Slurry of high-nickel positive electrode active material and preparation method and application thereof

Abstract

The application belongs to the technical field of new energy materials, and particularly relates to a slurry of high-nickel positive electrode active material and a preparation method and application thereof. The slurry comprises a solid component and a solvent, and the solid component comprises the following components with the mass percentage of 94%-98.5% of high-nickel positive electrode active material, 0.005%-0.5% of antioxidant, 0.01%-0.5% of halosilane, 1%-2% of polyvinylidene fluoride and 0.5%-3% of conductive agent. The slurry of high-nickel positive electrode active material in the application can inhibit the gelation of the slurry, and a battery containing the slurry has high capacity performance and excellent performance when applied to an electrical equipment.

Description

Technical Field

[0001] This invention belongs to the field of new energy materials technology, specifically relating to a slurry of a high-nickel cathode active material, its preparation method, and its application. Background Technology

[0002] Lithium nickel cobalt manganese oxide (transition metal elements including Ni, Co, and Mn, referred to as ternary materials) is one of the most commonly used cathode materials for high specific energy in power batteries. The higher the proportion of Ni, the more electrons can participate in the electrochemical reaction, and the higher the specific capacity and energy density of the ternary material.

[0003] However, as the nickel content increases (especially in high-nickel ternary materials with a nickel content >60%), the amount of lithium salts remaining on the material surface increases, leading to an increase in surface alkali. For example, the alkali content of NCM811 is about 5.5 times that of NCM622. Such a high alkali content causes a sharp decline in the processing performance of high-nickel ternary materials. That is, during use, the viscosity of high-nickel ternary slurry increases rapidly over time, loses its fluidity, and cannot be coated. This phenomenon is called "gelation" or "jelly-like" of high-nickel ternary slurry.

[0004] Because high-nickel cathode materials cannot come into contact with water, water cannot be used as a solvent during homogenization, which prevents the application of water-soluble binders. Generally, organic solvents such as N-methylpyrrolidone (NMP) are chosen as solvents when homogenizing cathode materials. Polyvinylidene fluoride (PVDF) has good solubility in these organic solvents, is chemically stable, and has strong binding ability, making it almost the only choice for cathode material binders in the industry.

[0005] The fundamental reason for the gelation of high-nickel ternary slurry is that the base groups (residual alkali on the surface of high-nickel ternary materials or amine groups in NMP) attack the CH and CF groups of polyvinylidene fluoride, causing an elimination reaction and forming C=C double bonds to produce chemical crosslinking. Because the polyvinylidene fluoride chain has a high degree of regularity, it is easy to undergo continuous deHF removal reaction, which in turn leads to crosslinking polymerization reaction, ultimately resulting in slurry gelation.

[0006] Currently, solutions to the above problems include (1) washing with water to reduce the residual alkali content of high-nickel ternary materials; and (2) adding oxalic acid to the slurry to neutralize the residual alkali. However, although washing the material with water can remove most of the residual alkali, it will be accompanied by a decrease in capacity; and the reaction of oxalic acid to neutralize the residual alkali will generate water, which will cause side reactions between water and electrolyte and negative electrode interface, reducing battery capacity. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the defect that inhibiting the gelation of high nickel cathode active material slurry will lead to a decrease in battery capacity in the prior art, thereby providing a high nickel cathode active material slurry, its preparation method and application.

[0008] Therefore, the present invention provides the following technical solution:

[0009] The first aspect of this invention protects a slurry for a high-nickel cathode active material, wherein the slurry comprises a solid component and a solvent, and, based on the total mass of the solid component, comprises the following components in mass percentage:

[0010] High-nickel cathode active material: 94%-98.5%;

[0011] Antioxidant 0.005%-0.5%;

[0012] Halogenated silanes 0.01%-0.5%;

[0013] Polyvinylidene fluoride 1%-2%;

[0014] Conductive agent 0.5%-3%.

[0015] According to the present invention, the antioxidant includes at least one of tert-butylhydroanisole (BHA), 2,6-di-tert-butyl-p-benzophenol (BHT), propyl gallate (PG), tert-butylhydroquinone, and benzoquinone, and may be selected as tert-butylhydroanisole and / or 2,6-di-tert-butyl-p-benzophenol.

[0016] In this invention, the antioxidant mechanism is taken as an example using BHT, specifically as follows:

[0017]

[0018] According to the present invention, the halosilane includes silicon tetrachloride and / or hexachlorosilane.

[0019] In this invention, the specific reaction formula for silicon tetrachloride is as follows:

[0020] SiCl4+H2O→H4SiO4+H2SiO3+HCl;

[0021] SiCl4 + LiOH → SiO2 + HCl + LiCl.

[0022] According to the present invention, the conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphene.

[0023] According to the present invention, the conductive agent includes a first conductive agent and a second conductive agent;

[0024] The first conductive agent includes at least one of conductive carbon black, conductive graphite, and carbon fiber;

[0025] The second conductive agent includes at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphene.

[0026] According to the present invention, based on the total solid mass percentage in the slurry of the high-nickel cathode active material, the dosage of the first conductive agent is 1% - 2%, and the dosage of the second conductive agent is 0.2% - 0.8%.

[0027] In the present invention, the nickel content of the high-nickel cathode active material of the cathode material is above 70%; the high-nickel cathode active material includes at least one of high-nickel ternary cathode material, cobalt-free cathode material, and quaternary cathode material; the composition of the high-nickel ternary cathode material is LiNi x Co y Mn 1-x-y O2, where 0.7 ≤ x < 1, 0 < y ≤ 0.3, 0 < x + y < 1; the composition of the cobalt-free cathode material is LiNi x Mn 1-x O2, where 0.7 ≤ x < 1; the composition of the quaternary cathode material is LiNi x Co y Mn z Al 1-x-y-z O2, where 0 < x + y + z < 1.

[0028] According to the present invention, the number-average molecular weight of the polyvinylidene fluoride is 500,000 - 1,500,000.

[0029] According to the present invention, the mass ratio of the solvent to the polyvinylidene fluoride is (90 - 100):(1 - 10).

[0030] According to the present invention, the solvent includes at least one of N-methylpyrrolidone (NMP), N-ethylpyrrolidone (NEP), and dimethyl sulfoxide (DMSO), and preferably N-methylpyrrolidone.

[0031] The second aspect of the present invention protects a preparation method of the aforementioned slurry, wherein the high-nickel cathode active material, antioxidant, halogenated silane, polyvinylidene fluoride, and conductive agent are mixed to obtain the slurry of the high-nickel cathode active material.

[0032] According to the present invention, the preparation method includes the following steps:

[0033] S1, perform the first mixing of the polyvinylidene fluoride and the solvent to obtain a colloidal solution;

[0034] S2, perform the second mixing of the above colloidal solution, conductive agent, and high-nickel cathode active material to obtain a mixture;

[0035] S3, add an antioxidant and silicon tetrachloride to the mixture for the third mixing to obtain the slurry of the high-nickel cathode active material.

[0036] In the present invention, the preparation of the colloidal solution is carried out in a colloidal solution preparation machine.

[0037] According to the present invention, in step S2, the first conductive agent is mixed with the adhesive to obtain conductive adhesive A, and the second conductive agent is added and mixed to obtain conductive adhesive B; then the conductive adhesive is mixed with a high-nickel positive electrode active material to obtain a mixture.

[0038] In this invention, the conditions for the first mixing, the second mixing, and the third mixing are conventional conditions in the art, as long as they can mix evenly.

[0039] A third aspect of the present invention protects a secondary battery, wherein the battery comprises a slurry of the aforementioned high-nickel positive electrode active material.

[0040] In this invention, the battery preparation method is a conventional practice in the art. Typically, and not specifically, the prepared positive electrode slurry containing high-nickel positive electrode active material is uniformly coated onto the current collector aluminum foil, with a coating amount of 12-14 mg / cm². 2 After drying at 85-90℃, the material is cold-pressed, trimmed, cut into pieces, and slit. Then, it is dried under vacuum at 85-90℃ for 3-4 hours, and the tabs are welded to produce the positive electrode sheet of a lithium-ion secondary battery that meets the requirements.

[0041] The negative electrode active material, artificial graphite, conductive agent Super-P, thickener CMC, and binder SBR are dissolved in deionized water at a mass ratio of (96-98):(1.0-1.1):(1.0-1.1):(1.2-1.5) and mixed evenly to prepare a negative electrode slurry. The negative electrode slurry is then uniformly coated onto the current collector copper foil with a coating amount of 8-9 mg / cm². 2 After drying at 85-90℃, the material is cold-pressed, trimmed, cut into pieces, and slit. Then, it is dried under vacuum at 110-120℃ for 3-4 hours, and the tabs are welded to produce the negative electrode sheet of the lithium-ion secondary battery that meets the requirements.

[0042] The electrolyte, positive electrode, negative electrode and separator (PE film) obtained in the examples and comparative examples were stacked to form a battery with a thickness of 8 mm, a width of 60 mm and a length of 130 mm. The battery was then vacuum baked at 85°C for 10 h, injected with electrolyte and left to stand for 24 h.

[0043] A fourth aspect of this invention protects an electrical device, which includes the aforementioned secondary battery.

[0044] The technical solution of this invention has the following advantages:

[0045] This invention provides a slurry for a high-nickel cathode active material, comprising a solid component and a solvent. The solid component, by mass percentage, comprises the following components: 94%-98.5% high-nickel cathode active material; 0.005%-0.5% antioxidant; 0.01%-0.5% halosilane; 1%-2% polyvinylidene fluoride (PVDF); and 0.5%-3% conductive agent. The slurry of this invention's high-nickel cathode active material does not exhibit gelation. During use, residual base groups on the surface of the high-nickel ternary cathode material attack PVDF, causing it to polymerize. The antioxidant of this invention inhibits the removal of H+. + With F - Polyvinylidene fluoride undergoes a cross-linking reaction to form a gel; while silicon tetrachloride reacts with the positive electrode material to generate water and residual alkali during operation. Compared with oxalic acid, silicon tetrachloride does not undergo side reactions, and it is inexpensive, highly reactive, and fast-reacting. As a result, batteries containing the high-nickel positive electrode active material of this invention will not experience gelation and will maintain excellent capacity performance.

[0046] In this invention, when the antioxidants are tert-butyl-p-hydroxyanisole and 2,6-di-tert-butyl-p-benzophenol, the flow characteristics of the slurry can be further improved, thereby increasing the battery capacity.

[0047] This invention defines the first type of conductive agent and the second type of conductive agent, which can further improve the flow characteristics of the slurry and increase the capacity of the high-nickel cathode material. Attached Figure Description

[0048] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0049] Figure 1 The slurry of the high-nickel cathode active material prepared in Example 1;

[0050] Figure 2 The slurry of high-nickel cathode active material prepared in Comparative Example 2. Detailed Implementation

[0051] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0052] For experiments not specifically described in the examples, the procedures or conditions should be followed according to the conventional experimental procedures described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0053] Example 1

[0054] This embodiment provides a slurry for a high-nickel cathode active material. Based on the total solids mass percentage in the slurry, polyvinylidene fluoride (PVDF) is 1.2%, conductive carbon black is 1%, single-walled carbon nanotubes are 0.5%, and cobalt-free high-nickel cathode active material (LiNi) is also included. 0.75 Mn 0.25 The content of O2 was 97.1%, 2,6-di-tert-butyl-p-cresol was 0.1%, silicon tetrachloride was 0.1%; the mass ratio of N-methylpyrrolidone to polyvinylidene fluoride was 93:7;

[0055] The specific method for preparing the slurry of the high-nickel cathode active material is as follows:

[0056] S1, N-methylpyrrolidone and polyvinylidene fluoride are added to the glue-making machine for the first mixing to obtain the glue solution;

[0057] S2, add conductive carbon black to the above adhesive solution and mix to obtain conductive adhesive A; add single-walled carbon nanotubes to conductive adhesive A and mix to obtain conductive adhesive B; then mix conductive adhesive B with cobalt-free high-nickel cathode active material LiNi. 0.75 Mn 0.25 O2 is mixed to obtain a mixture;

[0058] S3, the mixture is mixed with silicon tetrachloride and 2,6-di-tert-butyl-p-cresol to obtain a slurry of high-nickel cathode active material;

[0059] The high-nickel cathode active material prepared in Example 1 is as follows: Figure 1 As shown, from Figure 1 As can be seen from the example, the slurry of the high-nickel cathode active material prepared in Example 1 can flow freely and be successfully coated.

[0060] Example 2

[0061] This embodiment provides a slurry for a high-nickel cathode active material. Based on the total solids mass percentage in the slurry, polyvinylidene fluoride (PVDF) is 1.2%, conductive carbon black is 1%, single-walled carbon nanotubes are 0.5%, and high-nickel ternary high-nickel cathode active material (LiNi) is also present. 0.8 Co 0.1 Mn 0.1The content of O2 was 97.1%, 2,6-di-tert-butyl-p-cresol was 0.1%, silicon tetrachloride was 0.1%; the mass ratio of N-methylpyrrolidone to polyvinylidene fluoride was 93:7;

[0062] The specific method for preparing the slurry of the high-nickel cathode active material is as follows:

[0063] The procedure was carried out in accordance with Example 1, except that the dosage was different.

[0064] Example 3

[0065] This embodiment provides a slurry for a high-nickel cathode active material. Compared with Example 1, the difference is that an equal mass of tert-butyl-p-hydroxyanisole is used instead of 2,6-di-tert-butyl-p-benzophenol.

[0066] Example 4

[0067] This embodiment provides a slurry for a high-nickel cathode active material. Compared with Example 1, the difference is that 2,6-di-tert-butyl-p-benzophenol and tert-butyl-p-hydroxyanisole (wherein, the total mass of 2,6-di-tert-butyl-p-benzophenol and tert-butyl-p-hydroxyanisole is equal to the mass of 2,6-di-tert-butyl-p-benzophenol in Example 1, and the mass ratio of 2,6-di-tert-butyl-p-benzophenol to tert-butyl-p-hydroxyanisole is 1:1) are used instead of 2,6-di-tert-butyl-p-benzophenol.

[0068] Example 5

[0069] This embodiment provides a slurry for a high-nickel cathode active material. Compared with Example 1, the difference is that benzoquinone of equal mass is used instead of 2,6-di-tert-butyl-p-cresol.

[0070] Example 6

[0071] This embodiment provides a slurry for a high-nickel cathode active material. Based on the total solids percentage in the slurry, polyvinylidene fluoride (PVDF) is 1.2%, conductive carbon black is 1.5%, cobalt-free high-nickel cathode active material is 97.2%, 2,6-di-tert-butyl-p-cresol is 0.1%, and silicon tetrachloride is 0.1%. The mass ratio of N-methylpyrrolidone to PVDF is 93:7.

[0072] The specific method for preparing the slurry of the high-nickel cathode active material is as follows:

[0073] S1, proceed according to step S1 of Example 1;

[0074] S2, add conductive carbon black to the above adhesive solution and mix to obtain conductive adhesive; then mix the conductive adhesive with cobalt-free high-nickel cathode active material LiNi. 0.75 Mn 0.25 O2 is mixed to obtain a mixture;

[0075] S3, proceed according to step S3 of Example 1.

[0076] Example 7

[0077] This embodiment provides a slurry for a high-nickel cathode active material. Based on the total solid mass percentage of the slurry, polyvinylidene fluoride (PVDF) accounts for 1.8%, conductive carbon black 1.5%, single-walled carbon nanotubes 0.3%, and high-nickel ternary high-nickel cathode active material (LiNi)... 0.8 Co 0.1 Mn 0.1 The content of O2 was 96.2%, 2,6-di-tert-butyl-p-cresol was 0.1%, silicon tetrachloride was 0.1%; the mass ratio of N-methylpyrrolidone to polyvinylidene fluoride was 93:7;

[0078] The specific method for preparing the slurry of the high-nickel cathode active material is as follows:

[0079] The procedure was carried out in accordance with Example 1, except that the dosage was different.

[0080] Comparative Example 1

[0081] The difference between this comparative example and Example 1 is that 0.1% of silicon tetrachloride was removed from the solids in the slurry, and the content of the positive electrode active material was increased by 0.1% to 97.2%, while the types and amounts of other components remained unchanged.

[0082] The specific method for preparing the slurry of the high-nickel cathode active material is as follows:

[0083] The procedure was carried out in accordance with Example 1, except that silicon tetrachloride was not added in step S3.

[0084] Comparative Example 2

[0085] The difference between this comparative example and Example 1 is that 0.1% of 2,6-di-tert-butyl-p-cresol was removed from the slurry, and the content of the positive electrode active material was increased by 0.1% to 97.2%, while the types and amounts of other components remained unchanged.

[0086] The specific method for preparing the slurry of the high-nickel cathode active material is as follows:

[0087] The procedure was carried out as in Example 1, except that in step S3, 2,6-di-tert-butyl-p-cresol was not added.

[0088] The material prepared in Comparative Example 2 is as follows Figure 2 As shown in the figure, the slurry is in a solidified state, with severe gelation, making it impossible to coat properly.

[0089] Comparative Example 3

[0090] This comparative example provides a slurry of a high-nickel cathode active material. The difference between this example and Example 1 is that an equal mass of oxalic acid is used instead of silicon tetrachloride.

[0091] Test case

[0092] (1) The slurries prepared in the examples and comparative examples were placed in air for 2 hours, and their flowability was tested. The flowability was measured using a rheometer at the same shear rate (0.1 / s) for different slurries. -1 The shear viscosity at ) is shown in Table 1.

[0093] Table 1

[0094] Shear viscosity (Pa·s) Example 1 1020 Example 2 1080 Example 3 1010 Example 4 980 Example 5 1400 Example 6 1500 Example 7 1060 Comparative Example 1 6000 (light gel) Comparative Example 2 5800 (Slight Gel) Comparative Example 3 2000

[0095] (2) The prepared positive electrode slurry containing high-nickel positive electrode active material is uniformly coated onto the current collector aluminum foil, with a coating amount of 13.8 mg / cm². 2 After drying at 85°C, the material is cold-pressed, trimmed, cut into pieces, and slit. Then, it is dried under vacuum at 85°C for 4 hours, and the tabs are welded to produce the positive electrode sheet of a lithium-ion secondary battery that meets the requirements.

[0096] A negative electrode slurry was prepared by dissolving artificial graphite (anode active material), Super-P (conductive agent), CMC (thickener), and SBR (binder) in deionized water at a mass ratio of 96.5:1.0:1.0:1.5. The slurry was then uniformly coated onto the current collector copper foil at a coating weight of 8.3 mg / cm². 2 After drying at 85℃, the material is cold-pressed, trimmed, cut into pieces, and slit. Then, it is dried under vacuum at 110℃ for 4 hours, and the tabs are welded to produce a negative electrode sheet for a lithium-ion secondary battery that meets the requirements.

[0097] The electrolyte, positive electrode, negative electrode, and separator (PE film) obtained in the examples and comparative examples were stacked to form a battery with a thickness of 8 mm, a width of 60 mm, and a length of 130 mm. The battery was vacuum baked at 85°C for 10 h, injected with electrolyte, and left to stand for 24 h. Then, it was charged to 4.2 V with a constant current of 0.1 C (200 mA), and then charged at a constant voltage of 4.2 V until the current dropped to 0.05 C (100 mA). Then, it was discharged to 2.8 V with a constant current of 0.1 C (200 mA) (the discharge capacity C0 here is recorded as the battery capacity). This charge and discharge cycle was repeated twice. Finally, it was charged to 3.65 V with a constant current of 0.1 C (200 mA) to obtain a lithium-ion battery.

[0098] The specific results are shown in Table 2.

[0099] Table 2

[0100] Battery capacity C0 (mAh) Example 1 2004 Example 2 1995 Example 3 2005 Example 4 2009 Example 5 1992 Example 6 1991 Example 7 2003 Comparative Example 1 1972 Comparative Example 2 1975 Comparative Example 3 1962

[0101] The data in Tables 1 and 2 show that the lower the shear viscosity of the embodiments of the present invention, the better the fluidity, and at the same time, it has excellent capacity performance.

[0102] A comparison of Example 1 and Comparative Example 3 shows that although Comparative Example 3, which uses oxalic acid, still maintains good fluidity, the battery capacity decreases because water is generated when oxalic acid neutralizes the residual alkali, thus failing to meet actual needs.

[0103] A comparison of Examples 1 and 4 shows that when tert-butyl-p-hydroxyanisole and 2,6-di-tert-butyl-p-benzophenol are used simultaneously, the flow characteristics of the slurry can be further improved, thereby increasing the battery capacity.

[0104] A comparison of Example 1 and Example 6 shows that there is a synergistic effect between the first conductive agent and the second conductive agent in this invention, which can improve the fluidity and stability of the slurry and increase the capacity of the cathode material.

[0105] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A slurry for a high-nickel cathode active material, characterized in that, The slurry comprises solid components and solvent, and based on the total mass of the solid components, it includes the following components by mass percentage: High-nickel cathode active material: 94%-98.5%; Antioxidant content: 0.005%-0.5%; Halogenated silanes 0.01%-0.5%; Polyvinylidene fluoride 1%-2%; Conductive agent 0.5%-3%; The antioxidant includes at least one of tert-butylhydroanisole, 2,6-di-tert-butyl-p-benzophenol, propyl gallate, tert-butylhydroquinone, and benzoquinone. The halosilanes include silicon tetrachloride and / or hexachlorosilane.

2. The slurry according to claim 1, characterized in that, The antioxidants include tert-butyl-p-hydroxyanisole and / or 2,6-di-tert-butyl-p-benzophenol.

3. The slurry according to claim 1 or 2, characterized in that, The conductive agent includes at least one of conductive carbon black, conductive graphite, carbon fiber, single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphene.

4. The slurry according to claim 1, characterized in that, The conductive agent includes a first conductive agent and a second conductive agent; The first conductive agent includes at least one of conductive carbon black, conductive graphite, and carbon fiber; The second conductive agent includes at least one of single-walled carbon nanotubes, multi-walled carbon nanotubes, and graphene; And / or, based on the total mass percentage of solids in the slurry of the high-nickel cathode active material, the amount of the first conductive agent is 1%-2%, and the amount of the second conductive agent is 0.2%-0.8%.

5. The slurry according to claim 1, characterized in that, The high-nickel cathode active material includes at least one of high-nickel ternary cathode material, cobalt-free cathode material, and quaternary cathode material; the composition of the high-nickel ternary cathode material is LiNi x Co y Mn 1-x-y O2, where 0.7 ≤ x < 1, 0 < y ≤ 0.3, 0 < x + y < 1; the composition of the cobalt-free cathode material is LiNi x Mn 1-x O2, where 0.7 ≤ x < 1; the composition of the quaternary cathode material is LiNi x Co y Mn z Al 1-x-y-z O2, where 0 < x + y + z < 1.

6. The slurry according to claim 1, characterized in that, The number average molecular weight of the polyvinylidene fluoride is 500,000 to 1,500,000. And / or, the mass ratio of the solvent to the polyvinylidene fluoride is (90-100):(1-10); And / or, the solvent includes at least one of N-methylpyrrolidone, N-ethylpyrrolidone, and dimethyl sulfoxide.

7. The slurry according to claim 6, characterized in that, The solvent is N-methylpyrrolidone.

8. A method for preparing the slurry according to any one of claims 1-7, characterized in that, A slurry of high-nickel cathode active material is obtained by mixing high-nickel cathode active material, antioxidant, halosilane, polyvinylidene fluoride, and conductive agent.

9. The preparation method according to claim 8, characterized in that, The preparation method includes the following steps: S1, Polyvinylidene fluoride and solvent are mixed for the first time to obtain a glue solution; S2, the above-mentioned adhesive, conductive agent, and high-nickel positive electrode active material are mixed a second time to obtain a mixture; S3, the mixture, antioxidant, and silicon tetrachloride are mixed for the third time to obtain a slurry of high-nickel positive electrode active material.

10. The preparation method according to claim 9, characterized in that, In step S2, the first conductive agent is mixed with the adhesive to obtain conductive adhesive A, and the second conductive agent is added and mixed to obtain conductive adhesive B; then conductive adhesive B is mixed with high nickel positive electrode active material to obtain a mixture.

11. A secondary battery, characterized in that, The battery comprises a slurry of the high-nickel cathode active material as described in any one of claims 1-7.

12. An electrical appliance, characterized in that, Includes the secondary battery as described in claim 11.

Images