A method for preparing a binder nanomaterial with a hollow structure and its application

Abstract

The present invention provides a method and application for preparing a binder nanomaterial with a hollow structure. The method comprises the following steps: (1) mixing 3-(benzylthiocarbonylthio) propionic acid, a first soft monomer, a first hard monomer, an initiator and a first solvent, performing a primary reaction under an inert atmosphere, and obtaining a first reactant after cooling; (2) performing a secondary mixing of the first reactant, a second hard monomer, a cross-linking monomer, an initiator and a second solvent obtained in step (1), performing a secondary reaction under an inert atmosphere to obtain a second reactant, and then spray-drying the second reactant to obtain the binder nanomaterial with a hollow structure. The binder nanomaterial with a hollow structure prepared by the present invention can have a larger number of particles under the same mass, thereby increasing the bonding force of the binder and simultaneously alleviating the volume change of the positive electrode material during the cycle.

Description

Technical Field

[0001] The present invention belongs to the technical field of adhesive materials, and in particular relates to a method for preparing an adhesive nanomaterial with a hollow structure and its application. Background Art

[0002] Lithium-ion batteries operate by cycling between the positive and negative electrodes during the charge and discharge process, constantly embedding and releasing lithium ions from the electrode materials. This phenomenon is often referred to as a "rocking chair battery." Lithium-ion batteries have attracted widespread attention due to their high average discharge voltage, high specific energy, high energy density, low self-discharge rate, long cycle life, clean and pollution-free operation, lightweight, compact size, and lack of memory effect.

[0003] With the rapid development of the lithium-ion battery industry, the market's performance requirements for lithium-ion batteries have gradually increased. As an important component of the positive electrode active material layer, the positive electrode binder not only binds the positive electrode active material and strengthens the bonding between the positive electrode active material and the conductive agent and current collector, but also improves the structural stability of the positive electrode sheet, thereby buffering the volume changes of the positive electrode material during the charge and discharge process. In summary, improving the comprehensive performance of the positive electrode binder will be beneficial to the further development of lithium-ion batteries.

[0004] At present, the particle morphology of the positive electrode binder materials disclosed in the prior art is mostly micron-scale spherical. At the same time, the positive electrode binder material is also a solid sphere structure, which not only increases the density of the binder, but also reduces the number of binder particles under the same mass, resulting in insufficient adhesion between the positive electrode active material and the conductive agent. Subsequently, during the battery cycle, the electrode is prone to fall off, causing the battery's specific capacity to decay rapidly.

[0005] Therefore, in this field, there is an urgent need to develop an adhesive material that not only has the advantages of low density and high adhesion, but also enables the prepared electrode to have good structural stability and electrochemical properties. Summary of the Invention

[0006] To address the shortcomings of the prior art, the present invention provides a method for preparing a hollow-structured binder nanomaterial and its application. The hollow-structured binder nanomaterial prepared by the present invention can have a higher number of particles per mass, thereby increasing the adhesive strength of the binder material and mitigating the volume changes of the positive electrode material during cycling.

[0007] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0008] In a first aspect, the present invention provides a method for preparing a binder nanomaterial having a hollow structure, the method comprising the following steps:

[0009] (1) mixing 3-(benzylthiocarbonylthio)propionic acid, a first soft monomer, a first hard monomer, an initiator, and a first solvent, reacting the mixture under an inert atmosphere, and cooling the mixture to obtain a first reactant;

[0010] (2) The first reactant, the second hard monomer, the cross-linking monomer, the initiator and the second solvent obtained in step (1) are mixed for a second time, and a secondary reaction is carried out under an inert atmosphere to obtain a second reactant, and then the second reactant is spray-dried to obtain the binder nanomaterial with a hollow structure.

[0011] Compared with the spherical micron-shaped binders used in the prior art, the binder nanomaterial with a hollow structure prepared by the present invention has the following advantages: ① Particle morphology: The binder material prepared by the present invention has a hollow structure, so the compression or expansion caused by the volume change of the positive electrode material can be offset by the unique hollow structure of the binder particles, thereby enhancing the safety and service life of the battery; ② Particle size: The binder provided by the present invention is a nanomaterial with a smaller particle size and a hollow structure. Therefore, under the same mass, the number of binder particles can be significantly increased, so that the binder particles can better bond with the active material and the conductive material, thereby enhancing the mutual adhesion; ③ Binder structure: The positive electrode binders used in the prior art are mainly random copolymer structures, and the hard monomer polymer segments and the soft monomer polymer segments are irregularly distributed on the polymer segments. The binder prepared by the present invention has a block copolymer structure. By selecting specific types of monomers, the binder particles are designed with hard monomers as nucleating monomers and soft monomers as crown monomers, so that the soft monomer polymer segments can be distributed on the particle surface, further improving its adhesion.

[0012] Preferably, in parts by weight, the weight portion of the 3-(benzylthiothiocarbonylthio) propionic acid in step (1) is 1.5 parts, the weight portion of the first soft monomer is 40-60 parts (for example, 40 parts, 42 parts, 45 parts, 48 parts, 50 parts, 52 parts, 55 parts, 58 parts, 60 parts), the weight portion of the first hard monomer is 1-2 parts (for example, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, 2 parts), and the weight portion of the initiator is 0.3-1 part. The weight parts of the first soft monomer and the first hard monomer are 50 parts, 2 parts, 0.3 parts, 1 part, 0.5 parts, 0.8 parts, and 1 part, respectively, and the weight parts of the first solvent are 80-300 parts (for example, 80 parts, 90 parts, 100 parts, 120 parts, 150 parts, 180 parts, 200 parts, 220 parts, 250 parts, 280 parts, and 300 parts, respectively). Preferably, the weight parts of the first soft monomer are 50 parts, the weight parts of the first hard monomer are 2 parts, the weight parts of the initiator are 0.3 parts, and the weight parts of the first solvent are 120 parts.

[0013] In the present invention, by adjusting the weight fractions of the above-mentioned various components, the length of the solvent-philic segment (soft monomer polymer segment) can be controlled, thereby affecting the peel strength of the adhesive and the size of the hollow spheres.

[0014] Preferably, in step (1), the first soft monomer comprises any one of isooctyl acrylate, acrylic acid, octyl acrylate, ethyl acrylate or butyl acrylate, or a combination of at least two thereof.

[0015] Preferably, in step (1), the first hard monomer comprises any one of methacrylic acid, acrylamide or acrylonitrile, or a combination of at least two of them.

[0016] Preferably, the initiator in step (1) comprises azobisisobutyronitrile and / or 4,4-azobis(4-cyanovaleric acid).

[0017] Preferably, in step (1), the first solvent comprises methanol, ethanol or isopropanol, preferably ethanol.

[0018] Preferably, the inert atmosphere in step (1) includes a nitrogen atmosphere or an argon atmosphere.

[0019] Preferably, the temperature of the primary reaction in step (1) is 60-80°C, for example, 60°C, 65°C, 70°C, 75°C, or 80°C; and the time is 1-3h, for example, 1h, 1.5h, 2h, 2.5h, or 3h.

[0020] Preferably, the temperature is lowered to room temperature in step (1).

[0021] Preferably, in terms of parts by weight, the weight of the second hard monomer in step (2) is 20-30 parts (for example, 20 parts, 22 parts, 25 parts, 28 parts, or 30 parts), the weight of the cross-linking monomer is 1-2 parts (for example, 1 part, 1.2 parts, 1.5 parts, 1.8 parts, or 2 parts), the weight of the initiator is 0.3-1 part (for example, 0.3 parts, 0.5 parts, 0.8 parts, or 1 part), and the weight of the second solvent is 80-180 parts (for example, 80 parts, 90 parts, 100 parts, 120 parts, 150 parts, or 180 parts). Preferably, the weight of the second hard monomer is 20 parts, the weight of the cross-linking monomer is 1 part, the weight of the initiator is 0.5 parts, and the weight of the second solvent is 80 parts.

[0022] In the present invention, by adjusting the weight fractions of the above-mentioned various components, the size of the solvophobic segment (hard monomer polymer segment) can be changed, thereby affecting the particle size of the hollow spheres.

[0023] Preferably, in step (2), the second solvent comprises ethanol and deionized water.

[0024] In the present invention, the mass ratio of ethanol to deionized water in the second solvent in step (2) is 1:1.

[0025] Preferably, the weight proportion of the ethanol is 40-100 parts, for example, 40 parts, 50 parts, 60 parts, 70 parts, 80 parts, 90 parts, or 100 parts.

[0026] Preferably, the weight proportion of the deionized water is 40-80 parts, for example, 40 parts, 50 parts, 60 parts, 70 parts, or 80 parts.

[0027] Preferably, the second hard monomer in step (2) comprises any one of styrene, methylstyrene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, acrylamide, methacrylamide, methyl methacrylate, methyl acrylate, cyclohexyl acrylate or cyclohexyl methacrylate, or a combination of at least two thereof.

[0028] Preferably, the cross-linking monomer in step (2) comprises divinylbenzene and / or trimethylolpropane triacrylate.

[0029] Preferably, the temperature of the secondary reaction in step (2) is 60-80°C, for example, 60°C, 65°C, 70°C, 75°C, or 80°C; and the time is 7-9h, for example, 7h, 7.5h, 8h, 8.5h, or 9h.

[0030] Preferably, the spray drying process in step (2) is carried out in a nitrogen atmosphere with an outlet temperature of 100°C and an air volume of 540m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min.

[0031] In a second aspect, the present invention provides a binder nanomaterial with a hollow structure, wherein the binder nanomaterial with a hollow structure is prepared by the method for preparing a binder nanomaterial with a hollow structure according to the first aspect.

[0032] In a third aspect, the present invention provides a positive electrode sheet comprising a positive electrode current collector and a positive electrode active material layer disposed on at least one side of the positive electrode current collector, wherein the positive electrode active material layer comprises the binder nanomaterial with a hollow structure according to the second aspect.

[0033] In a fourth aspect, the present invention provides a lithium-ion battery, comprising a positive electrode sheet, a negative electrode sheet, an electrolyte, and a separator, wherein the positive electrode sheet is the positive electrode sheet according to the third aspect.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] Compared with the spherical micron-shaped binders used in the prior art, the binder nanomaterial with a hollow structure prepared by the present invention has the following advantages: ① Particle morphology: The binder material prepared by the present invention has a hollow structure, so the compression or expansion caused by the volume change of the positive electrode material can be offset by the unique hollow structure of the binder particles, thereby enhancing the safety and service life of the battery; ② Particle size: The binder provided by the present invention is a nanomaterial with a smaller particle size and a hollow structure. Therefore, under the same mass, the number of binder particles can be significantly increased, so that the binder particles can better bond with the active material and the conductive material, thereby enhancing the mutual adhesion; ③ Binder structure: The positive electrode binders used in the prior art are mainly random copolymer structures, and the hard monomer polymer segments and the soft monomer polymer segments are irregularly distributed on the polymer segments. The binder prepared by the present invention has a block copolymer structure. By selecting specific types of monomers, the binder particles are designed with hard monomers as nucleating monomers and soft monomers as crown monomers, so that the soft monomer polymer segments can be distributed on the particle surface, further improving its adhesion. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0037] Example 1

[0038] This embodiment provides a method for preparing a binder nanomaterial having a hollow structure and the binder nanomaterial having a hollow structure, the method comprising the following steps:

[0039] (1) 1.5 parts of 3-(benzylthiocarbonylthio)propionic acid, 50 parts of isooctyl acrylate, 1.5 parts of methacrylic acid, 0.4 parts of azobisisobutyronitrile initiator, and 200 parts of ethanol were mixed once according to weight parts, reacted once at 70° C. under a nitrogen atmosphere for 2 hours, and cooled to room temperature to obtain a first reactant;

[0040] (2) The first reactant obtained in step (1), 25 parts of styrene, 1.5 parts of divinylbenzene, 0.4 parts of azobisisobutyronitrile initiator and 130 parts of a second solvent (including 70 parts of ethanol and 60 parts of deionized water) were mixed for a second time, and a secondary reaction was carried out at 70°C in a nitrogen atmosphere for 8 hours to obtain a second reactant, and then the second reactant was spray-dried at an outlet air temperature of 100°C and an air volume of 540m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min, to obtain the binder nanomaterial with a hollow structure.

[0041] Example 2

[0042] This embodiment provides a method for preparing a binder nanomaterial having a hollow structure and the binder nanomaterial having a hollow structure, the method comprising the following steps:

[0043] (1) 1.5 parts of 3-(benzylthiocarbonylthio)propionic acid, 45 parts of isooctyl acrylate, 1.2 parts of methacrylic acid, 0.4 parts of azobisisobutyronitrile initiator, and 140 parts of ethanol were mixed once by weight, reacted once at 70° C. under a nitrogen atmosphere for 2 hours, and cooled to room temperature to obtain a first reactant;

[0044] (2) The first reactant obtained in step (1), 22 parts of styrene, 1.2 parts of divinylbenzene, 0.4 parts of azobisisobutyronitrile initiator and 110 parts of a second solvent (comprising 55 parts of ethanol and 55 parts of deionized water) were mixed for a second time, and a secondary reaction was carried out under a nitrogen atmosphere at 70°C for 8 hours to obtain a second reactant, and then the second reactant was spray-dried at an outlet air temperature of 100°C and an air volume of 540m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min, to obtain the binder nanomaterial with a hollow structure.

[0045] Example 3

[0046] This embodiment provides a method for preparing a binder nanomaterial having a hollow structure and the binder nanomaterial having a hollow structure, the method comprising the following steps:

[0047] (1) 1.5 parts of 3-(benzylthiothiocarbonylthio)propionic acid, 55 parts of isooctyl acrylate, 1.8 parts of methacrylic acid, 0.6 parts of azobisisobutyronitrile initiator, and 250 parts of ethanol were mixed once by weight, reacted at 70° C. under a nitrogen atmosphere for 2 hours, and cooled to room temperature to obtain a first reactant;

[0048] (2) The first reactant obtained in step (1), 28 parts of styrene, 1.8 parts of divinylbenzene, 0.6 parts of azobisisobutyronitrile initiator and 160 parts of a second solvent (including 85 parts of ethanol and 75 parts of deionized water) were mixed for a second time, and a secondary reaction was carried out under a nitrogen atmosphere at 70°C for 8 hours to obtain a second reactant, and then the second reactant was spray-dried at an outlet air temperature of 100°C and an air volume of 540m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min, to obtain the binder nanomaterial with a hollow structure.

[0049] Example 4

[0050] This embodiment provides a method for preparing a binder nanomaterial having a hollow structure and the binder nanomaterial having a hollow structure, the method comprising the following steps:

[0051] (1) 1.5 parts of 3-(benzylthiocarbonylthio)propionic acid, 40 parts of isooctyl acrylate, 1 part of methacrylic acid, 0.3 parts of azobisisobutyronitrile initiator, and 80 parts of ethanol were mixed once by weight, reacted once at 60° C. under a nitrogen atmosphere for 3 hours, and cooled to room temperature to obtain a first reactant;

[0052] (2) The first reactant obtained in step (1), 20 parts of styrene, 1 part of divinylbenzene, 0.3 parts of azobisisobutyronitrile initiator and 80 parts of a second solvent (including 40 parts of ethanol and 40 parts of deionized water) were mixed for a second time, and a secondary reaction was carried out at 60° C. under a nitrogen atmosphere for 9 hours to obtain a second reactant, and then the second reactant was spray-dried at an outlet air temperature of 100° C. and an air volume of 540 m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min, to obtain the binder nanomaterial with a hollow structure.

[0053] Example 5

[0054] This embodiment provides a method for preparing a binder nanomaterial having a hollow structure and the binder nanomaterial having a hollow structure, the method comprising the following steps:

[0055] (1) 1.5 parts of 3-(benzylthiocarbonylthio)propionic acid, 60 parts of isooctyl acrylate, 2 parts of methacrylic acid, 1 part of azobisisobutyronitrile initiator, and 300 parts of ethanol were mixed once according to weight parts, reacted once at 80° C. under a nitrogen atmosphere for 1 hour, and cooled to room temperature to obtain a first reactant;

[0056] (2) The first reactant obtained in step (1), 30 parts of styrene, 2 parts of divinylbenzene, 1 part of azobisisobutyronitrile initiator and 180 parts of a second solvent (including 100 parts of ethanol and 80 parts of deionized water) were mixed for a second time, and a secondary reaction was carried out under a nitrogen atmosphere at 80° C. for 7 h to obtain a second reactant, and then the second reactant was spray-dried at an outlet air temperature of 100° C. and an air volume of 540 m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min, to obtain the binder nanomaterial with a hollow structure.

[0057] Example 6

[0058] The difference between this embodiment and embodiment 1 is that in step (1), the weight proportions of isooctyl acrylate and methacrylic acid are 35 parts and 0.5 parts, respectively. Other aspects are the same as those in embodiment 1.

[0059] Example 7

[0060] The difference between this embodiment and embodiment 1 is that in step (1), the weight parts of isooctyl acrylate are 65 parts and the weight parts of methacrylic acid are 4 parts. Other parts are the same as those in embodiment 1.

[0061] Example 8

[0062] The difference between this embodiment and embodiment 1 is that the weight parts of styrene and divinylbenzene in step (2) are 15 parts and 0.5 parts respectively, and the other parts are the same as those in embodiment 1.

[0063] Example 9

[0064] The difference between this embodiment and embodiment 1 is that the weight parts of styrene and divinylbenzene in step (2) are 35 parts and 4 parts respectively, and the rest are the same as those in embodiment 1.

[0065] Example 10

[0066] The difference between this embodiment and embodiment 1 is that the outlet air temperature of the spray drying process in step (2) is 70°C and the air volume is 540m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min to obtain the binder nanomaterial with a hollow structure. Others are the same as in Example 1.

[0067] Example 11

[0068] The difference between this embodiment and embodiment 1 is that the outlet air temperature of the spray drying process in step (2) is 120°C and the air volume is 540m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min to obtain the binder nanomaterial with a hollow structure. Others are the same as in Example 1.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 1 is that no spray drying treatment is performed in step (2), and the other steps are the same as those in Example 1.

[0071] Comparative Example 2

[0072] This comparative example provides a method for preparing a binder having a solid spherical structure, which comprises the following steps:

[0073] (1) After stirring and pre-emulsifying 1.5 parts of 3-(benzylthiothiocarbonylthio)propionic acid, 20 parts of styrene, 1.5 parts of divinylbenzene, 10 parts of isooctyl acrylate, 0.4 parts of potassium persulfate, 0.08 parts of polyvinylpyrrolidone PVP-K30 and 150 parts of water in parts by weight, the mixture was dropwise added to 50 parts of water under a nitrogen atmosphere at 70° C. for 2.5 hours, then the temperature was raised to 75° C. and the reaction was continued for 3 hours. The reaction was then cooled to room temperature to obtain a first reactant;

[0074] (2) After stirring and pre-emulsifying 5 parts of styrene, 40 parts of isooctyl acrylate, 0.4 parts of potassium persulfate, 0.12 parts of polyvinylpyrrolidone PVP-K30 and 100 parts of water, the pre-emulsified liquid was added dropwise to the first reactant obtained in step (1), and the mixture was added dropwise at 70°C under a nitrogen atmosphere for 2.5 hours, and then the temperature was raised to 75°C and the reaction was continued for 3 hours to obtain a second reactant, and then the second reactant was spray-dried at an outlet air temperature of 100°C and an air volume of 540m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min, to obtain the binder nanomaterial with a hollow structure.

[0075] Application Examples 1 to 11 and Comparative Application Examples 1 to 2

[0076] Lithium-ion batteries were prepared using the hollow-structured binder nanomaterials provided in Examples 1 to 11 and Comparative Examples 1 and 2. The preparation method is as follows:

[0077] Preparation of the positive electrode sheet: The binder provided in the above examples and comparative examples and N-methylpyrrolidone were mixed to prepare a binder solution with a mass fraction of 7%. Then, 28 parts by weight of N-methylpyrrolidone, 1 part of conductive carbon Super.P, and 0.5 parts of conductive graphite KS-6 were added to a double planetary mixer and stirred for 1 hour. 45 parts of the binder solution were added and stirred for 1.5 hours. 100 parts of DY-3 active material were added and stirred for 30 minutes to obtain a positive electrode slurry. The positive electrode slurry was then coated on a carbon-coated aluminum foil and baked at 100°C for 1 minute to obtain a positive electrode sheet.

[0078] Preparation of the negative electrode sheet: Graphite, conductive carbon black, sodium carboxymethyl cellulose, and styrene-butadiene latex were mixed in a mass ratio of 94.5:1:2.25:2.25, and deionized water was added to obtain a negative electrode slurry. The negative electrode slurry was then scraped onto the surface of a copper foil and dried to obtain a negative electrode sheet.

[0079] Preparation of lithium-ion battery: Assemble the above-mentioned positive electrode sheet, negative electrode sheet, electrolyte and separator to obtain a lithium-ion battery.

[0080] Test conditions

[0081] The positive electrode sheets provided by Application Examples 1 to 11 and Comparative Application Examples 1 to 2 were tested, and the preparation method was as follows:

[0082] (1) Peel force test: The stainless steel plate and the current collector were fixed on the fixture of the peel force tester and a 180-degree peel test was performed at a speed of 10 mm / min and a load of 10 N.

[0083] (2) High-temperature volume expansion rate test: At 25°C, charge the battery sample to 100% SOC at a constant current of 0.1C. Place the sample in an oven and heat it to 150°C at a heating rate of 5°C / min, then switch to a constant temperature and maintain for 30 minutes. After taking it out, check the battery volume expansion rate (volume expansion rate (%) = (maximum cross-sectional perimeter of the battery after expansion / maximum cross-sectional perimeter of the battery before expansion) × 100%)

[0084] The lithium-ion batteries provided in Application Examples 1 to 11 and Comparative Application Examples 1 to 2 were tested, and the preparation methods were as follows:

[0085] (1) Cycling performance test: The battery was charged at 25°C at a constant current of 3000mA (1C) to 4.5V, then charged at a constant voltage with a cut-off current of 150mA, and then discharged at a constant current of 3000mA to 3V. This was considered one cycle. After repeating this cycle 500 times, the residual capacity after the cycle (%) was calculated as (discharge capacity after n cycles / initial discharge capacity) × 100%.

[0086] The test results are shown in Table 1:

[0087] Table 1

[0088]

[0089]

[0090] As can be seen from Table 1, the hollow structured binder nanomaterial provided by the present invention has a smaller particle size and a hollow structure. Therefore, the number of binder particles can be significantly increased under the same mass, so that the binder particles can better bond with the active material and the conductive material, thereby enhancing the mutual adhesion. At the same time, the volume expansion is smaller and the cycle performance of the battery is improved.

[0091] Compared with Application Example 1, Application Examples 6-9 show that by regulating the weight proportions of each component, the prepared adhesive material has good performance; Application Examples 10-11 show that the spray drying treatment temperature is too low, resulting in the moisture content of the obtained powder being higher than the standard (should be less than 0.5%), and the treatment temperature is too high, which may cause the powder to turn yellow and oxidize, affecting the appearance and peel strength.

[0092] Compared with Application Example 1, the adhesive materials obtained in Comparative Application Example 1 and Comparative Application Example 2 cannot achieve the technical effect of the present application.

[0093] The applicant states that while the above-described embodiments illustrate the process of the present invention, the present invention is not limited to the above-described process steps, nor does it imply that the present invention must rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for preparing a binder nanomaterial having a hollow structure, characterized in that: The method comprises the following steps: (1) mixing 3-(benzylthiocarbonylthio)propionic acid, a first soft monomer, a first hard monomer, an initiator, and a first solvent, reacting the mixture under an inert atmosphere, and cooling the mixture to obtain a first reactant; (2) the first reactant obtained in step (1), the second hard monomer, the crosslinking monomer, the initiator and the second solvent are mixed for a second time, and a secondary reaction is carried out under an inert atmosphere to obtain a second reactant, and then the second reactant is spray-dried to obtain the binder nanomaterial having a hollow structure; In step (1), the first soft monomer comprises any one of isooctyl acrylate, octyl acrylate, ethyl acrylate or butyl acrylate, or a combination of at least two thereof; In step (1), the first hard monomer comprises any one of methacrylic acid, acrylamide or acrylonitrile, or a combination of at least two thereof; The second hard monomer in step (2) includes any one of styrene, methylstyrene, acrylonitrile, methacrylonitrile, acrylic acid, methacrylic acid, acrylamide, methacrylamide, methyl methacrylate, methyl acrylate, cyclohexyl acrylate or cyclohexyl methacrylate, or a combination of at least two thereof.

2. The method according to claim 1, characterized in that In parts by weight, the weight of the 3-(benzylthiothiocarbonylthio)propionic acid in step (1) is 1.5 parts, the weight of the first soft monomer is 40-60 parts, the weight of the first hard monomer is 1-2 parts, the weight of the initiator is 0.3-1 parts, and the weight of the first solvent is 80-300 parts.

3. The method according to claim 2, characterized in that In parts by weight, the weight of 3-(benzylthiothiocarbonylthio)propionic acid in step (1) is 1.5 parts, the weight of the first soft monomer is 50 parts, the weight of the first hard monomer is 2 parts, the weight of the initiator is 0.3 parts, and the weight of the first solvent is 120 parts.

4. The method according to claim 1, wherein The initiator in step (1) includes azobisisobutyronitrile and / or 4,4-azobis(4-cyanovaleric acid).

5. The method according to claim 1, wherein In step (1), the first solvent includes methanol, ethanol or isopropanol.

6. The method according to claim 5, characterized in that In step (1), the first solvent is ethanol.

7. The method according to claim 1, characterized in that The inert atmosphere in step (1) includes a nitrogen atmosphere or an argon atmosphere.

8. The method according to claim 1, characterized in that The temperature of the primary reaction in step (1) is 60-80° C., and the time is 1-3 h.

9. The method according to claim 1, characterized in that Cooling to room temperature as described in step (1).

10. The method according to claim 1, characterized in that In terms of parts by weight, in step (2), the weight of the second hard monomer is 20-30 parts, the weight of the crosslinking monomer is 1-2 parts, the weight of the initiator is 0.3-1 parts, and the weight of the second solvent is 80-180 parts.

11. The method according to claim 10, characterized in that In terms of parts by weight, in step (2), the weight of the second hard monomer is 20 parts, the weight of the crosslinking monomer is 1 part, the weight of the initiator is 0.5 parts, and the weight of the second solvent is 80 parts.

12. The method according to claim 1, characterized in that In step (2), the second solvent includes ethanol and deionized water.

13. The method according to claim 12, characterized in that The weight proportion of the ethanol is 40-100 parts.

14. The method according to claim 12, characterized in that The weight proportion of the deionized water is 40-80 parts.

15. The method according to claim 1, wherein The cross-linking monomer in step (2) includes divinylbenzene and / or trimethylolpropane triacrylate.

16. The method according to claim 1, wherein The temperature of the secondary reaction in step (2) is 60-80° C. and the time is 7-9 hours.

17. The method according to claim 1, wherein The spray drying process in step (2) is carried out under a nitrogen atmosphere with an outlet temperature of 100°C and an air volume of 540m 3 / h, the gas flow meter wind speed is 15L / min, and the peristaltic pump speed is 6mL / min.

18. A binder nanomaterial with a hollow structure, characterized in that: The binder nanomaterial with a hollow structure is prepared by the method for preparing a binder nanomaterial with a hollow structure according to any one of claims 1-17.

19. A positive electrode sheet, characterized in that: The positive electrode sheet includes a positive electrode current collector and a positive electrode active material layer arranged on at least one side of the positive electrode current collector, and the positive electrode active material layer includes the binder nanomaterial with a hollow structure according to claim 18.

20. A lithium ion battery, characterized in that: The lithium-ion battery includes a positive electrode sheet, a negative electrode sheet, an electrolyte and a separator, and the positive electrode sheet is the positive electrode sheet according to claim 19.

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