Binder composition for electrochemical elements, conductive material dispersion for electrochemical elements, slurry for electrochemical element electrodes, electrodes for electrochemical elements and electrochemical elements

Abstract

The purpose of the present invention is to provide a binder composition able to form an electrode in which an increase in internal resistance can be suppressed following electrochemical element cycles. This binder composition contains a polymer X, N-methyl-2-pyrrolidone, and a nitrogen compound other than N-methyl-2-pyrrolidone. The polymer X contains a nitrile group-containing monomer unit and also contains an aliphatic conjugated diene monomer unit and / or an alkylene structural unit. The molecular weight of the nitrogen compound is 1000 or less. In addition, the HSP distance (RA) between the nitrogen compound and the polymer X is 10.0 MPa1 / 2 or less.

Description

[Technical Field]

[0001] The present invention relates to a binder composition for electrochemical elements, a conductive material dispersion for electrochemical elements, a slurry for electrochemical element electrodes, an electrode for an electrochemical element, and an electrochemical element. [Background technology]

[0002] Electrochemical elements such as lithium-ion secondary batteries, lithium-ion capacitors, and electric double-layer capacitors are small, lightweight, have high energy density, and can be repeatedly charged and discharged, making them suitable for a wide range of applications. Therefore, in recent years, improvements to battery components such as electrodes have been considered to further enhance the performance of electrochemical elements.

[0003] Here, the electrodes used in electrochemical elements typically comprise a current collector and an electrode composite layer formed on the current collector. This electrode composite layer is formed, for example, by applying an electrode slurry containing an electrode active material, a conductive material, and a binder composition onto the current collector, and then drying the applied electrode slurry.

[0004] Therefore, in recent years, research has been conducted to improve the performance of electrochemical elements by improving polymer components such as binders. For example, Patent Document 1 proposes using a predetermined copolymer containing units derived from (meth)acrylonitrile and units derived from conjugated diene monomers. According to Patent Document 1, the copolymer functions as a dispersant for dispersing conductive materials such as carbon nanotubes (hereinafter sometimes abbreviated as "CNT"). In Patent Document 1, in order to sufficiently disperse the conductive material, the conductive material and the copolymer are pre-mixed to form a conductive material dispersion, and the resulting conductive material dispersion is combined with an electrode active material to prepare an electrode slurry. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2020-187866 [Overview of the Initiative] [Problems that the invention aims to solve]

[0006] However, the conventional technology described above had a problem in that the internal resistance of the electrochemical element increased when it underwent repeated charging and discharging cycles. In other words, there was room for improvement in the conventional technology in terms of suppressing the increase in internal resistance of the electrochemical element after the cycle.

[0007] Therefore, the present invention aims to provide a binder composition for electrochemical elements, a conductive material dispersion for electrochemical elements, and a slurry for electrochemical element electrodes that can form electrodes capable of suppressing the increase in internal resistance after the electrochemical element cycle. Furthermore, the present invention aims to provide an electrochemical element in which the increase in internal resistance after cycling is suppressed. [Means for solving the problem]

[0008] The inventors diligently conducted research with the aim of solving the above problems. As a result, the inventors discovered that by using a binder composition containing a predetermined polymer, N-methyl-2-pyrrolidone (hereinafter sometimes abbreviated as "NMP") as an organic solvent, and a predetermined nitrogen compound, in which the polymer and the nitrogen compound satisfy a predetermined relationship, it is possible to produce an electrode that can suppress the increase in internal resistance after the cycle of an electrochemical element, and thus completed the present invention.

[0009] In other words, the present invention aims to advantageously solve the above problems, and according to the present invention, the following binder compositions for electrochemical elements are provided [1] to [6], conductive material dispersions for electrochemical elements are provided [7] to

[10] , slurries for electrochemical element electrodes are provided

[11] to

[12] , electrodes for electrochemical elements are provided

[13] , and an electrochemical element is provided

[14] . [1] A binder composition for an electrochemical device, comprising a polymer X, N-methyl-2-pyrrolidone, and a nitrogen compound other than the N-methyl-2-pyrrolidone, wherein the polymer X contains a nitrile group-containing monomer unit and at least one of an aliphatic conjugated diene monomer unit and an alkylene structural unit, the nitrogen compound has a molecular weight of 1,000 or less, and the Hansen solubility parameter (HSP N ) of the nitrogen compound and the Hansen solubility parameter (HSP X ) of the polymer X have a HSP distance (R A ) of 10.0 MPa 1 / 2 or less. A binder composition for an electrochemical device. According to an electrode produced using a binder composition containing both the above-mentioned polymer X and the above-mentioned nitrogen compound in NMP and having a HSP distance (R A ) between the nitrogen compound and the polymer X of the above-mentioned value or less, an increase in the internal resistance of the electrochemical device after cycling can be suppressed.

[0010] Here, in the present invention, the "monomer unit" means "a structural unit (repeating unit) derived from the monomer contained in the polymer obtained using the monomer". Also, in the present invention, the "alkylene structural unit" means "a structural unit composed only of an alkylene structure represented by the general formula -C n H 2n -[where n is an integer of 2 or more]". And the proportion of the polymer containing each structural unit can be measured using nuclear magnetic resonance (NMR) methods such as 1 H-NMR and 13 C-NMR. In the present invention, the "Hansen solubility parameter (HSP N ) of the nitrogen compound" is composed of a polar term δ p1 , a dispersion term δ d1 , and a hydrogen bond term δ h1 , and the "Hansen solubility parameter (HSP X ) of the polymer X" is composed of a polar term δ p2 , a dispersion term δ d2 , and a hydrogen bond term δ h2 . Here, in the present invention, "δ p1 "δ d1 " and "δ h1 ", and "δ p2 "δ d2 " and "δ h2 This can be identified using the method described in the examples. Furthermore, in the present invention, "HSP distance (R A )" is expressed in the following formula (A): HSP distance (R A )={(δ p1 -δ p2 ) 2 +4×(δ d1 -δ d2 ) 2 +( δ h1 -δ h2 ) 2} 1 / 2 ...(A) It can be calculated using [this method].

[0011] [2] The binder composition for electrochemical elements according to [1] above, wherein the polymer X has a weight-average molecular weight of 300,000 or less. If the weight-average molecular weight of polymer X is less than or equal to the value described above, conductive materials such as CNTs can be well dispersed in the conductive material dispersion prepared using the binder composition (i.e., the dispersibility of the conductive material dispersion can be improved), and the increase in internal resistance after the electrochemical element cycle can be further suppressed. In this invention, the "weight-average molecular weight" of the polymer can be measured using the method described in the examples.

[0012] [3] The binder composition for electrochemical elements according to [1] or [2] above, wherein the polymer X contains 500 ppm by mass or more of sulfur. If the sulfur content of polymer X is greater than or equal to the value mentioned above, the dispersibility of the conductive material dispersion can be improved while further suppressing the increase in internal resistance after the electrochemical element cycle. In this invention, the "sulfur content" of the polymer can be measured using the method described in the examples.

[0013] [4] Hansen solubility parameter (HSP) of the nitrogen compound N ) Polarity term δ p1 14.0 MPa 1 / 2 A binder composition for electrochemical elements as described in any of the above [1] to [3]. Hansen solubility parameter (HSP) of nitrogen compounds N ) Polarity term δ p1 If the value is below the above-mentioned value, the dispersibility of the conductive material and the time-dependent stability of the electrode slurry prepared using the binder composition can be improved, while further suppressing the increase in internal resistance after the electrochemical element cycle.

[0014] [5] The nitrogen compound has a cyclic amidine structure, and is a binder composition for electrochemical elements according to any one of [1] to [4] above. Nitrogen compounds having a cyclic amidine structure exhibit excellent viscosity reduction effects in binder compositions. By using nitrogen compounds having a cyclic amidine structure, it is possible to improve the dispersibility of conductive material dispersions while further suppressing the increase in internal resistance after the electrochemical element cycle.

[0015] [6] The binder composition for electrochemical elements according to any one of [1] to [5] above, wherein the ratio of the mass of the nitrogen compound to the total mass of the polymer X and the nitrogen compound is 0.1% by mass or more and 40% by mass or less. If the mass of the nitrogen compound in the total mass of polymer X and the nitrogen compound is within the range described above, it is possible to further suppress the increase in internal resistance after the electrochemical element cycle while improving the dispersibility of the conductive material dispersion and the time-dependent stability of the electrode slurry.

[0016] [7] A conductive material dispersion for an electrochemical element, comprising a binder composition for an electrochemical element as described in any of [1] to [6] above and a fibrous conductive material. An electrode made using a conductive material dispersion containing any of the above-described binder compositions and a fibrous conductive material can suppress the increase in internal resistance after the electrochemical element has been cycled. In this invention, "fibrous conductive material" means a conductive material whose aspect ratio, as measured using a transmission electron microscope (TEM), is 10 or greater.

[0017] [8] The conductive material dispersion for electrochemical elements according to [7] above, wherein the fibrous conductive material is of the bundle type. By using bundled fibrous conductive materials, the dispersibility of the conductive material dispersion can be further improved while suppressing the increase in internal resistance after the electrochemical element cycle. In this invention, "bundle type" refers to a secondary shape that is bundle-like or rope-like, in which multiple fibrous conductive materials are arranged or aligned in a certain direction.

[0018] [9] The conductive material dispersion for electrochemical elements according to [7] or [8] above, wherein the fibrous conductive material has a surface acid content of 0.01 mmol / g or more and 0.20 mmol / g or less. If the surface acid content of the fibrous conductive material is within the above-mentioned range, it is possible to further suppress the increase in internal resistance after the electrochemical element cycle while improving the dispersibility of the conductive material dispersion and the time-dependent stability of the electrode slurry. In this invention, the "surface acid content" and the "surface base content" of the fibrous conductive material, as described later, can be measured using the method described in the examples.

[0019]

[10] A conductive material dispersion for an electrochemical element according to any one of [7] to [9] above, wherein the fibrous conductive material is a fibrous carbon material, and the ratio of the D-band peak intensity to the G-band peak intensity in the Raman spectrum of the fibrous carbon material is 2.0 or less. For fibrous carbon materials used as fibrous conductive materials, if the ratio of the D-band peak intensity to the G-band peak intensity in the Raman spectrum (hereinafter sometimes abbreviated as "D / G ratio") is less than or equal to the value mentioned above, it is possible to further suppress the increase in internal resistance after the electrochemical element cycle while improving the dispersibility of the conductive material dispersion and the time-dependent stability of the electrode slurry. In this invention, the ratio of the D-band peak intensity to the G-band peak intensity in the Raman spectrum of a fibrous carbon material can be measured using the method described in the examples.

[0020]

[11] A slurry for electrochemical element electrodes comprising a conductive material dispersion for electrochemical elements described in any of [7] to

[10] above, and an electrode active material. Electrodes fabricated using an electrode slurry containing one of the conductive material dispersions described above and an electrode active material can suppress the increase in internal resistance after the electrochemical element has been cycled.

[0021]

[12] The slurry for electrochemical element electrodes according to

[11] , further comprising a binder other than the polymer X. If the electrode slurry includes a binder other than polymer X (hereinafter sometimes abbreviated as "other binders") in addition to the conductive material dispersion and electrode active material described above, the electrode composite layer obtained using the electrode slurry can be firmly adhered to the current collector (i.e., the peel strength of the electrode can be improved), while further suppressing the increase in internal resistance after the electrochemical element cycle.

[0022]

[13] An electrode for an electrochemical element, comprising an electrode composite layer formed using the electrochemical element electrode slurry described in

[11] or

[12] above. An electrode comprising an electrode composite layer obtained using any of the electrode slurries described above can suppress the increase in internal resistance after the electrochemical element has been cycled.

[0023]

[14] An electrochemical element comprising electrodes for an electrochemical element as described in

[13] above. The electrochemical element equipped with the electrodes described above exhibits suppressed increases in internal resistance after cycling. [Effects of the Invention]

[0024] According to the present invention, it is possible to provide a binder composition for electrochemical elements, a conductive material dispersion for electrochemical elements, and a slurry for electrochemical element electrodes that can form electrodes capable of suppressing the increase in internal resistance after the electrochemical element cycle. Furthermore, according to the present invention, it is possible to provide an electrochemical element in which the increase in internal resistance after cycling is suppressed. [Modes for carrying out the invention]

[0025] Embodiments of the present invention will be described in detail below. Here, the binder composition for electrochemical elements of the present invention can be used when preparing a slurry for electrochemical element electrodes. Furthermore, the binder composition for electrochemical elements of the present invention can be mixed with a fibrous conductive material such as CNTs to form a conductive material dispersion for electrochemical elements containing the binder composition and the fibrous conductive material, which can then be used to prepare a slurry for electrochemical element electrodes. The slurry for electrochemical element electrodes prepared using the conductive material dispersion can then be used to form electrodes for electrochemical elements such as lithium-ion secondary batteries. Moreover, the electrochemical element of the present invention is characterized by comprising electrodes for electrochemical elements formed using the slurry for electrochemical element electrodes.

[0026] (Binder composition for electrochemical elements) The binder composition of the present invention comprises polymer X, a nitrogen compound, and NMP, and optionally further comprises components other than polymer X, a nitrogen compound, and NMP (other components). In the binder composition of the present invention, Polymer X contains nitrile group-containing monomer units and also contains at least one of aliphatic conjugated diene monomer units and alkylene structural units. The molecular weight of the nitrogen compound is 1,000 or less, and Hansen solubility parameter (HSP) of nitrogen compounds N ) and the Hansen solubility parameter (HSP) of polymer X. X ) and the HSP distance (R A) is 10.0 MPa 1 / 2 The following: It is necessary.

[0027] Furthermore, the polymer X and nitrogen compound described above are included, and the HSP distance (R A By using the binder composition of the present invention, in which the value is less than or equal to the value described above, it is possible to produce electrodes that can suppress the increase in internal resistance after the electrochemical element has been cycled.

[0028] <Polymer X> Polymer X is a component that can function as a binder in an electrode composite layer formed using a binder composition, holding electrode active materials and other components without detaching them from the current collector. Polymer X can also function as a dispersant in a conductive material dispersion prepared using a binder composition, capable of dispersing fibrous conductive materials.

[0029] <<Composition>> Here, polymer X, as described above, comprises at least nitrile group-containing monomer units and aliphatic conjugated diene monomer units and / or alkylene structural units. Polymer X may also contain structural units other than nitrile group-containing monomer units, aliphatic conjugated diene monomer units, and alkylene structural units (other structural units).

[0030] [Nitrile group-containing monomer unit] Examples of nitrile group-containing monomers that can form nitrile group-containing monomer units include α,β-ethylenically unsaturated nitrile monomers. Specifically, the α,β-ethylenically unsaturated nitrile monomer is not particularly limited as long as it is an α,β-ethylenically unsaturated compound having a nitrile group, but examples include acrylonitrile; α-halogenoacrylonitriles such as α-chloroacrylonitrile and α-bromoacrylonitrile; and α-alkylacrylonitriles such as methacrylonitrile and α-ethylacrylonitrile. Note that one type of nitrile group-containing monomer may be used alone, or two or more types may be used in any ratio. Among these, acrylonitrile is preferred.

[0031] The content of nitrile group-containing monomer units in polymer X is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, particularly preferably 35% by mass or more, preferably 50% by mass or less, and more preferably 40% by mass or less, based on 100% by mass of all structural units in polymer X. If the content of nitrile group-containing monomer units in polymer X is 10% by mass or more, the time-dependent stability of the electrode slurry can be improved, and if it is 50% by mass or less, the increase in internal resistance after the electrochemical element cycle can be further suppressed.

[0032] [Aliphatic conjugated diene monomer units and alkylene structural units] Examples of aliphatic conjugated diene monomers that can form aliphatic conjugated diene monomer units include conjugated diene compounds having four or more carbon atoms, such as 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-ethyl-1,3-butadiene, and 1,3-pentadiene. These may be used individually or in combination of two or more in any ratio. Among these, 1,3-butadiene is preferred.

[0033] The alkylene structural unit may be linear or branched, but from the viewpoint of improving the dispersibility of the conductive material dispersion while further suppressing the increase in internal resistance after the electrochemical element cycle, it is preferable that the alkylene structural unit be linear, i.e., a linear alkylene structural unit. Furthermore, the number of carbon atoms in the alkylene structural unit is 4 or more (i.e., the general formula -C described above). n H 2n It is preferable that n is an integer greater than or equal to 4.

[0034] Here, the method for introducing alkylene structural units into polymer X is not particularly limited, but for example, the following methods (1) and (2): (1) A method for converting aliphatic conjugated diene monomer units into alkylene structural units by preparing a polymer from a monomer composition containing an aliphatic conjugated diene monomer and hydrogenating the polymer. (2) Method for preparing a polymer from a monomer composition containing a 1-olefin monomer. These are some examples. Among these, method (1) is preferred because it facilitates the production of polymer X.

[0035] In method (1), the aliphatic conjugated diene monomers that can be used are those described above as "aliphatic conjugated diene monomers that can form aliphatic conjugated diene monomer units". Among these, 1,3-butadiene is preferred. That is, the alkylene structural unit is preferably a structural unit obtained by hydrogenating an aliphatic conjugated diene monomer unit (aliphatic conjugated diene hydride unit), and more preferably a structural unit obtained by hydrogenating a 1,3-butadiene monomer unit (1,3-butadiene hydride unit). Examples of 1-olefin monomers include ethylene, propylene, and 1-butene. Furthermore, when forming alkylene structural units, aliphatic conjugated diene monomers and 1-olefin monomers may be used individually, or two or more may be used in any ratio.

[0036] Here, as described above, polymer X only needs to contain at least one of aliphatic conjugated diene monomer units and alkylene structural units. That is, polymer X may contain alkylene structural units but not aliphatic conjugated diene monomer units, or it may contain aliphatic conjugated diene monomer units but not alkylene structural units, or it may contain both aliphatic conjugated diene monomer units and alkylene structural units. However, from the viewpoint of improving the dispersibility of the conductive material dispersion while further suppressing the increase in internal resistance after the electrochemical element cycle, it is preferable that polymer X contains at least alkylene structural units among aliphatic conjugated diene monomer units and alkylene structural units, and it is more preferable that it contains both aliphatic conjugated diene monomer units and alkylene structural units.

[0037] Furthermore, the total content of aliphatic conjugated diene monomer units and alkylene structural units in polymer X is preferably 30% by mass or more, more preferably 50% by mass or more, even more preferably 60% by mass or more, particularly preferably 65% ​​by mass or more, preferably 80% by mass or less, more preferably 75% by mass or less, and even more preferably 70% by mass or less, based on the total content of all structural units in polymer X being 100% by mass. If the total content of aliphatic conjugated diene monomer units and alkylene structural units in polymer X is 30% by mass or more, the increase in internal resistance after the electrochemical element cycle can be further suppressed, and if it is 80% by mass or less, the time-dependent stability of the electrode slurry can be improved.

[0038] [Other structural units] Other structural units are not particularly limited, but include, for example, (meth)acrylic acid ester monomer units, aromatic-containing monomer units, and hydrophilic group-containing monomer units. Polymer X may contain one other repeating unit, or two or more other repeating units. In this invention, "(meth)acrylic" means acrylic and / or methacrylic.

[0039] Examples of (meth)acrylic acid ester monomers that can form (meth)acrylic acid ester monomer units include methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, t-butyl acrylate, isobutyl acrylate, n-pentyl acrylate, isopentyl acrylate, hexyl acrylate, heptyl acrylate, octyl acrylate, 2-ethylhexyl acrylate, nonyl acrylate, decyl acrylate, lauryl acrylate, n-tetradecyl acrylate, stearyl acrylate, and other acrylates. Examples include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, n-pentyl methacrylate, isopentyl methacrylate, hexyl methacrylate, heptyl methacrylate, octyl methacrylate, 2-ethylhexyl methacrylate, nonyl methacrylate, decyl methacrylate, lauryl methacrylate, n-tetradecyl methacrylate, and stearyl methacrylate. Note that (meth)acrylic acid monomers may be used individually or in combination of two or more in any ratio.

[0040] Examples of aromatic monomers that can form aromatic monomer units include aromatic monovinyl monomers such as styrene, α-methylstyrene, pt-butylstyrene, butoxystyrene, vinyltoluene, chlorostyrene, and vinylnaphthalene. The aromatic monomers may be used individually or in combination of two or more in any ratio.

[0041] Examples of hydrophilic group-containing monomer units include carboxylic acid group-containing monomer units, sulfonic acid group-containing monomer units, phosphate group-containing monomer units, and hydroxyl group-containing monomer units. In other words, examples of hydrophilic group-containing monomers that can form hydrophilic group-containing monomer units include carboxylic acid group-containing monomers, sulfonic acid group-containing monomers, phosphate group-containing monomers, and hydroxyl group-containing monomers. Note that a single type of hydrophilic group-containing monomer may be used alone, or two or more types may be used in any ratio.

[0042] Examples of monomers containing carboxylic acid groups include monocarboxylic acids and their derivatives, dicarboxylic acids and their acid anhydrides, and their derivatives. Examples of monocarboxylic acids include acrylic acid, methacrylic acid, and crotonic acid. Examples of monocarboxylic acid derivatives include 2-ethylacrylic acid, isocrotonic acid, α-acetoxyacrylic acid, β-trans-aryloxyacrylic acid, α-chloro-β-E-methoxyacrylic acid, and β-diaminoacrylic acid. Examples of dicarboxylic acids include maleic acid, fumaric acid, and itaconic acid. Examples of dicarboxylic acid derivatives include methyl maleic acid, dimethyl maleic acid, phenyl maleic acid, chloro maleic acid, dichloro maleic acid, fluoromaleic acid, and maleic acid esters such as methyl allyl maleate, diphenyl maleate, nonyl maleate, decyl maleate, dodecyl maleate, octadecyl maleate, and fluoroalkyl maleate. Examples of dicarboxylic acid acid anhydrides include maleic anhydride, acrylic anhydride, methyl maleic anhydride, and dimethyl maleic anhydride. Furthermore, as monomers having a carboxylic acid group, acid anhydrides that generate a carboxyl group by hydrolysis can also be used. Other examples include monoesters and diesters of α,β-ethylenically unsaturated polycarboxylic acids such as monoethyl maleate, diethyl maleate, monobutyl maleate, dibutyl maleate, monoethyl fumarate, diethyl fumarate, monobutyl fumarate, dibutyl fumarate, monocyclohexyl fumarate, dicyclohexyl fumarate, monoethyl itaconate, diethyl itaconate, monobutyl itaconate, and dibutyl itaconate.

[0043] Examples of monomers containing sulfonic acid groups include vinyl sulfonic acid, methyl vinyl sulfonic acid, (meth)allyl sulfonic acid, styrene sulfonic acid, ethyl (meth)acrylate-2-sulfonate, 2-acrylamido-2-methylpropanesulfonic acid, and 3-alyloxy-2-hydroxypropanesulfonic acid. In this invention, "(meth)allyl" means allyl and / or metallyl.

[0044] Examples of phosphate-containing monomers include 2-(meth)acryloyloxyethyl phosphate, methyl-2-(meth)acryloyloxyethyl phosphate, and ethyl-(meth)acryloyloxyethyl phosphate. In this invention, "(meth)acryloyl" means acryloyl and / or methacryloyl.

[0045] Examples of hydroxyl group-containing monomers include ethylenically unsaturated alcohols such as (meth)allyl alcohol, 3-buten-1-ol, and 5-hexen-1-ol; and alkanol esters of ethylenically unsaturated carboxylic acids such as 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl methacrylate, di-2-hydroxyethyl maleate, di-4-hydroxybutyl maleate, and di-2-hydroxypropyl itaconate; general formula: CH2=CR A -COO-(C k H 2k O) m -H(where m is an integer from 2 to 9, k is an integer from 2 to 4, R APolyalkylene glycols represented by (where represents hydrogen or a methyl group) and (meth)acrylic acid esters; mono(meth)acrylic acid esters of dihydroxy esters of dicarboxylic acids such as 2-hydroxyethyl-2'-(meth)acryloyl oxyphthalate and 2-hydroxyethyl-2'-(meth)acryloyl oxysuccinate; vinyl ethers such as 2-hydroxyethyl vinyl ether and 2-hydroxypropyl vinyl ether; alkyl groups such as (meth)allyl-2-hydroxyethyl ether, (meth)allyl-2-hydroxypropyl ether, (meth)allyl-3-hydroxypropyl ether, (meth)allyl-2-hydroxybutyl ether, (meth)allyl-3-hydroxybutyl ether, (meth)allyl-4-hydroxybutyl ether, and (meth)allyl-6-hydroxyhexyl ether Examples include mono(meth)allyl ethers of alkylene glycols; polyoxyalkylene glycol mono(meth)allyl ethers such as diethylene glycol mono(meth)allyl ether and dipropylene glycol mono(meth)allyl ether; mono(meth)allyl ethers of halogen and hydroxy-substituted (poly)alkylene glycols such as glycerin mono(meth)allyl ether, (meth)allyl-2-chloro-3-hydroxypropyl ether, and (meth)allyl-2-hydroxy-3-chloropropyl ether; mono(meth)allyl ethers of polyhydric phenols such as eugenol and isoeugenol and their halogen-substituted derivatives; and (meth)allyl thioethers of alkylene glycols such as (meth)allyl-2-hydroxyethyl thioether and (meth)allyl-2-hydroxypropyl thioether.

[0046] Furthermore, the content of other structural units in polymer X is preferably 30% by mass or less, and more preferably 10% by mass or less, with the total content of structural units in polymer X being 100% by mass. If the content of other structural units is 30% by mass or less, the viscosity reduction effect of the binder composition is enhanced in relation to the nitrogen compound described later, and the initial viscosity of the dispersion when preparing the conductive material dispersion can be reduced. In other words, the dispersibility of the conductive material dispersion can be improved. Also, if the content of other structural units is 30% by mass or less, the time-dependent stability of the electrode slurry can be improved. Needless to say, polymer X may not contain other structural units. In other words, the content of other structural units in polymer X may be 0% by mass.

[0047] <<Properties>> Here, polymer X is not particularly limited, but preferably has the following properties.

[0048] [Sulfur content] The sulfur content of polymer X is preferably 500 ppm by mass or more, more preferably 1,000 ppm by mass or more, even more preferably 3,000 ppm by mass or more, particularly preferably 4,000 ppm by mass or more, preferably 20,000 ppm by mass or less, more preferably 10,000 ppm by mass or less, even more preferably 8,000 ppm by mass or less, and particularly preferably 6,000 ppm by mass or less. A sulfur content of 500 ppm by mass or more in polymer X suppresses the formation of structural viscosity in the conductive material dispersion, thereby lowering the initial TI value and improving the dispersibility of the conductive material dispersion. Furthermore, it is presumed that the inclusion of sulfur atoms in the molecule of polymer X enhances its oxidation resistance, and a sulfur content of 500 ppm by mass or more in polymer X further suppresses the increase in internal resistance after the electrochemical element cycle. On the other hand, if the sulfur content of polymer X is 20,000 ppm by mass or less, the dispersibility of the conductive material dispersion can be improved by suppressing the formation of structural viscosity in the conductive material dispersion and lowering the initial TI value of the dispersion. Furthermore, the time-dependent stability of the electrode slurry can be improved. Furthermore, the amount of sulfur contained in polymer X can be controlled, for example, based on the amount of a compound (molecular weight adjuster) containing a sulfur-containing group, such as a mercapto group, that is added during polymerization.

[0049] [Iodine value] The polymer X preferably has an iodine value of 100 mg / 100 mg or less, more preferably 80 mg / 100 mg or less, even more preferably 70 mg / 100 mg or less, and particularly preferably 50 mg / 100 mg or less. If the iodine value of polymer X is 100 mg / 100 mg or less, the dispersibility of the conductive material dispersion and the time-dependent stability of the electrode slurry can be improved, while further suppressing the increase in internal resistance after the electrochemical element cycle. The lower limit of the iodine value of polymer X is not particularly limited, but for example, it can be 0.1 mg / 100 mg or more, 1 mg / 100 mg or more, or 5 mg / 100 mg or more. In this invention, the "iodine value" can be measured using the method described in the examples.

[0050] [Weight average molecular weight] The weight-average molecular weight of polymer X is preferably greater than 1,000, more preferably 5,000 or more, even more preferably 10,000 or more, even more preferably 20,000 or more, particularly preferably 25,000 or more, preferably 300,000 or less, preferably 250,000 or less, more preferably 100,000 or less, even more preferably 70,000 or less, and particularly preferably 50,000 or less. If the weight-average molecular weight of polymer X is greater than 1,000, the viscosity reduction effect of the binder composition in relation to the nitrogen compound described later can be increased, thereby improving the dispersibility of the conductive material dispersion. On the other hand, if the weight-average molecular weight of polymer X is 300,000 or less, the dispersibility of the conductive material dispersion can be improved by lowering the initial TI value of the dispersion, etc. Furthermore, the increase in internal resistance after the electrochemical element cycle can be further suppressed.

[0051] <<Preparation method>> The method for preparing polymer X is not particularly limited. Polymer X can be produced, for example, by polymerizing a monomer composition containing the above-mentioned monomers in an aqueous solvent and optionally performing hydrogenation (hydrogenation). The content ratio of each monomer in the monomer composition can be determined in accordance with the content ratio of each structural unit in polymer X. Furthermore, there are no particular restrictions on the polymerization method; any method such as solution polymerization, suspension polymerization, bulk polymerization, or emulsion polymerization can be used. Addition polymerization, such as ionic polymerization, radical polymerization, or living radical polymerization, can be used as the polymerization reaction. As for the polymerization initiator, known polymerization initiators, such as redox polymerization initiators containing iron-based compounds, can be used.

[0052] Here, the molecular weight (particularly the weight-average molecular weight) of the polymer X obtained during polymerization can be adjusted by using a molecular weight adjusting agent. Examples of such molecular weight adjusting agents include compounds having sulfur-containing groups such as mercapto groups. Examples of compounds having a mercapto group that can be used as molecular weight modifiers include compounds having 8 to 12 carbon atoms such as octyl mercaptan, 2,2,4,6,6-pentamethyl-4-heptanethiol, 2,4,4,6,6-pentamethyl-2-heptanethiol, 2,3,4,6,6-pentamethyl-2-heptanethiol, 2,3,4,6,6-pentamethyl-3-heptanethiol, t-dodecyl mercaptan, and n-dodecyl mercaptan; and compounds having a mercapto group such as 2,2,4,6,6-pentamethyl-4-octanthiol, 2,2,4,6,6,8,8-heptamethyl-4-nonanthiol, bis(2-mercaptoethyl) sulfide, methyl 3-mercaptopropionate, and 1-butanethiol.

[0053] Furthermore, when polymer X is produced by the method described in (1) above, radical polymerization using a redox polymerization initiator containing an iron-based compound can be used as the polymerization method for the hydrogenated polymer (i.e., a polymer containing nitrile group-containing monomer units and aliphatic conjugated diene monomer units). Here, the redox polymerization initiator containing an iron-based compound is not particularly limited, and for example, a combination of cumene hydroperoxide as a polymerization initiator and ferrous sulfate and / or monosodium iron ethylenediaminetetraacetate as an iron-based compound can be used. Furthermore, when polymer X is produced by the method described in (1) above, after emulsion polymerization, it can be coagulated with a coagulant and recovered, and the recovered material can be hydrogenated (optionally after carrying out the "double decomposition reaction" described later). Furthermore, hydrogenation can be carried out using known hydrogenation methods such as oil-layer hydrogenation or aqueous-layer hydrogenation. In addition, any known selective hydrogenation catalyst can be used as the catalyst for hydrogenation, including palladium-based and rhodium-based catalysts. Two or more of these may be used in combination.

[0054] Note that the hydrogenation of the polymer may be carried out using, for example, the method described in Patent No. 4509792. Specifically, the hydrogenation of the polymer may be carried out after performing a metathesis reaction of the polymer in the presence of a catalyst and a co-olefin. Here, as the catalyst for the metathesis reaction, a known ruthenium-based catalyst can be used. Among them, as the catalyst for the metathesis reaction, it is preferable to use a Grubbs catalyst such as bis(tricyclohexylphosphine)benzylidene ruthenium dichloride, 1,3-bis(2,4,6-trimethylphenyl)-2-(imidazolidinylidene)(dichlorophenylmethylene)(tricyclohexylphosphine)ruthenium. Further, as the co-olefin, olefins having 2 to 16 carbon atoms such as ethylene, isobutane, and 1-hexane can be used. Further, as the hydrogenation catalyst when performing hydrogenation after the metathesis reaction, a known homogeneous hydrogenation catalyst such as Wilkinson catalyst ((PPh3)3RhCl) can be used.

[0055] <Nitrogen compound> The nitrogen compound is an organic compound containing a nitrogen atom (however, excluding NMP).

[0056] (<HSP distance (R A )> Here, in the binder composition of the present invention, the HSP distance (R A ) between the nitrogen compound and the above-described polymer X needs to be 10.0 MPa 1 / 2 or less. The HSP distance (R A ) is 10.0 MPa 1 / 2The affinity between nitrogen compounds and polymer X is high for the following reasons. Therefore, it is presumed that using nitrogen compounds in the preparation of the binder composition weakens the interactions between the polymer chains constituting polymer X, and thus the viscosity of the binder composition can be reduced by using nitrogen compounds (viscosity reduction effect). By preparing a conductive material dispersion and / or electrode slurry using a binder composition with sufficiently reduced viscosity, it becomes possible to form an electrode composite layer in which components such as fibrous conductive materials are well dispersed. As a result, the increase in internal resistance after the electrochemical element cycle can be suppressed. Furthermore, from the perspective of achieving the above-mentioned effects even more effectively, the HSP distance (R A ) is 8.0 MPa 1 / 2 Preferably, the following is true: 6.0 MPa 1 / 2 It is more preferable that the following conditions be met: 4.6 MPa 1 / 2 The following is even more preferable. Also, the HSP distance (R A The lower limit of ) is not particularly limited, but for example, 0.1 MPa 1 / 2 That's all.

[0057] Here, the HSP distance (R A As can be seen from equation (A) above, the Hansen solubility parameter (HSP) of nitrogen compounds is N ) and the Hansen solubility parameter (HSP) of polymer X. X This can be adjusted by controlling the polarity term, dispersion term, and hydrogen bonding term that constitute each of these terms. Hansen solubility parameter (HSP) of nitrogen compounds N The Hansen solubility parameter (HSP) of polymer X can be changed by selecting the type of nitrogen compound. X This can be controlled by changing the type and proportion of monomers used in the preparation of polymer X, as well as the weight-average molecular weight, iodine value, and sulfur content of polymer X.

[0058] <<Polar term δ p1 >> Hansen solubility parameter (HSP) of nitrogen compounds N) in the polar term δ p1 14.0 MPa or less 1 / 2 Preferably, the following is true: 11.0 MPa 1 / 2 The following is more preferable: Polarity term δ p1 14.0 MPa 1 / 2 Under the following conditions, the acid dissociation constant of the nitrogen compound will not increase excessively, and the nitrogen compound will be able to fully exert the viscosity-reducing effect described above. Therefore, it is possible to further suppress the increase in internal resistance after the electrochemical element cycle while improving the dispersibility of the conductive material dispersion and the time-dependent stability of the electrode slurry. Note the polar term δ p1 The lower limit is not particularly limited, but for example, 5.0 MPa 1 / 2 That's all.

[0059] <<Molecular weight>> Here, the nitrogen compound must have a molecular weight of 1,000 or less, preferably 50 or more, more preferably 60 or more, even more preferably 70 or more, particularly preferably 80 or more, preferably 600 or less, more preferably 300 or less, even more preferably 200 or less, and particularly preferably 130 or less. If the molecular weight of the nitrogen compound exceeds 1,000, the viscosity reduction effect cannot be sufficiently obtained, and the increase in internal resistance after the electrochemical element cycle cannot be suppressed. In addition, the time-dependent stability of the electrode slurry decreases. On the other hand, if the molecular weight of the nitrogen compound is 50 or more, the viscosity reduction effect described above can be sufficiently obtained, and the increase in internal resistance after the electrochemical element cycle can be further suppressed while improving the dispersibility of the conductive material dispersion.

[0060] <<Structure>> Furthermore, it is preferable that the nitrogen compound has a cyclic amidine structure. Nitrogen compounds having a cyclic amidine structure are particularly excellent in viscosity reduction, and by using a nitrogen compound having a cyclic amidine structure, the dispersibility of the conductive material dispersion can be improved by reducing the initial viscosity and initial TI value of the dispersion, and the increase in internal resistance after the electrochemical element cycle can be further suppressed. Furthermore, from the viewpoint of improving the dispersibility of the conductive material dispersion while further suppressing the increase in internal resistance after the electrochemical element cycle, it is preferable that the nitrogen compound does not have aromatic rings such as benzene rings.

[0061] <<Specific Examples>> Here, suitable specific examples of nitrogen compounds include 2-methyl-2-imidazoline, 2-propyl-2-imidazoline, diazabicycloundecene (DBU), diazabicyclononene (DBN), and 1,5,7-triazabicyclo[4.4.0]deca-5-ene (TBD). Note that a single nitrogen compound may be used, or two or more may be used in any ratio. As for the nitrogen compound, 2-methyl-2-imidazoline and DBU are preferred, and 2-methyl-2-imidazoline is more preferred, from the viewpoint of improving the dispersibility of the conductive material dispersion and the time-dependent stability of the electrode slurry, while further suppressing the increase in internal resistance after the electrochemical element cycle.

[0062] <<Mixing ratio>> In the binder composition of the present invention, the mixing ratio of polymer X and nitrogen compound is not particularly limited, but it is preferable that the proportion of the nitrogen compound in the total mass of polymer X and nitrogen compound be 0.1% by mass or more, more preferably 1% by mass or more, more preferably 3% by mass or more, even more preferably 5% by mass or more, preferably 40% by mass or less, more preferably 30% by mass or less, and even more preferably 20% by mass or less. If the proportion of the nitrogen compound in the total mass of polymer X and nitrogen compound is 0.1% by mass or more, the viscosity reduction effect can be sufficiently exhibited, and if it is 40% by mass or less, the time-dependent stability of the electrode slurry can be improved. Furthermore, if the proportion of the nitrogen compound in the total mass of polymer X and nitrogen compound is 0.1% by mass or more and 40% by mass or less, the dispersibility of the conductive material dispersion can be improved while further suppressing the increase in internal resistance after the electrochemical element cycle.

[0063] <Other ingredients> The binder composition of the present invention may contain other components besides polymer X, NMP, and nitrogen compounds, and these are not particularly limited. Examples include binders, reinforcing agents, leveling agents, viscosity modifiers, and electrolyte additives other than polymer X, which will be described later. These are not particularly limited as long as they do not affect the battery reaction, and known ones, such as those described in International Publication No. 2012 / 115096, can be used. Furthermore, the binder composition of the present invention may contain organic solvents that are neither NMP nor nitrogen compounds. These other components may be used individually or in combination of two or more components in any ratio.

[0064] <Method for preparing a binder composition> The method for preparing the binder composition of the present invention is not particularly limited, and can be obtained by mixing the above-mentioned components using a known mixing device such as a disper.

[0065] (Conductive material dispersion) The conductive material dispersion of the present invention is a composition comprising a fibrous conductive material and the binder composition described above. That is, the conductive material dispersion of the present invention contains a fibrous conductive material, the polymer X described above, NMP, and the nitrogen compound described above, and optionally contains conductive materials other than the fibrous conductive material (other conductive materials) and / or other components. Here, in the conductive material dispersion of the present invention, similar to the binder composition of the present invention described above, the Hansen solubility parameter (HSP) of the nitrogen compound is used. N ) and the Hansen solubility parameter (HSP) of polymer X. X ) and the HSP distance (R A ) is 10.0 MPa 1 / 2 The following applies: Furthermore, since the conductive material dispersion of the present invention contains the binder composition of the present invention, by using the conductive material dispersion of the present invention, electrodes can be fabricated that can suppress the increase in internal resistance after the electrochemical element cycle. The conductive material dispersion of the present invention is an intermediate product for preparing the electrode slurry of the present invention described later and usually does not contain an electrode active material. Further, the polymer X and the nitrogen compound contained in the conductive material dispersion of the present invention are derived from the binder composition of the present invention, and their preferred abundance ratios are the same as those of the binder composition of the present invention.

[0066] <Fibrous conductive material> Examples of the fibrous conductive material include fibrous carbon materials such as carbon nanotubes (single-walled CNT, multi-walled CNT), carbon nanohorns, carbon nanofibers, and mild carbon fibers. The fibrous conductive material may be used alone or in combination of two or more kinds at an arbitrary ratio. Among these, from the viewpoint of further suppressing the increase in internal resistance after cycling of the electrochemical device, carbon nanotubes and carbon nanofibers are preferred, and carbon nanotubes are more preferred. Further, the fibrous conductive material is preferably of a bundle type. By using a bundle-type fibrous conductive material, it is possible to improve the dispersibility of the conductive material dispersion and further suppress the increase in internal resistance after cycling of the electrochemical device.

[0067] <<HSP distance (R B )>> In the conductive material dispersion of the present invention, the Hansen solubility parameter (HSP N ) of the nitrogen compound and the Hansen solubility parameter (HSP F ) of the fibrous conductive material, the HSP distance (R B ) is preferably 10.0 MPa 1 / 2 or less, more preferably 8.0 MPa 1 / 2 or less, and even more preferably 6.0 MPa 1 / 2 or less. If the HSP distance (R B ) between the nitrogen compound and the fibrous conductive material is 10.0 MPa 1 / 2 or less, the dispersibility of the conductive material dispersion is improved, and the increase in internal resistance after cycling of the electrochemical device can be further suppressed. The reason for this is not clear, but the HSP distance (R B) is 10.0 MPa 1 / 2 Since it is as follows, it is presumed that the nitrogen compound that can interact well with the fibrous conductive material modifies the surface of the fibrous conductive material (surface modification effect), and the polymer X can be adsorbed well on the fibrous conductive material through the nitrogen compound. Also, the lower limit of the HSP distance (R B ) is not particularly limited, but for example, it is 0.1 MPa 1 / 2 or more.

[0068] In the present invention, the "Hansen solubility parameter (HSP F ) of the fibrous conductive material" is composed of a polar term δ p3 , a dispersion term δ d3 , and a hydrogen bond term δ h3 . Here, in the present invention, "δ p3 ", "δ d3 ", and "δ h3 " can be specified using the method described in the examples. And in the present invention, the "HSP distance (R B )" is represented by the following formula (B): HSP distance (R B ) = {(δ p1 - δ p3 ) 2 + 4 × (δ d1 - δ d3 ) 2 + (δ h1 - δ h3 ) 2} 1 / 2 ···(B) It can be calculated using this.

[0069] Note that the HSP distance (R B ) can be adjusted by controlling the polar term, dispersion term, and hydrogen bond term that respectively constitute the Hansen solubility parameter (HSP N ) of the nitrogen compound and the Hansen solubility parameter (HSP X ) of the fibrous conductive material, as can be seen from the above formula (B). The Hansen solubility parameter (HSP NRegarding , it can be changed by selecting the type of nitrogen compound. Also, regarding the Hansen solubility parameter (HSP F ) of the fibrous conductive material, it can be controlled by changing the type of fibrous conductive material (the material of the main component), the surface acid amount, the surface base amount, and the D / G ratio, etc. of the fibrous conductive material.

[0070] <<D / G ratio>> When using a fibrous carbon material as the fibrous conductive material, from the viewpoint of improving the dispersibility of the conductive material dispersion liquid by reducing the initial TI value of dispersion, etc., and increasing the stability over time of the electrode slurry, while further suppressing the increase in internal resistance after cycling of the electrochemical device, the D / G ratio of the fibrous carbon material is preferably 2.0 or less, and more preferably 1.5 or less. Here, the D / G ratio is an index generally used to evaluate the quality of carbon materials. In the Raman spectrum of the carbon material measured by a Raman spectrometer, vibration modes called the G band (around 1600 cm -1 -1) and the D band (around 1350 cm -1 -1) are observed. The G band is a vibration mode derived from the hexagonal lattice structure of graphite, and the D band is a vibration mode derived from amorphous sites. Therefore, it can be said that a carbon material with a smaller peak intensity ratio of the D band to the G band (D / G ratio) has fewer amorphous sites, that is, fewer defect structures. And according to the study of the present inventors, if a fibrous carbon material with fewer defect structures is used, the dispersibility of the conductive material dispersion liquid is improved, such as by reducing the initial TI value of dispersion, etc. Furthermore, due to the improvement in the dispersibility of the conductive material dispersion liquid, it has been clarified that the stability over time of the electrode slurry is improved and the increase in internal resistance after cycling of the electrochemical device can be further suppressed. The reason why the use of a fibrous carbon material with fewer defect structures improves the dispersibility of the conductive material dispersion liquid is not clear, but it is presumed that a fibrous carbon material with fewer defect structures can obtain a good surface modification effect by the above-mentioned nitrogen compound, and the polymer X can be adsorbed better on the fibrous carbon material through the nitrogen compound. The lower limit of the D / G ratio of the fibrous carbon material is not particularly limited, but is, for example, 0.01 or more. The D / G ratio of the fibrous carbon material can be controlled by changing conditions such as those during the preparation of the fibrous carbon material.

[0071] <<BET specific surface area>> The fibrous conductive material preferably has a BET specific surface area of 100 m 2 / g or more, more preferably 150 m 2 / g or more, still more preferably 200 m 2 / g or more, and preferably 1,000 m 2 / g or less, more preferably 500 m 2 / g or less, still more preferably 400 m 2 / g or less. If the BET specific surface area is within the above-described range, while improving the dispersibility of the conductive material dispersion, it is possible to further suppress an increase in the internal resistance after cycling of the electrochemical device. In the present invention, the "BET specific surface area" of the fibrous conductive material can be measured using the method described in the examples.

[0072] <<Amount of surface acid>> The fibrous conductive material preferably has an amount of surface acid of 0.01 mmol / g or more, preferably 0.20 mmol / g or less, and more preferably 0.15 mmol / g or less. If the amount of surface acid of the fibrous conductive material is 0.01 mmol / g or more, it is presumed that the amount of residual base components attached to the surface of the fibrous conductive material is reduced, and the stability of the electrode slurry over time can be enhanced. On the other hand, if the amount of surface acid of the fibrous conductive material is 0.20 mmol / g or less, it is presumed that the amount of residual acid components attached to the surface of the fibrous conductive material is reduced to suppress side reactions in the electrochemical device, and an increase in the internal resistance after cycling of the electrochemical device can be further suppressed. In the present invention, the "amount of surface base" and the "amount of surface acid" of the carbon nanotube can be measured using the method described in the examples.

[0073] <<Surface acid content / Surface base content>> Furthermore, the ratio of the amount of surface acid to the amount of surface base (amount of surface acid / amount of surface base) of the fibrous conductive material is preferably 0.10 or more, more preferably 0.15 or more, even more preferably 0.20 or more, preferably 2.5 or less, more preferably 2.0 or less, and even more preferably 1.5 or less. It is presumed that if the amount of surface acid / amount of surface base of the fibrous conductive material is 0.10 or more, the amount of residual base components adhering to the surface of the fibrous conductive material is reduced, thereby improving the time-dependent stability of the electrode slurry. On the other hand, if the amount of surface acid / amount of surface base of the fibrous conductive material is 2.5 or less, it is presumed that the amount of residual acid components adhering to the surface of the fibrous conductive material is reduced, thereby suppressing side reactions in the electrochemical element, and further suppressing the increase in internal resistance after the electrochemical element cycle.

[0074] <<Preparation method>> The method for preparing the fibrous conductive material is not particularly limited. Below, we will describe the preparation method using CNTs in which the surface acid content and the surface acid content / surface base content are within the preferred range described above as an example. CNTs in which the surface acid content and the surface acid content / surface base content are within the preferred range described above can be prepared by following three steps: an acid treatment step of raw material CNTs, a base treatment step of the acid-treated raw material CNTs, and a washing step of the base-treated raw material CNTs.

[0075] [Acid treatment process] In the acid treatment process, the raw material CNTs are subjected to acid treatment. The raw material CNTs are not particularly limited and can be appropriately selected from known CNTs according to the desired surface-treated CNT properties (number of layers, D / G ratio, BET specific surface area, etc.).

[0076] The method of acid treatment is not particularly limited as long as it allows the raw material CNTs to come into contact with an acid, but a preferred method is to immerse the raw material CNTs in an acid treatment solution (an aqueous solution of acid). The acid contained in the acid treatment solution is not particularly limited, but examples include nitric acid, sulfuric acid, and hydrochloric acid. These can be used individually or in combination of two or more. Among these, nitric acid and sulfuric acid are preferred.

[0077] The immersion time for the raw material CNTs in the acid treatment solution is preferably 1 minute or more, more preferably 10 minutes or more, even more preferably 30 minutes or more, particularly preferably 50 minutes or more, preferably 120 minutes or less, more preferably 100 minutes or less, and even more preferably 80 minutes or less. If the immersion time is 1 minute or more, the surface acid content of the surface-treated CNTs can be increased, and if it is 120 minutes or less, the surface acid content of the surface-treated CNTs will not become excessively high, and the production efficiency of the surface-treated CNTs will be sufficiently ensured.

[0078] Furthermore, the temperature at which the raw material CNTs are immersed in the acid treatment solution (immersion temperature) is preferably 20°C or higher, more preferably 40°C or higher, preferably 80°C or lower, and more preferably 70°C or lower. If the immersion temperature is within the above range, the surface acid content of the resulting surface-treated CNTs can be appropriately increased.

[0079] After the immersion described above, the acid-treated CNTs (CNTs that have undergone the acid treatment process) can be recovered from a mixture of the acid treatment solution by known methods such as filtration. The recovered acid-treated CNTs may be washed with water if necessary.

[0080] [Base treatment process] In the base treatment process, the acid-treated CNTs obtained through the acid treatment process described above are subjected to base treatment.

[0081] The method of base treatment is not particularly limited as long as it allows the acid-treated CNTs to come into contact with a base, but a preferred method is to immerse the acid-treated CNTs in a base treatment solution (an aqueous solution of a base). The bases included in the base treatment solution are not particularly limited, but examples include lithium hydroxide, ammonium chloride, sodium bicarbonate, and sodium hydroxide. These can be used individually or in combination of two or more. Among these, lithium hydroxide and ammonium chloride are preferred, with lithium hydroxide being more preferred.

[0082] The immersion time for acid-treated CNTs in the base treatment solution is preferably 10 minutes or more, more preferably 60 minutes or more, even more preferably 80 minutes or more, particularly preferably 90 minutes or more, preferably 240 minutes or less, more preferably 200 minutes or less, and even more preferably 150 minutes or less. If the immersion time is 10 minutes or more, the amount of surface base on the surface-treated CNTs can be increased, and if it is 240 minutes or less, the amount of surface base on the surface-treated CNTs will not increase excessively, and the production efficiency of surface-treated CNTs will be sufficiently ensured.

[0083] Furthermore, the temperature at which the acid-treated CNTs are immersed in the base treatment solution (immersion temperature) is preferably 10°C or higher, more preferably 20°C or higher, preferably 40°C or lower, and more preferably 27°C or lower. If the immersion temperature is within the above range, the amount of surface base in the resulting surface-treated CNTs can be appropriately increased.

[0084] [Washing process] In the washing process, the raw material CNTs (acid-base treated CNTs) obtained through the acid treatment and base treatment processes described above are washed. This washing removes excess acid and base components (especially base components) adhering to the surface of the acid-base treated CNTs, thereby obtaining surface-treated CNTs with predetermined properties.

[0085] Furthermore, while there are no particular limitations on the method for washing acid-base treated CNTs, washing with water is preferred. For example, the acid-base treated CNTs can be recovered from a mixture of acid-base treated CNTs and a base treatment solution by known methods such as filtration, and the acid-base treated CNTs can be washed with water. At this time, the extent to which acid and base components have been removed can be estimated by measuring the electrical conductivity of the water used to wash the acid-base treated CNTs (wash water). After the cleaning process described above, surface-treated CNTs can be obtained by removing any water adhering to the surface by drying, if necessary.

[0086] Furthermore, the surface acid content and surface base content of surface-treated CNTs can be adjusted by changing the conditions of the acid treatment process, base treatment process, and washing process described above. For example, the surface acid content and surface base content of surface-treated CNTs can be adjusted by changing the types of acids and bases contained in the acid treatment solution and base treatment solution used in the acid treatment process and base treatment process, respectively, as well as their concentrations. In addition, the surface acid content of surface-treated CNTs can be increased by increasing the immersion time in the acid treatment process, and the surface base content of surface-treated CNTs can be increased by increasing the immersion time in the base treatment process. Moreover, the surface acid content and surface base content (especially the surface base content) can be adjusted by changing the degree of washing in the washing process.

[0087] <Other conductive materials> Other conductive materials are not particularly limited as long as they have a shape other than fibrous form (e.g., particulate, plate-like), and include carbon black (e.g., acetylene black, Ketjenblack®, Farnest Black, etc.) and graphene. Note that these other conductive materials may be used individually or in combination of two or more types in any ratio.

[0088] The mixing ratio of the fibrous conductive material to other conductive materials used as desired is not particularly limited, but from the viewpoint of ensuring sufficient dispersibility of the conductive material dispersion, it is preferable that the proportion of the mass of the fibrous conductive material to the total mass of the fibrous conductive material and other conductive materials be 50% by mass or more and 100% by mass or less.

[0089] <Binder composition> As the binder composition, the binder composition of the present invention is used, which contains the polymer X described above, the nitrogen compound described above, and NMP, and optionally contains other components.

[0090] Here, when mixing the fibrous conductive material and the binder composition to obtain a conductive material dispersion, the ratio of the fibrous conductive material to the binder composition is not particularly limited. For example, the fibrous conductive material and the binder composition may be mixed in such a ratio that the resulting conductive material dispersion contains, preferably, 5 to 40 parts by mass, more preferably 10 to 30 parts by mass, of polymer X per 100 parts by mass of fibrous conductive material.

[0091] <Method for preparing conductive material dispersion> The method for preparing the conductive material dispersion is not particularly limited. The conductive material dispersion can be prepared by mixing a fibrous conductive material and a binder composition, for example, using a known mixing apparatus. When preparing the conductive material dispersion, other conductive materials may be mixed in addition to the fibrous conductive material and binder composition, and organic solvents such as NMP may also be added.

[0092] (Slurry for electrochemical element electrodes) The electrode slurry of the present invention is a composition comprising an electrode active material and the conductive material dispersion described above. That is, the electrode slurry of the present invention contains at least the electrode active material, the fibrous conductive material described above, the polymer X described above, the nitrogen compound described above, and NMP. Here, the electrode slurry of the present invention preferably contains other binders from the viewpoint of increasing the peel strength of the electrode while further suppressing the increase in internal resistance after the electrochemical element cycle. Furthermore, since the electrode slurry of the present invention contains a conductive material dispersion of the present invention, electrodes formed using this electrode slurry can suppress the increase in internal resistance after the electrochemical element has been cycled. The fibrous conductive material, polymer X, and nitrogen compound contained in the electrode slurry of the present invention are derived from the binder composition and conductive material dispersion liquid of the present invention, and their preferred abundance ratios are the same as those of the binder composition and conductive material dispersion liquid of the present invention.

[0093] <Electrode active material> As the electrode active material (positive electrode active material, negative electrode active material) to be blended in the electrode slurry, known electrode active materials can be used without particular limitation.

[0094] For example, the positive electrode active material used in a lithium ion secondary battery is not particularly limited, but includes metal oxides containing lithium (Li). And as the positive electrode active material, in addition to lithium (Li), a positive electrode active material containing at least one selected from the group consisting of cobalt (Co), nickel (Ni), manganese (Mn), and iron (Fe) is preferable. Such positive electrode active materials include lithium-containing cobalt oxide (LiCoO2), lithium manganate (LiMn2O4), lithium-containing nickel oxide (LiNiO2), lithium-containing composite oxides of Co-Ni-Mn, lithium-containing composite oxides of Ni-Mn-Al, lithium-containing composite oxides of Ni-Co-Al, olivine-type lithium manganese phosphate (LiMnPO4), olivine-type lithium iron phosphate (LiFePO4), Li 1+x Mn 2-x O4 (0 < X < 2) spinel compounds with excess lithium, Li[Ni 0.17 Li 0.2 Co 0.07 Mn 0.56 O2, LiNi 0.5 Mn 1.5 O4 and the like. The positive electrode active material may be used alone or in combination of two or more in any ratio.

[0095] The particle size of the electrode active material is not particularly limited and can be the same as that of the conventionally used electrode active materials. Also, the amount of the electrode active material in the electrode slurry is not particularly limited and can be within the range conventionally used.

[0096] <Conductive material dispersion> As the conductive material dispersion, the conductive material dispersion of the present invention is used, which contains at least the fibrous conductive material described above, the polymer X described above, the nitrogen compound described above, and NMP.

[0097] <Other binding agents> Other binders are not particularly limited, but fluorine-based polymers are preferred. Examples of fluorine-based polymers include polyvinylidene fluoride (PVdF) and polyvinylidene fluoride-hexafluoropropylene (PVdF-HFP) copolymers. One type of fluorine-based polymer may be used alone, or two or more types may be used in any ratio. Among these, polyvinylidene fluoride is preferred from the viewpoint of further increasing the peel strength of the electrode while further suppressing the increase in internal resistance after the electrochemical element cycle.

[0098] Furthermore, from the viewpoint of increasing the peel strength of the electrode while further suppressing the increase in internal resistance after the electrochemical element cycle, the content of other binders in the electrode slurry is preferably 0.1 parts by mass or more, more preferably 0.5 parts by mass or more, preferably 3 parts by mass or less, and more preferably 2 parts by mass or less per 100 parts by mass of electrode active material.

[0099] <Method for preparing electrode slurry> The method for preparing the electrode slurry is not particularly limited. The electrode slurry can be prepared by mixing the electrode active material, a conductive material dispersion, and other optional components such as binders using, for example, a known mixing apparatus. Alternatively, the electrode slurry can be prepared without going through the conductive material dispersion; for example, it may be prepared by mixing the electrode active material, polymer X, nitrogen compound, fibrous conductive material, and NMP all at once.

[0100] (Electrodes for electrochemical devices) The electrode of the present invention comprises an electrode composite layer obtained using the electrode slurry of the present invention described above. More specifically, the electrode of the present invention typically comprises the electrode composite layer on a current collector. Since the electrode composite layer of the electrode of the present invention is formed from the electrode slurry of the present invention described above, it is possible to suppress the increase in internal resistance after the electrochemical element cycle. Here, the electrode composite layer typically consists of the dried product of the electrode slurry of the present invention described above. The electrode composite layer contains at least an electrode active material, a fibrous conductive material, a polymer X, and a nitrogen compound. The components contained in the electrode composite layer are those contained in the electrode slurry of the present invention described above, and the preferred ratio of each component is the same as the preferred ratio of each component in the electrode slurry of the present invention.

[0101] <Current collector> The current collector is made of a material that is electrically conductive and electrochemically durable. The current collector is not particularly limited, and any known current collector can be used. For example, the current collector in the positive electrode of a lithium-ion secondary battery may be made of aluminum or an aluminum alloy. In this case, a combination of aluminum and an aluminum alloy may be used, or a combination of different types of aluminum alloys may be used. Aluminum and aluminum alloys are excellent current collector materials because they are heat-resistant and electrochemically stable.

[0102] <Method of manufacturing electrodes> The method for manufacturing the electrode of the present invention is not particularly limited. For example, the electrode of the present invention can be manufactured by applying the electrode slurry of the present invention described above to at least one surface of a current collector and drying it to form an electrode composite layer. More specifically, the manufacturing method includes the steps of applying the electrode slurry to at least one surface of a current collector (coating step) and drying the electrode slurry applied to at least one surface of the current collector to form an electrode composite layer on the current collector (drying step).

[0103] <<Coating process>> The method for applying the electrode slurry onto the current collector is not particularly limited, and known methods can be used. Specifically, application methods such as the doctor blade method, dip method, reverse roll method, direct roll method, gravure method, extrusion method, and brush application method can be used. In this case, the electrode slurry may be applied to only one side of the current collector or to both sides. The thickness of the slurry film on the current collector before drying after application can be appropriately set according to the thickness of the electrode composite layer obtained after drying.

[0104] <<Drying process>> The method for drying the electrode slurry on the current collector is not particularly limited and known methods can be used, such as drying with hot air, hot air, or low-humidity air, vacuum drying, or drying by irradiation with infrared rays or electron beams. By drying the electrode slurry on the current collector in this way, an electrode composite layer is formed on the current collector, and an electrode comprising the current collector and the electrode composite layer can be obtained.

[0105] Furthermore, after the drying process, the electrode composite layer may be subjected to pressure treatment using a die press or roll press. This pressure treatment allows the electrode composite layer to adhere well to the current collector. Furthermore, if the electrode composite layer contains a curable polymer, the polymer may be cured after the formation of the electrode composite layer.

[0106] (Electrochemical element) The electrochemical element of the present invention comprises the electrodes of the present invention as described above. Furthermore, because the electrochemical element of the present invention is equipped with the electrodes of the present invention, it is possible to suppress an excessive increase in internal resistance after cycling. The electrochemical element of the present invention is, for example, a non-aqueous secondary battery, and is preferably a lithium-ion secondary battery.

[0107] Hereinafter, the configuration of a lithium-ion secondary battery as an example of the electrochemical element of the present invention will be described. This lithium-ion secondary battery comprises a positive electrode, a negative electrode, an electrolyte, and a separator. At least one of the positive electrode and the negative electrode is the electrode of the present invention. That is, in this lithium-ion secondary battery, the positive electrode may be the electrode of the present invention and the negative electrode may be an electrode other than the electrode of the present invention, the positive electrode may be an electrode other than the electrode of the present invention and the negative electrode may be the electrode of the present invention, or both the positive electrode and the negative electrode may be the electrode of the present invention.

[0108] <Electrodes other than the electrode of the present invention> Electrodes that do not fall under the electrodes of the present invention are not particularly limited and any known electrodes can be used.

[0109] <Electrolyte> Typically, an organic electrolyte is used, which is obtained by dissolving a supporting electrolyte in an organic solvent. For example, lithium salts are used as supporting electrolytes. Examples of lithium salts include LiPF6, LiAsF6, LiBF4, LiSbF6, LiAlCl4, LiClO4, CF3SO3Li, C4F9SO3Li, CF3COOLi, (CF3CO)2NLi, (CF3SO2)2NLi, and (C2F5SO2)NLi. Among these, LiPF6, LiClO4, and CF3SO3Li are preferred, with LiPF6 being particularly preferred, because they are easily soluble in the solvent and exhibit a high degree of dissociation. Note that one type of electrolyte may be used alone, or two or more types may be used in any ratio. Generally, the lithium ion conductivity tends to increase as the supporting electrolyte with a higher degree of dissociation is used, so the lithium ion conductivity can be adjusted by the type of supporting electrolyte.

[0110] The organic solvent used in the electrolyte is not particularly limited as long as it can dissolve the supporting electrolyte, but suitable examples include carbonates such as dimethyl carbonate (DMC), ethylene carbonate (EC), diethyl carbonate (DEC), propylene carbonate (PC), butylene carbonate (BC), and methyl ethyl carbonate (EMC); esters such as γ-butyrolactone and methyl formate; ethers such as 1,2-dimethoxyethane and tetrahydrofuran; and sulfur-containing compounds such as sulfolane and dimethyl sulfoxide. A mixture of these solvents may also be used. Among these, carbonates are preferred because they have a high dielectric constant and a wide stable potential range, and a mixture of ethylene carbonate and ethyl methyl carbonate is even more preferred. The concentration of the electrolyte in the electrolyte solution can be adjusted as appropriate. For example, it is preferably 0.5 to 15% by mass, more preferably 2 to 13% by mass, and even more preferably 5 to 10% by mass. In addition, known additives, such as fluoroethylene carbonate or ethyl methyl sulfone, may be added to the electrolyte solution.

[0111] <Separator> The separator is not particularly limited, and for example, those described in Japanese Patent Publication No. 2012-204303 can be used. Among these, a microporous membrane made of polyolefin resin (polyethylene, polypropylene, polybutene, polyvinyl chloride) is preferred because it allows for a thinner overall film thickness of the separator, thereby increasing the ratio of electrode active material in the lithium-ion secondary battery and thus increasing the capacity per unit volume.

[0112] <Manufacturing method for lithium-ion secondary batteries> A lithium-ion secondary battery according to the present invention can be manufactured, for example, by stacking a positive electrode and a negative electrode with a separator in between, winding or folding them as needed according to the battery shape, placing them in a battery container, injecting an electrolyte into the battery container, and sealing it. To prevent pressure rise inside the secondary battery, overcharge and discharge, etc., an overcurrent prevention element such as a fuse or PTC element, expanded metal, lead plates, etc. may be provided as needed. The shape of the secondary battery may be any of the following: coin type, button type, sheet type, cylindrical type, rectangular type, flat type, etc. [Examples]

[0113] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples. In the following description, "%", "ppm", and "parts" used to express quantities refer to mass unless otherwise specified. Furthermore, in polymers produced by copolymerizing multiple types of monomers, the proportion of monomer units formed by polymerizing a certain monomer in the polymer is, unless otherwise specified, usually equal to the ratio of that particular monomer to the total monomers used in the polymerization of the polymer (starting ratio). Also, in the case of a hydrogenated polymer produced by hydrogenating a polymer containing aliphatic conjugated diene monomer units, the total content ratio of unhydrogenated aliphatic conjugated diene monomer units and alkylene structural units as hydrogenated aliphatic conjugated diene monomer units in the hydrogenated polymer is equal to the ratio of aliphatic conjugated diene monomers to the total monomers used in the polymerization of the polymer (starting ratio). In the examples and comparative examples, various measurements and evaluations were performed using the following methods.

[0114] <Weight average molecular weight> The weight-average molecular weight of a polymer (polymer X, polyvinylpyrrolidone) was measured by gel permeation chromatography (GPC). Specifically, the weight-average molecular weight was calculated as a standard-converted value by creating a calibration curve using polystyrene as the standard substance. The measurement conditions were as follows: <<Measurement Conditions>> Column: TSKgel α-M x 2 (Inner diameter 7.8mm x 30cm x 2, manufactured by Tosoh Corporation) Eluent: Dimethylformamide (50 mM lithium bromide, 10 mM phosphoric acid) Flow rate: 0.5mL / min Sample concentration: Approximately 0.5 g / L (solid content concentration) Injection volume: 200μL Column temperature: 40℃ Detector: Differential refractive index detector (RI) (Tosoh Corporation HLC-8320 GPC RI detector) Detector conditions: RI: Pol(+), Res(1.0s) Molecular weight marker: Tosoh Corporation standard polystyrene kit PStQuick K <Iodine value> The iodine value of the polymer was measured in accordance with JIS K 6235. <Sulphur content> The polymer NMP solution was distilled under reduced pressure to remove the NMP and obtain the sample. Approximately 0.02 g of the sample was weighed onto a magnetic board and combusted in an automatic combustion apparatus (Yanaco), after which the sulfur content was quantified by ion chromatography (Metrohm 930 Compact IC Flex). The sulfur content was quantified as the amount of sulfur (μg) per gram of polymer mass, i.e., the amount (ppm) relative to the mass of the polymer. <Surface acid amount> Approximately 1 g of CNTs to be measured was accurately weighed, and 0.01 mol dm³ was measured. -3 The tetrabutyl hydride (also known as "tetrabutylammonium hydroxide," hereinafter abbreviated as "TBA OH") / 4-methyl-2-pentanone (MIBK) solution was immersed in 100 ml and stirred with a stirrer for 1 hour. The mixture was then centrifuged, and the supernatant was filtered. The remaining TBA OH in the resulting 50 mL filtrate was extracted at a concentration of 0.01 mol dm³. -3 Quantitative analysis was performed by non-aqueous coulometric titration with perchloric acid (HClO4) / MIBK solution, and the amount of acid per gram of carbon nanotube (mmol / g) was determined from the obtained values. An automated coulometric titrator (Kyoto Electronics Ltd., product name "AT-700") was used for the analysis. The entire procedure was performed at room temperature under an argon atmosphere. <Surface basicity> Precisely weigh approximately 1 g of the CNT to be measured, and immerse it in 100 ml of 0.01 mol dm -3 HClO4 / MIBK solution, and stir with a stirrer for 1 hour. Then perform centrifugation and filter the supernatant with a filter. The HClO4 remaining in 50 mL of the obtained filtrate was quantitatively analyzed by non-aqueous potentiometric titration with 0.01 mol dm -3 TBA OH / MIBK solution, and the base amount (mmol / g) per 1 g of CNT was specified from the obtained value. For the analysis, an automatic potentiometric titrator (manufactured by Kyoto Electronics Co., Ltd., product name "AT-700") was used. Also, a series of operations were performed at room temperature under an argon stream. <BET specific surface area> The BET specific surface area of the CNT was measured using Belsorp-mini (manufactured by Microtrac·BEL Co., Ltd., in accordance with ASTM D3037-81). <D / G ratio> The D / G ratio of the CNT was measured at an excitation wavelength of 532 nm by the Raman method (manufactured by Bruker Optics, microscopic laser Raman SENTERRA) with the sample fixed under glass. <HSP distance> The Hansen solubility parameters (HSP N ) of the nitrogen compound, the Hansen solubility parameters (HSP X ) of the polymer X, and the Hansen solubility parameters (HSP F ) of the fibrous conductive material (CNT) were determined, and the HSP distances (R A ) between the nitrogen compound and the polymer X and the HSP distances (R B ) between the nitrogen compound and the fibrous conductive material were calculated using the above-mentioned formulas (A) and (B), respectively. <<HSP of nitrogen compound N >> The numerical values (polar term δ p1 , dispersion term δ d1 , and hydrogen bond term δ h1For substances not listed in the database, values ​​obtained by the Y-MB method (Hiroshi Yamamoto's molecular breaking method) were used. <<HSP of PolymerX X >> 0.5 g of polymer X was added to 10 ml each of the 15 organic solvents shown in Table 1 below, and the mixture was allowed to stand at 25°C for 24 hours to prepare the evaluation solution. This evaluation solution was scored by visual observation as follows. • Insoluble (poor solvent): 0 • Turbid and / or fluctuating state (poor solvent): 2 • Complete dissolution (good solvent): 1 The scoring results are shown in Table 1. Based on the obtained scores, the HSPiP calculation program described above is used to perform the HSP X The polar term δ p2 , dispersion term δ d2 and hydrogen bonding term δ h2 The following was determined. For the polyvinylpyrrolidone (PVP) used in Comparative Example 3, the values ​​from the HSPiP database mentioned above were used. <<HSP of fibrous conductive material F >> 0.1 g of fibrous conductive material (CNT) was added to 10 ml each of the 16 organic solvents shown in Table 2 below, and ultrasonically dispersed under conditions of 20 kHz, 200 W, and 10 minutes to prepare the measurement solution. Pulse NMR measurements were performed on the above 16 organic solvents (pure solvents) and the measurement solution. From the obtained results, R as a function of the relaxation time T1 of the pure solvent and the relaxation time T2 of the solvent in the measurement solution was determined. sp This was calculated using the following formula. R sp =(T1 / T2)-1 The obtained R sp Based on the values, the affinity between each solvent and the fibrous conductive material was scored as follows. ·R sp ≤0.2 (poor solvent):0 0.2 <R sp ≤0.5 (poor solvent):2 0.5 <R sp (Good solvent): 1 The scoring results are shown in Table 2. Based on the obtained scores, the HSPiP calculation program described above is used to perform the HSP F The polar term δ p3 , dispersion term δ d3 and hydrogen bonding term δ h3 They sought it. <Viscosity reduction effect> The viscosity reduction effect of each combination of nitrogen compound and polymer X used in the examples and comparative examples was evaluated as follows. First, an 8% NMP solution of polymer X was prepared. The viscosity (V1) of this NMP solution was measured using a B-type viscometer (rotation speed: 60 rpm) under conditions of 25°C. Next, an 8% NMP solution of polymer X, etc., and an 8% NMP solution of a nitrogen compound, etc., prepared separately, were mixed in a mass ratio of polymer X, etc.:nitrogen compound, etc. = 1:9. The mixture was then stirred at 60 rpm for 1 hour using a shaker to prepare the sample solution. The viscosity (V2) of this sample solution was measured using a B-type viscometer (rotation speed: 60 rpm) under conditions of 25°C. The viscosity ratio (%) = V2 / V1 × 100 was then calculated and evaluated according to the following criteria. A smaller viscosity ratio before and after the addition of nitrogen compounds indicates a better viscosity reduction effect due to the addition of nitrogen compounds. A: Viscosity ratio less than 60% B: Viscosity ratio between 60% and less than 65% C: Viscosity ratio of 65% or higher <Dispersion initial viscosity (dispersibility)> For the conductive material dispersion, a rheometer (Anton Paar MCR302) was used to measure the temperature at 25°C and the shear rate at 10s. -1 Under these conditions, the initial dispersion viscosity η A The following criteria were used to measure and evaluate η. A A smaller value indicates that the CNTs, etc., are well dispersed in the conductive material dispersion. A:η A is 5 Pa·s or less B:η A If the pressure is between 5 Pa·s and 15 Pa·s or less C:η A If the pressure is between 15 Pa·s and 50 Pa·s, then... D:ηA If the pressure exceeds 50 Pa·s, or if measurement is not possible, <Dispersion (Initial TI value of dispersion)> For the conductive material dispersion, using a rheometer (Anton Paar MCR302), the shear rate was measured in units of 1 / s at a temperature of 25°C. -2 from 10 3 The dependence of viscosity on shear rate in the range up to 10s was evaluated. -1 viscosity η 10 , shear rate 0.1s -1 viscosity η 0.1 Using TI value = η 0.1 / η 10 The coefficient of dispersion (TI) was calculated and evaluated according to the following criteria. A lower TI value indicates that the CNTs, etc., are well dispersed in the conductive material dispersion. A: TI value is less than 30 B: TI value between 30 and 50 C: TI value between 50 and 70 D: TI value of 70 or higher <Temporal stability of electrode slurry> Regarding the electrode slurry, the viscosity value V after 1 hour of preparation. 1h , and the viscosity value V after 10 days of preparation 10d Each viscosity was measured. The viscosity measurements were performed using a Type B viscometer (rotation speed: 60 rpm) under conditions of 25°C. And viscosity increase rate (%) = (V 10d -V 1h ) / V 1h The viscosity was calculated and evaluated according to the following criteria. A smaller viscosity increase rate indicates that the electrode slurry is less likely to thicken over time. A: Viscosity increase rate less than 20% B: Viscosity increase rate is 20% or more but less than 50% C: Viscosity increase rate of 50% or more <Suppression of resistance increase after cycle> A lithium-ion secondary battery was charged to 50% of its State of Charge (SOC) at 1C (where C is a value expressed as rated capacity (mA) / hour (h)) in a 25°C atmosphere. Subsequently, in a 25°C environment, charging and discharging cycles were performed for 20 seconds at 0.2C, 0.5C, 1.0C, 2.0C, and 3.0C, centered around 50% of the SOC. In each case (charging and discharging), the battery voltage after 20 seconds was plotted against the current value, and the slope was determined as the IV resistance (Ω) (IV resistance during charging and IV resistance during discharging), which was defined as the pre-cycle IV resistance R1 (Ω). Subsequently, a cycle test was conducted in which the lithium-ion secondary battery was charged at 1C in a 45°C atmosphere until the battery voltage reached 4.2V, and then discharged at 1C until the battery voltage reached 3.0V, repeating this process 200 times. Then, the IV resistance (Ω) was determined using the same method as described above, and this was set as the IV resistance R2 (Ω) after the cycle. For the obtained IV resistance R2 (Ω) after the cycle, the IV resistance increase rate (%) was calculated as (R2-R1) / R1 × 100, relative to the IV resistance R1 (Ω) before the cycle. Based on this IV resistance increase rate (%) and the IV resistance R2 (Ω) after the cycle, the following criteria were used for evaluation. A lower percentage increase in IV resistance and a smaller IV resistance R2 (Ω) after the cycle test indicate that the resistance has decreased over the long term, demonstrating superior battery characteristics of the lithium-ion secondary battery. A: IV resistance increase rate is less than 30% and R2 is less than 2.5Ω B: IV resistance increase rate is 30% or more but less than 35% AND R2 is less than 2.8Ω C:IV resistance increase rate is 35% or more but less than 40% AND R2 is less than 3.2Ω D:IV resistance change rate of 40% or more

[0115] (Example 1) <Preparation of Polymer X> In the reactor, 200 parts of deionized water, 25 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate, 35 parts of acrylonitrile as a nitrile group-containing monomer, and 7.90 parts of t-dodecyl mercaptan as a molecular weight modifier were charged in this order. Next, the internal gas was replaced with nitrogen three times, and then 65 parts of 1,3-butadiene as an aliphatic conjugated diene monomer were charged. The reactor was then kept at 5°C, and 0.03 parts of cumene hydroperoxide as a polymerization initiator, appropriate amounts of a reducing agent and a chelating agent were charged. The polymerization reaction was continued with stirring, and when the polymerization conversion rate reached 80%, 0.1 parts of a 10% aqueous solution of hydroquinone as a polymerization termination agent was added to stop the polymerization reaction. Next, residual monomers were removed at a water temperature of 80°C to obtain an aqueous dispersion of the polymer precursor. To obtain the target polymer X (hydrogenated polymer, hydrogenated nitrile rubber), an aqueous dispersion of the precursor was obtained. The aqueous dispersion was then combined with a palladium catalyst (a solution of 1% palladium acetate acetone solution mixed with an equal weight of deionized water) in an autoclave so that the palladium content relative to the weight of solids in the aqueous dispersion was 3,000 ppm. A hydrogenation reaction was then carried out at a hydrogen pressure of 3 MPa and a temperature of 50°C for 6 hours to obtain an aqueous dispersion of the target polymer X (hydrogenated polymer, hydrogenated nitrile rubber). Subsequently, the contents were allowed to return to room temperature, the system was subjected to a nitrogen atmosphere, and then concentrated using an evaporator until the solid content concentration reached 40% to obtain a concentrated aqueous dispersion. Next, 200 parts of NMP were added to 100 parts of the concentrated aqueous dispersion, and after evaporating all the water and residual monomers under reduced pressure, the NMP was evaporated to obtain a 7.2% NMP solution of polymer X(X-1). The iodine value, weight-average molecular weight, and sulfur content of polymer X were measured. The results are shown in Table 3. <Preparation of Binder Composition> In the NMP solution of polymer X obtained according to the above, 2-methyl-2-imidazoline (molecular weight: 84, polarity term δ) was added as a nitrogen compound. p1 :10.5MPa 1 / 2 A binder composition was prepared by adding 2-methyl-2-imidazoline. The amount of 2-methyl-2-imidazoline added was such that polymer X (equivalent to solid content):2-methyl-2-imidazoline = 90:10 (by mass). The viscosity reduction effect was evaluated separately using the above polymer X and 2-methyl-2-imidazoline. Furthermore, the HSP distance (R) between the nitrogen compound and polymer X was also evaluated. A The result was calculated. The results are shown in Table 3. <Preparation of surface-treated carbon nanotubes (CNTs)> 1g weighed multi-walled carbon nanotube (BET specific surface area: 300m²) 2 The CNTs (CNTs) were added to a mixed solution of 40 mL of concentrated nitric acid and 40 mL of 2 M sulfuric acid, and stirred for 1 hour while maintaining the temperature at 60°C (acid treatment). Then, solid-liquid separation was performed by filtration using filter paper (Toyo Roshi Kaisha, Filter Paper No. 2, 125 mm). After washing the solids on the filter paper with 200 mL of purified water, the CNT solids (acid-treated CNTs) were recovered. Furthermore, these CNT solids were added to 200 mL of a 2.5 mol / liter lithium hydroxide aqueous solution, and stirred for 2 hours while maintaining the temperature at 25°C in a water bath (base treatment). Then, solid-liquid separation was performed by suction filtration using a membrane filter with a pore size of 10 μm. The CNT solids (acid-base treated CNTs) on the membrane filter were repeatedly washed with purified water. When the electrical conductivity of the washing water was 50 μs / m or less, the CNT solids were separated into solid and liquid components using the same method as above. The obtained CNT solids were dried under reduced pressure at 50°C for 8 hours to prepare surface-treated CNTs (C-1). Table 3 shows the surface acid content, the ratio of surface acid content to surface base content, and the D / G ratio of these surface-treated CNTs. The BET specific surface area of ​​these surface-treated CNTs was 300 m². 2 It was / g. <Preparation of conductive material dispersion> A conductive material dispersion with a solid content of 7.2% was prepared by stirring 6.0 parts of the above-mentioned surface-treated CNTs as a fibrous conductive material, 1.2 parts of the above-mentioned binder composition (in terms of solid content), and 92.8 parts of NMP using a disperser (3000 rpm, 10 minutes), and then mixing for 1 hour at a peripheral speed of 8 m / s using a bead mill with 1 mm diameter zirconia beads. The initial viscosity and initial TI value of this conductive material dispersion were evaluated. The results are shown in Table 3. Furthermore, the HSP distance (R) between the nitrogen compound and the fibrous conductive material B The result was calculated. The results are shown in Table 3. <Preparation of cathode slurry> 1.0 part (in terms of solid content) of the conductive material dispersion obtained as described above, and a ternary active material (LiNi) having a layered structure as the positive electrode active material. 0.6 Co 0.2 Mn 0.2 A cathode slurry was prepared by mixing 98.0 parts of O2 (volume-average particle size: 10 μm), 1.0 part of polyvinylidene fluoride as another binder, and NMP in a planetary mixer (60 rpm, 30 minutes). The amount of NMP added was adjusted so that the viscosity of the resulting cathode slurry (measured using a single-cylindrical rotational viscometer in accordance with JIS Z8803:1991; temperature: 25°C, rotation speed: 60 rpm) was within the range of 4000 to 5000 mPa·s. <Fabrication of the positive electrode> As a current collector, a 20 μm thick aluminum foil was prepared. The positive electrode slurry obtained as described above was coated onto one side of the aluminum foil using a comma coater, resulting in a basis weight of 20 mg / cm² after drying. 2 The material was applied in this manner, dried at 90°C for 20 minutes, then at 120°C for 20 minutes, and then heat-treated at 60°C for 10 hours to obtain a cathode base. This cathode base was rolled using a roll press to form a cathode composite layer (density: 3.2 g / cm³). 3 A sheet-like positive electrode was fabricated from aluminum foil. The sheet-like positive electrode was then cut to a width of 48.0 mm and a length of 47 cm to be used as a positive electrode for a lithium-ion secondary battery. <Fabrication of the negative electrode> In a 5 MPa pressure vessel equipped with a stirrer, 33 parts of 1,3-butadiene as an aliphatic conjugated diene monomer, 3.5 parts of itaconic acid as a carboxylic acid group-containing monomer, 63.5 parts of styrene as an aromatic-containing monomer, 0.4 parts of sodium dodecylbenzenesulfonate as an emulsifier, 150 parts of deionized water, and 0.5 parts of potassium persulfate as a polymerization initiator were added and thoroughly stirred. Polymerization was then started by heating to 50°C. When the polymerization conversion rate reached 96%, the mixture was cooled to stop the polymerization reaction, and a mixture containing particulate binder (styrene-butadiene copolymer) was obtained. A 5% aqueous sodium hydroxide solution was added to the above mixture to adjust the pH to 8, and unreacted monomers were removed by heated vacuum distillation. The mixture was then cooled to below 30°C to obtain an aqueous dispersion containing the negative electrode binder. In a planetary mixer, 48.75 parts of artificial graphite and 48.75 parts of natural graphite were added as negative electrode active materials, along with 1 part of carboxymethylcellulose (equivalent to solid content) as a thickener. The mixture was then diluted with deionized water to a solid content concentration of 60%, and kneaded at a rotation speed of 45 rpm for 60 minutes. Subsequently, 1.5 parts (equivalent to solid content) of the aqueous dispersion containing the negative electrode binder obtained as described above was added, and the mixture was kneaded at a rotation speed of 40 rpm for 40 minutes. Finally, deionized water was added to achieve a viscosity of 3000 ± 500 mPa·s (measured with a B-type viscometer at 25°C and 60 rpm) to prepare the negative electrode slurry. The above-mentioned negative electrode slurry is applied to the surface of a 15 μm thick copper foil current collector using a comma coater, at a rate of 10 ± 0.5 mg / cm². 2 The material was applied in this manner. Subsequently, the copper foil coated with the negative electrode slurry was transported at a speed of 400 mm / min through an oven at 80°C for 2 minutes, and then through an oven at 110°C for another 2 minutes, thereby drying the slurry on the copper foil and obtaining a negative electrode base with a negative electrode composite layer formed on the current collector. This negative electrode raw material is rolled using a roll press to form a negative electrode composite layer (density: 1.6 g / cm³). 3 A sheet-like negative electrode was fabricated from aluminum foil. The sheet-like negative electrode was then cut to a width of 50.0 mm and a length of 52 cm to be used as a negative electrode for a lithium-ion secondary battery. <Manufacturing of lithium-ion secondary batteries> The fabricated positive electrode and negative electrode for lithium-ion secondary batteries were placed with their electrode composite layers facing each other, and a 15 μm thick separator (microporous polyethylene membrane) was interposed between them. The materials were then wound around a 20 mm diameter core to obtain a wound body. The resulting wound body was then compressed from one direction at a speed of 10 mm / second until its thickness reached 4.5 mm. The compressed wound body was elliptical in plan view, and its ratio of major axis to minor axis (major axis / minor axis) was 7.7. In addition, a 1.0 M LiPF6 solution was prepared as the electrolyte (solvent: a mixed solvent of ethylene carbonate (EC) / ethyl methyl carbonate (EMC) = 3 / 7 (volume ratio), additive: containing 2 vol% vinylene carbonate (solvent ratio)). Subsequently, the compressed coil was placed in an aluminum laminate case along with 3.2 g of electrolyte. Then, nickel lead wires were connected to designated locations on the negative electrode and aluminum lead wires were connected to designated locations on the positive electrode. Finally, the opening of the case was sealed with heat to obtain the lithium-ion secondary battery as the electrochemical element of the present invention. This lithium-ion secondary battery was a pouch type with a width of 35 mm, a height of 60 mm, and a thickness of 5 mm, and the nominal capacity of the battery was 700 mAh. The resistance increase suppression after cycling was evaluated for the obtained lithium-ion secondary batteries. The results are shown in Table 3.

[0116] (Examples 2 and 3) In preparing the binder composition, 2-methyl-2-imidazoline was replaced with DBU (Example 2, molecular weight: 152, polarity term δ) as the nitrogen compound. p1 : 6.4 MPa 1 / 2 ), TBD (Example 3, Molecular weight: 139, Polarity term δ p1 :12.0MPa 1 / 2 Except for using ), polymer X, binder composition, surface-treated CNTs, conductive material dispersion, cathode slurry, cathode, anode, and lithium-ion secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3.

[0117] (Example 4) Except for adjusting (reducing) the amount of t-dodecyl mercaptan as a molecular weight modifier during the preparation of polymer X, which changed the weight-average molecular weight and sulfur content of the resulting polymer X, polymer X (X-4), a binder composition, surface-treated CNTs, conductive material dispersion, cathode slurry, cathode, anode, and lithium-ion secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3.

[0118] (Example 5) Except for adjusting the amount of palladium catalyst used in the preparation of polymer X to change the iodine value of the resulting polymer X, polymer X(X-5), binder composition, surface-treated CNTs, conductive material dispersion, cathode slurry, cathode, anode, and lithium-ion secondary battery were prepared in the same manner as in Example 4, and various evaluations were performed. The results are shown in Table 3.

[0119] (Examples 6 and 7) In preparing polymer X, the amount of acrylonitrile was reduced to 25 parts, and 10 parts of n-butyl acrylate as a (meth)acrylic acid ester monomer (Example 6) and 10 parts of styrene as an aromatic-containing monomer (Example 7) were used, respectively. Except for these differences, polymer X (Example 6: X-6, Example 7: X-7), a binder composition, surface-treated CNTs, a conductive material dispersion, a cathode slurry, a cathode, a negative electrode, and a lithium-ion secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3.

[0120] (Example 8) Except for changing the amount of 2-methyl-2-imidazoline added to the binder composition so that polymer X (solid content equivalent):2-methyl-2-imidazoline = 65:35 (by mass), polymer X, binder composition, surface-treated CNTs, conductive material dispersion, cathode slurry, cathode, anode, and lithium-ion secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 3.

[0121] (Examples 9 and 10) Except for adjusting the base treatment time and acid treatment time during the preparation of surface-treated CNTs to change the surface acid content, surface base content, and D / G ratio of the surface-treated CNTs, polymer X, binder composition, surface-treated CNTs (Example 9: C-9, Example 10: C-10), conductive material dispersion, cathode slurry, cathode, anode, and lithium-ion secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 4.

[0122] (Example 11) Except for using polymer X(X-11) obtained as described below, a binder composition, surface-treated CNTs, conductive material dispersion, cathode slurry, cathode, anode, and lithium-ion secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 4. <Preparation of Polymer X> [Polymerization (Preparation of Polymer Intermediates)] In the reactor, 180 parts of deionized water, 25 parts of a 10% aqueous solution of sodium dodecylbenzenesulfonate (emulsifier), 35 parts of acrylonitrile as a nitrile group-containing monomer, and 0.8 parts of t-dodecyl mercaptan as a molecular weight modifier were charged in this order. After replacing the internal gas with nitrogen three times, 65 parts of 1,3-butadiene as an aliphatic conjugated diene monomer were charged. The reactor was then maintained at 10°C, and 0.1 parts of cumene hydroperoxide (polymerization initiator) and 0.1 parts of ferrous sulfate were charged, and the polymerization reaction was continued with stirring. When the polymerization conversion rate reached 85%, 0.1 parts of a 10% aqueous solution of hydroquinone (polymerization inhibitor) was added to stop the polymerization reaction. Next, residual monomers were removed at a water temperature of 80°C to obtain nitrile rubber latex. Then, a portion of the obtained latex was added to an aqueous solution of magnesium sulfate in an amount equal to 12% relative to the nitrile rubber content, and the mixture was stirred to solidify the latex. After that, it was filtered while being washed with water, and the resulting solidified material was vacuum-dried at a temperature of 60°C for 12 hours to obtain nitrile rubber, which is an intermediate (polymer intermediate) of the target polymer. [Double decomposition of polymer intermediates] Next, 9 parts of the obtained nitrile rubber were dissolved in 141 parts of monochlorobenzene and added to the reactor. After heating the reactor to 80°C, 2 L of monochlorobenzene solution containing bis(tricyclohexylphosphine)benzylideneruthenium dichloride as a Grubbs catalyst was added so that the amount of Grubbs catalyst was 0.25 parts per 100 parts of polymer. The reactor was then pressurized to 3.5 MPa with ethylene as a coolefin, and the double decomposition reaction of the nitrile rubber was carried out at a stirring speed of 600 rpm. During the reaction, the temperature was kept constant using a cooling coil connected to a temperature control device and a thermal sensor. [Hydrogenation of multiple decomposed polymer intermediates] Subsequently, the reactor was degassed three times with H2 at 0.7 MPa while continuing to stir. Then, the reactor temperature was raised to 130°C, and 1 L of monochlorobenzene solution containing Wilkinson catalyst and triphenylphosphine was added to the reactor. The amount of Wilkinson catalyst was 0.075 parts and the amount of triphenylphosphine was 1 part per 100 parts of the double-decomposed polymer intermediate. The temperature was then raised to 138°C, and the hydrogenation reaction of the polymer was carried out for 6 hours under a hydrogen pressure of 8.4 MPa to obtain the hydrogenated polymer. After the reaction was complete, 0.2 parts of activated carbon with an average diameter of 15 μm was added to the reactor and stirred for 30 minutes. Then, the solution was filtered through a pore size 5 μm filter to obtain the filtrate. [Preparation of NMP composition] Fifty parts (equivalent to three parts as solids) of the hydrogenated polymer obtained according to the above procedure were taken and mixed with 17 parts of NMP to obtain a mixture. Next, all of the monochlorobenzene contained in the obtained mixture was evaporated under reduced pressure to obtain a 7.2% NMP solution of polymer X (X-11).

[0123] (Examples 12 and 13) In preparing the conductive material dispersion, C-9 (Example 12) and C-10 (Example 13), obtained in the same manner as in Examples 9 and 10, were used as surface-treated CNTs. Except for the cases mentioned above, polymer X, binder composition, conductive material dispersion, cathode slurry, cathode, anode, and lithium-ion secondary battery were prepared in the same manner as in Example 11, and various evaluations were performed. The results are shown in Table 4.

[0124] (Comparative Examples 1 and 2) In preparing the binder composition, benzoic acid (Comparative Example 1, molecular weight: 122, polarity term δ) was used instead of 2-methyl-2-imidazoline as the nitrogen compound. p1 : 6.9 MPa 1 / 2 ), 2-methylimidazole (Comparative Example 2, molecular weight: 82, polarity term δ) p1 :12.0MPa 1 / 2 Except for using ), polymer X, binder composition, surface-treated CNTs, conductive material dispersion, cathode slurry, cathode, anode, and lithium-ion secondary battery were prepared in the same manner as in Example 1, and various evaluations were performed. The results are shown in Table 4.

[0125] (Comparative Example 3) In the preparation of the binder composition, a binder composition, a surface-treated CNT, a conductive material dispersion, a slurry for a positive electrode, a positive electrode, a negative electrode, and a lithium-ion secondary battery were produced in the same manner as in Example 1, except that polyvinylpyrrolidone was used instead of polymer X, and various evaluations were performed. The results are shown in Table 4.

[0126] In Tables 3 and 4 shown below, "AN" means an acrylonitrile unit, "BD" means a structural unit derived from 1,3-butadiene (1,3-butadiene unit and / or 1,3-butadiene hydride unit), "BA" means an n-butyl acrylate unit, "ST" means a styrene unit, "PVP" means polyvinylpyrrolidone, "Mw" means the weight average molecular weight, "25k" means 25×10 3 and "250k" means 250×10 3 and "MI" means 2-methyl-2-imidazoline, "DBU" means diazabicycloundecene, "TBD" means 1,5,7-triazabicyclo[4.4.0]dec-5-ene, "MIZ" means 2-methylimidazole.

[0127] [Table 1] [[ID=forty-two]]<00,00885>

[0128] [Table 2]

[0129] [Table 3]

[0130]

Table 4

[0131] From Tables 3 and 4, a predetermined polymer X, a predetermined nitrogen compound, and NMP are included, and the HSP distance (R A ) is 10.0 MPa 1 / 2 According to Examples 1 to 13 in which it is 10.0 MPa or less, it can be seen that a positive electrode capable of exhibiting excellent cycle characteristics in an electrochemical device can be produced.

Industrial Applicability

[0132] According to the present invention, it is possible to provide a binder composition for an electrochemical device, a conductive material dispersion for an electrochemical device, and a slurry for an electrochemical device electrode, which can form an electrode capable of suppressing an increase in internal resistance after cycling of the electrochemical device. Further, according to the present invention, it is possible to provide an electrochemical device in which an increase in internal resistance after cycling is suppressed.

Claims

1. A binder composition for an electrochemical element comprising polymer X, N-methyl-2-pyrrolidone, and a nitrogen compound other than N-methyl-2-pyrrolidone, The polymer X comprises a nitrile group-containing monomer unit and at least one of an aliphatic conjugated diene monomer unit and an alkylene structural unit. The nitrogen compound has a molecular weight of 1,000 or less and has a cyclic amidine structure. And the Hansen solubility parameter (HSP) of the nitrogen compound Ｎ ) and the Hansen solubility parameter (HSP) of the polymer X Ｘ ) and the HSP distance (R Ａ ) is 10.0 MPa １／２ The following is a binder composition for electrochemical elements.

2. The binder composition for electrochemical elements according to claim 1, wherein the polymer X has a weight-average molecular weight of 300,000 or less.

3. The binder composition for electrochemical elements according to claim 1, wherein the polymer X contains 500 ppm by mass or more of sulfur.

4. The Hansen solubility parameter (HSP) of the nitrogen compound Ｎ ) Polar term δ ｐ１ 14.0 MPa １／２ The binder composition for an electrochemical element according to claim 1, which is as follows:

5. The binder composition for an electrochemical element according to claim 1, wherein the ratio of the mass of the nitrogen compound to the total mass of the polymer X and the nitrogen compound is 0.1% by mass or more and 40% by mass or less.

6. A conductive material dispersion for an electrochemical element, comprising the binder composition for an electrochemical element described in claim 1 and a fibrous conductive material.

7. The conductive material dispersion for an electrochemical element according to claim 6, wherein the fibrous conductive material is of the bundle type.

8. The conductive material dispersion for an electrochemical element according to claim 6, wherein the fibrous conductive material has a surface acid content of 0.01 mmol / g or more and 0.20 mmol / g or less.

9. The conductive material dispersion for an electrochemical element according to claim 6, wherein the fibrous conductive material is a fibrous carbon material, and the ratio of the D-band peak intensity to the G-band peak intensity in the Raman spectrum of the fibrous carbon material is 2.0 or less.

10. A slurry for an electrochemical element electrode, comprising a conductive material dispersion for an electrochemical element according to claim 6 and an electrode active material.

11. The slurry for electrochemical element electrodes according to claim 10, further comprising a binder other than the polymer X.

12. An electrode for an electrochemical element, comprising an electrode composite layer formed using the electrochemical element electrode slurry described in claim 10 or 11.

13. An electrochemical element comprising an electrode for an electrochemical element as described in claim 12.

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