Phosphorus-containing ureido pyrimidone monomer and preparation method thereof, gel electrolyte and lithium battery

Abstract

The invention relates to the technical field of electrochemistry, in particular to a phosphorus-containing ureido pyrimidone monomer and a preparation method thereof, a gel electrolyte and a lithium battery. The phosphorus-containing ureido pyrimidone monomer is prepared by the following steps: reacting a phosphorus-containing hydroxyl compound with a diisocyanate compound to generate a phosphorus-containing isocyanate intermediate, reacting the phosphorus-containing isocyanate intermediate with a 2-amino-4-hydroxypyrimidine derivative to generate a urea intermediate, and reacting the urea intermediate with an acrylic anhydride compound. According to the phosphorus-containing ureido pyrimidone monomer, a dynamic self-repairing unit and a flame-retardant unit are integrated into the monomer from a molecular source, so that the monomer molecule has a flame-retardant function and a self-repairing function. The raw materials of the gel electrolyte comprise the phosphorus-containing ureido pyrimidone monomer, the gel electrolyte is prepared in the lithium battery through constant-temperature gradient boosting curing, the lithium battery is obtained, the gel electrolyte has good flame retardance and self-repairing performance, and the lithium battery has good conductivity, cycle performance and safety.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of electrochemistry, and in particular to a phosphorus-containing urea-based pyrimidinone monomer, a preparation method thereof, a gel electrolyte and a lithium battery. BACKGROUND

[0002] The gel electrolyte has both the high ionic conductivity of the liquid electrolyte and the safety and mechanical stability of the solid-state electrolyte, and is one of the core materials for battery manufacturing. However, there are two major technical bottlenecks in the traditional gel electrolyte: first, the lack of flame retardancy, the traditional gel electrolyte mostly uses flammable polymer matrices such as polyethylene oxide and polyacrylate, and flammable plasticizers such as carbonates, which are prone to combustion and explosion under extreme conditions such as overcharging, short circuit and thermal runaway of the battery, causing safety accidents; second, the lack of self-repairing performance, during the charging and discharging cycle and mechanical deformation of the battery, the gel electrolyte is prone to micro-cracks and damage, leading to electrolyte leakage and electrode interface failure, affecting the cycle life of the battery.

[0003] At present, for the flame-retardant improvement of the gel electrolyte, a method of directly adding phosphorus-containing, nitrogen-containing, silicon-containing and other flame retardants is mostly used, but the physically added flame retardants are prone to agglomeration and migration, resulting in a decrease in the mechanical properties and ionic conductivity of the gel electrolyte. Therefore, there is an urgent need to provide a technical solution that takes into account the repair efficiency and thermal stability, and can realize the synergy of flame retardancy and self-repairing. SUMMARY

[0004] In order to solve the technical problem that the flame-retardant performance and self-repairing performance of the existing gel electrolyte are difficult to be synergized, the present application provides a phosphorus-containing urea-based pyrimidinone monomer, a preparation method thereof, a gel electrolyte and a lithium battery.

[0005] The present application provides a phosphorus-containing urea-based pyrimidinone monomer, the structural general formula of the phosphorus-containing urea-based pyrimidinone monomer is shown as formula [1], Formula [1] In formula [1], R1 and R2 are C1-C4 alkyl, and R1 and R2 can be the same; R3 is an alpha-hydroxyl saturated alkyl group; R4 is an inert group; and Ar is a phenylene group or an alkyl-substituted derivative thereof.

[0006] The present application also provides a preparation method of the phosphorus-containing urea-based pyrimidinone monomer, which comprises the following steps: generating a phosphorus-containing isocyanate intermediate by reacting a phosphorus-containing hydroxyl compound with a diisocyanate compound; generating a urea intermediate by reacting the phosphorus-containing isocyanate intermediate with a 2-amino-4-hydroxypyrimidine derivative; and obtaining the phosphorus-containing urea-based pyrimidinone monomer by reacting the urea intermediate with an acrylic anhydride compound; the phosphorus-containing urea-based pyrimidinone monomer has the general formula shown as formula [1].

[0007] Further, the phosphorus-containing hydroxyl compound includes any one of (1-hydroxyethyl)dimethylphosphonate, diisopropyl (hydroxymethyl)phosphonate or a combination of both; and / or, the diisocyanate compound includes a combination of one or more of toluene 2,6-diisocyanate, toluene-2,4-diisocyanate, 1,3-diisophthalonitrile, p-phenylene diisocyanate, toluene 2,6-diisocyanate.

[0008] Further, the 2-amino-4-hydroxypyrimidine derivative includes a combination of one or more of 2-amino-4-hydroxy-6-methylpyrimidine, 2-amino-4-hydroxy-5-methoxypyrimidine, 2-amino-4-hydroxy-5-bromopyrimidine, 2-amino-4-hydroxy-6-ethylpyrimidine; and / or the acrylic anhydride compound includes a combination of one or more of methyl acrylate, dimethyl acrylate, ethyl acrylate, phenyl acrylate.

[0009] Further, the generating the phosphorus-containing isocyanate intermediate by reacting the phosphorus-containing hydroxyl compound with the diisocyanate compound specifically includes the following steps: dissolving the phosphorus-containing hydroxyl compound in a first solvent at 0-5°C under a protective atmosphere, adding a catalyst, and adding the diisocyanate compound dropwise at a rate of 1-5 drops per second to react; after the dropwise addition is completed, the temperature is raised to 40-60°C, and the stirring reaction is continued for 2-4 h to obtain the phosphorus-containing isocyanate intermediate.

[0010] Further, the molar ratio of the phosphorus-containing hydroxyl compound to the diisocyanate compound is 1:(1-1.2); the first solvent is anhydrous tetrahydrofuran; and the catalyst is dibutyl tin dilaurate.

[0011] Further, the reaction of the phosphorus-containing isocyanate intermediate with the 2-amino-4-hydroxypyrimidine derivative to generate the ureidation intermediate specifically includes the following steps: dissolving the phosphorus-containing isocyanate intermediate in a second solvent, adding the 2-amino-4-hydroxypyrimidine derivative under a protective atmosphere, and raising the temperature to 85-100°C to stir for 1-3 h to obtain the ureidation intermediate; the molar ratio of the phosphorus-containing isocyanate intermediate to the 2-amino-4-hydroxypyrimidine derivative is 1:1-1.1; and the second solvent is anhydrous dimethyl sulfoxide.

[0012] Further, the reaction of the urea intermediate with acrylic anhydride compounds to obtain the phosphorus-containing urea-pyrimidinone monomer specifically includes the following steps: at 0-5°C, the urea intermediate is dissolved in a third solvent under a protective atmosphere, a polymerization inhibitor and an organic base are added to form a reaction system, and acrylic anhydride compounds are added dropwise at a rate of 1-5 drops per second to carry out the reaction. After the addition is completed, the reaction is stirred for 20-40 minutes; the temperature is raised to room temperature and the reaction is continued for 2-4 hours to obtain the phosphorus-containing urea-pyrimidinone monomer; wherein, the molar ratio of the urea intermediate to the acrylic anhydride compounds is 1:(1.2-1.5), and the third solvent is anhydrous dichloromethane.

[0013] This invention provides a gel electrolyte, which is prepared by curing electrolyte raw materials through a constant temperature gradient pressure. The electrolyte raw materials include the phosphauracil pyrimidinone monomer described above. The gel electrolyte has a dual-network structure consisting of a chemically cross-linked network with covalent bonds and a physically cross-linked network with four hydrogen bonds.

[0014] The present invention also provides a lithium battery comprising the gel electrolyte as described above.

[0015] Compared with the prior art, the phosphorus-containing ureapyridinone monomer, its preparation method, gel electrolyte, and lithium battery provided by the present invention have the following beneficial effects: 1. This invention provides a phosphorus-containing ureapyrimidinone monomer. In the general formula of the phosphorus-containing ureapyrimidinone monomer, groups R1 and R2 are C1-C4 alkyl groups, belonging to short-chain aliphatic alkyl groups, which are structurally stable and flexible regulatory groups; R3 is an α-hydroxy saturated alkyl group with polar hydroxyl groups, participating in hydrogen bonding and enhancing self-healing properties; R4 is an inert group with strong stability; Ar is a phenylene or its alkyl-substituted derivative, belonging to rigid connecting units, which can enhance thermal stability and synergistically improve flame retardant properties. The phosphorus-containing ureapyrimidinone monomer contains ureapyrimidinone groups, phosphorus-containing flame-retardant structural units, and acrylate groups, integrating dynamic self-healing units and flame-retardant units into the monomer from the molecular source, so that the monomer molecule has both flame-retardant and self-healing functions.

[0016] 2. This invention provides a method for preparing a phosphorus-containing ureapyrimidine ketone monomer, employing a three-step process. First, a phosphorus-containing hydroxyl compound reacts with a diisocyanate compound to generate a phosphorus-containing isocyanate intermediate, constructing a phosphorus-containing flame-retardant unit with flame-retardant properties. The phosphorus-containing isocyanate intermediate reacts with a 2-amino-4-hydroxypyrimidine derivative to generate a ureation intermediate, introducing a ureapyrimidine ketone group with self-healing capabilities. The ureation intermediate reacts with an acrylic anhydride compound to introduce an acrylate group with a carbon-carbon double bond, yielding the phosphorus-containing ureapyrimidine ketone monomer. This three-step synthetic pathway facilitates confirmation of the structure of the intermediate obtained in each reaction step, ensuring that each reaction proceeds according to the predetermined path, guaranteeing the accuracy of the obtained monomer structure, and improving the purity of the obtained monomer.

[0017] 3. In the technical solution of this invention, phosphorus-containing flame-retardant structural units are constructed using phosphorus-containing hydroxyl compounds. The phosphorus groups in these compounds are responsible for flame retardancy, while the hydroxyl groups are responsible for linkage. The phosphorus groups in these compounds are mostly pentavalent phosphorus functional groups, resulting in high flame-retardant efficiency. The diisocyanate compound contains two active isocyanate groups (-NCO), enabling stepwise directional reactions, molecular bridging, and the construction of polymer chains. The two active isocyanate groups have equivalent chemical activity, and selective reactions of the single-terminal isocyanate groups can be achieved during the reaction process by controlling temperature, feed ratio, and reaction rate.

[0018] 4. In the technical solution of the present invention, the 2-amino-4-hydroxypyrimidine derivative has a functional group with reversible interaction. A ureidylpyrimidine group with self-healing ability can be constructed on a phosphorus-containing isocyanate intermediate through the 2-amino-4-hydroxypyrimidine derivative. Acrylic anhydride compounds can be introduced with acrylate groups. The acrylate group is an unsaturated functional group containing both carbon-carbon double bonds and ester bonds. When forming an electrolyte, it can provide highly active carbon-carbon double bond sites to construct a chemical network framework, bind the phosphorus flame retardant element in the chemical network framework, and improve the flame retardant performance.

[0019] 5. In the technical solution of the present invention, during the process of generating a phosphorus-containing isocyanate intermediate by reacting a phosphorus-containing hydroxyl compound with a diisocyanate compound, the diisocyanate compound is added dropwise at a rate of 1 to 5 drops per second at 0-5°C and in a protective atmosphere. This can slow down the reaction rate, prevent the system temperature from rising sharply due to excessively rapid exothermic reaction, and avoid the simultaneous reaction of the isocyanate groups at both ends of the diisocyanate compound to generate byproducts.

[0020] 6. In the technical solution of this invention, during the synthesis of the phosphorus-containing isocyanate intermediate, the molar ratio of the phosphorus-containing hydroxyl compound to the diisocyanate compound is 1:(1-1.2). Under this feed ratio, the diisocyanate compound containing two active isocyanate groups (-NCO) can achieve selective reaction of the single-end isocyanate group, retaining the other-end active isocyanate group (-NCO) for the next reaction. Anhydrous tetrahydrofuran is used as the solvent. Anhydrous tetrahydrofuran is a polar solvent that can dissolve most organic or inorganic reactants and promote the reaction. At the same time, it has relatively stable chemical properties and is a good solvent commonly used in organic synthesis. Dibutyltin dilaurate is used as the catalyst. Dibutyltin dilaurate has high catalytic activity and good compatibility with the reaction organic system.

[0021] 7. In the technical solution of the present invention, during the reaction of the phosphorus-containing isocyanate intermediate with the 2-amino-4-hydroxypyrimidine derivative to generate the ureated intermediate, the reaction is carried out at 85-100°C for 1-3 hours to generate the ureated intermediate. At this reaction temperature, the system concentration can be kept stable while ensuring the reaction rate. Stirring for 1-3 hours allows the phosphorus-containing isocyanate intermediate to react fully. In the process of synthesizing the ureated intermediate, anhydrous dimethyl sulfoxide is used as a solvent. Anhydrous dimethyl sulfoxide has good solubility and can fully dissolve the reaction substrate. At the same time, its chemical properties are stable and it will not react with the reactants.

[0022] 8. In the technical solution of the present invention, during the reaction of the urea intermediate with acrylic anhydride compounds to obtain the phosphorus-containing ureidopyrimidinone monomer, anhydrous dichloromethane is used as a solvent, which can avoid hydrolysis of the reactants and effectively dissolve the reaction substrate; the addition of a polymerization inhibitor can prevent the carbon-carbon double bonds of the acrylate group from undergoing self-polymerization during the reaction; the addition of an organic base can activate the reaction sites and neutralize the reaction byproducts.

[0023] 9. This invention also provides a gel electrolyte, which is prepared by isothermal gradient pressure curing of electrolyte raw materials. The electrolyte raw materials include the phosphorus-containing ureapyrimidine ketone monomer described in this invention. The gel electrolyte has a dual-network structure consisting of a covalently cross-linked chemical cross-linked network and a quadruple hydrogen-bonded physical cross-linked network. Isothermal gradient pressure curing enables physical adsorption and chemical bonding at the electrode-electrolyte interface, improving interface stability, reducing interfacial impedance, and enhancing the conductivity of the gel electrolyte. Isothermal gradient pressure curing can also regulate the formation of the dual-network structure of the gel electrolyte. The covalently cross-linked chemical cross-linked network has phosphorus-containing flame-retardant structural units that can catalyze the dehydration and carbonization of the gel electrolyte, forming a dense and stable physically flame-retardant carbon layer, giving the gel electrolyte good flame-retardant properties and mechanical strength. The quadruple hydrogen-bonded physical cross-linked network has dynamically reversible quadruple hydrogen bond interaction sites. After the gel electrolyte is damaged, the hydrogen bonds can be broken and recombined through moderate heating and then cooling, allowing the gel electrolyte to self-repair and recover its properties.

[0024] 10. The present invention also provides a lithium battery comprising the gel electrolyte as described above. The gel electrolyte simultaneously constructs a dual-network structure within the cell, consisting of a chemically cross-linked network of covalent bonds and a physically cross-linked network of quadruple hydrogen bonds, giving the electrolyte excellent self-healing ability and flame-retardant properties, and providing the lithium battery with good conductivity, cycle performance, and safety. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 The flowchart illustrates the steps of a method for preparing a phosphourethrinone monomer according to the second embodiment of the present invention.

[0027] Figure 2 The photon spectrum of the phosphorus-containing ureapyridinone monomer prepared in Experimental Example 1 of this invention is shown.

[0028] Figure 3 The phosphorus spectrum of the phosphorus-containing ureapyridone monomer prepared in Experimental Example 1 of this invention is shown. Detailed Implementation

[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and experimental examples. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0030] In the embodiments provided by this invention, it should be understood that "B corresponding to A" means that B is associated with A, and B can be determined based on A. However, it should also be understood that determining B based on A does not mean determining B solely based on A; B can also be determined based on A and / or other information.

[0031] It should be understood that the phrase "one embodiment" or "an embodiment" throughout the specification means that a specific feature, structure, or characteristic related to the embodiment is included in at least one embodiment of the invention. Therefore, "in one embodiment" or "in an embodiment" appearing throughout the specification does not necessarily refer to the same embodiment. Furthermore, these specific features, structures, or characteristics can be combined in any suitable manner in one or more embodiments. Those skilled in the art should also recognize that the embodiments described in the specification are optional embodiments, and the actions and modules involved are not necessarily essential to the invention.

[0032] In various embodiments of the present invention, it should be understood that the sequence number of each process does not necessarily imply the order of execution. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process defined by the present invention.

[0033] The flowcharts and block diagrams in the accompanying drawings illustrate methods and possible architectures, functions, and operations according to various embodiments of this application. In this regard, each block in the flowchart or block diagram may represent part of a step. It should also be noted that in some alternative implementations, the functions indicated in the blocks may occur in a different order than those indicated in the drawings. For example, two consecutively indicated blocks may actually be executed substantially in parallel, or they may sometimes be executed in reverse order, depending on the functions involved.

[0034] The first embodiment of the present invention provides a phosphorus-containing ureapyrimidinone monomer (P-UPyMA), the general structural formula of which is shown in Formula [1]. Formula [1] In formula [1], R1 and R2 are C1-C4 alkyl groups, which are short-chain aliphatic alkyl groups and have structurally stable flexible regulatory groups. R1 and R2 can be the same. In some embodiments of the present invention, R1 and R2 can be -CH(CH3)2. R3 is an α-hydroxy saturated alkyl group with polar hydroxyl groups, which participate in hydrogen bonding and enhance self-healing performance. In some embodiments of the present invention, R3 can be -CH2- or -CH(CH3)- etc. R4 is an inert group. In some embodiments of the present invention, R4 can be -H or -CH3 etc. Ar is a phenylene or its alkyl-substituted derivative. The bonding sites are the ortho, meta or para positions of the benzene ring and the typical sites of the alkyl-substituted benzene ring (such as 2,4-position, 2,6-position). It belongs to rigid connecting units and can enhance thermal stability and improve flame retardant performance. In some embodiments of the present invention, Ar can specifically be -C6H4- or -C6H3(CH3)- etc.

[0035] Specifically, the phosphorus-containing ureidopyrimidinone monomer has a ureidopyrimidinone group (UPy), a phosphorus-containing flame-retardant structural unit, and an acrylate group. By integrating the dynamic self-healing unit and the phosphorus-containing flame-retardant unit into the monomer at the molecular level, the monomer molecule possesses both flame-retardant and self-healing functions. Simultaneously, the acrylate group in the monomer molecule is an unsaturated functional group containing both carbon-carbon double bonds and ester bonds, providing highly active carbon-carbon double bond sites and enabling diverse chemical bonding between the flame-retardant unit and the substrate.

[0036] Please see Figure 1 The second embodiment of the present invention provides a method for preparing a phosphourethrinone monomer, comprising the following steps: S1. A phosphorus-containing isocyanate intermediate is generated by reacting a phosphorus-containing hydroxyl compound with a diisocyanate compound. S2, the reaction of a phosphorus-containing isocyanate intermediate with a 2-amino-4-hydroxypyrimidine derivative to form a ureated intermediate; and; S3. The urea intermediate reacts with acrylic anhydride compounds to obtain the phosphorus-containing ureidopyrimidinone monomer.

[0037] Specifically, in step S1, the phosphorus-containing hydroxyl compound includes any one or more combinations of (1-hydroxyethyl)phosphonate dimethyl ester and (hydroxymethyl)phosphonate diisopropyl ester. In the phosphorus-containing hydroxyl compound, the phosphorus group is responsible for flame retardancy, and the hydroxyl group is responsible for linkage. The phosphorus group in the phosphorus-containing hydroxyl compound is mostly a pentavalent phosphorus functional group, and its flame retardant efficiency is much higher than that of low-valent phosphorus, making it a commonly used compound for constructing phosphorus-containing flame-retardant units.

[0038] Specifically, the diisocyanate compound includes one or more combinations of toluene-2,6-diisocyanate, toluene-2,4-diisocyanate, 1,3-diisophenylcyanate, terephthalic diisocyanate, and toluene-2,6-diisocyanate. The diisocyanate compound molecule contains two active isocyanate groups (-NCO), enabling key functions such as stepwise directional reactions, molecular bridging, and the construction of polymer chains. The two active isocyanate groups have equivalent chemical activity, and selective reaction of the single-end isocyanate group can be achieved during the reaction process by controlling temperature, feed ratio, and reaction rate, while the other end of the isocyanate group retains its activity.

[0039] Step S1 includes the following steps: at 0-5°C, under a protective atmosphere, the phosphorus-containing hydroxyl compound is dissolved in a first solvent, a catalyst is added, and a diisocyanate compound is added dropwise at a rate of 1-5 drops per second to carry out the reaction; after the addition is complete, the temperature is raised to 40-60°C, and the reaction is continued with stirring for 2-4 hours to obtain a phosphorus-containing isocyanate intermediate. In step S1, the hydroxyl group (-OH) in the phosphorus-containing hydroxyl compound reacts with the single-terminal isocyanate group (-NCO) in the diisocyanate compound to finally generate the phosphorus-containing isocyanate intermediate.

[0040] Specifically, in step S1, the molar ratio of the phosphorus-containing hydroxyl compound to the diisocyanate compound is 1:1-1.2. In some embodiments of the present invention, it may further be 1:(1-1.12), 1:(1.12-1.15), 1:(1.14-1.16), 1:(1.18-1.2), etc.; in some specific embodiments of the present invention, it may be 1:1, 1:1.12, 1:1.14, 1:1.15, 1:1.2, etc. At this feed ratio, the diisocyanate compound containing two active isocyanate groups (-NCO) can achieve selective reaction of the single-end isocyanate group, retaining the other active isocyanate group (-NCO) for the next reaction.

[0041] Specifically, the protective atmosphere in step S1 can be a nitrogen atmosphere. The diisocyanate compound is added dropwise at a rate of 1-5 drops per second over 0.5-1 hour. The temperature during the addition process is 0-5℃, and can further be 0-2℃, 1-3℃, 2-4℃, 3-4℃, 4-5℃, specifically 0℃, 1℃, 2℃, 3℃, 4℃, 5℃, etc. Adding the diisocyanate compound at a low temperature of 0-5℃ can significantly reduce the reaction rate, preventing a sudden rise in system temperature due to excessively rapid exothermic reaction, and avoiding the simultaneous reaction of the isocyanate groups at both ends of the diisocyanate compound to form byproducts.

[0042] Specifically, in step S1, after the dropwise addition is completed, the temperature is raised to 40-60°C. In some embodiments of the present invention, the temperature can be raised to 40-50°C, 50-60°C, 45-50°C, 45-55°C, or 45-60°C; in some specific embodiments of the present invention, the temperature can be raised to 40°C, 45°C, 50°C, 55°C, or 60°C. The reaction is continued with stirring for 2-4 hours. In some embodiments of the present invention, the reaction can be stirred for 2-2.5 hours, 2-3 hours, 2.5-3 hours, 2.5-4 hours, or 3-4 hours; in some specific embodiments of the present invention, the reaction can be stirred for 2 hours, 2.5 hours, 3 hours, 3.5 hours, or 4 hours. After the low-temperature dropwise addition is completed, the reaction system is heated to 40-60°C, which can promote the reaction of unreacted phosphorus-containing hydroxyl compounds and diisocyanate compounds in the system, improve the conversion rate of raw materials, ensure the purity of the generated phosphorus-containing isocyanate intermediate, and the stirring reaction for 2-4 hours provides sufficient reaction time.

[0043] Specifically, in step S1, the first solvent is anhydrous tetrahydrofuran; the catalyst is dibutyltin dilaurate. Anhydrous tetrahydrofuran is a polar solvent that can dissolve most organic or inorganic reactants and promote the reaction. It is also relatively chemically stable, making it a commonly used and effective solvent in organic synthesis. Dibutyltin dilaurate (DBTDL) is the most widely used organotin catalyst in organic and polymer synthesis. It possesses high catalytic activity, good compatibility with organic systems, and controllable catalytic selectivity, making it a classic catalyst for transesterification, polycondensation, and addition reactions.

[0044] Specifically, after the reaction in step S1 is completed, the solvent and excess free diisocyanate compound in the reaction system are removed by vacuum distillation to obtain a purified phosphorus isocyanate intermediate for use in the next step of the reaction.

[0045] Step S2 includes the following steps: dissolving the phosphorus-containing isocyanate intermediate in a second solvent, adding a 2-amino-4-hydroxypyrimidine derivative under a protective atmosphere; heating to 85-100°C and stirring for 1-3 hours to generate a urea intermediate. In this step, the unreacted isocyanate groups in the phosphorus-containing isocyanate intermediate react with the amino group (-NH2) in 2-amino-4-hydroxy-6-methylpyrimidine to form a urea bond, thus obtaining the urea intermediate.

[0046] Specifically, the 2-amino-4-hydroxypyrimidine derivative includes one or more combinations of 2-amino-4-hydroxy-6-methylpyrimidine, 2-amino-4-hydroxy-5-methoxypyrimidine, 2-amino-4-hydroxy-5-bromopyrimidine, and 2-amino-4-hydroxy-6-ethylpyrimidine. The 2-amino-4-hydroxypyrimidine derivative has reversibly interacting functional groups, and a self-healing ureidylpyrimidinone group is constructed on a phosphorus-containing isocyanate intermediate using the 2-amino-4-hydroxypyrimidine derivative.

[0047] Specifically, the molar ratio of the phosphorus-containing isocyanate intermediate to the 2-amino-4-hydroxypyrimidine derivative is 1:1-1.1, which may be 1:(1-1.02), 1:(1.02-1.05), 1:(1.05-1.08), 1:(1.05-1.1), etc. in some embodiments of the present invention; and 1:1, 1:1.02, 1:1.05, 1:1.08, 1:1.1, etc. in some specific embodiments of the present invention.

[0048] Specifically, in step S2, the protective atmosphere can be a nitrogen atmosphere, and the second solvent is anhydrous dimethyl sulfoxide, which has good solubility. The temperature is raised to 85-100°C, and the reaction is stirred for 1-3 hours to generate the ureaized intermediate. In some embodiments of the present invention, the temperature can be raised to 85-90°C, 88-98°C, 90-95°C, 90-100°C, 95-100°C, etc.; in some specific embodiments of the present invention, the temperature can be raised to 85°C, 88°C, 90°C, 95°C, 98°C, 100°C, etc. In some embodiments of the present invention, the reaction is stirred for 1-2 hours, 1.5-2 hours, 2-3 hours, 2.5-3 hours, etc.; in some specific embodiments of the present invention, the reaction is stirred for 1 hour, 1.5 hours, 2 hours, 2.5 hours, 3 hours, etc.

[0049] Specifically, after the reaction in step S2 is completed, the mixture is cooled to room temperature, and the reaction solution is slowly poured into 8-10 times its volume of anhydrous diethyl ether to induce precipitation of the urea intermediate. The solid urea intermediate is collected by filtration, washed 3-5 times with anhydrous diethyl ether, and dried under reduced pressure to obtain the urea intermediate, which is used for the next step of the reaction.

[0050] Step S3 includes the following steps: At 0-5℃, under a protective atmosphere, the urea intermediate is dissolved in a third solvent. A polymerization inhibitor and an organic base are added to form a reaction system. An acrylic anhydride compound is added dropwise at a rate of 1-5 drops per second. After the addition is complete, the reaction is stirred for 20-40 minutes. The temperature is then raised to room temperature, and the reaction continues for 2-4 hours to obtain a phosphorus-containing urea-pyrimidinone monomer. During this process, the urea intermediate reacts with the anhydride group (-CO-O-CO-) in methacrylic anhydride to generate a phosphorus-containing urea-pyrimidinone monomer. A new functional group, acrylate (-O-CO-C(CH3)=CH2), is synthesized during this process. The acrylate group is an unsaturated functional group containing both carbon-carbon double bonds and ester bonds.

[0051] Specifically, the acrylic anhydride compounds include one or more combinations of methacrylic anhydride, dimethacrylic anhydride, ethylacrylic anhydride, and phenylacrylic anhydride. The acrylic anhydride compounds introduce acrylate groups onto the ureaization intermediate.

[0052] Specifically, the molar ratio of the ureaized intermediate to the acrylic anhydride compound is 1:(1.2-1.5), which in some embodiments of the present invention may be 1:(1.2-1.25), 1:(1.2-1.3), 1:(1.25-1.35), 1:(1.4-1.5), etc.; and in some specific embodiments of the present invention may be 1:1.2, 1:1.25, 1:1.3, 1:1.4, 1:1.5, etc.

[0053] Specifically, in step S3, the protective atmosphere can be a nitrogen atmosphere; the third solvent is anhydrous dichloromethane, which can effectively prevent hydrolysis of the reactants and effectively dissolve the reaction substrate. The polymerization inhibitor is hydroquinone monomethyl ether (MEHQ), which can prevent the carbon-carbon double bond from self-polymerizing during the reaction and does not affect the main reaction; the organic base is N,N-diisopropylethylamine (DIPEA), which is a weak organic base with mild basicity and will not destroy the urea bond. During the reaction, it can activate the active H next to the carbonyl group of the pyrimidine ring to generate an enol anion, activating -C=O into a nucleophilic site that can attack the anhydride; N,N-diisopropylethylamine can also neutralize by-products and prevent product hydrolysis.

[0054] Specifically, in step S3, a reaction system is formed at 0-5°C. In some embodiments of the present invention, the temperature for forming the reaction system can be further 0-2°C, 1-3°C, 2-4°C, 3-4°C, 4-5°C, etc., specifically 0°C, 1°C, 2°C, 3°C, 4°C, 5°C, etc. Acrylic anhydride compounds are added dropwise at a rate of 1-5 drops per second over 0.5-1 hour, and the reaction is stirred at room temperature for 20-40 minutes. In some embodiments of the present invention, the stirring time can be 20-25 minutes, 20-30 minutes, 20-35 minutes, 30-40 minutes, etc.; further, the stirring time can specifically be 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, etc. Using methacrylic anhydride at 0-5°C can avoid localized exothermic reactions that could lead to double bond self-polymerization. After the dropwise addition reaction is completed, the temperature is raised to room temperature to continue the reaction, allowing the product to fully react and improving the utilization rate of raw materials.

[0055] After the reaction in step S3 is completed, a small amount of anhydrous methanol is added dropwise to the reaction system to quench the residual acrylic anhydride compounds. The reaction solution is washed successively with saturated sodium bicarbonate solution and dried with anhydrous sodium sulfate. After filtration, the solvent is removed by vacuum concentration to obtain the crude product of the phosphorus-containing ureapyridinone monomer. The crude product can be purified by recrystallization with a mixed solvent of diethyl ether / n-hexane and dried to finally obtain the relatively pure phosphorus-containing ureapyridinone monomer target product.

[0056] In the above steps, a phosphorus-containing isocyanate intermediate is generated by reacting a phosphorus-containing hydroxyl compound with a diisocyanate compound, thus constructing a phosphorus-containing flame-retardant structural unit. The phosphorus-containing isocyanate intermediate is then reacted with a 2-amino-4-hydroxypyrimidine derivative to construct a ureidylpyrimidinone group with self-healing capabilities, yielding a ureated intermediate. The ureated intermediate is then reacted with an acrylic anhydride compound to introduce acrylate groups, resulting in the phosphorus-containing ureidylpyrimidinone monomer. The prepared phosphorus-containing ureidylpyrimidinone monomer simultaneously contains ureidylpyrimidinone groups, a phosphorus-containing flame-retardant structural unit, and acrylate groups. This phosphorus-containing ureidylpyrimidinone monomer integrates a dynamically self-healing ureidylpyrimidinone group and a flame-retardant phosphorus-containing flame-retardant structural unit into the monomer from the molecular level.

[0057] The third embodiment of the present invention provides a gel electrolyte, which is prepared by curing electrolyte raw materials through a constant temperature gradient pressure. The electrolyte raw materials include the phosphorus-containing ureapyrimidine ketone monomer as described in the first embodiment; the electrolyte raw materials include the phosphorus-containing ureapyrimidine ketone monomer prepared by the method described in the second embodiment.

[0058] It is understood that the specific limitations of the phosphorus-containing ureapyridinone monomer in the electrolyte raw material of the gel electrolyte in this embodiment are consistent with those in the first and second embodiments, and will not be repeated here.

[0059] The electrolyte raw material also includes ionic liquid monomers, lithium salts, initiators, compatibilizers, and plasticizers. The content of each component in the electrolyte raw material is as follows: the mass percentage of phosphauracil pyrimidinone monomers is 0.5% to 5%, the mass percentage of ionic liquid monomers is 5% to 20%, the mass percentage of lithium salts is 5% to 15%, the mass percentage of compatibilizers is 0.5% to 3%, the mass percentage of initiators is 0.1% to 2%, and the mass percentage of plasticizers is 60% to 85%.

[0060] Electrolyte raw materials containing phosphauracil pyrimidinone monomers can be used to prepare gel electrolytes through isothermal gradient pressure curing.

[0061] Specifically, the isothermal gradient pressure curing process is as follows: The three-stage isothermal gradient pressure curing process induces the polymerization reaction of the gel electrolyte within the pre-designed structure. Specifically, the isothermal temperature is 40-90℃, and can be further specified as 40-50℃, 55-75℃, 60-70℃, 70-80℃, 80-90℃, etc. The battery cell is subjected to a gradient pressure increase sequentially through the first, second, and third stages and maintained for a certain period. The pressure difference between the first and second stages is 0.01-0.06 MPa, and the pressure difference between the second and third stages is 0.01-0.12 MPa. In the first stage of gradient pressurization, maintain a pressure of 0.001-0.02 MPa for 0.5-6 hours; In the second stage, maintain a pressure of 0.03-0.06 MPa for 1-5 hours; In the third stage, maintain a pressure of 0.07-0.15 MPa for 1-4 hours.

[0062] After the curing process is complete, allow it to cool naturally to room temperature to complete the polymerization reaction.

[0063] The three stages of isothermal gradient pressure-increasing curing correspond to three key state transition nodes: fluid wetting, gel anchoring, and gel solidification. Isothermal gradient pressure-increasing guides the smooth transition of the gel electrolyte precursor solution from a liquid to a solid gel, driving physical adsorption and chemical bonding between the gel electrolyte and the electrode interface during this process. Gradient pressure increases allow the gel electrolyte to undergo an adaptation process and rearrange itself as the pressure increases at each stage, enabling the gradual and slow release of internal stress. The specific limitations of isothermal gradient pressure-increasing curing are consistent with the discussions on isothermal gradient pressure-increasing curing mentioned in the fourth embodiment regarding lithium battery fabrication, and will not be repeated here.

[0064] During the curing process, the acrylate groups in the phosphauracil ketone monomer possess highly active carbon-carbon double bond sites. During gel electrolyte curing, these carbon-carbon double bonds can undergo free radical copolymerization with the ionic liquid monomer to form a copolymer, creating a covalently cross-linked chemical cross-linked network. In this free radical copolymerization process, the phosphorus-containing flame-retardant structural units of the phosphauracil ketone monomer do not participate in the reaction. Embedded within the covalently cross-linked chemical cross-linked network, these phosphorus-containing flame-retardant structural units catalyze the dehydration and carbonization of the gel electrolyte, forming a dense and stable physically flame-retardant char layer. This gives the gel electrolyte excellent flame-retardant properties and mechanical strength. In free radical copolymerization, the ureidopyrimidinone group of the phosphoureidopyrimidinone monomer does not participate in the reaction. The ureidopyrimidinone group has a dynamic and reversible quadruple hydrogen bond interaction site. After the phosphoureidopyrimidinone monomer and the ionic liquid monomer complete the free radical copolymerization reaction, the ureidopyrimidinone group on the copolymer molecular chain undergoes quadruple hydrogen bond self-assembly between molecules to form a physical cross-linking network. The reversible quadruple hydrogen bond interaction enables the gel electrolyte to have self-healing properties.

[0065] After curing, the gel electrolyte comprises a dual-network structure consisting of a covalently cross-linked chemical cross-linked network and a quadruple hydrogen-linked physical cross-linked network. The chemical and physical cross-linked networks in the gel electrolyte work synergistically at the microscopic level to jointly construct the dual-network structural framework of the gel electrolyte, providing a supporting framework for the gel electrolyte.

[0066] Through thermally reversible dynamic rheological temperature scanning test and DMA dynamic thermomechanical analysis test, it was found that the gel electrolyte provided in the third embodiment of the present invention has excellent self-healing properties and the gel electrolyte has a dual network structure that is both interconnected and maintains kinetic independence.

[0067] The fourth embodiment of the present invention provides a lithium battery, wherein the electrolyte of the lithium battery is the gel electrolyte described in the third embodiment of the present invention; the preparation method of the lithium battery is as follows: (1) A gel electrolyte precursor solution was prepared by stepwise mixing of a phosphauracil pyrimidinone monomer, an ionic liquid monomer, a lithium salt, an initiator, a compatibilizer, and a plasticizer. First, the phosphauracil pyrimidinone bifunctional monomer, the ionic liquid monomer, and the compatibilizer were mixed and stirred at 40-50℃ for 2-3 hours to obtain a first premix. The plasticizer was pre-cooled at 0-5℃, and then the lithium salt was added. The first premix was added to the lithium salt-containing plasticizer while stirring, keeping the temperature of the mixing system below 15℃. Finally, the initiator was added, and the mixture was stirred at low temperature for 1-2 hours to obtain a homogeneous, transparent, and precipitate-free gel electrolyte precursor solution. No stratification or precipitation was observed after standing at room temperature for 20-24 hours.

[0068] (2) Perform cell assembly and electrolyte injection. Assemble the positive electrode, separator and negative electrode in sequence into a cell and inject the prepared gel electrolyte precursor solution into the cell.

[0069] (3) The assembled battery cell undergoes a three-stage isothermal gradient pressure curing process to induce in-situ polymerization of the gel electrolyte within the battery. The isothermal temperature is 40-90℃. Gradual pressure is applied to the battery cell in the order of the first, second, and third stages and maintained for a certain time. The pressure difference between the first and second stages is 0.01-0.06 MPa, and the pressure difference between the second and third stages is 0.01-0.12 MPa. During the first stage of gradient pressure increase, a pressure of 0.001-0.02 MPa is maintained for 0.5-6 hours; during the second stage, a pressure of 0.03-0.06 MPa is maintained for 1-5 hours; and during the third stage, a pressure of 0.07-0.15 MPa is maintained for 1-4 hours. After the curing process is complete, the cell is allowed to cool naturally to room temperature, completing the in-situ polymerization reaction.

[0070] (4) The cell is sealed and then subjected to conventional aging, formation, and capacity testing processes to obtain the finished lithium battery.

[0071] Specifically, the content of each component in the gel electrolyte precursor solution in step (1) is as follows: the mass percentage of the phosphauracil pyrimidinone monomer is 0.5% to 5%, the mass percentage of the ionic liquid monomer is 5% to 20%, the mass percentage of the lithium salt is 5% to 15%, the mass percentage of the compatibilizer is 0.5% to 3%, the mass percentage of the initiator is 0.1% to 2%, and the mass percentage of the plasticizer is 60% to 85%. By precisely mixing the phosphauracil pyrimidinone monomer with the polymerizable ionic liquid, lithium salt, compatibilizer, initiator, and plasticizer, and through a stepwise mixing process, a uniform and stable gel electrolyte precursor solution can be obtained.

[0072] Specifically, the phosphoureidopyrimidinone monomer possesses a ureidopyrimidinone group, a phosphorus-containing flame-retardant structural unit, and an acrylate group. The acrylate group in the phosphoureidopyrimidinone monomer has highly active carbon-carbon double bond sites. During the formation of the gel electrolyte, the carbon-carbon double bonds in the acrylate group of the phosphoureidopyrimidinone monomer can undergo a free radical copolymerization reaction with the ionic liquid monomer to generate a copolymer, forming a covalently cross-linked chemical cross-linked network. During the free radical copolymerization reaction, the phosphorus-containing flame-retardant structural unit of the phosphoureidopyrimidinone monomer does not participate in the reaction. Embedded in the covalently cross-linked chemical cross-linked network, the phosphorus-containing flame-retardant structural unit can catalyze the dehydration and carbonization of the gel electrolyte, forming a dense and stable physically flame-retardant char layer, thus giving the gel electrolyte good flame-retardant properties and mechanical strength. In free radical copolymerization, the ureidopyrimidinone group of the phosphoureidopyrimidinone monomer does not participate in the reaction. The ureidopyrimidinone group has a dynamic and reversible quadruple hydrogen bond interaction site. After the phosphoureidopyrimidinone monomer and the ionic liquid monomer complete the free radical copolymerization reaction, the ureidopyrimidinone group on the copolymer molecular chain undergoes quadruple hydrogen bond self-assembly between molecules to form a physical cross-linking network. The reversible quadruple hydrogen bond interaction enables the gel electrolyte to have self-healing properties.

[0073] Specifically, the ionic liquid monomer comprises one or more combinations of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide, 1-vinyl-3-alkylimidazolium bis(trifluoromethanesulfonyl)imide, 1-vinyl-3-alkylimidazolium bis(fluorosulfonyl)imide, and N-vinyl-N-alkylpyrrolidine bis(trifluoromethanesulfonyl)imide. The ionic liquid monomer possesses a polymerizable backbone and ion-conducting function. Under the action of an initiator, the ionic liquid monomer undergoes a free radical copolymerization reaction with a phosphauracil-containing pyrimidinone bifunctional monomer to form a chemically cross-linked network. The viscosity of the ionic liquid monomer at room temperature is less than or equal to 100 mPa·s. Low-viscosity ionic liquid monomers exhibit better compatibility, enabling faster and more uniform miscibility and reaction with other monomers and solvents to form a homogeneous and stable gel electrolyte precursor solution.

[0074] Specifically, the lithium salt includes one or more combinations of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI), lithium bis(fluorosulfonyl)imide (LiFSI), and lithium hexafluorophosphate (LiPF6). The lithium salt provides freely moving lithium ions to the gel electrolyte. With the help of a plasticizer, the lithium salt fully dissociates to form freely moving lithium ions, which are dispersed in the gel electrolyte precursor solution, giving the gel electrolyte precursor solution uniform ionic conductivity.

[0075] Specifically, the compatibilizer includes one or more of triethyl phosphate, tributyl phosphate, polyethylene glycol dimethyl ether, and 1-ethyl-3-methylimidazolium diethyl phosphate. The compatibilizer is a regulator of the compatibility of the gel electrolyte precursor solution system. Through intermolecular hydrogen bonds, van der Waals forces, or electrostatic interactions, it forms molecular bridges at the interface between the ionic liquid monomer and the lithium salt / plasticizer, reducing the interfacial tension between the components. This allows the lithium salt and plasticizer to be uniformly and stably dispersed in the ionic liquid monomer, forming a homogeneous and stable gel electrolyte precursor solution, preventing stratification or precipitation.

[0076] Specifically, the initiator includes one or a combination of two of azobisisobutyronitrile (AIBN) and benzoyl peroxide (BPO). The initiator is a trigger for the in-situ polymerization reaction of the gel electrolyte precursor solution. The initiator itself decomposes to generate free radicals, which initiate a free radical copolymerization reaction between the phosphatidylpyrimidinone monomer and the ionic liquid monomer, promoting the formation of a chemical cross-linked network.

[0077] Specifically, the plasticizer includes one or more combinations of succinic anionyl nitrile (SN), polyvinyl alcohol (PVA), ethylene carbonate (EC), propylene carbonate (PC), fluoroethylene carbonate (FEC), dimethyl carbonate (DMC), and diethyl carbonate (DEC). As a polar co-solvent, the plasticizer dissolves lithium salts and promotes their complete dissociation, improving the ionic conductivity of the gel electrolyte precursor solution. Simultaneously, it is miscible with ionic liquid monomers, reducing the viscosity of the gel electrolyte precursor solution, ensuring fluidity, facilitating the filling of cell pores by the gel electrolyte, and contributing to the formation of a uniform gel electrolyte network structure.

[0078] Specifically, in step (2), the positive electrode can be a lithium iron phosphate (LFP) positive electrode, a ternary lithium (NCM / NCA) positive electrode, a lithium cobalt oxide (LCO) positive electrode, etc., for example, it can be NCM811(Li(Ni) 0.8 Co 0.1 Mn 0.1 The positive electrode is a ternary cathode (O2); the negative electrode can be a lithium metal negative electrode or a silicon-carbon composite negative electrode, such as a graphite-silicon-carbon composite negative electrode. The positive and negative electrodes are prepared through processes such as slurry preparation, coating, rolling, slitting, and die-cutting. During cell assembly, a stacking process is used, assembling the cells in the order of negative electrode - separator - positive electrode to form a dry cell.

[0079] Specifically, in step (3) of isothermal gradient pressure curing, the constant temperature ensures a uniform reaction rate, allowing the curing reaction to proceed synchronously within the system. This avoids excessively high local temperatures leading to overly rapid reactions and insufficient polymerization, and prevents uneven structures caused by differences in local reaction progress, thus ensuring the formation of a complete gel electrolyte network structure. Isothermal gradient pressure curing enables the gel electrolyte precursor solution to undergo in-situ polymerization within the battery, forming a gel electrolyte. This achieves physical adsorption and chemical bonding at the electrode-electrolyte interface of the gel electrolyte battery, improving the stability of the gel electrolyte-electrode interface and giving the battery excellent conductivity.

[0080] Specifically, the pressure of the three stages of isothermal gradient pressurization corresponds to three key state transition nodes: fluid wetting, gel anchoring, and gel solidification. Isothermal gradient pressurization guides the smooth transition of the gel electrolyte precursor solution from a liquid to a solid gel, driving physical adsorption and chemical bonding between the gel electrolyte and the electrode interface during this process. The gradient pressurization allows the gel electrolyte to undergo an adaptation process and rearrange itself as the pressure increases at each stage, enabling the gradual and slow release of internal stress. If high pressure is applied directly during solidification, the drastic shrinkage will lead to stress concentration, potentially causing cracks in the gel electrolyte and resulting in interface detachment. Furthermore, isothermal gradient pressurization can also regulate the formation of the gel electrolyte's dual-network structure.

[0081] Specifically, the first stage of the isothermal gradient pressurization curing process is a low-pressure impregnation period, with a curing pressure of 0.001-0.02 MPa. Under this low and uniform pressure, the low-viscosity gel electrolyte precursor solution fully penetrates the micropores between the positive and negative electrode active material particles and the macropores of the membrane. In this stage, the in-situ polymerization reaction has just begun, and the viscosity of the gel electrolyte precursor solution starts to rise slowly, but the gel electrolyte network structure has not yet formed. This stage eliminates gas from the electrode pores, laying the foundation for the subsequent formation of the gel electrolyte dual-network structure. The pressure in the first stage should not be too high; if the pressure is too high, it will hinder the penetration of the gel electrolyte precursor solution into the depths of the micropores, resulting in incomplete interfacial contact.

[0082] Specifically, in the second stage of isothermal gradient pressure curing, gel networking and initial anchoring of the electrode interface occur. As the pressure increases, the degree of polymerization of the gel electrolyte precursor solution increases. The phosphoureidopyrimidinone monomer and the ionic liquid monomer react under the action of an initiator. The polymerizable carbon-carbon double bonds on the acrylate groups of the phosphoureidopyrimidinone monomer undergo free radical copolymerization with the ionic liquid monomer to form a copolymer, initiating the formation of a covalently cross-linked chemical cross-linked network. During this process, the phosphorus-containing flame-retardant structural units on the phosphoureidopyrimidinone monomer do not participate in the reaction, maintaining their original flame-retardant properties. After the phosphoureidopyrimidinone monomer and the ionic liquid monomer complete free radical copolymerization, the ureidopyrimidinone groups on the copolymer molecular chains undergo quadruple hydrogen bond self-assembly between molecules, forming a physical cross-linked network. The physical and chemical cross-linked networks of the gel electrolyte form a dual-network structure that is both interpenetrating and relatively independent. In this stage, a gel electrolyte with a dual-network structure of covalently cross-linked chemical cross-linked network and quadruple hydrogen bonded physical cross-linked network is initially formed.

[0083] Specifically, in the second stage of isothermal gradient pressure curing, pressure drives the gel electrolyte to adhere to the electrode surface, allowing the forming, somewhat flexible gel electrolyte to adhere more tightly to the micro-roughness of the electrode surface, increasing the effective contact area between the gel electrolyte and the electrode. Simultaneously, the pressure enhances the physical interaction between the polar groups in the gel electrolyte precursor solution and the electrode, achieving physical adsorption. In this stage, the dual-network structure framework of the gel electrolyte is initially formed, establishing a preliminary, primarily physically adsorbed, tight interface with the electrode, providing a stable foundation for the more robust chemical bonding in the next stage.

[0084] Specifically, in the third stage of isothermal gradient pressurization curing, the higher pressure helps drive the remaining monomers to complete the reaction and enables the gel electrolyte to complete its final curing. At the same time, the pressure promotes covalent bonding between the ionic liquid monomer, the phosphoureidopyrimidinone monomer and the electrode surface, realizing the chemical bonding between the gel electrolyte and the electrode.

[0085] The lithium batteries obtained through the above methods exhibit excellent electrical conductivity, good cycle performance, and high safety. The phosphourea-containing pyrimidinone monomer integrates dynamic self-healing and flame-retardant units at the molecular level, giving the monomer molecules both flame-retardant and self-healing functions. When used to prepare gel electrolytes, these gel electrolytes possess excellent flame-retardant and self-healing properties. The gel electrolyte simultaneously constructs a dual-network structure within the lithium battery using the phosphourea-containing pyrimidinone monomer, consisting of a covalently cross-linked chemical cross-linked network and a quadruple hydrogen-bonded physical cross-linked network. The chemical and physical cross-linked networks in the gel electrolyte work synergistically at the microscopic level to jointly construct the dual-network structural framework of the gel electrolyte, providing strong support and contributing to improved cycle performance and safety. This results in lithium batteries with excellent conductivity, cycle performance, and safety.

[0086] Experimental Example 1: Synthesis of a phosphorus-containing ureapyridinium ketone monomer Step 1: Synthesis of phosphorus-containing isocyanate intermediates Under nitrogen protection and an ice bath at 0°C, 18.2 g of diisopropyl phosphonate (hydroxymethyl)phosphonate was dissolved in 100 mL of anhydrous tetrahydrofuran, and 0.05 g of dibutyltin dilaurate catalyst was added. Subsequently, 22.8 g of 2,4-toluene diisocyanate was added dropwise at a rate of 3 drops per second over 1 h. After the addition was complete, the reaction mixture was heated to 50°C and the reaction was stirred for another 3 hours. After the reaction was completed, the solvent and excess free diisocyanate were removed by vacuum distillation to obtain a viscous phosphorus-containing isocyanate intermediate for the next reaction step.

[0087] Step 2: Synthesis of ureaization intermediates Dissolve 20 g of the phosphorus isocyanate intermediate obtained in the previous step in 120 mL of anhydrous dimethyl sulfoxide. Under nitrogen protection, add 12.5 g of 2-amino-4-hydroxy-6-methylpyrimidine. Heat the mixture to 95 °C and stir for 2 hours to generate the urea intermediate. After the reaction is complete, cool to room temperature and slowly pour the reaction solution into 10 times its volume of anhydrous diethyl ether to induce precipitation of the urea intermediate. Filter and collect the solid urea intermediate, wash three times with anhydrous diethyl ether, and dry under reduced pressure to obtain a white powdery urea intermediate.

[0088] Step 3: Introduction of acrylate groups Under nitrogen protection and a 0°C ice bath, 23 g of the ureated intermediate obtained in the previous step was dissolved in 150 mL of anhydrous dichloromethane, and 0.05 g of the polymerization inhibitor hydroquinone monomethyl ether (MEHQ) and 12.9 g of the organic base N,N-diisopropylethylamine (DIPEA) were added. 17.0 g of methacrylic anhydride was slowly added dropwise over 1 h while maintaining a low temperature. After the addition was complete, the mixture was stirred at 0°C for 30 min, then allowed to return to room temperature (25°C) and the reaction continued for 3 hours.

[0089] After the reaction was complete, a small amount of anhydrous methanol was added dropwise to quench the residual acid anhydride. The reaction solution was washed successively with saturated sodium bicarbonate solution and dried over anhydrous sodium sulfate. After filtration, the solvent was removed by concentration under reduced pressure to obtain the phosphoureidopyrimidinone monomer. The crude product could be purified by recrystallization in a mixed solvent of diethyl ether / n-hexane to finally obtain the target product, the phosphoureidopyrimidinone monomer, which was a white solid.

[0090] The reaction equation for Experiment Example 1 is shown below:

[0091] In this composition, 1 is diisopropyl (hydroxymethyl)phosphonate, 3 is 2,4-toluene diisocyanate, 2 is a phosphorus-containing isocyanate intermediate, 6 is 2-amino-4-hydroxy-6-methylpyrimidine, 3 is a ureation intermediate, 7 is methacrylic anhydride, and 4 is a phosphorus-containing ureidopyrimidinone monomer. In the phosphorus-containing ureidopyrimidinone monomer obtained in Example 1, the groups R1 and R2 corresponding to the general formula are both -CH(CH3)2; R3 is -CH2-; R4 is -CH3; and Ar is -C6H4-.

[0092] The phosphorus-containing ureapyridone monomer prepared in Example 1 was verified by nuclear magnetic resonance. The product obtained in Example 1 was dissolved in DMSO- d In a 6-(deuterated dimethyl sulfoxide) solvent, the sample was characterized by NMR spectroscopy at 400 MHz. 1 ¹H NMR was performed at 162 MHz to characterize the ¹H NMR spectrum. 31 The obtained proton and phosphorus spectra (P NMR) are as follows: Figure 2 as well as Figure 3 As shown in the image.

[0093] Combination Figure 2 As shown, the product obtained in Experimental Example 1 1 H NMR (400 MHz, DMSO- d 6) The data are as follows: δ = 13.1 (s, 1H), 11.65 (s, 1H), 10.10 (s, 1H), 8.80 (s, 1H), 7.75 (s, 1H), 7.45 (dd, J = 8.0, 1.5 Hz, 1H), 6.05 (s, 1H), 5.85 (s, 1H), 5.65 (s, 1H), 4.65 (t, J = 6.2 Hz, 2H), 4.45 (d, J = 11.5 Hz, 2H), 2.20 (s, 6H), 1.90 (s, 3H), 1.25 (d,J = 6.2 Hz, 12H).

[0094] δ = 13.1 (s, 1H), 11.65 (s, 1H), 10.10 (s, 1H) are characteristic peaks for hydrogen atoms in the ureidopyrimidinone group; δ = 6.05 (s, 1H), 5.85 (s, 1H), 5.65 (s, 1H) are characteristic peaks for hydrogen atoms in the acrylate group; δ = 4.65 (t, J = 6.2 Hz, 2H), δ=1.25 (d, J = 6.2 Hz, 12H) is the characteristic peak of hydrogen atoms in phosphorus-containing groups.

[0095] Combination Figure 3 As shown, the product obtained in Experimental Example 1 31 P NMR (162 MHz, DMSO- d 6) The data is as follows: A sharp single peak appears at δ=21.2 ppm, without any impurity peaks or shoulder peaks, indicating that the phosphorus-containing flame retardant group has been successfully introduced into the molecular backbone. The phosphorus groups in the product have a consistent chemical environment, no phosphorus-containing byproducts are generated, and the overall purity of the product is high.

[0096] pass 1 H NMR and 31 P NMR characterization results indicate that the phosphorus-containing ureapyrimidine ketone monomer was successfully prepared, and the obtained monomer has high purity. Using the method of this invention, a phosphorus-containing hydroxyl compound is reacted with a diisocyanate compound to generate a phosphorus-containing isocyanate intermediate, constructing a phosphorus-containing flame-retardant structural unit. The phosphorus-containing isocyanate intermediate is then reacted with a 2-amino-4-hydroxypyrimidine derivative to construct a ureapyrimidine ketone group with self-healing capabilities, yielding a ureated intermediate. The ureated intermediate is then reacted with an acrylic anhydride compound to introduce acrylate groups, obtaining the phosphorus-containing ureapyrimidine ketone monomer. The phosphorus-containing ureapyrimidine ketone monomer integrates a dynamically self-healing ureapyrimidine ketone group with a flame-retardant phosphorus-containing flame-retardant structural unit from the molecular level.

[0097] The following experimental examples 2-4 and comparative examples 1-4 are used to prepare gel electrolytes and lithium batteries; the gel electrolytes of experimental examples 2-4 contain the phosphorus-containing ureapyridinone monomer synthesized in experimental example 1.

[0098] Experimental Example 2: 1. Formulation and preparation of gel electrolyte precursor solution The formulation of the gel electrolyte precursor solution is as follows: Example 1: 5 g (5%) of phosphorus-containing ureapyridinone monomer (P-UPyMA) synthesized. Ionic liquid monomer (1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt): 10 g (10%); Lithium salt (lithium bis(trifluoromethanesulfonylimide)): 7 g (7%); Compatibilizer (triethyl phosphate): 1 g (1%); Initiator (AIBN): 1 g (1%); Plasticizer (EC / EMC=3 / 7; v / v): 76 g (76%).

[0099] The preparation process of the gel electrolyte precursor solution is as follows: (1) Preparation of the first premixed solution: Add the phosphauracil pyrimidinone monomer, 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt and triethyl phosphate to the sample bottle, place it on a heating platform at 50°C, and stir magnetically for 2 h to obtain a uniform, transparent, light yellow liquid.

[0100] (2) Plasticizer pre-cooling: Mix EC / EMC at a volume ratio of 3 / 7 and cool in an ice water bath to about 5°C, then add lithium bis(trifluoromethanesulfonyl)imide.

[0101] (3) Low-temperature mixing: Under magnetic stirring, the first premixed liquid is slowly added dropwise to the cooled electrolyte, keeping the temperature of the mixing system below 15°C.

[0102] (4) Add initiator: Add AIBN to the above mixture and continue stirring at low temperature for 1 hour until completely dissolved to obtain a homogeneous gel electrolyte precursor solution without precipitation, and no stratification or precipitation after standing at room temperature for 24 hours.

[0103] 2. Cell Assembly (1) Ternary positive electrode sheets and silicon-based graphite negative electrode sheets are prepared by processes such as homogenization, coating, rolling, slitting and die cutting. The prepared positive and negative electrode sheets and separators are stacked and assembled into dry cells in the order of negative electrode sheet-separator-positive electrode sheet. Positive electrode preparation: NCM811(Li(Ni) 0.8 Co 0.1 Mn 0.1 O2) Single crystal ternary material, carbon black, carbon nanotubes and polyvinylidene fluoride are mixed in a mass ratio of 97:1:0.8:1.2, and NMP solvent is added at the same time to homogenize the mixture. The mixture is then uniformly coated on both sides of the aluminum foil surface, and after drying, rolling and die cutting, the positive electrode sheet is obtained. Negative electrode preparation: Graphite, silicon carbide, carbon nanotubes, styrene-butadiene rubber, sodium carboxymethyl cellulose and polyacrylic acid are mixed in a mass ratio of 80:15:1:1:1:2, and deionized water is added at the same time to homogenize the mixture. The mixture is then uniformly coated on both sides of the copper foil surface, and after drying, rolling and die cutting, the negative electrode is obtained. (2) Inject the aforementioned precursor liquid into the dry cell, seal it, and let it stand at room temperature for 24 hours.

[0104] 3. In-situ polymerization and curing (1) After the above-mentioned settling period, place the sealed battery in a temperature- and pressure-controlled oven and perform the following polymerization and curing process at a constant temperature of 70°C: First stage: 0.02 MPa, maintained for 4 hours; Second stage: Increase the pressure to 0.05 MPa and maintain it for 3 hours; Third stage: Increase the pressure further to 0.10 MPa and maintain it for 3 hours.

[0105] After the process is complete, allow it to cool naturally to room temperature to complete the in-situ polymerization.

[0106] (2) The cells are subjected to conventional aging, formation and capacity testing processes to obtain finished lithium batteries.

[0107] Experimental Example 3: The lithium battery was prepared according to the method described in Experimental Example 2, except that the content of the phosphorus-containing ureidopyrimidinone monomer was adjusted to 4.5 g (4.5%) and the content of 1-vinyl-3-ethylimidazolium bis(trifluoromethanesulfonyl)imide salt was adjusted to 10.5 g (10.5%).

[0108] Experiment Example 4: The lithium battery was prepared according to the method described in Example 2, except that the gradient pressure and time for curing were adjusted. The pressure program is as follows: First stage: 0.01 MPa, maintained for 3 hours; Second stage: Increase the pressure to 0.03 MPa and maintain it for 4 hours; Phase 3: Increase the pressure further to 0.12 MPa and maintain it for 5 hours.

[0109] Comparative Example 1: The lithium battery was prepared according to the method described in Example 2, except that the phosphorus-containing ureapyrimidine ketone monomer (P-UPyMA) was not added, and the proportion of the ionic liquid monomer was adjusted to 15g (15.0%).

[0110] Comparative Example 2: The lithium battery was prepared according to the method described in Experimental Example 2, except that the phosphorus-containing ureapyrimidinone monomer (P-UPyMA) was replaced with 3g of UPy-ethyl methacrylate monomer (UPyMA), and 2g of triphenyl phosphate (TPP) was added as a small molecule flame retardant to supplement the phosphorus content.

[0111] Comparative Example 3: The lithium battery was prepared by following the method described in Example 2, except that the in-situ polymerization was carried out only at a constant pressure of 0.1 MPa, without a step-up pressure process.

[0112] Comparative Example 4: The lithium battery was prepared by operating according to the method described in Experiment Example 2, except that the holding time of the second stage pressure was shortened to 0.5 h during the gradient pressurization process.

[0113] The homogeneity of the gel electrolyte precursor solutions in Experiments 2-4 and Comparative Examples 1-4 was evaluated. The ionic conductivity, limiting oxygen index (LOI), and self-healing efficiency of the gel electrolytes in Experiments 2-4 and Comparative Examples 1-4 were measured. The cycle retention rate of the lithium batteries in Experiments 2-4 and Comparative Examples 1-4 was measured, and safety performance tests such as heating, deformation extrusion, and needle penetration were conducted.

[0114] To evaluate the homogeneity of the gel electrolyte precursor solution, the gel electrolyte precursor solutions of Experimental Examples 2-4 and Comparative Examples 1-4 were placed in transparent sample bottles and their state was observed. After standing for 24 hours, it was observed whether there was layering or precipitation.

[0115] The ionic conductivity of the gel electrolyte was determined by EIS (electrochemical impedance spectroscopy) (25℃, mS / cm).

[0116] The limiting oxygen index (LOI) of the gel electrolyte was measured using an oxygen index meter. The limiting oxygen index (LOI) is a core indicator for measuring flame retardant performance; the higher the limiting oxygen index (LOI), the better the flame retardant performance.

[0117] The self-healing efficiency of the gel electrolyte was calculated by measuring the ionic conductivity. The ionic conductivity a1 of the original gel electrolyte was measured according to the ionic conductivity test method. The gel electrolyte was then scratched with a blade to form a through crack, simulating gel damage during the cycling process. After self-healing at room temperature for 12 hours, the ionic conductivity a2 of the repaired gel membrane was measured again. The self-healing efficiency = (a2 / a1) × 100%.

[0118] The lithium batteries in Experiments 2-4 and Comparative Examples 1-4 were charged at 1C constant current to the cutoff voltage, and then discharged at 1C constant current to the cutoff voltage, for a total of 400 charge-discharge cycles. Battery cycle retention rate = (specific capacity at 400th cycle / specific capacity at 1st cycle) × 100%.

[0119] The lithium batteries in Experiments 2-4 and Comparative Examples 1-4 were subjected to heating safety tests in a heating chamber, and the temperatures at which the batteries caught fire or exploded were recorded. A compression testing machine was used to perform deformation compression tests on the lithium batteries, and the thickness reduction rate of the lithium batteries at the time of fire or explosion was recorded. A higher thickness reduction rate indicates a stronger ability of the lithium battery to withstand compression deformation. A needle penetration testing machine was used to perform needle penetration tests on the lithium batteries, and it was observed whether the lithium batteries caught fire or exploded after being punctured. If fire or explosion occurred, the lithium battery failed the needle penetration test; if no fire or explosion occurred, the lithium battery passed the needle penetration test.

[0120] Table 1. Test Results Table

[0121] As shown in Table 1, the gel electrolyte precursor solutions obtained in Examples 2-4 exhibit good homogeneity, laying a solid foundation for the formation of gel electrolytes and the preparation of lithium batteries with gel electrolytes. All of these methods yield gel electrolytes with excellent overall performance and lithium batteries containing gel electrolytes. The gel electrolytes in Examples 2-4 have an ionic conductivity ≥6.9 mS / cm, indicating good electrical conductivity; a limiting oxygen index (LOI) ≥31%, demonstrating good flame retardant properties; and a self-healing efficiency ≥82%, indicating good self-healing performance. The lithium batteries in Examples 2-4 have a cycle retention rate ≥94.5%, indicating good cycle performance. In safety performance tests such as heating, deformation extrusion, and needle penetration, the lithium batteries in Examples 2-4 all demonstrated good safety performance.

[0122] Compared with Experimental Example 2, Comparative Example 1 did not add a phosphourethrindone monomer. The self-healing efficiency and limiting oxygen index (LOI) of the gel electrolyte in Comparative Example 1 were lower than those in Experimental Example 2, indicating that the phosphourethrindone monomer helps to improve the self-healing and flame-retardant properties of the electrolyte. The battery cycle retention rate and safety performance of the lithium battery in Comparative Example 1 were lower than those in Experimental Example 2, indicating that the phosphourethrindone monomer helps to improve the cycle performance and safety performance of the lithium battery.

[0123] Compared to Experimental Example 2, Comparative Example 2 replaced the phosphoureidopyrimidinone monomer with UPy-ethyl methacrylate monomer (UPyMA) and added triphenyl phosphate (TPP) as a small molecule flame retardant to supplement the phosphorus content. The flame-retardant phosphorus element was introduced simply through physical mixing. The self-healing efficiency and limiting oxygen index (LOI) of the gel electrolyte in Comparative Example 2 were lower than those in Experimental Example 2. The cycle performance and safety of the lithium battery in Comparative Example 2 were also weaker than those in Experimental Example 2. This indicates that the phosphoureidopyrimidinone monomer of the present invention integrates the dynamic self-healing unit and the flame-retardant unit into the monomer from the molecular source, resulting in stronger flame-retardant and self-healing properties. Simple physical doping cannot achieve the same effect.

[0124] Compared to Experimental Example 2, Comparative Example 3 did not use isothermal gradient pressure curing, but instead used constant high pressure for curing. Compared to Experimental Example 2, the ionic conductivity, limiting oxygen index (LOI), and self-healing efficiency of the gel electrolyte in Comparative Example 3 decreased, and the cycle performance and safety of the lithium battery decreased. This indicates that the isothermal gradient pressure curing method can improve the conductivity of the gel electrolyte of the present invention, and isothermal gradient pressure curing can regulate the formation of the dual-network structure of the gel electrolyte, thereby enhancing the flame retardant and self-healing properties of the gel electrolyte.

[0125] Compared to Experimental Example 2, Comparative Example 4 shortened the holding time under the second stage pressure during isothermal gradient pressurization. Since the dual-network structure of the gel electrolyte mainly forms in the second stage of isothermal gradient pressurization, the physical adsorption of the gel electrolyte to the electrode also primarily occurs in the second stage. The ionic conductivity, limiting oxygen index (LOI), and self-healing efficiency of the gel electrolyte in Comparative Example 4 were lower than those in Experimental Example 2; the cycle retention rate and thermal stability of the lithium battery were also lower than those in Experimental Example 2. The comparative results indicate that holding the gel electrolyte under the second stage pressure during isothermal gradient pressurization curing for a sufficient time helps improve the conductivity of the gel electrolyte of this invention, promotes the formation of the dual-network structure of the gel electrolyte, and improves the cycle performance and safety of the lithium battery.

[0126] In summary, the gel electrolyte provided by this invention has good ionic conductivity, flame retardancy, and self-healing properties; the lithium battery has excellent cycle performance and safety.

[0127] The foregoing has provided a detailed description of a phosphorus-containing ureapyrimidinone monomer, its preparation method, gel electrolyte, and lithium battery disclosed in the embodiments of the present invention. Specific examples have been used to illustrate the principles and implementation methods of the present invention. The descriptions of the above embodiments are only for the purpose of helping to understand the method and core ideas of the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation methods and application scope based on the ideas of the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention. Any modifications, equivalent substitutions, and improvements made within the principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A phosphourethrinone monomer, characterized in that, The general structural formula of the phosphorus-containing ureidopyrimidinone monomer is shown in formula [1]: Formula [1] In formula [1], R1 and R2 are C1~C4 alkyl groups, and R1 and R2 can be the same; R3 is an α-hydroxy saturated alkyl group; R4 is an inert group; and Ar is a phenylene or its alkyl-substituted derivative.

2. A method for preparing a phosphoureidopyrimidinone monomer, characterized in that, Includes the following steps: Phosphorus-containing isocyanate intermediates are generated by reacting phosphorus-containing hydroxyl compounds with diisocyanate compounds. The phosphorus-containing isocyanate intermediate reacts with a 2-amino-4-hydroxypyrimidine derivative to generate a ureidation intermediate; as well as The ureation intermediate is reacted with an acrylic anhydride compound to obtain the phosphorus-containing ureidopyrimidinone monomer; the phosphorus-containing ureidopyrimidinone monomer has the general formula as described in claim 1.

3. The method for preparing a phosphoureidopyrimidinone monomer as described in claim 2, characterized in that, The phosphorus-containing hydroxyl compound includes any one or a combination of two of (1-hydroxyethyl)phosphonate dimethyl ester and (hydroxymethyl)phosphonate diisopropyl ester; and / or, the diisocyanate compound includes one or a combination of toluene 2,6-diisocyanate, toluene-2,4-diisocyanate, 1,3-diisophenyl cyanate, terephthalic diisocyanate, and toluene-2,6-diisocyanate.

4. The method for preparing a phosphoureidopyrimidinone monomer as described in claim 2, characterized in that, The 2-amino-4-hydroxypyrimidine derivatives include one or more combinations of 2-amino-4-hydroxy-6-methylpyrimidine, 2-amino-4-hydroxy-5-methoxypyrimidine, 2-amino-4-hydroxy-5-bromopyrimidine, and 2-amino-4-hydroxy-6-ethylpyrimidine; and / or the acrylic anhydride compounds include one or more combinations of methacrylic anhydride, dimethacrylic anhydride, ethylacrylic anhydride, and phenylacrylic anhydride.

5. The method for preparing a phosphoureidopyrimidinone monomer as described in claim 2, characterized in that, The process of reacting a phosphorus-containing hydroxyl compound with a diisocyanate compound to generate a phosphorus-containing isocyanate intermediate specifically includes the following steps: At 0-5℃, the phosphorus-containing hydroxyl compound is dissolved in the first solvent under a protective atmosphere, a catalyst is added, and the diisocyanate compound is added dropwise at a rate of 1-5 drops per second to carry out the reaction; after the addition is completed, the temperature is raised to 40-60℃, and the reaction is continued to be stirred for 2-4 hours to obtain the phosphorus-containing isocyanate intermediate.

6. The method for preparing a phosphorus-containing ureapyridinone monomer as described in claim 5, characterized in that, The molar ratio of the phosphorus-containing hydroxyl compound to the diisocyanate compound is 1:(1-1.2); the first solvent is anhydrous tetrahydrofuran; and the catalyst is dibutyltin dilaurate.

7. The method for preparing a phosphorus-containing ureapyridinone monomer as described in claim 2, characterized in that, The reaction of the phosphorus-containing isocyanate intermediate with a 2-amino-4-hydroxypyrimidine derivative to generate a ureaized intermediate specifically includes the following steps: The phosphorus-containing isocyanate intermediate was dissolved in a second solvent, and a 2-amino-4-hydroxypyrimidine derivative was added under a protective atmosphere; the temperature was raised to 85-100℃, and the reaction was stirred for 1-3 hours to obtain the ureated intermediate; The molar ratio of the phosphorus-containing isocyanate intermediate to the 2-amino-4-hydroxypyrimidine derivative is 1:(1-1.1); the second solvent is anhydrous dimethyl sulfoxide.

8. The method for preparing a phosphoureidopyrimidinone monomer as described in claim 2, characterized in that, The reaction of the ureation intermediate with an acrylic anhydride compound to obtain the phosphorus-containing ureidopyrimidinone monomer specifically includes the following steps: At 0-5℃, the urea intermediate is dissolved in a third solvent under a protective atmosphere. An inhibitor and an organic base are added to form a reaction system. An acrylic anhydride compound is added dropwise at a rate of 1-5 drops per second to carry out the reaction. After the addition is complete, the reaction is stirred for 20-40 minutes. The temperature is raised to room temperature and the reaction is continued for 2-4 hours to obtain a phosphorus-containing ureidopyrimidinone monomer. The molar ratio of the ureaized intermediate to the acrylic anhydride compound is 1:(1.2-1.5), and the third solvent is anhydrous dichloromethane.

9. A gel electrolyte, characterized in that, The gel electrolyte is prepared by curing electrolyte raw materials through a constant temperature gradient pressure, wherein the electrolyte raw materials include the phosphorus-containing ureidopyrimidinone monomer as described in claim 1; the gel electrolyte has a dual-network structure of a chemically cross-linked network with covalent bonds and a physically cross-linked network with four hydrogen bonds.

10. A lithium battery, characterized in that, The lithium battery includes the gel electrolyte as described in claim 9.

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