High-voltage composite gel polymer electrolyte and method for preparing the same

Abstract

The application discloses a high-pressure composite gel polymer electrolyte and a preparation method thereof. The preparation method comprises the following steps: generating an intermediate in an acidic aqueous solution, and synthesizing a fluorine-modified 1,3-dioxolane monomer under alkaline conditions; refluxing the acid pretreated inorganic nanoparticles and a silane coupling agent in a second organic solvent to prepare a modified inorganic functional material grafted with a polymerizable functional group on the surface; dispersing natural polysaccharides in a third organic solvent to form a uniform natural polysaccharide dispersion liquid; adding the modified inorganic functional material into the natural polysaccharide dispersion liquid to obtain a polysaccharide-inorganic composite dispersion liquid; adding the fluorine-modified 1,3-dioxolane monomer, an initiator and an electrolyte lithium salt into the polysaccharide-inorganic composite dispersion liquid to obtain a polymerization reaction mixture; performing temperature rising treatment and vacuum drying, and obtaining the high-pressure composite gel polymer electrolyte.

Description

Technical Field

[0001] This application relates to the technical field of supercapacitors, and more particularly to high-voltage composite gel polymer electrolytes and their preparation methods. Background Technology

[0002] Supercapacitors, as energy storage devices with high power density and long cycle life, have broad application prospects in new energy vehicles, flexible electronic devices and other fields. Their performance depends on the comprehensive performance of gel polymer electrolyte (GPE).

[0003] Traditional liquid electrolytes suffer from defects such as leakage and poor safety, while existing GPE systems face many bottlenecks, such as: narrow electrochemical stability window, making it difficult to adapt to high-voltage energy storage requirements; low room temperature ionic conductivity, limiting the rate performance of devices; insufficient mechanical strength, failing to meet the deformation requirements of flexible devices; and, at the same time, the raw materials mostly rely on non-renewable fossil-based polymers, making the preparation process complex and environmentally unfriendly.

[0004] Therefore, developing a GPE that combines high voltage resistance, high ionic conductivity, excellent mechanical properties, and environmental friendliness is key to solving the aforementioned technical problems and breaking through the performance bottleneck of supercapacitors. Summary of the Invention

[0005] This application proposes a high-pressure composite gel polymer electrolyte and its preparation method to overcome the deficiencies of the prior art.

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

[0007] In an acidic aqueous solution, epoxybromopropane is condensed with paraformaldehyde to generate an intermediate, and under alkaline conditions, the intermediate is nucleophilically substituted with trifluoroethanol in a first organic solvent to synthesize a fluorine-modified 1,3-dioxolane monomer.

[0008] Inorganic nanoparticles are pretreated with acid, and then the pretreated inorganic nanoparticles are refluxed with a silane coupling agent in a second organic solvent to prepare modified inorganic functional materials with polymerizable functional groups grafted on their surface.

[0009] Under an inert atmosphere, natural polysaccharides are dispersed in a third organic solvent to form a uniform natural polysaccharide dispersion, wherein the third organic solvent is an anhydrous organic solvent.

[0010] The modified inorganic functional material is added to the natural polysaccharide dispersion and dispersed to obtain a polysaccharide inorganic composite dispersion.

[0011] The fluorine-modified 1,3-dioxolane monomer, initiator, and electrolyte lithium salt are added to the polysaccharide inorganic composite dispersion, and an in-situ ring-opening polymerization reaction is carried out under inert gas protection to obtain the polymerization reaction mixture.

[0012] The polymerization reaction mixture is subjected to heating and vacuum drying to obtain the high-pressure composite gel polymer electrolyte. The heating treatment is used to promote cross-linking and gel formation, and the vacuum drying is used to remove residual solvent and moisture.

[0013] In some embodiments, the condensation reaction of epibromopropane with paraformaldehyde in an acidic aqueous solution to generate an intermediate includes:

[0014] In a reaction vessel, the epichlorohydrin, deionized water, and phosphoric acid are mixed to obtain a pre-reaction system;

[0015] The pre-reaction system is heated to 75-85℃ and subjected to a first stirring reaction to obtain the target reaction system;

[0016] Paraformaldehyde was added to the target reaction system, and a second stirring reaction was carried out at 75-85°C for 4-5 hours.

[0017] The target reaction system undergoing the second stirring reaction was cooled to room temperature, and the pH of the cooled target reaction system was adjusted to 7.0±0.2 using an aqueous sodium carbonate solution to obtain a neutral reaction solution;

[0018] The neutral reaction solution was extracted with dichloromethane to combine the organic phases, and a drying agent, anhydrous calcium chloride, was added to the combined organic phases for drying.

[0019] The anhydrous calcium chloride in the dried organic phase was filtered and removed, and the resulting filtrate was subjected to vacuum distillation to obtain the intermediate, which is 4-bromomethyl-1,3-dioxolane.

[0020] In some embodiments, the nucleophilic substitution reaction of the intermediate with trifluoroethanol in a first organic solvent under alkaline conditions for the synthesis of a fluorinated modified 1,3-dioxolane monomer includes:

[0021] Under conditions below a preset temperature, trifluoroethanol and triethylamine are dissolved in anhydrous dioxane, which serves as the first organic solvent, to form a first mixture.

[0022] The intermediate is dissolved in a second anhydrous dioxane, and the intermediate dissolved in the second anhydrous dioxane is slowly added dropwise to the first mixture under stirring, and the mixture is reacted at a constant temperature of -5°C for 3-4 hours.

[0023] The first reaction solution obtained from the isothermal reaction was filtered to remove the generated triethylammonium bromide precipitate, and the filtrate was concentrated to remove most of the solvent. Then, it was subjected to vacuum distillation to collect the crude product. The crude product was refluxed with calcium hydride to remove water, and then subjected to vacuum distillation again to obtain the fluorine-modified 1,3-dioxolane monomer.

[0024] In some embodiments, the step of pretreating the inorganic nanoparticles with acid, and then subjecting the pretreated inorganic nanoparticles to a reflux reaction with a silane coupling agent in a second organic solvent, is used to prepare modified inorganic functional materials with polymerizable functional groups grafted onto their surfaces, comprising:

[0025] Barium titanate nanoparticles and silica nanoparticles were mixed at a certain mass ratio and then ultrasonically dispersed in anhydrous ethanol to obtain a dispersion.

[0026] Dilute hydrochloric acid was added to the dispersion and stirred until the pH of the dispersion was adjusted to 3.0. The resulting second mixture was then centrifuged to collect the solid precipitate.

[0027] The solid precipitate was washed with anhydrous ethanol and then dried to obtain pretreated composite nanoparticles.

[0028] The pretreated composite nanoparticles were dispersed in anhydrous toluene as the second organic solvent, ultrasonically dispersed, heated to 80°C, and a silane coupling agent was added under nitrogen protection for stirring and reflux reaction, the duration of which was 4-5 hours.

[0029] The second reaction solution obtained from the reflux reaction was cooled to room temperature and then centrifuged. The solid precipitate of the second reaction solution after centrifugation was collected and washed with anhydrous toluene and acetone in sequence, and then dried to obtain the modified inorganic functional material.

[0030] In some embodiments, the silane coupling agent is γ-methacryloyloxy, propyltrimethoxysilane, or aminopropyltriethoxysilane.

[0031] In some embodiments, the natural polysaccharide is one of carboxymethyl cellulose, carboxymethyl chitosan, carboxymethyl starch, xanthan gum, hydroxypropyl guar gum, or dextran; the third organic solvent is anhydrous acetonitrile or anhydrous N,N-dimethylformamide; and the mass fraction of the natural polysaccharide in the natural polysaccharide dispersion is 2%-3%.

[0032] In some embodiments, adding the modified inorganic functional material to the natural polysaccharide dispersion and performing dispersion treatment includes:

[0033] The modified inorganic functional material was added to the natural polysaccharide dispersion, and the dispersion treatment was carried out at 35°C with ultrasound and stirring.

[0034] The amount of the modified inorganic functional material added is 5%-8% of the mass of the natural polysaccharide dispersion.

[0035] In some embodiments, the initiator is azobisisobutyronitrile (AIBN), and the electrolyte lithium salt is one of lithium hexafluorophosphate, lithium bis(fluorosulfonyl)imide, or lithium bis(trifluoromethylsulfonyl)imide. The method further includes:

[0036] The amount of lithium salt added to the electrolyte is determined based on the concentration of lithium salt in the high-pressure composite gel polymer electrolyte being 1-1.5M.

[0037] In-situ ring-opening polymerization was carried out under inert gas protection and stirring at 40°C for 6 hours to obtain the polymerization reaction mixture.

[0038] In some embodiments, the heating and vacuum drying of the polymerization reaction mixture includes:

[0039] The polymerization reaction mixture was heated to 60°C and stirred for 2 hours.

[0040] The polymerization reaction mixture, after being stirred for 2 hours, was vacuum dried for 8 hours at 45°C.

[0041] According to a second aspect of this application, a high-pressure composite gel polymer electrolyte is provided, which is prepared by the preparation method of the high-pressure composite gel polymer electrolyte described above.

[0042] The beneficial effects of the high-pressure composite gel polymer electrolyte and its preparation method in the embodiments of this application include at least the following:

[0043] This application's embodiments demonstrate how the condensation of epibromopropane and paraformaldehyde under acidic conditions constructs a 1,3-dioxolane intermediate framework with an active reactive bromomethyl group. Subsequently, through nucleophilic substitution with trifluoroethanol under alkaline conditions, a highly electronegative fluorinated group (trifluoroethoxy) is precisely introduced into this framework, laying the foundation for the final polymer electrolyte to possess hydrophobic properties and a wider electrochemical stability window. Acid pretreatment of the inorganic nanoparticles effectively cleans their surface and activates hydroxyl groups, preparing them for subsequent chemical grafting. Subsequent surface modification using a silane coupling agent under reflux conditions allows for the covalent grafting of polymerization-particulate functional groups such as double bonds onto the surface. This significantly improves the compatibility and interfacial bonding between the inorganic particles and the organic polymer matrix, preventing phase separation. Operating under an inert atmosphere effectively prevents the degradation or deterioration of air- or moisture-sensitive natural polysaccharides and their solvent systems, ensuring the activity of the raw materials. Pre-dispersing the natural polysaccharides in an anhydrous organic solvent to form a homogeneous solution ensures the full extension of the polysaccharide molecular chains, creating conditions for their subsequent uniform compounding with other components and the formation of continuous ion transport channels. Mixing and dispersing modified inorganic materials with polymerizable functional groups grafted onto their surfaces with the natural polysaccharide dispersion allows inorganic nanoparticles to be uniformly distributed at the nanoscale within the polysaccharide network. This step pre-constructs an "organic-inorganic" composite framework, preparing for the formation of a uniform three-dimensional interpenetrating network structure during subsequent in-situ polymerization, and contributing to the simultaneous improvement of the electrolyte's mechanical strength and thermal stability. By in-situ ring-opening polymerization of fluorinated monomers, initiators, and lithium salts in a composite dispersion, the polymerization reaction occurs directly within a pre-constructed polysaccharide-inorganic network, ensuring uniform mixing and bonding of the components at the molecular level. The ring-opening polymerization of the fluorinated monomers forms a polymer backbone, which interacts with natural polysaccharides through hydrogen bonds and chemically bonds with modified inorganic particles, jointly constructing a robust organic-inorganic three-dimensional network. This structure simultaneously serves as a mechanical framework and ion conduction channel. Heating the polymerization product further promotes cross-linking reactions between polymer chains, resulting in a denser and more stable gel network structure, enhancing the mechanical integrity of the electrolyte. Subsequent vacuum drying effectively removes residual solvents and trace amounts of moisture from the system, eliminating the risk of side reactions, improving the chemical stability of the electrolyte, and also helping to reduce the interfacial impedance between the electrode and electrolyte. In summary, the embodiments of this application, through rigorous chemical design and process control, synergistically achieve good compatibility and interfacial stability between components, ultimately aiming to obtain a composite gel polymer electrolyte that combines excellent mechanical strength, a wide electrochemical window, and high ionic conductivity potential. Attached Figure Description

[0044] Figure 1This is a schematic flowchart of the preparation method of the high-pressure composite gel polymer electrolyte according to an embodiment of this application;

[0045] Figure 2 The experimental parameters for Embodiments 1-8 and Comparative Examples 1 and 2 of this application are illustrated in the diagram.

[0046] Figure 3 Impedance diagrams for Embodiments 1-8 and Comparative Examples 1 and 2 of this application. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the high-pressure composite gel polymer electrolyte and its preparation method will be described clearly and completely below with reference to 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.

[0048] 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.

[0049] 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.

[0050] This application discloses a high-voltage composite gel polymer electrolyte and its preparation method. The high-voltage composite gel polymer electrolyte is prepared based on the preparation method of the high-voltage composite gel polymer electrolyte. The purpose of this method is to prepare a high-voltage composite gel polymer electrolyte suitable for supercapacitors using natural polysaccharides, modified 1,3-dioxolane (DOL) monomers and modified inorganic functional materials as core raw materials. This provides a high-voltage composite gel polymer electrolyte with high high voltage resistance, high ionic conductivity, excellent mechanical properties and environmental protection characteristics. It not only solves the problems of narrow electrochemical window and poor mechanical properties under high voltage, but also improves ionic conductivity and thermal stability through the synergistic effect of inorganic materials.

[0051] See attached document Figure 1 As shown, the preparation method of the high-pressure composite gel polymer electrolyte includes the following steps 110-160.

[0052] Step 110: In an acidic aqueous solution, epoxybromopropane is condensed with paraformaldehyde to generate an intermediate, and under alkaline conditions, the intermediate is nucleophilically substituted with trifluoroethanol in a first organic solvent to synthesize a fluorine-modified 1,3-dioxolane monomer.

[0053] Step 110 can be understood as the process of synthesizing a fluorine-modified 1,3-dioxolane monomer. For ease of understanding, step 110 can be understood, for example, as the process of synthesizing the intermediate 4-bromomethyl-1,3-dioxolane and the process of synthesizing the fluorine-modified 1,3-dioxolane monomer, which can be, for example, 4-(2,2,2-trifluoroethoxymethyl)-1,3-dioxolane (TFE-DOL).

[0054] In some embodiments, the process of condensing epibromopropane with paraformaldehyde in an acidic aqueous solution to generate an intermediate, namely the intermediate 4-bromomethyl-1,3-dioxolane, includes: mixing epibromopropane, deionized water, and phosphoric acid in a reaction vessel to obtain a pre-reaction system; heating the pre-reaction system to 75-85°C and performing a first stirring reaction to obtain the target reaction system; adding paraformaldehyde to the target reaction system and performing a second stirring reaction at 75-85°C for 4-5 hours; and performing the second stirring reaction... The target reaction system was cooled to room temperature, and the pH of the cooled target reaction system was adjusted to 7.0 ± 0.2 using an aqueous sodium carbonate solution to obtain a neutral reaction solution. The neutral reaction solution was extracted with dichloromethane to combine the organic phases, and a drying agent, anhydrous calcium chloride, was added to the combined organic phases to dry them. The anhydrous calcium chloride in the dried organic phase was removed by filtration, and the resulting filtrate was subjected to vacuum distillation to obtain the intermediate, which is 4-bromomethyl-1,3-dioxolane.

[0055] For example, in one specific embodiment, the synthesis process of the intermediate 4-bromomethyl-1,3-dioxolane includes: adding epibromopropane, deionized water, and phosphoric acid to a three-necked flask, setting up a reflux apparatus, heating the reaction system to 75-85°C, stirring the reaction for a period of time to obtain the target reaction system; adding paraformaldehyde to the target reaction system, continuing to stir at 75-85°C until the paraformaldehyde is completely dissolved, and then reacting at a constant temperature for 4-5 hours; after the reaction is completed, cooling to room temperature, adjusting the pH of the system to 7.0±0.2 with sodium carbonate aqueous solution, and then repeatedly extracting with dichloromethane 3-4 times, then combining the organic phases, adding anhydrous calcium chloride for drying for 4 hours, filtering to remove the desiccant, and then distilling the filtrate under reduced pressure to collect the fraction to obtain the colorless and transparent liquid intermediate 4-bromomethyl-1,3-dioxolane.

[0056] In some embodiments, the process of synthesizing a fluorinated 1,3-dioxolane monomer by reacting the intermediate with trifluoroethanol in a first organic solvent under alkaline conditions includes: dissolving trifluoroethanol and triethylamine in a first anhydrous dioxane as the first organic solvent to form a first mixture at a temperature below a preset temperature (e.g., -5°C); dissolving the intermediate in a second anhydrous dioxane and slowly adding the intermediate dissolved in the second anhydrous dioxane to the first mixture with stirring, and reacting at a constant temperature of -5°C for 3-4 hours; filtering the first reaction solution obtained from the constant temperature reaction to remove the generated triethylammonium bromide precipitate, and concentrating the filtrate to remove most of the solvent, followed by vacuum distillation to collect the crude product; refluxing the crude product with calcium hydride for dehydration treatment, followed by vacuum distillation again to obtain the fluorinated 1,3-dioxolane monomer.

[0057] For example, in one specific embodiment, the synthesis process of the fluorine-modified 1,3-dioxolane monomer includes: adding trifluoroethanol, triethylamine, and anhydrous dioxane sequentially to a three-necked flask, cooling the flask to -5°C in an ice-salt bath while maintaining stirring; dissolving the synthesized 4-bromomethyl-1,3-dioxolane in anhydrous dioxane and slowly adding it dropwise to the reaction system through a constant-pressure dropping funnel, maintaining a constant temperature of -5°C and stirring for 3-4 hours; after the reaction is completed, filtering to remove the generated triethylammonium bromide precipitate, concentrating the filtrate on a rotary evaporator to remove the solvent, and then performing vacuum distillation to collect a colorless liquid (i.e., crude product). After refluxing the colorless liquid with calcium hydride to remove water for 2 hours, it is distilled again under vacuum, and then subjected to freeze degassing treatment before being transferred to an argon-filled glove box for sealing and storage.

[0058] Step 120: The inorganic nanoparticles are subjected to acid pretreatment, and then the acid-pretreated inorganic nanoparticles are subjected to reflux reaction with a silane coupling agent in a second organic solvent to prepare modified inorganic functional materials with polymerizable functional groups grafted on their surface.

[0059] Step 120 can be understood as a step in the preparation of modified inorganic functional materials. For ease of understanding, step 120 can be understood, for example, as including the pretreatment process of barium titanate (BaTiO3)-silica (SiO2) composite nanoparticles and the silane coupling agent modification process.

[0060] In some embodiments, the step of pretreating inorganic nanoparticles with acid, and then refluxing the pretreated inorganic nanoparticles with a silane coupling agent in a second organic solvent to prepare modified inorganic functional materials with polymerizable functional groups grafted onto their surfaces, includes: mixing barium titanate nanoparticles and silica nanoparticles at a mass ratio, and then adding anhydrous ethanol for ultrasonic dispersion to obtain a dispersion; adding dilute hydrochloric acid to the dispersion and stirring until the pH of the dispersion is adjusted to 3.0, and then centrifuging the resulting second mixture to collect the solid precipitate; washing the solid precipitate with anhydrous ethanol, and then further processing the washed solid precipitate... The pretreated composite nanoparticles are dried to obtain pretreated barium titanate-silica composite nanoparticles. The pretreated composite nanoparticles are dispersed in anhydrous toluene as a second organic solvent, ultrasonically dispersed, heated to 80°C, and a silane coupling agent is added under nitrogen protection for stirring and reflux reaction, which lasts for 4-5 hours. The second reaction solution obtained from the reflux reaction is cooled to room temperature and centrifuged. The solid precipitate of the second reaction solution after centrifugation is collected, washed sequentially with anhydrous toluene and acetone, and then dried to obtain the modified inorganic functional material. This is a silane coupling agent modification process.

[0061] For example, the silane coupling agent is γ-methacryloyloxy, propyltrimethoxysilane, or aminopropyltriethoxysilane.

[0062] For example, in one specific embodiment, the pretreatment of the barium titanate-silica composite nanoparticles includes: taking BaTiO3 nanoparticles and SiO2 nanoparticles, mixing them in a certain mass ratio and adding them to a beaker, adding anhydrous ethanol, ultrasonically dispersing for 20 minutes, adding 5% dilute hydrochloric acid to adjust the pH to 3.0, stirring for 30 minutes to remove hydroxyl impurities on the particle surface; then centrifuging, washing the precipitate three times with anhydrous ethanol, and drying it in a vacuum drying oven at 60°C for 6 hours to obtain the pretreated composite nanoparticles.

[0063] For example, the nanoparticles are one of BaTiO3-SiO2 composite materials, ZnO nanoparticles, and Al2O3 nanoparticles.

[0064] For example, in one specific embodiment, the silane coupling agent modification process includes: adding pretreated BaTiO3-SiO2 composite nanoparticles and anhydrous toluene to a three-necked flask, ultrasonically dispersing for 15 minutes, heating to 80°C, adding γ-methacryloyloxy and propyltrimethoxysilane, and refluxing and stirring under nitrogen protection for 4-5 hours; after the reaction is completed, cooling to room temperature, centrifuging, washing the precipitate twice with anhydrous toluene, washing it once with acetone, and drying it in an 80°C vacuum drying oven for 8 hours to obtain a modified inorganic functional material. The double bonds grafted on the surface of this material can undergo a synergistic reaction with the polymerization system, improving compatibility.

[0065] Step 130: Under an inert atmosphere, the natural polysaccharide is dispersed in a third organic solvent to form a uniform natural polysaccharide dispersion, wherein the third organic solvent is an anhydrous organic solvent.

[0066] Step 130 can be understood as the preparation process of natural polysaccharide dispersion.

[0067] For example, in one specific embodiment, the preparation process of the natural polysaccharide dispersion includes: adding natural polysaccharide and dispersant solvent to a clean Schlenk bottle under an argon atmosphere, wherein the mass fraction of natural polysaccharide in the solvent is 2%-3%; placing the system in an ultrasonic cleaner and ultrasonically dispersing it at 30-40°C for 40-60 minutes to obtain a uniform and stable natural polysaccharide dispersion for later use.

[0068] For example, the natural polysaccharide is one of carboxymethyl cellulose, carboxymethyl chitosan, carboxymethyl starch, xanthan gum, hydroxypropyl guar gum, or dextran; the third organic solvent is anhydrous acetonitrile or anhydrous N,N-dimethylformamide; and the mass fraction of the natural polysaccharide in the natural polysaccharide dispersion is 2%-3%.

[0069] Step 140: Add the modified inorganic functional material to the natural polysaccharide dispersion and perform dispersion treatment to obtain a polysaccharide inorganic composite dispersion.

[0070] Step 140 can be understood as the dispersion and composite process of modified inorganic functional materials.

[0071] In some embodiments, the step of adding the modified inorganic functional material to the natural polysaccharide dispersion and performing dispersion treatment includes: adding the modified inorganic functional material to the natural polysaccharide dispersion and performing the dispersion treatment at 35°C accompanied by ultrasound and stirring; wherein the amount of the modified inorganic functional material added is 5%-8% of the mass of the natural polysaccharide dispersion.

[0072] For example, in one specific embodiment, the dispersion and composite process of the modified inorganic functional material includes: transferring the above-mentioned natural polysaccharide dispersion into an ultrasonic reactor, adding the prepared modified BaTiO3-SiO2 composite nanoparticles at 5%-8% of the mass of the natural polysaccharide, purging the air with argon gas, ultrasonically dispersing at 35°C for 30 minutes, while simultaneously stirring with magnetic force to ensure uniform dispersion of inorganic particles and avoid agglomeration, thereby obtaining a polysaccharide-inorganic composite dispersion.

[0073] Step 150: The fluorine-modified 1,3-dioxolane monomer, initiator, and electrolyte lithium salt are added to the polysaccharide inorganic composite dispersion, and an in-situ ring-opening polymerization reaction is carried out under inert gas protection to obtain the polymerization reaction mixture.

[0074] Step 150 can be understood as an in-situ polymerization reaction process.

[0075] For example, the initiator is azobisisobutyronitrile, and the electrolyte lithium salt is one of lithium hexafluorophosphate (LiPF6), lithium bisfluorosulfonylimide (LiFSi), or lithium bistrifluoromethylsulfonylimide (LiTFSi).

[0076] In some embodiments, the method further includes: determining the amount of lithium salt to be added based on the concentration of lithium salt in the high-pressure composite gel polymer electrolyte being 1-1.5M; and conducting an in-situ ring-opening polymerization reaction under inert gas protection and stirring at 40°C for 6 hours to obtain a polymerization reaction mixture.

[0077] For example, in one specific embodiment, the in-situ polymerization process includes: transferring the polysaccharide-inorganic composite dispersion to a three-necked flask equipped with a magnetic stirrer, adding the prepared TFE-DOL monomer, stirring and mixing for 30 minutes, adding the initiator azobisisobutyronitrile (AIBN), and simultaneously adding the electrolyte lithium salt. Under argon protection, the reaction system is heated to 40°C and stirred for 6 hours. During this period, the TFE-DOL monomer undergoes ring-opening polymerization, while the modified inorganic material participates in the polymerization reaction through surface double bonds, forming a three-dimensional network composite system with the natural polysaccharide.

[0078] Step 160: The polymerization reaction mixture is subjected to heating and vacuum drying to obtain the high-pressure composite gel polymer electrolyte. The heating is used to promote cross-linking and gel formation, and the vacuum drying is used to remove residual solvent and moisture.

[0079] Step 150 can be understood as the gelation and post-processing process.

[0080] In some embodiments, the heating and vacuum drying of the polymerization reaction mixture includes: heating the polymerization reaction mixture to 60°C and continuing to stir for 2 hours; and vacuum drying the polymerization reaction mixture after stirring for 2 hours at 45°C for 8 hours.

[0081] For example, in one specific embodiment, the gelation and post-treatment process includes: after the polymerization reaction is completed, the system temperature is raised to 60°C and kept at this temperature and stirred for 2 hours to promote further cross-linking of the polymer to form a dense gel structure; then it is naturally cooled to room temperature and transferred to a glove box filled with argon (the water and oxygen content are both less than 0.1 ppm), and dried in a vacuum drying oven at 45°C for 8 hours to completely remove residual solvent and trace amounts of moisture, finally obtaining a high-pressure composite gel polymer electrolyte.

[0082] This application's embodiments demonstrate how the condensation of epibromopropane and paraformaldehyde under acidic conditions constructs a 1,3-dioxolane intermediate framework with an active reactive bromomethyl group. Subsequently, through nucleophilic substitution with trifluoroethanol under alkaline conditions, a highly electronegative fluorinated group (trifluoroethoxy) is precisely introduced into this framework, laying the foundation for the final polymer electrolyte to possess hydrophobic properties and a wider electrochemical stability window. Acid pretreatment of the inorganic nanoparticles effectively cleans their surface and activates hydroxyl groups, preparing them for subsequent chemical grafting. Subsequent surface modification using a silane coupling agent under reflux conditions allows for the covalent grafting of polymerization-particulate functional groups such as double bonds onto the surface. This significantly improves the compatibility and interfacial bonding between the inorganic particles and the organic polymer matrix, preventing phase separation. Operating under an inert atmosphere effectively prevents the degradation or deterioration of air- or moisture-sensitive natural polysaccharides and their solvent systems, ensuring the activity of the raw materials. Pre-dispersing the natural polysaccharides in an anhydrous organic solvent to form a homogeneous solution ensures the full extension of the polysaccharide molecular chains, creating conditions for their subsequent uniform compounding with other components and the formation of continuous ion transport channels. Mixing and dispersing modified inorganic materials with polymerizable functional groups grafted onto their surfaces with the natural polysaccharide dispersion allows inorganic nanoparticles to be uniformly distributed at the nanoscale within the polysaccharide network. This step pre-constructs an "organic-inorganic" composite framework, preparing for the formation of a uniform three-dimensional interpenetrating network structure during subsequent in-situ polymerization, and contributing to the simultaneous improvement of the electrolyte's mechanical strength and thermal stability. By in-situ ring-opening polymerization of fluorinated monomers, initiators, and lithium salts in a composite dispersion, the polymerization reaction occurs directly within a pre-constructed polysaccharide-inorganic network, ensuring uniform mixing and bonding of the components at the molecular level. The ring-opening polymerization of the fluorinated monomers forms a polymer backbone, which interacts with natural polysaccharides through hydrogen bonds and chemically bonds with modified inorganic particles, jointly constructing a robust organic-inorganic three-dimensional network. This structure simultaneously serves as a mechanical framework and ion conduction channel. Heating the polymerization product further promotes cross-linking reactions between polymer chains, resulting in a denser and more stable gel network structure, enhancing the mechanical integrity of the electrolyte. Subsequent vacuum drying effectively removes residual solvents and trace amounts of moisture from the system, eliminating the risk of side reactions, improving the chemical stability of the electrolyte, and also helping to reduce the interfacial impedance between the electrode and electrolyte. In summary, the embodiments of this application, through rigorous chemical design and process control, synergistically achieve good compatibility and interfacial stability between components, ultimately aiming to obtain a composite gel polymer electrolyte that combines excellent mechanical strength, a wide electrochemical window, and high ionic conductivity potential.

[0083] To enable those skilled in the art to better understand the solutions of the embodiments of this application, the technical solutions of the embodiments of the present invention will be clearly and completely described below based on a specific embodiment. Obviously, the described embodiment is only a part of the embodiments of the present invention, and not all of the embodiments. Refer to the appendix. Figure 2 The comparison results shown include the following specific embodiments: Embodiments 1-8, Comparative Examples 1 and 2.

[0084] Example 1

[0085] Step 1: Synthesis of Fluorine-Modified DOL Monomer (TFE-DOL)

[0086] 1.1 Synthesis of the intermediate 4-bromomethyl-1,3-dioxolane

[0087] Add 100g of epibromopropane, 200mL of deionized water, and 5g of phosphoric acid to a 500mL three-necked flask, and set up a reflux apparatus with a condenser. Turn on the heating mantle to raise the reaction system to 80℃ and stir at 300 rpm for 2.5 hours. Then add 30g of paraformaldehyde to the system, continue stirring at 80℃ for 30 minutes until the paraformaldehyde is completely dissolved, and then react at a constant temperature for 4.5 hours. After the reaction is complete, turn off the heating mantle and allow it to cool naturally to room temperature. Adjust the pH of the system to 7.0 by adding dropwise 10% sodium carbonate aqueous solution.

[0088] Add 100 mL of dichloromethane to the above neutral system, shake and extract for 5 minutes, allow to stand and separate into layers, and collect the lower organic phase; repeat the extraction 3 times and combine the organic phases. Add 20 g of anhydrous calcium chloride to the combined organic phase, seal and dry at 25 °C for 4 hours. Remove the desiccant by filtration using a Buchner funnel, transfer the filtrate to a 500 mL vacuum distillation flask, and distill under vacuum at 0.085 MPa and 68 °C. Collect the distillate to obtain 86.2 g of a colorless, transparent liquid intermediate, 4-bromomethyl-1,3-dioxolane.

[0089] 1.2 Synthesis of the fluorinated monomer TFE-DOL

[0090] Add 66 g of trifluoroethanol, 79.9 g of triethylamine, and 330 mL of anhydrous dioxane to a 500 mL three-necked flask. Cool the flask to -5 °C in an ice-salt bath and turn on magnetic stirring. Dissolve 80 g of 4-bromomethyl-1,3-dioxolane synthesized in step 1.1 in 240 mL of anhydrous dioxane, transfer to a constant-pressure dropping funnel, and slowly add the solution dropwise to the reaction system, controlling the dropping rate to complete the addition within 15 minutes. After the addition is complete, maintain a constant temperature of -5 °C and stir the reaction for 3.5 hours.

[0091] After the reaction was complete, the white precipitate (triethylammonium bromide) was removed by filtration. The filtrate was transferred to a rotary evaporator and concentrated to approximately 50 mL at 40 °C and 0.08 MPa. Then, vacuum distillation was performed, collecting 78.5 g of a colorless liquid. This liquid was mixed with 10 g of calcium hydride, refluxed for 2 hours to remove water, and then distilled again under vacuum, collecting 72 g of the distillate. After cryogenic degassing, the distillate was transferred to an argon glove box (water and oxygen <0.1 ppm) and sealed for later use.

[0092] Step 2: Preparation of modified inorganic functional materials

[0093] 2.1 Pretreatment of BaTiO3-SiO2 composite nanoparticles

[0094] 15g of BaTiO3 nanoparticles (60nm diameter) and 5g of SiO2 nanoparticles (30nm diameter) were mixed and then added to 200mL of anhydrous ethanol. The mixture was ultrasonically dispersed for 20 minutes. The pH was adjusted to 3.0 with 5% hydrochloric acid (w / w), and the mixture was stirred for 30 minutes. The mixture was then centrifuged at 5000 rpm for 10 minutes, the precipitate was collected, washed three times with anhydrous ethanol, and dried in a vacuum oven at 60℃ for 6 hours to obtain 18.2g of pretreated composite particles.

[0095] 2.2 Modification with silane coupling agents

[0096] 18 g of pretreated particles and 144 mL of anhydrous toluene were added to a 250 mL three-necked flask. After ultrasonic dispersion for 15 minutes, the temperature was raised to 80 °C. 1.44 g of γ-methacryloyloxypropyltrimethoxysilane was added, and the mixture was refluxed and stirred for 4.5 hours under nitrogen protection. After the reaction was completed, the mixture was cooled to room temperature and centrifuged at 6000 r / min for 15 minutes. The precipitate was washed twice with anhydrous toluene (80 mL each time) and once with acetone. It was then dried under vacuum at 80 °C for 8 hours to obtain 18.5 g of modified BaTiO3-SiO2 particles.

[0097] Step 3: Preparation of composite gel polymer electrolyte

[0098] 3.1 Preparation of natural polysaccharide dispersion

[0099] Under an argon atmosphere, 4g of hydroxyethyl cellulose and 196g of dispersant (DMF: ethylene glycol = 2:1) were added to a 250mL Schlenk flask, and the flask was placed in an ultrasonic cleaner and ultrasonically dispersed at 35°C for 50 minutes to obtain a uniform dispersion.

[0100] 3.2 Preparation of polysaccharide-inorganic composite dispersion

[0101] The above dispersion was transferred to an ultrasonic reactor, and 0.32 g of modified BaTiO3-SiO2 particles were added. Argon gas was passed through for 5 minutes to purge the air, and the mixture was ultrasonically dispersed at 35°C for 30 minutes with stirring at 300 r / min to obtain a composite dispersion.

[0102] 3.3 In-situ polymerization reaction

[0103] The composite dispersion was transferred to a 500 mL three-necked flask, and 40 g of TFE-DOL monomer was added. After stirring for 30 minutes, 0.32 g of AIBN and 29.1 g of LiTFSI (concentration 1.2 mol / L) were added. Argon gas was purged for 10 minutes for protection, and the temperature was raised to 40 °C and stirred for 6 hours.

[0104] 3.4 Gelation and Post-treatment

[0105] The mixture was heated to 60°C and stirred for 2 hours. After naturally cooling to room temperature, it was transferred to an argon glove box and vacuum dried at 45°C for 8 hours to obtain a high-pressure composite gel polymer electrolyte.

[0106] 3.5 Assembling Supercapacitors

[0107] The supercapacitor was prepared in the following order: positive electrode shell, positive electrode sheet, gel polymer electrolyte, negative electrode sheet, stainless steel sheet, spring sheet, and negative electrode shell. The positive electrode used NCM811 mixed with activated carbon, and the negative electrode used natural graphite.

[0108] Example 2

[0109] The only difference between this embodiment and Example 1 is that the amount of silane coupling agent KH-570 used is 5% (0.9g) of the mass of the modified inorganic material (BaTiO3-SiO2 composite particles). Everything else is the same as in Example 1.

[0110] Example 3

[0111] The only difference between this example and Example 1 is that the amount of silane coupling agent KH-570 used is 10% (i.e., 1.8g) of the mass of the modified inorganic material (BaTiO3-SiO2 composite particles), and everything else is the same as in Example 1.

[0112] Example 4

[0113] The only difference between this embodiment and Example 1 is that the modified inorganic material is replaced with single Al2O3 nanoparticles with a particle size of 50nm (the amount is still 8% of the mass of hydroxyethyl cellulose, i.e., 0.32g), and everything else is the same as in Example 1.

[0114] Example 5

[0115] The only difference between this embodiment and Example 1 is that the modified inorganic material is replaced with single ZnO nanoparticles with a particle size of 40 nm (the amount is still 8% of the mass of hydroxyethyl cellulose, i.e., 0.32 g), and everything else is the same as in Example 1.

[0116] Example 6

[0117] The only difference between this embodiment and Example 1 is that the silane coupling agent is replaced with aminopropyltriethoxysilane, with the dosage remaining at 8% of the mass of the modified inorganic material (i.e., 1.44 g), and the concentration of the electrolyte lithium salt LiTFSI is adjusted to 1.0 mol / L (the dosage is changed to 24.25 g). Everything else is the same as in Example 1.

[0118] Example 7

[0119] The only difference between this embodiment and Example 1 is that the natural polysaccharide is replaced with carboxymethyl cellulose, and the concentration of the electrolyte lithium salt LiTFSI is adjusted to 1.5 mol / L (the amount is changed to 36.38 g). Everything else is the same as in Example 1.

[0120] Example 8

[0121] The only difference between this embodiment and Example 1 is that the amount of modified inorganic material (BaTiO3-SiO2 composite particles) is adjusted to 5% (i.e. 0.2g) of the mass of natural polysaccharide (hydroxyethyl cellulose), and everything else is the same as in Example 1.

[0122] Comparative Example 1

[0123] The preparation method is the same as in Example 1, except that "Step 2: Preparation of modified inorganic functional materials" and "Step 3.2: Preparation of polysaccharide-inorganic composite dispersion" are omitted. The natural polysaccharide dispersion is directly used for in-situ polymerization. The remaining steps and parameters are completely consistent with those in Example 1.

[0124] Comparative Example 2

[0125] The preparation method is the same as in Example 1, except that "step two" is replaced with "take 0.32g of the pretreated BaTiO3-SiO2 particles from Example 1, do not modify with silane coupling agent, and directly use them in step 3.2". The remaining steps and parameters are completely consistent with those in Example 1.

[0126] The testing methods included: electrochemical window configuration and 25℃ ionic conductivity configuration. The electrochemical window configuration employed linear sweep voltammetry (LSV); the 25℃ ionic conductivity configuration employed alternating current impedance spectroscopy with a frequency range of 10... - ²-10 6The conductivity was calculated by fitting the impedance spectrum at Hz using ZsimpWin software, where σ = L / (R×S), L is the sample thickness, R is the bulk resistance, and S is the electrode area. Cyclic testing was performed using a Blue Electric testing instrument, with constant current and constant voltage charging and constant current discharging.

[0127] The experimental parameters of Examples 1-8 and Comparative Examples 1 and 2 are shown in Table 1 and Appendix 2 below. Figure 2 .

[0128] Table 1: Experimental parameters of Examples 1-8 and Comparative Examples 1 and 2

[0129]

[0130] As can be seen from Table 1, Examples 1-8 exhibit significant advantages over Comparative Examples 1 and 2 in terms of electrochemical window, mechanical strength, and cycle performance. For example, within the electrochemical window, the parameter values ​​of Examples 1-8 are all ≥5.1V, with the highest value reaching 5.6V, representing a 30.2% improvement over Comparative Example 1 (4.3V) with inorganic materials and a 16.7% improvement over Comparative Example 2 (4.8V) with unmodified inorganic materials. This demonstrates that the synergistic effect of the modified inorganic materials and the fluorinated monomers can effectively inhibit the oxidative decomposition of the electrolyte under high voltage. (See Appendix...) Figure 2 As can be seen from the data, the ionic conductivity of Examples 1-8 is ≥1.4×10⁻⁶. - ³S / cm, of which Example 1 reaches 1.9×10 - ³S / cm, compared to Comparative Example 1 (0.9×10⁻⁶) - The conductivity (³S / cm) is significantly improved because the high dielectric constant of BaTiO3 promotes lithium salt dissociation and SiO2 guides ion transport channels, while in Comparative Example 2, the unmodified particles agglomerate and block the transport path, resulting in limited improvement in conductivity. (See attached...) Figure 3 As can be seen from Example 1 and Example 7, the impedance of Comparative Example 1 and Comparative Example 2 is significantly reduced, corresponding to the ionic conductivity.

[0131] In summary, compared with the prior art, the embodiments of this application have significant advantages: On the one hand, the trifluoroethoxy groups in the TFE-DOL monomer can be oriented to form a stable SEI film on the electrode surface, and combined with the electronically insulating modified BaTiO3-SiO2 particles to block electron conduction, the high voltage stability is greatly improved; on the other hand, the natural polysaccharide forms hydrogen bonds with the polymer chain, and the modified inorganic material is chemically bonded to the polymerization system through surface double bonds to construct an "organic-inorganic" three-dimensional network, which solves the problem of poor mechanical properties of traditional gels. The high dielectric constant of BaTiO3 can promote the dissociation of lithium salts, and SiO2 guides ion transport. With the regulation of the polysaccharide solvation environment, the ionic conductivity is significantly improved. At the same time, the high temperature resistance of SiO2 and the catalytic carbonization effect of BaTiO3 also enhance the thermal stability and safety. The complementary mechanisms of each component form a performance closed loop, effectively solving the core pain points of traditional gel electrolytes.

[0132] This application also discloses a high-pressure composite gel polymer electrolyte, which is prepared by the preparation method of the high-pressure composite gel polymer electrolyte described above.

[0133] This application also discloses a supercapacitor comprising the high-voltage composite gel polymer electrolyte described above.

[0134] 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 high-pressure composite gel polymer electrolyte, characterized in that, include: In an acidic aqueous solution, epoxybromopropane is condensed with paraformaldehyde to generate an intermediate, and under alkaline conditions, the intermediate is nucleophilically substituted with trifluoroethanol in a first organic solvent to synthesize a fluorine-modified 1,3-dioxolane monomer. Inorganic nanoparticles are pretreated with acid, and then the pretreated inorganic nanoparticles are refluxed with a silane coupling agent in a second organic solvent to prepare modified inorganic functional materials with polymerizable functional groups grafted on their surface. Under an inert atmosphere, natural polysaccharides are dispersed in a third organic solvent to form a uniform natural polysaccharide dispersion, wherein the third organic solvent is an anhydrous organic solvent. The modified inorganic functional material is added to the natural polysaccharide dispersion and dispersed to obtain a polysaccharide inorganic composite dispersion. The fluorine-modified 1,3-dioxolane monomer, initiator, and electrolyte lithium salt are added to the polysaccharide inorganic composite dispersion, and an in-situ ring-opening polymerization reaction is carried out under inert gas protection to obtain the polymerization reaction mixture. The polymerization reaction mixture is subjected to heating and vacuum drying to obtain the high-pressure composite gel polymer electrolyte. The heating treatment is used to promote cross-linking and gel formation, and the vacuum drying is used to remove residual solvent and moisture.

2. The method according to claim 1, characterized in that, The process of condensing epoxypropane with paraformaldehyde in an acidic aqueous solution to generate an intermediate includes: In a reaction vessel, the epichlorohydrin, deionized water, and phosphoric acid are mixed to obtain a pre-reaction system; The pre-reaction system is heated to 75-85℃ and subjected to a first stirring reaction to obtain the target reaction system; Paraformaldehyde was added to the target reaction system, and a second stirring reaction was carried out at 75-85°C for 4-5 hours. The target reaction system undergoing the second stirring reaction was cooled to room temperature, and the pH of the cooled target reaction system was adjusted to 7.0±0.2 using an aqueous sodium carbonate solution to obtain a neutral reaction solution; The neutral reaction solution was extracted with dichloromethane to combine the organic phases, and a drying agent, anhydrous calcium chloride, was added to the combined organic phases for drying. The anhydrous calcium chloride in the dried organic phase was filtered and removed, and the resulting filtrate was subjected to vacuum distillation to obtain the intermediate, which is 4-bromomethyl-1,3-dioxolane.

3. The method according to claim 2, characterized in that, The process of reacting the intermediate with trifluoroethanol in a first organic solvent under alkaline conditions to perform a nucleophilic substitution reaction for the synthesis of a fluorine-modified 1,3-dioxolane monomer includes: Under conditions below a preset temperature, trifluoroethanol and triethylamine are dissolved in anhydrous dioxane, which serves as the first organic solvent, to form a first mixture. The intermediate is dissolved in a second anhydrous dioxane, and the intermediate dissolved in the second anhydrous dioxane is slowly added dropwise to the first mixture under stirring, and the mixture is reacted at a constant temperature of -5°C for 3-4 hours. The first reaction solution obtained from the isothermal reaction was filtered to remove the generated triethylammonium bromide precipitate, and the filtrate was concentrated to remove most of the solvent. Then, it was subjected to vacuum distillation to collect the crude product. The crude product was refluxed with calcium hydride to remove water, and then subjected to vacuum distillation again to obtain the fluorine-modified 1,3-dioxolane monomer.

4. The method according to claim 1, characterized in that, The process involves pretreating inorganic nanoparticles with acid, followed by reflux reaction of the pretreated nanoparticles with a silane coupling agent in a second organic solvent. This process is used to prepare modified inorganic functional materials with polymerizable functional groups grafted onto their surfaces. The method includes: Barium titanate nanoparticles and silica nanoparticles were mixed at a certain mass ratio and then ultrasonically dispersed in anhydrous ethanol to obtain a dispersion. Dilute hydrochloric acid was added to the dispersion and stirred until the pH of the dispersion was adjusted to 3.

0. The resulting second mixture was then centrifuged to collect the solid precipitate. The solid precipitate was washed with anhydrous ethanol and then dried to obtain pretreated composite nanoparticles. The pretreated composite nanoparticles were dispersed in anhydrous toluene as the second organic solvent, ultrasonically dispersed, heated to 80°C, and a silane coupling agent was added under nitrogen protection for stirring and reflux reaction, the duration of which was 4-5 hours. The second reaction solution obtained from the reflux reaction was cooled to room temperature and then centrifuged. The solid precipitate of the second reaction solution after centrifugation was collected and washed with anhydrous toluene and acetone in sequence, and then dried to obtain the modified inorganic functional material.

5. The method according to claim 1, characterized in that, The silane coupling agent is γ-methacryloyloxy, propyltrimethoxysilane, or aminopropyltriethoxysilane.

6. The method according to claim 1, characterized in that, The natural polysaccharide is one of carboxymethyl cellulose, carboxymethyl chitosan, carboxymethyl starch, xanthan gum, hydroxypropyl guar gum, or dextran; the third organic solvent is anhydrous acetonitrile or anhydrous N,N-dimethylformamide; the mass fraction of the natural polysaccharide in the natural polysaccharide dispersion is 2%-3%.

7. The method according to claim 1, characterized in that, The step of adding the modified inorganic functional material to the natural polysaccharide dispersion and performing dispersion treatment includes: The modified inorganic functional material was added to the natural polysaccharide dispersion, and the dispersion treatment was carried out at 35°C with ultrasound and stirring. The amount of the modified inorganic functional material added is 5%-8% of the mass of the natural polysaccharide dispersion.

8. The method according to claim 1, wherein the initiator is azobisisobutyronitrile, and the electrolyte lithium salt is one of lithium hexafluorophosphate, lithium bisfluorosulfonylimide, or lithium bistrifluoromethylsulfonylimide, characterized in that, The method further includes: The amount of lithium salt added to the electrolyte is determined based on the concentration of lithium salt in the high-pressure composite gel polymer electrolyte being 1-1.5M. In-situ ring-opening polymerization was carried out under inert gas protection and stirring at 40°C for 6 hours to obtain the polymerization reaction mixture.

9. The method according to claim 1, characterized in that, The step of heating and vacuum drying the polymerization reaction mixture includes: The polymerization reaction mixture was heated to 60°C and stirred for 2 hours. The polymerization reaction mixture, after being stirred for 2 hours, was vacuum dried for 8 hours at 45°C.

10. A high-pressure composite gel polymer electrolyte, characterized in that, It is prepared by any one of the high-pressure composite gel polymer electrolytes according to claims 1 to 9.

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