Negative electrode manufacturing process and negative electrode manufacturing device

Abstract

A negative electrode manufacturing process comprises feeding a negative electrode composite material, which includes a negative electrode active material including graphite, to a metal foil serving as a current collector, and applying a magnetic field to the negative electrode active material, wherein magnetic field lines point in a direction perpendicular to a surface of the metal foil. The application of the magnetic field to the negative electrode active material comprises continuously applying the magnetic field using a plurality of magnets while the metal foil is conveyed in a conveying direction, the magnets being arranged at predetermined intervals in the conveying direction.

Description

Background of the invention 1. Field of the invention

[0001] The present invention relates to a negative electrode manufacturing method and a negative electrode manufacturing device. 2. Description of the relevant state of the art

[0002] Several technologies have been proposed for a method of manufacturing a battery, as disclosed in JP 2024 - 73970 A and WO 2012 / 124033. Summary of the invention

[0003] Graphite, used as a negative electrode active material, has a structure in which many layers, each containing continuous six-membered carbon rings, are stacked on top of each other. During charging, ions, such as lithium ions, are inserted between the layers. Typically, in graphite, the in-plane direction of the layer containing the continuous six-membered rings is represented as the (002) plane direction, and the stacking direction of the layers, each containing the continuous six-membered rings, is represented as the (110) plane direction. During charging, ions, such as lithium ions, enter between the layers in the in-plane direction, that is, along the (002) plane, from near an edge of the layer containing the continuous six-membered rings.Thus, the alignment of the (002) plane of the graphite in the direction of a positive electrode enables the entry of ions into the graphite and the diffusion of ions from the graphite to proceed effectively.

[0004] JP 2024-73970 A discloses a method for manufacturing a lithium-ion secondary battery, wherein the manufacturing process comprises feeding a negative electrode composite material containing graphite to a metal foil serving as a current collector, and applying a magnetic field with magnetic field lines pointing in a direction perpendicular to a surface of the metal foil being fed with the negative electrode composite material. The manufacturing process described in JP 2024-73970 A aligns the graphite, which corresponds to a negative electrode active material, upon application of the magnetic field. JP 2024-73970 A states that a shorter application time for the magnetic field is preferable and that the graphite is preferably sufficiently aligned within a short time of approximately 0.5 seconds.JP 2024-73970 A also specifies that the magnetic field strength when the magnetic field is applied is 1.0 T or more, preferably 1.5 T or more, and even more preferably 2.0 T or more. However, there is room for improvement in applying the magnetic field to increase the degree of graphite alignment in the negative electrode.

[0005] The present invention was made in view of the foregoing circumstances, and a main objective of it is to provide a negative electrode manufacturing process which can improve the degree of alignment of graphite which corresponds to a negative electrode active material.

[0006] That is to say, the present invention comprises the following aspects. <1> A negative electrode manufacturing process, comprising: Feeding a negative electrode composite material, which includes a negative electrode active material including graphite, to a metal foil which serves as a current collector; and Applying a magnetic field to the negative electrode active material with magnetic field lines pointing in a direction perpendicular to a surface of the metal foil, wherein Applying the magnetic field to the negative electrode active material involves continuously applying the magnetic field using a plurality of magnets while the metal foil is transported in a conveying direction, with the magnets being arranged at predetermined intervals in the conveying direction. <2> The negative electrode manufacturing process according to point <1> This also includes drying the negative electrode composite material after applying the magnetic field. <3> The negative electrode manufacturing process according to point <1> or point <2> , where the coating weight of the negative electrode composite material is 25 mg / cm² 2 or more. <4> The negative electrode manufacturing process according to one of the points <1> until <3> , where: the time required to apply the magnetic field is 0.36 seconds or more and 5.04 seconds or less; and When the magnetic field is applied, the time for the metal foil to pass through each of the magnets is 0.18 seconds. <5> Negative electrode manufacturing device, comprising: a feeding unit configured to feed a negative electrode composite material, which includes a negative electrode active material including graphite, to a metal foil serving as a current collector; and a magnetic field application unit configured to apply a magnetic field to the negative electrode active material with magnetic field lines pointing in a direction perpendicular to a surface of the metal foil, wherein The magnetic field application unit comprises a plurality of magnets configured to apply the magnetic field, the magnets being arranged at predetermined intervals in a conveying direction of the metal foil.

[0007] The present invention can improve the degree of alignment of graphite, which corresponds to a negative electrode active material. Brief description of the illustrations

[0008] Features, advantages and the technical and industrial significance of exemplary embodiments of the invention are described below with reference to the accompanying figures, in which the same symbols denote the same elements and wherein: Fig.1 is a schematic illustration showing an example of a step for applying a magnetic field in a manufacturing process of the present disclosure; Fig. 2 is an illustration showing an example of a manufacturing apparatus of the present disclosure; Fig. Figure 3 is a schematic sectional view showing one step in applying a magnetic field in a comparative example; and Fig. 4 is a diagram that shows the relationship between the magnetic field application time and the degree of alignment in examples and comparisons. Detailed description of embodiments

[0009] An embodiment according to the present disclosure is described below. It should be noted that elements not specifically mentioned in the present specification but necessary for the execution of the present disclosure (for example, the general configuration and manufacturing process of a negative electrode, which are not part of the present disclosure) can be understood by a person skilled in the art as design features based on the relevant prior art. The present disclosure can be carried out based on the details disclosed in the present specification and the general technical knowledge in the field.

[0010] Furthermore, the dimensional ratios (e.g., length, width, and thickness) in the illustrations do not reflect the actual dimensional ratios. 1. Manufacturing process

[0011] The present disclosure provides a negative electrode manufacturing process comprising a step for feeding a negative electrode composite material, which includes a negative electrode active material including graphite, to a metal foil serving as a current collector (hereinafter referred to as the negative electrode composite material feeding step), and a step for applying a magnetic field to the negative electrode active material with magnetic field lines pointing in a direction perpendicular to a surface of the metal foil (hereinafter referred to as the magnetic field application step). The step for applying the magnetic field to the negative electrode active material comprises, while the metal foil is conveyed in a conveying direction,Transport is achieved by continuously applying a magnetic field using a plurality of magnets, wherein the magnets are arranged at predetermined intervals in the conveying direction.

[0012] Each step is described below. Negative electrode composite material feed step

[0013] A negative electrode composite material delivery step corresponds to the step of delivering a negative electrode composite material, which includes a negative electrode active material including graphite, to a metal foil that serves as a current collector. The negative electrode composite material forms a negative electrode layer that contains the negative electrode active material.

[0014] The metal foil serves as the current collector of a negative electrode. Furthermore, the metal foil must not interfere with the alignment of the graphite during the subsequent magnetic field application step. Specific examples of metal foil include aluminum foil and copper foil. The metal foil can be an alloy foil, or it can contain a material other than metal.

[0015] The shape of the metal foil is not limited to any specific form and can be the same as that used in conventional negative electrode manufacturing. For example, the shape can be elongated (plate-like). The thickness of the metal foil is also not limited to any specific form.

[0016] The negative electrode composite material includes at least graphite as the negative electrode active material, but may also contain a negative electrode active material other than graphite, or graphite alone. The graphite may be a material capable of absorbing and releasing ions, such as lithium ions, and may have a boundary section that serves as an ion inlet and is aligned by applying a magnetic field. The graphite may, for example, have a layered structure in which hexagonal, plate-like crystals are stacked to form multiple layers. Examples of graphite include, in particular, natural graphite, synthetic graphite, amorphous carbon derived from natural graphite, and amorphous carbon derived from synthetic graphite. A material other than graphite, which is conventionally known, may also be used as the negative electrode active material, provided it is suitable.

[0017] The amount of graphite contained in the negative electrode composite material can be such that the total graphite content in the negative electrode layer is 80% or more by mass and 99% or less by mass, or 90% or more by mass and 97.95% or less by mass. The amount that results in the total graphite content in the negative electrode layer being 80% or more by mass means that the total graphite content in the negative electrode layer formed by removing a volatile component, such as a solvent contained in the negative electrode composite material, is 80% or more by mass. The same applies to components other than graphite and solvent.

[0018] The negative electrode composite material may contain an additional component besides the negative electrode active material, and this additional component may, for example, include a binder. Examples of binders include styrene-butadiene rubber (SBR), carboxymethylcellulose (CMC), polytetrafluoroethylene (PTFE), polyethylene (PE), polyacrylic acid (PAA), and polyvinylidene fluoride (PVdF). It should be noted that each of the materials listed above as examples of binders may also function as a thickener or other additive to the negative electrode composite material.

[0019] The amount of binder contained in the negative electrode composite material may, for example, be such that the amount of binder contained in the entire negative electrode layer is 0.4% by mass or more and 10% by mass or less, or 0.4% by mass or more and 5% by mass or less.

[0020] The negative electrode composite material can contain a conductive material as an additional component. Examples of conductive materials include carbon nanotubes (CNTs), acetylene black, carbon black, and Ketjen black. The amount of conductive material is not limited to a specific quantity and can be, for example, 0.05% or more by mass, 1% or less by mass, or 0.5% or less by mass in the entire negative electrode layer.

[0021] The negative electrode composite material may contain a solvent that disperses the aforementioned components. Examples of solvents include organic solvents such as N-methylpyrrolidone (NMP), pyrrolidone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, toluene, dimethylformamide, and dimethylacetamide. Alternatively, the solvent may be water or a mixed solvent consisting primarily of water. As a solvent other than water, an organic solvent (such as a lower alcohol or a lower ketone) that is readily miscible with water may be selected and used appropriately.

[0022] The amount of solvent contained in the negative electrode composite material is not limited to a specific quantity.

[0023] The alignment of the graphite in the negative electrode composite material typically increases as the viscosity of the negative electrode composite material decreases. However, since the alignment of the graphite is high in the manufacturing process of the present disclosure, the graphite can be sufficiently aligned without reducing the viscosity of the negative electrode composite material. Thus, the negative electrode composite material can, for example, be a slurry (paste) exhibiting a high viscosity of 100,000 mPa·s or more at a shear rate of 0.01 s⁻¹. -1 exhibits.

[0024] A method for feeding the negative electrode composite material to the metal foil is not limited to any particular method, and a general method can be used. An example of such a method is a coating process using an applicator, such as a coating nozzle. The ability to ensure sufficient graphite alignment, even when using a highly viscous negative electrode composite material—that is, a negative electrode composite material with a low solvent content—means that it is possible to achieve both a high coating weight of the negative electrode and a high degree of graphite alignment. With the manufacturing process of the present disclosure, the coating weight of the negative electrode composite material can be reduced to 25 mg / cm². 2 or more. The coating weight of the negative electrode composite material can be 200 mg / cm².2 or less, 100 mg / cm² 2 or less, or 40 mg / cm² 2 or less. Magnetic field application step

[0025] The magnetic field application step corresponds to the step of applying a magnetic field to the negative electrode active material in the negative electrode composite material, which is fed onto the metal foil (current collector) in the negative electrode composite material feeding step, wherein magnetic field lines point in a direction perpendicular to a surface of the metal foil, and to the step of continuously applying the magnetic field using a plurality of magnets while the metal foil is transported in a conveying direction, wherein the magnets are arranged at predetermined intervals in the conveying direction. By initiating the action of the magnetic field with the magnetic field lines pointing in the direction perpendicular to the surface of the metal foil, the graphite (negative electrode active material) on the metal foil is aligned such that a plane (002) between the layers becomes parallel to the magnetic field lines.

[0026] As a result of intensive research by the present inventor, it was found that the degree of alignment of the graphite on the metal foil can be improved by arranging the magnets at predetermined intervals in the conveying direction of the metal foil (hereinafter referred to simply as the conveying direction) to form a magnetic field distribution in which the magnetic fields of the adjacent magnets are continuous, as described above. In particular, (1) a case in which a magnetic field is applied by stationary arrangement of a metal foil, to which a negative electrode composite material (containing graphite) has been fed, with respect to a magnet (with respect to Fig. 3), and (2) a case in which a magnetic field is applied by conveying a metal foil, to which a negative electrode composite material (with graphite) has been fed, along a plurality of magnets arranged at predetermined intervals (see Fig.1) compared. As a result, it was shown that the degree of alignment of the graphite is higher in case (2) where the magnets are arranged at predetermined intervals, even with the same application time.

[0027] A magnetic field distribution pattern, which is formed in the magnetic field application step of the manufacturing process of the present disclosure, is described with reference to Fig. 1 described. Fig. Figure 1 is a schematic illustration showing an example of the magnetic field application step in the manufacturing process of the present disclosure.

[0028] In Fig.In the process, a negative electrode composite material 20 is fed onto a metal foil 10, which represents the current collector. The magnets that generate the magnetic field with magnetic field lines pointing perpendicular to the surface of the metal foil 10 correspond to a plurality of magnets 132A, 132B, 132C, arranged at predetermined intervals in the conveying direction of the metal foil 10. Here, the "perpendicular direction" need not be perfectly perpendicular and allows for a predetermined error. Magnet 132A corresponds to a pair of magnets (hereinafter also referred to as the magnet unit) comprising a magnet 132A1 and a magnet 132A2. Magnet 132B corresponds to a pair of magnets (magnet unit) comprising a magnet 132B1 and a magnet 132B2. The magnet 132C corresponds to a pair of magnets (magnetic unit) comprising a magnet 132C1 and a magnet 132C2.Each of the magnets 132A to 132C is arranged such that the metal foil 10 is held between the magnets of the magnet unit. Furthermore, each magnet unit is arranged such that the N-pole of one of the magnets (132A1, 132B1, 132C1) and the S-pole of the other of the magnets (132A2, 132B2, 132C2) face the metal foil 10.

[0029] The magnets 132, which are adjacent to each other, are arranged at a predetermined distance D and form a magnetic field distribution pattern in which the magnetic field distributions of the adjacent magnets 132 are continuous. In particular, each magnet 132A, 132B, 132C has a magnetic field distribution with a positive magnetic flux, which is a strong magnetic field, and a negative magnetic flux, which is a weak inverted magnetic field, as shown in Fig.Figure 1 shows that these magnets, arranged at intervals D, form the magnetic field distribution in which the magnetic fields of the adjacent magnets are continuous. With such a continuous magnetic field distribution pattern, the strong magnetic field and the weak inverse magnetic field are continuously and repeatedly applied to the graphite on the metal foil. It is considered that, as a result of the above, an acceleration acts on the graphite on the metal foil and the mobility of the graphite in the negative electrode composite material is increased. Therefore, it is considered that the method of the present disclosure makes the degree of alignment of the graphite higher than in the case in which the metal foil is arranged stationary with respect to a magnet unit 132A, as in Figure 1. Fig. 3 shown, and the magnetic field formed only by the magnet unit 132A is applied to the graphite in the negative electrode composite material.

[0030] As described above, the manufacturing process of the present disclosure can improve the degree of alignment of the graphite corresponding to the active material and, as a result, provide the negative electrode with excellent ion diffusion capability (ion conductivity).

[0031] Since the manufacturing process of the present disclosure can align the graphite in a shorter time than conventional methods, it also offers the advantage of reducing the manufacturing time of the negative electrode. Furthermore, it is possible to increase the degree of graphite alignment even when the viscosity of the negative electrode composite material is high. This makes it easy to achieve a high coating weight of the negative electrode and also to shorten the drying time of the electrode composite material. Moreover, since a high-viscosity negative electrode composite material can be used, it is also possible to prevent sagging when the negative electrode composite material is fed to the metal foil.

[0032] The number of magnets arranged in the conveying direction is not limited to any specific number, as long as there are two or more, and this number can be suitably selected according to the magnetic force of each magnet, the viscosity, and the coating weight of the negative electrode composite material on the metal foil. For example, the number of magnets can be three or more, five or more, or eight or more.

[0033] Everyone in the Fig.In the embodiment shown in Figure 1, the magnet used corresponds to the magnetic unit, which comprises the pair of magnets and is arranged such that the N pole of one of the magnets and the S pole of the other magnet face the metal foil. However, in the present disclosure, not every magnet necessarily has to correspond to the magnetic unit. A strong magnetic field can be applied using the magnetic unit described above. In the present disclosure, although the magnetic unit comprises the pair of magnets, the magnetic unit is considered a single magnet, and a magnetic unit is not considered a plurality of magnets. The magnets are arranged in the conveying direction, and a pair of magnets forming a magnetic unit is typically arranged to intersect the conveying direction.

[0034] Although in Fig.1 Each magnet unit 132 is arranged such that the S-pole faces a bottom side of the metal foil 10 and the N-pole faces the top side of the metal foil 10 (the side to which the negative electrode composite material 20 is supplied), the orientation of the S-pole and the N-pole is not limited to this mode and can be selected as required.

[0035] The type of each magnet is not limited to any particular type and can be, for example, a permanent magnet or an electromagnetic magnet.

[0036] The magnets are arranged at predetermined intervals in the conveying direction. If the magnets are arranged without any spacing, the negative magnetic field is not generated, and a sufficient magnetic field application effect cannot be achieved. On the other hand, it is considered that the magnetic field application effect does not change within a range where the distance between the magnets is greater than the length of each magnet in the conveying direction.

[0037] The distance between the magnets can be adjusted appropriately and may be, for example, 1 mm or more, 1 cm or more, or 10 cm or less.

[0038] Although the length of each magnet in the conveying direction is not limited to any specific length, an excessively long magnet results in a weak magnetic force around its midpoint. Therefore, the length of each magnet in the conveying direction can be appropriately adjusted, taking into account the magnet's magnetic force and other factors.

[0039] The strength of the magnetic field generated by each magnet can, for example, result in a maximum value of the magnetic flux density of the strong magnetic field of 0.5 T or more, 0.75 T or more, or 1.0 T or more.

[0040] Although the time required to apply the magnetic field depends on the strength of the magnetic field generated by the magnets, the time can be, for example, 0.36 seconds or more, or 5.04 seconds or less.

[0041] The time required to apply the magnetic field corresponds to the total time the metal foil needs to pass through each of the magnets. The time for the metal foil to pass through a magnet can be, for example, 0.1 seconds or more, 0.15 seconds or more, or 0.18 seconds or more.

[0042] A specific example of the magnetic field application conditions corresponds to a mode where the time to apply the magnetic field is 0.36 seconds or more and 5.04 seconds or less, and the time for the metal foil to pass through each magnet is 0.18 seconds. Drying step

[0043] The drying step corresponds to the step of drying the negative electrode composite material.

[0044] A drying process is not limited to any particular method, as long as the solvent in the negative electrode composite material can be dried and removed, and a known method can be used. Examples of drying methods include hot air drying and infrared drying. As described above, the method of the present disclosure can use the highly viscous negative electrode composite material with a small amount of solvent. Thus, it can be said that it is possible to shorten and simplify the drying step compared to conventional methods.

[0045] The drying step is usually performed after the magnetic field application step. This is because the graphite in the negative electrode composite material can no longer be aligned after the negative electrode composite material has dried. Further

[0046] The negative electrode manufacturing process of the present disclosure may, in addition to the negative electrode composite material feeding step, the magnetic field application step, and the drying step as described above, include an additional step. An example of the additional step is a rolling step for rolling the negative electrode layer obtained in the drying step. A rolling process may be selected, for example, from known methods such as roll pressing and flat plate pressing.

[0047] The negative electrode provided by the manufacturing process of the present disclosure can be used, for example, in a battery, such as a lithium-ion battery.

[0048] The battery in which the negative electrode obtained by the manufacturing process of the present disclosure is used can be a primary battery or a secondary battery, but is preferably a secondary battery. This is because the secondary battery can be repeatedly charged and discharged and is useful, for example, as a vehicle battery. The shape of the battery is not limited to any particular shape and can, for example, be a coin shape, a cylindrical shape, a square shape, a plate shape, a button shape, a flat shape, or a stacked shape.

[0049] Examples of the use of the battery with the negative electrode obtained by the manufacturing process of the present disclosure include power sources for vehicles such as a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), a battery electric vehicle (BEV), a gasoline-powered vehicle, and a diesel-powered vehicle. In particular, the battery can be used as a power source for propelling a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a battery electric vehicle (BEV). Furthermore, the battery can be used as a power source for mobile objects other than vehicles (e.g., a train, a ship, and an aircraft) and can be used as a power source for an electrical product, such as an information processing device. 2. Manufacturing device

[0050] The present disclosure provides a negative electrode manufacturing device comprising a feeding unit that feeds a negative electrode composite material, which includes a negative electrode active material including graphite, to a metal foil serving as a current collector (hereinafter referred to as the composite material feeding unit), and a magnetic field application unit that applies a magnetic field to the negative electrode active material with magnetic field lines pointing in a direction perpendicular to a surface of the metal foil. The magnetic field application unit comprises a plurality of magnets for applying the magnetic field, wherein the magnets are arranged at predetermined intervals in a conveying direction of the metal foil.

[0051] The negative electrode manufacturing device of the present disclosure is described below with reference to Fig. 2 described. Fig.Figure 2 shows an example of the negative electrode manufacturing apparatus of the present disclosure. It should be noted that, in the case of the negative electrode manufacturing apparatus of the present disclosure, the description of details that overlap with those of the manufacturing process of the present disclosure may be omitted.

[0052] In Fig. 2 comprises a negative electrode manufacturing device 100, a conveying or transport path 110, a metal foil feeding unit 112, a collecting unit 114, a composite material feeding unit 120, a magnetic field application unit 130, a drying unit 140 and a rolling unit 150.

[0053] Transport path 110 corresponds to the path for conveying or transporting the metal foil (current collector) 10. In the Fig.In the embodiment shown in Figure 2, a plurality of guide rollers 116 are arranged along the path for transporting the metal foil 10. The metal foil 10 is guided over the guide rollers 116, and a predetermined tension is exerted on the metal foil 10.

[0054] At one end of the transport path 110, the metal foil feeder 112 is provided, which feeds the metal foil 10. The metal foil feeder 112 guides the metal foil 10, which has a long or elongated shape and is wound in a roll around a core 112A, to the transport path 110 by rotating the core 112A. At one end of the transport path 110, the collecting unit 114 is provided, which collects or picks up the metal foil 10. The collecting unit 114 winds the metal foil 10, which has undergone a predetermined process in the transport path 110, onto a core 114A.

[0055] The composite material feeding unit 120, the magnetic field application unit 130, the drying unit 140 and the rolling unit 150 are arranged in series on the transport path 110.

[0056] The composite material feed unit 120 feeds the negative electrode composite material 20, which contains the negative electrode active material including graphite, to the metal foil 10, which serves as the current collector. In the Fig.In the embodiment shown in Figure 2, the composite material feeding unit 120 is a coating nozzle coating machine that applies the negative electrode composite material 20 to the metal foil 10, which has an elongated shape in the longitudinal direction of the metal foil 10. In the composite material feeding unit 120, the negative electrode composite material 20, stored in a tank 122, is drawn in by a pump 124 and fed to a nozzle 126. The metal foil 10 is then guided through a gap between the backup roller 128 and the nozzle 126 while being transported by the rotation of a backup roller 128, and a coating of the negative electrode composite material 20 is formed on the surface of the metal foil 10 by the nozzle 126.

[0057] The magnetic field application unit 130 applies the magnetic field to the negative electrode active material in the negative electrode composite material 20, which is fed onto the metal foil 10 by the composite material feed unit 120. The magnetic field lines point in a direction perpendicular to the surface of the metal foil 10. The magnets 132 for applying the magnetic field are arranged at predetermined intervals in the conveying direction of the metal foil 10.

[0058] In the Fig. In the embodiment shown in Figure 2, the magnets 132A, 132B, 132C are arranged at predetermined intervals in the conveying direction of the metal foil 10. As shown in Figure 2. Fig.As shown in Figure 1, each of the magnets 132A to 132C corresponds to a magnet unit comprising a pair of magnets, arranged such that the metal foil 10 is held between the magnets of the magnet unit. Furthermore, each magnet unit is arranged such that the N pole of one of the magnets (132A1, 132B1, 132C1) and the S pole of the other magnet (132A2, 132B2, 132C2) face the metal foil 10. The magnets 132A to 132C continuously apply the magnetic field to the graphite (negative electrode active material) on the metal foil 10 transported in transport path 110, with the magnetic field lines pointing in the direction perpendicular to the surface of the metal foil 10.

[0059] The metal foil 10, onto which the magnetic field is applied by the magnetic field application unit 130, is transported along the transport path 110 to the drying unit 140. In the drying unit 140, the negative electrode composite material 20 on the metal foil 10 is dried to obtain a negative electrode layer 30. The metal foil 10 with the negative electrode layer 30 is transported along the transport path 110 to the rolling unit 150. In the rolling unit 150, the negative electrode layer 30 is rolled (pressed). In the present embodiment, which is described in Fig. As shown in 2, a rolling press machine is used. Examples 1 to 7

[0060] Synthetic graphite (negative electrode active material), CMC (thickening agent), SBR (binder), and a CNT paste (conductive material) were mixed and dispersed using a planetary mixer to produce a negative electrode composite material (paste). The composition of the negative electrode composite material is synthetic graphite / CMC / SBR / CNT paste = 97.95 / 0.4 / 1.6 / 0.05 by mass. The viscosity of the resulting negative electrode composite material is 212,530 mPa·s at a shear rate of 0.01 s⁻¹. -1 .

[0061] The negative electrode composite material was applied to a copper foil, corresponding to a current collector, using an applicator. The coating quantity corresponds to a coating weight of 27.8 mg / cm². 2 on one page.

[0062] Next, as in Fig.Figure 1 shows the Cu foil with the negative electrode composite material being conveyed between magnets of a plurality of magnet units arranged at predetermined intervals in the conveying direction of the Cu foil, and a magnetic field being continuously applied to the graphite in the negative electrode composite material.

[0063] Each magnet unit was arranged so that the S-pole of one magnet and the N-pole of the other magnet faced the surfaces of the copper foil. Each magnet unit has a length of 50 mm in the conveying direction and a maximum magnetic flux density of 1 T in the strong magnetic field and a magnetic field distribution as shown in Fig. 1 shown, on. As in Fig. As shown in Figure 1, the magnet units were arranged next to each other at intervals in the conveying direction, so that the magnetic fields of the adjacent magnet units are continuous.

[0064] The number of magnet units in each example is shown in Table 1. The copper foil was transported such that it passed between the magnets of each magnet unit in 0.18 seconds. The magnetic field application time given in Table 1 is calculated as the number of magnet units × 0.18 (s).

[0065] After applying the magnetic field, the negative electrode composite material was dried. X-ray diffraction (XRD) was performed on the dried negative electrode, and the peak intensities of the 110 and 002 planes were measured. The relative ratio of the peak intensity of the 110 plane to the peak intensity of the 002 plane (110 / 002) was calculated as the degree of alignment. The results are shown in Table 1 and Fig. 4 shown.

[0066] Furthermore, the negative electrode density was increased to 1.25 g / cm³ by roller pressing. 3 brought. Comparative example 1

[0067] The fabrication of the negative electrode and the XRD measurement were performed in the same way as in the examples, except that the application of the magnetic field was omitted. The degree of alignment of the negative electrode is shown in Table 1 and Fig. 4 shown. Comparative examples 2 to 4

[0068] The fabrication of the negative electrode and the XRD measurement were performed in the same manner as in the examples, except that the copper foil with the negative electrode composite material was positioned stationary between the magnets of a magnet unit for a predetermined time, as in Fig. Figure 3 shows the magnetic field being applied to the graphite in the negative electrode composite material. The magnetic field application time is given in Table 1, and the degree of alignment of the negative electrode is shown in Table 1 and Fig. 4 shown. Table 1 Number of magnetic units Magnetic field application time (s) Alignment degree (110 / 002) Example 1 2 0,36 0,0198 Example 2 4 0,72 0,0298 Example 3 6 1,08 0,0363 Example 4 8 1,44 0,0451 Example 5 10 1,8 0,0478 Example 6 11 1,98 0,0470 Example 7 28 5,04 0,0729 Comparative example 1 - - 0,0074 Comparative example 2 1 1,8 0,0339 Comparative example 3 1 3 0,0509 Comparative example 4 1 5 0,0660

[0069] As shown in Table 1 and Fig. As shown in Figure 4, the examples exhibit a higher degree of alignment than the comparison examples, even with the same magnetic field application time. This confirms that the method of the present disclosure can shorten the magnetic field application time. Furthermore, it was found that the effect of improving the degree of alignment can also be maintained when using a highly viscous negative electrode composite material with a viscosity of 100,000 mPa·s or more at a shear rate of 0.01 s⁻¹. -1 is used. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] JP 2024 - 73970 A [0002, 0004] WO 2012 / 124033

[0002]

Claims

[1] Negative electrode manufacturing process comprising: Feeding a negative electrode composite material, which includes a negative electrode active material including graphite, to a metal foil which serves as a current collector; and Applying a magnetic field to the negative electrode active material with magnetic field lines pointing in a direction perpendicular to a surface of the metal foil, wherein Applying the magnetic field to the negative electrode active material involves continuously applying the magnetic field using a plurality of magnets while the metal foil is transported in a conveying direction, with the magnets being arranged at predetermined intervals in the conveying direction. [2] Negative electrode manufacturing method according to claim 1, further comprising drying the negative electrode composite material after applying the magnetic field. [3] Negative electrode manufacturing method according to claim 1, wherein the coating weight of the negative electrode composite material is 25 mg / cm² 2 or more. [4] Negative electrode manufacturing method according to claim 1, wherein: the time required to apply the magnetic field is 0.36 seconds or more and 5.04 seconds or less; and When the magnetic field is applied, the time for the metal foil to pass through each of the magnets is 0.18 seconds. [5] Negative electrode manufacturing device comprising: a feeding unit configured to feed a negative electrode composite material, which includes a negative electrode active material including graphite, to a metal foil serving as a current collector; and a magnetic field application unit configured to apply a magnetic field to the negative electrode active material with magnetic field lines pointing in a direction perpendicular to a surface of the metal foil, wherein The magnetic field application unit comprises a plurality of magnets configured to apply the magnetic field, the magnets being arranged at predetermined intervals in a conveying direction of the metal foil.

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