materials, and particularly relates to a dynamic two-dimensional silicone polymer and its preparation method and application. The dynamic two-dimensional silicone polymer provided by the present invention has reversible covalent bonds (C=N bonds). Compared with non-reversible covalent bond silicones, it can improve the recycling of materials while ensuring the material properties and stability. The dynamic two-dimensional silicone polymer provided by the present invention combines the structural advantages of polymers and two-dimensional nanomaterials, and realizes efficient in-plane charge and energy transfer while ensuring the mechanical properties of the material. Using the dynamic two-dimensional silicone polymer provided by the present invention to prepare an electrolyte membrane can improve the conductivity, mechanical properties and cycle stability of the electrolyte membrane, and further improve the performance and service life of the battery.

Description

Technical Field

[0001] The present invention relates to the technical field of organosilicon materials, and in particular to a dynamic two-dimensional organosilicon polymer and a preparation method and application thereof. Background Art

[0002] Since the first organosilicon compound was synthesized in 1863, organosilicon materials have been widely used in aerospace, electronics, energy and other fields. Organosilicon materials are usually formed by covalent bonds such as Si-Si, Si-C, Si-OC, etc., and have excellent properties such as high and low temperature resistance, aging resistance, and biological inertness. Currently, most commonly used organosilicon materials are generated by non-reversible covalent bond coupling and have a linear structure. There is room for further improvement in product life and recyclability. Summary of the invention

[0003] The object of the present invention is to provide a dynamic two-dimensional organosilicon polymer and a preparation method and application thereof. The dynamic two-dimensional organosilicon polymer provided by the present invention is used to prepare an electrolyte membrane, which can improve the electrical conductivity, mechanical properties and cycle stability of the electrolyte membrane, thereby improving the performance and service life of the battery.

[0004] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0005] The present invention provides a dynamic two-dimensional organosilicon polymer, characterized in that the structural unit has a structure shown in Formula 1:

[0006] Formula 1;

[0007] In Formula 1, R is -CH3, -C2H5, -C3H7, -CH(CH3)2, -C6H6 or -O-[Si(CH3)2-O] n -CH3, n is an integer from 1 to 11.

[0008] The present invention provides a method for preparing the dynamic two-dimensional organosilicon polymer described in the above scheme, comprising the following steps:

[0009] (1) dissolving 2-(4-bromophenyl)-1,3-dioxolane in tetrahydrofuran and cooling to -60 to -95°C, adding an organic lithium reagent to carry out an intermediate reaction, adding a tetrahydrofuran solution of dichlorosilane to the obtained intermediate system and heating to room temperature to carry out a nucleophilic substitution reaction to obtain a compound with a structure shown in Formula 3;

[0010] The dichlorosilane has a structure shown in Formula 2: Formula 2;

[0011] Formula 3;

[0012] In Formula 2 and Formula 3, R is -CH3, -C2H5, -C3H7, -CH(CH3)2, -C6H6 or -O-[Si(CH3)2-O] n -CH3, n is an integer from 1 to 11;

[0013] (2) dissolving the compound of the structure represented by Formula 3 in acetone and mixing the mixture with water and a strong inorganic acid to carry out a deprotection reaction to obtain a compound of the structure represented by Formula 4;

[0014] Formula 4;

[0015] (3) The compound having the structure shown in Formula 4 is polymerized with melamine to obtain the dynamic two-dimensional organosilicon polymer.

[0016] Preferably, in step (1), the molar ratio of 2-(4-bromophenyl)-1,3-dioxolane to dichlorosilane is (1-4):1.

[0017] Preferably, in step (1), the molar ratio of the 2-(4-bromophenyl)-1,3-dioxolane to the organic lithium reagent is 1:(0.5-1.5);

[0018] The organic lithium reagent includes one or more of n-butyl lithium, sec-butyl lithium and tert-butyl lithium.

[0019] Preferably, in step (2), the mass ratio of the compound having the structure represented by formula 3 to the volume ratio of water is 1 g: 8-12 mL.

[0020] Preferably, in step (3), the polymerization reaction of the compound represented by formula 4 with melamine comprises method 1 or method 2;

[0021] The method 1 comprises the following steps:

[0022] The compound of the structure shown in Formula 4 and melamine are dissolved in a mixed solvent, an organic weak acid catalyst is added to the obtained solution, and then the solution is vacuum-sealed and allowed to stand under vacuum-sealed conditions to perform a polymerization reaction; the mixed solvent is a combination of 1,4-dioxane and mesitylene, or a combination of n-butanol and o-dichlorobenzene;

[0023] The second method comprises the following steps:

[0024] The compound with the structure shown in Formula 4 and melamine are dissolved in a high boiling point solvent, an organic weak acid catalyst is added to the obtained solution, and a polymerization reaction is carried out in an inert atmosphere or a vacuum atmosphere under static conditions; the high boiling point solvent includes one or more of dimethyl sulfoxide, chlorobenzene, dichlorobenzene and N,N-dimethylformamide.

[0025] Preferably, when the polymerization reaction is carried out using method 1 or method 2, the molar ratio of the compound of the structure represented by formula 4 to melamine is 3:(1.8-2.2).

[0026] Preferably, when the polymerization reaction is carried out by method 1, the polymerization reaction temperature is 60-80° C. and the time is 60-80 h;

[0027] When the polymerization reaction is carried out using method 2, the polymerization reaction temperature is 110-130° C. and the time is 60-80 hours.

[0028] The present invention provides the application of the dynamic two-dimensional organosilicon polymer described in the above scheme or the dynamic two-dimensional organosilicon polymer prepared by the preparation method described in the above scheme in an electrolyte membrane.

[0029] Preferably, the electrolyte membrane comprises a matrix, an electrolyte salt and a dynamic two-dimensional organosilicon polymer, and the mass of the dynamic two-dimensional organosilicon polymer is 1-5% of the mass of the matrix.

[0030] The dynamic two-dimensional organosilicon polymer provided by the present invention has a reversible covalent bond (C=N bond). Compared with non-reversible covalent bond organosilicon, it can improve the recycling of materials while ensuring the performance and stability of the materials; the dynamic two-dimensional organosilicon polymer provided by the present invention combines the structural advantages of polymers and two-dimensional nanomaterials, and achieves efficient in-plane charge and energy transfer while ensuring the mechanical properties of the materials. The dynamic two-dimensional organosilicon polymer provided by the present invention is used to prepare an electrolyte membrane, which can improve the conductivity, mechanical properties and cycle stability of the electrolyte membrane, thereby improving the performance and service life of the battery.

[0031] The dynamic two-dimensional organosilicon polymer provided by the present invention is a brand-new structure, which will foreseeably bring novel changes to the field of traditional organosilicon materials and inject new vitality. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 The hydrogen spectrum (a) and carbon spectrum (b) of 2-(4-bromophenyl)-1,3-dioxolane;

[0033] Figure 2 The hydrogen spectrum (a) and carbon spectrum (b) of bis(4-(1,3-dioxolan-2-yl)phenyl)dimethylsilane;

[0034] Figure 3 The hydrogen spectrum (a) and carbon spectrum (b) of 4,4'-(dimethylsilanediyl)benzaldehyde;

[0035] Figure 4 The XPS spectrum of the dynamic two-dimensional organosilicon polymer prepared in Example 1;

[0036] Figure 5 This is the C 1s-XPS spectrum of the dynamic two-dimensional organosilicon polymer prepared in Example 1;

[0037] Figure 6 This is the N-XPS spectrum of the dynamic two-dimensional organosilicon polymer prepared in Example 1;

[0038] Figure 7 This is the Si-XPS spectrum of the dynamic two-dimensional organosilicon polymer prepared in Example 1;

[0039] Figure 8 The infrared spectra of 4,4'-(dimethylsilanediyl)benzaldehyde, melamine, and 2D-COSi-Me prepared in Example 1 and Example 2;

[0040] Fig. 9 This is the thermogravimetric analysis diagram of melamine;

[0041] Fig.10 This is a thermogravimetric analysis diagram of the dynamic two-dimensional organosilicon polymer of Example 1;

[0042] Fig.11 is an optical microscope photograph of the dynamic two-dimensional organosilicon polymer of Example 1, a~d are different particles;

[0043] Fig.12 TEM images (a and b) and HRTEM images (c and d) of the dynamic two-dimensional organosilicon polymer of Example 1;

[0044] Fig.13 This is a physical photo of the electrolyte slurry;

[0045] Fig.14 This is a photo of the electrolyte membrane doped with 1% 2D-COSi-Me;

[0046] Fig.15 SEM photos of PEO electrolyte membrane, where a~c are surface photos and d is a cross-sectional photo;

[0047] Fig.16 SEM photos of the electrolyte membrane doped with 2% 2D-COSi-Me, where a~c are surface photos and d is a cross-sectional photo;

[0048] Fig.17 Element analysis diagrams of different positions of the electrolyte membrane doped with 2% 2D-COSi-Me, where b and c are the element analysis results of a, and e and f are the element analysis results of d;

[0049] Fig.18 Cycling stability test results of batteries assembled with PEO electrolyte membrane (a and c) and electrolyte membrane doped with 1% 2D-COSi-Me (b and d);

[0050] Fig.19 The stability test results of electrolyte membranes doped with 1% 2D-COSi-Me (a), 1.5% 2D-COSi-Me (b), 2% 2D-COSi-Me (c) and 2.5% 2D-COSi-Me (d);

[0051] Fig. 20 The electron transfer activation energy (a) and the conductivity comparison diagram in the range of 30~70℃ of the PEO electrolyte membrane and the electrolyte membrane doped with 1% 2D-COSi-Me (b);

[0052] Fig.21 This is a comparison chart of the stretching results of the PEO electrolyte membrane and the electrolyte membrane doped with 1% 2D-COSi-Me. DETAILED DESCRIPTION

[0053] The present invention provides a dynamic two-dimensional organosilicon polymer, wherein the structural unit has a structure shown in Formula 1:

[0054] Formula 1;

[0055] In Formula 1, R is -CH3, -C2H5, -C3H7, -CH(CH3)2, -C6H6, or -O-[Si(CH3)2-O] n -CH3, n is an integer from 1 to 11.

[0056] In the present invention, the wavy lines in Formula 1 represent connecting the same structural units.

[0057] The dynamic two-dimensional organosilicon polymer provided by the present invention has a reversible covalent bond (C=N bond). Compared with non-reversible covalent bond organosilicon, it can improve the recycling of materials while ensuring the performance and stability of the materials; the dynamic two-dimensional organosilicon polymer provided by the present invention combines the structural advantages of polymers and two-dimensional nanomaterials, and achieves efficient in-plane charge and energy transfer while ensuring the mechanical properties of the materials. The dynamic two-dimensional organosilicon polymer provided by the present invention is used to prepare an electrolyte membrane, which can improve the conductivity, mechanical properties and cycle stability of the electrolyte membrane, thereby improving the performance and service life of the battery.

[0058] The dynamic two-dimensional organosilicon polymer provided by the present invention is a brand-new structure, which will foreseeably bring novel changes to the field of traditional organosilicon materials and inject new vitality.

[0059] The present invention provides a method for preparing the dynamic two-dimensional organosilicon polymer described in the above scheme, comprising the following steps:

[0060] (1) dissolving 2-(4-bromophenyl)-1,3-dioxolane in tetrahydrofuran and cooling to -60 to -95°C, adding an organic lithium reagent to carry out an intermediate reaction, adding a tetrahydrofuran solution of dichlorosilane to the obtained intermediate system and heating to room temperature to carry out a nucleophilic substitution reaction to obtain a compound with a structure shown in Formula 3;

[0061] The dichlorosilane has a structure shown in Formula 2: Formula 2;

[0062] Formula 3;

[0063] In Formula 2 and Formula 3, R is -CH3, -C2H5, -C3H7, -CH(CH3)2, -C6H6 or -O-[Si(CH3)2-O] n -CH3, n is an integer from 1 to 11;

[0064] (2) dissolving the compound of the structure represented by Formula 3 in acetone and mixing the mixture with water and a strong inorganic acid to carry out a deprotection reaction to obtain a compound of the structure represented by Formula 4;

[0065] Formula 4;

[0066] (3) The compound having the structure shown in Formula 4 is polymerized with melamine to obtain the dynamic two-dimensional organosilicon polymer.

[0067] In the present invention, unless otherwise specified, the raw materials used are commercially available products well known in the art.

[0068] The present invention dissolves 2-(4-bromophenyl)-1,3-dioxolane in tetrahydrofuran and then cools the mixture to -60 to -95°C, adds an organic lithium reagent to carry out an intermediate reaction, adds a tetrahydrofuran solution of dichlorosilane to the obtained intermediate system, and heats the mixture to room temperature to carry out a nucleophilic substitution reaction, thereby obtaining a compound with a structure shown in Formula 3.

[0069] In the present invention, the 2-(4-bromophenyl)-1,3-dioxolane can be commercially available or prepared by methods well known in the art. In a specific embodiment of the present invention, the 2-(4-bromophenyl)-1,3-dioxolane is prepared in-house, and the preparation method is as follows: 4-bromobenzaldehyde (15.00 g, 81 mmol) is added to a two-necked flask, anhydrous toluene (90 mL) is added to dissolve, and then ethylene glycol (7.50 g, 6.74 mL, 120.8 mmol) and p-toluenesulfonic acid (66 mg, 0.35 mmol) are added. After heating and reflux at 145°C under N2 conditions for 24 h, it is washed with saturated NaHCO3 solution and brine, and the organic layer is dried with MgSO4, filtered, and rotary evaporated to obtain a crude product, and the 2-(4-bromophenyl)-1,3-dioxolane pure product is obtained by vacuum distillation (set at 135°C, the thermometer shows 106°C).

[0070] In the present invention, the structural formula of the 2-(4-bromophenyl)-1,3-dioxolane is as shown in Formula 5:

[0071] Formula 5.

[0072] In the present invention, tetrahydrofuran is used as a solvent, and the mass ratio of the 2-(4-bromophenyl)-1,3-dioxolane to the volume ratio of tetrahydrofuran is preferably 1 g: (8-13) mL, more preferably 1 g: (9-11) mL. The present invention has no special requirements for the dissolution temperature, as long as the 2-(4-bromophenyl)-1,3-dioxolane can be completely dissolved.

[0073] In the present invention, the 2-(4-bromophenyl)-1,3-dioxolane is dissolved in tetrahydrofuran and then cooled to -60 to -95°C. In specific embodiments, the temperature can be cooled to -60°C, -70°C, -78°C, -85°C, -90°C or -95°C, which are not listed here.

[0074] In the present invention, the organolithium reagent preferably includes one or more of n-butyl lithium, sec-butyl lithium and tert-butyl lithium; the molar ratio of the 2-(4-bromophenyl)-1,3-dioxolane to the organolithium reagent is preferably 1:(0.5-1.5), more preferably 1:(0.8-1.2), and further preferably 1:1. In the present invention, the organolithium reagent is preferably added dropwise.

[0075] In the present invention, the intermediate reaction is preferably carried out under stirring conditions, and the intermediate reaction time is preferably 1 hour. In the intermediate reaction process of the present invention, the lithium in the organolithium reagent can replace the bromine atom in 2-(4-bromophenyl)-1,3-dioxolane to generate a phenyllithium intermediate product, and then further undergoes a nucleophilic substitution reaction with the subsequently added dichlorosilane.

[0076] In the present invention, the organic lithium is highly active and generates heat when reacting with 2-(4-bromophenyl)-1,3-dioxolane. The present invention reduces the temperature to -60 to -95°C for the reaction, which can prevent other side reactions.

[0077] In the present invention, the dichlorosilane has a structure shown in Formula 2:

[0078] Formula 2.

[0079] In the present invention, the concentration of the tetrahydrofuran solution of dichlorosilane is preferably 0.5-2 mol / L. In the present invention, the tetrahydrofuran solution of dichlorosilane is preferably added dropwise.

[0080] In the present invention, the temperature increase is preferably natural temperature increase.

[0081] In the present invention, the nucleophilic substitution reaction is preferably carried out under stirring conditions, and the time of the nucleophilic substitution reaction is preferably 0.5 to 1.5 h, more preferably 1 h.

[0082] In the present invention, after the nucleophilic substitution reaction time is reached, methanol is preferably added to the reaction system to quench the reaction, and then the obtained product is poured into a saturated NaHCO3 solution, the organic layer is separated, and then extracted three times with dichloromethane, dried with MgSO4, filtered, and rotary evaporated to obtain a compound with a structure shown in Formula 3;

[0083] Formula 3.

[0084] In the present invention, taking n-butyl lithium as an example, the reaction equation for preparing the compound of the structure shown in Formula 3 is shown in Formula (1):

[0085] Formula (1).

[0086] After obtaining the compound of the structure shown in Formula 3, the present invention dissolves the compound of the structure shown in Formula 3 in acetone and then mixes it with water and a strong inorganic acid to perform a deprotection reaction to obtain a compound of the structure shown in Formula 4.

[0087] In the present invention, the mass ratio of the compound of the structure represented by Formula 3 to the volume ratio of acetone is preferably 1 g: (10-40) mL, more preferably 1 g: (20-30) mL. The acetone is used as a solvent.

[0088] In the present invention, the mass ratio of the compound of the structure shown in Formula 3 to the volume ratio of water is preferably 1 g: 8-12 mL, more preferably 1 g: 10 mL. The water is used as a reactant.

[0089] In the present invention, the inorganic strong acid is preferably p-toluenesulfonic acid or dilute sulfuric acid; the mass ratio of the compound of the structure shown in Formula 3 to the inorganic strong acid is preferably (15~15.5):1, and in a specific embodiment of the present invention, the mass ratio of the compound of the structure shown in Formula 3 to the inorganic strong acid is 15.15:1. In the present invention, the inorganic strong acid serves as a catalyst for the reaction.

[0090] In the present invention, the deprotection is preferably carried out under reflux conditions, and the reflux temperature is preferably 50~80°C. In a specific embodiment, the reflux temperature can be 50°C, 60°C, 70°C or 80°C. In the present invention, the equation of the deprotection reaction is shown as the following formula (2):

[0091] Formula (2).

[0092] After completing the deprotection reaction, in the present invention, the obtained reaction solution is cooled to room temperature, the cooled solution is added to saturated NaHCO3 solution, extracted with dichloromethane, dried over MgSO4, filtered, and then distilled under reduced pressure to obtain the compound of the structure shown in Formula 4;

[0093] Formula 4.

[0094] After obtaining the compound of the structure shown in Formula 4, in the present invention, the compound of the structure shown in Formula 4 is subjected to a polymerization reaction with melamine to obtain the dynamic two-dimensional organosilicon polymer.

[0095] The present invention preferably uses Method 1 or Method 2 to carry out the polymerization reaction of the compound of the structure shown in Formula 4 with melamine.

[0096] First, Method 1 will be described below.

[0097] In the present invention, Method 1 preferably includes the following steps: dissolving the compound of the structure shown in Formula 4 and melamine in a mixed solvent, adding an organic weak acid catalyst to the obtained solution, then evacuating and sealing, and carrying out the polymerization reaction under the condition of standing in a vacuum seal.

[0098] In the present invention, the mixed solvent is preferably a combination of 1,4-dioxane and mesitylene, or a combination of n-butanol and o-dichlorobenzene. When it is a combination of 1,4-dioxane and mesitylene, the volume ratio of 1,4-dioxane to mesitylene is preferably 4:1; when it is a combination of n-butanol and o-dichlorobenzene, the volume ratio of n-butanol to o-dichlorobenzene is preferably 5:1.

[0099] In the present invention, the molar ratio of the compound of the structure shown in Formula 4 to melamine is preferably 3:(1.8 - 2.2), more preferably 3:2; the mass ratio of melamine to the mixed solvent is preferably 7:(6000 - 7000), more preferably 7:6600.

[0100] In the present invention, the dissolution is preferably carried out at 70 °C.

[0101] In the present invention, the organic weak acid catalyst preferably includes one or more of formic acid, acetic acid, trifluoroacetic acid and propionic acid; the concentration of the formic acid is preferably 6 M; the mass ratio of the organic weak acid catalyst to melamine is preferably 3:1.

[0102] In the present invention, the vacuum is preferably pumped to -60 to -80 kPa.

[0103] In the present invention, the temperature of the polymerization reaction is preferably 70 °C, and the time is preferably 72 h.

[0104] After completing the polymerization reaction, in the present invention, it is preferred to cool the obtained product liquid, then filter, and wash the filter cake with methanol to obtain the dynamic two-dimensional organosilicon polymer.

[0105] The following describes Method 2.

[0106] In the present invention, Method 2 preferably includes the following steps: dissolving the compound of the structure shown in Formula 4 and melamine in a high-boiling solvent, adding an organic weak acid catalyst to the obtained solution, and carrying out a polymerization reaction under an inert atmosphere or a vacuum atmosphere and static conditions.

[0107] In the present invention, the molar ratio of the compound of the structure shown in Formula 4 to melamine is preferably 3:(1.8 - 2.2), more preferably 3:2. The dosage ratio of melamine to the high-boiling solvent is preferably 70 mg:(5 - 7) mL, more preferably 70 mg:6 mL; the high-boiling solvent preferably includes one or more of dimethyl sulfoxide, chlorobenzene, dichlorobenzene and N,N-dimethylformamide; the type and dosage of the organic acid catalyst are the same as those in Method 1 and will not be elaborated here.

[0108] In the present invention, the gas providing the inert atmosphere is preferably one or more of nitrogen, helium, neon and argon.

[0109] After adding the organic weak acid catalyst, in the present invention, it is preferred to cycle the obtained reaction system through freezing - pumping - thawing - filling with inert gas, and seal the gas-filled reaction system to provide the inert atmosphere required for the polymerization reaction.

[0110] In the present invention, the temperature for freezing is preferably -80°C, and the time is preferably 5 min; the time for evacuation is preferably 180 s; the temperature for thawing is preferably room temperature, and the time is preferably 20 min; the inert gas is preferably filled to atmospheric pressure.

[0111] In the present invention, the freezing-evacuation-thawing-inert gas filling is preferably repeated 3 times. By cyclically performing freezing-evacuation-thawing-inert gas filling in the present invention, the atmosphere in the reaction system can be replaced with an inert gas.

[0112] In the present invention, the vacuum degree of the vacuum atmosphere is preferably -60 kPa to -80 kPa.

[0113] In the present invention, the temperature of the polymerization reaction is preferably 110 - 130°C, and the time of the polymerization reaction is preferably 60 - 80 h; in specific embodiments, the temperature of the polymerization reaction can be 110°C, 120°C, or 130°C, and the time of the polymerization reaction can be 60 h, 72 h, 76 h, or 80 h.

[0114] After completing the polymerization reaction, in the present invention, it is preferred to cool the obtained product liquid and then filter it, and the obtained solid is washed with tetrahydrofuran and methanol respectively to obtain the dynamic two-dimensional organosilicon polymer.

[0115] In the present invention, although the dynamic two-dimensional organosilicon polymer prepared by the above two methods has been washed, there is still some unreacted melamine remaining. In the present invention, it is preferred to further remove it by solvent extraction.

[0116] The present invention has no special requirements for the process of the solvent extraction, and the well-known solvent extraction process in the art can be adopted, such as Soxhlet extraction.

[0117] The present invention provides the application of the dynamic two-dimensional organosilicon polymer described in the above scheme or the dynamic two-dimensional organosilicon polymer prepared by the preparation method described in the above scheme in an electrolyte membrane.

[0118] In the present invention, the electrolyte membrane preferably comprises a matrix, an electrolyte salt, and a dynamic two-dimensional organosilicon polymer; the matrix preferably comprises polyethylene oxide; the electrolyte salt preferably comprises lithium bis(trifluoromethanesulfonyl)imide; the mass of the dynamic two-dimensional organosilicon polymer is preferably 1 - 5% of the mass of the matrix. In specific embodiments, the mass of the dynamic two-dimensional organosilicon polymer can be 1%, 2%, 3%, 4%, or 5% of the mass of the matrix.

[0119] The present invention has no special requirements for the preparation process of the electrolyte membrane, and the well-known preparation process in the art can be adopted.

[0120] The dynamic two-dimensional organosilicon polymer provided by the present invention, its preparation method and application will be described in detail below in conjunction with embodiments, but they should not be construed as limiting the protection scope of the present invention.

[0121] Example 1

[0122] Synthesize a dynamic two-dimensional organosilicon polymer with the structure shown in Formula 1-1:

[0123] Formula 1-1.

[0124] The specific steps are as follows:

[0125] (1) Add 4-bromobenzaldehyde (15.00 g, 81 mmol) into a two-necked flask, dissolve it with anhydrous toluene (90 mL), then add ethylene glycol (7.50 g, 6.74 mL, 120.8 mmol), p-toluenesulfonic acid (66 mg, 0.35 mmol). After heating under reflux at 145 °C for 24 h under N2 condition, wash with saturated NaHCO3 solution and brine. The organic layer is dried with MgSO4, filtered, and rotary evaporated to obtain a crude product. After vacuum distillation (set at 135 °C, thermometer shows 106 °C), pure 2-(4-bromophenyl)-1,3-dioxolane is obtained as a white solid.

[0126] Dissolve 1.83 g of 2-(4-bromophenyl)-1,3-dioxolane in 20 mL of tetrahydrofuran (THF), cool to -78 °C, then dropwise add 1.6 M n-butyllithium (5.1 mL, 8.16 mmol). After stirring for 1 h, a white precipitate is obtained. Dropwise add 2 mL of a THF solution containing 515 mg of dichlorodimethylsilane, and stir at room temperature for 1 h for a nucleophilic substitution reaction to obtain a light yellow solution. Quench the reaction with 1 mL of methanol and pour it into saturated NaHCO3 solution. After separating the organic layer, extract it three times with dichloromethane, dry with MgSO4, filter, and rotary evaporate to obtain bis(4-(1,3-dioxolan-2-yl)phenyl)dimethylsilane (Formula 6);

[0127] Formula 6.

[0128] (2) Dissolve bis(4-(1,3-dioxolan-2-yl)phenyl)dimethylsilane (1 g, 2.8 mmol) in 30 mL of acetone, add 10 mL of water until slightly turbid, then add 66 mg of p-toluenesulfonic acid and heat to 70 °C for reflux for 10 min. After cooling, add 20 mL of saturated NaHCO3 solution, extract with dichloromethane, dry with MgSO4, filter, and perform vacuum distillation to obtain 4,4'-(dimethylsilylene)dibenzaldehyde (Formula 7).

[0129] Formula 7.

[0130] (3) Solvothermal condition: Melamine (70 mg, 0.56 mmol) and 4,4'-(dimethylsilanediyl) dibenzaldehyde (240 mg, 0.89 mmol) were added into a 30 mL hard glass tube and dissolved in 6 mL of dimethyl sulfoxide. After adding 0.6 mL of 6 M acetic acid, the mixture was ultrasonically dispersed for 30 min. After three freeze-pump-thaw-inflate cycles, the glass tube was sealed and allowed to react statically at 120 °C for 3 days. After cooling, the solid obtained was filtered and washed with tetrahydrofuran and methanol respectively to obtain a dynamic two-dimensional organosilicon polymer with the structure shown in Formula 1-1, denoted as 2D-COSi-Me (yield: 38%).

[0131] Example 2

[0132] The difference from Example 1 is only that step (3) is replaced with the following step:

[0133] Vacuum condition: Melamine (70 mg, 0.56 mmol) and 4,4'-(dimethylsilanediyl) dibenzaldehyde (240 mg, 0.89 mmol) were added into a 30 mL hard glass tube and dissolved in 6 mL of dimethyl sulfoxide. After adding 0.6 mL of 6 M acetic acid, the mixture was ultrasonically dispersed for 30 min. After three freeze-pump-thaw-inflate cycles, the glass tube was evacuated and sealed, and allowed to react statically at 120 °C for 3 days. After cooling, the solid obtained was filtered and washed with tetrahydrofuran and methanol respectively to obtain a dynamic two-dimensional organosilicon polymer, denoted as 2D-COSi-Me (yield: 40%).

[0134] Example 3

[0135] The difference from Example 1 is only that step (3) is replaced with the following step:

[0136] Melamine (0.16 mmol), 4,4'-(dimethylsilanediyl) dibenzaldehyde (0.24 mmol), 1,4-dioxane (5 mL) and mesitylene (1.25 mL) were added into a 20 mL glass bottle. After heating to 70 °C until the precursors were dissolved, 3 mL of acetic acid (10.5 M) was added, the mixture was evacuated and sealed, and continuously heated at 70 °C for 72 h without stirring. After cooling, it was filtered and washed with methanol to obtain a dynamic two-dimensional organosilicon polymer (yield: 45%).

[0137] Examples 4 - 9

[0138] The difference from Example 1 is only that dichlorodimethylsilane in step (1) is replaced with other dichlorosilanes, and the structural formula is Formula 2. In Formula 2, the substituents R are -C2H5, -C3H7, -CH(CH3)2, -C6H5, -O-Si(CH3)2-O-CH3 and -O-[Si(CH3)2-O] respectively11 -CH3, in the resulting dynamic two-dimensional organosilicon polymer with the structure shown in Formula 1, R is respectively -C2H5, -C3H7, -CH(CH3)2, -C6H5, -O-Si(CH3)2-O-CH3 and -O-[Si(CH3)2-O] 11 -CH3.

[0139] Structural characterization:

[0140] (1) The 2-(4-bromophenyl)-1,3-dioxolane prepared in Example 1 was tested by nuclear magnetic resonance hydrogen spectrum (H-NMR) and nuclear magnetic resonance carbon spectrum (C-NMR). The results are as Figure 1 shown, where a is the hydrogen spectrum and b is the carbon spectrum. It can be seen from the hydrogen spectrum that there are a total of 9 Hs in 2-(4-bromophenyl)-1,3-dioxolane, with 4 different chemical environments. The d peaks at δ 7.39 and 7.37 are 2 Hs on the benzene ring close to Br, J = 8; the d peaks at δ 7.23 and 7.21 are 2 Hs on the benzene ring far from Br, J = 8; the s peak at δ 5.62 is 1 H on the carbon of the dioxolane connected to the benzene ring; the d peaks at δ 3.94 and 3.85 are 4 Hs on the dioxolane far from the benzene ring, J = 36.

[0141] It can be seen from the carbon spectrum that there are a total of 9 Cs in 2-(4-bromophenyl)-1,3-dioxolane, with 6 different chemical environments. The peak at δ 136.02 is the C on the benzene ring connected to the dioxolane; the peak at δ 130.38 is 2 Cs on the benzene ring close to Br; the peak at δ 121.17 is 2 Cs on the benzene ring far from Br; the peak at δ 122.09 is the C on the benzene ring connected to Br; the peak at δ 101.87 is the C on the dioxolane connected to the benzene ring; the peak at δ 64.19 is 2 Cs on the dioxolane far from the benzene ring.

[0142] It can be Figure 1 seen that the structural formula of the synthesized 2-(4-bromophenyl)-1,3-dioxolane is the structure of Formula 5:

[0143] Formula 5.

[0144] (2) The bis(4-(1,3-dioxolan-2-yl)phenyl)dimethylsilane prepared in Example 1 was respectively tested by H-NMR and C-NMR. The results are as Figure 2As shown, where a is the hydrogen spectrum and b is the carbon spectrum. From the hydrogen spectrum, it can be seen that there are 24 Hs in bis(4-(1,3-dioxolan-2-yl)phenyl)dimethylsilane, in 5 different chemical environments. The d peaks at δ 7.46 and 7.44 are the 4 Hs on the benzene ring close to Si, J = 8; the d peaks at δ 7.38 and 7.36 are the 4 Hs on the benzene ring far from Si, J = 8; the s peak at δ 5.74 is the 2 Hs on the carbon of the dioxolane connected to the benzene ring; the d peaks at δ 4.04 and 3.95 are the 8 Hs on the dioxolane far from the benzene ring, J = 36; the s peak at δ 0.46 is the 6 Hs on the methyl group connected to Si.

[0145] From the carbon spectrum, it can be seen that there are 20 Cs in bis(4-(1,3-dioxolan-2-yl)phenyl)dimethylsilane, in 7 different chemical environments. The peak at δ 141.66 is the 2 Cs on the benzene ring connected to the dioxolane; the peak at δ 141.16 is the 2 Cs on the benzene ring connected to Si; the peak at δ 136.70 is the 4 Cs on the benzene ring close to Si; the peak at δ 128.13 is the 4 Cs on the benzene ring far from Si; the peak at δ 106.05 is the 2 Cs on the benzene ring connected to the dioxolane; the peak at δ 67.73 is the 4 Cs on the dioxolane far from the benzene ring; the peak at δ -0.23 is the 2 Cs on the methyl group connected to Si.

[0146] From Figure 2 it can be known that the structural formula of bis(4-(1,3-dioxolan-2-yl)phenyl)dimethylsilane is the structure of Formula 6: Formula 6.

[0147] (3)The 4,4'-(dimethylsilanediyl)dibenzaldehyde prepared in Example 1 was respectively tested by H-NMR and C-NMR, and the results are as Figure 3 shown, where a is the hydrogen spectrum and b is the carbon spectrum. From the hydrogen spectrum, it can be seen that there are 16 Hs in 4,4'-(dimethylsilanediyl)dibenzaldehyde, in 4 different chemical environments. The s peak at δ 9.94 is the 2 Hs on the aldehyde group; the d peaks at δ 7.78 and 7.76 are the 4 Hs on the benzene ring close to the aldehyde group, J = 8; the d peaks at δ 7.61 and 7.59 are the 2 Hs on the benzene ring close to Si, J = 8; the s peak at δ 0.56 is the 6 Hs on the methyl group connected to Si.

[0148] It can be seen from the carbon spectrum that there are 16 C's and 6 different chemical environments in 4,4'-(dimethylsilylene)dibenzaldehyde. The peak at δ 191.42 is for the 2 C's on the aldehyde group; the peak at δ 144.61 is for the 2 C's on the benzene ring connected to Si; the peak at δ 135.87 is for the 2 C's on the benzene ring connected to the aldehyde group; the peak at δ 133.63 is for the 4 C's on the benzene ring close to Si; the peak at δ 127.79 is for the 4 C's on the benzene ring close to the aldehyde group; the peak at δ -3.86 is for the 2 C's on the methyl group connected to Si.

[0149] It can be known from Figure 3 that the structural formula of 4,4'-(dimethylsilylene)dibenzaldehyde is Structure 7: Structure 7.

[0150] (4) The dynamic two-dimensional organosilicon polymer prepared in Example 1 was characterized by XPS, and the results are as Figures 4 to 7 shown. Among them, Figure 4 is the XPS total spectrum, Figure 5 is the C 1s-XPS spectrum, Figure 6 is the N-XPS spectrum, Figure 7 is the Si-XPS spectrum.

[0151] Figure 4 Four elements, C, N, Si and O, are shown in the XPS total spectrum of

[0152] Figure 5 . Among them, the C, N and Si elements are the same as the elemental composition of the molecular structure of the dynamic two-dimensional organosilicon polymer, while the O element is mainly attributed to the adsorbed oxygen in the material.

[0152] Figure 5 The high-resolution C 1s spectrum is deconvoluted into four sub-peaks at 284.6, 283.6, 286 and 287, which are attributed to sp 2 C=C, sp 3 C-Si, sp 2 C=N and C=O bonds respectively. Moreover, the abundance ratios of sp 2 C=C, sp 3 C-Si and sp 2 C=N are close to 6:1:1, which is consistent with the theoretical ratios of sp 2 C=C, sp 3 C-Si and sp 2 C=N in the 2D-COSi-Me structure. In the high-resolution C 1s spectrum, the proportion abundance of the C=O bond is relatively high. In addition to a part being the amide bond in 2D-COSi-Me, there is also oxidation of the end groups.

[0153] Figure 6The N-XPS spectrum was deconvoluted into two peaks at 398.7 and 397.5, which were attributed to the C=N bond and N≡N bond respectively, consistent with the chemical structure of 2D-COSi-Me. The appearance of the N≡N peak may be due to the nitrogen adsorbed on the sample surface.

[0154] Figure 7 There was only a small peak at 102.7 in the Si-XPS spectrum, which was attributed to the Si-C bond in the 2D-COSi-Me sample.

[0155] The above results indicate that the bonding environment of each element is close to the theoretical value, indicating that the synthesized product is the target designed substance, and the structural formula is Formula 1-1.

[0156] The dynamic two-dimensional organosilicon polymers prepared in Examples 1 to 3 have the same structure, and the only difference is the yield.

[0157] (5) A series of characterizations were carried out on the changes of functional groups during the synthesis of 4,4'-(dimethylsilanediyl) dibenzaldehyde, melamine, and the samples 2D-COSi-Me prepared in Examples 1 and 2 by Fourier transform infrared spectroscopy (FT-IR), and the results are as Figure 8 shown. Figure 8 Si-COF vacuum in it represents 2D-COSi-Me prepared in Example 2, Si-COF solvothermal represents 2D-COSi-Me prepared in Example 1, and Si-COF precursor represents 4,4'-(dimethylsilanediyl) dibenzaldehyde. Figure 8 It shows that at 120 °C, attempts were made to prepare 2D-COSi-Me under two conditions of vacuum and solvothermal pressure respectively. Infrared shows that 2D-COSi-Me has C-H bond vibration (3010 cm -1 -3100 cm -1 ), N-H bond vibration (1650 cm -1 , 780 cm -1 ), C=C bond vibration (1550 cm -1 , 1450 cm -1 ), C=N bond vibration (1000 cm -1 ), C-N bond vibration (1340 cm -1 , 1350 cm -1 ), and Si-C bond vibration (1100 cm -1 ). By comparing with the infrared data of the precursor 4,4'-(dimethylsilanediyl) dibenzaldehyde (abbreviated as Si COF precursor) and melamine respectively, it was initially found that the crude product 2D-COSi-Me contained unreacted melamine, which needed to be removed by solvent extraction method.

[0158] (6) The thermal stability of melamine was detected by thermogravimetric analysis (TGA), and the results are as Fig. 9 shown. In the test range from room temperature of 25 °C to 800 °C, melamine showed two mass loss stages. The first stage of mass loss occurred at 132 °C, which was analyzed as the volatilization of the solvent attached to melamine. The second stage of mass loss occurred at 320 °C, indicating that melamine underwent thermal decomposition and quickly decomposed completely, losing all its mass.

[0159] Furthermore, the thermal stability of 2D-COSi-Me prepared in Example 1 was detected by thermogravimetric analysis (TGA), and the results are as Fig.10 shown. In the test range from 25 °C to 800 °C, the 2D-COSi-Me sample showed three mass loss stages. Among them, the first stage of mass loss occurred at 80 °C, which was analyzed as the volatilization of the solvent attached to 2D-COSi-Me. The second stage of mass loss occurred at 399 °C. By comparing with the TGA data of melamine, the mass loss at this position was mainly attributed to the decomposition of melamine and oligomers encapsulated in 2D-COSi-Me. And the mass loss after that was the thermal decomposition of 2D-COSi-Me, and all the mass was lost at 710 °C, indicating that 2D-COSi-Me would decompose completely above 700 °C.

[0160] (7) The 2D-COSi-Me sample prepared in Example 1 was observed by optical microscope, and the results are as Fig.11 shown. As Fig.11 can be seen, the 2D-COSi-Me sample was in the shape of rhombuses with different sizes, ranging from 20 to 600 μm.

[0161] Under a transmission electron microscope (TEM), the rhombic morphology of 2D-COSi-Me was also observed (as in Fig.12 (a) and (b)), and under the observation of a high-resolution transmission electron microscope (HRTEM), lattice fringes with a length of 0.42 nm were seen (as in Fig.12 (c) and (d)).

[0162] Application Example

[0163] Preparation process of electrolyte membrane:

[0164] 6 mg of 2D-COSi-Me of Example 1 and 10 mL of acetonitrile were added to a 20 mL glass bottle and stirred for 24 h. Then 600 mg of PEO (polyethylene oxide) and 219 mg of LiTFSI (lithium bis(trifluoromethanesulfonyl)imide) were added and stirred for 24 h to obtain an electrolyte slurry (as Fig.13As shown in the figure). Pipette 5 mL of the electrolyte slurry and evenly apply it in the PTFE mold. After standing for 2 h, vacuum dry it at 50 °C for 12 h. Peel the film off the mold and then cut it into a circular separator with a diameter of 2 cm (as shown in Fig.14 ), obtaining an electrolyte membrane doped with 1% 2D-COSi-Me. Cut the lithium foil into a circular piece with a diameter of 1 cm and assemble the battery in the order of the positive electrode case, lithium foil, separator, lithium foil, steel sheet, spring piece, and negative electrode case.

[0165] Preparation of the pure PEO electrolyte membrane: The same as above, except that 2D-COSi-Me is not added.

[0166] Preparation of the electrolyte membrane doped with 2% 2D-COSi-Me: The same as above, except that the mass of 2D-COSi-Me is 12 mg.

[0167] SEM observation was carried out on the PEO electrolyte membrane and its interfacial morphology, and the results are as shown in Fig.15 . The SEM photo of PEO doped with 2% 2D-COSi-Me is as shown in Fig.16 .

[0168] From Fig.15 and Fig.16 , it can be seen that compared with the pure PEO electrolyte membrane, the PEO electrolyte membrane doped with 2% 2D-COSi-Me is flatter. No obvious phase separation phenomenon was observed. It shows that the doped 2D-COSi-Me has a role similar to that of an adhesive, making the whole electrolyte membrane more complete, which is beneficial to the contact between the electrolyte and the electrode material, thus improving the battery performance.

[0169] Elemental analysis was carried out on different positions of the PEO electrolyte membrane doped with 2% 2D-COSi-Me, and the results are as shown in Fig.17 . Fig.17 It shows that the content change of Si element is not significant, indicating that 2D-COSi-Me is evenly doped into PEO.

[0170] Comparison of battery cycle stability

[0171] A 2032-type button battery was used for electrochemical testing. After doping with 1% 2D-COSi-Me, the cycle stability test was carried out at 60 °C, and the results are as shown in Fig.18 , in Fig.18 , a and c are the PEO electrolyte membranes at 0.1 mA·cm -2 , 0.1 mAh·cm -2 and 0.2 mA·cm -2 , 0.2 mAh·cm -2Cyclic stability test results under certain conditions. b and d are the electrolyte membranes formed after doping 1% 2D-COSi-Me at 0.1 mA·cm -2 、0.1 mAh·cm -2 and 0.2 mA·cm -2 、0.2 mAh·cm -2 conditions respectively. Fig.18 It shows that at 0.1 mA·cm -2 , 0.1 mAh·cm -2 (indicating a current density of 0.1 mA·cm -2 and a capacity density of 0.1 mA·cm -2 ) and 0.2 mA·cm -2 , 0.2 mAh·cm -2 conditions, the PEO electrolyte membrane can only operate stably for about 100 h and 60 h respectively, and its failure is manifested as battery short circuit. After doping 2D-COSi-Me, the battery can operate stably for more than 300 h and 230 h respectively at 0.1 mA·cm -2 , 0.1 mAh·cm -2 and 0.2 mA·cm -2 , 0.2 mAh·cm -2 conditions respectively. It can be seen that its stability is better than that of the PEO electrolyte membrane.

[0172] At 60 °C, 0.1 mA·cm -2 , 0.1 mAh·cm -2 conditions, the influence of the doping amount on the electrolyte stability was observed, and the results are as Fig.19 shown. Fig.19 It shows that after doping 1% 2D-COSi-Me, it can operate stably for 300 h (see a in Fig.19 ), after doping 1.5% 2D-COSi-Me, it can operate stably for 380 h (see b in Fig.19 ), after doping 2% 2D-COSi-Me, it can operate stably for up to 500 h at most (see c in Fig.19 ), and after doping 2.5% 2D-COSi-Me, the stable operation time is reduced to 340 h (see d in Fig.19 ). It shows that within a certain range, increasing the doping amount of 2D-COSi-Me can improve the electrolyte stability.

[0173] Variable-temperature electrochemical impedance spectroscopy tests were carried out in the range of 30 - 70 °C. By analyzing the relationship between the electron transfer resistance (R ct ) and temperature, using the Arrhenius formula (R: resistance; A: pre-exponential factor; E a: Activation energy; R: Gas constant; T: Temperature) to calculate the activation energy of electron transfer, and the results are as Fig. 20 shown in a of Fig. 20 . After comparison, after adding 1% 2D-COSi-Me to PEO, the activation energy of electron transfer decreases, from 0.370 eV to 0.283 eV. The decreased activation energy is further manifested in the change of conductivity. In the range of 30~70 °C, after adding 1% 2D-COSi-Me, the conductivity of the electrolyte increases by 25~800% (see Fig. 20 b of Fig. 20 ). Higher conductivity is beneficial to the cycle stability of the battery and reduces the growth of lithium dendrites during the cycling process of the battery.

[0174] In addition, the present invention also conducts a mechanical tensile test on the electrolyte membrane, and the results are shown in Fig.21 . It can be seen from Fig.21 that the fracture strength of the pure PEO electrolyte membrane is 0.36 MPa, and the maximum strain is 786%. After adding 1% 2D-COSi-Me, its mechanical properties are greatly improved. Its fracture strength and maximum strain are increased by about 1 time, reaching 0.84 MPa and 1561%, respectively. Better mechanical properties are also beneficial to improving the cycle stability of the battery and extending the battery life.

[0175] The above is only the preferred embodiment of the present invention. It should be noted that for those of ordinary skill in the art, without departing from the principle of the present invention, several improvements and refinements can be made, and these improvements and refinements should also be regarded as the protection scope of the present invention.

Claims

1. A dynamic two-dimensional organosilicon polymer, characterized in that: The structural unit has the structure shown in Formula 1: Formula 1; In formula 1, R is -C6H6.

2. The method for preparing the dynamic two-dimensional organosilicon polymer according to claim 1, characterized in that: The following steps are involved: (1) dissolving 2-(4-bromophenyl)-1,3-dioxolane in tetrahydrofuran and cooling to -60 to -95°C, adding an organic lithium reagent to carry out an intermediate reaction, adding a tetrahydrofuran solution of dichlorosilane to the obtained intermediate system and heating to room temperature to carry out a nucleophilic substitution reaction to obtain a compound with a structure shown in Formula 3; The dichlorosilane has a structure shown in Formula 2: Formula 2; Formula 3; In formula 2 and formula 3, R is -C6H6; (2) dissolving the compound of the structure represented by Formula 3 in acetone and mixing the mixture with water and a strong inorganic acid to carry out a deprotection reaction to obtain a compound of the structure represented by Formula 4; Formula 4; (3) The compound having the structure shown in Formula 4 is polymerized with melamine to obtain the dynamic two-dimensional organosilicon polymer.

3. The preparation method according to claim 2, characterized in that: In step (1), the molar ratio of 2-(4-bromophenyl)-1,3-dioxolane to dichlorosilane is (1-4):

1.

4. The preparation method according to claim 2 or 3, characterized in that: In step (1), the molar ratio of the 2-(4-bromophenyl)-1,3-dioxolane to the organic lithium reagent is 1:(0.5-1.5); The organic lithium reagent includes one or more of n-butyl lithium, sec-butyl lithium and tert-butyl lithium.

5. The preparation method according to claim 2, characterized in that: In step (2), the mass ratio of the compound of the structure represented by formula 3 to the volume ratio of water is 1 g: 8-12 mL.

6. The preparation method according to claim 2, characterized in that: In step (3), the polymerization reaction of the compound represented by formula 4 and melamine includes method 1 or method 2; The method 1 comprises the following steps: The compound of the structure shown in Formula 4 and melamine are dissolved in a mixed solvent, an organic weak acid catalyst is added to the obtained solution, and then the solution is vacuum-sealed and allowed to stand under vacuum-sealed conditions to perform a polymerization reaction; the mixed solvent is a combination of 1,4-dioxane and mesitylene, or a combination of n-butanol and o-dichlorobenzene; The second method comprises the following steps: The compound with the structure shown in Formula 4 and melamine are dissolved in a high boiling point solvent, an organic weak acid catalyst is added to the obtained solution, and a polymerization reaction is carried out in an inert atmosphere or a vacuum atmosphere under static conditions; the high boiling point solvent includes one or more of dimethyl sulfoxide, chlorobenzene, dichlorobenzene and N,N-dimethylformamide.

7. The preparation method according to claim 6, characterized in that: When the polymerization reaction is carried out using method 1 or method 2, the molar ratio of the compound with the structure represented by formula 4 to melamine is 3:(1.8-2.2).

8. The preparation method according to claim 6 or 7, characterized in that: When the polymerization reaction is carried out by method 1, the polymerization reaction temperature is 60-80° C. and the time is 60-80 hours; When the polymerization reaction is carried out using method 2, the polymerization reaction temperature is 110-130° C. and the time is 60-80 hours.

9. Use of the dynamic two-dimensional organosilicon polymer according to claim 1 or the dynamic two-dimensional organosilicon polymer prepared by the preparation method according to any one of claims 2 to 8 in an electrolyte membrane.

10. The use according to claim 9, characterized in that: The electrolyte membrane comprises a matrix, an electrolyte salt and a dynamic two-dimensional organic silicon polymer, wherein the mass of the dynamic two-dimensional organic silicon polymer is 1-5% of the mass of the matrix.

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