High-viscosity composite binder and preparation method thereof

Abstract

The invention belongs to the technical field of new energy adhesives, and provides a high-viscosity composite adhesive and a preparation method thereof.The high-viscosity composite adhesive is prepared from, by weight, 25-45 parts of a water-based adhesive, 20-35 parts of composite ceramic particles, 7-11 parts of PMMA composite microspheres, 1-2 parts of modified cellulose, 0.5-1 part of a wetting agent and 45-60 parts of deionized water. The composite binder disclosed by the invention plays a role in binding a battery diaphragm, has relatively good binding property, high temperature resistance, flame retardance and ionic conductivity, and has a good market prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of new energy adhesives, and particularly relates to a high-viscosity composite adhesive and a preparation method thereof. Background Art

[0002] With the rapid development of new energy technologies, especially in the field of electric vehicles and energy storage systems, the demand for high-performance batteries is growing. As one of the key components of lithium-ion batteries, the performance of battery separators directly affects the safety, energy density and cycle life of batteries.

[0003] Conventional diaphragms can no longer meet the current social development needs. In order to overcome the shortcomings of lithium battery diaphragms, a certain amount of binder needs to be added during diaphragm modification to enable better adhesion between the diaphragm and the electrode. However, although traditional binders (such as polyvinylidene fluoride) have good chemical stability and affinity for electrolytes, their insulating properties for ions and electrons increase the resistance of the system and limit the improvement of battery performance. Therefore, the development of high-viscosity composite binders has become an effective strategy to improve battery performance and safety by integrating electronic and ionic conductivity while maintaining thermal stability and processability.

[0004] Chinese patent CN 109103397 A discloses a method for preparing a ceramic coated diaphragm for lithium ion batteries, including a polymer porous base film, a polymer glue coated on one or both sides of the base film surface, a ceramic coating coated on the surface of the polymer glue, and PVDF and its copolymer glue coated on the surface of the ceramic coating and the other side of the base film surface. The ceramic coated diaphragm structure design of this invention can increase the bonding force between the ceramic coating and the polymer porous base film, improve the bonding strength between the diaphragm and the positive and negative electrodes, effectively improve the problems of powder loss and coating shedding, realize efficient automatic assembly of lithium batteries, and greatly improve the heat resistance and electrochemical stability of the diaphragm. However, the design of the multi-layer coating layer increases the thickness of the diaphragm, affects the weight and electrochemical performance of the battery cell, and also affects the air permeability of the diaphragm, reduces the lithium ion migration channel and rate, and the coating process is cumbersome and complicated, and the production efficiency is low.

[0005] Therefore, there is an urgent need to develop a highly viscous composite adhesive that can improve ionic conductivity. Summary of the invention

[0006] In view of the existing technical problems, the purpose of the present invention is to provide a high-viscosity composite adhesive and a preparation method thereof. The composite adhesive of the present invention plays a role in bonding battery separators, has good adhesion, high temperature resistance, flame retardancy and ionic conductivity, and has good market prospects.

[0007] In order to achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] On one hand, the present invention provides a high-viscosity composite adhesive, which comprises the following raw materials, by weight: 25-45 parts of aqueous adhesive, 20-35 parts of composite ceramic particles, 7-11 parts of PMMA composite microspheres, 1-2 parts of modified cellulose, 0.5-1 parts of wetting agent, and 45-60 parts of deionized water.

[0009] The reaction mechanism and effects of the present invention are as follows:

[0010] 1. Ceramic particles and binders work together to enhance the adhesion between the diaphragm and the battery pole piece, improving the overall performance and safety of the battery. However, most ceramic particles have poor dispersibility in polymer systems.

[0011] The present invention can improve the dispersibility of ceramic particles in the polymer system, enhance the adhesion and mechanical strength of the binder by using 3-methoxycatechol and diethylenetriamine to jointly modify silica, and the benzene ring structure can form π-π stacking to improve the high temperature stability of the binder, thereby further improving the ionic conductivity and the number of lithium ion migration; further, the applicant combines the product with short carboxylated single-walled carbon nanotubes through chemical bonds, avoiding the problem of poor dispersibility of carbon nanotubes; at the same time, the carbon nanotubes increase the gap between the silica particles, which helps to build a good gas transmission channel, improve the permeability of the diaphragm, and improve the lithium ion migration channel and rate. In addition, there is a strong polar force between the abundant polar functional groups on the surface of the composite ceramic particles and the lithium ions, which can strengthen the affinity with the polar electrolyte, which is conducive to the formation of a fast ion migration channel and improve the ionic conductivity of the diaphragm.

[0012] 2. The thermal stability of cellulose has certain limitations. Prolonged heating above 80°C may denature cellulose, resulting in a significant decrease in viscosity and performance, which is not conducive to the formation of a composite binder with good stability.

[0013] The present invention uses sodium catechol-3,5-disulfonate and 3-(2,5-dioxy-pyrroline-1-yl)-propionic acid to modify carboxymethyl cellulose. On the one hand, the introduction of imide rings and benzene ring structures into the cellulose skeleton achieves the improvement of the high temperature resistance of cellulose; the applicant adds a specific proportion of sodium catechol-3,5-disulfonate to make the substitution degree of sodium sulfonate good, and the appropriate sodium sulfonate group can not only improve the water solubility of the modified cellulose, but also avoid the possibility of hydrogen bonds between cellulose molecules being destroyed. At the same time, the introduction of sodium sulfonate groups can cause interchain effects through Coulomb forces and hydrogen bonds, thereby improving stability and thus improving thermal stability. On the other hand, the present invention selects a specific modified cellulose as a thickener. The modified cellulose forms a network structure through its own intermolecular forces or hydrogen bonds, which is beneficial to improving the bonding performance; in addition, the hydroxyl and sulfonic acid functional groups in the modified cellulose structure can form strong hydrogen bonds with other molecules, which helps to improve ionic conductivity.

[0014] In some embodiments, the aqueous binder is any one or more of a polyacrylic acid aqueous binder, a polyurethane aqueous binder, a polyacrylonitrile aqueous binder, and a polyacrylate aqueous binder.

[0015] In some embodiments, the method for preparing the composite ceramic particles comprises the following steps:

[0016] Q1. Mix silica, deionized water and N,N-dimethylformamide, treat with ultrasound, adjust the solution pH to 8-9, add 3-methoxycatechol and diethylenetriamine, heat to 40-60°C, stir for 20-30 minutes, let stand for reaction for 20-24 hours, centrifuge, filter and dry to obtain the product;

[0017] Q2. The product obtained in step Q1, carboxylated carbon nanotubes and N,N-dimethylformamide are mixed, ultrasonically treated, triethylamine is added, heated to 110-130°C, an inert gas is introduced, the reaction is stirred, cooled, distilled under reduced pressure, washed, filtered and dried to obtain composite ceramic particles.

[0018] In some embodiments, the mass ratio of silicon dioxide, 3-methoxycatechol and diethylenetriamine in step Q1 is 1:(2-3.5):(0.9-1.1).

[0019] In some embodiments, the mass ratio of the product in step Q2 to the carboxylated carbon nanotubes is 1:(0.5-0.9).

[0020] Preferably, the carbon nanotubes in step Q2 are short carboxylated single-walled carbon nanotubes.

[0021] In some embodiments, the method for preparing the modified cellulose comprises the following steps:

[0022] Carboxymethyl cellulose, sodium catechol-3,5-disulfonate, 3-(2,5-dioxy-pyrroline-1-yl)-propionic acid and dimethyl sulfoxide are mixed and stirred, 4-dimethylaminopyridine and N,N-dicyclohexylcarbodiimide are added, stirred to react, sodium hydroxide aqueous solution is added, stirred to precipitate, filtered, washed and dried to obtain modified cellulose.

[0023] In some embodiments, the mass ratio of the carboxymethyl cellulose, sodium catechol-3,5-disulfonate, and 3-(2,5-dioxy-pyrroline-1-yl)-propionic acid is 1:(1.7-2):(0.25-0.45).

[0024] In some embodiments, the method for preparing the PMMA composite microspheres comprises the following steps:

[0025] S1. Soak the PMMA microspheres with isopropanol and acetone, centrifuge, and take the precipitate to obtain pretreated PMMA microspheres for later use;

[0026] S2. The modified magnesium hydroxide was added to isopropanol, ultrasonicated, and then acetic acid and polyethylene glycol were added successively, ultrasonicated, and the upper suspension was taken to obtain a magnesium hydroxide suspension for later use;

[0027] S3. The pretreated PMMA microspheres obtained in step S1 are immersed in the magnesium hydroxide suspension obtained in step S2 under ultrasound, centrifuged, washed, and immersed 3-5 times repeatedly, dried, and ground to obtain PMMA composite microspheres.

[0028] In some embodiments, the wetting agent is a nonionic surfactant.

[0029] Preferably, the dynamic surface tension (25° C., 2 G / L) of the wetting agent is 32-34 MN / M.

[0030] Another aspect of the present invention provides a method for preparing a high-viscosity composite adhesive, comprising the following steps:

[0031] P1. The composite ceramic particles, modified cellulose and deionized water were mixed, stirred at a rate of 800-1200 rpm for 1-2 h, and ground to obtain a premix;

[0032] P2. The premix obtained in step P1, the aqueous adhesive and the wetting agent are mixed, stirred at a rate of 400-600 rpm for 40-80 min, PMMA composite microspheres are added, and stirred at a rate of 400-600 rpm for 20-40 min to obtain a composite adhesive.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] 1. The composite adhesive of the present invention plays the role of bonding battery separators, has good bonding properties, high temperature resistance, flame retardancy and ionic conductivity, and has good market prospects.

[0035] 2. The present invention can improve the dispersibility of ceramic particles in the polymer system by using 3-methoxycatechol and diethylenetriamine to modify silica, thereby improving ionic conductivity and high temperature resistance; further, the applicant combines the product with short carboxylated single-walled carbon nanotubes through chemical bonds, thereby avoiding the problem of poor dispersibility of carbon nanotubes; at the same time, the addition of carbon nanotubes improves the air permeability of the diaphragm. In addition, the abundant polar functional groups on the surface of the composite ceramic particles are conducive to improving ionic conductivity.

[0036] 3. The modified carboxymethyl cellulose of the present invention improves high temperature stability by introducing an imide ring structure, a benzene ring structure and a sulfonic acid group. At the same time, the modified cellulose forms a network structure through its own intermolecular force or hydrogen bond, which is beneficial to improving the bonding performance; in addition, the hydroxyl and sulfonic acid functional groups in the modified cellulose structure can form strong hydrogen bonds with other molecules, which helps to improve the ionic conductivity. DETAILED DESCRIPTION

[0037] The present invention will be described below in conjunction with specific embodiments. It should be noted that the following embodiments are examples of the present invention and are only used to illustrate the present invention, rather than to limit the present invention. Other combinations and various modifications within the concept of the present invention may be performed without departing from the spirit or scope of the present invention.

[0038] The composite adhesives were prepared according to the ratios of the raw materials and the preparation methods specified in the following examples and comparative examples.

[0039] In order to facilitate those skilled in the art to implement the present invention, some raw material manufacturers of the embodiments and comparative examples are described as follows:

[0040] Short carboxylation single-walled carbon nanotubes: purchased from Suzhou Kaifa New Material Technology Co., Ltd., model number szbknm2010;

[0041] Single-walled carbon nanotubes: purchased from Shanghai Gaibang Industrial Co., Ltd.

[0042] Carboxymethyl cellulose: purchased from Renqiu Shuangcheng Chemical Products Factory;

[0043] Water-based binder: polyacrylic acid, purchased from Wuhan Lanabai Pharmaceutical Chemical Co., Ltd.; wetting agent: purchased from Nanjing Baiju Technology Co., Ltd., model FB300;

[0044] PEG-1000: purchased from Shandong Baihua Chemical Co., Ltd.;

[0045] Polyvinyl pyrrolidone: purchased from Huzhou Shenhua Polymer Materials Co., Ltd., model K30;

[0046] Epoxy resin: purchased from Zhengzhou Wubaotong Trading Co., Ltd., brand CYDW-100;

[0047] Other raw materials are not specially specified and can be purchased from the market.

[0048] Preparation Example 1

[0049] The preparation method of composite ceramic particles A comprises the following steps:

[0050] Q1. 10 g of silica, 1 L of deionized water, and 500 mL of N,N-dimethylformamide were mixed, ultrasonically treated for 10 min, the pH value of the solution was adjusted to 8.5, 28 g of 3-methoxycatechol and 10 g of diethylenetriamine were added, heated to 50 ° C, stirred for 25 min, allowed to react for 24 h, centrifuged, filtered, and dried at 100 ° C for 24 h to obtain the product;

[0051] Q2. 5 g of the product obtained in step Q1, 3.5 g of short carboxylated single-walled carbon nanotubes, and 500 mL of N,N-dimethylformamide were mixed, ultrasonically treated for 15 min, and then 7.5 mL of triethylamine was added. The mixture was heated to 120 ° C, nitrogen was introduced, and the reaction was stirred for 6 h. The mixture was cooled to room temperature, distilled under reduced pressure, washed with deionized water for 3 times, filtered, and dried at 100 ° C for 24 h to obtain composite ceramic particles A.

[0052] Preparation Example 2

[0053] The preparation method of composite ceramic particles B is the same as that of Preparation Example 1, except that the amount of silicon dioxide added is 15 g.

[0054] Preparation Example 3

[0055] The preparation method of composite ceramic particles C is the same as that of Preparation Example 1, except that the amount of short carboxylated single-walled carbon nanotubes added is 2 g.

[0056] Preparation Example 4

[0057] The preparation method of modified cellulose A comprises the following steps:

[0058] 100 g of carboxymethyl cellulose, 185 g of sodium catechol-3,5-disulfonate, 35 g of 3-(2,5-dioxy-pyrroline-1-yl)-propionic acid, and 1800 mL of dimethyl sulfoxide were mixed and stirred for 1 h. 10 g of 4-dimethylaminopyridine and 25 g of N,N-dicyclohexylcarbodiimide were added and stirred at 30 ° C for 24 h. 0.05 mol / L of sodium hydroxide aqueous solution was added to adjust the pH to 9. The precipitate was stirred and precipitated, filtered, washed with anhydrous ethanol 3 times, and dried at 60 ° C to constant weight to obtain modified cellulose A.

[0059] Preparation Example 5

[0060] The preparation method of modified cellulose B is the same as that of Preparation Example 4, except that the amount of sodium catechol-3,5-disulfonate added is 150 g.

[0061] Preparation Example 6

[0062] The preparation method of modified cellulose C is the same as that of Preparation Example 4, except that the amount of 3-(2,5-dioxy-pyrrolidine-1-yl)-propionic acid added is 22 g.

[0063] Preparation Example 7

[0064] The preparation of PMMA composite microspheres includes the following steps:

[0065] S1. The PMMA microspheres were immersed in a mixed solution of isopropanol and acetone in a volume ratio of 2:1 for 2 minutes, centrifuged at 6000 r / min for 15 minutes, and the precipitate was obtained to obtain the pretreated PMMA microspheres for later use;

[0066] S2. 8g of modified magnesium hydroxide was added to 500ml of isopropanol, ultrasonicated at 400W power for 4h, and then 7.2g of acetic acid and 1.6g of PEG-1000 were added successively, ultrasonicated at 400W power for 4h, and the upper suspension was taken to obtain a magnesium hydroxide suspension for standby use;

[0067] S3. The pretreated PMMA microspheres obtained in step S1 are immersed in the magnesium hydroxide suspension obtained in step S2 under ultrasound for 6 minutes, centrifuged at 6000 r / min for 15 minutes, washed with deionized water twice, and the immersion process is repeated 4 times. The PMMA microspheres are dried at 60° C. to constant weight, and ground into powder to obtain PMMA composite microspheres.

[0068] Wherein, the preparation method of modified magnesium hydroxide comprises the following steps:

[0069] T1. 60 g of magnesium hydroxide, 90 g of water and 90 g of ethanol were added to the reactor in sequence, 3.6 g of vinyltrimethoxysilane was added dropwise, heated to 50 ° C, stirred for 12 h, filtered, washed with ethanol 3 times, dried at 80 ° C to constant weight, and ground to an average particle size of 0.5 μm to obtain an intermediate;

[0070] T2. 36 g of the intermediate obtained in step T1, 25.5 g of tricyclodecane dimethanol dimethacrylate, 6 g of 4-hydroxybutyl acrylate, 2.1 g of 2-methylbenzene butyrolactone, and 0.3 g of azobisisobutyronitrile were added to a reactor, heated to 75 ° C, reacted for 4 h, filtered, washed with deionized water 3 times, and dried at 105 ° C for 10 h to obtain modified magnesium hydroxide;

[0071] The preparation method of PMMA microspheres comprises the following steps:

[0072] R1. Add 1.8g polyvinyl pyrrolidone, 150ml ethanol and 50ml pure water into the reactor, stir for 15min, then add a mixture of 20g styrene, 15g methyl methacrylate, 9g N-methylacetamide and 6g hydroxyethyl methacrylate, heat to 65°C, stir for 30min, add 0.2g azobisisobutyronitrile, stir and react for 1.5h to obtain a core layer emulsion;

[0073] R2. Under the protection of nitrogen, 6 g of 2-hydroxyethyl acrylate, 1.5 g of β-(acryloyloxy) propionic acid, 3.6 g of ethylene glycol dimethacrylate, 0.9 g of hydroxymethyl acrylamide, 0.32 g of sodium dodecyl sulfate, and 0.16 g of epoxy resin were mixed and stirred thoroughly to obtain a shell emulsion; when the temperature of the reactor was raised to 80°C, 38 g of the core layer emulsion obtained in step R1 and 0.4 g of sodium persulfate were added, and the polymerization reaction was carried out for 24 hours to obtain PMMA microspheres.

[0074] Example 1

[0075] A high-viscosity composite adhesive, comprising the following raw materials, by weight: 35 parts of polyacrylic acid, 27.5 parts of composite ceramic particles A, 9 parts of PMMA composite microspheres, 1.5 parts of modified cellulose A, 0.75 parts of wetting agent FB-300, and 52 parts of deionized water;

[0076] The preparation method of the composite adhesive of this embodiment comprises the following steps:

[0077] P1. The composite ceramic particles A, modified cellulose A, and deionized water were mixed, stirred at a rate of 1000 rpm for 1.5 h, and ground to obtain a premix;

[0078] P2. The premix obtained in step P1, polyacrylic acid, and wetting agent FB-300 were mixed, stirred at a rate of 500 rpm for 60 min, PMMA composite microspheres were added, and stirred at a rate of 500 rpm for 30 min to obtain a composite adhesive.

[0079] Example 2

[0080] A high-viscosity composite adhesive, comprising the following raw materials, by weight: 25 parts of polyacrylic acid, 20 parts of composite ceramic particles A, 7 parts of PMMA composite microspheres, 1 part of modified cellulose A, 0.5 parts of wetting agent FB-3000, and 45 parts of deionized water;

[0081] The preparation method of the composite adhesive of this embodiment comprises the following steps:

[0082] P1. The composite ceramic particles A, modified cellulose A, and deionized water were mixed, stirred at a rate of 1200 rpm for 2 h, and ground to obtain a premix;

[0083] P2. The premix obtained in step P1, polyacrylic acid, and wetting agent FB-300 were mixed, stirred at a rate of 600 rpm for 40 min, PMMA composite microspheres were added, and stirred at a rate of 600 rpm for 20 min to obtain a composite adhesive.

[0084] Example 3

[0085] A high-viscosity composite adhesive, comprising the following raw materials, by weight: 45 parts of polyacrylic acid, 35 parts of composite ceramic particles A, 11 parts of PMMA composite microspheres, 2 parts of modified cellulose A, 1 part of wetting agent FB-300, and 60 parts of deionized water;

[0086] The preparation method of the composite adhesive of this embodiment comprises the following steps:

[0087] P1. The composite ceramic particles A, modified cellulose A, and deionized water were mixed, stirred at 800 rpm for 2 h, and ground to obtain a premix;

[0088] P2. The premix obtained in step P1, polyacrylic acid, and wetting agent FB-300 were mixed, stirred at a rate of 400 rpm for 80 min, PMMA composite microspheres were added, and stirred at a rate of 400 rpm for 40 min to obtain a composite adhesive.

[0089] Example 4

[0090] A high-viscosity composite adhesive and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that an equal amount of composite ceramic particles B is used to replace composite ceramic particles A.

[0091] Example 5

[0092] A high-viscosity composite adhesive and a preparation method thereof. The specific implementation method is the same as that of Example 1, except that an equal amount of composite ceramic particles C is used to replace composite ceramic particles A.

[0093] Example 6

[0094] A high-viscosity composite adhesive and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified cellulose B is used to replace modified cellulose A.

[0095] Example 7

[0096] A high-viscosity composite adhesive and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of modified cellulose C is used to replace modified cellulose A.

[0097] Comparative Example 1

[0098] A high-viscosity composite adhesive and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of commercially available single-walled carbon nanotube fibers is used to replace the composite ceramic particles A.

[0099] Comparative Example 2

[0100] A high-viscosity composite adhesive and a preparation method thereof. The specific implementation manner is the same as that of Example 1, except that an equal amount of commercially available carboxymethyl cellulose is used to replace modified cellulose A.

[0101] Effect evaluation:

[0102] The composite adhesives prepared in the above Examples 1-7 and Comparative Examples 1-2 were tested and analyzed, and the specific results are shown in Table 1.

[0103] Performance Test:

[0104] (1) Peel strength: By weight, the positive electrode sheet is prepared by mixing 200 parts of lithium manganese oxide + 150 parts of lithium iron phosphate + 10 parts of conductive carbon black + 16 parts of PVDF into a slurry, which is evenly coated on an aluminum foil. The positive electrode sheet and a polypropylene separator coated with a 2 μm thick binder are hot pressed at 85°C and 3 MPa for 60 seconds. After hot pressing, the samples are cut into 25 mm × 200 mm size samples, and the peel strength is tested using a KT-PSA-1056 peel force tester;

[0105] (2) Ionic conductivity: The membrane sample in (1) was made into a 2016 button cell with an electrolyte of EC:DEC=1:1 (v / v) and LiPF 6 The concentration of the electrolyte is 1 mol / L, and the AC impedance test in the electrochemical workstation is calculated according to the following formula:

[0106] σ=d / (R b ·S);

[0107] Where d is the sample thickness, R b is the body resistance, and S is the effective diaphragm area.

[0108] Table 1

[0109] Serial number Peel strength / MPa <![CDATA[Ionic conductivity / S·cm -1 > Example 1 192 <![CDATA[5.38×10 -4 ]]> Example 2 189 <![CDATA[5.27×10 -4 ]]> Example 3 190 <![CDATA[5.34×10 -4 ]]> Example 4 185 <![CDATA[5.17×10 -4 ]]> Example 5 188 <![CDATA[4.89×10 -4 ]]> Example 6 182 <![CDATA[5.19×10 -4 ]]> Example 7 178 <![CDATA[5.12×10 -4 ]]> Comparative Example 1 181 <![CDATA[4.09×10 -4 <!-- 6 -->]]> Comparative Example 2 165 <![CDATA[4.47×10 -4 ]]>

[0110] From the results in Table 1, it can be seen that the composite adhesives prepared in Examples 1-3 have good bonding properties and good ionic conductivity.

[0111] Examples 4-5 and Comparative Example 1 Compared with Example 1, when preparing composite ceramic particles, Example 4 changes the mass ratio of 3-methoxycatechol and diethylenetriamine, and the dispersibility of the product is weakened; Example 5 changes the mass ratio of the product and carboxylated carbon nanotubes, which affects the dispersibility and stability of the composite ceramic particles, affects the air permeability of the diaphragm, and thus reduces the ionic conductivity; Comparative Example 1 replaces composite ceramic particles A with an equal amount of commercially available single-walled carbon nanotube fibers, which has poor dispersibility and thus affects the ionic conductivity of the composite binder.

[0112] Compared with Example 1, in the preparation of modified cellulose, Examples 6-7 and Comparative Example 2 changed the mass ratio of carboxymethyl cellulose, sodium catechol-3,5-disulfonate, and 3-(2,5-dioxy-pyrroline-1-yl)-propionic acid, the cross-linking effect was weakened, and the active groups were reduced, both of which would affect the adhesion and ionic conductivity of the composite binder. Comparative Example 2 used an equal amount of commercially available carboxymethyl cellulose to replace modified cellulose A, which had weak cross-linking and poor stability, thereby affecting the adhesion and ionic conductivity of the composite binder.

[0113] The above is only a preferred embodiment of the present invention and does not constitute any form of limitation to the present application. Although the present application is disclosed as above in the preferred embodiment, it is not intended to limit the present application. Any technician familiar with the profession, without departing from the scope of the technical solution of the present application, using the technical content disclosed above to make slight changes or modifications are equivalent to equivalent implementation cases. However, any simple modifications, equivalent changes and modifications made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention are still within the scope of the technical solution.

Claims

1. A high-viscosity composite adhesive, characterized in that: The invention comprises the following raw materials by weight: 25-45 parts of aqueous adhesive, 20-35 parts of composite ceramic particles, 7-11 parts of PMMA composite microspheres, 1-2 parts of modified cellulose, 0.5-1 parts of wetting agent and 45-60 parts of deionized water.

2. A high-viscosity composite adhesive according to claim 1, characterized in that: The water-based binder is any one or more of a polyacrylic acid-based water-based binder, a polyurethane-based water-based binder, a polyacrylonitrile-based water-based binder, and a polyacrylate-based water-based binder.

3. A high-viscosity composite adhesive according to claim 1, characterized in that: The method for preparing the composite ceramic particles comprises the following steps: Q1. Mix silica, deionized water and N,N-dimethylformamide, treat with ultrasound, adjust the solution pH to 8-9, add 3-methoxycatechol and diethylenetriamine, heat to 40-60°C, stir for 20-30 minutes, let stand for reaction for 20-24 hours, centrifuge, filter and dry to obtain the product; Q2. The product obtained in step Q1, carboxylated carbon nanotubes and N,N-dimethylformamide are mixed, ultrasonically treated, triethylamine is added, heated to 110-130°C, an inert gas is introduced, the reaction is stirred, cooled, distilled under reduced pressure, washed, filtered and dried to obtain composite ceramic particles.

4. A high-viscosity composite adhesive according to claim 3, characterized in that: The mass ratio of silicon dioxide, 3-methoxycatechol and diethylenetriamine in step Q1 is 1:(2-3.5):(0.9-1.1).

5. A high-viscosity composite adhesive according to claim 3, characterized in that: The mass ratio of the product in step Q2 to the carboxylated carbon nanotubes is 1:(0.5-0.9).

6. The high-viscosity composite adhesive according to claim 1, characterized in that: The preparation method of the modified cellulose comprises the following steps: Carboxymethyl cellulose, sodium catechol-3,5-disulfonate, 3-(2,5-dioxy-pyrroline-1-yl)-propionic acid and dimethyl sulfoxide are mixed and stirred, 4-dimethylaminopyridine and N,N-dicyclohexylcarbodiimide are added, stirred to react, sodium hydroxide aqueous solution is added, stirred to precipitate, filtered, washed and dried to obtain modified cellulose.

7. A high-viscosity composite adhesive according to claim 6, characterized in that: The mass ratio of the carboxymethyl cellulose, sodium catechol-3,5-disulfonate and 3-(2,5-dioxy-pyrroline-1-yl)-propionic acid is 1:(1.7-2):(0.25-0.45).

8. The high-viscosity composite adhesive according to claim 1, characterized in that: The wetting agent is a nonionic surfactant.

9. The high-viscosity composite adhesive according to claim 1, characterized in that: The preparation method of the PMMA composite microspheres comprises the following steps: S1. Soak the PMMA microspheres with isopropanol and acetone, centrifuge, and take the precipitate to obtain pretreated PMMA microspheres for later use; S2. The modified magnesium hydroxide was added to isopropanol, ultrasonicated, and then acetic acid and polyethylene glycol were added successively, ultrasonicated, and the upper suspension was taken to obtain a magnesium hydroxide suspension for standby use; S3. The pretreated PMMA microspheres obtained in step S1 are immersed in the magnesium hydroxide suspension obtained in step S2 under ultrasound, centrifuged, washed, and immersed 3-5 times repeatedly, dried, and ground to obtain PMMA composite microspheres.

10. A method for preparing the high-viscosity composite adhesive according to any one of claims 1 to 9, characterized in that: The following steps are included: P1. The composite ceramic particles, modified cellulose and deionized water were mixed, stirred at a rate of 800-1200 rpm for 1-2 h, and ground to obtain a premix; P2. The premix obtained in step P1, the aqueous adhesive and the wetting agent are mixed, stirred at a rate of 400-600 rpm for 40-80 min, PMMA composite microspheres are added, and stirred at a rate of 400-600 rpm for 20-40 min to obtain a composite adhesive.