阅读说明：本技术 一种锂电池用丙烯酸类粘接剂及其制备、使用方法 (Acrylic adhesive for lithium battery and preparation and use methods thereof ) 是由 赵天宝 毛家容 陈宝书 李正秋 于 2021-08-27 设计创作，主要内容包括：本发明提供了一种锂电池用丙烯酸类粘接剂,包括丙烯酸类单体、第一功能单体、第二功能单体、引发剂、链转移剂、乳化剂和溶剂；丙烯酸类单体为丙烯酸、丙烯酸正丁酯、丙烯酸叔丁酯、甲基丙烯酸甲酯中的一种或多种；第一功能单体为烯丙基聚醚、二醇二丙烯酸酯、聚缩水甘油醚中的一种或多种；第二功能单体为丙烯腈或丙烯酸酰胺中的一种或两种。其能够提高粘接剂的粘接性能,用于锂电池隔膜涂覆改性。本发明还提供了这种丙烯酸类粘接剂的制备和使用方法,能够改善隔膜的综合性能。(The invention provides an acrylic acid adhesive for a lithium battery, which comprises an acrylic acid monomer, a first functional monomer, a second functional monomer, an initiator, a chain transfer agent, an emulsifier and a solvent, wherein the first functional monomer is a monomer with a first molecular weight; the acrylic monomer is one or more of acrylic acid, n-butyl acrylate, tert-butyl acrylate and methyl methacrylate; the first functional monomer is one or more of allyl polyether, glycol diacrylate and polyglycidyl ether; the second functional monomer is one or two of acrylonitrile or acrylamide. The adhesive can improve the adhesive property of the adhesive and is used for coating and modifying the lithium battery diaphragm. The invention also provides a preparation method and a using method of the acrylic adhesive, which can improve the comprehensive performance of the diaphragm.)

1. The acrylic adhesive for the lithium battery is characterized by comprising an acrylic monomer, a first functional monomer, a second functional monomer, an initiator, a chain transfer agent, an emulsifier and a solvent;

the acrylic monomer is one or more of acrylic acid, n-butyl acrylate, tert-butyl acrylate and methyl methacrylate;

the first functional monomer is one or more of allyl polyether, glycol diacrylate and polyglycidyl ether;

the second functional monomer is one or two of acrylonitrile or acrylamide.

2. The acrylic adhesive for a lithium battery as claimed in claim 1, which comprises the following components in parts by weight:

100 parts of acrylic monomer, 1-5.5 parts of initiator, 1-200 parts of chain transfer agent, 0.5-1 part of emulsifier, 10-20 parts of first functional monomer, 10-20 parts of second functional monomer and 250-420 parts of solvent.

3. The acrylic adhesive for a lithium battery as claimed in claim 1, wherein the acrylic monomer is an acrylic acid neutralized with an alkali.

4. The acrylic adhesive for lithium batteries according to claim 3, wherein said alkali is one or more of lithium carbonate, lithium bicarbonate and lithium hydroxide, and the amount of said neutralization alkali is 30 to 90% by mole of said acrylic monomer.

5. The acrylic adhesive for a lithium battery as claimed in claim 3, wherein the initiator is one or more of potassium persulfate, ammonium persulfate, and sodium bisulfite.

6. The acrylic adhesive for lithium batteries according to claim 3, wherein said chain transfer agent is one or more of n-dodecyl mercaptan, isopropyl alcohol, acetone, and sodium bisulfite.

7. The acrylic adhesive for lithium battery as claimed in claim 3, wherein the solvent is deionized water.

8. The method for preparing an acrylic adhesive for a lithium battery as claimed in any one of claims 1 to 2, comprising the steps of:

s1: weighing a functional monomer, an emulsifier and an acrylic monomer, fully stirring and uniformly mixing to obtain a mixed monomer;

s2: weighing an initiator, and fully dissolving the initiator in a solvent to obtain a mixed solution;

s3: weighing a chain transfer agent and a solvent, uniformly mixing and adding into a reaction kettle;

s4: weighing a mixed monomer which accounts for 10-20% of the total amount of the mixed monomer in the S1, weighing a mixed solution which accounts for 10-20% of the total amount of the mixed solution in the S2, uniformly mixing the weighed mixed monomer and the mixed solution, placing the mixture in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s5: and uniformly mixing the residual mixed monomer S1 and the mixed solution S2, slowly dripping the mixture into the reaction kettle, continuously stirring for reaction, and carrying out nitrogen protection to obtain the acrylic adhesive.

9. The method for preparing an acrylic adhesive for a lithium battery as claimed in any one of claims 3 to 7, comprising the steps of:

s1: weighing neutralizing alkali, slowly adding the neutralizing alkali into a proper amount of monomer acrylic acid, and continuously stirring in the adding process;

s2: weighing another or two types of acrylic acid monomers, functional monomers and an emulsifier, and fully stirring and uniformly mixing the acrylic acid monomers and the acrylic acid neutralized by alkali to obtain a mixed monomer;

s3: weighing an initiator, and fully dissolving the initiator in a solvent to obtain a mixed solution;

s4: weighing a chain transfer agent and a solvent, uniformly mixing and adding into a reaction kettle;

s5: weighing a mixed monomer which accounts for 10-20% of the total amount of the mixed monomer in the S2, weighing a mixed solution which accounts for 10-20% of the total amount of the mixed solution in the S3, uniformly mixing the weighed mixed monomer and the mixed solution, placing the mixture in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s6: and uniformly mixing the residual S2 mixed monomer and the S3 mixed solution, slowly dropwise adding the mixture into the reaction kettle, continuously stirring for reaction, and carrying out nitrogen protection to obtain the acrylic adhesive.

10. The use method of the acrylic adhesive for the lithium battery is characterized in that the acrylic adhesive obtained in the claim 8 or 9 is proportionally added with deionized water to be diluted to the required mass fraction, and then polyvinylidene fluoride powder and ceramic particles are added, mixed and dispersed uniformly, and the coating modification can be carried out on the lithium battery diaphragm.

Technical Field

The invention relates to the technical field of adhesives, and particularly relates to an acrylic adhesive for a lithium battery and a preparation method thereof.

Background

The lithium ion battery has the advantages of high energy density, excellent cycle life and the like, and is widely applied to a plurality of fields such as energy storage power stations, new energy traffic, smart power grids, portable electronic equipment and the like. The diaphragm is one of the important components of the lithium battery, is not conductive, mainly plays a role in separating a positive electrode from a negative electrode and preventing the two electrodes from being contacted to form short circuit, and can enable lithium ions to pass through to form a charge-discharge loop. Its performance affects the characteristics of battery internal resistance, charge and discharge rate, capacity, cycle and safety performance. The diaphragm with excellent performance plays an important role in improving the comprehensive performance of the battery.

Most of commercial lithium battery diaphragms are made of polypropylene (PP), Polyethylene (PE) and PP/PE materials, and the diaphragms are usually required to be coated and modified on the surfaces so as to improve the thermal stability of the diaphragms, reduce the high-temperature shrinkage rate and increase the wettability with electrolyte, thereby being beneficial to reducing the internal resistance of the lithium batteries, improving the charge and discharge rate and improving the safety performance. The separator is usually surface-coated with a binder, and conventional binders, such as polyvinylidene fluoride (PVDF), have high chemical stability but have the following disadvantages: (1) the bonding strength is relatively low, and structural collapse and powder falling are easy to occur in the charging and discharging processes of the battery; (2) swelling and dissolving in the organic electrolyte to form gel, so that the internal resistance of the battery is increased; (3) the reaction heat released by the chemical reaction with lithium is twice that of the fluorine-free adhesive, so that thermal runaway is easily caused; (4) when in use, N-methylpyrrolidone (NMP) which is an organic solvent is needed as a solvent; (5) the ionic conduction depends on the short-range chain motion of the polymer, the polymer is expected to have an amorphous structure and a lower glass transition temperature to meet the requirement of ionic conduction at normal temperature, and the semi-crystalline PVDF influences the conduction of lithium salt to a certain extent.

Therefore, PVDF is not an ideal environmentally friendly and efficient binder material for lithium batteries.

Polyacrylic acid (PAA) is a water-soluble amorphous polymer and has a chain-like cross-linked structure, contains a large number of carboxyl groups, and interacts with each other to form hydrogen bonds, thereby generating strong adhesion. Research reports at home and abroad show that the PAA adhesive applied to the electrode plate of the lithium battery is superior to the PVDF adhesive in the aspects of cycle performance, polarization degree, capacity retention rate and the like. However, the single use of PAA as the adhesive cannot meet the requirement of multifunctionalization, so the modification of the PAA adhesive is needed to better realize the improvement of the lithium ion conductivity of the diaphragm and the improvement of the comprehensive performance of the diaphragm.

Disclosure of Invention

The invention aims to provide a multifunctional acrylic adhesive for a lithium battery, which has the advantages of good adhesive property, strong stability and high lithium ion conductivity;

a second object of the present invention is to provide a method for preparing an acrylic adhesive for a lithium battery, which has the above-mentioned advantages.

The invention is realized by the following technical scheme:

an acrylic acid adhesive for a lithium battery comprises an acrylic acid monomer, a first functional monomer, a second functional monomer, an initiator, a chain transfer agent, an emulsifier and a solvent;

the acrylic monomer is one or more of acrylic acid, n-butyl acrylate, tert-butyl acrylate and methyl methacrylate;

the first functional monomer is one or more of allyl polyether, glycol diacrylate and polyglycidyl ether;

the second functional monomer is one or two of acrylonitrile or acrylamide.

Acrylic acid monomers are used as main monomers, polyacrylic acid is water-soluble amorphous polymer and is in a chain-shaped cross-linking structure, contains a large amount of carboxyl, and interacts with each other to form hydrogen bonds, so that strong adhesion is generated. The structure collapse and powder falling in the battery charging and discharging process are avoided.

The first functional monomer is provided with a polyoxyethylene ether group, and the hydrophilic polyoxyethylene ether group can form a thicker hydration layer on the surface of the emulsion particle, plays a role of a nonionic emulsifier and is beneficial to the polymerization reaction; the first functional monomer is copolymerized with the acrylic monomer to form a long branched chain on an acrylic main chain, so that entanglement among molecular chains is increased, toughness is improved, film-forming property is improved, and bonding strength is improved; the acrylic acid-COOH-modified epoxy resin has a chemical crosslinking effect with an acrylic monomer or realizes chemical crosslinking through a bifunctional group of the acrylic acid-COOH-modified epoxy resin, so that the bonding strength is effectively improved; the ionic conduction depends on the short-range chain segment motion of the polymer, a branched chain structure is introduced, the crystallization of the polymer is inhibited, an amorphous structure is increased, the ionic conduction requirement is met, and the lithium ion conductivity is improved.

The acrylonitrile and the acrylamide of the second functional monomer are high dielectric constant monomers, so that the carrier concentration of a system can be increased, and the conductivity of lithium ion can be effectively improved; and the ammonium ions of the second functional monomer and-COOH of the acrylic monomer form ionic bonds or own polar cyano groups, so that the adhesive strength can be improved in an auxiliary manner.

The first functional monomer and the second functional monomer cooperate with each other to form a three-dimensional network structure together with the acrylic monomer under the combined action of entanglement of long-chain branches, chemical crosslinking, ionic bonds and hydrogen bonds, so that the bonding strength of the adhesive is improved.

Further, the paint comprises the following components in parts by weight:

100 parts of acrylic monomer, 1-5.5 parts of initiator, 1-200 parts of chain transfer agent, 0.5-1 part of emulsifier, 10-20 parts of first functional monomer, 10-20 parts of second functional monomer and 250-420 parts of solvent.

Further, the paint comprises the following components in parts by weight:

100 parts of acrylic monomer, 4.5 parts of initiator, 4 parts of chain transfer agent, 0.5 part of emulsifier, 10 parts of first functional monomer, 15 parts of second functional monomer and 310 parts of solvent.

Further, the monomeric acrylic acid is acrylic acid after alkali neutralization.

The alkali neutralization can effectively reduce the polymerization reaction heat of the acrylic monomer, effectively avoid the occurrence of implosion in the polymerization process, and simultaneously introduce low-molecular cations, so that the electrostatic repulsion between carboxylate anions on an acrylic macromolecular chain can be balanced, the fluid performance of a polymerization product is improved, and the low viscosity can be obtained at a high shear rate, thereby facilitating the subsequent process operation. The polymerization reaction is carried out after the monomer acrylic acid is neutralized, thereby effectively avoiding the occurrence of side reaction of the polymer and improving the stability and the reproducibility of the reaction.

Further, the neutralizing alkali used for alkali neutralization is one or more of lithium carbonate, lithium bicarbonate and lithium hydroxide, and the using amount of the neutralizing alkali is 30-90% of the mole number of the monomer acrylic acid. The selected neutralizing alkali can perform alkali neutralization on monomer acrylic acid, improve the synthesis stability and the performance of the adhesive fluid, and simultaneously provide a lithium source, thereby being beneficial to providing the capacity of a lithium battery.

Further, the initiator is one or more of potassium persulfate, ammonium persulfate and sodium bisulfite.

Further, the chain transfer agent is one or more of n-dodecyl mercaptan, isopropanol, acetone and sodium bisulfite. The chain transfer agent selected by the invention has moderate molecular weight, is suitable for acrylic polymers with small dispersion coefficients, is convenient for adjusting the viscosity of the slurry and optimizing the coating process.

Further, the emulsifier is one of sodium dodecyl benzene sulfonate and sodium styrene sulfonate, and the using amount of the emulsifier is 0.5-1% of the weight fraction of the monomers.

Further, the solvent is deionized water. The invention uses deionized water as solvent under the condition of ensuring excellent bonding strength and electrochemical performance, and is more environment-friendly compared with organic solvent.

The preparation method of the acrylic adhesive for the lithium battery comprises the following preparation steps:

s1: weighing neutralizing alkali, slowly adding the neutralizing alkali into a proper amount of monomer acrylic acid, and continuously stirring in the adding process;

s2: weighing one or more other acrylic acid monomers, functional monomers and emulsifiers, and fully stirring and uniformly mixing the other one or more acrylic acid monomers, functional monomers and emulsifiers with the acrylic acid neutralized by alkali to obtain a mixed monomer;

s3: weighing an initiator, and fully dissolving the initiator in deionized water to obtain a mixed solution;

s4: weighing a chain transfer agent, uniformly mixing with deionized water, and adding into a reaction kettle;

s5: weighing a mixed monomer which accounts for 10-20% of the total amount of the mixed monomer in the S2, weighing a mixed solution which accounts for 10-20% of the total amount of the mixed solution in the S3, uniformly mixing the weighed mixed monomer and the mixed solution, placing the mixture in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s6: and uniformly mixing the residual mixed monomer and the mixed solution, slowly dripping the mixture into a reaction kettle, continuously stirring the mixture for reaction, and performing nitrogen protection to obtain the acrylic adhesive.

The application method of the acrylic adhesive for the lithium battery comprises the steps of adding deionized water into the obtained acrylic adhesive in proportion to dilute the acrylic adhesive to a required mass fraction, adding polyvinylidene fluoride powder and ceramic particles, mixing and dispersing uniformly, and then applying the mixture to coating modification of a lithium battery diaphragm.

The technical scheme of the invention at least has the following advantages and beneficial effects:

(1) the acrylic adhesive for the lithium battery, provided by the invention, contains long-chain branches which are easy to tangle, and under the actions of chemical crosslinking, ionic bonds and hydrogen bonds, the acrylic monomer, the first functional monomer and the second functional monomer form a three-dimensional network structure, so that the adhesive strength is improved, the defects of insufficient toughness of polyacrylic acid and brittle film forming are overcome, and the defects of structural collapse, powder falling and the like of a diaphragm in the use process of the lithium battery are avoided;

(2) according to the preparation method of the acrylic acid adhesive for the lithium battery, provided by the invention, the acrylic acid monomer is neutralized and then subjected to polymerization reaction, so that the occurrence of polymerization side reaction is effectively avoided, and the stability and the reproducibility of the reaction are improved;

(3) the preparation method of the acrylic acid adhesive for the lithium battery, provided by the invention, has the advantages of simple process, easiness in operation and suitability for actual production;

(4) the application method of the acrylic adhesive for the lithium battery can be used for coating and modifying the lithium battery diaphragm, so that the mechanical property of the diaphragm is improved, and the ionic conductivity is improved.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. The examples, in which specific conditions are not specified, were conducted under conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.

Example 1

The preparation method of the acrylic adhesive for the lithium battery comprises the following preparation steps:

s1: weighing lithium hydroxide which is 75% of the mole number of the monomer acrylic acid, slowly adding the lithium hydroxide into 60 parts by weight of the acrylic acid, and continuously stirring in the adding process;

s2: weighing 20 parts of methyl methacrylate, 20 parts of n-butyl acrylate, 10 parts of glycol diacrylate, 15 parts of acrylonitrile and 0.5 part of sodium dodecyl benzene sulfonate, and fully stirring and uniformly mixing the methyl methacrylate, the 20 parts of n-butyl acrylate, the 10 parts of glycol diacrylate and the 15 parts of acrylonitrile with acrylic acid neutralized by alkali to obtain a mixed monomer;

s3: weighing 1.5 parts of ammonium persulfate and 3 parts of sodium bisulfite, and fully dissolving in 300 parts of deionized water to obtain a mixed solution;

s4: weighing 4 parts of n-dodecyl mercaptan, uniformly mixing with 10 parts of deionized water, and adding into a reaction kettle;

s5: respectively weighing the mixed monomer and the mixed solution which account for 15% of the total amount obtained in S2 and S3, uniformly mixing, placing in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s6: and uniformly mixing the residual mixed monomer and the mixed solution, slowly dropwise adding the mixture into the reaction kettle, continuously stirring for reaction, and carrying out nitrogen protection to obtain a sample 1.

Example 2

The preparation method of the acrylic adhesive for the lithium battery comprises the following preparation steps:

s1: weighing 30% of lithium carbonate of the mole number of the monomer acrylic acid, slowly adding the lithium carbonate into 60 parts by weight of the acrylic acid, and continuously stirring in the adding process;

s2: weighing 40 parts of n-butyl acrylate, 20 parts of allyl polyether, 20 parts of acrylamide and 0.5 part of sodium styrene sulfonate, and fully stirring and uniformly mixing the n-butyl acrylate, the allyl polyether, the acrylamide and the sodium styrene sulfonate with acrylic acid neutralized by alkali to obtain a mixed monomer;

s3: weighing 2 parts of ammonium persulfate and 5 parts of sodium bisulfite, and fully dissolving in 300 parts of deionized water to obtain a mixed solution;

s4: weighing 200 parts of isopropanol, and adding into a reaction kettle;

s5: respectively weighing the mixed monomer and the mixed solution which account for 20% of the total amount obtained in S2 and S3, uniformly mixing, placing in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s6: and uniformly mixing the residual mixed monomer and the mixed solution, slowly dropwise adding the mixture into the reaction kettle, continuously stirring for reaction, and carrying out nitrogen protection to obtain a sample 2.

Example 3

The preparation method of the acrylic adhesive for the lithium battery comprises the following preparation steps:

s1: weighing 75% of lithium bicarbonate of the mole number of the monomer acrylic acid, slowly adding the lithium bicarbonate into 60 parts by weight of the acrylic acid, and continuously stirring in the adding process;

s2: weighing 40 parts of methyl methacrylate, 10 parts of polyglycidyl ether, 10 parts of acrylamide and 0.5 part of sodium dodecyl benzene sulfonate, and fully stirring and uniformly mixing the methyl methacrylate, the polyglycidyl ether, the acrylamide and the sodium dodecyl benzene sulfonate with the acrylic acid neutralized by alkali to obtain a mixed monomer;

s3: weighing 3 parts of ammonium persulfate, and sufficiently dissolving the ammonium persulfate in 300 parts of deionized water to obtain a mixed solution;

s4: weighing 200 parts of isopropanol, and adding into a reaction kettle;

s5: respectively weighing the mixed monomer and the mixed solution which account for 10% of the total amount obtained in S2 and S3, uniformly mixing, placing in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s6: and uniformly mixing the residual mixed monomer and the mixed solution, slowly dropwise adding the mixture into the reaction kettle, continuously stirring for reaction, and carrying out nitrogen protection to obtain a sample 3.

Comparative example 1

The preparation method of the acrylic adhesive for the lithium battery comprises the following preparation steps:

s1: weighing lithium hydroxide which is 75% of the mole number of the monomer acrylic acid, slowly adding the lithium hydroxide into 60 parts by weight of the acrylic acid, and continuously stirring in the adding process;

s2: weighing 20 parts of methyl methacrylate, 20 parts of n-butyl acrylate, 15 parts of acrylonitrile and 0.5 part of sodium dodecyl benzene sulfonate, and fully stirring and uniformly mixing the methyl methacrylate, the 20 parts of n-butyl acrylate, the 15 parts of acrylonitrile and the 0.5 part of sodium dodecyl benzene sulfonate with acrylic acid neutralized by alkali to obtain a mixed monomer;

s3: weighing 1.5 parts of ammonium persulfate and 3 parts of sodium bisulfite, and fully dissolving in 300 parts of deionized water to obtain a mixed solution;

s4: weighing 4 parts of n-dodecyl mercaptan, uniformly mixing with 10 parts of deionized water, and adding into a reaction kettle;

s5: respectively weighing the mixed monomer and the mixed solution which account for 15% of the total amount obtained in S2 and S3, uniformly mixing, placing in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s6: and uniformly mixing the residual mixed monomer and the mixed solution, slowly dropwise adding the mixture into the reaction kettle, continuously stirring for reaction, and carrying out nitrogen protection to obtain a sample 4.

Comparative example 2

The preparation method of the acrylic adhesive for the lithium battery comprises the following preparation steps:

s1: weighing lithium hydroxide which is 75% of the mole number of the monomer acrylic acid, slowly adding the lithium hydroxide into 60 parts by weight of the acrylic acid, and continuously stirring in the adding process;

s2: weighing 20 parts of methyl methacrylate, 20 parts of n-butyl acrylate, 10 parts of glycol diacrylate and 0.5 part of sodium dodecyl benzene sulfonate, and fully stirring and uniformly mixing the methyl methacrylate, the 20 parts of n-butyl acrylate, the 10 parts of glycol diacrylate and the 0.5 part of sodium dodecyl benzene sulfonate with acrylic acid neutralized by alkali to obtain a mixed monomer;

s3: weighing 1.5 parts of ammonium persulfate and 3 parts of sodium bisulfite, and fully dissolving in 300 parts of deionized water to obtain a mixed solution;

s4: weighing 4 parts of n-dodecyl mercaptan, uniformly mixing with 10 parts of deionized water, and adding into a reaction kettle;

s5: respectively weighing the mixed monomer and the mixed solution which account for 15% of the total amount obtained in S2 and S3, uniformly mixing, placing in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s5: and uniformly mixing the residual mixed monomer and the mixed solution, slowly dropwise adding the mixture into the reaction kettle, continuously stirring for reaction, and carrying out nitrogen protection to obtain a sample 5.

Comparative example 3

The preparation method of the acrylic adhesive for the lithium battery comprises the following preparation steps:

s1: weighing lithium hydroxide which is 75% of the mole number of the monomer acrylic acid, slowly adding the lithium hydroxide into 100 parts by weight of acrylic acid, and continuously stirring in the adding process;

s2: weighing 1.5 parts of ammonium persulfate, and fully dissolving the ammonium persulfate in 300 parts of deionized water to obtain a mixed solution;

s3: respectively weighing the mixed monomer and the mixed solution which account for 15% of the total amount obtained in S1 and S2, uniformly mixing, placing in a reaction kettle, stirring for reaction, and protecting with nitrogen;

s4: and uniformly mixing the residual mixed monomer and the mixed solution, slowly dropwise adding the mixture into the reaction kettle, continuously stirring for reaction, and carrying out nitrogen protection to obtain a sample 6.

Comparative example 4

Polyacrylic acid (PAA, CAS: 9003-01-4), available from Guangdong , Chemicals, Inc., was formulated with deionized water to give a mass fraction of adhesive as sample 7.

Comparative example 5

Polyvinylidene fluoride (PVDF powder, CAS: 24937-79-9) purchased from Guangdong chemical Co., Ltd was formulated into a binder in a mass fraction using N-methylpyrrolidone as a solvent, as sample 8.

Experimental example 1

Adding deionized water into the sample 1-7 until the mass fraction is 6%, adding polyvinylidene fluoride powder and ceramic particles, and uniformly mixing and dispersing; and adding N-methyl pyrrolidone into the sample 8 until the mass fraction is 6%, adding ceramic particles, and uniformly mixing and dispersing. Uniformly coating the samples 1-8 on a lithium battery diaphragm, and drying in a vacuum oven to obtain samples a-h. Samples a-h were cut into 20 × 100mm strips, and bond strength was tested by a 180 ° peel test using an electronic tensile machine at a constant speed of 300mm/min, and the test results are shown in the following table:

table 1 table of results of adhesion strength test

Serial number	Adhesive Strength (N/cm)
		Sample a	2.37
Sample b	2.03
		Sample c	2.08
Sample d	1.51
		Sample e	1.89
Sample f	0.83
		Sample g	1.19
Sample h	1.02

According to the test results, the following results are obtained:

the bonding strength of the samples a to c is obviously higher than that of the samples d to h, which shows that the monomer components selected by the invention and the using amount of the monomer components are very reasonable, the provided acrylic acid bonding agent for the lithium battery can improve the bonding performance of the bonding agent, improve the bonding strength, and can avoid the phenomena of diaphragm collapse and powder falling in practical application;

the adhesive strength of samples a-c is higher than that of samples g and h, which shows that the acrylic monomer selected for use in the invention is modified, and the adhesive performance of the adhesive is improved better than that of the commercial acrylic adhesive and the conventional polyvinylidene fluoride adhesive;

the bonding strength of the sample a is higher than that of the sample d, which shows that the first functional monomer and the dosage thereof are reasonable, and the chemical crosslinking and long-chain branched chain entanglement effects can effectively improve the bonding strength of the adhesive;

the bonding strength of the sample a is higher than that of the sample e, which shows that the second functional monomer selected by the invention can better play a role in synergy and assist in improving the bonding strength of the adhesive;

the lowest adhesive strength of the sample f indicates that neutralization of the acrylic adhesive is not beneficial to the adhesive performance, but the alkali neutralization is beneficial to improving the stability of polymerization reaction, improving the pulping process performance of the adhesive when in use, supplementing a lithium source and the like, and the selected monomer components and the dosage can better balance the contradiction, thereby showing more excellent multifunctional comprehensive performance.

Experimental example 2

Respectively punching samples a-h into phi 19mm circular sheets, fully soaking the circular sheets in an electrolyte solution for 6 hours, assembling the circular sheets into a stainless steel/diaphragm/stainless steel button cell, measuring alternating current impedance by using an electrochemical station, wherein the amplitude of alternating current perturbation is 5mv, the scanning frequency range is 100 KHz-0.1 Hz, calculating to obtain the ionic conductivity, and obtaining the test results shown in the following table:

TABLE 2 conductivity test results table

Serial number	Conductivity (S.cm)-1)
		Sample a	5.03×10-3
Sample b	4.79×10-3
		Sample c	4.33×10-3
Sample d	4.07×10-3
		Sample e	2.86×10-3
Sample f	8.17×10-4
		Sample g	3.62×10-4
Sample h	2.71×10-4

According to the test results, the following results are obtained:

compared with samples d-h, the conductivity of the samples a-c is obviously improved, which shows that the monomer components selected by the invention and the use amount of the monomer components are very reasonable, the provided acrylic adhesive for the lithium battery can effectively improve the conductivity of the adhesive, can effectively reduce the internal resistance of the battery in practical application, and is beneficial to improving the charge and discharge rate of the battery;

the electric conductivity of the samples a-c is higher than that of the samples g and h, which shows that the improvement of the lithium ion conductivity of the adhesive is better than that of the commercially available acrylic adhesive and the traditional PVDF adhesive by modifying the acrylic monomer selected by the invention;

the conductivity of the sample a is higher than that of the sample d, which shows that the first functional monomer selected by the invention and the dosage thereof are reasonable, and the introduced polyoxyethylene ether group is reacted with Li⁺Continuous complexation and decomplexing are beneficial to the transmission of lithium ions, and the conductivity of the adhesive is effectively improved;

the conductivity of the sample a is higher than that of the sample e, which shows that the second functional monomer with higher dielectric constant selected by the invention can effectively improve the conductivity of the adhesive;

the above is only a preferred embodiment of the present invention, and is not intended to limit the present invention, and various modifications and changes will occur to those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.