Conductive material slurry for secondary battery electrodes, secondary battery electrodes, and secondary batteries including the same

Abstract

A conductive material slurry for a secondary battery electrode is provided, which reduces the viscosity of the conductive material slurry and simultaneously reduces the surface resistance of a film produced from the conductive material slurry. One embodiment of the present invention provides a conductive material slurry for a secondary battery electrode, which includes a conductive material and a dispersant, wherein the dispersant includes a cellulose-based compound and an organic acid salt.

Description

[Technical Field]

[0001] The present invention (Disclosure) relates to a conductive material slurry for a secondary battery electrode, and more particularly to a conductive material slurry for a secondary battery electrode, a secondary battery electrode, and a secondary battery including the same. [Background technology]

[0002] With the rapid development of the electronics, communications, and computer industries, electric vehicles, mobile phones, laptop computers, etc. have made remarkable progress, and batteries with high energy density and stable output are required as power sources for portable electronic devices. In particular, lithium secondary batteries are being actively developed as high-performance batteries with the highest energy density among currently commercially available secondary batteries.

[0003] First, conductive materials are materials used to facilitate the transfer of electrons between electrode active materials or between electrode active materials and current collectors, and are primarily developed as carbon-based materials. Conductive material slurry is a solution in which such conductive materials are dispersed in a solvent, and later becomes a material that makes up electrode slurry together with electrode active materials and binders. These materials have recently become increasingly important as secondary batteries expand into the medium- to large-sized battery market, such as electric vehicles and energy storage systems (ESS), and research into increasing theoretical capacity is ongoing.

[0004] The negative electrodes of commercial lithium secondary batteries are graphite-based, and graphite with a layered structure exhibits excellent cycle characteristics. Because the potential when lithium ions are inserted into the graphite is close to the equilibrium potential of lithium, the output voltage is not significantly different from when using metallic lithium. However, the commonly known theoretical capacity is 372 mAh / g, which limits the electrical capacity. Therefore, silicon-based materials are expected to be next-generation electrodes that can replace graphite-based negative electrodes as a negative electrode material with high specific capacity and excellent cycle performance.

[0005] Silicon, which has the highest theoretical capacity (4,200mAh / g) of any anode material for lithium secondary batteries, has the advantages of being environmentally friendly, having a low potential difference with lithium, and being abundant in reserves. However, silicon is a non-conductor, which means it has poor durability and a low electrical capacity. To address these shortcomings, there is a growing need for improved conductivity of silicon active materials and conductive materials.

[0006] Among them, carbon nanotubes (CNTs) have rapidly emerged as the main conductive material. Carbon nanotubes have a nano-sized diameter and a cylindrical shape, and carbon atoms are arranged in a spiral, forming sp 2 Based on this structure, carbon nanotubes have attracted attention as a material with excellent physical properties such as excellent electrical properties, strength, resilience, and thermal conductivity, and are being researched as new materials in various fields.

[0007] CNTs, used as a conductive material in secondary batteries, can increase energy density and improve battery life compared to existing powdered carbon, while also enabling battery size reduction. These advantages are particularly significant in electric vehicle batteries, which require high capacity and rapid charging and discharging. However, despite these advantages, CNTs' poor solubility and dispersibility are pointed out as major problems. In particular, CNTs exist in a bundle or agglomerate structure in solution due to strong van der Waals attraction. Therefore, research into technologies for dispersing CNTs is ongoing in the development of conductive slurries. Summary of the Invention [Problem to be solved by the invention]

[0008] An object of the present invention is to provide a conductive material slurry that can uniformly disperse a conductive material.

[0009] Another object of the present invention is to provide a conductive slurry that can reduce the viscosity of the conductive slurry and simultaneously reduce the surface resistance of a film produced from the conductive slurry. A further object of the present invention is to provide a conductive material slurry in which the particle size of the conductive material can be adjusted to be small. It is still another object of the present invention to provide a secondary battery electrode that can increase the energy density of the battery, improve the capacity retention rate, and extend the lifespan. It is still another object of the present invention to provide a secondary battery including the secondary battery electrode.

[0010] The objects of the present invention are not limited to those mentioned above, and other unmentioned objects and advantages of the present invention will be understood from the following description and will become more clearly understood from the examples of the present invention. Furthermore, it will be easily understood that the objects and advantages of the present invention can be realized by the means and combinations thereof as claimed. [Means for solving the problem]

[0011] To achieve the above object, according to a first aspect of the present invention, there is provided a conductive material slurry for a secondary battery electrode, comprising a conductive material and a dispersant, wherein the dispersant comprises a cellulose-based compound and an organic acid salt.

[0012] According to a second aspect of the present invention, in the first aspect, the conductive material may be any one selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and combinations thereof.

[0013] According to a third aspect of the present invention, in the second aspect, the weight ratio of the single-walled carbon nanotubes to the dispersant (single-walled carbon nanotubes:dispersant) may be 1:1 to 1:2.

[0014] According to a fourth aspect of the present invention, in the second aspect, the weight ratio of the multi-walled carbon nanotubes to the dispersant (multi-walled carbon nanotubes:dispersant) may be 1:0.5 to 1:1.

[0015] According to a fifth aspect of the present invention, in any one of the first to fourth aspects, the conductive material is analyzed by Raman spectroscopy using a laser having a wavelength of 520 to 540 nm, and the ratio of the maximum intensity of the D band (I) to the maximum intensity of the G band is d / I g ) may be 0.01 to 2.

[0016] According to a sixth aspect of the present invention, in any one of the first to fifth aspects, the content of the conductive material may be less than 2.7% by weight based on the total weight of the conductive material slurry for a secondary battery electrode.

[0017] According to a seventh aspect of the present invention, in any one of the first to sixth aspects, the weight ratio of the cellulose compound to the organic acid salt (cellulose compound:organic acid salt) may be 1:0.15 to 1:0.5.

[0018] According to an eighth aspect of the present invention, in any one of the first to seventh aspects, the cellulose-based compound may be any one selected from the group consisting of cellulose, carboxymethyl cellulose, a salt of carboxymethyl cellulose, hydroxyethyl cellulose, and combinations thereof.

[0019] According to a ninth aspect of the present invention, in any one of the first to eighth aspects, the weight average molecular weight (Mw) of the cellulose compound may be 400,000 g / mol or less.

[0020] According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the weight average molecular weight (Mw) of the cellulose compound may be 50,000 g / mol or more and 400,000 g / mol or less.

[0021] According to an eleventh aspect of the present invention, in any one of the first to tenth aspects, the organic acid salt can include one or more carboxylate structures including a carboxylate and a cation.

[0022] According to a twelfth aspect of the present invention, in any one of the first to eleventh aspects, the organic acid salt may be any one selected from the group consisting of citrate, oxalate, succinate, oxalosuccinate, malate, tartrate, oxaloacetate, polyacrylate, EDTA (Ethylenediaminetetraacetic acid) salt, alginate, and combinations thereof.

[0023] To achieve the above object, according to a thirteenth aspect of the present invention, there is provided a secondary battery electrode comprising an electrode active material, a conductive material, and a dispersant, wherein the dispersant comprises a cellulose-based compound and an organic acid salt. According to a fourteenth aspect of the present invention, in the thirteenth aspect, the electrode active material can include a silicon-based negative electrode active material. According to a fifteenth aspect of the present invention, there is provided a secondary battery including the secondary battery electrode according to the thirteenth or fourteenth aspect.

[0024] The above summary of the invention is not an exhaustive list of the features of the invention, and the various features and advantages thereof will be more fully understood with reference to the following specific examples. [Effects of the Invention]

[0025] According to one aspect of the present invention, it is possible to provide a conductive material slurry that can reduce the particle size of the conductive material and disperse the conductive material uniformly, thereby reducing the viscosity of the conductive material slurry and simultaneously reducing the surface resistance of a film produced from the conductive material slurry.

[0026] According to another aspect of the present invention, it is possible to provide a secondary battery electrode that can increase the energy density of a battery, improve the capacity retention rate, and extend the lifespan, and a secondary battery including the same. In addition to the above-mentioned effects, specific effects of the present invention will be described below while explaining specific details for carrying out the invention. DETAILED DESCRIPTION OF THE INVENTION

[0027] In this specification, the singular expression includes the plural expression unless the context clearly indicates otherwise.

[0028] When various embodiments are described in this specification, the effects of the present invention can be defined to include not only the effects attributable to each embodiment itself, but also the effects resulting from the organic combination of each embodiment. For example, even if Examples 1 and 2 are described independently in this specification, the effects resulting from the organic combination of Examples 1 and 2 are also included in the effects of the present invention, unless the context clearly indicates otherwise.

[0029] In this specification, a numerical range indicated using the term "to" indicates a numerical range that includes the values ​​described before and after the term as the lower and upper limits, respectively. When multiple numerical values ​​are disclosed as the upper and lower limits of a given numerical range, the numerical range disclosed in this specification can be understood as any numerical range in which any one of the multiple lower limits and any one of the multiple upper limits are the lower and upper limits, respectively. For example, when a range is described as a to b or c to d, it can be understood that the range described is a to b, a to d, c to d, or c to b.

[0030] As used herein, terms such as "about" or "substantially" refer to a reasonable amount of deviation from the modified term so as not to significantly change the end result. Such terms can be interpreted to include a deviation of at least ±5% or at least ±10%, within the limits where such deviation does not alter or invalidate the meaning of the word.

[0031] As used herein, the term "layer" or "film" refers to a layer or film that covers the entire area of ​​a given region, as well as a layer or film that covers only a portion of that region. For example, the surface of a layer or film can be defined as having a flat, non-flat, or a combination thereof; or a continuous, discontinuous, or a combination thereof. For example, when a layer or film is placed directly on top of another member, the coverage of the other member on the surface of the first member can be defined as 1% or more, 5% or more, 10% or more, 20% or more, 30% or more, 40% or more, 50% or more, 60% or more, 70% or more, 80% or more, 85% or more, 90% or more, 95% or more, or 99% or more.

[0032] In this specification, the average particle size of particles is the particle size at which the cumulative percentage in the volume-based particle size distribution curve reaches 50% when measured by a laser diffraction particle size distribution analyzer (D 50 ) can be defined as

[0033] In this specification, the weight-average molecular weight is a molecular weight converted into standard polystyrene and can be analyzed by a GPC (gel permeation chromatography) device. For example, in the case of GPC analysis, the developing solvent is tetrahydrofuran (THF), the column is PL Olexis from Polymer Laboratories, the sample concentration is 5 mg / mL, the sample injection amount is 100 μL, the flow rate is 1 mL / min, the detector is an Agilent High Temperature RI detector, and the column temperature can be set to 40° C.

[0034] According to one aspect of the present invention, there is provided a conductive material slurry for a secondary battery electrode, comprising a conductive material and a dispersant, wherein the dispersant contains a cellulose-based compound and an organic acid salt.

[0035] Generally, when a conductive material has low solubility and dispersibility in a conductive material slurry, the conductive material may exist in a bundle or agglomerate structure in the slurry due to strong van der Waals attraction. To address this issue, when a conductive material is dispersed using a surfactant, the surfactant must be added in excess of the conductive material content, resulting in an increase in the viscosity of the conductive material slurry and a decrease in electrical conductivity. Therefore, simply using a surfactant to disperse a conductive material makes it difficult to reduce the viscosity of the conductive material slurry while simultaneously increasing its electrical conductivity. For example, when a cellulose-based compound or an organic acid salt is used alone as a surfactant, a conductive material with a long length and a large specific surface area forms a bundle or agglomerate structure in the slurry, making it difficult to uniformly disperse the conductive material. As a result, the viscosity of the conductive material slurry is low and the surface resistance is high, making it difficult to increase the electrical conductivity between electrode active material particles or with a metal current collector when the conductive material slurry is applied to a secondary battery electrode.

[0036] According to one aspect of the present invention, a dispersant containing a cellulose-based compound and an organic acid salt can effectively prevent the conductive material from forming bundle or aggregate structures in the slurry, thereby reducing the viscosity of the conductive material slurry and simultaneously reducing the surface resistance of the film produced from the conductive material slurry. Specifically, the glucose ring structure in the cellulose-based compound can bond with the surface of the conductive material, and the anionic structure, such as carboxylate, can provide the advantage of interacting with the aqueous solvent to disperse the conductive material. The organic acid salt simultaneously contains a hydrophobic carbon chain and a polar functional group, and the hydrophobic carbon chain contributes to the dispersion effect of the conductive material, while the polar functional group contributes to the good dispersion of the conductive material in the aqueous solvent. The configuration of the present invention will be described in more detail below.

[0037] 1. Conductive material slurry for secondary battery electrodes The conductive material slurry for a secondary battery electrode according to the present invention includes a conductive material that can act to increase the conductivity between electrode active material particles or between the electrode active material particles and a metal current collector in an electrode, and minimizes the binder from acting as a non-conductor.

[0038] Specifically, the conductive material may be any one selected from the group consisting of single-walled carbon nanotubes (SWCNTs), multi-walled carbon nanotubes (MWCNTs), graphene, and combinations thereof, and more specifically, single-walled carbon nanotubes. The single-walled or multi-walled carbon nanotubes are linear carbon materials that can connect electrode active materials or electrode active materials and current collectors over a much longer distance than powders, easily forming a network structure and significantly contributing to improved conductivity. This can increase the energy density of batteries and extend their lifespan compared to existing powdered carbon materials. The graphene may be a two-dimensional monolayer separated from graphite, which is composed of stacked carbon layers with hexagonal rings, and may have a thickness of 0.2 to 0.4 nm.

[0039] Specifically, the single-walled carbon nanotubes may have a diameter of 1 to 2 nm, a length of 1 to 50 μm, and a BET specific surface area (Brunauer, Emmett, Teller specific surface area) of 700 to 1600 m 2 / g.

[0040] Specifically, the multi-walled carbon nanotubes may have a diameter of 5 to 10 nm, a length of 50 to 150 μm, and a BET specific surface area (Brunauer, Emmett, Teller specific surface area) of 200 to 1000 m. 2 / g.

[0041] In particular, carbon nanotubes, among conductive materials, have poor solubility and dispersibility in the solvent of the conductive material slurry due to their long length and high BET specific surface area. That is, carbon nanotubes may exist in a bundle or agglomerate structure in the slurry due to strong van der Waals attraction. To address this issue, if a surfactant is used to disperse the conductive material, the surfactant must be added in excess of the conductive material content, which can increase the viscosity of the conductive material slurry and reduce its electrical conductivity. To address this issue, a conductive material slurry according to one embodiment of the present invention uses a dispersant containing a cellulose-based compound and an organic acid salt to effectively prevent the conductive material from forming a bundle or agglomerate structure in the slurry. This reduces the viscosity of the conductive material slurry and simultaneously reduces the surface resistance of the film produced from the conductive material slurry.

[0042] The oxygen content of the conductive material according to the present invention may be 0.1 to 3%. Specifically, the oxygen content of the conductive material can be analyzed by elemental analysis using an EA (Elemental Analyzer) analyzer. The oxygen content of the conductive material can contribute to the conductivity and dispersion properties. When the oxygen content of the conductive material satisfies the above numerical range, the conductivity and dispersion effects can be achieved.

[0043] According to another embodiment of the present invention, the weight ratio of the single-walled carbon nanotubes to the dispersant (single-walled carbon nanotubes:dispersant) may be 1:1 to 1:2, specifically 1:1 to 1:1.7, and more specifically 1:1 to 1:1.5. When the weight ratio of the single-walled carbon nanotubes to the dispersant satisfies this weight ratio range, the single-walled carbon nanotubes are effectively prevented from forming an aggregate structure, thereby reducing the viscosity of the conductive slurry and increasing the electrical conductivity of the conductive slurry.

[0044] According to another embodiment of the present invention, the weight ratio of the multi-walled carbon nanotubes to the dispersant (multi-walled carbon nanotubes:dispersant) may be 1:0.5 to 1:1, specifically 1:0.5 to 1:0.9, and more specifically 1:0.5 to 1:0.8. When the weight ratio of the multi-walled carbon nanotubes to the dispersant satisfies this weight ratio range, the multi-walled carbon nanotubes are effectively prevented from forming an aggregate structure, thereby reducing the viscosity of the conductive slurry and increasing the electrical conductivity of the conductive slurry.

[0045] According to yet another embodiment of the present invention, the conductive material is analyzed by Raman spectroscopy using a laser with a wavelength of 520 to 540 nm, and the ratio of the maximum intensity of the D band (I d / I g ) may be 0.01 to 2. On the other hand, the ratio of the maximum intensity of the D band (I d / I g ) can be a parameter indicating defects in the conductive material. d / I g ) may vary depending on the type of conductive material.

[0046] Specifically, the maximum intensity of the D band (I) relative to the maximum intensity of the G band of the single-walled carbon nanotube d / I g ) may be 0.01 to 0.25, specifically 0.01 to 0.2, and more specifically 0.01 to 0.15. The ratio of the maximum intensity of the D band (I) to the maximum intensity of the G band of the single-walled carbon nanotube d / I g When the above numerical range is satisfied, the viscosity of the conductive slurry can be reduced and the electrical conductivity of the conductive slurry can be increased.

[0047] Specifically, the maximum intensity of the D band (I) relative to the maximum intensity of the G band of the multi-walled carbon nanotube d / I g ) may be 0.5 to 2.0, specifically 0.5 to 1.8, and more specifically 0.5 to 1.6. The ratio of the maximum intensity of the D band (I) to the maximum intensity of the G band of the multi-walled carbon nanotube may be 0.5 to 2.0, specifically 0.5 to 1.8, and more specifically 0.5 to 1.6. d / I g When the above numerical range is satisfied, the viscosity of the conductive slurry can be reduced and the electrical conductivity of the conductive slurry can be increased.

[0048] According to another embodiment of the present invention, the content of the conductive material may be less than 2.7 wt %, specifically 0.5 to 2.0 wt %, and more specifically 0.5 to 1.0 wt %, based on the total weight of the conductive material slurry for a secondary battery electrode. When the content of the conductive material satisfies the above range, the viscosity of the conductive material slurry can be reduced, and at the same time, the surface resistance of a film produced from the conductive material slurry can be reduced. The conductive material slurry for a secondary battery electrode according to the present invention includes a dispersant that effectively disperses the conductive material in the slurry and effectively prevents the conductive material from forming an aggregate structure.

[0049] The dispersant according to the present invention includes a cellulose-based compound and an organic acid salt. The cellulose-based compounds commonly include a glucose ring molecular structure and an equatorial substituent bonded to the glucose ring. Specifically, the glucose ring molecular structure exhibits hydrophobic properties and can bond with the surface of the conductive material, and the equatorial substituent contains a hydrophilic functional group and can form hydrogen bonds with water. The cellulose-based compound has rigid properties, allowing it to effectively disperse the conductive material in the conductive material slurry.

[0050] According to yet another embodiment of the present invention, the weight ratio of the cellulose compound to the organic acid salt (cellulose compound:organic acid salt) may be 1:0.15 to 1:0.5, specifically 1:0.3 to 1:0.5, and more specifically 1:0.4 to 1:0.5. When the weight ratio of the cellulose compound to the organic acid salt satisfies the above range, the viscosity of the conductive slurry may be reduced and the electrical conductivity of the conductive slurry may be increased.

[0051] For example, the cellulose-based compound may be any one selected from the group consisting of cellulose, carboxymethyl cellulose, a salt of carboxymethyl cellulose, hydroxyethyl cellulose, and combinations thereof.

[0052] The degree of etherification (or degree of substitution; DS) of the cellulose compound may be 0.6 to 1.2, specifically 0.6 to 1.0, and more specifically 0.6 to 0.8. The degree of etherification refers to the degree to which three -R groups present in one repeating unit of the cellulose compound are substituted with carboxymethyl groups.

[0053] Specifically, the weight average molecular weight (M w ) may be 400,000 g / mol or less, or may be 50,000 g / mol or more and 400,000 g / mol or less, and more specifically, 50,000 g / mol or more and 100,000 g / mol or less. The weight-average molecular weight of the cellulose-based compound affects the viscosity of the conductive material slurry, and the lower the weight-average molecular weight, the lower the viscosity of the conductive material slurry. When the weight-average molecular weight of the cellulose-based compound satisfies the above numerical range, the conductive material is effectively dispersed in the conductive material slurry, further reducing the viscosity of the conductive material slurry and increasing the electrical conductivity of the conductive material slurry.

[0054] The organic acid salt according to the present invention may contain one or more carboxylate structures containing a carboxylate and a cation, specifically, two or more carboxylate structures, and more specifically, three or more carboxylate structures. The more carboxylate structures containing a carboxylate and a cation in one molecule, the more the solubility and dispersibility of the conductive material in the aqueous solvent can be simultaneously increased. This improves the flowability of the conductive material slurry, reduces the viscosity of the conductive material slurry, and increases the electrical conductivity. Meanwhile, the cation may be, for example, any one selected from the group consisting of sodium ions, lithium ions, and potassium ions.

[0055] For example, the organic acid salt may be any one selected from the group consisting of citrate, oxalate, succinate, oxalosuccinate, malate, tartrate, oxaloacetate, polyacrylate, EDTA (Ethylenediaminetetraacetic acid) salt, alginate, and combinations thereof.

[0056] According to yet another embodiment of the present invention, the weight ratio of the conductive material, cellulose compound, and organic acid salt (conductive material:cellulose compound:organic acid salt) may be 0.5-2.5:0.3-4.0:0.07-1.5. When the weight ratio of the conductive material, cellulose compound, and organic acid salt satisfies the above range, the solubility and dispersibility of the conductive material in the conductive material slurry are further improved, the viscosity of the conductive material slurry is reduced, and the electrical conductivity of the conductive material slurry can be sufficiently increased.

[0057] The conductive material slurry for a secondary battery electrode according to the present invention may further include a solvent for dissolving the conductive material and the dispersant. Specifically, the solvent may be an aqueous solvent, more specifically, water. The content of the solvent based on the total weight of the conductive material slurry for a secondary battery electrode may be the content excluding the conductive material and the dispersant.

[0058] The viscosity of the conductive material slurry for secondary battery electrodes according to one embodiment of the present invention is 50 s -1 The viscosity of the conductive material slurry for secondary battery electrodes may be 150 to 1,000 cP at 23°C. When the viscosity of the conductive material slurry for secondary battery electrodes is reduced to within the above range, the role of the conductive material in improving conductivity can be reinforced. The viscosity of the conductive material slurry for secondary battery electrodes can be measured, for example, using an HR-2 Viscometer (TA Instruments) at a Cone of 2°, a diameter of 40 mm, and a viscosity of 50 s. -1 , can be measured at 23°C.

[0059] The surface resistance of a film prepared using a conductive material slurry for a secondary battery electrode according to an embodiment of the present invention may vary depending on the type of conductive material. When the conductive material is single-walled carbon nanotubes, the surface resistance of the prepared film may be 2.0 Ω / sq or less. When the conductive material is multi-walled carbon nanotubes, the surface resistance of the prepared film may be 20 Ω / sq or less. Since the surface resistance of the prepared film is low within this range, it can be inferred that the conductive material in the conductive material slurry is effectively dispersed, contributing to improved electrical conductivity. For example, the surface resistance of the prepared film can be measured using a four-point probe (FPP) method.

[0060] 2. Secondary battery electrode Another embodiment of the present invention provides a secondary battery electrode including an electrode active material, a conductive material, and a dispersant, the dispersant including a cellulose-based compound and an organic acid salt. Specifically, the secondary battery electrode is a negative electrode, and includes a negative electrode current collector and a negative electrode active material layer disposed on the negative electrode current collector.

[0061] The negative electrode current collector can play a role as a passage for transmitting electrons from the outside or receiving electrons from the negative electrode active material and sending them to the outside so that an electrochemical reaction occurs with the negative electrode active material. For example, as the negative electrode current collector, copper, stainless steel, aluminum, nickel, titanium, fired carbon, or those obtained by surface treatment with carbon, nickel, titanium, silver, etc. on the surface of aluminum or stainless steel can be used. Specifically, a transition metal that adsorbs carbon well, such as copper or nickel, may be used as the current collector. For example, the thickness of the negative electrode current collector may be 6 μm to 55 μm, but the thickness of the negative electrode current collector is not limited thereto. The negative electrode active material layer according to the present invention can include a negative electrode active material, a conductive material, and a negative electrode binder.

[0062] The negative electrode active material can play a role of storing or releasing lithium ions to generate electricity. Specifically, the negative electrode active material can include at least one of a silicon-based negative electrode active material and a graphite-based negative electrode active material, and specifically, can include a silicon-based negative electrode active material. The silicon-based negative electrode active material has a high theoretical capacity as a negative electrode material for a lithium secondary battery, has a low potential difference with lithium, is environmentally friendly, and has the advantage of abundant reserves. However, the silicon-based negative electrode active material is a non-conductor and is disadvantageous in terms of durability, and has the disadvantage that the battery capacity decreases. According to still another aspect of the present invention, by mixing the conductive material slurry and the silicon-based negative electrode active material, the conductive material can be well dispersed in the conductive material slurry to increase the electrical conductivity of the conductive material slurry. Thereby, the non-conductor characteristics of the silicon-based negative electrode active material can be compensated.

[0063] For example, the silicon-based active material can be one or more selected from the group consisting of Si, SiOx (0 < x ≤ 2), Si-C composite, and Si-Y alloy (Y is any one element selected from the group consisting of an alkali metal, an alkaline earth metal, a transition metal, a Group 13 element, a Group 14 element, and a rare earth element). The graphite-based active material may include at least one selected from the group consisting of artificial graphite, natural graphite, graphitized carbon fiber, and graphitized mesocarbon microbeads. For example, the content of the negative electrode active material may be 80 to 97% by weight based on the total solid content contained in the negative electrode active material layer.

[0064] The negative electrode binder can suppress separation between negative electrode active material particles or between the negative electrode and the current collector. The negative electrode binder can be a polymer commonly used in electrodes in the art. Examples of such negative electrode binders include, but are not limited to, polyvinylidene fluoride-hexafluoropropylene, polyvinylidene fluoride-trichloroethylene, poly(methylmethacrylate), poly(ethylhexylacrylate), poly(butylacrylate), poly(acrylonitrile), poly(vinylpyrrolidone), poly(vinyl acetate), poly(ethylene-co-vinyl acetate), poly(ethylene oxide), polyacrylate, cellulose acetate, and cellulose acetate butyrate. The cellulose ester may include, but is not limited to, cellulose acetate propionate, cyano ethyl pullulan, cyano ethyl poly(vinylalcohol), cyanoethylcellulose, cyanoethylsucrose, pullulan, and carboxyl methyl cellulose.

[0065] 3. Secondary battery Yet another embodiment of the present invention provides a secondary battery including the electrode for a secondary battery. The secondary battery according to the present invention may include a separator, a positive electrode disposed on one side of the separator, a negative electrode disposed on the other side of the separator, and an electrolyte. The description of the negative electrode will be omitted as it overlaps with the description of the electrode for the secondary battery.

[0066] separation membrane The porous substrate according to the present invention can electrically insulate the negative electrode and the positive electrode to prevent short circuits, while providing a path for lithium ions to move, and can be a porous structure having high resistance to the electrolyte and fine pore diameters.

[0067] The porous substrate may be made of any organic or inorganic material having electrical insulation properties, without any particular limitation. The porous substrate may contain, for example, at least one selected from the group consisting of polyolefin, polyethylene terephthalate, polybutylene terephthalate, polyacetal, polyamide, polycarbonate, polyimide, polyether ether ketone, polyether sulfone, polyphenylene oxide, polyphenylene sulfide, and polyethylene naphthalene, and may specifically contain a polyolefin. Polyolefins not only have excellent coating properties, but also can reduce the thickness of the separator, thereby increasing the proportion of the electrode active material layer in the battery and increasing the capacity per volume. Specifically, the weight-average molecular weight (M w ) may be 100,000 to 500,000 g / mol. If the weight-average molecular weight of the polyolefin is below the above range, it may be difficult to ensure sufficient mechanical properties, and if it exceeds the above range, the shutdown function may not be realized or molding may be difficult. The shutdown function refers to the function of blocking ion movement and preventing thermal runaway of the battery when the temperature of the secondary battery becomes high by dissolving the thermoplastic resin and closing the pores of the porous substrate.

[0068] The thickness of the porous substrate may be, for example, 3 to 50 μm or 4 to 30 μm. If the thickness of the porous substrate is below this range, the conductive barrier function may be insufficient, and if it exceeds this range, the resistance of the separator may increase excessively.

[0069] The average diameter of the pores in the porous substrate may be, for example, 10 to 100 nm. The pores in the porous substrate have a structure in which they are interconnected, allowing gas or liquid to pass from one surface of the porous substrate to the other surface.

[0070] A separator according to another embodiment of the present invention may include a coating layer disposed on at least one surface of the porous substrate, which may improve the mechanical strength and heat resistance of the separator for a secondary battery and increase ionic conductivity within the secondary battery. The coating layer according to the present invention may include a binder polymer and inorganic particles.

[0071] The binder polymer according to the present invention can link and stably fix inorganic particles. Examples of the binder polymer include polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polymethylmethacrylate, polyacrylonitrile, polyvinylpyrrolidone, polyvinylacetate, ethylene-co-vinyl acetate, polyethylene oxide, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate. One or a mixture of two or more selected from the group consisting of acrylonitrile-styrene butadiene copolymer, polyimide, and styrene-butadiene rubber may be used.

[0072] According to another embodiment of the present invention, the weight ratio of the inorganic particles to the binder polymer (inorganic particles:binder polymer) may be 50:50 to 99:1, specifically 70:30 to 95:5. If the content ratio of the inorganic particles to the binder polymer is below this range, the content of the binder polymer may be increased, which may reduce the performance of improving the thermal stability of the separator, and the pore size and porosity may be reduced due to the reduction in void spaces formed between the inorganic particles, which may result in a decrease in the performance of the final battery. If the content ratio exceeds this range, the content of the binder polymer may be too low, which may reduce the peeling resistance of the coating layer.

[0073] The inorganic particles according to the present invention can contribute to improving the mechanical strength and heat resistance of the separator for a secondary battery. Specifically, the inorganic particles are not particularly limited as long as they are electrochemically stable. That is, the inorganic particles usable in the present invention are those that are within the operating voltage range (e.g., Li / Li) of the secondary battery to be used. + There are no particular limitations on the material as long as it does not undergo oxidation and / or reduction reactions at a voltage of 0 to 5 V relative to the reference voltage.

[0074] For example, when inorganic particles with a high dielectric constant are used as the inorganic particles, they can contribute to increasing the dissociation degree of the electrolyte salt, e.g., lithium salt, in the liquid electrolyte, thereby improving the ionic conductivity of the electrolyte. For the above reasons, the inorganic particles may be inorganic particles with a dielectric constant of 5 or more, inorganic particles with lithium ion transport ability, or a mixture thereof.

[0075] The inorganic particles having a dielectric constant of 5 or more include Al2O3, SiO2, ZrO2, AlO(OH), Al(OH)3, Mg(OH)2, BaSO4, TiO2, BaTiO3, Pb(Zr x Ti 1-x )O3(PZT, where 0 <x<1)、Pb 1-x La x Zr 1-y Ti y O3(PLZT, where 0 <x<1、0<y<1である)、(1-x)Pb(Mg 1 / 3 Nb 2 / 3)O 3-x It may also be one or more mixtures selected from the group consisting of PbTiO3 (PMN-PT, where 0 < x < 1), HfO2, SrTiO3, SnO2, CeO2, MgO, NiO, CaO, ZnO, and SiC.

[0076] The inorganic particles having the lithium ion transfer ability are lithium phosphate (Li3PO4), lithium titanium phosphate (Li x Ti y (PO4)3, 0 < x < 2, 0 < y < 3), lithium aluminum titanium phosphate (Li x Al y Ti z (PO4)3, 0 < x < 2, 0 < y < 1, 0 < z < 3), (LiAlTiP) x O y -based glass (0 < x < 4, 0 < y < 13), lithium lanthanum titanate (Li x La y TiO3, 0 < x < 2, 0 < y < 3), lithium germanium thiophosphate (Li x Ge y P z S w , 0 < x < 4, 0 < y < 1, 0 < z < 1, 0 < w < 5), lithium nitride (Li x N y , 0 < x < 4, 0 < y < 2), SiS2-based glass (Li x Si y S z , 0 < x < 3, 0 < y < 2, 0 < z < 4) and P2S5-based glass (Li x P y S z , 0 < x < 3, 0 < y < 3, 0 < z < 7), and may be one or more mixtures selected from the group.

[0077] For example, the average particle size (D 50 ) of the inorganic particles may be 1 nm to 10 μm, specifically 10 nm to 2 μm, and more specifically 50 nm to 1 μm for forming a coating layer with a uniform thickness and an appropriate porosity. The "average particle size (D 50) refers to the particle size at the 50% point of the cumulative particle number distribution by particle size. The average particle size can be measured using the laser diffraction method. Specifically, the powder to be measured is dispersed in a dispersion medium, and then introduced into a commercially available laser diffraction particle size analyzer (e.g., Microtrac S3500). The particle size distribution can be calculated by measuring the difference in the diffraction pattern depending on the particle size when the particles pass through a laser beam.

[0078] Specifically, the thickness of the coating layer may be 0.1 to 10 μm, more specifically 1 to 3 μm, and more specifically 1.4 to 1.6 μm. When the thickness of the coating layer is within this range, the insulating properties and thermal stability of the separator can be improved, and at the same time, the energy density of the battery can be improved.

[0079] positive electrode The positive electrode according to the present invention may include a positive electrode current collector and a positive electrode active material layer disposed on at least one surface of the positive electrode current collector. The positive electrode active material layer may include a positive electrode active material, a conductive material, and a positive electrode binder.

[0080] For example, the positive electrode current collector is not particularly limited as long as it has high conductivity and does not induce chemical changes in the battery. Specifically, the positive electrode current collector can be made of copper, stainless steel, aluminum, nickel, titanium, baked carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, or the like, or an aluminum-cadmium alloy. The positive electrode current collector can typically have a thickness of 6 to 20 μm.

[0081] For example, the positive electrode active material may include a lithium transition metal oxide. The lithium transition metal oxide may be, for example, Li x1 CoO2(0.5 <x1<1.3)、Li x2 NiO2(0.5 <x2<1.3)、Li x3 MnO2(0.5 <x3<1.3)、Li x4Mn2O4(0.5 < x4 < 1.3), Li x5 (Ni a1 Co b1 Mn c1 )O2(0.5 < x5 < 1.3, 0 < a1 < 1, 0 < b1 < 1, 0 < c1 < 1, a1 + b1 + c1 = 1), Li x6 Ni 1-y1 Co y1 O2(0.5 < x6 < 1.3, 0 < y1 < 1), Li x7 Co 1-y2 Mn y2 O2(0.5 < x7 < 1.3, 0 ≦ y2 < 1), Li x8 Ni 1-y3 Mn y3 O2(0.5 < x8 < 1.3, O ≦ y3 < 1), Li x9 (Ni a2 Co b2 Mn c2 )O4(0.5 < x9 < 1.3, 0 < a2 < 2, 0 < b2 < 2, 0 < c2 < 2, a2 + b2 + c2 = 2), Li x10 Mn 2-z1 Ni z1 O4(0.5 < x10 < 1.3, 0 < z1 < 2), Li x11 Mn 2-z2 Co z2 O4(0.5 < x11 < 1.3, 0 < z2 < 2), Li x12 CoPO4(0.5 < x12 < 1.3) and Li x13 FePO4(0.5 < x13 < 1.3) may be one or more selected from the group consisting of. The conductive material used for the positive electrode may be the same as or different from the conductive material used for the negative electrode. The positive electrode binder may be the same as or different from the negative electrode binder.

[0082] electrolyte The electrolytic solution according to the present invention may contain a solvent and a lithium salt. The solvent according to the invention is, for example, propylene carbonate (PC), ethylene carbonate (EC), diethyl carbonate (DEC), dimethyl carbonate (DMC), dipropyl carbonate (DPC), dimethyl sulfoxide, acetonitrile, dimethoxyethane, diethoxyethane, tetrahydrofuran, N-methyl-2-pyrrolidone, ethyl methyl carbonate (EMC), gamma-buturolactone (GBL), fluoroethylene carbonate (Fluoroethylene carbonate), methyl methyl carbonate (Methyl methyl ... methyl carbonate (Methyl methyl carbonate), methyl methyl methyl carbonate (Methyl methyl carbonate), methyl methyl methyl carbonate (Methyl methyl carbonate), methyl methyl methyl methyl carbonate (Methyl methyl carbonate), methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl methyl The alkyl ester may be one or a mixture of two or more selected from the group consisting of methyl carbonate, FEC), methyl formate, ethyl formate, propyl formate, methyl acetate, ethyl acetate, propyl acetate, pentyl acetate, methyl propionate, ethyl propionate, ethyl propionate, and butyl propionate. The lithium salt according to the present invention is, for example, NO3 - , F - , Cl - , Br - , I - , PF6 - It may contain anions such as The secondary battery according to the present invention may be a cylindrical, prismatic or pouch-type secondary battery, but is not particularly limited as long as it corresponds to a charge / discharge device.

[0083] Another embodiment of the present invention provides a battery module including the secondary battery as a unit cell, and a battery pack including the battery module. The battery pack can be used as a power source for one or more medium- to large-sized devices selected from the group consisting of power tools, electric vehicles (EVs), hybrid electric vehicles (HEVs), and plug-in hybrid electric vehicles (PHEVs), and power storage systems.

[0084] Hereinafter, the embodiments of the present invention will be described in detail so that those skilled in the art can easily implement the present invention. However, this is merely an example, and the scope of the present invention is not limited to the following content.

[0085] [Production Example 1-1: Production of SWCNT slurry] Dispersant manufacturing 950 g of distilled water was placed in a round-bottom flask, and 50 g of trisodium citrate was added thereto, followed by stirring at room temperature for 2 hours to prepare a 5 wt % aqueous citrate solution.

[0086] 950 g of distilled water and 50 g of CMC (Carboxymethyl cellulose) with a controlled weight average molecular weight (Mw) were added to a round-bottom flask and stirred at room temperature for 2 hours to prepare a 5 wt% CMC aqueous solution. The following conductive material slurry was produced using the citrate aqueous solution and the CMC aqueous solution.

[0087] Manufacturing of conductive slurry The conductive material (SWCNT), dispersant (CMC aqueous solution and / or citrate aqueous solution), and remaining distilled water were placed in a beaker and stirred at 500-2,000 rpm for 60 minutes using a high-speed stirrer (Dispermat LC 55-E). The stirred mixture was placed in a high-pressure disperser (MN400BF, Micronox) and high-pressure dispersed under specific conditions (5 or 7 passes and 700 bar) to produce the final SWCNT slurry. In Comparative Examples 1-3, no pass progression was possible; in Examples 1-11, high-pressure dispersion was performed under 5 passes and 700 bar, and in Examples 12-18, high-pressure dispersion was performed under 7 passes and 700 bar. Meanwhile, in the following Tables 1, 3, 5, 7, 9 and 11, the remaining contents are defined as distilled water.

[0088] [Table 1]

[0089] [Experimental Example 1: Evaluation of Conductive Slurry of Production Example 1-1] 1) Viscosity of the conductive material slurry The viscosity of the conductive material slurry in Preparation Example 1-1 was measured using an HR-2 Viscometer (TA Instruments) at a cone of 2°, a diameter of 40 mm, and a temperature of 50 s. -1 , values ​​measured at 23°C.

[0090] 2) Measurement of the surface resistance of films made from conductive slurry The conductive material slurry was coated onto one side of a PET film using an applicator and then dried in an oven at 90°C to prepare a 7µm-thick film specimen (10cm x 15cm). The surface resistance was measured using the four-point probe (FPP) method using a surface resistance measurement device (MCP-T700; Resistivity measurement; Mitsubishi Chemical Analytech) and is shown in Table 2 below.

[0091] [Table 2]

[0092] Comparing Comparative Examples 1 to 3 with Examples 12 to 16 in terms of the dispersant composition in Table 2, it can be seen that the use of a cellulose compound and an organic acid salt as a dispersant reduces the viscosity of the conductive slurry and significantly reduces the surface resistance of the film produced from the conductive slurry. That is, Comparative Examples 1 and 2, which used CMC alone, had such high viscosity that pass-through was impossible, and Comparative Example 3, which used an organic acid salt alone, also had such high viscosity that pass-through was impossible.

[0093] Comparing Examples 1 to 6 from the perspective of the ratio of dispersant to conductive material, it can be seen that when the weight ratio of SWCNT to dispersant (SWCNT:dispersant) is 1:1 or more, the viscosity of the conductive material slurry is low, and the surface resistance of the film produced from the conductive material slurry is low.

[0094] Comparing Examples 2 to 16 from the perspective of the ratio of citrate to cellulose compound in the dispersant, it can be seen that when the weight ratio of the cellulose compound to citrate (cellulose compound:citrate) is 1:0.15 to 1:0.5, the viscosity of the conductive material slurry becomes lower and the surface resistance of the film produced from the conductive material slurry becomes lower.

[0095] Comparing Examples 1 to 18 in terms of the conductive material content, it can be seen that when the conductive material content is less than 2.7 wt % based on the total weight of the conductive material slurry, the viscosity of the conductive material slurry becomes lower and the surface resistance of the film produced using the conductive material slurry becomes lower.

[0096] [Production Example 1-2: Production of SWCNT slurry] A SWCNT slurry was produced in the same manner as in Production Example 1-1, except that CMC with a weight-average molecular weight of 50,000 to 100,000 g / mol was used. On the other hand, in the cases of Examples 19 to 28, 36 and 37, high-pressure dispersion was carried out under conditions of 5 passes and 700 bar, and in the cases of Examples 29 to 35, 38 and 39, high-pressure dispersion was carried out under conditions of 7 passes and 700 bar.

[0097] [Table 3]

[0098] [Experimental Example 2: Evaluation of Conductive Slurry of Production Example 1-2] The viscosity of the conductive material slurry of Preparation Example 1-2 and the surface resistance of the film prepared using the conductive material slurry were measured using the same measuring method as in Experimental Example 1, and the results are shown in Table 4 below.

[0099] [Table 4]

[0100] Comparing Tables 2 and 4 from the viewpoint of the weight average molecular weight of the CMC, it can be seen that by using a CMC with a relatively low weight average molecular weight of 50,000 g / mol or more and 100,000 g / mol or less, the dispersion effect of the conductive material is improved, the viscosity of the conductive material slurry is further reduced, and the surface resistance of the film produced using the conductive material slurry is further reduced.

[0101] Comparing Examples 19 to 33 from the perspective of the ratio of citrate to cellulose compound in the dispersant, it can be seen that when the weight ratio of the cellulose compound to citrate (cellulose compound:citrate) is 1:0.15 to 1:0.5, the viscosity of the conductive slurry becomes even lower, and the surface resistance of the film produced from the conductive slurry becomes even lower.

[0102] Comparing Examples 19 to 35 in terms of the conductive material content, it can be seen that when the conductive material content is less than 2.7 wt % based on the total weight of the conductive material slurry, the viscosity of the conductive material slurry becomes lower and the surface resistance of the film produced using the conductive material slurry becomes lower.

[0103] Comparing Examples 19 to 24 and Example 40 in terms of the ratio of dispersant to conductive material, it can be seen that when the weight ratio of SWCNT to dispersant (SWCNT:dispersant) is 1:1 to 1:2, the dispersion effect of the conductive material is further improved, the viscosity of the conductive material slurry is reduced, and the surface resistance of the film produced using the conductive material slurry is further reduced.

[0104] [Production Example 1-3: Production of SWCNT slurry] In Examples 41 to 45, SWCNT slurries were produced in the same manner as in Production Example 1-1, except that CMC with a weight-average molecular weight of 400,000 g / mol was used and dispersion was performed under high pressure of 700 bar for 5 passes.

[0105] In Examples 46 to 49, the SWCNTs were analyzed by Raman spectroscopy using a laser with a wavelength of 520 to 540 nm, and the ratio of the maximum intensity of the D band (I d / I g A SWCNT slurry was produced in the same manner as in Production Example 1-1, except that a conductive material with a σ of 0.3 was used and dispersion was performed under high pressure of 700 bar for 5 passes.

[0106] [Table 5]

[0107] [Experimental Example 3: Evaluation of Conductive Slurries of Production Examples 1-3] The viscosity of the conductive material slurries of Preparation Examples 1-3 and the surface resistance of the films prepared using the conductive material slurries were measured using the same measuring method as in Experimental Example 1, and the results are shown in Table 6 below.

[0108] [Table 6]

[0109] Comparing Tables 2, 4, and 6 in terms of the weight average molecular weight of CMC, it can be seen that the lower the weight average molecular weight of CMC, the more improved the dispersion effect of the conductive material, the lower the viscosity of the conductive material slurry, and the lower the surface resistance of the film produced from the conductive material slurry.

[0110] The maximum intensity of the D band relative to the maximum intensity of the G band (I d / I g ) from the viewpoint of comparing Examples 4, 5, 21, and 22 with Examples 46 to 49, I d / I g If the ratio exceeds 0.25, the viscosity of the conductive material slurry may be low, but it can be confirmed that the surface resistance becomes excessively high.

[0111] [Production Example 2: Production of MWCNT slurry] A conductive material slurry was produced in the same manner as in Production Example 1-1, except that MWCNT was used as the conductive material instead of SWCNT. In Examples 50 to 56, 61 to 64, and 69 to 72, high-pressure dispersion was performed at 700 bar for 5 passes, and in the remaining Examples, high-pressure dispersion was performed at 700 bar for 7 passes.

[0112] [Table 7]

[0113] [Experimental Example 4: Evaluation of the conductive material slurry of Production Example 2] The viscosity of the conductive material slurry of Preparation Example 2 and the surface resistance of the film prepared using the conductive material slurry were measured using the same measuring method as in Experimental Example 1, and the results are shown in Table 8 below.

[0114] [Table 8]

[0115] Comparing Examples 51 to 56 and 61 to 64 in terms of the ratio of dispersant to conductive material in Table 8, it can be seen that when the weight ratio of MWCNT to dispersant (MWCNT:dispersant) is 1:0.5 to 1:1, the dispersion effect of the conductive material is further improved, the viscosity of the conductive material slurry is reduced, and the surface resistance of the film produced using the conductive material slurry is further reduced.

[0116] The maximum intensity of the D band relative to the maximum intensity of the G band (I d / I g ) From the viewpoint of the present invention, when Examples 50, 51, 63 and 70 to 72 are compared, I d / I g When the ratio is 0.5 to 2.0, the dispersion effect of MWCNTs is further improved, the viscosity of the conductive slurry is reduced, and the surface resistance of the film produced using the conductive slurry is further reduced.

[0117] Comparing Examples 53 to 68 from the perspective of the ratio of citrate to cellulose compound in the dispersant, it can be seen that when the weight ratio of cellulose compound to citrate (cellulose compound:citrate) is 1:0.15 to 1:0.5, the viscosity of the conductive slurry becomes lower and the surface resistance of the film produced from the conductive slurry becomes lower.

[0118] [Production Example 3: Production of SWCNT conductive slurries containing different types of organic acid salts] A conductive material slurry was produced in the same manner as in Production Example 1-1, except that succinate was used instead of citrate as the organic acid salt. In Examples 74 to 84, high-pressure dispersion was performed at 700 bar for 5 passes, and in the remaining Examples, high-pressure dispersion was performed at 700 bar for 7 passes.

[0119] [Table 9]

[0120] [Experimental Example 5: Evaluation of the conductive slurry of Production Example 3] The viscosity of the conductive material slurry of Preparation Example 3 and the surface resistance of the film prepared using the conductive material slurry were measured using the same measuring method as in Experimental Example 1, and the results are shown in Table 10 below.

[0121] [Table 10]

[0122] [Production Example 4: Production of MWCNT conductive material slurries with different types of salt] A conductive material slurry was produced in the same manner as in Production Example 3, except that MWCNT was used as the conductive material instead of SWCNT. In Examples 90 to 94 and 99 to 102, high pressure dispersion was carried out at 700 bar for 5 passes, and in the remaining Examples, high pressure dispersion was carried out at 700 bar for 7 passes.

[0123] [Table 11]

[0124] [Experimental Example 6: Evaluation of the conductive material slurry of Production Example 4] The viscosity of the conductive material slurry of Preparation Example 4 and the surface resistance of the film prepared using the conductive material slurry were measured using the same measuring method as in Experimental Example 1, and the results are shown in Table 12 below.

[0125] [Table 12]

[0126] Referring to Tables 10 and 12, it can be seen that the conductive material slurry using succinate salts exhibits similar trends to the conductive material slurry using citrate salts.

[0127] Although the preferred embodiments of the present invention have been described in detail above, the scope of the present invention is not limited thereto, and various modifications and improvements made by those skilled in the art using the basic concept of the present invention defined in the following claims also fall within the scope of the present invention.

Claims

1. A conductive material; a dispersant, The dispersant comprises a cellulose-based compound and an organic acid salt. Conductive slurry for secondary battery electrodes.

2. The conductive material is any one selected from the group consisting of single-walled carbon nanotubes, multi-walled carbon nanotubes, graphene, and combinations thereof; The conductive material slurry for secondary battery electrodes according to claim 1 .

3. The weight ratio of the single-walled carbon nanotubes to the dispersant is 1:1 to 1:2; The conductive material slurry for secondary battery electrodes according to claim 2 .

4. The weight ratio of the multi-walled carbon nanotubes to the dispersant is 1:0.5 to 1:

1. The conductive material slurry for secondary battery electrodes according to claim 2 .

5. The conductive material was analyzed by Raman spectroscopy using a laser with a wavelength of 520 to 540 nm, and the maximum intensity of the D band (I ) relative to the maximum intensity of the G band (I ). ｄ / I ｇ ) is 0.01 to 2; The conductive material slurry for secondary battery electrodes according to claim 1 .

6. The content of the conductive material is The content of the conductive material for secondary battery electrodes is less than 2.7% by weight based on the total weight of the conductive material slurry for secondary battery electrodes. The conductive material slurry for secondary battery electrodes according to claim 1 .

7. the weight ratio of the cellulose compound to the organic acid salt is 1:0.15 to 1:0.5; The conductive material slurry for secondary battery electrodes according to claim 1 .

8. The cellulose-based compound is any one selected from the group consisting of cellulose, carboxymethyl cellulose, salts of carboxymethyl cellulose, hydroxyethyl cellulose, and combinations thereof; The conductive material slurry for secondary battery electrodes according to claim 1 .

9. The weight average molecular weight (Mw) of the cellulose-based compound is 400,000 g / mol or less. The conductive material slurry for secondary battery electrodes according to claim 1 .

10. The weight average molecular weight (Mw) of the cellulose-based compound is 50,000 g / mol or more and 400,000 g / mol or less. The conductive material slurry for a secondary battery electrode according to claim 9 .

11. The organic acid salt is Contains one or more carboxylate structures containing a carboxylate and a cation, The conductive material slurry for secondary battery electrodes according to claim 1 .

12. The organic acid salt is any one selected from the group consisting of citrate, oxalate, succinate, oxalosuccinate, malate, tartrate, oxaloacetate, polyacrylate, EDTA (Ethylenediaminetetraacetic acid) salt, alginate, and combinations thereof; The conductive material slurry for a secondary battery electrode according to claim 11.

13. an electrode active material; A conductive material; a dispersant, The dispersant comprises a cellulose-based compound and an organic acid salt. Secondary battery electrode.

14. The electrode active material includes a silicon-based negative electrode active material. The secondary battery electrode according to claim 13 .

15. A secondary battery comprising the secondary battery electrode according to claim 13 or 14.

Images