Electrode slurry as well as preparation method and application thereof

Abstract

The invention belongs to the field of battery packaging materials, and provides an electrode slurry and a preparation method and application thereof.The preparation method comprises the steps that a specific packaging material containing PVDF fibers is adopted for packaging and bearing a battery powder raw material, the packaged raw material is not unpackaged, the packaging material is directly used as a part of a binder, and the battery powder raw material is prepared into the electrode slurry. And integrally blanking the packaged raw materials, and mixing and pulping to obtain the electrode slurry. The packaging material not only can provide a bearing function, but also can directly put the whole packaging material loaded with materials into a material mixing process and equipment without unpacking the packaging material due to the fact that the PVDF is a common binder component for preparing electrode slurry, so that the packaging material is directly dissolved in a solvent as a part of a binder, and therefore, the packaging material can be used for preparing the electrode slurry. Therefore, the dust problem caused by unpacking is effectively avoided, and the cleanliness of the production environment is improved.

Description

Technical Field

[0001] This invention belongs to the field of battery packaging materials technology, and relates to an electrode slurry, its preparation method and application. Background Technology

[0002] Lithium-ion batteries, as high-performance energy storage devices, have been widely used in consumer electronics, electric vehicles, and large-scale energy storage systems due to their advantages such as high energy density, long cycle life, and environmental friendliness. The development of high-performance batteries depends not only on the properties of the battery materials or structure themselves but also significantly on the manufacturing process. In particular, the cleanliness of the environment during manufacturing is crucial; airborne dust particles and other contaminants can reduce the consistency of electrode materials, increase the risk of internal short circuits, and shorten battery life. Therefore, maintaining a highly clean working environment is essential in the production of lithium-ion batteries.

[0003] The particle size of electrode materials in batteries is typically in the micrometer to nanometer range. For example, lithium iron phosphate, a common positive electrode material, generally has particle sizes between 0.1 μm and 1.5 μm; conductive carbon black, a commonly used conductive agent, is a nanoscale carbon material; and graphite, a common negative electrode material, has particle sizes of approximately 10 μm to 30 μm. When these micrometer or nanoscale materials are unpacked and fed into lithium battery production facilities, the physical properties of the materials themselves, especially the presence of fine particles, result in a large amount of dust being released into the air. These micro- and nano-scale particles remain suspended in the air for extended periods, drifting with the airflow to different locations within the production workshop, thus reducing the overall cleanliness of the production area. If these particles deposit on production equipment or product surfaces, they can cause a series of problems, such as uneven electrode coatings, increased contact resistance, and internal short circuits. These problems not only affect the electrochemical performance of the battery but may also shorten its lifespan and even pose safety hazards.

[0004] Currently, the common solution in industrial production to address these issues is to install low, medium, and high-efficiency filtration systems to remove airborne particles and pollutants, ensuring a clean production environment. While these filtration systems can meet purification requirements to some extent, they also significantly increase the costs of purchase, maintenance, and operation. Another solution is to use a closed-loop feeding system, where materials are transferred from packaging to the production line within a relatively enclosed space, thereby reducing dust dispersion. Although this method can alleviate dust problems to some extent, the system is complex in structure, difficult to install and debug, and requires a high degree of equipment sealing and automation. Leaks or malfunctions could lead to even greater pollution risks.

[0005] It is evident that there is relatively little focus within the field on how to directly prevent dust generation during material unpacking and feeding. In fact, fundamentally reducing particulate matter generation is the key to solving the problem. However, currently, there is a lack of effective means to directly suppress dust released during material handling, meaning that even with advanced air purification facilities, the impact of particulate matter on the production environment cannot be completely avoided. Therefore, a new technological solution needs to be developed. Summary of the Invention

[0006] In view of the problems existing in the prior art, the purpose of this invention is to provide an electrode slurry, its preparation method, and its uses. The preparation method uses a specific packaging material containing PVDF fibers to package battery powder raw materials. The packaged raw materials are not unpacked; the packaging material is directly used as part of the binder, allowing the packaged raw materials to be fed as a whole for mixing and slurry preparation to obtain the electrode slurry. The packaging material not only provides a load-bearing function, but also, since PVDF is a commonly used binder component in electrode slurry preparation, the entire package containing the material can be directly put into the mixing process and equipment without unpacking. The packaging material acts as part of the binder and dissolves directly in the solvent, effectively avoiding dust problems caused by unpacking and improving the cleanliness of the production environment.

[0007] To achieve this objective, the present invention adopts the following technical solution:

[0008] In a first aspect, the present invention provides a method for preparing an electrode paste, the method comprising:

[0009] Provide packaging material including PVDF fiber; use the packaging material to load electrode active material and / or conductive agent to obtain packaged raw material;

[0010] The packaged raw materials are not unpacked. Instead, the packaging is used as part of the binder, and the packaged raw materials are fed as a whole for mixing and slurry preparation to obtain electrode slurry.

[0011] The packaging material of this invention includes PVDF fiber. PVDF (polyvinylidene fluoride), a commonly used binder in electrode manufacturing, is soluble in common solvents such as NMP (N-methyl-2-pyrrolidone) during the mixing and slurry preparation process. This means that the packaging material of this invention is soluble in the electrode mixing and slurry preparation process. Simultaneously, PVDF fiber exhibits good chemical stability, resistance to acids, alkalis, and ultraviolet light, and a long-term operating temperature up to 150°C, with even higher short-term temperature resistance. Its thermal stability meets requirements. Furthermore, it possesses flexibility, facilitating weaving into fabrics or composite reinforcing materials. After being woven into bags, it also possesses the mechanical strength to bear solid powder materials. Therefore, the packaging material of this invention can be effectively used for loading battery powder raw materials and can also be directly added as a binder to the mixing process. This allows for the overall unloading of the packaging containing battery powder raw materials without unpacking, effectively avoiding dust problems caused by unpacking and improving the cleanliness of the production environment.

[0012] It should be noted that the battery powder raw materials include powdered solid materials used in the electrode slurry manufacturing process. For example, they can be positive electrode materials, such as ternary materials and lithium iron phosphate, negative electrode materials such as graphite materials, conductive agents such as conductive carbon black, or other raw materials or additives.

[0013] The following are preferred technical solutions of the present invention, but are not intended to limit the technical solutions provided by the present invention. The technical objectives and beneficial effects of the present invention can be better achieved and realized through the following technical solutions.

[0014] As a preferred technical solution of the present invention, the diameter of the PVDF fiber is 50nm to 30μm, including 50nm, 80nm, 100nm, 150nm, 200nm, 280nm, 350nm, 400nm, 500nm, 600nm, 700nm, 800nm, 900nm, 1μm, 3μm, 5μm, 8μm, 10μm, 15μm, 20μm, 23μm, 25μm, 28μm, or 30μm.

[0015] As a preferred technical solution of the present invention, the packaging includes bags, tubes, or irregularly shaped objects.

[0016] As a preferred technical solution of the present invention, the method for making the bag-shaped object includes: spinning PVDF raw material to obtain PVDF fibers, and weaving, blending, bonding or felting the PVDF fibers to obtain the woven bag.

[0017] As a preferred technical solution of the present invention, the spinning method includes at least one of melt spinning, coagulation bath spinning, dry spinning or electrospinning.

[0018] Melt spinning is more suitable for continuous industrial production, with higher efficiency. The resulting PVDF fibers typically have a diameter in the micrometer range and high mechanical strength. Care should be taken to control the melt viscosity and cooling rate to avoid uneven crystallization.

[0019] As a preferred embodiment of the present invention, when the spinning method is melt spinning, the PVDF raw material includes PVDF solid particles; when the spinning method is coagulation bath spinning, dry spinning or electrospinning, the PVDF raw material includes PVDF solution.

[0020] Preferably, the solvent in the PVDF solution includes DMF (N,N-dimethylformamide), NMP, or acetone.

[0021] The coagulation bath spinning process involves extruding a PVDF solution (containing polar solvents such as N,N-dimethylformamide, NMP, or acetone) through a spinneret into a coagulation bath (such as water or ethanol) to precipitate PVDF fibers. Dry spinning involves extruding the PVDF solution and then using hot air to evaporate the solvent to form PVDF fibers. This method can produce finer PVDF fibers, but it faces the challenge of solvent recovery. Electrospinning places the PVDF solution in a high-voltage electric field, using the electric field force to stretch the solution and form nanoscale ultrafine fibers, reaching 50nm to 500nm.

[0022] As a preferred technical solution of the present invention, the method for making the bag-shaped object includes: weaving the PVDF fibers to obtain the bag-shaped object, wherein the bag-shaped object is a woven bag.

[0023] As a preferred technical solution of the present invention, the weaving density of the woven bag is 5Tex to 50000Tex, such as 5Tex, 10Tex, 30Tex, 50Tex, 80Tex, 100Tex, 300Tex, 500Tex, 800Tex, 1000Tex, 300Tex, 5000Tex, 8000Tex, 10000Tex, 20000Tex, 30000Tex, 40000Tex, or 50000Tex.

[0024] As a preferred technical solution of the present invention, the thickness of the woven bag is 100μm to 600μm, such as 100μm, 130μm, 150μm, 180μm, 200μm, 230μm, 250μm, 300μm, 330μm, 380μm, 400μm, 450μm, 500μm, 530μm, 550μm or 600μm, etc.

[0025] As a preferred embodiment of the present invention, the particle size D of the loaded electrode active material and / or conductive agent is... 50When the diameter is ≤1.5μm, it can be, for example, 1.5μm, 1.3μm, 1.1μm, 1μm, 0.8μm, 0.6μm, 0.4μm, 0.3μm or 0.1μm, etc., and the diameter of the PVDF fiber is 0.5nm to 25μm; the weaving density of the woven bag is 2000Tex to 50000Tex; and the thickness of the woven bag is 100μm to 300μm.

[0026] As a preferred embodiment of the present invention, the particle size D of the loaded electrode active material and / or conductive agent is... 50 When the diameter is >1.5μm, for example, 1.8μm, 3μm, 5μm, 8μm, 10μm, 15μm, 20μm, 25μm, 28μm or 30μm, the diameter of the PVDF fiber is 0.1nm to 10μm; the weaving density of the woven bag is 5Tex to 20000Tex; and the thickness of the woven bag is 200μm to 600μm.

[0027] This invention does not limit the shape or specific dimensions of the packaging material, which should be reasonably adjusted according to the type and quantity of battery powder raw materials to be carried. Taking a woven bag as an example, the woven bag can be integrally formed by spinning, or it can have other reasonable structures, such as a sealing structure. Furthermore, the thickness of the PVDF fiber and the woven bag should ensure that the woven bag has sufficient mechanical strength to carry the battery powder raw materials without damage. For example, when carrying ternary materials, due to the higher density of the battery to be formed and the higher humidity requirements, smaller PVDF fibers are needed, but the woven bag thickness is also required; when carrying lithium iron phosphate, due to the smaller particle size of the active material, the weaving density of the woven bag should be greater.

[0028] As a preferred embodiment of the present invention, the packaging material serves as an inner lining, and a semi-transparent protective bag is also provided on the outside of the packaging material.

[0029] As a preferred technical solution of the present invention, the material of the translucent protective bag includes any one of PVC (polyvinyl chloride), PE (polyethylene), EVA (ethylene-vinyl acetate copolymer) or PA (polyamide).

[0030] As a preferred technical solution of the present invention, the thickness of the translucent protective bag is 3μm to 8μm, for example, 3μm, 3.3μm, 3.5μm, 3.8μm, 4μm, 4.2μm, 4.5μm, 4.8μm, 5μm, 5.2μm, 5.5μm, 5.8μm, 6μm, 6.2μm, 6.5μm, 6.8μm, 7μm, 7.2μm, 7.5μm, 7.8μm or 8μm, etc.

[0031] As a preferred technical solution of the present invention, the preparation method further includes, during the storage and transportation of the packaged raw materials, covering them with the semi-transparent protective bag, and removing the semi-transparent protective bag before the packaged raw materials are discharged as a whole.

[0032] To prevent the PVDF fiber packaging from being accidentally torn or dissolved by solvents before feeding, the packaging can be used as an inner liner (such as an inner bag), and then a protective bag can be placed over the inner liner. The protective bag can not only prevent damage to the packaging, but also further prevent dust problems. During the feeding, mixing and pulping process, the protective bag can be removed and the packaging containing the battery powder raw materials can be fed out as a whole.

[0033] As a preferred embodiment of the present invention, a supplementary binder is added during the mixing and pulping process.

[0034] As a preferred embodiment of the present invention, the supplementary adhesive includes at least one of PVDF, PAA (polyacrylic acid), PMMA (polymethyl methacrylate), SBR (styrene-butadiene rubber), or CMC (sodium carboxymethyl cellulose).

[0035] As a preferred embodiment of the present invention, based on the total mass of the PVDF fiber and the supplementary adhesive as 100%, the proportion of the supplementary adhesive is 0% to 99%, for example, 0%, 1%, 3%, 5%, 8%, 10%, 20%, 30%, 40%, 50%, 60%, 70%, 80%, 90%, 95%, or 99%, preferably 10% to 65%.

[0036] It is understandable that when the packaging material is used as part of the binder and fed as a whole, the mass of the packaging material should be known in advance, and the amount of supplementary binder to be added during the mixing process should be calculated. When the amount of packaging material as binder is sufficient, no additional binder needs to be added, i.e., the proportion of supplementary binder is 0%, and this should be reasonably selected based on the actual situation. Furthermore, when the proportion of supplementary binder is between 20% and 55%, the mixing and slurry preparation effect and quality can be better balanced, which is beneficial to ensuring the bonding performance of the slurry, as well as the internal resistance and rate performance of the electrode sheet and battery, while also being cost-effective.

[0037] As a preferred technical solution of the present invention, the mixing and pulping is carried out at 25℃~80℃, for example 25℃, 30℃, 35℃, 40℃, 50℃, 60℃, 70℃ or 80℃, preferably 35℃~70℃.

[0038] As a preferred technical solution of the present invention, the method for mixing and pulping includes dry mixing, and the dry mixing process includes:

[0039] 1) Discharge the packaged raw materials as a whole and perform solid-phase mixing to obtain a mixture;

[0040] 2) Add supplementary binder to the mixture gradually, kneading and stirring after each addition;

[0041] 3) After the final kneading and stirring, solid-phase dispersion is carried out to obtain the dispersion.

[0042] 4) Add solvent to the dispersion to adjust the viscosity and obtain electrode slurry;

[0043] Preferably, the supplementary adhesive is prepared in advance with the solvent to form an adhesive solution before use;

[0044] Preferably, the solvent includes NMP.

[0045] PVDF fibers in packaging materials possess superior mechanical stability. When used as a binder component in bulk, it's crucial to maximize their solubility and adhesive properties. This can be achieved by increasing the mixing temperature to accelerate dissolution, and by gradually kneading the mixture using a dry mixing process to enhance the slurry's shear strength and solubility.

[0046] In a second aspect, the present invention provides an electrode slurry, wherein the electrolytic slurry is obtained according to the preparation method described in the first aspect.

[0047] Thirdly, the present invention provides an electrode sheet, which is obtained by coating with the electrode paste described in the second aspect.

[0048] Fourthly, the present invention provides a battery comprising the electrode plates described in the third aspect.

[0049] Compared with existing technical solutions, the present invention has at least the following beneficial effects:

[0050] This invention innovatively uses packaging materials containing PVDF fibers as packaging for battery powder raw materials. This not only provides the function of carrying and packaging the raw materials, but also, since PVDF is a commonly used binder component in the preparation of electrode slurry, the entire package containing the material can be directly put into the mixing process and equipment without opening the packaging. This allows the packaging material to dissolve directly in the solvent as part of the binder, thereby effectively avoiding the dust problem caused by opening the packaging and improving the cleanliness of the production environment. Detailed Implementation

[0051] The technical solution of the present invention will be further illustrated below through specific embodiments.

[0052] Those skilled in the art should understand that the following embodiments are merely illustrative of the invention and should not be construed as specific limitations thereof.

[0053] Example 1

[0054] This embodiment provides a method for preparing an electrode paste, the method comprising:

[0055] (1) A woven bag A is provided, wherein the material of the woven bag A is PVDF fiber; the diameter of the PVDF fiber is 2μm; the thickness of the woven bag A is 330μm and the weaving density is 1600Tex; the woven bag A is used to load ternary cathode material, and its height and width are 75cm and 50cm respectively. After loading the ternary cathode material, the bag is sealed to obtain packaged raw material A. A semi-transparent protective bag is placed on the outside of the packaged raw material A. The material of the semi-transparent protective bag is PE and the thickness of the semi-transparent protective bag is 5μm.

[0056] The method for preparing the woven bag A is as follows: PVDF raw material is spun into fibers, and the spinning method is melt spinning. The melt spinning process includes using PVDF particles as PVDF raw material, heating them to a molten state, extruding them through a spinneret, cooling and solidifying them to form PVDF fibers, and finally weaving the PVDF fibers into the woven bag A.

[0057] (2) Provide a woven bag B, wherein the material of the woven bag B is PVDF fiber; the diameter of the PVDF fiber is 0.5μm; the thickness of the woven bag is 100μm and the weaving density is 8000Tex; the woven bag is used to load the conductive agent superconducting carbon black for mixing the positive electrode slurry, and its height and width are 60cm and 40cm respectively. After loading the superconducting carbon black, the bag is sealed to obtain the packaged raw material B. A semi-transparent protective bag is placed on the outside of the package. The material of the semi-transparent protective bag is PVC and the thickness of the semi-transparent protective bag is 3μm.

[0058] The method for preparing the woven bag B is as follows: PVDF raw material is spun into fibers using electrospinning. The electrospinning process includes preparing a PVDF solution using PVDF particles and the solvent NMP as the PVDF raw material; placing the PVDF solution in a high-voltage electric field; and stretching the solution using the electric field force to form nanoscale ultrafine fibers. Finally, the PVDF fibers are woven into the woven bag B.

[0059] (3) Neither the packaged raw material A nor the packaged raw material B shall be unpacked. The woven bag shall be used as part of the adhesive to allow the packaged raw materials to be discharged as a whole. The materials shall be mixed and pulped at 35°C. The mixing and pulping method includes dry mixing. The dry mixing process includes:

[0060] 1) Discharge the packaged raw materials as a whole and perform solid-phase mixing to obtain a mixture;

[0061] 2) The supplementary adhesive PVDF is pre-prepared with solvent NMP to form an adhesive solution, and the adhesive solution is added to the mixture one by one, and kneading and stirring are performed after each addition; the supplementary adhesive accounts for 37% of the total mass of PVDF fibers in woven bag A and woven bag B plus the total mass of the supplementary adhesive, which is 100%.

[0062] 3) After the final kneading and stirring, solid-phase dispersion is carried out to obtain the dispersion.

[0063] 4) Add solvent to the dispersion to adjust the viscosity and obtain positive electrode slurry A.

[0064] Example 2

[0065] This embodiment provides a method for preparing an electrode paste, the method comprising:

[0066] (1) A woven bag C is provided, wherein the material of the woven bag C is PVDF fiber; the diameter of the PVDF fiber is 12μm; the thickness of the woven bag is 230μm and the weaving density is 3000Tex; the woven bag is used to load lithium iron phosphate cathode material, and its height and width are 75cm and 45cm respectively. After loading the lithium iron phosphate cathode material, the bag is sealed to obtain packaged raw material C. A semi-transparent protective bag is placed on the outside of the packaged raw material C. The material of the semi-transparent protective bag is EVA and the thickness of the semi-transparent protective bag is 6μm.

[0067] The preparation method of woven bag C is as follows: PVDF raw material is spun into fibers using a dry spinning method. The dry spinning process includes preparing a PVDF solution using PVDF particles and the solvent NMP as the PVDF raw material; extruding the PVDF solution and then evaporating the solvent with hot air to form PVDF fibers; finally, weaving the PVDF fibers into the woven bag C.

[0068] (2) Using the woven bag B from Example 1 and loading it with superconducting carbon black, we obtain packaged raw material B, and then cover it with a semi-transparent protective bag.

[0069] (3) Neither the packaged raw material C nor the packaged raw material B is unpacked. The woven bag is used as part of the adhesive to allow the packaged raw materials to be discharged as a whole. The materials are then mixed and pulped at 55°C. The mixing and pulping method includes dry mixing. The dry mixing process includes:

[0070] 1) Discharge the packaged raw materials as a whole and perform solid-phase mixing to obtain a mixture;

[0071] 2) The supplementary adhesive PVDF is pre-prepared with solvent NMP to form an adhesive solution, and the adhesive solution is added to the mixture one by one, and kneading and stirring are performed after each addition; the supplementary adhesive accounts for 12% of the total mass of PVDF fibers in woven bag C and woven bag B plus the total mass of the supplementary adhesive, which is 100%.

[0072] 3) After the final kneading and stirring, solid-phase dispersion is carried out to obtain the dispersion.

[0073] 4) Add solvent to the dispersion to adjust the viscosity and obtain positive electrode slurry B;

[0074] Example 3

[0075] This embodiment provides a method for preparing an electrode paste, the method comprising:

[0076] (1) A woven bag D is provided, wherein the material of the woven bag D is PVDF fiber; the diameter of the PVDF fiber is 5μm; the thickness of the woven bag is 520μm and the weaving density is 12000Tex; the woven bag is used to load graphite anode material, and its height and width are 90cm and 55cm respectively. After loading the graphite anode material, the bag is sealed to obtain packaged raw material D. A semi-transparent protective bag is placed on the outside of the packaged raw material D, wherein the material of the semi-transparent protective bag is PA and the thickness of the semi-transparent protective bag is 8μm.

[0077] The method for preparing the woven bag D is as follows: PVDF raw material is spun into fibers using a coagulation bath spinning method. The coagulation bath spinning process includes preparing a PVDF solution using PVDF particles and solvent NMP as the PVDF raw material, and extruding the PVDF solution through a spinneret into a coagulation bath (water to alcohol volume ratio of 1:1) to precipitate PVDF fibers. Finally, the PVDF fibers are woven into the woven bag D.

[0078] (2) Using the woven bag B from Example 1 and loading it with superconducting carbon black, we obtain packaged raw material B, and then cover it with a semi-transparent protective bag.

[0079] (3) Neither the packaged raw material D nor the packaged raw material B shall be unpacked. The woven bag shall be used as part of the adhesive to allow the packaged raw materials to be discharged as a whole. The materials shall be mixed and pulped at 70°C. The mixing and pulping method includes dry mixing. The dry mixing process includes:

[0080] 1) Discharge the packaged raw materials as a whole and perform solid-phase mixing to obtain a mixture;

[0081] 2) The supplementary adhesive PVDF is pre-prepared with solvent NMP to form an adhesive solution, and the adhesive solution is added to the mixture one by one, and kneading and stirring are performed after each addition; the supplementary adhesive accounts for 50% of the total mass of PVDF fibers in woven bag D and woven bag B plus the total mass of the supplementary adhesive, which is 100%.

[0082] 3) After the final kneading and stirring, solid-phase dispersion is carried out to obtain the dispersion.

[0083] 4) Add solvent to the dispersion to adjust the viscosity and obtain negative electrode slurry C.

[0084] Comparative Example 1

[0085] This comparative example provides a method for preparing an electrode slurry. The method uses the packaged raw material A and packaged raw material B from Example 1, but after unpacking both, the woven bags are discarded, and only the raw materials inside the woven bags are discharged for mixing and slurry preparation. An additional binder PVDF is added to prepare the positive electrode slurry D.

[0086] Comparative Example 2

[0087] This comparative example provides a method for preparing an electrode slurry. The method uses the packaged raw material C and packaged raw material B from Example 2. However, after unpacking both, the woven bags are discarded, and only the raw materials inside the woven bags are discharged for mixing and slurry preparation. An additional binder PVDF is added to prepare the positive electrode slurry E.

[0088] Characterization and testing:

[0089] I. The following tests were performed on woven bags A, B, C, and D described in Examples 1-3:

[0090] (1) Tensile strength test

[0091] Sample preparation: Samples were taken according to GB / T 36363-2018 standard, cut along the width of the diaphragm, and conditioned for 4 hours in an environment of (23±2)℃ and (50±10)% humidity.

[0092] Test procedure: Use an electronic tensile testing machine, set the clamp spacing and tensile rate (set to 50 mm / min), record the maximum tensile force and calculate the tensile strength value.

[0093] Data calculation: Take the arithmetic mean of the test values ​​of 5 samples.

[0094] (2) Puncture strength test

[0095] Sample preparation: Cut 5 samples (width ≥ 100 mm) and adjust them to the same environmental conditions as Test I.

[0096] Test equipment: A universal puncture tester was used. The puncture needle had a diameter of 1.0 mm and a tip radius of 0.5 mm. The sample was punctured at a speed of (50±5) mm / min, and the maximum peak force was recorded.

[0097] Data calculation: Take the arithmetic mean of the test values ​​of 5 samples.

[0098] The results are shown in Table 1.

[0099] Table 1

[0100] Group Puncture strength tensile strength Woven bag A 512g 103MPa Woven bag B 273g 57MPa Woven bag C 313g 79MPa Woven bag D 457g 93MPa

[0101] As can be seen from Table 1, woven bags made of PVDF fibers have sufficient strength. The diameter of the fibers will affect the mechanical strength properties to a certain extent, and the thickness of the woven bag will also have an impact. Generally, the thicker the woven bag, the greater the strength and the more material it can carry. Therefore, the diameter of the fibers and the thickness of the woven bag should be reasonably adjusted according to the packaging volume in order to meet the needs of carrying battery powder raw materials at the best cost.

[0102] II. The obtained positive electrode slurries A, B, D, E, and C are coated onto their respective current collectors (aluminum foil for the positive electrode and copper foil for the negative electrode) and then dried to obtain positive electrode sheets A, B, D, E, and C. A, B, D, and E are then assembled with negative electrode sheet C to form a soft-pack battery with a designed capacity of 2000mAh. The electrolyte is 1M LiPF6 dissolved in 1mol / L LiPF6 in EC (ethylene carbonate), EMC (ethyl methyl carbonate), and DMC (dimethyl carbonate) at a volume ratio of 1:1:1. A PE separator is used.

[0103] A battery testing system will be used, with each pouch cell undergoing performance testing in a temperature-controlled chamber / environmental chamber. A data acquisition system will synchronously record voltage, current, temperature, and time. The battery testing system will have the following specifications: current accuracy: ≤±0.1%FS (full scale); voltage accuracy: ≤±0.1%FS; current range: must cover 5C charging and discharging currents; response time: ≤10ms; data sampling rate: ≥1Hz. The temperature-controlled chamber / environmental chamber will have the following specifications: temperature range: -20℃ to +60℃ (test temperature: 25℃±2℃); temperature uniformity: within ±2℃ (within the test chamber); temperature control accuracy: ±1℃. The data acquisition system will have a high sampling rate channel for recording detailed charging curves.

[0104] The performance testing process includes:

[0105] Single loop steps:

[0106] Step 1.5C Constant Current Charging (CC@5C): Charge at a constant current of 5C (I_chg=5×C_rated, 5C=10A for the following tests); the termination condition is reaching the charging cutoff voltage (V_chg_cutoff=3.65V); note that the constant voltage (CV) stage is not performed. High-rate tests usually only perform CC charging to simulate fast charging scenarios.

[0107] Step 2. Rest: Let it stand for 30 minutes to allow the voltage to stabilize;

[0108] Step 3. Constant Current Discharge (CC Discharge): Discharge at a constant current rate of the set rate (5C = 10A); the termination condition is reaching the discharge cutoff voltage (V_dis_cutoff = 2.5V);

[0109] Step 4. Rest: Let stand for 10 minutes.

[0110] Execution of cyclical test steps:

[0111] Repeat steps 1, 2, 3, and 4 in sequence; maintain a constant ambient temperature (25℃±2℃); the cycle terminates when the preset number of cycles of 1000 is reached.

[0112] The 5C rate charging performance is calculated as follows: 5C charging capacity / 0.33C charging capacity × 100%; the cycle performance capacity retention rate @ 1000 cycles is calculated as follows: battery capacity at 1000 cycles / initial fresh battery capacity at the first cycle × 100%.

[0113] The results are recorded in Table 2.

[0114] Table 2

[0115] The positive electrode plate contained in the battery 5C rate charging performance Cycling performance / capacity retention @ 1000 cycles Positive electrode A 93.4％ 93.3％ Positive electrode plate B 95.7％ 89.1％ Positive electrode D 93.1％ 92.7％ Positive electrode plate E 95.5％ 90.1％

[0116] As shown in Table 2, the positive electrode sheet produced by integral feeding using the woven bags of the battery powder raw materials described in this invention has the same performance level as the positive electrode sheet produced by the conventional unpacking and feeding process, and may even be slightly improved. In particular, the integrated packaging feeding improves the electrical performance of the ternary electrode sheet, with a 0.3% increase in 5C rate and a 0.6% increase in capacity retention after 1000 cycles. For the lithium iron phosphate system, the rate performance of the battery is basically the same, slightly higher by 0.2%, but the cycle performance is 1% lower, and the difference is not significant.

[0117] As can be seen from the above, this invention innovatively uses packaging materials made of PVDF fibers to package battery powder raw materials. This not only provides a load-bearing function, but also, since PVDF is a commonly used binder component in electrode slurry preparation, allows the entire package containing the material to be directly added to the mixing process and equipment without unpacking. The package acts as a binder, dissolving directly in the solvent and being used directly for slurry mixing, eliminating the need for unpacking or recycling. This effectively avoids dust problems caused by unpacking, improves the cleanliness of the production environment, and achieves "dual use of one material." Furthermore, this whole-bag feeding method does not adversely affect the performance of the resulting positive electrode slurry, positive electrode sheet, and battery; on the contrary, it is more conducive to producing high-performance positive electrode sheets and batteries, making it highly suitable for large-scale industrial applications.

[0118] The preferred embodiments of the present invention have been described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

[0119] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not describe the various possible combinations separately.

[0120] Furthermore, various different embodiments of the present invention can be combined in any way, as long as they do not violate the spirit of the present invention, they should also be regarded as the content disclosed by the present invention.

Claims

1. A method for preparing an electrode paste, characterized in that, The preparation method includes: Provide packaging material including PVDF fiber; use the packaging material to load electrode active material and / or conductive agent to obtain packaged raw material; The packaged raw materials are not unpacked. Instead, the packaging is used as part of the binder, and the packaged raw materials are fed as a whole for mixing and slurry preparation to obtain electrode slurry.

2. The method for preparing the electrode paste according to claim 1, characterized in that, The diameter of the PVDF fiber is 50 nm to 30 μm; Preferably, the packaging includes bags, tubes, or irregularly shaped objects.

3. The method for preparing electrode paste according to claim 2, characterized in that, The method for producing the bag-shaped object includes: spinning PVDF raw material to obtain PVDF fibers, and weaving, blending, bonding or felting the PVDF fibers to obtain the bag-shaped object; Preferably, the spinning method includes at least one of melt spinning, coagulation bath spinning, dry spinning, or electrospinning; Preferably, when the spinning method is melt spinning, the PVDF raw material includes PVDF solid particles; when the spinning method is coagulation bath spinning, dry spinning or electrospinning, the PVDF raw material includes PVDF solution.

4. The method for preparing the electrode paste according to claim 2 or 3, characterized in that, The method for making the bag-shaped object includes: weaving the PVDF fibers to obtain the bag-shaped object, wherein the bag-shaped object is a woven bag; Preferably, the weaving density of the woven bag is 5Tex to 50000Tex; Preferably, the thickness of the woven bag is 100μm to 600μm; Preferably, the particle size D of the loaded electrode active material and / or conductive agent is... 50 When the diameter of the PVDF fiber is ≤1.5μm, the diameter of the PVDF fiber is 0.5nm~25μm; the weaving density of the woven bag is 2000Tex~50000Tex; and the thickness of the woven bag is 100μm~300μm. Preferably, the particle size D of the loaded electrode active material and / or conductive agent is... 50 When the diameter of the PVDF fiber is greater than 1.5 μm, the diameter of the PVDF fiber is 0.1 nm to 10 μm; the weaving density of the woven bag is 5 Tex to 20000 Tex; and the thickness of the woven bag is 200 μm to 600 μm.

5. The method for preparing the electrode paste according to any one of claims 1-4, characterized in that, The packaging material serves as an inner lining, and a semi-transparent protective bag is also placed over the outer part of the packaging material. Preferably, the translucent protective bag is made of any one of PVC, PE, EVA or PA; Preferably, the thickness of the translucent protective bag is 3μm to 8μm; Preferably, the preparation method further includes covering the packaged raw materials with the semi-transparent protective bag during storage and transportation, and removing the semi-transparent protective bag before the packaged raw materials are discharged as a whole.

6. The method for preparing the electrode paste according to any one of claims 1-5, characterized in that, A supplementary binder is also added during the mixing and pulping process; Preferably, the supplementary adhesive comprises at least one of PVDF, PAA, PMMA, SBR, or CMC; Preferably, based on the total mass of the PVDF fiber and the supplementary adhesive as 100%, the proportion of the supplementary adhesive is 0% to 99%, preferably 10% to 65%.

7. The method for preparing the electrode paste according to claim 6, characterized in that, The mixing and pulping are carried out at 25℃~80℃, preferably 35℃~70℃; Preferably, the method for mixing and pulping includes dry mixing, and the dry mixing process includes: 1) Discharge the packaged raw materials as a whole and perform solid-phase mixing to obtain a mixture; 2) Add supplementary binder to the mixture gradually, kneading and stirring after each addition; 3) After the final kneading and stirring, solid-phase dispersion is carried out to obtain the dispersion. 4) Add solvent to the dispersion to adjust the viscosity and obtain electrode slurry; Preferably, the supplementary adhesive is prepared in advance with the solvent to form an adhesive solution before use; Preferably, the solvent includes NMP.

8. An electrode paste, characterized in that, The preparation method according to any one of claims 1-7 is obtained.

9. An electrode sheet, characterized in that, The electrode paste described in claim 8 is used for coating.

10. A battery, characterized in that, It contains the electrode sheet as described in claim 9.