Method for preparing battery pole piece, battery positive pole piece and battery
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- SHENZHEN TOPBAND NEW ENERGY CO LTD
- Filing Date
- 2023-04-07
- Publication Date
- 2026-07-14
Smart Images
Figure CN116469998B_ABST
Abstract
Description
Technical Field
[0001] This application relates to the field of battery manufacturing technology, and in particular to a method for preparing a battery electrode, a battery positive electrode, and a battery. Background Technology
[0002] In recent years, the new energy vehicle and energy storage sectors have flourished, leading to a sharp increase in demand for lithium-ion batteries. However, the insufficient lithium resources have resulted in a significant increase in lithium salt prices and a substantial increase in the cost of lithium-ion batteries, which is detrimental to the healthy and sustainable development of the new energy vehicle industry.
[0003] Sodium, which belongs to the same group as lithium, has abundant resources and is inexpensive. Therefore, the research and development of sodium-ion batteries has, to some extent, alleviated the problem of limited development of new energy vehicle batteries caused by the shortage of lithium resources. Moreover, if high-performance, safe and stable materials are developed on this basis, sodium-ion batteries will have a greater competitive advantage in the market than lithium-ion batteries.
[0004] In the research or industrialization of sodium-ion batteries, the cathode materials used are prone to cracking or crushing during the rolling process of battery manufacturing. The cracking and crushing of the inner layered transition metal oxides of the cathode are the most obvious problems. This leads to a significant increase in the contact area between the cathode and the electrolyte, and a corresponding increase in side reactions, resulting in gas production (the cathode participates in chemical reactions and produces gas). This problem seriously limits the application of sodium-ion batteries in the field of new energy vehicles. Summary of the Invention
[0005] The purpose of this application is to provide a method for preparing a battery electrode, a battery positive electrode, and a battery. This method is applied in the manufacturing process of sodium-ion batteries. It can repair the active material in the positive electrode after rolling, prevent the electrolyte from entering the gaps of the broken particles of the active material after rolling, reduce side reactions and the gases generated by the side reactions, thereby significantly slowing down the consumption rate of electrolyte during cycling and significantly improving the cycle life of sodium-ion batteries.
[0006] Therefore, in a first aspect, embodiments of this application provide a method for preparing a battery electrode, which includes the following steps:
[0007] S1. Preparation of battery electrode slurry;
[0008] S2. The battery electrode slurry is coated onto a conductive substrate and dried to form a battery electrode layer on the conductive substrate.
[0009] S3. Roll the conductive substrate and the battery electrode layer to form a battery electrode;
[0010] S4. Dissolve polyvinylidene fluoride in N-methylpyrrolidone to form a glue solution, wherein the weight percentage of polyvinylidene fluoride in the glue solution is 2%-10%, and the molecular weight of polyvinylidene fluoride is 700,000-1,400,000.
[0011] S5. The adhesive is applied to the surface of the battery electrode, dried, and the target electrode is formed.
[0012] In a second aspect, this application also proposes a battery positive electrode sheet, which is manufactured based on the battery electrode sheet preparation method described in the first aspect.
[0013] In a third aspect, this application also proposes a battery comprising a positive electrode and a negative electrode as described in the second aspect.
[0014] This application proposes a method for preparing a battery electrode, a battery positive electrode, and a battery. Compared with the prior art, its advantages are as follows:
[0015] This method coats the surface of rolled battery electrodes, such as sodium metal compound battery electrodes, with a glue composed of polyvinylidene fluoride and N-methylpyrrolidone. This repairs the damage to the surface of the active material inside the battery electrode caused by rolling, prevents electrolyte from entering the gaps between the broken particles of the active material after rolling, reduces side reactions and the gases generated by the side reactions, thereby significantly slowing down the electrolyte consumption rate during cycling and greatly improving the cycle life of batteries such as sodium-ion batteries.
[0016] This application also proposes a battery positive electrode sheet made using the above method and a battery containing the battery positive electrode sheet. The battery can use a metal compound such as sodium as the active material in the battery positive electrode sheet and can effectively avoid excessive contact between the positive electrode sheet and the electrolyte, thereby ensuring its cycle performance. Attached Figure Description
[0017] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort. In addition, in the drawings, the same parts use the same reference numerals, and the drawings are not drawn to scale.
[0018] Figure 1 This is a comparison chart of the capacity retention stability of the batteries prepared in Examples 1, 2 and 3 of this application with the batteries prepared in the comparative test in terms of the number of charge-discharge cycles.
[0019] Figures 2-4The images are scanning electron microscope (SEM) images of the positive electrode sheets of the batteries prepared in Examples 1, 2, and 3 of this application, respectively.
[0020] Figure 5 This is a scanning electron microscope image of the positive electrode sheet of the battery prepared in the comparative experiment; Detailed Implementation
[0021] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.
[0022] This application provides a method for preparing a battery electrode sheet in its first aspect, which includes the following steps:
[0023] S1. Preparation of battery electrode slurry;
[0024] S2. The battery electrode slurry is coated onto the conductive substrate and dried to form a battery electrode layer on the conductive substrate.
[0025] S3. Roll the conductive substrate and battery electrode layer to form battery electrodes;
[0026] S4. Dissolve polyvinylidene fluoride (PVDF) in N-methylpyrrolidone (NMP, an organic solvent with the highest PVDF solubility) to form a glue solution, wherein the weight percentage of polyvinylidene fluoride in the glue solution is 2%-10%, and the molecular weight of polyvinylidene fluoride is 700,000-1,400,000.
[0027] S5. Apply the adhesive to the surface of the battery electrode, dry it, and form the target electrode.
[0028] Based on the above technical solution, this method coats the surface of the rolled battery electrode sheet, such as a sodium metal compound battery electrode sheet, with a glue solution composed of polyvinylidene fluoride and N-methylpyrrolidone. In this glue solution, the weight percentage of polyvinylidene fluoride is 2%-10%, and the molecular weight of polyvinylidene fluoride is 700,000-1,400,000. This repairs the damage to the surface of the active material in the battery electrode sheet caused by rolling, prevents the electrolyte from entering the gaps of the broken particles of the active material after rolling, reduces side reactions and the gases generated by the side reactions, thereby significantly slowing down the electrolyte consumption rate during cycling and significantly improving the cycle life of batteries such as sodium-ion batteries.
[0029] Specifically, step S5 above includes the following steps:
[0030] S51. The adhesive is applied to the surface of the battery electrode by spraying or coating. If a coating machine is used for coating, the width of the outlet gap of the coating machine can be set to 10 micrometers-100 micrometers.
[0031] Therefore, the adhesive is evenly coated on the surface of the battery electrode to improve the repair effect of the layered transition metal oxides within the battery electrode.
[0032] Next, the adhesive on the surface of the battery electrodes needs to be dried:
[0033] S52. The adhesive coating on the surface of the battery electrode is dried at a temperature of 80℃-120℃. After drying, the amount of solid material remaining on the surface of the battery electrode after drying is 0.1g / m. 2 -6g / m 2 .
[0034] In fact, the solid substance left on the surface of the battery electrode is polyvinylidene fluoride, which is a kind of adhesive. After the sodium-ion battery electrode undergoes the rolling process, it can effectively bond the layered transition metal oxides in the sodium-ion battery electrode, repair the damage to the surface of the active material caused by rolling, prevent the electrolyte from entering the gaps of the broken particles of the active material after rolling, reduce side reactions and the gases generated by the side reactions, thereby significantly slowing down the electrolyte consumption rate during the cycle and improving the cycle life of the battery.
[0035] In this method, the amount of polyvinylidene fluoride remaining on the surface of the battery electrode is 0.1 g / m. 2 -6g / m 2 In this way, while ensuring the repair effect, the conductivity of the target electrode is also ensured. If too much polyvinylidene fluoride remains, it will hinder the contact of the active material in the target electrode with the electrolyte, thereby affecting the conductivity of the target electrode. If too little polyvinylidene fluoride remains, the repair effect will be poor, which will reduce the cycle performance of the target electrode.
[0036] Step S1 above includes the following steps:
[0037] S11. Dissolve the active electrode material, conductive material and binder material in a solvent, stir and prepare a battery electrode slurry. In the solid content of the battery electrode slurry, that is, in the solid matter dissolved in the solvent, the proportion of active electrode material is 90%-96%, the proportion of conductive material is 2%-5%, and the proportion of binder material is 2%-5%.
[0038] Furthermore, to ensure the quality of the battery electrodes, step S11 above includes the following steps:
[0039] The active material of the electrode, the conductive material, the binder and the solvent are placed in a mixing tank and stirred. The stirring speed of the stirring paddle is set to 30 rpm-60 rpm, the speed of the dispersing wheel is set to 1000 rpm-3000 rpm, the stirring time is 120 min-240 min, and the stirring temperature is 30℃-50℃.
[0040] This ensures that the electrode active material, conductive material, and binder material can be completely dissolved in the solvent.
[0041] In this method, the active material of the electrode is one or more of transition metal oxides, polyanionic materials, and Prussian blue compounds; the conductive material is one or more of conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, and graphene; and the binder material includes polyvinylidene fluoride.
[0042] The microstructures of the aforementioned transition metal oxides include single-crystal and polycrystalline structures, such as sodium nickel iron manganate, with the chemical formula: Na. x Ni a Fe b Mn c M d O2 (0 < x ≤ 1, a + b + c + d = 1, a > 0, b > 0, c > 0, M is one or more of Cu, Ti, Zr, and Co).
[0043] Furthermore, in step S2 above, the thickness of the battery electrode paste coated on the conductive substrate is 100 micrometers to 200 micrometers (this is the thickness of the paste remaining on the conductive substrate after drying); the conductive substrate includes aluminum foil.
[0044] Therefore, in this application, sodium nickel iron manganese oxide is selected as the active material for the electrode, and the steps of Example 1 are as follows:
[0045] 1. Prepare the slurry according to the following proportions;
[0046] The electrode active material accounts for 96% by weight, conductive carbon black accounts for 2% by weight, binder (PVDF) accounts for 2% by weight, and N-methylpyrrolidone (NMP, as a solvent) is added in appropriate amount.
[0047] 2. Coat the prepared slurry evenly onto the aluminum foil and dry it (drying temperature is 80-120℃, air volume adjustment parameter is set to 10-50Hz, belt speed is 4m / min-50m / min).
[0048] 3. Roll press according to the required thickness to produce the target positive electrode sheet.
[0049] 4. Mix NMP and PVDF with a molecular weight of 1.1 million at a ratio of 92:8 (by weight) and stir to dissolve into a solution with a solid content of 8%.
[0050] 5. Apply the adhesive solution to the rolled target positive electrode using a coating machine, and dry it at 100℃ to form the target electrode. (The coating machine parameters are controlled as follows: the outlet gap width is set to 10-100µm to control the coating thickness and amount; the baking temperature is set to 80-120℃; the airflow is set to 10-50Hz; and the conveyor speed is 4m / min-50m / min. This achieves a coating amount (the amount of solid material after drying) of 0.5g / m² on the target positive electrode.) 2 ).
[0051] Afterwards, a small piece of the target positive electrode can be taken and its surface crack repair status can be observed using a scanning electron microscope.
[0052] The steps of Embodiment 2 of this application are as follows:
[0053] 1. Prepare the slurry according to the following proportions;
[0054] The electrode active material accounts for 96% by weight, conductive carbon black accounts for 2% by weight, binder (PVDF) accounts for 2% by weight, and N-methylpyrrolidone (NMP, as a solvent) is added in appropriate amount.
[0055] 2. Coat the prepared slurry evenly onto the aluminum foil and dry it (drying temperature is 80-120℃, air volume is 10-50Hz, and belt speed is 4m / min-50m / min).
[0056] 3. Roll press according to the required thickness to produce the target positive electrode sheet.
[0057] 4. Mix NMP and PVDF with a molecular weight of 800,000 at a ratio of 90:10 (by weight) and stir to dissolve into a 10% solid content solution.
[0058] 5. Apply the adhesive solution to the rolled target positive electrode using a coating machine, and dry at 100℃ to form the target electrode. (The coating machine parameters are controlled as follows: the outlet gap width is set to 10-100µm to control the coating thickness and amount; the baking temperature is set to 80-120℃; the airflow is set to 10-50Hz; and the conveyor speed is 4m / min-50m / min. This achieves a coating amount (the amount of solid material after drying) of 3g / m² on the target positive electrode.) 2 ).
[0059] Afterwards, a small piece of the target positive electrode can be taken and its surface crack repair status can be observed using a scanning electron microscope.
[0060] The steps of Embodiment 3 of this application are as follows:
[0061] 1. Prepare the slurry according to the following proportions;
[0062] The electrode active material accounts for 96% by weight, conductive carbon black accounts for 2% by weight, binder (PVDF) accounts for 2% by weight, and N-methylpyrrolidone (NMP, as a solvent) is added in appropriate amount.
[0063] 2. Coat the prepared slurry evenly onto the aluminum foil and dry it (drying temperature is 80-120℃, air volume is 10-50Hz, and belt speed is 4m / min-50m / min).
[0064] 3. Roll press according to the required thickness to produce the target positive electrode sheet.
[0065] 4. Mix NMP and PVDF with a molecular weight of 1.3 million at a ratio of 95:5 (by weight) and stir to dissolve into a 5% solid content solution.
[0066] 5. Apply the adhesive solution to the rolled target positive electrode using a coating machine, and dry it at 100℃ to form the target electrode. (The coating machine parameters are controlled as follows: the outlet gap width is set to 10-100µm to control the coating thickness and amount; the baking temperature is set to 80-120℃; the airflow is set to 10-50Hz; and the conveyor speed is 4m / min-50m / min. This achieves a coating amount (the amount of solid material after drying) of 6g / m² on the target positive electrode.) 2 ).
[0067] Afterwards, a small piece of the target positive electrode can be taken and its surface crack repair status can be observed using a scanning electron microscope.
[0068] Similarly, a comparative experiment was conducted:
[0069] 1. Prepare the slurry according to the following proportions;
[0070] The electrode active material accounts for 96% by weight, conductive carbon black accounts for 2% by weight, binder (PVDF) accounts for 2% by weight, and N-methylpyrrolidone (NMP, as a solvent) is added in appropriate amount.
[0071] 2. Coat the prepared slurry evenly onto the aluminum foil and dry it (drying temperature is 80-120℃, air volume is 10-50Hz, and belt speed is 4m / min-50m / min).
[0072] 3. Roll press according to the required thickness to produce the target positive electrode sheet.
[0073] In the above embodiments and experiments, hard carbon was used as the negative electrode active material to make negative electrode sheets. The positive and negative electrode sheets were then assembled into soft-pack finished cells using a stacking method and industry-standard processes, and their cycle performance was tested.
[0074] like Figures 1-5 As shown in the diagrams, the scanning electron microscope (SEM) images of the above embodiments and the comparative experiment show that the adhesive coating on the positive electrode can significantly repair the lamellar cracks on the particle surface caused by rolling and cover the crushed particles. Figure 5 (A very obvious crack appears in the box pointed to by A) This prevents the electrolyte from seeping into the crack and the gap between the broken particles, reduces the contact area between the electrolyte and the positive electrode surface and the occurrence of side reactions, thereby reducing the consumption of electrolyte during the cycle and improving the cycle performance.
[0075] It needs to be explained here that... Figures 2-5 In the accompanying images, the areas of the positive electrode plates scanned by the scanning electron microscope are slightly different because it is difficult to scan the corresponding areas in the positive electrode plates of different batteries. However, it can be clearly seen from the accompanying images that cracks appeared in the positive electrode plates of the batteries in the comparative test, while no obvious cracks were found in Examples 1, 2 and 3.
[0076] In a second aspect, this application also proposes a battery positive electrode sheet, which is manufactured based on the battery electrode sheet preparation method described in the first aspect.
[0077] In a third aspect, this application also proposes a battery comprising a positive electrode and a negative electrode as described in the second aspect. This battery can use a sodium metal compound as a transition metal oxide in the positive electrode and can effectively prevent excessive contact between the positive electrode and the electrolyte, thereby ensuring its safety.
[0078] It should be noted that the terms "one embodiment," "embodiment," "exemplary embodiment," "some embodiments," etc., mentioned in the specification indicate that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, such phrases do not necessarily refer to the same embodiment. Moreover, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments, whether explicitly described or not, is within the knowledge scope of those skilled in the art.
[0079] It should be readily understood that the terms “on,” “above,” and “on top of” in this disclosure should be interpreted in the broadest possible sense, such that “on” means not only “directly on something” but also “on something” with an intermediate feature or layer therebetween, and that “above” or “on top of” means not only “on top of something” but also “on top of something” without an intermediate feature or layer therebetween (i.e., directly on something).
[0080] Furthermore, for ease of explanation, spatially relative terms such as "below," "below," "under," "above," and "above" may be used to describe the relationship of one element or feature relative to other elements or features as shown in the figures. Spatially relative terms are intended to encompass different orientations of the device in use or operation other than those shown in the figures. The device may have other orientations (rotated 90 degrees or in other orientations), and the spatially relative descriptive terms used herein may be interpreted accordingly.
[0081] It should be noted that, in this document, relational terms such as "first" and "second" 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.
[0082] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit them. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such 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 method for preparing a battery electrode, characterized in that, The method for preparing a positive electrode sheet for a sodium-ion battery includes the following steps: A battery electrode slurry comprising an electrode active material is prepared, wherein the electrode active material is a transition metal oxide, and the microstructure of the transition metal oxide includes a single crystal structure and a polycrystalline structure. The battery electrode slurry is coated onto a conductive substrate and dried to form a battery electrode layer on the conductive substrate. The conductive substrate and the battery electrode layer are rolled together to form battery electrodes; Polyvinylidene fluoride is dissolved in N-methylpyrrolidone to form a gel, wherein the weight percentage of polyvinylidene fluoride in the gel is 2%-10%, and the molecular weight of polyvinylidene fluoride is 700,000-1,400,000. The adhesive is coated onto the surface of the battery electrode, dried, and the target electrode is formed. The process of coating the adhesive onto the surface of the battery electrode, drying it, and forming the target electrode includes the following steps: The adhesive is applied to the surface of the battery electrode by spraying or coating. The adhesive solution coated on the surface of the battery electrode is dried at a temperature of 80℃-120℃. After drying, the amount of solid material remaining on the surface of the battery electrode after drying is 0.1 g / m³. 2 -6g / m 2 .
2. The method for preparing battery electrode sheets according to claim 1, characterized in that, The preparation of the battery electrode slurry includes the following steps: The active electrode material, conductive material, and binder material are dissolved in a solvent, stirred, and the battery electrode slurry is prepared. In the solid material dissolved in the solvent, the weight percentage of the active electrode material is 90%-96%, the weight percentage of the conductive material is 2%-5%, and the weight percentage of the binder material is 2%-5%.
3. The method for preparing battery electrode sheets according to claim 2, characterized in that, The electrode active material, the conductive material, the binder and the solvent are placed in a mixing tank and stirred. The stirring speed of the stirring paddle is set to 30 rpm-60 rpm, the speed of the dispersing wheel of the stirring tank is set to 1000 rpm-3000 rpm, the stirring time is 120 min-240 min, and the stirring temperature is 30℃-50℃.
4. The method for preparing battery electrode sheets according to claim 2, characterized in that, The active material of the electrode also includes one or more of polyanionic materials and Prussian blue compounds; The conductive material is one or more of the following: conductive carbon black, conductive graphite, carbon fiber, carbon nanotubes, and graphene. The adhesive material includes polyvinylidene fluoride.
5. The method for preparing battery electrode sheets according to claim 1, characterized in that, The thickness of the battery electrode paste coated on the conductive substrate is 100-200 micrometers.
6. The method for preparing battery electrode sheets according to claim 1, characterized in that, The conductive substrate includes aluminum foil.
7. A positive electrode plate for a battery, characterized in that, The positive electrode of the battery is manufactured based on the method for preparing a battery electrode as described in any one of claims 1-6.
8. A battery, characterized in that, Includes the battery positive electrode and battery negative electrode as described in claim 7.