Binder-type conductive material composite, electrode composition comprising same, electrode manufactured from electrode composition, and secondary battery comprising electrode

Abstract

The present invention relates to a technology related to an electrode composition for a secondary battery. More specifically, the present invention relates to: a binder-type conductive material composite having a novel structure capable of improving the electrochemical and mechanical properties of a secondary battery while reducing the content of an organic compound, that is, a CNT / PAG composite in which carbon nanotubes (CNTs) are surface-treated with an acrylonitrile-glycol-based copolymer-based polymer (PAG) such that the two components are controlled to have a ratio within a predetermined range; an electrode composition comprising same; an electrode manufactured from the electrode composition; and a secondary battery comprising the electrode.

Description

Binder-type conductive composite, electrode composition including the same, electrode manufactured from the electrode composition, and secondary battery including the electrode

[0001] This invention was supported by the following national research and development project.

[0002] [Project ID] 1415188327

[0003] [Assignment Number] 20024827

[0004] Ministry of Trade, Industry and Energy

[0005] [Name of Project Management (Specialist) Institution] Korea Institute of Industrial Technology Planning and Evaluation

[0006] [Research Project Name] Material and Components Technology Development

[0007] [Research Project Name] Development of a High-Cohesion Binder Suitable for Solid Electrolyte Manufacturing and Electrode Process Conditions

[0008] The present invention relates to a technology related to an electrode composition for a secondary battery, and more specifically, to a novel binder-like conductive composite capable of improving the electrochemical and mechanical properties of a secondary battery while reducing the content of organic compounds, that is, a CNT / PAG composite in which carbon nanotubes (CNTs) are surface-treated with an acrylonitrile-glycol copolymer polymer (PAG) so that the two components have a certain ratio within a certain range, an electrode composition comprising the same, an electrode manufactured with the electrode composition, and a secondary battery comprising the electrode.

[0009] The electrode for making secondary batteries such as lithium-ion batteries is composed of three components: an active material that exhibits electrochemical properties, a conductive material that provides electrical conductivity, and a binder that bonds them together.

[0010] In the conventional wet process, active materials, binders, and conductive agents are mixed in a solvent to create an electrode composition slurry. This slurry is then applied to a metal plate (current collector) and dried to form the electrode plate, which is then used to manufacture secondary batteries. In contrast, in the dry process, these three components are dry-mixed without solvent, formed into sheets of a certain thickness, and then attached to a metal plate to produce the electrode plate.

[0011] Since the electrode is composed of three components, uniformly dispersing these components is a key task in manufacturing an electrode composition for a secondary battery. If uniform dispersion is not achieved, the electrochemical characteristics as well as the mechanical characteristics of the electrode and secondary battery manufactured from it cannot be stably maintained.

[0012] Of these three components, the conductive material is the most difficult to disperse uniformly. Previously, conductive carbon black was used as a conductive material. Carbon black is a nano-sized particle that can be directly added and dispersed in a solvent along with the active material and binder during the manufacture of the electrode composition slurry, making it a convenient conductive material to use. However, conductive carbon black has hydroxyl groups (-OH) on its surface, which allows it to form strong hydrogen bonds and remain in a clumped state, making it very difficult to disperse in a solvent. This clumping within the electrode composition slurry can reduce the conductivity-enhancing effect, or it can require increasing the content of conductive carbon black to overcome this issue.

[0013] To overcome these shortcomings, recent attempts have been made to use carbon nanotubes instead of conductive carbon black. Carbon nanotubes have a nanometer diameter and a length ranging from several to several hundred microns, resulting in a very high aspect ratio (the ratio of length to diameter), making them advantageous because they can significantly enhance conductivity even at low concentrations.

[0014] However, carbon nanotubes are usually entangled or bundled, making them very difficult to disperse in a solvent. Therefore, it is common to use a carbon nanotube dispersion prepared by pre-dispersing the carbon nanotubes with an appropriate dispersant. In this case, organic compounds such as a binder and a dispersant for dispersing carbon nanotubes exist together in the electrode composition, thereby increasing the overall organic compound content within the electrode composition.

[0015] This ultimately has the effect of reducing the content of the active material contained within the electrode, which is very disadvantageous in terms of the electric capacity of the electrode. Therefore, it is advantageous to minimize the content of the dispersant for dispersing the carbon nanotubes. However, if the content of the dispersant is reduced to a minimum, problems arise such as difficulty in dispersion or a significant increase in viscosity. To solve this problem of increased viscosity, surfactants are sometimes used. However, surfactants have both negative and positive charges within the molecule, and it is unclear how the charges within the surfactant affect the movement of electrons or lithium ions within the electrode composition. Ultimately, in order to use carbon nanotubes as a conductive material, a dispersant that does not adversely affect the electrochemical characteristics of the secondary battery must be selected.

[0016] Therefore, when using nanocarbon materials such as carbon nanotubes as conductive materials for secondary battery electrodes, it is necessary to invent a new technology that can minimize the content of organic compounds in the electrode composition while dispersing the nanocarbon materials well without causing the above-mentioned disadvantages.

[0017] In order to solve the above-described problems, the present inventors have developed a novel structure of a binder-type conductive composite in which a nanocarbon material is used as a core and the surface of the core is treated with an acrylonitrile-glycol copolymer (PAG) to form a shell, thereby completing the present invention.

[0018] Accordingly, the purpose of the present invention is to provide a novel structure of a binder-conductive composite capable of improving the electrochemical and mechanical properties of a secondary battery by maximizing the dispersibility of a nanocarbon material while minimizing the content of organic compounds used as a binder (for binding an active material) and a dispersant (for dispersing a nanocarbon material including carbon nanotubes) in an electrode composition of a secondary battery using a nanocarbon material as a conductive material, an electrode composition including the same, an electrode manufactured with the electrode composition, and a secondary battery including the electrode.

[0019] Another object of the present invention is to provide a binder-like conductive composite having a novel structure that is effective in both wet and dry methods when manufacturing electrodes for secondary batteries, an electrode composition comprising the same, an electrode manufactured using the electrode composition, and a secondary battery comprising the electrode.

[0020] The purpose of the present invention is not limited to the purposes mentioned above, and even if not explicitly mentioned, the purpose of the invention that can be recognized by a person of ordinary skill in the art from the description of the detailed description of the invention described below may also be included.

[0021] In order to achieve the above-described object of the present invention, the present invention provides a binder-type conductive composite comprising a core composed of a nanocarbon material; and a shell including an acrylonitrile-glycol copolymer bound to surround the core through physical interaction with the nanocarbon material; wherein the acrylonitrile-glycol copolymer acts as a dispersant for the nanocarbon material and a binder for a secondary battery.

[0022] In a preferred embodiment, the acrylonitrile-glycol copolymer is a copolymer comprising two or more monomers selected from the group consisting of an acrylonitrile monomer, a carboxylic monomer, a butadiene monomer, and a glycol monomer.

[0023] In a preferred embodiment, the acrylonitrile-glycol copolymer is an acrylonitrile-ethylene glycol-carboxylic copolymer, wherein the carboxylic monomer is at least one selected from the group consisting of acrylic acid monomers, acrylate monomers, maleic acid monomers, maleic anhydride monomers, and compounds thereof to which lithium is added.

[0024] In a preferred embodiment, the acrylonitrile-glycol copolymer is an acrylonitrile-ethylene glycol-maleic acid copolymer or an acrylonitrile-ethylene glycol-maleic anhydride copolymer.

[0025] In a preferred embodiment, the nanocarbon material:acrylonitrile-glycol copolymer is included in a weight ratio of 10:90 to 90:10.

[0026] In a preferred embodiment, the nanocarbon material is at least one selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, few-walled carbon nanotubes (few-wall CNTs), branched carbon nanotubes, carbon nanoplates (CNPs), vapor-grown carbon fibers (VGCFs), carbon nanoribbons, and carbon nanofibers.

[0027] In a preferred embodiment, the nanocarbon material has an aspect ratio of 100 or more.

[0028] In a preferred embodiment, the shell further comprises one or more binder compounds for secondary batteries.

[0029] In a preferred embodiment, the secondary battery binder compound is at least one selected from the group consisting of an acrylonitrile-butadiene copolymer, a styrene-butadiene copolymer, polyacrylic acid, polyacrylate, polyvinylidene fluoride, polytetrafluoroethylene, and a cellulose-based polymer.

[0030] In a preferred embodiment, the shell comprises an acrylonitrile-glycol copolymer: a secondary battery binder compound in a weight ratio of 10:90 to 90:10.

[0031] In a preferred embodiment, the physical interactions are hydrogen bonding and van der Waals bonding.

[0032] In addition, the present invention provides a binder conductive composite dispersion comprising any one of the binder conductive composites described above.

[0033] In addition, the present invention provides a method for producing a binder-type conductive material composite dispersion, comprising the steps of: dissolving an acrylonitrile-glycol copolymer in an organic solvent to obtain a precursor solution; adding a nanocarbon material to the precursor solution and stirring it to obtain a precursor dispersion; and redispersing the precursor dispersion at least once to obtain a binder-type conductive material composite dispersion.

[0034] In a preferred embodiment, the redispersion treatment includes a step of subjecting the precursor dispersion to a high-pressure dispersion treatment at 15,000 psi or higher; and a step of stirring the high-pressure dispersed precursor dispersion at a low-speed of 1000 rpm or lower.

[0035] In a preferred embodiment, the weight ratio of the acrylonitrile-glycol copolymer included in the precursor solution and the nanocarbon material introduced is 10:90 to 90:10.

[0036] In a preferred embodiment, the binder-conductive composite dispersion contains 0.2-20 wt% of the binder-conductive composite.

[0037] In addition, the present invention provides a method for manufacturing a binder-like conductive composite, comprising a post-treatment step of removing a solvent from a binder-like conductive composite dispersion obtained by any one of the above-described manufacturing methods and then drying it; and a step of pulverizing a solid material obtained in the post-treatment step.

[0038] In addition, the present invention provides a method for manufacturing an electrode slurry composition, comprising the steps of: preparing a binder-type conductive material complex dispersion using any one of the above-described manufacturing methods; and adding and dispersing an active material into the binder-type conductive material complex dispersion.

[0039] In a preferred embodiment, at least one of a conductive agent and a solvent is further added in the dispersing step.

[0040] In a preferred embodiment, the conductive material is at least one selected from the group consisting of conductive carbon black, graphene, carbon nanoplate, and graphene nanoplate.

[0041] In addition, the present invention provides a method for manufacturing an electrode for a secondary battery, including the steps of preparing an electrode slurry composition using the above-described manufacturing method; and the steps of applying the electrode slurry composition onto a current collector and drying it to prepare an electrode plate.

[0042] In a preferred embodiment, the electrode slurry composition further comprises at least one of a conductive material and a solvent, wherein the conductive material is at least one selected from the group consisting of conductive carbon black, graphene, carbon nanoplates, and graphene nanoplates.

[0043] In addition, the present invention provides a dry electrode composition comprising any one of the binder-like conductive composites described above and an active material.

[0044] In addition, the present invention provides a dry electrode composition comprising a binder-like conductive composite obtained by the above-described manufacturing method and an active material.

[0045] In addition, the present invention provides a method for manufacturing a dry electrode for a secondary battery, including the steps of preparing a dry electrode sheet by calendering the above-described dry electrode composition; attaching the dry electrode sheet to a current collector to manufacture a dry electrode plate; and rolling the electrode plate.

[0046] In addition, the present invention provides an electrode for a secondary battery manufactured by the above-described manufacturing method.

[0047] In addition, the present invention provides a secondary battery including the electrode described above.

[0048] According to the binder-conductive composite of the present invention described above, an electrode composition can be manufactured in which the content of organic compounds used as binders (for binding active materials) and dispersants (for dispersing nanocarbon materials including carbon nanotubes) in the electrode composition of a secondary battery using nanocarbon materials as conductive materials is minimized while the dispersibility of nanocarbon materials is maximized, and the electrochemical and mechanical properties of a secondary battery including an electrode manufactured from the electrode composition can be improved. In particular, there is an advantage in that the content of organic compounds and conductive materials in the electrode composition can be lowered to increase the content of active materials, thereby increasing the overall electric capacity of a secondary battery manufactured from the electrode composition.

[0049] In addition, according to the binder-type conductive composite of the present invention, the dispersibility of the electrode slurry can be increased when manufacturing an electrode using a wet method, thereby increasing the solid content of the slurry, which can ultimately reduce the amount of solvent that needs to be volatilized, minimize the content of organic compounds in the electrode composition, and increase the electrode thickness, so that there is an advantage in that a secondary battery having stable electrochemical characteristics can be manufactured.

[0050] These technical effects of the present invention are not limited to the scope mentioned above, and effects of the invention that can be recognized by a person having ordinary skill in the art from the description of specific contents for implementing the invention described below, even if not explicitly mentioned, are also naturally included.

[0051] Figure 1 is a photograph showing the flowability of electrode slurry according to Example 4 of the present invention.

[0052] Figure 2 is a graph showing the results of a charge / discharge cycle test of a coin cell obtained in an example and comparative example of the present invention.

[0053] Figure 3 is a graph showing the results of rate characteristic tests of coin cells obtained in examples and comparative examples of the present invention.

[0054] The terminology used herein is merely used to describe specific embodiments and is not intended to limit the present invention. The singular expression includes the plural expression unless the context clearly indicates otherwise. In this application, it should be understood that the terms "comprise" or "have" indicate the presence of a feature, number, step, operation, component, part, or combination thereof described in the description of the invention, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, operations, components, parts, or combinations thereof.

[0055] While terms like "first" and "second" may be used to describe various components, these components should not be limited by these terms. These terms are used solely to distinguish one component from another. For example, without departing from the scope of the present invention, a first component could be referred to as a "second component," and similarly, a second component could also be referred to as a "first component."

[0056] Unless otherwise defined, all terms used herein, including technical or scientific terms, have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. Terms defined in commonly used dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and shall not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0057] When interpreting components, even if there is no explicit description, they are interpreted as including the tolerance range. In particular, when terms such as "about" or "substantially" are used, they may be interpreted as meaning at or near that value when manufacturing and material tolerances inherent to the meaning stated are provided.

[0058] When describing a temporal relationship, for example, when the temporal order is described as ‘after’, ‘following’, ‘next to’, ‘before’, etc., it also includes cases where it is not continuous, unless ‘right away’ or ‘directly’ is used.

[0059] Hereinafter, the technical configuration of the present invention will be described in detail with reference to the attached drawings and preferred embodiments.

[0060] However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. Throughout the specification, the same reference numbers are used to designate the same components. Furthermore, in describing the present invention, detailed descriptions of known components or functions will be omitted if they are deemed to obscure the gist of the present invention.

[0061] The technical features of the present invention are: designing a new organic compound, an acrylonitrile-glycol copolymer (PAG), which can be used as a binder for a secondary battery and a dispersant for a nano-carbon material; and utilizing this characteristic, surface-treating a carbon nanotube (CNT), which is a nano-carbon material, as a core and coating the surface of the core with an acrylonitrile-glycol copolymer (PAG) to form a shell; obtaining a new structure of a binder-conductive composite; a method for producing the same; an electrode composition comprising the same; an electrode produced with the electrode composition; and a secondary battery comprising the electrode.

[0062] That is, in the conventional technology, the method of using carbon nanotubes as a conductive material for secondary batteries is to first disperse carbon nanotubes in advance using an organic compound that acts as a carbon nanotube dispersant in a solvent to prepare a carbon nanotube dispersion (CNT dispersion), and then add this to an electrode slurry according to the content of carbon nanotubes for use. In addition, since a binder had to be used to bind the active material and the conductive material in the electrode composition for secondary batteries, the electrode composition could not help but contain a carbon nanotube dispersant and a binder for secondary batteries.

[0063] In addition, the conventional method of manufacturing electrode slurry is to manufacture electrode slurry by adding and dispersing active material, binder, and conductive material including carbon nanotubes into a solvent. However, it is important to uniformly disperse the binder and carbon nanotubes, and for this purpose, the flowability of the electrode composition slurry must be certain, so there was a problem that it was difficult to increase the solids content of the slurry. However, if a dispersion liquid is prepared by pre-dispersing carbon nanotubes using a secondary battery binder as a dispersing agent, the carbon nanotubes and binder are already uniformly dispersed, so only the active material can be added and dispersed in this dispersion liquid to manufacture electrode slurry, and thus the solids content of the electrode slurry can be increased. This is effective because it can ultimately reduce the amount of solvent that needs to be volatilized and increase the electrode thickness. At this time, it is natural that not all secondary battery binders can be used as a dispersing agent for carbon nanotubes. For example, considering that carbon nanotubes have functional groups such as hydroxyl groups (-OH) and carboxyl groups (-COOH) on their surfaces, it can be fully expected that a binder that is compatible with these functional groups would be suitable for dispersing carbon nanotubes.

[0064] Based on this background, the present invention was started with the idea that if a dispersant for dispersing nanocarbon materials can be used as a binder for secondary batteries at the same time in order to minimize the content of organic compounds included in the electrode composition, an electrode composition in which nanocarbon materials are uniformly distributed can be manufactured without a separate dispersant. In particular, the binder-conductive composite of the present invention not only includes an acrylonitrile-glycol copolymer (PAG), which is a new organic compound designed to be used as a binder and a dispersant for nanocarbon materials, but also has a core-shell structure in which a nanocarbon material as a conductive material is placed in a core and a shell surrounding the core is formed with an acrylonitrile-glycol copolymer (PAG), thereby allowing an electrode composition in which a nanocarbon material as a conductive material is uniformly distributed and organic compounds are minimized can be manufactured easily.

[0065] Accordingly, the binder-type conductive composite of the present invention comprises a core composed of a nanocarbon material; and a shell comprising an acrylonitrile-glycol copolymer bound to surround the core through physical interaction with the nanocarbon material; wherein the acrylonitrile-glycol copolymer acts as a dispersant for the nanocarbon material and a binder for a secondary battery. Here, the physical interaction between the nanocarbon material and the acrylonitrile-glycol copolymer is hydrogen bonding and van der Waals bonding, and no chemical bonding occurs.

[0066] The nanocarbon material forming the core and the acrylonitrile-glycol copolymer included in the shell may be included in a weight ratio of 10:90 to 90:10, preferably 20:80 to 80:20. If the content of the nanocarbon material exceeds 90, the content of the nanocarbon material is too high and thus uneconomical, which is disadvantageous. On the other hand, if the content of the acrylonitrile-glycol copolymer exceeds 90, the binder content is too high and the content of the nanocarbon material is too low, which is disadvantageous because the electrical conductivity is low.

[0067] The nanocarbon material forming the core may be at least one selected from the group including nanocarbon materials such as single-walled carbon nanotubes, double-walled carbon nanotubes, few-walled carbon nanotubes (FWCNTs), multi-walled carbon nanotubes, branched carbon nanotubes, carbon nanoplates (CNPs), carbon nanoribbons, vapor-grown carbon fibers (VGCFs), and carbon nanofibers. These nanocarbon materials may be either as-received nanocarbon materials or nanocarbon materials surface-treated, such as by plasma treatment, to improve functionality, such as surface adhesion.

[0068] As an example, a nanocarbon material having an aspect ratio, which is the ratio of length to diameter or thickness, of 100 or more can be used, and in particular, in the case of carbon nanotubes, a carbon nanotube having an aspect ratio of 500 or more can be used. This is because carbon nanotubes with an aspect ratio of less than 100 are ultimately particles-like materials, making it difficult to maximize the conductivity increase effect with a small content, which is disadvantageous. It is self-evident that there is no need to specifically limit the maximum aspect ratio, since the larger the aspect ratio, the higher the conductivity increase effect can be obtained with a small content.

[0069] Among nanocarbon materials, carbon nanotubes are typically manufactured and supplied in the form of carbon nanotube lumps or bundles for ease of handling. To ensure smooth dispersion of carbon nanotubes, it is advantageous to use lumps or bundles with a particle diameter or size of 0.2-200 microns, with a particle diameter of 1-100 microns being optimal. A particle diameter smaller than 0.2 microns is disadvantageous because the carbon nanotubes become shorter and behave like particles, potentially reducing their conductivity-enhancing effect. On the other hand, a particle diameter larger than 200 microns can be disadvantageous because it requires a long dispersion time or has a high viscosity, making post-processing difficult.

[0070] The acrylonitrile-glycol copolymer contained in the shell is a new organic compound designed to be used as a binder for secondary batteries and a dispersant for nanocarbon materials, and may be a copolymer comprising two or more selected from the group consisting of acrylonitrile monomers, carboxylic monomers, butadiene monomers, and glycol monomers. That is, it may be a ternary copolymer in which acrylonitrile and glycol monomers are used as a base, and a carboxylic or butadiene monomer is copolymerized therewith. At this time, the content ratio of each component can be selected in consideration of flexibility, adhesiveness, and other characteristics, and can be determined by selecting from the range of 1-40 wt% of carboxylic or butadiene components, 10-40 wt% of glycol components, and 20-89 wt% of acrylonitrile components. If the composition ratio is below the lower limit or above the upper limit, the performance of each component is not properly implemented or is excessive, which is disadvantageous. In particular, among the above components, the carboxylic monomer has a hydroxyl group (-OH) or a carboxyl group (-COO - ) and other functional groups, such as hydroxyl groups (-OH) and carboxyl groups (-COOH) on the surface, are compatible with nanocarbon materials such as carbon nanotubes, and thus can improve dispersibility while enhancing adhesion to each component in the electrode and the current collector, making it effective.

[0071] In one embodiment, the acrylonitrile-glycol copolymer may be an acrylonitrile-ethylene glycol-carboxylic copolymer, wherein the carboxylic monomer may be at least one selected from the group consisting of acrylic acid monomers, acrylate monomers, maleic acid monomers, maleic anhydride monomers, and lithium-containing compounds thereof. In addition, the nitrogen component of the cyanide group (-CN) of the acrylonitrile monomer has particularly good compatibility with carbon nanotubes and is particularly useful for dispersing carbon nanotubes. In addition, the glycol component or the acrylate component is effective in imparting ionic conductivity or flexibility to the copolymer depending on its molecular structure or molecular weight.

[0072] In particular, ternary copolymers based on glycol and maleic acid, such as ethylene glycol-maleic acid (or maleic anhydride)-acrylic acid (or acrylate) copolymer, have good compatibility with nanocarbon materials including carbon nanotubes and can improve the dispersibility of the conductive material, so they are useful for producing a binder-type conductive material composite (i.e., a CNT / PAG composite) with a more uniform distribution. Therefore, as an example, the acrylonitrile-glycol copolymer may be an acrylonitrile-ethylene glycol-maleic acid copolymer or an acrylonitrile-ethylene glycol-maleic anhydride copolymer. In this case, the acrylonitrile-acrylic acid (or acrylate)-maleic acid (or maleic anhydride) copolymer can increase the adhesive strength between the electrode layer and the metal electrode plate, which is a current collector, and the bonding strength between each component in the electrode, depending on the component ratio, so it is particularly useful in terms of long-term stability.

[0073] Meanwhile, acrylonitrile-glycol copolymers can be synthesized in various ways. Basically, they are synthesized by using a reaction initiator under reaction conditions of 60-120℃ and 4-48 hours using a reaction solvent such as DMF and water. Representative reaction methods include, for example, a radical polymerization method using AIBN (2,2-azobisisobutyronitrile), a method using an organic acid such as acetic acid or paratoluenesulfonic acid, an oxidative polymerization method represented by ammonium persulfate, a redox polymerization method using a redox reaction, a photopolymerization method using light such as ultraviolet rays, or a thermal polymerization method. Among various polymerization methods, one or more reaction initiators are combined or sequentially used for polymerization.

[0074] In addition, the binder having a carboxyl group in the molecule, such as the acrylonitrile-based copolymer of the present invention, is a polar polymer. When these compounds are used as a binder or dispersant, they may interfere with the movement of metal ions such as lithium during charge and discharge cycles. Therefore, if necessary, for example, if the polar part of these compounds, such as lithium-containing polyacrylic acid (-CH2-CH(COOLi)n-), is pre-treated with a metal ion such as sodium or lithium, the movement of metal ions is no longer interfered with, making it effective. One of the methods for pre-adding lithium cations to the acrylonitrile-based copolymer of the present invention is to dissolve these compounds in a solvent and then add a desired amount of a lithium salt compound (e.g., LiPF6, LiBF4, or Li(TFSI)(Lithium bis(trifluoromethanesulfonyl)imide)) to pre-bond the lithium cations. In some cases, lithium can be added in advance by pre-hydrogenating these compounds with an organic acid (e.g., acetic acid or para-toluenesulfonic acid) and then adding a lithium compound (e.g., LiOH, LiCO3, or LiNO3). Either method can be selected depending on the solvent system to be used.

[0075] If necessary, the shell may further include one or more binder compounds for secondary batteries, in which case the shell may include an acrylonitrile-glycol copolymer: a binder compound for secondary batteries in a weight ratio of 10:90 to 90:10. Here, the binder compound for secondary batteries may be one or more selected from the group consisting of an acrylonitrile-butadiene copolymer, a styrene-butadiene copolymer, polyacrylic acid, polyacrylate, polyvinylidene fluoride, polytetrafluoroethylene, and a cellulose-based polymer, and the cellulose-based polymer may include cellulose or a derivative of cellulose, and in particular, may be carboxymethyl cellulose (CMC).

[0076] Next, the method for manufacturing a binder-type conductive composite dispersion of the present invention may include a step of dissolving an acrylonitrile-glycol copolymer in an organic solvent to obtain a precursor solution; a step of adding a nanocarbon material to the precursor solution and stirring it to obtain a precursor dispersion; and a step of redispersing the precursor dispersion at least once to obtain a binder-type conductive composite dispersion.

[0077] Here, the organic solvent included in the precursor solution is not limited as long as it can dissolve the acrylonitrile-glycol copolymer, and as a representative example, NMP or DMF can be used.

[0078] The weight ratio of the acrylonitrile-glycol copolymer included in the precursor solution and the nanocarbon material introduced may be 10:90 to 90:10.

[0079] The redispersion treatment includes a step of high-pressure spraying the precursor dispersion at 15,000 psi or higher; and a step of low-speed stirring the high-pressure sprayed precursor dispersion at 1,000 rpm or lower. Repeating the redispersion treatment multiple times improves the dispersibility, allowing for the production of a more uniform composite. Meanwhile, the redispersion treatment can be performed using a known method, as long as it can perform low-speed stirring at 1,000 rpm or lower after high-pressure spraying at 15,000 psi or higher. Various types of dispersion devices, such as general low-speed / high-speed stirring devices, dispersion devices using revolution / rotation, planetary mixers, ball milling devices that mix with balls, or high-pressure / high-speed spraying, can be used in combination with one or more of these devices. In addition, a small amount of nonionic and ionic surfactants may be used if necessary. Note that the selection of surfactants should be done carefully depending on the intended use. For example, when using it as a conductive dispersion for secondary batteries, a surfactant that does not affect the characteristics of the secondary battery must be selected. Furthermore, if the viscosity of the conductive dispersion is excessively high, a coupling agent or acidity regulator can be added to lower the viscosity.

[0080] The binder-conductive composite dispersion may contain a binder-conductive composite, i.e., a solid content of 0.2-20 wt%. If the solid content is less than 0.2%, the solvent content is too high, making the post-processing (drying) difficult, which is disadvantageous. On the other hand, if the solid content is more than 20%, the flowability is too poor, making the post-processing difficult, which is rather disadvantageous.

[0081] Next, the method for manufacturing a binder-like conductive composite of the present invention may include a post-treatment step of removing a solvent from a binder-like conductive composite dispersion obtained by the above-described method for manufacturing a binder-like conductive composite dispersion and then drying it; and a step of pulverizing a solid material obtained in the post-treatment step. That is, since the binder-like conductive composite of the present invention has a core-shell structure in which an acrylonitrile-glycol copolymer wraps the surface of a nanocarbon material, a binder-like conductive composite dispersion in which a nanocarbon material is dispersed in an acrylonitrile-glycol copolymer solution must be provided.

[0082] Here, the post-processing step can use any known technique as long as it can remove the solvent contained in the binder-type conductive composite dispersion, for example, a liquid composite dispersion can be spray-dried or freeze-dried to obtain solid particles.

[0083] Next, the method for preparing an electrode slurry composition of the present invention may include the steps of preparing a binder-type conductive material composite dispersion using the above-described method for preparing a binder-type conductive material composite dispersion; and the step of adding and dispersing an active material in the binder-type conductive material composite dispersion. If necessary, at least one of a conductive material and a solvent may be further added in the dispersing step, and the conductive material may be at least one selected from the group consisting of conductive carbon black, graphene, carbon nanoplates, and graphene nanoplates. The additionally included conductive material may be, as an example, a nanocarbon material having an aspect ratio of less than 100. Since the aspect ratio of the nanocarbon material included in the binder-type conductive material composite of the present invention is 100 or more, when they are used and dispersed together, particles with a small aspect ratio exist between nanocarbon materials with a large aspect ratio, which is advantageous in that a dispersion state can be better maintained.

[0084] As described above, the method for manufacturing an electrode slurry composition of the present invention is a method of preparing a uniformly dispersed binder-type conductive material complex dispersion in advance and then adding and dispersing only the active material therein, so that a more uniform electrode composition slurry can be obtained more quickly compared to the existing method [a method of mixing and dispersing the active material, binder, and conductive material (CNT dispersion dispersed in a dispersant) at once]. As described above, if necessary, a solvent may be further mixed. At this time, considering the contents of the active material, the acrylonitrile-glycol copolymer as the binder, and the nano-carbon material as the conductive material contained in the electrode composition, the weight ratio is adjusted from the beginning according to the ratio of the conductive material and binder of the secondary battery electrode to prepare a dispersion, and then only the active material is added to this dispersion and dispersed, thereby manufacturing an electrode composition slurry having a desired composition ratio, making the electrode slurry manufacturing process simple and easy, which is effective. As a result of the research of the present inventors, when manufacturing an electrode composition using the method of the present invention, the solid content in the electrode slurry can be increased to 75% or more, which is effective in reducing the amount of solvent that must be volatilized during the electrode manufacturing process.

[0085] Since the binder-like conductive composite of the present invention can be used for any positive electrode or negative electrode active material, the active material used in the method for producing an electrode slurry composition of the present invention may be an active material component composed of one or more selected from the group consisting of, for example, an alkali metal element such as lithium, an alkaline earth metal element, manganese, nickel, cobalt, aluminum, iron, phosphorus, tin, a carbon material such as graphite, titanium, silicon, silicon oxide, sulfur, and combinations thereof. Here, the alkali metal element may be any one selected from the group consisting of lithium, sodium, potassium, rubidium, cesium, and francium, and the alkaline earth metal element may be any one selected from the group consisting of beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra).

[0086] Next, the method for manufacturing an electrode for a secondary battery of the present invention includes a step of preparing an electrode slurry composition by the method described above; and a step of applying the electrode slurry composition onto a current collector and drying it to prepare an electrode plate.

[0087] Next, the dry electrode composition of the present invention may include any one of the binder-like conductive material composites and active materials described above. Here, the conductive material may further be included, and the conductive material may be at least one selected from the group consisting of conductive carbon black, graphene, carbon nanoplates, and graphene nanoplates. The additionally included conductive material may be, as an example, a nanocarbon material having an aspect ratio of less than 100. Since the aspect ratio of the nanocarbon material included in the binder-like conductive material composite of the present invention is 100 or more, when used together and dispersed, particles having a small aspect ratio exist between nanocarbon materials having a large aspect ratio, which is advantageous in that a dispersed state can be better maintained.

[0088] Next, the method for manufacturing a dry electrode for a secondary battery of the present invention may include a step of preparing a dry electrode sheet by calendering a dry electrode composition; a step of manufacturing a dry electrode plate by attaching the dry electrode sheet to a current collector; and a step of rolling the dry electrode plate.

[0089] As described below, the embodiments of the present invention have been mainly described using an electrode composition for a positive electrode of a lithium-ion battery. However, the present invention is applicable to various types of secondary batteries, such as other metal-ion batteries or sulfide-based or oxide-based solid electrolyte batteries. In addition, it is self-evident that the binder-like conductive material composite of the present invention can be used as an integrated binder / conductive material for a dry process as well as a conventional wet process as described above. In addition, it is self-evident that the binder-like conductive material composite dispersion of the present invention can be applied to both positive electrode and negative electrode plates by appropriately selecting the type of dispersant and solvent. The contents of the conductive material and other components in the embodiments and comparative examples of the present invention refer to the contents of pure solids excluding the solvent.

[0090]

[0091] Experimental method

[0092] 1. Adhesion test

[0093] To confirm the adhesive strength of the electrode layer of the present invention, an adhesive strength test was performed using Scotch tape (3M Scotch Tape). If the electrode layer was not completely peeled off from the electrode plate when the tape was attached to the electrode layer and then removed, the electrode was judged to have good adhesive strength with the electrode plate.

[0094] 2. Cohesion test

[0095] Additionally, the bonding strength between each component within the electrode was determined by the amount of electrode layer material that was left on the tape when the tape was peeled.

[0096] 3. Electrical conductivity of the electrode layer

[0097] The electrical conductivity of the electrode layer was measured by measuring the surface resistance of the upper surface of the electrode layer formed on a polyester film or aluminum foil (measuring device: Mitsubishi Corporation, 4-point probe method, using a flat tip).

[0098] 4. Dispersibility of binder-type conductive composite dispersion

[0099] The dispersibility of the binder-type conductive composite dispersion of the present invention was judged to be good if no clumped particles were visible when the conductive dispersion was thinly coated on a polyester film.

[0100] 5. Electrochemical properties of the electrode

[0101] In order to determine the electrochemical characteristics of the electrode manufactured using the electrode composition of the present invention, a half-cell (2032 type) was manufactured and a charge-discharge cycle test was performed. At this time, lithium metal foil was used as the counter electrode, and the electrolyte was a mixed solvent of carbonates such as ethylene carbonate (EC), ethyl methyl carbonate (EMC), diethyl carbonate (DEC), and fluoroethylene carbonate (FEC) (weight ratio: EC / EMC / DEC / FEC = 3 / 5 / 2 / 0.05), and 1.15 mol of LiPF6 was dissolved and used as the electrolyte. Coin cells were manufactured using a conventional method in a glove box filled with argon gas. The charge-discharge cycle test was initially performed at a formation process at rates of 0.1, 0.2, and 0.33C, and then at a charge-discharge cycle test at a rate of 1C. In the charge / discharge cycle test, the discharge capacity after 4 cycles was taken as the initial capacity, and the capacity retention rate was calculated by comparing it with the discharge capacity after 50 cycles.

[0102]

[0103] Example 1

[0104] 1. Step of obtaining precursor solution

[0105] To 10 grams of NMP, 0.4 grams of ethylene glycol-maleic acid-acrylonitrile copolymer (PAG) was added and stirred sufficiently at room temperature to obtain a precursor solution. Here, PAG was synthesized by the following method. First, maleic acid and ethylene glycol (molecular weight: 4,000 grams / mol) were weighed in a molar ratio of 1:2, and then added to dimethylformamide so that the solid content was 5 wt% and mixed by stirring at 90℃ for 10 minutes. Then, at the same temperature, 1.5 wt% of para-toluenesulfonic acid (p-CH3CH6CH4SO3H) as a reaction initiator based on the solid content was slowly added to this mixture and reacted for more than 6 hours. After the reaction was completed, the reaction temperature was lowered to 70℃, and acrylonitrile was added to this mixture, and ammonium persulfate was slowly dropped while stirring and reacted for 10 hours to synthesize a ternary copolymer. At this time, the total weight of the maleic acid and ethylene glycol that were reacted in the first step and the weight ratio of acrylonitrile were set to 1:1, and the content of ammonium persulfate, the reaction initiator, was set to 1.5 wt% based on the total solid content. After all reactions were completed, the reactants were pressure filtered, and the solid obtained was vacuum-dried (40°C, 24 hours) to obtain PAG.

[0106] 2. Step for obtaining precursor dispersion

[0107] 0.2 grams of as-received MWCNT (JO) was added to the precursor solution and stirred (2,000 rpm, 10 minutes) to obtain a precursor dispersion (solid content 6%).

[0108] 3. Step for obtaining a binder-type conductive composite dispersion

[0109] A binder-type conductive composite dispersion 1 was obtained by performing two steps of high-speed injection of the precursor dispersion at 15,000 psi or higher using a high-pressure, high-speed injection device and then low-speed stirring.

[0110]

[0111] Example 2

[0112] A binder-type conductive composite dispersion 2 was obtained by performing the same method as Example 1 except that the weight ratio of CNT and PAG was 20:80.

[0113]

[0114] Example 3

[0115] A binder-like conductive composite dispersion 3 was obtained by performing the same method as in Example 1 except that as-received SWCNTs (cobon) were used.

[0116]

[0117] Comparative Example 1

[0118] Comparative dispersion solution 1 was obtained by performing the same method as Example 1 except that the weight ratio of CNT and PAG was 95:5.

[0119]

[0120] Comparative Example 2

[0121] Comparative dispersion solution 2 was obtained by performing the same method as Example 1 except that PVP (Polyvinylpyrrolidone, Aldrich) instead of PAG was used.

[0122]

[0123] Comparative Example 3

[0124] Comparative dispersion solution 3 was obtained by performing the same method as in Example 1 except that PVDF (polyvinylidene fluoride, Aldrich) instead of PAG was used.

[0125]

[0126] Experimental Example 1

[0127] In order to confirm the characteristics of the dispersion, viscosity, dispersibility, and surface resistance were measured for the binder-type conductive composite dispersions 1 to 3 obtained in Examples 1 to 3 and the comparative dispersions 1 to 3 obtained in Comparative Examples 1 to 3, and the results are shown in Table 1. As described above, the dispersibility was judged to be good if there were no particles when thinly coated on a polyester film, but the poor quality of Comparative Example 1 was such that viscosity could not be measured because dispersion was not possible, and the poor quality of Comparative Example 3 showed a change in dispersibility over time and was judged to be bad (initial dispersion: good dispersibility, after 3 days: solution separated). The surface resistance was measured as the surface resistance of the composite dispersion film formed on the polyester film.

[0128] CNT binder weight ratio (CNT: binder) viscosity (cP) dispersibility surface resistance (ohm / area) Example 1 MWCNTPAG33:6721,000 good 10 2 Example 2MWCNTPAG20:8014,000Good10 2 Example 3SWCNTPAG33:679,200 Good 10 2 Comparative Example 1MWCNTPAG95:5-Poor-Comparative Example 2MWCNTPVP33:672,500Good10 1 Comparative example 3MWCNTPVDF33:6723,000 defective 10 2

[0129]

[0130] The viscosity of the binder-like conductive composite dispersions 1 to 3 obtained in Examples 1 to 3 was relatively high, at the level of several thousand to tens of thousands of centipoise. This is expected because no separate efforts, such as additive prescription or CNT treatment, were made to lower the viscosity since the dispersions were intended to be used in the manufacture of secondary battery electrode composition slurry. At the same composition ratio, the viscosity of the multi-walled carbon nanotube dispersion was measured to be higher than that of the single-walled carbon nanotube dispersion. When the dispersions were applied on a polyester film to form a thin film, the dispersibility was good enough that no particles were visible to the naked eye. In addition, the surface resistance of the conductive layer (binder-like conductive composite layer, thickness: average 1.0 micron) formed on the polyester film was hundreds (10 2 ) was ohm / area, and the surface resistance was slightly higher when the dispersant content was high, but all were 10 2 The ohm / area range was measured. The comparative dispersion liquid 1 obtained in Comparative Example 1 had too low a content of PAG, a dispersant, so that dispersion was not properly achieved and thus the dispersibility was so poor that the viscosity could not be measured. The comparative dispersion liquid 2 obtained in Comparative Example 2 used PVP, a representative CNT dispersion liquid, as a dispersant, and showed good dispersibility, and the surface resistance was 10 1 The ohm / area was measured to be good. However, Comparative Dispersion Solution 3 using PVDF as a dispersant had good dispersibility in the beginning of dispersion, but when checked again after about 3 days, the dispersion solution was found to be separating into layers, and the dispersibility was judged to be "poor."

[0131] As described above, both PVDF and PAG are organic compounds used as binders for positive electrodes of lithium-ion batteries. However, unlike PAG, which exhibits good dispersibility when dispersing CNTs, PVDF exhibits good dispersibility in the early stages of dispersion, but deteriorates over time as layer separation occurs. This demonstrates that not all organic compounds used as binders for secondary batteries are compounds that disperse carbon nanotubes well.

[0132] On the other hand, PAG, the dispersant used in Examples 1-3, is a compound used as a binder for a positive electrode of a lithium-ion battery, and it can be seen that the binder-type conductive composite dispersions 1 to 3 manufactured using these as dispersants exhibit good surface resistance and dispersibility.

[0133]

[0134] Example 4

[0135] 1. Preparation of a binder-type conductive composite dispersion

[0136] The same process as Example 1 was performed to prepare 3.5 g of a binder-type conductive composite dispersion 1 (solid content: 6 wt% (CNT 2 wt%, PAG 4 wt%)).

[0137] 2. Step of adding and dispersing an active material into a binder-type conductive composite dispersion.

[0138] 9.79 g of active material (NCM811) was added to the binder-type conductive composite dispersion 1 and stirred for the first time (2,000 rpm, 5 minutes). Then, a thinky mixer was used to disperse the material at 2,000 rpm for 5 minutes to prepare electrode slurry composition 1 (active material 97.9 wt%, CNT 0.7 wt%, PAG 1.4 wt%).

[0139]

[0140] Comparative Example 4

[0141] Comparative electrode slurry 1 was prepared by performing the same method as Example 4 except that Comparative Dispersion 2 was used.

[0142]

[0143] Comparative Example 5

[0144] Comparative electrode slurry 2 was prepared by performing the same method as Example 4 except that Comparative Dispersion Solution 3 was used.

[0145]

[0146] Experimental Example 2

[0147] As a result of testing the flowability of the electrode slurry composition 1 obtained in Example 4 and the comparative electrode slurries 1 and 2 obtained in Comparative Examples 4 and 5, it was confirmed that there would be no problem with electrode coating since they all showed a honey-like flowing shape. In particular, the electrode slurry composition 1 obtained in Example 4 showed a flowing shape as shown in Fig. 1 even though the solid content in the electrode slurry composition 1 was 75 wt%. However, since the electrode slurry 2 of Comparative Example 5 was too thick and did not flow, 0.2 g of NMP 0.6 was additionally added thereto to make the flow characteristics suitable for electrode coating. At this time, the solid content was approximately 72 wt%, which is suitable for electrode coating.

[0148] In addition, it was confirmed that both electrode slurry composition 1 and comparative electrode slurries 1 and 2, which were thinly applied on a polyester film, did not show any clumped particles, indicating that they were well-made to the extent that there were no problems with electrode coating.

[0149]

[0150] Example 5

[0151] The electrode slurry composition 1 manufactured in Example 4 was applied on aluminum foil, dried, and a positive electrode plate 1 (electrode density: 2.7 g / cm 3 , loading level: 10mg / cm 2 ) was manufactured, and coin cell 1 was manufactured from it.

[0152]

[0153] Comparative Example 6

[0154] Comparative Example Electrode Plate 1 and Comparative Example Coin Cell 1 were manufactured by performing the same method as Example 5, except that Comparative Example Electrode Slurry 1 obtained in Comparative Example 4 was used.

[0155]

[0156] Comparative Example 7

[0157] Comparative Example Electrode Plate 2 and Comparative Example Coin Cell 2 were manufactured by performing the same method as Example 5, except that Comparative Example Electrode Slurry 2 obtained in Comparative Example 5 was used.

[0158]

[0159] Experimental Example 3

[0160] Charge and discharge cycles were tested on the coin cell 1 obtained in Example 5 and the comparative coin cells 1 and 2 obtained in Comparative Examples 6 and 7, and the results are shown in Fig. 2.

[0161] As shown in Fig. 2, in the case of the coin cell 1 obtained in Example 5, the initial efficiency was about 95%, and the capacity retention rate after 50 cycles was about 96%. However, in the case of the comparative example coin cell 1 obtained in Comparative Example 6 in which PVP was used, the electric capacity decreased rapidly as soon as the charge / discharge test began, and the capacity retention rate decreased to almost 0%, and in the case of the comparative example coin cell 2 obtained in Comparative Example 7 in which PVDF was used, the capacity also decreased rapidly, showing a capacity retention rate of about 60%.

[0162] To further understand these cell characteristics, the rate capability was measured for the coin cell 1 and comparative example coin cell 2, and the results are shown in FIG. 3. As can be seen in FIG. 3, the coin cell 1 of Example 5 had a capacity of about 87% at 0.2C / 2C, and when it returned to 0.1C after the 2C measurement, it recovered to a capacity similar to the original capacity. However, in the case of comparative example 7, it was measured that 0.2C / 2C was less than 15%, and when it returned to 0.1C, only about 80% was recovered.

[0163] From the above results, it was found that by preparing the binder-like conductive material composite dispersion of the present invention as in Example 5, a CNT dispersion, i.e., a binder-like conductive material composite dispersion, having sufficient performance to be used as a conductive material for secondary batteries can be prepared without using a separate dispersant. On the other hand, as can be seen from the results of Comparative Examples 6-7, it was confirmed that not all binders for secondary batteries can be used for this purpose. For example, it was confirmed that both PVDF, a representative binder for secondary batteries, and PVP, a representative dispersant for carbon nanotubes, significantly deteriorated the electrochemical characteristics of electrodes prepared therefrom.

[0164]

[0165] Example 6

[0166] 1. Step of obtaining precursor solution

[0167] 0.4 g of ethylene glycol-maleic acid-acrylonitrile copolymer (PAG) was added to 10 g of DMF and stirred sufficiently at room temperature to obtain a precursor solution. Here, PAG was prepared in the same manner as in Example 1.

[0168] 2. Step for obtaining precursor dispersion

[0169] 0.2 g of as-received MWCNT (JO) was added to the precursor solution and stirred with a high-speed stirrer (2,000 rpm, 10 minutes) to obtain a precursor dispersion (solid content: 6%).

[0170] 3. Step for obtaining a binder-type conductive composite dispersion

[0171] A binder-type conductive composite dispersion 4 was obtained by performing the steps of high-speed spraying of the precursor dispersion at 15,000 psi or higher using a high-pressure spray device and then stirring at low speed twice or more.

[0172] 4. Post-processing step

[0173] The binder-type conductive composite dispersion 4 was spray-dried by adjusting the nozzle temperature to 200 degrees to obtain solid particles, which were then pulverized in a mortar to obtain a binder-type conductive composite.

[0174]

[0175] Experimental Example 4

[0176] The dispersibility of the binder-like conductive composite obtained in Example 6 was confirmed as follows. That is, in Example 6, the binder-like conductive composite was obtained in the form of fine particles, which were then placed in NMP and redispersed using a gyroscopic mixer (Thinky mixer, 2,000 rpm, 10 minutes), and it was confirmed that the composite was cleanly redispersed. The redispersion solution in which the binder-like conductive composite particles were redispersed in NMP was well applied thinly (about 2 microns thick) on a polyester film, but the surface resistance after drying was 10 2-3 It was measured to be slightly higher than that of the liquid CNT / PAG dispersion in terms of surface area / area. However, when it was formed on aluminum foil with a thickness of 2 microns, the surface resistance was 10 -3 The oom / area was good.

[0177]

[0178] Example 7

[0179] Except that the binder-conductive composite obtained in Example 6 was dispersed in NMP to prepare 3.5 g of a binder-conductive composite dispersion 4 (solid content: 6 wt% (CNT 2 wt%, PAG 4 wt%)), an electrode slurry composition 2 was prepared in the same manner as in Example 4, and then the same manner as in Example 5 was performed to prepare a positive electrode plate 2 (loading level: 10 mg / cm 2 ) was manufactured, and then coin cell 2 was manufactured.

[0180]

[0181] Experimental Example 5

[0182] A charge-discharge cycle test was performed on the coin cell 2 obtained in Example 7. Although the results of the charge-discharge cycle test are not shown, the initial efficiency after the formation process was approximately 94%, and the capacity retention rate after 50 cycles was measured to be approximately 94%.

[0183] From the above results, it was confirmed that a binder-like conductive material composite solid can be obtained from a binder-like conductive material composite dispersion and then redispersed to produce an electrode slurry composition, and that the charge-discharge cycle test results for the coin cell 2 manufactured therefrom can also produce results similar to those of the coin cell 1 manufactured directly using the binder-like conductive material composite dispersion.

[0184]

[0185] Example 8

[0186] 1. Dry electrode composition preparation step

[0187] NCM811 94 wt% and binder conductive composite 6 wt% were weighed and placed in a high-speed stirrer and stirred at 5,000 rpm for 10 minutes to obtain a dry electrode composition.

[0188] 2. Dry electrode sheet preparation stage

[0189] A dry electrode sheet was made by calendering a dry electrode composition.

[0190] 3. Dry electrode plate manufacturing stage

[0191] A dry electrode plate was manufactured by pressing a dry electrode sheet onto an aluminum electrode plate (pressure: approximately 8 kgf / cm2). At this time, a 1-micron thick primer layer was formed on the surface of the aluminum electrode plate.

[0192] 4. Rolling step

[0193] Afterwards, it was rolled at 100℃ using a roll press to make a positive electrode plate 3 (loading level: 20mg / cm) with a thickness of about 80 microns. 2 ) was manufactured.

[0194] Coin cells 3 were manufactured by taking circular electrodes from the manufactured positive electrode plate 3.

[0195] Experimental Example 6

[0196] The positive electrode plate 3 manufactured in Example 8 had an attractive appearance with almost no surface irregularities. As a result of the charge / discharge cycle test on coin cell 3, the initial efficiency after the formation process was approximately 95%, and the capacity retention rate after 50 cycles was approximately 95%, showing good electrochemical characteristics.

[0197] From the above-described results, it was confirmed that the binder-conductive composite of the present invention can be effectively used in the manufacture of a dry electrode.

[0198]

[0199] Example 9

[0200] 1. Preparation of a binder-type conductive composite dispersion

[0201] Except for reducing the CNT content by 0.2 wt%, the same process as Example 1 was performed to prepare 3.5 g of a binder-type conductive composite dispersion 5 (solid content: 5.86 wt% (CNT 1.8 wt%, PAG 4 wt%)).

[0202] 2. Step of adding and dispersing an active material into a binder-type conductive composite dispersion.

[0203] 9.79 g of active material (NCM811) and carbon black (Super P) were added to the binder-type conductive composite dispersion 5, and the first stirring was performed (2,000 rpm, 5 minutes). Then, the dispersion was performed again for 5 minutes at 2,000 rpm using a thoughtful mixer to prepare an electrode slurry composition 3 (active material 97.9 wt%, CNT 0.63 wt%, carbon black 0.07 wt%, PAG 1.4 wt%).

[0204] 3. Manufacturing of positive electrode plates and coin cells

[0205] The same method as Example 5 was performed except that electrode slurry composition 3 was used to prepare a positive electrode plate 4 (loading level: 10 mg / cm 2 ) was manufactured, and then coin cell 4 was manufactured.

[0206]

[0207] Experimental Example 7

[0208] The positive electrode plate 4 obtained in Example 9 had a smooth surface and a surface resistance of 10 -3 It showed good surface resistance as an ohm / area. In addition, as a result of the charge / discharge cycle test for coin cell 4, the initial efficiency after 4 cycles was approximately 95%, and the capacity retention rate after 50 cycles was approximately 96%, showing electrochemical characteristics almost similar to those of coin cell 1 of Example 5.

[0209] In Example 9, the use of conductive carbon black mixed into the electrode slurry composition was described. However, it is clear that the same effect will be achieved by using nanocarbon materials such as graphene, carbon nanoplates, or graphene nanoplates in addition to conductive carbon black.

[0210] As described above, the PAG of the present invention, that is, the acrylonitrile-glycol copolymer, was used as a dispersant to disperse the nanocarbon material in a solvent to create a binder-type conductive material composite dispersion, and when only the active material was further added to this dispersion to prepare an electrode slurry, it was confirmed that the electrode slurry characteristics were good enough for electrode coating. Here, the conventional slurry preparation method refers to a method of preparing an electrode slurry by adding the active material, the binder solution (a solution in which the binder is dissolved in a solvent), and CNTs at once to a solvent and dispersing them.

[0211] In addition, the binder conductive material complex dispersion of the present invention can be dried to obtain a binder conductive material complex in the form of solid particles, and the binder conductive material complex can be introduced into a solvent to be redispersed, and only an active material can be added to the obtained dispersion to prepare an electrode slurry, and the electrode prepared therefrom also exhibits similar electrochemical characteristics.

[0212] In addition, the binder conductive composite of the present invention and the active material are dry mixed to produce a dry electrode composition, and the dry electrode sheet and dry electrode can be produced by calendaring the dry electrode composition. It was confirmed that the electrochemical characteristics of the dry electrode produced thereby are similar to the electrochemical characteristics of the electrode produced by the wet method.

[0213] Therefore, when using nano-carbon materials, especially carbon nanotubes, as a conductive material in a secondary battery electrode composition, using the technology of the present invention will be more effective in improving the dispersibility of all components than the existing method of preparing a slurry by adding the active material, binder solution, and CNT dispersion all into a solvent and stirring and dispersing them. That is, according to the present invention, since only the active material needs to be added to the binder-conductive material complex dispersion prepared by uniformly dispersing the CNT and binder components in advance according to the content ratio of the electrode composition, the electrode slurry preparation process is simpler and is more advantageous than the existing method in terms of dispersibility and economy. In particular, according to the present invention, since it is possible to replace all conductive materials used in the electrode composition with carbon nanotubes, the content of the conductive material can be further reduced, and as a result, the content of the active material can be further increased, which has the advantage of increasing the total electrical capacity.

[0214]

[0215] Although the present invention has been illustrated and described with reference to preferred embodiments as described above, it is not limited to the above embodiments, and various changes and modifications may be made by a person having ordinary skill in the art to which the invention pertains within a scope that does not depart from the spirit of the present invention.

Claims

1. A core composed of nanocarbon material; and It is composed of a shell including an acrylonitrile-glycol copolymer that is combined to surround the core through physical interaction with the nanocarbon material; The above acrylonitrile-glycol copolymer is a binder-type conductive composite that acts as a dispersant for the nanocarbon material and a binder for secondary batteries.

2. In paragraph 1, A binder-type conductive composite, characterized in that the acrylonitrile-glycol copolymer is a copolymer comprising two or more selected from the group consisting of an acrylonitrile-based monomer, a carboxylic monomer, a butadiene-based monomer, and a glycol-based monomer.

3. In paragraph 2, A binder-type conductive composite, characterized in that the acrylonitrile-glycol copolymer is an acrylonitrile-ethylene glycol-carboxylic copolymer, and the carboxylic monomer is at least one selected from the group consisting of acrylic acid monomers, acrylate monomers, maleic acid monomers, maleic anhydride monomers, and compounds thereof to which lithium is added.

4. In paragraph 3, A binder-type conductive composite, characterized in that the acrylonitrile-glycol copolymer is an acrylonitrile-ethylene glycol-maleic acid copolymer or an acrylonitrile-ethylene glycol-maleic anhydride copolymer.

5. In paragraph 1, A binder-type conductive composite characterized in that the nanocarbon material and acrylonitrile-glycol copolymer are included in a weight ratio of 10:90 to 90:

10.

6. In paragraph 1, A binder-like conductive composite characterized in that the nano-carbon material is at least one selected from the group consisting of single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, few-walled carbon nanotubes (few-wall CNTs), branched carbon nanotubes, carbon nanoplates (CNPs), vapor-grown carbon fibers (VGCFs), carbon nanoribbons, and carbon nanofibers.

7. In paragraph 1, The above nanocarbon material is a binder-conductive composite characterized by an aspect ratio of 100 or more.

8. In paragraph 1, A binder-conductive composite, characterized in that the shell further comprises at least one binder compound for secondary batteries.

9. In paragraph 8, A binder conductive composite characterized in that the secondary battery binder compound is at least one selected from the group consisting of an acrylonitrile-butadiene copolymer, a styrene-butadiene copolymer, polyacrylic acid, polyacrylate, polyvinylidene fluoride, polytetrafluoroethylene, and a cellulose-based polymer.

10. In paragraph 8, A binder conductive composite characterized in that the shell comprises an acrylonitrile-glycol copolymer: a binder compound for secondary batteries in a weight ratio of 10:90 to 90:

10.

11. In any one of paragraphs 1 to 10, A binder-conductive composite characterized in that the above physical interactions are hydrogen bonds and van der Waals bonds.

12. A binder conductive composite dispersion comprising a binder conductive composite of any one of claims 1 to 10.

13. A step of dissolving an acrylonitrile-glycol copolymer in an organic solvent to obtain a precursor solution; A step of adding nanocarbon material to the precursor solution and stirring to obtain a precursor dispersion; and A method for producing a binder-like conductive composite dispersion, comprising: a step of redispersing the precursor dispersion at least once to obtain a binder-like conductive composite dispersion.

14. In paragraph 13, A method for manufacturing a binder-type conductive composite dispersion, characterized in that the above redispersion treatment includes a step of high-pressure dispersion treatment of the precursor dispersion at 15,000 psi or higher; and a step of low-speed stirring of the high-pressure dispersion-treated precursor dispersion at 1000 rpm or lower.

15. In paragraph 13, A method for producing a binder-type conductive composite dispersion, characterized in that the weight ratio of the acrylonitrile-glycol copolymer included in the precursor solution and the nanocarbon material introduced is 10:90 to 90:

10.

16. In paragraph 13, A method for producing a binder-type conductive material complex dispersion, characterized in that the binder-type conductive material complex dispersion contains 0.2-20 wt% of the binder-type conductive material complex.

17. A post-treatment step of removing the solvent from the binder conductive composite dispersion obtained by the manufacturing method of any one of claims 13 to 16 and then drying it; and A method for manufacturing a binder-type conductive composite, comprising: a step of pulverizing a solid material obtained in the above post-processing step.

18. A step of preparing a binder-type conductive composite dispersion using any one of the manufacturing methods of Articles 13 to 16; and A method for manufacturing an electrode slurry composition, comprising: a step of adding and dispersing an active material into the binder-type conductive composite dispersion.

19. In paragraph 18, A method for producing an electrode slurry composition, characterized in that at least one of a conductive agent and a solvent is further added in the dispersing step.

20. In paragraph 19, A method for manufacturing an electrode slurry composition, characterized in that the conductive material is at least one selected from the group consisting of conductive carbon black, graphene, carbon nanoplate, and graphene nanoplate.

21. A step of preparing an electrode slurry composition using the manufacturing method of Article 18; and A method for manufacturing an electrode for a secondary battery, comprising the step of applying the above electrode slurry composition onto a current collector and drying it to prepare an electrode plate.

22. In paragraph 21, The above electrode slurry composition further includes at least one of a conductive material and a solvent, A method for manufacturing an electrode for a secondary battery, characterized in that the conductive material is at least one selected from the group consisting of conductive carbon black, graphene, carbon nanoplate, and graphene nanoplate.

23. A dry electrode composition comprising a binder-like conductive composite and an active material according to any one of claims 1 to 10.

24. A dry electrode composition comprising a binder-like conductive composite and an active material obtained by the manufacturing method of Article 17.

25. A step of preparing a dry electrode sheet by calendaring the dry electrode composition of Article 23; A step of manufacturing a dry electrode plate by attaching the above dry electrode sheet to a current collector; and A method for manufacturing a dry electrode for a secondary battery, comprising the step of rolling the electrode plate.

26. An electrode for a secondary battery manufactured by the manufacturing method of Article 21.

27. An electrode for a secondary battery manufactured by the manufacturing method of Article 25.

28. A secondary battery comprising the electrode of clause 26.

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