WO2024018997A1 - Conductive material dispersion liquid for electrochemical elements, slurry for electrochemical element electrodes, electrode for electrochemical elements, and electrochemical element - Google Patents

Abstract

A conductive material dispersion liquid for electrochemical elements according to the present invention contains a conductive material, a dispersant composition and a solvent. The dispersant composition contains a polymer A which comprises a linear alkylene structure unit having 4 or more carbon atoms, a nitrile group-containing monomer unit, and a polar functional group-containing monomer unit; and if a film that is formed of the dispersant composition is immersed in a propylene carbonate solution which contains Ni ions, the amount of Ni ions trapped by the dispersant composition is 10 mg to 800 mg per 1 g of the dispersant composition.

Description

Conductive material dispersion liquid for electrochemical devices, slurry for electrochemical device electrodes, electrodes for electrochemical devices, and electrochemical devices

The present invention relates to a conductive material dispersion liquid for electrochemical devices, a slurry for electrochemical device electrodes, an electrode for electrochemical devices, and an electrochemical device.

Electrochemical devices such as lithium ion secondary batteries, lithium ion capacitors, and electric double layer capacitors are small, lightweight, have high energy density, and can be repeatedly charged and discharged, and are used in a wide range of applications. . Here, the electrode of the electrochemical element includes, for example, a current collector and an electrode mixture layer formed by drying a slurry for an electrochemical element electrode coated on the current collector.

In recent years, attempts have been made to improve the slurry composition used to form the electrode mixture layer in order to improve the performance of electrochemical devices (Patent Documents 1 to 4).

For example, in Patent Document 1, the conductive material contains a binder A containing at least one of an alkylene structural unit and a (meth)acrylic acid ester monomer unit, and a solvent, and the binder adsorption amount of the conductive material is 100 mg/g. A conductive material paste for secondary battery electrodes having a content of 600 mg/g or less has been proposed. In Patent Document 1, by using the conductive material paste for secondary battery electrodes to prepare a slurry for secondary battery electrodes, the oxidation of the binder is suppressed and the potential of the electrode formed from the slurry for the electrodes is reduced. It has been reported that stability can be increased.

Patent Document 2 includes a conductive material, a first binder, a second binder, and a solvent, and the adsorption amount of the first binder to the conductive material is 110 mg/g or more and 1000 mg/g or less, and the amount of the second binder is 110 mg/g or more and 1000 mg/g or less. A conductive material for a secondary battery electrode, which has an adsorption amount on a conductive material of 0 mg/g or more and less than 110 mg/g, and a TI value (ratio of viscosity at 6 rpm to viscosity at 60 rpm) of 1.0 or more and 6.0 or less. material paste has been proposed. Patent Document 2 discloses that by using the conductive material paste for secondary battery electrodes in a slurry for secondary battery electrodes, it is possible to manufacture a positive electrode that can sufficiently reduce the direct current resistance of secondary batteries at low temperatures. has been reported.

Patent Document 3 describes a binder containing a polymerized unit having a nitrile group, an aromatic vinyl polymerized unit, a polymerized unit having a hydrophilic group, and a linear alkylene polymerized unit having 4 or more carbon atoms, the aromatic vinyl polymerized unit A binder composition for a secondary battery positive electrode has been proposed in which the content ratio of 5 to 50% by mass. Patent Document 3 reports that battery characteristics such as high-temperature cycling in a secondary battery can be improved by using a slurry composition for a secondary battery positive electrode containing the binder composition for a secondary battery positive electrode. There is.

Patent Document 4 discloses a binder composition for a secondary battery positive electrode containing a polymer, a nitrile group-containing monomer unit, an aromatic vinyl monomer unit, a hydrophilic group-containing monomer unit, and a conjugated diene monomer unit. and a linear alkylene structural unit having 4 or more carbon atoms, the content of aromatic vinyl monomer units in the polymer is 30.0% by mass or more and 60.0% by mass or less, and the polymer A binder composition for a secondary battery positive electrode having an iodine value of 60 mg/100 mg or more and 150 mg/100 mg or less has been proposed. Patent Document 4 reports that the output characteristics and cycle characteristics of a secondary battery can be improved by using a slurry composition for a secondary battery positive electrode containing the binder composition for a secondary battery positive electrode. .

Japanese Patent Application Publication No. 2015-191732 JP2016-66544A Japanese Patent Application Publication No. 2013-179040 International Publication No. 2019/131210

Here, the electrochemical device has the following features in terms of suppressing cracking and deterioration of the electrode active material in the electrode due to repeated charging and discharging, and improving the output characteristics, cycle characteristics, and life characteristics of the electrochemical device. There was room for further improvement.

Therefore, the present invention can suppress cracking and deterioration of the electrode active material in the electrode due to repeated charging and discharging, and can make the electrochemical device exhibit excellent output characteristics, cycle characteristics, and life characteristics. The present invention aims to provide a conductive material dispersion liquid for electrochemical devices and a slurry for electrochemical device electrodes.
In addition, the present invention suppresses cracking and deterioration of the electrode active material in the electrode due to repeated charging and discharging, and enables the electrochemical device to exhibit excellent output characteristics, cycle characteristics, and life characteristics. The purpose of the present invention is to provide an electrode for an electrochemical device.
A further object of the present invention is to provide an electrochemical element with excellent output characteristics, cycle characteristics, and life characteristics.

The present inventor conducted extensive studies in order to achieve the above object. The present inventor has proposed a conductive material dispersion liquid comprising a conductive material, a dispersant composition, and a solvent, wherein the dispersant composition contains a polymer A having a predetermined composition, and the dispersant composition contains a polymer A having a predetermined composition. It has been found that a conductive material dispersion liquid in which the Ni ion capture amount of the dispersant composition measured by the method described above is within a predetermined range has excellent dispersibility of the conductive material. Furthermore, by using the above-mentioned conductive material dispersion liquid, the present inventors were able to obtain an electrode in which cracking and deterioration of the electrode active material due to repeated charging and discharging were suppressed, and that the electrode was excellent in electrochemical elements. The present invention has been completed based on the discovery that it is possible to exhibit excellent output characteristics, cycle characteristics, and life characteristics.

That is, the present invention aims to advantageously solve the above problems, and according to the present invention, the following (1) to (7) conductive material dispersions for electrochemical elements, the following (8) The following slurry for an electrochemical device electrode, the following (9) electrode for an electrochemical device, and the following (10) an electrochemical device are provided.
(1) A conductive material dispersion liquid for an electrochemical element containing a conductive material, a dispersant composition, and a solvent, wherein the dispersant composition contains a linear alkylene structural unit having 4 or more carbon atoms and a nitrile group. When a film containing a polymer A containing a containing monomer unit and a polar functional group-containing monomer unit and consisting of the dispersant composition is immersed in a Ni ion-containing propylene carbonate solution, the dispersant A conductive material dispersion liquid for an electrochemical element, wherein the amount of Ni ion trapped in the composition is 10 mg or more and 800 mg or less per 1 g of the dispersant composition.
In this way, the dispersant composition contains a conductive material, a dispersant composition, and a solvent, the dispersant composition contains the polymer A having a predetermined composition, and the Ni of the dispersant composition is measured by a predetermined method. A conductive material dispersion liquid in which the amount of ion capture is within a predetermined range has excellent dispersibility of the conductive material. In addition, by using the above conductive material dispersion, it is possible to obtain an electrode in which cracking and deterioration of the electrode active material due to repeated charging and discharging are suppressed, and the electrode has excellent output characteristics and excellent output characteristics for electrochemical devices. It is possible to exhibit cycle characteristics and life characteristics.
In addition, in the present invention, the "monomeric unit" of a polymer means "a repeating unit derived from the monomer and contained in a polymer obtained using the monomer."
Further, in the present invention, the content ratio of each repeating unit (monomer unit and structural unit) in the polymer can be measured using a nuclear magnetic resonance (NMR) method such as ¹ H-NMR.
Furthermore, in the present invention, the "Ni ion capture amount" of the dispersant composition can be measured according to the method described in Examples. Moreover, "a film made of a dispersant composition" is a film obtained by drying a dispersant composition, and can be obtained according to the method described in Examples.

(2) The conductive material dispersion liquid for an electrochemical element according to (1) above, wherein the amount of the dispersant composition not adsorbed onto the conductive material is 15 mg or more and 1500 mg or less per 1 g of the conductive material.
In the present invention, the "amount of the dispersant composition not adsorbed to the conductive material" means the amount of the dispersant composition contained in the conductive material dispersion that is not adsorbed to the conductive material.
As described above, if the amount of the dispersant composition not adsorbed onto the conductive material is within the above range, cracking of the electrode active material in the electrode due to repeated charging and discharging can be further suppressed, and The cycle characteristics of the electrochemical device can be further improved.
In the present invention, the "amount of the dispersant composition not adsorbed onto the conductive material" can be measured according to the method described in Examples.

(3) The conductive material dispersion liquid for an electrochemical device according to (1) or (2) above, wherein the iodine value of the polymer A is 1 mg/100 mg or more and 60 mg/100 mg or less.
As described above, if the iodine value of the polymer A is within the above range, the viscosity of the conductive material dispersion for electrochemical devices is reduced, so that the dispersibility of the conductive material can be further improved, and the dispersant composition can be further improved. The amount of Ni ions captured can be further increased.
In the present invention, the "iodine value" of the polymer can be measured according to the method described in Examples.

(4) The conductive material dispersion for an electrochemical device according to any one of (1) to (3) above, wherein the polymer A has a weight average molecular weight of 5,000 or more and 150,000 or less.
As described above, if the weight average molecular weight of the polymer A is within the above range, the viscosity of the conductive dispersion liquid for electrochemical devices is further reduced, so that the dispersibility of the conductive material can be further improved, and the charging/discharging performance can be improved. It is possible to further suppress cracking of the electrode active material in the electrode due to repetition.
In the present invention, the "weight average molecular weight" of the polymer can be measured according to the method described in Examples.

(5) The conductive material dispersion for an electrochemical device according to any one of (1) to (4) above, wherein the conductive material contains at least carbon nanotubes.
In this way, if the conductive material contains at least carbon nanotubes, the dispersibility of the conductive material can be further improved.

(6) The content of the conductive material is 0.05% by mass or more and 10% by mass or less based on the entire conductive material dispersion for electrochemical elements, and the content of the dispersant composition is The conductive material dispersion for electrochemical devices according to any one of (1) to (5) above, which is 0.02% by mass or more and 8% by mass or less based on the entire conductive material dispersion for devices.
In this way, if the content of the conductive material is within the above range with respect to the entire conductive material for electrochemical elements, the viscosity of the conductive material dispersion further decreases, so that the dispersibility of the conductive material can be further improved. . Furthermore, cracking of the electrode active material in the electrode due to repeated charging and discharging can be further suppressed, and the output characteristics of the resulting electrochemical device can be further improved.

(7) The conductive material dispersion liquid for an electrochemical device according to any one of (1) to (6) above, having a solid content concentration of 0.1% by mass or more and 15% by mass or less.
As described above, if the solid content concentration is within the above range, the viscosity of the conductive material dispersion for electrochemical devices is further reduced, so that the dispersibility of the conductive material can be further improved, and the resulting electrochemical device is Output characteristics can be further improved.

(8) A slurry for an electrochemical device electrode, comprising at least the conductive material dispersion for an electrochemical device according to any one of (1) to (7) above and an electrode active material.
In this way, if the slurry for an electrochemical element electrode containing at least the conductive material dispersion liquid for an electrochemical element according to any one of (1) to (7) above and an electrode active material is used, the electrode can be An electrode in which cracking and deterioration of the active material are suppressed can be produced.

(9) An electrode for an electrochemical device, comprising an electrode mixture layer formed using the slurry for an electrochemical device electrode of (8) above.
As described above, in the electrode for an electrochemical device including the electrode mixture layer formed using the slurry for an electrochemical device electrode in (8) above, cracking and deterioration of the electrode active material due to repeated charging and discharging are suppressed. . Therefore, by using the electrode for an electrochemical device, the electrochemical device can exhibit excellent output characteristics, cycle characteristics, and life characteristics.

(10) An electrochemical device comprising the electrode for an electrochemical device according to (9) above.
As described above, an electrochemical device including the electrode for an electrochemical device according to (9) above has excellent output characteristics, cycle characteristics, and life characteristics.

According to the present invention, it is possible to suppress cracking and deterioration of the electrode active material in the electrode due to repeated charging and discharging, and it is possible to make the electrochemical device exhibit excellent output characteristics, cycle characteristics, and life characteristics. A conductive material dispersion liquid for electrochemical devices and a slurry for electrochemical device electrodes can be provided.
Furthermore, according to the present invention, cracking and deterioration of the electrode active material in the electrode due to repeated charging and discharging is suppressed, and the electrochemical device can exhibit excellent output characteristics, cycle characteristics, and life characteristics. It is possible to provide a possible electrode for an electrochemical device.
Furthermore, according to the present invention, it is possible to provide an electrochemical element with excellent output characteristics, cycle characteristics, and life characteristics.

Embodiments of the present invention will be described in detail below.
Here, the conductive material dispersion liquid for electrochemical devices of the present invention can be used when preparing a slurry for electrochemical device electrodes. Moreover, the slurry for electrochemical device electrodes of the present invention can be used when producing electrodes for electrochemical devices. Furthermore, the electrochemical device of the present invention includes an electrode for an electrochemical device produced using the slurry for an electrode of the present invention.

(Conductive material dispersion liquid for electrochemical devices)
The conductive material dispersion liquid for electrochemical elements of the present invention (hereinafter also simply referred to as "conductive material dispersion liquid") contains a conductive material, a dispersant composition, and a solvent, and optionally contains other components. . Note that the conductive material dispersion usually does not contain electrode active materials (positive electrode active material, negative electrode active material). Further, in the present invention, the dispersant composition usually does not contain a conductive material.

Further, the conductive material dispersion of the present invention is characterized in that the dispersant composition contained in the conductive material dispersion contains a linear alkylene structural unit having 4 or more carbon atoms, a nitrile group-containing monomer unit, and a polar functional group-containing monomer unit. The dispersant composition contains a polymer A containing a monomer unit, and the Ni ion capture amount of the dispersant composition measured by a predetermined method is 10 mg or more and 800 mg or less per 1 g of the dispersant composition. .

The conductive material dispersion of the present invention has the above-mentioned predetermined composition, and the amount of Ni ions captured in the dispersant composition is within the above-mentioned range. By using this method, cracking and deterioration of the electrode active material in the electrode due to repeated charging and discharging can be suppressed, and the electrochemical device can exhibit excellent output characteristics, cycle characteristics, and life characteristics.
Although the reason why the above-mentioned effects are obtained by using the conductive material dispersion of the present invention is not clear, it is presumed to be as follows.
In the conductive material dispersion liquid of the present invention, since the polymer A contained in the dispersant composition contains the above-mentioned predetermined monomer units and structural units, the polymer A can be used as both the conductive material and the electrode active material. In addition to being able to adsorb, the interaction between the polymers A is enhanced. Therefore, the polymer A adsorbs to the conductive material in the conductive material dispersion, thereby suppressing condensation of the conductive material and improving the dispersibility of the conductive material. Furthermore, if an electrode active material is blended into such a conductive material dispersion liquid to form a slurry composition, in the slurry composition, the polymer A adsorbed on the conductive material and the polymer A adsorbed on the electrode active material are combined. Due to the interaction, the electrode active material is uniformly covered with the conductive material via the polymer A. Therefore, by using the above slurry composition, it is possible to suppress the cracking of the electrode active material in the electrode due to repeated charging and discharging reactions, and also to form a good conductive path in the electrode to ensure a homogeneous charging and discharging reaction. can be converted into Further, according to the above electrode, since the amount of Ni ion captured by the dispersant composition in the conductive material dispersion is within the above-mentioned range, metal ions eluted from the electrode active material with repeated charging and discharging are absorbed into the polymer. Since it can be captured by A, deterioration of the electrode active material can be suppressed.

<Conductive material>
The conductive material is for ensuring electrical contact between electrode active materials. Examples of the conductive material include conductive carbon materials such as single-walled or multi-walled carbon nanotubes, carbon black (e.g., acetylene black, Ketjenblack (registered trademark), furnace black, etc.), graphite, and carbon break; various metals. Fibers, foils, etc. can be used. These can be used alone or in combination of two or more.

The conductive material preferably includes at least carbon nanotubes (hereinafter also referred to as "CNTs"). If the conductive material contains at least CNT, the dispersibility of the conductive material can be further improved.
Here, the proportion of CNT in the entire conductive material is not particularly limited, but it is preferably 50% by mass or more, more preferably 80% by mass or more, assuming the mass of the entire conductive material as 100% by mass, It is preferably 100% by mass or less, and particularly preferably 100% by mass (that is, the conductive material consists only of CNTs). If the proportion of CNTs in the entire conductive material is 50% by mass or more, a better conductive path can be formed in the electrode, and the charge/discharge reaction can be made more homogeneous.
Note that CNTs are not particularly limited, and those synthesized using known CNT synthesis methods such as arc discharge method, laser ablation method, and chemical vapor deposition method (CVD method) can be used. .

<<BET specific surface area of conductive material>>
The BET specific surface area of the conductive material in the conductive material dispersion is preferably 100 m ² /g or more, more preferably 150 m ² /g or more, and even more preferably 200 m ² /g or more. , 300 m ² /g or less. If the BET specific surface area of the conductive material is equal to or greater than the lower limit value, the viscosity of the conductive material dispersion further decreases, so that the dispersibility of the conductive material can be further improved. Further, if the BET specific surface area of the conductive material is equal to or larger than the above lower limit, the output characteristics of the resulting electrochemical device can be further improved.
In the present invention, "BET specific surface area" means a nitrogen adsorption specific surface area measured using the BET method.

<Dispersant composition>
The dispersant composition contains at least the polymer A having the above-mentioned predetermined composition, and optionally further contains a solvent and components other than the polymer A and the solvent (hereinafter referred to as "other components"). It is a thing. In addition, examples of the solvent that may be optionally included in the dispersant composition include the same solvents as those included in the conductive material dispersion of the present invention. In the present invention, if the conductive material dispersion liquid contains the polymer A, the conductive material dispersion liquid contains a dispersant composition. Other components that may be included in the dispersant composition include, for example, a polymerization initiator, a reducing agent, a chelating agent, and the like used when preparing the precursor of the polymer A.

<<Ni ion capture amount of dispersant composition>>
In the conductive material dispersion of the present invention, the amount of Ni ions trapped in the dispersant composition needs to be 10 mg or more per 1 g of the dispersant composition, preferably 50 mg or more, and preferably 100 mg or more. The amount is more preferably 800 mg or less, preferably 600 mg or less, and more preferably 400 mg or less. If the amount of Ni ions captured by the dispersant composition is within the above range, the use of the conductive material dispersion of the present invention will suppress elution of metal ions from the electrode active material in the electrode due to repeated charging and discharging. Thus, deterioration of the electrode active material can be suppressed.

<<Amount of dispersant composition not adsorbed onto conductive material>>
Furthermore, in the conductive material dispersion of the present invention, the amount of the dispersant composition not adsorbed onto the conductive material (hereinafter also referred to as "non-adsorbed amount of conductive material") is preferably 15 mg or more per 1 g of the conductive material. , more preferably 25 mg or more, even more preferably 40 mg or more, preferably 1500 mg or less, more preferably 1000 mg or less, and even more preferably 800 mg or less. If the amount of the dispersant composition that does not adsorb the conductive material is 15 mg or more per 1 g of the conductive material, cracking of the electrode active material in the electrode due to repeated charging and discharging can be further suppressed. Further, if the amount of the dispersant composition that does not adsorb the conductive material is 1500 mg or less per gram of the conductive material, the cycle characteristics of the resulting electrochemical device can be further improved.

[Polymer A]
Polymer A contained in the dispersant composition is a component that favorably disperses the conductive material in the conductive material dispersion liquid. In addition, in an electrode equipped with an electrode composite layer prepared using an electrode slurry containing a conductive material dispersion liquid and an electrode active material, the components contained in the electrode composite material layer are retained so as not to separate from the electrode composite material layer. It is a component that can be used. In the conductive material dispersion of the present invention, the polymer A contains a linear alkylene structural unit having 4 or more carbon atoms, a nitrile group-containing monomer unit, and a polar functional group-containing monomer unit. Requires.

- Straight chain alkylene structural unit with 4 or more carbon atoms -
A linear alkylene structural unit having 4 or more carbon atoms (hereinafter also simply referred to as an "alkylene structural unit") is a straight-chain alkylene structural unit having 4 or more carbon atoms represented by the general formula: -C _n H _2n - [where n is an integer of 4 or more] It is a repeating unit composed only of the above linear alkylene structure. Since Polymer A contains a linear alkylene structural unit having 4 or more carbon atoms, Polymer A easily adsorbs to the conductive material, thereby suppressing agglomeration of the conductive material, thereby improving the dispersibility of the conductive material. be able to.

Here, the method of introducing the linear alkylene structural unit having 4 or more carbon atoms into the polymer is not particularly limited, but for example, the following method (1) or (2):
(1) By preparing a polymer from a monomer composition containing a conjugated diene monomer and hydrogenating the polymer, the conjugated diene monomer unit is converted into a linear alkylene structural unit having 4 or more carbon atoms. Conversion method (2) A method of preparing a polymer from a monomer composition containing a 1-olefin monomer having 4 or more carbon atoms such as 1-butene and 1-hexene. These conjugated diene monomers and 1-olefin monomers can be used alone or in combination of two or more.
Among these, method (1) is preferred because it allows easy production of the polymer.

Conjugated diene monomers that can be used in the method (1) above include, for example, 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, etc. having 4 or more carbon atoms. Examples include conjugated diene compounds. Among them, 1,3-butadiene is preferred. That is, the linear alkylene structural unit having 4 or more carbon atoms is preferably a structural unit obtained by hydrogenating a conjugated diene monomer unit (conjugated diene hydride unit), and is preferably a structural unit obtained by hydrogenating a 1,3-butadiene unit. A structural unit (1,3-butadiene hydride unit) obtained by The selective hydrogenation of the conjugated diene monomer unit can be performed using a known method such as an oil layer hydrogenation method or an aqueous layer hydrogenation method.

In addition, when the linear alkylene structural unit having 4 or more carbon atoms is introduced into the polymer by the method (1) above, if the conjugated diene monomer is not completely hydrogenated, the polymer A Conjugated diene monomer units may remain therein. In other words, the polymer A may optionally contain a conjugated diene monomer unit as a repeating unit.

The content ratio of linear alkylene structural units having 4 or more carbon atoms in polymer A is, when the total repeating units (total of structural units and monomer units) in polymer A is 100% by mass. It is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, preferably 80% by mass or less, and preferably 75% by mass or less. The content is more preferably 70% by mass or less. If the content of linear alkylene structural units having 4 or more carbon atoms in the polymer A is within the above range, the dispersibility of the conductive material can be further improved.
In addition, when the polymer A contains a conjugated diene monomer unit, the total content of the conjugated diene monomer unit and the linear alkylene structural unit having 4 or more carbon atoms in the polymer is within the above-mentioned preferred range. It is preferable to meet the requirements.

-Nitrile group-containing monomer unit-
The nitrile group-containing monomer unit is a repeating unit derived from a nitrile group-containing monomer. Monomers that can form nitrile group-containing monomer units include α,β-ethylenically unsaturated nitrile monomers. Examples of α,β-ethylenically unsaturated nitrile monomers include acrylonitrile; α-halogenoacrylonitrile such as α-chloroacrylonitrile and α-bromoacrylonitrile; α-alkylacrylonitrile such as methacrylonitrile and α-ethyl acrylonitrile; Examples include. Among these, as the nitrile group-containing monomer, acrylonitrile and methacrylonitrile are preferred, and acrylonitrile is more preferred.
These can be used alone or in combination of two or more.

The proportion of nitrile group-containing monomer units in polymer A is 10% by mass when the total repeating units (total of structural units and monomer units) in polymer A is 100% by mass. It is preferably at least 15% by mass, more preferably at least 20% by mass, even more preferably at most 50% by mass, more preferably at most 45% by mass, More preferably, it is 40% by mass or less. If the content of the nitrile group-containing monomer unit in the polymer A is within the above range, the viscosity of the conductive material dispersion is further reduced, so that the dispersibility of the conductive material can be further improved.

-Polar functional group-containing monomer unit-
A polar functional group-containing monomer unit is a monomer unit derived from a monomer having a polar functional group. By containing a polar group-containing monomer unit, the polymer A is easily adsorbed to the electrode active material, and can interact with the electrode active material to capture metal ions eluted from the electrode active material. In the present invention, the monomers having a polar functional group and included in the above-mentioned nitrile group-containing monomers are not included in the polar functional group-containing monomers.
Here, examples of the polar functional group possessed by the polar functional group-containing monomer include an amino group, a carboxyl group, a hydroxyl group, and a carbonyl group. Examples of monomers that can form polar functional group-containing monomer units include (meth)acrylic acid, diethylaminoethyl methacrylate, hydroxyethyl methacrylate, and allylamine, among which (meth)acrylic acid, Diethylaminoethyl methacrylate is preferred.
These can be used alone or in combination of two or more.

The proportion of polar functional group-containing monomer units in polymer A is 7% by mass when all repeating units (total of structural units and monomer units) in polymer A are 100% by mass. % or more, more preferably 9% by mass or more, preferably 20% by mass or less, and more preferably 15% by mass or less. If the proportion of the polar functional group-containing monomer units in the polymer A is within the above range, the amount of Ni ions trapped in the dispersant composition can be further increased.

-Other monomer units-
Polymer A contains other repeating units other than the above-mentioned linear alkylene structural units having 4 or more carbon atoms, conjugated diene monomer units, nitrile group-containing monomer units, and polar functional group-containing monomer units. It may further contain monomer units (hereinafter referred to as "other monomer units").
Other monomer units are not particularly limited, and include, for example, aromatic vinyl monomer units and (meth)acrylic acid ester monomer units. Among these, aromatic vinyl monomer units are preferred as other monomer units.
The number of other monomer units contained in the polymer A may be one type or a combination of two or more types in any ratio.
In the present invention, "(meth)acrylic acid" means acrylic acid and/or methacrylic acid.

=Aromatic vinyl monomer unit=
Aromatic vinyl monomer units are repeating units derived from aromatic vinyl monomers. Examples of aromatic vinyl monomers that can form aromatic vinyl monomer units include styrene, α-methylstyrene, pt-butylstyrene, butoxystyrene, vinyltoluene, chlorostyrene, and vinylnaphthalene. . Among these, styrene is preferred as the aromatic vinyl monomer.
These can be used alone or in combination of two or more.

= (meth)acrylic acid ester monomer unit =
(Meth)acrylate monomers that can form the (meth)acrylate monomer unit include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, and t-butyl acrylate. octyl acrylate such as butyl acrylate, pentyl acrylate, hexyl acrylate, heptyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate; and methyl methacrylate, Butyl methacrylates such as ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate and t-butyl methacrylate, octyl methacrylates such as pentyl methacrylate, hexyl methacrylate, heptyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl Examples include methacrylic acid alkyl esters such as methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate. Among these, n-butyl acrylate, 2-ethylhexyl acrylate and methyl methacrylate are preferred as the (meth)acrylic ester monomer.
These can be used alone or in combination of two or more.

The content ratio of other monomer units in polymer A is 20% by mass when the total repeating units (total of structural units and monomer units) in polymer A is 100% by mass. It is preferably at most 15% by mass, more preferably at most 10% by mass, and even more preferably at most 10% by mass. Further, the lower limit of the content of other monomer units in the polymer A is not particularly limited, and can be, for example, 0% by mass or more.

[Method for preparing polymer A]
The method for preparing the above-mentioned polymer A is not particularly limited, and for example, after obtaining a polymer by polymerizing a monomer composition containing the above-mentioned monomers optionally in the presence of a chain transfer agent, It can be prepared by hydrogenating (hydrogenating) the obtained polymer.

Here, the content ratio of each monomer in the monomer composition used for preparing the polymer A can be determined according to the content ratio of each repeating unit in the polymer A.
The polymerization method is not particularly limited, and any method such as solution polymerization, suspension polymerization, bulk polymerization, and emulsion polymerization can be used. Note that as the polymerization reaction, any reaction such as ionic polymerization, radical polymerization, living radical polymerization, etc. can be used. Furthermore, known polymerization initiators can be used as the polymerization initiator.
Furthermore, the method for hydrogenating the polymer is not particularly limited, and a general method using a catalyst (for example, see International Publication No. 2012/165120, International Publication No. 2013/080989, and Japanese Patent Application Laid-Open No. 2013-8485) can be used. can be used.

<Properties of polymer A>
[Iodine value of polymer A]
The iodine value of polymer A is preferably 1 mg/100 mg or more, preferably 60 mg/100 mg or less, more preferably 50 mg/100 mg or less, and even more preferably 30 mg/100 mg or less. preferable. If the iodine value of the polymer A is equal to or higher than the above lower limit, the viscosity of the conductive material dispersion further decreases, so that the dispersibility of the conductive material can be further improved. Moreover, if the iodine number of the polymer A is below the said upper limit, the amount of Ni ions captured by the dispersant composition can be further increased.
Note that the iodine value of the polymer can be controlled, for example, by changing the hydrogenation conditions during production of the polymer A.

[Weight average molecular weight of polymer A]
The weight average molecular weight of the polymer A is preferably 5,000 or more, more preferably 10,000 or more, even more preferably 15,000 or more, preferably 150,000 or less, and more preferably 100,000 or less. It is preferably 80,000 or less, and more preferably 80,000 or less. If the weight average molecular weight of the polymer A is greater than or equal to the above lower limit, the viscosity of the conductive material dispersion is further reduced, so that the dispersibility of the conductive material can be further improved. Moreover, if the weight average molecular weight of the polymer A is below the above upper limit, cracking of the electrode active material in the electrode due to repeated charging and discharging can be further suppressed.

<Solvent>
The solvent contained in the conductive material dispersion is not particularly limited, and both water and organic solvents can be used. Examples of the organic solvent include N-methylpyrrolidone (NMP), N,N-dimethylformamide, and acetone. As the organic solvent, it is preferable to use N-methylpyrrolidone (NMP).
One type of solvent may be used alone, or two or more types may be used as a mixture in any ratio.

<Other ingredients>
Other components that may be included in the conductive material dispersion include, for example, reinforcing materials, leveling agents, viscosity modifiers, electrolyte additives, and the like. These are not particularly limited as long as they do not affect the element reaction of the electrochemical element, and known ones, such as those described in International Publication No. 2012/115096, can be used.
One type of these components may be used alone, or two or more types may be used in combination in any ratio.

<<Content of conductive material>>
In the conductive material dispersion of the present invention, the content of the conductive material is not particularly limited, but is preferably 0.05% by mass or more and 10% by mass or less based on the entire conductive material dispersion. If the content of the conductive material is 0.05% by mass or more, the viscosity of the conductive material dispersion further decreases, so that the dispersibility of the conductive material can be further improved. Furthermore, if the content of the conductive material is 10% by mass or less, cracking of the electrode active material in the electrode due to repeated charging and discharging can be further suppressed.

<Content of dispersant composition>
Further, in the conductive material dispersion of the present invention, the content of the dispersant composition is not particularly limited, but it is preferably 0.02% by mass or more, and 0.05% by mass based on the entire conductive material dispersion. % or more, still more preferably 1% by mass or more, preferably 8% by mass or less, more preferably 6% by mass or less, and even more preferably 4% by mass or less. preferable. If the content of the dispersant composition in the conductive material dispersion is equal to or greater than the above lower limit with respect to the entire conductive material dispersion, the output characteristics of the resulting electrochemical device can be further improved. In addition, if the content of the dispersant composition in the conductive material dispersion is less than the above upper limit with respect to the entire conductive material dispersion, the viscosity of the conductive material dispersion will further decrease, so the dispersibility of the conductive material will be reduced. It can be further improved.

<Solids concentration of conductive material dispersion>
Further, the solid content concentration of the conductive material dispersion of the present invention (that is, the proportion of solid content in the entire conductive material dispersion) is preferably 0.1% by mass or more, and preferably 1% by mass or more. It is more preferably 3% by mass or more, still more preferably 15% by mass or less, more preferably 11% by mass or less, and even more preferably 9% by mass or less. If the solid content concentration of the conductive material dispersion is equal to or higher than the above lower limit, the viscosity of the conductive material dispersion is further reduced, so that the dispersibility of the conductive material can be further improved. Moreover, if the solid content concentration of the conductive material dispersion liquid is below the above upper limit value, the output characteristics of the resulting electrochemical device can be further improved.

<Method for preparing conductive material dispersion liquid for electrochemical devices>
The conductive material dispersion of the present invention can be prepared by mixing the above-described conductive material, a dispersant composition, a solvent, and other optional components. The mixing method is not particularly limited, and for example, general mixing devices such as a disper, mill, kneader, mixer, etc. can be used.

In order to fully exhibit the effects of the present invention, the conductive material dispersion liquid is prepared by, for example, combining the above-mentioned conductive material, dispersant composition, solvent, and any other components in at least two stages. It is preferable to prepare by a method of mixing through a dispersion process (a first dispersion process and a second dispersion process). In such a method, the dispersant composition can be adjusted by adjusting the conditions of the dispersion treatment (type of dispersion device, rotation speed and peripheral speed, time and temperature of the dispersion treatment) in the first dispersion step and/or the second dispersion step. The amount of Ni ions captured in the object can be easily controlled.

Hereinafter, suitable conditions for controlling the amount of Ni ion captured by the dispersant composition in the conductive material dispersion liquid within a predetermined range through a two-stage dispersion process will be described. In this embodiment, the two-stage dispersion process usually uses different dispersion devices. By using different dispersion devices in the two-stage dispersion process, it is possible to apply different dispersion processes to the objects to be dispersed at the initial stage of dispersion (coarse dispersion stage) and at the latter stage of dispersion (main stage). The amount of Ni ions trapped in the agent composition can be easily controlled.
Note that in this embodiment, steps other than the first dispersion step and the second dispersion step may be performed.

<<First dispersion step>>
In the first dispersion step, a composition containing at least a conductive material, a dispersant composition, and a solvent is subjected to a dispersion treatment to obtain a rough dispersion. The first dispersion step is a step whose main purpose is to wet (mix) the conductive material to be dispersed, the dispersant composition, and the solvent.

Examples of the dispersion device used in the first dispersion step include a disper, a homomixer, a planetary mixer, a kneader, and a ball mill. As the dispersion device used in the first dispersion step, a disper or a planetary mixer is preferable, and a disper is more preferable.

When a disper is used as a dispersion device, the rotation speed is preferably 500 rpm or more, more preferably 1,000 rpm or more, even more preferably 2,000 rpm or more, and 8,000 ppm or less. The speed is preferably 7,000 rpm or less, and even more preferably 6,000 rpm or less.

The time for the dispersion treatment in the first dispersion step is not particularly limited, but is preferably 5 minutes or more, more preferably 8 minutes or more, and preferably 15 minutes or less.

The temperature of the dispersion treatment in the first dispersion step is not particularly limited, but is preferably 5°C or higher, more preferably 10°C or higher, even more preferably 20°C or higher, and 50°C or lower. The temperature is preferably 45°C or lower, more preferably 35°C or lower, and even more preferably 35°C or lower.

<<Second dispersion process>>
In the second dispersion step, the crude dispersion obtained in the first dispersion step is further subjected to a dispersion treatment to obtain a conductive material dispersion. The second dispersion step is a step whose main purpose is to apply shearing force and collision energy in order to disperse and defibrate the conductive material that is the object to be dispersed.

As mentioned above, the second dispersion step usually uses a different dispersion device from that used in the first dispersion step. Examples of the dispersion device used in the second dispersion step include a disper, a homomixer, a planetary mixer, a kneader, a ball mill, and a thin film swirl type high-speed mixer such as Filmix (registered trademark). As the dispersion device used in the second dispersion step, a dispersion device that does not use media (that is, medialess) is preferable, and a thin film swirl type high-speed mixer is more preferable.

When a thin film swirl type high-speed mixer is used as a dispersion device, the circumferential speed is preferably 10 m/sec or more, more preferably 20 m/sec or more, even more preferably 25 m/sec or more, and 45 m/sec or more. The speed is preferably at most 40 m/sec, more preferably at most 40 m/sec, even more preferably at most 35 m/sec.

The dispersion treatment time in the second dispersion step is preferably 2 minutes or more, more preferably 3 minutes or more, even more preferably 4 minutes or more, preferably 20 minutes or less, and 10 minutes or more. It is more preferable that the heating time is 7 minutes or less, and even more preferably 7 minutes or less. When the dispersion treatment time is within the above range, homogenization of the conductive material dispersion can be promoted, and the viscosity can be reduced and the viscosity stability can be improved.

(Slurry for electrochemical device electrodes)
The electrochemical element electrode slurry of the present invention (hereinafter also simply referred to as "electrode slurry") contains at least the above-mentioned conductive material dispersion and an electrode active material, and optionally contains other components and a binder. Further contains. That is, the electrode slurry of the present invention contains at least a conductive material, a polymer A, a solvent, and an electrode active material, and optionally further contains other components and/or a binder. Since the electrode slurry of the present invention contains the above-mentioned conductive material dispersion, by using the electrode slurry, it is possible to create an electrode in which cracking and deterioration of the electrode active material due to repeated charging and discharging are suppressed. can do.

In addition, although the case where the slurry for electrochemical element electrodes of this invention is slurry for lithium ion secondary battery positive electrodes is demonstrated below as an example, this invention is not limited to the following example.

<Conductive material dispersion>
As the conductive material dispersion, the conductive material dispersion of the invention described above is used.

<Electrode active material>
The electrode active material is a material that transfers the battery at the electrode of the secondary battery. As a positive electrode active material for a lithium ion secondary battery, a material that can intercalate and deintercalate lithium is usually used.
The positive electrode active materials used in lithium ion secondary batteries are not particularly limited, and include lithium-containing cobalt oxide (LiCoO ₂ ), lithium manganate (LiMn ₂ O ₄ ), and lithium-containing nickel oxide (LiNiO ₂ ). , Co-Ni-Mn lithium-containing composite oxide, Ni-Mn-Al lithium-containing composite oxide, Ni-Co-Al lithium-containing composite oxide, olivine type lithium manganese phosphate (LiMnPO ₄ ), olivine type Lithium iron phosphate (LiFePO ₄ ), lithium-excess spinel compound represented by Li _1+x Mn _2-x O ₄ (0<X<2), Li[Ni _0.17 Li _0.2 Co _0.07 Mn _{0 .56} ]O ₂ , LiNi _0.5 Mn _1.5 O ₄ and the like can be used as positive electrode active materials. Note that the lithium-containing composite oxide of Co-Ni-Mn includes Li(Ni _0.6 Co _0.2 Mn _0.2 )O ₂ and Li(Ni _0.5 Co _0.2 Mn _0.3 )O. ₂ , Li(Ni _1/3 Co _1/3 Mn _1/3 ) O ₂ and the like.
Among the above, from the viewpoint of improving the battery capacity of lithium ion secondary batteries, the positive electrode active materials include lithium-containing cobalt oxide (LiCoO ₂ ), lithium-containing nickel oxide (LiNiO ₂ ), Co-Ni- It is preferable to use a lithium-containing composite oxide of Mn, Li[Ni _0.17 Li _0.2 Co _0.07 Mn _0.56 ]O ₂ or LiNi _0.5 Mn _1.5 O ₄ , and Co-Ni- It is more preferable to use a lithium-containing composite oxide of Mn.
Note that the blending amount and particle size of the positive electrode active material are not particularly limited, and can be the same as those of conventionally used positive electrode active materials. Moreover, one type of positive electrode active material may be used alone, or two or more types may be used in combination in any ratio.

<Other ingredients>
Other components that may be included in the electrode slurry are not particularly limited, and include, for example, the same components as those that may be included in the dispersant composition described above. As for the other components, one type may be used alone, or two or more types may be used in combination in any ratio.

<Binder>
The binder that may be optionally included in the electrode slurry is not particularly limited, but for example, fluorine-containing resins such as polyvinylidene fluoride (PVDF), polyacrylonitrile (PAN), and polyvinyl alcohol (PVOH) are preferred; Resins and PAN are more preferred, and fluorine-containing resins are even more preferred.

<Method for preparing slurry for electrochemical device electrodes>
The electrode slurry of the present invention can be prepared by mixing the above-described conductive material dispersion, an electrode active material, and any other components and/or binder by a known method. The electrode slurry of the present invention can also be prepared by preparing the conductive material dispersion of the present invention in advance, and adding and mixing the electrode active material to the conductive material dispersion. Among them, from the viewpoint of dispersing the conductive material well, an electrode slurry is prepared by adding and mixing the electrode active material and any other components and/or binder to the conductive material dispersion liquid. It is preferable.
In addition, mixing can be performed using a mixer such as a ball mill, a sand mill, a bead mill, a pigment dispersion machine, a crusher, an ultrasonic dispersion machine, a homogenizer, a planetary mixer, and a film mix.

(Electrode for electrochemical elements)
The electrode for an electrochemical device of the present invention includes an electrode mixture layer formed using the electrode slurry of the present invention described above. That is, the electrode composite material layer contains at least the above-mentioned conductive material, polymer A, and electrode active material, and optionally contains other components and/or a binder. In addition, each component contained in the electrode mixture layer was contained in the above-mentioned electrode slurry, and the preferable abundance ratio of each component is determined by the preferable abundance ratio of each component in the electrode slurry. It is the same as the abundance ratio.
Furthermore, since the electrode for an electrochemical device of the present invention includes an electrode composite material layer formed using an electrode slurry containing the conductive material dispersion of the present invention, the electrode active material decreases due to repeated charging and discharging. Cracking and deterioration are suppressed. Therefore, according to the electrode for an electrochemical device of the present invention, the electrochemical device can exhibit excellent output characteristics, cycle characteristics, and life characteristics.

<Method for manufacturing electrodes for electrochemical devices>
The electrode for an electrochemical device of the present invention can be produced by, for example, a step of applying the above-mentioned electrode slurry onto a current collector (coating step), and drying the electrode slurry applied onto the current collector. It is manufactured through a process of forming an electrode mixture layer thereon (drying process).

<<Coating process>>
The method for applying the electrode slurry onto the current collector is not particularly limited, and any known method can be used. Specifically, as a coating method, a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, a brush coating method, etc. can be used. At this time, the electrode slurry may be applied to only one side of the current collector, or may be applied to both sides. The thickness of the slurry film on the current collector after coating and before drying can be appropriately set depending on the thickness of the electrode mixture layer obtained by drying.

Here, as the current collector to which the electrode slurry is applied, a material that has electrical conductivity and is electrochemically durable is used. Specifically, as the current collector, for example, a current collector made of iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, platinum, etc. can be used. Note that the above-mentioned materials may be used alone or in combination of two or more in any ratio.

<<Drying process>>
The method for drying the electrode slurry on the current collector is not particularly limited and any known method can be used, such as drying with hot air, hot air, low humidity air, vacuum drying, or irradiation with infrared rays or electron beams. An example is a drying method. By drying the electrode slurry on the current collector in this manner, it is possible to form an electrode mixture layer on the current collector and obtain an electrode for an electrochemical element including the electrode mixture layer.

Note that after the drying step, the electrode composite material layer may be subjected to pressure treatment using a mold press, a roll press, or the like. The pressure treatment allows the electrode mixture layer to adhere well to the current collector.

(electrochemical device)
The electrochemical device of the present invention includes the electrode for electrochemical device of the present invention described above. Since the electrochemical device of the present invention includes the electrode for electrochemical device of the present invention, it has excellent output characteristics, cycle characteristics, and life characteristics. Note that the electrochemical device of the present invention may be, for example, an electric double layer capacitor or a non-aqueous secondary battery such as a lithium ion secondary battery.
When the electrochemical device of the present invention is a nonaqueous secondary battery such as a lithium ion secondary battery, the nonaqueous secondary battery includes a positive electrode, a negative electrode, an electrolyte, and a separator, The electrode for an electrochemical device of the present invention is used as at least one of a positive electrode and a negative electrode. Furthermore, the non-aqueous secondary battery as an electrochemical device of the present invention preferably uses the electrode for electrochemical device of the present invention as a positive electrode.
In addition, although the case where an electrochemical element is a lithium ion secondary battery is demonstrated below as an example, this invention is not limited to the following example.

<Electrode>
Here, electrodes other than the above-mentioned electrochemical element electrodes that can be used in the lithium ion secondary battery as the electrochemical element of the present invention are not particularly limited, and can be used in the manufacture of the lithium ion secondary battery. Any known electrode can be used. Specifically, as an electrode other than the above-mentioned electrode for an electrochemical device, an electrode formed by forming an electrode mixture layer on a current collector using a known manufacturing method can be used.

<Electrolyte>
As the electrolytic solution, an organic electrolytic solution in which a supporting electrolyte is dissolved in an organic solvent is usually used. As the supporting electrolyte, for example, lithium salt is used. Examples of lithium salts include LiPF ₆ , LiAsF ₆ , LiBF ₄ , LiSbF ₆ , LiAlCl ₄ , LiClO ₄ , CF ₃ SO ₃ Li, C ₄ F ₉ SO ₃ Li, CF ₃ COOLi, (CF ₃ CO) ₂ NLi. , (CF ₃ SO ₂ ) ₂ NLi, (C ₂ F ₅ SO ₂ ) NLi, and the like. Among these, LiPF ₆ , LiClO ₄ and CF ₃ SO ₃ Li are preferred, and LiPF ₆ is particularly preferred, since they are easily soluble in solvents and exhibit a high degree of dissociation. Note that one type of electrolyte may be used alone, or two or more types may be used in combination in any ratio. Usually, the lithium ion conductivity tends to increase as a supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted depending on the type of supporting electrolyte.

The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte, but examples include dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), Carbonates such as butylene carbonate (BC) and methyl ethyl carbonate (EMC); Esters such as γ-butyrolactone and methyl formate; Ethers such as 1,2-dimethoxyethane and tetrahydrofuran; Sulfur-containing compounds such as sulfolane and dimethyl sulfoxide etc. are preferably used. Alternatively, a mixture of these solvents may be used. Note that the concentration of the electrolyte in the electrolytic solution can be adjusted as appropriate.

<Separator>
The separator is not particularly limited, and for example, those described in JP-A No. 2012-204303 can be used. Among these, polyolefins are preferred because they can reduce the overall film thickness of the separator, thereby increasing the ratio of the electrode active material in the lithium ion secondary battery and increasing the capacity per volume. A microporous membrane made of a resin of the type (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred. In addition, the separator may be a separator with an adhesive layer formed on the surface of the microporous membrane, or a separator with an adhesive layer formed on the surface of the microporous membrane, or a separator with an adhesive layer formed on the surface of the microporous membrane. A separator with a heat-resistant layer may also be used.

<Method for manufacturing electrochemical element>
A lithium ion secondary battery as an electrochemical element is produced by, for example, stacking a positive electrode and a negative electrode with a separator interposed therebetween, then rolling or folding this according to the battery shape as necessary and placing it in a battery container. It can be manufactured by injecting an electrolyte into a battery container and sealing it. In order to prevent the occurrence of pressure rise inside the lithium ion secondary battery, overcharging and discharging, etc., fuses, overcurrent prevention elements such as PTC elements, expanded metal, lead plates, etc. may be provided as necessary. . The shape of the secondary battery may be, for example, a coin shape, a button shape, a sheet shape, a cylindrical shape, a square shape, a flat shape, or the like.

EXAMPLES Hereinafter, the present invention will be specifically explained based on Examples, but the present invention is not limited to these Examples. In the following description, "%" and "part" representing amounts are based on mass unless otherwise specified.
In addition, in a polymer produced by copolymerizing multiple types of monomers, the proportion of monomer units formed by polymerizing a certain monomer in the polymer is usually , corresponds to the ratio of the certain monomer to the total monomers used in the polymerization of the polymer (feeding ratio). In addition, when the polymer is a hydrogenated polymer obtained by hydrogenating (hydrogenating) a polymer containing conjugated diene monomer units, unhydrogenated conjugated diene monomer in the hydrogenated polymer The total content ratio of the unit and the alkylene structural unit as a hydrogenated conjugated diene monomer unit is the ratio of the conjugated diene monomer to the total monomers used for polymerization of the polymer (preparation ratio) matches.
In Examples and Comparative Examples, various measurements and evaluations were performed using the following methods.

<Weight average molecular weight of polymer>
The weight average molecular weight (Mw) of the polymer was measured by gel permeation chromatography (GPC) using a LiBr-DMF solution with a concentration of 10 mM under the following measurement conditions.
・Separation column: Shodex KD-806M (manufactured by Showa Denko Co., Ltd.)
・Detector: Differential refractometer detector RID-10A (manufactured by Shimadzu Corporation)
・Flow rate of eluent: 0.3 mL/min ・Column temperature: 40°C
・Standard polymer: TSK standard polystyrene (manufactured by Tosoh Corporation)

<Iodine value of polymer>
100 g of the aqueous dispersion of polymer A prepared in Examples and Comparative Examples was coagulated with 1 L of methanol, and then vacuum-dried at a temperature of 60° C. for 12 hours. Then, the iodine value of the obtained dry polymer was measured according to JIS K6235 (2006).

<Ni ion capture amount of dispersant composition>
The amount of Ni ion trapped in the dispersant compositions prepared in Examples and Comparative Examples was measured according to the following procedure.
First, the dispersant composition (NMP solution of polymer) was placed in a Teflon (registered trademark) Petri dish so that the solid content was 1.5 g, and dried at 130°C for 4 hours to obtain a film of the dispersant composition. . Next, a Ni ion-containing PC solution was prepared by dissolving nickel chloride in propylene carbonate (PC) so that the Ni ion concentration was 5 ppm. 0.1 g of the film of the dispersant composition was immersed in 30 g of Ni ion-containing PC solution and left at 60° C. for 90 hours. After being allowed to stand still, the film of the dispersant composition was taken out. The Ni ion concentration in the Ni ion-containing PC solution after immersing the film of the dispersion composition in the Ni ion-containing PC solution by flame atomic absorption spectrometry (JIS K 0102-59.2) using an atomic absorption photometer C2 (ppm) was quantified. Then, the amount of Ni ion trapped in the dispersant composition was calculated based on the following formula.
Formula: Ni ion capture amount of dispersant composition [ppm] = 30 x (C1-C2)/W
[In the formula, C1 is the Ni ion concentration (5 ppm) in the Ni ion-containing PC solution before immersing the film of the dispersant composition in the Ni ion-containing PC solution, and C2 is the concentration of Ni ions in the Ni ion-containing PC solution before immersing the film of the dispersant composition This is the Ni ion concentration in the Ni ion-containing PC solution after the sample is immersed in the Ni ion-containing PC solution, and W is the mass (0.1 g) of the film of the dispersant composition. ]

<Non-adsorption amount of conductive material of dispersant composition>
Regarding the conductive material dispersions prepared in Examples and Comparative Examples, the amount of conductive material not adsorbed by the dispersant composition was measured according to the following procedure.
The conductive material dispersion prepared in Examples and Comparative Examples was filtered using a membrane filter with a pore size of 0.2 μm to remove the conductive material in the conductive material dispersion and the dispersant composition adsorbed on the conductive material. A filtrate was obtained. Next, the amount (X) of the dispersant composition in the filtrate was determined using liquid chromatography. Then, from the amount (X) of the dispersant composition in the filtrate and the amount (Y) of the conductive material contained in the conductive material dispersion, the dispersant composition per 1 g of the conductive material is determined based on the following formula. The amount of conductive material not adsorbed was calculated.
Formula: Non-adsorbed amount of conductive material of dispersant composition = X/Y
Note that the measurement conditions for liquid chromatography are as follows.
・Device: LC-2030 (manufactured by Shimadzu Corporation)
・Separation column: TSKgel α-M, 3 pieces (manufactured by Tosoh Corporation)
・Detector: Differential refractometer detector RID-10A (manufactured by Shimadzu Corporation)
・Eluent: LiBr-NMP solution with a concentration of 10mM ・Eluent flow rate: 0.5 mL/min ・Column temperature: 40°C

<Viscosity of conductive material dispersion>
The viscosity of the conductive material dispersions prepared in Examples and Comparative Examples was measured using a rheometer (MCR302 manufactured by Anton Paar) at a temperature of 25°C and a shear rate of 10 s ^-1 , and the viscosity was measured according to the following criteria. It was evaluated. Note that, at the same solid content concentration, the lower the viscosity of the conductive material dispersion, the better the dispersibility of the conductive material such as carbon nanotubes in the conductive material dispersion.
A: Viscosity is less than 0.6 Pa·s B: Viscosity is 0.6 Pa·s or more and less than 2 Pa·s C: Viscosity is 2 Pa·s or more and less than 5 Pa·s D: Viscosity is 5 Pa·s or more

<Output characteristics>
The lithium ion secondary batteries produced in Examples and Comparative Examples were left standing at a temperature of 25° C. for 5 hours after injecting the electrolyte. Next, the battery was charged to a cell voltage of 3.65 V using a constant current method at a temperature of 25° C. and 0.2 C, and then an aging treatment was performed at a temperature of 60° C. for 12 hours. Then, the battery was discharged to a cell voltage of 3.00 V using a constant current method at a temperature of 25° C. and 0.2 C. Thereafter, CC-CV charging (upper limit cell voltage 4.20V) was performed at a constant current of 0.2C, and CC discharge was performed at a constant current of 0.2C to a cell voltage of 3.00V. This charging and discharging at 0.2C was repeated three times. The third discharge capacity at 0.2C was defined as the initial capacity CX. After that, CC-CV charging (upper limit cell voltage 4.20V) is performed at a constant current of 0.2C, and CC discharge is performed at a constant current of 3.0C until the cell voltage reaches 3.00V. was set as CY. The 3.0C/0.2C discharge capacity retention rate expressed as (CY/CX)×100(%) was determined and evaluated based on the following criteria. The larger the discharge capacity retention rate, the better the output characteristics of the lithium ion secondary battery.
A: 3.0C/0.2C discharge capacity retention rate is 80% or more B: 3.0C/0.2C discharge capacity retention rate is 75% or more and less than 80% C: 3.0C/0.2C discharge capacity retention rate is 70% or more and less than 75% D: 3.0C/0.2C discharge capacity retention rate is less than 70%

<Cycle characteristics>
The lithium ion secondary batteries produced in Examples and Comparative Examples were left standing at a temperature of 25° C. for 3 hours after injecting the electrolyte. Next, the battery was charged to a cell voltage of 3.65 V using a constant current method at a temperature of 25° C. and 0.2 C, and then an aging treatment was performed at a temperature of 60° C. for 12 hours. Then, the battery was discharged to a cell voltage of 3.00 V using a constant current method at a temperature of 25° C. and 0.2 C. Thereafter, CC-CV charging (upper limit cell voltage 4.20V) was performed using a constant current method at 0.2C, and CC discharge was performed to 3.00V using a constant current method at 0.2C. This charging and discharging at 0.2C was repeated three times.
Thereafter, charging and discharging operations were performed for 200 cycles at a cell voltage of 4.20-3.00V, a charge rate of 1.0C, and a discharge rate of 2.0C in an environment at a temperature of 45°C. At that time, the discharge capacity of the first cycle was defined as X1, and the discharge capacity of the 200th cycle was defined as X2. Using the discharge capacity X1 and the discharge capacity X2, the capacity retention rate represented by ΔC=(X2/X1)×100(%) was determined and evaluated according to the following criteria. The larger the value of this capacity retention rate ΔC, the better the cycle characteristics of the lithium ion secondary battery are.
A: Capacity retention rate is 90% or more B: Capacity retention rate is 85% or more and less than 90% C: Capacity retention rate is 80% or more and less than 85% D: Capacity retention rate is less than 80%

<Cracking of positive electrode active material after cycle test>
The lithium ion secondary batteries produced in Examples and Comparative Examples were disassembled after the cycle test, and the cross-sectional scanning electron microscope (SEM) images of the taken-out positive electrodes were observed at 1000x magnification. , was evaluated as follows.
The smaller the number of positive electrode active materials in which cracks were confirmed, the more suppressed is the cracking of the electrode active material in the electrode due to repeated charging and discharging.
A: The number of cracked positive electrode active materials is less than 2. B: The number of cracked positive electrode active materials is 2 or more and less than 5. C: The number of cracked positive electrode active materials is 5 or more and less than 9. D: The number of cracked positive electrode active materials is 9 or more.

<Transition metal content of negative electrode after cycle test>
The lithium ion secondary batteries produced in Examples and Comparative Examples were disassembled after the cycle test, and the transition metal content of the negative electrodes taken out was measured. Specifically, the lithium ion secondary battery after the cycle test was disassembled, the negative electrode was washed with diethyl carbonate (DEC), and the sample scraped off from the copper foil was weighed into a quartz beaker. After adding sulfuric acid thereto, it was carbonized on a heater and incinerated using a muffle furnace. After that, after cooling, nitric acid and hydrochloric acid were added to dissolve the sample, and the volume of the sample was measured by inductively coupled plasma emission spectrometry (ICP-AES). The total amount of (Mn) content was calculated, and this total amount was taken as the transition metal content of the negative electrode after the cycle test. According to the calculated transition metal content of the negative electrode, evaluation was made based on the following criteria.
The lower the transition metal content of the negative electrode, the more suppressed is the elution of metal ions from the positive electrode active material in the positive electrode due to repeated charging and discharging.
A: Transition metal content is less than 150 ppm B: Transition metal content is 150 ppm or more and less than 250 ppm C: Transition metal content is 250 ppm or more and less than 400 ppm D: Transition metal content is 400 ppm or more

(Example 1)
<Preparation of dispersant composition>
In a reactor, 200 parts of ion-exchanged water, 25 parts of a 10% concentration aqueous sodium dodecylbenzenesulfonate solution, 28 parts of acrylonitrile as a nitrile group-containing monomer unit, and 2.50 parts of t-dodecylmercaptan as a chain transfer agent were added. were prepared in order. Next, after replacing the internal gas with nitrogen three times, 60 parts of 1,3-butadiene as a conjugated diene monomer was charged. Then, the reactor was kept at 10°C, 0.03 part of cumene hydroperoxide as a polymerization initiator, a reducing agent, and an appropriate amount of a chelating agent were charged, and the polymerization reaction was continued with stirring until the polymerization conversion rate was 30%. At that point, 12 parts of methacrylic acid as a polar functional group-containing monomer was added, and the polymerization reaction was further continued. When the polymerization conversion rate reached 83%, 0.1 part of a 10% concentration hydroquinone aqueous solution as a polymerization terminator was added to terminate the polymerization reaction. Then, residual monomers were removed at a water temperature of 80° C. to obtain an aqueous dispersion of the precursor of polymer A.
The aqueous dispersion of the precursor of the polymer A and the palladium catalyst ( A solution of 1% palladium acetate in acetone and an equal weight of ion-exchanged water was added to perform a hydrogenation reaction at a hydrogen pressure of 3 MPa and a temperature of 55° C. for 3 hours to obtain an aqueous dispersion of polymer A. . Using the obtained aqueous dispersion of Polymer A, the iodine value of Polymer A was measured. The results are shown in Table 1.
Thereafter, the contents were returned to room temperature, the inside of the system was made into a nitrogen atmosphere, and then concentrated using an evaporator until the solid content concentration reached 40%.
Next, a 2.5% KOH aqueous solution was added to the concentrated aqueous dispersion of Polymer A to adjust the pH to 9.5.
Add 200 parts of N-methylpyrrolidone to 30 parts of the aqueous dispersion of polymer A after pH adjustment, evaporate all water and residual monomer under reduced pressure, and then evaporate the N-methylpyrrolidone to disperse. A 10% NMP solution of polymer A was obtained as agent composition A1. Using the obtained dispersant composition A1, the weight average molecular weight of the polymer A, the amount of Ni ion captured by the dispersant composition, and the amount of conductive material not adsorbed by the dispersant composition were measured and evaluated. The results are shown in Table 1.

<Preparation of conductive material dispersion>
4 parts of CNT1 (multi-walled CNT, BET specific surface area: 280 m ² /g) as a conductive material, 10 parts of dispersant composition A1 (NMP solution of polymer A) (equivalent to 1 part as solid content), 86 parts of NMP. was subjected to dispersion treatment using a disper at a rotational speed of 3000 rpm for 10 minutes while keeping the temperature below 25° C. (first dispersion step). Next, a conductive material dispersion was prepared by performing a dispersion process at a circumferential speed of 30 m/sec for 5 minutes using a thin film rotating high-speed mixer (Primix, product name "Filmix, Model 56-50"). second dispersion step). The viscosity of the obtained conductive material dispersion was measured and evaluated. The results are shown in Table 1.

<Preparation of slurry for positive electrode>
98.0 parts of a ternary active material (LiNi _0.6 Co _0.2 Mn _0.2 O ₂ ) (average particle size: 6 μm) as a positive electrode active material, and 1.0 part of polyvinylidene fluoride as a binder. , 1.0 part (solid content equivalent) of the conductive material dispersion obtained above, and NMP were added and mixed in a planetary mixer (60 rpm, 30 minutes) to prepare a positive electrode slurry. . The amount of NMP added is determined when the viscosity of the resulting positive electrode slurry (measured using a single cylindrical rotational viscometer according to JIS Z8803:1991, temperature: 25°C, rotation speed: 60 rpm) is 6000 to 8000 mPa・s. Adjusted to be within range.

<Preparation of positive electrode>
Aluminum foil with a thickness of 20 μm was prepared as a current collector. The positive electrode slurry obtained as described above was coated on one side of aluminum foil using a comma coater so that the drying weight was 20 mg/cm ² . Thereafter, the aluminum foil coated with the positive electrode slurry was transported at a speed of 300 mm/min in an oven at a temperature of 110°C for 3 minutes, and then in an oven at a temperature of 120°C for 3 minutes. The positive electrode slurry was dried to obtain a positive electrode material in which a positive electrode composite layer was formed on a current collector. This positive electrode original fabric was rolled with a roll press to produce a sheet-like positive electrode consisting of a positive electrode composite material layer having a density of 3.3 g/cm ³ and aluminum foil. Then, the sheet-like positive electrode was cut into pieces with a width of 48.0 mm and a length of 47 cm to obtain a positive electrode for a lithium ion secondary battery.

<Preparation of negative electrode>
In a 5 MPa pressure vessel equipped with a stirrer, 33 parts of 1,3-butadiene as a conjugated diene monomer, 3.5 parts of itaconic acid as a carboxylic acid group-containing monomer, and 63 parts of styrene as an aromatic vinyl monomer were placed. 5 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of ion-exchanged water, and 0.5 parts of potassium persulfate as a polymerization initiator, stirred thoroughly, and then heated to 50°C. Polymerization was started. When the polymerization conversion rate reached 96%, the polymerization reaction was stopped by cooling to obtain a mixture containing a particulate binder (styrene-butadiene copolymer). After adjusting the pH to 8 by adding a 5% aqueous sodium hydroxide solution to the above mixture, unreacted monomers were removed by heating and vacuum distillation. Thereafter, the mixture was cooled to 30° C. or lower to obtain an aqueous dispersion containing a negative electrode binder.
48.75 parts of artificial graphite and 48.75 parts of natural graphite as negative electrode active materials, and 1 part of carboxymethyl cellulose (equivalent to solid content) as a thickener were charged into a planetary mixer. Further, the mixture was diluted with ion-exchanged water to a solid concentration of 60%, and then kneaded for 60 minutes at a rotational speed of 45 rpm. Thereafter, 1.5 parts of the aqueous dispersion containing the negative electrode binder obtained as described above was added in terms of solid content, and kneaded at a rotational speed of 40 rpm for 40 minutes. Then, ion-exchanged water was added so that the viscosity was 5000±500 mPa·s (measured using a B-type viscometer, 25° C., 60 rpm) to prepare a negative electrode slurry.
The above slurry for negative electrode was applied to the surface of a 15 μm thick copper foil serving as a current collector using a comma coater so that the coating amount was 12.0±0.5 mg/cm ² . Thereafter, the copper foil coated with the negative electrode slurry was transported at a speed of 400 mm/min in an oven at a temperature of 80°C for 2 minutes, and then in an oven at a temperature of 110°C for 2 minutes. The negative electrode slurry was dried to obtain a negative electrode original fabric in which a negative electrode composite layer was formed on a current collector.
This negative electrode original fabric was rolled with a roll press to produce a sheet-like negative electrode consisting of a negative electrode composite material layer having a density of 1.6 g/cm ³ and aluminum foil. Then, the sheet-shaped negative electrode was cut into pieces with a width of 50.0 mm and a length of 52 cm to obtain a negative electrode for a lithium ion secondary battery.

<Production of lithium ion secondary battery>
The positive electrode for a lithium ion secondary battery and the negative electrode for a lithium ion secondary battery are arranged so that their electrode mixture layers face each other, and a separator (microporous membrane made of polyethylene) with a thickness of 15 μm is interposed. It was wound using a 20 mm core to obtain a wound body. Then, the obtained wound body was compressed from one direction at a speed of 10 mm/sec until it had a thickness of 4.5 mm. The wound body after compression had an elliptical shape in plan view, and the ratio of the major axis to the minor axis (major axis/minor axis) was 7.7.
In addition, as an electrolyte, LiPF ₆ solution with a concentration of 1.0 M (solvent: mixed solvent of ethylene carbonate (EC)/diethyl carbonate (DEC) = 3/7 (volume ratio), additive: vinylene carbonate 2% by volume (solvent ratio) ) was prepared.
Thereafter, the compressed wound body was housed in an aluminum laminate case together with 3.2 g of electrolyte. After connecting a nickel lead wire to a predetermined location of the negative electrode for a lithium ion secondary battery, the opening of the case was sealed with heat to obtain a lithium ion secondary battery as an electrochemical element. This lithium ion secondary battery was in the form of a pouch with a width of 35 mm, a height of 60 mm, and a thickness of 5 mm, and the nominal capacity of the battery was 700 mAh.
Using the obtained lithium ion secondary battery, output characteristics, cycle characteristics, cracking of the positive electrode active material after the cycle test, and transition metal content of the negative electrode after the cycle test were measured and evaluated. The results are shown in Table 1.

(Example 2)
When preparing a dispersant composition, 12 parts of diethylaminoethyl methacrylate was used in place of 12 parts of methacrylic acid as the polar functional group-containing monomer to obtain a dispersant composition A2. Then, when preparing a conductive material dispersion liquid, dispersant composition A2 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 3)
When preparing a dispersant composition, 12 parts of hydroxyethyl methacrylate was used in place of 12 parts of methacrylic acid as the polar functional group-containing monomer to obtain a dispersant composition A3. Then, when preparing a conductive material dispersion liquid, dispersant composition A3 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 4)
When preparing a dispersant composition, the amount of methacrylic acid as a polar functional group-containing monomer was changed from 12 parts to 18 parts to obtain a dispersant composition A4. Then, when preparing a conductive material dispersion liquid, dispersant composition A4 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 5)
When preparing the dispersant composition, the amount of acrylonitrile as a nitrile group-containing monomer was changed from 28 parts to 37 parts, and the amount of 1,3-butadiene as a conjugated diene monomer was changed from 60 parts to 51 parts. part, to obtain a dispersant composition A5. Then, when preparing a conductive material dispersion liquid, dispersant composition A5 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 6)
When preparing the dispersant composition, the amount of acrylonitrile as a nitrile group-containing monomer was changed from 28 parts to 22 parts, and the amount of 1,3-butadiene as a conjugated diene monomer was changed from 60 parts to 66 parts. Part was changed to obtain a dispersant composition A6. Then, when preparing a conductive material dispersion liquid, dispersant composition A6 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 7)
In preparing the dispersant composition, an additional 10 parts of styrene as an aromatic vinyl-containing monomer was added to the reactor, and 1,3-butadiene as a conjugated diene monomer was increased from 60 parts to 50 parts. Dispersant composition 7 was obtained by changing the procedure. Then, when preparing a conductive material dispersion liquid, dispersant composition A7 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 1.

(Example 8)
When preparing a dispersant composition, the amount of palladium catalyst added is changed so that the palladium content is 1500 ppm with respect to the solid content contained in the aqueous dispersion of the precursor of polymer A. I got item 8. Then, when preparing a conductive material dispersion liquid, dispersant composition A8 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 2. The results are shown in Table 2.

(Example 9)
When preparing the conductive material dispersion liquid, the amount of dispersant composition A1 was changed from 10 parts (corresponding to 1 part as solid content) to 20 parts (corresponding to 2 parts as solid content), and the amount of NMP was changed from 86 parts to 20 parts (corresponding to 2 parts as solid content). Changed to 76 copies. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

(Example 10)
When preparing the conductive material dispersion liquid, the amount of dispersant composition A1 was changed from 10 parts (equivalent to 1 part as solid content) to 5 parts (equivalent to 0.5 part as solid content), and the amount of NMP was changed to 86 parts. The number was changed from 91 to 91. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

(Example 11)
When preparing the conductive material dispersion liquid, the amount of CNT1 as a conductive material was changed from 4 parts to 8 parts, and the amount of dispersant composition A1 was changed from 10 parts (equivalent to 1 part as solid content) to 20 parts (solid content). (equivalent to 2 parts), and the amount of NMP was changed from 86 parts to 72 parts. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

(Example 12)
When preparing the conductive material dispersion liquid, the amount of CNT1 as a conductive material was changed from 4 parts to 2 parts, and the amount of dispersant composition A1 was changed from 10 parts (equivalent to 1 part as solid content) to 20 parts (solid content). (equivalent to 2 parts), and the amount of NMP was changed from 86 parts to 78 parts. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

(Example 13)
When preparing a conductive material dispersion liquid, 1 part of CNT2 (single-walled CNT, BET specific surface area: 800 m ² /g) was used as a conductive material in place of 4 parts of CNT1, and the dispersant composition A1 was The amount was changed from 10 parts (equivalent to 1 part as solid content) to 20 parts (equivalent to 2 parts as solid content), and the amount of NMP was changed from 86 parts to 79 parts. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

(Example 14)
When preparing a conductive material dispersion, 1 part of CNT2 is used as a conductive material instead of 4 parts of CNT1, and the amount of dispersant composition A1 is changed from 10 parts (corresponding to 1 part as solid content) to 1 part of CNT2. The amount of NMP was changed from 86 parts to 69 parts. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

(Example 15)
When preparing a dispersant composition, the amount of t-dodecyl mercaptan as a chain transfer agent was changed from 2.50 parts to 1.00 parts to obtain a dispersant composition A9. Then, when preparing a conductive material dispersion liquid, dispersant composition A9 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 2.

(Comparative example 1)
When preparing a conductive material dispersion, 10 parts of a 10% NMP solution of polyvinylpyrrolidone (manufactured by Fuji Film Wako Pure Chemical Industries, Ltd., PVP K30) was added in place of 10 parts of dispersant composition A1 (equivalent to 1 part as solid content). (equivalent to 1 part as solid content) was used. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

(Comparative example 2)
When preparing the dispersant composition, the amount of acrylonitrile as a nitrile group-containing monomer was changed from 28 parts to 38 parts, and the amount of methacrylic acid as a polar functional group-containing monomer was changed from 12 parts to 2 parts. Dispersant composition A10 was obtained. Then, when preparing a conductive material dispersion liquid, dispersant composition A10 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

(Comparative example 3)
When preparing the dispersant composition, the amount of acrylonitrile as a nitrile group-containing monomer was changed from 28 parts to 21 parts, and the amount of 1,3-butadiene as a conjugated diene monomer was changed from 60 parts to 54 parts. The amount of methacrylic acid as a polar functional group-containing monomer was changed from 12 parts to 25 parts to obtain a dispersant composition A11. Then, when preparing a conductive material dispersion liquid, dispersant composition A11 was used in place of dispersant composition A1. Other than that, a dispersant composition, a conductive material dispersion, a positive electrode slurry, a positive electrode, a negative electrode, and a lithium ion secondary battery were produced in the same manner as in Example 1. Then, various measurements and evaluations were performed in the same manner as in Example 1. The results are shown in Table 3.

In Tables 1 to 3,
"MAA" indicates methacrylic acid,
"DEAEMA" refers to diethylaminoethyl methacrylate,
“HEMA” stands for hydroxyethyl methacrylate;
"PVP" indicates polyvinylpyrrolidone.

Tables 1 to 3 show that the dispersant composition contains a conductive material, a dispersant composition, and a solvent, and that the dispersant composition contains a linear alkylene structural unit having 4 or more carbon atoms, a nitrile group-containing monomer unit, and a polar The conductive material dispersion liquids of Examples 1 to 15 include a polymer A containing a functional group-containing monomer unit, and the amount of Ni ion trapped in the dispersant composition is 10 mg or more and 800 mg or less per 1 g of the dispersant composition. It can be seen that the dispersibility of the conductive material is excellent. In addition, by using the above conductive material dispersion, it is possible to produce an electrode in which cracking and deterioration of the electrode active material due to repeated charging and discharging are suppressed, and the electrode has excellent performance in lithium ion secondary batteries. It can be seen that the output characteristics, cycle characteristics, and life characteristics can be exhibited.

According to the present invention, it is possible to suppress cracking and deterioration of the electrode active material in the electrode due to repeated charging and discharging, and it is possible to make the electrochemical device exhibit excellent output characteristics, cycle characteristics, and life characteristics. A conductive material dispersion liquid for electrochemical devices and a slurry for electrochemical device electrodes can be provided.
Furthermore, according to the present invention, cracking and deterioration of the electrode active material in the electrode due to repeated charging and discharging is suppressed, and the electrochemical device can exhibit excellent output characteristics, cycle characteristics, and life characteristics. It is possible to provide a possible electrode for an electrochemical device.
Furthermore, according to the present invention, it is possible to provide an electrochemical element with excellent output characteristics, cycle characteristics, and life characteristics.

Claims (10)

A conductive material dispersion liquid for an electrochemical element, comprising a conductive material, a dispersant composition, and a solvent,
The dispersant composition contains a polymer A containing a linear alkylene structural unit having 4 or more carbon atoms, a nitrile group-containing monomer unit, and a polar functional group-containing monomer unit, and
An electrochemical element, wherein when a film made of the dispersant composition is immersed in a Ni ion-containing propylene carbonate solution, the amount of Ni ions captured by the dispersant composition is 10 mg or more and 800 mg or less per 1 g of the dispersant composition. Conductive material dispersion liquid for use. The conductive material dispersion liquid for an electrochemical device according to claim 1, wherein the amount of the dispersant composition not adsorbed onto the conductive material is 15 mg or more and 1500 mg or less per 1 g of the conductive material. The conductive material dispersion liquid for an electrochemical element according to claim 1, wherein the iodine value of the polymer A is 1 mg/100 mg or more and 60 mg/100 mg or less. The conductive material dispersion liquid for an electrochemical device according to claim 1, wherein the weight average molecular weight of the polymer A is 5,000 or more and 150,000 or less. The conductive material dispersion for an electrochemical element according to claim 1, wherein the conductive material includes at least carbon nanotubes. The content of the conductive material is 0.05% by mass or more and 10% by mass or less based on the entire conductive material dispersion for electrochemical devices, and the content of the dispersant composition is The conductive material dispersion for an electrochemical device according to claim 1, wherein the content is 0.02% by mass or more and 8% by mass or less based on the entire material dispersion. The conductive material dispersion for electrochemical devices according to claim 1, wherein the solid content concentration is 0.1% by mass or more and 15% by mass or less. A slurry for an electrode of an electrochemical device, comprising at least the dispersion of a conductive material for an electrochemical device according to any one of claims 1 to 7 and an electrode active material. An electrode for an electrochemical device, comprising an electrode mixture layer formed using the slurry for an electrochemical device electrode according to claim 8. An electrochemical device comprising the electrode for an electrochemical device according to claim 9.