Polyvinylidene fluoride material product, preparation method thereof and preparation method of battery slurry
By encapsulating PVDF powder with a polyvinylidene fluoride film, the problems of PVDF adsorption residue and floating during the transfer process were solved, achieving accurate proportioning and stable bonding performance of the battery slurry.
Patent Information
- Application Number
- CN202510931636.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-07
- Publication Date
- 2025-10-28
AI Technical Summary
PVDF powder is prone to adsorption of residues and floating during the transfer process, resulting in weight deviation and affecting the bonding performance of lithium-ion battery slurry and electrode peel strength.
PVDF powder is wrapped in polyvinylidene fluoride film to form standard weight PVDF material products, avoiding direct contact with transfer equipment and preventing electrostatic adsorption and floating.
To ensure accurate PVDF weight, avoid human error, improve the accuracy of battery slurry formulation, and ensure that bonding performance is not affected.
Smart Images
Figure CN120842618A_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of lithium-ion batteries, and in particular to a polyvinylidene fluoride (PVDF) material product, its preparation method, and a method for preparing battery slurry. Background Technology
[0002] Polyvinylidene fluoride (PVDF) is widely used as a binder in lithium-ion battery slurries due to its excellent electrochemical stability, chemical inertness, solvent resistance, and advantages in adhesion and film formation. Currently, PVDF products are typically available in powder or small particle form. The current method for adding PVDF is as follows: weigh the entire container containing PVDF powder, use a transfer tool to scoop out the required weight of PVDF powder, pour the PVDF into the container used to prepare the lithium-ion battery slurry, weigh the entire container containing PVDF powder again, and calculate the weight of the transferred PVDF.
[0003] However, PVDF has a certain tendency to be electrostatically charged, while battery production environments typically require low humidity. This causes PVDF to easily adhere to the surface of transfer equipment and leave PVDF powder floating in the air during the transfer process, resulting in deviations in the actual weight. Furthermore, scratches, dents, or pores on the surface of the transfer equipment can more easily trap tiny powder particles. These deviations in PVDF weight can further affect the bonding performance of lithium-ion battery slurry, and in severe cases, impact the peel strength of the electrodes. Summary of the Invention
[0004] In view of this, the purpose of this application is to provide a polyvinylidene fluoride material product and a method for preparing the same, so that the polyvinylidene fluoride material product can avoid adsorption residues on the transfer device and floating in the air, avoid loss of binder weight, and make the proportioning more accurate when preparing battery slurry.
[0005] Another objective of this application is to provide a method for preparing battery slurry based on the aforementioned polyvinylidene fluoride material products.
[0006] In order to solve the above-mentioned technical problems / achieve the above-mentioned objectives, or at least partially solve the above-mentioned technical problems / achieve the above-mentioned objectives, as a first aspect of this application, a polyvinylidene fluoride material product is provided, comprising a polyvinylidene fluoride film and polyvinylidene fluoride powder, wherein the polyvinylidene fluoride film encapsulates the polyvinylidene fluoride.
[0007] Optionally, the thickness of the polyvinylidene fluoride film is 60-200 μm.
[0008] Further optionally, the polyvinylidene fluoride film also includes N-methylpyrrolidone. Optionally, the mass ratio of N-methylpyrrolidone to polyvinylidene fluoride is 97:3-90:10.
[0009] As a second aspect of this application, a method for preparing a polyvinylidene fluoride (PVDF) material product as described in this application is provided, comprising:
[0010] S1. Polyvinylidene fluoride powder is coated onto a smooth substrate to form a thin film, thus forming a polyvinylidene fluoride film;
[0011] S2. Place the same batch of polyvinylidene fluoride powder on the polyvinylidene fluoride film, and make the overall weight of the polyvinylidene fluoride meet the expected requirements. Fold the polyvinylidene fluoride film in half to wrap the polyvinylidene fluoride powder, and heat seal it to obtain the polyvinylidene fluoride material product.
[0012] Optionally, S1 includes:
[0013] Polyvinylidene fluoride powder and N-methylpyrrolidone are mixed and stirred into a slurry. The slurry is coated onto a smooth substrate and baked to form a polyvinylidene fluoride film.
[0014] Alternatively, the baking temperature is 80-150°C and the baking time is 1-5 hours.
[0015] Optionally, S1 includes:
[0016] Polyvinylidene fluoride powder is melted and then extruded and coated into a polyvinylidene fluoride film.
[0017] As a third aspect of this application, a method for preparing a battery slurry is provided, wherein the polyvinylidene fluoride material product described in this application and N-methylpyrrolidone are stirred and mixed to form a slurry, and then a conductive agent and an electrode active material are added and stirred continuously. The mixture is adjusted to the required viscosity by adding N-methylpyrrolidone to obtain the battery slurry.
[0018] This application utilizes a PVDF film of a certain weight to encapsulate a certain weight of powdered PVDF material, forming a standard-weight packaged PVDF material product. This avoids direct contact between the PVDF powder and the transfer equipment, preventing adsorption residue due to electrostatic adsorption. Simultaneously, the PVDF film encapsulation prevents the PVDF powder from floating in the air, ensuring no weight loss during PVDF transfer and use. Furthermore, the standard-weight PVDF material product eliminates the need for weighing during battery slurry production, avoiding human error. Attached Figure Description
[0019] Figure 1 The diagram shown is a structural schematic of the PVDF material product of this application;
[0020] Figure 2The figure shows the comparison of dissolution time of materials in each experimental group and control group when used in battery slurry; where, experimental group 1: Example 1; experimental group 2: Example 2; control group 1: Comparative Example 1; control group 2: Comparative Example 2; control group 3: Comparative Example 3;
[0021] Figure 3 The results show the viscosity comparison of the materials used in the experimental and control groups when applied to battery slurry; where, experimental group 1: Example 1; experimental group 2: Example 2; control group 1: Comparative Example 1; control group 2: Comparative Example 2; control group 3: Comparative Example 3. Detailed Implementation
[0022] This application discloses a polyvinylidene fluoride (PVDF) material product and its preparation method, as well as a method for preparing battery slurry. Those skilled in the art can refer to this document and appropriately modify the process parameters to achieve the desired results. It is particularly important to note that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this application. The products, processes, and applications described in this application have been described through preferred embodiments. Those skilled in the art can obviously modify or appropriately change and combine the preparation methods described herein without departing from the content, spirit, and scope of this application to realize and apply the technology of this application. Obviously, the described embodiments are only some, not all, of the embodiments in this application. All other embodiments obtained by those skilled in the art based on the embodiments in this application without creative effort are within the scope of protection of this application.
[0023] It should be noted that, in this document, relational terms such as "first" and "second," "step 1" and "step 2," and "(1)" and "(2)" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element. Moreover, the embodiments and features described in this application can be combined with each other without conflict.
[0024] To address the issues of PVDF floating and residue during transfer using transfer equipment, this application first forms a PVDF film with suitable load-bearing capacity from the PVDF material, and then encapsulates the PVDF powder. Encapsulation with PVDF can eliminate the problems of floating in the air and residue in the equipment, and avoid weight deviation issues of PVDF in the process of preparing battery slurry.
[0025] Therefore, in a first aspect of this application, a polyvinylidene fluoride (PVDF) material product is provided, comprising a PVDF film and PVDF powder, wherein the PVDF film encapsulates the PVDF.
[0026] In some embodiments of this application, the thickness of the PVDF film is 60-200 μm, for example, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 110 μm, 120 μm, 130 μm, 140 μm, 150 μm, 160 μm, 170 μm, 180 μm, 190 μm, 200 μm, or any value between the two. Experiments conducted in this application have shown that PVDF films with a thickness less than 60 μm have poor encapsulation properties, easily leading to leakage of PVDF powder after multiple transfers; while PVDF films with a thickness exceeding 200 μm have better encapsulation properties, the dissolution time of various materials in subsequent battery slurry preparation is significantly increased. Therefore, within the 60-200 μm thickness range specified in this application, it is possible to improve the encapsulation properties of the PVDF film without significantly increasing the material dissolution time.
[0027] In other embodiments of this application, the mass ratio of the PVDF film to the PVDF powder is preferably 5:95-10:90, such as 5:95, 6:94, 7:93, 8:92, 9:91, 10:90, or any ratio between the two. The PVDF film can be manufactured into corresponding length and width specifications according to its mass and expected thickness. For example, a PVDF film with a size of 10cm*20cm and a thickness of 100μm weighs approximately 8g.
[0028] In some embodiments of this application, the PVDF film further comprises N-methylpyrrolidone (NMP). In other embodiments of this application, the mass ratio of NMP to PVDF is 97:3-90:10, for example 97:3, 96:4, 95:5, 94:6, 93:7, 92:8, 91:9, 90:10 or any ratio between the two.
[0029] In a second aspect of this application, a method for preparing a polyvinylidene fluoride (PVDF) material product as described in this application is provided, comprising:
[0030] S1. Polyvinylidene fluoride powder is coated onto a smooth substrate to form a thin film, thus forming a polyvinylidene fluoride film;
[0031] S2. Place the same batch of polyvinylidene fluoride powder on the polyvinylidene fluoride film, and make the overall weight of the polyvinylidene fluoride meet the expected requirements. Fold the polyvinylidene fluoride film in half to wrap the polyvinylidene fluoride powder, and heat seal it to obtain the polyvinylidene fluoride material product.
[0032] In some embodiments of this application, S1 includes:
[0033] PVDF powder and NNP are mixed and stirred into a slurry, which is then coated onto a smooth substrate and baked to form a polyvinylidene fluoride film. Commercially available PVDF powders typically contain different functional groups beneficial to lithium-ion battery performance. The film formation method described in this application does not require high-temperature processing, does not alter the PVDF structure, and since NMP is primarily an organic solvent for subsequent battery slurries, it will not affect the composition of those slurries.
[0034] In some embodiments of this application, the baking temperature is 80-150°C, such as 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C, 150°C or any value between the two, and the baking time is 1-5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours, 5 hours or any value between the two.
[0035] In other embodiments of this application, S1 includes:
[0036] Polyvinylidene fluoride (PVDF) powder is melted and then extruded to form a PVDF film. This film-forming method is simpler than the aforementioned film-forming method of drying a mixed slurry. It does not require the addition of NMP to form a slurry or coating; PVDF films of predetermined thickness and specifications can be prepared directly by extrusion coating. However, its processing temperature is relatively high, which may affect the structure of PVDF.
[0037] In a third aspect of this application, a method for preparing a battery slurry is also provided, wherein the polyvinylidene fluoride material product described in this application and N-methylpyrrolidone are stirred and mixed to form a slurry, and then a conductive agent and an electrode active material are added and stirred continuously. The mixture is adjusted to the required viscosity by adding N-methylpyrrolidone to obtain the battery slurry.
[0038] In some embodiments of this application, the conductive agent includes at least one of conductive carbon black SP, Ketjen black, acetylene black, carbon nanotubes, graphene, and conductive graphite KS-6; the electrode active material includes a positive electrode active material or a negative electrode active material, wherein the positive electrode active material includes, but is not limited to, lithium cobalt oxide, ternary materials, lithium iron phosphate, lithium manganese oxide, lithium-rich manganese-based materials, lithium nickel manganese oxide, lithium nickel cobalt manganese oxide, etc., and the negative electrode active material includes, but is not limited to, graphite materials, silicon-based materials, lithium titanate, and lithium metal, etc.
[0039] In the comparative experiments provided in this application, unless otherwise specified, all experimental conditions and materials are kept consistent to ensure comparability. Unless otherwise specified, all experimental materials and reagents used in the examples are commercially available.
[0040] The following provides a further description of a polyvinylidene fluoride material product, its preparation method, and the preparation method of battery slurry provided in this application.
[0041] Example 1:
[0042] Taking 500g of PVDF required for production as an example;
[0043] NMP and powdered PVDF at a mass ratio of 94:6 were added to a stirred tank. The PVDF dissolved to obtain a slurry.
[0044] The slurry was coated onto a glass plate with a thickness of 100 μm and baked at 120 °C for 2 hours to produce a PVDF film.
[0045] Take a 20cm x 40cm piece of the above film (approximately 8g, film size can be adjusted), and add PVDF powder to make the total weight 500g. Fold the film in half and seal it with a heat sealer at 180℃ to obtain the product as shown. Figure 1 As shown in the diagram.
[0046] Example 2:
[0047] Taking 500g of PVDF required for production as an example;
[0048] PVDF powder was melted into a liquid at 180°C and then coated into a thin film by extrusion with a thickness of 100 μm. The film prepared by this method dissolved in NMP with the same effect as the PVDF powder mentioned above.
[0049] Take a 10cm x 20cm (approximately 8g, size can be adjusted) piece of the above film and place it in the same type of PVDF powder to make the total weight 100g. Fold the film in half and seal it with a heat sealer at a temperature of 180℃.
[0050] Experimental example:
[0051] Taking 500g of PVDF required for production as an example, to prepare PVDF material products with uniform specifications of 10cm*20cm (approximately 8g) of the above-mentioned film, add the same type of PVDF powder to make the total weight 100g:
[0052] Experimental group 1: Prepared according to the method in Example 1;
[0053] Experimental group 2: Prepared according to the method in Example 2;
[0054] Control group 1: Prepared according to the method of Example 1, except that the film thickness is 300 μm;
[0055] Control group 2: Prepared according to the method of Example 1, except that the film thickness is 50 μm;
[0056] Control group 3: Direct use of PVDF powder;
[0057] (1) Test the strength of the film of each group of materials.
[0058] Simulate the height of daily use by dropping the product freely from a height of 2 meters onto the floor. Repeat this 10 times and observe whether the product is damaged.
[0059] Experimental results: No damage was found in experimental group 1, experimental group 2 and control group 1. However, control group 2 was damaged and exposed the PVDF powder on the sixth test, indicating that the thickness of control group 2 was too small and could not achieve the required encapsulation performance.
[0060] (2) Test the dissolution time of each group of material products.
[0061] During production, the PVDF materials from the experimental and control groups were added to a mixing tank, along with the main materials lithium titanate (negative electrode) and conductive carbon black SP. The proportions were the same for all groups. After feeding, the mixture was stirred until no visible particles were observed and the viscosity no longer changed, at which point it was considered completely dissolved. The results are shown in [see attached figure]. Figure 2 ;
[0062] according to Figure 2 The dissolution time comparison shows that the control group 3, which uses the conventional method of directly using PVDF powder, has a complete dissolution time of 235 min for the entire battery slurry; the complete dissolution times of experimental group 1 and experimental group 2 are 241 min and 247 min, respectively, which are not significantly different from the control group 3; the complete dissolution time of control group 1 is significantly increased to 306 min due to the excessive thickness of the PVDF film; the PVDF film thickness of control group 2 is smaller, which has little impact on the dissolution time and is closest to that of control group 3, but the aforementioned film encapsulation is not strong.
[0063] Meanwhile, the slurry viscosity of the battery slurry prepared in each experimental group and the control group was tested, and the results are shown in [the table below]. Figure 3 ;
[0064] Figure 3 The results show that the viscosity of the battery slurry prepared in each group is basically similar, indicating that the PVDF material product prepared in this application does not affect the effect of PVDF and has no significant impact on its bonding performance.
[0065] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.
Claims
1. A polyvinylidene fluoride (PVDF) material product, characterized in that, It includes a polyvinylidene fluoride (PVDF) film and PVDF powder, wherein the PVDF film encapsulates the PVDF.
2. The polyvinylidene fluoride material product according to claim 1, characterized in that, The thickness of the polyvinylidene fluoride film is 60-200 μm.
3. The polyvinylidene fluoride material product according to claim 1 or 2, characterized in that, The polyvinylidene fluoride film also includes N-methylpyrrolidone.
4. The polyvinylidene fluoride material product according to claim 3, characterized in that, The mass ratio of N-methylpyrrolidone to polyvinylidene fluoride is 97:3-90:
10.
5. A method for preparing the polyvinylidene fluoride material product as described in claim 1, characterized in that, include: S1. Polyvinylidene fluoride powder is coated onto a smooth substrate to form a thin film, thus forming a polyvinylidene fluoride film; S2. Place the same batch of polyvinylidene fluoride powder on the polyvinylidene fluoride film, and make the overall weight of the polyvinylidene fluoride meet the expected requirements. Fold the polyvinylidene fluoride film in half to wrap the polyvinylidene fluoride powder, and heat seal it to obtain the polyvinylidene fluoride material product.
6. The preparation method according to claim 5, characterized in that, S1 includes: Polyvinylidene fluoride powder and N-methylpyrrolidone are mixed and stirred into a slurry. The slurry is coated onto a smooth substrate and baked to form a polyvinylidene fluoride film.
7. The preparation method according to claim 6, characterized in that, The baking temperature is 80-150℃, and the time is 1-5 hours.
8. The preparation method according to claim 5, characterized in that, S1 includes: Polyvinylidene fluoride powder is melted and then extruded and coated into a polyvinylidene fluoride film.
9. A method for preparing a battery slurry, characterized in that, The polyvinylidene fluoride material product according to any one of claims 1-4 and N-methylpyrrolidone are stirred and mixed to form a slurry. Then, a conductive agent and an electrode active material are added and stirring is continued. The mixture is adjusted to the required viscosity by adding N-methylpyrrolidone to obtain the battery slurry.