Sulfur-containing polymer electrolyte and method for preparing the same

Abstract

The embodiment of the application provides a sulfur-containing polymer electrolyte and a preparation method thereof, relates to the technical field of supercapacitors, and the preparation method comprises the following steps: mixing double-hydroxyl-terminated polyether sulfone, 4,4'-dimercaptodiphenyl sulfide and an N,N-dimethylformamide solution, the N,N-dimethylformamide solution comprising an electrolyte salt and N,N-dimethylformamide, and stirring at a constant temperature under the protection of an inert atmosphere to generate a monomer mixture; adding terephthaloyl chloride to the monomer mixture to perform a polycondensation reaction, so as to obtain a prepolymer solution; heating the prepolymer solution to perform a post-polymerization reaction, cooling the prepolymer solution to room temperature, adding trimethylolpropane triacrylate and a photoinitiator and uniformly dispersing, so as to obtain a mixed system; performing a cross-linking reaction on the mixed system under ultraviolet light irradiation, so as to form a three-dimensionally cross-linked sulfur-containing polymer electrolyte film; and performing drying treatment on the sulfur-containing polymer electrolyte film, so as to remove residual solvents and obtain a target sulfur-containing polymer electrolyte.

Description

Technical Field

[0001] This application relates to the technical field of supercapacitors, specifically to sulfur-containing polymer electrolytes and their preparation methods. Background Technology

[0002] As an energy storage device that combines high power density and long cycle life, supercapacitors have irreplaceable application value in fields such as new energy vehicles and smart grids. Their performance depends on the comprehensive performance of sulfur-containing polymer electrolytes.

[0003] High voltage is a key path to improve the energy density of supercapacitors. However, existing polymer electrolytes generally face technical bottlenecks such as insufficient mechanical strength, poor high voltage resistance, easy loss of sulfur-based active sites, and low ionic conductivity, which seriously restrict the upgrading of device performance.

[0004] To solve the above problems, there is an urgent need for a solution that combines excellent mechanical stability, high pressure resistance, high ionic conductivity and long cycle life with sulfur-containing polymer electrolyte. Summary of the Invention

[0005] This application proposes a sulfur-containing polymer electrolyte and its preparation method to address the deficiencies of the prior art.

[0006] According to a first aspect of the embodiments of this application, a method for preparing a sulfur-containing polymer electrolyte is provided, comprising:

[0007] Dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide, and an N,N-dimethylformamide solution, wherein the N,N-dimethylformamide solution comprises an electrolyte salt and N,N-dimethylformamide, are mixed and stirred at a constant temperature under an inert atmosphere until the monomers dissolve to generate a monomer mixture.

[0008] Terephthaloyl chloride was added to the monomer mixture to carry out a polycondensation reaction to obtain a prepolymer solution;

[0009] The prepolymer liquid was heated to carry out a post-polymerization reaction, and then the prepolymer liquid after the polymerization reaction was cooled to room temperature. Trimethylolpropane triacrylate as a crosslinking agent and a photoinitiator were added and dispersed evenly to obtain a mixed system.

[0010] The mixture was subjected to a cross-linking reaction under ultraviolet light irradiation to form a three-dimensional cross-linked sulfur-containing polymer electrolyte membrane;

[0011] The sulfur-containing polymer electrolyte membrane is dried to remove residual solvent, thereby obtaining the target sulfur-containing polymer electrolyte.

[0012] In some embodiments, the process includes, prior to mixing the dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide, and the solution mixture containing the electrolyte salt and N,N-dimethylformamide:

[0013] The dihydroxy-terminated polyethersulfone was placed in a drying oven for drying to remove adsorbed water;

[0014] The 4,4'-dimercaptodiphenyl sulfide was purified by recrystallization.

[0015] The terephthaloyl chloride is ground into powder to prevent moisture absorption and hydrolysis;

[0016] In a glove box, the electrolyte salt is mixed with the N,N-dimethylformamide to prepare an N,N-dimethylformamide solution.

[0017] In some embodiments, the functional group molar ratio of the dihydroxy-terminated polyethersulfone, the terephthaloyl chloride, the 4,4'-dimercaptodiphenyl sulfide and the trimethylolpropane triacrylate is 1:(1.05-1.3):(0.08-0.2):(0.02-0.05).

[0018] In some embodiments, the total mass of the dihydroxy-terminated polyethersulfone and the 4,4'-dimercaptodiphenyl sulfide accounts for 15-20 wt% of the mass of the N,N-dimethylformamide solution.

[0019] In some embodiments, the electrolyte salt is one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, or lithium bis(trifluoromethyl)sulfinate; the mass of the electrolyte salt accounts for 8-10 wt% of the mass of the target sulfur-containing polymer electrolyte.

[0020] In some embodiments, heating the prepolymer liquid to carry out a post-polymerization reaction includes:

[0021] The prepolymer liquid is heated to carry out a post-polymerization reaction at a heating temperature of 80-100℃.

[0022] In some embodiments, the photoinitiator is 2,2-dimethoxy-2-phenylacetophenone; the amount of the photoinitiator is 3-5 wt% of the mass of the crosslinking agent trimethylolpropane triacrylate.

[0023] In some embodiments, the crosslinking reaction of the mixture under ultraviolet light irradiation includes:

[0024] The mixture was subjected to a crosslinking reaction under ultraviolet light at a wavelength of 365 nm for 30-60 minutes.

[0025] In some embodiments, drying the sulfur-containing polymer electrolyte membrane includes:

[0026] The sulfur-containing polymer electrolyte membrane was dried in a vacuum drying oven at 60°C for 6 hours.

[0027] According to a second aspect of this application, a sulfur-containing polymer electrolyte is provided, which is prepared based on the preparation method of a sulfur-containing polymer electrolyte as described above.

[0028] The sulfur-containing polymer electrolyte has a three-dimensional cross-linked network structure formed by the condensation reaction of dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide and terephthaloyl chloride to form a polymer backbone, and cross-linked by trimethylolpropane triacrylate.

[0029] Electrolyte salts are interspersed within the three-dimensional cross-linked network structure.

[0030] The beneficial effects of the sulfur-containing polymer electrolyte and its preparation method in the embodiments of this application include at least the following:

[0031] This application's embodiments utilize a precise combination of dihydroxyl-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide, terephthaloyl chloride, trimethylolpropane triacrylate, and lithium salt to form a multi-dimensional synergistic system. The dihydroxyl-terminated polyethersulfone provides basic rigidity and chemical stability through its aromatic ring backbone. Its terminal hydroxyl groups undergo a polycondensation reaction with the acyl chloride groups of terephthaloyl chloride. Simultaneously, the sulfur-containing segments of 4,4'-dimercaptodiphenyl sulfide are anchored to the backbone through stable carbon-sulfur covalent bonds, forming a linear prepolymer framework. The trimethylolpropane triacrylate... Methylpropane triacrylate, as a multifunctional crosslinking agent, forms a three-dimensional network structure through UV crosslinking. This network intertwines and entangles with the linear segments of the polycondensation chain, filling structural gaps and limiting excessive segment creep. Furthermore, the dihydroxyl-terminated polyethersulfone forms a conjugated stable system with the aromatic ring structure of terephthaloyl chloride, synergistically enhancing high-pressure resistance through the three-dimensional crosslinking network. The thiol groups of 4,4'-dimercaptodiphenyl sulfide and the hydroxyl groups of the dihydroxyl-terminated polyethersulfone form a reactive gradient, achieving ordered polycondensation and preventing sulfur loss. Its sulfur-containing groups react with the Li groups released from the lithium salt. + Forming weak complexation, guiding Li + Directed migration, while the pore structure regulated by a three-dimensional cross-linked network is Li + It provides a continuous transport path; the acyl chloride group of terephthaloyl chloride has moderate reactivity and forms a stepwise reaction system with each monomer. Combined with the integrated process of "thermal prepolymerization-photocrosslinking" to improve the controllability and scalability of the reaction, the components complement each other and promote each other's functions. It successfully solves the bottlenecks in the existing technology, such as the imbalance between mechanical strength and high pressure resistance, serious sulfur loss, poor process controllability, and mutual restriction of performance. Finally, it achieves the comprehensive optimization of sulfur-containing polymer electrolyte in terms of mechanical strength, ionic conductivity, cycle stability and high pressure resistance. Attached Figure Description

[0032] Figure 1 This is a schematic flowchart of a method for preparing sulfur-containing polymer electrolytes according to an embodiment of this application;

[0033] Figure 2 The figures illustrate the parameters of Embodiments 1-8 and Comparative Examples 1-2 of this application.

[0034] Figure 3 This is a diagram illustrating the impedance variation in an embodiment of this application. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the sulfur-containing polymer electrolyte and its preparation method will be clearly and completely described below in conjunction with the accompanying drawings of the embodiments of this application. Obviously, the described embodiments are only some embodiments of the embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0036] Therefore, the following detailed description of the embodiments of the present application provided in the accompanying drawings is not intended to limit the scope of the claimed embodiments of the present application, but merely to illustrate selected embodiments of the present application. Other embodiments obtained by those skilled in the art based on the embodiments of the present application without inventive effort are all within the scope of protection of the embodiments of the present application.

[0037] It can be noted that similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it will not be further defined and explained in subsequent figures according to the embodiments of this application.

[0038] This application discloses a sulfur-containing polymer electrolyte and its preparation method. The sulfur-containing polymer electrolyte is prepared based on a method for preparing a sulfur-containing polymer electrolyte. The purpose is to add functional polymers such as dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide and terephthaloyl chloride to a solid electrolyte membrane and perform crosslinking polymerization through a crosslinking agent, thereby overcoming the shortcomings of the prior art.

[0039] See attached document Figure 1 As shown, the preparation method of the sulfur-containing polymer electrolyte includes steps 110-150.

[0040] Step 110: Mix dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide and N,N-dimethylformamide solution, and stir at a constant temperature under an inert atmosphere until the monomers dissolve to generate a monomer mixture.

[0041] This stage can also be understood as the raw material pretreatment stage.

[0042] The N,N-dimethylformamide solution comprises an electrolyte salt and N,N-dimethylformamide.

[0043] In some embodiments, before mixing the dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide, and the solution mixture containing the electrolyte salt and N,N-dimethylformamide, the following steps are included: drying the dihydroxy-terminated polyethersulfone in a drying oven to remove adsorbed water; purifying the 4,4'-dimercaptodiphenyl sulfide by recrystallization; and mixing the electrolyte salt (e.g., lithium salt) with the N,N-dimethylformamide in a glove box to prepare an N,N-dimethylformamide solution.

[0044] For example, the total mass of the dihydroxy-terminated polyethersulfone and the 4,4'-dimercaptodiphenyl sulfide accounts for 15-20 wt% of the mass of the N,N-dimethylformamide solution.

[0045] For example, the electrolyte salt (or lithium salt) is one of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, or lithium bistrifluoromethylsulfinate; the mass of the electrolyte salt accounts for 8-10 wt% of the mass of the target sulfur-containing polymer electrolyte.

[0046] For example, generating the monomer mixture may include: adding pretreated dihydroxy-terminated polyethersulfone and 4,4'-dimercaptodiphenyl sulfide to an argon-protected three-necked flask, injecting lithium salt / DMF electrolyte (i.e., the above-mentioned N,N-dimethylformamide solution), and stirring at a constant temperature until the monomers are completely dissolved. Another example is generating the monomer mixture by: drying the dihydroxy-terminated polyethersulfone in a vacuum drying oven at 80°C for 12 hours; preparing the LiPF6 / DMF electrolyte in an argon-filled glove box (water and oxygen content ≤0.1ppm), and stirring for 30 minutes until completely dissolved.

[0047] Step 120: Terephthaloyl chloride is added to the monomer mixture to carry out a polycondensation reaction to obtain a prepolymer solution.

[0048] This stage can also be understood as the prepolymerization reaction stage.

[0049] In some embodiments, the process further includes grinding the terephthaloyl chloride into a powder before mixing the dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide, and the solution mixture containing the electrolyte salt and N,N-dimethylformamide, to prevent moisture absorption and hydrolysis.

[0050] In some embodiments, the functional group molar ratio of the dihydroxy-terminated polyethersulfone, the terephthaloyl chloride, the 4,4'-dimercaptodiphenyl sulfide, and the trimethylolpropane triacrylate is 1:(1.05-1.3):(0.08-0.2):(0.02-0.05).

[0051] For example, adding terephthaloyl chloride to the monomer mixture includes: adding terephthaloyl chloride powder dropwise to the monomer mixture to carry out a polycondensation reaction, thereby obtaining a homogeneous and transparent prepolymer solution. For example, terephthaloyl chloride powder is added dropwise to the monomer mixture in three portions, and the reaction is maintained at 40°C for 2 hours after the addition is completed to obtain the prepolymer solution.

[0052] Step 130: The prepolymer liquid is heated to carry out a post-polymerization reaction. After the polymerization reaction, the prepolymer liquid is cooled to room temperature, and trimethylolpropane triacrylate as a crosslinking agent and a photoinitiator are added and dispersed evenly to obtain a mixed system.

[0053] This stage can also be understood as the post-polymerization and crosslinking agent introduction stage.

[0054] In some embodiments, heating the prepolymer liquid for post-polymerization includes heating the prepolymer liquid for post-polymerization based on a heating temperature of 80-100°C.

[0055] For example, the photoinitiator is 2,2-dimethoxy-2-phenylacetophenone.

[0056] For example, the amount of photoinitiator used is 3-5 wt% of the mass of the crosslinking agent trimethylolpropane triacrylate.

[0057] For example, the prepolymer liquid is heated to carry out a post-polymerization reaction, and then the prepolymer liquid after the polymerization reaction is cooled to room temperature. Trimethylolpropane triacrylate as a crosslinking agent and a photoinitiator are added and dispersed evenly to obtain a mixed system. The process includes: heating the prepolymer liquid to continue the reaction to promote the complete polycondensation reaction and increase the molecular weight of the polymer. After the system is naturally cooled to room temperature, trimethylolpropane triacrylate and the initiator (2,2-dimethoxy-2-phenylacetophenone) are added under light-protected conditions, and the mixture is stirred for 30 minutes to make the crosslinking agent and the initiator evenly dispersed in the system, thereby obtaining a mixed system.

[0058] Step 140: The mixture is subjected to a cross-linking reaction under ultraviolet light irradiation to form a three-dimensional cross-linked sulfur-containing polymer electrolyte membrane.

[0059] This stage can be understood as the ultraviolet cross-linking stage.

[0060] In some embodiments, the crosslinking reaction of the mixture under ultraviolet light irradiation includes: subjecting the mixture to ultraviolet light with a wavelength of 365 nm for a reaction time of 30-60 minutes.

[0061] Step 150: The sulfur-containing polymer electrolyte membrane is dried to remove residual solvent, thereby obtaining the target sulfur-containing polymer electrolyte.

[0062] This stage can be understood as the post-processing stage.

[0063] In some embodiments, the drying process of the sulfur-containing polymer electrolyte membrane includes: drying the sulfur-containing polymer electrolyte membrane in a vacuum drying oven at 60°C by removing residual electrolyte salts, N,N-dimethylformamide solvent, and trace bubbles for 6 hours.

[0064] In some embodiments, the method further includes: preparing a supercapacitor in the order of positive electrode shell, positive electrode sheet, sulfur-containing polymer electrolyte, graphite sheet, stainless steel sheet, spring sheet, and negative electrode shell, wherein the positive electrode is NCM523 doped with activated carbon and the negative electrode is natural graphite.

[0065] The method for preparing a sulfur-containing polymer electrolyte according to an embodiment of this application involves a multi-dimensional synergistic system formed by the precise formulation of dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide, terephthaloyl chloride, trimethylolpropane triacrylate, and lithium salt. The dihydroxy-terminated polyethersulfone provides basic rigidity and chemical stability through its aromatic ring backbone. Its terminal hydroxyl groups undergo a polycondensation reaction with the acyl chloride groups of terephthaloyl chloride. Simultaneously, the sulfur-containing segments of 4,4'-dimercaptodiphenyl sulfide are anchored to the backbone through stable carbon-sulfur covalent bonds, forming a linear chain. The prepolymer backbone, with trimethylolpropane triacrylate as a multifunctional crosslinking agent, forms a three-dimensional network structure through UV crosslinking. This network intertwines and entangles with the condensation linear segments, filling structural gaps and limiting excessive segment creep. Furthermore, the dihydroxyl-terminated polyethersulfone forms a conjugated stable system with the aromatic ring structure of terephthaloyl chloride, synergistically enhancing high-pressure resistance through the three-dimensional crosslinking network. The thiol groups of 4,4'-dimercaptodiphenyl sulfide and the hydroxyl groups of the dihydroxyl-terminated polyethersulfone form a reactive gradient, achieving ordered polycondensation and preventing sulfur loss. Its sulfur-containing groups react with the Li released from the lithium salt. + Forming weak complexation, guiding Li + Directed migration, while the pore structure regulated by a three-dimensional cross-linked network is Li +It provides a continuous transport path; the acyl chloride group of terephthaloyl chloride has moderate reactivity and forms a stepwise reaction system with each monomer. Combined with the integrated process of "thermal prepolymerization-photocrosslinking" to improve the controllability and scalability of the reaction, the components complement each other and promote each other's functions. It successfully solves the bottlenecks in the existing technology, such as the imbalance between mechanical strength and high pressure resistance, serious sulfur loss, poor process controllability, and mutual restriction of performance. Finally, it achieves the comprehensive optimization of sulfur-containing polymer electrolyte in terms of mechanical strength, ionic conductivity, cycle stability and high pressure resistance.

[0066] The following discloses a specific process of an embodiment of this application. This process demonstrates the differences in the embodiment of this application under different conditions of related components or ingredients and the comparison with related technology comparative examples by adjusting different parameters in Examples 1-8 and Comparative Examples 1-2.

[0067] Example 1: Dihydroxy-terminated polyethersulfone was dried in a vacuum oven at 80°C for 12 hours. A LiPF6 / DMF electrolyte was prepared in an argon-filled glove box (water and oxygen content ≤0.1ppm), and stirred for 30 minutes until completely dissolved. Dihydroxy-terminated polyethersulfone and 4,4'-dimercaptodiphenyl sulfide were added to an argon-protected three-necked flask, followed by the LiPF6 / DMF electrolyte. The mixture was heated to 40°C with stirring at 300 rpm and held at that temperature for 1 hour to dissolve. Terephthaloyl chloride powder was added dropwise in three portions, and the reaction was maintained at 40°C for 2 hours after the addition was complete to obtain a prepolymer. The prepolymer was heated to 80°C and reacted for 4 hours. After cooling to room temperature, trimethylolpropane triacrylate and an initiator (2,2-dimethoxy-2-phenylacetophenone) were added under light-protected conditions, and the mixture was stirred for 30 minutes to disperse evenly. The mixture was then irradiated with 365 nm ultraviolet light for 30 minutes to form a three-dimensional cross-linked sulfur-containing polymer electrolyte membrane. The electrolyte was dried in a vacuum drying oven at 60℃ for 6 hours to obtain a sulfur-containing polymer electrolyte. A supercapacitor was prepared in the following order: positive electrode shell, positive electrode sheet, sulfur-containing polymer electrolyte, graphite sheet, stainless steel sheet, spring sheet, and negative electrode shell. The positive electrode was NCM523 doped with activated carbon, and the negative electrode was natural graphite.

[0068] Example 2: The only difference between Example 1 and Example 2 is that the amount of 4,4'-dimercaptodiphenyl sulfide is adjusted to a functional group molar ratio of 0.12 (i.e., dihydroxyl-terminated polyethersulfone: 4,4'-dimercaptodiphenyl sulfide = 1:0.12). Everything else is the same as Example 1.

[0069] Example 3: The only difference from Example 1 is that the amount of trimethylolpropane triacrylate is adjusted to a functional group molar ratio of 0.04 (i.e., dihydroxy-terminated polyethersulfone: trimethylolpropane triacrylate = 1:0.04), and everything else is the same as Example 1.

[0070] Example 4: The only difference from Example 1 is that the amount of terephthaloyl chloride is adjusted to a functional group molar ratio of 1.10 (i.e., dihydroxy-terminated polyethersulfone: terephthaloyl chloride = 1:1.10), and everything else is the same as Example 1.

[0071] Example 5: The only difference from Example 1 is that the mass ratio of total monomer mass to solvent DMF is adjusted to 20wt%, and everything else is the same as Example 1.

[0072] Example 6: The only difference from Example 1 is that LiPF6 accounts for 10 wt% of the total mass of the sulfur-containing polymer; otherwise, it is the same as Example 1.

[0073] Example 7: The only difference from Example 1 is that the temperature in the post-polymerization stage is adjusted to 90°C; otherwise, it is the same as Example 1.

[0074] Example 8: The only difference from Example 1 is that the UV crosslinking time is adjusted to 45 min, and everything else is the same as Example 1.

[0075] Comparative Example 1: The only difference from Example 1 is that diamino-terminated polydimethylsiloxane is used instead of dihydroxy-terminated polyethersulfone, 2,6-pyridinedicarboxyl chloride is used instead of terephthaloyl chloride, and diaminodiphenyl disulfide is used instead of 4,4'-dimercaptodiphenyl sulfide. Trimethylolpropane triacrylate and photoinitiator are not added. The polymerization reaction is carried out at 50°C for 6 hours without UV crosslinking. Everything else is the same as in Example 1.

[0076] Comparative Example 2: The only difference from Example 1 is that 4,4'-dimercaptodiphenyl sulfide is not added; otherwise, it is the same as Example 1.

[0077] Table 1: Parameter display table for Examples 1-8 and Comparative Examples 1-2

[0078]

[0079] In Example 1, serving as the baseline, a synergistic system of rigid main chain + moderately cross-linked network + optimized sulfur-containing sites was constructed by precisely controlling core parameters such as the molar ratio of functional groups and solid-liquid ratio of each component, achieving a balanced and optimal performance across all aspects. In Example 2, while the increased amount of sulfur-containing monomer enriched the ion transport pathway and improved lithium-ion conductivity, the flexible sulfur-containing segments disrupted the rigidity of the main chain, resulting in a slight decrease in mechanical strength. In Example 3, increasing the amount of cross-linking agent enhanced the three-dimensional network density and improved mechanical strength, but reduced ion conductivity due to pore space compression. In Example 4, while increasing the excess proportion of acylated monomer ensured reaction completeness, the excess acylate chloride was prone to hydrolysis, generating impurities and causing slight fluctuations in mechanical strength. In Example 5, increasing the solid-liquid ratio enhanced the sulfur-containing density and mechanical strength, but increased ion transport resistance due to narrowed pores. In Example 6, increasing the amount of lithium salt improved the free Li-24 ratio.+ Concentration was used to increase ionic conductivity, but it damaged polymer chain segment compatibility, leading to a decrease in mechanical strength and high-pressure resistance. In Example 7, increasing the polymerization temperature accelerated the reaction rate, but the random entanglement of chain segments affected the regularity of the main chain, causing a slight deterioration in mechanical strength and interfacial properties. In Example 8, extending the UV crosslinking time promoted complete crosslinking, enhanced skeleton stability and mechanical strength, and reduced interfacial defects, but slight pore shrinkage led to a decrease in ionic conductivity. Comparative Example 1 used existing raw material systems but lacked crosslinking agents and UV crosslinking steps. The flexible main chain could not form a stable skeleton, and the sulfur-nitrogen bonds were easily broken, resulting in a large loss of sulfur. Ultimately, mechanical strength, high-pressure resistance, and ionic conductivity were all significantly deteriorated. Comparative Example 2 lacked sulfur-containing monomers, and Li + Insufficient directional migration pathways and poor interfacial compatibility significantly reduce ionic conductivity and cycling stability. The mechanical strength is only slightly improved due to the increased rigidity of the main chain, making it impossible to achieve optimal synergy among multiple performance parameters.

[0080] from Figure 2 It can be seen that, compared with Example 2, both Example 4 and Example 3 improved the electrochemical window, with Example 3 showing the most significant improvement.

[0081] from Figure 3 It can be seen that the impedance of Examples 1 and 4 is significantly reduced, mainly due to the key deficiency of Comparative Example 2, which is the absence of 4,4'-dimercaptodiphenyl sulfide, resulting in a lack of the regulatory effect of sulfur groups. On the one hand, the polymer has insufficient polarity, resulting in weak dissociation ability of LiPF6 and free Li + The low carrier concentration, coupled with the tendency of polymer chains to form local crystalline regions and a small proportion of amorphous regions, leads to a significant increase in bulk ion transport impedance. On the other hand, the lack of "anchoring" effect between sulfur groups and the electrode surface at the interface results in poor electrode-electrolyte interface compatibility, increased resistance to charge transfer processes, and further increases interfacial impedance.

[0082] This application also discloses a sulfur-containing polymer electrolyte, which is prepared based on the above-described method for preparing a sulfur-containing polymer electrolyte.

[0083] In some embodiments, the sulfur-containing polymer electrolyte has a three-dimensional cross-linked network structure formed by the polymerization of a polymer backbone composed of dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide and terephthaloyl chloride, and cross-linked via trimethylolpropane triacrylate.

[0084] Electrolyte salts are interspersed within this three-dimensional cross-linked network structure.

[0085] This application discloses a sulfur-containing polymer electrolyte. Through its unique structural design, namely, the condensation polymerization of rigid aromatic monomers to form a stable polymer backbone, and further constructing a three-dimensional network through a multifunctional crosslinking agent, while uniformly fixing the electrolyte salt within the network, it successfully achieves a synergistic improvement in mechanical strength, ionic conductivity, and electrochemical stability. This three-dimensional crosslinking structure not only effectively suppresses the disordered movement of polymer chain segments and avoids the loss of small molecule components, but also provides a continuous and stable transport channel for ion migration. Thus, it comprehensively solves the technical bottleneck of traditional polymer electrolytes in achieving both mechanical and electrochemical performance under high pressure, providing a key material basis for the preparation of energy storage devices with high energy density and long cycle life.

[0086] It is understood that the above embodiments are merely exemplary implementations used to illustrate the principles of this application, and this application is not limited thereto. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and substance of this application, and these modifications and improvements are also considered to be within the scope of protection of this application.

Claims

1. A method for preparing a sulfur-containing polymer electrolyte, characterized in that, include: Dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide, and an N,N-dimethylformamide solution, wherein the N,N-dimethylformamide solution comprises an electrolyte salt and N,N-dimethylformamide, are mixed and stirred at a constant temperature under an inert atmosphere until the monomers dissolve to generate a monomer mixture. Terephthaloyl chloride was added to the monomer mixture to carry out a polycondensation reaction to obtain a prepolymer solution; The prepolymer liquid was heated to carry out a post-polymerization reaction, and then the prepolymer liquid after the polymerization reaction was cooled to room temperature. Trimethylolpropane triacrylate as a crosslinking agent and a photoinitiator were added and dispersed evenly to obtain a mixed system. The mixture was subjected to a cross-linking reaction under ultraviolet light irradiation to form a three-dimensional cross-linked sulfur-containing polymer electrolyte membrane; The sulfur-containing polymer electrolyte membrane is dried to remove residual solvent, thereby obtaining the target sulfur-containing polymer electrolyte.

2. The method according to claim 1, characterized in that, Before mixing the dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide, and the solution mixture containing the electrolyte salt and N,N-dimethylformamide, the following steps are included: The dihydroxy-terminated polyethersulfone was placed in a drying oven for drying to remove adsorbed water; The 4,4'-dimercaptodiphenyl sulfide was purified by recrystallization. The terephthaloyl chloride is ground into powder to prevent moisture absorption and hydrolysis; In a glove box, the electrolyte salt is mixed with the N,N-dimethylformamide to prepare an N,N-dimethylformamide solution.

3. The method according to claim 1, characterized in that, The functional group molar ratio of the dihydroxy-terminated polyethersulfone, the terephthaloyl chloride, the 4,4'-dimercaptodiphenyl sulfide and the trimethylolpropane triacrylate is 1:(1.05-1.3):(0.08-0.2):(0.02-0.05).

4. The method according to claim 1, characterized in that, The total mass of the dihydroxy-terminated polyethersulfone and the 4,4'-dimercaptodiphenyl sulfide accounts for 15-20 wt% of the mass of the N,N-dimethylformamide solution.

5. The method according to claim 1, characterized in that, The electrolyte salt is one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, or lithium bis(trifluoromethyl)sulfinate; the mass of the electrolyte salt accounts for 8-10 wt% of the mass of the target sulfur-containing polymer electrolyte.

6. The method according to claim 1, characterized in that, The step of heating the prepolymer liquid to carry out the post-polymerization reaction includes: The prepolymer liquid is heated to carry out a post-polymerization reaction at a heating temperature of 80-100℃.

7. The method according to claim 1, characterized in that, The photoinitiator is 2,2-dimethoxy-2-phenylacetophenone; the amount of the photoinitiator is 3-5 wt% of the mass of the crosslinking agent trimethylolpropane triacrylate.

8. The method according to claim 1, characterized in that, The crosslinking reaction of the mixture under ultraviolet light irradiation includes: The mixture was subjected to a crosslinking reaction under ultraviolet light at a wavelength of 365 nm for 30-60 minutes.

9. The method according to claim 1, characterized in that, The drying process of the sulfur-containing polymer electrolyte membrane includes: The sulfur-containing polymer electrolyte membrane was dried in a vacuum drying oven at 60°C for 6 hours.

10. A sulfur-containing polymer electrolyte, prepared according to the preparation method of a sulfur-containing polymer electrolyte as described in any one of claims 1 to 9, characterized in that, The sulfur-containing polymer electrolyte has a three-dimensional cross-linked network structure formed by the condensation reaction of dihydroxy-terminated polyethersulfone, 4,4'-dimercaptodiphenyl sulfide and terephthaloyl chloride to form a polymer backbone, and cross-linked by trimethylolpropane triacrylate. Electrolyte salts are interspersed within the three-dimensional cross-linked network structure.

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