Electrode layer formation method
By applying a binder solution and projecting active material powder onto a current collector, the method addresses the issue of inadequate powder density in electrode layers, resulting in a high-density, efficient, and cost-effective electrode formation process.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Applications
- Current Assignee / Owner
- NISSAN MOTOR CO LTD
- Filing Date
- 2025-01-16
- Publication Date
- 2026-07-29
AI Technical Summary
Existing methods for forming an electrode layer using a pressing roller result in inadequate powder density due to liquid bridging forces, leading to potential gaps and uneven distribution of granulated particles.
A method involving applying a binder solution onto a current collector, projecting active material powder onto the binder layer, and ensuring at least partial contact with the collector surface to form an electrode layer with controlled density.
The method achieves an electrode layer with appropriate powder density, improved thickness, and reduced material scattering, enhancing manufacturing efficiency and battery performance.
Smart Images
Figure 2026122645000001_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a method for forming an electrode layer.
Background Art
[0002] Patent Document 1 discloses a method of forming an electrode layer by applying a binder solution onto a current collector, supplying granulated particles onto the current collector, and pressing the granulated particles against the current collector by a pressing roller.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] By the way, when pressing granulated particles together with a binder solution against a current collector by a pressing roller, a force that spreads between the granulated particles acts due to the liquid bridging force by which the granulated particles adhere to the pressing roller, and there is a fear that an electrode layer having an appropriate powder density cannot be obtained.
[0005] An object of the present invention is to form an electrode layer having an appropriate powder density.
Means for Solving the Problems
[0006] An electrode layer forming method according to an aspect of the present invention includes forming a binder layer by applying a binder solution onto the surface of a current collector foil, projecting a powder of an active material onto the binder layer, and forming an electrode layer in which at least a part of the powder of the active material is in contact with the surface of the current collector foil.
Effects of the Invention
[0007] According to the electrode layer forming method of the present invention, an electrode layer having an appropriate powder density can be formed.
Brief Description of the Drawings
[0008] [Figure 1] This is a plan view showing the structure of the electrode layer according to the embodiment. [Figure 2] This is a schematic diagram illustrating the electrode layer formation method. [Figure 3] This is a schematic diagram showing an electrode layer formation method that includes a drying step. [Figure 4] This is a schematic diagram showing an electrode layer formation method including a pre-drying step and a drying step. [Figure 5] This is a schematic diagram showing a method for forming the separator layer. [Modes for carrying out the invention]
[0009] The electrode layer formation method according to the embodiment will be described below with reference to the drawings. Furthermore, components having the same function as those already described will be denoted by the same reference numerals and their descriptions will be omitted.
[0010] A method for forming an electrode layer according to an embodiment will now be described. As illustrated in Figure 1, the electrode layer 2 is formed on the surface 1A of the current collector foil 1. The electrode layer 2 is, for example, a positive electrode layer or a negative electrode layer used as an electrode in a secondary battery. As illustrated in Figure 2, the method for forming the electrode layer 2 includes a first step S1 for forming a binder layer 11A, and a second step S2 for projecting active material powder 21 onto the binder layer 11A.
[0011] The current collector foil 1 is a current collector formed in the form of a thin film, and known current collectors such as aluminum foil, aluminum alloy foil, copper foil, and nickel foil can be used. In the electrode layer forming method according to the embodiment, the current collector foil 1 is transported at a constant speed from left to right in Figure 2-6 by, for example, a transport device. That is, the current collector foil 1 moves relative to the first nozzle 31 and the second nozzle 41, which will be described later, in the direction from left to right in Figure 2-6.
[0012] As illustrated in Figure 2, in the first step S1, a binder solution 11 is applied to the surface 1A of the current collector foil 1. As illustrated in Figure 2, the binder solution 11 is applied to the surface 1A of the current collector foil 1 from a second nozzle 41 positioned above the current collector foil 1. At this time, the current collector foil 1 is transported at a constant speed relative to the second nozzle 41. This makes it possible to form a binder layer 11A having a predetermined thickness in the horizontal direction (width direction and transport direction of the current collector foil 1) on the surface 1A of the current collector foil 1. The second nozzle 41 may consist of multiple nozzles arranged in parallel in a line in the width direction of the current collector foil 1, or the binder solution 11 may be applied while scanning the second nozzle 41 in the width direction of the current collector foil 1. The binder solution 11 is applied in a predetermined pattern to a predetermined area on the surface 1A of the current collector foil 1. Furthermore, as long as a binder layer 11A having a predetermined thickness in the horizontal direction can be formed, the structure of the second nozzle 41, the coating method, coating speed, coating pressure, etc., are not particularly limited, and known methods such as dispensers, inkjet printers, and sprayers can be applied.
[0013] In the first step S1, a binder layer 11A is formed by applying a binder solution 11 to the surface 1A of the current collector foil 1. The thickness of the binder layer 11A according to this embodiment is, for example, 10 to 100 μm. The binder solution 11 contains a binder and a solvent. The type of binder is not particularly limited, but known materials such as polyvinylidene fluoride (PVdF) and a composite of polyvinylidene fluoride and hexafluoropropylene (HFP) can be used. The solvent is not particularly limited, but known materials such as N-methylpyrrolidone (NMP) and acetonitrile can be used.
[0014] As illustrated in Figure 2, in the second step S2, the active material powder 21 is projected onto the binder layer 11A. As illustrated in Figure 2, the active material powder 21 is projected from the first nozzle 31 and collides onto the binder layer 11A. At this time, the current collector foil 1 is transported at a constant speed relative to the first nozzle 31. As a result, an active material powder layer 21A having a predetermined thickness in the horizontal direction is formed in the binder layer 11A on the surface 1A of the current collector foil 1. The first nozzle 31 has multiple nozzles arranged in parallel in a line in the width direction of the current collector foil 1. The nozzle diameter of the first nozzle 31 in this embodiment is about 1 mm, and the particle size of the active material powder 21 is about 10 μm. The structure of the first nozzle 31 is not limited to the above, and for example, the active material powder layer 21A may be projected while scanning the first nozzle 31 in the width direction of the current collector foil 1.
[0015] In the second step S2, an electrode layer 2 is formed by bringing at least a portion of the active material powder 21 into contact with the surface 1A of the current collector foil 1. By projecting the active material powder 21 onto the binder layer 11A, the gaps between the particles of the active material powder 21 can be filled by the particles that arrive later, promoting contact between particles in the active material powder layer 21A. Therefore, the gaps between particles can be properly filled by the particles of the active material powder 21. As a result, an electrode layer 2 (active material powder layer 21A) with a high powder density of the active material powder 21 can be formed. Powder density is defined as bulk density. The powder density value according to this embodiment is, for example, 3.0 g / cm³. 2 That is the case.
[0016] In the second step S2, the active material powder 21 is projected onto the binder layer 11A at a predetermined speed. As a result, the active material powder 21 collides with the binder layer 11A with a predetermined kinetic energy. Therefore, at least a portion of the active material powder 21 penetrates into the binder layer 11A in the thickness direction. That is, by projecting the active material powder 21 onto the binder layer 11A at a predetermined speed, at least a portion of the active material powder 21 can be brought into contact with the surface 1A of the current collector foil 1. Thus, the projected active material powder 21 can be brought into contact with the surface 1A of the current collector foil 1 to form an active material powder layer 21A, and thus form the electrode layer 2. The predetermined speed according to this embodiment is 200 m / sec. The thickness of the active material powder layer 21A according to this embodiment is approximately 100 to 200 μm. Furthermore, the structure, projection method, projection speed, projection pressure, etc. of the first nozzle 31 are not limited, as long as an active material powder layer 21A having a predetermined thickness in the horizontal direction can be formed and an electrode layer 2 can be formed.
[0017] As illustrated in Figure 2, the active material powder 21 is projected through the first nozzle 31. The active material powder 21 is projected from the first nozzle 31 at a predetermined pressure using air or nitrogen as a carrier gas. The predetermined pressure P according to this embodiment is in the range of 0.01 to 1.0 MPa. As a result, the active material powder 21 is accelerated by the predetermined pressure and collides with the binder layer 11A with a predetermined kinetic energy. Therefore, at least a portion of the active material powder 21 penetrates the binder layer 11A in the thickness direction. In addition, when the predetermined pressure is applied to the surface of the binder layer 11A, the binder layer 11A may deform to a small thickness. Furthermore, the thickness of the active material powder layer 21A is stacked to a thickness of approximately 100 to 200 μm. As a result, by projecting the active material powder 21 onto the binder layer 11A at a predetermined pressure, at least a portion of the active material powder 21 can be brought into contact with the surface 1A of the current collector foil 1, thereby forming the electrode layer 2.
[0018] When the electrode layer 2 is used as the positive electrode layer, the powder 21 of the active material may be, for example, a layered rock salt type active material such as LiCoO2, LiMnO2, LiNiO2, LiVO2, Li(Ni-Mn-Co)O2, a spinel type active material such as LiMn2O4, LiNi 0.5 Mn 1.5 O4, an olivine type active material such as LiFePO4, LiMnPO4, a Si-containing active material such as Li2FeSiO4, Li2MnSiO4, etc. can be used. Further, as oxide active materials other than the above, for example, Li4Ti5O 12 can be mentioned. In addition, positive electrode active materials other than the above may be used. When the electrode layer 2 is used as the negative electrode layer, the powder 21 of the active material may be, for example, a carbon material, a metal oxide, and a metal active material. The negative electrode active material may be a metal containing Li, and such a negative electrode active material is not particularly limited as long as it is an active material containing Li.
[0019] As illustrated in FIG. 3, the electrode layer forming method according to the embodiment may include a drying step S2-2 of drying at least a part of the binder layer 11A contained in the electrode layer 2 after the second step S2 of projecting the powder 21 of the active material. As illustrated in FIG. 3, the drying device 4 can dry the binder layer 11A and promote the evaporation of the solvent contained in the binder layer 11A. Thereby, the binder layer 11A is partially cured.
[0020] As illustrated in FIG. 4, the electrode layer forming method according to the embodiment may include a preliminary drying step S1-2 of drying at least a part of the binder layer 11A by a drying device 5 after the first step S1 of forming the binder layer 11A and before the second step S2 of projecting the active material powder 21. As illustrated in FIG. 4, the drying device 5 can dry the binder layer 11A and promote the evaporation of the solvent contained in the binder layer 11A. Thereby, since the viscosity of the formed binder layer 11A increases to a certain extent, it is possible to suppress scattering, flowing, etc. to the surroundings. Only one of the above-mentioned preliminary drying step S1-2 and drying step S2-2 may be carried out, or both may be carried out in combination. The drying devices 4 and 5 are, for example, lamps, hot plates, etc., and their arrangements are not limited to the arrangements illustrated in FIGS. 3 and 4. Also, during the above-mentioned preliminary drying step S1-2 and drying step S2-2, the conveyance of the current collector foil 1 may be stopped. In the preliminary drying step S1-2, for example, a drying step at a drying temperature of 60° C. for 5 minutes is performed. In the drying step S2-2, for example, a drying step at a drying temperature of 80° C. for 5 minutes is performed.
[0021] When adding a conductive assistant to the positive electrode or the negative electrode, as shown in FIG. 2, in the second step S2 of projecting the active material powder 21, the conductive assistant 61 can be included in the active material powder 21. Thereby, the electrode layer 2 to which the conductive assistant 61 is added can be formed.
[0022] Examples of the conductive assistant include metals such as aluminum, stainless steel, silver, gold, copper, titanium, alloys or metal oxides containing these metals, carbon fibers, carbon nanotubes, carbon nanofibers, carbon black (such as acetylene black), etc., but are not limited thereto. These conductive assistants may contain two or more kinds.
[0023] As illustrated in Figure 5, the electrode layer formation method according to the embodiment may further include a third step S3, a fourth step S4, and a drying step S4-2. In the third step S3, a binder solution 11 is applied to the electrode layer 2 to form a second binder layer 12A. In the fourth step S4, a separator component powder 51 is projected onto the second binder layer 12A. As illustrated in Figure 5, the separator component powder 51 is projected onto the second binder layer 12A from the first nozzle 31 under predetermined conditions. In the drying step S4-2, a separator layer 51A is formed by drying. Note that one or both of the pre-drying steps S1-2 and the drying step S2-2 may be performed before the third step S3. Also, the separator component powder 51 may be projected through a nozzle different from the first nozzle 31. The powder 51 of the separator component is not particularly limited, but aluminum oxide and the like can be used.
[0024] As illustrated in Figure 1, the electrode layer 2 formed by the above electrode layer formation method is intermittently provided in a predetermined pattern over a predetermined area on the surface 1A of the current collector foil 1. The electrode layer 2 can be used, for example, as an electrode in a battery 3, which is a secondary battery. For example, the battery 3 can be manufactured by appropriately covering the current collector foil 1 on which the electrode layer 2 is formed with an outer casing member, and performing processes such as injecting an electrolyte.
[0025] (1) In the electrode layer formation method according to the embodiment, a binder solution 11 is applied to the surface 1A of the current collector foil 1 to form a binder layer 11A, and active material powder 21 is projected onto the binder layer 11A to form an electrode layer 2 in which at least a portion of the active material powder 21 is in contact with the surface 1A of the current collector foil 1. With the above configuration, the projected active material powder 21 can be brought into contact with the surface 1A of the current collector foil 1 to form an active material powder layer 21A, and thus an electrode layer 2 can be formed. In addition, the gaps between the particles of the active material powder 21 can be filled by particles that are projected later, promoting contact between particles. As a result, the gaps between particles can be appropriately filled by the particles of the active material powder 21, and an electrode layer 2 with a high powder density of the active material powder 21 can be formed. Furthermore, compared to the case in which the electrode layer 2 is formed by a press roller, an electrode layer 2 with a larger thickness can be formed more easily.
[0026] (2) In this embodiment, the active material powder 21 is projected onto the binder layer 11A at a predetermined velocity. As a result, the active material powder 21, which has a predetermined kinetic energy, penetrates the binder layer 11A. Therefore, the active material powder 21 can be brought into suitable contact with the surface 1A of the current collector foil 1 to form the electrode layer 2.
[0027] (3) Furthermore, in this embodiment, the active material powder 21 is projected from the first nozzle 31 at a predetermined pressure using air or nitrogen as a carrier gas. As a result, the active material powder 21 having a predetermined kinetic energy penetrates the binder layer 11A. Therefore, the active material powder 21 can be suitably brought into contact with the surface 1A of the current collector foil 1 to form the electrode layer 2.
[0028] (4) In this embodiment, the binder solution 11 is applied to the surface 1A of the current collector foil 1 via the second nozzle 41. This allows the binder solution 11 to be applied only to the required area. As a result, the yield of materials when forming the electrode layer 2 can be improved, and manufacturing costs can be reduced.
[0029] (5) Furthermore, in the embodiment, a drying step is provided in which at least a portion of the binder layer 11A is dried after the active material powder 21 is projected. As a result, the binder layer 11A constituting the electrode layer 2 hardens in part, which suppresses flow to the surroundings, contamination, etc. Therefore, handling in subsequent processes is made easier.
[0030] (6) In addition, the embodiment includes a pre-drying step in which at least a portion of the binder layer 11A is dried before projecting the active material powder 21. This increases the viscosity of the formed binder layer 11A to a certain extent, thereby suppressing scattering and flowing into the surroundings.
[0031] (7) Furthermore, in this embodiment, the active material powder 21 includes a conductive additive 61. This ensures conductive paths between the active material powder 21, improving the battery performance when the electrode layer 2 is used as a battery 3.
[0032] (8) In this embodiment, a binder solution 11 is applied to the electrode layer 2 to form a second binder layer 12A, and a separator component powder 51 is projected onto the second binder layer 12A and dried to form a separator layer 51A. This allows the separator layer 51A to be formed thinly and uniformly by the surface tension of the second binder layer 12A. Furthermore, the separator layer 51A can be formed in a predetermined area on the electrode layer 2. For example, compared to forming the separator layer 51A with a press roller, it is possible to form a thinner and more uniform film thickness more easily, improving the performance of the separator layer 51A and reducing the cost of manufacturing the separator layer 51A.
[0033] (9) Furthermore, in the battery 3 according to the embodiment, the electrode layer 2 is formed in a predetermined area of the surface 1A of the current collector foil 1 using the electrode layer formation method described above. This makes it possible to form the electrode layer 2 only in the necessary area. Therefore, the yield of materials when forming the electrode layer 2 used in the battery 3 can be improved, and manufacturing costs can be reduced.
[0034] As described above, embodiments of the present invention have been presented, but the statements and drawings that constitute part of this disclosure should not be understood as limiting the invention. Various alternative embodiments, examples, and operational techniques will become apparent to those skilled in the art from this disclosure. [Explanation of Symbols]
[0035] 1 Current collector foil 1A surface 2 electrode layer 3 batteries 11 Binder solution 11A Binder layer 12A Second Binder Layer 21 Active material powder 31. Nozzle No. 1 41. Second nozzle 51. Powdered material of the separator component 51A Separator layer 61 Conductive additive
Claims
1. A binder solution is applied to the surface of the current collector foil to form a binder layer. The active material powder is projected onto the binder layer, A method for forming an electrode layer, wherein at least a portion of the active material powder is in contact with the surface of the current collector foil to form an electrode layer.
2. The electrode layer forming method according to claim 1, wherein the powder of the active material is projected onto the binder layer at a predetermined speed.
3. The electrode layer forming method according to claim 1 or 2, wherein the active material powder is projected from a first nozzle at a predetermined pressure using air or nitrogen as a carrier gas.
4. The electrode layer forming method according to claim 1, wherein the binder solution is applied to the surface of the current collector foil via a second nozzle.
5. The electrode layer forming method according to claim 1, further comprising a drying step of drying at least a portion of the binder layer after projecting the powder of the active material.
6. The electrode layer forming method according to claim 1, further comprising a pre-drying step of drying at least a portion of the binder layer before projecting the active material powder.
7. The electrode layer forming method according to claim 1, wherein the powder of the active material contains a conductive additive.
8. The binder solution is applied to the electrode layer to form a second binder layer. The electrode layer formation method according to claim 1, wherein powder of separator constituent material is projected onto the second binder layer and dried to form a separator layer.
9. A battery in which the electrode layer is formed in a predetermined area on the surface of the current collector foil using the electrode layer formation method described in claim 1.