Preparation method of self-adaptive conductive ionic polyimide composite binder, lithium ion battery electrode plate and preparation method of lithium ion battery electrode plate

Abstract

The invention relates to a preparation method of a self-adaptive conductive ionic polyimide composite binder. The preparation method comprises the following steps: carrying out polycondensation on polyaromatic structure dicarboxylic anhydride, polyaromatic structure diamine, heteroatom flexible dicarboxylic anhydride, heteroatom flexible diamine, ionic characteristic dicarboxylic anhydride and ionic characteristic diamine in a polar solvent; respectively obtaining a high-strength polyamide acid solution, a high-elasticity polyamide acid solution and a polyamide acid solution with a conductive ion characteristic; uniformly mixing the obtained high-strength polyamide acid solution, the high-elasticity polyamide acid solution and the polyamide acid solution with the ion-conducting property to obtain a mixed solution; doping and uniformly mixing the mixed solution and a conductive substance to obtain a precursor solution, and performing imidization treatment on the precursor solution to obtain a finished product. The prepared multifunctional composite binder inherits high strength of polyimide, meanwhile, the problem that polyimide is too rigid is solved, the polyimide is endowed with the self-adaptive characteristic, and meanwhile the problem that polyimide is not conductive is solved through introduction of the conductive substance.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery technology, and particularly relates to a method for preparing an adaptive conductive and ion-conducting polyimide composite binder and a lithium-ion battery electrode sheet and its preparation method. Background Technology

[0002] In recent years, "carbon peaking" and "carbon neutrality" have become core issues in global economic development. While actively promoting the development of clean and renewable energy, countries are also vigorously advancing the application of new energy technologies. With their advantages of high energy density, long cycle life, fast charge / discharge performance, and environmental friendliness, lithium-ion batteries (LIBs) have been widely used in consumer electronics, electric vehicles, energy storage systems, and power tools, with the promotion of new energy vehicles being particularly prominent. Over the past decade, the driving range of new energy vehicles has increased from less than 300 kilometers to over 700 kilometers. This significant progress is mainly attributed to the continuous optimization and improvement of the performance of positive and negative electrode materials. Among many negative electrode materials, silicon-based materials, with their theoretical specific capacity of up to 4200 mAh g⁻¹, are considered the most promising negative electrode candidate for next-generation high-performance lithium-ion batteries. However, silicon undergoes significant volume expansion during charge and discharge, leading to electrode structure breakage and pulverization, which in turn causes the solid electrolyte interphase (SEI) film to rupture, ultimately resulting in rapid capacity decay and severely affecting the battery's cycle stability.

[0003] Developing high-performance binders is an effective means of ensuring electrode integrity during volume expansion. Compared to traditional binders, polyimide (PI) is a high-performance material with excellent mechanical strength and chemical stability, and its use as a binder has attracted widespread attention. It is worth noting that the rigid structural units on the PI molecular chain, including aromatic and imine rings, restrict its free volume, which together hinders the ionic / electronic conductivity of traditional polyimide materials. Therefore, achieving adaptive, high ionic and electronic conductivity, and high temperature resistance while maintaining the inherent structural stability of PI binders remains a key challenge. Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for preparing an adaptive conductive and ion-conducting polyimide composite adhesive.

[0005] The present invention also provides a method for preparing an adaptive conductive and ion-conducting polyimide composite adhesive.

[0006] The present invention also provides a lithium-ion battery electrode sheet.

[0007] The present invention also provides a method for preparing a lithium-ion battery electrode sheet.

[0008] A method for preparing an adaptive conductive and ion-conductive polyimide composite adhesive includes the following steps:

[0009] (1) Polyaromatic dicarboxylic acid anhydrides, polyaromatic diamines, heteroatom flexible dicarboxylic acid anhydrides and heteroatom flexible diamines, ion-conducting dicarboxylic acid anhydrides and ion-conducting diamines are polycondensed in polar solvents to obtain high-strength polyamic acid solutions, high-elasticity polyamic acid solutions, and ion-conducting polyamic acid solutions, respectively. The solid content of the high-strength polyamic acid solutions, high-elasticity polyamic acid solutions, and ion-conducting polyamic acid solutions is 5~25%.

[0010] (2) The high-strength polyamic acid solution, high-elasticity polyamic acid solution, and ion-conducting polyamic acid solution obtained in step (1) are mixed evenly in a mass ratio of 0.1~0.4:0.12~0.8:0.01~0.2 to obtain a mixed solution;

[0011] (3) The mixed solution obtained in step (2) is doped with a conductive substance and mixed evenly to obtain a precursor solution. The precursor solution is imidized to obtain the finished product. The mass ratio of solute to conductive substance in the mixed solution is 100:0.1~3.

[0012] Further, the polyaromatic dicarboxylic anhydride includes one or more of pyromellitic dianhydride, biphenyl dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, and 2,3,3',4'-biphenyltetracarboxylic dianhydride; the polyaromatic diamine includes one or more of 4,4'-diaminodiphenylmethane, p-phenylenediamine, 4,4''-diaminoterphenyl, and o-phenylenediamine.

[0013] Further, the heteroatom flexible dicarboxylic anhydride includes one or more of hexafluoroisopropylphthalic anhydride, 4,4-biphenyl ether dianhydride, 4,4'-thiodiphthalic anhydride, and 4,4'-(4,4'-isopropyldiphenoxy)bis(phthalic anhydride); the heteroatom flexible diamine includes one or more of 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, poly(dimethylsiloxane), bis(3-aminopropyl)-terminated, and 2,2-bis(aminoethoxy)propane.

[0014] Further, the ion-conducting diacid anhydride includes one or more of 3,3,4,4-diphenylsulfone tetracarboxylic dianhydride, 4,4'-(3,4-dicarboxyphenoxy)diphenylthiodianhydride, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride; the ion-conducting diamine includes one or more of diethylene glycol di(3-aminopropyl) ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, and 4,4'-diamino-5,5'-dimethyl-2,2'-biphenyl disulfonic acid.

[0015] The polar solvent includes one or more of N-dimethylformamide (DMF), N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP).

[0016] Furthermore, the conductive material is selected from one or more of carbon nanotubes, graphene, silver nanowires, and conductive carbon black.

[0017] Furthermore, in step (1), the molar ratio of diacid anhydride and diamine in polyaromatic diacid anhydride and polyaromatic diamine, heteroatom flexible diacid anhydride and heteroatom flexible diamine, and ion-conducting diacid anhydride and ion-conducting diamine is 1~1.15:1; in step (3), the concentration of the precursor solution is 0.05~0.3wt%, the imidization treatment temperature is 300℃, and the holding time is 1~3h.

[0018] A lithium-ion battery electrode sheet comprises a current collector and an active material layer; the active material layer includes a positive or negative electrode active material, a conductive agent, and a multifunctional polyimide binder as described in any one of claims 1 to 7; the positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt aluminum oxide, or lithium nickel cobalt manganese oxide ternary materials; the negative electrode active material includes one or more of carbon materials, silicon and its oxides, tin and its oxides, silicon-carbon composites, silicon-oxygen-carbon composites, or tin-carbon composites; the conductive agent includes one or more of conductive carbon black, conductive graphite, graphene, or carbon nanotubes; the mass percentage range of each component in the active material layer is: positive or negative electrode active material 70-95 wt%, conductive agent 0.5-20 wt%, multifunctional polyimide binder 0.5-10 wt%.

[0019] A method for preparing a lithium-ion battery electrode sheet, characterized by comprising the following steps:

[0020] (1) Take the precursor solution, positive or negative electrode active material, and conductive agent and stir them evenly to obtain the electrode slurry;

[0021] (2) The electrode paste is coated onto the current collector, imidized under vacuum or nitrogen atmosphere, and rolled to obtain lithium-ion battery electrode sheet.

[0022] Further, the viscosity of the electrode slurry is 500~20000 cP; in step (2), the coating thickness of the electrode slurry on the current collector is 50~150 μm; and the compaction density after rolling is 0.6~3 mg / cm³. 3 .

[0023] The beneficial effects of this invention are:

[0024] 1. The preparation method of the adaptive conductive and ion-conducting polyimide composite binder prepared in this invention inherits the high strength of polyimide while making up for the problem of polyimide being too rigid. By introducing segments with longer bond lengths and larger bond angles than traditional CC segments, the energy barrier for segment conformational changes is reduced, significantly improving the elasticity and deformation adaptability of the polymer and giving polyimide adaptive properties. At the same time, the introduction of conductive materials solves the problem of polyimide being non-conductive. By precisely controlling the proportion of conductive materials, the dual functions of conductivity and elasticity are achieved, which can effectively adapt to the volume expansion of electrode materials.

[0025] 2. Compared with traditional binders, the adaptive high-temperature resistant, conductive, and ion-conducting polyimide multifunctional composite binder of the present invention has superior ion-conducting / electronic-conducting properties due to the introduction of the ion-conducting groups to promote the rapid migration of Li⁺. This compensates for the shortcomings of traditional lithium-ion battery binders, increases ion and electronic conductivity, and reduces capacity decay.

[0026] 3. The preparation method of the adaptive conductive and ion-conducting polyimide composite binder of the present invention has structural diversity and is composed of multiple components. It can be customized by adjusting the ratio of the formula and according to different battery material systems and application scenarios.

[0027] 4. The preparation method of the adaptive conductive and ion-conducting polyimide composite adhesive of the present invention has a simple synthesis process, is easy to operate, and is suitable for industrialization. Detailed Implementation

[0028] Example 1: A method for preparing an adaptive conductive and ion-conductive polyimide composite adhesive, comprising the following steps:

[0029] (1) Polyaromatic diacid anhydrides and polyaromatic diamines, heteroatom flexible diacid anhydrides and heteroatom flexible diamines, and ion-conducting diacid anhydrides and ion-conducting diamines are polycondensed in polar solvents to obtain high-strength polyamic acid solutions, high-elasticity polyamic acid solutions, and ion-conducting polyamic acid solutions, respectively. The molar ratio of diacid anhydrides to diamines in polyaromatic diacid anhydrides and polyaromatic diamines, heteroatom flexible diacid anhydrides and heteroatom flexible diamines, and ion-conducting diacid anhydrides and ion-conducting diamines is 1:1. The solid content of both the high-elasticity polyamic acid solution and the ion-conducting polyamic acid solution is 5%; the polyaromatic diacid anhydrides include pyromellitic dianhydride; the polyaromatic diamines include 4,4'-diaminodiphenylmethane; the heteroatom flexible diacid anhydrides include hexafluoroisopropylphthalic anhydride; the heteroatom flexible diamines include 4,4'-diaminodiphenyl ether; the ion-conducting diacid anhydrides include 3,3,4,4-diphenylsulfone tetracarboxylic acid dianhydride; the ion-conducting diamines include diethylene glycol di(3-aminopropyl) ether; and the polar solvent includes N,N-dimethylformamide (DMF).

[0030] (2) The high-strength polyamic acid solution, the high-elasticity polyamic acid solution, and the ion-conducting polyamic acid solution obtained in step (1) are mixed evenly in a mass ratio of 0.1:0.12:0.01 to obtain a mixed solution;

[0031] (3) The mixed solution obtained in step (2) is doped with a conductive substance and mixed evenly to obtain a precursor solution. The precursor solution is imidized to obtain the finished product. The mass ratio of solute to conductive substance in the mixed solution is 100:0.1, the concentration of the precursor solution is 0.05wt%, the imidization treatment temperature is 300℃, and the holding time is 1h.

[0032] Example 2: A method for preparing an adaptive conductive and ion-conductive polyimide composite adhesive, comprising the following steps:

[0033] (1) Polyaromatic diacid anhydrides and polyaromatic diamines, heteroatom flexible diacid anhydrides and heteroatom flexible diamines, and ion-conducting diacid anhydrides and ion-conducting diamines were polycondensed in polar solvents to obtain high-strength polyamic acid solutions, high-elasticity polyamic acid solutions, and ion-conducting polyamic acid solutions, respectively. The molar ratio of diacid anhydrides to diamines in the polyaromatic diacid anhydrides and polyaromatic diamines, heteroatom flexible diacid anhydrides and heteroatom flexible diamines, and ion-conducting diacid anhydrides and ion-conducting diamines was 1.1:1. High-strength polyamic acid solutions... The solid content of the acid solution, the highly elastic polyamic acid solution, and the ion-conducting polyamic acid solution is 15%; the polyaromatic diacid anhydride includes biphenyl dianhydride; the polyaromatic diamine includes p-phenylenediamine; the heteroatom flexible diacid anhydride includes 4,4-biphenyl ether dianhydride; the heteroatom flexible diamine includes 1,4-bis(4-aminophenoxy)benzene; the ion-conducting diacid anhydride includes 4,4'-(3,4-dicarboxyphenoxy)diphenylthiodianhydride; the ion-conducting diamine includes 4,4'-diaminodiphenyl sulfone; the polar solvent includes NN-dimethylacetamide (DMAc);

[0034] (2) The high-strength polyamic acid solution, the high-elasticity polyamic acid solution, and the ion-conducting polyamic acid solution obtained in step (1) are mixed evenly in a mass ratio of 0.2:0.4:0.1 to obtain a mixed solution;

[0035] (3) The mixed solution obtained in step (2) is doped with a conductive substance and mixed evenly to obtain a precursor solution. The precursor solution is imidized to obtain the finished product. The mass ratio of solute to conductive substance in the mixed solution is 100:1, the concentration of the precursor solution is 0.1wt%, the imidization treatment temperature is 300℃, and the holding time is 2h.

[0036] Example 3: A method for preparing an adaptive conductive and ion-conductive polyimide composite adhesive, comprising the following steps:

[0037] (1) Polyaromatic diacid anhydrides and polyaromatic diamines, heteroatom flexible diacid anhydrides and heteroatom flexible diamines, and ion-conducting diacid anhydrides and ion-conducting diamines were polycondensed in polar solvents to obtain high-strength polyamic acid solutions, high-elasticity polyamic acid solutions, and ion-conducting polyamic acid solutions, respectively. The molar ratio of diacid anhydrides to diamines in polyaromatic diacid anhydrides and polyaromatic diamines, heteroatom flexible diacid anhydrides and heteroatom flexible diamines, and ion-conducting diacid anhydrides and ion-conducting diamines was 1.15:1. The high-strength polyamic acid solutions and high-elasticity polyamic acid solutions were all polyamic acid solutions. The solid content of both the solution and the ion-conducting polyamic acid solution is 25%; the polyaromatic diacid anhydride includes perylene-3,4,9,10-tetracarboxylic acid dianhydride; the polyaromatic diamine includes 4,4''-diaminoterphenyl; the heteroatom flexible diacid anhydride includes 4,4'-thiophthalic anhydride; the heteroatom flexible diamine includes poly(dimethylsiloxane), bis(3-aminopropyl)-terminated; the ion-conducting diacid anhydride includes 3,3',4,4'-benzophenone tetracarboxylic acid dianhydride; the ion-conducting diamine includes 4,4'-diaminodiphenyl sulfide; the polar solvent includes dimethyl sulfoxide (DMSO).

[0038] (2) The high-strength polyamic acid solution, the high-elasticity polyamic acid solution, and the ion-conducting polyamic acid solution obtained in step (1) are mixed evenly in a mass ratio of 0.4: 0.8: 0.2 to obtain a mixed solution;

[0039] (3) The mixed solution obtained in step (2) is doped with a conductive substance and mixed evenly to obtain a precursor solution. The precursor solution is imidized to obtain the finished product. The mass ratio of solute to conductive substance in the mixed solution is 100:3, the concentration of the precursor solution is 0.3wt%, the imidization treatment temperature is 300℃, and the holding time is 3h.

[0040] Example 4: Referring to Example 1, the polyaromatic dicarboxylic anhydride includes one or more of pyromellitic dianhydride, biphenyl dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, and 2,3,3',4'-biphenyltetracarboxylic dianhydride; the polyaromatic diamine includes one or more of 4,4'-diaminodiphenylmethane, p-phenylenediamine, 4,4''-diaminoterphenyl, and o-phenylenediamine. Heteroatom flexible dicarboxylic anhydrides include one or more of hexafluoroisopropylphthalic anhydride, 4,4-biphenyl ether dianhydride, 4,4'-thiodiphthalic anhydride, and 4,4'-(4,4'-isopropyldiphenoxy)bis(phthalic anhydride); heteroatom flexible diamines include one or more of 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, poly(dimethylsiloxane), bis(3-aminopropyl)-terminated, and 2,2-bis(aminoethoxy)propane. The ion-conducting diacid anhydrides include one or more of 3,3,4,4-diphenylsulfone tetracarboxylic dianhydride, 4,4'-(3,4-dicarboxyphenoxy)diphenylthiodianhydride, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride; the ion-conducting diamines include one or more of diethylene glycol di(3-aminopropyl) ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, and 4,4'-diamino-5,5'-dimethyl-2,2'-biphenyl disulfonic acid. The polar solvents include one or more of N,N-dimethylformamide (DMF), N,N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP); the conductive materials are selected from one or more of carbon nanotubes, graphene, silver nanowires, and conductive carbon black.

[0041] Comparative Example 1: Referring to Example 1, in step (1), polyaromatic dicarboxylic anhydride and polyaromatic diamine are polycondensed in a polar solvent to obtain a high-strength polyamic acid solution; step (2) is omitted, and in step (3), the high-strength polyamic acid solution obtained in step (1) is directly doped with a conductive material and mixed evenly to obtain a precursor solution, with other steps remaining unchanged.

[0042] Comparative Example 2: Polyacrylic acid and deionized water were mixed to form a 5% solids solution to create an adhesive.

[0043] To better demonstrate the performance of the adhesive, we conducted tensile property tests on Examples 1-3 and Comparative Examples 1 and 2. The elongation at break in Example 1 was 32%, in Example 2 it was 75%, and in Example 3 it was 120%. The study shows that the elongation at break gradually increases with the increasing proportion of the high-elastic component. Comparative Example 1, lacking the high-elastic component, had an elongation at break of only 15%, while the traditional polyacrylic acid adhesive exhibited brittleness with an elongation at break of only 1%. The high elongation at break indicates effective adaptation to the volume expansion of the silicon anode, thereby ensuring the integrity of the electrode structure.

[0044] Example 5: A lithium-ion battery electrode sheet, comprising a current collector and an active material layer, wherein the active material layer comprises a positive electrode active material, a conductive agent, and a multifunctional polyimide binder prepared in Example 1; the positive electrode active material includes lithium cobalt oxide; the conductive agent includes conductive carbon black; the mass percentage range of each component in the active material layer is: positive electrode active material 70 wt%, conductive agent 20 wt%, multifunctional polyimide binder 10 wt%.

[0045] Example 6: A lithium-ion battery electrode sheet, comprising a current collector and an active material layer; the active material layer includes a negative electrode active material, a conductive agent, and a multifunctional polyimide binder prepared in Example 2; the negative electrode active material includes carbon materials; the conductive agent includes conductive graphite; the mass percentage range of each component in the active material layer is: negative electrode active material 95 wt%, conductive agent 0.5 wt%, and multifunctional polyimide binder 4.5 wt%.

[0046] Example 7: A lithium-ion battery electrode sheet, comprising a current collector and an active material layer; the active material layer includes a positive electrode active material, a conductive agent, and a multifunctional polyimide binder prepared in Example 3; the positive electrode active material includes lithium manganese oxide; the conductive agent includes graphene; the mass percentage range of each component in the active material layer is: positive electrode active material 89.5 wt%, conductive agent 10 wt%, multifunctional polyimide binder 0.5 wt%.

[0047] Example 8: Referring to Example 5, the active material layer comprises a positive or negative electrode active material, a conductive agent, and the multifunctional polyimide binder prepared in Example 1; the positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt aluminum oxide, or lithium nickel cobalt manganese oxide ternary materials; the negative electrode active material includes one or more of carbon materials, silicon and its oxides, tin and its oxides, silicon-carbon composites, silicon-oxygen-carbon composites, or tin-carbon composites; the conductive agent includes one or more of conductive carbon black, conductive graphite, graphene, or carbon nanotubes.

[0048] Comparative Example 3: Referring to Example 6, the multifunctional polyimide adhesive prepared in Example 2 of Example 6 was replaced with the multifunctional polyimide adhesive prepared in Comparative Document 1.

[0049] Comparative Example 4: Referring to Example 6, the multifunctional polyimide adhesive prepared in Example 2 of Example 6 was replaced with the adhesive prepared in Comparative Document 2.

[0050] Example 9: A method for preparing a lithium-ion battery electrode sheet, comprising the following steps:

[0051] (1) Take the precursor solution, positive electrode active material and conductive agent from Example 1 and Example 5, stir them evenly to obtain electrode slurry, and the viscosity of the electrode slurry is 500~20000 cP;

[0052] (2) The electrode slurry was coated onto the current collector, imidized under a vacuum atmosphere, and rolled to obtain a lithium-ion battery electrode sheet. The coating thickness of the electrode slurry on the current collector was 50 μm; the compaction density after rolling was 0.6 mg / cm³. 3 .

[0053] Example 10: A method for preparing a lithium-ion battery electrode sheet, comprising the following steps:

[0054] (1) Take the precursor solution, negative electrode active material and conductive agent from Example 2 and Example 6 and stir them evenly to obtain an electrode slurry with a viscosity of 500~20000 cP;

[0055] (2) The electrode slurry was coated onto the current collector, imidized under a nitrogen atmosphere, and rolled to obtain a lithium-ion battery electrode sheet. The coating thickness of the electrode slurry on the current collector was 100 μm; the compaction density after rolling was 2 mg / cm³. 3 .

[0056] Example 11: A method for preparing a lithium-ion battery electrode sheet, comprising the following steps:

[0057] (1) Take the precursor solution, positive electrode active material and conductive agent from Example 3 and Example 7, stir them evenly to obtain electrode slurry, and the viscosity of the electrode slurry is 500~20000 cP;

[0058] (2) The electrode slurry was coated onto the current collector, imidized under a vacuum atmosphere, and rolled to obtain a lithium-ion battery electrode sheet. The coating thickness of the electrode slurry on the current collector was 150 μm; the compaction density after rolling was 3 mg / cm³. 3 .

[0059] Comparative Example 5: Referring to Example 10, the phrase "take the precursor solution, negative electrode active material, and conductive agent from Example 2 and Example 6, stir them evenly to obtain an electrode slurry" was changed to "take the precursor solution, negative electrode active material, and conductive agent from Comparative Example 1 and Comparative Example 3, stir them evenly to obtain an electrode slurry".

[0060] Comparative Example 6: Referring to Example 10, the phrase "take the precursor solution, negative electrode active material, and conductive agent from Example 2 and Example 6 and stir them evenly to obtain an electrode slurry" was changed to "take the precursor solution, negative electrode active material, and conductive agent from Comparative Example 2 and Comparative Example 4 and stir them evenly to obtain an electrode slurry".

[0061] To investigate the effect of the prepared functional binder on electrochemical performance, we assembled batteries in Example 10, Comparative Example 5, and Comparative Example 6 and tested their electrochemical performance. The experimental results showed that the battery prepared in Example 10 retained 92.5% of its capacity after 100 cycles at 1C, while the capacity retention of Comparative Example 5 was 85.3% and that of Comparative Example 1 was 80.2%, demonstrating that the prepared multifunctional polyimide binder can effectively improve electrochemical stability.

[0062] The present invention will be further described below with reference to embodiments. The description of the embodiments below is only for the purpose of helping to understand the present invention. It should be noted that those skilled in the art can make several modifications to the present invention without departing from the principle of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A method for preparing an adaptive conductive and ion-conductive polyimide composite adhesive, characterized in that, Includes the following steps: (1) Polyaromatic dicarboxylic acid anhydrides, polyaromatic diamines, heteroatom flexible dicarboxylic acid anhydrides and heteroatom flexible diamines, ion-conducting dicarboxylic acid anhydrides and ion-conducting diamines are polycondensed in polar solvents to obtain high-strength polyamic acid solutions, high-elasticity polyamic acid solutions, and ion-conducting polyamic acid solutions, respectively. The solid content of the high-strength polyamic acid solutions, high-elasticity polyamic acid solutions, and ion-conducting polyamic acid solutions is 5~25%. (2) The high-strength polyamic acid solution, high-elasticity polyamic acid solution, and ion-conducting polyamic acid solution obtained in step (1) are mixed evenly in a mass ratio of 0.1~0.4:0.12~0.8:0.01~0.2 to obtain a mixed solution; (3) The mixed solution obtained in step (2) is doped with a conductive substance and mixed evenly to obtain a precursor solution. The precursor solution is imidized to obtain the finished product. The mass ratio of solute to conductive substance in the mixed solution is 100:0.1~3.

2. The preparation method of the adaptive conductive and ion-conductive polyimide composite adhesive according to claim 1, characterized in that, The polyaromatic dicarboxylic anhydride includes one or more of pyromellitic dianhydride, biphenyl dianhydride, perylene-3,4,9,10-tetracarboxylic dianhydride, and 2,3,3',4'-biphenyltetracarboxylic dianhydride; the polyaromatic diamine includes one or more of 4,4'-diaminodiphenylmethane, p-phenylenediamine, 4,4''-diaminoterphenyl, and o-phenylenediamine.

3. The preparation method of the adaptive conductive and ion-conductive polyimide composite adhesive according to claim 1, characterized in that, The heteroatom flexible dicarboxylic anhydride includes one or more of hexafluoroisopropylphthalic anhydride, 4,4-biphenyl ether dianhydride, 4,4'-thiodiphthalic anhydride, and 4,4'-(4,4'-isopropyldiphenoxy)bis(phthalic anhydride); the heteroatom flexible diamine includes one or more of 4,4'-diaminodiphenyl ether, 1,4-bis(4-aminophenoxy)benzene, poly(dimethylsiloxane), bis(3-aminopropyl)-terminated, and 2,2-bis(aminoethoxy)propane.

4. The preparation method of the adaptive conductive and ion-conductive polyimide composite adhesive according to claim 1, characterized in that, The ion-conducting diacid anhydride includes one or more of 3,3,4,4-diphenylsulfone tetracarboxylic dianhydride, 4,4'-(3,4-dicarboxyphenoxy)diphenylthiodianhydride, and 3,3',4,4'-benzophenone tetracarboxylic dianhydride; the ion-conducting diamine includes one or more of diethylene glycol di(3-aminopropyl) ether, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl sulfide, and 4,4'-diamino-5,5'-dimethyl-2,2'-biphenyl disulfonic acid.

5. The method for preparing the adaptive conductive and ion-conductive polyimide composite adhesive according to claim 1, characterized in that, The polar solvent includes one or more of N-dimethylformamide (DMF), N-dimethylacetamide (DMAc), dimethyl sulfoxide (DMSO), and N-methylpyrrolidone (NMP).

6. The method for preparing the adaptive conductive and ion-conductive polyimide composite adhesive according to claim 1, characterized in that, The conductive material is selected from one or more of carbon nanotubes, graphene, silver nanowires, and conductive carbon black.

7. The method for preparing the adaptive conductive and ion-conductive polyimide composite adhesive according to claim 1, characterized in that, In step (1), the molar ratio of diacid anhydride to diamine in polyaromatic diamine, heteroatom flexible diacid anhydride and heteroatom flexible diamine, and ion-conducting diacid anhydride and ion-conducting diamine is 1~1.15:1; in step (3), the concentration of the precursor solution is 0.05~0.3wt%, the imidization treatment temperature is 300℃, and the holding time is 1~3h.

8. A lithium-ion battery electrode sheet, characterized in that, It is composed of a current collector and an active material layer; the active material layer includes a positive or negative electrode active material, a conductive agent, and a multifunctional polyimide binder as described in any one of claims 1 to 7; the positive electrode active material includes one or more of lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate, lithium manganese iron phosphate, lithium nickel cobalt aluminum oxide, or lithium nickel cobalt manganese oxide; the negative electrode active material includes one or more of carbon materials, silicon and its oxides, tin and its oxides, silicon-carbon composites, silicon-oxygen-carbon composites, or tin-carbon composites; the conductive agent includes one or more of conductive carbon black, conductive graphite, graphene, or carbon nanotubes; the mass percentage range of each component in the active material layer is: positive or negative electrode active material 70-95 wt%, conductive agent 0.5-20 wt%, multifunctional polyimide binder 0.5-10 wt%.

9. A method for preparing a lithium-ion battery electrode sheet as described in claim 8, characterized in that, Includes the following steps: (1) Take the precursor solution, positive or negative electrode active material and conductive agent and stir them evenly to obtain electrode slurry; (2) The electrode paste is coated onto the current collector, imidized under vacuum or nitrogen atmosphere, and rolled to obtain lithium-ion battery electrode sheet.

10. The method for preparing a lithium-ion battery electrode sheet according to claim 9, characterized in that, The electrode slurry has a viscosity of 500~20000 cP; in step (2), the coating thickness of the electrode slurry on the current collector is 50~150 μm; the compacted density after roller pressing is 0.6~3 mg / cm³. 3 .