KR101786774B1 - Lithium-ion secondary battery manufacturing method, lithium-ion secondary battery manufacturing device, and lithium-ion secondary battery - Google Patents

Abstract

It is possible to prevent the formation of a mixed layer of the electrode material and the insulating material in the vicinity of the interface between the electrode material layer and the insulating material layer when the electrode layer of the lithium ion secondary battery is coated on the current collecting foil and the insulating material serving as the separator is coated on the electrode layer do. A step of applying an electrode material slurry on the surface of the current collector foil using a first coating part and a solidifying liquid containing a component for precipitating a binder component contained in the electrode material slurry are supplied to the electrode material slurry, A step of solidifying the surface layer of the re-slurry, a step of applying an insulating material slurry by using the second coating portion on the electrode material slurry in which the surface layer is solidified, and a step of drying the electrode material slurry and the insulating material slurry. As another means, it is also possible to adopt a method of manufacturing an electrode material (ES) comprising the steps of applying an electrode material (ES) containing a binder on the surface of a current collecting foil (EP) A step of applying an insulating material IF1 and a step of solidifying the electrode material ES by supplying a spray liquid LIQ containing a second component for depositing the binder to the electrode material ES, A step of drying the material ES and the insulating material IF1 is performed.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a lithium ion secondary battery, a method of manufacturing the same, a lithium ion secondary battery, a lithium ion secondary battery, a lithium ion secondary battery, a lithium ion secondary battery,

The present invention relates to a method of manufacturing a lithium ion secondary battery, an apparatus for manufacturing a lithium ion secondary battery, and a lithium ion secondary battery, and particularly relates to a lithium ion secondary battery having a positive electrode, a negative electrode, and a separator for electrically separating the positive electrode and the negative electrode. And a technology effective for application to the lithium ion secondary battery.

BACKGROUND ART With the development of portable electronic devices, small secondary batteries capable of being repeatedly charged are used as power sources for such portable electronic devices. Among them, a lithium ion secondary battery having a high energy density, a long cycle life, a low self-discharge property, and a high operating voltage has been attracting attention. Since the lithium ion secondary battery has the advantages described above, it has been widely used in portable electronic devices such as a digital camera, a notebook type personal computer, and a mobile phone.

In recent years, research and development of a large-sized lithium ion secondary battery capable of realizing a high capacity, a high output, and a high energy density as an electric vehicle battery and a power storage battery are underway. Particularly, in the automobile industry, development of a hybrid vehicle using both an engine (internal combustion engine) and a motor as an electric vehicle or a power source using a motor as a power source is under development to cope with environmental problems. Lithium ion secondary batteries have attracted attention as power sources for such electric vehicles and hybrid cars. Likewise, lithium ion secondary batteries are becoming increasingly important in applications such as solar power generation and power storage for effectively utilizing nighttime power. However, since the lithium ion secondary battery has high energy density due to its high operating voltage, it is considered that sufficient measures against abnormal heat generation due to an internal short circuit or an external short circuit are required.

The lithium ion secondary battery is a kind of non-aqueous electrolyte secondary battery and is a secondary battery in which lithium ions in the electrolyte take charge of electric conduction. Lithium metal oxide is used as the cathode material (active material), carbon material such as graphite is used as the anode material (active material), and an organic solvent such as ethylene carbonate and lithium hexafluorophosphate (LiPF ₆ ) Or the like is used. The lithium ion secondary battery includes, for example, a band-shaped positive electrode plate in which a positive electrode material is coated on a metal foil, a band-shaped negative electrode plate in which a metal foil is coated with a negative electrode material, and a separator for electrically separating the positive electrode plate and the negative electrode plate And has a stacked body in which the disaster is superimposed. This laminate is rolled so as to constitute an electrode winding body having a spiral shape in cross section in an outer can of the lithium ion secondary battery.

As a background art in this technical field, Patent Document 1 (Japanese Patent Application Laid-Open No. 2003-045491) is known. Patent Document 1 discloses a method in which a solution containing an anode electrode material-containing solution, an electrolyte material and an insulating material is applied to both surfaces of a cathode sheet-like article using a die coater having a slit for solution discharge, Thereby forming an electrode sheet shaped article. Likewise, a solution containing a negative electrode material-containing solution, an electrolytic substance and an insulating material is coated on both surfaces of a negative electrode sheet material by using a die coater, and then a negative electrode sheet material is formed through a heating process . Here, both electrode sheets of the positive electrode and the negative electrode are laminated to form an electrode winding body. Also disclosed are a secondary battery manufacturing method and an apparatus for producing a secondary battery in which an electrode winding body is formed by laminating both electrode sheet-like materials.

Patent Document 1 discloses a technique in which a positive electrode film and a negative electrode film are separately formed and a separator film is attached to the negative electrode film to laminate the positive electrode film on the negative electrode film with the separator to form an electrode winding . In this case, it is described that it is difficult to uniformly inject a solution-like electric field material into a current collector in which a plurality of electrode winding bodies are stacked, and that the number of manufacturing steps is increased.

Japanese Patent Application Laid-Open No. 2003-045491

The lithium ion secondary battery includes a positive electrode plate coated with a positive electrode active material on the surface of a current collector foil, a negative electrode plate coated with a negative electrode active material on the surface of the current collecting foil, and a plate-like separator for preventing contact between the positive electrode plate and the negative electrode plate And an electrode winding body. Here, it is conceivable to prepare the positive electrode plate, the negative electrode plate and the separator as separate parts, that is, separate parts. However, in this case, foreign matter invades into the gap between the positive electrode plate and the separator due to, for example, There arises a problem that the anode and the cathode are short-circuited.

On the other hand, a lithium ion secondary battery is formed by winding a negative electrode plate formed by sequentially coating a surface of a current collector foil with a positive electrode active material and a separator, and a negative electrode plate formed by sequentially coating a negative electrode active material and a separator on the surface of another current collector foil I can think. With such a lithium ion secondary battery, it is possible to prevent a metal foreign matter generated by cutting the positive electrode plate or the negative electrode plate from intruding between the positive electrode plate or the negative electrode plate and the separator.

However, when an electrode material slurry containing a positive electrode active material or a negative electrode active material is coated on the surface of the current collecting foil and coated with an insulating material slurry to be a separator continuously on the slurry, an electrode material and an insulating material Is formed. In this case, since the insulating material layer functioning as a separator becomes thin, short-circuiting between the positive electrode and the negative electrode tends to occur, thereby causing a problem that the reliability of the lithium ion secondary battery is deteriorated. As a structure for preventing the short circuit, it is conceivable to increase the thickness of the separator. However, in this case, it is difficult to miniaturize the lithium ion secondary battery.

Further, in the coating process of the electrode material of the lithium ion secondary battery, as described in Patent Document 1, a coating film is formed by applying an electrode material of positive electrode or negative electrode to the surface of the current collecting foil as a carrier material, It is conceivable to form an electrode plate by coating an insulating material as a separator. As a result, it is possible to prevent the occurrence of a short circuit problem caused by the foreign matter, and to improve the production efficiency and to make the manufacturing apparatus smaller.

However, when an electrode material of a positive electrode or a negative electrode is coated on the surface of the current collecting foil that is a carrier and a continuous insulating material as a separator is applied, a mixed layer of an electrode material and an insulating material is formed at the interface between the electrode material layer and the insulating material layer The layer of the insulating material functioning as the separator is thinned. As a result, a short circuit between the positive electrode and the negative electrode is apt to occur, thereby increasing the possibility of occurrence of defects, thereby causing a problem that the reliability of the lithium ion secondary battery is deteriorated. It is conceivable to increase the thickness of the separator as a structure for preventing the short circuit. In this case, however, it is difficult to miniaturize the lithium ion secondary battery.

The above objects and novel features of the present invention will become apparent from the description of the present specification and the accompanying drawings.

Outline of representative examples of embodiments disclosed in the present application will be briefly described as follows.

A method of manufacturing a lithium ion secondary battery according to a representative embodiment includes the steps of applying an electrode material slurry on the surface of a current collecting foil using a first coating part, and a step of forming a slurry containing a component for precipitating a binder component contained in the electrode material slurry Applying the first solidified liquid to the slurry of the electrode material to solidify the surface layer of the slurry of the electrode material, and applying the slurry of the insulating material to the electrode material slurry on which the surface layer is solidified using the second coating portion And a step of drying the electrode material slurry and the insulating material slurry.

A method of manufacturing a lithium ion secondary battery according to a representative embodiment includes the steps of applying an electrode material containing a binder on a surface of a current collecting foil and a step of forming an electrode material containing a first component for depositing the binder on the electrode material A step of applying an insulating material and a spray liquid containing a second component for depositing the binder to the electrode material to solidify the electrode material and a step of drying the electrode material and the insulating material.

In addition, a manufacturing apparatus for a lithium ion secondary battery according to a representative embodiment includes a first coating portion for coating an electrode material slurry on the surface of a current collecting foil, and a second coating portion for coating the electrode material slurry A first coating unit for applying a slurry of insulating material onto the electrode material slurry on which the surface layer is solidified and a second coating unit for coating the slurry on the surface of the electrode material slurry, A drying chamber for drying the slurry of the electrode material and the slurry of the insulating material, and a transporting portion for transporting the current collecting foil in the order of the first coating portion, the first coating layer, the second coating portion and the drying chamber.

In addition, a manufacturing apparatus for a lithium ion secondary battery according to a representative embodiment includes a first coating portion for applying an electrode material slurry containing a binder to the surface of a current collecting foil, and a second coating portion for applying a slurry A solidifying portion for solidifying the electrode material slurry by supplying a solidifying liquid containing a second coating portion for applying an insulating material slurry containing one component and a second component for depositing the binding material to the electrode material slurry, A drying chamber for drying the slurry and the slurry of the insulating material, and a conveying portion for conveying the current collecting foil in the order of the first coating portion, the second coating portion, the solidification portion and the drying chamber.

Effects obtained by representative ones of the inventions disclosed in the present application will be briefly described as follows.

According to the present invention, the reliability of the lithium ion secondary battery can be improved.

Further, according to the present invention, the performance of a lithium ion secondary battery can be improved.

1 is a schematic diagram showing an apparatus for manufacturing a lithium ion secondary battery according to Embodiment 1 of the present invention.
2 is a schematic view showing an apparatus for manufacturing a lithium ion secondary battery according to Embodiment 2 of the present invention.
3 is a sectional view of an electrode plate constituting a lithium ion secondary battery;
4 is a graph showing the relationship between the thickness of the mixed layer of each of the lithium ion secondary battery of the first embodiment of the present invention and the lithium ion secondary battery of the second comparative example and the conveying speed of the current collecting foil.
5 is a schematic view showing an apparatus for manufacturing a lithium ion secondary battery which is a first comparative example.
6 is a flow chart showing a manufacturing process of a lithium ion secondary battery which is the first comparative example.
7 is a schematic view showing an apparatus for producing a lithium ion secondary battery in a second comparative example.
8 is an enlarged sectional view showing an apparatus for producing a lithium ion secondary battery in a second comparative example.
9 is a schematic view showing an apparatus for manufacturing a lithium ion secondary battery according to Embodiment 3 of the present invention.
10 is a sectional view of an electrode plate constituting a lithium ion secondary battery.
11 is a graph showing the relationship between the thickness of the mixed layer of each of the lithium ion secondary battery of the third embodiment of the present invention and the lithium ion secondary battery of the second comparative example and the conveying speed of the current collecting foil.
12 is a schematic view showing a structure of a lithium ion secondary battery.
13 is a flow chart showing a manufacturing process of a lithium ion secondary battery which is a third comparative example.
14 is a schematic view showing an apparatus for producing a lithium ion secondary battery in a fourth comparative example.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, members having the same functions are denoted by the same reference numerals, and repetitive description thereof will be omitted. In the following embodiments, descriptions of the same or similar portions are not repeated in principle, except when particularly required.

The thickness referred to herein refers to the length of each structure in the direction perpendicular to the surface of the current collecting foil constituting the lithium ion secondary battery.

[Embodiment 1]

Hereinafter, a method and an apparatus for manufacturing a lithium ion secondary battery in this embodiment will be described with reference to Fig. Fig. 1 is a diagram showing the configuration of a one-side coated electrode plate production apparatus according to the present embodiment. That is, Fig. 1 is a schematic view showing a manufacturing apparatus of a lithium ion secondary battery in this embodiment.

1, the apparatus for manufacturing a lithium ion secondary battery according to the present embodiment includes an accumulating foil roll RL1 for discharging a current collecting foil EP, a take-up roll RL4). The current collecting foil EP which is a thin plate-like metal foil is conveyed while being supported by a plurality of rollers such as the rollers RL2 and RL3 between the collecting metal foil roll RL1 and the winding roll RL4. Here, since the current collecting foil EP is conveyed at a constant speed, the plurality of rollers are referred to as a roller conveyance system, that is, a conveyance section.

A spray nozzle NZ1 in the solidification chamber SD1, a die coater (not shown) in the solidification chamber SD1, and a die coater (not shown) are disposed in this order on the conveying path of the current collecting foil EP from the collecting metal foil roll RL1 side to the winding roll RL4 side, DC2 and a drying chamber DRY are disposed. The current collecting foil EP to be conveyed passes between the die coater DC1 and the roller RL2, in the solidification chamber SD1, between the die coater DC2 and the roller RL3, and in the drying chamber DRY.

Each of the positive electrode and the negative electrode constituting the lithium ion secondary battery is basically manufactured by the same process although the material of the current collecting foil EP and the material of the film to be coated on the current collecting foil EP are different. Therefore, the manufacturing process of each of the positive electrode and the negative electrode will be described below without dividing it. For example, an electrode material (ES), which will be described later, includes a material for a positive electrode and a material for a negative electrode, and is made of different materials in each case. Here, in the manufacturing process of the positive electrode, it is needless to say that the current collecting foil (EP) made of the material for the positive electrode and the coating material are used and the material used only in the negative electrode manufacturing process is not used. Similarly, in the manufacturing process of the negative electrode, a material used only in the manufacturing process of the positive electrode is not used.

In the manufacturing process of the lithium ion secondary battery in the present embodiment, first, the electrode material (ES) for forming the anode or the cathode of the lithium ion secondary battery is adjusted. Next, the adjusted slurry-like electrode material ES is wound on the current collector foil RL1 supplied from the accumulation foil roll RL1 by using a die coater DC1 which is a first coating portion arranged so as to face the roller RL2 EP). ≪ / RTI > Hereinafter, this step is referred to as a first coating step. The film made of the electrode material (ES) coated on the current collecting foil (EP) by the first coating process is called a first coating film. For example, a slit die coater can be used for the first coating portion, but another device may be used as an apparatus for supplying the electrode material ES.

Next, the current collecting foil EP coated with the electrode material ES is transferred into the solidifying chamber SD1, and the solidified liquid supplied from the atomizing nozzle NZ1 is supplied to the electrode material ES on the current collecting foil EP By spraying, the surface layer of the first coating film made of the electrode material (ES) is solidified. Hereinafter, this process is referred to as a pre-solidification process. In addition, the solidifying liquid in the present invention is a liquid containing a component that precipitates a binder contained in a slurry such as a first coating film, that is, a binder. That is, the solidified liquid and solidified fire indicate different materials, and the solidified fire is contained in, for example, the first coating film, and the solidified liquid supplied from the spray nozzle NZ1 does not contain a solid fire.

Next, an insulating material IF supplied from a die coater DC2, which is a second coating portion provided so as to face the roller RL3, is thinly and uniformly coated on the surface of the first coated film on which the surface layer is solidified. This process is called a second coating process. The film made of the insulating material IF applied on the first coating film by the second coating process is called a second coating film. For example, a slit die coater can be used for the second coating portion. 1, the first coating film and the second coating film are not shown.

Next, the current collecting foil (EP) coated with the second coating film by the second coating process is transferred into a drying room (DRY) which is a hot air drying furnace. In the drying chamber DRY, the solvent component and the solidifying liquid in the first coating film and the second coating film are heated and evaporated, whereby the first coating film and the second coating film are dried and solidified, and the electrode layer and the insulating layer are collectively . Hereinafter, this process is referred to as a drying process. That is, the first coated film becomes an electrode layer by a drying process, and the second coated film becomes an insulating layer, that is, a separator by a drying process. Thus, an electrode plate comprising an electrode layer and an insulating layer, that is, a positive electrode plate or a negative electrode plate, which is laminated in order on one surface of the current collecting foil EP and the current collecting foil EP, is formed. Thereafter, the electrode plate is wound around a take-up roll RL4. In the present invention, the electrode, the positive electrode, and the negative electrode are sometimes referred to as an electrode plate, a positive electrode plate, and a negative electrode plate, respectively.

The electrode material (ES) in the present embodiment contains a positive electrode active material powder or a negative electrode active material powder capable of discharging and storing lithium ions by charge and discharge. Further, the electrode material (ES) contains a binder component for binding between the powder components after drying or for binding between the powder component and the current collector foil. In some cases, the electrode material (ES) contains a powder of a conductive auxiliary agent.

The solidified liquid used in the free solidification step needs to have a property that the binder component contained in the first coating film is insoluble and mutually dissolves with the solvent in the first coating film. When the solidified liquid comes into contact with the first coating film, the solidified liquid penetrates into the first coating film while being dissolved in the solvent in the first coating film. When the concentration of the solidified liquid on the surface layer of the first coated film is increased, the solubility of the binder is decreased, so that the binder is precipitated and only the surface layer of the first coated film is immobilized.

The present embodiment has a feature of introducing a free solidification process between the first coating process and the second coating process. As a result, the second coating process can be performed in a state in which the surface of the first coating film is not flowing. Therefore, as described later, it is possible to suppress the generation of the mixed layer formed by applying the coating pressure to the first coating film and the second coating film by the die coater as the second coating portion.

Hereinafter, each material used for manufacturing the lithium ion secondary battery in the present embodiment will be described.

Examples of the positive electrode active material used in the present embodiment include a lithium-containing complex oxide having a spinel structure containing lithium cobalt oxide or Mn (manganese), or a composite oxide containing Ni (nickel), Co (cobalt) Etc. may be used. As the cathode active material, olivine-type compounds such as olivine-type iron phosphate may also be used. However, the cathode active material is not limited to these materials and other materials may be used. The lithium-containing complex oxide having a spinel structure containing manganese is excellent in thermal stability, and therefore, for example, a cell having high safety can be formed.

As the cathode active material, only a lithium-containing complex oxide having a spinel structure containing manganese may be used, but other cathode active materials may be used in combination. Examples of other cathode active materials include olivine-type compounds represented by Li ₁ + x MO ₂ (-0.1 < x < 0.1). Examples of the metal M in this formula include Co (cobalt), Ni (nickel), Mn (manganese), Al (aluminum), Mg (magnesium), Zr (zirconium), Ti (titanium)

As the cathode active material, a lithium-containing transition metal oxide having a layered structure can be used. As a specific example of the lithium-containing transition metal oxide having a layered structure, LiCoO ₂ or LiNi ₁ -xCo _x -yAl _y O ₂ (0.1? _X ? 0.3, 0.01? _Y ? 0.2) or the like can be used. As the lithium-containing transition metal oxide having a layered structure, an oxide containing at least Co, Ni and Mn can be used. Co, as the oxide containing Ni and Mn, for example _{LiMn 1/3 Ni 1/3} Co 1/3 O 2, LiMn 5/12 Ni 5/12 Co 1/6 O 2, or LiNi _3/5 Mn _1/5 there may be mentioned Co _1/5 O ₂ or the like.

As the negative electrode active material used in the present embodiment, for example, graphite materials such as natural graphite (flake graphite), artificial graphite, or expanded graphite can be used. As the negative electrode active material, an easily graphitizable carbonaceous material such as coke obtained by baking the pitch can be used. Examples of the negative electrode active material include non-graphitizable materials such as polyfluoro-alcohols (PFA) or poly-para-phenylenes (PPP) and amorphous carbon obtained by low- Black lead-free carbonaceous material can be used.

In addition to the carbon material, Li (lithium) or a lithium-containing compound can also be used as the negative electrode active material. Examples of the lithium-containing compound include lithium alloys such as Li-Al and alloys containing elements capable of being alloyed with Li (lithium) such as Si (silicon) and Sn (tin). In addition, oxide-based materials such as Sn oxide and Si oxide can be used as the negative electrode active material. This oxide-based material may not contain Li (lithium).

The conductive auxiliary agent is used as an electron conduction auxiliary agent to be contained in the anode electrode film, and is preferably a carbon material such as carbon black, acetylene black, graphite, carbon fiber, or carbon nanotube. Among the above-mentioned carbon materials, acetylene black is particularly preferable from the viewpoint of the effect of the addition amount and conductivity, and the manufacturability of the positive electrode material mixture slurry for application. This conductive additive can also be contained in the cathode electrode film.

The binder used in the electrode of the present embodiment preferably contains a binder for binding the active material and the conductive auxiliary to each other. As the material of the binder, for example, a polyvinylidene fluoride-based polymer or a rubber-based polymer is preferably used. The polyvinylidene fluoride-based polymer is, for example, a polymer of a fluorine-containing (fluorine) monomer group containing 80% by mass or more of vinylidene fluoride whose main component is a monomer. These polymers may be used in combination of two or more. It is preferable that the binder of the present embodiment is provided in the form of a solution dissolved in a solvent.

Examples of the fluorine monomer group for synthesizing the polyvinylidene fluoride-based polymer include vinylidene fluoride or a mixture of vinylidene fluoride and other monomers and a monomer mixture containing 80% by mass or more of vinylidene fluoride .

Examples of other monomers include vinyl fluoride, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, hexafluoropropylene, and fluoroalkyl vinyl ether.

Examples of the rubber-based polymer include styrene-butadiene rubber (SBR), ethylene propylene diene rubber, and fluorine rubber.

The content of the binder in the electrode layer, that is, the first coating film, is preferably 0.1% by mass or more and 10% by mass or less based on the dried electrode layer. More preferably, the content of the binder is 0.3 mass% or more and 5 mass% or less. If the content of the binder is too small, not only the solidification in the freezing step of the present embodiment becomes insufficient, but also the problem that the electrode layer is peeled off from the current collecting foil due to the lack of mechanical strength of the dried electrode film. If the content of the binder is too large, the amount of the active material in the electrode layer may decrease, which may lower the battery capacity.

An inorganic oxide such as alumina (Al ₂ O ₃ ) or silica (SiO ₂ ) can be used as the insulating material IF used in the present embodiment. In addition, by using a slurry in which fine particles of polypropylene or polyethylene are mixed, the insulating layer can be shut down. The insulating layer is a porous film, and in the completed lithium ion secondary battery, the electrolyte is held in the vacancies of the insulating layer to constitute a path for lithium ion conduction between the electrodes. The term shutdown as used herein refers to a function of melting the insulating layer and blocking the hole when the lithium ion secondary battery is abnormally heated. By shutting off the transmission of lithium ions in the insulating layer by this shutdown function, the reaction in the battery stops, thereby preventing the battery temperature from further rising.

A resin is used as a binder for binding inorganic oxide particles used for the insulating material IF. The binder is preferably a polyvinylidene fluoride-based polymer or a rubber-based polymer as well as the positive electrode in the negative electrode.

The current collecting foil EP to be used in the present embodiment is not limited to a sheet-like foil. The substrate may be a pure metal such as aluminum (Al), copper (Cu), stainless steel, titanium Or an alloy conductive material can be used. As the current collecting foil (EP), for example, a mesh, a punched metal, a foam metal, or a foil processed into a plate shape is used. The thickness of the conductive base constituting the current collecting foil (EP) is, for example, 5 to 30 占 퐉, and more preferably 8 to 16 占 퐉.

It is important that the solidified solution of the present embodiment is appropriately selected and used for the solvent and the binder in the first coating film. The solidified liquid should be selected in consideration of the solubility of the binder component in the first coating film and the solubility of the solvent in the first coating film. The solvent in the first coating film used in the general solvent system slurry is preferably an aprotic polar solvent such as N-methylpyrrolidone, dimethylsulfoxide, propylene carbonate, dimethylformamide or? -Butyrolactone, . Considering the mutual solubility in these solvents and the solubility of the binder to be used, alcohols such as water, ethanol, isopropyl alcohol, or a mixture thereof can be selected as the solidifying liquid, but the examples are not limited thereto. For example, the alcohol as solidifying liquid may contain methanol, propanol, butanol, hexanol, heptanol, or octanol.

Further, in order to uniformly spray the solidified liquid, it is preferable to use a mixture of water and alcohol in consideration of the wettability of the first coating film and the solidifying liquid. This is because if the wettability of the first coating film and the solidifying liquid is poor, the solidifying liquid is dispersed in a plurality of places on the surface of the first coating film and is adhered in an island shape to uniformly supply the solidifying liquid to the surface of the first coating film I can not. The concentration of the alcohol in the mixture is preferably 20 to 80%, more preferably 40 to 60%. When the concentration of alcohol is lower than the above-mentioned concentration range, the wettability of the first coating film and the solidifying liquid deteriorates. When the concentration of alcohol is higher than the above-mentioned concentration range, the handling of the solidified liquid becomes difficult due to the increase in the concentration of the combustible alcohol, thereby increasing the risk of explosion in the manufacturing process and the like.

Here, the freezing step of the present embodiment will be described.

The freezing step of this embodiment is a step introduced between the first coating step and the second coating step. In the free solidification step, the solidifying liquid is sprayed on the surface of the first coating film to solidify the surface layer of the first coating film. The surface layer of the first coating film means the first coating film in the vicinity of the surface including the surface of the first coating film.

At this time, it is important to perform the freezing step by appropriately selecting the amount of spraying the solidified liquid and the sprayed particle size of the solidified liquid. As a kind of the spray nozzle, a one-fluid nozzle for spraying only liquid or a two-fluid nozzle for spraying a mixture of liquid and gas may be used. It is preferable to use a two-fluid nozzle capable of spraying finer droplets from the viewpoint of reducing the impact when water contacts the solidified film by spraying.

The average particle diameter D50 of the atomized particles sprayed from the nozzle is 20 mu m or less, more preferably 10 mu m or less, and damage such as coating film defects can be prevented. The coating film defect means that the surface of the coating film is concaved due to collision of the spray particles on the surface of the coating film when the spraying pressure, the spraying force or the average particle diameter of the droplet sprayed onto the surface of the coating film is large. In this case, there arises a problem such as a variation in insulation between the electrodes. The spraying force referred to herein refers to the pressure that the object undergoes per unit area by causing the liquid droplet to hit the object by spraying.

From the above, it is necessary to select an appropriate spray amount of the solidifying liquid depending on the kind of binder and solidifying liquid used for the electrode material. Concretely, all the binders in the first coating film are made to be equal to or lower than the solidifying liquid concentration at which they are precipitated. More preferably, all the binders in the first coating film are set to 40 to 90% of the concentration of the solidification solution to be precipitated. When the amount of the solidified liquid to be sprayed is too large, it is difficult to coat the insulating material due to the presence of solidified liquid on the first coated film. When the amount of solidified liquid is too small, there is a fear that the solidified liquid does not spread on the front surface of the first coated film .

The lithium ion secondary battery that can be provided by this embodiment can be manufactured by the same process as the lithium ion secondary battery of the second comparative example described below, except that it includes the positive electrode and the negative electrode manufactured by the above-described method. The structure of the container of the battery, the size thereof, or the structure of the electrode body having the positive electrode as the main component are not particularly limited.

The manufacturing method of the lithium ion secondary battery of the present embodiment is characterized in that after coating the first coating film to be the first electrode layer as described above and then solidifying only the surface layer of the electrode layer, Thereby coating the film. The apparatus for manufacturing a lithium ion secondary battery according to the present embodiment includes a first coating portion for coating a first coating film to be a first layer electrode layer as described above and a second coating portion for coating a second coating film to be a second insulating layer And a means for solidifying only the surface layer of the first coated film between the two coated portions. By using the above-described manufacturing method in such a manufacturing apparatus, the thickness of the mixed layer formed at the interface between the electrode layer and the insulating layer can be made thin as described later, so that the insulating layer can be thinned and highly reliable.

Hereinafter, an example of a manufacturing process of the lithium ion secondary battery of the present embodiment will be described. Here, an example of a process of forming an anode will be described.

First, in the step of adjusting the electrode material (ES), nickel cobalt lithium manganese oxide as a lithium transition metal composite oxide may be used as a positive electrode active material constituting the electrode material (ES) in the process of manufacturing the positive electrode. In the initial step of adjusting the electrode material (ES), polyvinylidene fluoride (hereinafter, simply referred to as PVdF), which is a binder having a role as a solid fire, the above-mentioned positive electrode active material, a conductive auxiliary containing graphite powder and acetylene black ). Further, N-methyl-2-pyrrolidone (hereinafter, simply referred to as NMP) which is the first solvent of the present embodiment is further added to the mixture. Thereby, each component of the mixed cathode active material, conductive auxiliary agent, solid electrolyte, and first solvent is further kneaded with a planetary mixer to adjust the cathode slurry, that is, the electrode material ES.

Here, the cathode active material, the graphite powder, the acetylene black, and the PVdF are mixed at a weight ratio of 85: 8: 2: 5. In the positive electrode slurry, the binder component, which is a high fire, is dissolved in NMP, and the slurry is a liquid having a high viscosity. The viscosity of the slurry measured by a rotational viscometer is about 10 Pa s.

Next, the first coating process is performed. Here, as the current collecting foil EP to be coated in the first coating step, for example, an aluminum foil having a thickness of 20 mu m and a width of 200 mm is used. In the first coating step, the electrode material ES is coated on the surface of the current collecting foil EP with a thickness of 100 mu m and a width of 150 mm using a die coater DC1 as a slit die coater. As a result, the first coating film made of the electrode material ES is formed on the current collecting foil EP. The above process is the first coating process of the present embodiment. The width of the current collecting foil EP and the first coating film referred to herein means the width of the current collecting foil EP in the direction along the top surface of the current collecting foil EP as a direction orthogonal to the traveling direction of the current collecting foil EP It refers to length.

Next, a free solidification step is performed. That is, the current collecting foil EP coated with the first coating film is conveyed into the solidification chamber SD1 to solidify only the surface layer of the first coating film. Here, 40% ethanol-containing water is used as the solidifying liquid supplied from the spray nozzle NZ1. The water containing 40% ethanol is a mixture of ethanol and water, and ethanol constitutes 40% of the liquid.

As the atomizing nozzle NZ1, an internally mixed type two-fluid nozzle is used. The average particle size D50 of spray particles as a solidified liquid ejected from the two-fluid nozzle is 10 mu m. Further, the distance from the spray nozzle to the first coating film is adjusted to 100 mm, the spraying pressure is 0.1 MPa, and the spraying force is 1 g / cm 2. The spray amount of the solidifying liquid was set to be 50% of the amount of the 40% ethanol-containing water required to completely precipitate PVdF as a binder. That is, the spray amount of the solidified liquid is set to be half of the amount used to deposit all of the binder. As a result, only the surface layer of the first coated film is solidified. The above process is the free solidification process of the present embodiment.

Further, on the surface including the surface of the first coating film, which is the slurry of the electrode material to which the spray nozzle NZ1 is sprayed with the solidified liquid, the spraying region of the solidifying liquid has an even flow rate distribution. That is, the distribution of the spray amount of the solidified liquid is sprayed in an equal amount within a certain range from the center of the spray nozzle NZ1 in the width direction of the first coating film. Here, the solidified liquid is uniformly sprayed over the entire upper surface of the first coated film by allowing the entire width of the first coated film to fall within a certain range in which uniform spraying is possible.

For this purpose, a position at which the flow rate is 50% of the flow rate at the center of the spray nozzle NZ1 is set at the end of the first coated film in the width direction of the first coated film, which is a direction orthogonal to the conveying direction of the current collecting foil EP, And is positioned outside. This is because there is a possibility that the solidified liquid can not be sprayed in an even amount in the region outside the position where the flow rate is 50% of the total flow rate of the solidified liquid in the width direction from the center of the spray nozzle NZ1 to be. That is, if the flow rate is within a range of 50% of the total flow rate of the solidified liquid from the center of the spray nozzle NZ1, it is possible to spray the solidified liquid in an even amount.

Next, the second coating process is performed. As the insulating material (IF), silica (SiO ₂ ) powder is used. Here, the insulating material IF and polyvinylidene fluoride (PVdF) as a binder were mixed at a ratio of 90:10 by weight, and N-methyl-2-pyrrolidone (NMP) And the components are kneaded with a planetary mixer to adjust the insulating material slurry. The insulating material slurry is a liquid of high viscosity and the viscosity of the slurry measured by a rotational viscometer is about 2Pa s.

Here, the insulating material slurry, that is, the insulating material IF is coated on the first coated film having the surface hardened to a thickness of 80 mu m and a width of 160 mm using a die coater DC2 as a slit die coater. As a result, a second coating film made of the insulating material IF is formed on the first coating film. The above process is the second coating process of this embodiment.

Next, a drying step is performed. Here, the first coated film and the second coated film are heated in a drying room DRY as a hot air drying furnace at 120 DEG C for 10 minutes and dried. As a result, the solvent contained in the first coating film and the second coating film is evaporated and removed to completely solidify the entire first coating film and the entire second coating film. Thereby producing a positive electrode plate for a lithium ion secondary battery. That is, the positive electrode plate is formed by drying and solidifying an electrode layer formed by drying and solidifying a first coating film containing a current collector EP and an electrode material ES and a second coating film containing an insulating material IF And an insulating layer. The above process is the drying process of this embodiment in which the solvent component is removed from the electrode material ES and the insulating material IF and dried.

After the above-described drying step, a film-like positive electrode or negative electrode plate is produced by subjecting the current collecting foil (EP) to processing such as compression or cutting.

Here, the thickness of the mixed layer formed at the interface between the electrode layer and the insulating layer in the manufacturing method of this embodiment is evaluated. The evaluation is carried out by cutting out the cross section of the completed electrode plate and calculating the thickness of the mixed layer from the image observed with an SEM (Scanning Electron Microscope).

3 is a cross-sectional view of an electrode plate constituting a lithium ion secondary battery. As shown in Fig. 3, on the current collecting foil EP, an electrode layer EL having a thickness L1 and an insulating layer SEL as a separator having a thickness L2 are sequentially stacked. This configuration is the same for the lithium ion secondary battery of the present embodiment and the lithium ion secondary battery of the second comparative example described later. A mixed layer MIX having a thickness L3 formed by mixing the constituent material of the electrode layer EL with the constituent material of the insulating layer SEL is formed in the vicinity of the interface between the electrode layer EL and the insulating layer SEL. In Fig. 3, the upper and lower ends of the mixed layer MIX are indicated by broken lines.

In the case of the present embodiment, the thickness L1 of the electrode layer constituting the positive electrode plate after the drying step is, for example, 50 mu m and the thickness L2 of the insulating layer is, for example, 40 mu m. The mixed layer MIX is a layer formed from the inside of the electrode layer EL to the inside of the insulating layer SEL in the vicinity of the interface between the electrode layer EL and the insulating layer SEL.

4 shows the result of evaluating the film thickness of the mixed layer MIX by SEM observation based on the sectional view shown in Fig. 4 is a graph showing the relationship between the thickness of each mixed layer MIX (see FIG. 3) of the lithium ion secondary battery of the above-described embodiment and the lithium ion secondary battery of the second comparative example described later to be. The vertical axis of the graph shown in Fig. 4 represents the film thickness of the mixed layer, and the horizontal axis represents the conveying speed of the current collecting foil. As a result of the above evaluation, the present inventors have found that the thickness L3 (see Fig. 3) of the mixed layer of the production method of the present embodiment is always 5 mu m or less irrespective of the conveying speed of the current collecting foil , And it was found that even if the insulating layer SEL (see FIG. 3) is thinned, the possibility of occurrence of a short circuit is low.

Here, an example was described in which a positive electrode plate was produced by sequentially coating a positive electrode material slurry and an insulating material slurry on one surface of a positive electrode collector foil. When the positive electrode material slurry and the insulating material slurry are coated on both surfaces of the positive electrode current collector foil, after the above-described steps are performed, before the processing step such as compression or cutting of the current collector foil is performed, It is conceivable to reverse the plate and apply the same process to the back surface.

Thereafter, in the assembling process of the electrode cell, in the process called winding, the positive electrode and the negative electrode of a necessary size are cut out from the film-like anode electrode plate and the cathode electrode plate formed by the above-described process. At this time, the insulating layer, which is a separator for separating the positive electrode plate and the negative electrode plate, is cut together with the positive electrode plate and the negative electrode plate. Subsequently, the positive electrode plate and the negative electrode plate, on which the separator is laminated, are stacked on the electrode layer, and then the laminate including the positive electrode plate and the negative electrode plate is wound together.

Next, an electrode pair group including an anode and a cathode wound together is assembled and welded. In this welding step, for example, an aluminum ribbon is wound around a positive electrode current collecting tab, and a positive current collecting tab is connected to the aluminum ribbon by ultrasonic welding. Thereafter, these welded electrode pair groups are placed in the battery can, and then an electrolyte is injected. Subsequently, the battery can is completely sealed to form the battery cell of the lithium ion secondary battery.

In the battery cell inspecting process, the cells of the lithium ion secondary cell formed in the cell assembling process are repeatedly charged and discharged. As a result, the step of inspecting a single cell relating to the performance and reliability of the battery cell is performed. In the single cell inspecting step, for example, the capacity or voltage of the battery cell is inspected, or the current or voltage at the time of charging or discharging is inspected. This completes the battery cell of the lithium ion secondary battery, that is, the unit cell.

Hereinafter, the manufacturing process of the lithium ion secondary battery of the first comparative example will be described with reference to FIGS. 5 and 6. FIG.

Fig. 6 is a flow chart schematically showing a specific process up to the production of a lithium ion secondary battery. As shown in FIG. 6, the manufacturing process of the lithium ion secondary battery includes a process of manufacturing a positive electrode plate, a process of manufacturing a negative electrode plate, and a process of assembling a battery cell.

5 shows an apparatus for manufacturing a lithium ion secondary battery according to a first comparative example. That is, FIG. 5 is a schematic view showing an apparatus for producing a lithium ion secondary battery in a first comparative example. In the production process of the lithium ion secondary battery in the first comparative example, the electrode material (ES) is first adjusted. The electrode material (ES) used for forming the electrode layer constituting the positive electrode or the negative electrode of the lithium ion secondary battery includes an active material capable of discharging and storing lithium ions and a powder of a conductive auxiliary agent by charging and discharging, A binder, a solvent and the like (kneading / combining step shown in Fig. 6), and is a liquid having a high viscosity slurry formed by the kneading and combining.

Next, the slurry-like electrode material ES is applied thinly and uniformly on the surface of the current collecting foil EP supplied from the collecting metal foil roll RL1 using a die coater DC1 as a coating part. Thereafter, a roller conveying system for conveying the current collecting foil EP at a constant speed while contacting the back surface of the current collecting foil EP, that is, a current collecting foil coated with a coating film made of a slurry-like electrode material (ES) (EP) is dried and solidified in a hot-air drying furnace which is a drying room (DRY). In this drying step, the solvent component in the coating film is heated and evaporated to dry and solidify the electrode material to form an electrode layer. Thus, by performing a series of steps of coating and drying the electrode material ES, an electrode layer is formed on the current collecting foil EP (coating step shown in Fig. 6). Thereafter, a film-like positive electrode or negative electrode plate is produced by subjecting the current collecting foil provided with the electrode layer to a process such as compression.

In the manufacturing process of the electrode plate of the first comparative example, the above-described steps were performed separately on one surface of the current collecting foil EP and on the surface opposite to the surface, and an electrode layer was formed on both surfaces of the current collecting foil EP And an electrode plate of a positive electrode and a negative electrode is manufactured.

Thereafter, in the assembling process of the electrode cell, a positive electrode and a negative electrode of a necessary size are cut out from the above-mentioned film-like positive electrode plate and negative electrode plate in a process called winding (a processing step shown in Fig. 6) . At this time, a separator for separating the positive electrode plate and the negative electrode plate from each other is cut out from the film-like separator material to a necessary size in the battery cell, and the separator is sandwiched between the positive electrode plate and the negative electrode plate, 6).

Next, electrode pairs of the positive electrode, the negative electrode and the separator wound together are assembled and welded (welding / assembling step shown in FIG. 6). Thereafter, these welded electrode pair groups are placed in the battery can, and then an electrolyte solution is injected (a pouring step shown in Fig. 6). Subsequently, a battery cell of the lithium ion secondary battery is formed by completely sealing the battery can (the sealing step shown in Fig. 6).

In the battery cell inspecting process, the cells of the lithium ion secondary cell formed in the cell assembling process are repeatedly charged and discharged (charging and discharging process shown in Fig. 6). As a result, the performance and reliability of the battery cell are inspected (the single cell inspection process shown in Fig. 6). In the step of inspecting a single cell, for example, the capacity or voltage of the battery cell is inspected, or the current or voltage at the time of charging or discharging is inspected. Thus, the battery cell, that is, the unit cell is completed, and the assembling process of the battery cell of the lithium ion secondary battery is completed.

In the above-described manufacturing process as the first comparative example, there is a problem in that the possibility of foreign matter intruding into the electrode winding body is increased by the steps performed before and after forming the electrode winding body. That is, since the positive electrode plate, the negative electrode plate, and the separator are formed of separate components, for example, there is a gap between the positive electrode plate and the separator, and metal foreign matter easily penetrates into the gap.

Specifically, in the first comparative example in which the electrode winding is formed by winding the positive electrode plate, the negative electrode plate and the separator around the central axis, the positive electrode plate, the negative electrode plate and the separator are constituted by separate components, There is a gap between the separators. In the manufacturing process of the lithium ion secondary battery, the positive electrode plate and the negative electrode plate are cut to a predetermined size (forming process shown in FIG. 6) before formation of the winding body, .

Thereafter, after the above-mentioned electrode winding is formed, for example, a step of ultrasonically welding the positive electrode current collecting tab formed on the positive electrode plate to the positive electrode collector ring, and the step of forming the negative electrode current collecting tab formed on the negative electrode plate by ultrasonic welding (A welding / assembling step shown in Fig. 6). Subsequently, the electrode winding body is inserted into an outer can (container). After the electrolyte is injected into the outer can, a step of connecting the outer can and the lid by welding or the like is performed to seal the inside of the outer can.

In the welding and assembling process, the welding of the positive electrode current collecting tab and the positive electrode current collecting ring is performed, for example, by winding an aluminum ribbon on the positive electrode current collecting tab and then connecting the positive electrode current collecting tab to the aluminum ribbon by ultrasonic welding. The ultrasonic welding used at this time is to connect the aluminum ribbon and the positive electrode current collecting tab by atomic interdiffusion by friction between the aluminum ribbon and the positive electrode current collecting tab.

Therefore, when the positive electrode current collecting tab and the aluminum ribbon are connected by ultrasonic welding, metallic foreign matter (aluminum) is generated by friction between the aluminum ribbon and the positive electrode current collecting tab. This phenomenon also occurs in the process of connecting the negative current collecting tab and the copper ribbon. That is, when the negative electrode current collecting tab and the copper ribbon are connected by ultrasonic welding, metallic foreign matter (copper) is generated by friction between the copper ribbon and the negative current collecting tab. Further, in the welding (arc welding) used in the process of connecting the external can with the lid, for example, welding residue easily occurs.

In view of the above, there is a high possibility that foreign matter intrudes into the electrode winding body by a step performed before and after forming the electrode winding body. In the case where the positive electrode plate, the negative electrode plate and the separator are constituted by separate parts as in the first comparative example, for example, since there is a gap between the positive electrode plate and the separator, metal foreign substances generated in the above- It gets easier. In this way, when foreign matter enters the inside of the electrode winding body, the foreign metal tears the separator, and the anode and the cathode are short-circuited through the metal foreign matter. Further, for example, when a metallic foreign matter intruded into the gap between the positive electrode and the separator adheres to the positive electrode, the adhered metal foreign matter dissolves in the electrolyte and then precipitates on the negative electrode. When the metal grown by precipitation from the cathode reaches the anode, there arises a problem that the anode and the cathode are short-circuited.

Further, when assembling the positive electrode plate, the negative electrode plate and the separator as separate components, it is necessary to simultaneously wind the four sheets of the positive electrode plate, the negative electrode plate and the two separators together. Further, it is necessary to dispose four film rolls in total, i.e., a positive electrode plate roll, a negative electrode plate roll and two separator rolls.

As a structure for solving the above-mentioned problem, it is conceivable to form the positive electrode plate and the negative electrode plate by directly coating the separator. In this case, a gap is formed between the positive electrode plate or the negative electrode plate and the separator by continuously forming the positive electrode plate or the negative electrode plate and the separator and integrating them with each other. As a result, foreign matter can be prevented from entering between the positive electrode plate or the negative electrode plate and the separator, so that a short circuit between the positive electrode and the negative electrode can be prevented. Further, by coating a slurry containing a positive electrode active material or a negative electrode active material on a metal and then applying an insulating material serving as a separator, it is possible to improve the productivity and reduce the manufacturing equipment.

A method for forming the electrode plate by directly applying the separator to the positive electrode plate and the negative electrode plate will be described below using the second comparative example with reference to FIG. 7 is a schematic view showing an apparatus for producing a lithium ion secondary battery in a second comparative example.

Fig. 7 shows a configuration of a single-sided coated electrode plate production apparatus in a second comparative example. In the manufacturing process of the lithium ion secondary battery of the second comparative example, the current collecting foil EP is discharged from the collecting metal foil roll RL1. The current collecting foil (EP) is, for example, an aluminum foil having a thickness of 20 mu m and a width of 200 mm. Subsequently, an electrode material ES supplied from a die coater DC1 opposed to the roller RL2 is coated on the surface of the current collecting foil EP to form a first coating film. The first coating film is, for example, 100 mu m in thickness and 150 mm in width.

Subsequently, an insulating material IF supplied from a die coater DC2, which is a coating portion opposed to the roller RL3, is coated on the first coating film to form a second coating film made of the insulating material IF. The second coating film is, for example, 20 mu m in thickness and 160 mm in width. Thereafter, the first coated film and the second coated film on the current collecting foil EP are dried by passing through the drying room DRY, and wound on the winding roll RL4 to produce an electrode plate. In this drying step, drying is carried out at 120 DEG C for 10 minutes.

As described above, the structure of the second comparative example has a die coater DC2 as a second coating portion as compared with the first comparative example described with reference to Fig. 5, and is formed as a separator on the first coating film by the die coater DC2 But differs in that the second coating film is directly formed.

As the die coater DC1 (see Fig. 7), for example, a slit die coater is used. The slit die coater is a coating apparatus used for coating a thick film or coating a high viscosity material.

In the die coating method of the second comparative example, as shown in Fig. 8, the electrode material ES as the slurry material is supplied from a tank (not shown) storing a slurry material by a metering pump (not shown) The electrode material (ES) is supplied to the manifold (3). Here, after the pressure distribution of the electrode material ES in the manifold 3 is made uniform, the electrode material ES is supplied to the slit 4 provided in the mouthpiece 1 and discharged. The discharged electrode material ES forms an electrode material holding portion 5 called a pad between the mouthpiece 1 and the current collecting foil EP which maintains a predetermined gap h1 and travels relatively, In this state, the electrode material ES is drawn out according to running of the current collecting foil EP to form a coating film. 8 is an enlarged sectional view of a die coater DC1 constituting an apparatus for manufacturing a lithium ion secondary battery in a second comparative example.

In the coating step, the coating film is continuously formed by supplying an amount of the electrode material ES equal to the amount consumed by forming the coating film from the slit 4. At this time, it is important to stabilize the formation of the meniscus 9 on the downstream side, which is the bending of the liquid surface of the electrode material holding portion 5, in order to stably apply the organic solvent-based thin film having a high evaporation rate. Therefore, the pressure for supplying the cathode material to the manifold 3 becomes the pressure of the slit 4 + the pressure loss on the downstream side lip 8 of the mouthpiece 1 + the pressure on the downstream side meniscus 9. That is, in order to stably apply the electrode material ES, it is necessary to apply a certain degree of pressure to the current collecting foil EP from the electrode material ES. This configuration is the same for the die coater DC2.

In the manufacturing process described with reference to Fig. 7, the insulating material is applied by the die coater DC2, which is the second coating portion. However, in the die coating method here, in the die coater DC1 as the first coating portion . That is, a slurry material, that is, an insulating material IF, made of an insulating material discharged from the slit 4 (see FIG. 8) of the die coater DC2 as a raw material is fed to the current collecting foil EP by the die coater DC1 Is applied on the coated electrode material (ES).

In the second comparative example described above, the slurry-like electrode material ES and the insulating material IF as shown in Fig. 7 are overlapped and coated, and then the coating layers of both sides are dried by the heating and drying process by the drying room DRY It can be dried and fixed at the same time, so that the efficiency of the manufacturing process is better than that of the first comparative example. In addition, since the electrode can be cut or welded in a state in which there is no gap between the electrode layer and the insulating layer, which is a separator, it is possible to prevent an internal short circuit due to intrusion of foreign matter.

However, when the slurry-like electrode material and the insulating material are continuously applied on the current collecting foil as in the second comparative example, as shown in Fig. 3, the electrode layer (EL) coated on the current collector foil A mixed layer MIX in which the insulating function disappears is formed in the vicinity of the interface of the insulating layer SEL. The present inventors have found that the mixed layer (MIX) is a layer formed due to the coating pressure of the slit die coater described with reference to Fig. As shown by a square plot in Fig. 4, the film thickness of the mixed layer MIX (see Fig. 3) produced in the second comparative example changes in accordance with the conveying speed of the current collecting foil. That is, the longer the conveying speed of the current collecting foil is, the longer the time taken for the pressure of the die coater to be applied to the coating film at a specific portion becomes longer, and the thickness of the mixed layer MIX becomes larger. Even if the conveying speed of the current collecting foil is relatively fast at 100 m / min, the thickness of the mixed layer MIX becomes 10 m or more.

When the mixed layer MIX is formed to have a relatively large thickness, the thickness of the insulating layer SEL having an insulating function becomes thinner than originally intended and that the thickness of the insulating layer SEL There is a possibility that the electrode material constituting the mixed layer MIX is exposed at the upper portion.

Specifically, when the thickness L3 of the mixed layer MIX is larger than 20% of the thickness L2 of the insulating layer SEL as a separator, among all the thicknesses of the insulating layer SEL between the positive electrode and the negative electrode, The insulating property of the insulating layer SEL is lowered and the problem of short-circuiting between the positive electrode and the negative electrode becomes remarkable.

That is, the thickness L3 of the mixed layer MIX is preferably 20% or less of the thickness L2 of the insulating layer SEL as a separator. Therefore, when the thickness L2 of the insulating layer SEL is 40 mu m, the thickness L3 of the mixed layer MIX is preferably 8 mu m or less. In the second comparative example, it is conceivable that the insulating layer is made to be a thick film of, for example, 50 탆 or more in order to prevent the above-described problems from occurring and to secure the reliability of the insulating layer SEL.

As in the second comparative example described above, by eliminating the gap between the electrode layer and the separator (insulating layer), it is possible to prevent an internal short circuit, improve the productivity of the lithium ion secondary battery, However, in this structure, it is difficult to make the insulating layer thinner due to the problem of the mixed layer. That is, in the second comparative example, there is a problem that it is difficult to increase the capacity and miniaturization of the lithium ion secondary battery.

Hereinafter, the effect of the present embodiment described with reference to Fig. 1 will be described.

With respect to the second comparative example described above, in the method of manufacturing a lithium ion secondary battery of the present embodiment, after coating the first coating film of the first layer to be an electrode layer and then solidifying only the surface layer of the first coating film, Is coated on the second coating film. By thus solidifying only the surface layer of the first coated film by performing the pre-solidifying process after coating the electrode material ES of the positive electrode or the negative electrode, the thickness L3 of the mixed layer MIX is set to It can be made smaller than the second comparative example. Specifically, the thickness of the mixed layer MIX can be set to 5 mu m or less. On the other hand, in the second comparative example, the thickness L3 of the mixed layer MIX is 10 mu m or more even at the practical conveying speed of the current collecting foil. Therefore, if the thickness L2 of the insulating layer SEL is made thin, The possibility increases.

Therefore, in the present embodiment, since the risk of short circuiting can be prevented even if the separator as the insulating layer is made thin, the reliability of the lithium ion secondary battery can be improved. In addition, since the separator as the insulating layer can be made thinner while preventing a short circuit, it is possible to miniaturize the lithium ion secondary battery. Therefore, the performance of the lithium ion secondary battery can be improved.

The above-described effect is not obtained only from the anode electrode plate made of the cathode material, and the same effect can be obtained in the cathode electrode plate. The manufacturing apparatus and the manufacturing method described in this embodiment are merely illustrative of concrete examples when the present embodiment is carried out and the above effects can be obtained even if various forms of embodiment are not deviated from the technical idea or main characteristic .

Although the lithium ion secondary battery is described here as an example, the present invention is not limited to the lithium ion secondary battery. The effect of the present embodiment can be achieved by, for example, a battery device having a positive electrode, a negative electrode, and a separator for electrically separating the positive electrode and the negative electrode And the like. As the electric storage device, for example, a battery of another type, a capacitor, or the like can be given.

[Embodiment 2]

In the present embodiment, as in Embodiment 1, a method of completely forming an insulating layer on a positive electrode or a negative electrode layer, followed by completely solidifying the coated layer by contacting the coated layer with a solidified liquid, And a manufacturing apparatus will be described.

Fig. 2 is a schematic view showing a manufacturing apparatus of the lithium ion secondary battery of the present embodiment. In the manufacturing process of the lithium ion secondary battery of the present embodiment, after the electrode material ES is adjusted in the same manner as in the first embodiment, the electrode material ES in the form of a slurry is supplied to the die coater DC1 opposed to the roller RL2, Is applied to the surface of the current collecting foil (EP) supplied from the current-collecting metallic foil roll. Thus, a first coating film composed of the electrode material ES is formed on the current collecting foil EP. The film thickness and the width of the current collecting foil EP and the first coating film are the same as those in the first embodiment.

Next, a freezing step is performed in the solidification chamber SD1 as in the first embodiment. Here, only the surface layer of the first coating film is solidified. The solidifying liquid and spraying conditions are the same as in the first embodiment. A second coating film made of an insulating material IF is coated on the first coating film whose surface is solidified using a die coater DC2. The film thickness and width of the second coating film are the same as those in the first embodiment.

Next, the current collecting foil EP coated with the first coating film and the second coating film is carried into the solidifying chamber SD2, and the solidifying liquid is applied to the first coating film and the second coating film using the spray nozzle NZ2 And a step of solidifying the first coating film and the second coating film is performed. Here, this process is referred to as a solidification process. As the solidifying solution, for example, water containing 40% ethanol is used. As the solidified liquid used here, alcohols such as water, ethanol, or isopropyl alcohol, or a mixture thereof may be used in the same manner as the solidified liquid sprayed in the solidifying chamber SD1 (see FIG. 1) in Embodiment 1 . For example, the alcohol as solidifying liquid may contain methanol, propanol, butanol, hexanol, heptanol, or octanol.

As the spray nozzle (NZ2), an internally mixed type two-fluid nozzle is used. The average particle size D50 of the sprayed particles ejected from the two-fluid nozzle is 10 mu m. Here, the distance from the spray nozzle NZ2 to the upper surface of the second coated film is 100 mm, the spraying pressure of the solidified liquid is 0.1 MPa, and the spraying force is adjusted to 1 g / cm2.

The spray amount of the solidified liquid is 200% of the amount of 40% ethanol-containing water in which PVdF is completely precipitated to completely solidify the first coating film as the electrode material layer and the second coating film as the insulating material layer. That is, by supplying a solidified liquid in an amount of twice the amount of 40% ethanol-containing water, which is a solidifying liquid necessary for precipitating all of PVdF, the respective coating films are completely solidified. In FIG. 2, the spray nozzle NZ2 is shown more than the spray nozzle NZ1 because the number of nozzles is increased to supply a large amount of solidified liquid as described above.

Next, the first coating film and the second coating film were dried in the drying room DRY at 120 DEG C for 10 minutes to evaporate the solvent contained in the first coating film and the second coating film to remove the electrode for lithium ion secondary battery Plate. Here, the thickness of the electrode layer constituting the electrode plate after the drying step is 50 占 퐉, and the thickness of the insulating layer on the electrode layer is 40 占 퐉. The above process can be applied to the manufacturing process of each of the positive electrode plate and the negative electrode plate.

As described above, the configuration of the present embodiment is almost the same as that of the first embodiment. It is to be noted that the second solidification chamber SD2 different from the first solidification chamber SD1 is provided between the die coater DC2 as the second coating section and the drying chamber DRY and the collecting foil EP ) Is different from the first embodiment in that the above coating film is solidified. In the pre-solidification step performed in the first solidification chamber SD1, only the surface layer of the first coating film is solidified and the interior of the first coating film is not solidified. In contrast, in the solidification step The whole of the first coating film and the second coating film including the interior thereof are all solidified. That is, all of the binder contained in each of the first coating film and the second coating film is precipitated.

The thickness of the mixed layer MIX (see FIG. 3) formed in the vicinity of the interface between the electrode layer EL and the insulating layer SEL in the electrode plate obtained in the above manufacturing process of this embodiment is the same as that of the first embodiment, Regardless of the conveying speed of the sheet. Therefore, even if the insulating layer SEL is thinned, the possibility of a short circuit between the anode and the cathode can be reduced.

Further, as in the present embodiment, since each coating film is completely solidified before the drying step, movement of the electrode material in the first coating film and the insulating material in the second coating film can be suppressed even if the drying step is performed at high speed . That is, in the case where the solidifying step using the second refinishing chamber SD2 shown in Fig. 2 is not performed, since the inside of the first coated film and the second coated film are liquid at the time of drying, Thereby causing convection or diffusion in each film. For this reason, there is a fear that the distribution of the electrode material ES after drying may be varied. In this case, since it is necessary to suppress the evaporation rate in order to suppress the convection or diffusion of the electrode material ES, there arises a problem that the drying time is prolonged.

On the other hand, in Embodiment 2, since each coating film is completely solidified before the drying process, it is possible to prevent the electrode material ES from moving during the drying process in the drying chamber DRY, The evaporation speed can be increased. Therefore, the drying time can be shortened and the drying equipment can be downsized. Thus, the throughput in the manufacturing process of the lithium ion secondary battery can be improved. In addition, the manufacturing cost of the lithium ion secondary battery can be reduced by shortening the drying time or miniaturizing the drying equipment.

[Embodiment 3]

Hereinafter, a manufacturing method and a manufacturing apparatus for a lithium ion secondary battery in this embodiment will be described with reference to FIG. In this embodiment, a description will be given of a method of making the mixed layer near the interface between the electrode material layer and the insulating material layer thinner, even when the insulating material layer serving as the separator is designed to be thin, with the miniaturization of the lithium ion secondary battery. Fig. 9 is a diagram showing the configuration of a one-side coated electrode plate production apparatus according to the present embodiment. Namely, Fig. 9 is a schematic view showing a manufacturing apparatus of a lithium ion secondary battery in this embodiment.

9, the apparatus for manufacturing a lithium ion secondary battery according to the present embodiment includes a current collector discharge roll RL0 for discharging a current collector EP as an electrode plate, And a winding roll RL4. The current collecting foil EP, which is a thin metal foil, is conveyed while being supported by a plurality of rollers such as rollers RL2 and RL3 between the current collecting roll RL0 and the winding roll RL4. Here, since the current collecting foil EP is conveyed at a constant speed, the plurality of rollers are referred to as a roller conveyance system, that is, a conveyance section.

The coater DC1, the coater DC2 and the spray nozzle SPR in the solidification chamber SD are provided in the conveying path of the current collecting foil EP in this order from the current collector discharge roll RL0 side to the winding roll RL4 side, And a drying chamber DRY are disposed. The current collecting foil EP to be conveyed passes between the coater DC1 and the roller RL2, between the coater DC2 and the roller RL3, in the solidification chamber SD, and then in the drying chamber DRY.

Each of the positive electrode and the negative electrode constituting the lithium ion secondary battery is basically manufactured by the same process although there is a difference between the material of the current collecting foil EP and the material of the film coated on the current collecting foil EP. Therefore, the manufacturing process of each of the positive electrode and the negative electrode will be described below without dividing it. For example, the electrode material (ES), which will be described later, includes a material for a positive electrode and a material for a negative electrode, and is made of different materials in each case. Here, it is needless to say that the current collecting foil (EP) made of the material for the positive electrode and the coating material are used in the manufacturing process of the positive electrode, and the material used only in the negative electrode manufacturing process is not used. Similarly, in the manufacturing process of the negative electrode, a material used only in the manufacturing process of the positive electrode is not used.

In the manufacturing process of the lithium ion secondary battery in the present embodiment, first, the electrode material (ES) for forming the anode or the cathode of the lithium ion secondary battery is adjusted. Next, the adjusted slurry-like electrode material ES is wound on the current collector EP (hereinafter referred to as EP) supplied from the current collector discharge roll RL0 by using a coater DC1 which is a first coating portion arranged so as to face the roller RL2, Lt; RTI ID = 0.0 &gt; g). &Lt; / RTI &gt; Hereinafter, this step is referred to as a first coating step. The film made of the electrode material (ES) coated on the current collecting foil (EP) by the first coating process is called an electrode material layer or a first coating film. As the first coating portion, for example, a slit die coater can be used, but another device may be used as an apparatus for supplying the electrode material ES.

Next, on the surface of the first coated film, the insulating material IF1 supplied from the coater DC2, which is a second coating portion provided so as to face the roller RL3, is thinly and uniformly coated. This process is called a second coating process. Further, a film made of the insulating material IF1 applied on the first coating film by the second coating process is called an insulating material layer or a second coating film. As the second coating portion, for example, a slit die coater or the like can be used. In Fig. 9, the first coating film and the second coating film are not shown.

Here, the insulating material IF1 contains a component that precipitates the binder component of the surface layer of the first coating film which is the electrode material layer. Herein, the component that precipitates the binder component is referred to as a solidified or solidified liquid. One of the characteristics of the lithium ion secondary battery of the present embodiment resides in that the insulating material IF1 contains a high fire as described above. In the second coating step, the insulating material IF1 containing a high fire is brought into contact with the surface of the first coating film. When the solidified film is brought into contact with the surface layer of the first coated film, the solidified liquid penetrates into the first coated film while being dissolved in the solvent in the first coated film.

As a result, when the concentration of the solidified liquid on the surface layer of the first coated film is increased, the solubility of the binder in the first coated film is reduced, so that the binder is precipitated and only the surface layer of the first coated film is immobilized. That is, the binder of the surface layer of the first coating film is precipitated to fix the active material constituting the first coating film which is the electrode material. Therefore, it is possible to prevent the active material constituting the first coating film from being mixed into the second coating film on the first coating film by solidifying the surface layer of the first coating film. The surface layer of the first coating film means a first coating film in the vicinity of the surface of the first coating film.

The binder is a component that binds between the powder components constituting the first coating film after drying of the first coating film and binds between the powder component and the current collector foil. Further, when the electrode material contains a conductive auxiliary agent, the binder has a role of binding the powder with the conductive auxiliary agent. The powder constituting the first coating film is, for example, a positive electrode active material powder or a negative electrode active material powder.

Next, a spraying liquid (LIQ) containing a component for depositing a binder in the electrode material layer from the spray nozzle (SPR) in the solidification chamber (SD), that is, a high- . Here, spray liquid LIQ is sprayed from the spray nozzle SPR. As a result, the binder in the first coating film as the electrode material layer is deposited, so that the active material in the first coating film is fixed not only in the surface layer of the first coating film. That is, in this solidification step, the entire first coating film as the electrode material layer is solidified. In the present invention, a configuration in which a coating film to be sprayed is solidified by spraying a spray liquid (LIQ), which is a high fire, using a spray nozzle (SPR) in a solidification chamber (SD) is called a solidification section.

Next, the current collecting foil EP is conveyed into a drying room DRY as a hot air drying furnace. In the drying chamber DRY, the solvent component and the solidification liquid in the first coating film and the second coating film are heated and evaporated, whereby the first coating film and the second coating film are dried and solidified to collectively form the electrode layer and the insulating layer . Hereinafter, this process is referred to as a drying process. That is, the first coated film becomes an electrode layer by a drying process, and the second coated film becomes an insulating layer, that is, a separator by a drying process. Thus, an electrode plate comprising an electrode layer and an insulating layer, that is, a positive electrode plate or a negative electrode plate, which is laminated in order on one surface of the current collecting foil EP and the current collecting foil EP, is formed. Thereafter, the electrode plate is wound around a take-up roll RL4. In the present invention, the electrode, the positive electrode, and the negative electrode are sometimes referred to as an electrode plate, a positive electrode plate, and a negative electrode plate, respectively.

After the above-described drying step, a current collector foil (EP) is subjected to processing such as compression or cutting to produce a film-like anode or cathode electrode plate. Thereafter, in the assembling process of the electrode cell, in the process called winding, the positive electrode and the negative electrode of a required size are cut out from the film-like anode electrode plate and the cathode electrode plate formed by the above-mentioned process. At this time, the insulating layer, which is a separator for separating the positive electrode plate and the negative electrode plate, is cut together with the positive electrode plate and the negative electrode plate. Subsequently, the positive electrode plate and the negative electrode plate, on which the separator is laminated, are stacked on the electrode layer, and then the laminate including the positive electrode plate and the negative electrode plate is wound together.

Next, an electrode pair group including an anode and a cathode wound together is assembled and welded. In this welding step, for example, an aluminum ribbon is wound around a positive electrode current collecting tab, and a positive current collecting tab is connected to the aluminum ribbon by ultrasonic welding. Thereafter, these welded electrode pair groups are placed in the battery can, and then an electrolyte is injected. Subsequently, the battery can is completely sealed to form the battery cell of the lithium ion secondary battery.

In the battery cell inspecting process, the cells of the lithium ion secondary cell formed in the cell assembling process are repeatedly charged and discharged. As a result, the step of inspecting a single cell relating to the performance and reliability of the battery cell is performed. In the single cell inspecting step, for example, the capacity or voltage of the battery cell is inspected, or the current or voltage at the time of charging or discharging is inspected. This completes the battery cell of the lithium ion secondary battery, that is, the unit cell.

Hereinafter, each material used for manufacturing the lithium ion secondary battery in the present embodiment will be described.

The electrode material (ES) in the present embodiment contains a positive electrode active material powder or a negative electrode active material powder capable of discharging and storing lithium ions by charge and discharge. Further, the electrode material (ES) contains a binder component for binding between the powder components after drying or for binding between the powder component and the current collector foil. In addition, the electrode material (ES) sometimes contains a powder of a conductive auxiliary agent.

In the case of forming the positive electrode plate, the electrode material (ES) to be applied in the first coating step, that is, the positive electrode material contains, for example, a mixture of an active material comprising a lithium-containing complex oxide and carbon as a conductive additive. The cathode material is a slurry obtained by kneading a mixture obtained by dissolving a binder (binder) comprising polyvinylidene fluoride in N-methylpyrrolidone (NMP), for example.

In the manufacturing process of the positive electrode, as the insulating material IF1, a binder (binder) composed of styrene butadiene rubber is dissolved in a component that precipitates a binder component of the surface layer of the electrode material, that is, utilizes a slurry by kneading a powder of silica (SiO ₂₎ was added. As the spray liquid (LIQ), which is a solidified liquid supplied from a solidification unit (SD), a component for precipitating a binder component of the electrode material, that is, an ethanol-added water, which is one of the solid fires, is used.

In the case of forming the negative electrode plate, the electrode material (ES) to be applied in the first coating step, that is, the negative electrode material contains a negative electrode active material composed of, for example, a carbon material (carbon material). The negative electrode material is, for example, a slurry obtained by kneading a negative electrode active material with a solution obtained by dissolving a binder (binder) comprising polyvinylidene fluoride in N-methylpyrrolidone (NMP).

In the manufacturing process of the negative electrode, as the insulating material IF1, a binder (binder) made of styrene-butadiene rubber is dissolved in a component that precipitates a binder component of the surface layer of the electrode material, that is, It utilizes a slurry by kneading a powder of silica (SiO ₂₎ on. As the spray liquid (LIQ), which is a solidified liquid supplied from the solidification chamber (SD), a component that precipitates the binder component of the electrode material, that is, ethanol-added water, which is one of the solid fires, is used.

Specific examples of the respective materials described above are shown below.

Examples of the positive electrode active material used in the present embodiment include a lithium-containing complex oxide having a spinel structure containing lithium cobalt oxide or Mn (manganese), or a composite oxide containing Ni (nickel), Co (cobalt) Etc. may be used. As the cathode active material, olivine-type compounds such as olivine-type iron phosphate may also be used. However, the cathode active material is not limited to these materials and other materials may be used. The lithium-containing complex oxide having a spinel structure containing manganese is excellent in thermal stability, and therefore, for example, a cell having high safety can be formed.

As the cathode active material, only a lithium-containing complex oxide having a spinel structure containing manganese may be used, but other cathode active materials may be used in combination. Examples of other cathode active materials include olivine-type compounds represented by Li ₁ + xMO ₂ (-0.1 < x < 0.1). Examples of the metal M in this formula include Co (cobalt), Ni (nickel), Mn (manganese), Al (aluminum), Mg (magnesium), Zr (zirconium), Ti (titanium)

As the cathode active material, a lithium-containing transition metal oxide having a layered structure can be used. As a specific example of the lithium-containing transition metal oxide having a layered structure, LiCoO ₂ or LiNi ₁ -xCo _x -yAl _y O ₂ (0.1? _X ? 0.3, 0.01? _Y ? 0.2) or the like can be used. As the lithium-containing transition metal oxide having a layered structure, an oxide containing at least Co, Ni and Mn can be used. Co, as the oxide containing Ni and Mn, for example _{LiMn 1/3 Ni 1/3} Co 1/3 O 2, LiMn 5/12 Ni 5/12 Co 1/6 O 2, or LiNi _3/5 Mn _1/5 there may be mentioned Co _1/5 O ₂ or the like.

The conductive auxiliary agent is used as an electron conduction auxiliary agent to be contained in the anode electrode film, and is preferably a carbon material such as carbon black, acetylene black, graphite, carbon fiber, or carbon nanotube. Among the above-mentioned carbon materials, acetylene black is particularly preferable from the viewpoint of the effect of the addition amount and conductivity, and the manufacturability of the positive electrode material mixture slurry for application. This conductive additive can also be contained in the cathode electrode film.

The binder which is the binder preferably contains a binder for binding the active material and the conductive auxiliary to each other. As the material of the binder, for example, a polyvinylidene fluoride-based polymer or a rubber-based polymer is preferably used. The polyvinylidene fluoride-based polymer is, for example, a polymer of a fluorinated monomer group containing 80% by mass or more of vinylidene fluoride whose main component is a monomer. These polymers may be used in combination of two or more. It is preferable that the binder of the present embodiment is provided in the form of a solution dissolved in a solvent.

Examples of the fluorine monomer group for synthesizing the polyvinylidene fluoride-based polymer include vinylidene fluoride or a mixture of vinylidene fluoride and other monomers, and a monomer mixture containing 80% by mass or more of vinylidene fluoride .

Examples of other monomers include vinyl fluoride, trifluoroethylene, trifluorochloroethylene, tetrafluoroethylene, hexafluoropropylene, and fluoroalkyl vinyl ether.

Examples of the rubber-based polymer include styrene-butadiene rubber (SBR), ethylene propylene diene rubber, and fluorine rubber.

The content of the binder in the electrode material layer, that is, the first coating film, is preferably 0.1% by mass or more and 10% by mass or less based on the dried electrode layer. More preferably, the content of the binder is 0.3 mass% or more and 5 mass% or less. If the content of the binder is too small, not only the solidification in the freezing step of the present embodiment becomes insufficient, but also the problem that the electrode layer is peeled off from the current collecting foil due to the lack of mechanical strength of the dried electrode film. If the content of the binder is too large, the amount of the active material in the electrode layer may decrease and the battery capacity may decrease.

Further, roneun insulating material (IF1) to be used in this embodiment may be an inorganic oxide such as alumina (Al ₂ O ₃₎ or silica (SiO _2). In addition, by using a slurry in which fine particles of polypropylene or polyethylene are mixed, the insulating layer can be shut down. The insulating layer is a porous film, and in the completed lithium ion secondary battery, the electrolyte solution is held in the pores of the insulating layer to constitute a path for lithium ion conduction between the electrodes. The term shutdown as used herein refers to a function of melting the insulating layer and blocking the hole when the lithium ion secondary battery is abnormally heated. By shutting down the transmission of lithium ions in the insulating layer by this shutdown function, the reaction in the battery stops, thereby preventing the battery temperature from further rising.

A resin is used as a binder for binding inorganic oxide particles used for the insulating material IF1. As for the binder in the negative electrode, the aforementioned polyvinylidene fluoride-based polymer or rubber-based polymer is preferably used as well as the positive electrode.

In this embodiment, it is important that the material of the solidified liquid contained in the insulating material IF1 is appropriately selected for the solvent and the binder in the first coating film. The solidified liquid should be selected in consideration of the solubility of the binder component in the first coating film and the solubility of the solvent in the first coating film. The solvent in the first coating film used in the general solvent system slurry is preferably an aprotic polar solvent such as N-methylpyrrolidone, dimethylsulfoxide, propylene carbonate, dimethylformamide or? -Butyrolactone, . Considering the mutual solubility in the solvent and the solubility of the binder to be used, alcohols such as water, ethanol, isopropyl alcohol, or a mixture thereof can be selected as the solidifying liquid, but the examples are not limited thereto. For example, the alcohol as solidifying liquid may contain methanol, propanol, butanol, hexanol, heptanol, or octanol.

In order to uniformly spray the solidified liquid, that is, spray liquid (LIQ) from the spray nozzle (SPR) in the solidification chamber (SD), the wettability of the laminated film composed of the first coating film and the second coating film and the solidifying liquid You must choose a solid solution. As the spraying liquid (LIQ), it is preferable to use, for example, a mixture of water and alcohol. This is because if the wettability of the laminated film composed of the first coating film and the second coating film is poor and the solidifying liquid is poor in wettability, the solidifying liquid is dispersed in a plurality of places on the surface of the laminated film and adhered in an island shape, Because it can not supply solidified liquid. That is, the solidifying liquid constituting the spraying liquid (LIQ) needs to be a component having good affinity with the surface of the laminated film.

The concentration of alcohol in the mixture is preferably, for example, 20 to 80%. However, more preferably, the concentration of the alcohol is preferably 40 to 60%. When the concentration of alcohol is lower than the above-mentioned concentration range, the wettability of the laminated film and the solidifying liquid deteriorates. In addition, when the concentration of alcohol is higher than the above-mentioned concentration range, handling of the solidified liquid becomes difficult due to an increase in the concentration of the flammable alcohol, thereby increasing the risk of explosion in the manufacturing process and the like.

The spraying liquid LIQ may be constituted only by water when the solidifying liquid constituting the spraying liquid LIQ has a high wettability with the surface of the laminated film, that is, with the surface of the second coated film, that is, when the affinity is good . Further, when the solidified liquid can be handled safely, the spraying liquid (LIQ) may be constituted by only alcohol.

Specifically, in the case of forming the negative electrode plate in the present embodiment, a graphite material such as natural graphite (man-made graphite), artificial graphite, or expanded graphite can be used as the negative electrode active material constituting the electrode material ES have. As the negative electrode active material, a graphitizable carbonaceous material such as coke obtained by baking the pitch can be used. Examples of the negative electrode active material include furfuryl alcohol (PFA) or poly-para-phenylen (PPP), and non-graphitizable carbonaceous materials such as amorphous carbon obtained by firing a phenol resin at low temperature Materials can be used.

In addition to the carbon material, Li (lithium) or a lithium-containing compound can also be used as the negative electrode active material. Examples of the lithium-containing compound include lithium alloys such as Li-Al and alloys containing elements capable of being alloyed with Li (lithium) such as Si (silicon) and Sn (tin). In addition, oxide-based materials such as Sn oxide and Si oxide can be used as the negative electrode active material. This oxide-based material may not contain Li (lithium).

The current collecting foil EP to be used in the present embodiment is not limited to a sheet-like foil. Examples of the base foil include a pure metal such as aluminum (Al), copper (Cu), stainless steel, titanium A conductive material can be used. As the current collecting foil (EP), for example, a mesh, a punched metal, a foam metal, or a foil processed into a plate shape is used. The thickness of the conductive base constituting the current collecting foil (EP) is, for example, 5 to 30 占 퐉.

Here, the mixed layer formed at the interface between the electrode layer and the insulating layer in the manufacturing method of the present embodiment is shown in Fig. 10, and the result of evaluation of the thickness of the mixed layer is shown in Fig. The evaluation is carried out by cutting out the cross section of the completed electrode plate and calculating the thickness of the mixed layer from the image observed with an SEM (Scanning Electron Microscope).

10 is a cross-sectional view of an electrode plate constituting a lithium ion secondary battery. As shown in Fig. 10, on the current collecting foil EP, an electrode layer EL having a thickness L1 and an insulating layer SEL as a separator having a thickness L2 are sequentially stacked. The electrode layer EL is a film formed by drying the above-described first coating film, and the insulating layer SEL is a film formed by drying the above-mentioned second coating film.

A mixed layer MIX having a thickness L3 formed by mixing the constituent material of the electrode layer EL with the constituent material of the insulating layer SEL is formed in the vicinity of the interface between the electrode layer EL and the insulating layer SEL. In Fig. 10, the upper and lower ends of the mixed layer MIX are shown by broken lines. The mixed layer MIX is a region including the interface between the electrode layer EL and the insulating layer SEL and is formed from the inside of the electrode layer EL to the inside of the insulating layer SEL. In the case of the present embodiment, the thickness L1 of the electrode layer constituting the positive electrode plate after the drying step is, for example, 30 to 500 mu m and the thickness L2 of the insulating layer is, for example, 10 to 20 mu m.

Fig. 11 shows the result of evaluating the film thickness of the mixed layer MIX by SEM observation based on the sectional view shown in Fig. 11 is a graph showing the relationship between the thickness of each mixed layer MIX (see FIG. 10) of the lithium ion secondary battery of the above-described embodiment and the lithium ion secondary battery of the comparative example 4 described later Graph. The vertical axis of the graph shown in Fig. 11 represents the film thickness of the mixed layer, and the horizontal axis represents the conveying speed of the current collecting foil.

As a result of the above evaluation, the present inventors have found the following.

That is, as shown by a square plot in Fig. 11, in the fourth comparative example described later, the film thickness of the mixed layer changes according to the conveying speed of the current collecting foil. That is, the thickness of the mixed layer MIX becomes larger as the conveying speed of the current collecting foil is slower. On the other hand, even if the conveying speed of the current collecting foil is 100 m / min, the thickness of the mixed layer does not become 10 mu m or less. The thickness of the mixed layer is 10 占 퐉 or more even at the practical conveying speed of the current collecting foil.

The mixed layer MIX is a film in which the insulating property is lost by mixing the electrode layer EL with the insulating layer SEL. When the mixed layer MIX is formed to have a relatively large thickness, there is a fear that the thickness of the insulating layer SEL having an insulating function becomes thinner than originally intended. In addition, when the insulating layer SEL is made thin, there is a risk that the electrode material constituting the mixed layer MIX is exposed on the insulating layer SEL. That is, if the insulating layer is made thinner, the possibility of occurrence of a short circuit increases.

On the other hand, as shown by a round plot in FIG. 11, the thickness L3 (see FIG. 10) of the mixed layer MIX of the manufacturing method of the present embodiment is always 4 m or less irrespective of the conveying speed of the current collecting foil. In this respect, the present inventors have found that, in the case of a lithium ion secondary battery formed by the manufacturing method of the present embodiment, short circuit can be prevented from occurring when the insulating layer SEL (see FIG. 10) is thinned.

In the manufacturing process described above with reference to Fig. 9, an example in which an electrode sheet of a positive electrode or a negative electrode is produced by sequentially coating an electrode material ES and an insulating material IF1 on one surface of a current collecting foil EP is described. When the electrode material ES and the insulating material IF1 are coated on both sides of the current collecting foil EP, the electrode sheet wound around the winding roll RL4 is reversed after the above-described manufacturing process, It is conceivable to coat the surface of the current collecting foil EP opposite to the one side.

Here, the basic operation principle of the lithium ion secondary battery will be described with reference to Fig. 12 is a schematic view showing a structure of a lithium ion secondary battery.

As shown in FIG. 12, the lithium ion secondary battery is a kind of non-aqueous electrolyte secondary battery, and is a secondary battery in which lithium ions in the electrolyte take charge of electric conduction. Lithium metal oxide is used as the active material (PA) as a cathode material, and carbon material such as graphite is used as an active material (NA) as a cathode material. As an electrolyte (ELQ) made of an electrolyte, an organic solvent such as ethylene carbonate and a lithium salt such as lithium hexafluorophosphate (LiPF ₆ ) are used. In the battery, lithium ions come out of the anode PE and enter the cathode NE at the time of charging, and conversely, when discharged, lithium ions come out of the cathode NE and enter the anode PE. An Al foil AF made of Al (aluminum) is used as a current collecting foil of the anode PE and a Cu foil CF made of Cu (copper) is used as a collecting foil of the cathode NE.

The lithium ion secondary battery includes, for example, a positive electrode plate coated with a positive electrode material, a negative electrode plate coated with a negative electrode material, and an electrode winding body wound with a separator (SP) such as a polymer film for preventing contact between the positive electrode plate and the negative electrode plate have. In the lithium ion secondary battery, the electrode winding body is inserted into the outer can, and the electrolyte is injected into the outer can. That is, the lithium ion secondary battery includes a positive electrode plate coated with a positive electrode material on a metal foil, a negative electrode plate coated with a negative electrode material on a metal foil, and a negative electrode plate formed in a band shape, And a laminate. By winding the stacked body, the electrode winding having a spiral-shaped cross section is formed.

Hereinafter, a method for manufacturing the lithium ion secondary battery of the third comparative example will be described.

FIG. 13 is a flow chart schematically showing a specific process up to the production of a lithium ion secondary battery. As shown in Fig. 13, the manufacturing process of the lithium ion secondary battery includes a process of manufacturing a positive electrode sheet, a process of manufacturing a negative electrode sheet, a process of assembling a battery cell, and a module assembling process.

In the manufacturing process of the lithium ion secondary battery in the third comparative example, the electrode material is adjusted first. The electrode material used for forming the electrode layer constituting the positive electrode or the negative electrode of the lithium ion secondary battery includes an active material capable of releasing and occluding lithium ions by charging and discharging and a powder of a conductive auxiliary agent and a binder for binding these powders and a solvent (The kneading and combining step shown in Fig. 13), and is a liquid having a high viscosity slurry formed by the kneading and combining step. Next, the slurry material is coated on the film-shaped metal foil and subsequently dried (coating step shown in FIG. 13). Thereafter, the metal foil coated with the slurry material is subjected to processing such as compression or cutting (a processing step shown in Fig. 13) to form a film-like anode electrode sheet.

On the other hand, the negative electrode sheet production process is performed in the same procedure as the above-described process of manufacturing the positive electrode sheet. However, various materials used in the manufacturing process of the positive electrode sheet and the various materials used in the manufacturing process of the negative electrode sheet may be different. That is, first, various materials serving as raw materials of the negative electrode material are kneaded and combined to prepare a slurry material (negative electrode material) (kneading / combining step shown in FIG. 13). Thereafter, the slurry material is coated on the film-shaped metal foil and dried (coating step shown in FIG. 13). Subsequently, the metal foil coated with the slurry material is subjected to processing such as compression or cutting (processing step shown in Fig. 13) to produce a film-shaped negative electrode sheet.

Thereafter, in the electrode cell assembling step, a positive electrode and a negative electrode of a required size are cut out from the positive electrode sheet and the negative electrode sheet in the process called winding in the battery cell. In addition, a separator of a required size is cut out in a battery cell made of a film-shaped separator material for separating the positive electrode sheet and the negative electrode sheet from each other, and a separator cut between the positive electrode and the negative electrode is sandwiched and wound together (The winding step shown in Fig. 13). Thereafter, the electrode pair group consisting of the positive electrode, the negative electrode and the separator wound together is assembled and welded (the welding and assembling step shown in FIG. 13). Thereafter, these welded electrode pair groups are placed in a battery can which is filled with an electrolyte solution (injection process shown in Fig. 13), and then the battery can is completely sealed (a sealing step shown in Fig. 13). Thus, a battery cell is formed.

In the battery cell inspecting process, the cells of the lithium ion secondary cell formed in the cell assembling process are repeatedly charged and discharged (charging and discharging process shown in FIG. 13). As a result, the single cell inspection process relating to the performance and reliability of the battery cell is performed (the single cell inspection process shown in Fig. 13). In the single cell inspecting step, for example, the capacity or voltage of the battery cell is inspected, or the current or voltage at the time of charging or discharging is inspected. This completes the battery cell of the lithium ion secondary battery, that is, the unit cell.

Next, in the module assembly process, a plurality of battery cells are combined in series to constitute a battery module, and a charge / discharge controller is connected to constitute a battery system (a module assembly process shown in FIG. 13). Thereafter, in the module inspecting process, the performance and reliability of the assembled battery module in the module assembling process are inspected (module inspecting process shown in Fig. 13). In this module inspecting step, for example, the capacity or voltage of the battery module is inspected, or the current or voltage at the time of charging or discharging is inspected.

In the method and apparatus for manufacturing a lithium ion secondary battery of the present embodiment, an insulating material layer is coated on an electrode material layer in an electrode sheet manufacturing process of a positive electrode or a negative electrode, and then a drying process is performed, An electrode plate in which the layers are integrated can be formed. For this reason, in the third comparative example, the step of preparing the separator worked in the step of winding the separator in the battery cell assembling step can be omitted. Thus, the throughput of the manufacturing process of the lithium ion secondary battery can be improved.

Hereinafter, a method of manufacturing the lithium ion secondary battery of Comparative Example 4 will be described with reference to FIG. 14 is a schematic view showing an apparatus for producing a lithium ion secondary battery in a fourth comparative example.

Fig. 14 shows a configuration of a single-sided coated electrode plate production apparatus in a fourth comparative example. An example of a manufacturing process of applying the electrode material ES and the insulating material IF2 to one surface of the current collecting foil EP is shown. The manufacturing process of the comparative example 4 is to coat the one surface of the electrode sheet. The electrode material ES supplied from the coater DC1 against the roller RL2 is applied to one face of the current collecting foil EP sent out from the current collecting foil roll RL0 in the manufacturing process of the fourth comparative example, .

Subsequently, the coated electrode material ES is coated with the insulating material IF2 supplied from the coater DC2 at a position opposed to the roller RL3. Next, the current collecting foil EP passes the drying chamber DRY, and the electrode material ES and the insulating material IF2 are dried and wound around the take-up roll RL4 to produce the anode electrode sheet. In this drying step, the first coating film made of the electrode material (ES) is dried to be an electrode layer, and the second coating film made of the insulating material (IF2) is dried to form an insulating layer, that is, a separator.

As described above, since the slurry-like cathode material and the insulating material are overlaid and coated, the both coating films can be simultaneously dried and fixed through the heating and drying process by the drying room DRY, The efficiency of the manufacturing process is better than that of the comparative example.

However, when the slurry-like electrode material and the insulating material are continuously applied on the current collecting foil as in the fourth comparative example, the electrode layer (EL) coated on the current collecting foil EP of the electrode plate A mixed layer MIX in which the insulating function disappears is formed in the vicinity of the interface of the insulating layer SEL. The present inventors have found that the mixed layer (MIX) is a layer formed due to the coating pressure of the slit die coater described with reference to Fig. As shown by a square plot in Fig. 11, the film thickness of the mixed layer MIX (see Fig. 10) produced in the fourth comparative example changes in accordance with the conveying speed of the current collecting foil. That is, the longer the conveying speed of the current collecting foil is, the longer the time taken for the pressure applied by the coater to be applied to the coating film at a specific portion becomes longer, and the thickness of the mixed layer MIX becomes larger. Even if the conveying speed of the current collecting foil is relatively fast at 100 m / min, the thickness of the mixed layer MIX becomes 10 m or more.

When the mixed layer MIX is formed to have a relatively large thickness, the thickness of the insulating layer SEL having an insulating function becomes thinner than originally intended and that the thickness of the insulating layer SEL There is a possibility that the electrode material constituting the mixed layer MIX is exposed at the upper portion.

As in the fourth comparative example described above, the internal short circuit is prevented by eliminating the gap between the electrode layer and the separator (insulating layer), and the productivity of the lithium ion secondary battery is improved, and the manufacturing apparatus of the lithium ion secondary battery is made compact However, in this structure, it is difficult to make the insulating layer thinner due to the problem of the mixed layer. That is, in the fourth comparative example, there is a problem that it is difficult to increase the capacity and miniaturization of the lithium ion secondary battery.

Hereinafter, the effect of the present embodiment described with reference to Fig. 9 will be described.

As compared to the fourth comparative example described above, the manufacturing method of the lithium ion secondary battery of the present embodiment is characterized in that, as shown in Fig. 9, after coating the first coating film of the first layer serving as the electrode layer, And an insulating material IF1 containing a high fire is applied as the second coating film. As a result, the surface layer of the first coating film is solidified. As described above, when the insulating layer IF1 is coated, the surface layer of the first coated layer is solidified to form the mixed layer MIX (see FIG. 10) with a large thickness by mixing the electrode material ES and the insulating material IF1 .

In this embodiment, after the coating process, the spray liquid (LIQ), which is a high fire in the solidification chamber (SD), is supplied to the first coating film and the second coating film so that the first coating film and the second coating film Fully solidify. As a result, in the drying process in the drying chamber DRY, the electrode material ES and the insulating material IF1 are bonded together due to the flow of the binder in each of the electrode material ES and the insulating material IF1, It is possible to prevent the mixed layer MIX (see FIG. 10) from being formed with a large thickness.

As described above, in the present embodiment, the thickness L3 of the mixed layer MIX shown in Fig. 10 can be made smaller than that of the fourth comparative example. More specifically, the thickness of the mixed layer MIX can be less than 5 mu m. On the other hand, in the fourth comparative example, the thickness L3 of the mixed layer MIX is 10 mu m or more even at the practical conveying speed of the current collecting foil. Therefore, if the thickness L2 of the insulating layer SEL is made thinner, The possibility increases.

Therefore, in the present embodiment, since the risk of short circuiting can be prevented even if the separator as the insulating layer is made thin, the reliability of the lithium ion secondary battery can be improved. In addition, since the separator as the insulating layer can be made thinner while preventing a short circuit, it is possible to miniaturize the lithium ion secondary battery. Therefore, the performance of the lithium ion secondary battery can be improved.

Further, in the present embodiment, as shown in Fig. 9, since the respective coating films are completely solidified by supplying the spraying liquid (LIQ) before the drying step, even if the drying step is carried out at a high speed, 2 Movement of the insulating material in the coating film can be suppressed. That is, when the solidification process using the solidification chamber (SD) is not performed, since the inside of the first coating film and the second coating film are liquid at the time of drying, components such as binders in the respective films move during the drying process, Convection or diffusion occurs. Therefore, there is a possibility that the distribution of the electrode material ES after drying is varied, and the mixed layer MIX (see FIG. 10) may be formed with a large thickness. In this case, it is necessary to suppress the evaporation rate in order to suppress the convection or diffusion of the electrode material (ES) due to the movement or re-melting of the binder. However, if the evaporation rate is slowed, there is a problem that the drying time is prolonged.

In contrast to this, in the present embodiment, since each coating film is completely solidified in the solidification chamber SD before the drying process, the electrode material ES can be prevented from moving during the drying process in the drying chamber DRY The evaporation speed of the solvent or the like can be increased. Therefore, the drying time can be shortened and the drying equipment can be downsized. Thus, the throughput in the manufacturing process of the lithium ion secondary battery can be improved. In addition, the manufacturing cost of the lithium ion secondary battery can be reduced by shortening the drying time or miniaturizing the drying equipment.

Further, the above-mentioned effect is not obtained only from the anode electrode plate made of the cathode material, and the same effect can be obtained in the cathode electrode plate. The manufacturing apparatus and the manufacturing method described in this embodiment are merely illustrative of concrete examples when the present embodiment is carried out and the above effects can be obtained even if various forms of embodiment are not deviated from the technical idea or main characteristic .

Although the lithium ion secondary battery is described here as an example, the present invention is not limited to the lithium ion secondary battery. The effect of the present embodiment can be achieved by, for example, a battery device having a positive electrode, a negative electrode, and a separator for electrically separating the positive electrode and the negative electrode And the like. Examples of the electrical storage device include batteries or capacitors of other types.

Although the invention made by the present inventors has been specifically described based on the embodiments, the present invention is not limited to the above-described first to third embodiments, and it goes without saying that various modifications are possible without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY The present invention is effectively applied to a manufacturing technique of a lithium ion secondary battery in which an electrode layer is formed by applying an insulating layer on an electrode layer.

1: mouthpiece 3: manifold
4: Slit 5: Electrode material retention part
8: Lip portion 9: Downward meniscus (bending of liquid surface)
AF: Al foil CF: Cu foil
DC1: die coater, coater (first coating part) DC2: die coater, coater (second coating part)
DRY: Drying room EL: Electrode layer
ELQ: electrolyte EP: current collector
ES: Electrode material IF: Insulating material
IF1: Insulation material LIQ: Spray liquid
MIX: mixed layer NA: active material
NE: cathode NZ1: atomizing nozzle
NZ2: Spray nozzle PA: Active material
PE: anode RL0: current collector roll
RL1: Roll of metal foil RL2: Rollers
RL3: roller RL4: winding roll
SD: High definition room SD1: High definition room
SD2: Solidification room SEL: Insulation layer
SP: Separator SPR: Spray nozzle

Claims (20)

(a1) a step of applying an electrode material slurry on the surface of a current collector foil (collector foil) using a first coating portion (coating portion)
(b1) a step of solidifying the surface layer of the electrode material slurry by supplying a first solidification liquid containing a component for precipitating a binder component contained in the electrode material slurry to the electrode material slurry,
(c1) a step of applying an insulating material slurry on the electrode material slurry after the step (b1) using a second coating portion,
(d1) drying the electrode material slurry and the insulating material slurry,
A mixed layer of the electrode layer and the insulating layer is formed near the interface between the electrode layer formed by drying the electrode material slurry by the drying step and the insulating layer formed by drying the insulating material slurry, Wherein the thickness of the insulating layer is 20% or less of the thickness of the insulating layer. The method according to claim 1,
(c2) a step of, after the step (c1), before the step (d1), a step of mixing the electrode material slurry and the insulating material slurry with a component for precipitating a binder component contained in each of the electrode material slurry and the insulating material slurry Wherein the electrode material slurry and the insulating material slurry are solidified by supplying a second solidification liquid to the electrode material slurry. The method according to claim 1,
The solvent contained in the electrode material slurry is an aprotic polar solvent,
Wherein the solvent used in the first solidification liquid is water, alcohols, or a mixture thereof. The method according to claim 1,
The solvent contained in the electrode material slurry is preferably N-methylpyrrolidone, dimethylsulfoxide, propylene carbonate, dimethylformamide or? -Butyrolactone, or a mixture thereof,
Wherein the solvent used for the first solidification liquid is water, ethanol, isopropyl alcohol, or a mixture thereof. The method according to claim 1,
Wherein an alcohol concentration of the first solidification liquid supplied in the step (b1) is 20 to 80%. A first coating part for applying an electrode material slurry to the surface of the current collecting foil,
A first solidifying chamber for solidifying the surface layer of the electrode material slurry by supplying a first solidifying liquid containing a component for precipitating a binder component contained in the electrode material slurry to the electrode material slurry,
A second coating portion for applying an insulating material slurry on the electrode material slurry on which the surface layer is solidified,
A drying chamber for drying the electrode slurry and the slurry of the insulating material,
And a transporting section for transporting the current collecting foil in order of the first coating section, the first coating section, the second coating section, and the drying chamber,
Wherein the spray nozzle for supplying the first solidification liquid, provided in the first refinement chamber, is an internally mixed type two-fluid nozzle,
Wherein the spray area by the spray nozzle has an even flow rate distribution and a position at which the flow rate is 50% of the flow rate of the center of the spray nozzle is a position in which the end of the electrode material slurry (The end portion)
Wherein a sprayed particle diameter of the first solidifying liquid supplied from the atomizing nozzle is 10 mu m or less,
The spraying force (striking force) of the first solidifying liquid is 1 g / cm 2 or less,
A mixed layer of the electrode layer and the insulating layer is formed near the interface between the electrode layer formed by drying the slurry of the electrode material by the drying chamber and the insulating layer formed by drying the slurry of the insulating material, Of the thickness of the lithium ion secondary battery. The method according to claim 6,
And a second solidifying liquid containing a component for precipitating the electrode material slurry and a binder component contained in the insulating material slurry is supplied to the electrode material slurry and the insulating material slurry so as to solidify the electrode material slurry and the slurry of the insulating material Having further a second furnace,
Wherein the conveying section conveys the current collecting foil in the order of the first coating section, the first coating chamber, the second coating section, the second solidification chamber, and the drying chamber. The method according to claim 6,
The solvent contained in the electrode material slurry is an aprotic polar solvent,
Wherein the solvent used in the first solidification liquid is water, alcohols, or a mixture thereof. The method according to claim 6,
The solvent contained in the electrode material slurry is preferably N-methylpyrrolidone, dimethylsulfoxide, propylene carbonate, dimethylformamide or? -Butyrolactone, or a mixture thereof,
Wherein the solvent used for the first solidification liquid is water, ethanol, isopropyl alcohol, or a mixture thereof. delete A lithium ion secondary battery formed by using the apparatus for manufacturing a lithium ion secondary battery according to claim 8. delete 12. The method of claim 11,
The current collecting foil,
An electrode layer formed by drying the electrode material slurry on the current collector foil,
An insulating layer formed by drying the slurry of the insulating material on the electrode slurry;
Wherein the electrode plate has a plurality of stacked layers. (a) a step of applying an electrode material slurry containing a binder on the surface of the current collector foil by using a first coating portion,
(b) applying a slurry of an insulating material containing a first component for depositing the binder onto the slurry of the electrode material using a second coating portion,
(c) a step of solidifying the electrode material slurry by supplying a solidifying liquid containing a second component for precipitating the binder to the electrode material slurry after the step (b)
(d) a step of drying the electrode material slurry and the insulating material slurry after the step (c)
Of the lithium ion secondary battery. 15. The method of claim 14,
Wherein the first component and the second component contain water or an alcohol. 16. The method of claim 15,
Wherein the alcohol contains methanol, ethanol, propanol, butanol, hexanol, heptanol or octanol. 15. The method of claim 14,
In the step (d), the electrode material slurry is dried to form an electrode layer, the insulating material slurry on the electrode material slurry is dried to form an insulating layer,
(e) a step of overlapping a plurality of electrode plates having the current collector foil, the electrode layer and the insulating layer. A first coating part for coating the surface of the current collecting foil with an electrode material slurry containing a binder,
A second coating portion for applying an insulating material slurry containing a first component for depositing the binder onto the electrode material slurry;
A solidifying portion for solidifying the electrode material slurry by supplying a solidifying liquid containing a second component for precipitating the binder to the electrode material slurry,
A drying chamber for drying the electrode slurry and the slurry of the insulating material,
And a conveying part for conveying the current collecting foil in order of the first coating part, the second coating part, the solidification part,
And a secondary battery. 19. The method of claim 18,
Wherein the first component and the second component contain water or an alcohol. 20. The method of claim 19,
Wherein the alcohol contains methanol, ethanol, propanol, butanol, hexanol, heptanol or octanol.

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