Conductive material slurry

Abstract

To provide a conductive material slurry containing a single layer carbon nanotube, having good dispersibility and handling property of the carbon nanotube (CNT), and capable of producing a coating film having high conductivity.SOLUTION: The conductive material slurry contains CNT, a maleic acid monoamide resin, and an organic solvent. A G / D ratio in a Raman spectrum of the CNTs is at least 20 and less than 80. The maleic acid monoamide resin contains at least one of structural units represented by general formula (1) and general formula (2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a conductive material slurry, a positive electrode paste for an electricity storage device containing the same, and the like. [Background technology]

[0002] In recent years, there has been active development of electric vehicles that do not emit carbon dioxide, with a view to curbing global warming. Electric vehicles have the drawback of having a shorter driving range and longer battery charging times than gasoline-powered vehicles. To shorten charging times, it is necessary to increase the electron transfer rate in the positive electrode. Currently, carbon materials are used as conductive materials in the positive electrodes of non-aqueous electrolyte batteries, but there has been a shift from conventional carbon black to multi-walled carbon nanotubes (MWCNTs), which can achieve equivalent conductivity with lower amounts of carbon black. MWCNTs have the advantage of being loosely aggregated and easily dispersible due to their large diameter and low crystallinity. However, although the conductivity of MWCNTs is higher than that of carbon black, it is still not sufficient.

[0003] Patent Document 1 below discloses a polymer composition containing double-walled carbon nanotubes (DWCNTs) with an average outer diameter of 4 nm or less, a specific polymer, and a polar organic solvent. In this polymer composition, the polymer functions not only as one component (matrix resin) in the composition but also as a dispersant. This makes it possible to obtain a polymer molded product in which double-walled carbon nanotubes (CNTs) are dispersed without impairing the properties of the carbon nanotubes. The following Patent Document 2 discloses a dispersant that can prepare a slurry in which multi-walled carbon nanotubes are well dispersed. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2010-132863 [Patent Document 2] Patent Publication No. 2023-097438 Summary of the Invention [Problem to be solved by the invention]

[0005] Single-walled carbon nanotubes (SWCNTs) are being considered as a conductive material for the positive electrodes of non-aqueous electrolyte batteries because they have higher conductivity than MWCNTs. However, although SWCNTs are highly conductive, their specific surface area is larger than that of MWCNTs, which increases the viscosity of conductive material slurry and positive electrode paste, making them difficult to handle.

[0006] Furthermore, to prepare conductive slurries or positive electrode pastes containing SWCNTs, it is necessary to disintegrate the SWCNT bundles through a dispersion process using mechanical force in the presence of a dispersant that can highly disperse the SWCNTs. However, there is a problem in that the performance of electrodes fabricated using conductive slurries prepared through such a process (e.g., coating resistance value, direct current resistance (DCR)) is unstable and varies.

[0007] Therefore, in one aspect, the present disclosure provides a conductive material slurry that contains SWCNTs, has good CNT dispersibility and handleability, and enables the production of a highly conductive coating film. [Means for solving the problem]

[0008] In one aspect, the present disclosure provides a method for producing a dispersion medium comprising: carbon nanotubes; a dispersant; and an organic solvent; The G / D ratio in the Raman spectrum of the carbon nanotube is 20 or more and less than 80, The dispersant is A maleic acid monoamide resin containing at least one of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), or The present invention relates to a conductive material slurry, which is a resin containing any one of a constitutional unit represented by the following general formula (3), a constitutional unit represented by the following general formula (4), and a constitutional unit represented by the following general formula (5). [ka] However, in the above general formula (1), R 1 is a hydrocarbon group having 12 to 30 carbon atoms which may have a hydrogen atom or a hydroxyl group, and R 2 is a hydrocarbon group having 1 to 8 carbon atoms which may have a hydrogen atom or a hydroxyl group, and M 1 is a hydrogen atom, NH4, a metal, or an organic ammonium. In the above general formula (2), R 3 is a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms which may have a hydroxyl group, or a polyalkylene oxide group, and R 4 is a hydrocarbon group having 1 to 8 carbon atoms which may have a hydrogen atom or a hydroxyl group, and M 1 is a hydrogen atom, NH4, a metal, or an organic ammonium. [ka] In the above general formula (3), R 5 , R 6 , R 7 are the same or different and each represents a hydrogen atom or a methyl group. [ka] [ka] In the above general formula (5), R 8 , R 9 , R 10 , R 11 , R 12 , R 13 are the same or different and are a hydrogen atom or a methyl group, and the degree of substitution of methyl groups is 0.1 to less than 2.9 per glucose ring.

[0009] In one aspect, the present disclosure relates to a positive electrode paste for an electricity storage device, which includes the conductive material slurry of the present disclosure, a positive electrode active material, and a binder resin.

[0010] In one aspect, the present disclosure relates to a method for producing a positive electrode for an electricity storage device, the method comprising applying the positive electrode paste for an electricity storage device of the present disclosure to a current collector and drying the applied paste.

[0011] In one aspect, the present disclosure relates to a method for producing an electricity storage device, which includes incorporating a positive electrode for an electricity storage device obtained by the method for producing a positive electrode for an electricity storage device of the present disclosure.

[0012] In one aspect, the present disclosure relates to the use of the conductive material slurry of the present disclosure for producing a positive electrode for an electricity storage device. [Effects of the Invention]

[0013] According to one aspect of the present disclosure, it is possible to provide a conductive material slurry that contains SWCNTs, has good CNT dispersibility and handleability, and can be used to prepare a positive electrode paste for an electricity storage device that can produce a highly conductive coating film. According to one aspect of the present disclosure, the conductive material slurry of the present disclosure is used to produce a positive electrode paste for an electricity storage device, thereby providing a positive electrode paste for an electricity storage device that enables the production of a coating film with high conductivity. According to one aspect of the present disclosure, a positive electrode for an electricity storage device is produced using the electricity storage device positive electrode paste of the present disclosure, thereby enabling the production of a highly conductive positive electrode for an electricity storage device. According to one aspect of the present disclosure, a positive electrode for an electricity storage device is produced using the electricity storage device positive electrode of the present disclosure, thereby enabling the production of a highly conductive electricity storage device. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present disclosure is based on the new finding that a combination of specific crystalline carbon nanotubes and a specific dispersant can provide a conductive material slurry that can be used to prepare a positive electrode paste for an electricity storage device that has good dispersibility of the carbon nanotubes and enables the stable production of a highly conductive coating film.

[0015] In one aspect, the present disclosure provides a conductive material slurry containing specific carbon nanotubes, a specific dispersant, and an organic solvent, which can be used, for example, to prepare a positive electrode paste for an electricity storage device.

[0016] <Carbon nanotubes> The conductive material slurry of the present disclosure contains carbon nanotubes as a conductive material. The carbon nanotubes have a G / D ratio in the Raman spectrum of 20 or more and less than 80. The G / D ratio is determined by the G band (1600 cm ) observed in the Raman spectrum of CNTs measured by a Raman spectrometer. -1 around 1350 cm -1 The G / D ratio is the peak intensity ratio of the G band and the D band (near the G band) and is a commonly used index for evaluating the crystallinity, purity, and defect concentration of CNTs. The G band is a vibration mode derived from the hexagonal lattice structure of graphite, which is the cylindrical surface of CNTs, and the D band is a vibration mode derived from amorphous regions. Therefore, the higher the G / D ratio, the more crystalline the CNT is. Generally, the fewer the number of layers, the higher the crystallinity. The higher the ratio of single-walled carbon tubes (SWCNTs) to double-walled carbon nanotubes (DWCNTs), the more crystalline the CNT is. From the viewpoint of improving the conductivity of the coating film, the G / D ratio is preferably 30 or more, more preferably 40 or more, and even more preferably 45 or more. From the viewpoint of improving the dispersibility and handleability of CNTs, the ratio is preferably 70 or less, more preferably 60 or less, and even more preferably 55 or less.

[0017] The carbon nanotubes (CNTs) contained in the conductive material slurry of the present disclosure are preferably composed primarily of single-walled carbon nanotubes (SWCNTs) and double-walled carbon nanotubes (DWCNTs). The proportion of SWCNTs among the CNTs contained in the conductive material slurry of the present disclosure is preferably 40% or more, more preferably 50% or more, and even more preferably 60% or more, from the viewpoint of improving the conductivity of the coating film. The proportion of DWCNTs among the CNTs contained in the conductive material slurry of the present disclosure is preferably 15% or more, more preferably 20% or more, and even more preferably 25% or more, from the viewpoint of improving the dispersibility and handleability of the CNTs. The proportion of DWCNTs among the CNTs contained in the conductive material slurry of the present disclosure is preferably 60% or less, more preferably 50% or less, and even more preferably 40% or less, from the viewpoint of improving the conductivity of the coating film. In the present disclosure, the proportion of SWCNTs and the proportion of DWCNTs are values ​​determined by the methods described in the Examples. The carbon nanotubes (CNTs) contained in the conductive material slurry of the present disclosure may include multi-walled carbon nanotubes (MWCNTs) with three or more walls, but in this case, from the viewpoint of electrical conductivity, the total ratio of SWCNTs and DWCNTs is preferably 50% or more, more preferably 70% or more, even more preferably 80% or more, and even more preferably 90% or more of the carbon nanotubes (CNTs) contained in the conductive material slurry of the present disclosure.

[0018] The outer diameter of the CNT is preferably 1.0 nm or more, more preferably 2.0 nm or more, from the viewpoint of improving the dispersibility of the CNT, and is preferably less than 6.0 nm, more preferably 4.0 nm or less, from the viewpoint of improving the conductivity.

[0019] The particle size (D50) of the CNTs contained in the conductive material slurry of the present disclosure, as measured by dynamic light scattering (DLS), is preferably 200 nm or more, more preferably 300 nm or more, and even more preferably 400 nm or more, from the viewpoint of improving conductivity, and is preferably 1500 nm or less, more preferably 1200 nm or less, and even more preferably 1000 nm or less, from the viewpoint of improving dispersibility of the CNTs.

[0020] CNTs may contain impurities (e.g., catalysts and amorphous carbon) derived from the CNT manufacturing process. The impurity content in CNTs is measured by methods such as thermogravimetric analysis, and in the present disclosure, the lower the impurity content, the better. From the viewpoint of achieving a high concentration of useful CNT content, the impurity content in CNTs is preferably 40% by mass or less, more preferably 30% by mass or less, even more preferably 20% by mass or less, even more preferably 10% by mass or less, and even more preferably substantially 0% by mass.

[0021] <Dispersant> The conductive material slurry of the present disclosure contains a specific dispersant, which is a maleic acid monoamide resin containing at least one of a constitutional unit represented by the following general formula (1) and a constitutional unit represented by the following general formula (2), or a resin containing a constitutional unit represented by the following general formula (3), a constitutional unit represented by the following general formula (4), or a constitutional unit represented by the following general formula (5) (hereinafter, these may be collectively referred to as the "dispersant of the present disclosure").

[0022] (Dispersant I) In one embodiment, the conductive material slurry of the present disclosure contains a maleic acid monoamide resin (hereinafter also referred to as "Dispersant I") as a dispersant of the present disclosure. Dispersant I is, for example, an amide-modified copolymer of an olefin and maleic anhydride and / or one obtained by neutralizing the amide-modified copolymer as necessary. From the viewpoint of improving the dispersibility and handleability of CNTs and improving the conductivity of the coating film, Dispersant I contains at least one of a structural unit represented by the following general formula (1) (hereinafter also referred to as "structural unit B1") and a structural unit represented by the following general formula (2) (hereinafter also referred to as "structural unit B2"), preferably containing structural unit B2, and more preferably containing both structural unit B1 and structural unit B2. [ka]

[0023] In the above general formula (1), R 1 R is a hydrocarbon group having 12 to 30 carbon atoms which may have a hydrogen atom or a hydroxyl group, and from the viewpoint of the adsorption of the dispersant to CNTs, it is preferably a hydrocarbon group having 12 to 30 carbon atoms which may have a hydroxyl group, and more preferably an alkyl group having 12 to 30 carbon atoms. 1 From the same viewpoint, the number of carbon atoms is preferably 16 or more, more preferably 18 or more, and from the same viewpoint, preferably 25 or less, more preferably 22 or less, and even more preferably 20 or less.

[0024] In the above general formula (1), R 2 is a hydrocarbon group having 1 to 8 carbon atoms which may have a hydrogen atom or a hydroxyl group, and is preferably a hydrogen atom from the viewpoint of availability and ease of synthesis of the dispersant.

[0025] In the above general formula (2), R 3 is a hydrogen atom, a hydrocarbon group having 1 to 8 carbon atoms which may have a hydroxyl group, or a polyalkylene oxide group, and R 4 is a hydrocarbon group having 1 to 8 carbon atoms which may have a hydrogen atom or a hydroxyl group. The polyalkylene oxide group is obtained by adding at least one alkylene oxide selected from ethylene oxide and propylene oxide to an alcohol. The number of carbon atoms in the alcohol is preferably 1 to 8 in terms of solubility. The number of moles of ethylene oxide added is preferably 10 or more, more preferably 15 or more, and even more preferably 20 or more in terms of the solubility of Dispersant I, and is preferably 50 or less, more preferably 40 or less in terms of the melting point. The number of moles of propylene oxide added is preferably 3 or more, more preferably 5 or more in terms of the fluidity of Dispersant I, and is preferably 20 or less, more preferably 15 or less in terms of the solubility of Dispersant I.

[0026] When dispersant I contains both structural units B1 and B2, the long-chain alkyl group R 1 From the viewpoint of suppressing the formation of association structures due to hydrophobic interactions between R 3 and R 4 is preferably a hydrocarbon group having 1 to 8 carbon atoms which may have a hydroxyl group. 3 and R 4 The tertiary amide structure in which both R and R are hydrocarbon groups is bulky, and therefore the formation of the association structure is suppressed, and as a result, the solubility of the dispersant in organic solvents at room temperature is increased, which is preferable. 3 and R 4 The number of carbon atoms in each of R is preferably 2 or more from the viewpoint of suppressing the formation of the association structure, and is preferably 7 or less, more preferably 6 or less, and even more preferably 5 or less from the viewpoint of availability and ease of synthesis of the dispersant. 3 and R 4 The total number of carbon atoms in R is preferably 4 or more from the viewpoint of inhibiting the formation of the association structure, and from the viewpoint of availability and ease of synthesis of the dispersant, is preferably 14 or less, more preferably 12 or less, and even more preferably 10 or less. 1is preferably an alkyl group having 12 to 30 carbon atoms, more preferably an alkyl group having 14 to 26 carbon atoms, and even more preferably an alkyl group having 16 to 22 carbon atoms, from the viewpoint of the adsorption of the dispersant to CNTs; R 2 From the viewpoint of availability and ease of synthesis of the dispersant, is preferably a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

[0027] When dispersant I contains structural unit B2 but not structural unit B1, R 3 and R 4 From the viewpoint of dispersibility, either one of R is preferably a hydrocarbon group having 1 to 8 carbon atoms which may have a hydroxyl group, more preferably a hydrocarbon group having 1 to 8 carbon atoms, and even more preferably an alkyl group having 1 to 8 carbon atoms. The preferred number of carbon atoms in the hydrocarbon group having 1 to 8 carbon atoms which may have a hydroxyl group is preferably 2 or more, more preferably 4 or more, from the viewpoint of solubility, and preferably 10 or less, more preferably 8 or less, from the viewpoint of dispersibility. 3 and R 4 From the viewpoints of availability and ease of synthesis of the dispersant, the other of these is preferably a hydrogen atom.

[0028] When dispersant I contains structural unit B1 but does not contain structural unit B2, R 1 is preferably an alkyl group having 12 to 30 carbon atoms, more preferably an alkyl group having 14 to 26 carbon atoms, and even more preferably an alkyl group having 16 to 22 carbon atoms, from the viewpoint of the adsorption of the dispersant to CNTs; R 2 From the viewpoint of availability and ease of synthesis of the dispersant, is preferably a hydrogen atom or a hydrocarbon group having 1 to 4 carbon atoms, and more preferably a hydrogen atom.

[0029] In the above general formula (1) and general formula (2), M 1is a hydrogen atom, NH4, a metal, or an organic ammonium. From the viewpoint of dispersibility of the dispersant in an organic solvent, M1 is, for example, a hydrogen atom when the carboxy group is not neutralized, and when some or all of the carboxy groups are neutralized, it is preferably NH4, a metal that gives a salt soluble in an organic solvent, or an organic ammonium derived from an organic amine that is soluble in an organic solvent. When some or all of the carboxy groups are neutralized, M 1 is preferably an organic ammonium, and the metal is preferably Na, K, Li, etc. Neutralizing agents that give these structures include ammonia, organic amine B1, or alkali metal hydroxides such as sodium hydroxide, potassium hydroxide, and lithium hydroxide.

[0030] Specific examples of the organic amine B1 are not particularly limited as long as they function as a neutralizing agent. For example, methylamine (SP value (solubility parameter) 8.85 (cal / cm 3 ) 1 / 2 , boiling point -6.3℃, same below.), dimethylamine (7.80, 7℃), ethylamine (7.93, 16.6℃), dimethylbenzylamine (9.1, 180℃), methylbenzylamine (9.8, 186℃), 2-N-dibutylaminoethanol (10.0, 226℃), 1-phenylmethanamine (10.5, 184℃), N,N-diethylaminoethanol (10.7, 162℃), 2-aminoethanol (14.3, 170℃), 2-dimethylaminoethanol (11.3, 134℃), 1 Examples of amine compounds include N-amino-2-butanol (same as above, 11.9°C, 169°C), 2-(ethylamino)ethanol (same as above, 12.0°C, 169°C), 2-amino-2-methyl-1-propanol (same as above, 12.2°C, 185°C), DL-1-amino-2-propanol (same as above, 12.4°C, 160°C), N-methyl-2-aminoethanol (same as above, 12.5°C, 175°C), 1-(2-hydroxyethyl)piperazine (same as above, 12.98°C, 246°C), and N-ethyldiethanolamine (same as above, 251°C).

[0031] The SP value is defined in the theoretical development of regular solutions and is used as an index showing the solubility of a compound. The SP value in the present disclosure is calculated in accordance with the Fedors calculation method, which is one of the methods for estimating from molecular structure, and is determined in detail based on the method described in "A Method for Estimating Both the Solubility Parameters and Molar Volumes of Liquids" in POLYMER ENGINEERING AND SCIENCE, FEBRUARY, 1974, vol. 14, No. 2.

[0032] Dispersant I is, for example, an amide-modified copolymer of an olefin and maleic anhydride and / or is obtained by neutralizing the amide-modified copolymer as needed, and further comprises a structural unit B6 derived from an olefin and represented by the following general formula (6). Structural unit B6 is a component responsible for the solubility of the dispersant in organic solvents. When amidation is performed on a portion of the maleic anhydride, Dispersant I further comprises a structural unit B7 derived from maleic anhydride and represented by the following general formula (7). However, from the viewpoints of improving the dispersibility and handleability of CNTs and improving the conductivity of the coating film, it is preferable that Dispersant I does not comprise structural unit B7. [ka]

[0033] In the above general formula (6), R 14 is a hydrogen atom or a methyl group, and is preferably a methyl group from the viewpoint of solubility in organic solvents.

[0034] In the above general formula (6), R 15From the viewpoint of the solubility of Dispersant I in organic solvents, is a hydrogen atom, an alkyl group having from 1 to 10 carbon atoms, an alkoxy group having from 1 to 20 carbon atoms, or an aromatic hydrocarbon group having or having no substituents containing from 1 to 10 carbon atoms, preferably an alkyl group having from 1 to 10 carbon atoms, or an aromatic hydrocarbon group having or having no substituents containing from 1 to 10 carbon atoms, more preferably an alkyl group having from 1 to 10 carbon atoms, or a naphthyl group or phenyl group having or having no substituents containing from 1 to 10 carbon atoms, and even more preferably an alkyl group having from 1 to 10 carbon atoms. The alkyl group may be either linear or branched. The substituent having from 1 to 10 carbon atoms is preferably a 2,2-dimethylpropyl group or a phenyl group.

[0035] R 15 The number of carbon atoms is 1 or more, preferably 2 or more, from the viewpoints of the adsorption of Dispersant I to CNTs, ease of synthesis of Dispersant I, and ease of availability of the monomer, and from the same viewpoints, is 10 or less, preferably 7 or less.

[0036] R 14 and R 15 The total number of carbon atoms is 2 or more and 11 or less, but from the viewpoint of the solubility of the dispersant in organic solvents, it is preferably 10 or less, more preferably 8 or less, even more preferably 7 or less, and still more preferably 6 or less.

[0037] If the molar fractions of structural unit B1, structural unit B2, structural unit B6, and structural unit B7 are a, b, c, and d, respectively, then a+b+c+d=1, and when a+b+c=1, this means that the amidation rate relative to maleic anhydride is 100 mol%. From the viewpoint of improving the adsorption of dispersant I to CNTs, the relationship a>b is preferably satisfied. From the same viewpoint, the molar fraction a of structural unit B1 is preferably 0.30 to 0.50, more preferably 0.35 to 0.40, and the molar fraction b of structural unit B2 is preferably 0.00 to 0.20, more preferably 0.10 to 0.15.

[0038] From the viewpoint of adsorption to CNTs, the weight-average molecular weight of Dispersant I is preferably 3,000 or more, more preferably 5,000 or more, and even more preferably 10,000 or more. From the viewpoints of solubility in organic solvents, CNT dispersibility, and low viscosity of the slurry, the weight-average molecular weight is preferably 250,000 or less, more preferably 200,000 or less, and even more preferably 150,000 or less. The weight-average molecular weight of Dispersant I is a value measured by GPC (gel permeation chromatography), and the detailed measurement conditions are as shown in the "Measurement of weight-average molecular weight" section of the Examples.

[0039] The monomer that provides the structural unit B6 represented by general formula (6) above (hereinafter also referred to as "monomer I") is preferably at least one selected from the group consisting of α-olefins having 2 to 25 carbon atoms, from the viewpoint of good solubility in organic solvents, such as diisobutylene, isobutylene, 1-pentene, 1-heptene, 1-butene, 1-oxene, 1-decene, styrene, α-methylstyrene, stearyl vinyl ether, etc. Among these, from the viewpoint of good solubility in organic solvents, at least one of diisobutylene (2,4,4-trimethylpentene-1) and isobutylene is preferred, with diisobutylene (2,4,4-trimethylpentene-1) being more preferred.

[0040] The monomer (hereinafter also referred to as "monomer II") that gives the structural unit B1 represented by the general formula (1) and the structural unit B2 represented by the general formula (2) can be easily selected from the group consisting of a monomer having an alkyl group R 1 , R 2 , R 3 , R 4 Since maleic anhydride having a structure with reactivity such as an acid anhydride can be introduced, maleic anhydride is preferred.

[0041] Dispersant I can be produced by, for example, a method used for polymerizing vinyl monomers. For example, Monomer I and Monomer II are mixed in a solvent, and the monomers are polymerized by a solution polymerization method to obtain a copolymer. 3 and R 4and an amine compound having R 3 and R 4 Then, the R 1 and R 2 and adding an amine compound having R 3 and R 4 In some or all of the units derived from the remaining monomer II into which R 1 and R 2 Alternatively, R is introduced into the copolymer. 1 and R 2 After introducing R 3 and R 4 may be introduced. The carboxylic acid in the solution containing the modified copolymer thus obtained is neutralized in whole or in part using a neutralizing agent, as necessary. Thereafter, if necessary, solvent substitution is performed to replace the solvent in the solution containing the modified copolymer with an aqueous solvent, thereby precipitating the modified copolymer and obtaining Dispersant I.

[0042] R 1 and R 2 Examples of the amine compound for introducing the formula include cetylamine, 1-aminoheptadecane, stearylamine, 1-aminononadecane, icosylamine, and behenylamine.

[0043] R 3 and R 4Examples of the amine compound for introducing the formula include isobutylamine, tert-butylamine, n-butylamine, isohexylamine, 2-ethylhexylamine, isooctylamine, n-octylamine, n-butylamine, isodecylamine, diethylamine, dibutylamine, dicyclohexylamine, ethanolamine, N-methylethanolamine, N-ethylethanolamine, 2-amino-1-propanol, 2-amino-2-methyl-1-propanol, 1-amino-2-propanol, 2-amino-1,3-propanediol, diethanolamine, and polyalkylene oxide amines. Commercially available polyalkylene oxide amines include M-600 (PO / EO ratio = 9 / 1), M-1000 (PO / EO ratio = 3 / 19), M-2005 (PO / EO ratio = 29 / 6), M-2070 (PO / EO ratio = 10 / 31), and M-3085 (PO / EO ratio = 8 / 58) from the JEFFAMINE M-series (manufactured by Tomoe Engineering Co., Ltd.).

[0044] Examples of solvents that can be used in the synthesis of Dispersant I include organic solvents such as hydrocarbons (hexane, heptane, etc.), aromatic hydrocarbons (toluene, xylene, etc.), ketones (acetone, methyl ethyl ketone, methyl isobutyl ketone, etc.), ethers (tetrahydrofuran, diethylene glycol dimethyl ether, etc.), and N-methylpyrrolidone. The amount of solvent is preferably 0.5 to 10 times the total amount of monomers by mass.

[0045] The polymerization initiator used in the polymerization can be a known radical polymerization initiator, such as an azo polymerization initiator, hydroperoxides, dialkyl peroxides, diacyl peroxides, or ketone peroxides. The amount of the polymerization initiator is preferably 0.01 to 5 mol% based on the total amount of monomer components. The polymerization reaction is preferably carried out in a nitrogen stream at a temperature range of 40 to 180°C, and the reaction time is preferably 0.5 to 20 hours. A known chain transfer agent can be used during the polymerization. Examples of the chain transfer agent include isopropyl alcohol and mercapto compounds such as mercaptoethanol.

[0046] (Dispersant II) In one embodiment, the conductive material slurry of the present disclosure contains, as the dispersant of the present disclosure, a resin (hereinafter also referred to as "dispersant II") containing a structural unit represented by the following general formula (3) (hereinafter also referred to as "structural unit B3"). Dispersant II may be composed only of structural unit B3, or may further contain at least one structural unit selected from a structural unit represented by the following general formula (8) (hereinafter also referred to as "structural unit B8") and a structural unit B represented by the following general formula (9) (hereinafter also referred to as "structural unit B9"). The method for synthesizing dispersant II is not particularly limited, and a method typically used for polymerizing vinyl monomers is used. [ka]

[0047] In the above general formula (3), R 5 , R 6 , R 7 are the same or different and are a hydrogen atom or a methyl group, and preferably, R 5 and R 6 is a hydrogen atom, and R 7 is a methyl group. In Dispersant II, Structural Unit B3 is a component that adjusts the weak adsorption to the carbon material-based conductive material and the solubility in organic solvents.

[0048] From the viewpoint of the solubility of the dispersant II in organic solvents, the monomer that provides the structural unit B3 is preferably at least one selected from acrylamide (AAm) and methacrylamide (MAAm), and more preferably methacrylamide (MAAm).

[0049] The proportion of structural unit B3 in Dispersant II is preferably 10% by mass or more, more preferably 15% by mass or more, and even more preferably 20% by mass or more, from the viewpoint of adjusting the adsorption to the carbonaceous conductive material and the solubility of Dispersant II in organic solvents, and from the same viewpoint, is preferably 100% by mass or less, more preferably less than 70% by mass, even more preferably less than 50% by mass, and even more preferably 40% by mass or less. The proportion of structural unit B3 in Dispersant II can be considered as the proportion of the amount of monomer that provides structural unit B3 relative to the total amount of monomers used in the synthesis of Dispersant II.

[0050] In the above general formula (8), R 16 is a hydrocarbon group having 8 to 30 carbon atoms, and X 1 represents a nitrogen atom or an oxygen atom, and R 17 is a hydrogen atom or a methyl group. In Dispersant II, the structural unit B8 is a component responsible for adsorption to the carbonaceous conductive material. From the viewpoint of improving the adsorption of Dispersant II to the surface of the carbonaceous conductive material, R 17 is preferably a methyl group, and X 1 is preferably an oxygen atom. 16 From the viewpoint of improving the adsorption of the dispersant II to the surface of the carbon material-based conductive material, the hydrocarbon group in R is preferably an alkyl group or an alkenyl group, more preferably an alkyl group. 16 The number of carbon atoms in R is 8 or more, preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, and even more preferably 16 or more, and from the same viewpoint, it is 30 or less, preferably 24 or less, more preferably 22 or less, and even more preferably 20 or less. 16 From the same viewpoint, at least one selected from a cetyl group, a stearyl group, an oleyl group, and a behenyl group is preferred.

[0051] From the viewpoint of improving the adsorptivity of Dispersant II to the surface of the carbon material-based conductive material, the proportion of structural unit B8 in Dispersant II is preferably 25% by mass or more, more preferably 30% by mass or more, and even more preferably 35% by mass or more, and from the same viewpoint, it is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less. The proportion of structural unit B8 in Dispersant II can be considered to be the proportion of the amount of monomer that provides structural unit B8 relative to the total amount of monomers used in the synthesis of Dispersant II.

[0052] From the viewpoint of improving the adsorptivity of Dispersant II to the surface of the carbon material-based conductive material, preferred examples of the monomer that provides Structural Unit B8 include ester compounds of 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, and behenyl (meth)acrylate; and amide compounds such as 2-ethylhexyl (meth)acrylamide, octyl (meth)acrylamide, lauryl (meth)acrylamide, stearyl (meth)acrylamide, and behenyl (meth)acrylamide. Among these, from the viewpoint of improving the dispersibility of the carbonaceous conductive material and facilitating the introduction of the structural unit B8 into the dispersant II, the monomer that provides the structural unit B8 is preferably at least one selected from lauryl (meth)acrylate, stearyl (meth)acrylate, and behenyl (meth)acrylate, more preferably at least one selected from stearyl (meth)acrylate and behenyl (meth)acrylate, even more preferably at least one selected from stearyl methacrylate (SMA) and behenyl acrylate (BeA), and even more preferably stearyl methacrylate. Note that "(meth)acrylate" refers to acrylate and / or methacrylate. The "(meth)" in other compounds has the same meaning.

[0053] In the dispersant II, the structural unit B9 is a component that improves the dispersibility of the carbon material-based conductive material by steric repulsion and adjusts the solubility of the dispersant II in organic solvents. 2is a carbonyl group or a cyano group, and X 3 may be present or absent, and if present, is an alkyleneoxy group or polyalkyleneoxy group terminated with a hydroxyl group or a methoxy group (-OCH3), and R 18 is hydrogen or a methyl group. The alkyleneoxy group is preferably an alkyleneoxy group having 2 to 3 carbon atoms, more preferably an alkyleneoxy group having 2 carbon atoms, i.e., an ethyleneoxy group. The number of moles of alkyleneoxy groups added is preferably 5 moles or less, more preferably 4 moles or less, and preferably 1 mole or more.

[0054] The proportion of structural unit B9 in Dispersant II is preferably 15% by mass or more, more preferably 20% by mass or more, and even more preferably 25% by mass or more, from the viewpoints of improving the dispersibility of the carbonaceous conductive material and the solubility of Dispersant II in organic solvents, and from the same viewpoints, is preferably 50% by mass or less, more preferably less than 45% by mass, and even more preferably 40% by mass or less. The proportion of structural unit B9 in Dispersant II can be considered as the proportion of the amount of monomer that provides structural unit B9 relative to the total amount of monomers used in the synthesis of Dispersant II.

[0055] From the viewpoints of improving the dispersibility of the carbonaceous conductive material due to steric repulsion and adjusting the solubility of Dispersant II in organic solvents, preferred monomers that provide structural unit B9 include acrylonitrile (AN), methacrylonitrile (MAN), methoxypolyethylene glycol methacrylate having an average number of moles of ethylene oxide added of 2 to 4, 2-hydroxyethyl methacrylate (HEMA), 2-hydroxyethyl acrylate, etc. Among these, at least one selected from acrylonitrile (AN) and methacrylonitrile (MAN) is more preferred, and acrylonitrile (AN) is even more preferred.

[0056] From the viewpoint of adsorption to the carbonaceous conductive material, the weight-average molecular weight of Dispersant II is preferably 5,000 or more, more preferably 10,000 or more, and even more preferably 15,000 or more. From the viewpoints of solubility in organic solvents, dispersibility of CNTs, and low viscosity of the slurry, the weight-average molecular weight is preferably 200,000 or less, more preferably 100,000 or less, and even more preferably 60,000 or less. The weight-average molecular weight of Dispersant II is a value measured by GPC (gel permeation chromatography), and the detailed measurement conditions are as shown in the "Measurement of weight-average molecular weight" section of the Examples.

[0057] (Dispersant III) In one embodiment, the conductive material slurry of the present disclosure contains a resin (hereinafter also referred to as "dispersant III") containing a structural unit represented by the following general formula (4) (hereinafter also referred to as "structural unit B4") as a dispersant of the present disclosure. Dispersant III may be composed solely of structural unit B4 represented by the following general formula (4), or may further contain at least one structural unit selected from a structural unit represented by the following general formula (10) (hereinafter also referred to as "structural unit B10") and a structural unit represented by the following general formula (11) (hereinafter also referred to as "structural unit B11"). The method for synthesizing dispersant III is not particularly limited, and it can be obtained, for example, by saponifying a homopolymer of a monomer that provides structural unit B10, or by saponifying a copolymer of a monomer that provides structural unit B10 and a monomer that provides structural unit B11.

[0058] [ka]

[0059] The structural unit B4 is a component that is responsible for adjusting the adsorption of the dispersant III to the carbon material-based conductive material and the solubility of the dispersant III in organic solvents.

[0060] From the viewpoint of adsorption to the carbonaceous conductive material, the proportion of structural unit B4 in Dispersant III is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 60% by mass or more, and from the same viewpoint, it is preferably 99% by mass or less, more preferably 95% by mass or less, even more preferably 90% by mass or less, and even more preferably 84% by mass or less. The proportion of structural unit B4 is controlled by the degree of saponification reaction (degree of saponification).

[0061] In the dispersant III, the structural unit B10 is a component that adjusts the solubility of the dispersant III in an organic solvent. 19 is a hydrocarbon group having 1 to 4 carbon atoms. From the viewpoint of the solubility of dispersant III in organic solvents, R 19 The number of carbon atoms is preferably 4 or less, more preferably 2 or less.

[0062] The monomer that provides the structural unit B10 is preferably a fatty acid vinyl ester from the viewpoint of the solubility of the dispersant III in an organic solvent. Specific examples include vinyl formate, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caprate, vinyl caprylate, vinyl caproate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl pivalate, vinyl octylate, vinyl monochloroate, vinyl benzoate, vinyl cinnamate, vinyl crotonate, divinyl adipate, and derivatives thereof. Of these, the monomer that provides the structural unit B10 is preferably vinyl acetate.

[0063] From the viewpoint of the solubility of Dispersant III in organic solvents, the proportion of structural unit B10 in Dispersant III is preferably 2% by mass or more, more preferably 4% by mass or more, and even more preferably 6% by mass or more, and from the same viewpoint, is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less. The proportion of structural unit B10 is controlled by the degree of saponification reaction (degree of saponification).

[0064] In the dispersant III, the structural unit B11 is a component that is responsible for the solubility of the dispersant III in organic solvents and the adsorption to the carbon material-based conductive material. 20 , R 21 are the same or different and are hydrocarbon groups having 1 to 4 carbon atoms which may contain a hydrogen atom or a hydroxyl group.

[0065] The monomer that provides the structural unit B11 is preferably one selected from the group consisting of 2-propen-1-ol (allyl alcohol), 1-propene-1,3-diol, 1-propen-2-ol, 2-methyl-2-propen-1-ol, 2-buten-1-ol (crotyl alcohol), 2-methyl-2-buten-1-ol, 1-methyl-2-buten-1-ol (prenol), 2-butene-1,4-diol, 1-butene-3,4-diol, 2-methyl-2-butene-1,4-diol, 4-penten-2-ol, 3-penten-1-ol, 4-penten-2-ol, 4-penten-1-ol, 1-pentene-4,5-diol, and 2-pentene-1,5-diol, either alone or in combination. Among these, the monomer that provides the structural unit B11 preferably includes a monomer having two or more hydroxyl groups, such as 2-propen-1-ol (allyl alcohol) or 1-pentene-4,5-diol.

[0066] The proportion of the structural unit B11 in Dispersant III is preferably 0% by mass or more, more preferably 5% by mass or more, and even more preferably 10% by mass or more, from the viewpoint of the adsorption onto the carbon material-based conductive material, and is preferably 30% by mass or less, more preferably 25% by mass or less, and even more preferably 20% by mass or less, from the viewpoint of the solubility of Dispersant III in organic solvents.

[0067] From the viewpoint of adsorption to CNTs, the weight-average molecular weight of Dispersant III is preferably 10,000 or more, more preferably 15,000 or more, and even more preferably 20,000 or more. From the viewpoints of the solubility of Dispersant III in organic solvents, the dispersibility of the carbon material-based conductive material, and low viscosity of the conductive material slurry, the weight-average molecular weight is preferably 150,000 or less, more preferably 120,000 or less, and even more preferably 100,000 or less. The weight-average molecular weight of Dispersant III is a value measured by GPC (gel permeation chromatography), and detailed measurement conditions are as shown in the "Measurement of weight-average molecular weight" section of the Examples.

[0068] (Dispersant IV) In one embodiment, the conductive material slurry of the present disclosure contains a resin (hereinafter also referred to as "dispersant IV") containing a structural unit represented by the following general formula (5) (hereinafter also referred to as "structural unit B5") as a dispersant of the present disclosure. Dispersant IV is composed of structural unit B5 represented by the following general formula (5). [ka]

[0069] In the above general formula (5), R 8 , R 9 , R 10 , R 11 , R 12 , R 13 are the same or different and each represents a hydrogen atom or a methyl group, and the degree of methyl group substitution is 0.5 or more and less than 2.9 per glucose ring.

[0070] General formula (5) is cellulose in which some or all of the hydrogen atoms of the hydroxyl groups have been substituted with methyl groups. From the viewpoint of good solubility in the solvent of dispersant IV, the degree of methyl group substitution of methyl cellulose is 0.1 or more, preferably 0.5 or more, more preferably 1.0 or more, and even more preferably 1.5 or more per glucose ring. Furthermore, from the viewpoint of suppressing an increase in the viscosity of the conductive material slurry, the degree of methyl group substitution is less than 2.9, preferably less than 2.5, and more preferably less than 2.0. The degree of methyl group substitution is determined by the following formula: H 1 -NMR can be used to calculate.

[0071] The viscosity of a 2% by mass aqueous solution of Dispersant IV at 20°C (E-type viscometer, cone rotor 1°34'XR24, 10 rpm) is preferably 2 mPa·s or more, more preferably 5 mPa·s or more, and even more preferably 8 mPa·s or more from the viewpoint of ease of handling, and is preferably 20 mPa·s or less, preferably 17 mPa·s or less, and even more preferably 15 mPa·s or less from the viewpoint of reducing the slurry viscosity.

[0072] Dispersant IV may be a commercially available product, for example METOLOSE (registered trademark) SM-4 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0073] <Organic solvents> Examples of organic solvents constituting the conductive material slurry of the present disclosure (hereinafter, sometimes referred to as "organic solvent C" to distinguish them from the solvent used in synthesizing the dispersant) include amide-based polar organic solvents such as dimethylformamide (DMF), diethylformamide, dimethylacetamide (DMAc), and N-methylpyrrolidone (NMP), ketone-based polar organic solvents such as methyl ethyl ketone (MEK) and methyl isobutyl ketone (MIBK), and ester-based polar organic solvents such as ethyl acetate, γ-butyllactone, and ε-caprolactone. Organic solvent C may be one of these organic solvents or a combination of two or more thereof, but it is more preferable for it to contain N-methylpyrrolidone, which has high solubility, and even more preferable for it to be N-methylpyrrolidone.

[0074] <Organic amine> In one embodiment, the conductive material slurry of the present disclosure preferably contains an organic amine soluble in an organic solvent (hereinafter also referred to as "organic amine B2" to distinguish it from the organic amine B1 used in synthesizing the dispersant) from the viewpoint of the effect of reducing the viscosity of the conductive material slurry and the positive electrode paste. The organic amine B2 preferably has an SP value of 9.5 (cal / cm 3 ) 1 / 2 More than 15.0(cal / cm 3 ) 1 / 2The following amine compounds are preferred, and from the viewpoint of suppressing residues on the electrodes, it is preferred that the boiling point is 260° C. or less.

[0075] The SP value of the organic amine B2 of the present disclosure is preferably 9.5 (cal / cm 3 ) from the viewpoint of reducing the viscosity of the positive electrode paste. 3 ) 1 / 2 More preferably, 10.5 (cal / cm 3 ) 1 / 2 More preferably, 11.0 (cal / cm 3 ) 1 / 2 and preferably 15.0 (cal / cm 3 ) 1 / 2 Less than 14.0 (cal / cm 3 ) 1 / 2 More preferably, 13.5 (cal / cm 3 ) 1 / 2 The following is the result.

[0076] The boiling point of the organic amine B2 of the present disclosure is preferably 260°C or lower, but from the viewpoint of reducing the resistance of the electrode of the electricity storage device, it is preferably a temperature at which it volatilizes during drying in the electrode production process, and is more preferably lower than the boiling point of N-methylpyrrolidone (NMP) (boiling point 202°C), which is frequently used as a solvent for positive electrode paste, and from the viewpoint of reusing NMP, it is even more preferably 190°C or lower. From the viewpoint of handleability, the lower limit of the boiling point of the organic amine B2 of the present disclosure is preferably 100°C or higher, and more preferably 120°C or higher.

[0077] Among the preferred specific examples of organic amine B1 described above, preferred specific examples of organic amine B2 of the present disclosure are those having an SP value of 9.5 (cal / cm 3 ) from the viewpoint of reducing the viscosity of the positive electrode paste. 3 ) 1 / 2 More than 14.0(cal / cm 3 ) 1 / 2Preferred are amine compounds having a molecular weight of 1,000 or less and a boiling point of 260° C. or less. Among these, from the viewpoint of reducing the DC resistance of the electricity storage device, at least one selected from the group consisting of 2-amino-2-methyl-1-propanol (AMP), 1-aminoethanol, 2-N-dibutylaminoethanol, 1-phenylmethanamine, 2-dimethylaminoethanol, N-methyl-2-aminoethanol, and N-ethyldiethanolamine is preferred, at least one selected from the group consisting of 2-dimethylaminoethanol, 2-amino-2-methyl-1-propanol, and N-methyl-2-aminoethanol is more preferred, and 2-amino-2-methyl-1-propanol is particularly preferred.

[0078] (CNT content in conductive slurry) The content of CNTs in the conductive material slurry of the present disclosure is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.25% by mass or more, from the viewpoint of improving the convenience of adjusting the concentration of the positive electrode paste, and is preferably 5% by mass or less, more preferably 3% by mass or less, and even more preferably 2% by mass or less, from the viewpoint of providing the conductive material slurry with a viscosity that is easy to handle.

[0079] (Dispersant content in conductive material slurry) The content of the dispersant in the conductive material slurry of the present disclosure is preferably 0.2 mass% or more, more preferably 0.3 mass% or more, even more preferably 0.4 mass% or more, and even more preferably 0.5 mass% or more, from the viewpoint of improving the dispersibility of CNTs, and is preferably 2.0 mass% or less, more preferably 1.5 mass% or less, even more preferably 1.2 mass% or less, and even more preferably 1.0 mass% or less, from the viewpoint of high conductivity.

[0080] The content of the dispersant in the conductive material slurry of the present disclosure is preferably 50 parts by mass or more, more preferably 100 parts by mass or more, even more preferably 150 parts by mass or more, and even more preferably 200 parts by mass or more, relative to 100 parts by mass of CNTs, from the viewpoint of improving the dispersibility of CNTs, and from the viewpoint of high conductivity, it is preferably 1000 parts by mass or less, more preferably 500 parts by mass or less, even more preferably 400 parts by mass or less, and even more preferably 300 parts by mass or less.

[0081] (Content of organic amine B2 in conductive material slurry) The content of organic amine B2 in the conductive material slurry of the present disclosure is preferably 0.01 mass% or more, more preferably 0.05 mass% or more, even more preferably 0.1 mass% or more, and still more preferably 0.2 mass% or more, from the viewpoint of improving the dispersibility of CNTs and reducing the resistance of the electricity storage device, and is preferably 2.0 mass% or less, more preferably 1.5 mass% or less, even more preferably 1.0 mass% or less, and still more preferably 0.8 mass% or less, from the viewpoint of high conductivity.

[0082] The content of organic amine B2 in the conductive material slurry of the present disclosure is preferably 10 parts by mass or more, more preferably 20 parts by mass or more, even more preferably 50 parts by mass or more, and even more preferably 80 parts by mass or more, relative to 100 parts by mass of CNTs, from the viewpoint of improving the dispersibility of the carbon material-based conductive material and from the viewpoint of reducing the resistance of the electricity storage device, and is preferably 300 parts by mass or less, more preferably 200 parts by mass or less, and even more preferably 150 parts by mass or less, from the viewpoint of high conductivity.

[0083] The conductive material slurry is measured by a rheometer at a shear rate of 0.1 s -1 From the 1000s -1 After raising it to (outbound), 1000s -1 to 0.1 seconds -1 When the shear rate is 1 s -1 In view of electrical conductivity, the viscosity is preferably 4.6 Pa·s or more, and in view of mixability with the active material, it is preferably 20 Pa·s or less, more preferably 10 Pa·s or less.

[0084] (Method for producing conductive slurry) In one or more embodiments, the conductive material slurry of the present disclosure can be prepared by mixing a mixture of the dispersant of the present disclosure, CNTs, organic solvent C, and, if necessary, an organic amine B2, using a mixer / disperser.

[0085] Examples of the mixer / disperser include at least one selected from an ultrasonic homogenizer, a vibration mill, a jet mill, a ball mill, a bead mill, a sand mill, a roll mill, a homogenizer, a high-pressure homogenizer, an ultrasonic device, an attritor, a dissolver, and a paint shaker. Some of the components constituting the conductive material slurry may be mixed first and then mixed with the remainder, or each component may be added in multiple batches rather than all at once. The dispersant of the present disclosure may be dissolved in an organic solvent C to form a dispersant composition containing the dispersant of the present disclosure and the organic solvent C, which may then be mixed with other components such as CNTs. The CNTs may be in a dry state or dispersed in a solvent. Examples of the solvent include the same organic solvent C as described above.

[0086] <Positive electrode paste for energy storage devices> In one aspect, the present disclosure relates to a positive electrode paste for an electricity storage device (hereinafter also referred to as the "positive electrode paste of the present disclosure") comprising a dispersant of the present disclosure, CNTs, a positive electrode active material, an organic solvent, and, optionally, an organic amine B2. A preferred embodiment of the dispersant of the present disclosure in this aspect is as described above. The organic solvent in this aspect is preferably the same as the organic solvent C described above, more preferably NMP. Because the positive electrode paste of the present disclosure contains the dispersant of the present disclosure, it is possible to form a positive electrode coating film with a low resistance value.

[0087] The positive electrode paste of the present disclosure may further include a binder. In one or more embodiments, the positive electrode paste of the present disclosure may further include a conductive material other than CNT. Examples of the conductive material other than CNT include carbon material-based conductive materials such as carbon black and graphene, and conductive polymers such as polyaniline.

[0088] (Cathode active material) The positive electrode active material is not particularly limited as long as it is an inorganic compound, and for example, a compound having an olivine structure or a lithium transition metal composite oxide can be used. The compound having an olivine structure is represented by the general formula Li x M1 s PO4 (where M1 is a 3d transition metal, 0≦x≦2, 0.8≦s≦1.2) can be exemplified. Compounds having an olivine structure may be used after being coated with amorphous carbon or the like. Examples of lithium transition metal composite oxides include lithium manganese oxides having a spinel structure, and lithium manganese oxides having a layered structure and the general formula Li x MO 2- Examples of the lithium transition metal composite oxide include a lithium transition metal composite oxide represented by x≦x≦1.2 and δ≦0.5 (where M is a transition metal, 0.4≦x≦1.2, 0≦δ≦0.5). The transition metal M may include Co, Ni, or Mn. The lithium transition metal composite oxide may further contain one or more elements selected from Al, Mn, Fe, Ni, Co, Cr, Ti, Zn, P, and B.

[0089] The content of the positive electrode active material in the positive electrode paste of the present disclosure is not particularly limited as long as it can be adjusted according to the viscosity of the positive electrode paste suitable for application to a current collector. From the viewpoints of energy density and stability of the positive electrode paste, however, the content is preferably 40% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, and is preferably 90% by mass or less, more preferably 85% by mass or less, even more preferably 80% by mass or less.

[0090] The content of the positive electrode active material in the total solid content of the positive electrode paste of the present disclosure is not particularly limited. The content of the positive electrode active material in the total solid content of the positive electrode paste of the present disclosure may be the same as that in the total solid content of a conventionally known positive electrode paste, and is preferably 90.0 mass% or more to maintain a high energy density of the energy storage device, and is preferably 99.9 mass% or less to ensure the conductivity and coating properties of the composite layer.

[0091] (binder) As the binder (binder resin), polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer, styrene-butadiene rubber, polyacrylonitrile, etc. can be used alone or in combination.

[0092] The content of the binder in the total solid content of the positive electrode paste of the present disclosure is preferably 0.05% by mass or more from the viewpoints of the coating properties of the composite layer and the binding strength with the current collector, and is preferably 5.00% by mass or less from the viewpoint of maintaining a high energy density of the electricity storage device.

[0093] (Dispersant content in positive electrode paste) From the viewpoint of coating resistance, the content of the dispersant of the present disclosure in the positive electrode paste of the present disclosure is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and is preferably 2.0% by mass or less, more preferably 1.0% by mass or less.

[0094] (Content of organic amine B2 in positive electrode paste) The content of organic amine B2 of the present disclosure in the positive electrode paste of the present disclosure is preferably 0.005% by mass or more, more preferably 0.012% by mass or more, and even more preferably 0.02% by mass or more, from the viewpoints of increasing the solids concentration of the positive electrode paste and reducing the viscosity, and is preferably 0.2% by mass or less, more preferably 0.1% by mass or less, and even more preferably 0.05% by mass or less, from the viewpoints of solubility in the solvent and stability of the positive electrode paste.

[0095] (CNT content in positive electrode paste) The CNT content of the positive electrode paste of the present disclosure is preferably 0.01% by mass or more, more preferably 0.02% by mass or more, and even more preferably 0.03% by mass or more, from the viewpoint of the conductivity of the composite layer, and is preferably 0.5% by mass or less, more preferably 0.2% by mass or less, and even more preferably 0.1% by mass or less, from the viewpoint of maintaining a high energy density of the electricity storage device.

[0096] In one or more embodiments, the positive electrode paste of the present disclosure can be prepared by mixing and stirring a positive electrode active material, the conductive material slurry of the present disclosure, a binder, organic amine B2, an organic solvent (additional solvent) for adjusting the solid content concentration, and the like. In addition, a dispersant other than the dispersant of the present disclosure, a functional material, and the like may be added. The organic solvent (additional solvent) is preferably the organic solvent C described above, and more preferably NMP. A planetary mixer, a bead mill, a jet mill, or the like can be used for mixing and stirring these components, or these can be used in combination.

[0097] The positive electrode paste of the present disclosure can be prepared by premixing some of the components used in preparing the positive electrode paste and then mixing the premixed components with the remaining components. Alternatively, each component may be added in multiple batches rather than all at once. This reduces the mechanical load on the stirring device.

[0098] The solids concentration of the positive electrode paste of the present disclosure, the amount of positive electrode active material, the amount of binder, the amount of conductive material slurry, the amount of additive components added, and the amount of organic solvent can be adjusted depending on the viscosity of the positive electrode paste suitable for application to a current collector. From the viewpoint of drying, a small amount of organic solvent is preferable, but from the viewpoints of uniformity of the positive electrode composite layer and surface smoothness, it is preferable that the viscosity of the positive electrode paste is not too high. On the other hand, from the viewpoints of inhibiting drying and obtaining a sufficient thickness of the composite layer (positive electrode coating), it is preferable that the viscosity of the positive electrode paste is not too low.

[0099] The positive electrode paste of the present disclosure is preferably able to be adjusted to a high concentration from the viewpoint of production efficiency, but a significant increase in viscosity is undesirable from the viewpoint of workability. The additives allow the high concentration to be maintained while maintaining a preferred viscosity range.

[0100] The conductive material slurry and the positive electrode paste of the present disclosure may each further contain other components, such as antioxidants, neutralizing agents, antifoaming agents, preservatives, dehydrating agents, rust inhibitors, plasticizers, and binders, to the extent that the effects of the present disclosure are not impaired.

[0101] (Positive electrode paste manufacturing method) In one or more embodiments, the method for producing a positive electrode paste according to the present disclosure may include mixing the conductive material slurry according to the present disclosure, a binder, a positive electrode active material, and, if necessary, an additional organic solvent and / or organic amine B2. The components may be mixed in any order. In one or more embodiments, the conductive material slurry according to the present disclosure, the additional organic solvent, and the binder are mixed and dispersed until homogeneous, and then the positive electrode active material is added and stirred until homogeneous, thereby obtaining a positive electrode paste. The order of addition of the components is not limited thereto.

[0102] <Method of manufacturing a positive electrode coating film or a positive electrode for an electricity storage device> In one aspect, the present disclosure relates to a method for producing a positive electrode coating film or a positive electrode for an electricity storage device, which is produced using the positive electrode paste of the present disclosure. The production method of this aspect includes applying the positive electrode paste of the present disclosure to a current collector, drying the applied current collector, and pressing the applied current collector as needed. In this aspect, the preferred form of the positive electrode paste of the present disclosure is as described above. In the production method of the present disclosure, the positive electrode coating film or the positive electrode for an electricity storage device can be produced by a conventionally known method, except for using the positive electrode paste of the present disclosure.

[0103] A positive electrode coating film or a positive electrode for a power storage device is prepared, for example, by applying the above-described positive electrode paste to a current collector such as aluminum foil and drying the applied paste. To increase the density of the positive electrode coating film, compaction can be performed using a press. A die head, a cone reverse roll, a direct roll, a gravure roll, or the like can be used to apply the positive electrode paste. Drying after application can be performed using heating, airflow, infrared irradiation, or a combination thereof. Drying after application is performed at a temperature at which the organic solvent in the positive electrode paste can no longer be present in the positive electrode paste after the drying time has elapsed. The drying temperature is not particularly limited as long as it is equal to or lower than the thermal decomposition temperature of the binder resin under the drying environment (atmospheric pressure or vacuum), but is preferably equal to or higher than the boiling point of the organic solvent. The drying temperature is preferably 60°C or higher and 220°C or lower, and the drying time is preferably 10 minutes to 24 hours. The positive electrode can be pressed using a roll press or the like. After pressing, the positive electrode for an electricity storage device may be processed into a size suitable for incorporation into an electricity storage device, and then re-dried under the above conditions.

[0104] <Electricity storage device and method for manufacturing the same> In one aspect, the present disclosure relates to an electricity storage device including a positive electrode for an electricity storage device obtained by the method for producing a positive electrode for an electricity storage device of the present disclosure, and a method for producing the same. In one or more embodiments, examples of the power storage device include a lithium ion secondary battery, a lithium-air secondary battery, a sodium ion battery, a sodium-sulfur secondary battery, a sodium-nickel chloride secondary battery, an organic radical battery, a zinc-air secondary battery, and an all-solid-state battery.

[0105] The method for producing an electricity storage device according to the present disclosure includes, for example, the same steps as those of known methods for producing electricity storage devices, except that the positive electrode for an electricity storage device according to the present disclosure is used as the positive electrode for an electricity storage device. The method for producing an electricity storage device according to the present disclosure includes, for example, a step of overlapping two electrodes (a positive electrode and a negative electrode) with a separator interposed therebetween and winding or stacking them into a battery shape, and a step of placing the resulting wound body or stack into a battery container or laminate container, injecting an electrolyte into the container, and sealing the battery container or laminate container.

[0106] The use of the conductive material slurry of the present disclosure is not limited to the preparation of the above-mentioned positive electrode paste. Examples of the conductive material slurry of the present disclosure include negative electrode paste, inkjet ink, conductive ink, etc. The polar solvent (organic solvent) contained in these CNT-containing dispersions is preferably the above-mentioned organic solvent C. The preferred content of CNTs in the CNT-containing dispersion may be determined depending on the application. The preferred content of the dispersant of the present disclosure in the CNT-containing dispersion (relative to 100 parts by mass of carbon material-based conductive material) may be the same as that in the conductive material slurry of the present disclosure.

[0107] In this specification, the upper and lower limits of each numerical range can be combined in any combination, and all such combinations are considered to be preferred numerical ranges described in this specification. [Example]

[0108] Examples and comparative examples of the present disclosure will be shown below, but the present disclosure is not limited thereto.

[0109] 1.Measuring methods for each parameter [Outer diameter of CNT] One or two drops of 100-fold diluted conductive slurry were placed on a microgrid (STEM150Cu grid, carbon reinforced, grid pitch 150 μm) and dried. This sample was placed in a transmission electron microscope (JEOL JEM-2100) and photographed at a magnification of 250,000 times. The accelerating voltage was 100 kV. From the 150 measurement images obtained, the diameters of 108 carbon nanotubes were measured, and the average value was calculated as the outer diameter.

[0110] [Ratio of SWCNT, ratio of DWCNT, ratio of MWCNT, and average number of CNT walls] A few drops of the conductive slurry were placed on a microgrid (STEM150Cu grid, carbon reinforced, grid pitch 150 μm) and dried. This sample was placed in a transmission electron microscope (JEOL JEM-2100) and photographed at 250,000x magnification. The accelerating voltage was 100 kV. From the 100 or more measurement images obtained, 50 or more CNTs were determined to be SWCNT, DWCNT, or MWCNT. The ratio of the number of SWCNTs, DWCNTs, and MWCNTs among these CNTs was each expressed as a percentage. The average number of CNT walls was also calculated using the number of SWCNTs, DWCNTs, and MWCNTs.

[0111] [Measurement of weight-average molecular weight] The weight-average molecular weight of the dispersant was measured by GPC under the following detailed conditions: Measuring device: HLC-8320GPC (Tosoh Corporation) Column: α-M + α-M (Tosoh Corporation) Column temperature: 40℃ Detector: Differential refractive index Eluent: 60mmol / L H3PO4 and 50mmol / L LiBr in N,N-dimethylformamide (DMF) Flow rate: 1mL / min Standard sample used for calibration curve: Polystyrene Sample solution: DMF solution containing 0.5 wt% copolymer solids Sample solution injection volume: 100 μL

[0112] [Viscosity measurement of conductive slurry and positive electrode paste] The viscosity (25° C.) of the conductive material slurry and the positive electrode paste was measured as follows. An Anton Paar MCR302 rheometer was equipped with a parallel plate PP50 and the shear rate was set to 0.1 s -1 From the 1000s -1 After raising it to (outbound), 1000s -1 to 0.1 seconds -1 Return to (return route), return shear rate 1s -1 The viscosity was measured at 100°C, and the results are shown in Tables 5 to 8.

[0113] [Method for measuring CNT particle diameter D50 using DLS measurement] The following conductive material slurries 1 to 14 were placed in the following measuring device and measured under the following conditions. In the obtained particle size distribution, the particle diameter at which the cumulative volume frequency from the small diameter side became 50% was defined as D50. The measurement results are shown in Table 5. <Measurement conditions> Measurement equipment: Malvern Zetasizer Nano "Nano S" Sample volume: 1.5 mL Laser: He-Ne, 3.0mW, 633nm Scattered light detection angle: 173°

[0114] [Measurement of the resistance value of the positive electrode coating] The positive electrode paste was dropped onto a polyester film and uniformly coated with a 100 μm applicator. The coated polyester film was dried at 80° C. for 1 hour to obtain a positive electrode coating film with a thickness of 40 μm. The coating resistance was measured at a limit voltage of 10 V using a Loresta-GP (manufactured by Mitsubishi Chemical Analytech) equipped with a PSP probe, and the results are shown in Tables 7 and 8.

[0115] [Measurement of DC resistance (DCR)] To measure the DC resistance, an electricity storage device was fabricated using the following procedure. The positive electrode paste was applied to a 20 μm thick Al foil (current collector) with a positive electrode capacity of 3 mAh / cm 2 The mixture was coated onto a current collector and vacuum dried at 100°C for 12 hours to produce an electrode material (positive electrode material). This positive electrode material was punched out to a diameter of 13 mm and pressed to produce an electrode (positive electrode). A 19 mm diameter separator and a 15 mm diameter, 0.5 mm thick coin-shaped lithium metal were placed on the positive electrode to produce a 2032-type coin cell (a test half cell). The electrolyte used was 1M LiPF6EC / DEC (volume ratio = 3 / 7).

[0116] The test half-cell was placed in a thermostatic chamber at 30° C. and subjected to a three-cycle charge-discharge test under the following charge-discharge conditions. (Charge / discharge conditions) 30℃, 0.2C, charge 4.45V CC / CV 1 / 10C cutoff, discharge CC 3.0V cutoff. Next, the battery was charged at 0.2 C for 2.5 hours, and the direct current resistance (DCR) was calculated from the voltage drop over 10 seconds during discharge at 0.2 C to 8 C. The results are shown in Tables 7 and 8.

[0117] [G / D ratio (crystallinity)] The CNT was placed in a Raman microscope (RAMANPlus, manufactured by Nanophoton Inc.), and measurements were performed using a 532 nm laser wavelength under the following conditions: -1 ~3000cm -1 The CNTs for measurement were separated onto a glass slide and flattened using a spatula. -1 ~1600cm -1 The maximum peak intensity within the range of G, 1300 cm -1 ~1350cm -1 The maximum peak intensity within this range was defined as D, and the G / D ratio was defined as the G / D ratio of the CNT. <Measurement conditions> Capture time 30 seconds, Accumulation count: 2 times Neutral density filter 10% Magnification of objective lens: 20x Confocus Hall 500 Slit width 100 μm,

[0118] 2. Synthesis of dispersant [Dispersant A-1] A 1 L four-necked separable glass flask was charged with 94.2 g of styrene / maleic anhydride copolymer (Polyscope XIRAN1000®, weight average molecular weight 5000) and 276.2 g of methyl isobutyl ketone (MIBK) (Fujifilm Wako Pure Chemical Industries, Ltd.), and stirred for a fixed time (0.5 hours) under a nitrogen atmosphere. Then, 125.6 g of stearylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise to the flask over 0.5 hours at room temperature, after which the reaction solution in the flask was heated to approximately 72°C and maintained for 2 hours to obtain a polymer solution. The solvent was evaporated from the polymer solution to obtain Dispersant A-1 (100% modified product) with the composition shown in Table 1 below.

[0119] [Dispersant A-2] A glass reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen inlet tube, and dropping funnel was charged with 621.8 g of diisobutylene (Maruzen Petrochemical Co., Ltd.) and 3.1 g of Lutonal A-50 (BASF, polyvinyl ethyl ether). A nitrogen atmosphere was created inside the reactor, and stirring was initiated. The contents of the reactor were heated to 105°C, and the temperature of the contents was maintained at 105°C until the polymerization reaction was completed. 190.0 g of liquid maleic anhydride (Mitsui Chemicals Polyurethanes, Inc.) kept at 70°C, and 9.2 g of Perbutyl O (polymerization initiator, NOF Corporation, t-butylperoxy-2-ethylhexanoate; "Perbutyl" is a registered trademark) dissolved in 23.1 g of diisobutylene as an initiator solution, were each added dropwise to the reactor from separate dropping funnels over a period of 4 hours. Twenty minutes after the end of the dropwise addition, 1.2 g of Perbutyl O dissolved in 7.3 g of diisobutylene was added to the reaction vessel, and the mixture was aged for an additional 2 hours and 40 minutes to complete the polymerization reaction, yielding a solution containing a copolymer. 800 g of ion-exchanged water was added to the reaction vessel, resulting in the precipitation of a copolymer precipitate. Next, unreacted diisobutylene was removed by steam distillation. The steam distillation was carried out by heating the reaction vessel at atmospheric pressure until the temperature of the contents of the reaction vessel reached 100°C and distillation of diisobutylene ceased. Next, water was removed by decantation, and the water-wet copolymer precipitate was dried at 105°C and under a reduced pressure of 100 mmHg for 24 hours to obtain a diisobutylene / maleic anhydride copolymer with a weight-average molecular weight of 19,000.

[0120] 95.7 g of the diisobutylene / maleic anhydride copolymer (weight average molecular weight 19,000) obtained by the above method and 276.2 g of methyl isobutyl ketone (MIBK) (Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 1 L four-neck glass separable flask and stirred for a certain period of time (0.5 hours) under a nitrogen atmosphere. 123.6 g of stearylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) was then added to the flask at room temperature. The reaction solution in the flask was then heated to around 72°C and maintained for 2 hours to obtain a polymer solution. The solvent was evaporated from the polymer solution to obtain Dispersant A-2 (100% modified product) with the composition shown in Table 1 below.

[0121] [Dispersant A-3] A 1 L four-neck glass separable flask was charged with 95.7 g of diisobutylene / maleic anhydride copolymer (weight average molecular weight 19,000) obtained in the synthesis of Dispersant A-2 and 276.2 g of methyl isobutyl ketone (MIBK) (Fujifilm Wako Pure Chemical Industries, Ltd.), and stirred for a certain period (0.5 hours) under a nitrogen atmosphere. Then, 17.8 g of dibutylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise to the flask over 0.5 hours at room temperature, followed by 86.5 g of stearylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) at room temperature. The reaction solution in the flask was then heated to approximately 72 °C and maintained for 2 hours to obtain a polymer solution. The solvent was evaporated from the polymer solution to obtain Dispersant A-3 (100% modified product) with the composition shown in Table 1 below.

[0122] [Dispersant A-4] A 1-L four-neck glass separable flask was charged with 95.7 g of the isobutylene / maleic anhydride copolymer (ISOBAM-04®, manufactured by Kuraray Co., Ltd., weight-average molecular weight 55,000-65,000) obtained by the above method and 276.2 g of methyl isobutyl ketone (MIBK) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the mixture was stirred for a certain period (0.5 hours) under a nitrogen atmosphere. Then, 24.1 g of dibutylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) was added dropwise to the flask over 0.5 hours at room temperature, followed by the addition of 117.1 g of stearylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.). The reaction solution in the flask was then heated to approximately 72°C and maintained for 2 hours, yielding a polymer solution. The solvent was evaporated from the polymer solution to obtain Dispersant A-4 (100% modified product) with the composition shown in Table 1 below.

[0123] [Dispersant A-5] A four-neck flask equipped with a condenser, a nitrogen gas inlet, a thermometer, and a stirrer was charged with 296.5 g (1 mol) of stearyl vinyl ether, 98.1 g (1 mol) of maleic anhydride, 6.0 g (1% by weight of the monomer) of benzoyl peroxide, and 395 g of toluene (same weight as the monomer), and the mixture was heated to 80°C under a nitrogen gas flow and stirred for 4 hours to carry out a copolymerization reaction. The toluene was then distilled off at 110°C under a reduced pressure of approximately 10 mmHg, yielding 394 g of a transparent, viscous liquid copolymer. 95.8 g of the stearyl vinyl ether / maleic anhydride copolymer (weight average molecular weight 11,000) obtained by the above method and 150 g of methyl isobutyl ketone (MIBK) (Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 1 L four-neck glass separable flask and stirred for a certain period of time (0.5 hours) under a nitrogen atmosphere. 31.4 g of isooctylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) was then added to the flask at room temperature. The reaction solution in the flask was then heated to around 72 °C and maintained for 2 hours to obtain a polymer solution. The solvent was evaporated from the polymer solution to obtain Dispersant A-5 (100% modified product) with the composition shown in Table 1 below.

[0124] [Dispersant A-6] 95.7 g of the diisobutylene / maleic anhydride copolymer (weight average molecular weight 19,000) prepared for the synthesis of Dispersant A-2 and 276.2 g of methyl isobutyl ketone (MIBK) (Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 1 L four-neck glass separable flask and stirred for a certain period (0.5 hours) under a nitrogen atmosphere. 17.6 g of dibutylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) was then added dropwise to the flask over 0.5 hours at room temperature, followed by 99.3 g of behenylamine (Fujifilm Wako Pure Chemical Industries, Ltd.) at room temperature. The reaction solution in the flask was then heated to around 72 ° C and maintained for 2 hours to obtain a polymer solution. The solvent was evaporated from the polymer solution to obtain Dispersant A-6 (100% modified product) with the composition shown in Table 1 below.

[0125] [Dispersant A-7] 95.7 g of the diisobutylene / maleic anhydride copolymer (weight average molecular weight 19,000) obtained with Dispersant A-2 and 276.2 g of methyl isobutyl ketone (MIBK) (Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a 1 L four-neck glass separable flask and stirred for a certain period (0.5 hours) under a nitrogen atmosphere. 14.4 g of diethanolamine (Fujifilm Wako Pure Chemical Industries, Ltd.) was then added dropwise to the flask over 0.5 hours at room temperature, followed by 85.9 g of stearylamine (Fujifilm Wako Pure Chemical Industries, Ltd.). The reaction solution in the flask was then heated to approximately 72 °C and maintained for 2 hours to obtain a polymer solution. The solvent was evaporated from the polymer solution to obtain Dispersant A-7 (100% modified product) with the composition shown in Table 1 below.

[0126] [Dispersant A-8] A 1 L four-necked separable glass flask was charged with 95.7 g of styrene / maleic anhydride copolymer (XIRAN1000 (registered trademark) manufactured by Polyscope, weight average molecular weight 5000) and 300 g of methyl isobutyl ketone (MIBK) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.), and the mixture was stirred for a certain period (0.5 hours) under a nitrogen atmosphere. Then, 177.0 g of Jeffamine M2070 (manufactured by Tomoe Engineering Co., Ltd.) was added dropwise to the flask over 1.0 hour at room temperature, followed by the addition of 102.0 g of stearylamine (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) at room temperature. The reaction solution in the flask was then heated to around 72°C and maintained for 2 hours to obtain a polymer solution. The solvent was evaporated from the polymer solution, and the R 1 nC 18 H 37 , R 2 H, R 3 is CH3(EO) 31 (PO) 10 -, R 4 A polymer in which H and M was H was obtained as dispersant A-8 (100% modified product).

[0127] [Dispersant A-9] 100 g of Dispersant A-3 was placed in a 500 ml four-neck flask, and 13.9 g of 2-aminoethanol was added thereto with stirring, followed by stirring at 60° C. for 6 hours to obtain Dispersant A-6.

[0128] [Dispersant B-1] Polyvinylpyrrolidone K-30 (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) having a weight average molecular weight of 40,000 was prepared as dispersant B-1.

[0129] [Table 1]

[0130] [Dispersant A-10] A mixed solution consisting of 40 g of SMA (stearyl methacrylate), 35 g of methacrylamide, 25 g of PEGMA(EO2) (methoxypolyethylene glycol methacrylate with an average ethylene oxide addition mole number of 2), and 100 g of NMP was prepared as the "monomer solution for dripping." A mixed solution consisting of 1.0 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (NOF Corp.; V-65) and 5 g of NMP was prepared as the "initiator solution for dripping." A mixed solution consisting of 1 g of V-65 and 30 g of NMP was prepared as the "initiator solution for dripping." 50 g of NMP and the above initiator solution were placed in a separable flask (reaction vessel) equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube. The atmosphere inside the reaction vessel was replaced with nitrogen, and the temperature inside the vessel (the temperature of the charged raw materials) was heated to 65°C. After the temperature inside the tank reached 65°C, the "monomer solution for dripping" and the "initiator solution for dripping" were simultaneously added dropwise to the tank over a period of 3 hours while stirring the tank. After the dripping was completed, the mixture was stirred at 65°C for an additional 1 hour. Next, the temperature inside the tank was raised to 75°C over approximately 30 minutes while continuing to stir, and after the temperature increase, the mixture was stirred for an additional 2 hours. The temperature inside the tank was then cooled to 40°C or below in a water bath. To adjust the concentration, NMP was added to the tank and mixed to obtain 287 g of an NMP solution of Dispersant A-10. The nonvolatile content of the NMP solution of Dispersant A-10 was 35.5% by mass, and the weight-average molecular weight of Dispersant A-10 was 45,000. The composition of Dispersant A-10 is shown in Table 2 below.

[0131] [Dispersant A-11] A mixed solution consisting of 45 g of SMA, 20 g of methacrylamide, 35 g of HEMA (2-hydroxyethyl methacrylate), and 100 g of NMP was prepared as the "monomer solution for dripping." A mixed solution consisting of 1.0 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (NOF Corp.; V-65) and 5 g of NMP was prepared as the "initiator solution for dripping." A mixed solution consisting of 1 g of V-65 and 30 g of NMP was prepared as the "initiator solution for dripping." 50 g of NMP and the above initiator solution were placed in a separable flask (reaction vessel) equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube. The atmosphere inside the reaction vessel was replaced with nitrogen, and the temperature inside the vessel (the temperature of the charged raw materials) was heated to 65°C. After the temperature inside the tank reached 65°C, the "monomer solution for dripping" and the "initiator solution for dripping" were simultaneously added dropwise to the tank over 3 hours while stirring the tank. After the dripping was completed, the mixture was stirred at 65°C for an additional 1 hour. Next, the temperature inside the tank was raised to 75°C over approximately 30 minutes while continuing to stir, and after the temperature increase, the mixture was stirred for an additional 2 hours. The temperature inside the tank was then cooled to 40°C or below in a water bath. To adjust the concentration, NMP was added to the tank and mixed to obtain 257 g of an NMP solution of Dispersant A-11. The nonvolatile content of the NMP solution of Dispersant A-11 was 35.5% by mass, and the weight-average molecular weight of Dispersant A-11 was 42,000. The composition of Dispersant A-11 is shown in Table 2 below.

[0132] [Dispersant A-12] A mixed solution consisting of 40 g of SMA, 20 g of methacrylamide, 40 g of acrylonitrile, and 100 g of NMP was prepared as the "monomer solution for dripping." A mixed solution consisting of 1.0 g of 2,2'-azobis(2,4-dimethylvaleronitrile) (NOF Corporation; V-65) and 5 g of NMP was prepared as the "initiator solution for dripping." A mixed solution consisting of 1 g of V-65 and 30 g of NMP was prepared as the "initiator solution for dripping." 50 g of NMP and the above initiator solution were placed in a separable flask (reaction vessel) equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube. The atmosphere inside the reaction vessel was replaced with nitrogen, and the temperature inside the vessel (the temperature of the charged raw materials) was heated to 65°C. After the temperature inside the tank reached 65°C, the "monomer solution for dropping" and the "initiator solution for dropping" were simultaneously added dropwise to the tank over 3 hours while stirring the tank. After the dropwise addition was completed, the mixture was stirred at 65°C for an additional 1 hour. Next, the temperature inside the tank was raised to 75°C over approximately 30 minutes while continuing to stir, and after the temperature increase, the tank was stirred for an additional 2 hours. The temperature inside the tank was then cooled to 40°C or below in a water bath. To adjust the concentration, NMP was added to the tank and mixed to obtain 257 g of an NMP solution of Dispersant A-12. The nonvolatile content of the NMP solution of Dispersant A-12 was 35.5% by mass, and the weight-average molecular weight of Dispersant A-12 was 35,000. The composition of Dispersant A-12 is shown in Table 2 below.

[0133] [Dispersant A-13] A mixed solution consisting of 100 g of acrylamide and 200 g of ion-exchanged water was prepared as the "monomer solution for dripping." A mixed solution consisting of 1.0 g of V-50 and 5 g of ion-exchanged water was prepared as the "initiator solution for dripping." A mixed solution consisting of 1 g of V-50 and 30 g of ion-exchanged water was prepared as the "initiator solution for dripping." 50 g of ion-exchanged water and the initiator solution were placed in a separable flask (reaction vessel) equipped with a reflux condenser, a stirrer, a thermometer, and a nitrogen inlet tube. The atmosphere in the reaction vessel was replaced with nitrogen, and the temperature inside the vessel (temperature of the charged raw materials) was heated to 65°C. After the temperature inside the vessel reached 65°C, the "monomer solution for dripping" and the "initiator solution for dripping" were simultaneously added dropwise to the vessel over 3 hours while stirring the contents inside the vessel. After the dripping was completed, the mixture was stirred at 65°C for an additional 1 hour. Next, the temperature in the tank was raised to 75°C over approximately 30 minutes while continuing to stir, and after the temperature increase, the tank was stirred for an additional 2 hours. The aqueous solution was then dehydrated and dried to obtain 100g of Dispersant A-13. The weight-average molecular weight of Dispersant A-13 was 55,000. The composition of Dispersant A-13 is shown in Table 2 below.

[0134] [Table 2]

[0135] [Dispersant A-14] A reaction vessel equipped with a thermometer, reflux tube, nitrogen gas inlet tube, and stirrer was charged with 90 g of vinyl acetate and 10 g of allyl alcohol as polymerizable monomers, 25 g of methanol as solvent, and 0.1 g of azobisisobutyronitrile as polymerization initiator. The copolymerization reaction was carried out at approximately 60°C, and unreacted monomers were removed under reduced pressure to obtain a resin solution. A methanol solution of sodium hydroxide was then added to the mixture to carry out a saponification reaction. The mixture was then thoroughly washed and dried in a hot air dryer. Finally, Dispersant A-14 was obtained, with a degree of polymerization of 300, a degree of saponification of 90 mol%, and a content of structural unit B11 of 16.5% by mass. The composition of Dispersant A-14 is shown in Table 3 below.

[0136] [Dispersant A-15] A reaction vessel equipped with a thermometer, reflux tube, nitrogen gas inlet, and stirrer was charged with 90 g of vinyl acetate and 10 g of 1-pentene-4,5-diol as polymerizable monomers, 25 g of methanol as solvent, and azobisisobutyronitrile as polymerization initiator. The copolymerization reaction was carried out at approximately 60°C, followed by removal of unreacted monomers under reduced pressure to obtain a resin solution. A methanol solution of sodium hydroxide was then added to the mixture to carry out a saponification reaction. The mixture was thoroughly washed and then dried in a hot air dryer. Finally, Dispersant A-15 was obtained, with a degree of polymerization of 300, a degree of saponification of 90 mol%, and a content of structural unit B11 of 17.2% by mass. The composition of Dispersant A-15 is shown in Table 3 below.

[0137] [Dispersant A-16] A reactor equipped with a thermometer, reflux tube, nitrogen gas inlet, and stirrer was charged with 100 g of vinyl acetate as a polymerizable monomer, 25 g of methanol as a solvent, and 0.1 g of azobisisobutyronitrile as a polymerization initiator. The copolymerization reaction was carried out at approximately 60°C, and unreacted monomer was removed under reduced pressure to obtain a resin solution. A methanol solution of sodium hydroxide was then added to the mixture to carry out a saponification reaction. The mixture was then thoroughly washed and dried in a hot air dryer. Finally, Dispersant A-16 was obtained, with a degree of polymerization of 300 and a degree of saponification of 82 mol%. The composition of Dispersant A-16 is shown in Table 3 below.

[0138] [Table 3]

[0139] [Dispersant A-17] Dispersant A-17: METOLOSE (registered trademark) SM-4 (methylcellulose, average degree of substitution 1.8, viscosity of a 2% by weight aqueous solution at 20°C of 12 mPa·s (E-type viscometer, 10 rpm) letter (manufactured by Etsu Chemical Industry Co., Ltd.) was prepared.

[0140] (Adjustment of conductive slurry) [Conductive slurry 1] Carbon nanotubes (CNT-A in Table 4 below, FT2020 manufactured by Cnano, CNT wall number 1 to 2, outer diameter (nm) see Table 4 below for details), dispersant A-1, and NMP were mixed to obtain a crude dispersion. The crude dispersion was loaded into a high-pressure homogenizer (manufactured by Biryu Co., Ltd., product name "BERYU MINI") equipped with a multistage pressure control device (multistage pressure reducer) that applies back pressure during dispersion, and dispersion treatment was performed at a pressure of 120 MPa. Specifically, carbon nanotubes (CNTs) were dispersed by applying shear force to the crude dispersion while applying back pressure, to obtain Conductive Material Slurry 1. The CNT content in Conductive Material Slurry 1 was 0.3 parts by mass, the Dispersant A-1 content was 0.6 parts by mass, and the remainder was NMP. The dispersion treatment was performed by circulating the dispersion by discharging it from the high-pressure homogenizer and then reinjecting it into the high-pressure homogenizer, and this circulation was repeated 20 times. The discharge and injection rate of the dispersion was 45 g / min. The viscosity of Conductive Material Slurry 1 at a temperature of 25°C was 8.2 Pa·s. Using conductive material slurry 1, the number and ratio of SWCNTs, the number and ratio of DWCNTs, the number and ratio of MWCNTs, the outer diameter, and the average number of walls of CNTs were determined according to the methods described in [CNT outer diameter], [SWCNT ratio, DWCNT ratio, MWCNT ratio, and average number of walls of CNT].The results were that the number of SWCNTs was 72 (67%), the number of DWCNTs was 26 (33%), the average number of walls was 1.33, the outer diameter was 2.76 nm, and the number of MWCNTs was 0.

[0141] [Table 4]

[0142] [Conductive Slurry 2-8, 10, 12] Conductive material slurries 2 to 8, 10, and 12 were prepared in the same manner as in the preparation of conductive material slurry 1, except that the types of dispersants were as shown in Table 5 below.

[0143] [Conductive slurry 9] Conductive material slurry 9 was prepared in the same manner as conductive material slurry 2, except that 2-amino-2-methyl-1-propanol (AMP) was added as organic amine B2.

[0144] [Conductive Slurry 11] Conductive material slurry 11 was prepared in the same manner as conductive material slurry 3, except that a mixture of 0.27 parts by mass of CNT-A and 0.03 parts by mass of CNT-C (mixed CNTs) was used as the CNTs. Using conductive material slurry 11, the number and ratio of SWCNTs, the number and ratio of DWCNTs, the average number of CNT walls, and the CNT outer diameter were determined using the methods described in [SWCNT ratio, DWCNT ratio, MWCNT ratio, and average number of CNT walls] and [CNT outer diameter]. The results showed that the number of SWCNTs was 47 (62.7%), the number of DWCNTs was 24 (32%), and the number of MWCNTs with three or more walls was 5.3%, with two 10-walled and two 11-walled. The average number of walls was 1.8, and the average outer diameter was 3.26 nm. The G / D ratio was 30, and the CNT particle diameter D50 measured by DLS was 420 nm.

[0145] [Conductive Slurry 13, 14] Conductive material slurries 13 and 14 were prepared in the same manner as in the preparation of conductive material slurry 1, except that the types of CNTs were as shown in Tables 4 and 5.

[0146] [Table 5]

[0147] As shown in Tables 4 and 5, the CNT particle diameter D50 and viscosity measured by DLS for conductive material slurries 1 to 11 prepared using CNTs with a G / D ratio in the range of 20 or more and less than 80 and the dispersant of the present disclosure were significantly smaller than those for conductive material slurry 12 containing polyvinylpyrrolidone as a dispersant. Furthermore, although the CNT particle diameter D50 and viscosity measured by DLS for conductive material slurries 1 to 11 were not smaller than those of conductive material slurry 14 containing MWCNT, the dispersibility and handleability of the CNTs were good for practical use. In particular, the viscosity of conductive material slurry 9 containing organic amine B2 was low and the handleability was good.

[0148] [Conductive Slurry 15-22] Conductive material slurries 15 to 22 were prepared in the same manner as in the preparation of conductive material slurry 1, except that the types of CNTs and dispersants were as shown in Table 6 below.

[0149] [Conductive Slurry 23, 24] Conductive material slurries 23 and 24 were prepared in the same manner as in the preparation of conductive material slurry 16, except that the types of CNTs were as shown in Tables 4 and 6.

[0150] [Table 6]

[0151] As shown in Tables 4 and 6, the viscosities of conductive material slurries 15 to 22 prepared using CNTs with a G / D ratio in the range of 20 or more and less than 80 and the dispersant of the present disclosure were significantly smaller than that of conductive material slurry 12 containing polyvinylpyrrolidone as a dispersant.

[0152] (Preparation of positive electrode pastes 1 to 14) The conductive material slurry and binder resin solution (PVDF (8%) NMP solution, KF polymer L#7208, manufactured by Kureha Corporation) prepared above were weighed into a 50 ml sample bottle in the amounts (grams) shown in Table 7, and then stirred with a spatula until homogeneous. 0.5 Co 0.2 Mn 0.3O2 (NCM523-ME5E12D, manufactured by Beijing Dangsheng) was added, and the mixture was again mixed with a spatula for approximately 20 seconds until homogenous. The mixture was further mixed for 5 minutes with a planetary centrifugal mixer (AR-100, manufactured by Thinky Corporation) to obtain a positive electrode paste with the composition shown in Table 7.

[0153] The mass ratio of the positive electrode active material, binder (PVDF), conductive material (carbon nanotubes) and dispersant was 98.635:1.153:0.071:0.141 (solid content equivalent), and the solid content (mass %) of the positive electrode paste was 73.2 mass %.

[0154] [Table 7]

[0155] As shown in Table 7, the viscosities of positive electrode pastes 1 to 11 prepared using the conductive material slurry of the present disclosure were significantly smaller than that of positive electrode paste 12 prepared using conductive material slurry 12 containing polyvinylpyrrolidone as a dispersant. Although the viscosities of Positive Electrode Pastes 13 and 14 were lower than those of Positive Electrode Pastes 1 to 11, the resistance of the coating film and the DCR of the electricity storage device produced using Positive Electrode Pastes 13 and 14 were higher than the resistance of the coating film and the DCR of the electricity storage device produced using Positive Electrode Pastes 1 to 11. This confirmed that when the CNTs contained in the positive electrode paste have a G / D ratio in the range of 20 or more and less than 80, a good conductive network of the CNTs can be maintained even if shear force for dispersion is applied to the CNTs during the production of the coating film or electricity storage device.

[0156] (Preparation of positive electrode pastes 15 to 27) The conductive material slurry and binder resin solution (PVDF (8%) NMP solution, KF polymer L#7208, manufactured by Kureha Corporation) prepared above were weighed into a 50 ml sample bottle in the amounts (grams) shown in Table 8, and then stirred with a spatula until homogeneous. 0.5 Co 0.2 Mn0.3 O2 (NCM523-ME5E12D, manufactured by Beijing Dangsheng) was added, and the mixture was again stirred with a spatula for approximately 20 seconds until homogenous. The mixture was further stirred for 5 minutes with a planetary centrifugal mixer (AR-100, manufactured by Thinky Corporation) to obtain a positive electrode paste with the composition shown in Table 8.

[0157] The mass ratio of the positive electrode active material, binder (PVDF), conductive material (carbon nanotubes) and dispersant was 98.635:1.153:0.071:0.141 (solid content equivalent), and the solid content (mass %) of the positive electrode paste was 75.4 mass %.

[0158] [Table 8]

[0159] As shown in Table 8, the viscosities of positive electrode pastes 15 to 22 prepared using the conductive material slurry of the present disclosure were significantly smaller than that of positive electrode paste 25 prepared using conductive material slurry 12 containing polyvinylpyrrolidone as a dispersant. Although the viscosities of positive electrode pastes 23 and 24 were lower than those of positive electrode pastes 15 to 22, the resistance of the coating films and the DCR of the electricity storage devices produced using positive electrode pastes 23 and 24 were higher than the DCR of the electricity storage devices produced using positive electrode pastes 15 to 22. This confirms that when the CNTs contained in the positive electrode paste have a G / D ratio in the range of 20 or more and less than 80, a good conductive network of the CNTs can be maintained even if shear force for dispersion is applied to the CNTs during the production of the coating film or electricity storage device. [Industrial Applicability]

[0160] The present disclosure enables preparation of a conductive material slurry that is easy to handle, thereby enabling preparation of a low-viscosity conductive material slurry and a positive electrode paste with high productivity. Furthermore, by using the conductive material slurry of the present disclosure, a positive electrode for an electricity storage device with low resistance and an electricity storage device can be produced with high productivity.

Claims

1. carbon nanotubes, a dispersant, and an organic solvent; the G / D ratio in the Raman spectrum of the carbon nanotube is 20 or more and less than 80; The dispersant is A maleic acid monoamide resin containing at least one of a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), or A conductive material slurry, which is a resin containing any one of a constitutional unit represented by the following general formula (3), a constitutional unit represented by the following general formula (4), and a constitutional unit represented by the following general formula (5). 【Chemistry 1】 However, in the above general formula (1), R 1 is a hydrocarbon group having 12 to 30 carbon atoms which may have hydrogen or a hydroxyl group, and R 2 is a hydrocarbon group having 1 to 8 carbon atoms which may have hydrogen or a hydroxyl group, and M 1 is hydrogen, NH 4 , metal or organic ammonium. In the above general formula (2), R 3 is a hydrocarbon group or polyalkylene oxide group having 1 to 8 carbon atoms which may have hydrogen or a hydroxyl group, and R 4 is a hydrocarbon group having 1 to 8 carbon atoms which may have hydrogen or a hydroxyl group, and M 1 is hydrogen, NH 4 , metal or organic ammonium. 【Chemistry 2】 In the above general formula (3), R 5 , R 6 , R 7 are the same or different and each represents a hydrogen atom or a methyl group. 【Transformation 3】 【Chemistry 4】 In the above general formula (5), R 8 , R 9 , R 10 , R 11 , R 12 , R 13 are the same or different and are a hydrogen atom or a methyl group, and the degree of substitution of methyl groups per glucose ring is 0.1 to less than 2.

9.

2. the carbon nanotubes include single-walled carbon nanotubes and double-walled carbon nanotubes; 2. The conductive material slurry according to claim 1, wherein the ratio of the single-walled carbon nanotubes is 40% or more and 85% or less, and the ratio of the double-walled carbon nanotubes is 15% or more and 60% or less.

3. The conductive material slurry according to claim 1 , wherein the carbon nanotubes have an outer diameter of 1 nm or more and less than 6 nm.

4. the carbon nanotubes include single-walled carbon nanotubes and double-walled carbon nanotubes; 2. The conductive material slurry according to claim 1, wherein the sum of the ratio of the single-walled carbon nanotubes and the ratio of the double-walled carbon nanotubes to the carbon nanotubes contained in the conductive material slurry is 50% or more.

5. 2. The conductive material slurry according to claim 1, wherein the carbon nanotubes contained in the conductive material slurry have a particle diameter (D50) measured by a dynamic light scattering method of 200 nm or more and 1500 nm or less.

6. The conductive material slurry according to claim 1 , wherein the carbon nanotubes include double-walled carbon nanotubes.

7. 2. The conductive material slurry according to claim 1, wherein the organic solvent is N-methylpyrrolidone.

8. The conductive material slurry according to claim 1 , wherein the content of the dispersant in the conductive material slurry is 0.2 mass % or more and 2.0 mass % or less.

9. A positive electrode paste for an electricity storage device, comprising the conductive material slurry according to claim 1 , a positive electrode active material, and a binder resin.

10. A method for producing a positive electrode for an electricity storage device, comprising applying the positive electrode paste for an electricity storage device according to claim 9 to a current collector and drying the applied paste.

11. A method for producing an electricity storage device, comprising incorporating a positive electrode for an electricity storage device obtained by the method for producing a positive electrode for an electricity storage device according to claim 10.

12. Use of the conductive material slurry according to any one of claims 1 to 8 for producing a positive electrode for an electricity storage device.

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