All-carbon skeleton polyarone cross-linked polymer-based solid electrolyte membrane and preparation method thereof

Abstract

The invention provides an all-carbon skeleton polyarone cross-linked polymer-based solid electrolyte membrane and a preparation method thereof, and relates to the technical field of polymer-based solid electrolyte. The structural formula of the all-carbon skeleton polyarone cross-linked polymer-based solid electrolyte disclosed by the invention is as shown in the following formula (I), the polymer electrolyte membrane material has good affinity with a positive electrode and a negative electrode of a lithium battery, high interface stability, low crystallinity, low porosity and small aperture, can simultaneously realize high ionic conductivity and mechanical strength, can also realize good flame retardance, and greatly enhances the safety performance of the battery.

Description

Technical Field

[0001] This application relates to the field of polymer-based solid electrolyte technology, and in particular to a full carbon skeleton polyaromatic ketone crosslinked polymer-based solid electrolyte membrane and its preparation method. Background Technology

[0002] Lithium-ion batteries (LIBs) have become a research hotspot in the new energy field due to their high energy density, long cycle life, and clean and environmentally friendly characteristics. However, traditional lithium-ion batteries using liquid electrolytes (LEs) have significant drawbacks: on the one hand, irregular lithium deposition during charging can easily lead to dendrite growth, resulting in a shortened battery cycle life; on the other hand, the inherent flammability and volatility of LEs pose safety hazards such as leakage, combustion, and explosion. These problems severely restrict their large-scale application. Developing solid-state lithium batteries (SSLIBs) provides a new approach to reducing lithium battery costs and improving safety. Compared to traditional liquid lithium-ion batteries, SSLIBs have significant advantages: firstly, their solid electrolytes can effectively suppress lithium dendrite growth, significantly reducing the risk of short circuits; secondly, solid electrolytes are compatible with high-capacity lithium metal anodes, allowing for a wider electrochemical window and enabling a leap in energy density; furthermore, the thermal stability of solid electrolytes is significantly better than that of liquid electrolytes, contributing to improved battery system safety and cycle life. These characteristics make SSLIBs a highly promising next-generation energy storage solution.

[0003] A key constraint hindering the large-scale application of solid-state electrolytes (SSEs) lies in the interfacial instability between them and the electrodes. Compared to liquid electrolyte lithium-ion batteries (LELIBs), where the liquid electrolyte can form sufficient and adaptive contact with the electrode surface, SSEs, due to their inherent rigidity, are prone to insufficient physical contact at the electrode-electrolyte interface, leading to a significant increase in interfacial resistance. This problem worsens during battery cycling; the volume changes of the electrode material during charge and discharge continuously disrupt the integrity of the interfacial structure, exacerbating interfacial contact failure and impedance increases. Therefore, constructing a solid-solid interface with high stability and low interfacial resistance is crucial for achieving efficient ion conduction and ensuring the overall performance of solid-state batteries. Polymer-based SSEs, with their excellent flexibility and processability, are considered an effective approach to addressing this solid-solid interface contact challenge. However, polymer-based SSEs suffer from low ionic conductivity. Currently, the main improvement is achieved by altering the polymer structure, such as constructing graft polymers with polymethacrylate as the main chain and polyether segments as side chains. This method reduces the polymer's crystallinity by lowering its glass transition temperature (Tg), thereby increasing its electrical conductivity. However, this process can damage the polymer's crystalline structure, leading to a decrease in mechanical strength.

[0004] Therefore, there is currently a lack of polymer-based solid electrolyte materials that possess both high interfacial stability, high conductivity, and high strength. Summary of the Invention

[0005] The purpose of this application is to address the shortcomings of existing technologies by providing a full carbon skeleton polyaryl ketone crosslinked polymer-based solid electrolyte membrane and its preparation method. This polymer electrolyte membrane material has good affinity with the positive and negative electrodes of lithium batteries, high interface stability, low crystallinity, low porosity and small pore size, and can simultaneously achieve high ionic conductivity and mechanical strength, as well as good rate performance and flame retardancy, which greatly enhances the safety performance of the battery.

[0006] To achieve the above objectives, the technical solution adopted in this application is as follows: According to one aspect of this application, a solid electrolyte membrane based on a fully carbon-backbone polyaryl ketone crosslinked polymer is provided, the structural formula of which is shown in formula (I) below: (I); In formula (I), Ar is an aromatic group; R is a fluorinated alkyl group; Group A is selected from any one of the following: halide ion, hexafluorophosphate ion, bis(trifluoromethanesulfonyl)imide ion, bis(fluorosulfonyl)imide ion, bicarbonate ion, and hydroxide ion; and: X and Y represent the molar ratio of the cross-linked and uncross-linked portions in a full-carbon skeleton polyaromatic ketone cross-linked polymer, respectively; X:Y = (1~50):(50~99); x+y=100; The weight-average molecular weight of all-carbon skeleton polyaryl ketone crosslinked polymers is 35–45 kDa; The polymer-based solid electrolyte membrane provided in this application has a cross-linked structure and quaternization, which gives it both excellent ion conductivity and mechanical strength. Its cross-linked structure is not only conducive to building a conductive three-dimensional network to achieve high ion conductivity, but its fluorinated chain also has strong flame retardancy, which greatly enhances the safety performance of the battery.

[0007] In the above-mentioned structural formula (I) of the all-carbon skeleton polyaryl ketone crosslinked polymer-based solid electrolyte, X:Y = (1-50):(50-99), and the value of X:Y can be 1:99, 2:98, 3:97, 4:96, 5:95, 6:94, 7:93, 8:92, 9:91, 10:90, 15:85, 20:80, 25:75, 30:70, 35:65, 40:60, 45:55, 50:50, or any range between them. Preferably, X:Y is any range between 10:90 and 15:85, for example, it can be 10:90, 11:89, 12:88, 13:87, 14:86, or 15:85.

[0008] Furthermore, in the above-mentioned all-carbon skeleton polyaryl ketone crosslinked polymers, the aromatic group is a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group; Preferably, the aromatic group is selected from any one or a combination of several of the structures shown in formula (II): , , , , , , , , , , , ; m is an integer from 2 to 8.

[0009] Furthermore, in the above-mentioned all-carbon skeleton polyaryl ketone crosslinked polymer-based solid electrolyte membrane, R is a fluorinated alkyl group; Preferably, R is selected from any one or a combination of several of the structures shown in formula (II) below: , , , , , , , .

[0010] According to another aspect of this application, a method for preparing the above-mentioned all-carbon skeleton polyaromatic ketone crosslinked polymer-based solid electrolyte membrane is provided, comprising the following steps: S1. Benzoyl peroxide (BPO) and N-bromosuccinimide (NBS) are added to a carbon tetrachloride solution of p-methyltrifluoroacetylbenzene to react. After the reaction is complete, the mixture is washed with water and evaporated to dryness to obtain the crude product. The crude product is then separated by column chromatography to obtain the pure product, i.e., p-bromomethyltrifluoroacetylbenzene. The reaction formula is shown below: ; S2. The aromatic monomer, p-bromomethyltrifluoroacetylbenzene, the first organic solvent, and the organic acid are mixed and subjected to a polycondensation reaction. After the reaction is complete, the mixture is poured into the first precipitant to precipitate, washed with water, and filtered to obtain polymer precursor 1. The reaction formula is shown below: ; S3. Dissolve polymer precursor 1 in a second organic solvent to obtain a polymer precursor 1 solution. Add alkali, followed by imidazole to react. After the reaction is complete, pour the solution into a second precipitant to precipitate, wash with water, and filter to obtain polymer precursor 2. The reaction formula is shown below: ; S4. Polymer precursor 2 is dissolved in a third organic solvent to obtain a polymer precursor 2 solution. An iodinated derivative of a fluoroalkane or perfluoroalkane is added to initiate a crosslinking reaction. After the reaction is complete, iodomethane is added to continue the reaction, yielding the target polymer solution. The reaction is shown below: ; S5. The target polymer solution obtained in step S4 is scraped and dried to obtain a thin film; the film is peeled off and immersed in a solution containing anions several times to obtain a solid electrolyte membrane.

[0011] Further, in step S1 of the preparation of the above-mentioned all-carbon skeleton polyaryl ketone crosslinked polymer, the molar ratio of methyltrifluoroacetylbenzene, NBS and BPO is 1:(1~1.2):(0.01~0.05); preferably, the molar ratio of methyltrifluoroacetylbenzene, NBS and BPO is 1:1.2:0.02; The reaction temperature is 60–70℃, and the reaction time is 12–16 h; preferably, the reaction temperature is 60℃, and the reaction time is 12 h. Further, in step S2 of the preparation of the above-mentioned all-carbon skeleton polyaryl ketone crosslinked polymer, the molar ratio of the aromatic hydrocarbon monomer to p-bromomethyltrifluoroacetylbenzene is 1:(1 to 1.3); for example, it can be 1:1, 1:1.05, 1:1.1, 1:1.15, 1:1.2, 1:1.25, 1:1.3 or any range therebetween; preferably, the molar ratio of the aromatic hydrocarbon monomer to p-bromomethyltrifluoroacetylbenzene is 1:(1 to 1.1). The aromatic monomers are the raw materials corresponding to the substituted or unsubstituted aryl groups and substituted or unsubstituted heteroaryl groups mentioned above. For example, the aromatic monomer corresponding to terphenyl is terphenyl, and the aromatic monomer corresponding to fluorene is fluorene. Therefore, they will not be described in detail here. The molar ratio of the organic superacid to p-bromomethyltrifluoroacetylbenzene is (1-20):1; for example, it can be 1:1, 1.5:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, 20:1 or any range therefrom; preferably, the molar ratio of the organic superacid to p-bromomethyltrifluoroacetylbenzene is (10-20):1; The volume ratio of the organic superacid to the first organic solvent is (0.1-1):1; for example, 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.7:1, 0.8:1, 0.9:1, 1:1; preferably, the volume ratio of the organic superacid to the first organic solvent is (0.5-1):1. The first organic solvent is selected from any one or a combination of several of dichloromethane, chloroform, and carbon tetrachloride; preferably, the first organic solvent is dichloromethane; The organic superacid is selected from any one or a combination of several of trifluoroacetic acid, trifluoromethanesulfonic acid, and methanesulfonic acid; preferably, the organic superacid is trifluoromethanesulfonic acid; The polycondensation reaction is carried out at a temperature of -5 to 5 °C, for example, it can be -5 °C, 0 °C or 5 °C; the time of the polycondensation reaction is 0.5 to 16 h, for example, it can be 0.5 h, 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, 9 h, 10 h, 11 h, 12 h, 13 h, 14 h, 15 h, 16 h; preferably, the polycondensation reaction is carried out at 0 °C, and the time of the polycondensation reaction is 14 to 16 h; The first precipitant is selected from any one or a combination of several of water, methanol, ethanol, potassium carbonate aqueous solution, sodium carbonate aqueous solution, sodium bicarbonate aqueous solution, sodium hydroxide aqueous solution, and potassium hydroxide aqueous solution. Preferably, the first precipitant is methanol; Further, in step S3 of the preparation of the above-mentioned all-carbon framework polyaryl ketone cross-linked polymer, the second organic solvent is selected from any one or a combination of several of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; preferably, the second organic solvent is dimethyl sulfoxide; The mass concentration of the polymer precursor 1 solution is 1 to 10%, for example, it can be 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any range therebetween; The base is selected from any one or a combination of several of sodium hydroxide, potassium hydroxide, sodium hydride, sodium methoxide, sodium tert-butoxide, and potassium tert-butoxide; the molar ratio of the base to the polymer precursor 1 is (1 to 1.1):1; The molar ratio of the imidazole to the polymer precursor 1 is (1 to 3):1; preferably, the molar ratio of the imidazole to the polymer precursor 1 is (1 to 1.5):1; The second precipitant is selected from any one or a combination of several of water, ethyl acetate, methanol, tetrahydrofuran, diethyl ether, or acetone; preferably, the second precipitant is methanol; The reaction temperature is room temperature, and the reaction time is 4 to 12 h.

[0012] Further, in step S4 of the preparation of the above-mentioned all-carbon framework polyaryl ketone cross-linked polymer, the third organic solvent is selected from any one or a combination of several of dimethyl sulfoxide, N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone; preferably, the third organic solvent is dimethyl sulfoxide; The iodinated derivative of the fluorinated alkane is selected from the raw material corresponding to the above-mentioned R group, preferably any one or a combination of several of the following: 1,2-diiodoperfluoroethane, 1,4-diiodoperfluorobutane, 1,6-diiodoperfluorohexane, 1,8-diiodoperfluorooctane, 1,5-diiodo-3,3'-difluoropentane, 1,6-diiodo-3,3',4,4'-tetrafluorohexane, 1,7-diiodo-3,3',4,4',5,5'-hexafluoroheptane, and 1,8-diiodo-3,3',4,4',5,5',6,6'-octafluorooctane; more preferably 1,2-diiodoperfluoroethane, 1,4-diiodoperfluorobutane, and 1,6-diiodoperfluorohexane. The mass concentration of the polymer precursor 2 solution is 1% to 10%, for example, it can be 1%, 1.5%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9%, 10% or any range thereof; The molar ratio of the iodinated fluoroalkane or perfluoroalkane to polymer precursor 2 is (0.01–0.2):1, for example, it can be 0.01:1, 0.02:1, 0.03:1, 0.04:1, 0.05:1, 0.06:1, 0.07:1, 0.08:1, 0.09:1, 0.1:1, 0.15:1, 0.2:1 or any range thereof; The temperature of the crosslinking reaction is 60–120°C; for example, it can be any range of 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 110°C, 120°C or therebetween; preferably, the temperature of the crosslinking reaction is 60–80°C. The cross-linking reaction time is 6 to 24 hours; preferably, the cross-linking reaction time is 6 hours. The reaction continues for 24 to 48 hours after the addition of iodomethane, preferably for 24 hours. Furthermore, in step S5 of the preparation of the above-mentioned all-carbon skeleton polyaryl ketone crosslinked polymer-based solid electrolyte membrane, the temperature of the substrate during the film-coating process is 60-120°C; for example, it can be any range between 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C, 110°C, and 120°C; preferably, the substrate temperature is 80°C. The drying temperature is 60 to 100°C, for example, it can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, 100°C or any range therebetween; preferably, the drying temperature is 100°C. In the aqueous solution containing anions, the anions are selected from any one of halide ions, hexafluorophosphate ions, bis(trifluoromethanesulfonyl)imide ions, bis(fluorosulfonyl)imide ions, bicarbonate ions, and hydroxide ions. Preferably, the anion is a bis(trifluoromethanesulfonyl)imide ion or a bis(fluorosulfonyl)imide ion; According to another aspect of this application, the above-mentioned all-carbon skeleton polyaryl ketone crosslinked polymer-based solid electrolyte membrane is provided for use in batteries.

[0013] Furthermore, the battery is any one of a lithium battery, a hydrogen-oxygen fuel cell, a methanol fuel cell, or a flow battery.

[0014] According to another aspect of this application, the above-mentioned all-carbon skeleton polyaromatic ketone crosslinked polymer-based solid electrolyte membrane is provided for use in alkaline exchange membrane water electrolysis to produce hydrogen.

[0015] Compared with the prior art, this application has the following beneficial effects: 1. This application provides a full carbon skeleton polyaromatic ketone crosslinked polymer electrolyte. The polymer has a full carbon aromatic crosslinked backbone and fluorine-containing side chains, which have good affinity with the positive and negative electrodes of lithium batteries and low crystallinity, which is conducive to the construction of a conductive three-dimensional network, thereby achieving high ionic conductivity. 2. The present application provides a full carbon skeleton polyaryl ketone crosslinked polymer electrolyte. The fluorinated side chains of the polymer have strong flame retardancy, which greatly enhances the safety performance of the battery. Attached Figure Description

[0016] Figure 1 This is a SEM image of the polymer solid electrolyte in Example 1 of this application; Figure 2 This is the IR spectrum of the polymer solid electrolyte in Example 1 of this application; Figure 3 This refers to the rate performance of the solid-state soft-pack lithium battery assembled with the polymer solid-state electrolyte in Example 1 of this application; Figure 4 The cycle performance of the solid-state soft-pack lithium batteries assembled with polymer solid-state electrolytes in Examples 1 and 2 of this application is shown. Detailed Implementation The following non-limiting embodiments are intended to enable those skilled in the art to gain a more comprehensive understanding of this application, but do not limit this application in any way. The following content is merely an exemplary description of the scope of protection claimed in this application, and those skilled in the art can make various changes and modifications to the invention based on the disclosed content, which should also fall within the scope of protection claimed in this application.

[0017] The present application will be further described below by way of specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of this application are obtained through conventional commercial means.

[0018] Example 1 This embodiment provides a method for preparing a solid electrolyte membrane based on a fully carbon-backbone polyaromatic ketone crosslinked polymer, comprising the following steps: S1. Dissolve 2.79 g of p-methyltrifluoroacetylbenzene in 20 mL of carbon tetrachloride solution, then add 0.10 g of benzoyl peroxide and 2.64 g of N-bromosuccinimide. Heat at 60 °C for 12 h, wash with water and evaporate to dryness to obtain crude product; separate the crude product by column chromatography to obtain 2.53 g of pure p-bromomethyltrifluoroacetylbenzene. S2. Add 2.19 g of p-terphenyl and 2.53 g of p-bromomethyltrifluoroacetylbenzene to a 250 mL round-bottom flask and dissolve them in 51 mL of dichloromethane. Place the reaction system in an ice bath and slowly add 51 mL of trifluoromethanesulfonic acid. After the addition is complete, continue the reaction at 0 °C for 16 h. After the reaction is complete, slowly pour the mixture into methanol to precipitate the precipitate. Wash the precipitate three times with deionized water, filter, and dry under vacuum to obtain 3.73 g of polymer precursor 1, namely poly(p-terphenyl-p-bromomethyltrifluoroacetylbenzene).

[0019] S3. Dissolve 3.73g of polymer precursor 1 in 50mL of dimethyl sulfoxide. First, add 1.08g of potassium carbonate, then add 0.80g of imidazole. After reacting at room temperature for 4h, pour the mixed solution into methanol to precipitate. Wash the precipitate three times with deionized water, filter, and dry under vacuum to obtain 3.21g of polymer precursor 2, a basic poly(p-terphenyl-p-dimethylaminemethyltrifluoroacetylbenzene); the weight-average molecular weight of the polymer is 40kDa.

[0020] S4. Dissolve 3.21g of polymer precursor 2 in 50mL of dimethyl sulfoxide, add 0.40g of 1,6-diiodoperfluorohexane, and react at 60℃ for 6h. After the reaction system is cooled to room temperature, add 0.5mL of iodomethane and continue the reaction for 24h to obtain the target polymer solution. S5. The target polymer solution is coated into a film at 60°C and dried in an oven at 100°C. After the film is formed, it is peeled off and immersed three times in 1 mol / L LiTFSI solution. The film is then dried to obtain the target polymer solid electrolyte membrane.

[0021] SEM images of the obtained polymer solid electrolyte membrane are as follows: Figure 1 As shown, the membrane surface is uniform and exhibits dense pores, which helps maintain interface stability.

[0022] The IR of the obtained polymer solid electrolyte membrane is as follows: Figure 2As shown, 3000-2800 cm -1 This is the C=N stretching vibration peak on the aromatic ring, at 2795 cm⁻¹. -1 The stretching vibration peak of quaternary ammonium salts is 1200 cm⁻¹. -1 The left and right sides are the bending vibration peaks of the -CF2- group.

[0023] A polymer solid electrolyte membrane is assembled into a solid-state soft-pack lithium battery, with lithium iron phosphate (LiFePO4) as the positive electrode and graphite as the negative electrode.

[0024] The assembled battery was tested for rate performance at 30°C, and the results are as follows: Figure 4 As shown, at a current of 1C (1C=35A), the capacity retention rate is 96.4% after 650 cycles.

[0025] Example 2 This embodiment provides a method for preparing a solid electrolyte membrane based on a fully carbon-backbone polyaromatic ketone crosslinked polymer, comprising the following steps: S1. Dissolve 2.79 g of p-methyltrifluoroacetylbenzene in 20 mL of carbon tetrachloride solution, then add 0.10 g of benzoyl peroxide (and 2.64 g of N-bromosuccinimide), heat at 60 °C for 12 h, wash with water and evaporate to dryness to obtain crude product; separate the crude product by column chromatography to obtain 2.53 g of pure p-bromomethyltrifluoroacetylbenzene; S2. In a 250 mL round-bottom flask, add 1.31 g of p-terphenyl, 0.88 g of m-terphenyl, and 2.53 g of p-bromomethyltrifluoroacetylbenzene, and dissolve them in 51 mL of dichloromethane. Place the reaction system in an ice bath and slowly add 51 mL of trifluoromethanesulfonic acid. After the addition is complete, continue the reaction at -5 °C for 14 h. After the reaction is complete, slowly pour the mixture into methanol to precipitate. Wash the precipitate three times with deionized water, filter, and vacuum dry to obtain 3.26 g of polymer precursor 1, i.e., poly(p-terphenyl-m-terphenyl-p-bromomethyltrifluoroacetylbenzene). S3. Dissolve 3.26g of polymer precursor 1 in 40mL of dimethyl sulfoxide, first add 0.95g of potassium carbonate, then add 0.72g of imidazole. After reacting at room temperature for 6 hours, pour the mixed solution into methanol to precipitate the precipitate. Wash the precipitate three times with deionized water, filter and vacuum dry to obtain 2.65g of polymer precursor 2, namely poly(p-terphenyl-m-terphenyl-p-dimethylaminemethyltrifluoroacetylbenzene).

[0026] S4. Dissolve 2.65 g of polymer precursor 2 in 40 mL of dimethyl sulfoxide solvent. First, add 0.14 g of 1,4-diiodoperfluorobutane and react at 80 °C for 6 h. After the reaction system cools to room temperature, add 0.34 mL of iodomethane and continue the reaction for 24 h to obtain the target polymer solution.

[0027] S5. The target polymer solution was coated into a film at 80°C, dried in an oven at 100°C, and after film formation, it was peeled off and immersed three times in a 1 mol / L LiTFSI solution, then dried to obtain the target polymer solid electrolyte membrane. The weight-average molecular weight of the polymer was 39 kDa.

[0028] A polymer solid electrolyte membrane was assembled into a solid-state pouch lithium battery, with lithium iron phosphate (LiFePO4) as the positive electrode and graphite as the negative electrode. The assembled battery was tested for cycle performance at 30°C, and the results are as follows: Figure 3 , 4 As shown. Figure 4 The results showed that the capacity retention was 96.8% after 650 cycles at a current of 1C (1C=35A).

[0029] Example 3 This embodiment provides a method for preparing a solid electrolyte membrane based on a fully carbon-backbone polyaromatic ketone crosslinked polymer, comprising the following steps: S1. Dissolve 4.17 g of p-methyltrifluoroacetylbenzene in 30 mL of carbon tetrachloride solution, then add 0.15 g of benzoyl peroxide (and 3.97 g of N-bromosuccinimide), heat at 60 °C for 12 h, wash with water and evaporate to dryness to obtain crude product; separate the crude product by column chromatography to obtain 3.80 g of pure p-bromomethyltrifluoroacetylbenzene; S2. Add 3.29 g of p-terphenyl and 3.80 g of p-bromomethyltrifluoroacetylbenzene to a 250 mL round-bottom flask and dissolve them in 70 mL of dichloromethane. Place the reaction system in an ice bath and slowly add 70 mL of trifluoromethanesulfonic acid. After the addition is complete, continue the reaction at 5 °C for 16 h. After the reaction is complete, slowly pour the mixture into methanol to precipitate the precipitate. Wash the precipitate three times with deionized water, filter, and dry under vacuum to obtain 5.46 g of polymer precursor 1, namely poly(p-terphenyl-p-bromomethyltrifluoroacetylbenzene).

[0030] S3. Dissolve 5.46g of polymer precursor 1 in 60mL of dimethyl sulfoxide, first add 2.13g of potassium carbonate, then add 1.20g of imidazole, react at room temperature for 12h, then pour the mixed solution into methanol to precipitate the precipitate, wash the precipitate three times with deionized water, filter and vacuum dry to obtain 5.48g of polymer precursor 2, methyl poly(p-terphenyl-p-dimethylaminemethyltrifluoroacetylbenzene).

[0031] S4. Dissolve 5.48g of polymer precursor 2 in 60mL of dimethyl sulfoxide, add 0.56g of 1,2-diiodoperfluoroethane, and react at 60℃ for 6h. After the reaction system is cooled to room temperature, add 0.6mL of iodomethane and continue the reaction for 24h to obtain the target polymer solution. S5. The target polymer solution is coated into a film at 80°C and dried in an oven at 100°C. After film formation, it is peeled off and immersed three times in 1 mol / L LiTFSI solution. The film is then dried to obtain the target polymer solid electrolyte membrane. The polymer weight-average molecular weight is 40 kDa.

[0032] A polymer solid electrolyte membrane is assembled into a solid-state soft-pack lithium battery, with lithium iron phosphate (LiFePO4) as the positive electrode and graphite as the negative electrode.

[0033] The assembled battery was tested for rate performance at 30°C. After 650 cycles at 1C (1C=35A) current, the capacity retention rate was 92.9%.

[0034] Comparative Example 1 This comparative example provides a method for preparing a solid electrolyte membrane based on a fully carbon-framework polyaromatic ketone crosslinked polymer, comprising the following steps: S1. Dissolve 2.79 g of p-methyltrifluoroacetylbenzene in 20 mL of carbon tetrachloride solution, then add 0.10 g of benzoyl peroxide and 2.64 g of N-bromosuccinimide. Heat at 60 °C for 12 h, wash with water and evaporate to dryness to obtain crude product; separate the crude product by column chromatography to obtain 2.53 g of pure p-bromomethyltrifluoroacetylbenzene. S2. Add 1.31 g of p-terphenyl, 0.88 g of m-terphenyl, and 2.53 g of p-bromomethyltrifluoroacetylbenzene to a 250 mL round-bottom flask, and dissolve them in 51 mL of dichloromethane. Place the reaction system in an ice bath and slowly add 51 mL of trifluoromethanesulfonic acid; after the addition is complete, continue the reaction at 0 °C for 4 h. After the reaction was complete, the mixture was slowly poured into methanol to precipitate. The precipitate was washed three times with deionized water, filtered, and then dried under vacuum to obtain 3.26 g of polymer precursor 1, namely poly(p-terphenyl-m-terphenyl-p-bromomethyltrifluoroacetylbenzene). S3. Dissolve 3.26g of polymer precursor 1 in 40mL of dimethyl sulfoxide, first add 0.95g of potassium carbonate, then add 0.72g of imidazole, react at room temperature for 6h, pour the mixed solution into methanol to precipitate, wash the precipitate three times with deionized water, filter and vacuum dry to obtain 2.65g of polymer precursor 2, namely poly(p-terphenyl-m-terphenyl-p-dimethylaminemethyltrifluoroacetylbenzene). S4. Dissolve 2.65 g of polymer precursor 2 in 40 mL of dimethyl sulfoxide solvent. First, add 0.14 g of 1,4-diiodoperfluorobutane and react at 60 °C for 6 h. After the reaction system cools to room temperature, add 0.34 mL of iodomethane and continue the reaction for 24 h to obtain the target polymer solution. Coat the solution into a film, dry it in an oven at 100 °C, peel it off after film formation, immerse it three times in 1 mol / L LiTFSI solution, and dry it to obtain the target polymer-based solid electrolyte membrane; its weight-average molecular weight is 12 kDa.

[0035] A polymer solid electrolyte membrane was assembled into a solid-state pouch lithium battery, with lithium iron phosphate (LiFePO4) as the positive electrode and graphite as the negative electrode. The assembled battery was tested for cycle performance at 30°C. After 250 cycles at 1C (1C=35A), it failed due to over-discharge.

[0036] Comparative Example 2 This comparative example provides a method for preparing a solid electrolyte membrane based on a fully carbon-framework polyaromatic ketone polymer, comprising the following steps: S1. Dissolve 2.79 g of p-methyltrifluoroacetylbenzene in 20 mL of carbon tetrachloride solution, then add 0.10 g of benzoyl peroxide and 2.64 g of N-bromosuccinimide. Heat at 60 °C for 12 h, wash with water and evaporate to dryness to obtain crude product; separate the crude product by column chromatography to obtain 2.53 g of pure p-bromomethyltrifluoroacetylbenzene. S2. Add 2.19 g of p-terphenyl and 2.53 g of p-bromomethyltrifluoroacetylbenzene to a 250 mL round-bottom flask and dissolve them in 51 mL of dichloromethane. Place the reaction system in an ice bath and slowly add 51 mL of trifluoromethanesulfonic acid. After the addition is complete, continue the reaction at 0 °C for 16 h. After the reaction is complete, slowly pour the mixture into methanol to precipitate the precipitate. Wash the precipitate three times with deionized water, filter, and dry under vacuum to obtain 3.73 g of polymer precursor 1, namely poly(p-terphenyl-p-bromomethyltrifluoroacetylbenzene).

[0037] S3. Dissolve 3.73g of polymer precursor 1 in 50mL of dimethyl sulfoxide, first add 1.08g of potassium carbonate, then add 0.80g of imidazole, react at room temperature for 6h, pour the mixed solution into methanol to precipitate, wash the precipitate three times with deionized water, filter and vacuum dry to obtain 3.21g of polymer precursor 2, methyl-p-terphenyl-p-dimethylaminemethyltrifluoroacetylbenzene.

[0038] S4. The target polymer solution is coated into a film and dried in an oven at 100°C. After the film is formed, it is peeled off and immersed three times in a 1 mol / L LiTFSI solution. The film is then dried to obtain the target polymer solid electrolyte membrane.

[0039] This uncrosslinked polymer solid electrolyte membrane was assembled into a solid-state pouch lithium battery, with lithium iron phosphate (LiFePO4) as the positive electrode and graphite as the negative electrode. The assembled battery was tested for cycle performance at 30°C. At a 1C (1C=35A) current, the capacity retention rate was 72.9% after 650 cycles.

[0040] Comparative Example 3 This comparative example provides a method for preparing a solid electrolyte membrane based on a fully carbon-framework polyaromatic ketone crosslinked polymer, comprising the following steps: S1. Dissolve 2.79 g of p-methyltrifluoroacetylbenzene in 20 mL of carbon tetrachloride solution, then add 0.10 g of benzoyl peroxide and 2.64 g of N-bromosuccinimide. Heat at 60 °C for 12 h, wash with water and evaporate to dryness to obtain crude product; separate the crude product by column chromatography to obtain 2.53 g of pure p-bromomethyltrifluoroacetylbenzene. S2. In a 250 mL round-bottom flask, add 1.58 g of 9,9-diethylfluorene and 2.53 g of p-bromomethyltrifluoroacetylbenzene, and dissolve them in 51 mL of dichloromethane. Place the reaction system in an ice bath and slowly add 51 mL of trifluoromethanesulfonic acid. After the addition is complete, continue the reaction at -5 °C for 14 h. After the reaction is complete, slowly pour the mixture into methanol to precipitate. Wash the precipitate three times with deionized water, filter, and dry under vacuum to obtain 2.36 g of polymer precursor 1, namely poly(diethylfluorene-p-bromomethyltrifluoroacetylbenzene). S3. Dissolve 2.36g of polymer precursor 1 in 40mL of dimethyl sulfoxide, first add 0.68g of potassium carbonate, then add 0.54g of imidazole. After reacting at room temperature for 6 hours, pour the mixed solution into methanol to precipitate the precipitate. Wash the precipitate three times with deionized water, filter and vacuum dry to obtain 2.03g of polymer precursor 2, namely poly(diethylfluorene-p-dimethylaminemethyltrifluoroacetylbenzene).

[0041] S4. Dissolve 2.03 g of polymer precursor 2 in 20 mL of dimethyl sulfoxide solvent. First, add 0.095 g of 1,4-diiodoperfluorobutane and react at 80 °C for 6 h. After the reaction system cools to room temperature, add 0.23 mL of iodomethane and continue the reaction for 24 h to obtain the target polymer solution.

[0042] S5. The target polymer solution was coated into a film at 80°C, dried in an oven at 100°C, and after film formation, it was peeled off and immersed three times in a 1 mol / L LiTFSI solution, then dried to obtain the target polymer solid electrolyte membrane. The weight-average molecular weight of the polymer was 36 kDa.

[0043] A polymer solid electrolyte membrane was assembled into a solid-state pouch lithium battery, with lithium iron phosphate (LiFePO4) as the positive electrode and graphite as the negative electrode. The assembled battery was tested for cycle performance at 30°C. After 650 cycles at a 1C (1C=35A) current, the capacity retention rate was 35.2%.

[0044] Comparative Example 4 This comparative example provides a method for preparing a solid electrolyte membrane based on a fully carbon-framework polyaromatic ketone crosslinked polymer, comprising the following steps: S1. Dissolve 2.79 g of p-methyltrifluoroacetylbenzene in 20 mL of carbon tetrachloride solution, then add 0.10 g of benzoyl peroxide and 2.64 g of N-bromosuccinimide. Heat at 60 °C for 12 h, wash with water and evaporate to dryness to obtain crude product; separate the crude product by column chromatography to obtain 2.53 g of pure p-bromomethyltrifluoroacetylbenzene. S2. Add 2.19 g of p-terphenyl and 2.53 g of p-bromomethyltrifluoroacetylbenzene to a 250 mL round-bottom flask and dissolve them in 51 mL of dichloromethane. Place the reaction system in an ice bath and slowly add 51 mL of trifluoromethanesulfonic acid. After the addition is complete, continue the reaction at 0 °C for 16 h. After the reaction is complete, slowly pour the mixture into methanol to precipitate the precipitate. Wash the precipitate three times with deionized water, filter, and dry under vacuum to obtain 3.73 g of polymer precursor 1, namely poly(p-terphenyl-p-bromomethyltrifluoroacetylbenzene).

[0045] S3. Dissolve 3.73g of polymer precursor 1 in 50mL of dimethyl sulfoxide, first add 1.08g of potassium carbonate, then add 0.80g of imidazole, react at room temperature for 4h, then pour the mixed solution into methanol to precipitate the precipitate, wash the precipitate three times with deionized water, filter and vacuum dry to obtain 3.21g of polymer precursor 2, methyl poly(p-terphenyl-p-dimethylaminemethyltrifluoroacetylbenzene).

[0046] S4. Dissolve 3.21g of polymer precursor 2 in 50mL of dimethyl sulfoxide, add 0.32g of 1,5-diiodopentane, and react at 60℃ for 6h. After the reaction system cools to room temperature, add 0.5mL of iodomethane and continue the reaction for 24h to obtain the target polymer solution; the weight average molecular weight of the polymer is 40kDa.

[0047] S5. The target polymer solution is coated into a film at 60°C and dried in an oven at 100°C. After the film is formed, it is peeled off and immersed three times in 1 mol / L LiTFSI solution. The film is then dried to obtain the target polymer solid electrolyte membrane.

[0048] The assembled battery was tested for rate performance at 30°C. After 650 cycles at 1C (1C=35A) current, the capacity retention rate was 60.3%.

[0049] Test case The polymer solid electrolyte membranes prepared in the above embodiments and comparative examples were tested, and the results are shown in Table 1 below.

[0050] As shown in the table, the polymer solid electrolyte membranes in Examples 1-3 can simultaneously achieve high ionic conductivity and mechanical strength, and have good rate performance, which greatly enhances the safety performance of the battery.

[0051] Table 1. Performance of polymer solid electrolyte membranes

[0052] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, this application is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of this application without departing from the scope of this application should be within the protection scope of this application.

Claims

1. A solid electrolyte membrane based on a fully carbon-framework polyaromatic ketone crosslinked polymer, characterized in that, The structural formula of the all-carbon skeleton polyaromatic ketone crosslinked polymer is shown in formula (I) below: （I）； In formula (I), Ar is an aromatic group; R is a fluorinated alkyl group; Group A is selected from any one of the following: halide ion, hexafluorophosphate ion, bis(trifluoromethanesulfonyl)imide ion, bis(fluorosulfonyl)imide ion, bicarbonate ion, and hydroxide ion; and: X and Y represent the molar ratio of the cross-linked and uncross-linked portions in a full-carbon skeleton polyaromatic ketone cross-linked polymer, respectively; X:Y = (1~50):(50~99); x+y=100; The weight-average molecular weight of all-carbon skeleton polyaromatic ketone crosslinked polymers is 35–45 kDa.

2. The all-carbon skeleton polyaromatic ketone crosslinked polymer-based solid electrolyte membrane according to claim 1, characterized in that, The aromatic group is a substituted or unsubstituted aryl group or a substituted or unsubstituted heteroaryl group; Preferably, the aromatic group is selected from any one or a combination of several of the structures shown in formula (II): 、 、 、 、 、 、 、 、 、 、 、 ； m is an integer from 2 to 8.

3. The all-carbon skeleton polyaromatic ketone crosslinked polymer-based solid electrolyte membrane according to claim 1, characterized in that, R is a fluorinated alkyl group; Preferably, R is selected from any one or a combination of several of the structures shown in formula (II) below: 、 、 、 、 、 、 、 。 4. The method for preparing the all-carbon skeleton polyaromatic ketone crosslinked polymer-based solid electrolyte membrane according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Benzoyl peroxide (BPO) and N-bromosuccinimide (NBS) were added to a carbon tetrachloride solution of p-methyltrifluoroacetylbenzene. The mixture was heated at 60-70°C for 12-16 hours, washed with water and evaporated to dryness to obtain the crude product. The crude product was separated by column chromatography to obtain p-bromomethyltrifluoroacetylbenzene. S2. Mix the aromatic monomer, p-bromomethyltrifluoroacetylbenzene, the first organic solvent, and the organic acid to carry out a polycondensation reaction; after the reaction is complete, pour the mixture into the first precipitant to precipitate, wash with water, and filter to obtain polymer precursor 1; S3. Dissolve polymer precursor 1 in a second organic solvent to obtain polymer precursor 1 solution, add alkali, and then add imidazole to react; after the reaction is complete, pour into a second precipitant to precipitate, wash with water and filter to obtain polymer precursor 2; S4. Dissolve polymer precursor 2 in a third organic solvent to obtain polymer precursor 2 solution, add a fluoroalkane or a perfluoroalkane derivative to carry out cross-linking reaction, after the reaction is complete, add iodomethane to continue the reaction to obtain target polymer solution. S5. The target polymer solution obtained in step S4 is scraped and dried to obtain a thin film; the film is peeled off and immersed in a solution containing anions several times to obtain a solid electrolyte membrane.

5. The preparation method according to claim 4, characterized in that, Includes the following steps: In step S1, the molar ratio of the aromatic hydrocarbon monomer to p-bromomethyltrifluoroacetylbenzene is 1:(1 to 1.3); the polycondensation reaction is carried out at a temperature of -5 to 5°C.

6. The preparation method according to claim 4, characterized in that, Includes the following steps: In step S3, the molar ratio of the crosslinking agent to the polymer precursor 2 is (0.01-0.2):1; the temperature of the crosslinking reaction is 60-120°C.

7. The preparation method according to claim 4, characterized in that, Includes the following steps: In step S4, the temperature of the film scraping treatment is 60-120℃, and the anion in the aqueous solution containing anions is selected from any one of halide ions, hexafluorophosphate ions, bis(trifluoromethanesulfonyl)imide ions, bis(fluorosulfonyl)imide ions, bicarbonate ions, and hydroxide ions.

8. The application of the all-carbon skeleton polyaryl ketone crosslinked polymer-based solid electrolyte membrane according to any one of claims 1-3 in batteries.

9. The application according to claim 8, characterized in that, The battery can be any one of lithium battery, hydrogen-oxygen fuel cell, methanol fuel cell, or flow battery.

10. The application according to claim 8, characterized in that, The applications include hydrogen production via alkaline exchange membrane water electrolysis.

Images