Binder for cold pressing process of lithium battery diaphragm and preparation method of binder

Abstract

The invention discloses a binder for a lithium battery diaphragm cold pressing process and a preparation method thereof, and relates to the technical field of lithium battery diaphragm binders, the binder is prepared from the following components: an acid monomer, an amide monomer, a nitrile monomer, an acrylate monomer, an ether bond-containing polyfunctional group monomer, a long side chain hydrocarbon chain monomer, a neutralizer and an initiator. The preparation method comprises the following steps: mixing the binder components, and adding the binder components into deionized water to form a mixed solution; adding an initiator under the protection of nitrogen, and heating for reaction; and after the reaction is finished, adding a neutralizer to adjust the pH value, diluting and vacuumizing to remove residual monomers. The ether bond-containing polyfunctional group monomer is introduced to form a three-dimensional network structure, so that cohesion is reduced, and a dry film is soft and adapts to a 25 DEG C cold pressing process; and meanwhile, a long-side-chain hydrocarbon chain monomer is introduced, so that the compatibility and wettability with the PE / PP diaphragm are improved, and low-energy-consumption cold pressing bonding is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of lithium battery separator adhesive, and particularly to an adhesive for lithium battery separator cold pressing process and a preparation method thereof. BACKGROUND

[0002] Lithium ion battery separator is an important component of the battery, which is used to separate the positive and negative electrodes to prevent short circuit, while allowing electrolyte ions to pass through. In the traditional lithium battery manufacturing process, the separator is usually coated with 1-2 μm polyvinylidene fluoride (PVDF) and polyacrylate (PAA) compounded adhesive, and is hot-pressed to the positive and negative electrode sheets at 80-90℃ and 5-30 tons of pressure to enhance the hardness of the battery, the strength of the separator, the shrinkage performance, reduce the internal resistance and improve the cycle performance. However, the traditional hot pressing process increases the production cost due to high energy consumption, which is difficult to meet the demand of green manufacturing; and the traditional PAA is a linear polymer with high cohesion, and the dry film is hard, which needs high temperature activation for bonding, and cannot realize 25℃ cold pressing. SUMMARY

[0003] To solve the above technical problems, the present application provides an adhesive for lithium battery separator cold pressing process and a preparation method thereof, and the specific technical solution is as follows: An adhesive for lithium battery separator cold pressing process, which is prepared from the following components in percentage by weight: 5-30% of acid monomer, 5-30% of amide monomer, 10-70% of nitrile monomer, 5-30% of acrylic ester monomer, 1-5% of ether bond-containing multifunctional monomer, 1-5% of long side chain hydrocarbon chain monomer, 5-30% of neutralizing agent, and 0.1-2% of initiator.

[0004] Preferably, The acid monomer is selected from at least one of acrylic acid, methacrylic acid, maleic acid, itaconic acid or derivatives thereof anhydride; The amide monomer is selected from at least one of acrylamide, methacrylamide, N-isopropyl acrylamide, N,N-dimethyl acrylamide, N-hydroxymethyl acrylamide; The nitrile monomer is selected from at least one of acrylonitrile, methacrylonitrile, styrylnitrile, fluorinated acrylonitrile, cyanoethyl vinyl ether; The acrylic ester monomer is selected from at least one of methyl methacrylate, (meth)acrylic acid ethyl ester, (meth)acrylic acid hydroxyethyl ester, (meth)acrylic acid isooctyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid glycidyl ester, (meth)acrylic acid lauryl ester; the ether bond-containing multifunctional monomer is at least one of trimethylolpropane diallyl ether, ethoxy ethoxy ethyl acrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glyceryl triacrylate, ethoxylated pentaerythritol tetraacrylate, ethoxylated 1,6-hexanediol diacrylate; the long side chain hydrocarbon chain monomer is at least one of tricyclodecanedimethanol (dimethyl) acrylate, bicyclo pentane (methyl) acrylate, 1-adamantyl acrylate, t-butyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate; the neutralizing agent is at least one of sodium hydroxide, lithium hydroxide, ammonia, ethanolamine, triethanolamine, isobutanolamine; the initiator is at least one of ammonium persulfate, sodium persulfate, potassium persulfate.

[0005] Preferably, further comprising: the high temperature resistant monomer is at least one of N-phenyl maleimide, vinyl trimethoxysilane; the dynamic crosslinking monomer is at least one of a disulfide bond-containing monomer or a Diels-Alder bond-containing monomer.

[0006] Preferably: the high temperature resistant monomer is at least one of N-phenyl maleimide, vinyl trimethoxysilane; the dynamic crosslinking monomer is at least one of a disulfide bond-containing monomer or a Diels-Alder bond-containing monomer.

[0007] Preferably: the disulfide bond-containing monomer is dithiodipropyl acrylate; the Diels-Alder bond-containing monomer is furanyl acrylate.

[0008] The application also provides a preparation method for preparing the binder for the cold pressing process of lithium battery separators as described in any one of the above. a. After mixing the binder component, add deionized water, stir to form a uniform mixture, wherein the binder component includes acid monomer, amide monomer, nitrile monomer, acrylate monomer, ether bond-containing multifunctional monomer and long side chain hydrocarbon chain monomer; b. Under nitrogen protection, add initiator, heat to perform free radical polymerization; c. After the reaction is completed, add a neutralizing agent to adjust the pH value to 6.5-8.0, dilute and vacuum to remove residual monomers.

[0009] Preferably: in the mixing step, the stirring speed is 200-500 rpm, and the solid content of the mixture is 20%-30%; The radical polymerization reaction is carried out at 60-80℃, and the reaction time is 5-15 hours. The vacuum degree of the vacuumizing step is -0.09 MPa.

[0010] Preferably, the nitrile monomer comprises fluoroacrylonitrile and / or cyanoethyl vinyl ether, and the binder component further comprises an imidazolium ionic liquid monomer and an antioxidant monomer, wherein: The imidazolium ionic liquid monomer accounts for 0.5%-3% of the total mass of the binder component, and the preparation process of the imidazolium ionic liquid monomer specifically comprises the following steps: acrylic acid is mixed with 1-ethyl-3-methylimidazolium chloride at a molar ratio of (2.5-3.5):1, dichloromethane solvent and catalyst N,N-dicyclohexyl carbodiimide are added, esterification is carried out at 25-35℃ under nitrogen protection for 5-7 hours, and then purification by extraction is performed to obtain the product. The antioxidant monomer accounts for 0.5%-2% of the total mass of the binder component, and the preparation process of the antioxidant monomer specifically comprises the following steps: 4-hydroxybenzoic acid is mixed with hydroxyethyl acrylate at a molar ratio of (1-1.2):1, toluene solvent and catalyst p-toluenesulfonic acid are added, esterification is carried out at 95-105℃ under nitrogen protection for 3-5 hours, and then purification by distillation is performed to obtain the product.

[0011] Preferably: The nitrile monomer comprises vinyl triethoxysilane modified acrylonitrile, and the preparation process specifically comprises the following steps: acrylonitrile is mixed with vinyl triethoxysilane at a molar ratio of (5-10):1, toluene solvent and initiator azobisisobutyronitrile are added, reaction is carried out at 60-80℃ under nitrogen protection for 4-6 hours, and then radical copolymerization is performed to obtain the product. And / or the acrylate monomer comprises 4-vinylpyridine modified methyl methacrylate, and the preparation process specifically comprises the following steps: methyl methacrylate is mixed with 4-vinylpyridine at a molar ratio of (3-5):1, catalyst p-toluenesulfonic acid and polymerization inhibitor hydroquinone are added, and then ester exchange reaction is carried out at 100-120℃ under nitrogen protection for 3-5 hours to obtain the product.

[0012] Preferably, the long side chain hydrocarbon chain monomer comprises phosphonic acid modified tricyclodecane dimethylol acrylate, and the preparation process specifically comprises the following steps: tricyclodecane dimethylol acrylate is mixed with dimethyl phosphonic acid at a molar ratio of (1.5-2.5):1, dichloromethane solvent and catalyst N,N-dicyclohexyl carbodiimide are added, esterification is carried out at 25-35℃ under nitrogen protection for 5-7 hours, and then purification by extraction is performed to obtain the product.

[0013] The binder for the cold pressing process of lithium battery separators provided by the present application has the following beneficial effects: 1. The formation of a three-dimensional network structure by ether-containing multifunctional monomers reduces the cohesive force of polyacrylate, making the dry film soft, and enables effective bonding of PE / PP separators and positive and negative electrodes at 25℃ under a pressure of 5-30 tons, breaking through the high energy consumption limit of traditional 80-90℃ hot pressing process and meeting the requirements of green manufacturing.

[0014] 2. The polar functional groups provided by the acid monomers and nitrile monomers enhance adhesion to the electrodes, and the first discharge efficiency is high.

[0015] 3. The long side chain hydrocarbon chain monomers improve the compatibility and wettability with PE / PP separators, improve the electrolyte conduction efficiency, and have excellent rate performance.

[0016] 4. The amide monomers and acrylate monomers provide flexibility and chemical stability, and the capacity retention rate after 300 cycles is high. DETAILED DESCRIPTION

[0017] In order to enable those skilled in the art to better understand the technical solutions of the present application, the present application will be described in detail below, and the description in this part is only exemplary and explanatory, and should not have any limiting effect on the protection scope of the present application.

[0018] The present embodiment provides a binder for lithium battery separator cold pressing process, which is made of the following components in percentage by weight: acid monomers 5%-30%, amide monomers 5%-30%, nitrile monomers 10%-70%, acrylate monomers 5%-30%, ether-containing multifunctional monomers 1%-5%, long side chain hydrocarbon chain monomers 1%-5%, neutralizing agent 5%-30%, and initiator 0.1%-2%.

[0019] Among them, the ether-containing multifunctional monomers form a three-dimensional network structure, reduce the cohesive force, make the dry film soft, and adapt to the 25℃ cold pressing process; at the same time, the long side chain hydrocarbon chain monomers improve the compatibility and wettability with PE / PP separators, and realize low-energy cold pressing bonding.

[0020] Further: The acid monomers are selected from at least one of acrylic acid, methacrylic acid, maleic acid, itaconic acid, or derivatives of anhydride thereof.

[0021] The amide monomers are selected from at least one of acrylamide, methacrylamide, N-isopropyl acrylamide, N,N-dimethyl acrylamide, and N-hydroxymethyl acrylamide.

[0022] The nitrile monomers are selected from at least one of acrylonitrile, methacrylonitrile, styrylnitrile, fluorinated acrylonitrile, and cyanoethyl vinyl ether.

[0023] The acrylate monomer is selected from at least one of methyl methacrylate, (meth)acrylic acid ethyl ester, (meth)acrylic acid hydroxyethyl ester, (meth)acrylic acid isooctyl ester, (meth)acrylic acid n-butyl ester, (meth)acrylic acid glycidyl ester, (meth)acrylic acid lauryl ester.

[0024] The ether bond-containing multifunctional monomer is selected from at least one of trimethylolpropane diallyl ether, ethoxy ethoxy ethyl acrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glyceryl triacrylate, ethoxylated pentaerythritol tetraacrylate, ethoxylated 1,6-hexanediol diacrylate.

[0025] The long side chain hydrocarbon chain monomer is selected from at least one of tricyclodecane dimethylol (dimethyl) acrylate, bicyclo pentane (meth) acrylate, 1-adamantane acrylate, t-butyl cyclohexyl acrylate, trimethyl cyclohexyl acrylate.

[0026] The neutralizing agent is selected from at least one of sodium hydroxide, lithium hydroxide, ammonia, ethanolamine, triethanolamine, isobutanolamine.

[0027] The initiator is selected from at least one of ammonium persulfate, sodium persulfate, potassium persulfate.

[0028] Among them, the amide monomer (such as N-isopropyl acrylamide) and the acrylate monomer (such as hydroxyethyl methacrylate) provide flexibility and polar groups to form hydrogen bonds with PE / PP separators and pole pieces; the long side chain monomer (such as tricyclodecane dimethylol acrylate) matches the hydrophobic surface of the PE / PP separator through the hydrocarbon chain to improve wettability and improve the electrolyte conduction efficiency, and the rate performance is excellent; the ether bond-containing monomer (such as ethoxylated trimethylolpropane triacrylate) forms a three-dimensional network to reduce cohesion, support the 25℃ cold pressing process, and reduce energy consumption; the neutralizing agent (such as ammonia) adjusts the pH to 6.5~8.0 to ensure the storage stability of the water-based adhesive.

[0029] Further, it also includes: High-temperature-resistant monomer 2%~10%.

[0030] Dynamic crosslinking monomer 1%~5%.

[0031] Among them, the high-temperature-resistant monomer (such as N-phenyl maleimide) enhances the thermal stability of the polymer chain, which can reduce the decline rate of the adhesion strength at high temperature; the dynamic crosslinking monomer (such as a monomer containing a disulfide bond or a Diels-Alder bond) forms a reversible crosslinking network, which can realize self-repairing of the coating through bond breaking and recombination at a battery operating temperature of 40~60℃, maintain the adhesion strength, and improve the cycle performance; the high-temperature-resistant monomer and the acid and nitrile monomers synergistically enhance the chemical stability, and the dynamic crosslinking monomer and the ether bond-containing monomer synergistically optimize the network structure.

[0032] Further: The high-temperature-resistant monomer is selected from at least one of N-phenyl maleimide and vinyl trimethoxysilane.

[0033] The dynamic crosslinking monomer is selected from at least one of a disulfide bond-containing monomer or a Diels-Alder bond-containing monomer.

[0034] Among them, the rigid aromatic ring of N-phenyl maleimide and the silicon-oxygen bond (Si-O) of vinyl trimethoxysilane significantly improve the heat resistance of the coating, which can effectively reduce the high-temperature bonding strength reduction rate; the disulfide bond-containing monomer (such as dithiodipropenylate) repairs the coating microcracks at high temperature through disulfide bond exchange and the Diels-Alder bond monomer through reversible addition reaction, thereby enhancing the cycle stability.

[0035] Further: The disulfide bond-containing monomer is dithiodipropenylate.

[0036] The Diels-Alder bond-containing monomer is furanyl acrylate.

[0037] Among them, the disulfide bond (-S-S-) of dithiodipropenylate can be dynamically repaired by breaking-recombining at 40-60°C, maintaining the integrity of the coating and reducing the high-temperature bonding strength reduction rate; furanyl acrylate forms reversible crosslinking through Diels-Alder reaction, repairs microcracks at high temperature, and re-crosslinks at low temperature, thereby enhancing the stability of the coating in battery cycling; the disulfide bond and the Diels-Alder bond synergize with the high-temperature-resistant monomers such as N-phenyl maleimide to strengthen the thermal stability of the polymer chain and reduce the risk of softening at high temperature; the self-repairing ability of the dynamic crosslinking monomer reduces the coating peeling and improves the cycle capacity retention rate.

[0038] The present embodiment also provides a preparation method for preparing the binder for the cold-pressing process of the lithium battery separator membrane as described in any one of the above embodiments, which comprises the following steps: a. After mixing the binder component, add deionized water and stir to form a uniform mixture, wherein the binder component includes acid monomers, amide monomers, nitrile monomers, acrylate monomers, ether bond-containing multifunctional monomers, and long side chain hydrocarbon chain monomers.

[0039] b. Under the protection of nitrogen, add an initiator and heat to perform a free radical polymerization reaction.

[0040] c. After the reaction is completed, add a neutralizing agent to adjust the pH value to 6.5-8.0, dilute and vacuum to remove residual monomers.

[0041] Further: The stirring speed in the mixing step is 200-500 rpm, and the solid content of the mixed solution is 20%-30%.

[0042] The radical polymerization reaction is carried out at 60-80°C, and the reaction time is 5-15 hours.

[0043] The vacuum degree in the vacuum extraction step is -0.09 MPa.

[0044] Further, the nitrile monomer includes fluoroacrylonitrile and / or cyanoethyl vinyl ether, the adhesive component further includes an imidazole-based ionic liquid monomer and an antioxidant monomer, wherein: The imidazole-based ionic liquid monomer accounts for 0.5%-3% of the total mass of the adhesive component, and the preparation process of the imidazole-based ionic liquid monomer specifically includes the following steps: mixing acrylic acid and 1-ethyl-3-methylimidazolium chloride at a molar ratio of (2.5-3.5):1, adding dichloromethane solvent and catalyst N,N-dicyclohexyl carbodiimide, and performing esterification reaction at 25-35°C for 5-7 hours under nitrogen protection. After purification by extraction, it is obtained.

[0045] The antioxidant monomer accounts for 0.5%-2% of the total mass of the adhesive component, and the preparation process of the antioxidant monomer specifically includes the following steps: mixing 4-hydroxybenzoic acid and hydroxyethyl acrylate at a molar ratio of (1-1.2):1, adding toluene solvent and catalyst p-toluenesulfonic acid, and performing esterification reaction at 95-105°C for 3-5 hours under nitrogen protection. After purification by distillation, it is obtained.

[0046] Among them, the imidazole-based ionic liquid monomer is specifically imidazole-based acrylate (IL-Monomer), and the imidazole group in the imidazole-based acrylate has a wide electrochemical window, which can coordinate with LiPF6 in the LiPF6 electrolyte to form a protective interfacial layer, effectively inhibiting the defluorination reaction (free radicals generated to cause polymer degradation) of fluoroacrylonitrile and the oxidative cleavage of the ether bond of cyanoethyl vinyl ether at high voltage. + and PF 6- The antioxidant monomer is specifically 4-hydroxybenzoic acid acrylate (AO-Monomer), and the phenolic hydroxyl group in the 4-hydroxybenzoic acid acrylate has strong antioxidant properties, which can capture free radicals in the high-voltage or electrolyte environment, preventing the defluorination chain reaction of fluoroacrylonitrile and the oxidative degradation of cyanoethyl vinyl ether.

[0047] The ionic liquid property of IL-Monomer enhances the ionic conductivity of the polymer coating, is compatible with the LiPF6 / EC / DMC electrolyte, promotes Li + conduction, and reduces the internal resistance of the battery cell. AO-Monomer stabilizes the nitrile monomer, reduces the interfacial side reaction, further reduces the impedance of the electrode / separator interface, and improves the first discharge efficiency.

[0048] Further, The nitrile monomer includes vinyl triethoxysilane modified acrylonitrile, and the preparation process thereof specifically includes the following steps: acrylonitrile is mixed with vinyl triethoxysilane at a molar ratio of (5-10):1, toluene solvent and initiator azobisisobutyronitrile are added, and the mixture is reacted at 60-80°C for 4-6 hours under nitrogen protection, and then a free radical copolymerization is performed to obtain the product.

[0049] The acrylate monomer includes 4-vinylpyridine modified methacrylate, and the preparation process thereof specifically includes the following steps: methacrylate is mixed with 4-vinylpyridine at a molar ratio of (3-5):1, a catalyst p-toluenesulfonic acid and a polymerization inhibitor hydroquinone are added, and then an ester exchange reaction is performed at 100-120°C under nitrogen protection for 3-5 hours to obtain the product.

[0050] The siloxane group (Si-PAN) is introduced into acrylonitrile through free radical copolymerization, which enhances the hydrophobic compatibility with the PE / PP separator and increases the adhesion; the pyridine ring (Py-MMA) is introduced into methacrylate through ester exchange, which forms hydrogen bonds and π-π stacking with the pole piece, reduces the internal resistance of the battery, and improves the initial efficiency; the silicon-oxygen bond of Si-PAN improves the high-temperature stability, and Py-MMA enhances the stability of the electrode interface, which can improve the cycle capacity retention rate.

[0051] Further, the long side chain carbon-hydrogen chain monomer includes phosphonic acid modified tricyclodecane dimethylol acrylate, and the preparation process thereof specifically includes the following steps: tricyclodecane dimethylol acrylate is mixed with dimethyl phosphonic acid at a molar ratio of (1.5-2.5):1, dichloromethane solvent and catalyst N,N-dicyclohexyl carbodiimide are added, and then an esterification reaction is performed at 25-35°C for 5-7 hours under nitrogen protection, and then the product is obtained through extraction and purification.

[0052] The phosphonic acid modified tricyclodecane dimethylol acrylate (P-TCDDA) retains the hydrophobicity of the tricyclodecane group, matches with the PE / PP separator (low surface energy material), reduces the surface tension, and improves the wettability. The phosphonic acid group forms a dynamic reversible bond through hydrogen bonding and coordination with the metal oxide / graphite on the surface of the pole piece, supports the repair of coating micro-cracks at 40-60°C, and enhances the mechanical toughness.

[0053] The P-TCDDA is prepared through esterification reaction, and the reaction conditions are mild, the by-products are few, and the product is easy to purify. The P-TCDDA cooperates with the multifunctional monomer containing ether bond to reduce the cohesive force of the polymer, make the dry film soft, adapt to the 25°C cold pressing process, and save energy and protect the environment.

[0054] The following provides specific examples, which can make the person skilled in the art more fully understand the present application, but do not limit the present application in any way.

[0055] Example 1 In a 5L reactor, 750g of deionized water was added, and then acrylic acid (150g), N-methylol acrylamide (100g), acrylonitrile (500g), hydroxyethyl methacrylate (150g), ethoxylated trimethylolpropane triacrylate (40g), tricyclodecane dimethanol acrylate (30g) were added in sequence. A magnetic stirrer (400 rpm) was used to stir for 30 minutes until uniform, and the solid content of the mixture was 25%.

[0056] Nitrogen was introduced (flow rate 0.5 L / min, 10 minutes) to remove oxygen, and nitrogen protection was maintained. The reactor was heated to 60°C (temperature control accuracy ±0.1°C), and ammonium persulfate (10g, dissolved in 20g deionized water) was added. The temperature was maintained at 60°C, and stirring (300 rpm) was performed for 10 hours to obtain a polyacrylate emulsion.

[0057] The temperature was cooled to 25°C, and ammonia water (120g, 25% concentration) was added. Stirring (200 rpm, 10 minutes) was performed, and the pH was adjusted to 7.0. Deionized water (about 250g) was added to dilute to a solid content of 20%, and a vacuum pump (-0.09 MPa) was used to remove residual monomers for 30 minutes.

[0058] The emulsion was coated on a PE separator (thickness 16μm) using a coating machine, and the coating thickness was 1.5μm. The coated separator was dried in a constant temperature oven at 80°C for 4 minutes to form a uniform dry film.

[0059] The coated separator was laminated with positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite) using a hydraulic cold press at 25°C and a pressure of 10 tons, and the pressure was maintained for 12 seconds.

[0060] The laminated separator and electrode sheets were assembled into a soft-pack battery, and electrolyte (1M LiPF6, EC / DMC=1:1) was injected. After sealing, formation was performed (0.1C charging to 4.2V, and standing for 24 hours).

[0061] The internal resistance was measured by AC impedance method in the frequency range of 0.1 Hz~100 kHz at a test temperature of 25°C. The internal resistance (unit: mΩ) was measured after the battery was fully charged to 4.2V. Eight samples were tested, and the average value was taken. The test data are shown in Table 1-1.

[0062] At 25°C, 0.1C constant current charging was performed to 4.2V, and constant voltage charging was performed to a current <0.01C, and then discharging was performed to 3.0V. The initial voltage, the end voltage (standing for 5 minutes), and the specific capacity (mAh / g) were recorded. Two groups of samples were tested, and the average value was taken. The test data are shown in Table 1-2.

[0063] Charge at 25 °C to 4.2 V at 0.1 C, discharge to 3.0 V at 0.2 C, 0.5 C, 1 C, 1.5 C, 2 C, respectively, record the discharge capacity (mAh). Calculate the rate retention (relative to 0.2 C). Test 2 groups of samples, test data as shown in Table 1-3.

[0064] Charge at 25 °C to 4.2 V at 3 C, constant voltage to current <0.01 C, discharge to 3.0 V at 3 C, cycle 300 times. Record the initial capacity (0.5 C and 3 C) and the capacity after 300 times, calculate the capacity retention rate (300 times capacity / 3 C initial capacity x 100%). Test 2 groups of samples, test data as shown in Table 1-4.

[0065] Charge at 25 °C to 4.2 V at 1 C, constant voltage to current <0.01 C, discharge to 3.0 V at 1 C, cycle 300 times. Record the initial capacity and the capacity after 300 times, calculate the residual capacity ratio (300 times capacity / initial capacity x 100%). Test 1 group of samples, test data as shown in Table 1-5.

[0066] Coated binder PE separator (16 μm, coating thickness 1.5 μm) and positive electrode sheet (NCM811) are cold pressed (25 °C, 10 tons, 12 seconds), cut into 1 cm wide strips. Adjust to 25 °C, 45 °C, 60 °C (humidity 50% RH, ±0.5 °C) in a constant temperature and humidity box, respectively. 180° peeling test, speed 50 mm / min, record the peeling force (N / cm). Test 3 times at each temperature point, take the average. Calculate the high temperature drop rate: [(25 °C peeling force-high temperature peeling force) / 25 °C peeling force] x 100%. Test data as shown in Table 1-6.

[0067]

[0068]

[0069]

[0070]

[0071]

[0072]

[0073] Example 2 In a 5L reaction kettle, 750g of deionized water was added, and then acrylic acid (120g), N-isopropyl acrylamide (120g), acrylonitrile (480g), hydroxyethyl methacrylate (180g), ethoxylated trimethylolpropane triacrylate (50g), tricyclodecane dimethanol acrylate (40g) were added in sequence. Using a magnetic stirrer (400 rpm), stirring for 30 minutes to uniform, the solid content of the mixture was 25%.

[0074] Nitrogen was introduced (flow rate 0.5 L / min, 10 minutes) to remove oxygen, and nitrogen protection was maintained. The reaction kettle was heated to 60°C (temperature control accuracy ±0.1°C), and ammonium persulfate (10g, dissolved in 20g deionized water) was added. Maintain 60°C, stirring (300 rpm), reaction for 10 hours, to obtain a polyacrylate emulsion.

[0075] Cool to 25°C, add ammonia (100g, 25% concentration), stirring (200 rpm, 10 minutes), adjust pH to 7.0. Diluted with deionized water (about 250g) to a solid content of 20%, using a vacuum pump (-0.09 MPa) to vacuum for 30 minutes, to remove residual monomers.

[0076] Using a coating machine, the emulsion was coated on a PE separator (thickness 16μm), coating thickness 1.5μm. Dried in a constant temperature oven at 80°C for 4 minutes to form a uniform dry film.

[0077] Using a hydraulic cold press, the coated separator was laminated with positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite) at 25°C and 10 tons of pressure, and the pressure was maintained for 12 seconds.

[0078] The cold-pressed separator was assembled with positive and negative electrode sheets into a soft-pack battery, and electrolyte (1M LiPF6, EC / DMC=1:1) was injected, and then sealed and formed (0.1C charged to 4.2V, and left for 24 hours).

[0079] The test items and test methods were the same as in Example 1, and the test data is shown in Tables 2-1 to 2-6.

[0080]

[0081]

[0082]

[0083]

[0084]

[0085]

[0086] Example 3 In a 5L reactor, 750g of deionized water was added, and then acrylic acid (100g), N-isopropyl acrylamide (150g), acrylonitrile (450g), hydroxyethyl methacrylate (200g), ethoxylated 1,6-hexanediol diacrylate (50g), tricyclodecane dimethanol acrylate (40g) were added in sequence. A magnetic stirrer (400 rpm) was used to stir for 30 minutes to uniformity, and the solid content of the mixture was 25%.

[0087] Nitrogen was introduced (flow rate 0.5 L / min, 10 minutes) to remove oxygen, and nitrogen protection was maintained. The reactor was heated to 60°C (temperature control accuracy ±0.1°C), and ammonium persulfate (10g, dissolved in 20g deionized water) was added. The temperature was maintained at 60°C, and stirring (300 rpm) was carried out for 10 hours to obtain a polyacrylate emulsion.

[0088] The temperature was cooled to 25°C, and ammonia water (100g, 25% concentration) was added. Stirring (200 rpm, 10 minutes) was carried out, and the pH was adjusted to 7.0. Deionized water (about 250g) was added to dilute to a solid content of 20%, and a vacuum pump (-0.09 MPa) was used to remove residual monomers for 30 minutes.

[0089] The emulsion was coated on a PE separator (thickness 16μm) using a coating machine, and the coating thickness was 1.5μm. Drying was carried out in a constant temperature oven at 80°C for 4 minutes to form a uniform dry film.

[0090] The coated separator was laminated with positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite) using a hydraulic cold press at 25°C and a pressure of 10 tons, and the pressure was maintained for 12 seconds.

[0091] The cold-pressed separator was assembled with positive and negative electrode sheets to form a soft-pack battery, and electrolyte (1M LiPF6, EC / DMC=1:1) was injected. After sealing, formation was carried out (0.1C charging to 4.2V, standing for 24 hours).

[0092] The test items and test methods were the same as in Example 1, and the test data are shown in Tables 3-1 to 3-6.

[0093]

[0094]

[0095]

[0096]

[0097]

[0098]

[0099] Example 4 In a 5L reactor, 750g of deionized water was added, and then acrylic acid (150g), N-methylol acrylamide (100g), acrylonitrile (500g), hydroxyethyl methacrylate (150g), ethoxylated trimethylolpropane triacrylate (40g), tricyclodecane dimethanol acrylate (30g), N-phenylmaleimide (50g), dithiodipropyl acrylate (30g) were added in sequence. A magnetic stirrer (400 rpm) was used to stir for 30 minutes to obtain a uniform mixture, and the solid content of the mixture was 25.2%.

[0100] Nitrogen was introduced (flow rate 0.5 L / min, 10 min) to remove oxygen, and nitrogen protection was maintained. The reactor was heated to 60°C (temperature control accuracy ±0.1°C), and ammonium persulfate (10g dissolved in 20g deionized water) was added. The temperature was maintained at 60°C, and the reaction was stirred (300 rpm) for 10.5 hours to obtain a polyacrylate emulsion.

[0101] The temperature was cooled to 25°C, and ammonia water (125g, 25% concentration) was added. The mixture was stirred (200 rpm, 10 min) to adjust the pH to 7.1. Deionized water (about 260g) was added to dilute the mixture to a solid content of 20.1%, and a vacuum pump (-0.09 MPa) was used to remove residual monomers for 30 minutes.

[0102] The emulsion was coated on a PE separator (thickness 16μm) using a coating machine, and the coating thickness was 1.5μm. The coated separator was dried in a constant temperature oven at 80°C for 4 minutes to form a uniform dry film.

[0103] The coated separator was laminated with positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite) using a hydraulic cold press at 25°C and a pressure of 10 tons, and the pressure was maintained for 12 seconds.

[0104] The laminated separator and electrode sheets were assembled into a soft-pack battery, and electrolyte (1M LiPF6, EC / DMC=1:1) was injected. After sealing, the battery was formed (charged at 0.1C to 4.2V and left for 24 hours).

[0105] The test items and test methods were the same as in Example 1, and the test data are shown in Tables 4-1 to 4-6.

[0106]

[0107]

[0108]

[0109]

[0110]

[0111]

[0112] Example 5 In a 5L reactor, 750g of deionized water was added, and then acrylic acid (150g), N-methylol acrylamide (100g), fluorinated acrylonitrile (250g), cyanoethyl vinyl ether (250g), hydroxyethyl methacrylate (150g), ethoxylated trimethylolpropane triacrylate (40g), tricyclodecane dimethanol acrylate (30g) were added in sequence. A magnetic stirrer (400 rpm) was used to stir for 30 minutes to uniformity, and the solid content of the mixture was 25.3%.

[0113] Nitrogen was introduced (flow rate 0.5 L / min, 10 minutes) to remove oxygen, and nitrogen protection was maintained. The reactor was heated to 60°C (temperature control accuracy ±0.1°C), and ammonium persulfate (10g, dissolved in 20g of deionized water) was added. The temperature was maintained at 60°C, and stirring (300 rpm) was performed for 10.2 hours to obtain a polyacrylate emulsion.

[0114] The temperature was cooled to 25°C, and ammonia water (122g, 25% concentration) was added. Stirring (200 rpm, 10 minutes) was performed, and the pH was adjusted to 7.0. Deionized water (about 255g) was added to dilute to a solid content of 20.2%, and a vacuum pump (-0.09 MPa) was used to remove residual monomers for 30 minutes.

[0115] The emulsion was coated on a PE separator (thickness 16μm) using a coating machine, and the coating thickness was 1.5μm. The coated separator was dried in a constant temperature oven at 80°C for 4 minutes to form a uniform dry film.

[0116] The coated separator was laminated with positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite) using a hydraulic cold press at 25°C and a pressure of 10 tons, and the pressure was maintained for 12 seconds.

[0117] The cold-pressed separator was assembled with positive and negative electrode sheets to form a soft-pack battery, and electrolyte (1M LiPF6, EC / DMC=1:1) was injected. After sealing, formation was performed (0.1C charging to 4.2V, standing for 24 hours).

[0118] The test items and test methods were the same as in Example 1, and the test data are shown in Tables 5-1 to 5-6.

[0119]

[0120]

[0121]

[0122]

[0123]

[0124]

[0125] Example 6 Mix acrylic acid (180 g) with 1-ethyl-3-methylimidazolium chloride (73 g), add dichloromethane solvent (500 mL) and catalyst N,N-dicyclohexyl carbodiimide (10 g). Perform esterification reaction at 25 °C for 6 hours under nitrogen protection, and purify by extraction to obtain imidazolyl acrylate (about 200 g).

[0126] Mix 4-hydroxybenzoic acid (138 g) with hydroxyethyl acrylate (116 g), add toluene solvent (500 mL) and catalyst p-toluenesulfonic acid (5 g). Perform esterification reaction at 100 °C for 4 hours under nitrogen protection, and purify by distillation to obtain 4-hydroxybenzoic acid acrylate (about 220 g).

[0127] In a 5 L reaction kettle, add 750 g of deionized water, and sequentially add acrylic acid (150 g), N-hydroxymethyl acrylamide (100 g), fluorinated acrylonitrile (250 g), cyanoethyl vinyl ether (250 g), hydroxyethyl methacrylate (150 g), ethoxylated trimethylolpropane triacrylate (40 g), tricyclodecane dimethanol acrylate (30 g), imidazolyl acrylate (20 g), and 4-hydroxybenzoic acid acrylate (15 g). Stir for 30 minutes to uniformity using a magnetic stirrer (400 rpm), and the mixture has a solid content of 25.4%.

[0128] Remove oxygen by purging with nitrogen (flow rate 0.5 L / min for 10 minutes) and maintain nitrogen protection. Heat the reaction kettle to 60 °C (temperature control accuracy ± 0.1 °C), and add ammonium persulfate (10 g dissolved in 20 g of deionized water). Maintain 60 °C and stir (300 rpm) for 10.3 hours to obtain a polyacrylate emulsion.

[0129] Cool to 25 °C, add ammonia water (123 g, 25% concentration), and stir (200 rpm for 10 minutes) to adjust the pH to 7.1. Dilute with deionized water (about 258 g) to a solid content of 20.3%, and remove residual monomers by vacuum pumping (-0.09 MPa) for 30 minutes.

[0130] Use a coating machine to coat the emulsion on a PE separator (thickness 16 μm) to a coating thickness of 1.5 μm. Dry in a constant temperature oven at 80 °C for 4 minutes to form a uniform dry film.

[0131] Using a hydraulic cold press, at 25°C and 10 tons of pressure, the coated separator was bonded to the positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite), and the pressure was maintained for 12 seconds.

[0132] The cold-pressed separator and positive and negative electrodes were assembled into a soft-pack battery, and the electrolyte (1M LiPF6, EC / DMC=1:1) was injected. After sealing, the battery was formed (charged at 0.1C to 4.2V and left to stand for 24 hours).

[0133] The test items and test methods are the same as those in Example 1, and the test data are shown in Tables 6-1 to 6-6.

[0134]

[0135]

[0136]

[0137]

[0138]

[0139]

[0140] Example 7 Acrylonitrile (500g) and vinyltriethoxysilane (100g) were mixed, and toluene solvent (1000mL) and initiator azobisisobutyronitrile (5g) were added. A free radical copolymerization reaction was carried out at 65°C under nitrogen for 5 hours. Vinyltriethoxysilane-modified acrylonitrile (approximately 550g) was obtained by purification by distillation.

[0141] Methyl methacrylate (400g) and 4-vinylpyridine (105g) were mixed, and p-toluenesulfonic acid (5g) as a catalyst and hydroquinone (2g) as a polymerization inhibitor were added. The transesterification reaction was carried out at 110°C under nitrogen for 4 hours. 4-vinylpyridine-modified methacrylate (approximately 450g) was obtained by purification by distillation.

[0142] To a 5L reactor, add 750g of deionized water, followed by acrylic acid (150g), N-methylol acrylamide (100g), vinyl triethoxysilane-modified acrylonitrile (500g), 4-vinyl pyridine-modified methacrylate (150g), ethoxylated trimethylolpropane triacrylate (40g), tricyclodecane dimethanol acrylate (30g), N-phenylmaleimide (50g), and dithiodiacrylate (30g). Stir with a magnetic stirrer (400rpm) for 30 minutes until homogeneous, resulting in a mixture with a solids content of 25.5%.

[0143] Nitrogen was purged (flow rate 0.5 L / min, 10 min) to remove oxygen, and nitrogen protection was maintained. The reaction kettle was heated to 60°C (temperature control accuracy ± 0.1°C), and ammonium persulfate (10 g, dissolved in 20 g of deionized water) was added. The reaction was maintained at 60°C with stirring (300 rpm) for 10.4 hours to obtain a polyacrylate emulsion.

[0144] Cooling to 25°C, adding ammonia water (124 g, 25% concentration), stirring (200 rpm, 10 min), adjusting pH to 7.2. Diluted with deionized water (about 260 g) to solid content 20.2%, vacuum (-0.09 MPa) for 30 min to remove residual monomers.

[0145] Using a coating machine, the emulsion was coated on a PE separator (thickness 16 μm), and the coating thickness was 1.5 μm. Drying in a constant temperature oven at 80°C for 4 min to form a uniform dry film.

[0146] Using a hydraulic cold press, the coated separator was laminated with positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite) at 25°C and 10 tons of pressure, and the pressure was maintained for 12 seconds.

[0147] The cold-pressed separator was assembled with positive and negative electrode sheets into a soft-pack battery, and electrolyte (1M LiPF6, EC / DMC=1:1) was injected. After sealing, formation (0.1C charging to 4.2V, standing for 24 hours).

[0148] The test items and test methods were the same as in Example 1, and the test data are shown in Tables 7-1 to 7-6.

[0149]

[0150]

[0151]

[0152]

[0153]

[0154]

[0155] Example 8 Tricyclodecane dimethylol acrylate (300 g) was mixed with dimethyl phosphonic acid (124 g), and dichloromethane solvent (600 mL) and catalyst N,N-dicyclohexyl carbodiimide (10 g) were added. Under nitrogen protection, esterification was carried out at 30°C for 6 hours, and phosphonic acid modified tricyclodecane dimethylol acrylate (about 350 g) was obtained by extraction purification.

[0156] Mix acrylonitrile (500 g) with vinyltriethoxysilane (100 g), add toluene solvent (1000 mL) and initiator azobisisobutyronitrile (5 g). Perform radical copolymerization at 65 °C for 5 hours under nitrogen protection, and purify by distillation to obtain vinyltriethoxysilane-modified acrylonitrile (about 550 g).

[0157] Mix methyl methacrylate (400 g) with 4-vinylpyridine (105 g), add catalyst p-toluenesulfonic acid (5 g) and polymerization inhibitor hydroquinone (2 g). Perform ester exchange reaction at 110 °C for 4 hours under nitrogen protection, and purify by distillation to obtain 4-vinylpyridine-modified methacrylate (about 450 g).

[0158] In a 5 L reaction kettle, add 750 g of deionized water, and sequentially add acrylic acid (150 g), N-hydroxymethyl acrylamide (100 g), vinyltriethoxysilane-modified acrylonitrile (500 g), 4-vinylpyridine-modified methacrylate (150 g), ethoxylated trimethylolpropane triacrylate (40 g), phosphonic acid-modified tricyclodecane dimethanol acrylate (30 g), N-phenylmaleimide (50 g), and dithiodipropyl acrylate (30 g). Use a magnetic stirrer (400 rpm) to stir for 30 minutes until uniform, and the mixture has a solid content of 25.6%.

[0159] Purge oxygen by passing nitrogen (flow rate 0.5 L / min for 10 minutes) and maintain nitrogen protection. Heat the reaction kettle to 60 °C (temperature control accuracy ± 0.1 °C), and add ammonium persulfate (10 g dissolved in 20 g of deionized water). Maintain 60 °C and stir (300 rpm) for 10.5 hours to obtain a polyacrylate emulsion.

[0160] Cool to 25 °C, add ammonia water (125 g, 25% concentration), stir (200 rpm for 10 minutes), and adjust the pH to 7.2. Dilute with deionized water (about 262 g) to a solid content of 20.3%, and use a vacuum pump (-0.09 MPa) to vacuum for 30 minutes to remove residual monomers.

[0161] Use a coating machine to coat the emulsion on a PE separator (thickness 16 μm) with a coating thickness of 1.5 μm. Dry in a constant temperature oven at 80 °C for 4 minutes to form a uniform dry film.

[0162] Use a hydraulic cold press to bond the coated separator with positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite) at 25 °C and a pressure of 10 tons, and maintain the pressure for 12 seconds.

[0163] The cold-pressed separator was assembled with positive and negative electrode sheets to form a soft-pack battery, and electrolyte (1M LiPF6, EC / DMC = 1:1) was injected. After sealing, formation (0.1C charging to 4.2V, standing for 24 hours) was carried out.

[0164] The test items and test methods were the same as in Example 1, and the test data is shown in Tables 8-1 to 8-6.

[0165]

[0166]

[0167]

[0168]

[0169]

[0170]

[0171] Comparative Example In a 5L reaction kettle, 1000g of N-methyl pyrrolidone was added, and polyvinylidene fluoride (500g) and polyacrylate (500g) were added in turn. Using a magnetic stirrer (400 rpm), stirring was carried out at 50°C for 2 hours to complete dissolution, to obtain a binder solution with a solid content of 20.1%.

[0172] The solution was coated on a PE separator (thickness 16μm) using a coater, with a coating thickness of 1.5μm. Drying was carried out in a constant temperature oven at 120°C for 5 minutes to form a uniform dry film.

[0173] The coated separator was laminated with positive and negative electrode sheets (positive electrode: NCM811, negative electrode: graphite) using a hydraulic hot press at 85°C and a pressure of 10 tons, with the pressure maintained for 12 seconds.

[0174] The hot-pressed separator was assembled with positive and negative electrode sheets to form a soft-pack battery, and electrolyte (1M LiPF6, EC / DMC = 1:1) was injected. After sealing, formation (0.1C charging to 4.2V, standing for 24 hours) was carried out.

[0175] The test items and test methods were the same as in Example 1, and the test data is shown in Tables 9-1 to 9-6.

[0176]

[0177]

[0178]

[0179]

[0180]

[0181]

[0182] From the above data, it can be seen that Examples 1-8 achieve 25℃ cold pressing process by ether-containing multifunctional monomers, reduce energy consumption; long side chain monomers (P-TCDDA), modified nitrile monomers (Si-PAN), acrylic ester monomers (Py-MMA), high temperature resistant monomers and dynamic crosslinking monomers synergistically improve the electrochemical performance and high temperature stability, which are significantly better than the traditional PVDF / PAA binder.

[0183] Among them, Example 3 performs best in rate performance (96.22%), because the ethoxylation of 1,6-hexanediol diacrylate forms a more optimized three-dimensional network structure, but the internal resistance (107.75mΩ) is higher, and the cycle performance (76.72%) is not as good as Examples 4-8.

[0184] Example 4 significantly improves the cycle performance (92.02%) and high temperature peel force stability (10.75%) by using high temperature resistant and dynamic crosslinking monomers, but the internal resistance and initial efficiency are slightly inferior to Examples 6-8.

[0185] Example 6 has lower internal resistance (101.98mΩ) and cycle performance (90.16%) than Example 5 due to the electrochemical optimization of IL-Monomer and AO-Monomer, but the peel force drop rate (15.28%) is higher.

[0186] Example 8 has the best comprehensive performance, with the lowest internal resistance (100.95mΩ), the highest initial efficiency (93.56%), and the best cycle performance (92.61%) and peel force stability (10.81%).

[0187] In this paper, specific examples are used to illustrate the principles and implementation methods of the present application. The above examples are only used to help understand the method and its core idea. The above is only a preferred embodiment of the present application, but the protection scope of the present application is not limited to this. Any skilled person in the technical field can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be within the protection scope of the present application.

Claims

1. A binder for a lithium battery separator cold pressing process, characterized in that: The invention comprises the following components by weight percentage: 5% to 30% of acid monomer, 5% to 30% of amide monomer, 10% to 70% of nitrile monomer, 5% to 30% of acrylate monomer, 1% to 5% of ether bond-containing multifunctional monomer, 1% to 5% of long side chain hydrocarbon chain monomer, 5% to 30% of neutralizer and 0.1% to 2% of initiator.

2. The adhesive for the cold pressing process of lithium battery separators according to claim 1, characterized in that: The acid monomer is selected from at least one of acrylic acid, methacrylic acid, maleic acid, itaconic acid or anhydrides of their derivatives; The amide monomer is selected from at least one of acrylamide, methacrylamide, N-isopropylacrylamide, N,N-dimethylacrylamide, and N-hydroxymethylacrylamide; The nitrile monomer is selected from at least one of acrylonitrile, methacrylonitrile, styryl nitrile, fluoroacrylonitrile, and cyanoethyl vinyl ether; The acrylic acid ester monomer is at least one selected from methyl methacrylate, ethyl (meth)acrylate, hydroxyethyl (meth)acrylate, isooctyl (meth)acrylate, n-butyl (meth)acrylate, glycidyl (meth)acrylate, and lauryl (meth)acrylate; The ether bond-containing multifunctional monomer is selected from at least one of trimethylolpropane diallyl ether, ethoxyethoxyethyl acrylate, ethoxylated trimethylolpropane triacrylate, propoxylated glycerol triacrylate, ethoxylated pentaerythritol tetraacrylate, and ethoxylated 1,6-hexanediol diacrylate; The long side chain hydrocarbon chain monomer is at least one selected from tricyclodecane dimethanol (dimethyl) acrylate, dicyclopentane (meth) acrylate, 1-adamantyl acrylate, tert-butyl cyclohexyl acrylate, and trimethyl cyclohexyl acrylate; The neutralizing agent is selected from at least one of sodium hydroxide, lithium hydroxide, ammonia, ethanolamine, triethanolamine, and isobutanolamine; The initiator is selected from at least one of ammonium persulfate, sodium persulfate, and potassium persulfate.

3. The binder for the cold pressing process of lithium battery separators according to claim 1, characterized in that: It also includes 2%~10% high temperature resistant monomers and 1%~5% dynamic cross-linking monomers.

4. The adhesive for the cold pressing process of lithium battery separators according to claim 3, characterized in that: The high temperature resistant monomer is selected from at least one of N-phenylmaleimide and vinyltrimethoxysilane; The dynamic cross-linking monomer is selected from at least one of a disulfide bond-containing monomer and a Diels-Alder bond-containing monomer.

5. The adhesive for the cold pressing process of lithium battery separators according to claim 4, characterized in that: The disulfide bond-containing monomer is dithiodiacrylate; The monomer containing Diels-Alder bonds is furanyl acrylate.

6. A preparation method, characterized in that: For preparing the binder for the cold pressing process of lithium battery separators according to any one of claims 1 to 5, the preparation method comprises the following steps: The binder components are mixed and added into deionized water, and stirred to form a uniform mixed solution, wherein the binder components include acid monomers, amide monomers, nitrile monomers, acrylate monomers, ether bond-containing multifunctional monomers and long side chain hydrocarbon chain monomers; Under nitrogen protection, add initiator and heat to carry out free radical polymerization reaction; After the reaction is completed, a neutralizing agent is added to adjust the pH value to 6.5-8.0, and the product is obtained after dilution and vacuum removal of residual monomers.

7. The preparation method according to claim 6, characterized in that: In the mixing step, the stirring speed is 200-500 rpm, and the solid content of the mixed liquid is 20%-30%; The free radical polymerization reaction is carried out at 60-80° C. for 5-15 hours; The vacuum degree of the vacuuming step is -0.09 MPa.

8. The preparation method according to claim 6, characterized in that: The nitrile monomer includes fluoroacrylonitrile and / or cyanoethyl vinyl ether, and the binder component further includes an imidazole-based ionic liquid monomer and an antioxidant monomer, wherein: The imidazolyl ionic liquid monomer accounts for 0.5% to 3% of the total mass of the binder components. The preparation process of the imidazolyl ionic liquid monomer specifically comprises the following steps: mixing acrylic acid and 1-ethyl-3-methylimidazolium chloride in a molar ratio of (2.5 to 3.5):1, adding dichloromethane solvent and catalyst N,N-dicyclohexylcarbodiimide, and conducting an esterification reaction at 25 to 35° C. for 5 to 7 hours under nitrogen protection, and obtaining the obtained product after purification by extraction; The antioxidant monomer accounts for 0.5% to 2% of the total mass of the binder components. The preparation process of the antioxidant monomer specifically includes the following steps: mixing 4-hydroxybenzoic acid and hydroxyethyl acrylate in a molar ratio of (1 to 1.2): 1, adding toluene solvent and catalyst p-toluenesulfonic acid, and conducting an esterification reaction at 95 to 105° C. for 3 to 5 hours under nitrogen protection, and obtaining the antioxidant monomer after purification by distillation.

9. The preparation method according to claim 6, characterized in that: The nitrile monomer includes vinyltriethoxysilane-modified acrylonitrile, and the preparation process specifically includes the following steps: mixing acrylonitrile and vinyltriethoxysilane in a molar ratio of (5-10):1, adding toluene solvent and initiator azobisisobutyronitrile, reacting at 60-80°C for 4-6 hours under nitrogen protection, and obtaining the product through free radical copolymerization; And / or the acrylic ester monomer includes 4-vinylpyridine-modified methacrylate, and the process specifically includes the following steps: methyl methacrylate and 4-vinylpyridine are mixed in a molar ratio of (3-5):1, a catalyst of p-toluenesulfonic acid and a polymerization inhibitor of hydroquinone are added, and an ester exchange reaction is carried out at 100-120° C. under nitrogen protection for 3-5 hours to obtain the product.

10. The preparation method according to claim 6, characterized in that: The long side chain hydrocarbon chain monomer includes phosphonic acid-modified tricyclodecane dimethanol acrylate, and its preparation process specifically includes the following steps: tricyclodecane dimethanol acrylate and dimethylphosphonic acid are mixed in a molar ratio of (1.5-2.5):1, dichloromethane solvent and catalyst N,N-dicyclohexylcarbodiimide are added, and an esterification reaction is carried out at 25-35°C under nitrogen protection for 5-7 hours, and the product is obtained after extraction and purification.

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