High-compaction dispersion material, preparation method thereof and high-compaction flexible positive pole piece

Abstract

The invention belongs to the technical field of lithium ion battery additive materials, and particularly relates to a high-compaction dispersion material and a preparation method thereof, and a high-compaction flexible positive pole piece, the high-compaction dispersion material comprises the following components by mass: 30-40 parts of a component A, 5-10 parts of a component B, 5-10 parts of a component C, and 40-60 parts of a solvent; wherein the component A comprises an unsaturated cyclic monomer, unsaturated polyether and a solution polymerization copolymer of an amine-containing monomer and a (methyl) acrylate monomer; the component B comprises a long-chain amine substance; the component C comprises organic ester; the high-compaction dispersion material, the preparation method thereof and the high-compaction flexible positive pole piece have the advantages of being excellent in dispersion performance, outstanding in softening effect, remarkable in pole piece compaction density improvement and the like, can have the two functions of dispersion and compaction improvement, reduces the production cost, improves the pole piece yield and has a good application prospect.

Description

Technical Field

[0001] The invention belongs to the technical field of lithium ion battery auxiliary materials, and specifically relates to a high-density dispersed material and a preparation method thereof, and a high-density flexible positive electrode sheet. Background Art

[0002] In recent years, with the vigorous development of the domestic new energy vehicle industry, the lithium-ion battery, as the heart of new energy vehicles, has become increasingly mature, and the industry competition has become increasingly fierce. Lithium battery companies have an urgent need to increase the energy density of single cells and reduce costs. Lithium batteries are generally composed of positive electrodes, negative electrodes, electrolytes and diaphragms. Without changing the existing structure and material system of the battery, a higher density positive electrode helps to increase the battery capacity and reduce the internal resistance of the electrode, thereby increasing the energy density of the battery cell.

[0003] The production of positive electrode sheets is generally divided into the steps of slurry preparation, coating, drying, rolling and slitting. The increase in the compaction density of the sheet requires the rolling equipment to provide greater pressure, which in turn causes the sheet to become brittle and easy to break, which brings huge challenges to the rolling equipment and battery production stability. In order to improve production efficiency and sheet yield, lithium battery companies generally prepare positive electrode slurry by adding dispersed materials.

[0004] However, existing dispersing materials can solve the dispersion problem of positive electrode slurry, but it is difficult to solve the need for high compaction and flexibility of the electrode. How to develop a dispersing material that can improve the compaction density has become a technical problem that urgently needs to be solved in this field.

[0005] It should be noted that the above information disclosed in this background technology section is only used to understand the background technology of the present application concept, and therefore, the above description is not considered to constitute information of the prior art. Summary of the invention

[0006] The embodiments of the present disclosure at least provide a high-compacted dispersion material and a preparation method thereof, and a high-compacted flexible positive electrode plate.

[0007] In the first aspect, the embodiments of the present disclosure provide a high-density dispersion material, which includes the following components in parts by mass: 30-40 parts of component A, 5-10 parts of component B, 5-10 parts of component C, and 40-60 parts of solvent; wherein the component A includes a solution-polymerized copolymer of an unsaturated cyclic monomer, an unsaturated polyether, an amine-containing monomer and a (meth)acrylate monomer; the component B includes a long-chain amine substance; and the component C includes an organic ester.

[0008] In an optional embodiment, the mass ratio of the unsaturated cyclic monomer, the unsaturated polyether, the amine-containing monomer and the (meth)acrylate monomer is (3-6):1:(2-4):(1-2).

[0009] In an alternative embodiment, the unsaturated cyclic monomer comprises any one or a combination of styrene, methylstyrene, vinylpyridine, N-vinylpyrrolidone, etc.

[0010] In an alternative embodiment, the unsaturated polyether comprises any one or a combination of allyl polyether APEG-500, allyl polyether APEG-800, allyl polyether APEG-1000, allyl polyether APEG-1500, allyl polyether APEG-2000; In an alternative embodiment, the amine-containing monomer comprises any one or a combination of acrylamide, N,N-dimethylacrylamide, isopropylacrylamide, dimethylaminoethyl acrylate, etc.

[0011] In an alternative embodiment, the (meth)acrylate monomer comprises any one or a combination of butyl methacrylate, pentyl methacrylate, hexyl methacrylate, butyl acrylate, hexyl acrylate, lauryl acrylate, etc.

[0012] In an alternative embodiment, the long-chain amine substance comprises any one or a combination of erucamide, oleamide, stearamide, and ethylene bisstearamide.

[0013] In an alternative embodiment, the organic ester comprises any one or a combination of dibutyl terephthalate, dioctyl terephthalate, dibutyl adipate, bis(2-ethylhexyl) adipate, dioctyl sebacate.

[0014] In an alternative embodiment, the solvent comprises any one of N-methylpyrrolidone and N-ethylpyrrolidone.

[0015] In a second aspect, the embodiments of the present disclosure further provide a method for preparing the high-compaction dispersion material as described above, comprising the following steps: Step S1, preparing component A, that is, adding the unsaturated cyclic monomer, unsaturated polyether, amine-containing monomer, (meth)acrylate monomer, and solvent into a reaction vessel respectively, stirring evenly, evacuating and replacing with nitrogen, then heating up and adding an initiator, stopping the reaction and cooling down to discharge after reacting for a certain time to obtain component A; Step S2, adding component A, component B, component C, and solvent into a reaction vessel respectively, mixing evenly and then performing vacuum dehydration, discharging after the water content is qualified to obtain the high-compaction dispersion material.

[0016] In an optional embodiment, the initiator includes any one or more combinations of azobisisobutyronitrile, azobisisoheptylnitrile, and dibenzoyl peroxide, and the amount of the initiator used is 0.1%-2% of the sum of the amounts of the unsaturated cyclic monomers, amine-containing monomers, unsaturated polyethers, and (meth)acrylate monomers, calculated by mass percentage.

[0017] In an optional embodiment, the reaction temperature in step S1 is 60-90° C., and the reaction time is 2-10 h; the amount of solvent added in step S1 accounts for 40-60% of the total mass of component A.

[0018] In a third aspect, an embodiment of the present disclosure also provides a method for preparing a high-compacted flexible positive electrode sheet, comprising the following steps: step S1, adding the high-compacted dispersed material, lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, and N-methylpyrrolidone as described above into a material tank, wherein the mass ratio of the lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and high-compacted dispersed material is (94-96): (1-3): (1-3): (40-60): (0.2-0.5), and stirring evenly at room temperature to obtain a slurry; step S2, coating the slurry on aluminum foil through a coater, drying it in an oven at 120-140°C, and then rolling it through a roller press to obtain a high-compacted flexible positive electrode sheet.

[0019] The high-compacted dispersion material and preparation method thereof, and high-compacted flexible positive electrode sheet have the following beneficial effects: 1. The component A in the high-density dispersion material can provide a strong dispersion effect. The cyclic unsaturated monomer will have a certain van der Waals force with the positive electrode particles and adsorb on the particle surface. The amine-containing monomer will wet the surface of the positive electrode material particles, causing large particles to gradually open into small molecules, thereby reducing the viscosity and maintaining the uniformity and stability of the positive electrode slurry. The acrylate monomer and the polyether monomer can reduce the rigidity of the dispersion material due to their certain flexibility. At the same time, a large number of ester groups in the acrylate cooperate with amide and polyether long chain groups to jointly maintain the stable and uniform dispersion of the slurry system; 2. The B component in the high-density dispersion material can interact with the first main material in the positive electrode slurry system, the positive electrode active material (such as lithium iron phosphate). The amide group is adsorbed on the surface of the positive electrode material particles, and the aliphatic hydrophobic long chain extends outward to form a hydrophobic layer, which helps the positive electrode particles to slip during the rolling process, avoiding direct collision and extrusion, and greatly reducing the rolling pressure and the risk of electrode rupture; 3. The C component in the high-compaction dispersion material can interact with the second major material binder in the positive electrode slurry system. This organic ester can shuttle between the molecular chains of the binder, reducing its regularity and crystallinity, significantly enhancing the flexibility of the binder, and thus contributing to improving the flexibility of the electrode during processing. 4. The high-compaction dispersion material can achieve functions such as dispersion, flexibility improvement, and compaction enhancement without adding auxiliaries such as flexibility agents, simplifying the production process and reducing the production cost of the battery.

[0020] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention are achieved and obtained by the structures specifically pointed out in the specification.

[0021] To make the above objectives, features, and advantages of the present invention more obvious and understandable, the following specific preferred embodiments are given for detailed description. Detailed Embodiments

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below. Obviously, the described embodiments are some, but not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

[0023] As used herein, phrases such as "in one embodiment", "according to one embodiment", "in some embodiments", etc. generally refer to the fact that the specific features, structures, or characteristics after the phrase can be included in at least one embodiment of the present disclosure. Therefore, the specific features, structures, or characteristics can be included in more than one embodiment of the present disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, terms such as "example", "exemplary", etc. are used "for purposes of illustration, instance, or explanation. Any embodiment, aspect, or design described herein as "example" or "exemplary" is not necessarily to be construed as preferred or superior to other embodiments, aspects, or designs. Instead, the use of terms such as "example", "exemplary", etc. is intended to present concepts in a specific manner.

[0024] In this document, as used herein, expressions such as "at least one of..." modify the entire list of elements when following a list of elements, rather than modifying individual elements in the list. For example, the expression "at least one of a, b, and c" should be understood to include only a, only b, only c, both a and b, both a and c, both b and c, or all of a, b, and c.

[0025] The terms used herein are for describing specific exemplary configurations only and are not intended to be limiting. As used herein, the singular articles "a", "an", and "the" may also be intended to include the plural forms, unless clearly stated otherwise herein. The terms "comprising", "including", and "having" are inclusive, thus specifying the presence of the features, steps, operations, elements, and / or components, but not precluding the presence or addition of one or more other features, steps, operations, elements, components, and / or combinations thereof. The method steps, processes, and operations described herein should not be construed as necessarily requiring them to be performed in the specific order discussed or shown, unless specifically identified as the order of execution. Additional or alternative steps may be employed.

[0026] First, the preparation of Component A: First, an unsaturated cyclic monomer, an unsaturated polyether, an amine-containing monomer, a (meth)acrylate monomer, and a solvent are added to a reaction kettle. After stirring evenly, the mixture is evacuated to remove oxygen and purged with nitrogen. Subsequently, the temperature is raised to 60 - 90 °C, and an initiator is added to the reaction kettle. After reacting for 2 h - 10 h, the reaction is stopped, and the temperature is lowered for discharging, thereby obtaining Component A, wherein the mass ratio of the unsaturated cyclic monomer, the unsaturated polyether, the amine-containing monomer, and the (meth)acrylate monomer is (3 - 6):1:(2 - 4):(1 - 2); calculated by mass percentage, the dosage of the initiator accounts for 0.1% - 2% of the total dosage of the unsaturated cyclic monomer, the unsaturated polyether, the amine-containing monomer, and the (meth)acrylate monomer; the solvent accounts for 50% of the total mass of the dispersed components.

[0027] In some embodiments, specifically, the unsaturated cyclic monomer includes any one or a combination of styrene, methylstyrene, vinylpyridine, N-vinylpyrrolidone, etc.

[0028] In some embodiments, specifically, the unsaturated polyether includes any one or a combination of allyl polyether APEG-500, allyl polyether APEG-800, allyl polyether APEG-1000, allyl polyether APEG-1500, allyl polyether APEG-2000, etc.; In some embodiments, specifically, the amine-containing monomer includes any one or a combination of acrylamide, N,N-dimethylacrylamide, isopropylacrylamide, dimethylaminoethyl acrylate, etc.

[0029] In some embodiments, specifically, the (meth)acrylate monomer includes any one or a combination of butyl methacrylate, pentyl methacrylate, hexyl methacrylate, butyl acrylate, hexyl acrylate, lauryl acrylate, etc.

[0030] In some embodiments, specifically, the solvent includes any one of N-methylpyrrolidone and N-ethylpyrrolidone.

[0031] In some embodiments, specifically, the initiator includes any one or a combination of more than one of azobisisobutyronitrile, azobisisoheptonitrile, and dibenzoyl peroxide, and calculated by mass percentage, the amount of the initiator accounts for 0.1%-2% of the total amount of the unsaturated cyclic monomer, unsaturated polyether, amine-containing monomer, and (meth)acrylate monomer.

[0032] Subsequently, the preparation of the high-compaction dispersion material: 30-40 parts of component A, 5-10 parts of component B, 5-10 parts of component C, and 50 parts of the solvent are sequentially added to the reaction kettle, mixed evenly, then vacuum dehydrated, and discharged after the moisture is qualified, thus obtaining the high-compaction dispersion material.

[0033] In an alternative embodiment, the long-chain amine substance includes any one or a combination of more than one of erucic acid amide, oleic acid amide, stearic acid amide, and ethylene bisstearamide.

[0034] In some embodiments, specifically, the organic ester includes any one or a combination of more than one of dibutyl terephthalate, dioctyl terephthalate, dibutyl adipate, bis(2-ethylhexyl) adipate, and dioctyl sebacate.

[0035] The above-prepared well-mixed high-compaction dispersion material is added to the positive electrode slurry. The mass ratio of lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and the high-compaction dispersion material in the positive electrode slurry is 95.7:2:2:50:0.3. The preparation process of the positive electrode sheet is as follows: The positive electrode slurry is added to the storage tank at one time according to the above ratio, stirred evenly at room temperature by a double-planet vacuum stirrer (the rotation speed is set to a revolution speed of 30±5 r / min and a rotation speed of 1300±50 r / min for 4 h), and then discharged. Then, the evenly dispersed slurry is coated on the aluminum foil by a coater (the coating thickness is selected to be 300 µm). The coated sample is dried in an oven at 130°C and subjected to processes such as rolling to obtain a high-compaction flexible positive electrode sheet.

[0036] Example 1. The preparation method of a high-compaction dispersion material is shown in the following steps in this example: 1) Preparation of the dispersion component A: First, 300 g of the unsaturated cyclic monomer styrene, 100 g of allyl polyether (APEG-500), 400 g of the amine-containing monomer acrylamide, 200 g of butyl methacrylate, and 1000 g of the solvent N-methylpyrrolidone were added to the reaction kettle. After stirring evenly, the oxygen was removed by evacuation and replaced with nitrogen. Subsequently, the temperature was raised to 60 °C, and 5 g of the initiator azobisisobutyronitrile was added to the reaction kettle. After reacting for 10 h, the reaction was stopped, and the temperature was lowered and the product was discharged, thus obtaining the dispersion component A.

[0037] 2) Preparation of the high-compaction dispersion material: 300 g of the component A synthesized in the previous step, 100 g of the component B erucic acid amide, 100 g of the component C dibutyl terephthalate, and 500 g of the solvent N-methylpyrrolidone were successively added to the reaction kettle. After mixing evenly, vacuum dehydration was carried out, and after the water content was qualified, the product was discharged, which was the high-compaction dispersion material.

[0038] Example 2. The preparation method of a high-compaction dispersion material is shown in the following steps in this embodiment: 1) Preparation of the dispersion component A: First, 400 g of the unsaturated cyclic monomer methylstyrene, 100 g of allyl polyether (APEG-800), 300 g of the amine-containing monomer N,N-dimethylacrylamide, 200 g of pentyl methacrylate, and 1000 g of the solvent N-methylpyrrolidone were added to the reaction kettle. After stirring evenly, the oxygen was removed by evacuation and replaced with nitrogen. Subsequently, the temperature was raised to 70 °C, and 10 g of the initiator azodiisooctanenitrile was added to the reaction kettle. After reacting for 6 h, the reaction was stopped, and the temperature was lowered and the product was discharged, thus obtaining the dispersion component A.

[0039] 2) Preparation of the high-compaction dispersion material: 350 g of the component A synthesized in the previous step, 50 g of the component B oleic acid amide, 100 g of the component C dioctyl terephthalate, and 500 g of the solvent N-methylpyrrolidone were successively added to the reaction kettle. After mixing evenly, vacuum dehydration was carried out, and after the water content was qualified, the product was discharged, which was the high-compaction dispersion material.

[0040] Example 3. The preparation method of a high-compaction dispersion material is shown in the following steps in this embodiment: 1) Preparation of the dispersion component A: First, 500 g of the unsaturated cyclic monomer vinylpyridine, 100 g of allyl polyether (APEG-1000), 300 g of the amine-containing monomer isopropylacrylamide, 100 g of hexyl methacrylate, and 1000 g of the solvent N-methylpyrrolidone were added to the reaction kettle. After stirring evenly, the oxygen was removed by evacuation and replaced with nitrogen. Subsequently, the temperature was raised to 80 °C, and 20 g of the initiator benzoyl peroxide was added to the reaction kettle. After reacting for 4 h, the reaction was stopped, and the temperature was lowered and the product was discharged, thus obtaining the dispersion component A.

[0041] 2) Preparation of high-compaction dispersion material: 400 g of component A synthesized in the previous step, 50 g of component B stearic acid amide, 50 g of component C dibutyl adipate, and 500 g of solvent N-methylpyrrolidone were successively added to the reaction kettle. After mixing evenly, vacuum dehydration was carried out. After the moisture was qualified, the product was discharged, which was the high-compaction dispersion material.

[0042] Example 4. The preparation method of a high-compaction dispersion material is shown in the following steps in this embodiment: 1) Preparation of dispersion component A: First, 600 g of unsaturated cyclic monomer N-vinylpyrrolidone, 100 g of allyl polyether (APEG-1500), 200 g of amine-containing monomer dimethylaminoethyl acrylate, 100 g of butyl acrylate, and 1000 g of solvent N-ethylpyrrolidone were added to the reaction kettle. After stirring evenly, vacuum was pumped to remove oxygen and nitrogen replacement was carried out. Subsequently, the temperature was raised to 90 °C, and 1 g of initiator azobisisobutyronitrile was added to the reaction kettle. After reacting for 2 h, the reaction was stopped and the temperature was lowered for discharging, thus obtaining dispersion component A.

[0043] 2) Preparation of high-compaction dispersion material: 300 g of component A synthesized in the previous step, 100 g of component B ethylene bisstearamide, 100 g of component C bis(2-ethylhexyl) adipate, and 500 g of solvent N-ethylpyrrolidone were successively added to the reaction kettle. After mixing evenly, vacuum dehydration was carried out. After the moisture was qualified, the product was discharged, which was the high-compaction dispersion material.

[0044] Example 5. The preparation method of a high-compaction dispersion material is shown in the following steps in this embodiment: 1) Preparation of dispersion component A: First, 500 g of unsaturated cyclic monomer N-vinylpyrrolidone, 100 g of allyl polyether (APEG-2000), 200 g of amine-containing monomer acrylamide, 200 g of hexyl acrylate, and 1000 g of solvent N-ethylpyrrolidone were added to the reaction kettle. After stirring evenly, vacuum was pumped to remove oxygen and nitrogen replacement was carried out. Subsequently, the temperature was raised to 60 °C, and 30 g of initiator azodiisooctanenitrile was added to the reaction kettle. After reacting for 10 h, the reaction was stopped and the temperature was lowered for discharging, thus obtaining dispersion component A.

[0045] 2) Preparation of high-compaction dispersion material: 350 g of component A synthesized in the previous step, 50 g of component B erucic acid amide, 100 g of component C dioctyl sebacate, and 500 g of solvent N-ethylpyrrolidone were successively added to the reaction kettle. After mixing evenly, vacuum dehydration was carried out. After the moisture was qualified, the product was discharged, which was the high-compaction dispersion material.

[0046] Example 6. The preparation method of a high-compaction dispersion material is shown in the following steps in this embodiment: 1) Preparation of the dispersion component A: First, 400 g of the unsaturated cyclic monomer N-vinylpyrrolidone, 100 g of allyl polyether (APEG-500), 400 g of the amine-containing monomer N,N-dimethylacrylamide, 100 g of lauryl acrylate, and 1000 g of the solvent N-ethylpyrrolidone were added to a reaction kettle. After stirring evenly, the mixture was evacuated to remove oxygen and purged with nitrogen. Subsequently, the temperature was raised to 70 °C, and 10 g of the initiator benzoyl peroxide was added to the reaction kettle. After reacting for 10 h, the reaction was stopped, and the temperature was lowered and the product was discharged, thus obtaining the dispersion component A.

[0047] 2) Preparation of the high-compaction dispersion material: 400 g of the component A synthesized in the previous step, 50 g of the component B oleic acid amide, 50 g of the component C dibutyl terephthalate, and 500 g of the solvent N-ethylpyrrolidone were successively added to a reaction kettle. After mixing evenly, vacuum dehydration was carried out. After the water content was qualified, the product was discharged, which was the high-compaction dispersion material.

[0048] Comparative Example 1 The preparation method of a high-compaction dispersion material is shown in the following steps in this comparative case: The high-compaction dispersion material only contains the dispersion component A, and the specific formulation is as follows: First, 500 g of the unsaturated cyclic monomer vinylpyridine, 100 g of allyl polyether (APEG-500), 300 g of the amine-containing monomer isopropylacrylamide, 100 g of hexyl methacrylate, and 1000 g of the solvent N-methylpyrrolidone were added to a reaction kettle. After stirring evenly, the mixture was evacuated to remove oxygen and purged with nitrogen. Subsequently, the temperature was raised to 80 °C, and 20 g of the initiator benzoyl peroxide was added to the reaction kettle. After reacting for 4 h, the reaction was stopped, and the temperature was lowered and the product was discharged, thus obtaining the dispersion component A. Subsequently, 500 g of the component A and 500 g of the solvent N-methylpyrrolidone were successively added to a reaction kettle. After mixing evenly, vacuum dehydration was carried out. After the water content was qualified, the product was discharged, which was the high-compaction dispersion material.

[0049] Comparative Example 2 The preparation method of a high-compaction dispersion material is shown in the following steps in this comparative case: The high-compaction dispersion material only contains the component B. Subsequently, 500 g of the component B erucic acid amide and 500 g of the solvent N-methylpyrrolidone were successively added to a reaction kettle. After mixing evenly, vacuum dehydration was carried out. After the water content was qualified, the product was discharged, which was the high-compaction dispersion material.

[0050] Comparative Example 3 The preparation method of a high-compaction dispersion material is shown in the following steps in this comparative case: The high-compaction dispersion material only contains the component C. Subsequently, 500 g of the component C dibutyl terephthalate and 500 g of the solvent N-methylpyrrolidone were successively added to a reaction kettle. After mixing evenly, vacuum dehydration was carried out. After the water content was qualified, the product was discharged, which was the high-compaction dispersion material.

[0051] Comparative Example 4 A commercially available general-purpose dispersion material HF2918

[0052] The preparation process of the positive electrode sheets in the above Examples 1-6 and Comparative Examples 1-4 is as follows: Lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and the dispersion material prepared in the Example or Comparative Example were all added to the feed tank at one time according to a mass ratio of 95.7:2:2:50:0.3. After stirring evenly at room temperature by a double planetary vacuum stirrer (the rotation speed is set to a revolution speed of 30±5 r / min and a rotation speed of 1300±50 r / min for 4 h), the mixture was discharged. Then, the uniformly dispersed slurry was coated on the aluminum foil by a coater (the coating thickness was selected to be 300 µm). The coated sample was dried in an oven at 130°C and subjected to processes such as rolling to obtain a high-compaction flexible positive electrode sheet.

[0053] The following are relevant tests for the viscosity of the positive electrode slurry, the flexibility of the positive electrode sheet, etc.

[0054] Table 1:

[0055] Please refer to Table 1. Table 1 shows the test data of the viscosity of the high-compaction dispersion material slurry and the flexibility of the electrode sheet. It can be seen from the slurry viscosity data in Table 1 that when comparing the initial viscosities of the slurries in Examples 1-6 and Comparative Example 4, the Examples have better dispersion effects. When compared with Comparative Examples 2 and 3, it is found that Component B and Component C have certain dispersion effects, but there is a certain gap compared with Component A designed in the present invention. From the number of folding times and the pressure of the electrode sheet rolling press in the table, it can be known that when the compaction density is 2.65 g / cm3, in Comparative Example 1, there is only Component A without other flexibility-enhancing components, and the electrode sheet is relatively brittle, and a higher rolling pressure is required to reach the same compaction density, which brings great challenges and negative impacts to the production and processing process of the electrode sheet. Comparative Example 4 does not have a flexibility-enhancing effect, so the electrode sheet is easily broken. The number of times the electrode sheets in Comparative Examples 2 and 3 can withstand bending is also less than that in Examples 1-6. This shows that using only flexibility-enhancing Component B or Component C alone cannot achieve a good flexibility-enhancing and compaction-improving effect, and Components A, B, and C need to work together; when the compaction density is increased to 2.75 g / cm 3 At this time, the electrode sheets prepared by using Examples 1-6 can be normally coated and rolled, while the electrode sheets prepared by using Comparative Examples 1-4 are broken. This result shows that conventional dispersion materials or single components cannot realize the production and processing of electrode sheets with higher compaction densities. The high-compaction dispersion material designed and prepared in the present invention has excellent dispersion performance, can also significantly improve the compaction density of the electrode sheet, and can ensure the stable operation of the electrode sheet without breaking during the high-compaction coating and rolling process, which helps to improve the energy density of the battery and the production efficiency and yield of battery manufacturers.

[0056] In summary, the high-compaction dispersion material, its preparation method, and the high-compaction flexible positive electrode sheet proposed by the present invention have the advantages of excellent dispersion performance, prominent flexibility enhancement effect, and significant improvement in the compaction density of the electrode sheet. They can balance the two functions of dispersion and compaction improvement, reduce production costs, increase the yield of the electrode sheet, and have good application prospects.

[0057] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that the technical solutions of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical solutions of the present invention, and they should all be covered within the scope of the claims of the present invention.

Claims

1. A high-compacted dispersed material, characterized in that: The components include the following by mass: 30-40 parts of component A, 5-10 parts of component B, 5-10 parts of component C, and 40-60 parts of solvent; The component A comprises a solution polymerization copolymer of an unsaturated cyclic monomer, an unsaturated polyether, an amine-containing monomer and a (meth)acrylate monomer; The B component includes long-chain amine substances; The C component includes an organic ester.

2. The high-compacted dispersion material according to claim 1, characterized in that: The mass ratio of the unsaturated cyclic monomer, the unsaturated polyether, the amine-containing monomer and the (meth)acrylate monomer is (3-6):1:(2-4):(1-2).

3. The high-compacted dispersion material according to claim 1, characterized in that: The unsaturated cyclic monomer includes any one or more combinations of styrene, methyl styrene, vinyl pyridine, and N-vinyl pyrrolidone; The unsaturated polyether includes any one or more combinations of allyl polyether APEG-500, allyl polyether APEG-800, allyl polyether APEG-1000, allyl polyether APEG-1500, and allyl polyether APEG-2000; The amine-containing monomer includes any one or more combinations of acrylamide, N,N-dimethylacrylamide, isopropylacrylamide, and dimethylaminoethyl acrylate; The (meth)acrylate monomers include any one or more combinations of butyl methacrylate, pentyl methacrylate, hexyl methacrylate, butyl acrylate, hexyl acrylate, lauryl acrylate, and the like.

4. The high-compacted dispersion material according to claim 1, characterized in that: The long-chain amine substances include any one or more combinations of erucamide, oleamide, stearamide and ethylene bisstearamide.

5. The high-compacted dispersion material according to claim 1, characterized in that: The organic ester includes any one or more combinations of dibutyl terephthalate, dioctyl terephthalate, dibutyl adipate, bis(2-ethylhexyl) adipate, and dioctyl sebacate.

6. The high-compacted dispersion material according to claim 1, characterized in that: The solvent includes any one of N-methylpyrrolidone and N-ethylpyrrolidone.

7. A method for preparing a high-compacted dispersion material according to any one of claims 1 to 6, characterized in that: The steps include: Step S1, preparing component A, namely The unsaturated cyclic monomer, the amine-containing monomer, the unsaturated polyether, the (meth)acrylate monomer and the solvent are added to the reaction container respectively, stirred evenly, evacuated and replaced with nitrogen, then the temperature is raised and the initiator is added, and the reaction is stopped after a certain reaction time and the temperature is lowered to discharge the material to obtain component A; Step S2, adding component A, component B, component C and solvent into a reaction container respectively, mixing them evenly and then performing vacuum dehydration, discharging the materials after the moisture content is qualified, and obtaining a high-compacted dispersed material.

8. The method for preparing a high-compacted dispersed material according to claim 7, characterized in that: The initiator includes any one or more combinations of azobisisobutyronitrile, azobisisoheptylnitrile, and dibenzoyl peroxide, and the amount of the initiator used accounts for 0.1%-2% of the sum of the amounts of the unsaturated cyclic monomer, the unsaturated polyether, the amine-containing monomer, the (meth)acrylate monomer, etc., calculated by mass percentage.

9. The method for preparing a high-compacted dispersed material according to claim 7, characterized in that: In step S1, the reaction temperature is 60-90°C and the reaction time is 2-10h; The amount of solvent added in step S1 accounts for 40-60% of the total mass of component A.

10. A method for preparing a high-density flexible positive electrode sheet, characterized in that: The steps include: Step S1, adding the high-density dispersed material according to any one of claims 1 to 6, lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, and N-methylpyrrolidone into a material tank, wherein the mass ratio of the lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and high-density dispersed material is (94-96): (1-3): (1-3): (40-60): (0.2-0.5), and stirring at room temperature to obtain a slurry; Step S2, coating the slurry on aluminum foil by a coating machine, drying in an oven at 120-140° C., and then rolling it by a roller press to obtain a high-density flexible positive electrode sheet.

Images