Electrode

Abstract

The present disclosure may provide an electrode capable of preventing the occurrence of wrinkles and a swelling phenomenon, and having excellent capacity retention and energy density. In addition, the present disclosure provides a battery cell, a battery module, and a battery pack including the electrode, and may provide an electrical device including at least one of the battery cell, the battery module, and the battery pack.

Description

electrode

[0001] The present disclosure relates to electrodes. Specifically, the present disclosure relates to electrodes and applications of the electrodes.

[0002] Recently, demand for mobile devices such as smartphones, tablet PCs, and wireless earphones has been increasing. Furthermore, with the development of electric vehicles, energy storage batteries, robots, satellites, and other devices in full swing, research is actively underway on high-performance secondary batteries capable of repeated charging and discharging as an energy source.

[0003] Currently commercialized secondary batteries include nickel-cadmium batteries, nickel-hydrogen batteries, nickel-zinc batteries, and lithium secondary batteries. Among these, lithium secondary batteries have the advantage of having almost no memory effect compared to nickel-based secondary batteries, allowing free charging and discharging, a very low self-discharge rate, and high energy density.

[0004] Meanwhile, the electrode refers to the positive and negative electrodes of a battery cell. The electrode is generally manufactured by applying a slurry containing an electrode active material onto a current collector in the form of a metal plate and then drying it.

[0005] The above electrode active material stores or releases electron transport materials through charge and discharge of the battery. For example, in a lithium battery, the electrode active material stores or releases lithium (Li) ions through charge and discharge.

[0006] Repeated charging and discharging of the above cell causes the electron transport material to be repeatedly stored or released, causing the electrode active material to expand and contract repeatedly. If this process continues, wrinkles and swelling of the electrode can occur, leading to problems.

[0007] The present disclosure aims to provide an electrode that prevents wrinkles and swelling.

[0008] In addition, the present disclosure aims to provide an electrode having excellent capacity retention and energy density.

[0009] In addition, the present disclosure provides a battery cell, a battery module and a battery pack including the electrode, and an electric device including at least one of the battery cell, the battery module and the battery pack.

[0010] An electrode according to one example of the present disclosure includes a current collector and an active material layer positioned on at least one surface of the current collector, the active material layer including a first active material layer in contact with the current collector and including a first binder, and a second active material layer positioned on the first active material layer and including a second binder, wherein a glass transition temperature (Tg1) of the first binder is greater than a glass transition temperature (Tg2) of the second binder, and a ratio (H1 / H2) of a thickness (H1) of the first active material layer and a thickness (H2) of the second active material layer may be greater than 1.

[0011] In an electrode according to an example of the present disclosure, the glass transition temperature (Tg1) of the first binder may be 50°C to 300°C, and the glass transition temperature (Tg2) of the second binder may be -100°C to 10°C.

[0012] In an electrode according to an example of the present disclosure, the weight average molecular weight (M) of the first binder W ) is 10,000 g / mol to 200,000 g / mol, and the weight average molecular weight (M) of the second binder W ) can be from 5,000 g / mol to 500,000 g / mol.

[0013] In an electrode according to one example of the present disclosure, the first binder may include a polymer containing a polar functional group.

[0014] In an electrode according to one example of the present disclosure, the first binder may include an acrylic polymer.

[0015] In an electrode according to one example of the present disclosure, the second binder comprises a polymer comprising a first repeating unit and a second repeating unit, wherein the first repeating unit comprises a carbon-carbon multiple bond, and the second repeating unit may comprise an aromatic group.

[0016] In an electrode according to an example of the present disclosure, the ratio (N1 / N2) of the mole number (N1) of the first repeating unit to the mole number (N2) of the second repeating unit in the second binder may be 1 to 5.

[0017] In an electrode according to one example of the present disclosure, the second binder may additionally include a cellulose polymer.

[0018] In an electrode according to an example of the present disclosure, the weight ratio (P1 / P2) of the polymer (P1) including the first repeating unit and the second repeating unit and the cellulose polymer (P2) in the second binder may be 0.1 to 1.

[0019] In an electrode according to an example of the present disclosure, the first active material layer may include the first binder in an amount of 1 wt% to 5 wt% based on the total weight, and the second active material layer may include the second binder in an amount of 3 wt% to 6 wt% based on the total weight.

[0020] In an electrode according to an example of the present disclosure, the first active material layer and the second active material layer may each independently include a carbon-based active material and a silicon-based active material.

[0021] In an electrode according to an example of the present disclosure, the weight ratio (C1 / Si1) of the carbon-based active material (C1) and the silicon-based active material (Si1) in the first active material layer may be 1 to 10, and the weight ratio (C2 / Si2) of the carbon-based active material (C2) and the silicon-based active material (Si2) in the second active material layer may be 1 to 10.

[0022] In an electrode according to an example of the present disclosure, the first active material layer may have a ratio (DC1 / DSi1) of the average particle size (DC1) of the carbon-based active material to the average particle size (DSi1) of the silicon-based active material of 1 to 20, and the second active material layer may have a ratio (DC2 / DSi2) of the average particle size (DC2) of the carbon-based active material to the average particle size (DSi2) of the silicon-based active material of 1 to 20.

[0023] In an electrode according to an example of the present disclosure, the first active material layer may include a carbon-based active material in an amount of 1,000 to 10,000 parts by weight relative to 100 parts by weight of the first binder, and the second active material layer may include a carbon-based active material in an amount of 500 to 5,000 parts by weight relative to 100 parts by weight of the second binder.

[0024] In an electrode according to an example of the present disclosure, the difference between the glass transition temperature (Tg1) of the first binder and the glass transition temperature (Tg2) of the second binder may be 50°C or more.

[0025] A battery cell according to an example of the present disclosure includes a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, wherein the negative electrode may be an electrode according to an example of the present disclosure. In addition, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on at least one surface of the negative electrode current collector, the negative electrode active material layer includes a first negative electrode active material layer in contact with the negative electrode current collector and including a first binder, and a second negative electrode active material layer positioned on the first negative electrode active material layer and including a second binder, wherein a glass transition temperature (Tg1) of the first binder is greater than a glass transition temperature (Tg2) of the second binder, and a ratio (H1 / H2) of a thickness (H1) of the first negative electrode active material layer and a thickness (H2) of the second negative electrode active material layer may be greater than 1.

[0026] A battery cell assembly according to an example of the present disclosure includes one or more battery cells, wherein the battery cells may be battery cells according to an example of the present disclosure.

[0027] An electrical device according to an example of the present disclosure comprises at least one selected from the group consisting of one or more battery cells and one or more battery cell assemblies, wherein the battery cells are battery cells according to an example of the present disclosure, and the battery cell assemblies may be battery cell assemblies according to an example of the present disclosure.

[0028] The present disclosure can provide an electrode that prevents wrinkles and swelling.

[0029] In addition, the present disclosure can provide an electrode having excellent capacity retention and energy density.

[0030] In addition, the present disclosure provides a battery cell, a battery module, and a battery pack including the electrode, and can provide an electric device including at least one of the battery cell, the battery module, and the battery pack.

[0031] FIG. 1 is a simplified diagram illustrating an exemplary structure of a battery cell according to an example of the present disclosure.

[0032] FIG. 2 is a drawing briefly illustrating an exemplary structure of a battery module according to an example of the present disclosure.

[0033] FIG. 3 is a simplified diagram illustrating an exemplary structure of a battery pack according to an example of the present disclosure.

[0034] FIG. 4 is a diagram showing the results of evaluating the rapid life capacity retention rate for battery cells manufactured in Example 1 and Comparative Examples 1 to 5.

[0035] Figure 5 is a drawing showing the electrode surface of the battery cell manufactured in Example 1 and Comparative Example 1.

[0036] FIG. 6 is a drawing briefly illustrating an exemplary structure of an electrode according to an example of the present disclosure.

[0037] Among the properties mentioned in this disclosure, if the measurement temperature affects the properties, the properties are properties measured at room temperature and pressure, unless otherwise specified.

[0038] The term room temperature used in this disclosure refers to a natural temperature that is not heated or cooled, and may mean, for example, a temperature of 10°C to 30°C, for example, a temperature of about 15°C or higher, about 18°C ​​or higher, about 20°C or higher, about 23°C or higher, about 27°C or lower, or 25°C. Unless specifically defined in this disclosure, the unit of temperature is Celsius (°C).

[0039] Among the properties mentioned in this disclosure, if the measurement pressure affects the property, the property is a property measured at atmospheric pressure unless otherwise specified.

[0040] The term atmospheric pressure used in this disclosure refers to natural pressure that is neither pressurized nor depressurized, and typically refers to atmospheric pressure of about 700 mmHg to 800 mmHg.

[0041] The terms a to b used in this disclosure mean between a and b, including a and b. For example, including a to b by weight means the same as including a to b by weight.

[0042] The term substitution used in the present disclosure means that a hydrogen atom bonded to a carbon atom of a compound is replaced with another substituent, and the position of substitution is not particularly limited as long as it is a position where a hydrogen atom is substituted, i.e., a position where a substituent can be substituted, and when two or more are substituted, the substituents may be the same or different from each other.

[0043] The term "substituent" used in this disclosure refers to an atom or group of atoms that replaces one or more hydrogen atoms on the parent hydrocarbon chain. Furthermore, the substituent is described below, but is not limited thereto, and unless otherwise specified in this disclosure, the substituent may be further substituted with the substituents described below or may not be substituted with any substituents.

[0044] The term alkyl group or alkylene group used in the present disclosure may be a straight-chain or branched alkyl group or alkylene group having 1 to 20 carbon atoms, or 1 to 16 carbon atoms, or 1 to 12 carbon atoms, or 1 to 8 carbon atoms, or 1 to 6 carbon atoms, unless otherwise specified, or a cyclic alkyl group or alkylene group having 3 to 20 carbon atoms, or 3 to 16 carbon atoms, or 3 to 12 carbon atoms, or 3 to 8 carbon atoms, or 3 to 6 carbon atoms. Here, the cyclic alkyl group or alkylene group includes an alkyl group or alkylene group that has only a ring structure and an alkyl group or alkylene group that includes a ring structure within the structure. For example, a cyclohexyl group and a methyl cyclohexyl group both correspond to cyclic alkyl groups. Also, for example, the alkyl group or alkylene group is specifically methyl(ene), ethyl(ene), n-propyl(ene), isopropyl(ene), n-butyl(ene), isobutyl(ene), tert-butyl(ene), sec-butyl(ene), 1-methyl-butyl(ene), 1-ethyl-butyl(ene), n-pentyl(ene), isopentyl(ene), neopentyl(ene), tert-pentyl(ene), n-hexyl(ene), 1-methylpentyl(ene), 2-methylpentyl(ene), 4-methyl-2-pentyl(ene), 3,3-dimethylbutyl(ene), 2-ethylbutyl(ene), n-heptyl(ene), 1-methylhexyl(ene), n-octyl(ene), tert-octyl(ene), 1-methylheptyl(ene), 2-ethylhexyl(ene), 2-propylpentyl(ene), Examples include, but are not limited to, n-nonyl(ene), 2,2-dimethylheptyl(ene), 1-ethylpropyl(ene), 1,1-dimethylpropyl(ene), isohexyl(ene), 2-methylpentyl(ene), 4-methylhexyl(ene), and 5-methylhexyl(ene).In addition, examples of the cycloalkyl group or cycloalkylene group include, but are not limited to, cyclopropyl(ene), cyclobutyl(ene), cyclopentyl(ene), 3-methylcyclopentyl(ene), 2,3-dimethylcyclopentyl(ene), cyclohexyl(ene), 3-methylcyclohexyl(ene), 4-methylcyclohexyl(ene), 2,3-dimethylcyclohexyl(ene), 3,4,5-trimethylcyclohexyl(ene), 4-tert-butylcyclohexyl(ene), cycloheptyl(ene), cyclooctyl(ene), etc.

[0045] The term alkenyl group or alkenylene group used in the present disclosure may be a straight or branched acyclic alkenyl group or alkenylene group having 2 to 20 carbon atoms, or 2 to 16 carbon atoms, or 2 to 12 carbon atoms, or 2 to 8 carbon atoms, or 2 to 6 carbon atoms, unless otherwise specified; or a cyclic alkenyl group or alkenylene group having 3 to 20 carbon atoms, or 3 to 16 carbon atoms, or 3 to 12 carbon atoms, or 3 to 8 carbon atoms, or 3 to 6 carbon atoms. Here, if an alkenyl group or alkenylene group having a ring structure is included, it corresponds to a cyclic alkenyl group or alkenylene group. Also, for example, ethenyl(ene), n-propenyl(ene), isopropenyl(ene), n-butenyl(ene), isobutenyl(ene), tert-butenyl(ene), sec-butenyl(ene), 1-methyl-butenyl(ene), 1-ethyl-butenyl(ene), n-pentenyl(ene), isopentenyl(ene), neopentenyl(ene), tert-pentenyl(ene), n-hexenyl(ene), 1-methylpentenyl(ene), 2-methylpentenyl(ene), 4-methyl-2-pentenyl(ene), 3,3-dimethylbutenyl(ene), 2-ethylbutenyl(ene), n-heptenyl(ene), 1-methylhexenyl(ene), n-octenyl(ene), tert-octenyl(ene), 1-methylheptenyl(ene), 2-ethylhexenyl(ene), Examples thereof include, but are not limited to, 2-propylpentenyl(ene), n-nonylenyl(ene), 2,2-dimethylheptenyl(ene), 1-ethylpropenyl(ene), 1,1-dimethylpropenyl(ene), isohexenyl(ene), 2-methylpentenyl(ene), 4-methylhexenyl(ene), 5-methylhexenyl(ene), etc.In addition, the cycloalkenyl group or cycloalkenylene group may be specifically exemplified by, but is not limited to, cyclopropenyl(ene), cyclobutenyl(ene), cyclopentenyl(ene), 3-methylcyclopentenyl(ene), 2,3-dimethylcyclopentenyl(ene), cyclohexenyl(ene), 3-methylcyclohexenyl(ene), 4-methylcyclohexenyl(ene), 2,3-dimethylcyclohexenyl(ene), 3,4,5-trimethylcyclohexenyl(ene), 4-tert-butylcyclohexenyl(ene), cycloheptenyl(ene), cyclooctenyl(ene), etc.

[0046] The term alkynyl group or alkynylene group used in the present disclosure may be, unless otherwise specified, a straight-chain or branched acyclic alkynyl group or alkynylene group having 2 to 20 carbon atoms, or 2 to 16 carbon atoms, or 2 to 12 carbon atoms, or 2 to 8 carbon atoms, or 2 to 6 carbon atoms, or a cyclic alkynyl group or alkynylene group having 3 to 20 carbon atoms, or 3 to 16 carbon atoms, or 3 to 12 carbon atoms, or 3 to 8 carbon atoms, or 3 to 6 carbon atoms. Here, if an alkynyl group or alkynylene group having a ring structure is included, it corresponds to a cyclic alkynyl group or alkynylene group. Also, for example, ethynyl(ene), n-propynyl(ene), isopropynyl(ene), n-butynyl(ene), isobutynyl(ene), tert-butynyl(ene), sec-butynyl(ene), 1-methyl-butynyl(ene), 1-ethyl-butynyl(ene), n-pentynyl(ene), isopentynyl(ene), neopentynyl(ene), tert-pentynyl(ene), n-hexynyl(ene), 1-methylpentynyl(ene), 2-methylpentynyl(ene), 4-methyl-2-pentynyl(ene), 3,3-dimethylbutynyl(ene), 2-ethylbutynyl(ene), n-heptynyl(ene), 1-methylhexynyl(ene), n-octynyl(ene), tert-octynyl(ene), 1-methylheptynyl(ene), 2-ethylheptynyl(ene), Examples thereof include, but are not limited to, 2-propylpentynyl(ren), n-nonynyl(ren), 2,2-dimethylheptynyl(ren), 1-ethylpropynyl(ren), 1,1-dimethylpropynyl(ren), isohexynyl(ren), 2-methylpentynyl(ren), 4-methylhexynyl(ren), 5-methylhexynyl(ren). In addition, the cycloalkynyl group or cycloalkynylene group may be specifically exemplified by cyclopropynyl(ren), cyclobutynyl(ren), cyclopentynyl(ren), 3-methylcyclopentynyl(ren), 2,3-dimethylcyclopentynyl(ren), cyclohexynyl(ren), 3-methylcyclohexynyl(ren), 4-methylcyclohexynyl(ren), 2,3-dimethylcyclohexynyl(ren), 3,4,5-trimethylcyclohexynyl(ren), 4-tert-butylcyclohexynyl(ren), cycloheptynyl(ren), cyclooctynyl(ren), etc.It is not limited to this.

[0047] The above alkyl group, alkylene group, alkenyl group, alkenylene group, alkynyl group and alkynylene group may each be independently optionally substituted by one or more substituents, or may be unsubstituted and be hydrogen (H). The substituent may be at least one selected from the group consisting of a halogen element, an aryl group, a heteroaryl group, an epoxy group, an alkoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, a carbonyl group and a hydroxy group, but is not limited thereto.

[0048] In addition, in the present disclosure, the number of carbon atoms in an alkyl group, an alkylene group, an alkenyl group, an alkenylene group, an alkynyl group, and an alkynylene group means the number of carbon atoms in a structure corresponding to the main chain, excluding the number of carbon atoms included in a substituent, unless otherwise stated.

[0049] The term aromatic group used in this disclosure may encompass both aryl groups and heteroaryl groups.

[0050] The term aryl group used in the present disclosure refers to an aromatic ring in which one hydrogen is removed from an aromatic hydrocarbon ring, and the aromatic hydrocarbon ring may include a monocyclic or polycyclic ring. The number of carbon atoms in the aryl group is not particularly limited, but unless otherwise stated, it may be an aryl group having 6 to 30 carbon atoms, or 6 to 26 carbon atoms, or 6 to 22 carbon atoms, or 6 to 20 carbon atoms, or 6 to 18 carbon atoms, or 6 to 15 carbon atoms. In addition, the term arylene group used in the present disclosure refers to a divalent group having two bonding positions to an aryl group. The description of the aryl group described above may be applied to these groups, except that each of them is a divalent group. Examples of the aryl group may include, but are not limited to, a phenyl group, a phenylethyl group, a phenylpropyl group, a benzyl group, a tolyl group, a xylyl group, or a naphthyl group.

[0051] The term heteroaryl group used in the present disclosure refers to an aromatic ring containing at least one heteroatom other than carbon, and specifically, the heteroatom may include at least one atom selected from the group consisting of nitrogen (N), oxygen (O), sulfur (S), selenium (Se), and tellurium (Te). In this case, an atom constituting the ring structure of the heteroaryl group may be referred to as a reducing group. In addition, the heteroaryl group may include a monocyclic or polycyclic ring. The number of carbon atoms in the heteroaryl group is not particularly limited, but unless otherwise stated, it may be a heteroaryl group having 2 to 30 carbon atoms, or 2 to 26 carbon atoms, or 2 to 22 carbon atoms, or 2 to 20 carbon atoms, or 2 to 18 carbon atoms, or 2 to 15 carbon atoms. In other examples, the heteroaryl group may be a heteroaryl group having a number of reducing atoms of 5 to 30, 5 to 25, 5 to 20, 5 to 15, 5 to 10, or 5 to 8, although the number of reducing atoms is not particularly limited. The above heteroaryl group is, for example, a thiophene group, a furan group, a pyrrole group, an imidazolyl group, a thiazolyl group, an oxazolyl group, an oxadiazolyl group, a triazolyl group, a pyridyl group, a bipyridyl group, a pyrimidyl group, a triazinyl group, an acridyl group, a pyridazinyl group, a pyrazinyl group, a quinolinyl group, a quinazolinyl group, a phthalazinyl group, a pyridopyrimidinyl group, a pyridopyrazinyl group, a pyrazinopyrazinyl group, an isoquinolinyl group, an indole group, a carbazolyl group, a benzoxazolyl group, a benzimidazolyl group, a benzothiazolyl group, a benzocarbazolyl group, a dibenzocarbazolyl group, a benzothiophene group, a dibenzothiophene group, a benzofuran group, Examples thereof include, but are not limited to, a dibenzofuran group, a benzosilole group, a dibenzosilole group, a phenanthrolinyl group, an isoxazolyl group, a thiadiazolyl group, a phenothiazinyl group, a phenoxazine group, and condensed structures thereof.

[0052] Additionally, the term heteroarylene group used in the present disclosure refers to a divalent group having two bonding positions to a heteroaryl group. The description of the heteroaryl group described above can be applied to each of these groups, except that they are each divalent.

[0053] The above aryl group and heteroaryl group may each be independently optionally substituted by one or more substituents, or may be unsubstituted and be hydrogen (H). The substituent may be at least one selected from the group consisting of a halogen element, an aryl group, a heteroaryl group, an epoxy group, an alkoxy group, a cyano group, a carboxyl group, an acryloyl group, a methacryloyl group, an acryloyloxy group, a methacryloyloxy group, a carbonyl group, and a hydroxy group, but is not limited thereto.

[0054] In addition, in the present disclosure, the number of carbon atoms in an aryl group and a heteroaryl group means the number of carbon atoms in a structure corresponding to a main chain, excluding the number of carbon atoms contained in a substituent, unless otherwise stated. In addition, the number of reducing atoms in the heteroaryl group means the number of reducing atoms in a structure corresponding to a main chain, excluding the number of reducing atoms contained in a substituent, unless otherwise stated.

[0055] The present disclosure can provide an electrode (10) that prevents wrinkles and swelling and has excellent capacity retention and energy density. In addition, the present disclosure can provide a battery cell (1), a battery module (2), and a battery pack (3) including the electrode (10), and can provide an electric device including at least one of the battery cell (1), the battery module (2), and the battery pack (3). Examples of the battery cell (1), the battery module (2), and the battery pack (3) may be referenced to FIGS. 1 to 3, respectively.

[0056] An electrode (10) according to an example of the present disclosure may include a current collector (100) and an active material layer (200). The active material layer (200) may be positioned on at least one surface of the current collector (100).

[0057] In an electrode (10) according to an example of the present disclosure, a current collector (100) may be used as a material that is electrically conductive and electrochemically durable. Typically, the current collector (100) may be made of, for example, iron, copper, aluminum, nickel, stainless steel, titanium, tantalum, gold, or platinum, and these materials may be used singly or in combination of two or more.

[0058] In addition, the material of the current collector (100) may be determined depending on whether the electrode (10) is a positive electrode or a negative electrode. If the electrode (10) is a positive electrode, the current collector (100) may be a positive current collector (100), and if the electrode (10) is a negative electrode, the current collector (100) may be a negative current collector (100). In addition, the type, size, shape, etc. of the positive current collector (100) are not particularly limited as long as it is conductive and does not cause a chemical change in the battery cell (1). For example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used as the positive current collector (100). The type, size, shape, etc. of the negative current collector (100) are not particularly limited as long as it is conductive and does not cause a chemical change in the battery cell (1). As the negative electrode current collector (100), for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used.

[0059] In addition, the current collector (100) may have an appropriate thickness as needed. Although not particularly limited, the current collector (100) may have a thickness of 1 ㎛ to 500 ㎛, a thickness of 1 ㎛ to 300 ㎛, a thickness of 1 ㎛ to 100 ㎛, or a thickness of 1 ㎛ to 50 ㎛.

[0060] The terms thickness (or height), width and length used in this disclosure mean average values ​​unless specifically stated otherwise, and measurements can be made according to a method known in the art using a measuring device capable of measuring thickness (or height), width and length, respectively.

[0061] In addition, the current collector (100) can form fine irregularities on the surface to further strengthen the adhesive strength with the active material layer (200). For example, the shape of the current collector may be one or more selected from the group consisting of a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven fabric.

[0062] In an electrode (10) according to an example of the present disclosure, the active material layer (200) may be formed by a slurry composition. Specifically, the active material layer (200) may refer to a dried form of the slurry composition, and may refer to a form in which rolling is performed after drying, if necessary.

[0063] The term "dry" used in this disclosure means a state in which substantially no solvent is contained, and for example, a state in which the amount of solvent contained in each layer is about 1 wt% or less, 0.5 wt% or less, 0.1 wt% or less, or 0.05 wt% or less. The drying conditions applied for this purpose are not particularly limited and can be adjusted so that the above-mentioned amount of solvent can be achieved.

[0064] In addition, the active material layer (200) can be formed by applying the slurry composition on at least one surface of the current collector (100) and drying it. As described above, rolling can be performed after drying as needed. The rolling can be performed using a rolling jig or the like according to a known method. In addition, the method of performing the coating is not particularly limited and a known method can be used. Specifically, the method of performing the coating can be a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, or a brushing method. The coating thickness of the slurry composition can be applied to an appropriate thickness in consideration of the thickness after drying, and the known method described above can be appropriately selected and performed depending on the coating thickness.

[0065] The slurry composition forming the active material layer (200) may contain various components. In addition, the slurry composition may be in a state in which the various components are appropriately dispersed. The slurry composition may be prepared by adding the various components in an appropriate manner and order and then mixing them through an appropriate mixing method. The mixing method is not particularly limited and any known method may be used. Specifically, the mixing method may use a mixer such as a ball mill, a sand mill, a bead mill, a pigment disperser, an ultrasonic disperser, a homogenizer, a rotating-orbital mixer, or a fill mixer. Specific details regarding the slurry composition forming the active material layer (200) will be described later.

[0066] The above active material layer (200) may be in direct contact with the current collector (100), or may be positioned on the current collector (100) even if not in direct contact. For example, a separate layer may be provided between the current collector (100) and the active material layer (200).

[0067] In an electrode (10) according to an example of the present disclosure, the active material layer (200) may have a single-layer structure. In another example, in the electrode (10), the active material layer (200) may have a multi-layer structure. In order to prevent the occurrence of wrinkles and swelling of the electrode (10) and to secure excellent capacity retention and energy density, it may be more advantageous for the active material layer (200) to have a multi-layer structure.

[0068] In an electrode (10) according to an example of the present disclosure, the active material layer (200) may include a first active material layer (210) and a second active material layer (220).

[0069] FIG. 6 is a schematic diagram illustrating an exemplary structure of an electrode according to an example of the present disclosure. Referring to FIG. 6, the electrode (10) includes a current collector (100) and an active material layer (200) including a first active material layer (210) and a second active material layer (220). In addition, the first active material layer (210) is in contact with the current collector (100), and the second active material layer (220) is positioned on the first active material layer (210). FIG. 6 illustrates that the first active material layer (210) and the second active material layer (220) are in contact with each other. However, this is merely an example, and an additional active material layer may be inserted between them.

[0070] Meanwhile, in an electrode (10) according to an example of the present disclosure, the first active material layer (210) may be formed by a first slurry composition, and the second active material layer (220) may be formed by a second slurry composition. In addition, each component of the first slurry composition and the second slurry composition may be independently configured, and their drying or rolling methods may also be independently performed.

[0071] In an electrode (10) according to an example of the present disclosure, the adhesive force between the current collector (100) and the first active material layer (210) and the adhesive force between the first active material layer (210) and the second active material layer (220) may each have an appropriate value so as to prevent separation of the layers from occurring. In addition, even when another active material layer is included between the first active material layer (210) and the second active material layer (220), the respective active material layers may have an appropriate adhesive force.

[0072] In the above electrode (10), the adhesive force between the current collector (100) and the first active material layer (210) may be 0.2 N or more, 0.21 N or more, 0.22 N or more, 0.23 N or more, 0.24 N or more, 0.25 N or more, 0.26 N or more, 0.27 N or more, 0.28 N or more, or 0.29 N or more. The upper limit of the adhesive force between the current collector (100) and the first active material layer (210) is not particularly limited, but may be 1 N or less or 0.5 N or less.

[0073] In addition, in the electrode (10), the adhesive force between the first active material layer (210) and the second active material layer (220) may be 0.25 N or more, 0.26 N or more, 0.27 N or more, 0.28 N or more, 0.29 N or more, 0.3 N or more, 0.31 N or more, 0.32 N or more, 0.33 N or more, or 0.34 N or more. The upper limit of the adhesive force between the first active material layer (210) and the second active material layer (220) is not limited, but may be 2 N or less, 1 N or less, or 0.5 N or less. In addition, the adhesive force between the first active material layer (210) and the second active material layer (220) may be greater than the adhesive force between the current collector (100) and the first active material layer (210).

[0074] The adhesive strength between the current collector (100) and the first active material layer (210) was measured as follows. The first slurry composition forming the first active material layer (210) was applied onto the current collector (100), dried at 80°C, and then rolled at 25°C to manufacture an electrode (10). Thereafter, the electrode (10) was cut into pieces 2.5 cm wide and 15 cm long to manufacture a measurement sample. Thereafter, the first active material layer (210) of the measurement sample was attached so as to be in contact with a release film made of PET (polyethylene terephthalate). Thereafter, the peeling force measured when the current collector (100) and the first active material layer (210) were completely peeled off with the release film at a peeling speed of about 0.5 mm / min and a peeling angle of about 90 degrees was evaluated as the adhesive strength. At this time, the measurement of the adhesive strength was performed at 25°C.

[0075] In addition, the adhesive strength between the first active material layer (210) and the second active material layer (220) was measured as follows. The first slurry composition forming the first active material layer (210) was applied onto the current collector (100), and the second slurry composition forming the second active material layer (220) was additionally applied onto the first slurry composition, and then dried at 80° C. and rolled at 25° C. to manufacture an electrode (10). Thereafter, the electrode (10) was cut into pieces 2.5 cm wide and 15 cm long to manufacture a measurement sample. Thereafter, the second active material layer (220) of the measurement sample was attached so as to be in contact with a release film made of PET (polyethylene terephthalate). Thereafter, the peeling force measured when the first active material layer (210) and the second active material layer (220) were completely peeled off at a peeling speed of about 0.5 mm / min and a peeling angle of about 90 degrees using the above-mentioned release film was evaluated as the adhesive force. At this time, the measurement of the adhesive force was performed at 25°C.

[0076] If each of the above adhesive strengths is within the aforementioned range, it can be considered that the adhesive strength has an appropriate value so that separation of the layers does not occur.

[0077] In an electrode (10) according to an example of the present disclosure, the first active material layer (210) may include a first binder. In addition, in the electrode (10), the second active material layer (220) may include a second binder. Each of the first binder and the second binder may perform roles such as pasting of the active material, mutual adhesion between active materials, adhesion between adjacent layers, and cushioning against expansion and contraction of the active material, which will be described later.

[0078] In an electrode (10) according to an example of the present disclosure, the first active material layer (210) may include the first binder in an amount of 1 wt% or more, 1.2 wt% or more, 1.4 wt% or more, 1.6 wt% or more, 1.8 wt% or more, 2 wt% or more, 2.2 wt% or more, 2.4 wt% or more, or 2.6 wt% or more, or 5 wt% or less, 4.8 wt% or less, 4.6 wt% or less, 4.4 wt% or less, 4.2 wt% or less, 4 wt% or less, 3.8 wt% or less, 3.6 wt% or less, 3.4 wt% or less, 3.2 wt% or less, 3 wt% or less, or 2.8 wt% or less, based on the total weight of the first active material layer (210). In addition, the first active material layer (210) can include the first binder within a range formed by appropriately selecting the upper and lower limits described above.

[0079] In an electrode (10) according to an example of the present disclosure, the second active material layer (220) may include the second binder in an amount of 3 wt% or more, 3.2 wt% or more, 3.4 wt% or more, 3.6 wt% or more, 3.8 wt% or more, 4 wt% or more, 4.2 wt% or more, or 4.4 wt% or more, or 6 wt% or less, 5.8 wt% or less, 5.6 wt% or less, 5.4 wt% or less, 5.2 wt% or less, 5 wt% or less, 4.8 wt% or less, or 4.6 wt% or less, of the total weight of the second active material layer (220). In addition, the second active material layer (220) may include the second binder within a range formed by appropriately selecting the above-mentioned upper and lower limits.

[0080] In an electrode (10) according to an example of the present disclosure, the content ratio of the first binder included in the first active material layer (210) may be equal to or less than the content ratio of the second binder included in the second active material layer (220). In the electrode (10), the content percentage (P) of the first binder included in the first active material layer (210) 11 ) and the content percentage (P) of the second binder included in the second active material layer (220) 22 ) ratio (P 11 / P 22 ) may be 0.01 or more, 0.05 or more, 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, 0.5 or more, or 0.55 or more, or 1 or less, less than 1, 0.95 or less, 0.9 or less, 0.85 or less, 0.8 or less, 0.75 or less, 0.7 or less, 0.65 or less, or 0.6 or less. In addition, the ratio (P 11 / P 22 ) can be formed within a range formed by appropriately selecting the upper and lower limits described above. By controlling as described above, the adhesive strength between the current collector (100) and the first active material layer (210) can be improved.

[0081] In an electrode (10) according to an example of the present disclosure, the glass transition temperature (Tg1) of the first binder may be higher than the glass transition temperature (Tg2) of the second binder. That is, the first active material layer (210) in contact with the current collector (100) includes a binder having a higher glass transition temperature than the second active material layer (220) which is an outer layer, thereby preventing the occurrence of wrinkles and swelling of the electrode (10) and ensuring excellent capacity retention and energy density.

[0082] The term "glass transition temperature" used in this disclosure may refer to a value measured using a differential scanning calorimeter (DSC) according to ISO 1135762. Specifically, the method for measuring the glass transition temperature may refer to the <Method for Measuring Physical Properties> below.

[0083] In an electrode (10) according to an example of the present disclosure, the difference between the glass transition temperature (Tg1) of the first binder and the glass transition temperature (Tg2) of the second binder may be 50°C or more, 55°C or more, 60°C or more, 65°C or more, 70°C or more, 75°C or more, 80°C or more, 85°C or more, 90°C or more, 95°C or more, 100°C or more, 105°C or more, or 110°C or more. In another example, the difference between the glass transition temperature (Tg1) of the first binder and the glass transition temperature (Tg2) of the second binder may be 300°C or less, 290°C or less, 280°C or less, 270°C or less, 260°C or less, 250°C or less, 240°C or less, 230°C or less, 220°C or less, 210°C or less, 200°C or less, 190°C or less, 180°C or less, 170°C or less, 160°C or less, or 150°C or less. In addition, in another example, the difference between the glass transition temperature (Tg1) of the first binder and the glass transition temperature (Tg2) of the second binder may be within a range formed by appropriately selecting the above-mentioned upper and lower limits. If the difference in glass transition temperature between the first binder and the second binder is as described above, wrinkles and swelling of the electrode (10) can be prevented, and excellent capacity retention and energy density can be secured.

[0084] In an electrode (10) according to an example of the present disclosure, a first active material layer (210) including a binder having a relatively high glass transition temperature is in contact with a current collector (100), and a second active material layer (220) including a binder having a relatively low glass transition temperature is positioned in an outer layer, thereby preventing the occurrence of wrinkles and swelling of the electrode (10) and ensuring excellent capacity retention and energy density.

[0085] In an electrode (10) according to an example of the present disclosure, the glass transition temperature (Tg1) of the first binder is 50°C or more, 55°C or more, 60°C or more, 65°C or more, 70°C or more, 75°C or more, 80°C or more, 85°C or more, 90°C or more, 95°C or more, 100°C or more, 105°C or more, or 110°C or more, or 300°C or less, 290°C or less, 280°C or less, 270°C or less, 260°C or less, 250°C or less, 240°C or less, 230°C or less, 220°C or less, 210°C or less, 200°C or less, 190°C or less, 180°C or less, 170°C or less, 160°C Below, it may be 150 ℃ or less, 140 ℃ or less, or 130 ℃ or less. In addition, the glass transition temperature (Tg1) of the first binder may be within a range formed by appropriately selecting the upper and lower limits described above. When the glass transition temperature of the first binder satisfies the range, the occurrence of wrinkles and swelling of the electrode (10) can be prevented, and excellent capacity retention rate and energy density can be secured.

[0086] In an electrode (10) according to an example of the present disclosure, the glass transition temperature (Tg2) of the second binder may be -100°C or higher, -90°C or higher, -80°C or higher, -70°C or higher, -60°C or higher, -50°C or higher, -40°C or higher, -30°C or higher, -20°C or higher, -10°C or higher, or -5°C or higher, or 10°C or lower, 5°C or lower, or 0°C or lower. In addition, the glass transition temperature (Tg2) of the second binder may be within a range formed by appropriately selecting the above-described upper and lower limits. When the glass transition temperature of the second binder satisfies the range, wrinkle occurrence and swelling of the electrode (10) can be prevented, and excellent capacity retention rate and energy density can be secured.

[0087] In addition, if the first binder and the second binder each have a glass transition temperature within the aforementioned range, the combination of these can prevent the occurrence of wrinkles and swelling of the electrode (10) and secure excellent capacity retention and energy density.

[0088] In an electrode (10) according to an example of the present disclosure, the weight average molecular weight (Mw) of the first binder is 10,000 g / mol or more, 15,000 g / mol or more, 20,000 g / mol or more, 25,000 g / mol or more, 30,000 g / mol or more, 35,000 g / mol or more, 40,000 g / mol or more, 45,000 g / mol or more, 50,000 g / mol or more, 55,000 g / mol or more, 60,000 g / mol or more, 65,000 g / mol or more, or 70,000 g / mol or more, or 200,000 g / mol or less, 190,000 g / mol or less, 180,000 g / mol or less, 170,000 g / mol or less, It may be 160,000 g / mol or less, 150,000 g / mol or less, 140,000 g / mol or less, 130,000 g / mol or less, 120,000 g / mol or less, 110,000 g / mol or less, 100,000 g / mol or less, 90,000 g / mol or less, or 80,000 g / mol or less. The weight average molecular weight (Mw) of the first binder may be within a range formed by appropriately selecting the above-mentioned upper and lower limits.

[0089] Additionally, in the electrode (10), the polydispersity index (PDI) of the first binder may be 1 to 2 or 1 to 1.5.

[0090] In the above electrode (10), when the weight average molecular weight of the first binder satisfies the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured. In addition, when the weight average molecular weight and polydispersity index of the first binder satisfies the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured.

[0091] In an electrode (10) according to an example of the present disclosure, the weight average molecular weight (Mw) of the second binder is 5,000 g / mol or more, 6,000 g / mol or more, 7,000 g / mol or more, 8,000 g / mol or more, 9,000 g / mol or more, 10,000 g / mol or more, 15,000 g / mol or more, 20,000 g / mol or more, 25,000 g / mol or more, 30,000 g / mol or more, 35,000 g / mol or more, or 40,000 g / mol or more, or 500,000 g / mol or less, 450,000 g / mol or less, 400,000 g / mol or less, 350,000 g / mol or less, 300,000 g / mol or less, 250,000 g / mol or less or 200,000 g / mol or less. The weight average molecular weight (Mw) of the second binder may be within a range formed by appropriately selecting the upper and lower limits described above.

[0092] Additionally, in the electrode (10), the polydispersity index (PDI) of the second binder may be 1 to 50, 1 to 40, 1 to 30, or 1 to 25.

[0093] In the above electrode (10), when the weight average molecular weight of the second binder satisfies the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured. In addition, when the second binder satisfies the weight average molecular weight and polydispersity index within the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured.

[0094] In addition, if the first binder and the second binder each have a weight average molecular weight within the aforementioned range, the combination thereof can prevent wrinkles and swelling phenomena and secure excellent capacity retention and energy density. In addition, if the first binder and the second binder each have a weight average molecular weight and a polydispersity index within the aforementioned range, the combination thereof can prevent wrinkles and swelling phenomena of the electrode (10) and secure excellent capacity retention and energy density.

[0095] In the present disclosure, the weight average molecular weight (Mw) can be measured using gel permeation chromatography (GPC). In addition, the number average molecular weight (Mn) can also be measured using the GPC, and the polydispersity index (PDI) can be derived by dividing the measured weight average molecular weight (MW) by the number average molecular weight (Mn) (MW / Mn). Specifically, the method for measuring the weight average molecular weight and polydispersity index can be referred to in the <Method for Measuring Physical Properties> below.

[0096] In an electrode (10) according to an example of the present disclosure, the type of the first binder is not particularly limited as long as it satisfies the above-described glass transition temperature range. For example, the first binder may more advantageously achieve the purpose of the present disclosure if it includes a polymer containing a polar functional group.

[0097] The above polar functional group may refer to a functional group in which a dipole momentum is formed due to the localization of electrons. The above polar functional group may be, for example, one or more selected from the group consisting of an amide group, a carboxyl group, an ester group, a hydroxy group, and an amine group, but is not particularly limited thereto.

[0098] The polymer containing the polar functional group can be formed through a polymerization reaction using one or more monomers containing the polar functional group. In addition, the polymer containing the polar functional group can contain the polar functional group in at least one polymerization unit of the polymer. In addition, the polymer can also be formed through a copolymerization reaction of one or more monomers containing the polar functional group and one or more monomers not containing the polar functional group.

[0099] The polymerization unit used in the present disclosure refers to a basic repeat unit that constitutes a polymer, and refers to a repeat unit that forms the structure of a polymer through a polymerization reaction of a polymerizable monomer. The polymerization in the present disclosure can be performed according to a known method, and for example, can be performed by a method such as bulk polymerization, solution polymerization, suspension polymerization, interfacial polymerization, or emulsion polymerization, taking into account the chemical characteristics of the monomers forming the polymer.

[0100] Additionally, in the present disclosure, the polymer may be a copolymer. When the polymer is a copolymer, the copolymer may be a block copolymer, a gradient copolymer, or a random copolymer, and is not particularly limited.

[0101] In an electrode (10) according to an example of the present disclosure, the first binder may include an acrylic polymer. The acrylic polymer refers to a polymer that is polymerized with a composition including one or more acrylic monomers and includes repeating units derived from the acrylic monomers. In addition, the acrylic monomer refers to acrylic acid, methacrylic acid, or derivatives thereof, such as acrylic acid esters or methacrylic acid esters. In addition, examples of the acrylic polymer include, but are not limited to, poly(acrylic acid) (PAA) or poly(methyl methacrylate) (PMMA).

[0102] Since the first binder includes an acrylic polymer, the adhesive strength between the first active material layer (210) and the current collector (100) can be improved, and wrinkles and swelling of the electrode (10) can be prevented, and excellent capacity retention and energy density can be secured.

[0103] The glass transition temperature (Tg) of the above acrylic polymer is 50 ℃ or more, 55 ℃ or more, 60 ℃ or more, 65 ℃ or more, 70 ℃ or more, 75 ℃ or more, 80 ℃ or more, 85 ℃ or more, 90 ℃ or more, 95 ℃ or more, 100 ℃ or more, 105 ℃ or more, or 110 ℃ or more, or 300 ℃ or less, 290 ℃ or less, 280 ℃ or less, 270 ℃ or less, 260 ℃ or less, 250 ℃ or less, 240 ℃ or less, 230 ℃ or less, 220 ℃ or less, 210 ℃ or less, 200 ℃ or less, 190 ℃ or less, 180 ℃ or less, 170 ℃ or less, 160 ℃ or less, 150 ℃ or less, or 140 ℃ or less. Or it may be 130 ℃ or less. In addition, the glass transition temperature (Tg) of the acrylic polymer may be within a range formed by appropriately selecting the upper and lower limits described above.

[0104] When the glass transition temperature of the above acrylic polymer satisfies the above range, the occurrence of wrinkles and swelling of the electrode (10) can be prevented, and excellent capacity retention rate and energy density can be secured.

[0105] The weight average molecular weight (Mw) of the above acrylic polymer is 10,000 g / mol or more, 15,000 g / mol or more, 20,000 g / mol or more, 25,000 g / mol or more, 30,000 g / mol or more, 35,000 g / mol or more, 40,000 g / mol or more, 45,000 g / mol or more, 50,000 g / mol or more, 55,000 g / mol or more, 60,000 g / mol or more, 65,000 g / mol or more, or 70,000 g / mol or more, or 200,000 g / mol or less, 190,000 g / mol or less, 180,000 g / mol or less, 170,000 g / mol or less, 160,000 g / mol or less, It may be 150,000 g / mol or less, 140,000 g / mol or less, 130,000 g / mol or less, 120,000 g / mol or less, 110,000 g / mol or less, 100,000 g / mol or less, 90,000 g / mol or less, or 80,000 g / mol or less. The weight average molecular weight (Mw) of the acrylic polymer may be within a range formed by appropriately selecting the above-mentioned upper and lower limits.

[0106] Additionally, the polydispersity index (PDI) of the acrylic polymer may be from 1 to 2 or from 1 to 1.5.

[0107] The above acrylic polymer can prevent wrinkles and swelling and secure excellent capacity retention and energy density by satisfying the weight average molecular weight and polydispersity index within the above range.

[0108] In an electrode (10) according to an example of the present disclosure, the first active material layer (210) may further include, in addition to the first binder including the acrylic polymer, another binder that can be used in the art. For example, as the additional binder, polyvinylidene fluoride (PVdF), a copolymer of polyhexafluoropropylene-polyvinylidene fluoride (PVdF / HFP)), poly(vinylacetate), polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, alkylated polyethylene oxide, polyvinyl ether, polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, polyvinylpyridine, styrene-butadiene rubber, or acrylonitrile-butadiene rubber, etc. may be further used.

[0109] In an electrode (10) according to an example of the present disclosure, the type of the second binder is not particularly limited as long as it satisfies the range of the glass transition temperature described above.

[0110] The second binder may include a polymer comprising a first repeating unit and a second repeating unit. The first repeating unit may include a carbon-carbon multiple bond, and the second repeating unit may include an aromatic group. The carbon-carbon multiple bond refers to a double bond or a triple bond between carbons. In addition, the first repeating unit may include a carbon-carbon multiple bond within the main chain structure, and the second repeating unit may include an aromatic group as a functional group. In addition, in order to secure a second binder having an appropriate level of glass transition temperature, the first repeating unit may include a carbon-carbon double bond within the main chain structure, and the second repeating unit may include an aryl group. Here, the aryl group included in the second repeating unit has no particular limitation on the number of carbon atoms, but the number of carbon atoms in the main chain structure of the aryl group may be 6 to 30, or 6 to 26, or 6 to 22, or 6 to 20, or 6 to 18, or 6 to 15. In addition, the aryl group included in the second repeating unit may be a phenyl group or a phenylalkyl group, etc.

[0111] In an electrode (10) according to an example of the present disclosure, the polymer including the first repeating unit and the second repeating unit may have a ratio (N1 / N2) of the mole number (N1) of the first repeating unit to the mole number (N2) of the second repeating unit of 1 or more, 1.2 or more, 1.4 or more, 1.6 or more, 1.8 or more, or 2 or more, or 5 or less, 4.5 or less, 4 or less, 3.5 or less, or 3 or less. Since the second binder includes the polymer in which the mole number ratio of the above-described repeating units is controlled as described above, it is possible to prevent wrinkles and swelling of the electrode (10) by combining with the first active material layer (210) and to secure excellent capacity retention and energy density.

[0112] In an electrode (10) according to an example of the present disclosure, the polymer including the first repeating unit and the second repeating unit included in the second binder may be a rubber polymer. As the rubber polymer, for example, styrene-butadiene rubber or acrylonitrile-butadiene rubber may be used.

[0113] The glass transition temperature (Tg) of the polymer including the first repeating unit and the second repeating unit included in the second binder may be -120°C or higher, -110°C or higher, -100°C or higher, -95°C or higher, -90°C or higher, -85°C or higher, -80°C or higher, -75°C or higher, -70°C or higher, -65°C or higher, -60°C or higher, -55°C or higher, or -50°C or higher, or -10°C or lower, -15°C or lower, -20°C or lower, -25°C or lower, -30°C or lower, -35°C or lower, -40°C or lower, or -45°C or lower. The glass transition temperature (Tg) of the polymer may be within a range formed by appropriately selecting the above-mentioned upper and lower limits. Since the second binder includes a polymer including the first repeating unit and the second repeating unit having a glass transition temperature within the aforementioned range, it is possible to prevent wrinkles and swelling of the electrode (10) by combining with the first active material layer (210) and secure excellent capacity retention and energy density.

[0114] In an electrode (10) according to an example of the present disclosure, the weight average molecular weight (Mw) of the polymer including the first repeating unit and the second repeating unit included in the second binder is 1,000 g / mol or more, 5,000 g / mol or more, 10,000 g / mol or more, 15,000 g / mol or more, 20,000 g / mol or more, 25,000 g / mol or more, 30,000 g / mol or more, 35,000 g / mol or more, or 40,000 g / mol or more, or 100,000 g / mol or less, 95,000 g / mol or less, 90,000 g / mol or less, 85,000 g / mol or less, 80,000 g / mol or less, 75,000 g / mol or less, 70,000 g / mol or less, It may be 65,000 g / mol or less, 60,000 g / mol or less, 55,000 g / mol or less, 50,000 g / mol or less, or 45,000 g / mol or less. The weight average molecular weight (Mw) of the polymer may be within a range formed by appropriately selecting the upper and lower limits described above.

[0115] Additionally, in the electrode (10), the polydispersity index (PDI) of the polymer including the first repeating unit and the second repeating unit included in the second binder may be 1 to 5, 1 to 4.5, or 1 to 4.

[0116] In the electrode (10), when the weight average molecular weight of the polymer including the first repeating unit and the second repeating unit satisfies the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured. In addition, when the polymer including the first repeating unit and the second repeating unit satisfies the weight average molecular weight and polydispersity index within the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured.

[0117] In an electrode (10) according to an example of the present disclosure, the second active material layer (220) may additionally include a thickener. In the present disclosure, the thickener may be a component that increases viscosity measured under the same conditions. The thickener is not particularly limited as long as it is used in the art. In particular, the thickener may suitably include a cellulose polymer. For example, the second active material layer (220) may include a second binder and additionally include a cellulose polymer as the thickener. Specifically, the second active material layer (220) may include a polymer including the first repeating unit and the second repeating unit described above, and a cellulose polymer. Through this combination, a second active material layer (220) having excellent flexibility and appropriate strength can be secured. In addition, the second active material layer (220) as described above can be combined with the first active material layer (210) described above to prevent wrinkles and swelling of the electrode (10) and secure excellent capacity retention and energy density.

[0118] The cellulose polymer may be, for example, at least one selected from the group consisting of carboxymethyl cellulose, starch, hydroxypropyl cellulose, regenerated cellulose, cellulose acetate, cellulose acetate butylate, and cellulose acetate propionate. In an electrode (10) according to an example of the present disclosure, the weight average molecular weight (Mw) of the cellulose polymer included in the second active material layer (220) is 50,000 g / mol or more, 60,000 g / mol or more, 70,000 g / mol or more, 80,000 g / mol or more, 90,000 g / mol or more, 100,000 g / mol or more, 110,000 g / mol or more, 120,000 g / mol or more, 130,000 g / mol or more, 140,000 g / mol or more, 150,000 g / mol or more, 160,000 g / mol or more, 170,000 g / mol or more, 180,000 g / mol or more, 190,000 g / mol or more, or 200,000 g / mol The weight average molecular weight (Mw) of the cellulose polymer may be within a range formed by appropriately selecting the upper and lower limits described above.

[0119] Additionally, in the electrode (10), the polydispersity index (PDI) of the cellulose polymer included in the second active material layer (220) may be 5 to 40, 10 to 30, or 12 to 25.

[0120] In the above electrode (10), when the weight average molecular weight of the cellulose polymer satisfies the above range, wrinkle formation and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured. In addition, when the cellulose polymer satisfies the weight average molecular weight and polydispersity index within the above range, wrinkle formation and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured.

[0121] In an electrode (10) according to an example of the present disclosure, the second binder may include a polymer including the first repeating unit and the second repeating unit in an amount of 55 wt% or more, 60 wt% or more, 65 wt% or more, 70 wt% or more, 75 wt% or more, 80 wt% or more, 85 wt% or more, 90 wt% or more, 95 wt% or more, or 99 wt% or more, based on the total weight of the second binder. Since the second binder includes the polymer including the first repeating unit and the second repeating unit within the above range, it is possible to prevent wrinkles and swelling of the electrode (10) by combining with the first active material layer (210) and secure excellent capacity retention and energy density.

[0122] Meanwhile, in an electrode (10) according to an example of the present disclosure, in the second active material layer (220), the weight ratio (P1 / P2) of the polymer (P1) including the first repeating unit and the second repeating unit and the cellulose polymer (P2) may be 0.1 or more, 0.15 or more, 0.2 or more, 0.25 or more, 0.3 or more, 0.35 or more, 0.4 or more, 0.45 or more, or 0.5 or more, or 1 or less, 0.9 or less, 0.8 or less, 0.7 or less, or 0.6 or less. The ratio (P1 / P2) may be included within a range formed by appropriately selecting the above-mentioned upper and lower limits. Since the second active material layer (220) includes a polymer including the first repeating unit and the second repeating unit and a cellulose polymer in an appropriate weight ratio as described above, it is possible to prevent wrinkles and swelling of the electrode (10) by combining with the first active material layer (210) and to secure excellent capacity retention and energy density.

[0123] In an electrode (10) according to an example of the present disclosure, the second active material layer (220) may further include a second binder including a polymer including the first repeating unit and the second repeating unit, and other binders that can be used in the art in addition to the cellulose polymer. For example, as the additional binder, polyvinylidene fluoride (PVdF), a copolymer of polyhexafluoropropylene-polyvinylidene fluoride (PVdF / HFP)), poly(vinylacetate), polyvinyl alcohol, polyethylene oxide, polyvinylpyrrolidone, alkylated polyethylene oxide, polyvinyl ether, polytetrafluoroethylene, polyvinyl chloride, polyacrylonitrile, or polyvinylpyridine, etc. may be further used.

[0124] In an electrode (10) according to an example of the present disclosure, the first active material layer (210) and the second active material layer (220) may each independently include a carbon-based active material and a silicon-based active material. The carbon-based active material and the silicon-based active material may be, for example, materials capable of transferring electrons in a lithium battery cell.

[0125] The above carbon-based active material is not particularly limited, and any material that can be used in the art may be used. Examples of the carbon-based active material include amorphous carbon, graphite, natural graphite, artificial graphite, mesocarbon microbeads, or pitch-based carbon fibers. One type of these carbon-based active materials may be used alone, or two types may be used in combination.

[0126] The above silicon-based active material is silicon (Si), silicon-containing alloy, SiO, SiO2, SiO x (wherein, x is 0.01 or more and less than 2), and a composite of a Si-containing material and conductive carbon, etc., which is formed by covering or composite-forming a Si-containing material with conductive carbon. Such silicon-based active materials may be used alone or in combination of two types. High capacity can be achieved by using a silicon-based active material. However, the silicon-based active material tends to have a somewhat greater volume expansion and contraction due to charge and discharge than a carbon-based active material. An electrode (10) according to an example of the present disclosure can mitigate the wrinkle phenomenon of the electrode (10) and respond to volume expansion by introducing a silicon-based active material for high capacity while satisfying characteristics such as an appropriate composition and ratio of each of the first active material layer (210) and the second active material layer (220), as well as thickness.

[0127] As the above-mentioned silicon-containing alloy, an alloy composition including silicon and at least one element selected from the group consisting of titanium, iron, cobalt, nickel, and copper may be exemplified. In addition, as the silicon-containing alloy, an alloy composition including transition metals such as silicon, aluminum, and iron, or including rare earth elements such as silicon, tin, and yttrium may also be used.

[0128] SiO x may be a compound containing Si and at least one of SiO and SiO2, wherein x may be generally 0.01 or more and less than 2. SiO x For example, it can be formed by using the disproportionation reaction of SiO. Specifically, SiO x SiO can be produced by optionally heat-treating SiO in the presence of a polymer such as polyvinyl alcohol to generate silicon and silicon dioxide. The heat treatment can be performed by grinding and mixing SiO and the polymer, and then at a temperature of, for example, about 900°C or higher or about 1000°C or higher in an atmosphere containing organic gas and / or vapor.

[0129] A composite of a Si-containing material and conductive carbon includes, for example, a compound obtained by heat-treating a pulverized mixture of SiO, a polymer such as polyvinyl alcohol, and optionally a carbon-based material in an atmosphere containing organic gas and / or vapor. In addition, the composite can also be obtained by known methods, such as a method of coating the surface of SiO particles by a chemical vapor deposition method using an organic gas, etc., or a method of forming composite particles (assembly) of SiO particles and graphite or artificial graphite by a mechanochemical method.

[0130] The first active material layer (210) contains 1,000 parts by weight or more, 1,100 parts by weight or more, 1,200 parts by weight or more, 1,300 parts by weight or more, 1,400 parts by weight or more, 1,500 parts by weight or more, 1,600 parts by weight or more, 1,700 parts by weight or more, 1,800 parts by weight or more, 1,900 parts by weight or more, 2,000 parts by weight or more, 2,100 parts by weight or more, 2,200 parts by weight or more, 2,300 parts by weight or more, 2,400 parts by weight or more, 2,500 parts by weight or more, 2,600 parts by weight or more, 2,700 parts by weight or more, 2,800 parts by weight or more, 2,900 parts by weight or more, or 3,000 parts by weight or more, of carbon-based active material relative to 100 parts by weight of the first binder, or It may include 10,000 parts by weight or less, 9,000 parts by weight or less, 8,000 parts by weight or less, 7,000 parts by weight or less, 6,000 parts by weight or less, 5,000 parts by weight or less, or 4,000 parts by weight or less. The first active material layer (210) may include a carbon-based active material within a range formed by appropriately selecting the upper and lower limits described above. The first active material layer (210) may prevent wrinkles and swelling of the electrode (10) and secure excellent capacity retention and energy density by controlling the weight ratio of the carbon-based active material and the first binder as described above.

[0131] In addition, the weight ratio (C1 / Si1) of the carbon-based active material (C1) and the silicon-based active material (Si1) in the first active material layer (210) may be 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or more, or 4.5 or more, or 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, or 5 or less. The weight ratio (C1 / Si1) may be within a range formed by appropriately selecting the above-described upper and lower limits. When the first active material layer (210) includes the above-described first binder and satisfies the above-described weight ratio (C1 / Si1) within the above-described range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured.

[0132] In addition, the first active material layer (210) may include a carbon-based active material having an average particle size (DC1) of 1 ㎛ or more, 2 ㎛ or more, 3 ㎛ or more, 4 ㎛ or more, 5 ㎛ or more, 6 ㎛ or more, 7 ㎛ or more, 8 ㎛ or more, 9 ㎛ or more, or 10 ㎛ or more, or 100 ㎛ or less, 90 ㎛ or less, 80 ㎛ or less, 70 ㎛ or less, 60 ㎛ or less, 50 ㎛ or less, or 40 ㎛ or less. The average particle size (DC1) of the carbon-based active material may be within a range formed by appropriately selecting the above-described upper and lower limits. The first active material layer (210) may secure excellent capacity retention and energy density by including a carbon-based active material having the above-described average particle size.

[0133] Meanwhile, the average particle size, a term used in the present disclosure, refers to the D50 particle size of the measurement target, which may be the particle size measured using a MASTERSIZER3000 device from Marvern in accordance with the ISO-13320 standard. For specific measurements of the average particle size, please refer to the <Method for Measuring Physical Properties> below.

[0134] In addition, the first active material layer (210) may include a silicon-based active material having an average particle size (DSi1) of 0.1 ㎛ or more, 0.2 ㎛ or more, 0.3 ㎛ or more, 0.4 ㎛ or more, 0.5 ㎛ or more, 0.6 ㎛ or more, 0.7 ㎛ or more, 0.8 ㎛ or more, 0.9 ㎛ or more, or 1 ㎛ or more, or 100 ㎛ or less, 90 ㎛ or less, 80 ㎛ or less, 70 ㎛ or less, 60 ㎛ or less, 50 ㎛ or less, 40 ㎛ or less, or 30 ㎛ or less. The average particle size (DSi1) of the silicon-based active material may be within a range formed by appropriately selecting the above-described upper and lower limits. The first active material layer (210) may secure excellent capacity retention and energy density by including a silicon-based active material having the above-described average particle size.

[0135] In addition, in the first active material layer (210), the ratio (DC1 / DSi1) of the average particle size (DC1) of the carbon-based active material to the average particle size (DSi1) of the silicon-based active material may be 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, or 1.4 or more, or 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, or 10 or less. The ratio (DC1 / DSi1) may be within a range formed by appropriately selecting the upper and lower limits described above. When the first active material layer (210) includes the first binder described above and satisfies the average particle size ratio (DC1 / DSi1) within the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured.

[0136] The second active material layer (220) may contain a carbon-based active material in an amount of 500 parts by weight or more, 600 parts by weight or more, 700 parts by weight or more, 800 parts by weight or more, 900 parts by weight or more, 1,000 parts by weight or more, 1,100 parts by weight or more, 1,200 parts by weight or more, 1,300 parts by weight or more, 1,400 parts by weight or more, 1,500 parts by weight or more, 1,600 parts by weight or more, or 1,700 parts by weight or more, or 5,000 parts by weight or less, 4,500 parts by weight or less, 4,000 parts by weight or less, 3,500 parts by weight or less, 3,000 parts by weight or less, 2,500 parts by weight or less, or 2,000 parts by weight or less, relative to 100 parts by weight of the second binder. The second active material layer (220) may include a carbon-based active material within a range formed by appropriately selecting the upper and lower limits described above. The second active material layer (220) may prevent the occurrence of wrinkles and swelling of the electrode (10) and secure excellent capacity retention and energy density by controlling the weight ratio of the carbon-based active material and the second binder as described above.

[0137] In the second active material layer (220), the weight ratio (C2 / Si2) of the carbon-based active material (C2) and the silicon-based active material (Si2) may be 1 or more, 1.5 or more, 2 or more, 2.5 or more, 3 or more, 3.5 or more, 4 or more, or 4.5 or more, or 10 or less, 9 or less, 8 or less, 7 or less, 6 or less, or 5 or less. The weight ratio (C2 / Si2) may be within a range formed by appropriately selecting the upper and lower limits described above. When the second active material layer (220) includes the second binder described above and satisfies the weight ratio (C2 / Si2) within the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured. In addition, the weight ratio (C1 / Si1) value of the above-mentioned carbon-based active material (C1) and silicon-based active material (Si1) may be greater than the weight ratio (C2 / Si2) value of the above-mentioned carbon-based active material (C2) and silicon-based active material (Si2).

[0138] In addition, the second active material layer (220) may include a carbon-based active material having an average particle size (DC2) of 1 ㎛ or more, 2 ㎛ or more, 3 ㎛ or more, 4 ㎛ or more, 5 ㎛ or more, 6 ㎛ or more, 7 ㎛ or more, 8 ㎛ or more, 9 ㎛ or more, or 10 ㎛ or more, or 100 ㎛ or less, 90 ㎛ or less, 80 ㎛ or less, 70 ㎛ or less, 60 ㎛ or less, 50 ㎛ or less, or 40 ㎛ or less. The average particle size (DC2) of the carbon-based active material may be within a range formed by appropriately selecting the above-described upper and lower limits. The second active material layer (220) may secure excellent capacity retention and energy density by including a carbon-based active material having the above-described average particle size.

[0139] In addition, the second active material layer (220) may include a silicon-based active material having an average particle size (DSi2) of 0.1 ㎛ or more, 0.2 ㎛ or more, 0.3 ㎛ or more, 0.4 ㎛ or more, 0.5 ㎛ or more, 0.6 ㎛ or more, 0.7 ㎛ or more, 0.8 ㎛ or more, 0.9 ㎛ or more, or 1 ㎛ or more, or 100 ㎛ or less, 90 ㎛ or less, 80 ㎛ or less, 70 ㎛ or less, 60 ㎛ or less, 50 ㎛ or less, 40 ㎛ or less, or 30 ㎛ or less. The average particle size (DSi1) of the silicon-based active material may be within a range formed by appropriately selecting the above-described upper and lower limits. The second active material layer (220) may secure excellent capacity retention and energy density by including a silicon-based active material having the above-described average particle size.

[0140] In addition, in the second active material layer (220), the ratio (DC2 / DSi2) of the average particle size (DC2) of the carbon-based active material to the average particle size (DSi2) of the silicon-based active material may be 1 or more, 1.1 or more, 1.2 or more, 1.3 or more, or 1.4 or more, or 20 or less, 19 or less, 18 or less, 17 or less, 16 or less, 15 or less, 14 or less, 13 or less, 12 or less, 11 or less, or 10 or less. The ratio (DC2 / DSi2) may be within a range formed by appropriately selecting the upper and lower limits described above. When the second active material layer (220) includes the second binder described above and satisfies the average particle size ratio (DC2 / DSi2) within the above range, wrinkle occurrence and swelling phenomenon can be prevented and excellent capacity retention rate and energy density can be secured.

[0141] Additionally, in the electrode (10) according to an example of the present disclosure, the first active material layer (210) and the second active material layer (220) may each independently include a metal active material. The metal active material may be, for example, lithium metal or an alloy including lithium. As the alloy including lithium, for example, an alloy composition including lithium and at least one element selected from the group consisting of Ag, Al, Ba, Bi, Cu, Ga, Ge, In, Ni, P, Pb, Sb, Si, Sn, Sr, Zn, and Ti may be exemplified, but is not limited thereto.

[0142] In an electrode (10) according to an example of the present disclosure, the first active material layer (210) and the second active material layer (220) may additionally include a conductive material independently, as needed. The conductive material is not particularly limited as long as it has conductivity without causing a chemical change in the battery cell. For example, conductive materials such as graphite such as natural graphite or artificial graphite; carbon black such as carbon black, acetylene black, Ketjen black, channel black, paneth black, lamp black, and thermal black; conductive fibers such as carbon fibers or metal fibers; conductive tubes such as carbon nanotubes (CNTs); metal powders such as fluorocarbon, aluminum, and nickel powders; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives may be used.

[0143] In an electrode (10) according to an example of the present disclosure, the first active material layer (210) and the second active material layer (220) may independently include carbon nanotubes as a conductive material, as needed. The first active material layer (210) and the second active material layer (220) may secure excellent electrical conductivity by using carbon nanotubes as a conductive material. The carbon nanotubes may be classified into single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), or multi-walled carbon nanotubes (MWCNTs) depending on the number of carbon walls. The carbon nanotubes may include at least one selected from the group consisting of the above-described SWCNTs, DWCNTs, and MWCNTs.

[0144] In an electrode (10) according to an example of the present disclosure, the first active material layer (210) and the second active material layer (220) may additionally include, independently of each other, a thickener, a reinforcing agent, a leveling agent, or an electrolyte additive, as needed. The types of these are not particularly limited as long as they are used in the art.

[0145] In an electrode (10) according to an example of the present disclosure, the ratio (H1 / H2) of the thickness (H1) of the first active material layer and the thickness (H2) of the second active material layer may be greater than 1. In another example, the ratio (H1 / H2) of the thicknesses may be 1.1 or more, 1.2 or more, 1.3 or more, 1.4 or more, or 1.5 or more, or 10 or less, 9.5 or less, 9 or less, 8.5 or less, 8 or less, 7.5 or less, 7 or less, 6.5 or less, 6 or less, 5.5 or less, 5 or less, 4.5 or less, 4 or less, 3.5 or less, 3 or less, 2.5 or less, or 2 or less, or may be within a range formed by appropriately selecting the upper and lower limits described above. The electrode (10) is in contact with the current collector (100) and controls the thickness of the first active material layer including a binder having a higher glass transition temperature than the binder included in the second active material layer within the aforementioned range, thereby preventing wrinkles and swelling and ensuring excellent capacity retention and energy density. The thicknesses of the first active material layer and the second active material layer may refer to the thickness after drying.

[0146] In an electrode (10) according to an example of the present disclosure, the thickness (H1) of the first active material layer (210) may be 60 µm or more, 61 µm or more, 62 µm or more, 63 µm or more, 64 µm or more, 65 µm or more, 66 µm or more, 67 µm or more, 68 µm or more, or 69 µm or more. In addition, the thickness (H1) of the first active material layer (210) may be greater than 50%, greater than 51%, greater than 52%, greater than 53%, greater than 54%, greater than 55%, greater than 56%, greater than 57%, greater than 58%, greater than 59%, or greater than 60% of the total thickness of the active material layer (200), or the upper limit is not particularly limited, but may be 99% or less, 95% or less, 90% or less, 85% or less, 80% or less, 75% or less, or 70% or less. The upper limit of the thickness (H1) of the first active material layer (210) is not particularly limited, but may be determined in consideration of the range of thicknesses that can be had compared to the total thickness.

[0147] In addition, the thickness (H2) of the second active material layer (220) in the electrode (10) may be less than 50%, 49% or less, 48% or less, 47% or less, 46% or less, 45% or less, 44% or less, 43% or less, 42% or less, 41% or less, or 40% or less of the total thickness of the active material layer (200), or the lower limit is not particularly limited, but may have a thickness of 1% or more, 5% or more, 10% or more, 15% or more, 20% or more, 25% or more, 30% or more, 35% or more, or 40% or more. The thickness (H2) of the second active material layer (220) may be determined in consideration of the ratio with the thickness (H1) of the first active material layer (210). When the thickness of the first active material layer (210) and the thickness of the second active material layer (220) are each within the above range, excellent load characteristics and energy density can be secured.

[0148] An electrode (10) according to an example of the present disclosure is T according to the following equation 1 ST may be 30% or less, 29.5% or less, or 29% or less. T according to Equation 1 below S The lower limit of is not particularly limited as it is more advantageous the lower it is, but it can be, for example, 0%, 1% or more, or 2% or more. In addition, T according to the following equation 1 S It can be specifically measured and evaluated according to the following <Method for Measuring Physical Properties>.

[0149] [Formula 1]

[0150] T S = (T2-T1) / T1Х 100 (%)

[0151] In Equation 1, T1 means the thickness of the electrode (10) before charging, and T2 means the thickness of the electrode (10) after charging to SOC (state of charge) 100 under the condition of 0.2 CC / CV charging 4.2 V 0.05C cut-off. In the above, CC / CV means constant voltage / constant current.

[0152] A method for manufacturing an electrode (10) according to an example of the present disclosure may include a step of forming an active material layer (200). The method for manufacturing the electrode (10) may refer to the configuration of the electrode (10) described above.

[0153] In a method for manufacturing an electrode (10) according to an example of the present disclosure, the step of forming an active material layer (200) can be performed in various ways. In particular, since the active material layer (200) includes a first active material layer (210) and a second active material layer (220), it can be performed in various ways.

[0154] In a method for manufacturing an electrode (10) according to an example of the present disclosure, the first active material layer (210) may be formed of a first active material composition, and the second active material layer (220) may be formed of a second active material composition. The first active material composition may include the composition included in the first active material layer (210) described above. In addition, the second active material composition may include the composition included in the second active material layer (220) described above.

[0155] The first active material composition and the second active material composition may each independently additionally include a solvent as needed. The solvent may be appropriately selected in consideration of the desired performance, etc., and may be an aqueous solvent such as water (pure or ultrapure water, etc.), an organic solvent, or a mixed solvent of two or more types. For example, the solvent may be an organic solvent such as N-methyl-2-pyrrolinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxy methane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, methyl propionate, alcohol, or ethyl propionate, or an aqueous solvent such as water, but water is most preferable considering the drying temperature or environmental influences. The content of the solvent may be selected considering the performance of the desired battery cell (1), etc.

[0156] The first active material composition and the second active material composition may use an appropriate amount of solvent considering the included composition and dispersibility. For example, the first active material composition and the second active material composition may each independently include the solvent in an amount of 50 parts by weight or more, 60 parts by weight or more, 70 parts by weight or more, 80 parts by weight or more, 90 parts by weight or more, 100 parts by weight or more, or 110 parts by weight or more, or 10,000 parts by weight or less, 5,000 parts by weight or less, 3,000 parts by weight or less, 2,000 parts by weight or less, 1,000 parts by weight or less, 500 parts by weight or less, 300 parts by weight or less, or 200 parts by weight or less, based on 100 parts by weight of the solid content, or may include the solvent within a range formed by appropriately selecting the upper and lower limits described above.

[0157] In addition, the first active material composition and the second active material composition may include the various components described above. In addition, the first active material composition and the second active material composition may be in a state in which the various components are appropriately dispersed. The first active material composition and the second active material composition may be prepared by adding the various components in an appropriate method and order and then through an appropriate mixing method. The mixing method is not particularly limited and a known method may be used. Specifically, the mixing method may use a mixer such as a ball mill, a sand mill, a bead mill, a pigment disperser, an ultrasonic disperser, a homogenizer, a rotating-orbital mixer, or a fill mixer. Specific details regarding the slurry composition forming the active material layer (200) will be described later.

[0158] The step of forming the above active material layer (200) can be performed by applying a first active material composition onto a release film and drying it, and then applying a second active material composition onto the dried first active material composition layer and drying it. The release film can then be removed to attach the formed active material layer (200) onto a current collector (100) to manufacture an electrode (10).

[0159] In addition, the step of forming the active material layer (200) may be performed by applying a first active material composition on a release film, applying a second active material composition on the applied first active material composition, and then drying the same. The release film may then be removed to attach the formed active material layer (200) on a current collector (100) to manufacture an electrode (10).

[0160] In addition, the step of forming the active material layer (200) can be performed by applying a first active material composition on a current collector, drying it, and then applying a second active material composition on the dried first active material composition layer and drying it. Through this, an electrode (10) can be manufactured.

[0161] In addition, the step of forming the active material layer (200) can be performed by applying a first active material composition, applying a second active material composition on the applied first active material composition, and then drying the same. Through this, an electrode (10) can be manufactured.

[0162] In addition, the method for performing the above-mentioned application is not particularly limited and a known method can be used. Specifically, the method for performing the above-mentioned application may include a doctor blade method, a dip method, a reverse roll method, a direct roll method, a gravure method, an extrusion method, or a brushing method. The coating thickness of the above-mentioned slurry composition may be applied at an appropriate thickness considering the thickness after drying, and the above-mentioned known method may be appropriately selected and performed according to the coating thickness. In addition, the method for performing the above-mentioned rolling may be performed using a rolling jig or the like according to a known method.

[0163] An electrode (10) according to an example of the present disclosure may preferably be a cathode.

[0164] A battery cell (1) according to an example of the present disclosure may include a positive electrode (1a), a negative electrode (1b), and a separator (1c) interposed between the positive electrode and the negative electrode.

[0165] A basic unit that performs a charge and discharge function may be referred to as a battery cell. FIG. 1 is a drawing briefly illustrating an exemplary structure of a battery cell (1) according to an example of the present disclosure. Referring to FIG. 1, the battery cell (1) includes a positive electrode (1a) and a negative electrode (1b), and has a structure in which a separator (1c) is interposed between the positive electrode (1a) and the negative electrode (1b). In addition, the battery cell (1) includes a structure including the positive electrode (1a), the negative electrode (1b), and the separator (1c), and is referred to as an electrode assembly. The battery cell (1) includes an outer material (1e) capable of housing the electrode assembly, and has a structure in which an electrolyte (1d) is filled in a space sealed by the outer material (1e).

[0166] According to an example of the present disclosure, a battery cell (1) has L according to the following equation 2 R This can be 80% or more, 81% or more, 82% or more, 83% or more, 84% or more, 85% or more, 86% or more, 87% or more, 88% or more, or 89% or more. In addition, L according to the following formula 2 R The upper limit of is not particularly limited because the higher it is, the closer it is, and it is advantageous, but it can be, for example, 100% or less, 99% or less, 98% or less, 97% or less, 96% or less, or 95% or less. In addition, L according to the following equation 2 R can be specifically measured and evaluated according to the <Method for Measuring Physical Properties> below. For the battery cell (1), if the LR according to the following Equation 2 satisfies the above range, it can be evaluated that the battery cell has an excellent capacity retention rate.

[0167] [Formula 2]

[0168] L R = L2 / L1Х 100 (%)

[0169] In Equation 2, L1 is the discharge capacity in 1 cycle under the condition that 25 ℃ is maintained, L2 is the discharge capacity in 300 cycles under the condition that 25 ℃ is maintained, and 1 cycle is defined as charging at 2.0 C c-rate in the SOC 8 to 50 range, charging at 0.5 C c-rate to SOC 80, and then discharging at 1 / 3 C c-rate to charge and discharge at DOD72 (SOC 8 to 80).

[0170] The above cathode (1a) refers to a reduction electrode to which an electron transport material transfers electrons when the battery cell (1) is discharged, and the above anode (1b) refers to an oxidation electrode to which an electron transport material transfers electrons when the battery cell (1) is discharged.

[0171] In a battery cell (1) according to an example of the present disclosure, the positive electrode (1a) or negative electrode (1b) may be an electrode (10) according to an example of the present disclosure described above.

[0172] In a battery cell (1) according to a specific example of the present disclosure, the negative electrode (1b) in the battery cell (1) may be the electrode (10) according to the example of the present disclosure described above. In the battery cell (1) according to an example of the present disclosure, the negative electrode (1b) may satisfy both the configuration and characteristics of the electrode (10) according to an example of the present disclosure.

[0173] In a battery cell (1) according to an example of the present disclosure, the negative electrode (1b) may include a negative electrode current collector and a negative electrode active material layer positioned on at least one surface of the negative electrode current collector. Here, the negative electrode current collector may be the current collector (100) of the electrode (10) described above, and the negative electrode active material layer may be the active material layer (200) of the electrode (10) described above.

[0174] In addition, in the battery cell (1) according to an example of the present disclosure, the negative electrode active material layer of the negative electrode (1b) may include a first negative electrode active material layer that is in contact with the negative electrode current collector and includes a first binder, and a second negative electrode active material layer that is positioned on the first negative electrode active material layer and includes a second binder. Here, the first negative electrode active material layer may be the first active material layer (210) of the electrode (10) described above, and the second negative electrode active material layer may be the second active material layer (220) of the electrode (10) described above.

[0175] In addition, in the battery cell (1) according to an example of the present disclosure, the negative electrode (1b) can satisfy both the configuration and characteristics of the electrode (10) according to an example of the present disclosure as described above. That is, the glass transition temperature relationship between the first binder and the second binder in the negative electrode (1b), the thickness relationship between the first negative electrode active material layer and the second negative electrode active material layer, and the like are the same as those of the electrode (10) described above, and thus will be omitted below.

[0176] In a battery cell (1) according to an example of the present disclosure, the positive electrode (1a) can be manufactured by applying a positive electrode active material composition on a positive electrode current collector and then drying it to form a positive electrode active material layer. If necessary, rolling can be performed after drying. Among the methods for manufacturing the positive electrode (1a), the methods for applying, drying, rolling, etc. can refer to the method for manufacturing the electrode (10) according to an example of the present disclosure.

[0177] The positive electrode current collector is not particularly limited in type, size, shape, etc., as long as it is conductive and does not cause a chemical change in the battery cell (1). As the positive electrode current collector (100), for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. can be used. As the negative electrode current collector (100), as long as it is conductive and does not cause a chemical change in the battery cell (1), the type, size, shape, etc., are not particularly limited. As the negative electrode current collector (100), for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., an aluminum-cadmium alloy, etc. can be used.

[0178] In addition, the positive electrode current collector may have an appropriate thickness as needed. Although not particularly limited, the positive electrode current collector may have a thickness of 1 μm to 500 μm, a thickness of 1 μm to 300 μm, a thickness of 1 μm to 100 μm, or a thickness of 1 μm to 50 μm.

[0179] In addition, the positive electrode current collector may have fine irregularities formed on its surface to further enhance adhesion to the positive electrode active material layer. For example, the shape of the positive electrode current collector may be one or more selected from the group consisting of a film, a sheet, a foil, a net, a porous body, a foam, and a non-woven fabric.

[0180] The above-described positive electrode active material layer may include a positive electrode active material. The positive electrode active material is not particularly limited, but may include, for example, layered compounds such as lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), or compounds substituted with one or more transition metals; lithium iron oxide such as LiFe3O4; and chemical formula Li1. +c1 Mn2 - c1 Lithium manganese oxides such as O4(0≤c1≤0.33), LiMnO3, LiMn2O3, or LiMnO2; lithium copper oxide (Li2CuO2); vanadium oxides such as LiV3O8, V2O5, or Cu2V2O7; chemical formula LiNi1 - c2 M c2 Ni-site type lithium nickel oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Mn, Al, Cu, Fe, Mg, B, and Ga, and satisfies 0.01≤c2≤0.3); chemical formula LiMn 2-c3 M c3 Lithium manganese composite oxide represented by O2 (wherein, M is at least one selected from the group consisting of Co, Ni, Fe, Cr, Zn, and Ta, and satisfies 0.01≤c3≤0.1) or Li2Mn3MO8 (wherein, M is at least one selected from the group consisting of Fe, Co, Ni, Cu, and Zn); lithium nickel cobalt manganese (NCM) composite oxide, lithium nickel cobalt manganese aluminum (NCMA) composite oxide, and LiMn2O4 in which a part of the Li in the chemical formula is replaced with an alkaline earth metal ion, etc. can be exemplified.

[0181] The above-mentioned positive electrode active material layer may include a binder. There is no particular limitation on the specific type of the binder, and any material that enhances adhesion between positive electrode active materials and adhesion between the positive electrode active material layer and the positive electrode current collector may be used.

[0182] The type of the above binder is not particularly limited. For example, polyvinylidene fluoride (PVDF), polyvinyl alcohol, styrene butadiene rubber (SBR), polyethylene oxide, carboxyl methyl cellulose (CMC), cellulose acetate, cellulose acetate butylate, cellulose acetate propionate, cyanoethylpullulan, cyanoethyl polyvinylalcohol, cyanoethyl cellulose, cyanoethyl sucrose, pullulan, polymethylmethacrylate, polybutylacrylate, polyacrylonitrile, At least one selected from the group consisting of polyvinylpyrrolidone, polyvinylacetate, polyethylene-co-vinyl acetate, and polyarylate may be used.

[0183] The above-described positive electrode active material layer may additionally include a conductive material. The conductive material is not particularly limited as long as it is conductive and does not cause a chemical change in the battery cell. For example, conductive materials such as graphite, such as natural graphite or artificial graphite; carbon black, such as carbon black, acetylene black, Ketjen black, channel black, paneth black, lamp black, or thermal black; conductive fibers, such as carbon fibers or metal fibers; conductive tubes, such as carbon nanotubes (CNTs); metal powders, such as fluorocarbon, aluminum, or nickel powders; conductive whiskers, such as zinc oxide or potassium titanate; conductive metal oxides, such as titanium oxide; and conductive materials, such as polyphenylene derivatives, may be used.

[0184] The positive electrode active material composition forming the positive electrode active material layer may include the positive electrode active material and binder described above, and may additionally include a conductive material as needed. In addition, the positive electrode active material composition may additionally include a solvent. The solvent may be appropriately selected in consideration of the desired performance, etc., and may be an aqueous solvent such as water (pure or ultrapure water, etc.), an organic solvent, or a mixed solvent of two or more types. For example, the solvent may be an organic solvent such as N-methyl-2-pyrrolinone, propylene carbonate, ethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, gamma-butyrolactone, 1,2-dimethoxyethane, tetrahydrofuran, 2-methyl tetrahydrofuran, dimethylsulfoxide, formamide, dimethylformamide, acetonitrile, nitromethane, methyl formate, methyl acetate, triester phosphate, trimethoxy methane, sulfolane, methyl sulfolane, 1,3-dimethyl-2-imidazolidinone, propylene carbonate derivatives, tetrahydrofuran derivatives, methyl propionate, alcohol, or ethyl propionate, or an aqueous solvent such as water, but water is most preferable considering the drying temperature or environmental influences. The content of the solvent may be selected considering the performance of the desired battery cell (1), etc.

[0185] The positive electrode active material composition forming the above positive electrode active material layer can appropriately adjust the content ratios of the active material and binder, as well as the conductive material and solvent, to achieve the purpose. Known content ratios can be applied.

[0186] In addition, the separator (1c) refers to a membrane that prevents electrical short-circuiting between the positive and negative electrodes while allowing an electron transport material to pass through. The separator may be used without particular limitation as long as it is commonly used in the art. In particular, the separator preferably has low resistance to ion movement of the electrolyte and excellent wettability of the electrolyte. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene polymer, a propylene polymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0187] In addition, the electrolyte (1d) refers to a medium that causes the movement of electron transport substances so that the electrochemical reaction between the positive electrode (1a) and the negative electrode (1b) can occur smoothly. The electrolyte may be a generally used organic liquid electrolyte, inorganic liquid electrolyte, gel-type polymer electrolyte, molten inorganic electrolyte, etc., but is not limited thereto. Meanwhile, although Fig. 1 illustrates a liquid electrolyte (1d), as described above, a solid-state electrolyte such as a gel-type polymer electrolyte may also be used. A battery using a solid-state electrolyte is generally called a solid battery or an all-solid-state battery. In the case of a liquid-state electrolyte, it generally includes an organic solvent and a lithium salt.

[0188] As the organic solvent, any solvent that can serve as a medium through which ions involved in the electrochemical reaction of the battery cell can move may be used without particular limitation. Specifically, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylenecarbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond) and amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, a carbonate solvent is preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of a battery cell and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0189] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is preferable to use the lithium salt at a concentration of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte has appropriate conductivity and viscosity, so that it can exhibit excellent electrolyte performance, and lithium ions can move effectively.

[0190] In addition to the electrolyte components, the electrolyte may further contain one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be contained in an amount of 0.1 to 5 wt% based on the total weight of the electrolyte.

[0191] The above is classified into several types depending on the type of electron transport material. For example, if the electron transport material is lithium (including Li ions), the battery is called a lithium ion battery.

[0192] In addition, the outer covering (1e) can protect the positive electrode (1a), negative electrode (1b), and separator (1c) from external impact and prevent the electrolyte (1d) from leaking out. Depending on the shape of the outer covering (1e), the battery cell (1) can be classified into a square shape, a cylindrical shape, or a pouch shape.

[0193] A battery cell assembly is a collection of one or more battery cells (1) electrically connected together. The battery cell assembly may be exemplified by a battery module and a battery pack, for example.

[0194] Additionally, a battery cell assembly according to an example of the present disclosure includes one or more battery cells, and the battery cells may be battery cells (1) according to the example of the present disclosure described above.

[0195] A structure in which the above battery cells (1) are bundled in a certain number and placed in a housing to protect them from external shock, heat, vibration, etc. is called a battery module. Patent Document 1 discloses an example of a battery module. Fig. 2 is a drawing that simply shows an exemplary structure of a battery module (2) according to an example of the present disclosure. Referring to Fig. 2, the battery module (2) has a structure including a battery cell unit (2a), upper and lower housings (2b-1, 2b-2), a busbar (2c), and inner and outer covers (2d-1, 2d-2).

[0196] The above battery cell unit (2a) includes one or more battery cells (1), and when there are multiple battery cells, it may refer to a structure in which the battery cells (1) are connected in series and / or in parallel. The battery cell unit (2a) may be embedded in a space formed by the lower housing (2b-1) and the upper housing (2b-2). However, the method of embedding the battery cell unit (2a) is not limited by Fig. 2.

[0197] Meanwhile, the battery cell (1) includes a positive tab extending from the positive electrode and a negative tab extending from the negative electrode. The battery cell unit (2a) has a structure in which the positive tabs and negative tabs protrude as many times as the number of battery cells (1) included. The positive tabs and negative tabs can be electrically connected to a bus bar (2c) having a slit, respectively. The positive tabs and negative tabs can be electrically connected by being inserted into the slits of the bus bar (2c), respectively. In addition, the battery module (2) includes an inner cover (2d-1) and an outer cover (2d-2) to cover the bus bar (2c) and the battery cell unit (2a).

[0198] A structure in which various control devices and protection systems, such as a BMS (Battery Management System) and a cooling device, are mounted on the above-mentioned battery module (2) is called a battery pack. Patent Document 2 discloses an example of a battery pack. However, recently, there are cases in which a battery pack is constructed directly from battery cells (1) rather than a battery module (2). This case is called a cell-to-pack.

[0199] Fig. 3 is a schematic diagram illustrating an exemplary structure of a battery pack (3) according to an example of the present disclosure. Referring to Fig. 3, the battery pack (3) is equipped with one or more battery modules (2) and electrical components (3e) such as various control devices, such as a BMS, in a receiving space (3b) formed inside a pack housing (3a).

[0200] The above battery pack (3) may be provided with a cross member (3d) protruding from the bottom part (3a-1) of the pack housing (3a) across the entire bottom part (3a-1) to connect the opposing side wall parts (3a-2) of the pack housing (3a) in order to secure the structural rigidity of the pack housing (3a), and a partition wall (3c) protruding from the bottom part (3a-1) of the pack housing (3a) in a manner that connects the cross member (3d) and the side wall part (3a-2).

[0201] An electric device according to an example of the present disclosure may include one or more selected from a group consisting of a battery cell (1) and one or more battery cell assemblies according to an example of the present disclosure. The aforementioned electric device refers to a device that operates through power generated from the battery cell (1), etc., and may be, for example, a mobile phone, a home appliance, an electric vehicle, a hybrid vehicle, or an energy storage system (ESS).

[0202] The structural or functional descriptions of the embodiments in this disclosure are merely illustrative for the purpose of explaining embodiments according to the technical concept of this disclosure. Furthermore, embodiments according to the technical concept of this disclosure may be implemented in various forms other than those described in this disclosure. Furthermore, the technical concept of this disclosure is not limited to the embodiments described in this disclosure.

[0203] <Method of measuring physical properties>

[0204] The properties mentioned below were measured as follows.

[0205] 1. Weight average molecular weight and polydispersity index

[0206] The weight-average molecular weight (Mw) was measured using GPC (Gel permeation chromatography). Specifically, the weight-average molecular weight (Mw) can be measured by placing the sample to be analyzed in a 5 mL vial, diluting it with THF (tetrahydrofuran) to a concentration of approximately 1 mg / mL, and then filtering the calibration standard sample and the analysis sample through a syringe filter (pore size: 0.45 μm). Agilent Technologies' ChemStation was used as the analysis program, and the weight-average molecular weight (Mw) can be obtained by comparing the elution time of the sample with the calibration curve. The number-average molecular weight (Mn) can also be measured in the same way, and the polydispersity index (PDI) is the value obtained by dividing the measured weight-average molecular weight (MW) by the number-average molecular weight (Mn) (MW / Mn).

[0207] <GPC 측정 조건>

[0208] Device: Agilent Technologies 1200 series

[0209] Column: Using TL Mix. A & B from Agilent Technologies

[0210] Solvent: THF (tetrahydrofuran)

[0211] Column temperature: 35℃

[0212] Sample concentration: 1 mg / mL, 200 μl injection

[0213] Standard sample: Polystyrene (MP: 3900000, 723000, 316500, 52200, 31400, 7200, 3940, 485) used

[0214] 2. Average particle size

[0215] The average particle size is the D50 particle size of the measurement target, which is the particle size measured using Marvern's MASTERSIZER3000 equipment in accordance with the ISO-13320 standard. Distilled water was used as the solvent during the measurement. The incident laser is scattered by the measurement target dispersed in the solvent, and the intensity and directionality of the scattered laser vary depending on the size of the measurement target. By analyzing this using Mie theory, the D50 particle size can be obtained. Through the above analysis, the distribution is obtained by converting it into the diameter of a sphere with the same volume as the dispersed measurement target, and the D50 value, which is the median value of the distribution, can be obtained to evaluate the particle size.

[0216] 3. Glass transition temperature

[0217] The glass transition temperature was measured using a conventional Differential Scanning Calorimeter (DSC) device. The DSC-STAR3 device (Mettler Toledo) was used. Approximately 10 mg of the sample was sealed in a dedicated pen, and the glass transition temperature was measured by checking the heat absorption and exotherm according to the temperature at a heating rate of 10°C / min.

[0218] 4. Energy density per volume

[0219] The energy density per volume was calculated by dividing the energy of the battery cell by the volume of the battery cell. Specifically, the volume of the battery cell relative to the area occupied by the electrolyte in the battery cell was used as the volume of the battery cell at the energy density per volume. In addition, the energy of the battery cell was calculated by multiplying the capacity and the average discharge voltage.

[0220] 5. Electrode swelling evaluation

[0221] Electrode swelling evaluation was performed based on the electrode thickness of the initially manufactured battery cell and the electrode thickness of the fully charged battery cell. The electrode thickness of the fully charged battery cell was determined by disassembling the fully charged battery cell.

[0222] Specifically, electrode swelling was evaluated according to the following criteria.

[0223] [metewand]

[0224] PASS: Ts according to Equation 1 below is 30% or less

[0225] NG: Ts according to Equation 1 below is greater than 30%

[0226] [Formula 1]

[0227] T S = (T2-T1) / T1Х 100 (%)

[0228] In Equation 1, T1 refers to the thickness of the electrode of the initially manufactured battery cell, and T2 refers to the thickness of the electrode after the battery cell is charged to SOC (state of charge) 100 under the conditions of 0.2 CC / CV charge, 4.2 V, 0.05C cut-off.

[0229] 6. Rapid life capacity retention rate

[0230] The rapid life capacity retention rate is L according to Equation 2 R It was derived as follows.

[0231] [Formula 2]

[0232] L R = L2 / L1Х 100 (%)

[0233] In Equation 2, L1 is the discharge capacity of the battery cell in 1 cycle under the condition that 25°C is maintained, and L2 is the discharge capacity of the battery cell in 300 cycles under the condition that 25°C is maintained.

[0234] In addition, one cycle in the above is defined as charging at 2.0 C c-rate in the SOC 8 to 50 range, charging at 0.5 C c-rate to SOC 80, and then discharging at 1 / 3 C c-rate to charge and discharge at DOD72 (SOC 8 to 80).

[0235] 7. Evaluation of electrode wrinkle phenomenon

[0236] The electrode wrinkle phenomenon evaluation was performed based on the electrode of a battery cell after full charging. The initially manufactured battery cell was charged to a state of charge (SOC) of 100 under the conditions of 0.2 CC / CV charging at 4.2 V with a 0.05 C cut-off. The cell was then disassembled and the surface condition of the electrode was visually evaluated according to the following criteria.

[0237] [metewand]

[0238] PASS: No wrinkles observed on the surface of the electrode

[0239] NG: Wrinkles observed on the surface of the electrode

[0240] 8. Adhesion

[0241] (1) Adhesion between copper foil and the first active material layer

[0242] The adhesive strength between the copper foil and the first active material layer was measured as follows. The adhesive strength was measured by applying the first slurry composition forming the first active material layer on the copper foil, drying it at 80°C, and rolling it at 25°C to manufacture an electrode. Thereafter, the electrode was cut into pieces measuring 2.5 cm in width and 15 cm in length to manufacture a measurement sample. Thereafter, the first active material layer (210) of the measurement sample was attached so as to be in contact with a release film made of PET (polyethylene terephthalate). Thereafter, the peeling force measured when the current collector (100) and the first active material layer (210) were completely peeled off at a peeling speed of about 0.5 mm / min and a peeling angle of about 90 degrees using the release film was evaluated as the adhesive strength. At this time, the measurement of the adhesive strength was performed at 25°C.

[0243] (2) Adhesion between the first active material layer and the second active material layer

[0244] The adhesive strength between the first active material layer and the second active material layer was measured as follows. The first slurry composition forming the first active material layer was applied onto a current collector, and the second slurry composition forming the second active material layer was additionally applied onto the first slurry composition, dried at 80°C, and rolled at 25°C to manufacture an electrode. Thereafter, the electrode was cut into pieces measuring 2.5 cm in width and 15 cm in length to manufacture a measurement sample. Thereafter, the second active material layer of the measurement sample was attached so as to be in contact with a release film made of PET (polyethylene terephthalate). Thereafter, the peeling force measured when the first active material layer and the second active material layer were completely peeled off with the release film at a peeling speed of about 0.5 mm / min and a peeling angle of about 90 degrees was evaluated as the adhesive strength. At this time, the measurement of the adhesive strength was performed at 25°C.

[0245] Manufacturing example 1.

[0246] After mixing the active material mixture (A), the first binder (B), and the conductive material (SWCNT, C) in a weight ratio of 97.05:2.6:0.25 (A:B:C), deionized water as a solvent was added so that the solid content in the first slurry composition was about 42 wt% based on the total weight, thereby preparing a first slurry composition.

[0247] The above active material mixture (A) was used by mixing a carbon-based active material (A1) having an average particle size of about 10 ㎛ to 35 ㎛ and a silicon-based active material (A2) having an average particle size of about 1 ㎛ to 25 ㎛ in a weight ratio of 80.05:17 (A1:A2). Artificial graphite was used as the carbon-based active material (A1), and SiO was used as the silicon-based active material (A2). x (Here, x is 0.01 or more and less than 2) was used.

[0248] Poly(acrylic acid) (PAA) was used as the first binder (B). The poly(acrylic acid) (PAA) used had a weight average molecular weight (MW) of about 70,000 g / mol and a polydispersity index (PDI) of about 1 to 1.5. In addition, the poly(acrylic acid) used had a glass transition temperature (Tg1) of about 113°C to 115°C.

[0249] Manufacturing example 2.

[0250] After mixing the active material mixture (A), the second binder (B), the conductive agent (SWCNT, C), and the thickener (D) in a weight ratio of 96.05:1.5:0.25:3 (A:B:C:D), deionized water as a solvent was added so that the solid content in the second slurry composition was about 42 wt% based on the total weight, thereby preparing a second slurry composition.

[0251] The above active material mixture (A) was used by mixing a carbon-based active material (A1) having an average particle size of about 10 ㎛ to 35 ㎛ and a silicon-based active material (A2) having an average particle size of about 1 ㎛ to 25 ㎛ in a weight ratio of 79.05:17 (A1:A2). Artificial graphite was used as the carbon-based active material (A1), and SiO was used as the silicon-based active material (A2). x (Here, x is 0.01 or more and less than 2) was used.

[0252] Styrene butadiene rubber (SBR) was used as the second binder (B). In addition, carboxymethyl cellulose (CMC) was used as the thickener (D). The styrene butadiene rubber (SBR) used was a polymer containing a unit represented by the following chemical formula A.

[0253] [Chemical Formula A]

[0254]

[0255] In the above chemical formula A, the ratio of n and m (n / m) was about 2 to 3.

[0256] The styrene butadiene rubber used above had a weight average molecular weight (Mw) of about 40,000 g / mol and a polydispersity index (PDI) of about 4 or less. In addition, the styrene butadiene rubber (SBR) had a glass transition temperature (Tg2) of about -55°C.

[0257] The carboxymethyl cellulose (CMC) used above had a weight average molecular weight (MW) of approximately 200,000 g / mol and a polydispersity index (PDI) of approximately 12 to 25.

[0258] Example 1.

[0259] The first slurry composition prepared in Manufacturing Example 1 was applied onto a copper foil having a thickness of about 8 ㎛, and the second slurry composition prepared in Manufacturing Example 2 was additionally applied onto the applied first slurry composition. The first slurry composition (H1) and the second slurry composition (H2) were applied so that the thickness after drying was in a ratio of about 6:4 (H1:H2) and the total thickness after drying (H1+H2) was about 116 ㎛.

[0260] The copper foil coated with the first and second slurry compositions was vacuum dried at 80° C. and then rolled to manufacture a negative electrode including a first active material layer and a second active material layer.

[0261] Here, the adhesive force between the copper foil and the first active material layer was approximately 0.29 N, and the adhesive force between the first active material layer and the second active material layer was approximately 0.34 N.

[0262] An electrode assembly was manufactured by interposing a separator made of polyethylene (PE) with a thickness of about 15 μm between the cathode and anode manufactured above. The cathode (counter electrode) was manufactured by applying a cathode slurry composition on an aluminum foil with a thickness of about 12 μm, drying, and rolling. The cathode slurry composition contained LiNi as the cathode active material (A). 0.88 Co 0.06 Mn 0.06 O2, polyvinylidene fluoride (PVdF) as a binder (B) and carbon as a conductive material (C) were mixed in a weight ratio of 98:1:1 (A:B:C) and dispersed in an appropriate amount of N-methyl-2-pyrrolidone to produce a composite.

[0263] The electrode assembly manufactured above was placed in a pouch measuring approximately 5 mm in thickness, 50 mm in width, and 60 mm in length, and a non-aqueous electrolyte was injected and the pouch was sealed to manufacture a battery cell. The non-aqueous electrolyte was manufactured by adding LiPF6 at a concentration of 1 M to a non-aqueous electrolyte solvent containing ethylene carbonate (EC) and ethyl methyl carbonate (EMC) mixed in a volume ratio of 25:75.

[0264] Comparative Example 1.

[0265] The first slurry composition (H1) and the second slurry composition (H2) were applied so that the thickness after drying was in a ratio of about 5:5 (H1:H2), and a negative electrode and a battery cell were manufactured in the same manner as in Example 1.

[0266] Comparative Example 2.

[0267] The first slurry composition (H1) and the second slurry composition (H2) were applied so that the thickness after drying was in a ratio of about 4:6 (H1:H2), and a negative electrode and a battery cell were manufactured in the same manner as in Example 1.

[0268] Comparative Example 3.

[0269] The first slurry composition prepared in Manufacturing Example 1 was applied onto a copper foil having a thickness of approximately 8 ㎛, and then dried to a total thickness of approximately 105 ㎛. Thereafter, the copper foil on which the first slurry composition was applied was vacuum-dried at 80° C. and then rolled to prepare a negative electrode.

[0270] Additionally, a battery cell was manufactured using the negative electrode manufactured above in the same manner as in Example 1.

[0271] Comparative Example 4.

[0272] The second slurry composition prepared in Manufacturing Example 2 was applied onto copper foil having a thickness of approximately 8 μm, and then dried to a total thickness of approximately 110 μm. Thereafter, the copper foil on which the second slurry composition was applied was vacuum-dried at 80°C and then rolled to produce a negative electrode.

[0273] Additionally, a battery cell was manufactured using the negative electrode manufactured above in the same manner as in Example 1.

[0274] Comparative Example 5.

[0275] The second slurry composition prepared in Manufacturing Example 2 was applied onto a copper foil having a thickness of about 8 ㎛, and the first slurry composition prepared in Manufacturing Example 1 was additionally applied onto the applied second slurry composition. The second slurry composition (H2) and the first slurry composition (H1) were applied so that the thickness after drying was in a ratio of about 6:4 (H2:H1) and the total thickness after drying (H1+H2) was about 116 ㎛.

[0276] The copper foil coated with the first and second slurry compositions was vacuum dried at 80°C and then rolled to manufacture a cathode.

[0277] Additionally, a battery cell was manufactured using the negative electrode manufactured above in the same manner as in Example 1.

[0278] The evaluation results for the negative electrode or battery cell manufactured in Example 1 and Comparative Examples 1 to 5 are summarized in Table 1 below. In Table 1 below, the electrode swelling evaluation and electrode wrinkle phenomenon evaluation were performed on the negative electrode. In addition, the values ​​in the electrode swelling evaluation in Table 1 below are T according to the above [Equation 1]. s The value means, and the numerical value in the rapid life capacity retention rate is L according to the above [Formula 2] R It means value.

[0279] The evaluation results of the rapid life capacity retention for the battery cells manufactured in Example 1 and Comparative Examples 1 to 5 are shown in Fig. 4 (the number of cycles indicates the number of cycles). In addition, the electrode surfaces for the battery cells manufactured in Example 1 and Comparative Example 1 are shown in Fig. 5 ((a): Example 1, (b): Comparative Example 1).

[0280] Energy density per unit volume (Wh / L) Electrode swelling evaluation Rapid life capacity retention (@300 cycle) Electrode wrinkle phenomenon evaluation Example 1761 PASS (28.6%) 89.0% PASS Comparative example 1756 NG (31.5%) 86.7% NG Comparative example 2752 NG (33.0%) 71.6% NG Comparative example 3744 NG (34.1%) 75.5% NG Comparative example 4739 NG (32.8%) 78.6% PASS Comparative example 5762 NG (32.5%) 80.9% PASS

[0281] The present disclosure can provide an electrode that prevents wrinkles and swelling and exhibits excellent capacity retention and energy density. Furthermore, the present disclosure can provide a battery cell, a battery module, and a battery pack comprising the electrode, and an electrical device comprising at least one of the battery cell, battery module, and battery pack.

Claims

1. Including a current collector and an active material layer positioned on at least one surface of the current collector, The active material layer includes a first active material layer in contact with the current collector and including a first binder, and a second active material layer positioned on the first active material layer and including a second binder, The glass transition temperature (Tg1) of the first binder is greater than the glass transition temperature (Tg2) of the second binder, An electrode in which the ratio (H1 / H2) of the thickness (H1) of the first active material layer and the thickness (H2) of the second active material layer is greater than 1.

2. In paragraph 1, An electrode wherein the glass transition temperature (Tg1) of the first binder is 50°C to 300°C, and the glass transition temperature (Tg2) of the second binder is -100°C to 10°C.

3. In paragraph 1, An electrode wherein the weight average molecular weight (Mw) of the first binder is 10,000 g / mol to 200,000 g / mol, and the weight average molecular weight (Mw) of the second binder is 5,000 g / mol to 500,000 g / mol.

4. In paragraph 1, An electrode comprising a first binder and a polymer containing polar functional groups.

5. In paragraph 1, The first binder is an electrode comprising an acrylic polymer.

6. In paragraph 1, The second binder comprises a polymer comprising first repeating units and second repeating units, The above first repeating unit comprises a carbon-carbon multiple bond, An electrode comprising the second repeating unit as an aromatic group.

7. In paragraph 6, An electrode in which the ratio (N1 / N2) of the mole number of the first repeating unit (N1) to the mole number of the second repeating unit (N2) in the polymer is 1 to 5.

8. In paragraph 6, An electrode wherein the second active material layer additionally comprises a cellulose polymer.

9. In paragraph 8, An electrode in which the weight ratio (P1 / P2) of the polymer (P1) including the first repeating unit and the second repeating unit and the cellulose polymer (P2) in the second active material layer is 0.1 to 1.

10. In paragraph 1, The first active material layer comprises a first binder in an amount of 1 wt% to 5 wt% based on the total weight, An electrode in which the second active material layer comprises a second binder in an amount of 3 to 6 wt% relative to the total weight.

11. In paragraph 1, An electrode wherein the first active material layer and the second active material layer each independently include a carbon-based active material and a silicon-based active material.

12. In paragraph 11, In the first active material layer, the weight ratio (C1 / Si1) of the carbon-based active material (C1) and the silicon-based active material (Si1) is 1 to 10, An electrode in which the weight ratio (C2 / Si2) of carbon-based active material (C2) and silicon-based active material (Si2) in the second active material layer is 1 to 10.

13. In paragraph 11, The first active material layer has a ratio (DC1 / DSi1) of the average particle size (DC1) of the carbon-based active material and the average particle size (DSi1) of the silicon-based active material of 1 to 20, The second active material layer is an electrode in which the ratio (DC2 / DSi2) of the average particle size of the carbon-based active material (DC2) to the average particle size of the silicon-based active material (DSi2) is 1 to 20.

14. In paragraph 11, The first active material layer contains 1,000 to 10,000 parts by weight of a carbon-based active material relative to 100 parts by weight of the first binder, An electrode in which the second active material layer comprises 500 to 5,000 parts by weight of a carbon-based active material relative to 100 parts by weight of the second binder.

15. In paragraph 1, An electrode in which the difference between the glass transition temperature (Tg1) of the first binder and the glass transition temperature (Tg2) of the second binder is 50°C or more.

16. Including a positive electrode, a negative electrode, and a separator interposed between the positive electrode and the negative electrode, The above negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on at least one surface of the negative electrode current collector, The negative electrode active material layer includes a first negative electrode active material layer in contact with the negative electrode current collector and including a first binder, and a second negative electrode active material layer positioned on the first negative electrode active material layer and including a second binder, The glass transition temperature (Tg1) of the first binder is greater than the glass transition temperature (Tg2) of the second binder, A battery cell in which the ratio (H1 / H2) of the thickness (H1) of the first negative electrode active material layer and the thickness (H2) of the second negative electrode active material layer is greater than 1.

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