An oligomer containing ester groups and ether bonds, a preparation method, applications, and a gel battery and a preparation method thereof

Abstract

This invention relates to an oligomer containing ester groups and ether bonds, its preparation method, applications, and a gel battery thereof. The general structural formula of the oligomer is shown in Formula I. This invention also provides a method for preparing the oligomer, specifically by heating and initiating polymerization of a mixture of methyl acrylate, 2-phenoxyethyl acrylate, and polyethylene glycol methyl ether acrylate. This invention also provides the application of the oligomer as an additive in gel batteries. This invention further provides a gel battery and its preparation method, wherein the oligomer containing ester groups and ether bonds is added to the gel electrolyte of the gel battery. This invention provides a novel oligomer for gel batteries; by adding this oligomer, the mechanical stability and electrochemical performance of the gel battery are significantly improved.

Description

Technical Field

[0001] This invention relates to the field of lithium battery technology, specifically to an oligomer containing ester groups and ether bonds, its preparation method, applications, and a gel battery and its preparation method. Background Technology

[0002] In recent years, lithium-ion batteries (LIBs) have attracted widespread attention due to their high energy density, high output voltage, and long cycle life. However, the liquid electrolytes widely used in existing technologies suffer from safety issues such as volatility, leakage, and even explosion, thus limiting their application in electric vehicles. Gel polymer electrolytes (GPEs), with their advantages of preventing liquid leakage, flexibility, and inhibiting lithium dendrite growth, have shown promising development prospects and are expected to become a substitute for liquid electrolytes. Among them, gel electrolytes prepared using polyethylene oxide, polyvinylidene fluoride-hexafluoropropylene, polymethyl methacrylate, polyacrylonitrile, and their derivatives have been extensively studied in recent years. However, the production process of these gel electrolytes requires first preparing the polymer into a film, and then absorbing the electrolyte to form a gel, resulting in drawbacks such as high cost, large solvent loss, and complex manufacturing processes, hindering their large-scale application.

[0003] In existing technologies, there are also methods for preparing gel electrolytes through in-situ polymerization. The specific process involves injecting a liquid electrolyte containing a completely soluble monomer / initiator into the battery cell, followed by thermal initiation to form a gel electrolyte. Polymer gel electrolytes, including polyacrylonitrile, polymethyl methacrylate, and polyethyl cyanoacrylate, can all be prepared through in-situ polymerization. For example, existing literature reports the use of poly(ethylene glycol) diacrylate and ethoxytrimethylolpropane triacrylate as monomers, and azobisisobutyronitrile as an initiator, to prepare a gel electrolyte with a conductivity of 0.56 mS / cm through in-situ polymerization. This gel electrolyte can effectively inhibit the growth of lithium dendrites. However, in practical applications, it was found that the cross-linking of this gel electrolyte system was too high, resulting in poor mechanical stability and easy breakage. Existing literature also reports the successful preparation of a gel electrolyte with a conductivity of 8.81 × 10⁻³ S / cm by using polyethylene glycol diacrylate as a monomer, azobisisobutyronitrile as an initiator, and adding cellulose acetate as an additive. During the preparation of this gel electrolyte, it was found that the polar groups on cellulose acetate can promote the dissolution of lithium salts and improve the thermal stability of the system. However, in actual preparation, it was discovered that due to the poor solubility of cellulose acetate and the unstable hydroxyl groups, side reactions are easily generated, thus limiting its application. Therefore, developing a gel electrolyte system with high mechanical strength, good electrochemical performance, and adaptability to current liquid battery manufacturing processes is a pressing technical problem that the industry needs to solve. Summary of the Invention

[0004] One objective of this invention is to provide an oligomer containing ester groups and ether bonds, its preparation method, and its application, so as to provide a new oligomer for gel lithium batteries; another objective is to provide a gel battery and its preparation method to solve the problems of poor mechanical stability and electrochemical performance of gel electrolytes in existing gel lithium batteries.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] An oligomer containing ester groups and ether bonds, with the general structural formula shown in Formula I:

[0007]

[0008] Where m is selected from integers between 1 and 10, n is selected from integers between 1 and 100, o is selected from integers between 1 and 100, and p is selected from integers between 0 and 100.

[0009] Preferably, the oligomer is obtained by terpolymerization of methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate.

[0010] This invention also provides a method for preparing oligomers containing ester groups and ether bonds as described herein, comprising the following steps:

[0011] The oligomer was prepared by heating a mixture of methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate to initiate polymerization.

[0012] The reaction formula is:

[0013]

[0014] Based on the above technical means, oligomers containing ester groups and ether bonds are obtained by ternary polymerization using three monomers with the same acrylate groups. Since the acrylate groups on the three monomers are the same, the reactivity of the three monomers is similar, and under heating and initiator conditions, it has the advantage of low polymerization difficulty.

[0015] Preferably, it includes the following steps:

[0016] S1. Add methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate to an organic solvent to obtain mixture A;

[0017] S2. Heat mixture A to 40℃~77.2℃, add initiator, continue the reaction for 10~150min, and cool to obtain mixture B;

[0018] S3. Add an inorganic solvent to mixture B to separate the mixture into layers. Take the organic phase and remove the organic solvent from the organic phase. Dry the mixture to obtain an oligomer containing ester groups and ether bonds.

[0019] Preferably, the initiator is selected from one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, and benzoyl peroxide.

[0020] Preferably, the amount of the initiator added is 0.1 wt% to 1 wt%.

[0021] The initiator is added at a mass percentage of 0.1 wt% to 1 wt% of the total mass of methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate.

[0022] Preferably, the organic solvent is ethyl acetate, and the sum of ethyl acetate and the three monomers is 10-20:1 in mL:g; the inorganic solvent is water.

[0023] The present invention also provides the use of oligomers containing ester groups and ether bonds as described herein, wherein the oligomers containing ester groups and ether bonds are used as additives in gel batteries.

[0024] This invention also provides a method for preparing a gel battery, comprising the following steps:

[0025] S1. Methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate are added to an organic solvent, heated to 40℃~77.2℃, an initiator is added, and the reaction is continued for 10~150 min. After cooling, an inorganic solvent is added to separate the system into layers. The organic phase is taken out and the organic solvent in the organic phase is removed. The product is dried to obtain the first product.

[0026] S2. Add 1wt% to 20wt% of the polymer monomer, 0.1wt% to 5wt% of the first product and 0.1wt% to 1wt% of the initiator to the electrolyte in sequence, and mix to obtain a precursor solution;

[0027] S3. Inject the precursor solution into the soft-pack battery cell, and after encapsulation, react at a temperature of 50℃~80℃ for 1~10h to solidify in situ and form a gel electrolyte.

[0028] S4. Pre-charge the soft-pack cell that forms the gel electrolyte to obtain a gel battery;

[0029] The monomers used in the polymerization are olefin monomers, and the electrolyte includes lithium salts and organic solvents.

[0030] Based on the above technical means, oligomers containing ester groups and ether bonds are added to the electrolyte as additives. Because the oligomers are rich in ester groups (-COOR) and ether bonds (COC), they have good compatibility with the electrolyte system. Under heating and initiator conditions, the polymer monomers form highly cross-linked polymers, and the oligomers containing ester groups and ether bonds easily form semi-interpenetrating networks with the highly cross-linked polymers, thereby enhancing the mechanical stability of the gel electrolyte system. At the same time, the oligomers containing ester groups and ether bonds themselves contain benzene ring structures. The π-π stacking effect generated by the benzene ring structure can further enhance the mechanical and thermal stability of the gel electrolyte system, thereby adapting to the expansion of the electrode and improving cycle performance.

[0031] Preferably, the olefin monomer is selected from one or more of methyl acrylate, methyl methacrylate, vinyl sulfite, pentaerythritol tetraacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, and bis(trimethylolpropane)tetraacrylate.

[0032] The initiator is selected from one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, and benzoyl peroxide.

[0033] Preferably, the lithium salt is selected from one or more of LiPF6, LiClO4, LiAsF6, LiBF4, LiCH3SO3, LiCF3SO3, LiBOB, LiDFOB, LiN(FSO2)2, LiN(CF3SO2)2, LiTFSI and LiFSI, and the concentration of the lithium salt is 0.5 to 6 mol / L.

[0034] The organic solvent in the electrolyte is selected from one or more of carbonates, ethers, carboxylic acid esters, phosphate esters, and fluorinated solvents.

[0035] Preferably, the carbonate is selected from cyclic carbonates and / or chain carbonate compounds;

[0036] The ethers are selected from one or more of tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,3-dioxocyclopentane, dimethoxymethane, 1,2-dimethoxyethylene, and diethylene glycol dimethyl ether;

[0037] The carboxylic acid esters are selected from one or more of methyl formate, ethyl formate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl acetate;

[0038] The phosphate esters are selected from one or more of trimethyl phosphite, triphenyl phosphite, and triphosphite;

[0039] The fluorinated solvent is selected from one or more of fluoroethylene carbonate, ethyl-2,2,2-trifluoroethyl carbonate, propylene trifluorocarbonate, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

[0040] Preferably, the cyclic carbonate compound is selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and butylene carbonate;

[0041] The chain carbonate compound is preferably one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, methyl ethyl carbonate (EMC), and carbonate derivatives synthesized from straight-chain or branched aliphatic monools with 3 to 8 carbon atoms and carbon dioxide.

[0042] The beneficial effects of this invention are:

[0043] 1) The oligomers containing ester groups and ether bonds provided by this invention and their preparation method are obtained by ternary polymerization of three monomers with the same acrylate groups. Since the three monomers have similar reactivity, they have the advantage of low polymerization difficulty under heating and initiator conditions. The three monomer raw materials are widely available. The preparation method has the advantages of low preparation cost, simple operation, mild conditions and high conversion rate. Moreover, the prepared oligomers are rich in ester groups and ether bonds. When used as an additive in the preparation of gel electrolyte in gel batteries, it can effectively improve the mechanical properties of gel batteries and provide a new direction for the development of gel batteries.

[0044] 2) The gel battery and its preparation method provided by this invention involve adding oligomers containing ester groups and ether bonds as additives to the electrolyte. Because the oligomers are rich in ester groups (-COOR) and ether bonds (COC), they have good compatibility with the electrolyte system. Under heating and initiator conditions, the monomers form highly cross-linked polymers, and the oligomers containing ester groups and ether bonds easily form a semi-interpenetrating network with these highly cross-linked polymers, thereby enhancing the mechanical stability of the gel electrolyte system. Simultaneously, the oligomers containing ester groups and ether bonds themselves contain benzene ring structures. The π-π stacking effect generated by the benzene ring structure further enhances the mechanical and thermal stability of the gel electrolyte system, thus adapting to electrode expansion and improving cycle performance. The resulting gel battery achieves an ionic conductivity of 3.9 x 10⁻⁶. -3 With an S / cm or higher, an electrochemical window of around 4.5V, and a capacity retention of over 75% after 500 cycles at 25℃ and 1C / 1C, it exhibits excellent electrochemical performance and has significant potential for widespread application in the field of gel battery technology. Attached Figure Description

[0045] Figure 1The graph shows the test results of the electrochemical window of the gel battery prepared in Example 6;

[0046] Figure 2 The graph shows the test results of the electrochemical window of the gel battery prepared in Example 7;

[0047] Figure 3 This is a graph showing the test results of the electrochemical window of the gel battery prepared in Example 8;

[0048] Figure 4 This is a graph showing the test results of the electrochemical window of the gel battery prepared in Example 9;

[0049] Figure 5 This is a graph showing the test results of the electrochemical window of the gel battery prepared in Example 10;

[0050] Figure 6 The graph shows the results of the room temperature cycle charge-discharge test of the gel battery prepared in Example 6.

[0051] Figure 7 The graph shows the results of the room temperature cycle charge-discharge test of the gel battery prepared in Example 7.

[0052] Figure 8 The graph shows the results of the room temperature cycle charge-discharge test of the gel battery prepared in Example 8;

[0053] Figure 9 The graph shows the results of the room temperature cycle charge-discharge test of the gel battery prepared in Example 9;

[0054] Figure 10 The graph shows the results of the room temperature cycle charge-discharge test of the gel battery prepared in Example 10.

[0055] Figure 11 The graph shows the results of room temperature cycle charge-discharge tests on the gel battery prepared in Comparative Example 1. Detailed Implementation

[0056] The embodiments of the present invention will be described below with reference to the accompanying drawings and preferred embodiments. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can also be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be understood that the preferred embodiments are only for illustrating the present invention and not for limiting the scope of protection of the present invention.

[0057] It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Therefore, the drawings only show the components related to the present invention and are not drawn according to the actual number, shape and size of the components in the actual implementation. In the actual implementation, the form, quantity and proportion of each component can be arbitrarily changed, and the layout of the components may also be more complex.

[0058] Example 1

[0059] A method for preparing an oligomer containing ester groups and ether bonds, comprising the following steps:

[0060] S1. Add 700 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer and condenser. Then add 8.609 g of methyl acrylate, 19.221 g of 2-phenoxyethyl acrylate and 20 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 480 g / mol to the three-necked flask and stir until homogeneous to obtain mixture A.

[0061] S2. Heat mixture A to 75°C, stir at high speed and slowly add azobisisobutyronitrile into the flask. After reacting for 20 minutes, stop heating and cool to room temperature to obtain mixture B.

[0062] S3. Add 700 mL of deionized water to the flask, stir and let stand. Remove the lower aqueous phase through a separatory funnel, retain the upper organic phase, and repeat the above operation three times. Then remove the solvent from the organic phase by rotary evaporation, and finally dry under vacuum to obtain oligomers containing ester groups and ether bonds.

[0063] Example 2

[0064] A method for preparing an oligomer containing ester groups and ether bonds, comprising the following steps;

[0065] S1. Add 200 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer and condenser. Then add 0.4035 g of methyl acrylate, 19.221 g of 2-phenoxyethyl acrylate and 2 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 2000 g / mol to the three-necked flask and stir until homogeneous to obtain mixture A.

[0066] S2. Heat mixture A to 55°C, stir at high speed and slowly add azobisisoheptanenitrile to the flask. After reacting for 30 minutes, stop heating and cool to room temperature to obtain mixture B.

[0067] S3. Add 200 mL of deionized water to the flask, stir and let stand. Remove the lower aqueous phase through a separatory funnel, retain the upper organic phase, and repeat the above operation three times. Then remove the solvent from the organic phase by rotary evaporation, and finally dry under vacuum to obtain oligomers containing ester groups and ether bonds.

[0068] Example 3

[0069] A method for preparing an oligomer containing ester groups and ether bonds, comprising the following steps:

[0070] S1. Add 150 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer and condenser. Then add 0.861 g of methyl acrylate, 0.961 g of 2-phenoxyethyl acrylate and 1 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 5000 g / mol to the three-necked flask and stir until homogeneous to obtain mixture A.

[0071] S2. Heat mixture A to 77°C, stir at high speed and slowly add azobisisoheptanenitrile to the flask. After reacting for 150 min, stop heating and cool to room temperature to obtain mixture B.

[0072] S3. Add 150 mL of deionized water to the flask, stir and let stand. Remove the lower aqueous phase through a separatory funnel, retain the upper organic phase, and repeat the above operation three times. Then remove the solvent from the organic phase by rotary evaporation, and finally dry under vacuum to obtain oligomers containing ester groups and ether bonds.

[0073] Example 4

[0074] A method for preparing an oligomer containing ester groups and ether bonds, comprising the following steps:

[0075] S1. Add 300 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer and condenser. Then add 0.807 g of methyl acrylate, 1.9221 g of 2-phenoxyethyl acrylate and 2 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 5000 g / mol to the three-necked flask and stir until homogeneous to obtain mixture A.

[0076] S2. Heat mixture A to 70°C, stir at high speed and slowly add dimethyl azobisisobutyrate into the flask. After reacting for 60 min, stop heating and cool to room temperature to obtain mixture B.

[0077] S3. Add 300 mL of deionized water to the flask, stir and let stand. Remove the lower aqueous phase through a separatory funnel, retain the upper organic phase, and repeat the above operation three times. Then remove the solvent from the organic phase by rotary evaporation, and finally dry under vacuum to obtain oligomers containing ester groups and ether bonds.

[0078] Example 5

[0079] A method for preparing an oligomer containing ester groups and ether bonds, comprising the following steps:

[0080] S1. Add 350 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer and condenser. Then add 1.009 g of methyl acrylate, 2.4026 g of 2-phenoxyethyl acrylate and 2.5 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 3500 g / mol to the three-necked flask and stir until homogeneous to obtain mixture A.

[0081] S2. Heat mixture A to 65°C, stir at high speed and slowly add benzoyl peroxide to the flask. After reacting for 50 minutes, stop heating and cool to room temperature to obtain mixture B.

[0082] S3. Add 350 mL of deionized water to the flask, stir and let stand. Remove the lower aqueous phase through a separatory funnel, retain the upper organic phase, and repeat the above operation three times. Then remove the solvent from the organic phase by rotary evaporation, and finally dry under vacuum to obtain oligomers containing ester groups and ether bonds.

[0083] Example 6

[0084] A method for preparing a gel battery includes the following steps:

[0085] S1. Add 700 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer, and condenser. Then add 8.609 g of methyl acrylate, 19.221 g of 2-phenoxyethyl acrylate, and 20 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 480 g / mol to the three-necked flask. After stirring evenly, heat to 75 °C, stir at high speed, and slowly add azobisisobutyronitrile to the flask. After reacting for 20 min, stop heating and cool to room temperature. Add 700 mL of deionized water to the flask, stir, and let stand. Remove the lower aqueous phase through a separatory funnel, retaining the upper organic phase. Repeat the process of adding 700 mL of deionized water, stirring, letting stand, and separating the liquid twice. Then remove the solvent from the organic phase by rotary evaporation. Finally, dry under vacuum to obtain the first product.

[0086] S2. Add 3 wt% pentaerythritol tetraacrylate to the electrolyte [1M LiTFSI in EC:EMC=1:1(V:V)], stir until homogeneous, then add 2 wt% of the first product, and then add 0.5 wt% azobisisobutyronitrile, stir until homogeneous to obtain the precursor solution.

[0087] S3. Inject the precursor solution into the soft-pack battery cell, encapsulate it, and heat it in an oven at 75°C for 5 hours to solidify it in situ and form a gel electrolyte.

[0088] S4. The soft-pack cell that forms the gel electrolyte is pre-charged and formed to obtain a gel battery.

[0089] Example 7

[0090] A method for preparing a gel battery includes the following steps:

[0091] S1. Add 200 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer, and condenser. Then add 0.4035 g of methyl acrylate, 19.221 g of 2-phenoxyethyl acrylate, and 2 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 2000 g / mol to the three-necked flask. After stirring evenly, heat to 55 °C, stir at high speed, and slowly add azobisisobutyronitrile to the flask. After reacting for 30 min, stop heating and cool to room temperature. Add 200 mL of deionized water to the flask, stir, and let stand. Remove the lower aqueous phase through a separatory funnel, retaining the upper organic phase. Repeat the process of adding 200 mL of deionized water, stirring, letting stand, and separating the liquid twice. Then remove the solvent from the organic phase by rotary evaporation. Finally, dry under vacuum to obtain the first product.

[0092] S2. Add 4 wt% of trimethylolpropane triacrylate to the electrolyte [1M LiFSI in EC:DEC:EMC=1:1:1(V:V:V)], stir until homogeneous, then add 3 wt% of the first product, and then add 0.2 wt% of dimethyl azobisisobutyrate, stir until homogeneous to obtain the precursor solution.

[0093] S3. Inject the precursor solution into the soft-pack battery cell, encapsulate it, and heat it in an oven at 65°C for 8 hours to solidify it in situ and form a gel electrolyte.

[0094] S4. The soft-pack cell that forms the gel electrolyte is pre-charged and formed to obtain a gel battery.

[0095] Example 8

[0096] A method for preparing a gel battery includes the following steps:

[0097] S1. Add 150 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer, and condenser. Then add 0.861 g of methyl acrylate, 0.961 g of 2-phenoxyethyl acrylate, and 1 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 5000 g / mol to the three-necked flask. After stirring evenly, heat to 77 °C, stir at high speed, and slowly add azobisisobutyronitrile to the flask. After reacting for 150 min, stop heating and cool to room temperature. Add 150 mL of deionized water to the flask, stir, and let stand. Remove the lower aqueous phase through a separatory funnel, retaining the upper organic phase. Repeat the process of adding 150 mL of deionized water, stirring, letting stand, and separating the liquid twice. Then remove the solvent from the organic phase by rotary evaporation. Finally, dry under vacuum to obtain the first product.

[0098] S2. Add 5 wt% of the mixed monomers to the electrolyte [1M LiFSI in EC:DEC:EMC = 1:1:1 (V:V:V)], stir until homogeneous, then add 4 wt% of the first product, and then add 0.3 wt% of benzoyl peroxide, stir until homogeneous to obtain the precursor solution; wherein, the mixed monomers are composed of vinyl sulfite and ethoxytrimethylolpropane triacrylate in a mass ratio of 4:1;

[0099] S3. Inject the precursor solution into the soft-pack battery cell, encapsulate it, and heat it in an oven at 73°C for 10 hours to solidify it in situ and form a gel electrolyte.

[0100] S4. The soft-pack cell that forms the gel electrolyte is pre-charged and formed to obtain a gel battery.

[0101] Example 9

[0102] A method for preparing a gel battery includes the following steps:

[0103] S1. Add 300 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer, and condenser. Then add 0.807 g of methyl acrylate, 1.9221 g of 2-phenoxyethyl acrylate, and 2 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 5000 g / mol to the three-necked flask. After stirring evenly, heat to 70 °C, stir at high speed, and slowly add dimethyl azobisisobutyrate to the flask. After reacting for 60 min, stop heating and cool to room temperature. Add 300 mL of deionized water to the flask, stir, and let stand. Remove the lower aqueous phase through a separatory funnel, retaining the upper organic phase. Repeat the above operation three times. Then remove the solvent from the organic phase by rotary evaporation. Finally, vacuum dry to obtain the first product.

[0104] S2. Add 5 wt% of the mixed monomers to the electrolyte [1M LiTFSI in EC:EMC = 1:1 (V:V)], stir until homogeneous, then add 3.5 wt% of the first product, stir until homogeneous to obtain the precursor solution; wherein, the mixed monomers are composed of methyl methacrylate and trimethylolpropane triacrylate in a mass ratio of 4:1.

[0105] S3. Inject the precursor solution into the soft-pack battery cell, encapsulate it, and heat it in an oven at 75°C for 5 hours to solidify it in situ and form a gel electrolyte.

[0106] S4. The soft-pack cell that forms the gel electrolyte is pre-charged and formed to obtain a gel battery.

[0107] Example 10

[0108] A method for preparing a gel battery includes the following steps:

[0109] S1. Add 350 mL of ethyl acetate to a three-necked flask equipped with a thermometer, mechanical stirrer, and condenser. Then add 1.009 g of methyl acrylate, 2.4026 g of 2-phenoxyethyl acrylate, and 2.5 g of polyethylene glycol methyl ether acrylate with an average molecular weight of 3500 g / mol to the three-necked flask. After stirring evenly, heat to 65 °C, stir at high speed, and slowly add benzoyl peroxide to the flask. After reacting for 50 min, stop heating and cool to room temperature. Add 350 mL of deionized water to the flask, stir, and let stand. Remove the lower aqueous phase through a separatory funnel, retaining the upper organic phase. Repeat the above operation three times. Then remove the solvent from the organic phase by rotary evaporation. Finally, vacuum dry to obtain the first product.

[0110] S2. Add 5 wt% of the mixed monomers to the electrolyte [1M LiFSI in EC:DEC:EMC = 1:1:1 (V:V:V)], stir until homogeneous, then add 1.5 wt% of the first product, followed by 0.1 wt% of azobisisobutyronitrile and 0.1 wt% of benzoyl peroxide, and stir until homogeneous to obtain the precursor solution; wherein, the mixed monomers are composed of methyl acrylate, pentaerythritol tetraacrylate and bis(trimethylolpropane) tetraacrylate in a mass ratio of 1:2:2;

[0111] S3. Inject the precursor solution into the soft-pack battery cell, encapsulate it, and heat it in an oven at 75°C for 6 hours to solidify it in situ and form a gel electrolyte.

[0112] S4. The soft-pack cell that forms the gel electrolyte is pre-charged and formed to obtain a gel battery.

[0113] Comparative Example 1

[0114] A method for preparing a gel battery includes the following steps:

[0115] S1. Add 3 wt% pentaerythritol tetraacrylate to the electrolyte [1M LiTFSI in EC:EMC=1:1(V:V)], stir until homogeneous, then add 0.5 wt% azobisisobutyronitrile, stir until homogeneous to obtain the precursor solution;

[0116] S2. Inject the precursor solution into the soft-pack battery cell, encapsulate it, and heat it in an oven at 75°C for 5 hours to solidify it in situ and form a gel electrolyte.

[0117] S3. The soft-pack cell that forms the gel electrolyte is pre-charged and formed to obtain a gel battery.

[0118] Detection and Analysis

[0119] 1) The gel electrolytes formed by in-situ curing in Examples 6 to 10 and Control Example 1 were prepared into strips of gel with a diameter of 40 mm × 8 mm × 0.5 mm by curing in a silicone rubber mold. Then, tensile tests were performed on each strip using a tensile testing machine to determine their tensile strength. The results are shown in Table 1.

[0120] Table 1. Tensile strength test results of gel electrolytes

[0121] Tensile strength (kPa) Example 6 21.4 Example 7 28.7 Example 8 39.2 Example 9 36.2 Example 10 34.9 Comparative Example 1 1.7

[0122] As can be seen from the comparative analysis in Table 1, the gel electrolytes prepared in Examples 6 to 10, i.e. gel electrolytes with added oligomers containing ester groups and ether bonds, showed a significant increase in tensile strength compared to gel electrolytes without added oligomers. This proves that the oligomers containing ester groups and ether bonds in this application can significantly improve the mechanical stability of gel batteries.

[0123] 2) The gel batteries prepared in Examples 6 to 10 and Control Example 1 were subjected to ionic conductivity and electrochemical window tests, and charge-discharge tests were performed using constant current / constant voltage charging / constant current discharging at 1C / 1C rates. The results are shown in Table 2 and... Figures 1 to 11 As shown:

[0124] Table 2. Test results of ionic conductivity, electrochemical window, and room temperature cycling performance of gel batteries.

[0125]

[0126] Through Table 2 and Figures 1 to 10 Analysis shows that the ionic conductivity of the gel batteries prepared in Examples 6 to 10 is all within the range of 3.9 x 10⁻⁶. -3 With an S / cm above 1, the electrochemical window is around 4.5V, and the capacity retention rate is above 77% after 500 cycles at 25℃ and 1C / 1C, it exhibits excellent electrochemical performance and has promotion and application value in the field of gel battery technology.

[0127] The above embodiments are merely preferred embodiments provided to fully illustrate the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. An application of an oligomer containing ester groups and ether bonds, characterized in that, The oligomers containing ester groups and ether bonds are used as additives in gel batteries to enhance the mechanical stability of the gel batteries. The oligomers are obtained by ternary copolymerization of methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate.

2. The application of the oligomer containing ester groups and ether bonds as described in claim 1, characterized in that, The preparation of the oligomer includes the following steps: The oligomer was prepared by heating a mixture of methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate to initiate polymerization. The reaction formula is: 。 3. The application of the oligomer containing ester groups and ether bonds according to claim 2, characterized in that, The preparation of the oligomer includes the following steps: S1. Add methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate to an organic solvent to obtain mixture A; S2. Heat mixture A to 40℃~77.2℃, add initiator, continue the reaction for 10~150min, and cool to obtain mixture B; S3. Add an inorganic solvent to mixture B to separate the mixture into layers. Take the organic phase and remove the organic solvent from the organic phase. Dry the mixture to obtain an oligomer containing ester groups and ether bonds.

4. The application of the oligomer containing ester groups and ether bonds according to claim 3, characterized in that, The initiator is selected from one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, and benzoyl peroxide.

5. The application of the oligomer containing ester groups and ether bonds according to claim 4, characterized in that, The amount of the initiator added is 0.1wt% to 1wt%.

6. The application of the oligomer containing ester groups and ether bonds according to claim 3, characterized in that, The organic solvent is ethyl acetate, and the sum of ethyl acetate and the three monomers is 10~20:1 in mL:g; the inorganic solvent is water.

7. A method for preparing a gel battery, characterized in that, Includes the following steps: S1. Methyl acrylate, 2-phenoxyethyl acrylate and polyethylene glycol methyl ether acrylate are added to an organic solvent, heated to 40℃~77.2℃, an initiator is added, and the reaction is continued for 10~150 min. After cooling, an inorganic solvent is added to separate the system into layers. The organic phase is taken out and the organic solvent in the organic phase is removed. The product is dried to obtain the first product. S2. Add 1wt%~20wt% of the polymer monomer, 0.1wt%~5wt% of the first product and 0.1wt%~1wt% of the initiator to the electrolyte in sequence, and mix to obtain a precursor solution; S3. Inject the precursor solution into the soft-pack battery cell, and after encapsulation, react at a temperature of 50℃~80℃ for 1~10h to solidify in situ and form a gel electrolyte. S4. Pre-charge the soft-pack cell that forms the gel electrolyte to obtain a gel battery; The monomers used in the polymerization are olefin monomers, and the electrolyte includes lithium salts and organic solvents.

8. The method for preparing a gel battery according to claim 7, characterized in that, The olefin monomer is selected from one or more of methyl acrylate, methyl methacrylate, vinyl sulfite, pentaerythritol tetraacrylate, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, ethoxylated trimethylolpropane triacrylate, trimethylolpropane triacrylate, and bis(trimethylolpropane)tetraacrylate. The initiator is selected from one or more of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, and benzoyl peroxide.

9. The method for preparing a gel battery according to claim 8, characterized in that, The lithium salt is selected from one or more of LiPF6, LiClO4, LiAsF6, LiBF4, LiCH3SO3, LiCF3SO3, LiBOB, LiDFOB, LiN(FSO2)2, LiN(CF3SO2)2, LiTFSI and LiFSI, and the concentration of the lithium salt is 0.5~6 mol / L; The organic solvent in the electrolyte is selected from one or more of carbonates, ethers, carboxylic acid esters, phosphate esters, and fluorinated solvents.

10. The method for preparing a gel battery according to claim 9, characterized in that, The carbonates are selected from cyclic carbonates and / or chain carbonate compounds; The ethers are selected from one or more of tetrahydrofuran (THF), 2-methyltetrahydrofuran, 1,3-dioxocyclopentane, dimethoxymethane, 1,2-dimethoxyethylene, and diethylene glycol dimethyl ether; The carboxylic acid esters are selected from one or more of methyl formate, ethyl formate, ethyl propionate, propyl propionate, methyl butyrate, and ethyl acetate; The phosphate esters are selected from one or more of trimethyl phosphite, triphenyl phosphite, and triphosphite; The fluorinated solvent is selected from one or more of fluoroethylene carbonate, ethyl-2,2,2-trifluoroethyl carbonate, propylene trifluorocarbonate, and 1,1,2,2-tetrafluoroethyl-2,2,3,3-tetrafluoropropyl ether.

11. The method for preparing a gel battery according to claim 10, characterized in that, The cyclic carbonate compounds are selected from one or more of ethylene carbonate (EC), propylene carbonate (PC), γ-butyrolactone (GBL), and butylene carbonate; the chain carbonate compounds are selected from one or more of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate, methyl ethyl carbonate (EMC), and carbonate derivatives synthesized from straight-chain or branched aliphatic monools with 3 to 8 carbon atoms and carbon dioxide.

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