WO2019044382A1 - Method for producing aqueous electrode slurry for lithium ion batteries, method for producing electrode for lithium ion batteries, thickening agent powder for lithium ion batteries, aqueous electrode slurry, electrode for lithium ion batteries, and lithium ion battery - Google Patents

Abstract

This method for producing an aqueous electrode slurry for lithium ion batteries is a production method for an aqueous electrode slurry that contains an electrode active material which is selected from among a positive electrode active material and a negative electrode active material, an aqueous binder, a thickening agent and an aqueous medium; and this method for producing an aqueous electrode slurry for lithium ion batteries comprises a step for obtaining a sieve-passed fraction (q) of a thickening agent powder, which contains a cellulose-based water-soluble polymer, by sieving the thickening agent powder and a step for preparing an aqueous electrode slurry by mixing an electrode active material, an aqueous binder, the sieve-passed fraction (q) and an aqueous medium with each other.

Description

Method for producing aqueous electrode slurry for lithium ion battery, method for producing electrode for lithium ion battery, thickener powder for lithium ion battery, aqueous electrode slurry, electrode for lithium ion battery and lithium ion battery

The present invention relates to a method for producing aqueous electrode slurry for lithium ion battery, a method for producing electrode for lithium ion battery, thickener powder for lithium ion battery, aqueous electrode slurry, electrode for lithium ion battery and lithium ion battery.

An electrode used in a lithium ion battery is generally mainly composed of an electrode active material layer and a current collector. The electrode active material layer is obtained, for example, by applying an aqueous electrode slurry containing an electrode active material, a thickener, an aqueous binder and the like on a current collector surface such as metal foil and drying.

As a manufacturing method of the electrode for lithium ion batteries, the method of patent document 1 and patent document 2 is mentioned, for example.

Patent Document 1 (Japanese Patent Application Laid-Open No. 2006-24550) includes a mixture containing an active material A, a conductive material B, a binder C and a thickener D, and a liquid component E in which the thickener D is dissolved. Preparing a mixture paint comprising a conductive material B comprising at least a carbon material, a thickener D comprising at least a water-soluble polymer, and a liquid component E comprising at least water; And a step a of preparing the combination paint by mixing the composition containing the active material A, the conductive material B and the thickener D in a powder state with the liquid component E, A positive electrode for a non-aqueous secondary battery having a primary kneading step for obtaining a primary kneaded material, and a secondary kneading step for kneading a primary kneaded material with a binder C and an additional liquid component to obtain a secondary kneaded material A method of making the electrode plate is described.

Patent Document 2 (Japanese Patent Application Laid-Open No. 2006-107896) discloses a negative electrode of a non-aqueous secondary battery using a paste constituted by kneading and dispersing a carbon material mainly containing graphite, a thickener, and a binder. In the method of manufacturing an electrode plate for graphite, the content of iron is 500 ppm or less, the thickener is a water-soluble polymer containing a carboxyl group, the binder is a water-dispersible polymer having a polar group, In the step of kneading the paste for forming the negative electrode coating film, an initial kneading step of adding a thickener in powder form to at least graphite and kneading with a dispersion medium and a kneaded material of the initial kneading step are diluted with a dispersion medium and kneaded. The process includes a dilution kneading step and a final kneading step of adding a binder to the kneaded material of the dilution kneading step and preparing a paste by kneading and the shearing force of the kneading in the initial kneading step is the dilution and kneading step. And work It describes a method of preparing the negative electrode of the electrode plates of nonaqueous secondary batteries, characterized by at least 2.5 times the shear force of the kneading under kneading step.

Japanese Patent Application Publication No. 2006-24550 JP, 2006-107896, A

According to the study of the present inventors, the aqueous electrode slurry obtained by the production method as described in Patent Documents 1 and 2 has a variation in viscosity per lot, or the viscosity changes during storage. It has become clear that the quality may not be stable. In addition, it has been revealed that aggregates and pinholes are easily generated in an electrode manufactured using a water-based electrode slurry whose quality is not stable.
Furthermore, according to the study of the present inventors, when preparing the aqueous electrode slurry, the aqueous electrode slurry obtained by the method of dividing and adding the thickener aqueous solution also has variation in viscosity among lots, It has become clear that the viscosity may change during storage and the quality may not be stable. Furthermore, in the method of producing such aqueous electrode slurry, the thickener aqueous solution is separately prepared, divided into the slurry and added, and there are many production steps, and the production time is long and the productivity is inferior.

The present invention has been made in view of the above-mentioned circumstances, and it is possible to obtain an aqueous electrode slurry and a thickener powder for lithium ion battery, which can stably obtain an electrode for lithium ion battery excellent in appearance with good productivity. An excellent electrode for a lithium ion battery and a lithium ion battery using the electrode.

The present inventors diligently studied to achieve the above object. As a result, it was found that by using a sieved thickener powder, it is possible to obtain an aqueous electrode slurry capable of stably obtaining an electrode of a lithium ion battery having an excellent appearance and with good productivity, and completing the present invention. It came to

According to the invention
A method for producing a water-based electrode slurry for a lithium ion battery, comprising: an electrode active material selected from a positive electrode active material and a negative electrode active material; an aqueous binder; a thickener; and an aqueous medium,
Obtaining a sieve passing portion (q) of the thickener powder by sieving a thickener powder containing a cellulose-based water-soluble polymer;
Preparing an aqueous electrode slurry by mixing an electrode active material, an aqueous binder, the sieve passing portion (q) and an aqueous medium;
There is provided a method of producing a water-based electrode slurry for a lithium ion battery, comprising:

Moreover, according to the present invention,
Preparing an aqueous electrode slurry by the above method for producing an aqueous electrode slurry for lithium ion batteries;
Coating the obtained aqueous electrode slurry on a substrate, drying the slurry, and removing the aqueous medium to form an electrode active material layer on the substrate;
A method of manufacturing a lithium ion battery electrode is provided.

Moreover, according to the present invention,
A thickener powder used to thicken an aqueous electrode slurry for lithium ion batteries,
Contains cellulose-based water-soluble polymers,
When the maximum particle diameter of the above-mentioned thickener powder in volume based particle size distribution by laser diffraction scattering type particle size distribution measuring method is D ₁₀₀ [μm],
The thickener powder was divided into a sieve residue and a sieve passing fraction by applying the thickener powder to a sieve having an opening of at least D ₁₀₀ (μm) and at least D ₁₀₀ +5 (μm). When the ratio of the said residue on a sieve sets the whole quantity of the said thickener powder to 100 mass%, the thickener powder for lithium ion batteries which is 0.05 mass% or less is provided.

Moreover, according to the present invention,
An electrode active material selected from a positive electrode active material and a negative electrode active material;
A water-based binder,
The above-mentioned thickener powder for lithium ion batteries,
Aqueous medium,
Including
The above-mentioned thickener powder for lithium ion batteries provides an aqueous electrode slurry dissolved in the above aqueous medium.

Moreover, according to the present invention,
An electrode active material selected from a positive electrode active material and a negative electrode active material;
A water-based binder,
An adhesive comprising the above-mentioned thickener powder for lithium ion batteries;
An electrode for a lithium ion battery is provided.

Moreover, according to the present invention,
A lithium ion battery comprising at least a positive electrode, an electrolyte and a negative electrode,
There is provided a lithium ion battery in which at least one of the positive electrode and the negative electrode includes the electrode for lithium ion battery described above.

According to the present invention, an aqueous electrode slurry capable of stably obtaining a lithium ion battery electrode having an excellent appearance with good productivity, a thickener powder for a lithium ion battery, an electrode for a lithium ion battery having an excellent appearance, and A lithium ion battery using the electrode can be provided.

The objects described above, and other objects, features and advantages will become more apparent from the preferred embodiments described below and the following drawings associated therewith.

It is sectional drawing which shows an example of the structure of the electrode for lithium ion batteries of embodiment which concerns on this invention. It is sectional drawing which shows an example of the structure of the lithium ion battery of embodiment which concerns on this invention.

Hereinafter, embodiments of the present invention will be described using the drawings. In all the drawings, similar components are denoted by the same reference numerals, and the description thereof will be omitted as appropriate. Further, in the drawings, each component schematically shows the shape, size and arrangement relationship to the extent that the present invention can be understood, and is different from the actual size.
In the present embodiment, “A to B” in the numerical range indicate A or more and B or less unless otherwise specified.

<Method of producing aqueous electrode slurry for lithium ion battery>
First, a method of producing a water-based electrode slurry for a lithium ion battery according to the present embodiment will be described.
In the method of producing an aqueous electrode slurry according to the present embodiment, an electrode active material (a) selected from a positive electrode active material and a negative electrode active material, an aqueous binder (b), a thickener, and an aqueous medium (c) A method of producing a water-based electrode slurry for a lithium ion battery, comprising at least the following steps (A) and (B).
Step (A): A step of obtaining a sieve passing portion (q) of the thickener powder by sieving a thickener powder containing a cellulose-based water-soluble polymer Step (B): Electrode active material (a), Step of preparing aqueous electrode slurry by mixing aqueous binder (b), sieve passing fraction (q) and aqueous medium (c)

According to the study of the present inventors, the aqueous electrode slurry obtained by the production method as described in Patent Documents 1 and 2 has a variation in viscosity per lot, or the viscosity changes during storage. It has become clear that the quality may not be stable. In addition, it was revealed that aggregates are likely to be generated in an electrode manufactured using a water-based electrode slurry whose quality is not stable.
Furthermore, according to the study of the present inventors, when preparing the aqueous electrode slurry, the aqueous electrode slurry obtained by the method of dividing and adding the thickener aqueous solution also has variation in viscosity among lots, It has become clear that the viscosity may change during storage and the quality may not be stable. Furthermore, in the method of producing such aqueous electrode slurry, the thickener aqueous solution is separately prepared, divided into the slurry and added, and there are many production steps, and the production time is long and the productivity is inferior.
That is, according to the study of the present inventors, it has become clear that the conventional aqueous electrode slurry has room for improvement from the viewpoint of stably obtaining the electrode for lithium ion battery excellent in appearance with good productivity. .

The present inventors diligently studied to achieve the above object. As a result, the thickener powder containing the conventional cellulose-based water-soluble polymer contains a water-insoluble component, and when the water-insoluble component is contained in a specific amount, the quality stability of the aqueous electrode slurry obtained decreases. It became clear to do.
Moreover, in the method of adding the thickener aqueous solution separately, since the thickener aqueous solution is added even after the solidifying step, it has become clear that the quality stability of the aqueous electrode slurry is lowered.
Therefore, the present inventors further studied earnestly. As a result, it is possible to stably obtain an aqueous electrode slurry having excellent quality stability by using a sieve passing fraction (q) obtained by sieving a thickener powder containing a cellulose-based water-soluble polymer. Found out. And when the water-based electrode slurry obtained in this way was used, generation | occurrence | production of an aggregate was suppressed and it discovered that the electrode for lithium ion batteries excellent in the external appearance could be obtained stably.
That is, an aqueous electrode slurry excellent in quality stability can be stably obtained by using a sieve passing fraction (q) obtained by sieving thickener powder containing a cellulose-based water-soluble polymer. . And an electrode for lithium ion batteries excellent in the appearance can be stably obtained by using such a water-based electrode slurry.

In the method for producing a water-based electrode slurry for lithium ion batteries according to the present embodiment, when the maximum particle diameter of sieve passing part (q) in volume-based particle size distribution by laser diffraction scattering type particle size distribution measurement method is D ₁₀₀ [μm] The sieve passing portion (q) is obtained by subjecting the sieve passing portion (q) to the sieve residue and the sieve passing portion by subjecting the sieve passing portion (q) to a sieve having an opening of D ₁₀₀ (μm) or more and D ₁₀₀ +5 (μm) or less. When the above-mentioned ratio of the residue on the sieve makes the total amount of sieve passing fraction (q) 100% by mass, it is preferably 0.05% by mass or less, more preferably 0.03% by mass or less. More preferably, it is 0.01 mass% or less. Although the lower limit value of the ratio of the above-mentioned sieve residue is not particularly limited, it is, for example, 0.00% by mass or more.
The maximum particle diameter D ₁₀₀ of the sieve passing fraction (q) can be measured, for example, using a particle size distribution analyzer (manufactured by Malvern Instruments, model name: Mastersizer 2000). The maximum particle diameter D ₁₀₀ means a particle diameter at which the integrated (accumulated) volume percentage is 100% in the volume-based particle diameter distribution.
Here, in the present embodiment, the ratio of the above-mentioned sieve residue means an index of the amount of the fiber component derived from the cellulose-based water-soluble polymer contained in the sieve passing portion (q). That is, the smaller the ratio of the residue on the sieve, the smaller the amount of the fiber component derived from the cellulose-based water-soluble polymer contained in the sieve passing portion (q).

In step (A), a sieve powder (q) of the thickener powder is obtained by sieving a thickener powder containing a cellulose-based water-soluble polymer.
Here, the thickener powder containing the cellulose-based water-soluble polymer can be produced by a known method, but various commercial products can also be used.
The sieve is not particularly limited. For example, when the maximum particle diameter of the thickener powder before being sieved is D ₁₀₀ [μm] in the volume-based particle size distribution by laser diffraction / scattering type particle size distribution measurement, It is preferable to use a sieve having an opening in the range of D ₁₀₀ (μm) or more and D ₁₀₀ +30 (μm) or less, and a sieve having an opening in the range of D ₁₀₀ (μm) to D ₁₀₀ +20 (μm) or less It is more preferable to use a sieve having an opening of D ₁₀₀ (μm) or more and D ₁₀₀ +10 (μm) or less, and an opening of D ₁₀₀ (μm) or more and D ₁₀₀ +5 (μm) or less It is particularly preferred to use a sieve which is As a result, the fiber component derived from the cellulose-based water-soluble polymer contained in the thickener powder can be effectively removed, and the sieve passing fraction of the thickener powder with the ratio of the sieve residue remaining below the above-mentioned upper limit q) can be obtained efficiently.

In the step (B), the aqueous electrode slurry is prepared by mixing the electrode active material (a), the aqueous binder (b), the sieve passing portion (q) and the aqueous medium (c). At this time, the conductive aid (d) may be combined and mixed.

Further, the step (B) preferably includes the following steps (B-1) to (B-3). Thus, the aqueous electrode slurry excellent in quality stability can be obtained more stably.
Step (B-1): A step of preparing a mixture containing the electrode active material (a) and the sieve passing portion (q) by dry mixing the electrode active material (a) and the sieve passing portion (q) in powder form Step (B-2): Slurry by wet mixing one or two or more kinds of liquid components selected from aqueous emulsion solution containing aqueous medium (c) and aqueous binder (b) into the above mixture Step of Preparing a Precursor Step (B-3): One or Two or More Liquid Components Selected from an Aqueous Emulsion Solution Containing an Aqueous Medium (c) and an Aqueous Binder (b) are further Added to the Slurry Precursor Of preparing the aqueous electrode slurry by mixing and wet mixing

In the step (B-1), the powder mixture containing the electrode active material (a) and the sieve passing portion (q) is obtained by dry mixing the electrode active material (a) and the sieve passing portion (q) in a powder state. Prepare. At this time, the conductive aid (d) may be combined and powder mixed.
In the present embodiment, by performing the step (B-1), the dispersibility of the electrode active material (a) and the thickener can be enhanced, and in the subsequent steps, the formation of the gel component derived from the thickener is carried out. It can be further suppressed. Thereby, generation | occurrence | production of the gel component derived from the thickener in the water-based electrode slurry obtained can be suppressed.

According to the study of the present inventor, an aggregate is generated in the lithium ion battery electrode manufactured using the aqueous electrode slurry obtained by the manufacturing method including the step of dry-mixing the electrode active material and the thickener in the powder state. It became clear that it was easy.
Therefore, the inventor further studied earnestly. As a result, by using the sieve passing portion (q) of the thickener powder according to the present embodiment, it is possible to suppress the generation of aggregates on the electrode surface, and it is possible to stably obtain the lithium ion battery electrode having an excellent appearance. I found out.

As a mixer which performs dry mixing, it is preferable to use a planetary motion type mixer, and it is more preferable to use a planetary motion type planetary mixer. By using such a mixer, the electrode active material (a) and the sieve passing portion (q) can be sufficiently mixed while suppressing scattering of the electrode active material (a) and the sieve passing portion (q). it can. In addition, a planetary motion type mixer means the mixer which has rotation and revolution function as a stirring mechanism. The planetary motion type planetary mixer refers to a mixer having a blade having rotation and revolution functions as a stirring mechanism.

In the step (B-2), one or more liquid components selected from an aqueous emulsion solution containing the aqueous medium (c) and the aqueous binder (b) in the mixture obtained in the step (B-1) The slurry precursor is prepared by adding and wet mixing.

It is preferable that the step (B-2) includes an adaptation step (B-2-1) and a solidifying step (B-2-2). The blending step (B-2-1) is a step of blending the powder mixture with one or more liquid components selected from an aqueous emulsion solution containing an aqueous medium (c) and an aqueous binder (b). By including the blending step (B-2-1), the powder mixture may rise up to the edge of the mixer during wet mixing, the wetting of the powder mixture may be uneven, and the powder mixture may be splashed during kneading Etc. can be suppressed.
Also, in the solidifying step (B-2-2), the wet mixing speed is set higher than that of the soaking step (B-2-1), and the powder mixture and the liquid component are kneaded to obtain a slurry precursor. Is a process of obtaining

As a mixer performing wet mixing in the step (B-2), it is preferable to use a planetary motion type mixer, and it is more preferable to use a planetary motion type planetary mixer. By using such a mixer, the dispersibility of each material can be enhanced while suppressing the scattering of each material constituting the aqueous electrode slurry.

The rotation speed of the wet mixing in the blending step (B-2-1) is not particularly limited, but is preferably in the range of 0.10 m / sec or more and 0.50 m / sec or less.
If the rotation speed of the wet mixing in the blending step (B-2-1) is within the above range, the powder mixture may rise up to the edge of the mixer during wet mixing, or the wetting of the powder mixture may be uneven. It is possible to make the liquid mixture sufficiently compatible with the powder mixture while suppressing effectively the powder mixture being splashed during kneading and the like.

Further, the revolving speed of the above-mentioned wet mixing in the blending step (B-2-1) is not particularly limited, but is preferably in the range of 0.01 m / sec or more and 0.10 m / sec or less.
If the revolution speed of the wet mixing in the blending step (B-2-1) is within the above range, the powder mixture may rise up to the edge of the mixer during wet mixing, and the wetting of the powder mixture may be uneven. It is possible to make the liquid mixture sufficiently compatible with the powder mixture while suppressing effectively the powder mixture being splashed during kneading and the like.

The mixing time of the wet mixing in the blending step (B-2-1) is not particularly limited, but is preferably, for example, 0.1 minutes or more and 30 minutes or less.

The rotation speed of the wet mixing in the solidifying step (B-2-2) is preferably in the range of 0.60 m / sec or more and 10.00 m / sec or less.
When the rotation speed of the wet mixing in the solidifying step (B-2-2) is in the above range, the shear force applied to the slurry precursor can be made more appropriate, so the molecular chain of the thickener The gel component derived from the thickener can be easily crushed while suppressing the cleavage of the polymer, and the generation of the gel component derived from the thickener in the obtained aqueous electrode slurry can be further suppressed.

In addition, the revolution speed of the wet mixing in the solidifying step (B-2-2) is preferably in the range of 0.20 m / sec to 3.00 m / sec.
Since the shear force applied to the slurry precursor can be made more appropriate when the revolution speed of the wet mixing in the solidifying step (B-2-2) is within the above range, the molecular chain of the thickener is The gel component derived from the thickener can be easily crushed while suppressing the cleavage of the polymer, and the generation of the gel component derived from the thickener in the obtained aqueous electrode slurry can be further suppressed.

The mixing time of the wet mixing in the solidifying step (B-2-2) is not particularly limited, and is, for example, 10 minutes or more and 180 minutes.

In the step (B-2), the solid content concentration of the slurry precursor is preferably adjusted to 30.0% by mass or more and 70.0% by mass or less. Since the shear force added to a slurry precursor can be made more suitable by this, the dispersibility of each material can be improved, suppressing a cutting | disconnection of the molecular chain of a thickener.
The solid content concentration of the slurry precursor can be adjusted by adjusting the concentration and the addition amount of the liquid component.

In the step (B-3), at least one selected from an aqueous emulsion solution containing an aqueous medium (c) and an aqueous binder (b) in the above-mentioned slurry precursor obtained in the step (B-2) The aqueous electrode slurry is prepared by further adding a liquid component and wet mixing.

As a mixer performing wet mixing, it is preferable to use a planetary motion type mixer, and it is more preferable to use a planetary motion type planetary mixer. By using such a mixer, sufficient mixing can be performed while stirring at low speed. Therefore, the dispersibility of each material which comprises a water-based electrode slurry can be improved, suppressing the cutting | disconnection of the molecular chain of the thickener by stirring and mixing, and suppressing aggregation of water-based binders (b). As a result, it is possible to obtain an aqueous electrode slurry having more excellent quality stability.
In addition, since the obtained aqueous electrode slurry is further excellent in dispersibility, the use of such aqueous electrode slurry makes it possible to obtain an even more uniform electrode active material layer. As a result, it is possible to obtain a lithium ion battery having further excellent battery characteristics.

In the present embodiment, at least one of the rotation speed and the rotation speed of the wet mixing in the step (B-3), preferably both the rotation speed and the rotation speed, the rotation speed of the wet mixing in the solidifying step (B-2-2) It is preferable to set it lower than the speed. Thereby, the dispersibility of each material which comprises a water-system electrode slurry can be improved, suppressing aggregation of water-system binders (b) by stirring mixing still more.

The mixing time of the wet mixing in the step (B-3) is not particularly limited, and is, for example, 5 minutes or more and 60 minutes or less.

The solid content concentration of the aqueous electrode slurry can be adjusted by adjusting the concentration and the addition amount of the liquid component.

The method for producing an aqueous electrode slurry according to the present embodiment may further include a step (C): vacuum degassing. Thereby, air bubbles caught in the slurry can be removed, and the coatability of the slurry can be improved.
The vacuum degassing may be performed by sealing the container or the shaft of the mixer to remove air bubbles, or by transferring it to another container.

<Thickener powder for lithium ion battery (p)>
The thickener powder (p) for a lithium ion battery according to the present embodiment is a thickener powder used to thicken an aqueous electrode slurry for a lithium ion battery, and contains a cellulose-based water-soluble polymer, and is a laser diffraction When the maximum particle diameter of the thickener powder (p) in the volume-based particle size distribution by scattering type particle size distribution measurement is D ₁₀₀ [μm], the opening is D ₁₀₀ (μm) or more and D ₁₀₀ +5 (μm) or less When the thickener powder (p) is divided into a sieve residue and a sieve passing fraction by applying thickener powder (p) to a sieve in a range, the ratio of the sieve residue is thickened When the total amount of the agent powder (p) is 100% by mass, it is 0.05% by mass or less, preferably 0.03% by mass or less, and more preferably 0.01% by mass or less. Although the lower limit value of the ratio of the above-mentioned sieve residue is not particularly limited, it is, for example, 0.00% by mass or more.
The maximum particle diameter D ₁₀₀ of the thickener powder (p) can be measured, for example, using a particle size distribution measurement device (Malvern Instruments, model name: Mastersizer 2000). The maximum particle diameter D ₁₀₀ means a particle diameter at which the integrated (accumulated) volume percentage is 100% in the volume-based particle diameter distribution.
Here, in the present embodiment, the ratio of the residue on the sieve means an index of the amount of the fiber component derived from the cellulose-based water-soluble polymer contained in the thickener powder (p). That is, it means that the ratio of the fiber component derived from the cellulose-based water-soluble polymer contained in the thickener powder (p) decreases as the ratio of the residue on the sieve decreases.

According to the study of the present inventors, the aqueous electrode slurry obtained by the production method as described in Patent Documents 1 and 2 has a variation in viscosity per lot, or the viscosity changes during storage. It has become clear that the quality may not be stable. In addition, it was revealed that aggregates are likely to be generated in an electrode manufactured using a water-based electrode slurry whose quality is not stable.
Furthermore, according to the study of the present inventors, when preparing the aqueous electrode slurry, the aqueous electrode slurry obtained by the method of dividing and adding the thickener aqueous solution also has variation in viscosity among lots, It has become clear that the viscosity may change during storage and the quality may not be stable. Furthermore, in the method of producing such aqueous electrode slurry, the thickener aqueous solution is separately prepared, divided into the slurry and added, and there are many production steps, and the production time is long and the productivity is inferior.
That is, according to the study of the present inventors, it has become clear that the conventional aqueous electrode slurry has room for improvement from the viewpoint of stably obtaining the electrode for lithium ion battery excellent in appearance with good productivity. .

The present inventors diligently studied to achieve the above object. As a result, the thickener powder containing the conventional cellulose-based water-soluble polymer contains a water-insoluble component, and when the water-insoluble component is contained in a specific amount, the quality stability of the aqueous electrode slurry obtained decreases. It became clear to do.
Moreover, in the method of adding the thickener aqueous solution separately, since the thickener aqueous solution is added even after the solidifying step, it has become clear that the quality stability of the aqueous electrode slurry is lowered.
Therefore, the present inventors further studied earnestly. As a result, it has been found that using a thickener powder (p) in which the ratio of the residue on the sieve is less than or equal to the upper limit can stably obtain an aqueous electrode slurry excellent in quality stability. And when the water-based electrode slurry obtained in this way was used, generation | occurrence | production of an aggregate or a pinhole was suppressed and it discovered that the electrode for lithium ion batteries excellent in the external appearance could be obtained stably.
That is, the aqueous electrode slurry excellent in quality stability can be stably obtained by using the thickener powder (p) in which the ratio of the residue on the sieve is the upper limit value or less. And an electrode for lithium ion batteries excellent in the appearance can be stably obtained by using such a water-based electrode slurry.

The thickener powder (p) preferably contains a cellulose-based water-soluble polymer as a main component. Here, containing a cellulose-based water-soluble polymer as a main component means that the thickener powder (p) contains 50% by mass or more of a cellulose-based water-soluble polymer. The thickener powder (p) contains preferably at least 70% by mass, more preferably at least 90% by mass, particularly preferably at least 99% by mass of a cellulose-based water-soluble polymer.
The cellulose-based water-soluble polymer is not particularly limited as long as it improves the coatability of the aqueous electrode slurry. Examples of cellulose-based water-soluble polymers include cellulose-based polymers such as carboxymethylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, methylethylhydroxycellulose, methylcellulose and hydroxypropylcellulose, and ammonium salts and alkali metal salts of these cellulose-based polymers It is possible to use one or two or more selected from cellulose-based polymer salts and the like.
Among these, it is preferable to include at least one selected from carboxymethylcellulose and carboxymethylcellulose salt, and one or more selected from carboxymethylcellulose, ammonium salt of carboxymethylcellulose, sodium salt of carboxymethylcellulose and potassium salt of carboxymethylcellulose. More preferably,

In the thickener powder (p) for a lithium ion battery according to the present embodiment, the above-described residue on the sieve is not particularly limited, and, for example, contains a fiber component derived from the above-mentioned cellulose water-soluble polymer.

In the thickener powder (p) for a lithium ion battery according to this embodiment, the viscosity calculated under the following condition 1 is preferably 10 mPa · s or more and 20000 mPa · s or less, and is 100 mPa · s or more and 10000 mPa · s or less The viscosity is more preferably 1000 mPa · s or more and 8000 mPa · s or less, and particularly preferably 2000 mPa · s or more and 4000 mPa · s or less.
Condition 1: The thickener powder (p) is dissolved in water to obtain a thickener aqueous solution having a concentration of 1.3% by mass. Next, using a B-type viscometer, the viscosity of the aqueous thickener solution is measured at 25 ° C. and a shear rate of 3.4 s ⁻¹ .
This makes it possible to further improve the coatability of the obtained aqueous electrode slurry.

<Method of producing thickener powder (p)>
Next, the manufacturing method of the thickener powder (p) for lithium ion batteries which concerns on this embodiment is demonstrated.
The thickener powder (p) according to the present embodiment can be obtained, for example, by sifting a thickener powder containing a cellulose-based water-soluble polymer. However, the method of producing the thickener powder (p) for a lithium ion battery according to the present embodiment is not limited to the method of screening.
Here, the step of sieving the thickener powder containing the cellulose-based water-soluble polymer can be performed according to the step (A) in the method for producing a water-based electrode slurry for lithium ion batteries described above. The description is omitted.

<Water based electrode slurry>
Next, the water-based electrode slurry according to the present embodiment will be described.
The aqueous electrode slurry according to the present embodiment comprises an electrode active material (a) selected from a positive electrode active material and a negative electrode active material, an aqueous binder (b), and a thickener powder for lithium ion batteries according to the present embodiment ( p) and an aqueous medium (c), wherein the thickener powder (p) for a lithium ion battery is dissolved in the aqueous medium (c). Moreover, it is preferable that the water-based electrode slurry which concerns on this embodiment further contains a conductive support agent (d) from a viewpoint of improving the electron conductivity of the electrode obtained.
Here, in the aqueous electrode slurry according to the present embodiment, the thickener powder (p) for a lithium ion battery is dissolved in the aqueous electrode slurry and is not in a powder state.

(Electrode active material (a))
The electrode active material (a) according to the present embodiment is appropriately selected according to the application. When manufacturing a positive electrode, a positive electrode active material is used, and when manufacturing a negative electrode, a negative electrode active material is used.

The positive electrode active material is not particularly limited as long as it is a normal positive electrode active material that can be used for the positive electrode of a lithium ion battery. For example, complex oxides of lithium and transition metals such as lithium nickel complex oxide, lithium cobalt complex oxide, lithium manganese complex oxide, lithium-manganese-nickel complex oxide, etc. Transitions such as TiS ₂ , FeS, MoS ₂ etc. Metal sulfides; transition metal oxides such as MnO, V ₂ O ₅ , V ₆ O ₁₃ , TiO ₂ , and olivine-type lithium phosphorus oxides.
The olivine-type lithium phosphorus oxide is, for example, at least one member of the group consisting of Mn, Cr, Co, Cu, Ni, V, Mo, Ti, Zn, Al, Ga, Mg, B, Nb, and Fe. It contains elements, lithium, phosphorus and oxygen. These compounds may be obtained by partially replacing some elements with other elements in order to improve their properties.

Among these, olivine-type lithium iron phosphorus oxide, lithium cobalt composite oxide, lithium nickel composite oxide, lithium manganese composite oxide, and lithium-manganese-nickel composite oxide are preferable. These positive electrode active materials have large capacity in addition to high action potential and large energy density.
The positive electrode active material may be used singly or in combination of two or more.

The negative electrode active material is not particularly limited as long as it is a common negative electrode active material that can be used for the negative electrode of a lithium ion battery. For example, carbon materials such as natural graphite, artificial graphite, resin charcoal, carbon fiber, activated carbon, hard carbon, soft carbon; lithium metals such as lithium metal and lithium alloy; metals such as silicon and tin; polyacene, polyacetylene, polypyrrole etc Conductive polymers and the like. Among these, carbon materials are preferable, and particularly graphitic materials such as natural graphite and artificial graphite are preferable.
The negative electrode active material may be used singly or in combination of two or more.

The content of the electrode active material (a) is preferably 70 parts by mass or more and 99.97 parts by mass or less, and 85 parts by mass or more and 99.85 parts by mass, based on 100 parts by mass of the total solid content of the aqueous electrode slurry. More preferably, it is at most parts by mass.

(Water-based binder (b))
The aqueous binder (b) is not particularly limited as long as it can be electrode-shaped and has sufficient electrochemical stability. For example, polyacrylic acid, polytetrafluoroethylene, polyvinylidene fluoride, styrene butadiene rubber And polyimide. These aqueous binders (b) may be used alone or in combination of two or more. Among these, styrene butadiene rubber is preferable.
In the present embodiment, the aqueous binder (b) refers to one that can be dispersed in an aqueous medium to form an aqueous emulsion solution.

The content of the aqueous binder (b) is preferably 0.01 parts by mass or more and 10.0 parts by mass or less, and 0.05 parts by mass or more, based on 100 parts by mass of the total solid content of the aqueous electrode slurry. More preferably, it is 5.0 parts by mass or less. When the content of the aqueous binder (b) is within the above range, the balance of the coating property of the aqueous electrode slurry, the binding property of the binder and the battery characteristics is further excellent.

The aqueous binder (b) is used as an aqueous emulsion solution by dispersing a powdery one in an aqueous medium. As a result, the contact between the electrode active material (a), between the conductive aid (d) and between the electrode active material (a) and the conductive aid (d) is not inhibited, and the dispersion of the aqueous binder (b) is carried out. It is possible to improve the quality.
The aqueous medium in which the aqueous binder (b) is dispersed is not particularly limited as long as it can disperse the aqueous binder (b), but distilled water, ion exchanged water, city water, industrial water, etc. can be used. Among these, distilled water and ion exchange water are preferable. In addition, water may be mixed with water such as alcohol and a highly hydrophilic solvent.

(Thickener powder (p))
The thickener powder (p) according to the present embodiment can be used as the thickener powder (p).
The thickener powder (p) may be used alone or in combination of two or more. The content of the thickener powder (p) is preferably 0.01 parts by mass or more and 10.0 parts by mass or less, based on 100 parts by mass of the total solid content of the aqueous electrode slurry, and 0.05 parts by mass It is more preferable that it is part or more and 5.0 parts by mass or less. When the content of the thickener powder (p) is within the above range, the balance of the coating property of the aqueous electrode slurry, the binding property of the binder and the battery characteristics is further excellent.

(Water-based medium (c))
It does not specifically limit about the aqueous medium (c) which concerns on this embodiment, For example, distilled water, ion-exchange water, municipal water, industrial water etc. can be used. Among these, distilled water and ion exchange water are preferable. In addition, water may be mixed with water such as alcohol and a highly hydrophilic solvent.

(Conductive assistant (d))
From the viewpoint of improving the electron conductivity of the obtained electrode, the aqueous electrode slurry according to the present embodiment preferably further contains a conductive auxiliary (d).
The conductive aid (d) has electron conductivity and is not particularly limited as long as it improves the conductivity of the electrode. Examples of the conductive additive (d) according to the present embodiment include carbon materials such as acetylene black, ketjen black, carbon black, carbon nanofibers, and graphite having a particle diameter smaller than that of graphite used as an active material. . These conductive assistants (d) may be used alone or in combination of two or more.

The content of the conductive additive (d) is preferably 0.01 parts by mass or more and 10.0 parts by mass or less, and 0.05 parts by mass or less, based on 100 parts by mass of the total solid content of the aqueous electrode slurry. More preferably, it is 5.0 parts by mass or less.
The balance of the coating property of a water-based electrode slurry, and the binding property of a binder as the content of a conductive support agent (d) is in the said range is much more excellent.

In the aqueous electrode slurry of the present embodiment, the content of the electrode active material (a) is preferably 70 parts by mass to 99.97 parts by mass, based on 100 parts by mass of the total solid content of the aqueous electrode slurry. More preferably, it is 85 parts by mass or more and 99.85 parts by mass or less. The content of the aqueous binder (b) is preferably 0.01 parts by mass or more and 10.0 parts by mass or less, and more preferably 0.05 parts by mass or more and 5.0 parts by mass or less. Moreover, content of thickener powder (p) becomes like this. Preferably it is 0.01 to 10.0 mass parts, More preferably, it is 0.05 to 5.0 mass parts. Moreover, content of a conductive support agent (d) becomes like this. Preferably it is 0.01 to 10.0 mass parts, More preferably, it is 0.05 to 5.0 mass parts.
When the content of each component constituting the aqueous electrode slurry is in the above range, the balance between the quality stability of the aqueous electrode slurry and the battery characteristics of the obtained lithium ion battery is particularly excellent.

<Electrode for lithium ion battery>
FIG. 1 is a cross-sectional view showing an example of the structure of a lithium ion battery electrode 100 according to an embodiment of the present invention. An electrode 100 for a lithium ion battery according to this embodiment is an electrode active material (a) selected from a positive electrode active material and a negative electrode active material, an aqueous binder (b), and a thickener powder for lithium ion batteries (p) And an adhesive constituted by

<Method of Manufacturing Electrode for Lithium Ion Battery>
Next, a method of manufacturing the lithium ion battery electrode 100 according to the present embodiment will be described.
The method of manufacturing the lithium ion battery electrode 100 according to the present embodiment includes at least the following two steps (1) and (2). Thereby, an electrode for a lithium ion battery excellent in appearance can be stably obtained.
(1) Step of preparing aqueous electrode slurry by the method for producing aqueous electrode slurry for lithium ion batteries according to the present embodiment (2) The obtained aqueous electrode slurry is coated on the substrate 101 and dried, and then the aqueous medium The step of forming the electrode active material layer 103 on the base material 101 by removing the second step The step (1) is the same as the method of producing the aqueous electrode slurry for lithium ion batteries according to the present embodiment described above. Is omitted. Hereinafter, the step (2) will be described.

(2) In the step of forming an electrode active material layer, for example, the aqueous electrode slurry obtained in the above step (1) is applied onto a substrate 101 such as a current collector and dried to remove the aqueous medium Thus, the electrode active material layer 103 is formed on the substrate 101 to obtain the lithium ion battery electrode 100 in which the electrode active material layer 103 is formed on the substrate 101.

As a method of applying the aqueous electrode slurry on the substrate 101, a generally known method can be used. For example, reverse roll method, direct roll method, doctor blade method, knife method, extrusion method, curtain method, gravure method, bar method, dip method, squeeze method and the like can be mentioned.

The aqueous electrode slurry may be coated on only one side of the substrate 101 or on both sides. In the case of coating on both sides of the substrate 101, it may be coated on one side or on both sides simultaneously. In addition, it may be applied to the surface of the base material 101 continuously or intermittently. The thickness, length, and width of the coating layer can be appropriately determined according to the size of the battery.

A commonly known method can be used to dry the coated aqueous electrode slurry. For example, hot air, vacuum, infrared, far infrared, electron beam and low temperature air can be used alone or in combination. The drying temperature is, for example, in the range of 30 ° C. or more and 350 ° C. or less.

As the base material 101 used for manufacture of the electrode 100 for lithium ion batteries which concerns on this embodiment, the normal collector which can be used for a lithium ion battery, for example can be used.
As the negative electrode current collector, copper, stainless steel, nickel, titanium or an alloy thereof can be used, and among these, copper is particularly preferable.
As the positive electrode current collector, aluminum, stainless steel, nickel, titanium or an alloy thereof can be used. Among these, aluminum is particularly preferable.
The shape of the current collector is not particularly limited. For example, a foil-like material having a thickness of 0.001 to 0.5 mm can be used.

The lithium ion battery electrode 100 according to the present embodiment may be pressed as necessary. As a method of pressing, generally known methods can be used. For example, a die press method, a calendar press method, etc. may be mentioned. The pressing pressure is not particularly limited, but is, for example, in the range of 0.2 to 3 t / cm ² .

The thickness and density of the lithium ion battery electrode 100 according to the present embodiment are not particularly limited because they are appropriately determined according to the use and the like of the battery, and can be set according to generally known information.

Lithium-ion battery
Subsequently, the lithium ion battery 150 according to the present embodiment will be described. FIG. 2 is a cross-sectional view showing an example of the structure of the lithium ion battery 150 according to the embodiment of the present invention.
The lithium ion battery 150 according to the present embodiment includes at least the positive electrode 120, the electrolyte 110, and the negative electrode 130, and at least one of the positive electrode 120 and the negative electrode 130 includes the lithium ion battery electrode 100 according to the present embodiment. In addition, the lithium ion battery 150 according to the present embodiment may include a separator, if necessary.
The lithium ion battery 150 according to the present embodiment can be manufactured according to a known method.
As the electrode, for example, a laminate or a wound body can be used. As an exterior body, a metal exterior body and an aluminum laminate exterior body can be used suitably. The shape of the battery may be any shape such as coin type, button type, sheet type, cylindrical type, square type and flat type.

Any known lithium salt can be used as the electrolyte in the electrolytic solution of the battery, and it may be selected according to the type of active material. For _{example, LiClO 4, LiBF 6, LiPF} 6, LiCF 3 SO 3, LiCF 3 CO 2, LiAsF 6, LiSbF 6, LiB 10 Cl 10, LiAlCl 4, LiCl, LiBr, LiB (C 2 H 5) 4, CF 3 SO ₃ Li, CH ₃ SO ₃ Li, LiCF ₃ SO ₃ , LiC ₄ F ₉ SO ₃ , Li (CF ₃ SO ₂ ) ₂ N, lithium lower fatty acid carboxylate and the like can be mentioned.

The solvent for dissolving the electrolyte is not particularly limited as long as it is generally used as a liquid component for dissolving the electrolyte, and ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), vinylene carbonate (VC) and other carbonates; γ-butyrolactone, γ-valerolactone and other lactones; trimethoxymethane, 1,2-dimethoxyethane Ethers such as diethyl ether, 2-ethoxyethane, tetrahydrofuran, 2-methyltetrahydrofuran, etc. Sulfoxides such as dimethylsulfoxide etc. Oxolanes such as 1,3-dioxolane, 4-methyl-1,3-dioxolane Kinds of nitrogen; Nitrogenous compounds such as acetonitrile, nitromethane, formamide, dimethylformamide, etc .; Organic acid esters such as methyl formate, methyl acetate, ethyl acetate, butyl acetate, methyl propionate, ethyl propionate; phosphoric acid triesters and diglymes; Triligmes; sulfolanes such as sulfolane and methyl sulfolane; oxazolidinones such as 3-methyl-2-oxazolidinone; and sultones such as 1,3-propane sultone, 1,4-butane sultone and naphtha sultone. These may be used singly or in combination of two or more.

As a separator, a porous separator is mentioned, for example. The form of the separator includes a membrane, a film, a non-woven fabric and the like.
Examples of the porous separator include polyolefin-based porous separators such as polypropylene and polyethylene; porous separators formed of polyvinylidene fluoride, polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride hexafluoropropylene copolymer, etc. Can be mentioned.

As mentioned above, although embodiment of this invention was described, these are the illustrations of this invention, and various structures other than the above can also be employ | adopted.
Further, the present invention is not limited to the above-described embodiment, and modifications, improvements, and the like within the range in which the object of the present invention can be achieved are included in the present invention.

Hereinafter, the present invention will be described by way of Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1
<Preparation of sieve passing part (q)>
First, a carboxymethyl cellulose powder (Sun Rose (registered trademark) MAC series by Nippon Paper Industries, maximum particle diameter D ₁₀₀ : 50 μm) and a sieve with an opening of 53 μm (made by As One, material: stainless steel, trade name: stainless steel sieve) The sieve passing portion (q1) was obtained.

<Preparation of aqueous electrode slurry>
(1) Process (B-1)
Into a planetary motion type planetary mixer, 960 g of graphite as a negative electrode active material, 10 g of a sieve passing portion (q1) of the carboxymethyl cellulose powder obtained above, and 10 g of carbon black as a conductive additive were charged.
Next, dry mixing was performed at 20 ° C. for 60 minutes to obtain a powder mixture.

(2) familiarization process (B-2-1)
Subsequently, water was added to the planetary motion type planetary mixer on which the above step (B-1) was completed. Thereafter, wet mixing was performed for 2 minutes under the conditions of a rotation speed of 0.15 m / sec, a rotation speed of 0.04 m / sec, and a temperature of 20 ° C., and the powder mixture was made to have water.
(3) Hard kneading process (B-2-2)
Next, wet mixing was performed for 40 minutes under the conditions of a rotation speed of 4.50 m / sec, a rotation speed of 1.50 m / sec, and a temperature of 20 ° C. to obtain a slurry precursor.
(4) Process (B-3)
Next, an SBR aqueous solution having a solid content concentration of 40% by mass, in which styrene butadiene rubber (SBR) was dispersed in water, was prepared. 50 g of the obtained SBR aqueous solution was added to the planetary motion type planetary mixer on which the solidifying step (B-2-2) was completed.
Thereafter, wet mixing was performed for 10 minutes under the conditions of a rotation speed of 0.25 m / sec, a rotation speed of 0.08 m / sec, and a temperature of 20 ° C.
(5) Process (C)
Next, vacuum degassing was performed to obtain an aqueous electrode slurry.
The solid content concentration of the aqueous electrode slurry was adjusted to 50% by mass by adjusting the amount of water added in the soaking step (B-2-1).

<Fabrication of negative electrode>
The obtained aqueous electrode slurry was applied to one side of a copper foil as a current collector using a die coater and dried. Then, the obtained electrode was pressed to obtain a negative electrode.

<Evaluation>
(Measurement of the ratio of the residue on the sieve)
The sieve passing part (q1) (maximum particle diameter D ₁₀₀ : 50 μm) obtained above is passed through a sieve with an aperture of 53 μm (made by As One, material: stainless steel, trade name: stainless steel sieve), and the sieve passing part (q1) Was again divided into a sieved residue and a sieved fraction. Next, the mass x (g) of the sieve residue remaining on the sieve without passing through the sieve was measured, and the ratio of the sieve residue in the sieve passing portion (q1) was calculated by the following equation.
Percent remaining on sieve (mass%) = 100 × x / y
Here, y in the formula is the mass (g) of the sieve passing part (q1) of the sieved carboxymethylcellulose powder.

(Evaluation of storage stability of thickener solution)
The fraction (q1) of the carboxymethyl cellulose powder passing through the sieve was dissolved in water at 25 ° C. for 10 minutes at 200 rpm to obtain a thickener aqueous solution with a concentration of 1.3 mass%. The viscosity of the aqueous thickener solution was measured using a B-type viscometer at 25 ° C. and a shear rate of 3.4 s ⁻¹ to find that the viscosity was 3000 mPa · s.
Next, 100 g of the obtained aqueous thickener solution was placed in a plastic container with a lid, and kept in a closed state for 3 days under the condition of a temperature of 25 ° C.
Next, the viscosity of the aqueous thickener solution after holding for 3 days was measured at 25 ° C. and a shear rate of 3.4 s ⁻¹ using a B-type viscometer. Thereafter, the viscosity change rate was calculated by the following formula, and the storage stability of the aqueous thickener solution was evaluated by the following standard.
Viscosity change rate [%] = 100 × (viscosity after holding for 3 days) / (viscosity before holding for 3 days)
:: Viscosity change rate is 80% or more and less than 120% ○: Viscosity change rate is 120% or more and less than 150% or 50% or more and less than 80% ×: Viscosity change rate is 150% or more or 10% or more and less than 50%

(Evaluation of storage stability of aqueous electrode slurry)
100 g of the obtained aqueous electrode slurry was placed in a plastic container with a lid, and the lid was kept closed for 3 days under the condition of a temperature of 25 ° C.
Next, the viscosity of the aqueous electrode slurry before and after holding was measured at 25 ° C. and a shear rate of 3.4 s ⁻¹ using a B-type viscometer. Thereafter, the viscosity change rate was calculated by the following formula, and the storage stability of the aqueous electrode slurry was evaluated by the following standard.
Viscosity change rate [%] = 100 × (viscosity after holding for 3 days) / (viscosity before holding for 3 days)
:: Viscosity change rate of 80% or more and less than 120% ○: Viscosity change rate of 120% or more and less than 150% or 50% or more and less than 80% Δ: Viscosity change rate of 150% or more or 10% or more and less than 50% The aqueous electrode slurry separated by the retention test (judged by visual observation)
The obtained results are shown in Table 1.

(Viscosity evaluation of aqueous electrode slurry)
The viscosity variation of the aqueous electrode slurry was evaluated as follows. First, five aqueous electrode slurries under the same conditions were prepared as samples. Next, the viscosity of the obtained aqueous electrode slurry at 25 ° C. and a shear rate of 3.4 s ⁻¹ is measured using a B-type viscometer, the maximum variation is calculated by the following equation, and the aqueous electrode slurry is Lot-to-lot variation was evaluated.
Maximum variation (mPa · s) = (maximum viscosity of 5 samples)-(minimum viscosity of 5 samples)
:: Maximum variation less than 500 mPa · s 〇: Maximum variation less than 500 mPa · s and less than 1000 mPa · s ×: Maximum variation less than 1000 mPa · s

(Evaluation of non-defective rate of negative electrode)
A total of 1,500 negative electrodes (1 cm × 1 cm) were prepared, and the ratio of non-defective products (non-defective product ratio) was calculated.
The obtained negative electrode surface was observed at a magnification of 100 times using an optical microscope to examine the presence or absence of aggregates and pinholes on the negative electrode surface. Then, those in which no aggregates and pinholes were not observed were regarded as good products, and those in which aggregates and pinholes were observed in at least one place were regarded as defects. Next, the ratio of non-defective products was calculated as the non-defective product rate, and evaluated according to the following criteria.
:: Non-defective rate 98% or more ○: Non-defective rate 95% to less than 98% ×: Non-defective rate less than 95%

(Productivity evaluation of negative electrode)
The productivity of the negative electrode was evaluated according to the following criteria. In each of the Examples and Comparative Examples, since the steps after obtaining the aqueous electrode slurry are the same, the production of the negative electrode is performed for the time taken to obtain the aqueous electrode slurry (hereinafter referred to as the production time of the aqueous electrode slurry). The sex was evaluated. Here, the production time of the aqueous electrode slurry in Comparative Example 2 was set to 100 in the following evaluation criteria.
◎: Production time of aqueous electrode slurry less than 70 ○: Production time of aqueous electrode slurry 70 to less than 100 ×: Production time of aqueous electrode slurry 100 or more

(Example 2)
A sieve with an opening of 63 μm instead of a sieve with an opening of 53 μm (made by As One Corp., material: stainless steel, trade name: stainless steel sieve) at the time of preparation of sieve passing part (q) A water-based electrode slurry and a negative electrode were produced under the same conditions as in Example 1 except that trade name: stainless steel sieve was used, and each evaluation was performed in the same manner as in Example 1. The obtained results are shown in Table 1.

(Example 3)
A sieve with an opening of 73 μm instead of a sieve with an opening of 53 μm (made by As One Corp., material: stainless steel, trade name: stainless steel sieve) at the time of preparation of sieve passing part (q) A water-based electrode slurry and a negative electrode were produced under the same conditions as in Example 1 except that trade name: stainless steel sieve was used, and each evaluation was performed in the same manner as in Example 1. The obtained results are shown in Table 1.

(Comparative example 1)
The same conditions as in Example 1 except that carboxymethyl cellulose powder (MAC series of Sun Rose (registered trademark) made by Nippon Paper Industries Co., Ltd.) was used as it was without sieving, instead of using a sieve passing portion (q1) of carboxymethyl cellulose powder. The aqueous electrode slurry and the negative electrode were prepared in the same manner as in Example 1, and each evaluation was performed. The obtained results are shown in Table 1.
Here, the ratio of the residue on the sieve of Comparative Example 1 in Table 1 was determined by the following method.
First, carboxymethylcellulose powder (MAC series of Sunrose (registered trademark) manufactured by Nippon Paper Industries Co., Ltd.) was passed through a sieve (made by As One, material: stainless steel, trade name: stainless steel sieve) having a mesh size of 53 μm. Next, the mass x ′ (g) of the residue on the sieve left on the sieve without passing through the sieve was measured, and the ratio of the residue on the sieve in the carboxymethylcellulose powder was calculated by the following equation.
Percent remaining on sieve (mass%) = 100 × x '/ y'
Here, y 'in the formula is the mass (g) of the carboxymethylcellulose powder screened.

(Comparative example 2)
<Preparation of Thickener Aqueous Solution B>
First, carboxymethyl cellulose powder (MAC series of Sun Rose (registered trademark) manufactured by Nippon Paper Industries Co., Ltd.) was dissolved in ion exchange water at 20 ° C. to obtain a thickener aqueous solution A having a concentration of 1.3 mass%. Next, the obtained aqueous thickener solution was filtered through a filter with an average pore diameter of 1 μm to obtain a aqueous thickener solution B.

<Preparation of aqueous electrode slurry>
(1) Process 1
Into a planetary motion type planetary mixer, 960 g of graphite as a negative electrode active material and 10 g of carbon black as a conductive additive were charged.
Next, dry mixing was performed at 20 ° C. for 60 minutes to obtain a powder mixture.

(2) Process 2
Next, water and an aqueous thickener solution B were added to the planetary motion type planetary mixer on which Step 1 above was completed. Thereafter, wet mixing was performed for 2 minutes under the conditions of a rotation speed of 0.15 m / sec, a rotation speed of 0.04 m / sec, and a temperature of 20 ° C., and the powder mixture was made to have water.

(3) Process 3
Next, water and an aqueous thickener solution B were added to the planetary motion type planetary mixer on which Step 2 above was completed. Next, wet mixing was performed for 40 minutes under the conditions of a rotation speed of 4.50 m / sec, a rotation speed of 1.50 m / sec, and a temperature of 20 ° C. to obtain a slurry precursor.

(4) Process 4
Next, an SBR aqueous solution having a solid content concentration of 40% by mass, in which styrene butadiene rubber (SBR) was dispersed in water, was prepared. 50 g of the obtained aqueous solution of SBR and an aqueous solution of thickener B were added to the planetary-type planetary mixer on which Step 3 was completed. The total of the thickener powder contained in the thickener aqueous solution B used in steps 2 to 4 was adjusted to 10 g.
Thereafter, wet mixing was performed for 10 minutes under the conditions of a rotation speed of 0.25 m / sec, a rotation speed of 0.08 m / sec, and a temperature of 20 ° C.
(5) Process 5
Next, vacuum degassing was performed to obtain an aqueous electrode slurry.
The solid content concentration of the aqueous electrode slurry was adjusted to 50% by mass by adjusting the amount of water added in each step.

<Fabrication of negative electrode>
The obtained aqueous electrode slurry was applied to one side of a copper foil as a current collector using a die coater and dried. Then, the obtained negative electrode was pressed to obtain a negative electrode.

Each evaluation was performed similarly to Example 1 about the obtained thickener aqueous solution, water-based electrode slurry, and the negative electrode. The obtained results are shown in Table 1.

(Comparative example 3)
An aqueous electrode slurry and a negative electrode were produced in the same manner as in Comparative Example 2 except that the above-mentioned aqueous thickener solution A was used instead of the aqueous thickener solution B, and each evaluation was performed in the same manner as in Example 1. The obtained results are shown in Table 1.

This application claims priority based on Japanese Patent Application No. 2017-168273 filed on Sep. 1, 2017, the entire disclosure of which is incorporated herein.

Claims (12)

1. A method for producing a water-based electrode slurry for a lithium ion battery, comprising: an electrode active material selected from a positive electrode active material and a negative electrode active material; an aqueous binder; a thickener; and an aqueous medium,
   Obtaining a sieve passing fraction (q) of the thickener powder by sieving a thickener powder containing a cellulose-based water-soluble polymer;
   Preparing an aqueous electrode slurry by mixing an electrode active material, an aqueous binder, the sieve passing portion (q) and an aqueous medium;
   A method for producing a water-based electrode slurry for a lithium ion battery, comprising:
2. In the method for producing a water-based electrode slurry for a lithium ion battery according to claim 1,
   When the maximum particle diameter of the sieve passing portion (q) in a volume-based particle size distribution by a laser diffraction / scattering particle size distribution measurement method is D ₁₀₀ [μm],
   By applying the sieve passing portion (q) to a sieve having an opening in the range of D ₁₀₀ (μm) or more and D ₁₀₀ +5 (μm) or less, the sieve passing portion (q) is obtained as a sieve residue and a sieve passing portion Manufacturing the aqueous electrode slurry for a lithium ion battery, wherein the ratio of the remaining on the sieve is 0.05% by mass or less when the total amount of the sieve passing part (q) is 100% by mass. Method.
3. In the manufacturing method of the water-based electrode slurry for lithium ion batteries of Claim 1 or 2,
   The step of preparing the aqueous electrode slurry comprises
   An aqueous electrode slurry for a lithium ion battery, comprising a step of preparing a mixture containing the electrode active material and the sieve passing portion (q) by dry-mixing the electrode active material and the sieve passing portion (q) in a powder state. Manufacturing method.
4. In the manufacturing method of the aqueous electrode slurry for lithium ion batteries of Claim 3,
   The step of preparing the aqueous electrode slurry comprises
   Wet mixing with one or two or more types of liquid components selected from the aqueous medium and the aqueous emulsion solution containing the aqueous binder added to the mixture containing the electrode active material and the sieve passing portion (q) Preparing a slurry precursor by
   Preparing the aqueous electrode slurry by further adding one or two or more types of liquid components selected from the aqueous medium and the aqueous emulsion solution containing the aqueous binder into the slurry precursor and wet mixing;
   A method of producing a water-based electrode slurry for lithium ion batteries, further comprising
5. A step of preparing a water-based electrode slurry by the method of producing a water-based electrode slurry for a lithium ion battery according to any one of claims 1 to 4.
   The step of forming an electrode active material layer on the substrate by coating the obtained aqueous electrode slurry on a substrate and drying it, and removing the aqueous medium.
   A method of producing an electrode for a lithium ion battery, comprising:
6. A thickener powder used to thicken an aqueous electrode slurry for lithium ion batteries,
   Contains cellulose-based water-soluble polymers,
   Assuming that the maximum particle diameter of the thickener powder in a volume-based particle size distribution by a laser diffraction / scattering particle size distribution measurement method is D ₁₀₀ [μm],
   The thickener powder was divided into a sieve residue and a sieve passing fraction by applying the thickener powder to a sieve having an opening of at least D ₁₀₀ (μm) and at least D ₁₀₀ +5 (μm). When the ratio of the said residue on a sieve is 0.05 mass% or less when the whole quantity of the said thickener powder is made into 100 mass%, the thickener powder for lithium ion batteries.
7. In the thickener powder for a lithium ion battery according to claim 6,
   A thickener powder for a lithium ion battery, wherein the cellulose-based water soluble polymer comprises at least one selected from carboxymethylcellulose and carboxymethylcellulose salt.
8. In the thickener powder for a lithium ion battery according to claim 6 or 7,
   The thickener powder for lithium ion batteries whose viscosity calculated by the following condition 1 is 10 mPa * s or more and 20000 mPa * s or less.
   (Condition 1: The thickener powder is dissolved in water to obtain an aqueous thickener solution having a concentration of 1.3% by mass Then, using a B-type viscometer, the shear rate is 3.4 s ^-1 at 25 ° C. Measure the viscosity of the aqueous thickener solution under the conditions.)
9. The thickener powder for a lithium ion battery according to any one of claims 6 to 8,
   The said sieving residue is a thickener powder for lithium ion batteries containing the fiber component derived from the said cellulose water soluble polymer.
10. An electrode active material selected from a positive electrode active material and a negative electrode active material;
    A water-based binder,
    The thickener powder for a lithium ion battery according to any one of claims 6 to 9,
    Aqueous medium,
    Including
    An aqueous electrode slurry, wherein the thickener powder for lithium ion batteries is dissolved in the aqueous medium.
11. An electrode active material selected from a positive electrode active material and a negative electrode active material;
    A water-based binder,
    An adhesive comprising the thickener powder for a lithium ion battery according to any one of claims 6 to 9,
    Electrodes for lithium ion batteries, including:
12. A lithium ion battery comprising at least a positive electrode, an electrolyte and a negative electrode,
    A lithium ion battery including at least one of the positive electrode and the negative electrode according to claim 11.

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