Dispersion comprising carbon material, and lithium sulfide secondary battery using same

Abstract

The present invention relates to a dispersion comprising a copolymer and a non-polar solvent, a positive electrode slurry composition, a positive electrode, and a lithium secondary battery. The use of the dispersion according to the present invention enables a carbon material to be dispersed in a non-polar solvent and thus enables manufacturing of a lithium sulfide secondary battery comprising a carbon material.

Description

A dispersion containing carbon material and a lithium sulfide secondary battery using the same

[0001] The present invention relates to a dispersion comprising a copolymer and a non-polar solvent, an anode slurry composition, an anode, and a lithium secondary battery, wherein the lithium secondary battery may be a lithium sulfide secondary battery.

[0002]

[0003] Carbon materials possess unique mechanical, electrical, and thermal properties, so they are used in various fields such as electronics, biotechnology, and medicine. Recently, in addition to conventional carbon materials such as graphite, activated carbon, and carbon black, carbon nanomaterials such as carbon nanotubes, fullerenes, and graphene are gaining attention.

[0004] In order to use carbon materials efficiently, they must be effectively dispersed in matrices of various materials. However, carbon materials, particularly carbon nanomaterials, tend to aggregate within the matrix due to strong Van der Waals forces. When carbon materials aggregate within the matrix, they are unable to exhibit their unique properties, and problems such as reduced uniformity may occur.

[0005] Methods for dispersing carbon materials include mechanical dispersion using physical forces such as ultrasound, milling, and high shear force, dispersion using dispersants, and dispersion by surface modification.

[0006] However, there is a problem in that mechanical dispersion and dispersion by surface modification are prone to causing damage to carbon materials, and such damage significantly degrades the inherent properties of the carbon materials (e.g., electrical conductivity, thermal conductivity, etc.).

[0007] Therefore, the dispersion of carbon materials using dispersants is being actively studied, and in particular, to efficiently disperse carbon nanomaterials such as carbon nanotubes, research is being conducted on wrapping carbon nanomaterials with polymer dispersants or utilizing the π-π interaction between the p orbitals of the aromatic rings of polymer dispersants and the p orbitals of carbon nanomaterials.

[0008] Research is also being conducted to use these carbon nanomaterials in the field of secondary batteries.

[0009] Lithium-ion batteries possess high energy density and are easy to design, so they are being adopted and used as the primary power source for mobile electronic devices, and their scope of application is expanding further to include electric vehicles and power storage devices for new and renewable energy.

[0010] In particular, active research and development are being conducted on lithium sulfide secondary batteries that use sulfur-based materials with SS bonds (Sulfur-Sulfur Bonds) as the positive electrode active material and lithium metal as the negative electrode active material.

[0011] Sulfur, the main material of lithium sulfide secondary batteries, has the advantages of being very abundant compared to lithium, being non-toxic, and having a low weight per atom.

[0012] In lithium sulfide secondary batteries, during discharge, lithium, the negative electrode active material, releases electrons and becomes ionized, undergoing oxidation, while sulfur-based materials, the positive electrode active material, accept electrons and are reduced.

[0013] Here, the oxidation reaction of lithium is the process in which lithium metal releases electrons and is converted into a lithium cation.

[0014] In addition, the reduction reaction of sulfur is a process in which SS bonds accept two electrons and are converted into the form of sulfur anions.

[0015] Sulfur before discharge has a cyclic S8 structure and, through a reduction reaction, becomes lithium polysulfide (LiS₂). x It is converted into ). In addition, when lithium polysulfide is completely reduced, lithium sulfide (Li2S) is produced.

[0016] Although lithium sulfide secondary batteries have advantages in energy storage density, various problems are known in their practical applications, such as the instability of lithium metal, low conductivity of the cathode, sublimation of sulfur-based materials during electrode manufacturing, and loss of sulfur-based materials during repeated charging and discharging.

[0017] In particular, sulfide-based electrolytes lose their electrolyte properties as their structure is damaged when in contact with polar solvents, making it impossible to perform carbon nanotube dispersion processes using conventional polar solvents. Therefore, there is a need to develop a novel dispersion containing a non-polar solvent and a high-efficiency lithium sulfide secondary battery manufactured using the novel dispersion.

[0018]

[0019] [Prior Art Literature]

[0020] [Patent Literature]

[0021] (Patent Document 1) Korean Published Patent Application No. 10-2019-0011943

[0022]

[0023] The objective of the present invention to solve the problems of the prior art is to provide a dispersion solution containing a non-polar solvent that can disperse carbon materials without damaging the structure of the electrolyte.

[0024] In addition, the present invention aims to provide a slurry composition for an anode using the dispersion and an anode, and to provide a high-efficiency, high-capacity lithium sulfide secondary battery including the anode.

[0025] However, the problems that the present invention aims to solve are not limited to those mentioned above, and other problems not mentioned but intended to be solved will be clearly understood by those skilled in the art to which the present invention belongs from the content to be described below.

[0026]

[0027] One aspect of the present invention comprises a copolymer and a nonpolar solvent, and

[0028] The copolymer comprises acrylate-based monomer units containing linear or branched aliphatic hydrocarbons having 5 to 22 carbon atoms;

[0029] A monomer unit comprising one or more substituted or unsubstituted aromatic rings; and

[0030] Cyano(CN), Pyrrolidone (NC4H6O), Carboxylic Acid (COOH), Caprolactam (C5H 10 A polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2);

[0031] Provides a dispersion.

[0032] Another aspect of the present invention is the dispersion; and

[0033] A positive electrode active material containing a sulfur element; comprising

[0034] Provides a slurry composition for an anode.

[0035] Another aspect of the present invention is a method of forming an anode active material layer by applying the anode slurry composition onto a current collector.

[0036] Provides a positive electrode.

[0037] The remaining aspect of the present invention is comprising the above-mentioned anode,

[0038] Provides a lithium secondary battery.

[0039]

[0040] By using the dispersion of the present invention, carbon nanotubes can be dispersed even in a non-polar solvent, and by using this, a slurry composition for the cathode and a cathode can be prepared to manufacture a lithium sulfide secondary battery with high efficiency, large capacity, and excellent safety.

[0041]

[0042] Figure 1 is a photograph showing samples of solutions in which the polymers (dispersants) of Preparation Examples 1 to 5 and Comparative Preparation Examples 1 to 4 were mixed with a butyl butyrate solution, arranged from left to right.

[0043] Figure 2 is a graph showing the current per applied voltage measured by linear sweep voltammetry using Electronic Impedance Spectroscopy (EIS) equipment for measurement samples prepared using the polymer (dispersant) of Preparation Examples 1 and 2 and Comparative Preparation Example 4.

[0044]

[0045] Hereinafter, the operation and effects of the invention will be described in more detail through specific embodiments and drawings. However, these embodiments are merely examples of the invention and do not define the scope of the invention.

[0046] Prior to this, terms and words used in this specification and claims should not be interpreted as being limited to their ordinary or dictionary meanings, but should be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0047] Therefore, it should be understood that the configuration of the embodiments described in this specification is merely one of the most preferred embodiments of the present invention and does not represent all of the technical ideas of the present invention, and that various equivalents and modifications that can replace them may exist at the time of filing this application.

[0048] In this specification, singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising,” “comprising,” or “having” are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0049] Where various parameters in this specification are given as an enumeration of ranges, preferred ranges, preferred upper limits, and preferred lower limits, it should be understood that any pair of any upper range limit or preferred value and any lower range limit or preferred value specifically discloses all ranges formed by any pair of any upper range limit or preferred value, regardless of whether the range is disclosed separately.

[0050] Where a range of numerical values ​​is mentioned in this specification, unless otherwise described, the range is intended to include its endpoint and all integers and fractions within the range.

[0051] The scope of the present invention is not intended to be limited to specific values ​​mentioned when defining the scope.

[0052] In the present specification, "a to b" and "a~b" indicating numerical ranges are defined as ≥a and ≤b.

[0053] Embodiments of the present invention have been described in detail below, but the present invention is not limited thereto.

[0054] A dispersion according to one aspect of the present invention may comprise a copolymer and a nonpolar solvent, wherein the copolymer comprises an acrylate-based monomer unit comprising a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms, a monomer unit comprising one or more substituted or unsubstituted aromatic rings, and cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), caprolactam (C5H 10 It may include a polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2).

[0055] In one embodiment, the monomer unit comprising one or more substituted or unsubstituted aromatic rings may include an acrylate-based monomer unit comprising one or more substituted or unsubstituted aromatic rings and a vinyl-based monomer unit comprising one or more substituted or unsubstituted aromatic rings.

[0056] In one embodiment, the copolymer comprises, based on 100 mol% of the copolymer, 30 mol% or more and 85 mol% or less of acrylate-based monomer units comprising linear or branched aliphatic hydrocarbons having 5 to 22 carbon atoms, 10 mol% or more and 60 mol% or less of one or more substituted or unsubstituted aromatic rings, and 5 mol% or more and 25 mol% or less of cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), and caprolactam (C5H 10 It may include a polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2).

[0057] The above acrylate-based monomer unit containing a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms can wrap and disperse carbon materials (especially carbon nanomaterials such as carbon nanotubes) and lower the viscosity of the dispersion.

[0058] If the number of carbon atoms in the above linear or branched aliphatic hydrocarbon is less than 5, it cannot sufficiently wrap the carbon material (especially carbon nanotubes), so the dispersion power is reduced, and if it exceeds 22, the polarity may be excessively low.

[0059] The content of the acrylate-based monomer unit containing the linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms may be 30 mol% or more and 85 mol% or less, based on the total content of the entire copolymer of 100 mol%.

[0060] For example, the content of the acrylate-based monomer unit containing the linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms may be 33 mol% or more and 84 mol% or less, 35 mol% or more and 83 mol% or less, 37 mol% or more and 82 mol% or less, or 39 mol% or more and 81 mol% or less, based on the total content of 100 mol% of the total copolymer.

[0061] If the content of the acrylate-series monomer unit containing the linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms is lower than that of the present invention, the solubility is low and it may not dissolve in a non-polar solvent, and if it is higher than that of the present invention, the molar ratio of the acrylate-series monomer unit containing one or more substituted or unsubstituted aromatic rings is relatively low, so the interaction with carbon nanotubes is weakened and dispersibility may be reduced.

[0062] The monomer unit containing one or more substituted or unsubstituted aromatic rings can act as a dispersion through π-π interactions with carbon materials (especially carbon nanomaterials such as carbon nanotubes).

[0063] The content of monomer units containing one or more substituted or unsubstituted aromatic rings may be 10 mol% or more and 60 mol% or less, based on the total content of the entire copolymer of 100 mol%.

[0064] For example, the content of monomer units containing one or more substituted or unsubstituted aromatic rings may be 12 mol% or more and 55 mol% or less, 13 mol% or more and 50 mol% or less, 14 mol% or more and 45 mol% or less, or 15 mol% or more and 40 mol% or less, based on the total content of 100 mol% of the total copolymer.

[0065] If the content of monomer units containing one or more substituted or unsubstituted aromatic rings is lower than that of the present invention, the interaction with carbon nanotubes is weakened and dispersibility may be reduced, and if it is higher than that of the present invention, the molar ratio of acrylate-based monomer units containing linear or branched aliphatic hydrocarbons having 5 to 22 carbon atoms is relatively low, so they may not dissolve in non-polar solvents or dispersibility may be reduced.

[0066] The above cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), and caprolactam (C5H 10 Polar monomer units comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2) can serve to balance the electrostatic charge in the dispersion.

[0067] The above cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), and caprolactam (C5H 10The polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2) may be acrylic acid, methacrylic acid, acrylonitrile, N-vinylpyrrolidone, N-vinylcaprolactam, 4-acryloyl morpholine, 3-acryloyl-2-oxazolidinone, or copolymers thereof.

[0068] For example, the above cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), caprolactam (C5H 10 The polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2) may be acrylic acid, acrylonitrile, or a combination of acrylic acid and acrylonitrile, and in the case of a combination of acrylic acid and acrylonitrile, the molar ratio of the acrylic acid and the acrylonitrile (moles of acrylic acid:moles of acrylonitrile) may be 0.5 to 3:1.

[0069] For example, the above cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), caprolactam (C5H 10 When a polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2) is a combination of acrylic acid and acrylonitrile, the molar ratio of acrylic acid and acrylonitrile may be 0.8:1, 1.0:1, 1.5:1, 2:1, 2.5:1, or 3:1.

[0070] The above cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), and caprolactam (C5H 10The content of polar monomer units comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2) may be 5 mol% or more and 25 mol% or less, based on the total content of the entire copolymer 100 mol%.

[0071] For example, the above cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), caprolactam (C5H 10 The content of polar monomer units comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2) may be 6 mol% or more and 24 mol% or less, 7 mol% or more and 23 mol% or less, 8 mol% or more and 22 mol% or less, 9 mol% or more and 21 mol% or less, or 10 mol% or more and 20 mol% or less, based on the total content of the entire copolymer of 100 mol%.

[0072] The above cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), and caprolactam (C5H 10 If the content of a polar monomer unit comprising one or more selected from the group consisting of CNO, morpholine (C4H8NO), and oxazolidone (C3H4NO2) is lower than that of the present invention, the electrostatic balance within the dispersion may be unbalanced, which may result in reduced dispersibility, and if it exceeds that of the present invention, the electrochemical stability in the solid electrolyte may be reduced due to polarity.

[0073] In one embodiment, the molar ratio of the acrylate-based monomer unit containing one or more substituted or unsubstituted aromatic rings and the vinyl-based monomer unit containing one or more substituted or unsubstituted aromatic rings (moles of the acrylate-based monomer unit containing one or more substituted or unsubstituted aromatic rings:moles of the vinyl-based monomer unit containing one or more substituted or unsubstituted aromatic rings) may be 1 to 4:1.

[0074] For example, the molar ratio of the acrylate-based monomer unit containing one or more substituted or unsubstituted aromatic rings and the vinyl-based monomer unit containing one or more substituted or unsubstituted aromatic rings may be 1.1:1, 1.5:1, 2:1, 2.5:1, 3:1, or 3.5:1.

[0075] In one embodiment, the copolymer may be represented by the following chemical formula 1.

[0076]

[0077] [Chemical Formula 1]

[0078]

[0079]

[0080] In the above chemical formula 1,

[0081] R1 to R 12 They are the same or different from each other, and each independently is hydrogen, a linear or branched hydrocarbon having 1 to 4 carbon atoms, and

[0082] R'1 is a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms, and

[0083] R'2 comprises one or more substituted or unsubstituted aromatic rings, and

[0084] R'3 is cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), caprolactam (C5H 10One or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2), and

[0085] R'4 comprises one or more substituted or unsubstituted aromatic rings, and

[0086] 30 mol%≤l≤85 mol%, 5 mol%≤m≤30 mol%, 5 mol%≤n≤25 mol% and 5 mol%≤o≤30 mol%.

[0087] That is, the monomer unit (1) of the above chemical formula 1 may correspond to an acrylate-series monomer unit comprising a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms, the monomer unit (2) of the above chemical formula 1 may correspond to an acrylate-series monomer unit comprising one or more substituted or unsubstituted aromatic rings, and the monomer unit (3) of the above chemical formula 1 may correspond to cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), caprolactam (C5H 10 It may correspond to a polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO) and oxazolidone (C3H4NO2), and each monomer unit (4) of Formula 1 may correspond to a vinyl series monomer unit comprising one or more substituted or unsubstituted aromatic rings.

[0088] In one embodiment, R'1 of Formula 1 is n-pentyl, n-hexyl, n-heptyl, n-octyl, 2-ethylhexyl, n-nonyl, n-decyl, n-undecyl, lauryl, n-dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, cetyl, n-hexadecyl, n-heptadecyl, stearyl, n-octadecyl, n-nonadecyl, n-icosyl, n-henicosyl, n-docosyl, n-bihenyl, iso-pentyl, iso-heptyl, iso-octyl, iso-nonyl, iso-decyl, iso-undecyl, iso-dodecyl, iso-tridecyl, iso-tetradecyl, iso-pentadecyl, iso-cetyl, iso-hexadecyl, iso-heptadecyl, iso-stearyl, It may be one or more selected from the group consisting of iso-octadecyl, iso-nonadecyl, iso-icosyl, iso-henicosyl, iso-docosyl, and iso-bihenyl.

[0089] That is, as a monomer containing R'1, only one type of monomer including a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms may be used, or two or more types of monomers including a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms may be used together.

[0090] The above acrylate series monomer comprising a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms may be an acrylate and / or methacrylate comprising a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms, and the acrylate series monomer comprising one or more substituted or unsubstituted aromatic rings may be an acrylate and / or methacrylate comprising one or more substituted or unsubstituted aromatic rings.

[0091] (Meth)acrylate refers to acrylate or methacrylate.

[0092] For example, the acrylate series monomer comprising the linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms is n-pentyl (meth)acrylate, n-heptyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-nonyl (meth)acrylate, n-decyl (meth)acrylate, n-undecyl (meth)acrylate, lauryl (meth)acrylate, n-dodecyl (meth)acrylate (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, n-pentadecyl (meth)acrylate, cetyl (meth)acrylate, n-hexadecyl (meth)acrylate, n-heptadecyl (meth)acrylate, stearyl (meth)acrylate, n-nonadecyl (meth)acrylate, n-eicosyl (meth)acrylate, n-heneicosyl (meth)acrylate, n-dococyl (meth)acrylate, n-behenyl (meth)acrylate, iso-pentyl (meth)acrylate,iso-heptyl (meth)acrylate, iso-octyl (meth)acrylate, iso-nonyl (meth)acrylate, iso-decyl (meth)acrylate, iso-undecyl (meth)acrylate, iso-dodecyl (meth)acrylate, iso-tridecyl (meth)acrylate, iso-tetradecyl (meth)acrylate, iso-pentadecyl (meth)acrylate iso-cetyl (meth)acrylate, iso-hexadecyl (meth)acrylate, iso-heptadecyl (meth)acrylate, iso-stearyl (meth)acrylate, iso-nonadecyl (meth)acrylate, iso-eicosyl (meth)acrylate, iso-heneicosyl (meth)acrylate, iso-docosyl (meth)acrylate, iso-behenyl (meth)acrylate, or their It may be a copolymer, but is not limited thereto.

[0093] For example, the acrylate series monomers comprising the linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms may be stearyl acrylate and behenyl acrylate, and the molar ratio of the stearyl acrylate and behenyl acrylate (moles of stearyl acrylate:moles of behenyl acrylate) may be 0.5 to 2:1.

[0094] For example, the molar ratio of stearyl acrylate and behenyl acrylate can be 0.7:1, 0.83:1, 1:1, 1.5:1, or 1.8:1.

[0095] In one embodiment, R'2 and R'4 of the above formula 1 may be the same or different from each other and may each include one or more selected from the group consisting of benzyl, phenyl, phenoxy, naphthalene, anthracene, and pyrene, which are independently substituted or unsubstituted.

[0096] In one embodiment, R'2 may include one or more selected from the group consisting of benzyl, 3-phenoxybenzyl, σ-phenyl phenoxy ethyl, biphenyl methyl, 1-naphthyl, 2-naphthyl, 9-anthracene methyl, and 1-pyrene methyl, and R'4 may include phenyl, but is not limited thereto.

[0097] That is, R'2 and R'4 may be the same or different from each other and each may include one or more aromatic rings that are independently substituted or not substituted.

[0098] Meanwhile, R'2 may be a hydrocarbon containing one or more substituted or unsubstituted aromatic rings.

[0099] In addition, only one type of monomer containing one or more aromatic rings that are substituted or not substituted with a monomer containing R'2 may be used, or two or more types of monomers containing one or more aromatic rings that are substituted or not substituted may be used together.

[0100] For example, when the above aromatic ring is substituted, the substituent may be a linear or branched hydrocarbon having 1 to 4 carbon atoms, a substituent connected through oxygen (O) (e.g., a substituted or unsubstituted aromatic ring connected through ether, etc.).

[0101] In one embodiment, the monomer comprising R'2 is benzyl acrylate, 3-phenoxybenzyl acrylate, σ-phenylphenoxyethyl acrylate, σ-phenylphenoxyethyl methacrylate, (1-pyrene) 2-methyl-2-propenoate, 1-naphthyl acrylate, 1-naphthyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, 9-anthracene methyl acrylate. It may be one or more selected from the group consisting of acrylate and 9-anthracene methyl methacrylate, and the monomer containing R'4 may be styrene.

[0102] In one embodiment, the monomer containing R'2 is benzyl acrylate and 3-phenoxybenzyl acrylate, and the monomer containing R'4 may be styrene.

[0103] In one embodiment, the non-polar solvent may be butyl butyrate, chloroform, hexane, dimethyl ether, diethyl ether, toluene, benzene, carbon tetrachloride, carbon disulfide, turpentine, tetrahydrofuran (THF), 1,4-dioxane, diglyme, or a combination thereof.

[0104] For example, the above nonpolar solvent may be butyl butyrate.

[0105] A slurry composition for an anode can be prepared by including a dispersion containing the above-mentioned nonpolar solvent and an anode active material.

[0106] At this time, the positive active material included in the above positive slurry composition may contain a sulfur element.

[0107] A positive electrode and a lithium secondary battery can be manufactured using the above positive electrode slurry composition.

[0108] Accordingly, the lithium secondary battery manufactured using the above-mentioned non-polar solvent may be a lithium sulfide secondary battery containing a positive electrode active material containing a sulfur element, and the lithium sulfide secondary battery may have superior battery efficiency, capacity, and safety compared to conventional lithium secondary batteries.

[0109] In one embodiment, the copolymer may be a random or block copolymer depending on the synthesis process.

[0110] In one embodiment, the dispersion may further include a carbon material, and the carbon material may be graphite, activated carbon, carbon black, single-walled carbon nanotubes, thin-walled carbon nanotubes, multi-walled carbon nanotubes, fullerene or graphene or a combination thereof, but is not limited thereto.

[0111] Meanwhile, the content of the copolymer in the dispersion may be 0.1 to 0.5 times the content of the carbon material.

[0112] If the content of the copolymer is less than 0.1 times the carbon material content, a sufficient dispersion effect cannot be obtained, and the carbon material cannot be efficiently dispersed.

[0113] In addition, if the carbon material content of the copolymer is greater than 0.5 times, the proportion of auxiliary materials in the battery increases, which can reduce energy density.

[0114] The copolymer of the present invention has excellent dispersion power, so it is possible to produce a dispersion of carbon materials (especially carbon nanotubes) having a uniform and dense particle size.

[0115] Meanwhile, based on 100% by weight of the dispersion, the carbon material (in particular, carbon nanotubes) may be included in an amount of 1 to 10% by weight.

[0116] If the content of carbon material in the dispersion is less than 1 weight%, the solid content of the electrode slurry is low, and if it exceeds 10 weight%, the viscosity is very high and dispersion is poor, making it difficult to produce a high-quality dispersion.

[0117] Based on its excellent dispersion power, the copolymer of the present invention can reduce the particle size of carbon nanotubes in the dispersion and lower the viscosity of the dispersion, as well as shorten the dispersion process time.

[0118] In one embodiment, when the total solid content is 3.75% by weight based on 100% by weight of the total weight of the dispersion, the viscosity of the dispersion at a shear rate of 1.0 / s is 5,000 cps or more and 30,000 cps or less, and the average particle size (D50) of the carbon material may be 13 μm or less.

[0119] For example, when the above dispersion contains 3.75 weight% of solids, the viscosity of the dispersion at a shear rate of 1.0 / s may be 6,000 cps or more and 28,000 cps or less, 6,500 cps or more and 26,000 cps or less, 7,000 cps or more and 24,000 cps or less, 7,500 cps or more and 22,000 cps or less, or 8,000 cps or more and 21,000 cps or less.

[0120] If the viscosity of the above dispersion exceeds that of the present invention, dispersion is not effective, making it difficult to produce a high-quality dispersion, and the electrode production speed may be reduced.

[0121] For example, the average particle size (D50) of the carbon material may be 3 μm or more and 12.5 μm or less, 4 μm or more and 12.0 μm or less, 5 μm or more and 11.0 μm or less, or 5.5 μm or more and 10.0 μm or less.

[0122] A positive electrode slurry composition according to another aspect of the present invention may include the dispersion and a positive electrode active material comprising a sulfur element.

[0123] The carbon nanotubes may be included in the anode slurry composition in an amount of 0.001 to 0.1 times, preferably 0.003 to 0.1 times, of the anode active material content.

[0124] If the carbon nanotube content is less than 0.001 times the positive active material content, the conductivity within the electrode active material is reduced, thereby degrading the output characteristics, and if it is more than 0.1 times the positive active material content, the positive active material content is lowered, which may reduce the capacity.

[0125] The positive electrode active material used in the present invention may be any positive electrode active material available in the relevant technical field. Specific examples of such positive electrode active materials may include sulfur or disulfide compounds, and Li2S n (n≥1), organic sulfur compounds, carbon-sulfur polymers ((C2S x ) n ), especially it could be S8.

[0126] For example, in a lithium sulfide secondary battery, during discharge, lithium, which is the negative electrode active material, can be oxidized as it releases electrons and becomes ionized, while sulfur-based materials, which are the positive electrode active materials, can be reduced by accepting electrons.

[0127] Here, the oxidation reaction of lithium can be a process in which lithium metal releases electrons and is converted into a lithium cation.

[0128] In addition, the reduction reaction of sulfur may be a process in which the SS bond accepts two electrons and is converted into a sulfur anion.

[0129] Sulfur before discharge can have a cyclic S8 structure, and through a reduction reaction, it becomes lithium polysulfide (LiS₂). x It can be converted into ). In addition, if lithium polysulfide is completely reduced, lithium sulfide (Li2S) may be produced.

[0130] In addition, the above positive active material layer may additionally include a binder, a conductive material, a filler, and other additives in addition to the positive active material.

[0131] The above positive active material may be included in an amount of 90 to 99 weight percent based on solid content. If the content of the active material is low, the battery cannot produce a high capacity, and if the content of the active material is excessively high, the content of binder, conductive material, etc. becomes relatively low, so electrode adhesion and conductivity may be reduced.

[0132] The above conductive material is not particularly limited and can be appropriately selected depending on the type of battery and capacitor. For example, in the case of a lithium-ion secondary battery, carbon such as graphite or activated carbon is used, and in the case of a nickel-hydrogen secondary battery, cobalt oxide is used, and nickel powder, cobalt oxide, titanium oxide, carbon, etc. can be used for the negative electrode.

[0133] Examples of the above carbons include acetylene black, furnace black, graphite, carbon fiber, and fullerenes.

[0134] The amount of the conductive material used is typically 1 to 20 parts by weight, preferably 2 to 10 parts by weight, based on 100 parts by weight of the electrode active material.

[0135] Since reducing the content of conductive material and increasing the content of cathode active material can improve the energy density of a secondary battery, it is important to achieve high efficiency even when using the same amount of conductive material.

[0136] When conductive materials used in electrode slurries for secondary batteries are dispersed in small and uniform sizes, the conductivity efficiency increases, which lowers resistance within the battery, exhibits improved output characteristics, and enhances lifespan characteristics. If they are dispersed in large and non-uniform sizes, even when the same amount is used, the binding characteristics and conductivity decrease, which adversely affects the battery's lifespan and output characteristics. Additionally, if the viscosity of the dispersion is low, the solid content of the slurry can be increased, thereby improving the electrode production speed.

[0137] As a binder for a positive electrode of a secondary battery, any one or two or more of poly(meth)acrylic acid, poly(meth)acrylamide, carboxymethylcellulose, polyvinylidene fluoride, copolymer of polyhexafluoropropylene-polyvinylidene fluoride (P(VdF / HFP)), poly(vinyl acetate), polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, alkylated polyethylene oxide, polyvinyl ether, poly(methyl methacrylate), poly(ethyl acrylate), polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, styrene-butadiene rubber, acrylonitrile-butadiene rubber, and copolymers thereof may be selected and used, but are not limited thereto.

[0138] The content of the above binder in the anode slurry composition is preferably 0.3% by weight or more and 10% by weight or less based on the solid content, and more preferably 0.7% by weight or more and 8% by weight or less. With a content of less than 0.3% by weight, it is difficult to expect sufficient binding strength in the current collector and electrode composition, and with a content exceeding 10% by weight, the proportion of the binder in the electrode slurry composition increases, which may reduce the battery capacity.

[0139] According to another aspect of the present invention, the anode may be formed by applying the anode slurry composition onto a current collector to form an anode active material layer.

[0140] The above anode can be manufactured through the steps of (a) preparing a composition for forming an anode active material layer comprising an anode active material and a copolymer of the present invention, and (b) applying the composition for forming an anode active material layer onto an anode current collector and drying it.

[0141] The above composition for forming the positive electrode active material layer can be mixed by stirring in a conventional manner using a conventional mixer, such as a sinker mixer, P / D mixer, high-speed shear mixer, homo mixer, etc.

[0142] The above step (b) is a step of manufacturing a positive electrode for a lithium secondary battery by applying the composition for forming a positive electrode active material layer prepared in step (a) onto a positive electrode current collector and then drying it.

[0143] At this time, there are no limitations on the method of applying the above-mentioned slurry-type composition for forming the positive electrode active material layer, and it can be manufactured by performing, for example, doctor blade coating, dip coating, gravure coating, slit die coating, spin coating, comma coating, bar coating, reverse roll coating, screen coating, cap coating, etc.

[0144] A positive electrode for a secondary battery (especially a lithium secondary battery) can be manufactured by drying after coating to finally form a positive electrode active material layer.

[0145] The above current collector can be used if it is conductive and does not chemically react with the electrode forming slurry. Typical examples include aluminum foil and copper foil. A current collector with a thickness between 3 and 50 micrometers can be selected and used.

[0146] A lithium secondary battery according to another aspect of the present invention may include the above-mentioned positive electrode.

[0147] Therefore, the above lithium secondary battery may be a lithium sulfide secondary battery.

[0148] Specifically, a secondary battery comprising a positive electrode, a negative electrode, and a solid electrolyte including the copolymer can be manufactured.

[0149] The electrolyte of the above-mentioned lithium secondary battery is a non-aqueous electrolyte containing a lithium salt, composed of a lithium salt and a solvent, and the solvent used is a non-aqueous organic solvent, an organic solid electrolyte, and an inorganic solid electrolyte.

[0150] The above lithium salt is a substance that dissolves well in the above-mentioned non-aqueous electrolyte, for example, lithium chloride (LiCl), lithium bromide (LiBr), lithium iodide (LiI), lithium perchlorate (LiClO4), lithium tetrafluoroborate (LiBF4), LiB 10 Cl 10 Lithium hexafluorophosphate (LiPF6), lithium hexafluoroalsenate (LiAsF6), lithium hexfluoroantimonate (LiSbF6), lithium tetrachloroaluminate (LiAlCl4), lithium thiocyanate (LiSCN), LiC4BO8, LiCF3CO2, LiCH3SO3, lithium trifluoromethanesulfonate (LiCF3SO3), LiN(SO2CF3)2, lithium bis(fluorosulfonyl)imide (LiN(SO2F)2), LiN(SO2C2F5)2, LiC4F9SO3, LiC(CF3SO2)3, (CF3SO2)·2NLi, lithium chloroborane, lithium lower aliphatic carboxylate, lithium 4-phenylborate imide, etc. may be used.

[0151] The above organic solid electrolyte may be, for example, a polyethylene derivative, a polyethylene oxide derivative, a polypropylene oxide derivative, a phosphate ester polymer, agitation lysine, polyester sulfide, polyvinyl alcohol, polyvinylidene fluoride, a polymer containing a secondary dissociating group, etc.

[0152] As the above inorganic solid electrolyte, for example, lithium nitride (Li3N), lithium iodide (LiI), Li5NI2, Li3N-LiI-LiOH, LiSiO4, LiSiO4-LiI-LiOH, Li2SiS3, lithium orthosilicate (Li4SiO4), Li4SiO4-LiI-LiOH, Li3PO4-Li2S-SiS2, and other nitrides, halides, sulfates of Li can be used.

[0153] The lithium secondary battery according to the present invention enables lamination stacking and folding processes of electrodes in addition to the general winding process. Furthermore, the battery case may be cylindrical, prismatic, pouch-type, or coin-type.

[0154] A lithium secondary battery utilizing a small and uniformly dispersed carbon nanotube dispersion of the present invention can have improved capacity retention rate and lifespan characteristics. Furthermore, such a lithium secondary battery can be used in small to medium-to-large models, such as automobiles and electronic devices.

[0155] The lithium secondary battery of the present invention may include an electrode containing a negative electrode active material as a negative electrode.

[0156] The above cathode includes the above cathode active material and can be manufactured by, for example, by mixing the above cathode active material, a binder, and optionally a conductive agent in a solvent to prepare a cathode active material composition, and then molding it into a certain shape or applying it to a current collector such as copper foil.

[0157] The above-mentioned negative electrode active material may include, for example, one or more selected from the group consisting of lithium metal and metals that can be alloyed with lithium.

[0158] For example, the metals that can be alloyed with the lithium may be silicon (Si), tin (Sn), aluminum (Al), germanium (Ge), lead (Pb), bismuth (Bi), antimony (Sb), Si-Y alloy (where Y is an alkali metal, alkaline earth metal, group 13 element, group 14 element, transition metal, rare earth element, or a combination thereof, and is not Si), Sn-Y alloy (where Y is an alkali metal, alkaline earth metal, group 13 to 16 element, transition metal, rare earth element, or a combination thereof, and is not Sn), etc. The above element Y includes magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), rutherfordium (Rf), vanadium (V), niobium (Nb), tantalum (Ta), dubnium (Db), chromium (Cr), molybdenum (Mo), tungsten (W), seaborgium (Sg), technetium (Tc), rhenium (Re), bohrium (Bh), iron (Fe), lead (Pb), ruthenium (Ru), osmium (Os), hassium (Hs), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), boron (B), aluminum (Al), gallium (Ga), It may be tin (Sn), indium (In), titanium (Ti), germanium (Ge), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), sulfur (S), selenium (Se), tellurium (Te), polonium (Po) or a combination thereof.

[0159] For example, the transition metal oxide may be lithium titanium oxide, lithium vanadium oxide, etc.

[0160]

[0161] Hereinafter, the operation and effects of the invention will be explained in more detail through specific embodiments of the invention. However, these embodiments are merely presented as examples of the invention and do not define the scope of the invention.

[0162]

[0163] Preparation Examples 1 to 5 and Comparative Preparation Examples 1 to 4

[0164] Based on a total monomer weight of 70 g, the mol % of each monomer was added to a 5-neck flask reactor according to Table 1 below, and 70 g of butyl butyrate was added. After installing a reflux condenser and a thermometer, the temperature was raised while purging with nitrogen until it reached 75°C.

[0165] Monomer (mol %) SABHABzAPBAAAANSM Preparation Example 140-201020-10 Preparation Example 240-2010101010 Preparation Example 370-551055 Preparation Example 42530101010510 Preparation Example 5-601010-1010 Comparative Preparation Example 130-201020-20 Comparative Preparation Example 280-15-5--Comparative Preparation Example 380-5-15--Comparative Preparation Example 440-101030-10

[0166] In Table 1 above, SA, BHA, BzA, PBA, AA, AN, and SM represent stearyl acrylate, behenyl acrylate, benzyl acrylate, phenoxybenzyl acrylate, acrylic acid, acrylonitrile, and styrene, respectively.

[0167]

[0168] Next, 0.15 g of 2,2'-azobis-2,4-dimethyl valeronitrile (V-65) was dissolved in 20 g of butyl butyrate and added dropwise over 30 minutes.

[0169] After the dropping was completed, the polymer (dispersant) was synthesized by maintaining it at 75°C for 7 hours.

[0170]

[0171] Example 1

[0172] 0.75 g of the polymer (dispersant) prepared in Preparation Example 1 (based on 100% solid content), 3 g of multi-walled carbon nanotubes, 96.25 g of butyl butyrate, and 400 g of zirconia beads with an average diameter of 0.65 mm were fed into a plantary ball mill and dispersed at 400 rpm for 60 minutes. Subsequently, the mixture of the dispersion and the zirconia beads was filtered through a 40 mesh to prepare a dispersion with a solid content of 3.75 wt%.

[0173]

[0174] Examples 2 to 5

[0175] Except that instead of the polymer (dispersant) prepared in Preparation Example 1, the polymers (dispersants) of Preparation Examples 2 to 5 were each added, the dispersions were prepared in the same manner as in Example 1.

[0176]

[0177] Comparative Examples 1 to 4

[0178] A dispersion was prepared in the same manner as Example 1, except that instead of the polymer (dispersant) prepared in Preparation Example 1, Comparative Examples 1 to 4 each used the polymer (dispersant) of Comparative Preparation Examples 1 to 4.

[0179]

[0180] Evaluation Example 1

[0181] The polymer (dispersant) of Preparation Examples 1 to 5 and Comparative Preparation Examples 1 to 4 was mixed with butyl butyrate at a ratio of 15% by weight, and the dissolution was checked visually.

[0182] Samples of solutions in which the polymers (dispersants) of Preparation Examples 1 to 5 and Comparative Preparation Examples 1 to 4 were mixed with butyl butyrate were shown in the order from left to right in FIG. 1.

[0183] It was confirmed that the sample of the solution mixed with the polymer (dispersant) of Preparation Examples 1 to 5 and Comparative Preparation Examples 2 to 4 dissolved transparently without precipitate, whereas the sample of the solution mixed with the polymer (dispersant) of Comparative Preparation Example 1 did not dissolve completely in the non-polar solvent because the proportion of non-polar monomer was insufficient.

[0184]

[0185] Evaluation Example 2

[0186] The viscosity and particle size of the dispersions of Examples 1 to 5 and Comparative Examples 2 to 4 were checked.

[0187] Comparative Example 1 was excluded from the evaluation of viscosity and particle size of the dispersion because the solubility was insufficient.

[0188] The viscosity of the dispersion was measured at 25°C using a Haake Mars rheometer (Thermo Fisher) in the range of shear rates from 0.01 to 200 / s, and evaluated based on the viscosity value at a shear rate of 1.0 / s, as shown in Table 2 below.

[0189] The particle size of the dispersion was measured using a Mastersizer 3000 (Malvern) and evaluated based on the median value (D50) according to the Fraunhofer diffraction model, and is shown in Table 2 below.

[0190] Viscosity [cPs, shear rate 1 / s] Particle Size [μm, D(50)] Example 1 15,625 6.8 Example 2 10,690 8.3 Example 3 20,241 7.5 Example 4 15,675 8.7 Example 5 8,340 8.1 Comparative Example 2 50,263 2.6 Comparative Example 3 40,256 42.8 Comparative Example 4 31,425 10.7

[0191] As a result of the evaluation, it was confirmed that the dispersions of Examples 1 to 5 had excellent dispersion, with lower viscosity and particle size compared to the comparative example.

[0192] Comparative Example 2 is judged to have low dispersibility because the electrostatic balance within the polymer (dispersant) is unstable due to the low content of polar monomers.

[0193] In addition, Comparative Example 3 is judged to have low dispersibility due to a lack of functional groups capable of interacting with carbon nanotubes.

[0194]

[0195] Evaluation Example 3

[0196] The electrochemical stability of measurement samples prepared as follows was evaluated using the polymers (dispersants) of Preparation Examples 1 and 2 and Comparative Preparation Example 4, which had the same content of nonpolar monomers.

[0197] First, 0.005 g of a polymer (dispersant) with 100% solid content of Preparation Examples 1 and 2 and Comparative Preparation Example 4 was placed between 0.2 g of a sulfide-based solid electrolyte and pressurized to produce sulfide-based electrolyte pellets.

[0198] A measurement sample was prepared by placing lithium metal and nickel foil on one side of each prepared pellet and assembling them.

[0199] Using an Electronic Impedance Spectroscopy (EIS) instrument (VSP-300, Biologics), voltage was applied to the measurement sample at a rate of 0.5 mV / s from 0 V to 6 V, and the current per applied voltage was measured using linear sweep voltammetry, as shown in Figure 2.

[0200] As a result of the measurement, it was confirmed that the measurement sample prepared using the polymer (dispersant) of Preparation Examples 1 and 2 had a lower current flow when the same voltage was applied compared to the measurement sample prepared using the polymer (dispersant) of Comparative Preparation Example 4.

[0201] In other words, it was confirmed that the polymer (dispersant) of Comparative Manufacturing Example 4 has excellent dispersion, but its stability is relatively poor when manufacturing cells.

[0202]

[0203] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive.

[0204] The scope of the present invention is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention.

[0205]

[0206] By using the dispersion of the present invention, carbon nanotubes can be dispersed even in a non-polar solvent, and by using this, a slurry composition for the cathode and a cathode can be prepared to manufacture a lithium sulfide secondary battery with high efficiency, large capacity, and excellent safety.

Claims

1. Contains a copolymer and a non-polar solvent, and The copolymer comprises acrylate-based monomer units containing linear or branched aliphatic hydrocarbons having 5 to 22 carbon atoms; A monomer unit comprising one or more substituted or unsubstituted aromatic rings; and Cyano(CN), Pyrrolidone (NC4H6O), Carboxylic Acid (COOH), Caprolactam (C5H 10 A polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2); Dispersion.

2. In Paragraph 1, The monomer unit comprising one or more substituted or unsubstituted aromatic rings is, An acrylate-series monomer unit comprising one or more substituted or unsubstituted aromatic rings; and A vinyl series monomer unit comprising one or more substituted or unsubstituted aromatic rings; comprising Dispersion.

3. In Paragraph 1, The above copolymer is based on 100 mol% of the above copolymer, Acrylate-series monomer units comprising linear or branched aliphatic hydrocarbons having 5 to 22 carbon atoms in an amount of 30 mol% or more and 85 mol% or less, Monomer units comprising one or more substituted or unsubstituted aromatic rings in an amount of 10 mol% or more and 60 mol% or less, and 5 mol% or more and 25 mol% or less of cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), and caprolactam (C5H 10 A polar monomer unit comprising one or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2), Dispersion.

4. In Paragraph 2, The molar ratio of the acrylate-based monomer unit containing one or more substituted or unsubstituted aromatic rings and the vinyl-based monomer unit containing one or more substituted or unsubstituted aromatic rings (moles of acrylate-based monomer unit containing one or more substituted or unsubstituted aromatic rings:moles of vinyl-based monomer unit containing one or more substituted or unsubstituted aromatic rings) is 1 to 4:

1. Dispersion.

5. In Paragraph 1, The above copolymer is represented by the following chemical formula 1, Dispersion. [Chemical Formula 1] In the above chemical formula 1, R1 to R 12 They are the same or different from each other, and each independently is hydrogen, a linear or branched hydrocarbon having 1 to 4 carbon atoms, and R'1 is a linear or branched aliphatic hydrocarbon having 5 to 22 carbon atoms, and R'2 comprises one or more substituted or unsubstituted aromatic rings, and R'3 is cyano(CN), pyrrolidone (NC4H6O), carboxylic acid (COOH), caprolactam (C5H 10 One or more selected from the group consisting of CNO), morpholine (C4H8NO), and oxazolidone (C3H4NO2), and R'4 comprises one or more substituted or unsubstituted aromatic rings, and 30 mol%≤l≤85 mol%, 5 mol%≤m≤30 mol%, 5 mol%≤n≤25 mol% and 5 mol%≤o≤30 mol%.

6. In Paragraph 5, R'2 and R'4 are the same or different from each other and each comprises one or more selected from the group consisting of independently substituted or unsubstituted benzyl, phenyl, phenoxy, naphthalene, anthracene, and pyrene, Dispersion.

7. In Paragraph 5, Monomers containing R'2 include benzyl acrylate, 3-phenoxybenzyl acrylate, σ-phenylphenoxyethyl acrylate, σ-phenylphenoxyethyl methacrylate, (1-pyrene) 2-methyl-2-propenoate, 1-naphthyl acrylate, 1-naphthyl methacrylate, 2-naphthyl acrylate, 2-naphthyl methacrylate, 9-anthracene methyl acrylate, and One or more selected from the group consisting of 9-anthracene methyl methacrylate, and The monomer containing R'4 is styrene, Dispersion.

8. In Paragraph 7, The monomers containing R'2 are benzyl acrylate and 3-phenoxybenzyl acrylate, and A monomer containing R'4 is styrene, Dispersion.

9. In Paragraph 1, The above non-polar solvent is butyl butyrate, chloroform, hexane, dimethyl ether, diethyl ether, toluene, benzene, carbon tetrachloride, carbon disulfide, turpentine, tetrahydrofuran (THF), 1,4-dioxane, diglyme, or a combination thereof. Dispersion.

10. In Paragraph 1, additionally including carbon materials, Dispersion.

11. In Paragraph 10, The above carbon material is graphite, activated carbon, carbon black, single-walled carbon nanotubes, thin-walled carbon nanotubes, multi-walled carbon nanotubes, fullerene, graphene, or a combination thereof. Dispersion.

12. In Paragraph 10, When the total solid content is 3.75% by weight based on 100% by weight of the total weight of the above dispersion, The viscosity of the dispersion at a shear rate of 1.0 / s is 5,000 cps or more and 30,000 cps or less, and The average particle size (D50) of the above carbon material is 13 μm or less, Dispersion.

13. A dispersion of any one of paragraphs 1 through 12; and A positive electrode active material containing a sulfur element; comprising Slurry composition for anode.

14. A positive electrode active material layer formed by applying the positive electrode slurry composition of claim 13 onto a current collector, anode.

15. Comprising the anode of paragraph 14, Lithium secondary battery.

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