Preparation method of solid-state battery positive electrode slurry, positive electrode sheet and battery

Abstract

The application discloses a preparation method of a solid-state battery positive electrode slurry, a positive electrode sheet and a battery, and belongs to the field of lithium ion batteries. The positive electrode slurry provided by the application can make the positive electrode sheet achieve an ideal effect in the mass ratio range of each substance. In the application, the positive electrode active material is added in two batches. Part of the positive electrode active material is first mixed with a conductive agent and a binder glue solution uniformly, then is stirred and mixed with a solid-state electrolyte slurry, and then the remaining part of the positive electrode active material is added and stirred and mixed, so that the solid-state electrolyte is not added first, the particles are not large and heavy and are not settled in the slurry, each material can be uniformly dispersed, the solid-state electrolyte and the positive electrode active material are uniformly doped, and therefore the accuracy of subsequent slurry viscosity testing and the uniformity and consistency of the slurry and the positive electrode sheet are ensured.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of secondary batteries, and relates to a preparation method of a solid-state battery positive electrode slurry, a positive electrode sheet and a battery. BACKGROUND

[0002] With the increasing exhaustion of traditional energy and the emphasis on environmental protection, people pay more and more attention to clean new energy. The dual pressure of energy crisis and environmental protection makes the development of energy-saving and new energy vehicles an important task in the field of automobiles in the world. As a kind of secondary battery, lithium ion battery has the advantages of high energy density, long cycle life and relatively low price, and is widely used in mobile phones, notebook computers, portable power tools, electronic instruments, energy storage and electric vehicles. In recent years, the development of solid-state battery technology has gradually become a hot spot. Among them, the positive electrode material with higher capacity potential is one of the research focuses.

[0003] Single-crystal high-nickel ternary material has the advantages of high energy density and high voltage, and is one of the most potential positive electrode materials. The positive electrode of the solid-state battery generally uses an electrode material composed of an active material, a solid-state electrolyte and a conductive agent.

[0004] In the preparation of a solid-state battery, according to the process requirements, a large amount of different powder materials need to be dispersed in a solvent. At present, the conventional method is to add various powder materials into the solvent in sequence or to add several powder materials into the solvent after dry pre-mixing, and then to stir and disperse them by using a planetary stirrer. The batching process mainly includes the following procedures: mixing (powder pre-mixing), kneading, stirring and stabilizing. As an extremely important procedure in the production process of lithium ion batteries, the current procedure also has some problems, such as: due to the large difference in weight between the active material and the conductive agent and other auxiliary materials, it is difficult to mix uniformly in the simple pre-mixing stage, the conductive agent particles are small and generally exist in the form of agglomerates and are not easy to disperse, the conventional slurry mixing process takes too long, the energy consumption is large during the kneading process, and the equipment load is large, etc. For improving the dispersibility of the solid-state positive and negative electrode slurry, especially for the power type battery with higher requirements for dispersibility, it is an urgent aspect to be improved.

[0005] The patent application with the authorization number CN109411700B discloses a positive electrode sheet applied to an all-solid-state lithium ion battery and a preparation method thereof, in particular, a method for preparing the positive electrode sheet, that is, first, lithium ion conductive ceramic powder (i.e., solid-state electrolyte) and solvent are uniformly mixed, then, a binder, a conductive agent, a positive active material, and lithium salt are gradually added and uniformly mixed in steps, and then, the positive electrode sheet is coated on a positive current collector. In the preparation method, since the lithium ion conductive ceramic powder has a large particle size and is larger than the positive active material, it is easy to settle at the bottom of the slurry, which affects the stirring and dispersion effect and precision, causes more lithium ion conductive ceramic powder to be distributed in the lower layer, and the positive active material and other small-particle materials to be distributed in the upper layer, affects the uniformity of the slurry, causes a large difference in viscosity between the upper and lower layers of the slurry, and uneven doping of the solid-state electrolyte and the positive active material, thereby causing poor consistency of the slurry and the positive electrode sheet and affecting the performance of the semi-solid-state battery.

[0006] In addition, the content of each substance in the positive electrode slurry is also crucial, which affects the processes of uniform slurry and coating, and the electrochemical performance and safety performance of the solid-state battery.

[0007] Therefore, it is necessary to seek a solid-state battery positive electrode slurry and a preparation method thereof, which are used for preparing a positive electrode sheet and a solid-state battery to improve the uniformity and viscosity of the slurry. SUMMARY

[0008] In order to overcome the problems in the prior art, the present application provides a uniform slurry method of a lithium ion battery positive electrode slurry which improves the uniformity and stability of the slurry.

[0009] The present application proposes a solid-state battery positive electrode slurry formula, and optimizes the ratio of each substance in the positive electrode slurry. If the content of the positive active material is lower than the range, the electrical performance cannot be good, the viscosity of the slurry is low, the coating is affected, the performance of the electrode sheet such as the peel strength is affected, and if the content is too high, the positive active material cannot be completely doped with the solid-state electrolyte; if the content of the solid-state electrolyte is too high, the coating flatness is affected, particles are easy to appear on the surface of the electrode sheet, and if the content of the solid-state electrolyte is too low, the ideal safety performance cannot be achieved.

[0010] The present application proposes a solid-state battery positive electrode slurry uniform slurry process. The positive active material is added in two batches, part of the positive active material is first mixed uniformly with the conductive agent and the binder solution, then mixed and stirred with the solid-state electrolyte slurry, and the remaining part of the positive active material is added and stirred, which avoids the problem that the solid-state electrolyte settles in the slurry due to its large and heavy particles when it is added first, ensures that each material is uniformly dispersed, ensures that the solid-state electrolyte and the positive active material are uniformly doped, and thus ensures the accuracy of the subsequent slurry viscosity test and the uniformity and consistency of the slurry and the positive electrode sheet.

[0011] The present application is realized by the following technical solutions:

[0012] A preparation method of a solid-state battery positive electrode slurry, comprising the following steps:

[0013] (1) uniformly mixing a binder and a solvent to obtain a binder glue solution;

[0014] (2) uniformly mixing the binder glue solution and a conductive agent to obtain a conductive glue solution, and dividing the conductive glue solution into a first conductive glue solution and a second conductive glue solution according to a mass ratio of 3-4:1;

[0015] (3) dividing a positive electrode active material into a first positive electrode active material and a second positive electrode active material, uniformly mixing the first positive electrode active material and the first conductive glue solution to obtain a first slurry;

[0016] wherein the mass ratio of the first positive electrode active material is 60%-100%, and the mass ratio of the second positive electrode active material is 0%-40%;

[0017] (4) adding a solid-state electrolyte to the first slurry and uniformly mixing to obtain a second slurry;

[0018] (5) adding the second positive electrode active material to the second slurry and uniformly mixing to obtain a semi-finished product slurry;

[0019] (6) adding the second conductive glue solution to the semi-finished product slurry and uniformly mixing to obtain the solid-state battery positive electrode slurry.

[0020] Further, in step (1), a double planetary mixer is used for uniform mixing, the double planetary mixer is first stirred at a revolution speed of 10-15 rpm for 10-15 min, then stirred at a revolution speed of 10-15 rpm and a dispersion speed of 1000-1800 rpm for 20-30 min, the cylinder is scraped, and then stirred at a revolution speed of 20-30 rpm and a dispersion speed of 2000-3000 rpm for 30-60 min;

[0021] In step (2), a double planetary mixer is used for uniform mixing, the double planetary mixer is first stirred at a revolution speed of 10-15 rpm and a dispersion speed of 800-1200 rpm for 10-15 min, the cylinder is scraped, and then stirred at a revolution speed of 20-28 rpm and a dispersion speed of 2200-2600 rpm for 20-45 min.

[0022] Further, in step (1), the binder is at least one of polyvinylidene fluoride, polytetrafluoroethylene, and polyimide, and preferably, the binder is polyvinylidene fluoride;

[0023] The solvent is at least one of N-methyl pyrrolidone (NMP), N-dimethylamide (DMF), and dimethyl sulfoxide (DMSO);

[0024] The conductive agent in step (2) is at least one of conductive carbon black, graphite, acetylene black, carbon fiber, carbon nanotube, and carbonyl carbon powder; preferably, the conductive agent is conductive carbon black.

[0025] Further, in step (3), a double planetary mixer is used for uniform mixing, and the double planetary mixer is first stirred at a revolution speed of 10-15 rpm and a dispersion speed of 800-1200 rpm for 20-40 min, scraped, and then stirred at a revolution speed of 20-30 rpm and a dispersion speed of 2800-3000 rpm for 60-180 min.

[0026] In step (4), a double planetary mixer is used for uniform mixing, and the double planetary mixer is stirred at a revolution speed of 10-15 rpm and a dispersion speed of 800-1200 rpm for 20-40 min.

[0027] Further, in step (3), the positive electrode active material is high-nickel single-crystal ternary material lithium nickel cobalt manganese oxide (NCM) or lithium nickel cobalt aluminum oxide (NCA).

[0028] In step (4), the solid-state electrolyte is at least one of lithium aluminum titanium phosphate, lithium lanthanum titanium oxide, and lithium lanthanum zirconium oxide; the solid-state electrolyte is added in the form of a solid-state electrolyte slurry, and the solid content of the solid-state electrolyte slurry is 20%-25%.

[0029] Further, in step (5), a double planetary mixer is used for uniform mixing, and the double planetary mixer is first stirred at a revolution speed of 10-15 rpm and a dispersion speed of 800-1000 rpm for 20-30 min, scraped, and then stirred at a revolution speed of 20-25 rpm and a dispersion speed of 2500-3000 rpm for 60-90 min.

[0030] In step (6), a double planetary mixer is used for uniform mixing, and the double planetary mixer is first stirred at a revolution speed of 20-25 rpm and a dispersion speed of 2500-3000 rpm for 60-90 min.

[0031] Further, the solid-state battery positive electrode slurry includes the following components in mass fractions: positive electrode active material 85%-98%, binder 1%-3%, conductive agent 1%-3%, and solid-state electrolyte 0.1%-10%, and the sum of the mass fractions is 100%.

[0032] Preferably, the positive electrode active material is 90%-97%, and the solid-state electrolyte is 1%-8%.

[0033] The mass ratio of the positive active material is 90-97, and the content is too low to make the battery performance ideal, and the content is too high to make part of the positive active material not fully doped with the solid-state electrolyte; the mass ratio of the solid-state electrolyte is 1-5, and the content of the solid-state electrolyte is too low to make the safety performance not good, and the content of the solid-state electrolyte is too high to affect the coating flatness and easily cause particles, thereby affecting the battery performance, and since the slurry is added in the form of slurry, the solid content of the slurry is large in the early stage and low in the later stage, thereby affecting the uniformity of the slurry.

[0034] Further, in step (1), the binder glue solution comprises the following components with the mass fraction: 3-11% of the binder, 89-97% of the solvent, and the sum of the mass percentages is 100%.

[0035] The application further provides a positive electrode sheet comprising a positive electrode current collector and an active material layer formed on the surface of the positive electrode current collector, wherein the slurry of the active material layer is prepared by the preparation method of the solid-state battery positive electrode slurry.

[0036] The application further provides a battery comprising the positive electrode sheet.

[0037] Compared with the prior art, the application has the following advantages:

[0038] The positive electrode slurry provided by the application can make the positive electrode sheet achieve an ideal effect.

[0039] In the application, the positive active material is added in two batches, part of the positive active material is first mixed with the conductive agent and the binder glue solution, then the solid-state electrolyte slurry is stirred and mixed, and the remaining part of the positive active material is added and stirred, so that the solid-state electrolyte and the positive active material are doped uniformly, and the accuracy of the subsequent slurry viscosity test and the uniformity and consistency of the slurry and the positive electrode sheet are ensured.

[0040] In the application, the solid-state electrolyte uses a solid-state medium, which is different from the traditional liquid electrolyte and separator, and compared with the traditional liquid electrolyte and separator, the solid-state battery has better performance in safety, energy density and cycle performance. BRIEF DESCRIPTION OF DRAWINGS

[0041] Figure 1 The figure is a preparation flowchart of the lithium ion battery positive electrode slurry according to the application. DETAILED DESCRIPTION

[0042] The application will be further described in detail below in combination with the embodiments, but the application is not limited to the embodiments.

[0043] Example 1

[0044] A solid-state lithium ion battery positive electrode slurry includes the following components by mass percentage: 95% NCM, 1.5% binder PVDF, 2% oxide solid-state electrolyte LATP, 1.5% conductive agent Super-P. Among them, the oxide solid-state electrolyte is added in the form of oil slurry, and the solid content is 21.23%.

[0045] A homogenizing process of a solid-state lithium ion battery positive electrode slurry includes the following steps:

[0046] (1) Add 1.5 parts of PVDF and 33.3 parts of NMP to a double planetary mixer, stir at 10 rpm for 10 min, and scrape the cylinder; stir at 10 rpm and 1000 rpm for 30 min, and scrape the cylinder; stir at 25 rpm and 2500 rpm for 60 min, and obtain a binder glue.

[0047] (2) Add 1.5 parts of Super-P to the binder glue, stir at 10 rpm and 1000 rpm for 10 min, and scrape the cylinder; stir at 25 rpm and 2500 rpm for 30 min, and obtain a conductive glue. The conductive glue is divided into two parts according to the mass ratio of 3:1, and first conductive glue and second conductive glue are obtained respectively.

[0048] (3) Add 57 parts of positive electrode active material NCM to the first conductive glue, stir at 10 rpm and 800 rpm for 40 min, and scrape the cylinder; stir at 25 rpm and 2800 rpm for 90 min, and obtain a first slurry.

[0049] (4) Add 9.42 parts of LATP slurry (containing 2 parts of LATP) to the first slurry, stir at 12 rpm and 1200 rpm for 20 min, and obtain a second slurry.

[0050] (5) Add 38 parts of positive electrode active material NCM to the second slurry, stir at 15 rpm and 1000 rpm for 30 min, and scrape the cylinder; stir at 25 rpm and 3000 rpm for 90 min, and obtain a semi-finished slurry.

[0051] (6) Add the second conductive glue to the second slurry, stir at 25 rpm and 3000 rpm for 60 min, and finally obtain a uniformly dispersed positive electrode slurry.

[0052] Example 2

[0053] A solid-state lithium ion battery positive electrode slurry comprises the following components by mass percentage: 97% NCM, 1% binder PVDF, 1% oxide solid electrolyte LATP, and 1% conductive agent Super-P. The oxide solid electrolyte is added in the form of an oil-based slurry, and the solid content is 21.23%.

[0054] A homogenizing process for a solid-state lithium ion battery positive electrode slurry, comprising the following steps:

[0055] (1) Add 1 part of PVDF and 32.3 parts of NMP to a double-planetary mixer, stir at a revolution speed of 15 rpm for 15 min, scrape the cylinder; stir at a revolution speed of 10 rpm and a dispersion speed of 1800 rpm for 20 min, scrape the cylinder; stir at a revolution speed of 20 rpm and a dispersion speed of 3000 rpm for 50 min, to obtain a binder glue.

[0056] (2) Add 1 part of Super-P to the binder glue, stir at a revolution speed of 10 rpm and a dispersion speed of 1200 rpm for 10 min, scrape the cylinder; stir at a revolution speed of 20 rpm and a dispersion speed of 2200 rpm for 45 min, to obtain a conductive glue. Divide the conductive glue into two parts according to a mass ratio of 4:1, to obtain a first conductive glue and a second conductive glue, respectively.

[0057] (3) Add 87.3 parts of positive electrode active material NCM to the first conductive glue, stir at a revolution speed of 15 rpm and a dispersion speed of 1200 rpm for 30 min, scrape the cylinder; stir at a revolution speed of 20 rpm and a dispersion speed of 3000 rpm for 180 min, to obtain a first slurry.

[0058] (4) Add 4.71 parts of LATP slurry (containing 1 part of LATP) to the first slurry, stir at a revolution speed of 10 rpm and a dispersion speed of 800 rpm for 40 min, to obtain a second slurry.

[0059] (5) Add 9.7 parts of positive electrode active material NCM to the second slurry, stir at a revolution speed of 10 rpm and a dispersion speed of 800 rpm for 30 min, scrape the cylinder; stir at a revolution speed of 25 rpm and a dispersion speed of 3000 rpm for 60 min, to obtain a semi-finished slurry.

[0060] (6) Add the second conductive glue to the second slurry, stir at a revolution speed of 25 rpm and a dispersion speed of 3000 rpm for 60 min, to finally obtain a positive electrode slurry with uniform dispersion.

[0061] Example 3

[0062] A solid-state lithium ion battery positive electrode slurry comprises the following components by mass percentage: 90% NCM, 3% binder PVDF, 4% oxide solid electrolyte LATP, and 3% conductive agent Super-P. The oxide solid electrolyte is added in the form of an oil-based slurry, and the solid content is 21.23%.

[0063] A homogenizing process for a solid-state lithium ion battery positive electrode slurry, comprising the following steps:

[0064] (1) Add 1 part of PVDF and 8.33 parts of NMP to a double planetary mixer, stir at a revolution speed of 15 rpm for 10 min, scrape the cylinder; stir at a revolution speed of 15 rpm and a dispersion speed of 1500 rpm for 30 min, scrape the cylinder; stir at a revolution speed of 30 rpm and a dispersion speed of 2500 rpm for 60 min, to obtain a binder glue.

[0065] (2) Add 1 part of Super-P to the binder glue, stir at a revolution speed of 15 rpm and a dispersion speed of 1000 rpm for 15 min, scrape the cylinder; stir at a revolution speed of 28 rpm and a dispersion speed of 2600 rpm for 30 min, to obtain a conductive glue. The conductive glue is divided into two parts in a mass ratio of 4:1, to obtain a first conductive glue and a second conductive glue, respectively.

[0066] (3) Add 21 parts of positive electrode active material NCM to the first conductive glue, stir at a revolution speed of 10 rpm and a dispersion speed of 1000 rpm for 30 min, scrape the cylinder; stir at a revolution speed of 25 rpm and a dispersion speed of 3000 rpm for 60 min, to obtain a first slurry.

[0067] (4) Add 6.28 parts of LATP slurry (containing 1.33 parts of LATP) to the first slurry, stir at a revolution speed of 15 min and a dispersion speed of 1000 rpm for 25 min, to obtain a second slurry.

[0068] (5) Add 9 parts of positive electrode active material NCM to the second slurry, stir at a revolution speed of 10 rpm and a dispersion speed of 1000 rpm for 30 min, scrape the cylinder; stir at a revolution speed of 25 rpm and a dispersion speed of 3000 rpm for 70 min, to obtain a semi-finished slurry.

[0069] (6) Add the second conductive glue to the second slurry, stir at a revolution speed of 25 rpm and a dispersion speed of 3000 rpm for 60 min, to finally obtain a positive electrode slurry with uniform dispersion.

[0070] Example 4

[0071] A solid-state lithium ion battery positive electrode slurry comprises the following components by mass percentage: 90% NCM, 1% binder PVDF, 8% oxide solid electrolyte LATP, and 1% conductive agent Super-P. The oxide solid electrolyte is added in the form of an oil-based slurry, and the solid content is 21.23%.

[0072] A homogenizing process for a solid-state lithium ion battery positive electrode slurry, comprising the following steps:

[0073] (1) Add 1 part of PVDF and 10 parts of NMP to a double planetary mixer, stir at a revolution speed of 10 rpm for 10 min, scrape the cylinder; stir at a revolution speed of 10 rpm and a dispersion speed of 1000 rpm for 30 min, scrape the cylinder; stir at a revolution speed of 25 rpm and a dispersion speed of 2000 rpm for 30 min, to obtain a binder glue.

[0074] (2) Add 1 part of Super-P to the binder glue, stir at a revolution speed of 10 rpm and a dispersion speed of 800 rpm for 10 min, scrape the cylinder; stir at a revolution speed of 25 rpm and a dispersion speed of 2500 rpm for 20 min, to obtain a conductive glue. The conductive glue is divided into two parts according to a mass ratio of 4:1, to obtain a first conductive glue and a second conductive glue, respectively.

[0075] (3) Add 45 parts of positive electrode active material NCM to the first conductive glue, stir at a revolution speed of 10 rpm and a dispersion speed of 1000 rpm for 30 min, scrape the cylinder; stir at a revolution speed of 30 rpm and a dispersion speed of 3000 rpm for 60 min, to obtain a first slurry.

[0076] (4) Add 37.68 parts of LATP slurry (containing 8 parts of LATP) to the first slurry, stir at a revolution speed of 10 rpm and a dispersion speed of 1000 rpm for 30 min, to obtain a second slurry.

[0077] (5) Add 45 parts of positive electrode active material NCM to the second slurry, stir at a revolution speed of 10 rpm and a dispersion speed of 1000 rpm for 20 min, scrape the cylinder; stir at a revolution speed of 25 rpm and a dispersion speed of 3000 rpm for 90 min, to obtain a semi-finished slurry.

[0078] (6) Add the second conductive glue to the second slurry, stir at a revolution speed of 25 rpm and a dispersion speed of 3000 rpm for 60 min, to finally obtain a positive electrode slurry with uniform dispersion.

[0079] Example 5

[0080] A solid-state lithium ion battery positive electrode slurry comprises the following components by mass percentage: 85% NCM, 1.5% binder PVDF, 10% oxide solid electrolyte LATP, 3.5% conductive agent Super-P. Among them, the oxide solid electrolyte is added in the form of an oil-based slurry, and the solid content is 25.00%.

[0081] A homogenizing process of a solid-state lithium ion battery positive electrode slurry, comprising the following steps:

[0082] (1) Add 1.5 parts of PVDF and 10 parts of NMP to a double planetary mixer, stir at 15 rpm for 15 min, scrape the cylinder; stir at 15 rpm and 1800 rpm for 30 min, scrape the cylinder; stir at 25 rpm and 2000 rpm for 60 min, to obtain a binder glue.

[0083] (2) Add 3.5 parts of Super-P to the binder glue, stir at 15 rpm and 1200 rpm for 10 min, scrape the cylinder; stir at 28 rpm and 2500 rpm for 45 min, to obtain a conductive glue. The conductive glue is divided into two parts according to the mass ratio of 4:1, to obtain a first conductive glue and a second conductive glue.

[0084] (3) Add 43 parts of positive electrode active material NCM to the first conductive glue, stir at 10 rpm and 1200 rpm for 40 min, scrape the cylinder; stir at 20 rpm and 3000 rpm for 120 min, to obtain a first slurry.

[0085] (4) Add 40 parts of LATP slurry (containing 10 parts of LATP) to the first slurry, stir at 15 rpm and 1200 rpm for 40 min, to obtain a second slurry.

[0086] (5) Add 42 parts of positive electrode active material NCM to the second slurry, stir at 15 rpm and 1000 rpm for 30 min, scrape the cylinder; stir at 25 rpm and 3000 rpm for 90 min, to obtain a semi-finished slurry.

[0087] (6) Add the second conductive glue to the second slurry, stir at 25 rpm and 3000 rpm for 60 min, to finally obtain a uniformly dispersed positive electrode slurry.

[0088] Comparative Example 1

[0089] A solid-state lithium ion battery positive electrode slurry includes the following components by mass percentage: 95% NCM, 1.5% binder PVDF, 2% oxide solid electrolyte LATP, 1.5% conductive agent Super-P. Among them, the oxide solid electrolyte is added in the form of an oil-based slurry, and the solid content is 21.23%.

[0090] A homogenizing process for a solid-state lithium ion battery positive electrode slurry includes the following steps:

[0091] (1) Add 1.5 parts of PVDF and 33.3 parts of NMP to a double planetary mixer, stir at 10 rpm for 10 min, and scrape the cylinder; stir at 10 rpm and 1000 rpm for 30 min, and scrape the cylinder; stir at 25 rpm and 2500 rpm for 60 min, and obtain a binder solution.

[0092] (2) Add 1.5 parts of Super-P to the binder solution, stir at 10 rpm and 1000 rpm for 10 min, and scrape the cylinder; stir at 25 rpm and 2500 rpm for 30 min, and obtain a conductive solution. Divide the conductive solution into two parts according to the mass ratio of 4:1, and obtain a first conductive solution and a second conductive solution.

[0093] (3) Add 95 parts of positive electrode active material NCM to the first conductive solution, stir at 10 rpm and 1000 rpm for 30 min, and scrape the cylinder; stir at 25 rpm and 3000 rpm for 180 min, and obtain a first slurry.

[0094] (4) Add 9.42 parts of LATP slurry (containing 2 parts of LATP) to the first slurry, stir at 10 rpm and 1000 rpm for 30 min, and obtain a second slurry.

[0095] (5) Add the second conductive solution to the second slurry, stir at 25 rpm and 3000 rpm for 60 min, and finally obtain a uniformly dispersed positive electrode slurry.

[0096] Comparative Example 2

[0097] A solid-state lithium ion battery positive electrode slurry includes the following components by mass percentage: 95% NCM, 1.5% binder PVDF, 2% oxide solid electrolyte LATP, 1.5% conductive agent Super-P. Among them, the oxide solid electrolyte is added in the form of an oil-based slurry, and the solid content is 21.23%.

[0098] A homogenizing process for a solid-state lithium ion battery positive electrode slurry includes the following steps:

[0099] (1) Put 1.5 parts of PVDF and 65.22 parts of NMP into a double planetary mixer, stir at 10 rpm for 10 min, scrape the cylinder; stir at 10 rpm and 1000 rpm for 30 min, scrape the cylinder; stir at 25 rpm and 2500 rpm for 60 min, to obtain a binder glue solution.

[0100] (2) Put 1.5 parts of Super-P into the binder glue solution, stir at 10 rpm and 1000 rpm for 10 min, scrape the cylinder; stir at 25 rpm and 2500 rpm for 30 min, to obtain a conductive glue solution.

[0101] (3) Put 9.42 parts of LATP slurry (containing 2 parts of LATP) into the conductive glue solution, stir at 10 rpm and 1000 rpm for 30 min, to obtain a solid slurry.

[0102] (4) Put 95 parts of positive active material NCM into the solid slurry, stir at 10 rpm and 1000 rpm for 30 min, scrape the cylinder; stir at 25 rpm and 3000 rpm for 180 min, to obtain a positive electrode slurry.

[0103] Comparative Example 3

[0104] A solid-state lithium ion battery positive electrode slurry includes the following components by mass percentage: 95% NCM, 1.5% binder PVDF, 2% oxide solid electrolyte LATP, and 1.5% conductive agent Super-P. Among them, the oxide solid electrolyte is added in the form of an oil-based slurry, and the solid content is 21.23%.

[0105] A homogenizing process for a solid-state lithium ion battery positive electrode slurry, the steps are as follows:

[0106] (1) Put 1.5 parts of PVDF and 33.3 parts of NMP into a double planetary mixer, stir at 10 rpm for 10 min, scrape the cylinder; stir at 10 rpm and 1000 rpm for 30 min, scrape the cylinder; stir at 25 rpm and 2500 rpm for 60 min, to obtain a binder glue solution.

[0107] (2) Put 1.5 parts of Super-P into the binder glue solution, stir at 10 rpm and 1000 rpm for 10 min, scrape the cylinder; stir at 25 rpm and 2500 rpm for 30 min, to obtain a conductive glue solution.

[0108] (3) Add 57 parts of positive active material NCM to the conductive glue solution, rotate at 10 rpm, disperse at 1000 rpm, stir for 30 min, and scrape the cylinder; rotate at 25 rpm, disperse at 3000 rpm, stir for 120 min, to obtain a first slurry.

[0109] (4) Add 9.42 parts of LATP slurry (containing 2 parts of LATP) to the first slurry, rotate at 10 rpm, disperse at 1000 rpm, stir for 30 min, to obtain a second slurry.

[0110] (5) Add 38 parts of positive active material NCM to the second slurry, rotate at 10 rpm, disperse at 1000 rpm, stir for 30 min, and scrape the cylinder; rotate at 25 rpm, disperse at 3000 rpm, stir for 90 min, to obtain a positive electrode slurry.

[0111] Test Example 1

[0112] The slurries of Examples 1-5 and Comparative Examples 1-3 were tested, and the surface layer slurry of each example after homogenization completion and standing for 6 h was tested for solid content, and the test results are shown in Table 1:

[0113] Table 1 Comparison of test results of positive electrode slurries

[0114] Number Solids content Viscosity Solids content reduction rate after 6h Theoretical solids content Example 1 70.7％ 3046 0.28％ 71.06％ Example 2 73.2％ 7522 0.14％ 73.52％ Example 3 71.3％ 5132 0.42％ 71.51％ Example 4 71.1％ 4781 0.56％ 71.59％ Example 5 70.8％ 3509 0.71％ 70.92％ Comparative Example 1 70.6％ 3065 1.42％ 71.06％ Comparative Example 2 54.9％ 2154 2.19％ 57.92％ Comparative Example 3 70.5％ 2890 0.99％ 71.06％

[0115] As can be seen from Table 1, Examples 1-5 add the positive active material in two batches, and the solid content of the first batch of solid-state electrolyte slurry and the second batch of positive active material is significantly improved compared to the comparative examples, and the 6 h solid content reduction rate index is significantly improved, indicating that the mixed and dispersed slurry is more uniform and stable.

[0116] In the examples, the mass ratio of each substance in the positive electrode slurry is within the range described in the present application, the viscosity of the obtained slurry is more appropriate, the solid content is within the error range, and the subsequent electrode sheet coating effect can be ideal.

Claims

1. A method of preparing a solid-state battery cathode slurry, characterized by, The method comprises the following steps: (1) uniformly mixing the binder and the solvent to obtain a binder glue solution; (2) uniformly mixing the binder glue solution and the conductive agent to obtain a conductive glue solution, and dividing the conductive glue solution into a first conductive glue solution and a second conductive glue solution according to a mass ratio of 3-4:1; (3) dividing the positive active material into a first positive active material and a second positive active material, uniformly mixing the first positive active material and the first conductive glue solution to obtain a first slurry; wherein the mass percentage of the first positive active material is 60%-90%, and the mass percentage of the second positive active material is 10%-40%; (4) adding the solid-state electrolyte into the first slurry and uniformly mixing to obtain a second slurry; the solid-state electrolyte is added in the form of a solid-state electrolyte slurry, and the solid content of the solid-state electrolyte slurry is 20%-25%; (5) adding the second positive active material into the second slurry and uniformly mixing to obtain a semi-finished product slurry; (6) adding the second conductive glue solution into the semi-finished product slurry and uniformly mixing to obtain the solid-state battery positive electrode slurry. The solid-state battery positive electrode slurry is composed of the following components in the following mass fractions: 85%-98% of the positive active material, 1%-3% of the binder, 1%-3% of the conductive agent, and 0.1%-10% of the solid-state electrolyte, and the sum of the mass percentages is 100%.

2. The method of claim 1, wherein the solid-state battery cathode slurry is prepared by mixing the cathode active material, the conductive material, the binder, and the solvent. In step (1), the double planetary mixer is used for uniform mixing, and the double planetary mixer is first stirred at a revolution speed of 10-15 rpm for 10-15 min, then stirred at a revolution speed of 10-15 rpm and a dispersion speed of 1000-1800 rpm for 20-30 min, scraped, stirred at a revolution speed of 20-30 rpm and a dispersion speed of 2000-3000 rpm for 30-60 min; In step (2), the double planetary mixer is used for uniform mixing, and the double planetary mixer is first stirred at a revolution speed of 10-15 rpm and a dispersion speed of 800-1200 rpm for 10-15 min, scraped, then stirred at a revolution speed of 20-28 rpm and a dispersion speed of 2200-2600 rpm for 20-45 min.

3. The method of claim 1, wherein the solid-state battery cathode slurry is prepared by mixing the cathode active material, the conductive material, the binder, and the solvent. In step (1), the binder is at least one of polyvinylidene fluoride, polytetrafluoroethylene, and polyimide; the solvent is at least one of N-methyl pyrrolidone, N-dimethylamide, and dimethyl sulfoxide; In step (2), the conductive agent is at least one of conductive carbon black, graphite, acetylene black, carbon fiber, carbon nanotube, and carbonyl carbon powder.

4. The method of claim 3, wherein the solid-state battery cathode slurry is prepared by mixing the cathode active material, the conductive material, the binder, and the solvent. The binder is polyvinylidene fluoride; the conductive agent is conductive carbon black.

5. The method of claim 1, wherein the solid-state battery cathode slurry is prepared by mixing the cathode active material, the conductive material, the binder, and the solvent. In step (3), the double planetary mixer is used for uniform mixing, and the double planetary mixer is first stirred at a revolution speed of 10-15 rpm and a dispersion speed of 800-1200 rpm for 20-40 min, scraped, then stirred at a revolution speed of 20-30 rpm and a dispersion speed of 2800-3000 rpm for 60-180 min; In step (4), the double planetary mixer is used for uniform mixing, and the double planetary mixer is stirred at a revolution speed of 10-15 rpm and a dispersion speed of 800-1200 rpm for 20-40 min.

6. The method of claim 1, wherein the solid-state battery cathode slurry is prepared by mixing the cathode active material, the conductive material, the binder, and the solvent. The positive active material in step (3) is high-nickel single-crystal ternary material lithium nickel cobalt manganese oxide or lithium nickel cobalt aluminum oxide; The solid-state electrolyte in step (4) is at least one of lithium aluminum titanium phosphate, lithium lanthanum titanium oxide, and lithium lanthanum zirconium oxide.

7. The method of claim 1, wherein the solid-state battery cathode slurry is prepared by mixing the cathode active material, the conductive material, the binder, and the solvent. In step (5), a double-planetary stirrer is used for uniform mixing, and the double-planetary stirrer is first stirred at a revolution speed of 10-15 rpm and a dispersion speed of 800-1000 rpm for 20-30 min, the cylinder is scraped, and then stirred at a revolution speed of 20-25 rpm and a dispersion speed of 2500-3000 rpm for 60-90 min. In step (6), a double-planetary stirrer is used for uniform mixing, and the double-planetary stirrer is first stirred at a revolution speed of 20-25 rpm and a dispersion speed of 2500-3000 rpm for 60-90 min.

8. The method of claim 1, wherein the solid-state battery cathode slurry is prepared by the steps of: The positive active material is 90%-97%, and the solid-state electrolyte is 1%-8%.

9. The method of claim 1, wherein the solid-state battery cathode slurry is prepared by mixing the cathode active material, the conductive material, the binder, and the solvent. In step (1), the binder glue solution is composed of the following components with mass fractions: a binder 3%-11%, a solvent 89%-97%, and the sum of the mass percentages is 100%.

10. A positive electrode sheet comprising a positive electrode current collector and an active material layer formed on a surface of the positive electrode current collector, characterized by, The slurry of the active material layer is prepared by the preparation method of the solid-state battery positive electrode slurry in any one of claims 1-9.

11. A battery, characterized by The positive electrode sheet comprises the positive electrode sheet in claim 10.

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