Method of manufacturing non-aqueous secondary battery and method of manufacturing electrode sheet

Abstract

To provide a method of manufacturing a non-aqueous secondary battery which reduces a magnetic field to be applied, and a method of manufacturing an electrode sheet.SOLUTION: Disclosed is a method of manufacturing a non-aqueous secondary battery comprising a cathode sheet, an anode sheet and a non-aqueous electrolyte. The method of manufacturing the non-aqueous secondary battery includes: an application step of applying electrode mixture paste 31, in which an active material and a conductive material are dispersed in a solvent, from a die head 41 to an electrode substrate 30 of at least one of the cathode sheet and the anode sheet, a discharge path 43 of the die head 41 being positioned vertical to the electrode substrate 30 in the application step; an orientation step of orienting the active material in parallel with an extension direction of the discharge path 43 by applying a magnetic field to the electrode mixture paste 31 in the discharge path 43 before applying the electrode mixture paste 31 to the electrode substrate 30; and a drying step of drying the electrode mixture paste 31 which is applied to the electrode substrate 30.SELECTED DRAWING: Figure 5

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a non-aqueous secondary battery and a method for manufacturing an electrode sheet. [Background technology]

[0002] The method for manufacturing a nonaqueous secondary battery described in Patent Document 1 involves coating a current collector foil of an electrode plate with an electrode mixture paste, in which electrode materials such as an active material and a binder are dispersed in a solvent, and drying the coating to form an active material layer. In this method for manufacturing a nonaqueous secondary battery, after the electrode mixture paste is coated on the current collector foil, a magnetic field is applied to orient the active material within the electrode mixture paste. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-96386 Summary of the Invention [Problem to be solved by the invention]

[0004] Incidentally, in the method for producing a nonaqueous secondary battery described in Patent Document 1, it is necessary to apply the active material with a viscosity that allows the active material to be oriented when a magnetic field is applied. [Means for solving the problem]

[0005] A method for manufacturing a non-aqueous secondary battery that solves the above-described problems is a method for manufacturing a non-aqueous secondary battery having a positive electrode sheet, a negative electrode sheet, and a non-aqueous electrolyte, and includes: a coating step of applying an electrode composite paste, in which an active material and a conductive material are dispersed in a solvent, from a die head to at least one of the electrode base materials of the positive electrode sheet and the negative electrode sheet, wherein the discharge path of the die head is positioned perpendicular to the electrode base material; an orientation step of applying a magnetic field to the electrode composite paste in the discharge path before coating the electrode composite paste on the electrode base material, to orient the active material parallel to the extension direction of the discharge path; and a drying step of drying the electrode composite paste that has been applied to the electrode base material.

[0006] According to the above method, before applying an electrode mixture paste, in which an active material and a conductive material are dispersed in a solvent, to an electrode substrate, a magnetic field is applied in the discharge path of a die head, which applies shear force to the electrode mixture paste, thereby orienting the active material. Therefore, the magnetic field is applied when the electrode mixture paste has a low viscosity before application, eliminating the need to consider the increase in viscosity after application, and allowing the paste to be applied at a viscosity suitable for application. Consequently, the applied magnetic field can be lower than in the past.

[0007] In the method for manufacturing a nonaqueous secondary battery, it is preferable that a magnet is provided above or below the discharge path, and that the north pole and south pole of the magnet are arranged side by side in the direction in which the discharge path extends.

[0008] In the method for producing a nonaqueous secondary battery, it is preferable that in the coating step, a shielding member for shielding a magnetic field is provided between the die head and the coated electrode mixture paste. In the method for producing the nonaqueous secondary battery, the orientation step is preferably a first orientation step, and the method preferably includes a second orientation step between the coating step and the drying step, in which a magnetic field is applied to the electrode composite paste coated on the electrode base material to orient the active material perpendicular to the electrode base material.

[0009] A method for manufacturing an electrode sheet that solves the above-mentioned problems is a method for manufacturing an electrode sheet for a non-aqueous secondary battery, and includes: a coating step of applying an electrode composite paste, in which an active material and a conductive material are dispersed in a solvent, from a die head to at least one of the electrode substrates, i.e., a positive electrode sheet or a negative electrode sheet, in which the discharge path of the die head is positioned perpendicular to the electrode substrate; an orientation step of applying a magnetic field to the electrode composite paste in the discharge path before coating the electrode composite paste on the electrode substrate, to orient the active material parallel to the extension direction of the discharge path; and a drying step of drying the electrode composite paste that has been applied to the electrode substrate.

[0010] According to the above method, before applying an electrode mixture paste, in which an active material and a conductive material are dispersed in a solvent, to an electrode substrate, a magnetic field is applied in the discharge path of a die head, which applies shear force to the electrode mixture paste, thereby orienting the active material. Therefore, the magnetic field is applied when the electrode mixture paste has a low viscosity before application, eliminating the need to consider the increase in viscosity after application, and allowing the paste to be applied at a viscosity suitable for application. Consequently, the applied magnetic field can be lower than in the past. [Effects of the Invention]

[0011] According to the present invention, the applied magnetic field can be made lower than in the past. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a perspective view showing a schematic configuration of a cell battery of a nonaqueous secondary battery according to one embodiment. [Figure 2] FIG. 2 is a view showing a part of the electrode body of the embodiment in an expanded state. [Figure 3] 3 is a flowchart showing a method for manufacturing the nonaqueous secondary battery according to the embodiment. [Figure 4] 3A to 3C are diagrams illustrating a method for manufacturing an electrode sheet of the nonaqueous secondary battery according to the embodiment. [Figure 5] 3A to 3C are diagrams illustrating a method for manufacturing an electrode sheet of the nonaqueous secondary battery according to the embodiment. [Figure 6]10A to 10C are diagrams illustrating a modified example of a method for manufacturing an electrode sheet of a nonaqueous secondary battery. [Figure 7] 10A to 10C are diagrams illustrating a modified example of a method for manufacturing an electrode sheet of a nonaqueous secondary battery. [Figure 8] 1 is a graph showing the relationship between shear rate and viscosity ratio. [Figure 9] 1 is a graph showing the relationship between the time from shearing to the start of orientation and the degree of orientation. [Figure 10] 1 is a graph showing the relationship between viscosity and orientation. [Figure 11] 1 is a graph showing the relationship between magnetic flux density and orientation. DETAILED DESCRIPTION OF THE INVENTION

[0013] [Present embodiment] An embodiment of a method for manufacturing a non-aqueous secondary battery will be described below with reference to Figures 1 to 6. A lithium ion secondary battery will be described as an example of a non-aqueous secondary battery.

[0014] [Lithium-ion secondary battery 10] As shown in Figure 1, a lithium-ion secondary battery 10 is a cell battery that is combined with a plurality of lithium-ion secondary batteries 10 and sealed in a resin or metal case to form a battery pack. The battery pack is used in hybrid vehicles and electric vehicles.

[0015] The lithium-ion secondary battery 10 includes a battery case 11 and a lid 12. The battery case 11 has a rectangular parallelepiped shape with an opening on the upper side. The lid 12 seals the opening of the battery case 11. The battery case 11 and the lid 12 are made of a metal such as aluminum or an aluminum alloy. The lithium-ion secondary battery 10 forms a sealed battery container by attaching the lid 12 to the battery case 11.

[0016] The lid 12 is provided with two external terminals, a positive electrode terminal 13A and a negative electrode terminal 13B. The positive electrode external terminal 13A and the negative electrode external terminal 13B are used for charging and discharging power. An electrode assembly 20 is housed inside the battery case 11. A positive electrode side current collector 20A, which is the positive electrode side end of the electrode assembly 20, is electrically connected to the positive electrode external terminal 13A via a positive electrode side current collector 14A. A negative electrode side current collector 20B, which is the negative electrode side end of the electrode assembly 20, is electrically connected to the negative electrode external terminal 13B via a negative electrode side current collector 14B. A nonaqueous electrolyte is injected into the battery case 11 through an inlet (not shown). The shapes of the positive electrode external terminal 13A and the negative electrode external terminal 13B are not limited to those shown in FIG. 1 and may be any shape.

[0017] [Electrode body 20] As shown in Fig. 2, the electrode assembly 20 is a flat wound body obtained by winding a laminate in which a long positive electrode sheet 21 and a negative electrode sheet 24 are stacked with a separator 27 interposed therebetween. The positive electrode sheet 21, the negative electrode sheet 24, and the separator 27 are stacked so that their respective longitudinal directions coincide with the longitudinal direction D1. In the laminate before winding, the positive electrode sheet 21, the separator 27, the negative electrode sheet 24, and the separator 27 are stacked in this order. The positive electrode sheet 21 and the negative electrode sheet 24 are electrode sheets.

[0018] [Positive electrode sheet 21] The positive electrode sheet 21 includes a positive electrode current collector 22 and a positive electrode composite layer 23. The positive electrode current collector 22 is a foil-like positive electrode base material formed in a long shape. The positive electrode composite layer 23 is provided on each of two opposing surfaces of the positive electrode current collector 22. The positive electrode current collector 22 includes, at one end in the width direction D2, a positive electrode-side uncoated portion 22A where the positive electrode composite layer 23 is not formed and the positive electrode current collector 22 is exposed.

[0019] A metal foil made of aluminum or an alloy containing aluminum as a main component is used for the positive electrode current collector 22. The positive electrode current collector 22 functions as a current collector for the positive electrode. In the wound state, the positive electrode-side uncoated portion 22A of the positive electrode current collector 22 has opposing surfaces that are pressed against each other to form the positive electrode-side current collecting portion 20A.

[0020] The positive electrode mixture layer 23 is a hardened product of a liquid positive electrode mixture paste. The positive electrode mixture paste includes a positive electrode active material, a positive electrode solvent, a positive electrode conductive material, and a positive electrode binder. The positive electrode mixture layer 23 is formed by drying the positive electrode mixture paste and evaporating the positive electrode solvent. Therefore, the positive electrode mixture layer 23 includes a positive electrode active material, a positive electrode conductive material, and a positive electrode binder.

[0021] The positive electrode active material is a lithium-containing composite oxide capable of absorbing and releasing lithium ions, which are charge carriers in the lithium-ion secondary battery 10. The lithium-containing composite oxide is an oxide containing lithium and a metal element other than lithium. The metal element other than lithium is at least one selected from the group consisting of, for example, nickel, cobalt, manganese, vanadium, magnesium, molybdenum, niobium, titanium, tungsten, aluminum, and iron contained in the lithium-containing composite oxide as iron phosphate.

[0022] For example, the lithium-containing composite oxide is lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or lithium manganese oxide (LiMn2O4). For example, the lithium-containing composite oxide is a ternary lithium-containing composite oxide containing nickel, cobalt, and manganese, such as lithium nickel cobalt manganese oxide (LiNiCoMnO2). For example, the lithium-containing composite oxide is lithium iron phosphate (LiFePO4).

[0023] The positive electrode solvent is an NMP (N-methyl-2-pyrrolidone) solution, which is an example of an organic solvent. The positive electrode conductive material may be, for example, carbon black such as acetylene black or ketjen black, carbon fiber such as carbon nanotube or carbon nanofiber, or graphite. The positive electrode binder is an example of a resin component contained in the positive electrode mixture paste. Examples of the positive electrode binder include polyvinylidene fluoride (PVDF), polyvinyl alcohol (PVA), and styrene butadiene rubber (SBR).

[0024] The positive electrode sheet 21 may have an insulating layer at the boundary between the positive electrode uncoated portion 22A and the positive electrode composite layer 23. The insulating layer contains an inorganic component having insulating properties and a resin component that functions as a binder. The inorganic component is at least one selected from the group consisting of powdered boehmite, titania, and alumina. The resin component is at least one selected from the group consisting of PVDF, PVA, and acrylic.

[0025] [Negative electrode sheet 24] The negative electrode sheet 24 includes a negative electrode current collector 25 and a negative electrode composite layer 26. The negative electrode current collector 25 is a foil-like negative electrode base material formed in a long strip. The negative electrode composite layer 26 is provided on each of two opposing surfaces of the negative electrode current collector 25. The negative electrode current collector 25 includes a negative electrode-side uncoated portion 25A at one end in the width direction D2, opposite the positive electrode-side uncoated portion 22A, where the negative electrode composite layer 26 is not formed and the negative electrode current collector 25 is exposed.

[0026] A metal foil made of copper or an alloy mainly containing copper is used for the negative electrode current collector 25. The negative electrode current collector 25 functions as a current collector for the negative electrode. When the negative electrode uncoated portion 25A is wound, opposing surfaces of the negative electrode uncoated portion 25A are pressed against each other to form the negative electrode current collector 20B.

[0027] The negative electrode mixture layer 26 is a hardened product of a liquid negative electrode mixture paste. The negative electrode mixture paste includes a negative electrode active material, a lithium salt, a negative electrode solvent, a negative electrode thickener, and a negative electrode binder. The negative electrode mixture layer 26 is formed by drying the negative electrode mixture paste and evaporating the negative electrode solvent. Therefore, the negative electrode mixture layer 26 includes the negative electrode active material, the lithium salt, and further includes a negative electrode thickener and a negative electrode binder as additives. The negative electrode mixture layer 26 may further include an additive such as a conductive material.

[0028] The negative electrode active material is a material capable of absorbing and releasing lithium ions. Examples of the negative electrode active material include carbon materials such as graphite, non-graphitizable carbon, and graphitizable carbon. An example of the negative electrode solvent is water. The lithium salt can be one or more lithium compounds (lithium salts) selected from LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC4F9SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiI, and LiBOB (lithium bis(oxalato)borate). In this embodiment, LiBOB is used as the lithium salt. For example, the negative electrode thickener can be carboxymethyl cellulose (CMC), which contains a sodium salt. For example, the negative electrode binder can be the same as the positive electrode binder. For example, the negative electrode binder can be styrene-acrylic acid copolymer (SAR), which contains a sodium salt.

[0029] [Separator 27] The separator 27 prevents contact between the positive electrode sheet 21 and the negative electrode sheet 24, and also holds the nonaqueous electrolyte between the positive electrode sheet 21 and the negative electrode sheet 24. When the electrode assembly 20 is immersed in the nonaqueous electrolyte, the nonaqueous electrolyte permeates from the ends of the separator 27 in the width direction D2 toward the center.

[0030] The separator 27 is a nonwoven fabric made of polypropylene, etc. Examples of the separator 27 that can be used include porous polymer membranes such as porous polyethylene membranes, porous polyolefin membranes, and porous polyvinyl chloride membranes, and ion-conductive polymer electrolyte membranes.

[0031] [Nonaqueous electrolyte] The nonaqueous electrolyte is a composition in which a supporting salt is contained in a nonaqueous solvent. The nonaqueous solvent can be one or more materials selected from the group consisting of propylene carbonate, ethylene carbonate, diethyl carbonate, dimethyl carbonate, ethyl methyl carbonate, etc. In this embodiment, ethylene carbonate is used as the nonaqueous solvent. The supporting salt can be one or more lithium compounds (lithium salts) selected from LiPF6, LiBF4, LiClO4, LiAsF6, LiCF3SO3, LiC4F9SO3, LiN(CF3SO2)2, LiC(CF3SO2)3, LiI, etc.

[0032] [Manufacturing method] Next, a method for manufacturing the lithium ion secondary battery 10 will be described with reference to Figures 3 to 5. In the method for manufacturing the lithium ion secondary battery 10, a laminate in which a positive electrode sheet 21 and a negative electrode sheet 24 are stacked with a separator 27 interposed therebetween is wound up. The wound laminate, which forms an electrode body 20, is housed in a battery case 11. A non-aqueous electrolyte solution is then poured into the battery case 11 housing the electrode body 20, and a lid 12 is attached to the battery case 11 to seal it.

[0033] 3, the electrode sheet manufacturing method, which is part of the manufacturing method of the lithium-ion secondary battery 10, includes an unwinding step (step S1), a magnetic field orientation step (step S2), a die coating step (step S3), and an electrode plate drying step (step S4). The magnetic field orientation step (step S2) is performed before the die coating step (step S3). This manufacturing method is performed on at least one of the electrode sheets, a positive electrode sheet 21 and a negative electrode sheet 24. The die coating step is performed using a die coater 40.

[0034] [Unwinding process] As shown in FIGS. 4 and 5, in the unwinding step, the electrode base material 30 of the electrode sheet is unwound by a transport roller 50.

[0035] [Die coating process] In the coating process, an electrode mixture paste 31, in which an active material and a conductive material are dispersed in a solvent, is applied from a die head 41 to an electrode substrate 30 unwound on a conveying roller 50. The electrode mixture paste 31 that will become the positive electrode mixture layer 23 is applied to the electrode substrate 30 of the positive electrode sheet 21. The electrode mixture paste 31 that will become the negative electrode mixture layer 26 is applied to the electrode substrate 30 of the negative electrode sheet 24. The discharge path 43 of the die head 41 is positioned perpendicular to the electrode substrate 30 being conveyed by the conveying roller 50. In other words, the discharge path 43 of the die head 41 extends in the radial direction of the conveying roller 50. The viscosity of the electrode mixture paste 31 is reduced to, for example, 1000 mPa·s or less by being subjected to shear force in the discharge path 43 of the die head 41. The electrode mixture paste 31 is discharged onto the electrode substrate 30 from a die lip 42 at the tip of the die head 41.

[0036] [Magnetic field orientation process] The magnetic field orientation process is performed in the die head 41. A first magnet 45 is provided above the die head 41. A second magnet 46 is provided below the die head 41. The first magnet 45 and the second magnet 46 are provided with their north and south poles aligned in the direction in which the discharge path 43 extends. Therefore, the first magnet 45 and the second magnet 46 form a magnetic field parallel to the direction in which the discharge path 43 extends. The first magnet 45 and the second magnet 46 are permanent magnets. Therefore, as the electrode mixture paste 31 passes through the discharge path 43, it passes through the magnetic fields of the first magnet 45 and the second magnet 46, and a magnetic field is applied to the electrode mixture paste 31.

[0037] In the magnetic field orientation process, a magnetic field is applied to the electrode mixture paste 31 in the discharge path 43 before the electrode mixture paste 31 is applied to the electrode substrate 30. By applying the magnetic field parallel to the direction of extension of the discharge path 43, the active material is oriented parallel to the direction of extension of the discharge path 43. The viscosity of the electrode mixture paste 31 passing through the discharge path 43 is reduced to, for example, 1000 mPa·s or less due to shear force. This facilitates orientation of the active material, and the active material can be oriented even at a low magnetic flux density. When orienting the active material using a magnetic field, a viscosity of approximately 5000 mPa·s or less is desirable. However, because the viscosity is 1000 mPa·s or less, the required magnetic flux density can be reduced, allowing for the miniaturization of the equipment used for magnetic field orientation.

[0038] Then, the electrode mixture paste 31, in which the active material is oriented parallel to the extension direction of the discharge path 43, is applied perpendicularly to the electrode substrate 30. Therefore, the active material contained in the electrode mixture paste 31 applied to the electrode substrate 30 is vertically oriented. When the orientation of the active material is increased, the lithium ion migration resistance is reduced in the lithium ion secondary battery 10. Furthermore, lithium ion precipitation is also reduced. The lithium ion migration resistance and lithium precipitation are correlated with the input / output characteristics of the lithium ion secondary battery 10. In other words, if the lithium ion migration resistance and lithium precipitation are reduced, the input / output characteristics of the lithium ion secondary battery 10 will improve. Therefore, increasing the orientation of the active material contributes to improving the quality of the lithium ion secondary battery 10.

[0039] [Plate drying process] In the electrode plate drying process, the electrode mixture paste 31 applied to the electrode substrate 30 is dried. In the drying process, the electrode mixture paste 31 is passed between heaters and heated and dried with hot air. By drying the electrode mixture paste 31, the active material is maintained in an oriented state. After the electrode plate drying process, the electrode sheet is formed to a predetermined thickness by a press machine in the pressing process. Then, the electrode sheet is cut to a predetermined size in the cutting process.

[0040] [Effects of this embodiment] Next, the effects of this embodiment will be described. (1) Before the electrode mixture paste 31 is applied to the electrode substrate 30, a magnetic field is applied in the discharge path 43 of the die head 41, where shear force is applied to the electrode mixture paste 31, thereby orienting the active material. Therefore, the magnetic field is applied when the viscosity of the electrode mixture paste 31 is low before application, and there is no need to take into account the increase in viscosity after application, allowing application at a viscosity suitable for application. Consequently, the applied magnetic field can be lower than in the past.

[0041] (2) The first magnet 45 and the second magnet 46 are arranged with their north and south poles aligned in the direction of extension of the discharge path 43 of the die head 41. Therefore, the active material contained in the electrode composite paste 31 that is applied perpendicularly to the electrode substrate 30 is applied in a state where it is oriented perpendicularly to the electrode substrate 30.

[0042] [Other embodiments] The above embodiment can be modified as follows: The above embodiment and the following modifications can be combined with each other within the scope of technical compatibility.

[0043] In the above embodiment, as shown in FIG. 6 , the manufacturing method may include a second orientation step between the die coating step (step S3) and the electrode plate drying step (step S4) in which a magnetic field is applied to the electrode composite paste 31 applied to the electrode substrate 30 to orient the active material perpendicular to the electrode substrate 30. After die coating, a third magnet 60 is provided to generate a magnetic field perpendicular to the electrode substrate 30. In this case, the magnetic field orientation step (step S3) is the first orientation step. According to this method, the active material may not be sufficiently oriented due to coating in the first orientation step, but the active material can be reliably oriented in the second orientation step. Furthermore, since the active material has already been oriented in the first orientation step, the magnetic field can be set weaker in the second orientation step. Because magnetic fields can affect health, setting a strong magnetic field makes handling difficult. Therefore, setting a weaker magnetic field makes handling easier.

[0044] In the above embodiment, as shown in FIG. 7 , a shielding member 51 for shielding a magnetic field may be provided between the die head 41 and the coated electrode mixture paste 31 in the coating process. According to this method, when a magnetic field is applied to the discharge path 43 of the die head 41 and applied to the coated electrode mixture paste 31, the magnetic field is oriented in a direction different from that perpendicular to the electrode base material 30. This makes it possible to prevent a magnetic field in a different direction from being applied to the coated electrode mixture paste 31. Note that, when the shielding member 51 is not provided, the magnitude of the applied magnetic field can be reduced to prevent a magnetic field in a different direction from being applied to the coated electrode mixture paste 31.

[0045] In the above embodiment, the first magnet 45 and the second magnet 46 are permanent magnets. However, the first magnet 45 and the second magnet 46 may be electromagnets. In this way, when application of the magnetic field is not required, application of the magnetic field can be stopped by turning off the power supply.

[0046] In the above embodiment, the first magnet 45 is provided above the die head 41, and the second magnet 46 is provided below the die head 41. However, the first magnet 45 and the second magnet 46 may be provided inside the die head 41.

[0047] In the above embodiment, the first magnet 45 is provided above the die head 41, and the second magnet 46 is provided below the die head 41. However, only one of the first magnet 45 and the second magnet 46 may be provided.

[0048] In the above embodiment, the electrode body 20 is a wound body obtained by winding a laminate in which a positive electrode sheet 21 and a negative electrode sheet 24 are stacked with a separator 27 interposed therebetween. However, the electrode body may also be a laminate in which a plurality of positive electrode sheets 21 and a plurality of negative electrode sheets 24 are alternately stacked with a separator 27 interposed therebetween.

[0049] The lithium-ion secondary battery 10 may be installed in an automatic transport vehicle, a special-purpose vehicle for loading and unloading, an electric vehicle, a hybrid vehicle, a computer, or other electronic device, or may be part of other systems. For example, it may be installed in a moving object such as a ship or an aircraft, or it may be a power supply system that supplies power from a power plant via a substation to a building or home where a secondary battery is installed.

[0050] [Example] Next, examples of the lithium ion secondary battery 10 will be described with reference to Figures 8 to 11. Note that these examples are not limited to non-aqueous secondary batteries.

[0051] As shown in FIG. 8, the electrode mixture paste 31 has a lower viscosity ratio at shear [%] as the shear rate [1 / s] increases. The viscosity at a shear rate of 0.01 [1 / s], which is the same as before shearing, is set to 100 [%]. For example, when the shear rate in the die head 41 is 100 [1 / s], the viscosity ratio at shear decreases by approximately 99 [%]. In this way, the viscosity of the electrode mixture paste 31 can be reduced by increasing the shear rate.

[0052] 9, the longer the time [sec] from shearing to the start of magnetic field orientation in the electrode mixture paste 31, the lower the orientation of the active material. As time passes after shearing, the viscosity of the electrode mixture paste 31, which was reduced by shearing, returns to its original state. Therefore, the shorter the time from shearing to the start of magnetic field orientation in the electrode mixture paste 31, the higher the orientation of the active material can be.

[0053] 10, the higher the viscosity (mPa·s) of the electrode mixture paste 31, the lower the orientation of the active material. If the viscosity of the electrode mixture paste 31 is high, the movement of the active material is restricted. Therefore, the lower the viscosity of the electrode mixture paste 31, the higher the orientation of the active material can be.

[0054] As shown in Figure 11, the higher the magnetic flux density [T] of the electrode mixture paste 31, the higher the orientation of the active material. ○ indicates a viscosity of 2000 [mPa·s], □ indicates a viscosity of 5000 [mPa·s], and ◇ indicates a viscosity of 12000 [mPa·s]. Therefore, when it is desired to obtain the same degree of orientation, the electrode mixture paste 31 can be achieved with a lower magnetic flux density as the viscosity decreases.

[0055] As described above, by applying a magnetic field to the electrode mixture paste 31 for a short time after shearing, particularly during shearing, the viscosity of the electrode mixture paste 31 can be reduced to, for example, 1000 mPa s or less, and a magnetic field can be applied to the electrode mixture paste 31. This improves the orientation of the active material, and ultimately reduces the applied magnetic flux density. [Explanation of symbols]

[0056] 10...Lithium-ion secondary battery 11...Battery case 12...lid body 13A...Positive external terminal 13B…Negative external terminal 14A...Positive electrode side current collecting member 14B...Negative electrode side current collecting member 20...Electrode body 20A...Positive electrode current collector 20B...Negative electrode side current collecting part 21...Positive electrode sheet 22...Positive electrode current collector 22A: Uncoated area on the positive electrode side 23...Positive electrode mixture layer 24...Negative electrode sheet 25...Negative electrode current collector 25A...Negative electrode uncoated area 26...Negative electrode composite material layer 27...Separator 30...electrode base material 31...Electrode mixture paste 40...Die coater 41...Die head 42...Die Lip 43...Discharge path 45...First magnet 46...Second magnet 50...Transport roll 51...Shielding member 60...Third magnet

Claims

1. A method for manufacturing a non-aqueous secondary battery having a positive electrode sheet, a negative electrode sheet, and a non-aqueous electrolyte solution, comprising: a coating step of coating an electrode composite paste, in which an active material and a conductive material are dispersed in a solvent, onto at least one of the electrode base materials of the positive electrode sheet and the negative electrode sheet, from a die head, wherein a discharge path of the die head is positioned perpendicular to the electrode base material; an orientation step of applying a magnetic field to the electrode mixture paste in the discharge path to orient the active material parallel to the extension direction of the discharge path before applying the electrode mixture paste to the electrode base material; a drying step of drying the electrode mixture paste applied to the electrode base material. A method for manufacturing a non-aqueous secondary battery.

2. a magnet is provided above or below the discharge path; The magnet is provided with its north pole and south pole aligned in the direction in which the discharge path extends. The method for producing the nonaqueous secondary battery according to claim 1 .

3. In the coating step, a shielding member for shielding a magnetic field is provided between the die head and the electrode mixture paste after coating. The method for producing the nonaqueous secondary battery according to claim 1 or 2.

4. The orientation step is referred to as a first orientation step, Between the coating step and the drying step, a second orientation step is included in which a magnetic field is applied to the electrode mixture paste coated on the electrode substrate to orient the active material perpendicular to the electrode substrate. The method for producing the nonaqueous secondary battery according to claim 1 .

5. A method for manufacturing an electrode sheet for a non-aqueous secondary battery, comprising: a coating step of coating an electrode composite paste, in which an active material and a conductive material are dispersed in a solvent, onto at least one of an electrode base material of a positive electrode sheet and a negative electrode sheet, from a die head, the coating step being performed with a discharge path of the die head positioned perpendicular to the electrode base material; an orientation step of applying a magnetic field to the electrode mixture paste in the discharge path to orient the active material parallel to the extension direction of the discharge path before applying the electrode mixture paste to the electrode base material; a drying step of drying the electrode mixture paste applied to the electrode base material. Manufacturing method of electrode sheet.

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