JP7109506B2 - Device for manufacturing lithium ion battery electrode and method for manufacturing lithium ion battery electrode - Google Patents

Description

TECHNICAL FIELD The present invention relates to an apparatus for manufacturing a lithium ion battery electrode and a method for manufacturing a lithium ion battery electrode.

Lithium ion (secondary) batteries have been widely used in recent years as high-capacity, small-sized, and lightweight secondary batteries.

Lithium-ion batteries generally form electrodes by applying a positive electrode or negative electrode active material or the like to a positive electrode collector or a negative electrode current collector, respectively, using a binder. In the case of a bipolar battery, one side of the current collector is coated with a positive electrode active material or the like using a binder to form a positive electrode layer, and the other side of the current collector is coated with a negative electrode active material or the like using a binder. As a result, a bipolar electrode having a negative electrode layer is formed.

As a method of manufacturing such a lithium ion battery, there is a method of compression molding an electrode active material using a roll press.

In Patent Document 1, an electrode material powder containing an electrode active material and a binder is supplied to a region surrounded by a pair of rolls and an end rectifying member, and the region is surrounded by the pair of rolls and the end rectifying member. A method is disclosed for fabricating an electrode layer by pressing an electrode material powder supplied in a defined region.

Patent Document 2 discloses a process of supplying a granule containing an electrode active material, a binder and a solvent between a pair of rolls and compression-molding the granule with a pair of rolls to form an electrode mixture layer. and disposing an electrode mixture layer on an electrode current collector.

Patent No. 5772429 JP 2018-85182 A Patent No. 6126546 Patent No. 6255546

In the method described in Patent Document 1, only an electrode layer continuous in the MD direction can be produced. Therefore, in order to use it as an electrode for a lithium ion battery, it is necessary to further process the electrode layer. Defects such as cracks and chips in the layers tend to occur.

Moreover, both of the methods disclosed in Patent Documents 1 and 2 include a step of roll-pressing the electrode active material in a powder state. In the process, air may be rolled up in the roll together with the electrode active material powder and compressed. There is a problem that moldability is reduced).

As a method for solving this problem, the inventors of the present invention have found that the powdery electrode active material is roll-pressed under a reduced pressure environment. According to the configuration found by the present inventors, in the step of roll-pressing the electrode active material in a powder state, air is suppressed from being rolled into the roll and compressed together with the electrode active material powder. It is possible to solve the problems described above. Among the configurations found by the inventors of the present invention, those that simply perform a predetermined process under a reduced pressure environment are disclosed in Patent Documents 3 and 4, for example.

Specifically, Patent Literature 3 discloses applying a negative electrode mixture slurry containing an electrode binder and a negative electrode active material to the surface of a negative electrode current collector, followed by hot roll pressing in a nitrogen atmosphere or in a vacuum. there is However, Patent Document 3 only discloses that when copper foil is used as a negative electrode current collector, the operation is performed in a non-oxygen environment, for example, in a vacuum in order to prevent oxidation of copper (Patent Document 3, for example, Paragraphs 0018, 0020, etc.), it does not disclose a specific configuration performed in a vacuum environment in order to suppress deterioration of the moldability of the electrode composition. Rather, as disclosed in FIG. 4B of Patent Document 3, a nitrogen replacement box (non-oxygen gas replacement chamber ) may lead to an increase in size of the manufacturing apparatus as a whole. If the entire manufacturing apparatus becomes large, it takes time to adjust the pressure between the reduced pressure and the atmospheric pressure, so that it cannot be applied to continuous product manufacturing, and a new problem arises that the manufacturing cost cannot be suppressed.

Further, in Patent Document 4, a process for bonding another plate-shaped work such as a touch panel or a cover film to a plate-shaped work such as a liquid crystal display or an organic EL display can be performed in a vacuum environment. disclosed. However, in order to perform the bonding process under the vacuum environment, Patent Document 4 only discloses a configuration in which the entire work is stored in a vacuum chamber, and the manufacturing apparatus as a whole is large as in Patent Document 3. It is a configuration that invites change. Then, Patent Document 4 also has the same problem as Patent Document 3 described above.

The present invention has been made in view of the above problems, and suppresses the occurrence of cracks and chips in the electrode layer, suppresses the deterioration of the moldability of the electrode composition, shortens the pressure adjustment time, and reduces the manufacturing cost. It is an object of the present invention to provide a method for manufacturing an electrode for a lithium ion battery and an apparatus for manufacturing the same.

The present invention provides a carrier substrate on which an electrode material for a lithium ion battery is placed, which comprises an electrode composition containing electrode active material particles and a frame-shaped member annularly arranged so as to surround the electrode composition. a conveying unit that conveys the entire conveying substrate; a covering film supply unit that covers a surface of the lithium ion battery electrode material opposite to the surface on which the conveying substrate is arranged with a covering film; By depressurizing the space sandwiched between the covering film and the fixing portion for fixing the electrode composition by the transfer substrate, the frame-shaped member, and the covering film, and the fixed electrode composition on the covering film side. By applying pressure from the pressure molding unit for pressure molding the electrode composition, the pressure in the space sandwiched between the transfer substrate and the coating film is released, and the coating film is used for the lithium ion battery. a separation unit that separates from the electrode material, and the transfer substrate is transported by the transport unit for processing by the coating film supply unit, processing by the fixing unit, processing by the pressure molding unit, and processing by the separation unit. An apparatus for producing a lithium ion battery electrode, characterized in that it is continuously performed while, and an electrode composition containing electrode active material particles, and a frame shape arranged in a ring so as to surround the electrode composition. a conveying step of placing a lithium ion battery electrode material consisting of a member on a conveying substrate and conveying the conveying substrate together, and a side opposite to the surface of the lithium ion battery electrode material on which the conveying substrate is arranged The electrode composition is fixed by the transport substrate, the frame-shaped member, and the coating film by depressurizing the space sandwiched between the transport substrate and the coating film in a coating step of covering the surface of the substrate with a coating film. A fixing step, a pressure molding step of pressure-molding the electrode composition by pressing the fixed electrode composition from the coating film side, and a space sandwiched between the transfer substrate and the coating film. and a separation step of separating the coating film from the lithium ion battery electrode material while releasing the reduced pressure of the lithium ion The present invention relates to a method for producing a lithium-ion battery electrode, which is characterized by continuously carrying out a battery electrode material while conveying it.

According to the present invention, it is possible to suppress the occurrence of cracks and chips in the electrode layer, suppress the deterioration of the moldability of the electrode composition, shorten the pressure adjustment time, and reduce the manufacturing cost. A manufacturing method and its manufacturing apparatus can be provided.

FIG. 1 is a perspective view schematically showing an example of a method for manufacturing a lithium ion battery electrode using a lithium ion battery electrode manufacturing apparatus. FIG. 2 is a cross-sectional view along line XX in FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2. FIG. 4 is a cross-sectional view taken along the line BB in FIG. 2. FIG. FIG. 5 is a sectional view taken along line CC in FIG. FIG. 6 is a cross-sectional view taken along line DD in FIG. FIG. 7 is a cross-sectional view taken along line EE in FIG. FIG. 8 is a cross-sectional view schematically showing another example of an electrode material for lithium ion batteries. FIG. 9 is a cross-sectional view schematically showing another example of a lithium ion battery electrode.

The present invention will be described in detail below.
In addition, in this specification, when describing a lithium ion battery, the concept includes a lithium ion secondary battery.

[Manufacturing equipment for lithium-ion battery electrodes]
An apparatus for producing a lithium ion battery electrode is equipped with an electrode material for a lithium ion battery, which comprises an electrode composition containing electrode active material particles and a frame-shaped member annularly arranged so as to surround the electrode composition. a conveying unit that conveys the placed conveying substrate together with the conveying substrate; and a covering film supplying unit that covers the surface of the lithium ion battery electrode material opposite to the surface on which the conveying substrate is arranged with a covering film. a fixing portion for fixing the electrode composition by the transfer substrate, the frame-shaped member, and the covering film by depressurizing the space sandwiched between the transfer substrate and the covering film; and the fixed electrode composition. By pressing the object from the side of the coating film, the vacuum in the space sandwiched between the pressure molding unit for pressure molding the electrode composition, the transfer substrate, and the coating film is released, and the coating film is released. from the lithium ion battery electrode material, the processing by the coating film supply unit, the processing by the fixing unit, the processing by the pressure molding unit, and the processing by the separation unit are performed by the conveying unit is carried out continuously while transporting the transport substrate.

By using the apparatus for manufacturing a lithium ion battery electrode, the following method for manufacturing a lithium ion battery electrode can be easily carried out.

[Method for producing electrode for lithium ion battery]
A method for producing a lithium ion battery electrode includes transporting a lithium ion battery electrode material comprising an electrode composition containing electrode active material particles and a frame-shaped member annularly arranged so as to surround the electrode composition. A carrying step of placing the electrode material on a substrate and carrying the carrying substrate together, a covering step of covering a surface of the electrode material for a lithium ion battery opposite to the surface on which the carrying substrate is arranged, with a coating film, and A fixing step of fixing the electrode composition by the transfer substrate, the frame-shaped member, and the coating film by depressurizing the space sandwiched between the transfer substrate and the coating film; and fixing the fixed electrode composition. By applying pressure from the side of the coating film, the space sandwiched between the pressure molding step of pressure molding the electrode composition, the transfer substrate, and the coating film is released from the reduced pressure, and the coating film is removed from the coating film. and a separation step of separating from the lithium ion battery electrode material, and the covering step, the fixing step, the pressure molding step and the separation step are continuously performed while conveying the lithium ion battery electrode material. , characterized in that

In the method for producing a lithium-ion battery electrode, in the fixing step, the electrode composition is fixed by the carrier substrate, the frame-shaped member and the coating film by reducing the pressure in the space sandwiched between the carrier substrate and the coating film. Since the frame-shaped member is arranged so as to surround the electrode composition, the shape of the electrode composition after the pressure molding process corresponds to the inner shape of the frame-shaped member. Therefore, by adjusting the shape of the frame-shaped member, processing of the electrode composition after pressure molding becomes unnecessary, and cracking and chipping can be prevented. Further, since the space sandwiched between the transfer substrate and the coating film is decompressed in the covering step, air is suppressed from being compressed in the pressure molding step. Furthermore, since the space that must be decompressed in the fixing step is a small space sandwiched between the transfer substrate and the coating film, the pressure adjustment time can be shortened, and the manufacturing cost can be reduced.

FIG. 1 is a perspective view schematically showing an example of a method for manufacturing a lithium ion battery electrode using a lithium ion battery electrode manufacturing apparatus, and FIG. 2 is a cross-sectional view taken along line XX in FIG. .
1 and 2 schematically show a method for producing a lithium ion battery electrode 1 from a lithium ion battery electrode material 1' using a lithium ion battery electrode production apparatus 100. FIG. The lithium ion battery electrode manufacturing apparatus 100 includes a belt conveyor 110 as a first conveying unit and an adsorption belt conveyor 120 as a second conveying unit for conveying the lithium ion battery electrode material 1 ′, and a coating film 60, a fixing portion 140, a pressure forming portion 150, and a separation portion 160. The suction belt conveyor 120 serves as the second conveying section as well as the fixed section 140 .

In the manufacturing method shown in FIGS. 1 and 2, the lithium ion battery electrode material 1′ is placed on the transfer substrate 10 and transferred together with the transfer substrate 10 (in FIG. ), the covering step (the position where the BB line is provided in FIG. 2), the fixing step (the position where the CC line is provided in FIG. 2), the pressure molding step (DD in FIG. 2) The position where the line is provided) and the separation step (the position where the EE line is provided in FIG. 2) are continuously performed.
The transfer substrate 10 and the lithium ion battery electrode material 1' are transferred in the directions of the arrows shown in FIGS.
That is, in the manufacturing apparatus 100, processing by the coating film supply unit 130 (coating step), processing by the fixing unit 140 (fixing step), processing by the pressure molding unit 150 (pressure molding step), and processing by the separation unit 160 (separation step) is continuously performed while the transfer substrate 10 is transferred by the first transfer unit 110 and the second transfer unit 120 . A control device (for example, a sequencer) (not shown) controls a transport unit (transport device) so that the processes in the coating process, the fixing process, the pressure molding process, and the separation process are continuously performed while transporting the transport substrate 10 . may be controlled, or the operator may manually transport the transport substrate 10 so as to continuously perform the above-described steps while transporting the transport substrate 10 .

In the conveying process, the covering process and the separating process, the lithium ion battery electrode material 1' and the conveying substrate 10 are conveyed using the belt conveyor 110, which is the first conveying section.
On the other hand, in the fixing process and the pressure molding process, the adsorption belt conveyor 120, which is the second transport section, is used to transport the lithium ion battery electrode material 1' and the transport substrate 10. As shown in FIG.
The first conveying section and the second conveying section are conveying sections in the apparatus for manufacturing a lithium ion battery electrode. In the present embodiment, a structure including a plurality of conveying units (first conveying unit and second conveying unit) is exemplified as the conveying unit in the lithium ion battery electrode manufacturing apparatus. Not limited. That is, the transport unit in this embodiment may be, for example, a single substrate transport device or a plurality of substrate transport devices as long as it has a function of transporting the transport substrate 10 so as to perform the above-described steps. , the configuration of which can be changed as appropriate.

Each step will be described in detail below.

[Conveyance process]
In the transporting step, the lithium ion battery electrode material is placed on the transport substrate and transported together with the transport substrate.
The lithium-ion battery electrode material may be placed directly on the transfer substrate, or may be placed on a base material different from the transfer substrate.

FIG. 3 is a cross-sectional view taken along the line AA in FIG. 2 and schematically shows an example of the transfer process.
As shown in FIG. 3, in the transporting step, the lithium ion battery electrode material 1′ is placed on the transport substrate 10 and transported together with the transport substrate 10. As shown in FIG.
The lithium-ion battery electrode material 1′ includes an electrode composition 30 containing electrode active material particles placed on a carrier substrate 10, and a frame-shaped member 20 annularly arranged to surround the electrode composition 30. Consists of

The order in which the electrode composition 30 and the frame-shaped member 20 are arranged on the transfer substrate 10 is not particularly limited. It is preferred to place the object 30 .

The lithium ion battery electrode material may be placed directly on the transfer substrate, or may be placed via another material.
Examples of the material arranged between the transfer substrate and the lithium ion battery electrode material include an electrode current collector.

The method of arranging the frame-shaped member on the transfer substrate is not particularly limited. Examples include a method of applying a body onto a carrier substrate and forming a frame-shaped member on the carrier substrate. Predetermined operations include, for example, heating and light irradiation.

Although the thickness of the electrode composition is not particularly limited, it is preferably equal to or greater than the thickness of the frame member.
The ratio of the thickness of the electrode composition to the thickness of the frame member is preferably 100% to 200%, more preferably 100% to 150%, even more preferably 110% to 130%.
When the frame-shaped member is difficult to deform, if the ratio of the thickness of the electrode composition to the thickness of the frame-shaped member is less than 100%, the electrode composition can be sufficiently pressure-molded in the pressure-molding step described later. Sometimes you can't.

When the ratio of the electrode composition to the thickness of the frame-shaped member exceeds 100%, the electrode composition protrudes from the frame-shaped member. Since the electrode composition is fixed in the packaging material during the vacuum packaging process, the electrode composition overflowing from the frame member does not pose a problem in the pressure molding process.

The frame-shaped member preferably contains polyolefin having a melting point of 75 to 90°C.

The polyolefin having a melting point of 75 to 90° C. may or may not have a polar group in its molecule.
Polar groups include hydroxy group (--OH), carboxyl group (--COOH), formyl group (--CHO), carbonyl group (=CO), amino group (--NH ₂ ), thiol group (--SH), 1, 3-dioxo-3-oxypropylene group and the like.
Whether or not the polyolefin has a polar group can be confirmed by analyzing the polyolefin by Fourier transform infrared spectroscopy (FT-IR) or nuclear magnetic resonance spectroscopy (NMR).

Examples of polyolefins having a melting point of 75 to 90° C. include Mersen (registered trademark) G (melting point: 77° C.) manufactured by Tosoh Corporation, Admer XE070 (melting point: 84° C.) manufactured by Mitsui Chemicals, Inc., and the like.
Mersen (registered trademark) G manufactured by Tosoh Corporation is an example of a resin having a polar group, and Admer XE070 manufactured by Mitsui Chemicals, Inc. is an example of a resin having no polar group.

The frame member may contain a non-conductive filler in addition to polyolefin having a melting point of 75 to 90°C.
Non-conductive fillers include inorganic fibers such as glass fibers and inorganic particles such as silica particles.

A part of the frame-shaped member may be composed of a heat-resistant annular support member.
If a portion of the frame-shaped member is composed of the heat-resistant annular support member, the mechanical strength and heat resistance of the frame-shaped member can be improved.

Since the heat-resistant annular support member has low adhesiveness to the electrode current collector and the separator, it is preferable that the heat-resistant annular support member is arranged in the central portion in the thickness direction of the frame-shaped member.
In this case, the layer containing polyolefin having a melting point of 75 to 90° C., the heat-resistant annular support member, and the layer containing polyolefin having a melting point of 75 to 90° C., which have the same planar shape, are arranged on the transfer substrate side (electrode current collector side). ) are preferably arranged in this order. With the above configuration, it is possible to increase the adhesiveness to the electrode current collector and the separator while imparting mechanical strength and heat resistance to the frame-shaped member.

The heat-resistant annular support member preferably contains a heat-resistant resin composition with a melting temperature of 150°C or higher, more preferably a heat-resistant resin composition with a melting temperature of 200°C or higher.
Since the heat-resistant annular support member contains a heat-resistant resin composition having a melting temperature of 150° C. or higher, the frame-shaped member is less likely to be deformed by heat.
The melting temperature (simply referred to as melting point) of the heat-resistant resin composition is measured by differential scanning calorimetry in accordance with JIS K7121-1987.

As the resin constituting the heat-resistant resin composition, thermosetting resin (epoxy resin, polyimide, etc.), engineering resin [polyamide (nylon 6 melting temperature: about 230 ° C., nylon 66 melting temperature: about 270 ° C., etc.), polycarbonate (also referred to as PC, melting temperature: about 150 ° C.) and polyether ether ketone (also referred to as PEEK, melting temperature: about 330 ° C.), etc.] and high-melting thermoplastic resins {polyethylene terephthalate (also referred to as PET, melting temperature: about 250 ° C.), polyethylene naphthalate (also referred to as PEN, melting temperature: about 260° C.) and high melting point polypropylene (melting temperature: about 160-170° C.)} and the like.
The high-melting point thermoplastic resin refers to a thermoplastic resin having a melting temperature of 150° C. or higher as measured by differential scanning calorimetry in accordance with JIS K7121-1987.

The heat-resistant resin composition desirably contains at least one resin selected from the group consisting of polyamide, polyethylene terephthalate, polyethylene naphthalate, high melting point polypropylene, polycarbonate and polyetheretherketone.

The heat resistant resin composition may contain a filler.
By including a filler in the heat-resistant resin composition, the melting temperature can be improved.
Examples of the filler include inorganic filler such as glass fiber, carbon fiber, and the like.
Examples of the heat-resistant resin composition containing a filler include glass fibers impregnated with an epoxy resin before curing and then cured (also referred to as glass epoxy), carbon fiber reinforced resins, and the like.

The distance between the outer shape and the inner shape when the frame-like member is viewed from above is also called the width of the frame-like member.
Although the width of the frame member is not particularly limited, it is preferably 3 to 20 mm.
If the width of the frame-shaped member is less than 3 mm, the mechanical strength of the frame-shaped member is insufficient, and the electrode composition may leak out of the frame-shaped member. On the other hand, if the width of the frame-shaped member exceeds 20 mm, the proportion of the electrode composition may decrease, resulting in a decrease in energy density.

Although the thickness of the frame-shaped member is not particularly limited, it is preferably 0.1 to 10 mm.

Electrode active material particles include positive electrode active material particles and negative electrode active material particles.
An electrode composition using positive electrode active material particles as electrode active material particles is also referred to as a positive electrode composition, and an electrode composition using negative electrode active material particles as electrode active material particles is also referred to as a negative electrode composition.
A frame-shaped member that annularly surrounds the positive electrode composition is also referred to as a positive electrode frame-shaped member, and a frame-shaped member that annularly surrounds the negative electrode composition is also referred to as a negative electrode frame-shaped member.

Examples of positive electrode active material particles include composite oxides of lithium and transition metals {composite oxides containing one type of transition metal (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 metal elements [for example, LiM _a M′ _b M″ _c O ₂ (M, M′ and M″ are different transition metals _element and _satisfies a _{+ b + c} = ₁ . ₄ ), 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), and two or more of them may be used in combination.
The lithium-containing transition metal phosphate may have a transition metal site partially substituted with another transition metal.

Examples of the negative electrode active material particles include carbon-based materials [graphite, non-graphitizable carbon, amorphous carbon, baked resin bodies (for example, carbonized by baking phenol resin and furan resin, etc.), cokes (for example, pitch coke, Needle coke and petroleum coke, etc.) and carbon fiber, etc.], silicon-based materials [silicon, silicon oxide (SiOx), silicon-carbon composites (carbon particles whose surface is coated with silicon and / or silicon carbide, silicon particles or silicon oxide particles coated with carbon and/or silicon carbide, silicon carbide, etc.) and silicon alloys (silicon-aluminum alloys, silicon-lithium alloys, silicon-nickel alloys, silicon-iron alloys, silicon-titanium alloys, silicon-manganese alloys, silicon-copper alloys and silicon-tin alloys, etc.], conductive polymers (e.g., polyacetylene and polypyrrole, etc.), metals (tin, aluminum, zirconium, titanium, etc.), metal oxides (titanium oxide and lithium-titanium oxide, etc.), metal alloys (eg, lithium-tin alloys, lithium-aluminum alloys, lithium-aluminum-manganese alloys, etc.), and mixtures thereof with carbonaceous materials.
Of the negative electrode active material particles, those not containing lithium or lithium ions inside may be subjected to a pre-doping treatment in which lithium or lithium ions are contained in part or all of the negative electrode active material particles in advance.

Among these, carbon-based materials, silicon-based materials, and mixtures thereof are preferable from the viewpoint of battery capacity and the like. As the carbon-based material, graphite, non-graphitizable carbon, and amorphous carbon are more preferable, and as the silicon-based material, , silicon oxide and silicon-carbon composites are more preferred.

The average particle size of the electrode active material particles is preferably 5 to 200 μm.
The average particle size of the electrode active material particles means the particle size (Dv50) at an integrated value of 50% in the particle size distribution determined by the microtrack method (laser diffraction/scattering method). The microtrack method is a method of obtaining a particle size distribution by utilizing scattered light obtained by irradiating particles with laser light. For the measurement of the volume average particle size, a laser diffraction/scattering type particle size distribution analyzer [Microtrac manufactured by Microtrac Bell Co., Ltd., etc.] can be used.

The electrode active material particles may be coated active material particles in which at least part of the surface is coated with a coating layer containing a polymer compound.
When the periphery of the electrode active material particles is covered with the coating layer, the volume change of the electrode is moderated, and the expansion of the electrode can be suppressed.
The coated active material particles in the case of using positive electrode active material particles as the electrode active material particles are referred to as coated positive electrode active material particles, and the coated active material particles in the case of using negative electrode active material particles as the electrode active material particles are referred to as coated negative electrodes. They are called active material particles.

As the polymer compound constituting the coating layer (also referred to as a coating polymer compound), those described as resins for coating non-aqueous secondary battery active materials in JP-A-2017-054703 can be suitably used. .

The coating layer may contain a conductive aid, which will be described later, if necessary.

The weight ratio of the coating polymer compound contained in the electrode composition is preferably 0.1 to 10% by weight based on the weight of the electrode composition.
When the content of the coating polymer compound contained in the electrode composition is less than 0.1% by weight based on the weight of the electrode composition, the content of the coating polymer compound contained in the electrode composition is low. If the thickness is too high, cracking of the electrode may occur, or the formability may deteriorate.
On the other hand, when the content of the coating polymer compound contained in the electrode composition exceeds 10% by weight based on the weight of the electrode composition, the content of the coating polymer compound contained in the electrode composition is Too much may increase the electrical resistance.

The weight ratio of the electrode active material particles contained in the electrode composition is preferably 70 to 95% by weight based on the weight of the electrode composition.
When the electrode active material particles are coated active material particles, the coating layer forming the coated active material particles is not included in the weight of the electrode active material particles.

The electrode composition may contain, in addition to the electrode active material particles, a conductive aid, a solution-drying type known binder for electrodes (also referred to as a binder), and an adhesive resin. It may also contain an electrolyte, a solvent, and the like that constitute the non-aqueous electrolyte used in the manufacture of the lithium ion battery.
However, the electrode composition preferably does not contain a known electrode binder.

The conductive aid is selected from materials having conductivity.
Specifically, metal [nickel, aluminum, stainless steel (SUS), silver, copper, titanium, etc.], carbon [graphite and carbon black (acetylene black, ketjen black, furnace black, channel black, thermal lamp black, etc.), etc. ], and mixtures thereof, but are not limited thereto.
One of these conductive aids may be used alone, or two or more thereof may be used in combination. Also, alloys or metal oxides thereof may be used. From the viewpoint of electrical stability, aluminum, stainless steel, carbon, silver, copper, titanium and mixtures thereof are preferred, silver, aluminum, stainless steel and carbon are more preferred, and carbon is even more preferred. These conductive aids may also be those obtained by coating a conductive material (a metal material among the materials of the conductive aids described above) around a particulate ceramic material or a resin material by plating or the like.

The average particle size of the conductive aid is not particularly limited, but from the viewpoint of the electrical characteristics of the battery, it is preferably 0.01 to 10 μm, more preferably 0.02 to 5 μm. It is more preferably 0.03 to 1 μm. In this specification, "particle size" means the maximum distance L among the distances between any two points on the contour line of the conductive aid. The value of "average particle size" is the average value of the particle size of particles observed in several to several tens of fields of view using an observation means such as a scanning electron microscope (SEM) or a transmission electron microscope (TEM). The calculated value shall be adopted.

The shape (form) of the conductive aid is not limited to a particle form, and may be in a form other than the particle form, and may be in a form that is practically used as a so-called filler-based conductive material such as carbon nanotubes.

The conductive aid may be a conductive fiber having a fibrous shape.
Examples of conductive fibers include carbon fibers such as PAN-based carbon fibers and pitch-based carbon fibers, conductive fibers obtained by uniformly dispersing highly conductive metals and graphite in synthetic fibers, and metals such as stainless steel. Examples include fibrillated metal fibers, conductive fibers obtained by coating the surface of organic fibers with metal, and conductive fibers obtained by coating the surfaces of organic fibers with a resin containing a conductive substance. Among these conductive fibers, carbon fibers are preferred. A polypropylene resin in which graphene is kneaded is also preferable.
When the conductive aid is conductive fiber, the average fiber diameter is preferably 0.1 to 20 μm.

The weight ratio of the conductive aid contained in the electrode composition is preferably 0 to 5% by weight based on the weight of the electrode composition.

Known solution-drying binders for electrodes include starch, polyvinylidene fluoride (PVdF), polyvinyl alcohol (PVA), carboxymethylcellulose (CMC), polyvinylpyrrolidone (PVP), polytetrafluoroethylene (PTFE), styrene-butadiene. rubber (SBR), polyethylene (PE), polypropylene (PP), and the like.
However, the content of the known electrode binder is preferably 2.0% by weight or less based on the weight of the entire electrode composition.

The weight ratio of the known electrode binder contained in the electrode composition is preferably 0 to 2% by weight, more preferably 0 to 0.5% by weight, based on the weight of the electrode composition.

The electrode composition preferably contains an adhesive resin instead of a known electrode binder.
When the electrode composition contains the known solution-drying type electrode binder, it is necessary to integrate by performing a drying step after forming the compression molded body, but when it contains an adhesive resin, The electrode composition can be integrated with a slight pressure at room temperature without a drying step. It is preferable not to carry out the drying step, because the shrinkage and cracking of the compression-molded body due to heating do not occur.

The solution-drying type electrode binder is one that evaporates the solvent component to dry and solidify, thereby firmly fixing the electrode active material particles to each other. On the other hand, the tacky resin means a resin having tackiness (property of adhering by applying slight pressure without using water, solvent, heat, etc.).
The solution-drying type electrode binder and adhesive resin are different materials.

As the adhesive resin, a polymer compound constituting the coating layer (such as a non-aqueous secondary battery active material coating resin described in JP-A-2017-054703) is mixed with a small amount of an organic solvent to obtain a glass transition. Those whose temperature is adjusted to room temperature or lower, and those described as adhesives in JP-A-10-255805 and the like can be preferably used.

The weight ratio of the adhesive resin contained in the electrode composition is preferably 0 to 2% by weight based on the weight of the electrode composition.

The total weight ratio of the resin components (coating polymer compound, electrode binder and adhesive resin) contained in the electrode composition is preferably 0.1 to 10% by weight.

_As the _{electrolyte ,} those used in known non _{- aqueous electrolytes} can be used. ₂ ) Lithium salts of organic acids such as LiN _{( C2F5SO2} ) _{2 , LiC(CF3SO2)3 , and the like} . Among these, LiPF ₆ is preferable from the viewpoint of battery output and charge-discharge cycle characteristics.

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

The type of transfer substrate on which the lithium ion battery electrode material is placed in the transfer step is not particularly limited, but may be an electrode current collector. When the transfer substrate is an electrode current collector, the lithium ion battery electrode material is placed on the electrode current collector, so that when manufacturing a lithium ion battery using the lithium ion battery electrode material Moreover, the step of bringing the electrode composition into contact with the electrode current collector can be omitted.
In addition to the electrode current collector, a resin film, metal foil, or the like may be used as the carrier substrate.

When a transfer substrate other than the electrode current collector is used, the electrode current collector may be further arranged between the transfer substrate, the electrode current collector, and the frame-shaped member.

Examples of electrode current collectors include positive electrode current collectors and negative electrode current collectors.

Materials constituting the positive electrode current collector include copper, aluminum, titanium, stainless steel, nickel, calcined carbon, conductive polymer, conductive glass, and the like. A resin current collector made of a conductive agent and a resin may also be used as the positive electrode current collector.

Materials constituting the negative electrode current collector include metal materials such as copper, aluminum, titanium, stainless steel, nickel, and alloys thereof. Among them, copper is preferable from the viewpoint of weight reduction, corrosion resistance, and high conductivity. The negative electrode current collector may be a current collector made of baked carbon, a conductive polymer, a conductive glass, or the like, or a resin current collector made of a conductive agent and a resin.

For both the positive electrode current collector and the negative electrode current collector, as the conductive agent that constitutes the resin current collector, the same conductive aid contained in the electrode composition can be preferably used.
Resins constituting the resin current collector include polyethylene (PE), polypropylene (PP), polymethylpentene (PMP), polycycloolefin (PCO), polyethylene terephthalate (PET), polyethernitrile (PEN), polytetra Fluoroethylene (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, and polyethylene (PE), polypropylene (PP) and polymethylpentene are more preferred. (PMP).

The shape of the transfer substrate is not particularly limited, but it is the same as or substantially similar to the outer shape of the frame-shaped member in a plan view, and is larger than the outer shape of the electrode composition arranged inside the frame-shaped member. It is preferably large and smaller than the outer shape of the frame-shaped member.

[Coating process]
In the coating step, the surface of the lithium ion battery electrode material opposite to the surface on which the transfer substrate is arranged is covered with a coating film.

FIG. 4 is a cross-sectional view taken along the line BB in FIG. 2 and schematically shows an example of the coating process.
As shown in FIGS. 2 and 4, in the coating step, a coating film 60 is sent out by a roller 130, which is a coating film supply unit, so that the surface of the lithium ion battery electrode material 1' on which the transfer substrate 10 is arranged and the is covered with a covering film 60 on the opposite side 1a'.
In FIGS. 1 and 2, the long covering film 60 covers the plurality of lithium ion battery electrode materials 1', but one lithium ion battery electrode material may be covered with one covering film. .

In the covering step, the lithium ion battery electrode material 1' is covered with the covering film 60 so that the covering film 60 is in contact with all surfaces other than the surface in contact with the transfer substrate 10 of the lithium ion battery electrode material 1'. is preferred.

The delivery speed of the coating film 60 is not particularly limited, but from the viewpoint of suppressing wrinkles of the coating film 60 in contact with the lithium ion battery electrode material 1 ′, the transport speed of the lithium ion battery electrode material 1 ′ and the coating film 60 It is preferable that the delivery speed is matched.

When covering the lithium ion battery electrode material with a covering film, for example, a guide for adjusting the position of the covering film may be provided. Also, a jig or the like for adjusting the position of the transfer substrate may be used.

Although the material constituting the covering film is not particularly limited, polypropylene and the like can be mentioned.

[Fixation process]
In the fixing step, the electrode composition is fixed by the transfer substrate, the frame-shaped member and the cover film by reducing the pressure in the space sandwiched between the transfer substrate and the cover film.

FIG. 5 is a cross-sectional view taken along the line CC in FIG. 2 and schematically shows an example of the fixing process.
As shown in FIG. 5, in the fixing step, the space sandwiched between the transfer substrate 10 and the coating film 60 is depressurized, so that the electrode material for a lithium ion battery is pushed from the outside by the atmospheric pressure, and the transfer substrate 10 and the electrode material are pressed together. While the position of the lithium ion battery electrode material 1 ′ is fixed, the electrode composition 30 is fixed by the transfer substrate 10 , the frame member 20 and the coating film 60 .

In FIG. 5, the suction belt constituting the suction belt conveyor 120 has a through hole (not shown) in the thickness direction, and the surface of the suction belt on the side where the transfer substrate 10 is not arranged is inside the decompression container 145. It communicates with the space 146 . When the space 146 in the decompression container 145 is decompressed by a decompressor (not shown) such as a vacuum pump, the space sandwiched between the transfer substrate 10 and the coating film 60 is decompressed through the through holes provided in the adsorption belt. be done. Arrows in FIG. 5 schematically show how gas is sucked through the suction belt. As a result, the electrode composition 30 is fixed by the transfer substrate 10 , the frame member 20 and the coating film 60 .
The combination of the adsorption belt conveyor 120 and the decompression container 145 provided with the decompressed space 146 provided on the opposite side of the adsorption belt from the surface on which the transfer substrate 10 is arranged is the lithium gas shown in FIGS. It is also the fixing part 140 that constitutes the ion battery electrode manufacturing apparatus 100 .

The degree of vacuum in the space sandwiched between the carrier substrate and the coating film is preferably −50 kPa or less, more preferably −70 kPa or less, and even more preferably −80 kPa or less.
If the degree of vacuum exceeds −70 kPa, the force for fixing the electrode composition is not sufficient, and the electrode composition may flow out of the frame-shaped member in the pressure molding step described later. That is, it is preferable that the reachable degree of vacuum of the fixed portion is -70 kPa or less.

The space required to be decompressed in the fixing step is a small space sandwiched between the transfer substrate and the coating film. Therefore, it is possible to reduce the pressure in the space sandwiched between the transfer substrate and the covering film in a time shorter than the time required to reduce the pressure in the pressure molding apparatus as a whole.

[Pressure molding process]
In the pressure-molding step, the electrode composition fixed in the fixing step is pressure-molded by applying pressure from the covering film side.

FIG. 6 is a cross-sectional view taken along line DD in FIG. 2, showing an example of the pressure molding process.
As shown in FIG. 6, in the pressure molding step, the electrode composition 30 fixed in the fixing step is pressed from the side of the covering film 60 by a roll press 150, which is a pressure molding unit, to form a pressure-molded electrode. It is referred to as composition 35.
At this time, since the electrode composition 30 is fixed by the carrier substrate 10, the frame-shaped member 20 and the covering film 60, air is not compressed during pressure molding, and the moldability of the electrode composition is improved.
As shown in FIG. 6, it is preferable to continue depressurizing the space sandwiched between the transfer substrate and the covering film even in the pressure molding step.

The method of pressure-molding the lithium ion battery electrode material is not particularly limited, and may be flat press or roll press, but roll press is preferred.
The distance between the press roller used in the roll press and the transfer substrate is set to the volume average particle size of the electrode active material particles from the viewpoint of alleviating the rise of the intense pressing force that is instantaneously generated when the roller rides on the starting end of the frame-shaped member. It is preferably at least three times the diameter. Also, the distance between the press roller and the transfer substrate is preferably 20 mm or less.

In the pressure molding step, the lithium ion battery electrode material may be heated.
When the carrier substrate is an electrode current collector, it is not necessary to separate the lithium ion battery electrode material from the carrier substrate. Therefore, by heating the lithium-ion battery electrode material in the pressure molding step, the frame-shaped member and the carrier substrate that serves as the electrode current collector can be bonded.

The heating temperature is preferably higher than the melting point of the resin forming the frame-shaped member and lower than the temperature that adversely affects the coating film.

[Separation process]
In the separation step, the pressure in the space sandwiched between the transfer substrate and the coating film is released, and the coating film is separated from the lithium ion battery electrode material.

FIG. 7 is a cross-sectional view taken along line EE in FIG. 2, showing the state immediately after the separation process.
As shown in FIGS. 1 and 2, after the pressure molding process, the lithium ion battery electrode material 1′ and the transfer substrate 10 move onto the belt conveyor 110, thereby being sandwiched between the transfer substrate 10 and the covering film 60. The decompression of the space is released. After that, the cover film 60 is separated from the lithium ion battery electrode material 1′ by the roller 160, which is a separation unit, so that the pressure-molded electrode composition 35 and the frame surrounding it are formed as shown in FIG. The lithium ion battery electrode 1 made of the shaped member 20 is obtained in a state of being placed on the carrier substrate 10 .

A lithium ion battery electrode is manufactured through the above steps.
In the case of producing a lithium ion battery using the lithium ion battery electrode produced by the method for producing a lithium ion battery electrode of the present invention, for example, in combination with an electrode serving as a counter electrode via a separator, the electrode is added to the electrode composition. A lithium ion battery can be manufactured by connecting current collectors, adding an electrolytic solution to an electrode composition and a separator as necessary, and housing the mixture in a battery outer package.
When the transfer substrate used in manufacturing the electrode material for a lithium ion battery is an electrode current collector, the step of connecting the electrode current collector to the electrode composition is omitted by not removing the transfer substrate. be able to.

In the method for producing a lithium ion battery electrode of the present invention, the transfer substrate is the first electrode current collector, and the lithium ion battery electrode material is the first electrode current collector and the first electrode current collector. A first electrode composition containing first electrode active material particles disposed on the body, and a first electrode current collector disposed on the first electrode composition arranged in a ring so as to surround the periphery of the first electrode composition a first frame-shaped member, a separator arranged on the first electrode composition and the first frame-shaped member, and a first electrode composition arranged to face the first electrode composition via the separator a second electrode composition containing two electrode active material particles; a second frame-shaped member arranged annularly so as to surround the second electrode composition; and a second electrode current collector disposed on the frame-shaped member.

One of the first electrode active material particles and the second electrode active material particles is a positive electrode active material particle, and the other is a negative electrode active material particle.

Another example of the lithium ion battery electrode material will be described with reference to FIGS. 8 and 9. FIG.
FIG. 8 is a cross-sectional view schematically showing another example of an electrode material for lithium ion batteries.
The lithium-ion battery electrode material 2' shown in FIG. a separator 40, a negative electrode composition 33 facing the positive electrode composition 31 via the separator 40, a negative electrode frame-shaped member 23 covering the periphery of the negative electrode composition 33, and a negative electrode placed on the negative electrode composition 33. It consists of a current collector 53 .

The thickness of the positive electrode composition 31 is greater than the thickness of the positive electrode frame member 21 . Moreover, the thickness of the negative electrode composition 33 is thicker than the thickness of the negative electrode frame-shaped member 32 . Therefore, the positive electrode frame-shaped member 21 is not in contact with either the transfer substrate 11 (positive electrode current collector 51 ) or the separator 40 . Moreover, the negative electrode frame member 23 is not in contact with either the separator 40 or the negative electrode current collector 53 .

In the lithium ion battery electrode material 2 ′ shown in FIG. 8 , the separator 40 is not in contact with the positive electrode frame member 21 and the negative electrode frame member 23 . Such a lithium ion battery electrode material is produced, for example, by arranging the positive electrode frame-shaped member 21 and the positive electrode composition 31 on the carrier substrate 11 (positive electrode current collector 51) and ), after placing the negative electrode frame-shaped member 23 and the negative electrode composition 33 on another base material, the separator 40 is placed from above and one side (negative electrode side) of the lithium ion battery electrode material is It can be obtained by placing it on one side of the initially prepared electrode material for a lithium ion battery so that the separator 40 is on the lower side (positive electrode side).

In the lithium ion battery electrode manufacturing apparatus 100 shown in FIGS. 1 and 2, when the lithium ion battery electrode material 2' shown in FIG. 8 is used instead of the lithium ion battery electrode material 1', in the coating step, The surface of the lithium-ion battery electrode material 2' opposite to the surface on which the transfer substrate 11 (positive electrode current collector 51) is arranged is covered with a coating film. Therefore, in the fixing step, the pressure in the space sandwiched between the coating film and the transfer substrate 11 (positive electrode current collector 51) is reduced. Therefore, the positive electrode composition 31 and the negative electrode composition 33 are fixed by the transfer substrate 11 and the coating film, and the positive electrode frame-shaped member 21 or the negative electrode frame-shaped member 23, respectively.

FIG. 9 is a cross-sectional view schematically showing another example of a lithium ion battery electrode.
1 and 2, by using the lithium ion battery electrode material 2' shown in FIG. 8 instead of the lithium ion battery electrode material 1', the lithium ion battery electrode material 2 shown in FIG. is obtained.
The lithium ion battery electrode 2 includes a positive electrode current collector 51 used as a carrier substrate 11, a pressure-molded positive electrode composition 36 placed on the positive electrode current collector 51, and a pressure-molded positive electrode. A positive electrode frame-shaped member 21 covering the periphery of the composition 36, a separator 40, a pressure-molded negative electrode composition 38 facing the pressure-molded positive electrode composition 36 via the separator 40, and a pressure-molded and a negative electrode current collector 53 arranged on the pressure-molded negative electrode composition 38 and the negative electrode frame-shaped member 23 . The pressure-molded positive electrode composition 36 and the pressure-molded negative electrode composition 38 are electrically connected to the positive current collector 51 and the negative current collector 53, respectively.
By using such a lithium ion battery electrode 2, the lithium ion battery is manufactured by omitting the step of combining the lithium ion battery electrode with the counter electrode and the step of connecting the electrode current collector to the electrode composition. be able to.
In the embodiment shown in FIGS. 8 and 9, the first electrode current collector is the positive electrode current collector, and the first frame-shaped member is the positive electrode frame-shaped member. The second electrode current collector is the negative electrode current collector, and the second frame-shaped member is the negative electrode frame-shaped member.

The positive electrode frame-shaped member and the negative electrode frame-shaped member preferably have substantially the same shape in plan view.

The method and apparatus for producing a lithium-ion battery electrode of the present invention are particularly useful as a method and apparatus for producing a lithium-ion battery electrode used in mobile phones, personal computers, hybrid vehicles, electric vehicles, and the like. is.

1, 2 Lithium ion battery electrodes 1′, 2′ Lithium ion battery electrode materials 10, 11 Transfer substrate 20 Frame-shaped member 21 Positive electrode frame-shaped member 23 Negative electrode frame-shaped member 30 Electrode composition 31 Positive electrode composition 33 Negative electrode composition 35 Pressure-molded electrode composition 36 Pressure-molded positive electrode composition 38 Pressure-molded negative electrode composition 40 Separator 51 Positive current collector 53 Negative current collector 60 Coating film 100 Preparation of electrodes for lithium ion batteries Device 110 First transport section (belt conveyor)
120 second conveying unit (adsorption belt conveyor)
130 Coating film feeder (roller)
140 Fixing part 145 Decompression container 146 Space 150 Pressure forming part (roll press)
160 separation unit (roller)

Claims (13)

a carrier substrate on which an electrode material for a lithium ion battery is placed, comprising an electrode composition containing electrode active material particles and a frame-shaped member annularly arranged so as to surround the electrode composition, together with the carrier substrate; a conveying unit for conveying;
a covering film supply unit covering a surface of the lithium ion battery electrode material opposite to the surface on which the transfer substrate is arranged with a covering film;
a fixing unit that fixes the electrode composition by the transfer substrate, the frame-shaped member, and the covering film by depressurizing the space sandwiched between the transfer substrate and the covering film;
A pressure-molding unit for pressure-molding the electrode composition by pressing the fixed electrode composition from the coating film side by a roll press ;
An apparatus for manufacturing a lithium ion battery electrode, comprising : 2. The lithium ion battery electrode according to claim 1, further comprising a separation unit for releasing the pressure reduction in the space sandwiched between the transfer substrate and the covering film and separating the covering film from the lithium ion battery electrode material. manufacturing device. The lithium ion battery according to claim 1 or 2, wherein the treatment by the coating film supply unit, the treatment by the fixing unit, and the treatment by the pressure molding unit are continuously performed while the transfer substrate is transferred by the transfer unit. Electrode manufacturing equipment. 4. The apparatus for manufacturing a lithium ion battery electrode according to claim 1 , wherein said transfer substrate is an electrode current collector. The transfer substrate is a suction belt,
4. The apparatus for manufacturing a lithium ion battery electrode according to claim 1 , wherein the fixing unit decompresses a space sandwiched between the adsorption belt and the covering film through through holes formed in the adsorption belt. . An electrode material for a lithium ion battery comprising an electrode composition containing electrode active material particles and a frame-shaped member annularly arranged so as to surround the electrode composition is placed on a carrier substrate, and the carrier substrate A transport process for transporting each
a covering step of covering a surface of the lithium ion battery electrode material opposite to the surface on which the transfer substrate is arranged with a covering film;
a fixing step of fixing the electrode composition by the transfer substrate, the frame-shaped member, and the covering film by depressurizing the space sandwiched between the transfer substrate and the covering film;
and a pressure molding step of pressure molding the electrode composition by pressing the fixed electrode composition from the coating film side by a roll press . Method. 7. The lithium ion battery electrode according to claim 6, wherein a separation step is performed to release the pressure reduction in the space sandwiched between the transfer substrate and the coating film and separate the coating film from the lithium ion battery electrode material. Production method. 8. The method for producing a lithium ion battery electrode according to claim 6, wherein the covering step, the fixing step and the pressure molding step are continuously performed while conveying the lithium ion battery electrode material. The method for producing a lithium ion battery electrode according to any one of claims 6 to 8 , wherein the transfer substrate is an electrode current collector. The transfer substrate is a suction belt,
The method for producing a lithium ion battery electrode according to any one of claims 6 to 8 , wherein in the fixing step, the space sandwiched between the adsorption belt and the covering film is decompressed through through holes formed in the adsorption belt. . 11. The method for producing a lithium ion battery electrode according to any one of claims 6 to 10 , wherein in said fixing step, the degree of vacuum in the space sandwiched between said transfer substrate and said coating film is -70 kPa or less. The method for producing a lithium ion battery electrode according to any one of claims 6 to 11 , wherein the electrode active material particles have an average particle size of 5 to 200 µm. The carrier substrate is a first electrode current collector,
The electrode material for a lithium ion battery comprises a first electrode composition containing first electrode active material particles arranged on the first electrode current collector, and arranged on the first electrode current collector. a first frame-shaped member arranged annularly so as to surround the first electrode composition, and a separator arranged on the first electrode composition and the first frame-shaped member; , a second electrode composition containing second electrode active material particles arranged to face the first electrode composition via the separator, and a second electrode composition surrounding the second electrode composition and a second electrode current collector disposed on the second electrode composition and the second frame-shaped member. A method for manufacturing an electrode for a lithium ion battery.

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