Battery slurry and preparation method thereof

Abstract

The invention provides battery slurry and a preparation method thereof. The battery slurry comprises a solid content and a solvent, and the mass percentage of the solid content in the battery slurry is 30-75%. And an electrode material with more excellent performance can be provided for the electrode plate due to relatively high solid content and ideal active substance proportion. The preparation method of the battery slurry comprises the following steps: providing an active substance, a conductive agent and a dispersing agent, and performing defoaming stirring for the first time to obtain a first premix; adding an adhesive into the first premix, and performing defoaming stirring for the second time to obtain a second premix; adding a solvent into the second premix, and mixing to obtain battery slurry; wherein the dispersing agent comprises zirconium oxide beads. According to the method, the solid materials are fully and mechanically mixed and then the solvent is added, so that the step of preparing an adhesive glue solution in advance is reduced, the efficiency is improved, and meanwhile, the agglomeration or precipitation phenomenon caused by the existence of the solvent is avoided, so that the uniformity and consistency of the slurry are improved, and the quality stability of the battery slurry is effectively improved.

Description

Technical Field

[0001] This application belongs to the field of battery slurry technology, specifically relating to a battery slurry and its preparation method. Background Technology

[0002] In the battery material mixing process, the lithium battery cell slurry process includes multiple steps such as ingredient preparation and active material treatment. Conventional battery slurry mixing uses wet mixing, which can produce a uniform battery slurry. However, wet mixing requires the prior preparation of binder solution, resulting in low production efficiency. Furthermore, there is room for improvement in the adhesion performance of electrode sheets using wet mixing, and the process is complex and costly. It requires precise control of parameters such as the order of addition of various raw materials, stirring speed, stirring time, and the amount of solvent added. Deviations in any step can affect the quality of the slurry, which increases the difficulty and cost of process control.

[0003] Developing a novel slurry mixing process to obtain battery slurry with ideal solid content and uniformity is a problem that needs to be solved. Summary of the Invention

[0004] The purpose of this application is to provide a battery slurry and its preparation method, which aims to solve the problem of unstable solid content and uniformity of battery slurries prepared by existing processes.

[0005] The first embodiment of this application provides a battery slurry, comprising solids and a solvent, wherein the solids in the battery slurry have a mass percentage of 30-75%;

[0006] The solids comprise, by mass, the following components:

[0007] Active substances: 80–98 wt%;

[0008] Conductive agent: 1-10 wt%;

[0009] Adhesive: 1-10 wt%.

[0010] In some embodiments, the battery slurry includes an oil-based slurry or an aqueous slurry;

[0011] The viscosity of the oily slurry is 3000–9000 mPa·s;

[0012] The viscosity of the aqueous slurry is 2000–7000 mPa·s.

[0013] In some embodiments, the active material includes at least one of lithium iron phosphate, lithium manganese iron phosphate, ternary materials, lithium nickel manganese oxide, lithium cobalt oxide, lithium titanate, graphite, and silicon carbide.

[0014] In some embodiments, the conductive agent includes at least one of carbon black and carbon nanotubes.

[0015] In some embodiments, the adhesive includes at least one of polyvinylidene fluoride, carboxymethyl cellulose, and polyacrylic acid.

[0016] In some embodiments, the solvent includes at least one of N-methylpyrrolidone and pure water.

[0017] The second embodiment of this application provides a method for preparing a battery slurry, used to prepare the battery slurry in any of the above embodiments, comprising the following steps:

[0018] The active material, conductive agent, and dispersant are provided, and the first degassing and stirring are carried out to obtain the first premix.

[0019] Add a binder to the first premix and perform a second degassing and stirring to obtain a second premix;

[0020] Add solvent to the second premix and mix to obtain the battery slurry;

[0021] The dispersant includes zirconia beads.

[0022] In some embodiments, the mass of the active substance is x g, the mass of the conductive agent is y g, and the mass of the dispersant is z g, satisfying: x:y = (80-98):(1-10), and z:(x+y) = 1:(1-5).

[0023] In some embodiments, the mass ratio of the first premix to the adhesive is (90-99):(1-10).

[0024] In some embodiments, the mass ratio of the second premix to the solvent is (30-75):(25-70).

[0025] In some embodiments, the D of the zirconium oxide beads 50 The particle size is 1.5–2.5 mm, and the D of the zirconium oxide beads is... 90 The particle size is 2.5–3.5 mm.

[0026] In some embodiments, the step of adding a solvent to the second premix and mixing to obtain the battery slurry further includes:

[0027] The solvent is divided into a first part solvent, a second part solvent, and a third part solvent;

[0028] Add the first portion of solvent to the second premix, and perform a third degassing and stirring to obtain the third premix;

[0029] The second portion of solvent is added to the third premix, and a fourth degassing and stirring is performed to obtain a fourth premix.

[0030] The third portion of solvent is added to the fourth premix, and a fifth degassing and stirring is performed to obtain the fifth premix.

[0031] The fifth premix is ​​remixed to obtain the battery slurry, so that the viscosity of the battery slurry meets the requirements of 3000-9000 mPa·s, or, so that the viscosity of the battery slurry meets the requirements of 2000-7000 mPa·s.

[0032] Wherein, the percentage of the first portion of solvent by mass to the total solvent mass is 'a', the percentage of the second portion of solvent by mass to the total solvent mass is 'b', and the percentage of the third portion of solvent by mass to the total solvent mass is 'c', satisfying the following:

[0033] a:b:c = (40~70):(15~40):(15~20), and a+b+c = 100%.

[0034] In some embodiments, the step of remixing the fifth premix to obtain the battery slurry further includes:

[0035] The fifth premix is ​​mixed and stirred several times to obtain the battery slurry;

[0036] The mixing speed during the several mixing cycles is greater than the speed during any one of the degassing cycles from the first degassing to the fifth degassing.

[0037] In some embodiments, the time for the first defoaming and stirring is t1 s, and the rotation speed is v1 rpm;

[0038] The second degassing and stirring time is t2 s, and the rotation speed is v2 rpm;

[0039] The third degassing and stirring time is t3 s, and the rotation speed is v3 rpm;

[0040] The fourth degassing and stirring time is t4 s, and the rotation speed is v4 rpm;

[0041] The fifth degassing and stirring time is t5 s, and the rotation speed is v5 rpm;

[0042] The total time for the several mixing and stirring operations is t6 s, and the rotation speed is v6 rpm; satisfying:

[0043] 60≤t1≤120,1350≤v1≤1500;

[0044] 60≤t2≤120,1350≤v2≤1500;

[0045] 250≤t3≤300, 1350≤v3≤1500;

[0046] 250≤t4≤300,1350≤v4≤1500;

[0047] 250≤t5≤300, 1350≤v5≤1500;

[0048] 500≤t6≤600, 2000≤v6≤2200.

[0049] In some embodiments, the interval between two adjacent mixing and stirring operations is 240 to 360 seconds.

[0050] This application provides a battery slurry, comprising solids and a solvent, wherein the solids comprise 30-75% by mass; wherein the solids comprise, by mass, the following components: active material: 80-98 wt%; conductive agent: 1-10 wt%; binder: 1-10 wt%. The battery slurry provided by this application has a high solids content and an ideal proportion of active material, enabling it to provide electrode materials with superior performance. Furthermore, coating with the battery slurry provided by this application effectively reduces drying time and energy consumption, thereby improving efficiency. This application also provides a method for preparing a battery slurry, comprising the following steps: providing active material, conductive agent, and dispersant; performing a first degassing and stirring to obtain a first premix; adding a binder to the first premix; performing a second degassing and stirring to obtain a second premix; adding a solvent to the second premix; and mixing to obtain a battery slurry; wherein the dispersant includes zirconium oxide beads. The preparation method provided in this application first thoroughly mechanically mixes the solid materials, and then adds solvent to form a slurry. This not only reduces the step of preparing the adhesive solution in advance and improves efficiency, but also avoids the agglomeration or precipitation caused by directly mixing solid materials with solvent, thereby improving the uniformity and consistency of the slurry and effectively improving the quality stability of the battery slurry. Detailed Implementation

[0051] The technical solutions of this application will be clearly and completely described below with reference to the embodiments therein. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0052] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "connected" and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection, an electrical connection, or a connection that allows for mutual communication; they can refer to a direct connection, an indirect connection through an intermediate medium, or an indirect connection through a pipe or conduit; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances. In the description of this application, "multiple" means two or more, unless otherwise expressly and specifically limited. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more features.

[0053] For the preparation of battery materials, the slurry mixing process is a crucial step. It is necessary to mix all the components in the battery slurry evenly to ensure uniform contact between the powder particles and the binder, thereby avoiding problems such as stratification or hard precipitation of the electrode materials in the later stages.

[0054] The wet slurry mixing process involves dissolving the binder and conductive agent separately in a solvent, then mixing the active material with the solution containing the binder and conductive agent to form a conductive slurry. However, this process is complex and time-consuming, involving multiple steps such as binder dissolution, conductive agent dispersion, and active material mixing. Each step has strict requirements for process parameters, and any deviation in parameters can affect the slurry quality, resulting in high difficulty in process control and a long production cycle.

[0055] The applicant discovered that by first thoroughly mechanically mixing various solid materials (such as active materials, conductive agents, binders, etc.) and then uniformly distributing particles of different sizes and densities through high-speed stirring and grinding, the agglomeration or precipitation caused by the presence of solvents in wet slurry mixing can be effectively avoided, thereby improving the uniformity and consistency of the battery slurry.

[0056] The first embodiment of this application provides a battery slurry, comprising solids and a solvent, wherein the mass percentage of the solids in the battery slurry is 30-75%;

[0057] The solids, by mass, include the following components:

[0058] Active substances: 80–98 wt%;

[0059] Conductive agent: 1-10 wt%;

[0060] Adhesive: 1-10 wt%.

[0061] It is understood that the mass percentage of solids in the battery slurry can be any value from 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, and 75%, or any value within a range of any two. A higher solid content can provide electrode materials with better performance for the electrode sheet. Furthermore, after coating with the battery slurry provided in this application, drying time and energy consumption can be effectively reduced, thus improving efficiency. When the mass percentage of solids in the battery slurry meets the above-mentioned range, coating efficiency can be improved while ensuring good fluidity of the battery slurry, thereby resulting in a highly uniform electrode material.

[0062] In some embodiments, the mass percentage of solids in the battery slurry is preferably 45% to 75%. When the mass percentage of solids in the battery slurry meets the preferred range, the consistency of the battery slurry can be further improved, thereby improving the overall quality of the electrode sheet.

[0063] In some embodiments, battery slurries can be classified into oil-based slurries and water-based slurries according to the type of solvent used. Oil-based slurries refer to slurries with organic solvents as dispersion media, which can be used in fields such as positive electrode coating of lithium-ion batteries; water-based slurries refer to slurries with water as dispersion media, which can be used in fields such as negative electrode coating of lithium-ion batteries.

[0064] When the battery slurry is an oil-based slurry, the viscosity of the battery slurry is 3000-9000 mPa·s.

[0065] It is understandable that the viscosity of the oily slurry (unit: mPa·s) can be any value among 3000, 4000, 5000, 6000, 7000, 8000, and 9000, or a value within any range of two values.

[0066] When the battery slurry is an aqueous slurry, the viscosity of the battery slurry is 2000-7000 mPa·s.

[0067] It is understood that the viscosity of the aqueous slurry (unit: mPa·s) can be any value from 2000, 3000, 4000, 5000, 6000, 7000, or any value between any two. When the viscosity of the battery slurry meets the above-mentioned range, the battery slurry exhibits good uniformity and flowability.

[0068] In some embodiments, the active material includes at least one selected from lithium iron phosphate, lithium manganese iron phosphate, ternary materials, lithium nickel manganese oxide, lithium cobalt oxide, lithium titanate, graphite, and silicon carbon. Ternary materials refer to lithium-ion battery cathode materials whose chemical composition includes the three metallic elements nickel (Ni), cobalt (Co), and manganese (Mn), and their general chemical formula can be LiNi.x Co y Mn z O2 (where x+y+z=1).

[0069] In some embodiments, the conductive agent includes at least one of carbon black (Supel P Li) and carbon nanotubes (CNTs).

[0070] In some embodiments, the adhesive includes at least one of polyvinylidene fluoride (PVDF), carboxymethyl cellulose (CMC), and polyacrylic acid (PAA).

[0071] In some embodiments, the solvent includes at least one of N-methylpyrrolidone (NMP) and pure water.

[0072] The second embodiment of this application provides a method for preparing a battery slurry, used to prepare the battery slurry in any of the above embodiments, comprising the following steps:

[0073] The active material, conductive agent, and dispersant are provided, and the first degassing and stirring are carried out to obtain the first premix.

[0074] Add binder to the first premix and perform a second degassing and stirring to obtain the second premix;

[0075] Add solvent to the second premix and mix to obtain the battery slurry;

[0076] The dispersant includes zirconia beads.

[0077] In the preparation of battery slurry, the active material and conductive agent are first dry-kneaded, which allows a preliminary conductive chain layer to form between the conductive agent and the active material. Then, a binder is added, which acts as a bond between the active material and the conductive agent, and also disperses in powder form within the preliminary conductive chain layer, facilitating the subsequent dissolution of the binder in the solvent. This method of thoroughly mechanically mixing solid materials before adding solvent for slurry preparation not only reduces the need for pre-preparing the binder solution, improving efficiency, but also avoids agglomeration or precipitation caused by solvents in wet slurry mixing. This improves the uniformity and consistency of the slurry, effectively enhancing the quality stability of the battery slurry.

[0078] Furthermore, this application incorporates zirconia beads as a dispersant during the preparation of the first premix, which enhances the uniformity of the dry powder and subsequent slurry through mechanical grinding and dispersion. As an inert grinding medium, the zirconia beads, through impact, shearing, and friction during stirring or grinding, break down agglomerates of solids such as active material particles and conductive agents in the premix into smaller sizes, improving the slurry's dispersion. After the subsequent addition of solvent, the movement of the zirconia beads can also puncture large bubbles generated during stirring and break them down into smaller bubbles, while simultaneously accelerating the rise of small bubbles or their discharge under vacuum, thus improving degassing efficiency. The dispersant provided in this application, as an inert grinding medium, can be completely separated from the battery slurry after preparation by filtration through a screen, ensuring no residue in the slurry. The operation is simple and has no impact on the performance of the battery slurry.

[0079] In some embodiments, the mass of the active substance is x g, the mass of the conductive agent is y g, and the mass of the dispersant is z g, satisfying: x:y = (80~98):(1~10), and z:(x+y) = 1:(1~5).

[0080] It is understandable that the value of x:y can be any value from 80:10, 84:8, 88:6, 92:4, 96:2, 98:1, or any value within a range between any two values. The value of z:(x+y) can be any value from 1:1, 1:2, 1:3, 1:4, 1:5, or any value within a range between any two values. When the addition ratio of active material to conductive agent meets the above range, the electrode material formed by the battery slurry has ideal performance. When the addition ratio of dispersant meets the above range, it can fully grind and disperse the solids in the premix, so that the slurry has ideal dispersion, while avoiding excessive particle breakage caused by excessive dispersant, which would lead to a decrease in sieving efficiency after the preparation process.

[0081] In some embodiments, the mass ratio of the first premix to the adhesive is (90-99):(1-10).

[0082] It is understandable that the mass ratio of the first premix to the adhesive can be any value among 90:10, 92:8, 94:6, 96:4, 98:2, and 99:1, or any value within a range of any two values.

[0083] In some embodiments, the mass ratio of the second premix to the solvent is (30-75):(25-70).

[0084] It is understandable that the mass ratio of the second premix to the solvent can be any value among 25:75, 26:74, 7:73, 28:72, 29:71, and 30:70, or any value within a range of any two values.

[0085] The active material includes at least one of lithium iron phosphate, lithium manganese iron phosphate, ternary materials, lithium nickel manganese oxide, lithium cobalt oxide, lithium titanate, graphite, and silicon carbide; the conductive agent includes at least one of Supel P Li and CNT; the binder includes at least one of PVDF, CMC, and PAA; and the solvent includes at least one of NMP and pure water.

[0086] In some embodiments, the D of zirconia beads 50 The particle size is 1.5–2.5 mm, and the D of the zirconia beads is... 90 The particle size is 2.5–3.5 mm.

[0087] Understandably, D 50 Particle size refers to the particle size corresponding to a cumulative volume percentage of 50%, D 90 Particle size refers to the particle size corresponding to a cumulative volume percentage of 90%. The D-value of zirconia beads... 50 The particle size (unit: mm) can be any value from 1.5, 2.0, 2.5, or a value within a range of any two values. The D value of zirconia beads... 90 The particle size (unit: mm) can be any value from 2.5, 3.5, 3.5, or any value within a range of two values. The particle size of zirconia beads has a significant impact on slurry quality. Small-diameter zirconia beads (e.g., below 3 mm) have a large specific surface area and a high collision frequency with slurry particles, enabling fine dispersion of micron-sized particles. However, they may agglomerate due to poor flowability, leading to decreased grinding efficiency and even equipment blockage. Large-diameter zirconia beads (e.g., 3 mm and above) have high impact energy, capable of breaking up large particle agglomerates and processing low-viscosity slurries. However, uneven impact force may result in significant differences in particle breakage degree and uneven particle size distribution, increasing internal friction in the slurry and leading to higher viscosity, affecting the consistency of the battery slurry. Therefore, when the D of the zirconia beads... 50 Particle size and D 90 When the particle size meets the above-mentioned range, it can ideally promote the dispersibility and uniformity of the battery slurry.

[0088] In some embodiments, the step of adding a solvent to the second premix and mixing to obtain a battery slurry further includes:

[0089] The solvent is divided into a first part solvent, a second part solvent, and a third part solvent;

[0090] Add the first portion of solvent to the second premix, and perform a third degassing and stirring to obtain the third premix;

[0091] Add the second portion of solvent to the third premix and perform a fourth degassing and stirring process to obtain the fourth premix.

[0092] Add the third portion of solvent to the fourth premix, and perform a fifth degassing and stirring to obtain the fifth premix.

[0093] The fifth premix is ​​remixed to obtain a battery slurry, such that the viscosity of the battery slurry meets the requirements of 3000-9000 mPa·s, or, such that the viscosity of the battery slurry meets the requirements of 2000-7000 mPa·s.

[0094] Where the mass percentage of the first solvent component is 'a', the mass percentage of the second solvent component is 'b', and the mass percentage of the third solvent component is 'c', satisfying the following condition:

[0095] a:b:c = (40~70):(15~40):(15~20), and a+b+c = 100%.

[0096] By adding solvent in batches, followed by degassing and stirring, and controlling the solvent addition ratio to meet the aforementioned range, the fluidity of the system can be gradually adjusted according to the current state of the slurry during mixing. This avoids a sudden drop in viscosity or uneven dispersion caused by adding a large amount of solvent at once, effectively achieving precise control of the battery slurry viscosity. This helps the solvent and premix to fully integrate, and also allows for the timely removal of air bubbles introduced during mixing, further optimizing the uniformity and dispersibility of the slurry. It is understood that when the solvent is oil-based, adding it in batches and controlling the solvent addition ratio each time can achieve a final viscosity of 3000–9000 mPa·s for the battery slurry; when the solvent is water-based, adding it in batches and controlling the solvent addition ratio each time can achieve a final viscosity of 2000–7000 mPa·s.

[0097] In some embodiments, the step of remixing the fifth premix to obtain the battery slurry further includes:

[0098] The fifth premix was mixed and stirred several times to obtain the battery slurry.

[0099] The mixing speed for several cycles is greater than the speed of any one of the degassing processes from the first to the fifth degassing process.

[0100] It is understandable that after mixing all the materials in the battery slurry, some small agglomerates or incompletely dispersed particles may still exist. High-speed stirring can not only break up these agglomerates and make the various components more evenly dispersed in the solvent, thereby improving the dispersion uniformity of the slurry, but also cause air bubbles in the slurry to break and escape under shear force, reducing the air bubble content in the slurry and avoiding defects such as pinholes and voids in the electrode materials formed later in the battery slurry. Furthermore, dividing the high-speed stirring into several stages can avoid the temperature rise caused by high-speed stirring from affecting the battery slurry and stirring equipment.

[0101] Specifically, the first degassing and stirring time is t1 s, and the rotation speed is v1 rpm;

[0102] The second degassing and stirring time was t2 s, and the rotation speed was v2 rpm;

[0103] The third degassing and stirring time was t3 s, and the rotation speed was v3 rpm;

[0104] The fourth degassing and stirring time was t4 s, and the speed was v4 rpm;

[0105] The fifth degassing and stirring time was t5 s, and the speed was v5 rpm;

[0106] The total time for several mixing and stirring operations is t6 s, and the rotation speed is v6 rpm, satisfying:

[0107] 60≤t1≤120, 1350≤v1≤1500.

[0108] 60≤t2≤120, 1350≤v2≤1500.

[0109] 250≤t3≤300, 1350≤v3≤1500.

[0110] 250≤t4≤300, 1350≤v4≤1500.

[0111] 250≤t5≤300, 1350≤v5≤1500.

[0112] 500≤t6≤600, 2000≤v6≤2200.

[0113] It is understandable that t1 can take any value from 60, 70, 80, 90, 100, 110, 120 or any value within the range of any two values; t2 can take any value from 60, 70, 80, 90, 100, 110, 120 or any value within the range of any two values; t3 can take any value from 250, 260, 270, 280, 290, 300 or any value within the range of any two values; and t4... The values ​​can be any one of 250, 260, 270, 280, 290, 300, or any value within a range of any two values. The value of t5 can be any one of 250, 260, 270, 280, 290, 300, or any value within a range of any two values. The value of t6 can be any one of 500, 520, 540, 560, 580, 600, or any value within a range of any two values. The value of v1 can be 1350, 1... The values ​​of v2 and v3 can be any two values ​​from 380, 1410, 1440, 1470, and 1500, or any two values ​​within the range of any two values. The values ​​of v4 and v3 can be any two values ​​from 1350, 1380, 1410, 1440, 1470, and 1500, or any two values ​​within the range of any two values. The values ​​for v5 and v6 are any two values ​​within the range of 1350, 1380, 1410, 1440, 1470, and 1500. The stirring time and rate during the degassing and stirring process affect the physicochemical properties of the battery slurry. If the degassing and stirring time is insufficient, the bubbles cannot fully break down or escape, potentially leaving a large number of residual bubbles in the slurry and affecting its uniformity. If the degassing and stirring time is too long, it may cause the slurry to overheat or the solvent to evaporate, affecting the physicochemical properties of the battery slurry. The rotation speed of the mixing and degassing machine affects the viscosity and uniformity of the battery slurry. If the speed is too low, it may result in uneven viscosity or poor thixotropy; if the speed is too high, it may damage the internal network structure of the slurry, leading to a temporary decrease in viscosity. When the degassing and stirring time and rotation speed meet the above-mentioned ranges, the prepared battery slurry has good viscosity and uniformity. The degassing and stirring in this application can be completed using equipment such as the THINKY AVR-310P model mixing and degassing machine, or other models of mixing and degassing machines, which will not be elaborated here.

[0114] In some embodiments, the degassing stirring time and speed further satisfy:

[0115] t1=t2, t3=t4=t5=(2.1~5)t1=(2.1~5)t2;

[0116] v1 = v2 = v3 = v4 = v5.

[0117] In the first and second degassing and stirring processes, since the conductive agent, active material, and binder are solid materials, the required mixing time is relatively short. In the subsequent degassing and stirring processes after the addition of solvent, controlling the stirring time to meet the above-mentioned range ensures thorough mixing of the slurry. At the same time, by maintaining the same rotation speed from the first to the fifth degassing and stirring processes, the air bubbles in the slurry can be broken by a continuous and stable force, stably migrate to the liquid surface and be discharged, and secondary air bubbles caused by sudden increases or decreases in rotation speed can be prevented.

[0118] In some embodiments, the number of mixing and stirring operations can be 2, with each mixing and stirring operation lasting 250 to 300 seconds, and the interval between two adjacent mixing and stirring operations lasting 240 to 360 seconds.

[0119] Understandably, the mixing time (in seconds) for each mixing cycle can be any value from 250, 260, 270, 280, 290, or 300 seconds, or any value within a range of any two values. Similarly, the interval between two adjacent mixing cycles (in seconds) can be any value from 240, 260, 280, 300, 320, 340, or 360 seconds, or any value within a range of any two values. Mixing causes a temperature rise, and high temperatures can lead to decomposition, oxidation, or other side reactions of the active materials and binders in the slurry, altering their chemical structure and properties. For example, binders in lithium battery slurries may lose their viscosity at high temperatures, affecting electrode molding; or increased temperature may reduce slurry viscosity (e.g., due to solvent evaporation or increased molecular thermal motion), causing subsequent coating and molding process parameters to become uncontrollable, affecting product uniformity and consistency. Therefore, it is necessary to control the mixing time for each cycle and to allow for a certain interval between adjacent mixing cycles. When the mixing time and interval meet the above-mentioned range, the mixed slurry can be fully dispersed while ensuring that the mixed slurry and equipment are within a reasonable temperature range, thereby ensuring the quality of the battery slurry and the safety of the equipment.

[0120] The battery slurry and preparation method provided in this application are described below with reference to specific embodiments:

[0121] Example 1

[0122] Example 1 provides a battery slurry, prepared in the following manner:

[0123] S1. Provide 18g of active material, 1g of conductive agent and 10g of zirconia beads, wherein the particle size formula of the zirconia beads is: 1g of 5mm particle size, 2g of 3mm particle size and 7g of 2mm particle size; perform the first degassing and stirring, the mixing time is 60s and the speed is 1250rpm, to obtain the first premix.

[0124] S2. Add 1g of binder to the first premix and perform a second degassing and stirring. The mixing time is 60s and the speed is 1250rpm to obtain the second premix.

[0125] S3. Add 62wt% of solvent, NMP, to the second premix and perform a third degassing and stirring for 300s at 1500rpm to obtain the third premix.

[0126] S4. Add 20wt% solvent to the third premix and perform a fourth degassing and stirring process. The mixing time is 300s and the speed is 1500rpm to obtain the fourth premix.

[0127] S5. Add 18wt% solvent to the fourth premix and perform the fifth degassing and stirring, with a mixing time of 300s and a speed of 1500rpm, to obtain the fifth premix.

[0128] S6. Mix the fifth premix twice, each time for 300 seconds, for a total of 600 seconds, at a speed of 2000 rpm to obtain the battery slurry.

[0129] Examples 2-4

[0130] The battery slurry preparation methods provided in Examples 2-4 are the same as those in Example 1, with the only difference being the adjustment of some parameters in the preparation process.

[0131] Comparative Example 1

[0132] Comparative Example 1 provides a battery slurry prepared by a wet slurry mixing process, the steps of which are as follows:

[0133] The solvent is divided into a first part solvent, a second part solvent, and a third part solvent;

[0134] Dissolve 1g of adhesive in the first solvent and stir. The mixing time is t3 = 300s and the stirring speed is v3 = 800rpm to obtain the first adhesive solution.

[0135] The first adhesive solution is dissolved in the second solvent and stirred for a mixing time of t4 = 300s and a stirring speed of v4 = 1500rpm to obtain the second adhesive solution.

[0136] The second adhesive solution is dissolved in the third solvent and stirred for a mixing time of t5 = 300s and a stirring speed of v5 = 2000rpm to obtain the total adhesive solution.

[0137] Add 1g of conductive agent to the total adhesive solution and continue stirring to ensure that the conductive agent is fully dispersed in the solution;

[0138] 18g of active material was gradually added to a mixture containing a conductive agent and a binder solution while stirring to ensure that the active material and the solution were fully mixed to obtain a battery slurry.

[0139] Comparative Example 2

[0140] Comparative Example 2 provides a battery slurry prepared in the following manner:

[0141] S1. Provide 18g of active material, 1g of conductive agent and 10g of zirconia beads, wherein the particle size formula of the zirconia beads is: 1g of 5mm particle size, 2g of 3mm particle size and 7g of 2mm particle size; perform the first degassing and stirring, the mixing time is 60s and the speed is 1250rpm, to obtain the first premix.

[0142] S2. Add 1g of binder to the first premix and perform a second degassing and stirring. The mixing time is 60s and the speed is 1250rpm to obtain the second premix.

[0143] S3. Mix the second premix with all the solvents, the solvent being NMP, and perform a third, fourth, and fifth degassing and stirring process to obtain the battery slurry.

[0144] Comparative Example 3

[0145] The battery slurry preparation method provided in Comparative Example 3 is the same as that in Example 1, except that some parameters in the preparation process are adjusted.

[0146] The relevant parameters in Examples 1-4 and Comparative Examples 1-3 are shown in Table 1.

[0147] Table 1

[0148]

[0149] The viscosity and solid content of the battery slurries provided in Examples 1-4 and Comparative Examples 1-3 were tested using the following methods:

[0150] Viscosity test:

[0151] 1. Samples are kept at room temperature (25±2℃) to remove air bubbles;

[0152] Calibrate the rotational viscometer with a standard solution and select a suitable rotor and rotation speed;

[0153] 2. Immerse the rotor in the slurry up to the mark and fix the instrument;

[0154] Start the instrument and wait for the rotation speed to stabilize (e.g., 30 rpm) before reading the viscosity value over 1-2 minutes.

[0155] 3. Key Points:

[0156] Temperature control: Maintain a constant temperature of 25℃±0.5℃;

[0157] 4. Post-processing:

[0158] Clean the rotor and container with solvents (such as NMP or ethanol) to prevent the slurry from drying out.

[0159] Solid content test:

[0160] 1. Empty pan weighing: Place the weighing pan in the moisture meter, press the "tare" button, and record the empty pan weight;

[0161] 2. Sampling and weighing: Take 3-5g of slurry (accurate to 0.001g) and spread it evenly in a dish, and record the initial weight of the sample m1 (g);

[0162] 3. Set parameters: Select the "solid content" mode, set the drying temperature (usually 105-110℃) and heating time (or automatically dry to constant weight);

[0163] 4. Start the test: The instrument automatically heats and dries the product, and displays the moisture loss curve in real time until the weight stabilizes (e.g., weight change ≤ 0.001g within 1 minute).

[0164] The test results are shown in Table 3.

[0165] Table 2

[0166]

[0167]

[0168] As shown in Tables 1 and 2, the solution provided in this application can effectively control the viscosity of the battery slurry within the ideal range, resulting in ideal uniformity and consistency. As shown in Comparative Example 1, conventional wet mixing processes lead to uneven stirring and an increase in the viscosity of the battery slurry. As shown in Comparative Example 2, mixing the solvent at one time can cause severe agglomeration or precipitation of solid materials in the solvent, resulting in a battery slurry viscosity significantly higher than the ideal standard. As shown in Comparative Example 3, excessive stirring speed during mechanical mixing can also cause solid materials to agglomerate in the solvent, leading to an increase in the viscosity of the battery slurry.

[0169] The battery slurry and preparation method provided in the embodiments of this application have been described in detail above. Specific examples have been used in this application to illustrate the principles and implementation methods of this application. The description of the above embodiments is only for the purpose of helping to understand the technical solutions and core ideas of this application. Those skilled in the art should understand that they can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.

Claims

1. A battery slurry, characterized in that, It includes solids and solvents, wherein the solids constitute 30-75% by mass in the battery slurry; The solids comprise, by mass, the following components: Active substances: 80–98 wt%; Conductive agent: 1-10 wt%; Adhesive: 1-10 wt%.

2. The battery slurry according to claim 1, characterized in that, The battery slurry includes an oil-based slurry or an aqueous slurry; The viscosity of the oily slurry is 3000–9000 mPa·s; The viscosity of the aqueous slurry is 2000–7000 mPa·s.

3. The battery slurry according to claim 1, characterized in that, The active material includes at least one of lithium iron phosphate, lithium manganese iron phosphate, ternary materials, lithium nickel manganese oxide, lithium cobalt oxide, lithium titanate, graphite, and silicon carbide; and / or, The conductive agent includes at least one of carbon black and carbon nanotubes; and / or, The adhesive comprises at least one of polyvinylidene fluoride, carboxymethyl cellulose, and polyacrylic acid; and / or, The solvent includes at least one of N-methylpyrrolidone and pure water.

4. A method for preparing a battery slurry as described in any one of claims 1-3, characterized in that, Includes the following steps: The active material, conductive agent, and dispersant are provided, and the first degassing and stirring are carried out to obtain the first premix. Add a binder to the first premix and perform a second degassing and stirring to obtain a second premix; Add solvent to the second premix and mix to obtain the battery slurry; The dispersant includes zirconia beads.

5. The method for preparing a battery slurry according to claim 4, characterized in that, The active substance has a mass of x g, the conductive agent has a mass of y g, and the dispersant has a mass of z g, satisfying: x:y = (80~98):(1~10), and z:(x+y) = 1:(1~5); and / or, The mass ratio of the first premix to the adhesive is (90-99):(1-10); and / or, The mass ratio of the second premix to the solvent is (30-75):(25-70).

6. The method for preparing a battery slurry according to claim 4, characterized in that, The D of the zirconia beads 50 The particle size is 1.5–2.5 mm, and the D of the zirconium oxide beads is... 90 The particle size is 2.5–3.5 mm.

7. The method for preparing a battery slurry according to claim 4, characterized in that, The step of adding solvent to the second premix and mixing to obtain the battery slurry further includes: The solvent is divided into a first part solvent, a second part solvent, and a third part solvent; Add the first portion of solvent to the second premix, and perform a third degassing and stirring to obtain the third premix; The second portion of solvent is added to the third premix, and a fourth degassing and stirring is performed to obtain a fourth premix. The third portion of solvent is added to the fourth premix, and a fifth degassing and stirring is performed to obtain the fifth premix. The fifth premix is ​​remixed to obtain the battery slurry, so that the viscosity of the battery slurry meets the requirements of 3000-9000 mPa·s, or, so that the viscosity of the battery slurry meets the requirements of 2000-7000 mPa·s. Wherein, the percentage of the first portion of solvent by mass to the total solvent mass is 'a', the percentage of the second portion of solvent by mass to the total solvent mass is 'b', and the percentage of the third portion of solvent by mass to the total solvent mass is 'c', satisfying the following: a:b:c = (40~70):(15~40):(15~20), and a+b+c = 100%.

8. The method for preparing a battery slurry according to claim 7, characterized in that, The step of remixing the fifth premix to obtain the battery slurry further includes: The fifth premix is ​​mixed and stirred several times to obtain the battery slurry; The mixing speed during the several mixing cycles is greater than the speed during any one of the degassing cycles from the first degassing to the fifth degassing.

9. The method for preparing a battery slurry according to claim 8, characterized in that, The first degassing and stirring time is t1 s, and the rotation speed is v1 rpm; The second degassing and stirring time is t2 s, and the rotation speed is v2 rpm; The third degassing and stirring time is t3 s, and the rotation speed is v3 rpm; The fourth degassing and stirring time is t4 s, and the rotation speed is v4 rpm; The fifth degassing and stirring time is t5 s, and the rotation speed is v5 rpm; The total time for the several mixing and stirring operations is t6 s, and the rotation speed is v6 rpm; satisfying: 60≤t1≤120,1350≤v1≤1500; 60≤t2≤120,1350≤v2≤1500; 250≤t3≤300, 1350≤v3≤1500; 250≤t4≤300,1350≤v4≤1500; 250≤t5≤300, 1350≤v5≤1500; 500≤t6≤600, 2000≤v6≤2200.

10. A method for preparing a battery slurry according to claim 8, characterized in that, The interval between each two adjacent mixing and stirring operations is 240 to 360 seconds.

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