Binder composition for manufacturing electrode, electrode material layer composition for dry process comprising binder composition, and secondary battery comprising same

Abstract

The present invention relates to an electrode material layer composition for a secondary battery and a secondary battery comprising same. More particularly, the present invention relates to: a novel binder composition containing a ternary copolymer to thus be able to enhance adhesion strength between an electrode and a metal electrode plate which is a current collector and the binding strength between components within the electrode regardless of whether used in a wet process or a dry process, maintain stable electrical conductivity, and exhibit excellent electrochemical properties; an electrode material layer composition for a dry process comprising the binder composition; and a secondary battery comprising same.

Description

Binder composition for electrode manufacturing, electrode material layer composition for dry process including the binder composition, and secondary battery including the same

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

[0002] [Project ID] 1415187718

[0003] [Assignment Number] 20023145

[0004] Ministry of Trade, Industry and Energy

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

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

[0007] [Research Project Name] Development of a Binder and Manufacturing Process for a Dry Process for Reducing Carbon in Secondary Battery Applications

[0008] The present invention relates to a technology for an electrode material layer composition for a secondary battery and a secondary battery comprising the same, and more specifically, to a binder composition having a novel composition that can improve the adhesive strength between an electrode and a metal electrode plate as a current collector and the bonding strength between each component in the electrode, regardless of whether it is used in a wet process or a dry process, including a ternary copolymer, and has excellent electrochemical properties by stably maintaining electrical conductivity, an electrode material layer composition for a dry process comprising the binder composition, and a secondary battery comprising the same.

[0009] The following description of the present invention will focus on lithium-ion batteries. However, it is clear that the scope of the present invention is not limited to lithium-ion batteries and can be applied to all secondary batteries.

[0010] Lithium-ion batteries are made by mixing lithium-containing compound particles as positive electrode active materials and negative electrode active materials, such as graphite, with a binder to form an active material layer on a metal foil (plate) such as aluminum or copper, impregnating it with an electrolyte, and then placing a separator in the middle and bonding them together. At this time, lithium ions operate by repeating the process of entering and exiting the positive and negative electrode layers (lithiation and delithiation). If the type of ion is different, a secondary battery that operates with that ion can be manufactured by using materials that match the ion, such as the positive electrode active material, negative electrode active material, and, if necessary, the type of electrolyte.

[0011] The conventional technology for making electrode plates is the so-called wet method, which involves dispersing active materials, binders, conductive agents, and other additives in a solvent such as N-methyl-2-pyrrolidone (NMP) or water to create a so-called electrode composition slurry, which is then applied to a metal plate to a certain thickness and dried to create an active material electrode plate. This requires a separate process to completely remove the solvent during the manufacturing process and to collect the evaporated solvent again. Therefore, the wet process is an expensive process that requires a lot of energy, such as evaporating the solvent and recapturing it. On the other hand, the dry process, which has recently emerged, is a technology that creates an electrode composition by dry mixing active materials, binders, and other additives without using a solvent, and then forms it directly onto the plate to a certain thickness to manufacture an electrode plate without a solvent. In the dry method, high-speed stirring or a stirring method that applies heat and pressure is used to uniformly mix the active material with the binder and other additives, but since no solvent is used, there is no separate process required for solvent removal and collection, so it can be said to be environmentally friendly.

[0012] To create an electrode composition, an electrode layer must be formed on a metal plate. The binder is the material that provides adhesion between the active materials and the plates. This binder must bond the active materials and conductive materials, while also preventing lithium ions from moving from the positive electrode active material (e.g., lithium-nickel-cobalt-manganese: NCM) to the negative electrode active material (e.g., graphite, silicon, etc.), or vice versa. To facilitate the movement of lithium ions through the binder, it is advantageous to use a binder with good ion conductivity. The binders currently used are mainly PVDF (polyvinylidene fluoride) for the positive electrode in the wet process and CMC / SBR (carboxymethyl cellulose / styrene-butadiene rubber) mixtures for the negative electrode. However, these binders are not effective in improving the bonding strength between active materials or adhesion to the electrode plates, and do not contain ionic conductive components, so these binders may have limited effectiveness in improving the bonding strength with the active materials or the electrode plates or increasing ionic conductivity. In addition, the binder mainly used in the dry process is a fluorine resin called PTFE (polytetrafluoroethylene). When using this as a binder to make an electrode composition and manufacturing an electrode layer sheet from it through calendaring, it requires high pressure, and it is pointed out that it is inconvenient to make a relatively thin electrode layer of less than about 100 microns. In addition, fluorine resins are known to be polymers with poor adhesive strength. In this case, although the electrode layer can be manufactured under high pressure, a major problem has arisen in that the adhesion of each component of the battery may be reduced due to repeated expansion and contraction accompanying the repeated charging and discharging process during battery use, which may ultimately lead to a deterioration in electrochemical characteristics.

[0013] Therefore, when manufacturing the electrode material layer of a secondary battery using a dry process, it is necessary to develop a new binder that can enhance the binding strength of components such as active materials and conductive materials and the adhesive strength with the electrode plate, while also having excellent electrochemical properties.

[0014] Accordingly, the purpose of the present invention is to provide a binder composition for manufacturing an electrode which can enhance the bonding strength between each component in an electrode, whether used in a wet process or a dry process, including a ternary copolymer, is flexible and has excellent adhesion to a plate metal, and does not interfere with the movement of lithium ions, thereby having excellent electrochemical properties, and an electrode material layer composition for a dry process including the binder composition.

[0015] Another object of the present invention is to provide a secondary battery electrode that can be miniaturized by manufacturing a thinner positive electrode material layer or negative electrode material layer using a binder composition for manufacturing an electrode.

[0016] Another object of the present invention is to provide various secondary batteries including lithium ion batteries having excellent environmental friendliness and economic efficiency, by eliminating the complex process of removing and capturing a solvent, including an electrode manufactured with an electrode material layer composition for a dry process.

[0017] The purposes of the present invention are not limited to those mentioned above, and other purposes not mentioned will be clearly understood by those skilled in the art from the description below.

[0018] In order to achieve the above-described object of the present invention, first, the present invention provides a binder composition for manufacturing an electrode, including a ternary copolymer composed of a glycol compound, a maleic acid compound, and a third monomer.

[0019] In a preferred embodiment, the third monomer is a compound having a main chain containing a vinyl group (CH2=CH-) and to which another functional group is attached.

[0020] In a preferred embodiment, the compound is at least one selected from the group consisting of an acrylic compound, an acrylonitrile compound, an ethylene compound, an imidazole compound, an imidazolium compound, a propylene compound, and a vinylidene compound.

[0021] In a preferred embodiment, the third monomer is an acrylic compound having the following chemical formula 1.

[0022] [Chemical Formula 1]

[0023] CH2=CH-COO-R

[0024] Here, R is any one of -H, an alkyl group, an alkenyl group, an alkynyl group, a phenyl group, and an amino group.

[0025] In a preferred embodiment, the three-component copolymer includes a glycol compound: a maleic acid compound in a molar ratio of 99:1 to 1:99, and the glycol compound and the maleic acid compound: a third monomer in a weight ratio of 99:1 to 1:99.

[0026] In a preferred embodiment, the glycol compound is a compound whose main chain is composed of ethylene glycol (HO-(CH2-CH2-O)nH) or ethylene oxide (-(CH2-CH2-O)n-)), where n is a natural number > 0, and the maleic acid compound is a compound including a 5-membered ring structure having two carboxyl groups.

[0027] In a preferred embodiment, the glycol compound is at least one selected from the group consisting of ethylene glycol, ethylene oxide, propylene glycol, and propylene oxide, and the maleic acid compound is at least one selected from the group consisting of maleic acid, salts thereof, and anhydrides thereof.

[0028] In a preferred embodiment, the third component copolymer is ethylene glycol-maleic acid-acrylonitrile or ethylene glycol-maleic acid-acrylic acid.

[0029] In a preferred embodiment, the ternary copolymer has a number average molecular weight of 10,000-1,000,000 grams / mol.

[0030] In a preferred embodiment, it further comprises one or more other types of binders, wherein the three-component copolymer:binder is included in a weight ratio of 90:10 to 10:90.

[0031] In a preferred embodiment, the binder is one or more of carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyacrylic acid (PAA).

[0032] In addition, the present invention provides an electrode material layer composition for a dry process, comprising: an active material for a positive or negative electrode; one of the binder compositions described above; and a conductive material.

[0033] In a preferred embodiment, the positive or negative electrode active material comprises 85-99.4 wt%, the binder composition comprises 0.5-10 wt%, and the conductive material comprises 0.1-5 wt%.

[0034] In a preferred embodiment, the conductive material is at least one selected from the group consisting of conductive carbon black, graphene, single-wall carbon nanotubes, double-wall carbon nanotubes, multi-wall carbon nanotubes, branched carbon nanotubes, carbon nanoplates, and carbon nanoribbons.

[0035] In a preferred embodiment, the invention further comprises an acrylate compound that is liquid at room temperature and capable of post-curing, and a curing agent for the acrylate compound.

[0036] In a preferred embodiment, the acrylate compound is a monomer or oligomer containing 2 to 16 functional groups and having a main chain of 2 to 1,000 carbon atoms.

[0037] In a preferred embodiment, the functional group is at least one selected from the group consisting of methylene, urethane, ester, ether, oxide, ethylene oxide, propylene oxide, ethylene glycol, propylene glycol, butadiene, imide, amine, amide, epoxy, olefin, sulfone, or a combination thereof.

[0038] In a preferred embodiment, the acrylate compound is included in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the active material for the positive or negative electrode.

[0039] In a preferred embodiment, the curing agent is at least one of a thermal curing agent and a photocuring agent, and is included in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the acrylate compound.

[0040] In a preferred embodiment, the thermal curing agent comprises a peroxide or an azo compound, and the photocuring agent comprises a phenyl ketone compound or a phosphine oxide compound.

[0041] In a preferred embodiment, the active material for the positive or negative electrode comprises at least one selected from the group consisting of lithium, manganese, nickel, cobalt, aluminum, iron, phosphorus, tin, titanium, carbon materials, silicon, silicon oxide, sulfur, and combinations thereof.

[0042] In addition, the present invention provides a primer layer composition comprising 0.05 to 300 parts by weight of a nanocarbon material and a solvent per 100 parts by weight of any one of the binder compositions described above, and having a solid content of 0.2 to 40% by weight.

[0043] In a preferred embodiment, the nanocarbon material is at least one selected from the group consisting of conductive carbon black, graphene, single-wall carbon nanotubes, double-wall carbon nanotubes, multi-wall carbon nanotubes, branched carbon nanotubes, carbon nanoplates, and carbon nanoribbons.

[0044] In addition, the present invention provides an electrode for a secondary battery including a positive electrode material layer or a negative electrode material layer made of the electrode material layer composition for a dry process described above.

[0045] In addition, the present invention provides a method for manufacturing an electrode for a secondary battery, comprising: a composition preparation step of preparing an electrode material layer composition for a dry process as described above; a sheet forming step of forming a positive electrode material layer sheet or a negative electrode material layer sheet with the electrode material layer composition for a dry process; an attachment step of attaching the positive electrode material layer sheet or the negative electrode material layer sheet to a metal plate; a curing step of curing the attached positive electrode material layer sheet or the negative electrode material layer sheet; and a step of rolling an electrode obtained by performing the curing step.

[0046] In a preferred embodiment, the attachment step is performed including: forming a primer layer on the metal electrode plate; and arranging the positive electrode material layer sheet or the negative electrode material layer sheet on the primer layer and then pressing it.

[0047] In a preferred embodiment, the curing step is performed through at least one of thermal curing at 50°C to 180°C for 5 to 30 minutes and photocuring through light irradiation.

[0048] In addition, the present invention provides a lithium ion battery including the electrode for a secondary battery described above.

[0049] In addition, the present invention provides a lithium ion battery including a secondary battery electrode manufactured by the above-described manufacturing method.

[0050] According to the above-described binder composition for electrode manufacturing of the present invention and the electrode material layer composition including the same, regardless of whether it is used in a wet process or a dry process, including a ternary copolymer, the binder composition can increase the bonding strength between each component in the electrode, is flexible, has excellent adhesion to the electrode metal, and does not interfere with the movement of lithium ions, so that the electrical conductivity is stably maintained and the electrochemical properties are excellent.

[0051] In addition, the secondary battery of the present invention is excellent in environmental friendliness and economic feasibility because it eliminates the complex process of removing and capturing a solvent, including an electrode manufactured by a dry process.

[0052] Therefore, the secondary battery of the present invention has the advantage that electrochemical characteristics such as electric capacity and charge / discharge cycle characteristics can be stably maintained.

[0053] The effects of the present invention are not limited to the effects mentioned above, and other effects not mentioned will be clearly understood by those skilled in the art from the description below.

[0054] Figures 1a and 1b are examples of chemical structures of ethylene glycol-maleic acid-acrylic acid copolymer and ethylene glycol-maleic acid-acrylonitrile copolymer, which are ternary copolymers manufactured in Examples 1 and 2 of the present invention, respectively.

[0055] Figure 2 is a photograph of the obtained copolymer of Example 2 of the present invention.

[0056] Figure 3 shows the results of a charge / discharge cycle test of a positive electrode manufactured by a wet process according to Example 5 of the present invention.

[0057] Figure 4 shows the results of a charge / discharge cycle test of a negative electrode manufactured by a wet process according to Example 6 of the present invention.

[0058] Figure 5 shows the results of a charge / discharge cycle test of a positive electrode 1 manufactured by a dry process according to Example 7 of the present invention.

[0059] Figure 6 shows the results of a charge / discharge cycle test of positive electrode 2 manufactured by a dry process according to Example 9 of the present invention.

[0060] Figure 7 shows the results of a charge / discharge cycle test of a comparative electrode 2 manufactured by a dry process in comparative example 2 of the present invention.

[0061] Figure 8 shows the results of a charge / discharge cycle test of a positive electrode 4 manufactured by a dry process according to Example 11 of the present invention.

[0062] The terms used in this invention have been selected from widely used, common terms, taking into account the functions of the invention. However, these terms may vary depending on the intentions of those skilled in the art, precedents, the emergence of new technologies, etc. Furthermore, in certain cases, the applicant may arbitrarily select terms, and in such cases, their meanings will be described in detail in the description of the relevant invention.

[0063] In the present invention, when the terms "includes," "has," and "consists of," etc. are used, other parts may be added unless "only" is used. When a component is expressed in the singular, it includes cases where the plural is included unless there is a specifically stated description.

[0064] When interpreting a component, it is interpreted as including the error range even if there is no separate explicit description.

[0065] The characteristic parts of each of the various embodiments of the present invention can be partially or wholly combined or combined with each other, and can be technically linked and driven in various ways, and each embodiment can be implemented independently of each other or can be implemented together in a related relationship.

[0066] Hereinafter, the technical configuration of the present invention will be described in detail with reference to the attached drawings and preferred embodiments.

[0067] However, the present invention is not limited to the embodiments described herein and may be embodied in other forms. The same reference numbers used to describe the present invention throughout the specification represent the same components.

[0068] The technical feature of the present invention is to provide a new use of a ternary copolymer manufactured by synthesizing a glycol compound, a maleic acid compound, or a complex chemically bonded thereof, and a third monomer, which can be used as a binder for both a dry process and a wet process, and which is flexible and can enhance the bonding strength between each component in an electrode, has excellent adhesion to a plate metal, and does not interfere with the movement of lithium ions, and thus has excellent electrochemical properties, and a binder composition for manufacturing an electrode, and an electrode material layer composition and a primer layer composition for a dry process, which contain the same. In addition, the electrode material layer composition for a dry process can manufacture an electrode layer having a thinner thickness, and thus the electrode for a secondary battery which is effective in miniaturization, and a secondary battery manufactured therefrom can stably maintain electrochemical properties such as electric capacity and charge / discharge cycle characteristics.

[0069] As such, the present invention has a technical characteristic in a novel binder composition that binds active materials and conductive materials, which are components of a secondary battery, and adheres an electrode layer (or electrode composition layer) composed of these to a metal plate, which is a current collector. Therefore, the binder composition for electrode manufacturing of the present invention is not limited to a lithium-ion battery, but can be applied to all types of secondary batteries including an anode and / or cathode including an active material, a conductive additive, and a binder composition. Hereinafter, the description will be mainly made using a lithium-ion battery. In addition, although the description will be mainly made using a positive electrode, it is obvious that the present invention is a technology that can be commonly applied to active materials for a positive electrode or a negative electrode, regardless of the type of active material.

[0070] Accordingly, the present invention provides a binder composition for manufacturing a dry process electrode, which comprises a three-component copolymer composed of a glycol compound, a maleic acid compound, and a third monomer.

[0071] Glycol compounds are compounds with ion conductivity that are introduced to help the movement of lithium ions within a battery or at least to prevent the movement of lithium ions. They may be compounds containing ethylene glycol (HO-(CH2-CH2-O)nH) or ethylene oxide (-(CH2-CH2-O)n-)) as a main chain. These two compounds have fundamentally the same chemical structure, and if the molecular weight is 20,000 g / mol or less, they are called ethylene glycol (EG), and if it is more, they are called ethylene oxide (EO). Therefore, hereinafter, in the present invention, they will be referred to as glycol compounds. As an example of implementation, the glycol compound may be a compound composed of an olefin compound such as ethylene or propylene and oxygen, and may have a main chain of 2 to 1,000 carbon atoms, and may be at least one selected from the group consisting of ethylene glycol, ethylene oxide, propylene glycol, and propylene oxide.

[0072] Maleic acid compounds are components used to increase the adhesive strength between metal plates and active materials. For example, maleic anhydride is a compound that contains a so-called 5-membered ring structure composed of 5 carbons and oxygen atoms with 2 carboxyl groups, and may be a compound that can form a copolymer by combining with other compounds. As an example, it may be at least one selected from the group consisting of maleic acid, salts thereof, and anhydrides thereof.

[0073] If necessary, these glycol compounds and maleic acid compounds can be prepared in advance as copolymers (hereinafter referred to as glycol-maleic acid complexes) through a chemical reaction using an organic acid reaction initiator.

[0074] The third monomer is a compound that constitutes the ternary copolymer of the present invention through a copolymerization reaction with the above-described glycol compound and maleic acid compound or glycol-maleic acid complex, and any monomer that is formed by bonding another component to the vinyl group and is a compound having a vinyl group (CH2=CH-) main chain and to which another functional group is attached can be used.

[0075] Representative compounds included in the third monomer include various types of compounds, such as monomers having a double bond in an acrylic group, a methacrylic group, an acrylonitrile group, an imidazole group, a vinylpyrrolidone group, an ethylene group, a propylene group, or a pendant group. Any compound composed of one or more of these can be used.

[0076] As an example of implementation, it may be any one selected from the group consisting of an acrylic compound, an acrylonitrile compound, an ethylene compound, an imidazole compound, an imidazolium compound, a propylene compound, and a vinylidene compound.

[0077] As another embodiment, the third monomer may be at least one selected from the group consisting of acrylic compounds, imidazole, imidazolium, acrylate, methacrylate, acrylonitrile, pyrrolidone, ethylene, propylene, or monomers having a double bond in the pendant group. Therefore, it is obvious that the actual synthetic method for each component may differ somewhat.

[0078] Here, the acrylic compound may be a compound having the following chemical formula.

[0079] [Chemical Formula 1]

[0080] CH2=CH-COO-R

[0081] At this time, R is any one of -H, an alkyl group, an alkenyl group, an alkynyl group, a phenyl group, and an amino group.

[0082] Additionally, acrylonitrile compounds are compounds in which a cyanide (-CN) group is attached to a vinyl group (CH2=CH-) backbone, and a representative example thereof may be acrylonitrile (CH2=CH-CN).

[0083] The following description of the ternary copolymer of the present invention will primarily focus on the use of an acrylic compound or an acrylonitrile compound as the third monomer. However, it should be understood that the scope of the present invention is not limited to acrylic or acrylonitrile compounds.

[0084] The ternary copolymer included in the binder composition for electrode manufacturing of the present invention can be synthesized by using the above-described compound, i.e., a glycol-based compound and a maleic acid-based compound or a glycol-maleic acid complex and a third monomer, by the two methods described below.

[0085] The first method is a one-step synthesis method, in which all components, including a glycol compound, a maleic acid compound, and a third monomer, are mixed in a solvent, and two reaction initiators, i.e., a reaction initiator for the glycol-maleic acid complex reaction and a reaction initiator for the subsequent synthesis reaction with the third monomer, are separately added, or a reaction initiator capable of participating in both reactions is added as a single reaction initiator to synthesize a ternary copolymer, and then the final ternary copolymer is synthesized through an appropriate filtering and washing process.

[0086] The second method is a two-step synthetic method, in which a glycol compound and a maleic acid compound are first reacted with a reaction initiator to form a glycol-maleic acid complex, and then a third monomer composed of this complex and a vinyl group is added to a solvent, and a reaction initiator is added to react again to synthesize a ternary copolymer.

[0087] In both of the above methods, a glycol compound and a maleic acid compound react during the synthesis reaction to form a glycol-maleic acid complex, which is then copolymerized with a third monomer to ultimately produce a ternary copolymer. Therefore, the sum of the weights of the glycol compound and the maleic acid compound initially added in the first synthesis step can be regarded as the weight of the glycol-maleic acid complex.

[0088] Therefore, in the three-component copolymer included in the binder composition for electrode manufacturing of the present invention, it may be experimentally convenient to calculate the component ratio of each component as a molar ratio for the component ratio of the glycol compound and the maleic acid compound, and a weight ratio for the component ratio of the glycol-maleic acid complex and the third component.

[0089] As a result, in the ternary copolymer synthesized by the above-described synthetic method, the glycol compound:maleic acid compound may be included in a molar ratio of 99:1 to 1:99, and the glycol compound and the maleic acid compound:third monomer may be included in a weight ratio of 99:1 to 1:99. More preferably, the glycol compound:maleic acid compound may be included in a molar ratio of 90:10 to 10:90, and the glycol compound and the maleic acid compound:third monomer may be included in a weight ratio of 90:10 to 10:90. If each molar ratio or weight ratio is below the lower limit or above the upper limit, it is disadvantageous because the characteristics of the two components are not well expressed since it is the same for either component.

[0090] In addition, the ternary copolymer included in the binder composition for electrode manufacturing of the present invention can be synthesized by various methods using the above-described compounds, that is, a glycol-based compound and a maleic acid-based compound or a glycol-maleic acid complex and a third monomer. For example, a glycol-maleic acid complex can be synthesized by using an organic acid-based reaction initiator such as acetic acid or paratoluenesulfonic acid. In addition, the synthesis of this glycol-maleic acid complex and the third component, acrylonitrile or acrylic acid mono, can be synthesized by various methods, such as a radical polymerization method using a radical-generating compound such as 2,2-azobisisobutyronitrile (AIBN), a peroxide, etc., or an oxidative polymerization method using ammonium persulfate. In addition, a ternary copolymer can be synthesized by combining or sequentially using one or more of various methods, such as a method using a photoinitiator, an ionic polymerization method, a redox polymerization method using a redox reaction, or a thermal polymerization method. The detailed reaction conditions of each polymerization method, such as the reaction temperature and time, the content of the reaction initiator, etc., are known to those skilled in the art, for example, using various solvents such as DMF or water at a temperature of 60-120 degrees for 4-48 hours, and therefore the present invention is not limited to a specific method.

[0091] The number average molecular weight of the ternary copolymer included in the binder composition for electrode manufacturing of the present invention is suitably in the range of 10,000-1,000,000 g / mol. If the number average molecular weight of the copolymer is 10,000 g / mol, the molecular weight is too low, which is disadvantageous because the physical properties of the electrode layer deteriorate, and if it is more than 1,000,000 g / mol, it is not only difficult to obtain by a general radical polymerization method, but also the molecular weight is too high and the viscosity is too high, which makes it difficult to mix with the active material and the conductive material, which is rather disadvantageous.

[0092] In another embodiment, the binder composition for electrode manufacturing of the present invention may further include a binder of another type in addition to the ternary copolymer of the above-described composition, and the ternary copolymer:other type of binder may be included in a weight ratio of 90:10 to 10:90. In this case, the characteristics of each binder composition are complemented to produce a better effect, which is advantageous, and if the upper and lower limits are exceeded, it is practically not a mixture but almost like a single binder, so its role as a mixed binder is minimal, which is disadvantageous.

[0093] Other types of binders may be any known binder, and one or more of the binders may include, for example, polyolefins, polyalkylenes, polyethers, styrene-butadiene rubber (SBR), polysiloxanes and copolymers of polysiloxanes, branched polyethers, polyvinylethers, polyacrylic acid, polyvinylcarbonate, copolymers thereof, and / or mixtures thereof. As other embodiments, the binder may further include guar, alginic acid, poly[(isobutylene-alt-maleic acid, ammonium salt)-co-isobutylene-alt-maleic anhydride)], poly(ethylene-alt-maleic anhydride), poly(methylvinyl ether-alt-maleic anhydride), polyacrylonitrile (PAN), acrylonitrile-acrylic acid-maleic anhydride copolymer, acrylic acid-acrylonitrile copolymer, imidazole polymers and copolymers, poly(methyl methacrylate) (PMMA), poly(vinyl chloride) (PVC), and polyvinyl ether. The binder may include cellulose. In some embodiments, the polyolefin may include polyethylene (PE), polypropylene (PP), polytetra fluoroethylene (PTFE), polyvinylidene fluoride (PVDF), copolymers thereof, and / or mixtures thereof.In another embodiment, the one or more binders can include polyvinylidene chloride, poly(phenylene oxide) (PPO), polyethylene-block-poly(ethylene glycol), poly(ethylene oxide) (PEO), poly(phenylene oxide) (PPO), polyethylene-block-poly(ethylene glycol), polydimethylsiloxane (PDMS), polydimethylsiloxane-co-alkylmethyl siloxane, copolymers thereof, and / or mixtures thereof. In certain embodiments, the fibrillable binder is PTFE. The one or more binders can include cellulose or a derivative of cellulose. Derivatives of cellulose include, for example, cellulose esters, such as cellulose acetate; A cellulose ether, such as methyl cellulose, ethylcellulose, hydroxylpropylcellulose (HPC), hydroxyl propylmethylcellulose (HPMC), or hydroxyethyl cellulose (HEC); cellulose nitrate; cellulosechitosan, such as carboxymethyl cellulose chitosan; or a carboxyalkyl cellulose, such as carboxymethylcellulose (CMC), carboxyethylcellulose, carboxypropyl cellulose, or carboxyisopropyl cellulose. In a further embodiment, the cellulose or cellulose derivative may comprise a cellulose salt.In another embodiment, the cellulose salt cation may be selected from sodium, ammonium, calcium, or lithium. For example, the cellulose or cellulose derivative may include sodium cellulose or a sodium cellulose derivative selected from sodium cellulose ester, sodium cellulose ether, sodium cellulose nitrate, or sodium carboxyalkylcellulose. The CMC may include sodium carboxymethylcellulose. In some embodiments, the one or more binders include CMC, PVDF, and / or PTFE.

[0094] The binder composition for electrode manufacturing of the present invention having such a configuration can be used not only as a binder for conventional wet processes and dry processes, but can also be used in a primer layer composition.

[0095] Next, the electrode material layer composition for a dry process of the present invention comprises an active material for a positive or negative electrode; a binder composition having the above-described composition; and a conductive material. Here, the binder composition may comprise a ternary copolymer or a ternary copolymer and one or more other types of binders as described above. In particular, the composition may comprise 85-99.4 wt% of an active material for a positive or negative electrode, 0.5-10 wt% of the binder composition, and 0.1-5 wt% of a conductive material.

[0096] Here, the active material for the positive or negative electrode may be any active material known in the art as a material suitable for use in the positive or negative electrode of a secondary battery. In one embodiment, it may be at least one selected from the group consisting of alkali metal elements such as lithium, alkaline earth metal elements, manganese, nickel, cobalt, aluminum, iron, tin, graphite, titanium, silicon, silicon oxide, sulfur, and combinations thereof. If the active material is less than 85 wt%, the electric capacity of the secondary battery is lowered, which is disadvantageous, and if it exceeds 99.4 wt%, the binder content is too low, which lowers the bonding between each component and the adhesive strength with the electrode plate, which deteriorates the mechanical properties, which is rather disadvantageous.

[0097] If the binder composition content is less than 0.5 wt%, there is too little binder, which is disadvantageous because the active material electrode layer formed on the electrode plate is too easily detached, and if it exceeds 10 wt%, there is an advantage in that the active material electrode layer is strongly attached to the electrode plate, but the active material content becomes relatively small, which is disadvantageous because the electric capacity per electrode volume becomes too small.

[0098] The conductive material is a component included for electrical conductivity between each component in the electrode layer and electrical conductivity between the electrode layer and the metal electrode plate which is a current collector, and carbon-based nanomaterials can be used. In one embodiment, any one or more of nanomaterials such as conductive carbon black, graphene, carbon nanotubes (single-walled, double-walled, multi-walled, branched, etc.), carbon nanoribbons, and carbon nanoplates can be mixed and used. In general, it is preferable to use a mixture of carbon nanotubes having a high aspect ratio and nanocarbon materials having an aspect ratio of less than 100 (e.g., conductive carbon black).

[0099] If the content of the conductive agent is lower than 0.1 wt%, the electrical conductivity decreases, which is disadvantageous. If it exceeds 5 wt%, the content of the active material is relatively low, which ultimately lowers the capacity of the secondary battery manufactured from it, which is rather disadvantageous.

[0100] If necessary, the electrode material layer composition for a dry process of the present invention may further include an acrylate-based compound and a curing agent for the acrylate-based compound.

[0101] That is, in forming an electrode material layer by a dry process, each component must first be dry mixed and then pressure and heat must be applied to create an electrode layer in the form of a thin film. However, when manufacturing an electrode material layer composition by mixing an active material, a binder composition, and a conductive material, an acrylate compound that exists in a liquid state at room temperature but changes into a solid state when cured by an appropriate method and a curing agent thereof are further included, thereby acting as a liquid processing aid during kneading in the dry process, thereby enabling the active material sheet to be manufactured thinner and more easily, and the surface appearance of the manufactured electrode layer is attractive, which is advantageous in manufacturing an electrode plate for a secondary battery.

[0102] Here, the acrylate compound is not limited as long as it has the property of being liquid at room temperature but solidifying through a separate treatment process, i.e., a curing process. This is because, when an appropriate type of curing agent is added to an acrylate compound that is liquid at room temperature and cured under appropriate conditions, it is converted into a polymer with a three-dimensional network structure while being solid, and the acrylate compound does not leach into the electrolyte, so it does not have a negative effect on the performance of the battery. Furthermore, in the case of an acrylate compound with an appropriate functional group, after curing, it forms a polymer with a three-dimensional network structure, which is advantageous because it can also increase the adhesion to the metal electrode plate. Meanwhile, although the examples mainly describe acrylate compounds (Acrylates), it is obvious that methacrylate compounds with similar properties are also included. Therefore, the acrylate compounds used in the present invention should be understood to include acrylate compounds and methacrylate compounds, as well as compounds of the same type with different substituents.

[0103] The acrylate compound is not limited as long as it is an acrylate compound containing at least two functional groups. The functional groups contained are not limited as long as they can react with heat or light, but may be at least one selected from the group consisting of methylene, urethane, ester, ether, oxide, ethylene oxide, propylene oxide, ethylene glycol, propylene glycol, butadiene, imide, amine, amide, epoxy, olefin, sulfone, or a combination thereof, and in particular, it may be an acrylate compound containing 2 to 16 functional groups. If the functional groups are 2 or less, it is a monofunctional acrylate with a low curing point, which is disadvantageous because the curing reaction is too slow, and if the functional groups are 16 or more, there is too much functionality, which makes the curing reaction too fast, making it difficult to control the reaction speed, or there is a concern that it may be converted into a polymer with hard properties in a short period of time, which is rather disadvantageous.

[0104] In addition, the acrylate compound used in the present invention means all forms of acrylate compounds, such as monomers and oligomers, unless otherwise specified, and may be in the form of a monomer or oligomer having a main chain of 2 to 1,000 carbon atoms, as an example. If the main chain has less than 2 carbon atoms, it becomes a polymer that is very brittle during post-curing, making it unsuitable as a binder material, which is disadvantageous. On the other hand, if the main chain has more than 1,000 carbon atoms, there is a concern that geometric hindrance may occur, which may rather hinder its function as a binder. Since the main technical feature of the present invention is to use an acrylate compound that is liquid at room temperature and post-cured through a separate treatment as a binder, it is obvious that the above-mentioned functional groups are only one example and are not limited thereto.

[0105] The acrylate compound used in the present invention may be at least one selected from the group consisting of various aliphatic and aromatic acrylate monomers such as triethylene glycol acrylate, trimethylpropane triacrylate, dipentaerythritol hexaacrylate, trimethylolpropane trimethacrylate, bisphenol A ethylene oxide dimethacrylate, and the like, and an oligomer which is a complex in which the monomers of the main chain forming these acrylates are formed of two or more units, for example, methylene, urethane group, ester group, ether group, oxide group, ethylene oxide, propylene oxide, ethylene glycol, propylene glycol group, butadiene group, imide group, amine group, amide group, epoxy group, olefin group, sulfone group, etc.

[0106] The acrylate compound may be included in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the active material for the positive or negative electrode. If the content of the acrylate compound is less than 0.1 parts by weight, the content of the acrylate compound is too low, so the effect of the acrylate is minimal, which is disadvantageous. If the content is 10 parts by weight or more, the acrylate content is unnecessarily high, so the electric capacity per unit volume is lowered, which is rather disadvantageous.

[0107] An acrylate curing agent is a component that converts an acrylate compound, which is liquid at room temperature, into a polymer with a three-dimensional network structure by mixing and then curing it through a separate process. One or more thermal curing agents and photocuring agents can be used. That is, when photocuring does not occur well, especially when the electrode layer is thick, the use of a photocuring agent (photoinitiator) and thermal curing agent in combination can be more effective. Any type of curing agent can be used as long as it is a substance that generates radicals by heat or light.

[0108] More specifically, the thermal initiator is not limited to a specific type as long as it is a curing agent containing a peroxide or an azo compound and decomposes at 50°C to 180°C to generate a reaction initiator. As an example, the curing agent containing a peroxide (peroxide initiator) may include benzoyl peroxide (BP) that generates oxygen radicals, and the curing agent containing an azo compound may include 2,2-azobisisobutyronitrile (AIBN). At this time, if the decomposition temperature of the curing agent is lower than 50°C, the decomposition temperature is too low and the reaction initiator is generated too easily, which is disadvantageous. If the decomposition temperature is higher than 180°C, the temperature for the curing reaction is too high and is disadvantageous in terms of cost. Preferably, it is preferable to use a curing agent that decomposes at a temperature of 50°C to 150°C.

[0109] The photoinitiator may be a curing agent including a phenyl ketone compound or a phosphine oxide compound that generates radicals when exposed to light such as UV. As an example, solid and liquid photoinitiators such as hydroxycyclohexyl phenyl ketone, hydroxydimethylacetophenone, trimethylbenzoyldiphenylphosphine oxide, or methyl benzoyl formate may be used.

[0110] The hardener may be included in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the acrylate compound. However, if the content of the hardener is less than 0.1 parts by weight, the acrylate compound is likely to remain in a liquid state even after the curing reaction due to non-curing, which is disadvantageous. If the content of the hardener exceeds 20 parts by weight, over-curing may occur, resulting in the compound becoming too hard, or radicals generated from the hardener that did not fully participate in the curing reaction may cause a side reaction, which may deteriorate the binder that is additionally included.

[0111] Meanwhile, the binder composition for manufacturing an electrode including the ternary copolymer of the present invention may be used not only for the dry process described above but also as a binder for a conventional wet process. For example, the ethylene glycol-maleic acid-acrylonitrile copolymer of the present invention may be dissolved in a solvent such as NMP, and then an NCM-based positive electrode active material and a conductive material such as conductive carbon black or carbon nanotubes may be added and dispersed therein to prepare an electrode composition slurry, and this slurry may be applied to a metal electrode plate and dried to manufacture a positive electrode plate. In addition, in the case of an all-solid-state battery, it is obvious that an electrode composition may be prepared using the ternary copolymer of the present invention as a binder for the active material or other components used, and then an electrode may be manufactured using this.

[0112] Next, the primer layer composition of the present invention includes a ternary copolymer and a nanocarbon material. The nanocarbon material is used to impart conductivity to the primer layer and is not limited as long as it is a nano-sized carbon material. However, as an example, the carbon nanomaterial may be a mixture of one or more of carbon nanomaterials such as conductive carbon black, carbon nanotubes (single-walled, double-walled, and multi-walled), graphene, or carbon nanoplates (Carbon nanotubes: CNPs), and carbon nanoribbons.

[0113] The content of the nanocarbon material may be in the range of 0.05-300 parts by weight per 100 parts by weight of the ternary copolymer. If the content of the nanocarbon material is less than 0.05 parts by weight, the content of the electrical conductivity increasing agent is too low, resulting in poor electrical conductivity, which is disadvantageous. On the other hand, if the content of the nanocarbon material is 300 parts by weight or more, the content of the electrical conductivity increasing agent is too high, resulting in excessively high viscosity of the primer material, which in turn results in poor coatability, which is disadvantageous. Any solvent, including organic solvents and aqueous solvents, may be used in the preparation of the primer layer composition, and is not limited to a specific solvent.

[0114] The method for preparing the primer layer composition comprises high-pressure and high-speed dispersion of the ternary copolymer of the present invention and the nanocarbon material in a solvent such as NMP or water. The solid content in the primer layer composition may be 0.2-40 wt% based on the total weight of the solution. If the solid content is less than 0.2%, the wet thickness must be too thick to obtain a primer layer of a certain thickness, which is disadvantageous. On the other hand, if the solid content is 40% or more, the viscosity is too high, making it difficult to obtain a primer layer of a thin thickness, which is rather disadvantageous.

[0115] As described below, the thickness of the primer layer formed on the metal electrode surface can be in the range of 0.05-5 um, and when the primer layer is formed as a film with a thickness of 1.0 micron on a polyester film, the surface resistance is 10 7 It is desirable that the surface resistance of the primer layer be less than 10 Ω / area. This is to facilitate the movement of electrons passing through the primer layer. The surface resistance of the primer layer is 10 7 If the area is greater than the ohm / area, the movement of electrons is restricted to some extent, which can ultimately lead to a decline in cell performance, which is disadvantageous.

[0116] In this way, when forming an electrode plate by attaching an electrode composition sheet to a metal plate after making it through a dry process, it is advantageous to form a primer layer on the surface of the metal plate if necessary and then attach an electrode composition layer thereon. Since the primer layer used here must have excellent electrical conductivity, the ternary copolymer of the present invention was used as a binder and a nanocarbon material was mixed therein to prepare a primer composition. The reason for using a primer composition prepared using a binder composition including the ternary copolymer of the present invention is that the binder of the primer layer and the active material layer must be the same so that the adhesive force between the two layers is maximized.

[0117] Next, the electrode for a secondary battery of the present invention includes a positive electrode material layer or a negative electrode material layer composed of any one of the above-described electrode material layer compositions for a dry process. The positive electrode material layer or the negative electrode material layer has a thickness of less than 100 μm, and in particular, when the electrode material layer composition for a dry process includes an acrylate-based compound, an electrode film that is thinner and has excellent properties can be manufactured.

[0118] As described below, when manufacturing the secondary battery electrode of the present invention by a dry process, that is, when attaching a sheet manufactured with an electrode material layer composition for a dry process to a metal electrode plate, a metal electrode plate (positive electrode: aluminum, negative electrode: copper) on which a primer layer was formed was used. However, unlike the dry process, in the wet process, the adhesion of the electrode layer is very excellent even without a primer layer, so that the electrode layer was formed on a metal electrode plate that was not primed.

[0119] Next, the method for manufacturing an electrode for a secondary battery of the present invention may include a composition preparation step of preparing any one of the above-described dry processing electrode material layer compositions; a sheet forming step of forming a positive electrode material layer sheet or a negative electrode material layer sheet with the dry processing electrode material layer composition; an attachment step of attaching the positive electrode material layer sheet or the negative electrode material layer sheet to a metal electrode plate; a curing step of curing the attached positive electrode material layer sheet or the negative electrode material layer sheet; and a rolling step of obtaining an electrode by performing the curing step. Here, each of these steps may be processed in a batch manner or a continuous process may be used to manufacture a final electrode plate. Introducing a continuous process may be the most efficient manufacturing process.

[0120] In the composition preparation step, any known mixing method can be used as long as all components, i.e., the active material for the negative or positive electrode, the binder composition for electrode manufacturing, and the conductive additive, are added and kneaded while applying a shear force in a dry manner. If necessary, a liquid acrylate compound and a curing agent for the acrylate compound can be further added. Here, various mixing methods can be used, and the mixing device includes a mixer-type mixer (low-speed and high-speed mixer) such as a Henschel mixer equipped with a blade of an appropriate shape, or a mixing device capable of a continuous process in the form of an extruder. Representative mixing devices such as a single screw extruder, twin screw extruder, or continuous kneader with an added mixing function are effective.

[0121] A sheet forming step can be performed by using a die capable of forming a sheet of an appropriate thickness at the end of such a continuous mixing device to form a sheet of an active material composition of a certain thickness and rolling it several times to form a sheet of a desired thickness. In the examples and comparative examples described below, a calendering method was used in which the sheet is passed between two rolls designed to have a certain interval.

[0122] The attachment step may be performed including a step of forming a primer layer on a metal electrode plate; and a step of arranging and then pressing the positive electrode material layer sheet or the negative electrode material layer sheet on the primer layer. In a continuous process, the above-described attachment step may be performed on a metal electrode plate supplied through a separate supply device. Here, the primer layer may be formed to a thickness of 0.05-5 um by coating the frying layer composition having the above-described configuration. If the thickness is less than 0.05 um, the primer layer is too thin, making the coating process itself difficult and the adhesion enhancement effect is insignificant, which is disadvantageous. On the other hand, if the thickness is 5 um or more, the electrically conductive layer is too thick, which may hinder the movement of lithium ions in this region, which is rather disadvantageous.

[0123] The curing step is a process for curing the positive electrode material layer sheet or negative electrode material layer sheet attached to the metal electrode plate in the attachment step to solidify the acrylate compound so that it acts as a binder, and also for strengthening the adhesion of the sheet to the metal electrode plate. The curing step may be performed through either thermal curing at 50°C to 150°C for 5 to 30 minutes and / or photocuring using UV irradiation.

[0124] The rolling step can be performed to increase the electrode density by finally pressing the electrode material layer obtained by performing the hardening step with an appropriate force.

[0125] Example 1

[0126] As follows, a binder composition 1 for electrode manufacturing was manufactured by synthesizing an ethylene glycol-maleic acid-acrylic acid copolymer as a three-component copolymer in one or two steps.

[0127] 1. Step 1 synthesis

[0128] Ethylene glycol (4,000 g / mol) and maleic acid (116 g / mol) were weighed at a molar ratio of 1:1 and placed in dimethylformamide (DMF), and then mixed with acrylic acid in a weight ratio of 1:1 relative to the total weight of ethylene glycol and maleic acid. At this time, the mixture was mixed so that the solid content in the mixed solution was 5 wt%, and the temperature was raised to 70℃ and stirred for 10 minutes. While maintaining this temperature, 1.5 wt% of ammonium persulfate (APS), a reaction initiator, was slowly dropped into the mixture and reacted for 5 hours. After the reaction was complete, ethanol was added to solidify the mixture, and then filtered / purified and vacuum-dried (40℃, 24 hours) to obtain the final ternary copolymer.

[0129] 2. 2-step synthesis

[0130] First, weigh out ethylene glycol (4,000 g / mol) and maleic acid (116 g / mol) in a molar ratio of 1:1, then add them to dimethylformamide (DMF) so that the solid content becomes 5 wt%, and mix them by stirring at 90℃ for 10 minutes. Then, at the same temperature, slowly add 1.5 wt% of para-toluenesulfonic acid (p-CH3CH6CH4SO3H) (reaction initiator) dropwise to this mixture, and react for at least 6 hours until the color of the mixture turns white. After the reaction is complete, slowly pour the mixture into ether to precipitate the compound, which is then filtered and dried under vacuum (50℃, 24 hours) to obtain an ethylene glycol-maleic acid complex.

[0131] The obtained ethylene glycol-maleic acid complex and acrylic acid were weighed in a weight ratio of 1:1 and added to water, stirred, and heated to 70°C. Afterwards, ammonium persulfate, a reaction initiator, was added dropwise and reacted for 10 hours to synthesize an ethylene glycol-maleic acid-acrylic acid ternary copolymer. At this time, the content of the reaction initiator, ammonium persulfate, was set to 1.5 wt% based on the total solid content. After all reactions were completed, the reactants were pressure filtered, and the obtained solid was vacuum-dried (40°C, 24 hours) to obtain an ethylene glycol-maleic acid-acrylic acid ternary copolymer.

[0132] Example 2

[0133] A binder composition 2 for electrode manufacturing was manufactured by synthesizing an ethylene glycol-maleic acid-acrylonitrile copolymer as a three-component copolymer in one step as follows.

[0134] The first step of the synthesis process of Example 1 was performed in the same manner as described above, except that acrylonitrile (53 g / mol) instead of acrylic acid was used, to obtain an ethylene glycol-maleic acid-acrylonitrile copolymer.

[0135] Example 3

[0136] As follows, a binder composition 3 for electrode production was prepared by further including PTFE as a different type of binder in the ethylene glycol-maleic acid-acrylonitrile copolymer synthesized in Example 2.

[0137] Ethylene glycol-maleic acid-acrylonitrile copolymer and PTFE were uniformly mixed at a weight ratio of 3:1.

[0138] Example 4

[0139] A binder composition 4 for electrode production was prepared by performing the same method as Example 3, except that the ethylene glycol-maleic acid-acrylonitrile copolymer and PTFE were used in a weight ratio of 1:1.

[0140] Example 5

[0141] Using the binder composition 2 for electrode manufacturing, a positive electrode composition slurry, a positive electrode, and a coin cell were prepared through a wet process as follows.

[0142] 1. Preparation of electrode composition slurry for positive electrode

[0143] 2.0 wt% of binder composition 2 for electrode manufacturing, 96.0 wt% of active material (NCM811), and 2.0 wt% of conductive carbon black were added to NMP (solid content in the slurry: 70%) and mixed in a C-mixer at a speed of 2,000 rpm for 20 minutes to prepare a slurry of an electrode composition for a positive electrode.

[0144] 2. Preparation of positive electrode

[0145] The above positive electrode composition slurry was applied on the aluminum foil, which is the positive electrode plate, and dried to a thickness of 40 microns (loading level: 10 mg / cm 2 ) was manufactured as a positive electrode plate having an electrode material layer formed thereon.

[0146] 3. Prepare the coin cell

[0147] Coin cells (CR2032) with a half-cell structure were manufactured using a positive electrode plate. At this time, lithium metal foil was used as a counter electrode, and the electrolyte was a mixture of carbonates such as ethylene carbonate (EC), propylene carbonate (PC), diethyl carbonate (DEC), vinylene carbonate (VC), and fluoroethylene carbonate (FEC) (weight ratio: EC / PC / DEC / VC / FEC=2 / 1 / 7 / 0.05 / 0.05), and 1.15 mol of LiPF6 was dissolved and used as an electrolyte. Coin cells were manufactured in a glove box filled with argon gas.

[0148] Example 6

[0149] Using the binder composition 1 for electrode manufacturing synthesized in two steps, a slurry of a negative electrode composition, a negative electrode, and a coin cell were prepared by a wet process as follows.

[0150] 1. Preparation of electrode composition slurry for negative electrode

[0151] 2.7 wt% of binder composition 1 for electrode manufacturing, 96.3 wt% of mixed active material (graphite / SiOx=90 / 10 wt%, theoretical capacity ~470 mAh / g), 1.0 wt% of carbon black, and 0.3 wt% of single-walled carbon nanotubes were added to a DMF / water mixed solvent (weight ratio: 8:2) (solid content in the slurry: 70%), and then mixed once more in a C-Mixer and mixed at 2,000 rpm for 10 minutes to manufacture a slurry of an electrode composition for a negative electrode.

[0152] 2. Preparation of the negative electrode

[0153] The above-mentioned electrode composition slurry for the negative electrode was applied onto copper foil and dried to manufacture a negative electrode plate composed of an electrode layer with a thickness of 20 microns.

[0154] 3. Prepare the coin cell

[0155] A cell (2032 type) for charge / discharge cycle testing was manufactured using a negative electrode plate. The electrolyte used was the electrolyte of Example 5.

[0156] Example 7

[0157] Using the binder composition 2 for electrode manufacturing, the electrode material layer composition 1 for dry process, the positive electrode 1 for secondary battery, and the coin cell were prepared as follows through a dry process.

[0158] 1. Preparation of electrode material layer composition for dry process

[0159] A binder composition 2 for electrode manufacturing (3.5 wt%), a positive electrode active material (NCM811, 95 wt%), and 1.5 wt% of conductive carbon black were mixed and kneaded using a kneader at a temperature of 120°C for 20 minutes at a speed of 40 rpm to manufacture a positive electrode material layer composition 1 for a dry process.

[0160] 2. Preparation of positive electrode

[0161] The manufactured positive electrode material layer composition for dry process is rolled again at room temperature to manufacture a positive electrode layer sheet with a thickness of 80 microns, and then placed on an electrode plate with a primer layer formed and pressed (8 kgf / cm 2 ) to manufacture a positive electrode plate.

[0162] 3. Prepare the coin cell

[0163] A coin cell (CR2032) with a half-cell structure was created using the above-mentioned positive electrode plate. The remaining configuration is the same as in Example 5.

[0164] Example 8

[0165] Using the binder composition 1 for electrode manufacturing synthesized in two steps, a negative electrode material layer composition 1 for dry process, a negative electrode 1, and a coin cell were prepared as follows through a dry process.

[0166] 1. Preparation of a negative electrode material layer composition for dry process

[0167] A dry process negative electrode material layer composition was manufactured by mixing 3.5 wt% of binder composition 1 for electrode manufacturing, 95.0 wt% of mixed active material (graphite / SiOx=90 / 10 wt%, theoretical capacity 470 mAh / g), 1.0 wt% of carbon black, and 0.5 wt% of single-wall carbon nanotube in the same manner as in Example 7.

[0168] 2. Preparation of the negative electrode

[0169] The manufactured negative electrode material layer composition for dry process was rolled again at room temperature to manufacture a negative electrode layer sheet with a thickness of 80 microns, and then this was attached to a copper foil on which a primer layer was formed to manufacture a negative electrode plate with a thickness of approximately 65 microns.

[0170] 3. Prepare the coin cell

[0171] A cell (2032 type) for charge / discharge cycle testing was manufactured using a negative electrode plate. The electrolyte used was the electrolyte of Example 5.

[0172] Example 9

[0173] 1. Preparation stage of electrode material layer composition for dry process

[0174] 1.5 wt% of binder composition 2 for electrode manufacturing, 2 wt% of acrylate compound (mixture of ethylene glycol-based bifunctional monomer and ethylene glycol-based hexafunctional oligomer in a weight ratio of 1:1), 2 wt% of AIBN (thermal curing agent) and 5 wt% of phosphine oxide-based curing agent (photocuring agent) based on the weight of the acrylate compound, positive electrode active material (NCM811, 95 wt%), and 1.5 wt% of conductive carbon black were mixed and kneaded using a kneader at a temperature of 120°C for 20 minutes at a speed of 40 rpm to manufacture a positive electrode material layer composition 2 for a dry process.

[0175] 2. Bipolar material layer sheet formation step

[0176] The positive electrode material layer composition 2 was rolled several times while applying a pressure of 7 kgf / cm2 to form a 70 ㎛ thick positive electrode material layer sheet.

[0177] 3. Attachment stage

[0178] ① Primer layer formation stage

[0179] To attach the cathode material layer sheet to the aluminum plate, a primer layer was formed on the plate surface as follows. The primer for the cathode plate was prepared by adding carbon nanotubes and an ethylene glycol-maleic anhydride-acrylonitrile copolymer (CNP Solutions, Korea) to NMP, stirring at room temperature for 10 minutes, and then dispersing the mixture using a pressure spray method. The content of carbon nanotubes in the binder was 20 wt% based on the total weight of the copolymer, and the solid content in the dispersion was 4 wt%. The primer layer was formed to a thickness of approximately 1.0 μm on aluminum foil (thickness: 12 μm) using a bar coater (drying: 130°C, 2 minutes). The results of a tape test on the primer layer confirmed that the primer layer was well adhered to the plate without peeling off. In addition, the surface resistance of the plate with the primer layer formed was 400 ohm / area.

[0180] ② Pressing stage

[0181] A temporary positive electrode was formed by placing a positive electrode material layer sheet on an aluminum plate on which a primer layer was formed and pressing it.

[0182] 4. Hardening stage

[0183] After treating the temporary positive electrode at a temperature of 120 degrees for 10 minutes and then irradiating it with UV light (700 mJ / cm2), the ethylene glycol difunctional monomer and the hexafunctional ethylene glycol oligomer, which are acrylate compounds, were cured, so that the acrylate compound used as a binder served as a binder that was not dissolved in the electrolyte.

[0184] 5. Rolling stage

[0185] The positive electrode material layer composition 2 that went through the hardening step was finally manufactured as a positive electrode 2 for a secondary battery including a positive electrode material layer sheet with a thickness of 70㎛ through a rolling process so that the electrode density became 1.0 g / cm3.

[0186] Example 10

[0187] In Example 9, when preparing an electrode material layer composition for a dry process, 2 wt% of a binder composition 2 for electrode manufacturing, 1.5 wt% of an acrylate compound (mixture of an ethylene glycol-based bifunctional monomer and a hexafunctional ethylene glycol-based oligomer in a weight ratio of 1:1), 2 wt% of AIBN (thermal curing agent) based on the weight of the acrylate compound, and 5 wt% of a phosphine oxide-based curing agent (photocuring agent) were used, and the same method as Example 9 was performed to finally manufacture a positive electrode 3 for a secondary battery.

[0188] Example 11

[0189] A positive electrode 4 for a secondary battery was manufactured using the same method as Example 7, except that binder composition 3 for electrode manufacturing was used.

[0190] Example 12

[0191] A positive electrode 5 for a secondary battery was manufactured using the same method as Example 7, except that binder composition 4 for electrode manufacturing was used.

[0192] Example 13

[0193] A positive electrode 6 for a secondary battery was manufactured using the same method as Example 10, except that binder composition 3 for electrode manufacturing was used.

[0194] Comparative Example 1

[0195] Comparative electrode 1 was obtained by performing the same method as Example 7 except that an electrode plate without a primer layer coating was used.

[0196] Comparative Example 2

[0197] Comparative electrode 2 was obtained by performing the same method as Example 7 except that polytetrafluoroethylene (PTFE) was used instead of binder composition 2 for electrode manufacturing. In this case, to make an electrode layer with a thickness of 90-100 microns or less, 15-20 ton / cm 2 A certain degree of high pressure was required.

[0198] Experimental Example 1

[0199] In Example 1, the 3-component copolymer ethylene glycol-maleic acid-acrylic acid synthesized in one or two steps was confirmed to be the same substance using an infrared spectroscopy (FTIR).

[0200] Ethylene glycol-maleic acid-acrylic acid synthesized in steps 1 and 2 were both white particles, and it was confirmed that all ethylene glycol-maleic acid-acrylic acid were synthesized as ternary copolymers by examining the presence or absence of the ketone group peak of acrylic acid using an infrared spectroscopy (FTIR).

[0201] The molecular weight of the three-component copolymer synthesized in step 1 was measured by chromatography and the number average molecular weight was 22,500 grams / mol, and the molecular weight of the three-component copolymer synthesized in step 2 was measured by chromatography and was 25,000 grams / mol.

[0202] As described above, the infrared spectra of the ternary copolymers synthesized in one and two steps were very similar to each other, confirming that both the one-step and two-step synthesis methods synthesize the same copolymer.

[0203] In addition, the three-component copolymer synthesized in Example 2, i.e., ethylene glycol-maleic acid-acrylonitrile copolymer, was observed with the naked eye and was found to be ivory-colored particles as shown in Fig. 2. The successful synthesis of this copolymer was confirmed by the presence or absence of an acrylonitrile peak using FTIR spectroscopy, indicating that the three-component copolymerization reaction was successful. The number average molecular weight measured by chromatography was 31,600 g / mol.

[0204] Experimental Example 2

[0205] To confirm whether the electrode material layer was well attached to the metal plate, an adhesion test using Scotch tape was performed on the positive and negative electrodes manufactured by a wet process, the positive electrodes 1 to 6 and the negative electrode for secondary batteries manufactured by a dry process, and the comparative positive electrodes 1 and 2. To this end, the degree of adhesion was judged by whether the electrode material layer was peeled off from the plate during the process of attaching 3M Scotch Tape to the surface of the electrode material layer and then removing it. In other words, if the electrode layer was peeled off from the plate when the tape was attached to the surface of the electrode layer and then removed, this was judged to have poor adhesion.

[0206] As a result of the adhesion test using Scotch tape, it was confirmed that the electrode material layer was well attached to the electrode plate for the positive and negative electrodes manufactured by the wet process, as well as the positive electrodes 1 to 6 and the negative electrode and comparative positive electrode 2 for secondary batteries manufactured by the dry process.

[0207] However, in the case of Comparative Example Positive Electrode 1, when the electrode composition sheet was formed using a plate without a primer layer, it was confirmed through a tape test that all of the electrode composition layers were peeled off. As such, since the primer layer was not formed, all of the electrode composition layers were peeled off from the plate, and further cell testing was deemed meaningless, so no cell test was performed on Comparative Example Positive Electrode 1.

[0208] In addition, in the case of positive electrodes 1 to 6 for secondary batteries manufactured by a dry process, positive electrodes 2, 3 and 6 manufactured with an electrode material layer composition including an acrylate compound and its curing agent had a much cleaner surface appearance of the electrode layer, and it was confirmed that the thickness of the electrode layer sheet could be made thinner when an acrylate compound and its curing agent were used.

[0209] In particular, the positive electrodes 2, 3, and 6 for secondary batteries had very excellent processability of the positive electrode material layer sheet. Since the acrylate compound is liquid at room temperature, it is presumed that processing such as kneading and rolling of the active material composition composed mostly of inorganic particles is much easier. Therefore, it can be seen that when the electrode material layer composition of the present invention includes an acrylate compound and its curing agent, it further improves the performance of the lithium ion battery while serving as a processing aid or mixed binder for a dry process.

[0210] In the process of manufacturing positive electrodes 4 and 5 in Examples 11 and 12, the appearance of the electrode layer was formed cleanly and well during the rolling operation, and the pressure for attaching the electrode layer onto the electrode plate was lower than that in the process of manufacturing comparative positive electrode 2 in Comparative Example 2, that is, when PTFE alone was used, and the electrode plate could be manufactured more easily than with PTFE alone. This shows that the ternary copolymer of the present invention can be mixed and used with PFTE, a binder of the prior art, without any major problems.

[0211] Experimental Example 3

[0212] Based on the results of Experimental Example 2, charge-discharge cycle tests were performed on the positive and negative electrode plates in which the electrode layers were well attached to the plates. During the charge-discharge cycle test, the formation process was performed by initially increasing the rate to 0.1-1.0C, and then a life test was performed at a rate of 0.2C or 1.0C. For all positive and negative electrodes manufactured by the wet or dry process, the discharge capacity after 3 or 4 cycles was set as the initial capacity, and the capacity retention rate was calculated by comparing these initial capacities with the discharge capacity after 50 cycles. The results of the cycle test are shown in Figs. 3 to 8.

[0213] First, as a result of the charge / discharge cycle test on the coin cell manufactured with the positive electrode manufactured by the wet process in Example 5, as shown in Fig. 3, there was almost no decrease in capacity, with the discharge capacity being 182 mAh / g after 4 cycles and 176 mAh / g after 50 cycles (capacity retention rate: ~97%).

[0214] In addition, for the coin cell manufactured with the negative electrode manufactured by the wet process in Example 6, a cycle test was conducted at a rate of 0.5C after the initial chemical reaction process. From Fig. 4 showing the results of the charge / discharge cycle test for the negative electrode cell, it can be seen that the discharge capacity after 3 cycles was 435 mAh / g, the discharge capacity after 50 cycles was 420 mAh / g, and the capacity retention rate was approximately 97%.

[0215] As a result of the charge / discharge cycle test for the coin cell manufactured with the positive electrode 1 manufactured by the dry process in Example 7, as shown in Fig. 5, it can be seen that the discharge capacity was 189 mAh / g after 4 cycles and 179 mAh / g after 50 cycles, indicating a capacity retention rate of approximately 95%.

[0216] Although not shown, the charge / discharge cycle test results for the coin cell manufactured with the negative electrode manufactured by the dry process in Example 8 showed that the discharge capacity after 4 cycles was 412 mAh / g, and after 50 cycles, the discharge capacity was measured to be 395 mAh / g, showing a capacity retention rate of approximately 95%.

[0217] As a result of the charge / discharge cycle test for the coin cell manufactured with the positive electrode 2 manufactured by the dry process in Example 9, as shown in FIG. 6, the discharge capacity after 4 cycles was 189 mAh / g, and after 50 cycles, the discharge capacity was 180 mAh / g, showing a capacity retention rate of about 95%. Although not shown, it was confirmed that the coin cell manufactured with the positive electrode 3 manufactured by the dry process in Example 10 showed a capacity retention rate of about 94%.

[0218] As a result of the charge / discharge cycle test for the coin cell manufactured with the comparative electrode 2 manufactured by the dry process in Comparative Example 2, as shown in Fig. 7, the discharge capacity after 4 cycles was 192 mAh / g, but after 50 cycles, the discharge capacity was 150 mAh / g, showing a rapid decrease in capacity. In this way, in the case of PTFE, a binder according to the prior art, the pressure required to form the electrode layer is considerably high, and in the charge / discharge cycle test, it was observed that the cell capacity continuously decreased as the charge / discharge cycle progressed.

[0219] As a result of the charge / discharge cycle test for the coin cell (type 2032) manufactured with the positive electrode 4 manufactured by the dry process in Example 11, the initial capacity was approximately 185 mAh / g or more, as shown in Fig. 8, and the capacity retention rate after 50 cycles was also 94%. The result of the charge / discharge cycle test for the coin cell (type 2032) manufactured with the positive electrode 5 manufactured by the dry process in Example 12 is not shown, but similar to Example 11, it was confirmed that the initial capacity was approximately 185 mAh / g or more, and the capacity retention rate after 50 cycles was maintained at approximately 95%.

[0220] Although not shown, the charge / discharge cycle test results for the coin cell manufactured with the positive electrode 6 manufactured by the dry process in Example 13 showed that the discharge capacity was 190 mAh / g after 4 cycles, and the capacity retention rate was 94% after 50 cycles. This shows that the acrylate compound is effective in manufacturing an active material composition sheet even in the case of a mixed binder.

[0221] From the experimental results described above, it was confirmed that the binder composition including the ternary copolymer based on glycol-maleic acid of the present invention can be used as a binder for electrode manufacturing in both dry and wet processes, as well as in a primer layer composition, and can be used in combination with other existing binders.

[0222] In addition, it can be seen that the binder composition for manufacturing an electrode including the 3-component copolymer of the present invention has good dry processability and can manufacture an electrode having a relatively thin thickness (thickness of less than 100 microns), and the electrochemical properties of the electrode manufactured therefrom are also excellent.

[0223] In particular, when an acrylate-based compound and a curing agent for the acrylate-based compound are used together in an electrode material layer composition for dry processing including a binder composition for electrode manufacturing, since the acrylate-based compound is liquid at room temperature, uniform mixing of the electrode material layer composition including a positive or negative electrode active material is possible, and the processability of the electrode sheet made of the electrode material layer composition, that is, the positive or negative electrode material layer sheet or the negative electrode material layer sheet, is also excellent, so that a relatively thin electrode material layer composition sheet having a thickness of less than 100 microns can be produced even at a relatively low pressure of less than 10 kgf / ㎠, and finally, it was confirmed that not only is the adhesion of the electrode material layer sheet to the metal electrode plate excellent during the curing step, but also the capacity retention rate can be maintained at a high level during a charge / discharge cycle test.

[0224] In this way, the electrode material layer composition including the binder composition for electrode manufacturing of the present invention can be used to form a positive electrode material layer and a negative electrode material layer, and can be used in various ways in general secondary batteries, including lithium ion batteries using active materials.

[0225] Although the present invention has been illustrated and described with reference to preferred embodiments as described above, it is not limited to the above-described 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 binder composition for manufacturing an electrode, comprising a ternary copolymer comprising a glycol compound, a maleic acid compound, and a third monomer.

2. In paragraph 1, A binder composition for electrode manufacturing, characterized in that the third monomer is a compound having a main chain containing a vinyl group (CH2=CH-) and to which another functional group is attached.

3. In paragraph 2, A binder composition for electrode manufacturing, characterized in that the compound is at least one selected from the group consisting of an acrylic compound, an acrylonitrile compound, an ethylene compound, an imidazole compound, an imidazolium compound, a propylene compound, and a vinylidene compound.

4. In paragraph 1, A binder composition for electrode manufacturing, characterized in that the third monomer is an acrylic compound having the following chemical formula 1. [Chemical Formula 1] CH2=CH-COO-R Here, R is any one of -H, an alkyl group, an alkenyl group, an alkynyl group, a phenyl group, and an amino group.

5. In paragraph 2, A binder composition for electrode manufacturing, characterized in that the above 3-component copolymer contains a glycol-based compound and a maleic acid-based compound in a molar ratio of 99:1 to 1:99, and the glycol-based compound and the maleic acid-based compound and a third monomer in a weight ratio of 99:1 to 1:

99.

6. In paragraph 1, The above glycol compound is a compound whose main chain is composed of ethylene glycol (HO-(CH2-CH2-O)nH) or ethylene oxide (-(CH2-CH2-O)n-)) (where n is a natural number > 0), A binder composition for electrode manufacturing, characterized in that the maleic acid compound is a compound including a 5-membered ring structure having two carboxyl groups.

7. In paragraph 6, The above glycol compound is at least one selected from the group consisting of ethylene glycol, ethylene oxide, propylene glycol, and propylene oxide, A binder composition for electrode manufacturing, characterized in that the maleic acid compound is at least one selected from the group consisting of maleic acid, salts thereof, and anhydrides thereof.

8. In paragraph 1, A binder composition for electrode manufacturing, characterized in that the third component copolymer is ethylene glycol-maleic acid-acrylonitrile or ethylene glycol-maleic acid-acrylic acid.

9. In paragraph 1, A binder composition for electrode manufacturing, characterized in that the above 3-component copolymer has a number average molecular weight of 10,000-1,000,000 g / mol.

10. In paragraph 1, A binder composition for electrode manufacturing, characterized in that it further includes one or more different types of binders, and includes the ternary copolymer: binder in a weight ratio of 90:10 to 10:

90.

11. In Article 10, A binder composition for electrode manufacturing, characterized in that the binder is at least one of carboxymethylcellulose (CMC), polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), and polyacrylic acid (PAA).

12. Active material for positive or negative electrode; A binder composition according to any one of claims 1 to 11; and A composition of an electrode material layer for a dry process, comprising a challenge agent.

13. In paragraph 12, An electrode material layer composition for a dry process, characterized in that it comprises 85-99.4 wt% of the positive or negative electrode active material, 0.5-10 wt% of the binder composition, and 0.1-5 wt% of the conductive material.

14. In paragraph 12, A dry process electrode material layer composition characterized in that the above-mentioned conductive material is at least one selected from the group consisting of conductive carbon black, graphene, single-walled carbon nanotubes, double-walled carbon nanotubes, multi-walled carbon nanotubes, branched carbon nanotubes, carbon nanoplates, and carbon nanoribbons.

15. In paragraph 12, A dry process electrode material layer composition characterized by further comprising an acrylate compound that is liquid at room temperature and capable of post-curing, and a curing agent for the acrylate compound.

16. In paragraph 15, A composition for an electrode material layer for a dry process, characterized in that the acrylate compound is a monomer or oligomer containing 2 to 16 functional groups and having a main chain of 2 to 1,000 carbon atoms.

17. In paragraph 16, A dry process electrode material layer composition, characterized in that the functional group is at least one selected from the group consisting of methylene, urethane, ester, ether, oxide, ethylene oxide, propylene oxide, ethylene glycol, propylene glycol, butadiene, imide, amine, amide, epoxy, olefin, sulfone or a combination thereof.

18. In paragraph 15, A dry process electrode material layer composition, characterized in that the acrylate compound is contained in an amount of 0.1 to 10 parts by weight per 100 parts by weight of the active material for the positive or negative electrode.

19. In paragraph 18, A dry process electrode material layer composition, characterized in that the curing agent is at least one of a thermal curing agent and a photocuring agent, and is contained in an amount of 0.1 to 20 parts by weight per 100 parts by weight of the acrylate compound.

20. In paragraph 19, A dry process electrode material layer composition, characterized in that the thermal curing agent comprises a peroxide or an azo compound, and the photocuring agent comprises a phenyl ketone-based compound or a phosphine oxide-based compound.

21. In paragraph 12, An electrode material layer composition for a dry process, characterized in that the positive or negative electrode active material comprises at least one selected from the group consisting of lithium, manganese, nickel, cobalt, aluminum, iron, phosphorus, tin, titanium, carbon materials, silicon, silicon oxide, sulfur, and combinations thereof.

22. A primer layer composition comprising 0.05 to 300 parts by weight of a nanocarbon material and a solvent per 100 parts by weight of the binder composition of any one of claims 1 to 11, and having a solid content of 0.2 to 40 wt%.

23. In paragraph 22, A frying layer composition characterized in that the above nano-carbon material is at least one selected from the group consisting of conductive carbon black, graphene, single-wall carbon nanotubes, double-wall carbon nanotubes, multi-wall carbon nanotubes, branched carbon nanotubes, carbon nanoplates, and carbon nanoribbons.

24. An electrode for a secondary battery comprising a positive electrode material layer or a negative electrode material layer composed of a dry process electrode material layer composition of Article 12.

25. Composition preparation step for preparing an electrode material layer composition for a dry process according to Article 15; A sheet forming step for forming a positive electrode material layer sheet or a negative electrode material layer sheet using the electrode material layer composition for the above dry process; An attachment step of attaching the positive electrode material layer sheet or negative electrode material layer sheet to the metal plate; A curing step for curing the attached positive electrode material layer sheet or negative electrode material layer sheet; and A method for manufacturing an electrode for a secondary battery, comprising: a step of rolling an electrode obtained by performing the above-mentioned hardening step.

26. In paragraph 25, A method for manufacturing an electrode for a secondary battery, characterized in that the above attachment step is performed including a step of forming a primer layer on the metal electrode plate; and a step of arranging the positive electrode material layer sheet or the negative electrode material layer sheet on the primer layer and then pressing it.

27. In paragraph 25, A method for manufacturing an electrode for a secondary battery, characterized in that the above-mentioned curing step is performed through at least one of thermal curing at 50°C to 180°C for 5 to 30 minutes and photocuring through light irradiation.

28. A lithium-ion battery comprising the secondary battery electrode of clause 24.

29. A lithium-ion battery comprising a secondary battery electrode manufactured by the manufacturing method of Article 25.

Images