Conductive polymer compositions and their applications

Abstract

A conductive polymer composition containing a lithium-containing compound and a self-doped conductive polymer is realized. [Solution] A conductive polymer composition comprising a conductive polymer having a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), a lithium-containing compound, carbon nanotubes, and a binder. [Formula 1] JPEG2026059501000014.jpg38141[M + R represents a hydrogen ion, alkali metal ion, conjugate acid of an amine compound, or quaternary ammonium cation. R represents an organic group with a total of 1 to 14 carbon atoms having at least one substituent selected from the group consisting of sulfonic acid groups and phosphonic acid groups.

Description

Technical Field

[0001] The present invention relates to a conductive polymer composition, a lithium-ion battery electrode, a lithium-ion battery, a method for manufacturing a lithium-ion battery electrode, and a method for manufacturing a lithium-ion battery.

Background Art

[0002] Conventionally, it has been proposed to use a carbon material and a conductive polymer as an electrode material for a lithium-ion battery to improve cycle characteristics. For example, Patent Document 1 discloses a powder composition having a Li-containing compound, conductive particles containing a π-conjugated conductive polymer, and a binder.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, it is considered that the powder composition as described in Patent Document 1 requires addition of a dopant to the conductive particles in order to obtain good conductivity. In a conventional conductive composition containing a lithium-containing compound or the like that can be used for a lithium-ion battery electrode or the like, an example in which a self-doping type conductive polymer having excellent handleability is applied has not been known.

[0005] One aspect of the present invention aims to realize a conductive polymer composition containing a lithium-containing compound and a self-doping type conductive polymer, etc.

Means for Solving the Problems

[0006] To solve the aforementioned problems, a conductive polymer composition according to one aspect of the present invention comprises a conductive polymer containing polythiophene (A) having at least one structural unit selected from the group consisting of structural units represented by the following general formula (1) and structural units represented by the following general formula (2), a lithium-containing compound, carbon nanotubes, and a binder.

[0007] [ka] [In the above general formula (1), M + R represents a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. In the general formulas (1) and (2) above, R represents an organic group with a total of 1 to 14 carbon atoms having at least one substituent selected from the group consisting of a sulfonic acid group and a phosphonic acid group. [Effects of the Invention]

[0008] According to one aspect of the present invention, a conductive polymer composition containing a lithium-containing compound and a self-doped conductive polymer can be realized. [Modes for carrying out the invention]

[0009] An aspect of the present invention will be described in detail below. Unless otherwise specified in this specification, "A to B" representing a numerical range means "greater than or equal to A and less than or equal to B".

[0010] [Conductive polymer composition] A conductive polymer composition according to one aspect of the present invention comprises a conductive polymer, a lithium-containing compound, carbon nanotubes, and a binder. The conductive polymer contains polythiophene (A) having at least one structural unit selected from the group consisting of structural units represented by the following general formula (1) and structural units represented by the following general formula (2).

[0011] [ka] [In the above general formula (1), M+ R represents a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. In the general formulas (1) and (2) above, R represents an organic group with a total of 1 to 14 carbon atoms having at least one substituent selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0012] Hereinafter, a conductive polymer composition according to one aspect of the present invention may be referred to as "the Composition." The Composition can be suitably used, for example, in lithium-ion battery electrodes. By using the Composition in lithium-ion battery electrodes, the conductivity of the lithium-ion battery electrodes can be improved, and a lithium-ion battery with good rate characteristics and cycle characteristics can be realized. In this specification, when "good battery characteristics" is described, it includes exhibiting good conductivity in the lithium-ion battery electrodes and exhibiting good rate characteristics and cycle characteristics in the lithium-ion battery.

[0013] (conductive polymer) A conductive polymer according to one aspect of the present invention comprises a polythiophene (A) having at least one structural unit selected from the group consisting of the structural unit represented by the general formula (1) and the structural unit represented by the general formula (2).

[0014] R in general formulas (1) and (2) - This represents a state in which the sulfonic acid group or phosphonic acid group contained in R is ionized, and for general formula (1), M is used as its countercation. + This represents a state in which cations are ionically bonded.

[0015] In the general formula (1), M + This represents a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation.

[0016] Preferred alkali metal ions include, for example, Li ions, Na ions, or K ions.

[0017] The conjugate acid of an amine compound refers to a species that becomes a cationic species when a hydron (H + ) is added to the amine compound. The amine compound may be any amine compound that reacts with a sulfonic acid group or a phosphonic acid group to form a conjugate acid, and examples include an amine compound represented by N(R 1 )3 having sp3 hybrid orbitals [the conjugate acid is represented by [NH(R 1 )3] + .], a pyridine compound having sp2 hybrid orbitals, or an imidazole compound, etc.

[0018] The substituent R 1 each independently represents a hydrogen atom, an alkyl group having 1 to 18 carbon atoms, or an alkyl group having 1 to 18 carbon atoms with a substituent.

[0019] The alkyl group having 1 to 18 carbon atoms is not particularly limited, and examples include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a tert-pentyl group, a cyclopentyl group, an n-hexyl group, a 2-ethylbutyl group, a cyclohexyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, a dodecyl group, a tetradecyl group, a hexadecyl group, or an octadecyl group, etc.

[0020] Examples of the alkyl group having 1 to 18 carbon atoms with a substituent include an alkyl group having 1 to 18 carbon atoms having a halogen atom, an alkyl group having 1 to 18 carbon atoms, an amino group, or a hydroxy group, and specifically, a trifluoromethyl group, a 2-hydroxyethyl group, etc. are exemplified.

[0021] Among these, as the substituent R 1 , independently, a hydrogen atom, a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, a hexyl group, an octyl group, a 2-ethylhexyl group, or a 2-hydroxyethyl group is preferable.

[0022] N(R that forms the conjugate acid of the amine compound1 Examples of amine compounds represented by )3 include ammonia, methylamine, dimethylamine, trimethylamine, ethylamine, diethylamine, triethylamine, n-propylamine, isopropylamine, n-butylamine, tert-butylamine, dibutylamine, tributylamine, hexylamine, dihexylamine, trihexylamine, octylamine, dioctylamine, trioctylamine, ethanolamine compounds (e.g., aminoethanol, dimethylaminoethanol, methylaminoethanol, diethanolamine, N-methyldiethanolamine, triethanolamine), 3-amino-1,2-propanediol, 3-methylamino-1,2-propanediol, 3-dimethylamino-1,2-propanediol, N-isopropyl-N,N-dimethylamine, or N-ethyl-N,N-dimethylamine.

[0023] N(R 1 Examples of compounds other than the amine compounds represented by )3 include imidazole compounds (e.g., imidazole, N-methylimidazole, 1,2-dimethylimidazole), pyridine, picoline, or lutidine.

[0024] The total number of carbon atoms in the conjugate acid of the amine compound is not particularly limited, but may be 1 to 30. From the viewpoint of solubility, it is preferable that the total number of carbon atoms be 4 to 30, more preferably 5 to 30, more preferably 5 to 25, more preferably 12 to 24, and more preferably 18 to 24.

[0025] Examples of quaternary ammonium cations include tetramethylammonium cation, tetraethylammonium cation, tetran-propylammonium cation, tetran-butylammonium cation, or tetran-hexylammonium cation. From the viewpoint of availability, tetramethylammonium cation or tetraethylammonium cation are preferred.

[0026] The total number of carbon atoms in a quaternary ammonium cation is not particularly limited, but for example, it may be 4 to 30, preferably 5 to 30, and more preferably 8 to 16.

[0027] In the general formulas (1) and (2) above, R represents an organic group having a total of 1 to 14 carbon atoms and having at least one substituent selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0028] Organic groups with a total of 1 to 14 carbon atoms can also be rephrased as hydrocarbon groups with a total of 1 to 14 carbon atoms that may have substituents, and are not particularly limited, but examples include methyl group, ethyl group, propyl group, butyl group, hexyl group, octyl group, decyl group, dodecyl group, tetradecyl group, propyloxymethyl group, or butyloxymethyl group.

[0029] While polythiophene (A) is not particularly limited, it is more preferable to use polythiophene (A2) containing at least two structural units selected from the group consisting of the structural unit represented by the following general formula (3) and the structural unit represented by the following general formula (4), or polythiophene (A3) containing at least two structural units selected from the group consisting of the structural unit represented by the following general formula (5) and the structural unit represented by the following general formula (6). Furthermore, it is more preferable for polythiophene (A3) to be polythiophene (A3') containing at least two structural units selected from the group consisting of the structural unit represented by the following general formula (5') and the structural unit represented by the following formula (6').

[0030] [ka] [In the above general formula (3), M + R represents a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. In the general formulas (3) and (4) above, R2 [where m represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a halogen atom. m represents an integer from 1 to 6, and n represents 0 or 1.]

[0031] [ka] [In the above general formula (5), M + R represents a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. In the general formulas (5) and (6) above, R 3 Each instance of R independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a halogen atom. 4 'p' represents a hydrogen atom, or a linear or branched alkyl group having 1 to 6 carbon atoms. 'p' represents 0 or 1, 'q' represents an integer from 0 to 6, and 'r' represents 0 or 1.

[0032] [ka] [In the above general formula (5'), M + This represents a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation.

[0033] In the above general formulas (3), (5), and (5'), M + The definition and preferred range of M in general formula (1) + This is the same as the definition and preferred range.

[0034] In the above general formulas (3) and (4), R 2 , and R in the general formulas (5) and (6) 3 This represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a halogen atom.

[0035] Examples of linear or branched alkyl groups having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, cyclopentyl group, n-hexyl group, 2-ethylbutyl group, or cyclohexyl group.

[0036] Examples of halogen atoms include fluorine atoms, chlorine atoms, or bromine atoms.

[0037] R 2 and R 3 Regarding this, in terms of solubility, it is preferable that it be a hydrogen atom, a methyl group, an ethyl group, or a fluorine atom. 2 Regarding this, in terms of solubility, it is more preferable to have a hydrogen atom or a methyl group, and more preferably a methyl group. 3 Regarding this, in terms of solubility, it is more preferable to have a hydrogen atom or a methyl group, and more preferably a hydrogen atom.

[0038] In the above general formulas (5) and (6), R 4 This represents a hydrogen atom or a linear or branched alkyl group having 1 to 6 carbon atoms.

[0039] Examples of linear or branched alkyl groups having 1 to 6 carbon atoms include methyl group, ethyl group, n-propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, neopentyl group, tert-pentyl group, cyclopentyl group, n-hexyl group, 2-ethylbutyl group, or cyclohexyl group.

[0040] R 4 Regarding this, in terms of solubility, it is preferably a hydrogen atom, a methyl group, or an ethyl group, and more preferably a hydrogen atom.

[0041] In the general formulas (3) and (4) above, m represents an integer from 1 to 6, preferably an integer from 1 to 4, and more preferably 2 or 3.

[0042] In the general formulas (3) and (4) above, n is 0 or 1, preferably 1. In the general formulas (5) and (6) above, p represents 0 or 1, preferably 0. In the general formulas (5) and (6) above, q represents an integer from 0 to 6, preferably 0. In the general formulas (5) and (6) above, r represents 0 or 1, preferably 0.

[0043] The structural units represented by general formulas (2), (4), (6) and (6') represent the self-doping state of the structural units represented by general formulas (1), (3), (5), and (5'), respectively. This doping state is manifested by the sulfonic acid group or phosphonic acid group in the structural units represented by general formulas (1), (3), (5), and (5') acting as a p-type dopant. Polymers that exhibit conductivity without the addition of external dopants in this manner are called self-doped polymers.

[0044] (Method for manufacturing conductive polymers) Polythiophene (A) can be produced by polymerizing a thiophene monomer represented by the following general formula (7) in water or an alcohol solvent in the presence of an oxidizing agent, and then, if necessary, by acid treatment.

[0045] [ka] [M in the above general formula (7) + This represents a hydrogen ion or a metal ion. Polythiophene (A2) can be produced by polymerizing a thiophene monomer represented by the following general formula (8) in water or an alcohol solvent in the presence of an oxidizing agent, and then, if necessary, by acid treatment.

[0046] [ka] [In the above general formula (8), M + R represents a hydrogen ion or a metal ion. 2 Regarding R in the above general formula (1), 2 This is synonymous. m represents an integer from 1 to 6, and n represents 0 or 1.

[0047] Polythiophene (A3) can be produced by polymerizing a thiophene monomer represented by the following general formula (9) in water or an alcohol solvent in the presence of an oxidizing agent, and then, if necessary, by acid treatment.

[0048] [ka] [In the above general formula (9), M + R represents a hydrogen ion or a metal ion. 3 Each instance of R independently represents a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms, or a halogen atom. 4 'p' represents a hydrogen atom, or a linear or branched alkyl group having 1 to 6 carbon atoms. 'p' represents 0 or 1, 'q' represents an integer from 0 to 6, and 'r' represents 0 or 1.

[0049] Polythiophene (A3') can be produced by polymerizing a thiophene monomer represented by the following general formula (9') in water or an alcohol solvent in the presence of an oxidizing agent, and then, if necessary, by acid treatment.

[0050] [ka] [In the above general formula (9'), M + This represents a hydrogen ion or a metal ion.

[0051] In the above general formulas (7), (8), (9), and (9'), M +The metal ions represented by are not particularly limited, but examples include transition metal ions, noble metal ions, non-ferrous metal ions, alkali metal ions (e.g., Li ions, Na ions, or K ions), or alkaline earth metal ions.

[0052] When the polymer obtained after polymerization of the thiophene monomer represented by the general formulas (7), (8), (9), and (9') is a salt of a metal ion, the obtained metal salt polymer can be treated with acid to M + It can be converted into hydrogen ions.

[0053] The thiophene monomer represented by the general formula (8) is not particularly limited, but specifically includes 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonic acid, 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonate sodium, 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl)hexane-1-sulfonate lithium, 6-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-2-yl ) Potassium hexane-1-sulfonate, 8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)octan-1-sulfonic acid, 8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)octan-1-sulfonate sodium, 8-(2,3-dihydrothieno[3,4-b][1,4]dioxin-2-yl)octan-1-sulfonate potassium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propanesulfonate sodium, 3-[(2 ,3-Dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propanesulfonate potassium, 3-[(2,3-Dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate sodium, 3-[(2,3-Dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-ethyl-1-propanesulfonate sodium, 3-[(2,3-Dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-propyl-1- Sodium propanesulfonate, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-pentyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-hexyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopropyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isobutyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-isopentyl-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]- 1-Fluoro-1-propanesulfonate sodium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate potassium, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonic acid, 3-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate ammonium, 3-[(2,3-di Hydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-propanesulfonate triethylammonium, 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butanesulfonate sodium, 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-butanesulfonate potassium, 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]- Examples include sodium 1-methyl-1-butanesulfonate, potassium 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-methyl-1-butanesulfonate, potassium 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-fluoro-1-butanesulfonate, or potassium 4-[(2,3-dihydrothieno[3,4-b]-[1,4]dioxin-2-yl)methoxy]-1-fluoro-1-butanesulfonate, etc.

[0054] In one embodiment of the present invention, the conductivity of the conductive polymer is not particularly limited, but it is preferable that the conductivity (electrical conductivity) in the film state be 10 S / cm or more, in order to provide a lithium-ion battery electrode with excellent conductivity.

[0055] Furthermore, in one aspect of the present invention, a conductive polymer synthesized based on prior art may also be used.

[0056] The content of the conductive polymer in this composition is not particularly limited, but in order to obtain good battery characteristics, it is preferably 0.01 to 30% by mass, more preferably 0.01 to 20% by mass, and even more preferably 0.01 to 10% by mass, based on 100% by mass of the total amount of the composition.

[0057] (Lithium-containing compounds) This composition contains a lithium-containing compound. When this composition is used, for example, in a lithium-ion battery electrode, the lithium-containing compound can function as an active material in the lithium-ion battery electrode.

[0058] Examples of lithium-containing compounds include lithium cobalt oxide (Li X CoO2), lithium iron phosphate (LiFePO4), lithium manganese phosphate (LiMnPO4), lithium iron manganese phosphate (LiMn X Fe (1-X) PO4), lithium nickelate (Li X NiO2), and lithium manganate (Li X MnO2, Li X Mn2O4), as well as other multi-component lithium (LiNi X Co (1-X) O2, LiLiLi X Mn (2-X) O4, LiMn a Ni b Co cExamples include lithium composite oxides such as O2(a+b+c=1). Among these, the lithium-containing compound is preferably at least one selected from the group consisting of lithium cobalt oxide, lithium iron phosphate, lithium manganese phosphate, lithium manganese iron phosphate, and multi-component lithium, from the viewpoint of having excellent battery performance such as high energy density, long life, and high output.

[0059] Furthermore, composite oxides of lithium and at least one transition metal selected from transition metals such as Co, Ni, and Mn are also preferred, and specific examples include LiCoO2, LiNiO2, LiMnO2, LiMn2O4, and LiNi X Co (1-X) O2, LiLiLi X Mn (2-X) O4, LiMn a Ni b Co c O2(a+b+c=1) is one example.

[0060] The lithium-containing compound content in this composition is not particularly limited, but in order to obtain good battery characteristics, it is preferably 0.001 to 30% by mass, more preferably 0.001 to 20% by mass, and even more preferably 0.001 to 10% by mass, based on 100% by mass of the total amount of the composition.

[0061] When the lithium-containing compound is in particulate form, its average particle size is not particularly limited, but is preferably, for example, 5 to 20 μm.

[0062] Lithium-containing compounds can be commercially available or prepared using other known methods.

[0063] (Carbon nanotubes) This composition contains carbon nanotubes. When this composition is used, for example, in lithium-ion battery electrodes, the carbon nanotubes function as a conductive additive in the lithium-ion battery electrodes. Furthermore, the conductive polymer described above also functions as a dispersant for the carbon nanotubes in the conductive additive.

[0064] Carbon nanotubes contribute to increasing the capacity, power output, and lifespan of lithium-ion batteries by being used as a conductive additive in lithium-ion battery electrodes. Specifically, the inclusion of carbon nanotubes allows for an increase in the amount of active material packed into the lithium-ion battery electrodes, thereby increasing the capacity of the lithium-ion battery. Furthermore, carbon nanotubes can improve the conductivity of lithium-ion battery electrodes, thereby increasing the power output of the lithium-ion battery. In addition, carbon nanotubes contribute to extending the lifespan of lithium-ion batteries by homogenizing the uptake and release of lithium by the active material in the lithium-ion battery electrodes.

[0065] Carbon nanotubes refer to materials in which a network of six-membered rings made of carbon is formed in a single-walled or multi-walled coaxial ring. While not particularly limited, at least one selected from the group consisting of single-walled carbon nanotubes and multi-walled carbon nanotubes is preferred. Multi-walled carbon nanotubes include double-walled carbon nanotubes and carbon nanotubes with three or more layers. Single-walled carbon nanotubes are more preferred because they yield conductive polymer films exhibiting high conductivity.

[0066] The diameter of the single-walled carbon nanotube (meaning the "average diameter") is not particularly limited, but may be, for example, 20 nm or less, preferably 10 nm or less, and more preferably 5 nm or less. The lower limit of the diameter of the single-walled carbon nanotube is not particularly limited, but may be, for example, 0.4 nm or more, and may be 0.5 nm or more. The diameter of the single-walled carbon nanotube is preferably in the range of 0.4 to 20 nm, more preferably in the range of 0.4 to 10 nm, more preferably in the range of 0.5 to 5 nm, and more preferably in the range of 0.8 to 3 nm.

[0067] Such carbon nanotubes can be commercially available or those prepared by other known methods. Although carbon nanotubes are available in the form of powdered solids, aqueous dispersants, or organic solvent dispersions, in this composition, they are preferably in the form of powdered solids.

[0068] The carbon nanotube content in this composition is not particularly limited, but in order to obtain good battery characteristics, it is preferably 0.001 to 5% by mass, more preferably 0.003 to 2% by mass, and even more preferably 0.005 to 1% by mass, based on 100% by mass of the total amount of the composition.

[0069] In this composition, in order to obtain good battery characteristics, the composition ratio of conductive polymer to carbon nanotubes is preferably 0.001 to 2 parts by mass of carbon nanotubes per 1 part by mass of conductive polymer, more preferably 0.001 to 1 part by mass, and even more preferably 0.05 to 1 part by mass.

[0070] (Binder) The binder is a substance that binds the conductive polymer, the lithium-containing compound, and the carbon nanotubes together, and examples include polymer compounds such as resins.

[0071] Examples of binders include fluororesins, polyolefins, conjugated diene polymers, acrylic resins, polyvinyl alcohol resins, cellulose resins, and latex resins.

[0072] Examples of fluororesins include polyvinylidene fluoride, polytetrafluoroethylene, ethylene-tetrafluoroethylene copolymer, and vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer.

[0073] Examples of polyolefins include polyethylene, polypropylene, and modified versions thereof.

[0074] Examples of conjugated diene polymers include styrene-butadiene copolymers, acrylonitrile-butadiene copolymers, and acrylonitrile-butadiene-styrene copolymers, as well as their hydrides.

[0075] Examples of acrylic resins include methacrylic acid ester copolymers, acrylic acid ester copolymers, methacrylic acid ester-acrylic acid ester copolymers, styrene-acrylic acid ester copolymers, and acrylonitrile-acrylic acid ester copolymers.

[0076] Examples of polyvinyl alcohol-based resins include polyvinyl alcohol and polyvinyl acetate.

[0077] Examples of cellulose-based resins include ethylcellulose, methylcellulose, hydroxymethylcellulose, hydroxyethylcellulose, and carboxymethylcellulose.

[0078] Examples of latexes include copolymers of unsaturated carboxylic acid monomers with other monomers copolymerizable thereto. Examples of unsaturated carboxylic acid monomers include (meth)acrylic acid, and examples of other monomers include styrene. Such copolymers can be produced, for example, by known emulsion polymerization. Specific examples include styrene-butadiene latex, acrylic latex, acrylonitrile-butadiene latex, fluorine latex, and silicone latex.

[0079] Among these, the binder is preferably at least one selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, polyester, and polyvinyl alcohol, because it is stable within the operating voltage range of the lithium-ion battery, has strong binding force to the positive electrode material, negative electrode material, conductive material, and current collector, and has low electrical resistance. The composition may contain one of these as the binder, or it may contain two or more of these.

[0080] The binder content in this composition is not particularly limited, but in order to obtain good battery characteristics, it is preferably 0.01 to 3.0% by mass, and more preferably 0.1 to 2.0% by mass, based on 100% by mass of the total composition.

[0081] (Other ingredients) This composition may further contain solvents, dispersants, inorganic fillers, carbon materials other than carbon nanotubes, viscosity modifiers, pH adjusters, antioxidants, defoamers, thickeners, precipitation inhibitors, and antibacterial agents. Any of these components can be commercially available.

[0082] While there are no particular limitations on the solvent, any solvent capable of dissolving or dispersing the components contained in this composition can be used without restriction.

[0083] Examples of solvents include alcohol-based solvents, glycol ether-based solvents, ketone-based solvents, ester-based solvents, amide-based solvents, carbonate-based solvents, or aromatic hydrocarbon-based solvents. More specifically, examples include ethanol, isopropanol, trifluoroethanol, 1-methoxy-2-propanol, ethylene glycol n-butyl ether, methyl ethyl ketone, methyl butyl ketone, methyl isobutyl ketone, diethyl ketone, dipropyl ketone, cyclohexanone, methyl acetate, ethyl acetate, isopropyl acetate, butyl acetate, γ-butyrolactone, N-methylformamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, ethylene carbonate, propylene carbonate, toluene, or xylene.

[0084] When this composition is used for lithium-ion battery electrodes, the solvent is preferably an amide-based solvent. Specific examples of amide-based solvents include formamide, dimethylformamide, diethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, 1,3-dimethyl-2-imidazolidinone, hexamethylphosphate triamide, tetramethylurea, and N,N'-dimethylpropyleneurea. Of these, dimethylformamide, dimethylacetamide, N-methyl-2-pyrrolidone, and 1,3-dimethyl-2-imidazolidinone are preferred because they have excellent binder solubility and are stable with respect to lithium-containing compounds, with N-methyl-2-pyrrolidone being particularly preferred.

[0085] The solvents specifically exemplified here can be used individually or in combination of two or more.

[0086] The solvent content is not limited, but is preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 60% by mass or less, based on 100% by mass of the entire composition.

[0087] While not particularly limited, examples of dispersants include those whose main chain is made of polyester, polyacrylic, polyurethane, polyamine, or polycaprolactone, and whose side chain has polar groups such as amino groups, carboxyl groups, sulfone groups, or hydroxyl groups.

[0088] Examples of polyester-based dispersants include Disparon KS873N, Disparon DA703-50, or Disparon DA7400 (manufactured by Kusumoto Chemical Co., Ltd.).

[0089] Examples of polyacrylic dispersants include Disperbyk-2000, 2001, 2008, 2009, 2010, 2020, 2020N, ​​2022, 2025, 2050, 2070, 2095, 2150, 2151, 2155, 2163, 2164, BYKJET-9130, 9131, 9132, 9133, 9151 (manufactured by Bic Chemie), EfkaPX4310, PX4320, PX4330, PA4401, 4402, PA4403, 4570, 7411, 7477, PX4700, PX4701 (manufactured by BASF), and TREPLUS. Products such as D-1200, D-1410, D-1420, MD-1000 (manufactured by Otsuka Chemical Co., Ltd.), Floren DOPA-15BHFS, 17HF, 22, G-700, 900, NC-500, or GW-1500 (manufactured by Kyoeisha Chemical Co., Ltd.) are used.

[0090] Examples of polyamine-based dispersants include Disparon 1860 (manufactured by Kusumoto Chemical Co., Ltd.).

[0091] Examples of polycaprolactone-based dispersants include Ajisper PB821, PB822, PB881 (manufactured by Ajinomoto Fine Techno Co., Ltd.), Hinoact KF-1000, KF-1500, KF-1700, T-6000, T-7000, T-8000, T-8000E, T-9050 (manufactured by Kawaken Fine Chemical Co., Ltd.), Solsperse 20000, 24000, 32000, 32500, 32550, 32600, 33000, 33500, 34000, 35200, 36000, 37500, 39000, 71000, 76400, 76500, 86000, 88000, J180, J200 (manufactured by Lubrizol), TEGO Dispers 652, 655, 685, 688, 690 (manufactured by Evonik Japan), etc. are used.

[0092] Other commercially available dispersants include, for example, Esream AD-3172M, 374M, 508E, 221P, 221J, DP-2, DJ-2, Marialim AKM-0531, AFB-1521, AAB-0851, SC-0505K, SC-1015F, or SC-0708A (manufactured by NOF Corporation).

[0093] Examples of inorganic fillers include silica, silica-alumina, glass, calcium carbonate, calcium hydroxide, talc, alumina, titania, zirconia, boehmite, antimony oxide, chromium oxide, nickel oxide, copper oxide, tin oxide, titanium oxide, zirconium oxide, indium oxide, zinc oxide, magnesium hydroxide, aluminum hydroxide, hydrotalcite, mica, silver particles, copper particles, gold particles, and aluminum particles.

[0094] Examples of carbon materials other than carbon nanotubes include carbon black, graphite, and vapor-grown carbon fibers.

[0095] The composition is preferably in the form of a paste or slurry. When the composition is in such a relatively high viscosity state, it is easy to mold it into a desired shape, such as a lithium-ion battery electrode.

[0096] (Method for producing this composition) There are no particular limitations on the method for producing this composition. For example, it can be produced by dispersing or dissolving a conductive polymer, a lithium-containing compound, carbon nanotubes, and a binder, along with other components as needed, in a solvent. Alternatively, a conductive additive may be prepared by first dissolving or dispersing the conductive polymer and carbon nanotubes in a solvent, and then dispersing or dissolving the conductive additive, the lithium-containing compound, the binder, and other components as needed, in a solvent. Thus, the conductive polymer according to one aspect of the present invention can be suitably used as a dispersant for carbon nanotubes.

[0097] There are no particular restrictions on the mixer used in the production of this composition; for example, a mortar and pestle, roll mill, ball mill, screw mill, vibratory mill, homogenizer, and a rotary-orbit mixer can be used.

[0098] The uses of this composition are not particularly limited, but for example, it can be used in lithium-ion battery electrodes, lithium-ion capacitor electrodes, lithium primary batteries, and dry cell batteries.

[0099] [Lithium-ion battery electrodes] A lithium-ion battery electrode containing this composition is also included in one aspect of the present invention. Hereinafter, a lithium-ion battery electrode according to one aspect of the present invention may be referred to as "this electrode."

[0100] The electrode can be manufactured using the composition. The electrode may comprise the composition and a current collector. The electrode is obtained by coating the composition onto a current collector and drying the composition. The thickness of the dried layer of the composition is preferably 10 to 200 μm. To form a layer of such thickness on the current collector, for example, the basis weight of the layer of the composition may be 4 to 25 mg / cm². 2 You may set it to that.

[0101] There are no particular restrictions on the method of applying this composition to the current collector; for example, methods such as slit coating, die coating, roll coating, dip coating, blade coating, knife coating, or wire bar coating can be used.

[0102] There are no particular restrictions on the drying method and conditions for this composition; a conventional hot air circulation dryer, vacuum dryer, infrared dryer, or microwave heating dryer can be used. There are also no particular restrictions on the heating temperature; for example, it can be heated and dried at 50 to 150°C. Furthermore, the porous structure can be made uniform by pressing the electrode during or after drying.

[0103] The current collector can be any conductor whose surface in contact with the composition exhibits conductivity. Examples include metals such as copper, gold, aluminum, titanium, nickel, stainless steel, or alloys thereof; conductive metal oxides such as indium oxide or tin oxide; and conductors formed from conductive carbon. There are no particular restrictions on the shape of the current collector; foil, film, sheet, net, expanded metal, perforated metal, or foam forms are acceptable. There are also no particular restrictions on the thickness of the current collector, but it is preferably about 1 to 100 μm.

[0104] The conductivity (electrical conductivity) of this electrode is not particularly limited, but 10 -8 Preferably S / cm or more, 10 -7 It is more preferable that the conductivity is S / cm or higher. The conductivity of this electrode can be measured by the method described later in the examples.

[0105] [Lithium-ion battery] A lithium-ion battery having this electrode is also included in one aspect of the present invention. Hereinafter, a lithium-ion battery according to one aspect of the present invention may be referred to as "this battery." This battery may be a lithium-ion primary battery or a lithium-ion secondary battery.

[0106] This battery can be manufactured using this electrode. This battery has this electrode as either the positive or negative electrode, and may further have an electrode with a polarity opposite to this electrode, a separator, and a non-aqueous electrolyte. When this battery is a lithium-ion secondary battery, it is preferable that this electrode be used as the positive electrode.

[0107] If this battery is equipped with this electrode as the positive electrode, the negative electrode may have a negative electrode active material instead of the lithium-containing compound in this composition. The negative electrode active material is not particularly limited as long as it is a material that can insert and remove lithium ions, and examples include natural graphite, artificial graphite, graphite, mesocarbon microbeads (MCMB), tin and / or tin alloys, tin oxides, silicon and / or silicon alloys, and silicon oxides. If the negative electrode active material is an alloy, the negative electrode active material may contain metallic lithium or a material that alloys with lithium. Examples of materials that alloy with lithium include germanium, tin, lead, zinc, magnesium, sodium, aluminum, gallium, and indium, and alloys thereof.

[0108] The electrode having a polarity opposite to the electrode in this battery is not limited to those described above, and conventionally known general electrodes can be used.

[0109] The separator can be a porous film such as polyolefin. The separator is responsible for shutting down the battery in the event of thermal runaway and is placed between the positive and negative electrodes. There are no particular restrictions on the separator, and known separators can be used. Specific examples of separators include polyethylene microporous membranes, polypropylene microporous membranes, laminated films of polyethylene microporous membranes and polypropylene microporous membranes, nonwoven fabrics made of polyester fibers, aramid fibers, crow fibers, etc., and separators in which ceramics, aramid, or polyvinylidene fluoride are coated on the surface of the microporous membrane.

[0110] The non-aqueous electrolyte may be an electrolyte salt such as LiPF4 dissolved in an organic solvent such as a cyclic carbonate. The inside of this battery is filled with the non-aqueous electrolyte, and lithium ions move from the positive electrode to the negative electrode during charging and from the negative electrode to the positive electrode during discharging.

[0111] There are no particular restrictions on the non-aqueous electrolyte, and known materials can be used. Examples of electrolyte salts in non-aqueous electrolytes include CF3SO3Li, (CF3SO2)2NLi, (CF3SO2)2Cli, LiBF4, LiB(C6H8)4, LiPF4, LiClO4, LiAsF6, LiCl, and LiBr.

[0112] Examples of organic solvents for dissolving the electrolyte salt include ethylene carbonate, vinylene carbonate, propylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl carbonate, 1,2-dimethoxyethane, 1,2-diethoxyethane, γ-butyrolactone, tetrahydrofuran, 1,4-dioxane, anisole, diethyl ether, sulfolane, methylsulfolane, acetonitrile, propionitrile, butyronitrile, valeronitrile, benzonitrile, dimethylformamide, dimethyl sulfoxide, trimethyl phosphate, and triethyl phosphate. The concentration of the electrolyte salt in the non-aqueous electrolyte can be selected, for example, in the range of 0.1 to 5 mol / L, preferably 0.5 to 3 mol / L.

[0113] This battery can be manufactured by known methods, for example, a manufacturing method that includes the step of immersing the electrode in a non-aqueous electrolyte. This manufacturing method may further include the step of immersing an electrode having the opposite polarity to the electrode, and a separator, in a non-aqueous electrolyte. Immersion, as used here, means that at least a part of the electrode, etc., is in contact with the non-aqueous electrolyte.

[0114] 〔summary〕 One aspect of the present invention may include the following [1] to

[10] .

[0115] [1] A conductive polymer composition comprising a conductive polymer having a structural unit represented by the following general formula (1) and a structural unit represented by the following general formula (2), a lithium-containing compound, carbon nanotubes, and a binder.

[0116] [ka] [In the above general formula (1), M + R represents a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. In the general formulas (1) and (2) above, R represents an organic group with a total of 1 to 14 carbon atoms having at least one substituent selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

[0117] [2] The conductive polymer composition according to [1], wherein the lithium-containing compound is at least one selected from the group consisting of lithium cobalt oxide, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, and multi-component lithium.

[0118] [3] The conductive polymer composition according to [1] or [2], wherein the carbon nanotube is at least one selected from the group consisting of single-walled carbon nanotubes and multi-walled carbon nanotubes.

[0119] [4] The conductive polymer composition according to any one of [1] to [3], wherein the binder is at least one selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, polyester and polyvinyl alcohol.

[0120] [5] A conductive polymer composition according to any one of [1] to [4], further comprising a solvent.

[0121] [6] A conductive polymer composition according to any one of [1] to [5], for use as an electrode in a lithium-ion battery.

[0122] A lithium-ion battery electrode characterized by containing the conductive polymer composition described in any of [7], [1], to [6].

[0123] A lithium-ion battery characterized by having the lithium-ion battery electrodes described in [8] and [7].

[0124] A method for manufacturing a lithium-ion battery electrode, characterized by applying a conductive polymer composition described in any of [9], [1] to [6] onto a current collector and then drying it.

[0125] A method for manufacturing a lithium-ion battery, characterized by immersing the lithium-ion battery electrodes described in

[10] [7] in a non-aqueous electrolyte.

[0126] [Additional Notes] The present invention is not limited to the embodiments described above, and various modifications are possible within the scope of the claims. Embodiments obtained by appropriately combining the technical means disclosed in different embodiments are also included in the technical scope of the present invention. [Examples]

[0127] Examples are shown below, but the present invention is not limited to these examples. The analytical instruments and measurement methods used in these examples are listed below. Unless otherwise specified, the "%" or ratio values ​​indicating the content in the following examples and comparative examples are based on weight.

[0128] [Electrode fabrication] This electrode was fabricated to be used as the positive electrode for a lithium-ion battery.

[0129] As the conductive additive, a dispersion of a conductive polymer, carbon nanotubes, and a solvent was used. The conductive polymer was polythiophene [polythiophene (A2)] produced according to the method of Example 2 of Japanese Patent Publication No. 2019-210356. However, R 2 =methyl group, M +=trioctylammonium, m=2. Hereafter abbreviated as "ST". Single-walled carbon nanotubes (Sigma-Aldrich, product number 805033, hereinafter abbreviated as "CNT") were used as the carbon nanotubes. N-methyl-2-pyrrolidone (hereinafter abbreviated as "NMP") was used as the solvent.

[0130] As the positive electrode active material, we used LiFePO4 (manufactured by Hosen Co., Ltd., with carbon coating, hereinafter abbreviated as "LFP"), a lithium-containing compound.

[0131] As a binder, an 8 wt% polyvinylidene fluoride (hereinafter abbreviated as "PVdF") solution dissolved in N-methyl-2-pyrrolidone was used.

[0132] Furthermore, zirconium oxide (ZrO2) beads (manufactured by Nikkatoh Co., Ltd.) were used to uniformly mix and stir the raw materials.

[0133] The electrode according to Example 1 had a final weight ratio of LFP / CNT / PVdF / ST = 97.5 / 0.5 / 2.0 / 1.0. Similarly, the electrode according to Comparative Example 1 also had a final weight ratio of LFP / CNT / PVdF = 97.5 / 0.5 / 2.0. The electrode according to Comparative Example 1 did not contain the conductive polymer according to one embodiment of the present invention.

[0134] The electrode according to Example 2 uses LiMn instead of the LFP of Example 1. 0.6 Fe 0.4 The electrode for Comparative Example 2 was prepared in the same manner as in Example 1, except that PO4 (hereinafter abbreviated as "LMFP") was used instead. The electrode for Comparative Example 2 was also prepared in the same manner as in Example 1, except that LFP was replaced with LMFP in Comparative Example 1.

[0135] To obtain such electrodes, each material was mixed according to the preparation amounts shown in Table 1 below. The values ​​in Table 1, except for the solid content concentration, are shown in parts by weight per 1 part by weight of LFP or LMFP, and the solid content concentration is shown as weight percent when the entire electrode is considered to be 100% by weight.

[0136] [Table 1]

[0137] Of the materials shown in Table 1, all materials except for the additional NMP were weighed using an ointment container. The weighed materials were mixed using a rotary-orbit mixer, Awatori Rentaro (registered trademark, manufactured by Shinky, ARE-310). The resulting mixture was mixed with additional NMP and mixed again to obtain the composition.

[0138] After removing the zirconium oxide (ZrO2) beads from the composition, it was applied to aluminum foil (20 μm thick) which served as the current collector. The gap was set to 150-200 μm. After application, it was dried on a hot plate at 120°C for 20 minutes. The resulting electrodes were punched out into circular shapes with a diameter of 15.96 mm and stamped at 3 t / cm². 2 It was pressed under load (using an 18mmΦ mold).

[0139] [Measurement of electrical conductivity] The 1kHz resistance of the obtained electrodes was measured using a measuring jig (SH-2Z type 4-terminal sample holder, manufactured by Toyo Technica). Electrode thickness and area (2cm²) 2 The conductivity (electrical conductivity) was calculated from the following formula (1). Conductivity (S / cm) = Electrode thickness / (1kHz resistance × Electrode area) (1)

[0140] [Manufacturing of lithium-ion batteries] A CR2032 coin cell was used to arrange the electrode (positive electrode) according to Example 1, Example 2, Comparative Example 1, or Comparative Example 2, and a metallic lithium negative electrode. A 1M LiPF6EC-DMC (1:2 vol / vol) non-aqueous electrolyte was then added to fabricate lithium-ion batteries according to Example 1, Example 2, Comparative Example 1, and Comparative Example 2.

[0141] [Charge / Discharge Test] In the charge-discharge tests of lithium-ion batteries in Example 1, Example 2, Comparative Example 1, and Comparative Example 2, the lithium-ion batteries were subjected to a voltage of 4.2-2.5V (constant current charging - constant current discharging) at room temperature (24°C).

[0142] As an initial cycle verification test, 10 charge and discharge cycles were performed at a charge and discharge rate of 0.2C for N=3. Next, a rate characteristic measurement test was performed using the lithium-ion batteries after the initial cycle verification test. For the rate characteristic measurement test, the charge rate was fixed at 0.2C, and the discharge rates were set to 1C, 5C, and 10C, with 2 charge and discharge cycles performed in each of these conditions for N=3.

[0143] The ratio of the discharge capacity at rate 10C during the second cycle to the discharge capacity at rate 0.2C during the tenth cycle of the initial cycle confirmation test was calculated as the 10C rate characteristic. The measurement results for discharge capacity and 10C rate characteristic are shown as the average values ​​of three samples.

[0144] 〔result〕 Table 2 below shows the conductivity of the electrodes (positive electrodes) for Example 1, Example 2, Comparative Example 1, and Comparative Example 2, as well as the discharge capacity and 10C rate characteristics of the lithium-ion batteries.

[0145] [Table 2]

[0146] As shown in Table 2, the electrodes (positive electrodes) in Example 1 and Example 2 showed better conductivity than Comparative Examples 1 and 2. Furthermore, the lithium-ion batteries in Example 1 and Example 2 also showed good 10C rate characteristics. In addition, the lithium-ion batteries in Example 1 and Example 2 showed 10-cycle characteristics that were equal to or better than those of Comparative Examples 1 and 2.

[0147] The results above demonstrate that by using a conductive polymer composition according to one aspect of the present invention, lithium-ion battery electrodes with excellent conductivity can be obtained, and lithium-ion batteries with excellent rate characteristics and cycle characteristics can be realized. [Industrial applicability]

[0148] A conductive polymer composition according to one aspect of the present invention can be used, for example, in lithium-ion battery electrodes.

Claims

1. A conductive polymer composition characterized by comprising a conductive polymer containing polythiophene (A) having at least one structural unit selected from the group consisting of structural units represented by the following general formula (1) and structural units represented by the following general formula (2), a lithium-containing compound, carbon nanotubes, and a binder. 【Chemistry 1】 [In the above general formula (1), M ＋ R represents a hydrogen ion, an alkali metal ion, a conjugate acid of an amine compound, or a quaternary ammonium cation. In the general formulas (1) and (2) above, R represents an organic group having 1 to 14 carbon atoms and having at least one substituent selected from the group consisting of a sulfonic acid group and a phosphonic acid group.

2. The conductive polymer composition according to claim 1, wherein the lithium-containing compound is at least one selected from the group consisting of lithium cobalt oxide, lithium iron phosphate, lithium manganese phosphate, lithium iron manganese phosphate, and multi-component lithium.

3. The conductive polymer composition according to claim 1, wherein the carbon nanotube is at least one selected from the group consisting of single-walled carbon nanotubes and multi-walled carbon nanotubes.

4. The conductive polymer composition according to claim 1, wherein the binder is at least one selected from the group consisting of polyvinylidene fluoride, polytetrafluoroethylene, polyester, and polyvinyl alcohol.

5. The conductive polymer composition according to claim 1, further comprising a solvent.

6. A conductive polymer composition according to any one of claims 1 to 5, for use as an electrode in a lithium-ion battery.

7. A lithium-ion battery electrode characterized by comprising the conductive polymer composition described in claim 6.

8. A lithium-ion battery characterized by having the lithium-ion battery electrode described in claim 7.

9. A method for manufacturing a lithium-ion battery electrode, characterized by applying the conductive polymer composition described in claim 6 onto a current collector and then drying it.

10. A method for manufacturing a lithium-ion battery, characterized by immersing the lithium-ion battery electrode described in claim 7 in a non-aqueous electrolyte.

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