Binder for negative electrode of rechargeable lithium battery and rechargeable lithium battery including the same

Abstract

Disclosed are a binder for a negative electrode of a rechargeable lithium battery and a rechargeable lithium battery including the binder. The binder for the negative electrode includes: a unit derived from a first monomer; and a unit derived from a (meth) acrylic monomer as a second monomer. The first monomer includes at least one of a (meth) allyl ether monomer and a (meth) acrylate monomer, and the (meth) allyl ether monomer and the (meth) acrylate monomer each include an alkyl group having a carbon number of 3 or more and an anionic functional group.

Description

[0001] This application claims priority to and the benefit of Korean Patent Application No. 10-2023-0133090 filed in the Korean Intellectual Property Office on October 6, 2023, the disclosure of which is incorporated herein in its entirety by reference. Technical Field

[0002] The present disclosure relates to a binder for a negative electrode of a rechargeable lithium battery, a negative electrode for a rechargeable lithium battery including the binder, and a rechargeable lithium battery including the negative electrode. Background Art

[0003] In recent years, with the rapid popularization of electronic devices using batteries (such as mobile phones, notebook computers and electric vehicles), the demand for secondary batteries with high energy density and high capacity has grown rapidly. In particular, rechargeable lithium batteries have attracted much attention as a power source for mobile devices due to their light weight and high energy density.

[0004] A rechargeable lithium battery includes positive and negative electrodes and an electrolyte, each of the positive and negative electrodes contains an active material that allows (e.g., is capable of) intercalating and deintercalating lithium ions, and generates electricity through a redox reaction when lithium ions are intercalated / deintercalated at the positive and negative electrodes.

[0005] The positive electrode active material for a rechargeable lithium battery may include one or more transition metal compounds such as lithium cobalt oxide, lithium nickel oxide, lithium manganese oxide, etc. The negative electrode active material may include one or more crystalline carbon materials (such as natural graphite, artificial graphite) and / or amorphous carbon materials.

[0006] As part (e.g., a significant part) of efforts to improve the performance of such rechargeable lithium batteries, single cells (battery cells) capable of rapid charging have been actively developed. Typically, rapid charging reduces single cell capacity by shortening the life of the single cell. It is desirable to have a reliable (e.g., fixed), low shrinkage, low expansion, no cracking, and low warping negative electrode having a silicon-based negative electrode active material. Summary of the invention

[0007] Aspects according to some embodiments relate to a binder for a negative electrode of a rechargeable lithium battery that reduces shrinkage and expansion of a silicon-based negative electrode active material, prevents or reduces negative electrode embrittlement, and improves negative electrode energy density.

[0008] Aspects according to some embodiments relate to a binder for a negative electrode of a rechargeable lithium battery that does not generate cracks in a negative electrode including a silicon-based negative electrode active material while reducing a warpage value of the negative electrode including the silicon-based negative electrode active material.

[0009] Aspects according to some embodiments relate to a rechargeable lithium battery including a negative electrode for a rechargeable lithium battery including the negative electrode binder.

[0010] Additional aspects will be set forth in part in the description which follows and, in part, will be obvious from the description, or may be learned by practice of the disclosed presented embodiments.

[0011] According to one or more embodiments of the present disclosure, a binder for a negative electrode of a rechargeable lithium battery includes: a unit derived from a first monomer; and a unit derived from a second monomer, the second monomer being a (meth)acrylic monomer, wherein the first monomer includes at least one of a (meth)allyl ether monomer and a (meth)acrylate monomer, and the (meth)allyl ether monomer and the (meth)acrylate monomer each include an alkyl group having a carbon number of 3 or more and an anionic functional group.

[0012] According to one or more embodiments of the present disclosure, a rechargeable lithium battery includes: a negative electrode including the binder; a positive electrode; and an electrolyte.

[0013] Embodiments of the present disclosure provide a binder for a negative electrode of a rechargeable lithium battery that reduces shrinkage and expansion of a silicon-based negative electrode active material, prevents or reduces embrittlement of the negative electrode, and improves energy density.

[0014] Embodiments of the present disclosure provide a binder for a negative electrode of a rechargeable lithium battery, which does not generate cracks in a negative electrode including a silicon-based negative electrode active material while reducing a warpage value of the negative electrode including the silicon-based negative electrode active material. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] The accompanying drawings are included to provide a further understanding of the present disclosure, and are incorporated in and constitute a part of this specification. The accompanying drawings illustrate embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure. In the drawings:

[0016] Figure 1 is a diagram schematically illustrating a rechargeable lithium battery according to one or more embodiments of the present disclosure.

[0017] Figure 2 is a schematic cross-sectional view of a prismatic battery according to one or more embodiments of the present disclosure.

[0018] Figure 3 is a schematic diagram of a pouch-type battery according to one or more embodiments of the present disclosure.

[0019] Figure 4 is a schematic diagram of a pouch-type battery according to one or more embodiments of the present disclosure. DETAILED DESCRIPTION

[0020] Hereinafter, exemplary embodiments of the present disclosure will be described in more detail with reference to the accompanying drawings. However, it should be understood that the following embodiments are provided by way of illustration and the present disclosure is not limited thereto and is only defined by the appended claims and their equivalents.

[0021] The terms used herein are for the purpose of describing the embodiments of the present disclosure and are not intended to limit the present disclosure. Throughout the specification, unless otherwise specified, each element may be singular or plural.

[0022] Herein, "combinations thereof" may refer to mixtures, stacks, composites, copolymers, alloys, blends, and reaction products of the components.

[0023] It will also be understood that when the terms "comprises," "includes," and / or variations thereof are used in this specification, it indicates the presence of stated features, integers, steps, operations, elements, and / or components, but does not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof.

[0024] In the drawings, the thickness of various elements, layers, regions, etc. may be exaggerated for clarity of illustration, and the same elements are denoted by the same reference numerals throughout the specification. In addition, when any element is referred to as being disposed (or located or positioned) "above" (or "below") or "on" (or "below") a component, it may mean that the arbitrary element is placed in contact with the upper (or lower) surface of the component, and it may also mean that another component may be placed between the component and the arbitrary element disposed (or located or positioned) on (or below) the component.

[0025] Here, the term "layer" refers not only to a feature formed on the entire surface in a plan view but also to a feature formed on a portion of the surface in a plan view.

[0026] Here, "average particle size" can be measured by any suitable method (e.g., known to those skilled in the art) (e.g., by a particle size analyzer, transmission electron micrographs, or scanning electron micrographs). Alternatively, the average particle size can be measured by counting the number of particles in each particle size range using a device that analyzes the data using a dynamic light scattering method, and then calculating the average particle size based on the analyzed data. The average particle size can be measured from a microscopic image or with a particle size analyzer, and can be defined as the diameter of particles having a cumulative volume of 50% by volume in a particle size distribution (D 50 ).

[0027] Here, the term "or" should not be interpreted as exclusive. For example, "A or B" should be interpreted as including A, B, A+B, etc.

[0028] Herein, the term "(meth)acrylic acid" refers to acrylic acid and / or methacrylic acid.

[0029] Expressions such as “at least one of” and “any of” when following a list of elements modify the entire list of elements and do not modify the individual elements in the list. When phrases such as “at least one of A, B, and C,” “at least one of A, B, or C,” “at least one selected from the group of A, B, and C,” or “at least one selected from A, B, and C,” are used to designate a list of elements A, B, and C, the phrase may refer to any and all suitable combinations or subsets of A, B, and C, such as A, B, C, A and B, A and C, B and C, or A and B and C. As used herein, the term “using” and variations thereof may be considered synonymous with the term “utilizing” and variations thereof, respectively.

[0030] It will be understood that, although the terms "first", "second", "third", etc. may be used herein to describe various elements, components, regions, layers and / or parts, these elements, components, regions, layers and / or parts should not be limited by these terms. These terms are used to distinguish one element, component, region, layer or part from another element, component, region, layer or part. Therefore, without departing from the teachings of the exemplary embodiments, the first element, first component, first region, first layer or first part discussed below may be referred to as a second element, second component, second region, second layer or second part.

[0031] Hereinafter, embodiments of the present disclosure will be described in more detail. However, it should be understood that the following embodiments are provided by way of illustration only, and the present disclosure is limited only by the appended claims and their equivalents.

[0032] Binders for negative electrodes of rechargeable lithium batteries

[0033] According to some embodiments, a binder for a negative electrode of a rechargeable lithium battery includes: a unit derived from a first monomer; and a unit derived from a (meth)acrylic monomer as a second monomer, wherein the first monomer includes at least one of a (meth)allyl ether monomer and a (meth)acrylate monomer, and the (meth)allyl ether monomer and the (meth)acrylate monomer each contain an alkyl group having a carbon number of 3 or more and an anionic functional group.

[0034] In some embodiments, the negative electrode binder may be a copolymer of a monomer mixture including a (meth)acrylic monomer as the second monomer and at least one of a (meth)allyl ether monomer and a (meth)acrylate monomer as the first monomer.

[0035] Although the negative electrode binder prepared only from the second monomer may be able to suppress the shrinkage and expansion of the silicon-based negative electrode active material, such a negative electrode binder may make the negative electrode brittle. As a result, the negative electrode binder may cause the negative electrode to crack (e.g., severely crack) and increase the warpage value of the negative electrode during the process of manufacturing the negative electrode. The cracking and warpage values ​​may be exacerbated in the manufacture of a negative electrode having a large area. It is desirable that the negative electrode be crack-free and have a low warpage value to improve the reliability of the negative electrode and the rechargeable lithium battery.

[0036] Each of the (meth)allyl ether monomer and the (meth)acrylate monomer can be applied to the negative electrode binder to provide a negative electrode active material layer that does not cause the negative electrode to break and has a low warpage value without compromising the effect of reducing the shrinkage and expansion of the silicon-based negative electrode active material. That is, even when the (meth)allyl ether monomer and / or the (meth)acrylate monomer are included, there is no trade-off between the effect of reducing the shrinkage and expansion of the negative electrode containing the silicon-based negative electrode active material and the effect of reducing the rupture and warpage value of the negative electrode.

[0037] In some embodiments, the first monomer and the second monomer may be present in the monomer mixture in a total amount of 99.5 wt % or more, for example, 99.5 wt % to 100 wt %, or 100 wt %. Within these ranges, the effect of the negative electrode binder may be fully achieved.

[0038] First monomer

[0039] The (meth) allyl ether monomer and the (meth) acrylate monomer each contain an alkyl group having 3 or more carbon atoms and an anionic functional group. The alkyl group having 3 or more carbon atoms and an anionic functional group can prevent or reduce the embrittlement of the negative electrode and can reduce the cracking of the negative electrode. It is believed that the (meth) allyl ether monomer and the (meth) acrylate monomer can prevent or reduce the embrittlement of the negative electrode while inhibiting the cracking of the negative electrode by providing a repulsive force between the binders.

[0040] In some embodiments, the anionic functional group refers to a functional group capable of exhibiting a negative charge in an aqueous solvent, and may include, for example, sulfur (S) or phosphorus (P). The anionic functional group may be a monovalent anion or a multivalent anion functional group.

[0041] In some embodiments, the anionic functional group can be a sulfonic acid group (-SO3H) or an anion of a sulfonic acid group (-SO3 - ), phosphonic acid group (-PO(OH)2) or the anion of phosphonic acid group (-PO(OH)O - ) or (-PO3 2- ), phosphinate (-P(O)H(OH)) or the anion of phosphinate (-P(O)HO- ) etc. For example, the anionic functional group may be a sulfonic acid group or an anion of a sulfonic acid group.

[0042] Here, in the "alkyl group having 3 or more carbon atoms", the carbon number refers to the number of carbon atoms constituting the main chain of the ester part or the ether part in the corresponding monomer. For example, the carbon number may be in the range of 3 to 20.

[0043] In some embodiments, the (meth)allyl ether monomer having an anionic functional group and the (meth)acrylate monomer having an anionic functional group may be represented by Formula 1:

[0044] Formula 1

[0045]

[0046] Wherein, R1 is hydrogen or methyl;

[0047] R2 is CH2 or C=O;

[0048] R3 is a substituted or unsubstituted alkylene group having 3 or more carbon atoms, a substituted or unsubstituted iminoalkyl group having 3 or more carbon atoms or an ammonium cation group thereof, or a substituted or unsubstituted alkylamino group having 3 or more carbon atoms or an ammonium cation group thereof; and

[0049] X is an anionic functional group.

[0050] As used herein, "substituted" means that at least one hydrogen atom of the corresponding functional group is replaced by a hydroxyl (OH) group or a C1 to C 10 Alkyl substitution.

[0051] In Formula 1, the "iminoalkyl group having a carbon number of 3 or more" may be a functional group represented by Formula 2:

[0052] Formula 2

[0053] *-R 31 -N(R 32 )-R 33 -*,

[0054] Among them, * is the attachment site of the element;

[0055] R 31 and R 33 are each independently substituted or unsubstituted C1 to C 10 Alkylene;

[0056] R 32 is hydrogen or substituted or unsubstituted C1 to C 10 Alkyl; and

[0057] R 31 and R33 The total number of carbons in the alkylene group is 3 or more.

[0058] In Formula 1, the “alkylamino group having a carbon number of 3 or more” may be a functional group represented by Formula 3:

[0059] Formula 3

[0060] *-N(R 34 )-R 35 -*,

[0061] Among them, * is the attachment site of the element;

[0062] R 34 is hydrogen or substituted or unsubstituted C1 to C 10 Alkyl; and

[0063] R 35 It is a substituted or unsubstituted alkylene group having 3 or more carbon atoms.

[0064] In some embodiments, R3 in Formula 1 may be a substituted or unsubstituted alkylene group having 3 or more carbon atoms, for example, a substituted or unsubstituted alkylene group having 3 to 10 carbon atoms.

[0065] In some embodiments, R3 in Formula 1 may be a substituted or unsubstituted imidoalkyl group having 3 or more carbon atoms or an ammonium cation group thereof, for example, a substituted or unsubstituted imidoalkyl group having 3 to 10 carbon atoms or an ammonium cation group thereof.

[0066] In some embodiments, R3 in Formula 1 may be a substituted or unsubstituted alkylamino group having 3 or more carbon atoms or an ammonium cation group thereof, for example, a substituted or unsubstituted alkylamino group having 3 to 10 carbon atoms or an ammonium cation group thereof.

[0067] In Formula 1, "ammonium cation group thereof" refers to a cation group in which hydrogen or C1 to C 10 The alkyl group is attached to the nitrogen of the corresponding amino group to represent a monovalent cationic functional group.

[0068] For example, the monomer (eg, the first monomer) may include at least one compound selected from among the compounds represented by Formula 1-1, Formula 1-2, and Formula 1-3:

[0069] Formula 1-1

[0070]

[0071] Formula 1-2

[0072]

[0073] Formula 1-3

[0074]

[0075] In some embodiments, at least one of the (meth)allyl ether monomer and the (meth)acrylate monomer may be present in the monomer mixture in an amount of 3 wt % to 15 wt %. In an embodiment, at least one of the (meth)allyl ether monomer and the (meth)acrylate monomer may be present in the monomer mixture in an amount of 5 wt % to 10 wt %. Within these ranges, the negative electrode binder can ensure coating processability by reducing the warpage of the negative electrode without compromising the effect of reducing the shrinkage and expansion of the silicon-based active material of the negative electrode binder.

[0076] In some embodiments, the first monomer may be present in the monomer mixture in an amount of 3 wt % to 15 wt %. In an embodiment, the first monomer is present in the monomer mixture in an amount of 5 wt % to 10 wt %. Within these ranges, the negative electrode binder can ensure coating processability by reducing the warpage of the negative electrode without compromising the effect of reducing the shrinkage and expansion of the silicon-based active material of the negative electrode binder.

[0077] In some embodiments, the negative electrode binder may further include a unit derived from a (meth) acrylamide monomer having an anionic functional group as a first monomer or a unit derived from a (meth) acrylamide monomer having an anionic functional group in addition to the first monomer. That is, the first monomer may include a (meth) acrylamide monomer having an anionic functional group and at least one of a (meth) allyl ether monomer and a (meth) acrylate monomer.

[0078] In some embodiments, the negative electrode binder can be a copolymer of a monomer mixture, the monomer mixture including at least one of a (meth)allyl ether monomer and a (meth)acrylate monomer as a first monomer; a (meth)acrylamide monomer having an anionic functional group; and a (meth)acrylic monomer as a second monomer.

[0079] A (meth)acrylamide monomer having an anionic functional group may be further included in the negative electrode binder to further reduce the expansion rate of the negative electrode active material layer or the negative electrode.

[0080] The anionic functional group (e.g., the anionic functional group of the (meth)acrylamide monomer) may include an anionic functional group containing sulfur (S) or phosphorus (P). The anionic functional group may be a sulfonic acid group (—SO3H) or an anion of a sulfonic acid group (—SO3 - ), phosphonic acid group (-PO(OH)2) or the anion of phosphonic acid group (-PO(OH)O - ) or (-PO3 2-), phosphinate (-P(O)H(OH)) or the anion of phosphinate (-P(O)HO - ) etc. For example, the anionic functional group may be a sulfonic acid group or an anion thereof.

[0081] In some embodiments, the monomer (eg, a (meth)acrylamide monomer having an anionic functional group) may be represented by Formula 4:

[0082] Formula 4:

[0083]

[0084] Wherein, R1 is hydrogen or methyl;

[0085] R2 is a substituted or unsubstituted alkylene group having 1 or more carbon atoms;

[0086] R3 is hydrogen or a substituted or unsubstituted C1 to C 10 Alkyl; and

[0087] X is an anionic functional group.

[0088] In some embodiments, R2 may be a substituted or unsubstituted alkylene group having 3 or more carbon atoms, for example, a substituted or unsubstituted C1 to C 10 Alkylene.

[0089] For example, the monomer may include 2-(meth)acrylamide-2-methyl-1-propanesulfonic acid, and the like.

[0090] The (meth) acrylamide monomer having an anionic functional group may be present in the monomer mixture in an amount of 1wt% to 5wt%. Within this range, the binder for the negative electrode can further reduce the warping of the negative electrode without compromising the effect of further reducing the expansion of the negative electrode active material layer or the negative electrode, while suppressing cracking. For example, the monomer (e.g., the (meth) acrylamide monomer having an anionic functional group) may be present in the monomer mixture in an amount of 1wt% to 3wt%.

[0091] In some embodiments, the monomer mixture may include: 90 wt % to 95 wt % of a (meth)acrylic monomer as a second monomer; 1 wt % to 5 wt % of at least one of a (meth)allyl ether monomer having an anionic functional group and a (meth)acrylate monomer having an anionic functional group as a first monomer; and 1 wt % to 5 wt % of a (meth)acrylamide monomer having an anionic functional group.

[0092] Second monomer

[0093] As the second monomer, the (meth)acrylic monomer has a (meth)acrylic group and can facilitate the preparation of a negative electrode binder by polymerization with a monomer having an anionic functional group. The second monomer is different from the first monomer.

[0094] The (meth)acrylic monomer may include at least one of a (meth)acrylic monomer having a nitrile group and a (meth)acrylic monomer having a carboxylic acid group. For example, the (meth)acrylic monomer may include at least one of (meth)acrylonitrile and (meth)acrylic acid.

[0095] The (meth)acrylic monomer (i.e., the second monomer) may be present in the monomer mixture in an amount of 85 wt % to 97 wt %. In an embodiment, the (meth)acrylic monomer is present in the monomer mixture in an amount of 90 wt % to 95 wt %. Within these ranges, the binder may reduce the shrinkage and expansion of the silicon-based active material.

[0096] In some embodiments, the (meth) acrylic monomer having a nitrile group may be present in the monomer mixture in an amount of 30 wt % to 50 wt %. Within this range, the (meth) acrylic monomer may improve the dispersibility of the negative electrode active material. For example, the (meth) acrylic monomer (e.g., a (meth) acrylic monomer having a nitrile group) may be present in the monomer mixture in an amount of 35 wt % to 45 wt %.

[0097] In some embodiments, the (meth) acrylic monomer having a carboxylic acid group may be present in the monomer mixture in an amount of 40 wt % to 65 wt %. Within this range, the negative electrode binder may reduce the shrinkage and expansion of the silicon-based active material. For example, the (meth) acrylic monomer (e.g., a (meth) acrylic monomer having a carboxylic acid group) may be present in the monomer mixture in an amount of 50 wt % to 60 wt %.

[0098] The negative electrode binder may have a weight average molecular weight (MW) of 500,000 g / mol to 1,500,000 g / mol, for example, 800,000 g / mol to 1,000,000 g / mol. Within these ranges, the negative electrode binder may be included in the negative electrode active material layer to achieve the effects of the present disclosure described above. As used herein, the "weight average molecular weight" may be obtained by gel permeation chromatography using polystyrene standards.

[0099] The negative electrode binder may be an aqueous binder. Therefore, the negative electrode binder may be suitable for use in a negative electrode for a rechargeable lithium battery. Since the positive electrode active material may be vulnerable in an aqueous system, it may not be suitable to apply the negative electrode binder according to an embodiment of the present disclosure to a positive electrode.

[0100] The negative electrode binder according to some embodiments may be prepared by polymerizing a monomer mixture via any suitable method (eg, any suitable method known to those skilled in the art). The polymerization may be achieved by emulsion polymerization, suspension polymerization, solution polymerization, and the like.

[0101] In polymerization, the emulsifier may include one or more alkali metal salts of higher fatty acids, N-acryloyl amino acid salts, alkyl ether carbonates, acylated peptides, alkyl sulfonates, alkyl benzene sulfonates, alkyl amino acid salts, alkyl naphthalene sulfonates, sulfosuccinates, sulfonated oils, alkyl sulfates, alkyl ether sulfates, alkyl aryl ether sulfates, alkyl amide sulfates, alkyl phosphates, alkyl ether phosphates, alkyl aryl ether phosphates or combinations thereof. For example, the emulsifier may be sodium dodecylbenzene sulfonate. The alkyl group may be an alkyl group having 1 to 20 carbon atoms.

[0102] In the polymerization, the initiator may include ammonium persulfate, potassium persulfate, hydrogen peroxide, tert-butyl hydroperoxide, or a combination thereof.

[0103] Relative to 100 parts by weight of the monomer mixture, the emulsifier may optionally be present in an amount of 3 parts by weight or less, for example, 2 parts by weight or less. Within these ranges, the emulsifier may further improve adhesion and may ensure good dispersion to provide a binder having a suitable size.

[0104] The initiator may be present in an amount of 0.1 parts by weight to 3 parts by weight, for example, 0.1 parts by weight to 2 parts by weight, relative to 100 parts by weight of the monomer mixture.

[0105] Negative electrode for rechargeable lithium battery

[0106] A negative electrode for a rechargeable lithium battery according to some embodiments includes a negative electrode binder.

[0107] The negative electrode for a rechargeable lithium battery according to an embodiment includes a current collector and a negative electrode active material layer formed on the current collector. The negative electrode active material layer includes a negative electrode active material and a negative electrode binder, and may also include a conductive material. The negative electrode active material layer may also include a binder other than the negative electrode binder. For convenience, the negative electrode binder (negative electrode binder according to an embodiment of the present disclosure) will be referred to as a first binder, and a binder other than the negative electrode binder will be referred to as a second binder.

[0108] For example, the negative electrode active material layer may include 90 wt % to 99 wt % of the negative electrode active material, 0.5 wt % to 5 wt % of (one or more) binders, and 0 wt % to 5 wt %, 0.5 wt % to 5 wt % of the conductive material.

[0109] Negative electrode active material

[0110] The negative electrode active material includes a material that allows (is capable of) reversibly inserting / extracting lithium ions, lithium metal, a lithium metal alloy, a material that can be doped with and de-doped with lithium, or a transition metal oxide.

[0111] The material that allows reversibly inserting / extracting lithium ions may include a carbon-based negative electrode active material, for example, crystalline carbon, amorphous carbon, or a combination thereof. Crystalline carbon may include, for example, graphite, such as natural graphite and / or artificial graphite in an amorphous (e.g., irregular), plate-like, flake-like, spherical, or fibrous form, and amorphous carbon may include, for example, soft carbon, hard carbon, mesophase pitch carbide, calcined coke, etc.

[0112] As the lithium metal alloy, an alloy of lithium and a metal selected from among Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn can be used.

[0113] The material that can be doped with and de-doped with lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may be silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy (where Q is selected from alkali metals, alkaline earth metals, Group XIII elements, Group XIV elements (excluding Si), Group XV elements, Group XVI elements, transition metals, rare earth elements, and combinations thereof), or a combination thereof. The Sn-based negative electrode active material may be Sn, SnO x (0 < x ≤ 2, for example, SnO2), a Sn alloy, or a combination thereof.

[0114] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to some embodiments, the silicon-carbon composite may be prepared in the form of silicon particles having an amorphous carbon coating formed on their surface. For example, the silicon-carbon composite may include secondary particles (cores) composed of primary silicon particles and an amorphous carbon coating (shells) formed on the surfaces of the secondary particles. The amorphous carbon may also be placed between the primary silicon particles such that, for example, the primary silicon particles are coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0115] The silicon-carbon composite may also include crystalline carbon. For example, the silicon-carbon composite may include a core containing crystalline carbon and silicon particles and an amorphous carbon coating formed on the core (the surface of the core).

[0116] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with the carbon-based negative electrode active material.

[0117] In some embodiments, the negative electrode active material layer may include only a first binder as the binder.

[0118] In some embodiments, the negative electrode active material layer may include a mixture of a first binder and a second binder as a binder.

[0119] The second binder may be a non-aqueous binder, an aqueous binder, a dry binder, or a combination thereof.

[0120] The non-aqueous binder may be polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide or a combination thereof.

[0121] The aqueous binder can be selected from styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinyl pyrrolidone, polyepichlorohydrin, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinyl pyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acryloyl resin, phenol resin, epoxy resin, polyvinyl alcohol and combinations thereof.

[0122] When the aqueous binder is used as the negative electrode binder, a cellulose compound capable of imparting viscosity may be further included. The cellulose compound may be a mixture of two or more of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose and an alkali metal salt thereof. The alkali metal may be Na, K or Li.

[0123] The dry binder may be a fibrous polymer material and may be, for example, polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0124] The conductive material is used to impart conductivity to the electrode, and may be any suitable conductive material that does not cause chemical changes in the monomer under construction. For example, the conductive material may include: one or more carbon materials, such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metal-based materials in the form of metal powder or metal fiber containing copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives, etc.; or mixtures thereof. The negative electrode current collector may be selected from copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer matrix coated with a conductive metal, and combinations thereof.

[0125] Rechargeable lithium battery

[0126] The rechargeable lithium battery includes a negative electrode and a positive electrode. The rechargeable lithium battery may further include an electrolyte. The rechargeable lithium battery may further include a separator.

[0127] Positive electrode

[0128] The positive electrode may include a current collector and a positive electrode active material layer formed on the current collector. The positive electrode active material layer may include a positive electrode active material, and may further include a binder and / or a conductive material.

[0129] In some embodiments, the positive electrode may further include an additive that can function as a sacrificial positive electrode.

[0130] The positive electrode active material may be present in an amount of 90 to 99.5 wt % based on 100 wt % of the positive electrode active material layer, and the binder and the conductive material may each be present in an amount of 0.5 to 5 wt % based on 100 wt % of the positive electrode active material layer.

[0131] Positive electrode active material

[0132] As the positive electrode active material, a compound that allows (e.g., is capable of) reversibly inserting and extracting lithium (lithiated inserting compound) can be used. For example, the positive electrode active material can be at least one complex oxide (e.g., composite oxide) of lithium and a metal selected from cobalt, manganese, nickel, and a combination thereof.

[0133] The composite oxide may be a lithium transition metal composite oxide. For example, the composite oxide may be lithium nickel oxide, lithium cobalt oxide, lithium manganese oxide, lithium iron phosphate compound, lithium manganese oxide not containing cobalt, or a combination thereof.

[0134] For example, the composite oxide may be a compound represented by any of the following formulae: Li a A 1-b X b O 2-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni 1-b- c Mn b X c O 2-α D α(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, 0<α<2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0≤e≤0.1); Li a NeG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-b G b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn b O4(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn 1-g G g PO4(0.90≤a≤1.8, 0≤g≤0.5); Li (3-f) Fe2(PO4)3(0≤f≤2); and Li a FePO4(0.90≤a≤1.8).

[0135] In the above formula, A is Ni, Co, Mn or a combination thereof; X represents Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element or a combination thereof; D is O, F, S, P or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V or a combination thereof; and L 1 It is Mn, Al or a combination thereof.

[0136] In some embodiments, the positive electrode active material may be a high nickel content positive electrode active material, based on 100 mol% of the metal other than lithium in the lithium transition metal composite oxide, the high nickel content positive electrode active material includes 80 mol% or more, 85 mol% or more, 90 mol% or more, 91 mol% or more, or 94 mol% or more and 99 mol% or less of nickel. The high nickel content positive electrode active material can achieve high capacity and can therefore be applied to high capacity / high density rechargeable lithium batteries.

[0137] The binder is used to attach the positive electrode active material particles to each other and also to the current collector. The binder may include, for example, polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinyl pyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth) acrylated styrene-butadiene rubber, epoxy resin, (meth) acrylic resin, polyester resin, nylon, etc., without limitation thereto.

[0138] The conductive material is used to impart conductivity to the electrode, and may be any suitable conductive material that does not cause chemical changes in the monomer under the configuration. The conductive material may include, for example: one or more carbon materials, such as natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, carbon nanotube, etc.; metal-based materials in the form of metal powder or metal fiber containing copper, nickel, aluminum, silver, etc.; conductive polymers, such as polyphenylene derivatives, etc.; and mixtures thereof.

[0139] The current collector may be Al or the like, but is not limited thereto.

[0140] Electrolyte

[0141] The electrolyte includes a non-aqueous organic solvent and a lithium salt.

[0142] The nonaqueous organic solvent serves as a medium through which ions participating in the electrochemical reaction of the monomer can move.

[0143] The non-aqueous organic solvent may be a carbonate solvent, an ester solvent, an ether solvent, a ketone solvent, an alcohol solvent, a non-amphoteric solvent or a combination thereof.

[0144] The carbonate solvents may include dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), butylene carbonate (BC), and the like.

[0145] The ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonolactone, valerolactone, caprolactone, and the like.

[0146] Ether solvents may include dibutyl ether, tetraglyme, diglyme, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. In addition, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and non-amphoteric solvents may include: nitrile, such as R-CN (wherein R is a straight chain, branched or cyclic hydrocarbon group having 2 to 20 carbon atoms, and may include a double bond, an aromatic ring or an ether group); amides, such as dimethylformamide; dioxolanes, such as 1,3-dioxolanes, 1,4-dioxolanes, etc.; sulfolane; etc.

[0147] The nonaqueous organic solvent may be used alone or as a mixture thereof.

[0148] When the carbonate-based solvent is used, a mixture of a cyclic carbonate and a chain carbonate may be used, and the cyclic carbonate and the chain carbonate may be mixed in a volume ratio of 1:1 to 1:9.

[0149] Lithium salts are substances that are soluble in organic solvents and used as a source of lithium ions in batteries, enabling the basic operation of rechargeable lithium batteries while promoting the transfer (e.g., movement) of lithium ions between the positive electrode and the negative electrode. Lithium salts may include those selected from LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide (LiFSI)), LiC4F9SO3, LiN(C x F 2x+1 SO2)(C y F 2y+ 1SO2) (wherein x and y are integers of 1 to 20), at least one of lithium trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalato)phosphate (LiDFOB) and lithium bis(oxalato)borate (LiBOB).

[0150] Diaphragm

[0151] Depending on the type of rechargeable lithium battery, a separator may be placed between the positive electrode and the negative electrode. For such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or at least two layers thereof and a mixed layer (such as a polyethylene / polypropylene double-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, a polyethylene / polyethylene / polypropylene three-layer separator, etc.) may be used.

[0152] The separator may include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof on one or both surfaces of the porous substrate.

[0153] The porous substrate can be a polymer layer formed by a polymer selected from polyolefins (such as polyethylene, polypropylene, etc.), polyesters (such as polyethylene terephthalate, polybutylene terephthalate, etc.), polyacetals, polyamides, polyimides, polycarbonates, polyether ketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene ethers, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., Teflon), copolymers thereof, or mixtures thereof.

[0154] The organic material may include a polyvinylidene fluoride polymer or a (meth)acrylic polymer.

[0155] The inorganic material may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite and combinations thereof, without limitation thereto.

[0156] The organic material and the inorganic material may exist in a mixed state in one coating layer or may exist in the form of a stacked structure of a coating layer including an organic material and a coating layer including an inorganic material.

[0157] Rechargeable lithium batteries may be classified based on their shapes into cylindrical batteries, prismatic batteries, pouch-type or pouch-like batteries, coin-type or coin-like batteries, and the like. Figures 1 to 4 is a schematic diagram of a rechargeable lithium battery according to an embodiment of the present disclosure, wherein Figure 1 A cylindrical battery is shown, Figure 2 A prismatic cell is shown, and Figure 3 and Figure 4 A pouch type battery is shown. Figures 1 to 4 , the rechargeable lithium battery 100 may include an electrode assembly 40 in which a separator 30 is disposed between a positive electrode 10 and a negative electrode 20, and a case 50 receiving the electrode assembly 40 therein. The positive electrode 10, the negative electrode 20, and the separator 30 may be embedded in an electrolyte. Figure 1 As shown in , the rechargeable lithium battery 100 may include a sealing member 60 that seals the housing 50. In addition, as shown in Figure 2 As shown in , the rechargeable lithium battery 100 may include a positive electrode lead tab 11, a positive electrode terminal 12, a negative electrode lead tab 21, and a negative electrode terminal 22. Figure 3 and Figure 4 , the rechargeable lithium battery 100 may include electrode tabs 70 , ie, a positive electrode tab 71 and a negative electrode tab 72 , serving as an electrical path for conducting current generated in the electrode assembly 40 to the outside.

[0158] The rechargeable lithium battery according to an embodiment of the present disclosure may be applied to automobiles, mobile phones, and / or various other electrical devices, without being limited thereto.

[0159] Next, the present disclosure will be described in more detail with reference to examples. However, it should be understood that these examples are provided for illustration only and should not be interpreted as limiting the present disclosure in any way.

[0160] Example 1

[0161] A mixture was prepared by mixing 55 wt% of acrylic acid (AA), 40 wt% of acrylonitrile (AN) and 5 wt% of 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) based on 100 wt% of the mixture, and potassium persulfate initiator and water were added to the mixture. The initiator was used in an amount of 0.5 parts by weight relative to 100 parts by weight of the mixture.

[0162] Then, an aqueous binder solution including a copolymer (weight average molecular weight: 910,000 g / mol) having a unit derived from AA, a unit derived from AN, and a unit derived from AHPS was prepared by subjecting the prepared mixture to solution polymerization.

[0163] The negative electrode active material slurry is prepared by mixing a binder solution, styrene butadiene rubber, a conductive material and a negative electrode active material in water as a solvent. The negative electrode active material slurry contains 1.5wt% of an aqueous binder, 2.0wt% of styrene butadiene rubber, 0.5wt% of carbon nanotubes as a conductive material and 96wt% of a negative electrode active material in terms of solid content without water. As a negative electrode active material, a mixture of artificial / natural graphite and a silicon-carbon composite is used (mixing ratio: 90:10 by weight). The silicon-carbon composite is prepared in the form of a secondary particle aggregate prepared by aggregation of artificial graphite and silicon nanoparticles and including a soft carbon coating formed on the surface of the aggregate. In addition, the silicon-carbon composite consists of 40wt% of artificial graphite, 40wt% of silicon nanoparticles and 20wt% of soft carbon.

[0164] The negative electrode was prepared by applying a negative electrode active material slurry onto a copper foil as a current collector, followed by drying and rolling.

[0165] A full single cell is prepared using the prepared negative electrode, positive electrode and electrolyte in a suitable (e.g., typical) manner. The electrolyte is a solution of 1.5M LiPF6 dissolved in a mixture of ethylene carbonate, ethyl methyl carbonate and dimethyl carbonate (volume ratio, 30:50:20). A positive electrode active material slurry is prepared by mixing 96wt% LiCoO2, 2wt% Ketjen black and 2wt% polyvinylidene fluoride in a solvent (N-methylpyrrolidone), and the positive electrode active material slurry is applied to an aluminum current collector, followed by drying and rolling to form a positive electrode.

[0166] Example 2

[0167] A binder solution containing a copolymer (weight average molecular weight: 910,000 g / mol) was prepared in the same manner as in Example 1, except that a mixture of 55 wt% of acrylic acid (AA), 40 wt% of acrylonitrile (AN), and 5 wt% of 3-sulfopropyl acrylate (SPA) based on 100 wt% of the mixture was prepared. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0168] Example 3

[0169] A binder solution containing a copolymer (weight average molecular weight: 870,000 g / mol) was prepared in the same manner as in Example 1, except that a mixture of 55 wt% of acrylic acid (AA), 40 wt% of acrylonitrile (AN), and 5 wt% of [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (MSAH) based on 100 wt% of the mixture was mixed. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0170] Example 4

[0171] A binder solution containing a copolymer (weight average molecular weight: 870,000 g / mol) was prepared in the same manner as in Example 1, except that a mixture of 55 wt% of acrylic acid (AA), 40 wt% of acrylonitrile (AN), 2.5 wt% of 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) and 2.5 wt% of 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) based on 100 wt% of the mixture was prepared. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0172] Example 5

[0173] A binder solution containing a copolymer was prepared in the same manner as in Example 1, except that a mixture of 50 wt % of acrylic acid (AA), 40 wt % of acrylonitrile (AN), and 10 wt % of 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) based on 100 wt % of the mixture was used. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0174] Example 6

[0175] A binder solution containing a copolymer was prepared in the same manner as in Example 1, except that a mixture of 56 wt % of acrylic acid (AA), 40 wt % of acrylonitrile (AN), and 4 wt % of 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) based on 100 wt % of the mixture was used. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0176] Example 7

[0177] A binder solution containing a copolymer was prepared in the same manner as in Example 1, except that a mixture of 49 wt % of acrylic acid (AA), 40 wt % of acrylonitrile (AN), and 11 wt % of 3-allyloxy-2-hydroxy-1-propanesulfonic acid (AHPS) based on 100 wt % of the mixture was used. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0178] Comparative Example 1

[0179] A binder solution containing a copolymer (weight average molecular weight: 900,000 g / mol) was prepared in the same manner as in Example 1, except that a mixture of 60 wt % of acrylic acid (AA) and 40 wt % of acrylonitrile (AN) based on 100 wt % of the mixture was used. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0180] Comparative Example 2

[0181] A binder solution containing a copolymer (weight average molecular weight: 890,000 g / mol) was prepared in the same manner as in Example 1, except that a mixture of 55 wt% of acrylic acid (AA), 40 wt% of acrylonitrile (AN), and 5 wt% of vinyl sulfonic acid (VS) based on 100 wt% of the mixture was used. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0182] Comparison Example 3

[0183] A binder solution containing a copolymer (weight average molecular weight: 880,000 g / mol) was prepared in the same manner as in Example 1, except that a mixture of 55 wt% of acrylic acid (AA) and 40 wt% of acrylonitrile (AN) based on 100 wt% of the mixture and 5 wt% of styrene (St) were used. A negative electrode and a battery were prepared in the same manner as in Example 1, except that the prepared binder solution was used.

[0184] Experimental Example 1: Crack Generation

[0185] Cracks generated in the process of using the negative electrode active material slurries prepared in Examples and Comparative Examples were observed with naked eyes. Specifically, the surface of the negative electrode was visually inspected to evaluate the generation of cracks.

[0186] Experimental Example 2: Warpage value (unit: cm)

[0187] Each of the negative electrodes prepared in Examples and Comparative Examples was cut into a sample having a size of 5 cm×5 cm (length×width) and then placed on a flat plate in a drying room for 1 hour to measure the height of the highest point of the negative electrode from the bottom of the plate.

[0188] Experimental Example 3: Negative electrode expansion rate when fully charged (unit: %)

[0189] The batteries of the examples and comparative examples were charged at 25° C. at 0.2 C constant current until the voltage reached 4.2 V and cut off at 0.025 C in constant voltage mode. The ratio of the thickness of the negative electrode before the test to the thickness of the negative electrode after the test was obtained and the result was expressed as the negative electrode expansion rate.

[0190] Experimental Example 4: Full battery SOH90 (unit: number of cycles)

[0191] A stacked full battery was manufactured by stacking 10 sheets of the positive electrode and the negative electrode manufactured in each of the example and the comparative example, and then the number of cycles at which the battery reached a capacity retention rate of 90% was evaluated by charging at 0.33C and discharging at 0.5C at 25°C.

[0192] Table 1

[0193]

[0194] As shown in Table 1, the aqueous binder according to the embodiments of the present disclosure reduces the shrinkage and expansion of the silicon-based negative electrode active material, prevents or substantially prevents the embrittlement of the negative electrode, improves the negative electrode energy density, makes the negative electrodes each containing the silicon-based negative electrode active material crack-free, and reduces the warpage value of the negative electrode.

[0195] Although the present disclosure has been described with reference to some embodiments and drawings, it should be understood that the present disclosure is not limited thereto and that those skilled in the art may make various modifications, changes, alterations, and equivalent embodiments without departing from the spirit and scope of the present disclosure.

Claims

1. A binder for a negative electrode of a rechargeable lithium battery, the binder comprising: units derived from a first monomer; as well as a unit derived from a second monomer, the second monomer being a (meth)acrylic monomer, wherein the first monomer comprises at least one of a (meth)allyl ether monomer and a (meth)acrylate monomer, and The (meth)allyl ether monomer and the (meth)acrylate monomer each include an alkyl group having a carbon number of 3 or more and an anionic functional group.

2. The adhesive according to claim 1, wherein The anion functional group is sulfonic acid group -SO3H or sulfonic acid anion -SO3 - , phosphonic acid group -PO(OH)2 or anion of phosphonic acid group -PO(OH)O - or-PO3 2- , or phosphinate -P(O)H(OH) or phosphinate anion -P(O)HO - .

3. The adhesive according to claim 1, wherein The number of carbon atoms ranges from 3 to 20.

4. The adhesive according to claim 1, wherein The first monomer is represented by Formula 1: Formula 1 Wherein, R1 is hydrogen or methyl; R2 is CH2 or C=O; R3 is a substituted or unsubstituted alkylene group having 3 or more carbon atoms, a substituted or unsubstituted iminoalkyl group having 3 or more carbon atoms or an ammonium cation group thereof, or a substituted or unsubstituted alkylamino group having 3 or more carbon atoms or an ammonium cation group thereof; and X is an anionic functional group.

5. The adhesive according to claim 1, wherein The first monomer includes at least one compound selected from among the compounds represented by Formula 1-1, Formula 1-2, and Formula 1-3: Formula 1-1 Formula 1-2 Formula 1-3 6. The adhesive according to claim 1, wherein The (meth)acrylic monomer includes at least one of a (meth)acrylic monomer having a nitrile group and a (meth)acrylic monomer having a carboxylic acid group.

7. The adhesive according to claim 6, wherein The (meth)acrylic monomer includes a mixture of a (meth)acrylic monomer having a nitrile group and a (meth)acrylic monomer having a carboxylic acid group.

8. The adhesive according to claim 1, wherein The binder is a copolymer of a monomer mixture including a first monomer and a second monomer.

9. The adhesive according to claim 8, wherein The monomer mixture includes 3 wt % to 15 wt % of the first monomer and 85 wt % to 97 wt % of the second monomer.

10. The adhesive according to claim 8, wherein The monomer mixture includes 3 wt % to 15 wt % of the first monomer, 30 wt % to 50 wt % of a (meth)acrylic monomer having a nitrile group, and 40 wt % to 65 wt % of a (meth)acrylic monomer having a carboxylic acid group.

11. The adhesive according to claim 8, wherein The first monomer and the second monomer are present in the monomer mixture in a total amount of 99.5 wt % or more.

12. The adhesive according to claim 1, further comprising: A unit derived from a (meth)acrylamide monomer having an anionic functional group.

13. The adhesive according to claim 12, wherein The anionic functional group of the (meth)acrylamide monomer is a sulfonic acid group -SO3H or an anion of a sulfonic acid group -SO3 - , phosphonic acid group -PO(OH)2 or anion of phosphonic acid group -PO(OH)O - or-PO3 2- , or phosphinate -P(O)H(OH) or phosphinate anion -P(O)HO - .

14. The adhesive according to claim 12, wherein The (meth)acrylamide monomer is represented by Formula 4: Wherein, R1 is hydrogen or methyl; R2 is a substituted or unsubstituted alkylene group having 1 or more carbon atoms; R3 is hydrogen or a substituted or unsubstituted C1 to C 10 Alkyl; and X is an anionic functional group.

15. The adhesive according to claim 12, wherein The binder is a copolymer of a monomer mixture including a first monomer, a second monomer and a (meth)acrylamide monomer, and The (meth)acrylamide monomer is present in the monomer mixture in an amount of 1 wt % to 5 wt %.

16. The adhesive according to claim 1, wherein The binder has a weight average molecular weight of 500,000 g / mol to 1,500,000 g / mol.

17. A rechargeable lithium battery, comprising: A negative electrode comprising a binder according to any one of claims 1 to 16 and a negative electrode active material; Positive electrode; as well as Electrolyte.

18. The rechargeable lithium battery according to claim 17, wherein: The negative electrode active material includes a silicon-based negative electrode active material.

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