CN115838580B

CN115838580B - Polyimide binder and preparation method and application thereof

Info

Publication number: CN115838580B
Application number: CN202211478869.8A
Authority: CN
Inventors: 祝春才; 刘冰海
Original assignee: Zhejiang Zhongke Jiuyuan New Material Co Ltd
Current assignee: Zhejiang Zhongke Jiuyuan New Material Co Ltd
Priority date: 2022-11-22
Filing date: 2022-11-22
Publication date: 2024-07-30
Anticipated expiration: 2042-11-22
Also published as: CN115838580A

Abstract

A polyimide binder and its preparation method and application are provided. The invention discloses a polyimide binder, which comprises the following raw materials: triamine monomers, dianhydride monomers, adipic acid and urea copolymers. The invention also discloses a preparation method of the polyimide adhesive, which comprises the following steps: in an inert gas atmosphere, taking a triamine monomer and a dianhydride monomer to react in an organic solvent, then adding adipic acid and urea copolymer to continue to react to obtain a polyamic acid solution, then removing the solvent, and imidizing to obtain the polyimide binder. The invention also discloses application of the polyimide binder in a silicon-carbon anode material. The invention has good toughness and bonding performance, can solve the problem of large volume change of the silicon-carbon anode material in the charge and discharge process, and improves the electrochemical performance of the silicon-carbon anode material.

Description

Polyimide binder and preparation method and application thereof

Technical Field

The invention relates to the technical field of adhesives, in particular to a polyimide adhesive and a preparation method and application thereof.

Background

The lithium ion battery has the advantages of high energy density, low self-discharge rate, long cycle life and the like, and is widely applied to various electronic products. Currently, silicon is receiving increasing attention as one of the negative electrode materials of lithium ion batteries due to its high charge capacity. However, the high volume expansion of the silicon-carbon negative electrode tends to result in poor rate capability and shorter sequential life, which hinders the application of the silicon-carbon negative electrode of the lithium ion battery.

Disclosure of Invention

Based on the technical problems in the background art, the invention provides a polyimide binder, a preparation method and application thereof, and the polyimide binder has good toughness and binding property, can improve the problem of large volume change of a silicon-carbon negative electrode material in the charge-discharge process, and improves the electrochemical performance of the silicon-carbon negative electrode material.

The invention provides a polyimide binder, which comprises the following raw materials: triamine monomers, dianhydride monomers, adipic acid and urea copolymers.

Preferably, the molar ratio of the triamine monomer to the dianhydride monomer is 1:1.6-1.8.

Preferably, the adipic acid and urea copolymer is used in an amount of 5 to 10wt% based on the total weight of the triamine monomer and the dianhydride monomer.

Preferably, the molar ratio of adipic acid to urea is from 1:1.9 to 2.1.

Preferably, the weight average molecular weight of the adipic acid and urea copolymer is 800-1000.

Preferably, in the preparation process of the adipic acid and urea copolymer, adipic acid and urea are taken to react in an inert gas atmosphere to obtain the adipic acid and urea copolymer.

Preferably, the reaction temperature is 140-160 ℃ during the preparation of the adipic acid and urea copolymer.

Preferably, the reaction time is 3-4 hours during the preparation of the adipic acid and urea copolymer.

Preferably, in the preparation of the adipic acid and urea copolymer, the reaction solvent is N-methylpyrrolidone.

Preferably, the triamine monomer is 1,3, 5-tris (4-aminophenoxy) benzene or 1,3, 5-tris (4-amino-2-trifluoromethylphenoxy) benzene.

Preferably, the dianhydride monomer is 2,2' -bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride.

The invention also provides a preparation method of the polyimide adhesive, which comprises the following steps: in an inert gas atmosphere, taking a triamine monomer and a dianhydride monomer to react in an organic solvent, then adding adipic acid and urea copolymer to continue to react to obtain a polyamic acid solution, then removing the solvent, and imidizing to obtain the polyimide binder.

Preferably, the triamine monomer and the dianhydride monomer are reacted in an organic solvent for 4-6 hours at room temperature.

Preferably, the adipic acid and urea copolymer is added and the reaction is continued for 2-3 hours at room temperature.

Preferably, the imidization temperature is 210-230 ℃.

Preferably, the organic solvent is at least one of N-methylpyrrolidone, dimethylacetamide and N, N-dimethylformamide.

The invention also provides application of the polyimide binder in a silicon-carbon anode material.

The beneficial effects are that:

According to the invention, a triamine monomer is selected to react with a dianhydride monomer, so that polyimide forms a network structure, the molar ratio of adipic acid to urea is adjusted, so that an adipic acid and urea copolymer is blocked by amino groups and then participates in the reaction, a plurality of amino groups are introduced into polyimide, and the complexity of the network structure can be further improved by long chain segments of the adipic acid and urea copolymer;

The reticular structure of polyimide can greatly improve the strength and toughness of the adhesive and solve the problem of large volume change of the silicon-carbon anode material in the charge and discharge process; and 2,2' -bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride is selected as dianhydride monomer, so that the toughness of the adhesive can be further improved, and the expansion problem of the silicon-carbon anode material can be further inhibited; the introduced multiple amino groups can form strong hydrogen bonds with the silicon-carbon material, so that the binding force of the binder and the silicon-carbon material is greatly improved, and the problem of large volume change of the silicon-carbon negative electrode material in the charge-discharge process is solved;

according to the invention, from two aspects of forming a network structure and introducing a plurality of amino groups, the toughness and the bonding performance of the adhesive are improved, so that the adhesive can effectively inhibit the problem of expansion of the silicon-carbon material, and the electrochemical performance of the silicon-carbon anode material is improved.

Detailed Description

The technical scheme of the invention is described in detail through specific embodiments.

Example 1

A preparation method of polyimide binder comprises the following steps:

Adding 0.1mol of adipic acid and 0.19mol of urea into N-methylpyrrolidone, stirring and dissolving, heating to 160 ℃ under the protection of nitrogen, stirring and reacting for 3 hours, removing the N-methylpyrrolidone by reduced pressure evaporation, washing, and drying to obtain an adipic acid and urea copolymer with the weight average molecular weight of 800-1000;

adding 0.1mol of 1,3, 5-tris (4-aminophenoxy) benzene and 0.18mol of 2,2' -bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride into N-methylpyrrolidone to dissolve, stirring at room temperature for reaction for 4 hours, then adding 13.3g of adipic acid and urea copolymer to mix uniformly, and continuing to react at room temperature for 3 hours to obtain polyamic acid solution; then heating to 200 ℃ to remove N-methyl pyrrolidone, and heating to 210-230 ℃ to imidize to obtain the polyimide binder.

Example 2

A preparation method of polyimide binder comprises the following steps:

Adding 0.1mol of adipic acid and 0.21mol of urea into N-methylpyrrolidone, stirring and dissolving, heating to 140 ℃ under the protection of nitrogen, stirring and reacting for 4 hours, removing the N-methylpyrrolidone by reduced pressure evaporation, washing and drying to obtain adipic acid and urea copolymer with the weight average molecular weight of 800-1000;

Adding 0.1mol of 1,3, 5-tris (4-ammonia-2-trifluoromethyl phenoxy) benzene and 0.16mol of 2,2' -bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride into N-methylpyrrolidone to dissolve, stirring at room temperature for reaction for 6 hours, then adding 7.1g of adipic acid and urea copolymer to mix uniformly, and continuing to react at room temperature for 2 hours to obtain polyamic acid solution; then heating to 200 ℃ to remove N-methyl pyrrolidone, and heating to 210-230 ℃ to imidize to obtain the polyimide binder.

Example 3

A preparation method of polyimide binder comprises the following steps:

adding 0.1mol of adipic acid and 0.2mol of urea into N-methylpyrrolidone, stirring for dissolution, heating to 150 ℃ under the protection of nitrogen, stirring for 3.5 hours, removing the N-methylpyrrolidone by reduced pressure evaporation, washing, and drying to obtain an adipic acid and urea copolymer with a weight average molecular weight of 800-1000;

Adding 0.1mol of 1,3, 5-tris (4-aminophenoxy) benzene and 0.17mol of 2,2' -bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride into N-methylpyrrolidone to dissolve, stirring at room temperature for reaction for 5 hours, adding 9.6g of adipic acid and urea copolymer to mix uniformly, and continuing to react at room temperature for 2.5 hours to obtain polyamic acid solution; then heating to 200 ℃ to remove N-methyl pyrrolidone, and heating to 210-230 ℃ to imidize to obtain the polyimide binder.

Comparative example 1

Adipic acid and urea copolymer were not added, otherwise as in example 3.

Comparative example 2

The procedure of example 3 was repeated except that 2,2' -bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride was replaced with pyromellitic anhydride.

Comparative example 3

A preparation method of polyimide binder comprises the following steps:

Adipic acid and urea copolymer as in example 3,

Adding 0.1mol of 4,4 '-diaminodiphenyl ether and 0.2mol of 2,2' -bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride into N-methylpyrrolidone to dissolve, stirring at room temperature for reaction for 5 hours, adding 9.3g of adipic acid and urea copolymer to mix uniformly, and continuing to react at room temperature for 2.5 hours to obtain polyamic acid solution; then heating to 200 ℃ to remove N-methyl pyrrolidone, and heating to 210-230 ℃ to imidize to obtain the polyimide binder.

The binders prepared in examples 1-3 and comparative examples 1-3 were added to N-methylpyrrolidone, respectively, and stirred until dissolved to obtain 10wt% binder solution; then preparing negative electrode slurry according to the weight ratio of silicon-carbon active substances, acetylene black and binder of 8:1:1; uniformly scraping the cathode slurry on a copper foil, and drying the copper foil at 60 ℃ in vacuum to obtain a silicon carbon pole piece; and (3) taking the silicon-carbon electrode sheet as a negative electrode, taking the lithium sheet as a positive electrode, taking the EC and EMC (v/v=1:1) mixed solution of 1mol/L LiPF ₆ as an electrolyte solution, and assembling to obtain the button cell. The button cells prepared in the above examples and comparative examples were subjected to charge and discharge tests, and the results are shown in table 1.

TABLE 1 detection results

As can be seen from Table 1, the silicon-carbon negative plate prepared by the binder provided by the invention has good electrochemical performance, the expansion rate of the plate is small, and the volume expansion problem of the silicon-carbon negative plate can be improved.

The foregoing is only a preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any person skilled in the art, who is within the scope of the present invention, should make equivalent substitutions or modifications according to the technical scheme of the present invention and the inventive concept thereof, and should be covered by the scope of the present invention.

Claims

1. The polyimide adhesive is characterized by comprising the following raw materials: triamine monomers, dianhydride monomers, adipic acid and urea copolymers;

the molar ratio of the triamine monomer to the dianhydride monomer is 1:1.6-1.8;

the dosage of the adipic acid and the urea copolymer is 5-10wt% of the total weight of the triamine monomer and the dianhydride monomer;

the molar ratio of adipic acid to urea is 1:1.9-2.1;

The dianhydride monomer is 2,2' -bis [4- (3, 4-dicarboxyphenoxy) phenyl ] propane dianhydride.

2. The polyimide binder of claim 1, wherein the weight average molecular weight of the adipic acid and urea copolymer is 800-1000.

3. The polyimide binder according to claim 1, wherein in the preparation of the adipic acid-urea copolymer, adipic acid and urea are reacted in an inert gas atmosphere to obtain the adipic acid-urea copolymer.

4. A polyimide binder according to claim 3, characterized in that the reaction temperature is 140-160 ℃ during the preparation of the adipic acid and urea copolymer.

5. A polyimide binder according to claim 3, characterized in that the reaction time during the preparation of the adipic acid and urea copolymer is 3-4 hours.

6. A polyimide binder according to claim 3, wherein the reaction solvent is N-methylpyrrolidone in the preparation of the copolymer of adipic acid and urea.

7. The polyimide binder of claim 1 wherein the triamine monomer is 1,3, 5-tris (4-aminophenoxy) benzene or 1,3, 5-tris (4-amino-2-trifluoromethylphenoxy) benzene.

8. A method for preparing the polyimide adhesive according to any one of claims 1 to 7, comprising the steps of: in an inert gas atmosphere, taking a triamine monomer and a dianhydride monomer to react in an organic solvent, then adding adipic acid and urea copolymer to continue to react to obtain a polyamic acid solution, then removing the solvent, and imidizing to obtain the polyimide binder.

9. The method for preparing polyimide binder according to claim 8, wherein the triamine monomer and the dianhydride monomer are reacted in an organic solvent at room temperature for 4 to 6 hours.

10. The method for preparing polyimide binder according to claim 8, wherein adipic acid and urea copolymer are added and the reaction is continued at room temperature for 2-3 hours.

11. The method for preparing a polyimide binder according to claim 8, wherein the imidization temperature is 210 to 230 ℃.

12. The method for producing a polyimide adhesive according to claim 8, wherein the organic solvent is at least one of N-methylpyrrolidone, dimethylacetamide, and N, N-dimethylformamide.

13. Use of the polyimide binder according to any one of claims 1 to 7 in silicon-carbon negative electrode materials.