Method for manufacturing electrodes for lithium-ion secondary battery

Abstract

To prevent an electrode composition from entering or falling off during electrode production, and make it possible to obtain an electrode composition layer with uniform thickness.SOLUTION: A method for manufacturing an electrodes for a lithium-ion secondary battery according to an embodiment of the present invention includes: a placing step of placing a frame member 101 having a first opening 101a on a surface of a substrate 100; an arranging step of arranging a spacer 103 on the frame member 101; a masking step of laminating a mask layer 102 having a second opening 102a on the frame member 101 so as to fill a gap between the frame member 101 and the mask layer 102 with the spacer 103; and a supplying step of supplying an electrode composition 120 containing an electrode active material into a recess 110 defined by the mask layer 102.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a method for manufacturing an electrode for a lithium ion secondary battery. [Background technology]

[0002] Recently, lithium ion secondary batteries have been attracting attention as high-capacity, small, and lightweight batteries. A typical lithium ion battery is configured by stacking a plurality of unit cells, each of which is made up of a laminate of a positive electrode collector, a positive electrode active material layer, a separator, a negative electrode collector, and a negative electrode active material layer, to form a battery pack, and then sealing the battery pack with a battery exterior material, as in Patent Document 1, for example. In a lithium ion secondary battery, a positive electrode is configured by the positive electrode collector and the positive electrode active material layer, and a negative electrode is configured by the negative electrode collector and the negative electrode active material layer, and these are used as electrodes.

[0003] For producing an electrode for a lithium ion secondary battery, a method is known in which a mask having an opening in a region where an electrode composition layer is to be formed is placed on a sheet-like substrate, an electrode composition is applied onto the mask including inside the opening, and the mask and any unnecessary electrode composition thereon are removed to leave the electrode composition only in the region where the electrode composition is to be formed on the substrate, thereby forming an electrode composition layer, as described in Patent Document 1, for example. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2021-027043 Summary of the Invention [Problem to be solved by the invention]

[0005] When manufacturing an electrode for a lithium ion secondary battery, the electrode composition may penetrate into the mask when the electrode composition is applied, or part of the electrode composition may scatter and fall onto the electrode composition layer or around the electrode composition layer when the electrode composition is removed together with the mask. Such penetration or fall of the electrode composition causes poor definition of the coating range of the electrode composition. In addition, there is a problem that the thickness of the electrode composition layer becomes non-uniform even when the applied electrode composition is pressed.

[0006] An object of the present invention is to provide a method for producing an electrode for a lithium ion secondary battery, which is capable of preventing intrusion or falling of an electrode composition during electrode production and capable of obtaining an electrode composition layer with a uniform thickness. [Means for solving the problem]

[0007] As a result of extensive research based on the above findings, the present inventors have arrived at the following aspects of the invention. a mounting step of mounting a frame member having a first opening on a surface of the base material; a placement step of placing a spacer on the frame member; a masking step of laminating a mask layer having a second opening on the frame member so as to fill a gap between the frame member and the mask layer with the spacer; a supplying step of supplying an electrode composition containing an electrode active material into the recess defined by the mask layer; having A method for manufacturing electrodes for lithium-ion secondary batteries. Effect of the Invention

[0008] According to the method for producing an electrode for a lithium ion secondary battery according to the present invention, it is possible to prevent the electrode composition from entering or falling off during the production of the electrode, and to obtain an electrode composition layer with a uniform thickness. [Brief description of the drawings]

[0009] [Figure 1] 1 is a schematic cross-sectional view showing a secondary battery module according to an embodiment of the present invention. [Diagram 2]FIG. 2 is a flow chart showing the steps of a method for producing an electrode for a lithium ion secondary battery according to the present embodiment. [Diagram 3] 5A to 5C are schematic diagrams illustrating an example of a frame member arrangement step in the manufacturing method of an electrode for a lithium ion secondary battery according to the present embodiment. [Figure 4] 3 is a schematic diagram showing an example of a mask layer used in a masking step in the method for producing an electrode for a lithium ion secondary battery according to the present embodiment. FIG. [Diagram 5] 5A to 5C are schematic diagrams showing an example of a masking step in the method for producing an electrode for a lithium ion secondary battery according to the present embodiment. [Figure 6] 5A to 5C are schematic diagrams showing other examples of mask layers used in the masking step in the method for producing an electrode for a lithium ion secondary battery according to the present embodiment. [Figure 7] 5A to 5C are schematic diagrams illustrating an example of a supplying step in the method for producing an electrode for a lithium ion secondary battery according to the present embodiment. [Figure 8] 5A to 5C are schematic diagrams illustrating an example of a pressurizing step in the method for producing an electrode for a lithium ion secondary battery according to the present embodiment. [Figure 9] 5A to 5C are schematic diagrams illustrating an example of a peeling step in the method for producing an electrode for a lithium ion secondary battery according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, specific embodiments of the method for producing an electrode for a lithium ion secondary battery according to the present invention will be described in detail with reference to the drawings.

[0011] (Structure of lithium-ion secondary battery) In describing the present embodiment, first, the configuration of a secondary battery module of a lithium ion secondary battery including electrodes manufactured according to the present embodiment will be described. Fig. 1 is a schematic cross-sectional view showing a secondary battery module according to a first embodiment.

[0012] The secondary battery module 1 is configured as a battery cell 20 consisting of a flat-plate laminated battery (single cell) in which a negative electrode 2 consisting of a negative electrode current collector 11 and a negative electrode active material layer 12 and a positive electrode 3 consisting of a positive electrode active material layer 14 and a positive electrode current collector 15 are laminated via a separator 13. That is, the battery cell 20 constituting the secondary battery module 1 is formed in a substantially rectangular flat plate shape as a whole by stacking the negative electrode current collector 11, the negative electrode active material layer 12, the separator 13, the positive electrode active material layer 14, and the positive electrode current collector 15 in an upward direction.

[0013] The secondary battery module 1 further includes a frame-shaped seal material 9 disposed on the periphery of the battery cell 20. The seal material 9 supports the separator 13 by embedding the end of the separator 13, and the seal material 9 fixes the positive electrode current collector 15 and the negative electrode current collector 11 to the upper and lower surfaces of the seal material 9 in surface contact with each other. The peripheral portions of the negative electrode current collector 11, the positive electrode current collector 15, and the separator 13 are fixed via the seal material 9, so that the negative electrode active material layer 12 and the positive electrode active material layer 14 can be tightly sealed without leaking to the outside. The seal material 9 can also determine the positional relationship between the negative electrode current collector 11, the separator 13, and the positive electrode current collector 15. The gap between the negative electrode current collector 11 and the separator 13, and the gap between the separator 13 and the positive electrode current collector 15 are adjusted in advance according to the capacity of the battery, and the negative electrode current collector 11, the separator 13, and the positive electrode current collector 15 can be fixed using the sealing material 9 so as to maintain this adjusted gap.

[0014] A negative electrode-side current supply layer 10 as a conductive layer is laminated in a planar shape on the lower side of the negative electrode current collector 11, and a positive electrode-side current extraction layer 16 as a conductive layer is laminated in a planar shape on the upper side of the positive electrode current collector 15. Conductive parts 7 and 8, which are locations to which current is supplied, are formed on the negative electrode-side current supply layer 10 and the positive electrode-side current extraction layer 16, respectively.

[0015] The secondary battery module 1 may be provided with an exterior film (not shown) that covers the battery cells 20, the negative electrode-side current supply layer 10, and the positive electrode-side current extraction layer 16. The exterior film may be made of, for example, an insulating material, and may be made of a known material used in batteries, and is preferably a laminate film. As the laminate film, a three-layer laminate film having a nylon film on the outside, an aluminum foil in the center, and an adhesive layer such as modified polypropylene on the inside can be preferably used.

[0016] The secondary battery module 1 to which the present invention is applied is not limited to the case where the battery cells 20 of the lithium ion secondary battery are constituted by single cells. For example, a plurality of battery cells 20 may be stacked and connected to form an assembled battery.

[0017] In such a battery pack, a plurality of battery cells 20 may be connected in series to freely supply current via the conductive part 8 connected to the positive electrode side current extraction layer 16 of the uppermost battery cell 20 and the conductive part 7 connected to the negative electrode side current supply layer 10 of the lowermost battery cell 20. In such a case, the battery cells 20 are stacked so that the lower surface of the negative electrode side current supply layer 10 and the upper surface of the positive electrode side current extraction layer 16 of the battery cells 20 to be connected to each other are adjacent to each other. Furthermore, when forming such a battery pack, a plurality of battery cells 20 may be connected in parallel, or a combination of series connection and parallel connection may be used. By forming such a battery pack, a high capacity and a high output can be obtained. In addition, a current may be freely supplied independently from the conductive parts 7 and 8 connected to the negative electrode side current supply layer 10 and the positive electrode side current extraction layer 16 of each battery cell 20, respectively.

[0018] Preferred embodiments of each of the constituent materials that make up the battery cell 20 will be described below.

[0019] The positive electrode active material layer contains a positive electrode active material as an electrode composition. The positive electrode active material may be a composite oxide of lithium and a transition metal {composite oxides containing one type of transition metal element (e.g., LiCoO2, LiNiO2, LiAlMnO4, LiMnO2, and LiMn2O4), composite oxides containing two types of transition metal elements (e.g., LiFeMnO4, LiNi 1-x Co x O2, LiMn 1-y Co y O2, LiNi 1 / 3 Co 1 / 3 Al 1 / 3 O2 and LiNi 0.8 Co 0.15 Al 0.05 O2) and composite oxides containing three or more transition metal elements [e.g. LiM a M' b M" c O2(M, M' and M" are different transition metal elements and satisfy a+b+c=1. For example, LiNi 1 / 3 Mn 1 / 3 Co 1 / 3 Examples of the conductive polymer include lithium-containing transition metal phosphates (for example, LiFePO4, LiCoPO4, LiMnPO4, and LiNiPO4), transition metal oxides (for example, MnO2 and V2O5), transition metal sulfides (for example, MoS2 and TiS2), and conductive polymers (for example, polyaniline, polypyrrole, polythiophene, polyacetylene, poly-p-phenylene, and polyvinylcarbazole), and two or more of these may be used in combination. The lithium-containing transition metal phosphate may have some of the transition metal sites substituted with other transition metals.

[0020] In this embodiment, the positive electrode active material is preferably a coated positive electrode active material coated with a conductive assistant and a coating resin. When the positive electrode active material is covered with a coating resin, the volume change of the electrode is mitigated, and the expansion of the electrode can be suppressed.

[0021] Examples of the conductive additive include metal-based conductive additives [aluminum, stainless steel (SUS), silver, gold, copper, titanium, etc.], carbon-based conductive additives [graphite and carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black, etc.)], and mixtures thereof. These conductive assistants may be used alone or in combination of two or more kinds, and may also be used as alloys or metal oxides thereof.

[0022] Among these, from the viewpoint of electrical stability, aluminum, stainless steel, silver, gold, copper, titanium, carbon-based conductive assistants, and mixtures thereof are more preferable, silver, gold, aluminum, stainless steel, and carbon-based conductive assistants are even more preferable, and carbon-based conductive assistants are particularly preferable. Furthermore, these conductive assistants may be obtained by coating the particle-based ceramic material or resin material with a conductive material (preferably a metal one of the conductive assistants described above) by plating or the like.

[0023] The shape (form) of the conductive additive is not limited to a particulate form, and may be a form other than a particulate form, and may be a form that is in practical use as a so-called filler-based conductive additive, such as carbon nanofibers or carbon nanotubes.

[0024] The ratio of the coating resin to the conductive assistant is not particularly limited, but from the viewpoint of the internal resistance of the battery, etc., the weight ratio of the coating resin (resin solid content weight):conductive assistant is preferably 1:0.01 to 1:50, and more preferably 1:0.2 to 1:3.0.

[0025] As the coating resin, for example, a non-aqueous secondary battery active material coating resin obtained by polymerizing a monomer composition containing at least one crosslinking agent (b) selected from the group consisting of an ester compound (a11) of a monohydric aliphatic alcohol having 4 to 12 carbon atoms and (meth)acrylic acid, (meth)acrylic acid (a12), a compound (b1) having two or more groups capable of reacting with the carboxyl group of (meth)acrylic acid (a12), a compound (b2) having two or more radically polymerizable groups, and a compound (b3) having one or more groups capable of reacting with the carboxyl group of (meth)acrylic acid (a12) and one or more radically polymerizable groups, can be suitably used. In this non-aqueous secondary battery active material coating resin, the weight ratio of the ester compound (a11) to the (meth)acrylic acid (a12) [ester compound (a11) / (meth)acrylic acid (a12)] is preferably 10 / 90 to 90 / 10.

[0026] The positive electrode active material layer may contain a conductive assistant other than the conductive assistant contained in the coated positive electrode active material. As the conductive assistant, the same conductive assistant as that contained in the coated positive electrode active material described above can be suitably used.

[0027] The positive electrode active material layer preferably contains a positive electrode active material and is a non-binding material that does not contain a binder that binds the positive electrode active material together. Here, non-bound material means that the positive electrode active material is not fixed in position by a binding material (also called a binder), and the positive electrode active materials are not irreversibly fixed to each other or to the current collector.

[0028] The positive electrode active material layer may contain an adhesive resin. As the adhesive resin, for example, a resin in which a small amount of an organic solvent is mixed with a non-aqueous secondary battery active material coating resin described in JP 2017-54703 A to adjust its glass transition temperature to room temperature or lower, and a resin described as an adhesive in JP 10-255805 A can be suitably used.

[0029] The adhesive resin refers to a resin that does not solidify even when the solvent component is evaporated and dried, and has adhesiveness (the property of adhering by applying slight pressure without using water, solvent, heat, etc.) On the other hand, the solution-drying type electrode binder used as a binding material refers to a material that dries and solidifies by evaporating the solvent component, thereby firmly adhering and fixing active materials together. Therefore, the solution drying type electrode binder (binding material) and the adhesive resin are different materials.

[0030] The thickness of the positive electrode active material layer is not particularly limited, but from the viewpoint of battery performance, it is preferably 250 μm to 600 μm, and more preferably 350 μm to 500 μm.

[0031] The negative electrode active material layer contains a negative electrode active material as an electrode composition. As the negative electrode active material, known negative electrode active materials for lithium ion batteries can be used, and examples of the negative electrode active material include carbon-based materials [graphite, non-graphitizable carbon, amorphous carbon, resin baked bodies (e.g., phenolic resins and furan resins baked and carbonized, etc.), cokes (e.g., pitch coke, needle coke, petroleum coke, etc.), and carbon fibers, etc.], silicon-based materials [silicon, silicon oxide (SiOx), silicon-carbon composites (carbon particles whose surfaces are coated with silicon and / or silicon carbide, silicon particles or silicon oxide particles whose surfaces are coated with carbon and / or silicon carbide, silicon carbide, etc.)], and silicon-based materials [silicon, silicon oxide (SiOx), silicon-carbon composites (carbon particles whose surfaces are coated with silicon and / or silicon carbide, silicon particles or silicon oxide particles whose surfaces are coated with carbon and / or silicon carbide, silicon carbide, etc.], and silicon-based materials [silicon, silicon oxide (SiOx), silicon-carbon composites (carbon particles whose surfaces are coated with silicon and / or silicon carbide, silicon carbide, etc.)] ... oxide (SiOx), silicon oxide (SiOx), silicon oxide Examples of the conductive material include silicon alloys (silicon-aluminum alloy, silicon-lithium alloy, silicon-nickel alloy, silicon-iron alloy, silicon-titanium alloy, silicon-manganese alloy, silicon-copper alloy, silicon-tin alloy, etc.), conductive polymers (for example, polyacetylene and polypyrrole), metals (tin, aluminum, zirconium, titanium, etc.), metal oxides (titanium oxide and lithium-titanium oxide, etc.) and metal alloys (for example, lithium-tin alloy, lithium-aluminum alloy, lithium-aluminum-manganese alloy, etc.), and mixtures of these with carbon-based materials.

[0032] In this embodiment, the negative electrode active material is preferably a coated negative electrode active material coated with a conductive assistant and a coating resin similar to the coated positive electrode active material described above. As the conductive assistant and the coating resin, the same conductive assistant and coating resin as those in the coated positive electrode active material described above can be suitably used.

[0033] The negative electrode active material layer may contain a conductive assistant other than the conductive assistant contained in the coated negative electrode active material. As the conductive assistant, the same conductive assistant as the conductive assistant contained in the coated positive electrode active material described above can be suitably used.

[0034] The negative electrode active material layer is preferably a non-binding material that does not contain a binder that binds the negative electrode active materials together, similar to the positive electrode active material layer, and may contain an adhesive resin, similar to the positive electrode active material layer.

[0035] The thickness of the negative electrode active material layer is not particularly limited, but from the viewpoint of battery performance, it is preferably 380 μm to 780 μm, and more preferably 480 μm to 680 μm.

[0036] The positive electrode current collector and the negative electrode current collector may be metal current collectors, but are preferably flexible resin current collectors made of, for example, a conductive polymer material. The shape of the resin collector is not particularly limited, and may be a sheet-like collector made of a conductive polymer material, or a deposition layer made of fine particles made of a conductive polymer material. The thickness of the resin current collector is not particularly limited, but is preferably 50 μm to 500 μm.

[0037] The conductive polymer material constituting the resin collector may be, for example, a conductive polymer or a resin to which a conductive agent has been added as necessary. As the conductive agent constituting the conductive polymer material, the same conductive assistant as that contained in the coated positive electrode active material described above can be suitably used.

[0038] Examples of resins that constitute the conductive polymer material include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polycycloolefin (PCO), polyethylene terephthalate (PET), polyethernitrile (PEN), polytetrafluoroethylene (PTFE), styrene butadiene rubber (SBR), polyacrylonitrile (PAN), polymethyl acrylate (PMA), polymethyl methacrylate (PMMA), polyvinylidene fluoride (PVdF), epoxy resin, silicone resin, and mixtures thereof. From the viewpoint of electrical stability, polyethylene (PE), polypropylene (PP), polymethylpentene (PMP) and polycycloolefin (PCO) are preferred, and polyethylene (PE), polypropylene (PP) and polymethylpentene (PMP) are more preferred.

[0039] Examples of the separator include known separators for lithium ion batteries, such as porous films made of polyethylene or polypropylene, laminated films of porous polyethylene film and porous polypropylene, nonwoven fabrics made of synthetic fibers (polyester fibers, aramid fibers, etc.) or glass fibers, and those having ceramic particles such as silica, alumina, titania, etc. attached to their surfaces.

[0040] In this embodiment, the electrode composition may be a so-called wet powder containing an electrode active material and an electrolyte for the positive electrode active material layer and the negative electrode active material layer. Instead of a wet powder using a liquid electrolyte, it is also possible to use a so-called dry powder containing, for example, an electrode active material and a solid electrolyte. In this case, a separator is not required in the battery cell 20.

[0041] As the electrolytic solution, a known electrolytic solution containing an electrolyte and a non-aqueous solvent, which is used in the production of known lithium ion batteries, can be used. As the electrolyte, those used in known electrolytic solutions can be used, for example, lithium salts of inorganic acids such as LiN(FSO2)2, LiPF6, LiBF4, LiSbF6, LiAsF6, and LiClO4, and lithium salts of organic acids such as LiN(CF3SO2)2, LiN(C2F5SO2)2, and LiC(CF3SO2)3, etc. Among these, imide-based electrolytes [LiN(FSO2)2, LiN(CF3SO2)2, LiN(C2F5SO2)2, etc.] and LiPF6 are preferred from the viewpoint of battery output and charge / discharge cycle characteristics.

[0042] As the non-aqueous solvent, those used in known electrolytic solutions can be used, such as lactone compounds, cyclic or chain carbonates, chain carboxylates, cyclic or chain ethers, phosphates, nitrile compounds, amide compounds, sulfones, sulfolane, and mixtures thereof.

[0043] The electrolyte concentration of the electrolytic solution is preferably 15 mol / L to 5 mol / L, more preferably 1.5 mol / L to 4 mol / L, and further preferably 2 mol / L to 3 mol / L. If the electrolyte concentration of the electrolytic solution is less than 1 mol / L, the battery may not exhibit sufficient input / output characteristics, whereas if it exceeds 5 mol / L, the electrolyte may precipitate. The electrolyte concentration of the electrolytic solution can be confirmed by extracting the electrolytic solution constituting the lithium ion battery electrode or the lithium ion battery without using a solvent or the like and measuring the concentration.

[0044] (Electrode manufacturing method) Hereinafter, a method for manufacturing electrodes (positive and negative electrodes) of a lithium ion secondary battery will be described. In this embodiment, a manufacturing method in which a plurality of electrodes are successively formed on a long sheet-like substrate is exemplified. However, the method is not limited to this method, and it is also possible to adopt a so-called batch method in which electrodes are formed one by one on each substrate.

[0045] FIG. 2 is a flow chart showing the process steps of the method for producing an electrode for a lithium ion secondary battery according to this embodiment. The manufacturing method of electrodes (positive and negative electrodes) according to this embodiment includes a frame member arrangement step S1 for arranging a frame member having a first opening on a substrate, a masking step S2 for arranging a mask layer having a second opening on the frame member, a supplying step S3 for supplying an electrode composition into a recess defined by the second opening of the mask layer, a mask removing step S4 for removing the mask layer, a pressurizing step S5 for pressurizing the electrode composition present inside the frame member, and a cutting step S6 for cutting out the electrodes. When the electrodes are manufactured by the above-mentioned batch method, for example, the cutting step S6 is not necessary.

[0046] (Frame member placement process S1) 3 shows the state in which the frame members are arranged in the frame member arrangement step S1, where (a) is a plan view and (b) is a cross-sectional view taken along the dashed line II' in (a). In the frame member arrangement step S1, a plurality of frame members 101 are arranged continuously on the substrate 100. FIG. 3(a) illustrates three frame members 101 arranged continuously. The frame member 101 has a first opening 101a having the same size as the electrode size, and in the example of FIG. 1, it becomes the frame member 9 of the battery cell 20. When the frame members 101 are arranged on the substrate 100, the first opening 101a of each frame member 101 exposes the portion of the substrate 100 where the electrode composition layer is to be formed. Here, the frame members 101 are arranged continuously means that the adjacent frame members 101 are arranged with their sides in contact with each other. It is also possible to arrange the adjacent frame members 101 at a distance from each other so that their sides face each other.

[0047] In this embodiment, a long sheet-like current collector is used as the substrate 100. In this case, a long film of, for example, a resin current collector is used as the current collectors (positive electrode current collector and negative electrode current collector) of the above-mentioned electrodes. A long film of a separator may be used instead of the current collector. In addition, for example, a transfer film may be used as the substrate 100, and an active material layer formed on the transfer film may be transferred onto the current collector.

[0048] When manufacturing an electrode, by forming an electrode composition layer using a frame member 101 that serves as a sealing material for the battery cell, it is possible to omit the process of removing the frame member after forming the electrode composition layer and then repositioning the sealing material for the battery cell.

[0049] (Masking process S2) The mask layer used in the masking step S2 is shown in Fig. 4, where (a) is a plan view and (b) is a cross-sectional view taken along the dashed line II' in (a). The mask layer 102 has a second opening 102a that is the same shape as the first opening 101a of the frame member 101 in a plan view and is smaller than the first opening 101a by the thickness of the four sides of the mask layer. The second opening 102a is formed in a shape in which its inner peripheral edge portion 102b is bent downward. For example, a spacer 103 made of a flexible material and having a predetermined thickness is attached to the back surface of the mask layer 102 in the peripheral portion 102c of the second opening 102a.

[0050] The mask layer 102 is preferably made of a material that does not easily generate static electricity on its surface, such as a metal material such as spring steel. Since static electricity is not easily generated on the surface of the mask layer 102, a part of the supplied electrode composition is not easily attached to the surface of the mask layer 102, and the occurrence of contamination (inclusion of foreign matter) is suppressed. The spacer 103 is preferably flexible enough to appropriately fill the gap between the exposed part of the spacer 103 and the upper surface of the frame member 101, which is the part that is in close contact with the frame member 101. Specifically, the spacer 103 is preferably made of silicone rubber, polyimide film, or the like. The thickness of the spacer 103 is appropriately determined in consideration of ensuring the thickness of the electrode composition layer required when the electrode composition layer is compressed in the pressurizing step S5, as described below.

[0051] The spacers 103 may be disposed on the rear surface of the mask layer 102 from the peripheral portion 102c to the inner periphery portion 102b.

[0052] 5 shows the state in which the mask layer 102 is disposed in the masking step S2, where (a) is a plan view, (b) is a cross-sectional view taken along dashed line II' in (a), and (c) is a cross-sectional view taken along dashed line II-II' in (a). In the masking step S2, the mask layer 102 is disposed so that its second opening 102a overlaps with the first opening 101a of the frame member 101. The second opening 102a of the mask layer 102 defines a recess 110. At this time, the exposed portion of the spacer 103 attached to the peripheral portion 102c on the back surface of the mask layer 102 adheres to the top surface of the frame member 101, and a part of the spacer 103 deforms appropriately to fill the gap between the top surface. The inner peripheral portion 102b of the mask layer 102 contacts the side surface (inner wall surface) of the first opening 101a of the frame member 101 on its back surface. By disposing the spacer 103 between the frame member 101 and the mask layer 102, the spacer 103 reliably fills the gap between the top surface of the frame member 101 and the back surface of the peripheral portion 102c of the mask layer 102, where gaps tend to occur, and the two are adhered to each other with as few gaps as possible.

[0053] Another example of the mask layer used in the masking step S2 is shown in Fig. 6, where (a) is a plan view and (b) is a cross-sectional view taken along the dashed line II' in (a). The mask layer 102 has a second opening 102a that is the same shape as the first opening 101a of the frame member 101 in a plan view, but smaller in size than the first opening 101a. The mask layer 102 has a folded portion 102d, shown by a broken line, formed in the outer portion of the second opening 102a, so that the inner peripheral edge portion 102b can be folded downward along the folded portion 102d. A spacer 103 made of a flexible material and having a predetermined thickness is attached to the back surface of the mask layer 102 in the peripheral portion 102c of the second opening 102a. The exposed portion of the spacer 103 is the portion that is in close contact with the frame member 101, and it is preferable that the spacer 103 has a flexibility sufficient to appropriately fill the gap between the exposed portion and the upper surface of the frame member 101, which is the portion that is in close contact with the frame member 101.

[0054] When the mask layer 102 of FIG. 6 is used, in the masking step S2, the mask layer 102 is arranged so that its second opening 102a overlaps with the first opening 101a of the frame member 101, and the exposed portion of the spacer 103 attached to the peripheral portion 102c on the back surface of the mask layer 102 is in close contact with the upper surface of the frame member 101. Then, the inner peripheral portion 102b of the mask layer 102 is folded downward, and the back surface of the inner peripheral portion 102b is brought into contact with the side surface (inner wall surface) of the first opening 101a of the frame member 101. The mask layer 102 defines a recess 110. In FIG. 6, the region on the surface of the substrate 100 where the electrode composition is to be formed is exposed as the bottom surface of the recess 110. Here, the exposed portion of the spacer 103 attached to the peripheral portion 102c on the back surface of the mask layer 102 comes into close contact with the top surface of the frame member 101, and a portion of the spacer 103 deforms appropriately to fill the gap between the top surface. By disposing the spacer 103 between the frame member 101 and the mask layer 102, the gap between the top surface of the frame member 101 and the back surface of the peripheral portion 102c of the mask layer 102, where gaps tend to occur, is reliably filled by the spacer 103, and the two come into close contact with as few gaps as possible.

[0055] (Supply process S3) 7 shows a state in which the electrode composition is supplied to the state in which the mask layer 102 is arranged in the supplying step S3, where (a) is a plan view and (b) is a cross-sectional view taken along the dashed line II' in (a). In the supplying step S3, an electrode composition 120 containing an electrode active material is intermittently supplied so as to fill the recesses 110 defined by the second openings 102a of the mask layer 102 up to the height of the mask layer 102. The electrode active material (coated positive electrode active material or coated negative electrode active material coated with a conductive assistant and a coating resin) described above is used as the electrode composition 120. Supplying intermittently means that the electrode composition 120 is supplied only into the recesses 110 of adjacent frame members 101 at a predetermined interval, so to speak, in a discontinuous manner.

[0056] For example, if the electrode composition 120 is supplied into the recess 110 without providing the spacer 103, it is difficult to avoid the formation of minute gaps between the frame member 101 and the mask layer 102, and therefore part of the electrode composition 120 penetrates into the gaps, and part of this electrode composition 120 remains even after the mask layer 102 is removed. The remaining electrode composition 120 may cause contamination.

[0057] In contrast, in this embodiment, the electrode composition 120 is applied to the recess 110 with the spacer 103 disposed between the frame member 101 and the mask layer 102. The flexible spacer 103 adheres the frame member 101 to the mask layer 102 with a portion of the spacer 103 appropriately deforming to fill the gap between the frame member 101 and the mask layer 102. This eliminates any room for a portion of the electrode composition 120 to penetrate between the frame member 101 and the mask layer 102, inhibiting such penetration and preventing the occurrence of contamination.

[0058] (Mask removal process S4) In the mask removing step S4, the mask layer 102 is removed from the frame member 101 together with the spacers 103. 8 shows the state after the mask layer 102 and the spacers 103 have been removed, where (a) is a plan view and (b) is a cross-sectional view taken along the dashed line II' in (a). When the mask layer 102 and the spacers 103 are removed, the electrode composition 120 present in the first opening 101a of the frame member 101 has its upper surface protruding from the upper end of the first opening 101a by the total thickness of the mask layer 102 and the spacers 103. In addition, the electrode composition 120 present in the first opening 101a of the frame member 101 is spaced from the side surface (inner wall surface) of the first opening 101a by the thickness of the mask layer 102.

[0059] For example, in the case where the spacer 103 is not provided, when the mask layer 102 is removed in the removing step S4, the upper surface of the electrode composition 120 present in the first opening 101a of the frame member 101 is in a state of protruding from the upper end of the first opening 101a by the thickness of the mask layer 102. The thickness of the mask layer 102 cannot be made too large due to factors such as the presence of the peripheral portion 102b. The protruding portion of the electrode composition 120 is restricted only by the thickness of the mask layer 102, and it is difficult to obtain the electrode composition 120 of the desired uniform thickness in the pressing step S5 with only the thickness of the mask layer 102.

[0060] In contrast, in this embodiment, when the mask layer 102 is removed in the mask removal step S4, the upper surface of the electrode composition 120 present in the first opening 101a of the frame member 101 is in a state of protruding from the upper end of the first opening 101a by an amount equal to the thickness of the mask layer 102 plus the thickness of the spacer 103. By forming the spacer 103 to a thickness as required, the protruding portion of the electrode composition 120 can be ensured to have a required thickness, and the electrode composition 120 of the desired uniform thickness can be obtained in the pressurizing step S5.

[0061] (Pressing step S5) FIG. 9 shows how the electrode composition 120 is pressed in the pressing step S5. In the pressurizing step S5, the electrode composition 120 present in the first opening 101a of the frame member 101 is pressed, for example, by a roll press to obtain an electrode composition layer 130. The line pressure in the roll press is not particularly limited, and can be adjusted according to the composition, fluidity, and density of the electrode composition. It is also possible to use a plate press instead of the roll press.

[0062] The roll press in the pressing step S5 is applied to the electrode composition 120 in a state in which the upper surface protrudes from the upper end of the first opening 101a by the total thickness of the mask layer 102 and the spacer 103, as shown in FIG. 8(b). The thickness of the spacer 103 is adjusted so that the total thickness is a required value. In the pressing step S5, the electrode composition 120 is pressed by the roll press to reduce the thickness and expand the size, and an electrode composition layer 130 having a flat upper surface and a uniform thickness, the uniform thickness being regulated by the upper surface of the frame member 101 and the size being regulated by the size of the first opening 101a of the frame member 101, is formed.

[0063] (Cutting process S6) In the cutting step S6, the substrate 100 having a plurality of electrode compositions 120 formed on its surface is cut between adjacent frame members 101 to cut out individual electrodes (positive electrodes or negative electrodes) each having an electrode composition layer (positive electrode active material layer or negative electrode active material layer) provided on a current collector (positive electrode current collector or negative electrode current collector) and sealed with a sealant. The method for cutting the substrate is not particularly limited, and examples thereof include known cutting methods (such as cutting with a rotary cutting blade, a guillotine blade, a Thomson type, or a laser).

[0064] In this manner, an electrode (positive electrode or negative electrode) for a lithium ion secondary battery can be manufactured.

[0065] In this embodiment, the frame member 101 is used as a sealant for the battery cells, but the frame member may be removed after the pressing step S5, and a sealant for the battery cells may be placed instead.

[0066] To manufacture a lithium ion secondary battery using the electrode manufactured according to the present embodiment, for example, a method can be used in which a positive electrode manufactured by the above-mentioned electrode manufacturing method and a negative electrode manufactured by the above-mentioned electrode manufacturing method are stacked with a separator between them so that the coated active material layers (positive electrode active material layer and negative electrode active material layer) face each other to prepare a battery cell, and this battery cell is then covered and sealed with an exterior film.

[0067] As described above, according to this embodiment, it is possible to prevent the electrode composition from entering or falling off during the production of an electrode, and to obtain an electrode composition layer with a uniform thickness.

[0068] (Method 1) A method for producing an electrode for a lithium ion secondary battery according to one embodiment of the present invention includes the following steps: a mounting step of mounting a frame member having a first opening on a surface of the base material; a placement step of placing a spacer on the frame member; a masking step of laminating a mask layer having a second opening on the frame member so as to fill a gap between the frame member and the mask layer with the spacer; a supplying step of supplying an electrode composition containing an electrode active material into the recess defined by the mask layer; has.

[0069] (Method 2) In the above method 1, the masking step involves laminating the mask layer, the inner periphery of which is bent downwardly, so that the inner periphery of the second opening fits along the side surface of the first opening of the frame member.

[0070] (Method 3) In the above-mentioned method 1, the masking step includes placing the mask layer on the frame member, and then folding the inner peripheral edge of the second opening of the mask layer along the side surface of the first opening of the frame member.

[0071] (Method 4) In any one of the above methods 1 to 3, the masking step includes laminating the mask layer having the second opening smaller in size than the first opening such that the second opening is included within the first opening.

[0072] (Method 5) In any one of the above methods 1 to 4, the spacer is made of silicone rubber or a polyimide film.

[0073] (Method 6) In any one of the above methods 1 to 5, the mask layer is made of a metal material.

[0074] (Method 7) In any one of the above methods 1 to 6, a removing step of removing the mask layer after the supplying step; a pressurizing step of pressurizing the electrode composition in the first opening with the frame member disposed on the surface of the base material to form an electrode composition layer; It further has:

[0075] (Method 8) In any one of the above methods 1 to 7, the frame member is used as a sealant that supports and fixes electrodes in a lithium ion secondary battery. [Explanation of symbols]

[0076] 1 Secondary battery module 2 negative electrode 3 Positive electrode 7,8 Conductive part 9. Sealing materials 10 Negative electrode current supply layer 11 Negative electrode current collector 12 Negative electrode active material layer 13 Separator 14 Cathode active material layer 15 Positive electrode current collector 16 Positive electrode side current extraction layer 20 Battery Cells 100 Base material 101 Frame members 101a First opening 101b Inner edge portion 101c Surrounding area 102 Mask Layer 102a Second opening 103 Spacer 110 Recess 120 Electrode composition 130 Electrode composition layer

Claims

1. a mounting step of mounting a frame member having a first opening on a surface of the base material; a placement step of placing a spacer on the frame member; a masking step of laminating a mask layer having a second opening on the frame member so as to fill a gap between the frame member and the mask layer with the spacer; a supplying step of supplying an electrode composition containing an electrode active material into the recess defined by the mask layer; having A method for manufacturing electrodes for lithium-ion secondary batteries.

2. The masking step includes laminating the mask layer having an inner peripheral edge of the second opening bent downward so that the inner peripheral edge is aligned with a side surface of the first opening of the frame member. A method for producing the electrode of the lithium ion secondary battery according to claim 1.

3. the masking step includes placing the mask layer on the frame member, and then folding an inner peripheral edge of the second opening of the mask layer along a side surface of the first opening of the frame member; A method for producing the electrode of the lithium ion secondary battery according to claim 1.

4. The masking step includes laminating the mask layer having the second opening smaller in size than the first opening such that the second opening is included within the first opening. A method for producing the electrode for a lithium ion secondary battery according to any one of claims 1 to 3.

5. The spacer is made of silicone rubber or polyimide film. A method for producing the electrode for a lithium ion secondary battery according to any one of claims 1 to 3.

6. The mask layer is made of a metal material. A method for producing the electrode for a lithium ion secondary battery according to any one of claims 1 to 3.

7. a removing step of removing the mask layer after the supplying step; a pressurizing step of pressurizing the electrode composition in the first opening in a state in which the frame member is disposed on the surface of the base material to form an electrode composition layer; Further comprising A method for producing the electrode for a lithium ion secondary battery according to any one of claims 1 to 3.

8. The frame member is used as a sealing material that supports and fixes electrodes in a lithium ion secondary battery. A method for producing the electrode for a lithium ion secondary battery according to any one of claims 1 to 3.

Images