Dispersion material composition, preparation method thereof, and bend-resistant positive electrode sheet

Abstract

The application belongs to the technical field of lithium ion battery auxiliary materials, and particularly relates to a dispersing material composition, a preparation method thereof and a bending-resistant positive electrode sheet. x H 2x+1 O (EO) y (PO) z OPO3H2, wherein the number of alkyl alcohol carbon atoms in a single polymer chain is 1-22, the number of grafted ethylene oxide is 0-50, and the number of grafted propylene oxide is 0-50; and the C component comprises an amine compound.

Description

Technical Field

[0001] This invention belongs to the field of lithium-ion battery additive materials technology, specifically relating to a dispersion material composition and its preparation method, and a bend-resistant positive electrode sheet. Background Technology

[0002] With the rapid development of electric vehicles and the explosive growth in demand for chemical energy storage, the production and sales volume of lithium batteries have both increased rapidly, thus placing higher demands on their performance and cost. The manufacturing process of lithium batteries can be simplified into three main steps: electrode manufacturing (preparation of positive and negative electrode sheets), cell assembly (winding or stacking, casing, and electrolyte injection), and formation and capacity testing. The most direct solution for reducing costs and improving efficiency in lithium batteries is to increase battery energy density, with the core solutions revolving around two main lines: material system upgrades and structural process optimization. Material system upgrades mainly include selecting high-nickel or high-voltage positive electrodes, silicon-based negative electrodes, and high-voltage electrolytes and additives. Structural process optimization mainly includes increasing positive electrode compaction density, thick coating, large cells, and CTP (cell-to-patch) integration technology.

[0003] The composition of cathode slurry systems is very complex, typically including cathode materials, binders, conductive agents, additives, and solvents. With increasing market demands for battery energy density and fast-charging performance, new components such as lithium replenishers and wetting agents are being introduced. Simultaneously, the particle size of cathode materials is becoming increasingly smaller, posing greater challenges to the dispersion, consolidation, and adhesion stabilization of cathode slurries. Currently, mainstream dispersion materials are only compatible with conventional materials and systems. Once the composition of the cathode material fluctuates or new materials such as lithium replenishers are introduced, viscosity reduction in cathode slurries becomes difficult, and viscosity rebound can be significant, even leading to gelation.

[0004] Without altering the battery material composition and overall structure, increasing the compaction density of battery electrodes is the most direct way to improve battery energy density. To achieve high compaction density electrode preparation, firstly, the cathode material particle size must be nanoscaled (smaller particle size presents challenges in dispersion and adhesion during slurry preparation); secondly, a greater rolling pressing capacity is required; and thirdly, the high compaction electrode must not break or shed powder during the winding process. Existing dispersion materials typically employ cyclic unsaturated monomers adsorbed on the cathode particle surface and used with other dispersion components to achieve strong dispersion. The rigidity of the cyclic unsaturated monomers themselves can be appropriately reduced by the flexibility of acrylate monomers. However, further research by the applicant revealed that achieving a compaction density of 2.7 g / cm³ for battery electrodes is challenging. 3 Then a bottleneck or upper limit appeared.

[0005] Therefore, how to overcome the limitations of existing dispersed materials with cyclic unsaturated monomers achieving a compaction density of 2.7 g / cm³ is a key challenge. 3 The defect that easily leads to breakage is a technical problem that urgently needs to be solved in this field.

[0006] It should be noted that the information disclosed in this background section is only for understanding the background technology of the present application concept, and therefore, the above description is not considered to constitute prior art information. Summary of the Invention

[0007] This disclosure provides at least one dispersion material composition and its preparation method, as well as a bend-resistant positive electrode sheet.

[0008] In a first aspect, embodiments of this disclosure provide a dispersion material composition comprising, by mass parts: 15-30 parts of component A, 15-50 parts of component B, 5-15 parts of component C, and 30-50 parts of solvent; wherein, component A comprises amine-containing monomers, (meth)acrylate monomers, and (meth)acrylate hydroxyphosphate monomers; and component B comprises an alkyl copolyether phosphate polymer with the chemical formula C. x H 2x+1 (EO) y (PO) z OPO3H2, wherein the number of alkyl alcohol carbon atoms on a single polymer chain is 1 to 22, the number of ethylene oxide grafts y is 0 to 50, and the number of propylene oxide grafts z is 0 to 50; the C component includes amine compounds.

[0009] In one optional embodiment, the mass ratio of the block copolymer containing amine monomers, (meth)acrylate monomers and (meth)acrylate hydroxyphosphate in component A is 2-4:2-5:1-2.

[0010] In one alternative embodiment, the amine-containing monomer includes any one or a combination of acrylamide, N,N-dimethylacrylamide, isopropylacrylamide, and dimethylaminoethyl acrylate.

[0011] In one alternative embodiment, the (meth)acrylate monomers include any one or more combinations of butyl methacrylate, hexyl methacrylate, lauryl methacrylate, butyl acrylate, hexyl acrylate, and lauryl acrylate.

[0012] In one optional embodiment, the (meth)acrylate hydroxyphosphate monomer includes any one or more combinations of hydroxyethyl methacrylate, hydroxyhexyl methacrylate, hydroxydecyl methacrylate, hydroxyethyl acrylate, hydroxyhexyl acrylate, and hydroxydecyl acrylate.

[0013] In one optional embodiment, the chemical structural formula of the amine compound in component C is as follows: Wherein, R1 is any one of H, OH, CH3, CH2CH3, CH2CH2OH, R2 is any one of H, OH, CH3, CH2CH3, CH2CH2OH, and R3 is any one of H, OH, CH3, CH2CH3, CH2CH2OH.

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

[0015] Secondly, this disclosure also provides a method for preparing the dispersion material composition as described above, comprising the following steps: S1, preparing component A, namely, adding an amine-containing monomer and a solvent to a reaction vessel, stirring evenly, evacuating and replacing with nitrogen, then heating and adding an initiator, after the reaction is complete, adding a (meth)acrylate monomer, after the reaction is complete, adding a (meth)acrylate hydroxyphosphate monomer, continuing the reaction for a certain period of time, stopping the reaction and cooling down to discharge the material, obtaining component A; S2, adding a polyether to a reaction vessel, stirring evenly and heating, then adding an esterification reagent to the reaction vessel, keeping the reaction at a certain temperature for a certain period of time, cooling and discharging the material for later use, obtaining component B; S3, adding component A, component B, component C and solvent to a reaction vessel respectively, mixing evenly, and then vacuum dehydrating, discharging the material after the moisture content is qualified, obtaining the dispersion material composition.

[0016] In one optional embodiment, the initiator includes any one or more combinations of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide, and the amount of the initiator is 0.1% to 2% of the sum of the amounts of the amine-containing monomer, the (meth)acrylate monomer, and the (meth)acrylate hydroxyphosphate monomer, calculated by mass percentage.

[0017] In one optional embodiment, the reaction temperature in S1 is 60-90°C and the reaction time is 4-10 h; the amount of solvent added in S1 accounts for 40-60% of the total mass of component A.

[0018] In one optional embodiment, the molecular weight of the polyether in S2 is 500 to 5000; the esterification reagent is either phosphorus pentoxide or polyphosphoric acid, the esterification temperature is 60 to 90°C, and the reaction time is 6 to 10 hours.

[0019] Thirdly, this disclosure also provides a method for preparing a flexible, bend-resistant positive electrode sheet, comprising the following steps: Step S1, adding the aforementioned dispersion material composition, lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, and N-methylpyrrolidone into a material tank, wherein the mass ratio of lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and dispersion material composition 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 onto aluminum foil using a coating machine, drying it in an oven at 120-140°C, and then rolling it using a roller press to obtain a flexible, bend-resistant positive electrode sheet.

[0020] The beneficial effects of this invention are as follows: the dispersion material composition and its preparation method, and component A in the flexurally resistant positive electrode sheet, provide strong flexibility and dispersion effects. The hydroxyphosphate monomer can be anchored to the surface of the lithium iron phosphate positive electrode. This polymer has a multi-block structure, and a single molecule can simultaneously interact with multiple materials in the slurry system, thereby maintaining the long-term stable dispersion of the slurry system. Furthermore, component B, containing a large number of flexible polyether segments, can synergistically enhance the flexibility of the electrode sheet with the block copolymer, helping to improve the electrode sheet compaction density and reduce the pressure of the roller press, extending equipment life and improving coating roller pressing efficiency. Simultaneously, component C can work with the polyether ester to rapidly wet the positive electrode active material, shortening the slurry preparation time without occupying effective solid content. In summary, this dispersion material composition, without the addition of stabilizers, softeners, or other additives, can simultaneously achieve multiple functions such as dispersion and stabilization, flexibility and compaction enhancement, and flexural resistance, improving battery cell yield and reducing battery production costs.

[0021] Other features and advantages of the invention will be set forth in the description which follows, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention are realized and obtained through the structures particularly pointed out in the description.

[0022] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below. Detailed Implementation

[0023] 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 only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] As used herein, the phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” etc., generally refer to the fact that a particular feature, structure, or characteristic following the phrase can be included in at least one embodiment of this disclosure. Therefore, a particular feature, structure, or characteristic can be included in more than one embodiment of this disclosure, such that these phrases do not necessarily refer to the same embodiment. As used herein, the terms “example,” “exemplary,” etc., are used to “serve as an example, instance, or illustration.” Any implementation, aspect, or design described herein as “example” or “exemplary” is not necessarily to be construed as preferred or superior to other implementations, aspects, or designs. Rather, the use of the terms “example,” “exemplary,” etc., is intended to present concepts in a specific manner.

[0025] The terminology used herein is for the purpose of describing specific exemplary configurations only and is not intended to be limiting. As used herein, the singular articles “a,” “an,” and “the” may also be intended to include plural forms unless otherwise clearly stated herein. The terms “comprising,” “including,” and “having” are inclusive and thus specify the presence of features, steps, operations, elements, and / or components, but do not preclude 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 requiring them to be performed in the specific order discussed or shown, unless specifically identified as such. Additional or alternative steps may be employed.

[0026] Currently, there is relatively little information available on the market for functional dispersion materials, although some companies have begun to explore and develop such technologies. Patent CN115863643B, for example, primarily relates to a dispersant and flexibility enhancer for lithium-ion battery cathode slurries. It mainly addresses the problem of poor electrode flexibility and ductility during thick-coating and fast-coating processes. The dispersant is primarily tristyrene-based phenol polyether phosphate or modified polyurethane, with a main structure containing a large number of benzene rings, exhibiting high rigidity and significantly negatively impacting the electrode winding process.

[0027] Patent CN119775528A relates to a vinyl monomer, its preparation method, and a flexible dispersant containing it. It mainly addresses the problem of poor electrode flexibility in positive electrode slurry for lithium-ion batteries. However, its synthesis route is very complex and not conducive to subsequent industrialization.

[0028] The shortcomings of the above solutions are the result of the inventor's practical experience and careful research. Therefore, the discovery process of the above problems and the solutions proposed in this disclosure below should be considered as the inventor's contribution to this disclosure.

[0029] The following describes some embodiments of the present invention in detail. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0030] This disclosure provides a dispersion material composition comprising, by mass parts: 15-30 parts of component A, 15-50 parts of component B, 5-15 parts of component C, and 30-50 parts of solvent; wherein, component A comprises amine-containing monomers, (meth)acrylate monomers, and (meth)acrylate hydroxyphosphate monomers; and component B comprises an alkyl polyether phosphate polymer with the chemical formula C. x H 2x+1 (EO) y (PO) z OPO3H2, wherein the number of alkyl alcohol carbon atoms on a single polymer chain is 1 to 22, the number of ethylene oxide grafts y is 0 to 50, and the number of propylene oxide grafts z is 0 to 50; the C component includes small molecule amine compounds.

[0031] In some embodiments, specifically, the mass ratio of the block copolymer containing amine monomers, (meth)acrylate monomers and (meth)acrylate hydroxyphosphate in component A is 2-4:2-5:1-2.

[0032] In some embodiments, specifically, the amine-containing monomer includes any one or more combinations of acrylamide, N,N-dimethylacrylamide, isopropylacrylamide, and dimethylaminoethyl acrylate.

[0033] In some embodiments, specifically, the (meth)acrylate monomers include any one or more combinations of butyl methacrylate, hexyl methacrylate, lauryl methacrylate, butyl acrylate, hexyl acrylate, and lauryl acrylate.

[0034] In some embodiments, specifically, the (meth)acrylate hydroxyphosphate monomer includes any one or more combinations of hydroxyethyl methacrylate, hydroxyhexyl methacrylate, hydroxydecyl methacrylate, hydroxyethyl acrylate, hydroxyhexyl acrylate, and hydroxydecyl acrylate.

[0035] Specifically, the amine-containing monomers in component A wet the carbon coating layer of the cathode material and the conductive carbon material, causing large particles to gradually open into small molecules, thereby reducing viscosity and maintaining the uniformity and stability of the cathode slurry. The long-chain acrylate monomers, due to their certain flexibility, can reduce the rigidity of the binder in the cathode system. The amine-containing monomers, long-chain acrylate monomers, and (meth)acrylate hydroxyphosphate monomers work together to achieve a softening and dispersing effect.

[0036] In some embodiments, specifically, the alkyl copolyether phosphate polymer in component B is an alkyl alcohol-initiated ethylene oxide-propylene oxide copolyether phosphate polymer, wherein EO is ethylene oxide and PO is propylene oxide; component B can assist in wetting and leveling, ensuring leveling during electrode coating and improving problems such as poor appearance.

[0037] In some embodiments, specifically, the chemical structural formula of the amine compound in component C is as follows: Wherein, R1 is any one of H, OH, CH3, CH2CH3, CH2CH2OH, R2 is any one of H, OH, CH3, CH2CH3, CH2CH2OH, and R3 is any one of H, OH, CH3, CH2CH3, CH2CH2OH; the overall pH value of the dispersion material can be adjusted to adapt to various complex environments.

[0038] In some embodiments, specifically, the solvent includes any one of N-methylpyrrolidone and N-ethylpyrrolidone.

[0039] This disclosure also provides a method for preparing the dispersion material composition as described above, comprising the following steps: S1, preparing component A by adding an amine-containing monomer and a solvent to a reaction vessel, stirring evenly, evacuating and replacing with nitrogen, then heating and adding an initiator, and after the reaction is complete, adding a (meth)acrylate monomer, and after the reaction is complete, adding a (meth)acrylate hydroxyphosphate monomer, continuing the reaction for a certain period of time, stopping the reaction and cooling down to discharge the material, obtaining component A; S2, adding a polyether to a reaction vessel, stirring evenly and heating, then adding an esterification reagent to the reaction vessel, keeping the reaction at a certain temperature for a certain period of time, cooling and discharging the material for later use, obtaining component B; S3, adding component A, component B, component C and solvent to a reaction vessel respectively, mixing evenly, and then vacuum dehydrating the mixture, discharging the material after the moisture content is qualified, obtaining the dispersion material composition.

[0040] In some embodiments, specifically, the initiator includes any one or more combinations of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide, and the amount of the initiator is 0.1% to 2% of the sum of the amounts of the amine-containing monomer, the (meth)acrylate monomer, and the (meth)acrylate hydroxyphosphate monomer, calculated by mass percentage.

[0041] In some embodiments, specifically, the reaction temperature in S1 is 60–90°C, and the reaction time is 4–10 h; the amount of solvent added in S1 accounts for 40–60% of the total mass of component A.

[0042] In some embodiments, specifically, the molecular weight of the polyether in S2 is 500 to 5000; the esterification reagent is any one of phosphorus pentoxide and polyphosphoric acid; the esterification temperature is 60 to 90°C; and the reaction time is 6 to 10 hours.

[0043] This disclosure also provides a method for preparing a flexible, bend-resistant positive electrode sheet, comprising the following steps: Step S1, adding the aforementioned dispersion material composition, lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, and N-methylpyrrolidone into a material tank, wherein the mass ratio of lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and dispersion material composition 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 onto aluminum foil using a coating machine, drying it in an oven at 120-140°C, and then rolling it using a roller press to obtain a flexible, bend-resistant positive electrode sheet.

[0044] Example 1 illustrates a method for preparing a dispersion material composition according to the following steps: S1, Preparation of softening and dispersing component A: 300g of amine-containing monomer acrylamide and 1000g of solvent N-methylpyrrolidone were added to a reaction vessel, stirred evenly, evacuated and purged with nitrogen, then heated to 60℃ and 1g of initiator azobisisobutyronitrile was added. After reacting for 2h, 500g of butyl methacrylate was added, and after an interval of 2h, 200g of hydroxyethyl phosphate methacrylate was added. The reaction was kept at the temperature for 10h and then stopped. The product was cooled and discharged to obtain component A.

[0045] S2, Preparation of wetting and dispersing component B: 1000g of polyether (initiator methanol, average molecular weight 500, average number of grafted EO and PO 3 and 6 respectively) was added to the reaction vessel, stirred evenly and heated to 60℃. Then 141g of esterification reagent phosphorus pentoxide was added to the reaction vessel, and the reaction was kept at the temperature for 10h. After cooling, the material was discharged for later use.

[0046] S3, Preparation of the dispersion material composition: 150g of component A, 300g of component B, 50g of component C synthesized in the previous step and 500g of solvent N-methylpyrrolidone are added to the reaction vessel in sequence. After mixing evenly, vacuum dehydration is performed. After the moisture and solid content are qualified, the material is discharged, which is the dispersion material composition.

[0047] Example 2 illustrates a method for preparing a dispersion material composition according to the following steps: S1, Preparation of softening and dispersing component A: 350g of amine-containing monomer N,N-dimethylacrylamide and 1000g of solvent N-methylpyrrolidone were added to a reaction vessel, stirred evenly, evacuated and purged with nitrogen, then heated to 70℃ and added 5g of initiator azobisisobutyronitrile. After reacting for 2h, 350g of hexyl methacrylate was added, and after an interval of 2h, 300g of hydroxyhexyl methacrylate was added. The reaction was kept at the temperature for 8h and then stopped. The product was cooled and discharged to obtain component A.

[0048] S2, Preparation of wetting and dispersing component B: 800g of polyether (initiator butanol, average molecular weight 800, average number of grafted EO and PO 15 and 2 respectively) was added to the reaction vessel, stirred evenly, and heated to 70℃. Then, 70.5g of esterification reagent phosphorus pentoxide was added to the reaction vessel, and the reaction was kept at the temperature for 9h. After cooling, the material was discharged for later use.

[0049] S3, Preparation of the dispersion material composition: 200g of component A, 300g of component B, 50g of component C, diethanolamine and 450g of solvent N-methylpyrrolidone synthesized in the previous step are added to the reaction vessel in sequence. After mixing evenly, vacuum dehydration is performed. After the moisture and solid content are qualified, the material is discharged, which is the dispersion material composition.

[0050] Example 3 illustrates a method for preparing a dispersion material composition according to the following steps: S1, Preparation of softening and dispersing component A: 400g of amine-containing monomer isopropylacrylamide and 1000g of solvent N-methylpyrrolidone were added to a reaction vessel, stirred evenly, evacuated and purged with nitrogen, then heated to 80℃ and 10g of initiator azobisisoheptanenitrile was added. After reacting for 2h, 200g of lauryl methacrylate was added, and after an interval of 2h, 400g of hydroxydecyl methacrylate was added. The reaction was kept at the temperature for 6h and then stopped. The product was cooled and discharged to obtain component A.

[0051] S2, Preparation of wetting and dispersing component B: 1500g of polyether (initiator n-butanol, average molecular weight 1500, average number of grafted EO and PO 19 and 10 respectively) was added to the reaction vessel, stirred evenly, and heated to 80℃. Then 70.5g of esterification reagent phosphorus pentoxide was added to the reaction vessel, and the reaction was kept at the temperature for 8h. After cooling, the material was discharged for later use.

[0052] S3, Preparation of the dispersion material composition: 250g of component A, 350g of component B, 100g of component C, triethanolamine and 300g of solvent N-methylpyrrolidone synthesized in the previous step are added to the reaction vessel in sequence. After mixing evenly, vacuum dehydration is performed. After the moisture and solid content are qualified, the material is discharged, which is the dispersion material composition.

[0053] Example 4 illustrates a method for preparing a dispersion material composition according to the following steps: S1, Preparation of softening and dispersing component A: 400g of amine-containing monomer dimethylaminoethyl acrylate and 1000g of solvent N-ethylpyrrolidone were added to a reaction vessel, stirred evenly, evacuated and purged with nitrogen, then heated to 90℃ and 20g of initiator benzoyl peroxide were added. After reacting for 2h, 500g of n-butyl acrylate was added, and after an interval of 2h, 100g of hydroxyethyl phosphate acrylate was added. The reaction was kept at the temperature for 4h and then stopped. The material was cooled and discharged to obtain component A. S2, Preparation of wetting and dispersing component B: 2000g of polyether (initiator lauryl alcohol, average molecular weight 2000, average number of grafted EO and PO 30 and 10 respectively) was added to the reaction vessel, stirred evenly and heated to 90℃. Then 98g of esterification reagent polyphosphoric acid was added to the reaction vessel, and the reaction was kept at the temperature for 6h. After cooling, the material was discharged for later use.

[0054] S3, Preparation of the dispersion material composition: 300g of component A, 150g of component B, 150g of component C synthesized in the previous step, diethylamine, and 400g of solvent N-ethylpyrrolidone are added sequentially to the reaction vessel. After mixing evenly, vacuum dehydration is performed. After the moisture and solid content are qualified, the material is discharged, which is the dispersion material composition.

[0055] Example 5 illustrates a method for preparing a dispersion material composition according to the following steps: S1, Preparation of softening and dispersing component A: 300g of amine-containing monomer isopropylacrylamide and 1000g of solvent N-ethylpyrrolidone were added to a reaction vessel, stirred evenly, evacuated and purged with nitrogen, then heated to 80℃ and 10g of initiator benzoyl peroxide were added. After reacting for 2h, 300g of hexyl acrylate was added, and after an interval of 2h, 400g of hydroxyhexyl phosphate acrylate was added. The reaction was kept at the temperature for 5h and then stopped. The material was cooled and discharged to obtain component A.

[0056] S2, Preparation of wetting and dispersing component B: 3000g of polyether (initializer octadecyl alcohol, average molecular weight 3000, average number of grafted EO and PO 50 and 9 respectively) was added to the reaction vessel, stirred evenly and heated to 80℃. Then 98g of esterification reagent polyphosphoric acid was added to the reaction vessel, and the reaction was kept at the temperature for 6h. After cooling, the material was discharged for later use.

[0057] S3, Preparation of the dispersion material composition: 150g of component A, 500g of component B, 50g of component C, triethylamine and 300g of solvent N-methylpyrrolidone synthesized in the previous step are added to the reaction vessel in sequence. After mixing evenly, vacuum dehydration is performed. After the moisture and solid content are qualified, the material is discharged, which is the dispersion material composition.

[0058] Example 6 illustrates a method for preparing a dispersion material composition according to the following steps: S1, Preparation of softening and dispersing component A: 400g of amine-containing monomer dimethylaminoethyl acrylate and 1000g of solvent N-ethylpyrrolidone were added to a reaction vessel, stirred evenly, evacuated and purged with nitrogen, then heated to 85℃ and 10g of initiator azobisisobutyronitrile was added. After reacting for 2h, 500g of lauryl acrylate was added, and after an interval of 2h, 100g of hydroxydecyl phosphate acrylate was added. The reaction was kept at the temperature for 4h and then stopped. The material was cooled and discharged to obtain component A. S2, Preparation of wetting and dispersing component B: 5000g of polyether (initiator dodecanol, average molecular weight 5000, average number of grafted EO and PO 40 and 50 respectively) was added to the reaction vessel, stirred evenly and heated to 90℃. Then 98g of esterification reagent polyphosphoric acid was added to the reaction vessel, and the reaction was kept at the temperature for 6h. After cooling, the material was discharged for later use.

[0059] S3, Preparation of the dispersion material composition: 150g of component A, 150g of component B, 100g of component C, N,N-dimethylethanolamine and 600g of solvent N-methylpyrrolidone synthesized in the previous step are added to the reaction vessel in sequence. After mixing evenly, vacuum dehydration is performed. After the moisture and solid content are qualified, the material is discharged, which is the dispersion material composition.

[0060] Comparative Example 1 illustrates a method for preparing a dispersion material composition by the following steps: The high-pressure compaction dispersion material contains only dispersion component A, with the following specific formulation: 300g of the amine-containing monomer acrylamide and 1000g of the solvent N-methylpyrrolidone are added to a reaction vessel, stirred evenly, evacuated and purged with nitrogen, then heated to 60℃ and 1g of the initiator azobisisobutyronitrile is added. After reacting for 2 hours, 500g of butyl methacrylate is added, followed by 200g of hydroxyethyl phosphate methacrylate after a 2-hour interval. The reaction is maintained at this temperature for 10 hours, then stopped, cooled, and discharged to obtain component A. Subsequently, 500g of component A and 500g of the solvent N-methylpyrrolidone are added sequentially to a reaction vessel, mixed evenly, and then dehydrated under vacuum. After the moisture content meets the requirements, the material is discharged, which is the dispersion material composition.

[0061] Comparative Example 2 demonstrates a method for preparing a dispersion material composition by the following steps: The high-pressure dispersion material contains only component B, and the specific formulation is as follows: 1000g of polyether (initiator methanol, average molecular weight 500, average number of grafted EO and PO molecule 3 and 6 respectively) is added to a reaction vessel, stirred until homogeneous, and heated to 60℃. Then, 141g of esterification reagent phosphorus pentoxide is added to the reaction vessel, and the reaction is maintained at this temperature for 10 hours. After cooling, the material is discharged for later use. Subsequently, component B and 500g of solvent N-methylpyrrolidone are added sequentially to a reaction vessel, mixed thoroughly, and then vacuum dehydrated. After the moisture content meets the requirements, the material is discharged, which is the dispersion material composition.

[0062] Comparative Example 3 illustrates a method for preparing a dispersion material composition using the following steps: The dispersion material composition contains only component C. Subsequently, 500g of component C ethanolamine and 500g of solvent N-methylpyrrolidone are added sequentially to the reaction vessel, mixed evenly, and then vacuum dehydrated. After the moisture content is qualified, the material is discharged, which is the dispersion material composition.

[0063] Comparative Example 4: YTF3509, a commercially available general-purpose dispersion material.

[0064] The preparation process of the positive electrode sheets in Examples 1-6 and Comparative Examples 1-4 above: Lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and the dispersion material prepared in the examples or comparative examples were added to the tank at a mass ratio of 95.7:2:2:50:0.3. The mixture was stirred at room temperature using a dual planetary vacuum mixer (rotation speed set to 30±5 r / min revolution speed and 1300±50 r / min rotation speed, time 4h) until uniform. The uniformly dispersed slurry was then coated on aluminum foil using a coating machine (coating thickness selected as 300µm). The coated sample was then baked and dried in a 130℃ oven and rolled to obtain a flexible and bend-resistant positive electrode sheet.

[0065] The following are relevant tests for positive electrode slurry viscosity, positive electrode sheet flexibility, etc.

[0066] Table 1. Viscosity of cathode slurry and its properties of the prepared cathode sheet

[0067] Please refer to Table 1, which shows the test data of viscosity, electrode electrical properties, and flexibility of the positive electrode slurry prepared using this dispersion material. From the slurry viscosity data in Table 1, it can be seen that: comparing the initial viscosity of the slurries in Examples 1-6 and Comparative Example 4, the Examples show better dispersion; compared with Comparative Examples 1 and 2, components A and B have certain dispersion effects, but the dispersion and adhesion stability of a single component are not as good as those in the Examples; compared with Comparative Example 3, component C has an advantage in initial dispersion, but its adhesion stability is significantly lower than that of the Examples; a comprehensive analysis of the slurry dispersion performance reveals that a single component cannot simultaneously achieve both initial dispersion and slurry stability. The synergistic effect of high molecular weight ester polymers, medium and low molecular weight phosphate polymers, and small molecules of organic amine compounds can effectively achieve initial dispersion and continuous stability without rebound in the positive electrode slurry, which is beneficial for lithium battery electrode preparation and process control.

[0068] Specifically, the flexible positive electrode sheet prepared using this dispersion material composition exhibits excellent bending resistance. This is attributed to the fact that the long-chain acrylates in the dispersion material can reduce the regularity and crystallinity of PVDF, while the flexible polyether segments in the copolyphosphate ester promote the slippage of the positive electrode particles during rolling, thereby giving the positive electrode sheet better flexibility, reducing rolling pressure and increasing the electrode sheet compaction density, ensuring that the positive electrode sheet has better bending resistance during winding. From the table, the number of folds and the pressure of the electrode roller press show that the compaction density is 2.75 g / cm³. 3 In Comparative Example 3, which only contained component C without other softening components, the electrode was relatively brittle, and achieving the same compaction density required higher rolling pressure, posing significant challenges and negative impacts to the electrode production process. Comparative Example 4, as a previous generation product, showed a certain gap in electrode flexibility compared to the examples. The bending resistance of the electrodes in Comparative Examples 1 and 2 was also lower than that in Examples 1-6. This indicates that using component A or component B alone cannot achieve a good softening and compaction effect; components A, B, and C need to work synergistically. This result shows that conventional dispersion materials or single components cannot achieve the production and processing of electrodes with higher compaction densities. The dispersion material designed and prepared in this invention has excellent dispersion and adhesion properties, can significantly improve the compaction density of the electrode, and can ensure stable operation of the electrode during coating and rolling without breakage, which helps to improve the energy density of the battery and improve the production efficiency and yield of battery manufacturers.

[0069] In summary, this dispersion material composition and its preparation method, as well as component A in the flexurally resistant positive electrode, provide strong flexibility and dispersion effects. The hydroxyphosphate monomer can be anchored to the surface of the lithium iron phosphate positive electrode. This polymer has a multi-block structure, allowing a single molecule to interact simultaneously with multiple materials in the slurry system, thus maintaining long-term stable dispersion of the slurry system. Furthermore, component B, containing a large number of flexible polyether segments, can synergistically enhance the flexibility of the electrode with the block copolymer, helping to improve the electrode compaction density, reduce roller press pressure, extend equipment life, and improve coating roller pressing efficiency. Simultaneously, component C can work with the copolymer polyether ester to rapidly wet the positive electrode active material, shortening the slurry preparation time without affecting the effective solids content. Therefore, this dispersion material composition, without the addition of stabilizers, softeners, or other additives, can simultaneously achieve multiple functions such as dispersion and stabilization, flexibility and compaction enhancement, and flexural resistance, improving battery cell yield and reducing battery production costs.

[0070] Based on the above-described preferred embodiments of the present invention, and through the foregoing description, those skilled in the art can make various changes and modifications without departing from the inventive concept. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A dispersion material composition, characterized in that, It includes the following components by mass parts: Component A: 15-30 parts, Component B: 15-50 parts, Component C: 5-15 parts, Solvent: 30-50 parts; Component A includes amine-containing monomers, (meth)acrylate monomers, and (meth)acrylate hydroxyphosphate monomers; Component B comprises an alkyl polyether phosphate polymer with the chemical formula C. x H 2x+1 (EO) y (PO) z OPO3H2, wherein the number of alkyl alcohol carbon atoms on a single polymer chain is 1 to 22, the number of ethylene oxide grafts y is 0 to 50, and the number of propylene oxide grafts z is 0 to 50; Component C includes amine compounds; The mass ratio of the block copolymer containing amine monomers, (meth)acrylate monomers and (meth)acrylate hydroxyphosphate in component A is 2-4:2-5:1-2; The amine-containing monomers include 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, hexyl methacrylate, lauryl methacrylate, butyl acrylate, hexyl acrylate, and lauryl acrylate. The (meth)acrylate hydroxyphosphate monomer includes any one or more combinations of hydroxyethyl methacrylate, hydroxyhexyl methacrylate, hydroxydecyl methacrylate, hydroxyethyl phosphate, hydroxyhexyl phosphate, and hydroxydecyl phosphate. The chemical structural formula of the amine compounds in component C is as follows: Wherein, R1 is any one of H, OH, CH3, CH2CH3, CH2CH2OH, R2 is any one of H, OH, CH3, CH2CH3, CH2CH2OH, and R3 is any one of H, OH, CH3, CH2CH3, CH2CH2OH.

2. The dispersion material composition according to claim 1, characterized in that, The solvent includes either N-methylpyrrolidone or N-ethylpyrrolidone.

3. A method for preparing the dispersion material composition as described in any one of claims 1 or 2, characterized in that, Includes the following steps: S1, to prepare component A, amine-containing monomers and solvents are added to a reaction vessel, stirred evenly, evacuated and purged with nitrogen, then heated and an initiator is added. After the reaction is complete, (meth)acrylate monomers are added. After the reaction is complete, (meth)acrylate hydroxyphosphate monomers are added. The reaction is continued for a certain period of time, then the reaction is stopped and the product is cooled and discharged to obtain component A. S2, add polyether to the reaction vessel, stir evenly and heat up, then add esterification reagent to the reaction vessel, keep the reaction at the temperature for a certain time, cool and discharge for later use to obtain component B; S3, add components A, B, C and solvent to the reaction vessel respectively, mix them evenly and then dehydrate them under vacuum. After the moisture content is qualified, discharge the material to obtain the dispersion material composition.

4. The preparation method according to claim 3, characterized in that, The initiator includes any one or more combinations of azobisisobutyronitrile, azobisisoheptanenitrile, and benzoyl peroxide, and the amount of the initiator is 0.1% to 2% of the sum of the amounts of the amine-containing monomers, (meth)acrylate monomers, and (meth)acrylate hydroxyphosphate monomers, calculated by mass percentage.

5. The preparation method according to claim 3, characterized in that, The reaction temperature in S1 is 60–90°C, and the reaction time is 4–10 h. The amount of solvent added in S1 accounts for 40-60% of the total mass of component A.

6. The preparation method according to claim 3, characterized in that, The molecular weight of the polyether in S2 is 500 to 5000; The esterification reagent is either phosphorus pentoxide or polyphosphoric acid, the esterification temperature is 60-90℃, and the reaction time is 6-10h.

7. A method for preparing a flexible, bend-resistant positive electrode sheet, comprising the following steps: Step S1: The dispersion material composition as described in claim 1 or 2, lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, and N-methylpyrrolidone are added to a material tank, wherein the mass ratio of lithium iron phosphate, conductive carbon black, polyvinylidene fluoride, N-methylpyrrolidone, and dispersion material composition is (94-96):(1-3):(1-3):(40-60):(0.2-0.5). After stirring evenly at room temperature, a slurry is obtained. Step S2: The slurry is coated on aluminum foil using a coating machine, dried in an oven at 120-140°C, and then rolled using a roller press to obtain a flexible, bend-resistant positive electrode sheet.

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