WO2023163073A1

WO2023163073A1 - Method for producing electrode

Info

Publication number: WO2023163073A1
Application number: PCT/JP2023/006589
Authority: WO
Inventors: 堀江英明; 草野亮介; 横山祐一郎
Original assignee: Ａｐｂ株式会社
Priority date: 2022-02-22
Filing date: 2023-02-22
Publication date: 2023-08-31
Also published as: JP2023122455A

Abstract

In a production process of an electrode of a lithium ion secondary battery according to the present invention, the surface temperatures of roll presses (140a, 140b) are controlled to a predetermined temperature within the range of 70°C to 100°C during a pressing step, and an electrode composition layer (120) is pressed with use of the temperature-controlled roll presses (140a, 140b), thereby forming a coated active material layer (130). Consequently, the present invention enables the achievement of an electrode that has excellent strength, while suppressing the occurrence of cracking or the like in the electrode.

Description

Electrode manufacturing method

The present invention relates to an electrode manufacturing method.

Recently, lithium-ion batteries have been attracting attention as high-capacity, compact and lightweight batteries. A general lithium-ion battery is an assembled battery in which a plurality of single cells each having a positive electrode current collector, a positive electrode active material layer, a separator, a negative electrode current collector, and a negative electrode active material layer are laminated, as described in Patent Document 1. It is configured to be sealed with a battery exterior material in such a state. In a lithium ion battery, a positive electrode is composed of a positive electrode current collector and a positive electrode active material layer, and a negative electrode is composed of a negative electrode current collector and a negative electrode active material layer.

In order to manufacture an electrode for a lithium ion battery, for example, as in Patent Document 2, an active material is applied onto a sheet-like substrate serving as a current collector, and the active material on the substrate is pressed by a roll press. After that, a method of cutting to a predetermined length is known.

Japanese Patent No. 6070822 JP 2016-181469 A

However, with conventional electrode manufacturing methods, the strength of the manufactured electrodes may be insufficient. For example, there is a problem that cracks occur in the electrode after performing the pressurizing step or after supplying the electrolyte solution to the formed electrode.

An object of the present invention is to provide an electrode manufacturing method capable of obtaining an electrode having excellent strength without cracks or the like.

As a result of intensive studies based on the above findings, the inventor has arrived at the following aspects of the invention.

A supplying step of supplying the electrode composition onto the substrate;
A pressurizing step of pressurizing the electrode composition using a roll press adjusted to a surface temperature of 70 ° C. or more and less than 100 ° C.;
having
A method of manufacturing an electrode.

According to the method for manufacturing an electrode according to the present invention, it is possible to obtain an electrode having excellent strength without cracking or the like.

FIG. 1 is a schematic cross-sectional view showing a secondary battery module according to the first embodiment. FIG. 2 is a flow chart showing the method for manufacturing the electrode of the lithium ion secondary battery according to the first embodiment in order of steps. FIG. 3 is a schematic perspective view showing an example of a masking step in the method for manufacturing the electrode of the lithium ion secondary battery according to the first embodiment. FIG. 4 is a schematic perspective view showing an example of the supply step in the method for manufacturing the electrode of the lithium ion secondary battery according to the first embodiment. FIG. 5 is a schematic perspective view showing an example of a removing step in the method for manufacturing the electrode of the lithium ion secondary battery according to the first embodiment. FIG. 6 is a schematic side cross-sectional view showing an example of a pressurizing step in the method for manufacturing the electrode of the lithium ion secondary battery according to the first embodiment. FIG. 7 is a flowchart showing a method for manufacturing an electrode of a lithium ion secondary battery according to the second embodiment in order of steps.

Embodiments in which the method for producing an electrode according to the present invention is applied to the production of electrodes for lithium ion secondary batteries will be described in detail below with reference to the drawings.
The following embodiments disclose a method of manufacturing an electrode for a lithium ion secondary battery. Although an example of a lithium ion secondary battery is shown below, the type of secondary battery according to the present invention is not limited to the lithium ion secondary battery, and includes other secondary batteries. Lithium-ion secondary batteries include not only the embodiments described below, but also batteries using a liquid material for the electrolyte and batteries using a solid material for the electrolyte (so-called all-solid-state batteries). In addition, the lithium ion battery in the present embodiment includes a battery having a metal foil (metal current collector foil) as a current collector, and is composed of a resin to which a conductive material is added instead of the metal foil, a so-called resin current collector. Including a battery with a body. When the resin current collector is used as a resin current collector for a bipolar electrode, a positive electrode is formed on one surface of the resin current collector and a negative electrode is formed on the other surface to form a bipolar electrode. It may be In addition, the lithium ion battery in the present embodiment includes those in which the positive electrode or negative electrode active material or the like is applied to the positive electrode current collector or the negative electrode current collector using a binder to form an electrode, and in the case of a bipolar battery, is a bipolar electrode having a positive electrode layer formed by applying a positive electrode active material or the like using a binder to one surface of a current collector, and a negative electrode layer formed by applying a negative electrode active material or the like using a binder to the opposite surface of the current collector. including those that consist of

[First embodiment]
First, the first embodiment will be described.

(Structure of lithium ion secondary battery)
Before describing this embodiment, first, the configuration of a secondary battery module for a lithium-ion secondary battery having electrodes manufactured according to this embodiment will be described. FIG. 1 is a schematic cross-sectional view showing a secondary battery module according to the first embodiment.

In the secondary battery module 1, a negative electrode 2 composed of a negative electrode current collector 11 and a negative electrode active material layer 12, and a positive electrode 3 composed of a positive electrode active material layer 14 and a positive electrode current collector 15 are laminated with a separator 13 interposed therebetween. It is configured as a battery cell 20 consisting of a laminated battery (single battery) on a flat plate. That is, the battery cell 20 constituting the secondary battery module 1 has a negative electrode current collector 11, a negative electrode active material layer 12, a separator 13, a positive electrode active material layer 14, and a positive electrode current collector 15, which are stacked upward. It is formed in a substantially rectangular flat plate shape as a whole.

The secondary battery module 1 further includes an annular frame member 9 arranged around the periphery of the battery cells 20 . The edge of the separator 13 is embedded in the frame member 9 to support the separator 13, and the frame member 9 brings the positive electrode current collector 15 and the negative electrode current collector 11 into surface contact with the upper and lower surfaces thereof. They are fixed on top of each other. By fixing the peripheral edge portions of the negative electrode current collector 11, the positive electrode current collector 15, and the separator 13 through the frame member 9, the negative electrode active material layer 12 and the positive electrode active material layer 14 are firmly prevented from leaking to the outside. It becomes possible to seal to Further, the frame member 9 can determine the positional relationship among 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. The negative electrode current collector 11, the separator 13, and the positive electrode current collector 15 can be fixed to each other.

A negative electrode current supply layer 10 as a conductor layer is laminated on the lower side of the negative electrode current collector 11 in a planar shape, and a positive electrode current extraction layer, which is also a conductor layer, is laminated on the upper side of the positive electrode current collector 15 . 16 are stacked in a plane. The negative current supply layer 10 and the positive current extraction layer 16 are provided with

conductive parts

7 and 8 to which current is supplied, respectively.

In the secondary battery module 1, an exterior film (not shown) that covers the battery cells 20, the negative electrode current supply layer 10, and the positive electrode current extraction layer 16 may be provided. As the exterior film, for example, it is made of an insulating material, and it is possible to use a known material used in batteries, 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.

It should be noted that 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 composed of single cells. For example, an assembled battery may be formed by stacking and connecting a plurality of battery cells 20 .

In such an assembled battery, by connecting a plurality of battery cells 20 in series, the conductive portion 8 connected to the positive electrode current extraction layer 16 of the uppermost battery cell 20 and the negative electrode current of the lowermost battery cell 20 are connected to each other. A current may be freely supplied via the conductive portion 7 connected to the supply layer 10 . In such a case, the battery cells 20 that are connected to each other are stacked such that the lower surface of the negative electrode current supply layer 10 and the upper surface of the positive electrode current extraction layer 16 are adjacent to each other. Furthermore, when forming such an assembled battery, a plurality of battery cells 20 may be connected in parallel, or series connection and parallel connection may be combined. By configuring such an assembled battery, high capacity and high output can be obtained. Alternatively, the

conductive portions

7 and 8 connected to the negative current supply layer 10 and the positive current extraction layer 16 of each battery cell 20 may be configured to independently supply current.

Preferred aspects of each constituent material constituting the battery cell 20 will be described below.

The positive electrode active material layer contains a positive electrode active material as an electrode composition.
Examples of positive electrode active materials include composite oxides of lithium and transition metals {composite oxides containing one type of transition metal element (LiCoO ₂ , LiNiO ₂ , LiAlMnO ₄ , LiMnO ₂ and LiMn ₂ O ₄ , etc.), transition metal elements are two kinds of composite oxides (for example, LiFeMnO ₄ , LiNi _1-x Co _x O ₂ , LiMn _1-y Co _y O ₂ , LiNi _1/3 Co _1/3 Al _1/3 O ₂ and LiNi _0.8 Co _0.15 Al _0.05 O ₂ ) and a composite oxide containing three or more transition metal elements [for example, LiM _a M′ _b M″ _c O ₂ (M, M′ and M″ are different transition metal elements _and _satisfies _a ₊ _b + _c = ₁ _. ), transition metal oxides (eg MnO ₂ and V ₂ O ₅ ), transition metal sulfides (eg MoS ₂ and TiS ₂ ) and conductive polymers (eg polyaniline, polypyrrole, polythiophene, polyacetylene and poly-p-phenylene and polyvinylcarbazole), etc., and two or more of them may be used in combination.
Note that the lithium-containing transition metal phosphate may have a transition metal site partially substituted with another transition metal.

In this embodiment, the positive electrode active material is a coated positive electrode active material coated with a conductive aid and a coating resin.
When the periphery of the positive electrode active material is covered with the coating resin, the volume change of the electrode is moderated, and the expansion of the electrode can be suppressed.

Conductive agents include metallic conductive agents [aluminum, stainless steel (SUS), silver, gold, copper, titanium, etc.], carbon-based conductive agents [graphite and carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black, etc.), and mixtures thereof.
One of these conductive aids may be used alone, or two or more thereof may be used in combination. Moreover, these alloys or metal oxides may be used.

Among them, from the viewpoint of electrical stability, aluminum, stainless steel, silver, gold, copper, titanium, carbon-based conductive aids and mixtures thereof are more preferable, and silver, gold, aluminum, stainless steel and carbon are more preferable. A conductive additive, particularly preferably a carbon-based conductive additive.
These conductive aids may also be those obtained by coating a conductive material [preferably a metal one of the above conductive aids] around a particulate ceramic material or a resin material by plating or the like.

The shape (form) of the conductive aid is not limited to the particle form, and may be in a form other than the particle form, such as carbon nanofibers, carbon nanotubes, etc., which are practically used as so-called filler-type conductive aids. can be

The ratio of the coating resin and the conductive aid 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 aid is 1:0.01 to 1. :50, more preferably 1:0.2 to 1:3.0.

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

Moreover, the positive electrode active material layer may contain a conductive support agent in addition to the conductive support agent contained in the coated positive electrode active material.
As the conductive aid, the same conductive aid as contained in the above-described coated positive electrode active material can be suitably used.

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 materials together.
Here, the non-bound body means that the position of the positive electrode active material is not fixed by a binder (also referred to as a binder), and the positive electrode active material and the current collector are irreversibly fixed to each other. means no.

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

In addition, adhesive resin is a resin that does not solidify even if the solvent component is volatilized and dried, and has adhesiveness (the property of adhering by applying a slight pressure without using water, solvent, heat, etc.) means On the other hand, a solution-drying type electrode binder used as a binding material is one that evaporates a solvent component to dry and solidify, thereby firmly adhering and fixing active materials to each other.
Therefore, the solution-drying type electrode binder (binding material) and the adhesive resin are different materials.

Although the thickness of the positive electrode active material layer is not particularly limited, it is preferably 150 μm to 600 μm, more preferably 200 μm to 450 μm, from the viewpoint of battery performance.

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. ), cokes (for example, pitch coke, needle coke, petroleum coke, etc.) and carbon fibers, etc.], silicon-based materials [silicon, silicon oxide (SiOx), silicon-carbon composites (carbon particles with silicon and / Or those coated with silicon carbide, silicon particles or silicon oxide particles whose surfaces are coated with carbon and / or silicon carbide, silicon carbide, etc.) and silicon alloys (silicon-aluminum alloy, silicon-lithium alloy, silicon-nickel alloys, silicon-iron alloys, silicon-titanium alloys, silicon-manganese alloys, silicon-copper alloys, silicon-tin alloys, etc.)], conductive polymers (such as polyacetylene and polypyrrole, etc.), metals (tin, aluminum, zirconium and titanium, etc.), metal oxides (titanium oxides and lithium-titanium oxides, etc.) and metal alloys (e.g., lithium-tin alloys, lithium-aluminum alloys, lithium-aluminum-manganese alloys, etc.), etc., and these and carbon-based materials and the like.

In this embodiment, the negative electrode active material is a coated negative electrode active material coated with the same conductive aid and coating resin as the coated positive electrode active material described above.
As the conductive aid and the coating resin, the same conductive aid and coating resin as those of the coated positive electrode active material described above can be suitably used.

In addition, the negative electrode active material layer may contain a conductive aid other than the conductive aid contained in the coated negative electrode active material. As the conductive aid, the same conductive aid as contained in the above-described coated positive electrode active material can be suitably used.

Like the positive electrode active material layer, 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. Also, like the positive electrode active material layer, it may contain an adhesive resin.

Although the thickness of the negative electrode active material layer is not particularly limited, it is preferably 150 μm to 600 μm, more preferably 200 μm to 450 μm, from the viewpoint of battery performance.

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 current collector is not particularly limited, and may be a sheet-like current collector made of a conductive polymer material or a deposited layer made of fine particles made of a conductive polymer material.
Although the thickness of the resin current collector is not particularly limited, it is preferably 50 μm to 500 μm.

As the conductive polymer material constituting the resin current collector, for example, a conductive polymer or a resin obtained by adding a conductive agent to the resin can be used.
As the conductive agent that constitutes the conductive polymer material, the same conductive aid as that contained in the above-described coated positive electrode active material can be preferably used.

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

Separators include porous films made of polyethylene or polypropylene, laminated films of porous polyethylene film and porous polypropylene, non-woven fabrics made of synthetic fibers (polyester fibers, aramid fibers, etc.) or glass fibers, and silica on their surfaces. , alumina, titania, and other known separators for lithium ion batteries.

The positive electrode active material layer and the negative electrode active material layer contain an electrolytic solution.
As the electrolytic solution, a known electrolytic solution containing an electrolyte and a non-aqueous solvent, which is used for manufacturing known lithium ion batteries, can be used.

_As _the electrolyte _, those _used in _known electrolytic solutions can _be used _. Lithium salts of organic acids such as LiN(CF ₃ SO ₂ ) ₂ , LiN(C ₂ F ₅ SO ₂ ) ₂ and LiC(CF ₃ SO ₂ ) ₃ are included. Among these, imide-based electrolytes [LiN( _FSO2 ) ₂ , LiN( _CF3SO2 ₎ ₂ , LiN( _C2F5SO2 ) ₂ _, etc. _] and _LiPF6 .

As the non-aqueous solvent, those used in known electrolytic solutions can be used. compounds, amide compounds, sulfones, sulfolane, etc. and mixtures thereof can be used.

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, even more 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 have sufficient input/output characteristics, and if it exceeds 5 mol/L, the electrolyte may precipitate.
The electrolyte concentration of the electrolytic solution can be confirmed by extracting the lithium ion battery electrode or the electrolytic solution constituting the lithium ion battery without using a solvent or the like and measuring the concentration.

(Method for manufacturing electrode)
A method for manufacturing electrodes (a positive electrode and a negative electrode) for a lithium ion secondary battery will be described below.
FIG. 2 is a flow chart showing the method for manufacturing the electrode of the lithium ion secondary battery according to the first embodiment in order of steps.

The method for manufacturing the electrodes (positive electrode and negative electrode) according to the present embodiment includes a masking step S1 of placing a mask layer on the substrate, a supplying step S2 of supplying the electrode composition on the substrate, and The method includes a removing step S3 for intermittently leaving the electrode composition, a pressing step S4 for pressing the electrode composition on the substrate using a roll press, and a cutting step S5 for cutting out the electrode.

In this embodiment, the order of the removing step S3 and the pressurizing step S4 is not particularly limited. Therefore, the pressure step S4 may be performed after the removal step S3 is performed, or the removal step S3 may be performed after the pressure step S4 is performed. Moreover, you may perform removal process S3 and pressurization process S4 simultaneously. Below, the case where the removing step S3 is performed first and then the pressurizing step S4 is performed will be described.

(Masking step S1)
In the masking step S1, as shown in FIG. 3, a mask layer 110 having openings A1, A2, A3, A4, and A5 having sizes corresponding to intermittently arranged electrode composition layer arrangement portions is continuously formed. It is placed on a sheet-like base material 100 . In the state where the mask layer 110 is placed on the base material 100, the openings of the mask layer 110 (here, only A1, A2, A3, A4 and A5 are shown) to the electrode composition layer arrangement portion of the base material 100. is exposed. Here, the electrode composition layer arrangement portion is intermittently arranged means that the electrode composition layer arrangement portion (electrode composition layer arrangement portion) and the electrode composition layer are arranged on the surface of the substrate 100. is not disposed (electrode composition layer non-arranged portion), and two or more electrode composition layer disposed portions exist and are not in contact with each other. The distance between the electrode composition layer arrangement portions provided so as not to contact each other may be constant or may be different.

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

(Supplying step S2)
In the supply step S2, an electrode composition containing an electrode active material is continuously supplied onto the substrate.
Continuous supply means that the electrode composition is continuously supplied so as to straddle two or more electrode composition layer arrangement portions formed by the removal step S3 described later. At this time, the electrode composition may be supplied intermittently. However, when the electrode composition is intermittently supplied, the electrode composition formed on the substrate by the intermittent supply of the electrode composition is removed by the removal step described later to form two or more electrode composition layer arrangement portions. should be Therefore, when only one electrode composition layer placement portion is formed in one electrode composition that is intermittently supplied, it cannot be said that the electrode composition is continuously supplied onto the substrate.

Supplying onto the substrate includes not only supplying directly onto the surface of the substrate but also supplying the electrode composition onto another member placed on the substrate. Therefore, in the supplying step, the electrode composition is directly or indirectly supplied onto the substrate.

The thickness of the electrode composition provided on the substrate may be adjusted as needed.
Examples of methods for adjusting the thickness of the electrode composition include methods using a squeegee, a rotating roller, a doctor blade, an applicator, and the like. The step of adjusting the thickness of the electrode composition may be performed by the device used in the supply step S2 described above, or may be performed by using a device different from the device used in the supply step.

An example of the supply step S2 will be described with reference to FIG.
In the supply step S<b>2 , the electrode composition 120 is continuously supplied onto the elongated sheet-like substrate 100 . The supplied electrode composition 120 is deposited so as to fill the openings A1, A2, A3, A4 and A5 of the mask layer 140 placed on the substrate 100 and cover the mask layer 110. FIG. As the electrode composition 120, the above-described electrode active material (coated positive electrode active material or coated negative electrode active material coated with a conductive aid and a coating resin) is used.

Specifically, the electrode composition 120 is continuously supplied from a hopper placed on the substrate 100 while changing the relative position between the hopper capable of quantitatively supplying the electrode composition 120 and the substrate 100. method can be used.

A method for changing the relative position between the hopper and the substrate 100 is not particularly limited, and the substrate 100 may be moved in one direction by a belt conveyor. Moreover, the method of providing a wheel in a hopper and driving a wheel, the method of winding up a hopper in one direction by a winch, etc. may be used.
The change speed of the relative position between the hopper and the substrate can be appropriately adjusted by the density and thickness of the electrode composition layer 120 and the viscosity of the electrode composition layer.

As another example of the supplying process, after intermittently supplying the electrode composition onto the substrate 100, the thickness of the supplied electrode composition may be adjusted using a squeegee.

(Removal step S3)
In the removing step S3, part of the electrode composition supplied onto the substrate 100 is removed to form an electrode composition layer on the electrode composition layer arrangement portion of the substrate surface. The region where the electrode composition layer was not formed becomes the electrode composition layer non-arranged portion.
In the case where the pressing step S4 is performed after the removing step S3 and the size of the electrode composition layer is changed by the pressing step S4, an electrode that has a desired shape after pressing is used. It is preferable to set the size of the composition layer in advance.

An example of the removal step S3 will be described with reference to FIG.
In the removing step S3, the mask layer 110 is removed from the substrate 100. FIG. At this time, the electrode composition 120 placed in the openings of the mask layer 110 remains on the substrate 100 . Meanwhile, the electrode composition 120 supplied on the mask layer 140 is removed from the substrate 100 together with the mask layer 110 . By leaving the electrode composition 120 only in the regions where the openings (A1, A2, A3, A4 and A5) of the mask layer 110 were, an electrode composition layer composed of the electrode composition 120 is formed on the substrate 100. 120A is formed intermittently.

Another example of the masking process, supply process, and removal process will be explained. Here, first, the electrode composition 120 is continuously supplied onto the substrate 100 by a supply step. Subsequently, on the electrode composition 120 deposited on the substrate 100 by the masking process, a cover layer having a size corresponding to the electrode composition layer is placed at each place where the electrode composition layer is to be arranged. Subsequently, in the removal step, the electrode composition 120 that is not covered with the cover layer is removed by suction with a suction device, and then the cover layer is removed from the electrode composition 120, thereby forming the electrode composition on the substrate 100. An electrode composition layer of material 120 can be intermittently deposited.

(Pressure step S4)
In the pressing step S4, the electrode composition supplied onto the substrate in the supplying step S3 is pressed by a roll press to obtain a coated active material layer. The linear pressure in the roll press is not particularly limited, and can be adjusted according to the composition of the electrode composition, the fluidity of the electrode composition, and the density of the electrode composition.

As a result of intensive studies on a manufacturing method for obtaining an electrode having excellent strength in a lithium ion battery, the present inventor found that using a coated active material as an electrode composition, the surface temperature of the roll press in the pressing step of the electrode composition was reduced to It was conceived that an electrode having excellent strength can be obtained by performing the pressurizing step with the value set within a predetermined range.

An example of the pressurizing step S4 will be described with reference to FIG.
In the pressing step S4, the electrode composition layer 120 placed on the substrate 100 is pressed by

roll presses

140a and 140b. A coating active material layer 130 is formed on the substrate 100 by pressing the electrode composition layer 120 . In this embodiment, during the pressurizing step, the surface temperatures of the roll presses 140a and 140b are adjusted to a predetermined temperature within the range of 70° C. or more and less than 100° C., and the temperature-controlled roll presses 140a and 140b are used to press the electrodes. Composite layer 120 is pressed.

Note that the pressurizing step S4 shown in FIG. 6 is an example of the pressurizing step performed after the removing step S3. When the pressurizing step S4 is performed before the removing step S3, the member (for example, the mask layer) used in the removing step may be pressurized together with the electrode composition layer.

If the surface temperature of the roll presses 140a and 140b is less than 70° C., the coating resin that coats the coating active material, which is the material of the electrode composition layer 120, will not melt sufficiently when the electrode composition layer 120 is pressed. While the strength of the electrode is ensured by melting the coating resin that coats the coated active material during pressurization, if the melting of the coating resin is insufficient, the manufactured electrode will not have excellent strength.
If the surface temperature of the roll presses 140a and 140b is 100° C. or higher, the substrate 100 on which the electrode composition layer 120 is arranged may deteriorate. In particular, when a resin current collector is used as the base material 100, there is a high possibility of deterioration.
By performing the pressing step S4 while adjusting the surface temperature of the roll presses 140a and 140b within the range of 70° C. or more and less than 100° C., the performance of the base material 100 is maintained, and the coated active material is compressed by pressing with heating. The coating resin covering the is sufficiently melted, and an electrode having excellent strength can be obtained.

Further, in this embodiment, it is desirable that the peripheral speed of the roll presses 140a and 140b during the pressing step S4 is 5 mm/s or more and 40 mm/s or less.
When the peripheral speed of the roll presses 140a and 140b is less than 5 mm/s, depending on the material of the base material 100 (particularly the resin current collector) on which the electrode composition layer 120 is arranged, the electrode composition layer 120 may not move during pressurization. The heat transfer from the roll presses 140a and 140b may be excessive and the substrate 100 may be degraded.
When the peripheral speed of the roll presses 140a and 140b is more than 40 mm/s, depending on the material of the coating resin that coats the coated active material in the electrode composition layer 120, the roll presses 140a and 140b onto the electrode composition layer 120 during pressurization Insufficient heat transfer from 140b may result in insufficient melting of the coating resin.
The surface temperature of the roll presses 140a and 140b is adjusted to a temperature within the range of 70 ° C. or more and less than 100 ° C., and the peripheral speed of the roll presses 140a and 140b is adjusted to 5 mm / s or more and 40 mm / s or less. By carrying out S4, an electrode having excellent strength can be reliably obtained.

In addition, in the present embodiment, as the coating resin that coats the coating active material that is the material of the electrode composition layer 120, a coating resin having a glass transition temperature Tg in the range of −70° C. or more and 50° C. or less is used. is desirable.
If a coating resin having a glass transition temperature Tg of less than −70° C. is used as the coating resin for the coating active material of the electrode composition layer 120, the crystallinity of the coating resin is too high. Adjusting the temperature of 140b within the predetermined range may not be reflected in the electrode strength.
When a coating resin having a glass transition temperature Tg of more than 50° C. is used as the coating resin for the coated active material of the electrode composition layer 120, the surface temperature of the roll presses 140a and 140b during the pressing step S4 is set within the predetermined range described above, for example. If the temperature is less than about 100° C., which is the maximum value, the coating resin is considered to flow, but the coating resin cannot be melted sufficiently, which may not be reflected in the electrode strength.
The surface temperature of the roll presses 140a and 140b is adjusted to a temperature within the range of 70 ° C. or more and less than 100 ° C., and the glass transition temperature Tg is a temperature within the range of -70 ° C. or more and 50 ° C. or less. By using it for the coating resin that coats the coating active material, which is the material of the composition layer 120, an electrode with excellent strength can be obtained without fail.

Further, in the present embodiment, the surface temperature of the roll presses 140a and 140b during the pressing step S4 is the glass transition temperature Tg of the coating resin that coats the coating active material that is the material of the electrode composition layer 120. It is desirable to adjust the temperature so that the difference in temperature falls within the range of 70°C or higher and 150°C or lower.
If the difference is less than 70° C., the coating resin that coats the coating active material, which is the material of the electrode composition layer 120 , will not melt sufficiently when the electrode composition layer 120 is pressurized.
If the difference exceeds 150° C., the substrate 100 (particularly the resin current collector) on which the electrode composition layer 120 is arranged may deteriorate.
The surface temperature of the roll presses 140a and 140b is set to a temperature within the range of 70° C. or more and less than 100° C., and the surface temperature and the glass transition temperature of the coating resin that coats the coating active material that is the material of the electrode composition layer 120. By performing the pressing step S4 while adjusting the temperature so that the difference from Tg is within the range of 70° C. or higher and 150° C. or lower, an electrode having excellent strength can be obtained without fail.

(Cutting step S5)
In the cutting step S5, the base material 100 having a plurality of coated active material layers 130 formed on the surface is cut at the electrode composition layer non-arrangement portion, and the current collector (positive electrode current collector or negative electrode current collector) is cut. Individual electrodes (positive electrodes or negative electrodes) provided with a coating active material layer (positive electrode active material layer or negative electrode active material layer) are cut out. The method for cutting the base material is not particularly limited, and includes known cutting methods (rotary cutting blade, guillotine blade, Thomson cutting, laser cutting, etc.).

As described above, an electrode (positive electrode or negative electrode) of a lithium ion secondary battery can be manufactured.

In order to manufacture a lithium ion secondary battery using the electrode manufactured according to the present embodiment, for example, the positive electrode manufactured by the electrode manufacturing method described above and the negative electrode manufactured by the electrode manufacturing method described above are laminated so that the coated active material layers (positive electrode active material layer and negative electrode active material layer) face each other with a separator interposed to form a battery cell, and the battery cell is covered with an exterior film and sealed. method.

As described above, according to the present embodiment, it is possible to obtain an electrode of a lithium-ion secondary battery that is free from cracks and has excellent strength.

[Second embodiment]
A second embodiment will be described below. This embodiment discloses a method for manufacturing an electrode for a lithium-ion secondary battery in the same manner as in the first embodiment, but differs from the first embodiment in that the manufacturing process is partially different.
FIG. 7 is a flowchart showing a method for manufacturing an electrode of a lithium ion secondary battery according to the second embodiment in order of steps.

In the electrode manufacturing method according to the present embodiment, the masking step S1, the supplying step S2, and the removing step S3 are sequentially performed, as in the first embodiment. Subsequently, the heating step S11 is performed as a pre-process of the pressing step S4, and then the pressing step S4 and the cutting step S5 are sequentially performed in the same manner as in the first embodiment.

In this embodiment, the order of the removing step S3, the heating step S11, and the pressing step S4 is not particularly limited. Therefore, the heating step S11 and the pressurizing step S4 may be performed after the removing step S3, or the removing step S3 may be performed after the heating step S11 and the pressurizing step S4 are performed.

(Heating step S11)
In the heating step S11, prior to the pressing step S4, the electrode composition supplied onto the substrate in the supplying step S3 is preliminarily heated.
Specifically, using a heating press that heats in a plane or a roll press that heats linearly, the surface temperature of the heating press or roll press is set to a temperature equivalent to the temperature in the subsequent pressing step S4, that is, 70 C. to less than 100.degree. C. to heat the electrode composition on the substrate. At this time, unlike the pressurizing step S4, the electrode composition on the substrate is heated with almost no pressurization.

After the heating step S11, the pressurizing step S4 is performed as in the first embodiment.
In this embodiment, the heating step S11 is first performed prior to the pressurizing step S4, so that the coating resin that coats the coating active material, which is the material of the electrode composition layer, melts. When the pressure step S4 is subsequently performed, the coating resin is in a state of being appropriately melted by the heating step S11, so there is no concern that the surface temperature of the roll press will deteriorate the substrate on which the electrode composition layer is arranged. The electrode composition layer can be pressurized by adjusting the degree. As a result, it is possible to obtain an electrode having excellent strength by sufficiently melting the coating resin of the electrode composition layer by roll pressing while suppressing deterioration of the base material.

After that, the cutting step S5 is performed in the same manner as in the first embodiment to manufacture the electrodes (positive electrode or negative electrode) of the lithium ion secondary battery.

As described above, according to the present embodiment, an electrode for a lithium-ion secondary battery having excellent strength that does not cause cracks or the like while reliably suppressing deterioration of the base material on which the electrode composition layer is formed. can be obtained.

A method for manufacturing an electrode according to an embodiment of the present invention includes a supplying step of supplying an electrode composition containing a coated active material onto a substrate;
A pressurizing step of pressurizing the electrode composition using a roll press adjusted to a surface temperature of 70 ° C. or more and less than 100 ° C.;
have

In the above embodiment, the peripheral speed of the roll press in the pressing step is 5 mm/s or more and 40 mm/s or less.

In the above embodiment, the difference between the surface temperature of the roll press in the pressing step and the glass transition temperature of the coating resin of the coating active material is 70°C or higher and 150°C or lower.

In the above embodiment, the glass transition temperature of the coating resin is -70°C or higher and 50°C or lower.

In the above embodiment, before the pressurizing step,
It has a heating step of heating the electrode composition supplied onto the substrate.

In the above embodiment, in the supplying step, the electrode composition is continuously supplied onto the substrate,
Before or after the pressurizing step, there is a removing step of removing a part of the electrode composition continuously supplied onto the substrate to intermittently leave the electrode composition on the substrate.

According to the aspect of the invention described above, it is possible to obtain an electrode with excellent strength that does not cause cracks or the like.

1 Secondary Battery Module 2 Negative Electrode 3

Positive Electrodes

7, 8 Conductive Part 9 Frame Member 10 Negative Electrode Side Current Supply Layer 11 Negative Electrode Current Collector 12 Negative Electrode Active Material Layer 13 Separator 14 Positive Electrode Active Material Layer 15 Positive Electrode Current Collector 16 Positive Electrode Side Current extraction layer 20 Battery cell 100 Base material 110 Mask layer 120 Electrode composition 120A Electrode composition layer 130 Covered

active material layers

140a, 140b Roll press

Claims

A supply step of supplying an electrode composition containing a coated active material coated with a coating resin having a glass transition temperature of −70° C. or more and 50° C. or less onto a substrate;
A pressurizing step of pressurizing the electrode composition using a roll press adjusted to a surface temperature of 70 ° C. or more and less than 100 ° C.;
a heating step of heating the electrode composition supplied onto the substrate after the supplying step and before the pressing step;
having
A method of manufacturing an electrode.
The peripheral speed of the roll press in the pressing step is 5 mm / s or more and 40 mm / s or less.
A method for manufacturing the electrode according to claim 1 .
The difference between the surface temperature of the roll press in the pressing step and the glass transition temperature of the coating resin of the coating active material is 70° C. or more and 150° C. or less.
A method for manufacturing the electrode according to claim 1 .
In the supplying step, the electrode composition is continuously supplied onto the substrate,
Before or after the pressurizing step, a removing step of removing a part of the electrode composition continuously supplied onto the substrate and intermittently leaving the electrode composition on the substrate;
A method for manufacturing the electrode according to claim 1 .