A battery slurry, its preparation method and uses

Abstract

This invention provides a battery slurry, its preparation method, and its applications. The preparation method includes: mixing a conductive agent and a first solvent to obtain a mud-like conductive solid; mixing the mud-like conductive solid with an active material; and then adding a conductive adhesive to obtain the battery slurry. In the battery slurry prepared by this invention, the conductive agent is uniformly coated on the surface of the active material, thereby significantly improving the conductivity of the battery electrodes. Furthermore, the battery slurry prepared by this invention exhibits high stability, effectively avoiding the problems of easy agglomeration of various conductive agents in the battery slurry and scratches caused by low-density coating, thus further improving the rate performance and fast-charging performance of the battery. Therefore, the battery slurry prepared by the method provided by this invention is suitable for fast-charge / fast-discharge high-rate battery systems.

Description

Technical Field

[0001] This invention belongs to the field of battery manufacturing technology, and in particular relates to a battery slurry, its preparation method and application. Background Technology

[0002] With the increasing development of battery technology and the increasing demands of consumers, there is a growing demand for fast-charging and fast-discharging high-rate batteries. The cells of this type of battery usually need to meet a discharge rate of 10C or higher. Currently, methods to improve the rate performance of cells usually include using small-particle-size active materials, adding multiple conductive agents, and reducing the areal density of the electrode sheets. However, the above methods will lead to the following problems: (1) Dispersion problem: Multiple conductive agents agglomerate in the slurry, affecting the stability of the slurry; (2) Coating under low areal density, the agglomerated slurry will cause a large number of particles and scratches on the surface of the electrode sheets. Therefore, the above methods will not only affect the rate performance of the cells, but also reduce the yield and processing efficiency of the electrode sheets, and increase the production cost of the cells.

[0003] CN113380973A discloses a method for preparing a silicon-based negative electrode slurry. The method includes: stirring a solvent, thickener, and conductive agent in a gelling tank to obtain a conductive adhesive; mixing a silicon active material and a carbon active material to obtain a silicon-based composite material; mixing the silicon-based composite material and the conductive adhesive in a stirrer; then adding the remaining conductive adhesive to the stirrer and mixing to obtain a mixed slurry; and adding an adhesive to the mixed slurry and continuing to stir to obtain the negative electrode slurry. This preparation method uses a simultaneous spraying method to add the conductive adhesive and the silicon-based composite material, which promotes the wetting process of the adhesive on the surface of the active material particles.

[0004] CN112366310A discloses a lithium-ion battery positive electrode slurry, its preparation method, and a lithium-ion battery. The preparation method includes the following steps: (1) mixing positive electrode active powder and conductive agent powder, and obtaining a first powder after degassing; (2) mixing the first powder with a humidifying gas to obtain a second powder; (3) mixing the second powder with a solvent, and obtaining an intermediate slurry after degassing; (4) mixing the intermediate slurry with a binder to obtain the lithium-ion battery positive electrode slurry. This preparation method shortens the wetting time by degassing the powder and using a humidifying gas, thus solving the problem of competition between gas and liquid on the powder surface.

[0005] CN109192941A discloses a lithium-ion battery positive electrode slurry and its preparation method. The method includes: adding positive electrode material, conductive agent, and binder into a stirring device and mixing them evenly to obtain a dry powder mixture; preheating the solvent to a specified temperature range; adding a specified amount of preheated solvent to the dry powder mixture and stirring to form a primary slurry; adjusting the viscosity of the primary slurry with solvent, and then grinding, filtering, and vacuum degassing to obtain the lithium-ion battery positive electrode slurry. This preparation method improves the dissolution rate of the binder during stirring by preheating the solvent.

[0006] The aforementioned literature has optimized the preparation process of battery slurry, which has improved the wetting effect of solvent on powder materials to a certain extent. However, it cannot solve the problems of easy agglomeration of various conductive agents and easy scratches caused by low-density coating. In other words, the slurry in the above literature is not suitable for fast-charge and fast-discharge high-rate battery systems. Summary of the Invention

[0007] To address the shortcomings of existing technologies, the present invention aims to provide a battery slurry, its preparation method, and its applications. The battery slurry prepared using the method provided by this invention has a conductive agent uniformly coated on the surface of the active material, thereby significantly improving the conductivity of the battery electrodes. Furthermore, the battery slurry prepared by this invention exhibits high stability, effectively avoiding the problems of easy agglomeration of various conductive agents in the battery slurry and scratches caused by low-density coating, thus further improving the rate performance and fast-charging performance of the battery. Therefore, the battery slurry prepared by the method provided by this invention is suitable for fast-charge / fast-discharge high-rate battery systems.

[0008] To achieve this objective, the present invention adopts the following technical solution:

[0009] In a first aspect, the present invention provides a method for preparing a battery slurry, the method comprising:

[0010] The conductive agent and the first solvent are mixed to obtain a mud-like conductive solid. The mud-like conductive solid is then mixed with the active material and a conductive adhesive is added to obtain the battery slurry.

[0011] In this invention, a mud-like conductive solid is mixed with the active material, i.e., a semi-dry mixing process is adopted. Combined with the subsequent addition of conductive adhesive, the fineness of the slurry is significantly reduced, the stability of the slurry is improved, and the conductive agent is uniformly dispersed and coated on the surface of the active material. This significantly improves the conductivity of the battery electrode, shortens the slurry preparation time, and improves the production efficiency of the battery cell.

[0012] The battery slurry prepared by the method provided in this invention has a uniform coating of conductive agents on the surface of the active material, thereby significantly improving the conductivity of the battery electrodes. Furthermore, the battery slurry prepared by this invention exhibits high stability, effectively avoiding the problems of easy agglomeration of various conductive agents in the battery slurry and scratches caused by low-density coating, thus further improving the rate performance and fast-charging performance of the battery. Therefore, the battery slurry prepared by the method provided in this invention is suitable for fast-charge / fast-discharge high-rate battery systems.

[0013] As a preferred technical solution of the present invention, the mass ratio of the conductive agent to the first solvent is 1:(1 to 40), for example, it can be 1:1, 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35 or 1:40, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable; preferably, it is 1:(3 to 10).

[0014] This invention controls the mass ratio of the conductive agent to the first solvent within the range of 1:(1-40). When the mass ratio is lower than 1:40, the amount of the first solvent added is too high, making it impossible to form a mud-like conductive solid. When the mass ratio is higher than 1:1, the amount of the first solvent added is too low, and the conductive agent cannot be effectively wetted, also failing to form a mud-like conductive solid. Controlling the mass ratio of the conductive agent to the first solvent within the range of 1:(3-10) is more conducive to the mixing of the conductive agent and the first solvent to form a mud-like conductive solid, thereby better leveraging its synergistic effect with the subsequent addition of the conductive adhesive.

[0015] Preferably, the conductive agent includes any one or a combination of at least two of conductive carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, acetylene black, or MXene.

[0016] Preferably, the solvent comprises N-methylpyrrolidone and / or acetone.

[0017] Preferably, the mixing process of the conductive agent and the first solvent includes a slow primary stirring followed by a rapid secondary stirring.

[0018] The reason for using slow stirring followed by rapid stirring when mixing the conductive agent and the first solvent in this invention is that slow stirring achieves wetting, while rapid stirring achieves dispersion. Furthermore, in this invention, the conductive agent and the first solvent undergo a scraping process during rapid stirring.

[0019] In addition, when only conductive carbon black is used as the conductive agent, the conductive carbon black and the first solvent can be directly mixed by first slow stirring and then fast stirring to obtain a conductive solid; when the conductive agent includes other types of conductive agents in addition to conductive carbon black, the conductive carbon black and the first solvent are first slowly stirred and then quickly stirred in sequence, and then other types of conductive agents are added and mixed under fast stirring to obtain a conductive solid.

[0020] Preferably, the stirring speed of the slow stirring once is 10 to 18 rpm, for example, it can be 10 rpm, 11 rpm, 12 rpm, 13 rpm, 14 rpm, 15 rpm, 16 rpm, 17 rpm or 18 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0021] Preferably, the dispersion speed of the slow one-time stirring is 600 to 1000 rpm, for example, it can be 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm or 1000 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0022] Preferably, the slow stirring time is 5 to 15 minutes, for example, 5 minutes, 6 minutes, 7 minutes, 8 minutes, 9 minutes, 10 minutes, 11 minutes, 12 minutes, 13 minutes, 14 minutes or 15 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0023] Preferably, the stirring speed of the rapid secondary stirring is 20 to 30 rpm, for example, it can be 20 rpm, 21 rpm, 22 rpm, 23 rpm, 24 rpm, 25 rpm, 26 rpm, 27 rpm, 28 rpm, 29 rpm or 30 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0024] Preferably, the dispersion speed of the rapid secondary stirring is 2000-2800 rpm, for example, it can be 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm or 2800 rpm, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0025] Preferably, the rapid secondary stirring time is 60 to 120 minutes, for example, it can be 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, 95 minutes, 100 minutes, 105 minutes, 110 minutes, 115 minutes or 120 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0026] As a preferred embodiment of the present invention, the mass ratio of the mud-like conductive solid to the active material is (0.4-5):(94-100), for example, it can be 0.4:94, 1:94.5, 1.5:95, 2:95.5, 2.5:96, 3:96.5, 3.5:97, 4:97.5, 4.5:98, 5:98.5, 0.6:99, 0.5:99.5 or 0.4:100, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0027] Preferably, the mixing of the mud-like conductive solid and the active material is carried out under stirring.

[0028] Preferably, the stirring speed for mixing the mud-like conductive solid with the active material is 20 to 30 rpm, for example, 20 rpm, 21 rpm, 22 rpm, 23 rpm, 24 rpm, 25 rpm, 26 rpm, 27 rpm, 28 rpm, 29 rpm or 30 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0029] Preferably, the dispersion speed of the mud-like conductive solid and the active material during stirring is 2000-2800 rpm, for example, 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm or 2800 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0030] Preferably, the stirring time between the mud-like conductive solid and the active material is 100 to 150 minutes, for example, 100 minutes, 105 minutes, 110 minutes, 115 minutes, 120 minutes, 125 minutes, 130 minutes, 135 minutes, 140 minutes, 145 minutes, or 150 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0031] Preferably, the active material includes any one or a combination of at least two of lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, lithium manganese oxide, or lithium cobalt oxide.

[0032] Preferably, the particle size D50 of the active material is ≤15μm, for example, it can be 15μm, 14μm, 13μm, 12μm, 11μm, 10μm, 9μm, 8μm or 7μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable; more preferably 3 to 6.5μm;

[0033] Preferably, the particle size D90 of the active material is ≤45μm, for example, it can be 45μm, 40μm, 35μm, 30μm, 25μm, 20μm, 15μm, 10μm or 8μm, but is not limited to the listed values, other unlisted values ​​within this range are also applicable.

[0034] The use of small-particle-size active materials in this invention is beneficial for further improving the rate performance of the battery.

[0035] As a preferred embodiment of the present invention, the preparation process of the conductive adhesive includes:

[0036] The adhesive and the second solvent are mixed to form an adhesive solution, and then a conductive agent solution is added to the adhesive solution and mixed to obtain the conductive adhesive liquid.

[0037] Preferably, the solid content of the adhesive solution is 6 to 9 wt%, for example, it can be 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, or 9 wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0038] Preferably, the viscosity of the adhesive solution is 2500 to 4000 cp, for example, it can be 2500 cp, 2700 cp, 3000 cp, 3200 cp, 3400 cp, 3600 cp, 3800 cp or 4000 cp, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0039] Preferably, the adhesive comprises any one or a combination of at least two of polyvinylidene fluoride, polytetrafluoroethylene, acrylate, or polyurethane.

[0040] Preferably, the second solvent comprises N-methylpyrrolidone and / or acetone.

[0041] Preferably, the process of mixing the adhesive and the second solvent includes three slow stirrings, four fast stirrings, and five slow stirrings in sequence.

[0042] Preferably, the stirring speed of the slow three-stage stirring is 10 to 18 rpm, for example, it can be 10 rpm, 11 rpm, 12 rpm, 13 rpm, 14 rpm, 15 rpm, 16 rpm, 17 rpm or 18 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0043] Preferably, the dispersion speed of the slow three-stage stirring is 600 to 1000 rpm, for example, it can be 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm or 1000 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0044] Preferably, the time for the three slow stirrings is 20 to 40 minutes, for example, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes or 40 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0045] Preferably, the stirring speed of the four rapid stirrings is 20 to 30 rpm, for example, it can be 20 rpm, 21 rpm, 22 rpm, 23 rpm, 24 rpm, 25 rpm, 26 rpm, 27 rpm, 28 rpm, 29 rpm or 30 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0046] Preferably, the dispersion speed of the rapid four-stage stirring is 2000-2800 rpm, for example, it can be 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm or 2800 rpm, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0047] Preferably, the duration of the four rapid stirring cycles is 200–300 min, for example, 200 min, 210 min, 220 min, 230 min, 240 min, 250 min, 260 min, 270 min, 280 min, 290 min, or 300 min, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0048] Preferably, the stirring speed for the five slow stirring cycles is 10–18 rpm, for example, 10 rpm, 11 rpm, 12 rpm, 13 rpm, 14 rpm, 15 rpm, 16 rpm, 17 rpm, or 18 rpm, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0049] Preferably, the dispersion speed of the five slow stirrings is 600 to 1000 rpm, for example, it can be 600 rpm, 650 rpm, 700 rpm, 750 rpm, 800 rpm, 850 rpm, 900 rpm, 950 rpm or 1000 rpm, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0050] Preferably, the time for the five slow stirring cycles is 20 to 40 minutes, for example, 20 minutes, 22 minutes, 24 minutes, 26 minutes, 28 minutes, 30 minutes, 32 minutes, 34 minutes, 36 minutes, 38 minutes or 40 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0051] In this invention, cooling water is passed through for 30 minutes during the five slow stirring processes.

[0052] Preferably, the slow three-times stirring, the fast four-times stirring, and the slow five-times stirring are all carried out under a vacuum of -0.1 to -0.055 MPa, for example, -0.1 MPa, -0.095 MPa, -0.09 MPa, -0.085 MPa, -0.08 MPa, -0.075 MPa, -0.07 MPa, -0.065 MPa, -0.06 MPa, or -0.055 MPa, but are not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0053] As a preferred embodiment of the present invention, the solid content of the conductive agent solution is 0.4 to 4 wt%, for example, it can be 0.4 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, 1.5 wt%, 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, or 4 wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0054] Preferably, the solute in the conductive agent solution includes any one or a combination of at least two of single-walled carbon nanotubes, double-walled carbon nanotubes, or graphene.

[0055] In this invention, multiple conductive agents can be dissolved in the same solvent, or multiple conductive agents can be dissolved in different solvents to prepare multiple conductive agent solutions, such as single-walled carbon nanotube solutions, double-walled carbon nanotube solutions, etc.

[0056] Preferably, the solvent of the conductive agent solution includes N-methylpyrrolidone and / or acetone.

[0057] Preferably, based on 100 parts by weight of the conductive adhesive liquid, the amount of adhesive solution added is 0.6 to 2 parts by weight, for example, 0.6 parts by weight, 0.8 parts by weight, 1 part by weight, 1.2 parts by weight, 1.4 parts by weight, 1.6 parts by weight, 1.8 parts by weight, or 2 parts by weight, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0058] Preferably, based on 100 parts by weight of the conductive adhesive, the amount of the conductive agent solution added is 98 to 99.4 parts by weight, for example, 98, 98.2, 98.4, 98.6, 98.8, 99, 99.2, or 99.4 parts by weight, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0059] Preferably, the adhesive solution and the conductive agent solution are mixed under stirring.

[0060] Preferably, the stirring speed for stirring the adhesive solution and the conductive agent solution is 20 to 30 rpm, for example, 20 rpm, 21 rpm, 22 rpm, 23 rpm, 24 rpm, 25 rpm, 26 rpm, 27 rpm, 28 rpm, 29 rpm or 30 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0061] Preferably, the dispersion speed of the adhesive solution and the conductive agent solution during stirring is 2000-2800 rpm, for example, 2000 rpm, 2100 rpm, 2200 rpm, 2300 rpm, 2400 rpm, 2500 rpm, 2600 rpm, 2700 rpm or 2800 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0062] The present invention specifies that the stirring speed of the binder solution and the conductive agent solution is 20-30 rpm and the dispersion speed is 2000-2800 rpm. This is because experiments have shown that the dispersion effect is better at this stirring and dispersion speed.

[0063] Preferably, the stirring time for the adhesive solution and the conductive agent solution is 100 to 150 minutes, for example, 100 minutes, 105 minutes, 110 minutes, 115 minutes, 120 minutes, 125 minutes, 130 minutes, 135 minutes, 140 minutes, 145 minutes or 150 minutes, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0064] As a preferred embodiment of the present invention, the mud-like conductive solid is mixed with the active material and then added to the conductive adhesive liquid in one step for stirring and mixing.

[0065] In this invention, after mixing the mud-like conductive solid and the active material, a battery slurry with finer particle size and higher stability can be obtained by adding the conductive adhesive in one go, without the need to add the conductive adhesive in multiple stages.

[0066] Preferably, the stirring and mixing is carried out under a vacuum of -0.1 to -0.055 MPa, for example, -0.1 MPa, -0.095 MPa, -0.09 MPa, -0.085 MPa, -0.08 MPa, -0.075 MPa, -0.07 MPa, -0.065 MPa, -0.06 MPa, or -0.055 MPa, but is not limited to the listed values; other unlisted values ​​within this range are also applicable.

[0067] Preferably, the stirring speed is 20 to 30 rpm, for example, 20 rpm, 21 rpm, 22 rpm, 23 rpm, 24 rpm, 25 rpm, 26 rpm, 27 rpm, 28 rpm, 29 rpm or 30 rpm, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0068] Preferably, the dispersion speed of the stirring and mixing is 1700 to 3500 rpm, for example, it can be 1700 rpm, 1900 rpm, 2000 rpm, 2200 rpm, 2400 rpm, 2600 rpm, 2800 rpm, 3000 rpm, 3200 rpm, 3400 rpm or 3500 rpm, but it is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0069] This invention specifies a stirring speed of 20–30 rpm and a dispersion speed of 1700–3500 rpm. Furthermore, when adding the adhesive solution all at once and mixing, cooling water is circulated to maintain a temperature of 25°C.

[0070] Preferably, the mixing time is 200 to 300 minutes, for example, 200 minutes, 210 minutes, 220 minutes, 230 minutes, 240 minutes, 250 minutes, 260 minutes, 270 minutes, 280 minutes, 290 minutes or 300 minutes, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0071] Preferably, the solid content of the battery slurry is adjusted to 69-76 wt%, for example, it can be 69 wt%, 70 wt%, 71 wt%, 72 wt%, 73 wt%, 74 wt%, 75 wt%, or 76 wt%, but it is not limited to the listed values. Other unlisted values ​​within this range are also applicable.

[0072] In this invention, after adding the conductive adhesive liquid and stirring, the viscosity of the battery slurry is tested, and then N-methylpyrrolidone solvent is added to adjust the solid content of the battery slurry to 69-75 wt%.

[0073] As a preferred embodiment of the present invention, the preparation method includes:

[0074] S1: The conductive agent and the first solvent are subjected to a mass ratio of 1:(1-40) and then subjected to slow stirring for 5-15 minutes and rapid stirring for 60-120 minutes to obtain a mud-like conductive solid; wherein, the stirring speed of the slow stirring is 10-18 rpm and the dispersion speed is 600-1000 rpm, and the stirring speed of the rapid stirring is 20-30 rpm and the dispersion speed is 2000-2800 rpm;

[0075] S2: Under a vacuum of -0.1 to -0.055 MPa, the binder and the second solvent are subjected to slow stirring three times, fast stirring four times, and slow stirring five times in sequence to form an binder solution with a solid content of 6 to 9 wt% and a viscosity of 2500 to 4000 cp. Then, based on 100 parts by weight of conductive adhesive, 99.6 to 98 parts by weight of conductive agent solution with a solid content of 0.4 to 4 wt% are added to 0.6 to 2 parts by weight of the binder solution. The mixture is stirred at a stirring speed of 20 to 30 rpm and a dispersion speed of 2000 to 2800 rpm for 100 to 150 minutes to obtain conductive adhesive.

[0076] The slow three-stage mixing process involves a mixing speed of 10–18 rpm, a dispersion speed of 600–1000 rpm, and a time of 20–40 min; the rapid four-stage mixing process involves a mixing speed of 20–30 rpm, a mixing speed of 20–30 rpm, and a time of 200–300 min; and the slow five-stage mixing process involves a mixing speed of 10–18 rpm, a dispersion speed of 600–1000 rpm, and a time of 20–40 min.

[0077] S3: The mud-like conductive solid and the active material with a particle size D50≤15μm are stirred at a mass ratio of (0.4~5):(94~100) at a stirring speed of 20~30rpm and a dispersion speed of 2000~2800rpm for 100~150min. Then, the conductive adhesive is added at a vacuum of -0.1~-0.055Mpa in one go, and the mixture is stirred at a stirring speed of 20~30rpm and a dispersion speed of 1700~3500rpm for 200~300min to obtain a battery slurry with a solid content of 69~76wt%.

[0078] The preparation method provided by this invention achieves the effect of compounding multiple conductive agents through modular preparation of conductive adhesive and conductive solids, and the combination of semi-dry mixing process and one-time adhesive addition. The resulting battery slurry has conductive agents uniformly coated on the surface of the active material, thereby significantly improving the conductivity of the battery electrodes. Furthermore, the battery slurry prepared by this invention has finer particle size and higher stability, effectively avoiding the problems of easy agglomeration of multiple conductive agents in the battery slurry and scratches caused by low-density coating, thus further improving the rate performance and fast-charging performance of the battery. Therefore, the battery slurry obtained by the preparation method provided by this invention is suitable for fast-charge-discharge high-rate battery systems.

[0079] In a second aspect, the present invention provides a battery slurry, which is prepared by the preparation method described in the first aspect.

[0080] Thirdly, the present invention provides a battery electrode sheet, the battery electrode sheet comprising the battery slurry described in the second aspect.

[0081] Fourthly, the present invention provides a battery comprising the battery electrodes described in the third aspect.

[0082] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0083] The preparation method provided by this invention achieves the effect of compounding multiple conductive agents through modular preparation of conductive adhesive and conductive solids, and the combination of semi-dry mixing process and one-time adhesive addition. The resulting battery slurry has conductive agents uniformly coated on the surface of the active material, thereby significantly improving the conductivity of the battery electrodes. Furthermore, the battery slurry prepared by this invention has finer particle size and higher stability, effectively avoiding the problems of easy agglomeration of multiple conductive agents in the battery slurry and scratches caused by low-density coating, thus further improving the rate performance and fast-charging performance of the battery. Therefore, the battery slurry obtained by the preparation method provided by this invention is suitable for fast-charge-discharge high-rate battery systems. Attached Figure Description

[0084] Figure 1 This is a SEM image of the electrode sheet prepared in Example 1 of the present invention.

[0085] Figure 2 This is a SEM image of the electrode sheet prepared in Example 1 of the present invention.

[0086] Figure 3 This is a SEM image of the electrode sheet prepared in Example 1 of the present invention.

[0087] Figure 4 This is a SEM image of the electrode sheet prepared in Example 1 of the present invention.

[0088] Figure 5 This is a SEM image of the electrode sheet prepared in Example 1 of the present invention.

[0089] Figure 6 This is a SEM image of the electrode sheet prepared in Example 1 of the present invention.

[0090] Figure 7 The viscosity changes of the slurry in Examples 1-5, Example 10, Example 12 and Comparative Example 1 over 24 hours are shown in the graph.

[0091] Figure 8 High-temperature 3C / 12C pulse discharge cycle curves of batteries assembled from the slurry of Examples 1-3 of this invention, which are made into electrodes.

[0092] Figure 9 The graph shows the fineness change of the slurry in Examples 1-5, Example 10, Example 12 and Comparative Example 1 over 24 hours. Detailed Implementation

[0093] The technical solution of the present invention will be further illustrated below through specific embodiments. Those skilled in the art should understand that the embodiments described are merely illustrative of the present invention and should not be construed as limiting the invention in any way.

[0094] Example 1

[0095] This embodiment provides a method for preparing battery slurry, the method comprising:

[0096] S1: Prepare 95 parts by weight of lithium iron phosphate with a particle size D50 of 10μm, 2 parts by weight of polyvinylidene fluoride, and 3 parts by weight of conductive agent. The conductive solid includes conductive carbon black, single-walled carbon nanotubes and MXene, and the conductive agent solution includes multi-walled carbon nanotubes. The total mass ratio of conductive carbon black, single-walled carbon nanotubes and MXene in the conductive solid to the mass ratio of multi-walled carbon nanotubes in the conductive agent solution is 3:1.

[0097] S2: Conductive carbon black and N-methylpyrrolidone were mixed at a mass ratio of 1:10, with slow stirring for 10 min and rapid stirring for 60 min. Then, single-walled carbon nanotubes and MXene were added at a mass ratio of 1:0.4:0.5, and rapid stirring was continued for another 60 min to obtain a mud-like conductive solid. The stirring speed of the slow stirring was 15 rpm and the dispersion speed was 600 rpm. The stirring speed of the rapid stirring was 25 rpm and the dispersion speed was 2500 rpm.

[0098] S3: Under a vacuum of -0.08 MPa, polyvinylidene fluoride and N-methylpyrrolidone were subjected to slow stirring three times, fast stirring four times, and slow stirring five times in sequence to form an adhesive solution with a solid content of 6 wt% and a viscosity of 2500 cp. Then, a conductive agent solution with a solid content of 2.8 wt% (the solvent of the conductive agent solution is N-methylpyrrolidone) was added, and the mixture was stirred at a stirring speed of 25 rpm and a dispersion speed of 2500 rpm for 120 min to obtain a conductive adhesive solution.

[0099] The process involves three slow stirring cycles at a stirring speed of 15 rpm and a dispersion speed of 800 rpm for 30 minutes; four fast stirring cycles at a stirring speed of 25 rpm and a dispersion speed of 2500 rpm for 240 minutes; and five slow stirring cycles at a stirring speed of 15 rpm and a dispersion speed of 600 rpm for 30 minutes, with cooling water flowing through each cycle.

[0100] S4: The mud-like conductive solid and lithium iron phosphate with a particle size D50 of 10μm were stirred at a stirring speed of 25rpm and a dispersion speed of 2500rpm for 120min, wherein the mass ratio of mud-like conductive solid to lithium iron phosphate was 0.05. Then, under a vacuum of -0.08Mpa and with cooling water flowing through to maintain 25℃, the conductive adhesive was added at one time, and stirred at a stirring speed of 25rpm and a dispersion speed of 2500rpm for 240min. The viscosity was tested, and the solid content was adjusted to 74wt%±2wt% to obtain the battery slurry.

[0101] The battery slurry prepared in this embodiment is coated onto the surface of aluminum foil to obtain a battery electrode. The areal density of the slurry coating is 180 g / cm³. 2 Furthermore, the slurry coating was free of scratches and particles. The surface morphology of the electrode was observed using a scanning electron microscope, such as... Figure 1 , Figure 2 and Figure 3 As shown in the figure, the conductive agent is uniformly dispersed and coated on the surface of the active material.

[0102] Example 2

[0103] This embodiment provides a method for preparing battery slurry, the method comprising:

[0104] S1: Prepare 98 parts by weight of lithium iron phosphate with a particle size D50 of 15μm, 0.6 parts by weight of polyvinylidene fluoride, and 1.4 parts by weight of conductive agent. The conductive solid includes conductive carbon black and MXene, the single-walled carbon nanotube solution includes single-walled carbon nanotubes, and the double-walled carbon nanotube solution includes double-walled carbon nanotubes. The total mass ratio of conductive carbon black and MXene to the total mass ratio of single-walled carbon nanotubes and double-walled nanotubes is 3:1, and the mass ratio of single-walled carbon nanotubes to double-walled carbon nanotubes is 1:1.

[0105] S2: Conductive carbon black and N-methylpyrrolidone were mixed at a mass ratio of 1:3 by slow stirring for 10 minutes and rapid stirring for 60 minutes. Then, MXene was added at a mass ratio of conductive carbon black to MXene of 2:1, and rapid stirring was continued for another 60 minutes to obtain a mud-like conductive solid. The stirring speed of the slow stirring was 15 rpm and the dispersion speed was 600 rpm. The stirring speed of the rapid stirring was 25 rpm and the dispersion speed was 2500 rpm.

[0106] S3: Under a vacuum of -0.1 MPa, polyvinylidene fluoride and N-methylpyrrolidone were subjected to slow stirring three times, fast stirring four times, and slow stirring five times in sequence to form an adhesive solution with a solid content of 9 wt% and a viscosity of 4000 cp. Then, a multi-walled carbon nanotube solution with a solid content of 2.8 wt% and a single-walled carbon nanotube solution with a solid content of 0.4 wt% (the solvent for both the multi-walled carbon nanotube solution and the single-walled carbon nanotube solution is N-methylpyrrolidone) were added. The mixture was stirred at a stirring speed of 25 rpm and a dispersion speed of 2500 rpm for 120 min to obtain a conductive adhesive solution.

[0107] The process involves three slow stirring cycles at a stirring speed of 15 rpm and a dispersion speed of 800 rpm for 30 minutes; four fast stirring cycles at a stirring speed of 25 rpm and a dispersion speed of 2500 rpm for 240 minutes; and five slow stirring cycles at a stirring speed of 15 rpm and a dispersion speed of 600 rpm for 30 minutes, with cooling water flowing through each cycle.

[0108] S4: The mud-like conductive solid and lithium iron phosphate with a particle size D50 of 15μm were stirred at a stirring speed of 25rpm and a dispersion speed of 2500rpm for 120min, wherein the mass ratio of mud-like conductive solid to lithium iron phosphate was 0.03. Then, under a vacuum of -0.1Mpa and with cooling water flowing to maintain 25℃, the conductive adhesive was added at once, and stirred at a stirring speed of 25rpm and a dispersion speed of 2500rpm for 240min. The viscosity was tested, and the solid content was adjusted to 76wt%±2wt% to obtain the battery slurry.

[0109] The battery slurry prepared in this embodiment is coated onto the surface of aluminum foil to obtain a battery electrode. The areal density of the slurry coating is 180 g / cm³. 2 Furthermore, the slurry coating is free of scratches and particles.

[0110] Example 3

[0111] This embodiment provides a method for preparing battery slurry, the method comprising:

[0112] S1: Prepare 98 parts by weight of lithium iron phosphate with a particle size D50 of 15μm, 0.7 parts by weight of polyvinylidene fluoride, and 1.3 parts by weight of conductive agent. The conductive solid includes conductive carbon black, the single-walled carbon nanotube solution includes single-walled carbon nanotubes, and the double-walled carbon nanotube solution includes double-walled carbon nanotubes. The mass ratio of conductive carbon black to the total mass of single-walled carbon nanotubes and double-walled nanotubes is 2:1, and the mass ratio of single-walled carbon nanotubes to double-walled carbon nanotubes is 1:10.

[0113] S2: Conductive carbon black and N-methylpyrrolidone are mixed at a mass ratio of 1:6, with slow stirring for 10 minutes and rapid stirring for 60 minutes to obtain a mud-like conductive solid; wherein, the stirring speed of the slow stirring is 15 rpm and the dispersion speed is 600 rpm, and the stirring speed of the rapid stirring is 25 rpm and the dispersion speed is 2500 rpm.

[0114] S3: Under a vacuum of -0.09 MPa, polyvinylidene fluoride and N-methylpyrrolidone were subjected to slow stirring three times, fast stirring four times, and slow stirring five times in sequence to form an adhesive solution with a solid content of 9 wt% and a viscosity of 3500 cp. Then, a multi-walled carbon nanotube solution with a solid content of 2.8 wt% and a single-walled carbon nanotube solution with a solid content of 0.4 wt% (the solvent for both the multi-walled carbon nanotube solution and the single-walled carbon nanotube solution is N-methylpyrrolidone) were added. The mixture was stirred at a stirring speed of 25 rpm and a dispersion speed of 2500 rpm for 120 min to obtain a conductive adhesive solution.

[0115] The process involves three slow stirring cycles at a stirring speed of 15 rpm and a dispersion speed of 800 rpm for 30 minutes; four fast stirring cycles at a stirring speed of 25 rpm and a dispersion speed of 2500 rpm for 240 minutes; and five slow stirring cycles at a stirring speed of 15 rpm and a dispersion speed of 600 rpm for 30 minutes, with cooling water flowing through each cycle.

[0116] S4: The mud-like conductive solid and lithium iron phosphate with a particle size D50 of 15μm were stirred at a stirring speed of 25rpm and a dispersion speed of 2500rpm for 120min, wherein the mass ratio of mud-like conductive solid to lithium iron phosphate was 0.07. Then, under a vacuum of -0.1Mpa and with cooling water flowing through to maintain 25℃, the conductive adhesive was added at one time, and stirred at a stirring speed of 25rpm and a dispersion speed of 2500rpm for 240min. The viscosity was tested, and the solid content was adjusted to 72wt%±2wt% to obtain the battery slurry.

[0117] The battery slurry prepared in this embodiment is coated onto the surface of aluminum foil to obtain a battery electrode. The areal density of the slurry coating is 180 g / cm³. 2 Furthermore, the slurry coating is free of scratches and particles.

[0118] Example 4

[0119] The difference between this embodiment and Embodiment 1 is that in step S3, after adding the conductive agent solution, the conductive adhesive is stirred at a stirring speed of 40 rpm to obtain the conductive adhesive solution. The remaining process parameters and operating conditions are the same as in Embodiment 1.

[0120] Example 5

[0121] The difference between this embodiment and Embodiment 1 is that in step S3, after adding the conductive agent solution, the conductive adhesive is stirred at a stirring speed of 10 rpm to obtain the conductive adhesive solution. The remaining process parameters and operating conditions are the same as in Embodiment 1.

[0122] Example 6

[0123] The difference between this embodiment and Embodiment 1 is that in step S3, after adding the conductive agent solution, the conductive adhesive solution is stirred and mixed at a dispersion speed of 1500 rpm to obtain the conductive adhesive solution. The remaining process parameters and operating conditions are the same as in Embodiment 1.

[0124] Example 7

[0125] The difference between this embodiment and Embodiment 1 is that in step S3, after adding the conductive agent solution, the conductive adhesive solution is stirred and mixed at a dispersion speed of 3500 rpm to obtain the conductive adhesive solution. The remaining process parameters and operating conditions are the same as in Embodiment 1.

[0126] Example 8

[0127] The difference between this embodiment and Embodiment 1 is that in step S4, after the conductive adhesive is added all at once, it is stirred and mixed at a stirring speed of 40 rpm. The remaining process parameters and operating conditions are the same as in Embodiment 1.

[0128] Example 9

[0129] The difference between this embodiment and Embodiment 1 is that in step S4, after the conductive adhesive is added all at once, it is stirred and mixed at a stirring speed of 10 rpm. The remaining process parameters and operating conditions are the same as in Embodiment 1.

[0130] Example 10

[0131] The difference between this embodiment and Embodiment 1 is that in step S3, after adding the conductive agent solution, the conductive adhesive solution is stirred and mixed at a dispersion speed of 1000 rpm to obtain the conductive adhesive solution. The remaining process parameters and operating conditions are the same as in Embodiment 1.

[0132] Example 11

[0133] The difference between this embodiment and Embodiment 1 is that in step S3, after adding the conductive agent solution, the conductive adhesive solution is stirred and mixed at a dispersion speed of 4000 rpm to obtain the conductive adhesive solution. The remaining process parameters and operating conditions are the same as in Embodiment 1.

[0134] Example 12

[0135] The difference between this embodiment and Embodiment 1 is that, in step S2, the total amount of conductive carbon black, single-walled carbon nanotubes and MXene and the mass ratio of N-methylpyrrolidone are 1:2.

[0136] Example 13

[0137] The difference between this embodiment and Embodiment 1 is that, in step S2, the total amount of conductive carbon black, single-walled carbon nanotubes and MXene is in a mass ratio of 1:15 to N-methylpyrrolidone.

[0138] Comparative Example 1

[0139] The difference between this comparative example and Example 1 is that step S2 is omitted, i.e., conductive carbon black, single-walled carbon nanotubes, MXene and lithium iron phosphate are mixed by dry mixing. The remaining process parameters and operating conditions are the same as in Example 1.

[0140] Comparative Example 2

[0141] The difference between this comparative example and Example 1 is that in step S2, conductive carbon black and N-methylpyrrolidone are mixed at a mass ratio of 1:60 to form a conductive agent solvent, instead of a mud-like conductive solid. That is, conductive carbon black, single-walled carbon nanotubes, MXene and lithium iron phosphate are mixed by a wet mixing method. The remaining process parameters and operating conditions are the same as in Example 1.

[0142] Comparative Example 3

[0143] The difference between this comparative example and Example 3 is that the mixing process of mud-like conductive solid and lithium iron phosphate in steps S2 and S4, as well as the one-time addition of conductive adhesive, are omitted. In step S3, lithium iron phosphate, conductive carbon black, single-walled carbon nanotubes and double-walled carbon nanotubes are simultaneously added to the binder solution to prepare the battery slurry. The remaining process parameters and operating conditions are the same as in Example 1.

[0144] The battery slurry prepared in this comparative example was coated onto the surface of aluminum foil to obtain a battery electrode. The areal density of the slurry coating was 180 g / cm³. 2 Furthermore, the slurry coating exhibits scratches and particles. The surface morphology of the electrode was observed using a scanning electron microscope, as shown... Figure 4 , Figure 5 and Figure 6 As shown.

[0145] The performance of the battery slurries prepared in Examples 1-11 and Comparative Examples 1-3 was tested under the following conditions:

[0146] (1) Battery slurry fineness test: The instrument is a scraper fineness gauge. Place the clean fineness gauge on a flat surface, and drop enough sample into the deepest part of the trench, i.e., the part with the largest scale value, so that the sample overflows slightly. Hold the scraper with your thumbs and forefingers, and place the scraper blade horizontally at the part with the largest scale value on the scraper (at the edge of the sample), so that the long side of the scraper is parallel to the wide side of the scraper and in perpendicular contact with the scraper surface. Within 1 to 2 seconds, scrape the scraper from the part with the largest scale value to the part with the smallest scale value. Immediately after scraping the sample (not exceeding 5 seconds), make an angle of 20° to 30° with the surface of the trench, observe the area in the trench where the particles are uniformly exposed under light, and record the corresponding scale value.

[0147] (2) Battery slurry viscosity test: The instrument is a viscometer. For the battery slurry viscosity range of 2000-10000 mPa.s, rotor No. 3, 10 rpm, measurement time 90s, constant temperature 25.0±0.5℃.

[0148] Figure 9 The graph shows the fineness change of the slurry in Examples 1-5, Example 10, Example 12 and Comparative Example 1 over 24 hours.

[0149] Figure 7 The viscosity changes of the slurry in Examples 1-5, Example 10, Example 12 and Comparative Example 1 over 24 hours are shown in the graph.

[0150] The performance test results of the battery slurries prepared in Examples 1-13 and Comparative Examples 1-3 are shown in Table 1.

[0151] Table 1

[0152]

[0153]

[0154] The battery electrodes prepared in Examples 1-11 and Comparative Examples 1-3 were assembled into batteries, and the electrochemical performance of the batteries was tested. The assembly process and test parameters are as follows:

[0155] (1) Battery assembly: 95.5 wt% graphite, 1.8 wt% SP, 1.5 wt% SBR, 1.2 wt% CMC, and NMP solvent. The above materials are mixed evenly by a planetary mixer and coated on a 6 μm copper foil. The negative electrode sheet is then prepared by rolling and slitting. The positive and negative electrode sheets are wound and processed into a soft-pack lithium-ion battery.

[0156] (2) Test parameters for cycle performance: test temperature 45℃, rate condition 3C / 12C pulse discharge (3s-10s discharge, 15-20s pause), settling time 10-15min, cutoff voltage 4.4-4.48V, cutoff current 0.02C.

[0157] Figure 8 High-temperature 3C / 12C pulse discharge cycle curves of batteries assembled from the slurry of Examples 1-3 of this invention, which are made into electrodes.

[0158] (3) Test parameters for rate performance: 3C charging, 12C discharging.

[0159] The performance of batteries assembled from the battery electrodes prepared in Examples 1-11 and Comparative Examples 1-3 was tested, and the test results are shown in Table 2.

[0160] Table 2

[0161]

[0162]

[0163] From Table 1, Table 2, Figure 7 and Figure 8 Analysis shows that the preparation method provided by this invention achieves the effect of compounding multiple conductive agents by modularly preparing conductive adhesive and conductive solid, and by combining semi-dry mixing process and one-time addition of adhesive. The prepared battery slurry has a smaller particle size and higher stability, which can effectively avoid the problems of easy agglomeration of multiple conductive agents in the battery slurry and easy scratches caused by low-density coating, thereby further improving the rate performance and fast charging performance of the battery.

[0164] By comparing Example 1 with Examples 4-7 and 10-11, it can be seen that there is an optimal range for the dispersion speed of the conductive adhesive liquid in step S3. Optimizing the stirring conditions can improve the dispersion effect and thus affect the product performance.

[0165] A comparison of Examples 1 and 8-9 shows that there is an optimal range for the mixing conditions after adding the conductive adhesive liquid all at once in step S4. Optimizing these mixing conditions can improve the dispersion effect and thus affect the product performance.

[0166] A comparison of Example 1 and Examples 12-13 shows that by optimizing the mass ratio of the conductive agent and the first solvent, the formation of the mud-like conductive solid can be affected, thus affecting the wetting state and consequently the product performance.

[0167] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method of preparing a lithium ion battery slurry, characterized by, The preparation method comprises: S1: the conductive agent and the first solvent are subjected to slow first stirring and fast second stirring to obtain a muddy conductive solid; wherein the stirring speed of the slow first stirring is 10-18 rpm, the dispersion speed is 600-1000 rpm, the stirring speed of the fast second stirring is 20-30 rpm, and the dispersion speed is 2000-2800 rpm; the first solvent comprises N-methyl pyrrolidone and / or acetone; S2: the binder and the second solvent are sequentially subjected to slow third stirring, fast fourth stirring and slow fifth stirring under a vacuum degree of-0.1 to-0.055 MPa to form a binder solution, the conductive agent solution is added into the binder solution, and stirring is performed to obtain a conductive glue solution; the stirring speed of the slow third stirring is 10-18 rpm, the dispersion speed is 600-1000 rpm; the stirring speed of the fast fourth stirring is 20-30 rpm, the dispersion speed is 2000-2800 rpm; the stirring speed of the slow fifth stirring is 10-18 rpm, and the dispersion speed is 600-1000 rpm; the second solvent comprises N-methyl pyrrolidone and / or acetone; S3: the muddy conductive solid is mixed with an active material, and then the conductive glue solution is added at one time under a vacuum degree of-0.1 to-0.055 MPa, and stirring is performed at a stirring speed of 20-30 rpm and a dispersion speed of 1700-3500 rpm for 200-300 min to obtain a battery slurry.

2. The production method according to claim 1, characterized by, The mass ratio of the conductive agent to the first solvent is 1:(1-40).

3. The production method according to claim 2, characterized by, The mass ratio of the conductive agent to the first solvent is 1:(3-10).

4. The method of claim 1, wherein, The conductive agent comprises any one or a combination of at least two of conductive carbon black, single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, acetylene black or MXene.

5. The preparation method according to claim 1, characterized in that, The time of the slow first stirring is 5-15 min.

6. The method of claim 1, wherein, The time of the fast second stirring is 60-120 min.

7. The preparation method according to claim 1, characterized in that, The mass ratio of the muddy conductive solid to the active material is (0.4-5):(94-100).

8. The method of claim 1, wherein, The mixing of the muddy conductive solid and the active material is performed under stirring.

9. The production method according to claim 8, characterized by, The stirring speed of the stirring of the muddy conductive solid and the active material is 20-30 rpm.

10. The preparation method according to claim 8, characterized in that, The dispersion speed of the stirring of the muddy conductive solid and the active material is 2000-2800 rpm.

11. The preparation method according to claim 8, characterized in that, The time of the stirring of the muddy conductive solid and the active material is 100-150 min.

12. The method of claim 1, wherein, The active material comprises any one or a combination of at least two of nickel cobalt lithium manganate, nickel cobalt lithium aluminate, lithium iron phosphate, lithium manganate or lithium cobaltate.

13. The method of claim 1, wherein, The particle size D50 of the active material is ≤15 μm.

14. The method of claim 13, wherein, The particle size of the active material is 3-6.5 μm.

15. The method of claim 1, wherein, The particle size D90 of the active material is ≤45 μm.

16. The method of claim 1, wherein, The solid content of the binder solution is 6-9 wt%.

17. The method of claim 1, wherein, The viscosity of the binder solution is 2500-4000 cp.

18. The method of claim 1, wherein, The binder comprises any one or a combination of at least two of polyvinylidene fluoride, polytetrafluoroethylene, acrylate or polyurethane.

19. The method of claim 1, wherein, The time of the slow third stirring is 20-40 min.

20. The method of claim 1, wherein, The time of the fast fourth stirring is 200-300 min.

21. The method of claim 1, wherein, The time of the slow fifth stirring is 20-40 min.

22. The method of claim 1, wherein, The solid content of the conductive agent solution is 0.4-4 wt%.

23. The method of claim 1, wherein, The solute of the conductive agent solution comprises any one or a combination of at least two of single-walled carbon nanotubes, double-walled carbon nanotubes or graphene.

24. The method of claim 1, wherein, The solvent of the conductive agent solution comprises N-methyl pyrrolidone and / or acetone.

25. The method of claim 1, wherein, The amount of the binder solution added is 0.6-2 parts by weight based on 100 parts by weight of the conductive adhesive solution.

26. The method of claim 1, wherein, The amount of the conductive agent solution added is 98-99.4 parts by weight based on 100 parts by weight of the conductive adhesive solution.

27. The method of claim 1, wherein, The stirring speed of the stirring of the binder solution and the conductive agent solution is 20-30 rpm.

28. The method of claim 1, wherein, The dispersion speed of the stirring of the binder solution and the conductive agent solution is 2000-2800 rpm.

29. The method of claim 1, wherein, The time of the stirring of the binder solution and the conductive agent solution is 100-150 min.

30. The method of claim 1, wherein, The solid content of the battery slurry is regulated to 69-76 wt%.

31. The method of claim 1, wherein, The preparation method comprises: S1: the conductive agent and the first solvent are sequentially subjected to slow first stirring for 5-15 min and fast second stirring for 60-120 min at a mass ratio of 1:(1-40) to obtain a mud-like conductive solid; wherein the stirring speed of the slow first stirring is 10-18 rpm and the dispersion speed is 600-1000 rpm, and the stirring speed of the fast second stirring is 20-30 rpm and the dispersion speed is 2000-2800 rpm; S2: the binder and the second solvent are sequentially subjected to slow third stirring, fast fourth stirring and slow fifth stirring under a vacuum degree of -0.1 to -0.055 MPa to form a binder solution with a solid content of 6-9 wt% and a viscosity of 2500-4000 cp, and then 99.6-98 parts by weight of the conductive agent solution with a solid content of 0.4-4 wt% is added to 0.6-2 parts by weight of the binder solution based on 100 parts by weight of the conductive adhesive solution, and the stirring is carried out at a stirring speed of 20-30 rpm and a dispersion speed of 2000-2800 rpm for 100-150 min to obtain a conductive adhesive solution; wherein the stirring speed of the slow third stirring is 10-18 rpm, the dispersion speed is 600-1000 rpm and the time is 20-40 min; the stirring speed of the fast fourth stirring is 20-30 rpm, the dispersion speed is 2000-2800 rpm and the time is 200-300 min; and the stirring speed of the slow fifth stirring is 10-18 rpm, the dispersion speed is 600-1000 rpm and the time is 20-40 min. S3: the mud-like conductive solid and the active material with a particle size D50≤15 μm are stirred at a mass ratio of (0.4-5):(94-100), a stirring speed of 20-30 rpm, a dispersing speed of 2000-2800 rpm for 100-150 min, followed by adding the conductive glue liquid at a vacuum degree of -0.1 to -0.055 Mpa, stirring at a stirring speed of 20-30 rpm, a dispersing speed of 1700-3500 rpm for 200-300 min to obtain a battery slurry with a solid content of 69-76 wt%.

32. A lithium-ion battery slurry, characterized in that, The battery slurry is prepared by the preparation method of any one of claims 1-31.

33. A lithium-ion battery pole piece, characterized by, The battery pole piece is prepared by coating and drying the battery slurry comprising the battery slurry of claim 32.

34. A lithium-ion battery, characterized by, The battery comprises the battery pole piece of claim 33.

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