Dry negative electrode film, dry negative electrode comprising dry negative electrode film, and lithium battery comprising dry negative electrode film

Abstract

Provided are a dry negative electrode film, a negative electrode including the dry negative electrode film, and a lithium battery. The dry negative electrode film includes a dry negative electrode active material and a dry binder. The dry anode active material includes a composite anode active material including a core and a shell on a surface of the core. Each core includes a carbon-based material, a mixture of a carbon-based material and a silicon-based material, a composite of a carbon-based material and a silicon-based material, or a combination thereof. Each shell comprises a composite of a first carbon-based material and one or more types of first metal oxides. The first metal oxide is located in the carbon-based material matrix and is represented by the chemical formula MaOb (0lt, a < = 3, 0lt, blt, 4, when a is 1, 2 or 3, b is not an integer), where M is at least one metal selected from Group 2 to Group 16 in the periodic table of elements.

Description

TECHNICAL FIELD

[0001] One or more embodiments relate to a dry negative electrode film, and a dry negative electrode and a lithium battery including the same. BACKGROUND

[0002] To meet the requirements of miniaturization and high performance of various devices, in addition to miniaturization and light weight of lithium batteries, high energy density has become important. In other words, high-capacity lithium batteries are becoming important.

[0003] An electrode manufactured from a slurry including a solvent uses an excess amount of the solvent during the manufacturing of the electrode. Accordingly, a dry method that does not use such an organic solvent is being studied. SUMMARY

[0004] TECHNICAL PROBLEM One or more embodiments include a new dry negative electrode film having improved cycle characteristics by reducing internal resistance and improving mechanical strength.

[0005] One or more embodiments include a dry negative electrode including the dry negative electrode film.

[0006] One or more embodiments include a lithium battery including the dry negative electrode.

[0007] TECHNICAL SOLUTION According to one or more embodiments, The dry negative electrode film includes a dry negative electrode active material and a dry binder, wherein the dry negative electrode active material includes a composite negative electrode active material, the composite negative electrode active material includes a core and a shell disposed along a surface of the core, wherein the core includes a carbon-based material, a mixture of a carbon-based material and a silicon-based active material, a composite of a carbon-based material and a silicon-based active material, or a combination thereof, and the shell includes a composite including a first carbon-based material and at least one first metal oxide, the first metal oxide being disposed within a matrix of the first carbon-based material, the first metal oxide being represented by the formula M a O b (0 < a ≤ 3 and 0 < b < 4, wherein if a is 1, 2, or 3, b is not an integer), and M is at least one metal selected from Groups 2 to 16 of the Periodic Table of the Elements.

[0008] According to one or more embodiments, the dry negative electrode includes a negative electrode current collector and the dry negative electrode film disposed on one side or opposite sides of the negative electrode current collector.

[0009] The negative electrode current collector includes a substrate and an intermediate layer disposed between the substrate and the dry negative electrode film, wherein the intermediate layer includes a carbon-based conductive material.

[0010] According to one or more embodiments, the lithium battery includes a positive electrode, a negative electrode, and an electrolyte disposed between the positive electrode and the negative electrode, wherein, The negative electrode is a dry negative electrode, and The electrolyte includes a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0011] Advantages According to one aspect, the internal resistance of the dry negative electrode film is reduced and its mechanical properties are improved, thereby improving the initial efficiency and cycle characteristics of a lithium battery using the dry negative electrode film. BRIEF DESCRIPTION OF DRAWINGS

[0012] Figure 1 is a schematic cross-sectional view of a dry negative electrode active material according to an embodiment; Figure 2 is a schematic cross-sectional view of a dry negative electrode active material according to an embodiment; Figure 3a shows a structure of a dry negative electrode-separator subassembly according to an embodiment; Figure 3b shows a structure of a dry negative electrode-separator subassembly according to an embodiment; Figure 4a is a cross-sectional view showing a stacked structure of a dry negative electrode for a lithium battery according to an embodiment; Figure 4b is a cross-sectional view showing a stacked structure of a dry negative electrode for a lithium battery according to an embodiment; Figure 4c is a cross-sectional view showing a stacked structure of a dry negative electrode for a lithium battery according to an embodiment; Figure 5 shows a schematic diagram of a lithium battery according to an embodiment; Figure 6 shows a schematic diagram of a lithium battery according to an embodiment; and Figure 7 shows a schematic diagram of a lithium battery according to an embodiment.

[0013] List of Reference Numerals of Main Elements 1 lithium battery; 2 negative electrode 3 positive electrode; 4 separator 5 battery case; 6 cap assembly 7 battery structure; 8 electrode tab 10 core; 20 shell 21 first metal oxide; 22 first carbon-based material 23 second carbon-based material; 100 dry negative electrode active material DETAILED DESCRIPTION

[0014] The presented inventive concepts will now be described more fully with reference to the accompanying drawings, in which example embodiments are shown. The inventive concepts may, however, be embodied in many different forms and should not be construed as limited to the example embodiments set forth herein. Rather, these example embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concepts to those skilled in the art. In the drawings, like reference numerals are used to indicate like elements throughout.

[0015] It will also be understood that when an element is referred to as being "on" or "over" another element, it can be directly on the other element or intervening elements can also be present. In contrast, when an element is referred to as being "directly on" or "directly over" another element, there are no intervening elements present.

[0016] It will be understood that, although the terms first, second, third, etc. can be used herein to describe various elements, components, regions, layers and / or sections, these elements, components, regions, layers and / or sections should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer or section from another element, component, region, layer or section. For example, a first element, component, region, layer or section could be termed a second element, component, region, layer or section without departing from the teachings of the disclosure.

[0017] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the inventive concepts. As used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, including "at least one", unless the context clearly indicates otherwise. The terms "comprises" and / or "comprising," or "includes" and / or "including" when used in this specification, specify the presence of stated features, regions, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, regions, integers, steps, operations, elements, components, and / or groups thereof.

[0018] Spatially relative terms, such as "beneath", "below", "lower", "on", "above", "upper" and the like, can be used herein for ease of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientations depicted in the figures. For example, if a device shown in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative terms used herein interpreted accordingly.

[0019] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the specification and relevant art and should not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0020] Exemplary embodiments are described herein with reference to cross-sectional illustrations that are schematic illustrations of idealized embodiments. As such, variations from the shapes of the illustrations as a result, for example, of manufacturing techniques and / or tolerances, are to be expected. Thus, embodiments described herein are not to be construed as limited to the precise shapes illustrated but are to include deviations in shapes that result from, for example, manufacturing. For example, a region illustrated or described as flat can often have rough and / or nonlinear features. Moreover, sharp angles can be rounded (e.g., spherically or otherwise). Thus, the regions depicted in the figures are schematic and are not intended to be limiting of the scope of the present disclosure in terms of the shapes of the regions depicted. The terms of degree such as "substantially", "approximately", and the like, are used herein to describe applicable embodiments. Unless otherwise specified, these terms are not to be interpreted as an absolute limitation but as an allowable variation that could exist when manufacturing or using the devices of the present disclosure, or enabling the both. For example, it is contemplated that the terms "substantially" and "approximately" can be used herein to refer to a value that is within 10% of the stated value, or within 5% of the stated value, or within 1% of the stated value, or within 0.1% of the stated value.

[0021] "Group" refers to a group in the Periodic Table of Elements according to the International Union of Pure and Applied Chemistry ("IUPAC") Group Numbering System 1-18.

[0022] The term "dry" used herein refers to a state in which proper operation can be achieved even without contact with a solvent such as a process solvent. For example, a dry conductive material refers to a conductive material that properly works without contact with a solvent or a conductive material that does not contain a solvent. For example, a dry binder refers to a binder that properly works without contact with a solvent or a binder that does not contain a solvent, and the like. For example, a binder that is not mixed with a solvent and is in a liquid state at room temperature can be considered as a dry binder.

[0023] The term "particle size" as used herein refers to the average diameter when the particle is spherical, and the average length of its major axis when the particle is non-spherical. Particle size can be measured using a particle size analyzer (PSA). For example, the term "particle size" can refer to the average particle size. The term "average particle size" can refer to, for example, the median particle size (D50).

[0024] D50 can refer to the particle size corresponding to 50% of the cumulative volume, calculated from the smallest particle size, in a particle size distribution measured by laser diffraction.

[0025] D90 can refer to the particle size corresponding to 90% of the cumulative volume, calculated from the smallest particle size, in a particle size distribution measured by laser diffraction.

[0026] D10 can refer to the particle size corresponding to 10% of the cumulative volume, calculated from the smallest particle size, in a particle size distribution measured by laser diffraction.

[0027] The average particle size (D50) can be measured by methods suitable for those skilled in the art, such as by a particle size analyzer, transmission electron microscope images, scanning electron microscope images, or field emission scanning electron microscope (FE-SEM) images. In some embodiments, data analysis is performed using a dynamic light scattering measurement device and the number of particles is counted according to the particle size range, and the average particle size (D50) value can be readily obtained by calculation. In this disclosure, "diameter" refers to the particle size or average particle size when the particle is spherical, and "diameter" refers to the length of the major axis or the average length of the major axis when the particle is non-spherical.

[0028] As used herein, the term "metal" refers to metals and metalloids (such as silicon and germanium) in the form of elements or ions.

[0029] As used herein, the term "alloy" means a mixture of two or more metals.

[0030] As used herein, the term "electrode active material" refers to an electrode material that can undergo lithiation and delithiation.

[0031] As used herein, the term "positive electrode active material" refers to a positive electrode material capable of lithiation and delithiation.

[0032] As used herein, the term "negative electrode active material" refers to a negative electrode material capable of lithiation and delithiation.

[0033] As used herein, the terms “lithiation” and “carrying lithiation” refer to the process of adding lithium to an electrode active material.

[0034] As used herein, the terms “delithiation” and “performing delithiation” refer to the process of removing lithium from the electrode active material.

[0035] As used herein, the terms "charging" and "to charge" refer to the process of providing electrochemical energy to a battery.

[0036] As used herein, the terms "discharging" and "to discharge" refer to the process of removing electrochemical energy from a battery.

[0037] The term "positive electrode" used herein refers to an electrode where electrochemical reduction and lithiation occur during the discharging process.

[0038] The term "negative electrode" used herein refers to an electrode where electrochemical oxidation and delithiation occur during the discharging process.

[0039] Although specific examples are described herein, alternatives, modifications, variations, improvements, and substantial equivalents that are within the scope of examples disclosed herein can exist. Accordingly, the attached claims as filed and as they can be amended are intended to encompass all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0040] Hereinafter, a dry negative electrode film according to an embodiment, and a dry negative electrode and a lithium battery each including the dry negative electrode film will be described in more detail.

[0041] If an active material, a conductive material, and a binder are mixed by using a dry method to prepare a negative electrode as a dry negative electrode, while the nano-particle conductive material is combined with the binder, the binder combined with the active material is excessively agglomerated with the conductive material. As a result, the mixed state of the active material, the conductive material, and the binder can be non-uniform, such that the resistance of the negative electrode can be high and the tensile strength can be low. By addressing these problems in the manufacturing process of the dry electrode plate, a dry negative electrode film in which the binder and the conductive material are uniformly combined to the surface of the active material can be provided, thereby resulting in a dry negative electrode film having an improved resistance reduction effect as well as an improved tensile strength, and a dry negative electrode and a lithium battery including the same.

[0042] The dry negative electrode film according to an embodiment includes a dry negative electrode active material and a dry binder, wherein the dry negative electrode active material includes a core and a shell disposed along a surface of the core, wherein the core includes a carbon-based material, a mixture of a carbon-based material and a silicon-based active material, a composite of a carbon-based material and a silicon-based active material, or a combination thereof, and the shell includes a composite including a first carbon-based material and at least one first metal oxide disposed within a matrix of the first carbon-based material, the first metal oxide represented by the formula M a O b (0 < a ≤ 3 and 0 < b < 4, wherein, if a is 1, 2, or 3, b is not an integer) and M is at least one metal selected from Groups 2 to 16 of the Periodic Table of Elements.

[0043] Referring toFigure 1 The dry negative active material 100 includes a core 10 and a shell 20 continuously or discontinuously disposed on a surface of the core 10.

[0044] The core 10 can include a carbon-based material, a mixture of a carbon-based material and a silicon-based active material, a composite of a carbon-based material and a silicon-based active material, or a combination thereof, and the shell 20 can cover all or a portion of the core 10.

[0045] The shell 20 can include a first metal oxide 21 and a first carbon-based material 22. The dry negative active material can be an electrode active material that is not impregnated, dissolved, or dispersed in a process solvent in a process of manufacturing a dry negative electrode film, for example.

[0046] Since the dry negative active material has a core / shell structure and the shell includes the first carbon-based material, the dry negative active material and the dry binder can be more uniformly mixed. Therefore, agglomeration of the dry binder in the dry negative electrode film can be inhibited, and the dry binder can be uniformly distributed in three dimensions. By inhibiting a local resistance region within the dry negative electrode film, current density imbalance can be reduced, and the internal resistance of the dry negative electrode film as a whole can be reduced.

[0047] Since the dry negative active material has a core / shell structure and the shell includes the first carbon-based material, the interfacial resistance between the dry negative active material and the dry negative active material can be reduced. Since the dry negative active material has a core / shell structure and the shell includes the first carbon-based material, the internal resistance of the dry negative electrode film can be reduced. Since the dry negative active material has a core / shell structure and the shell includes the first carbon-based material, the adhesion of the dry negative active material and the dry binder can be improved. Since the dry composite negative active material has a core / shell structure and the shell includes the first carbon-based material, the mechanical properties (such as tensile strength) of the dry negative electrode film can be improved. Since the internal resistance of the dry negative electrode film is reduced and its mechanical properties are improved, the cycle characteristics of a lithium battery including such a dry negative electrode film can be improved.

[0048] Since the shell includes the first metal oxide, its ionic conductivity can be improved compared to a shell made of a carbon-based material, and as a result, the ionic conductivity of the dry negative active material can be improved.

[0049] The dry negative active material has a core / shell structure, and the shell can be continuously or discontinuously disposed along the surface of the core. Since the shell includes the first metal oxide disposed in the matrix of the first carbonaceous material, the shell can be more uniformly disposed on the core. In some embodiments, since the complex including the first metal oxide disposed in the matrix of the first carbonaceous material is introduced onto the core, the first carbonaceous material can be less agglomerated and more uniformly disposed on the core. Since the contact between the core and the electrolyte is effectively blocked by the shell uniformly disposed on the core, the side reaction due to the contact between the core and the electrolyte can be prevented. In some embodiments, since the mixing of cations due to the contact between the core and the electrolyte is suppressed, the formation of a resistance layer on the surface of the core can be suppressed. Further, since the shell is introduced on the core, the elution of transition metal ions from the core including the transition metal can be suppressed. The first carbonaceous material can be, for example, a crystalline carbonaceous material. The first carbonaceous material can be, for example, a carbonaceous nanostructure. The first carbonaceous material can be, for example, a carbonaceous two-dimensional nanostructure. The first carbonaceous material can be, for example, graphene. For example, the shell including graphene and / or the matrix thereof has flexibility, allowing easy adaptation to the volume change of the dry negative active material during charging and discharging, thereby preventing cracks from occurring inside the dry negative active material. Since graphene has high electronic conductivity, the interfacial resistance between the dry negative active material and the electrolyte can be reduced. Despite the introduction of the graphene-containing shell, the increase in the internal resistance of the lithium battery can be suppressed. In some embodiments, the carbonaceous material of the art not including the first metal oxide is easily agglomerated, making it difficult to uniformly distribute it on the core of the dry negative active material. In some embodiments, since the matrix of the first carbonaceous material is derived from, for example, a graphene matrix, its density is relatively low and its porosity is relatively high compared to the carbonaceous material of the art derived from a graphite-based material.

[0050] The dry negative active material has a core / shell structure. The shell can include a first metal oxide, and the metal included in the first metal oxide can be, for example, at least one selected from Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se. The first metal oxide can be, for example, at least one selected from Al2O z (0<z<3), NbO x (0 x (0 z (0<z<3), TiO y (0 y (0 z (0 y (0 y (0 z(0 < z < 3), Co3O4 w (0 < w < 4), PdO x (0 < x < 1), CuO x (0 < x < 1), AgO x (0 < x < 1), ZnO x (0 < x < 1), Sb2O3 z (0 < z < 3), and SeO2 y (0 < y < 2). Since the first metal oxide is disposed in the matrix of the first carbon-based material, uniformity of the shell disposed on the core is improved, and high-pressure resistance of the dry negative electrode active material can be further improved. The shell can include, for example, Al2O3 x (0 < x < 3) as the first metal oxide.

[0051] The shell can further include one or more second metal oxides. The second metal oxide can be represented by, for example, the formula M a O c (0 < a ≤ 3, 0 < c ≤ 4, where, if a is 1, 2, or 3, c is an integer), where M is at least one metal selected from Groups 2 through 13, Group 15, and Group 16 of the periodic table. The second metal oxide can include, for example, the same metal as the first metal oxide. The ratio c / a of c to a of the second metal oxide can have a value greater than the ratio b / a of b to a of the first metal oxide. For example, c / a > b / a can be satisfied. The second metal oxide can be disposed within the matrix of the first carbon-based material. In some embodiments, the second metal oxide can be selected from Al2O3, NbO, NbO2, Nb2O5, MgO, Sc2O3, TiO2, ZrO2, V2O3, WO2, MnO2, Fe2O3, Co3O4, PdO, CuO, AgO, ZnO, Sb2O3, and SeO2. The first metal oxide can be, for example, a reduction product of the second metal oxide. The first metal oxide can be obtained by partially or completely reducing the second metal oxide. Accordingly, the first metal oxide can have a lower amount of oxygen and a lower oxidation number of metal than the second metal oxide. For example, the shell can include the first metal oxide Al2O x (0 < x < 3) and the second metal oxide Al2O3.

[0052] The shell can include, for example, at least one selected from the first metal oxide and the second metal oxide, and the particle diameter of the at least one selected from the first metal oxide and the second metal oxide can be, for example, about 0.1 nm to about 100 nm, about 0.5 nm to about 100 nm, about 1 nm to about 100 nm, about 1 nm to about 50 nm, about 1 nm to about 30 nm, about 5 nm to about 30 nm, or about 10 nm to about 30 nm. In these nanometer ranges of the particle diameter of the first metal oxide and / or the second metal oxide, a uniform distribution can be obtained in the matrix of the first carbon-based material. If the particle diameter of the at least one of the first metal oxide and the second metal oxide is excessively increased, the thickness of the shell can increase, and thus the internal resistance of the composite negative electrode active material can increase. If the particle diameter of the at least one of the first metal oxide and the second metal oxide is excessively decreased, a uniform dispersion can not be obtained.

[0053] The shell can include the first metal oxide and / or the second metal oxide, and can include the first carbon-based material. The first carbon-based material can be disposed in a direction protruding from the surface of the first metal oxide and / or the second metal oxide. The first carbon-based material can be disposed in a direction protruding from the surface of the first metal oxide and / or the second metal oxide by directly growing from the surface of the first metal oxide and / or the second metal oxide. The first carbon-based material disposed in a direction protruding from the surface of the first metal oxide and / or the second metal oxide can be, for example, a carbon-based two-dimensional nanostructure, a carbon-based platelet, or graphene.

[0054] The thickness of the shell can be, for example, 5 µm or less, about 0.1 nm to about 5 µm, about 0.5 nm to about 5 µm, about 1 nm to about 5 µm, about 1 nm to about 1 µm, about 1 nm to about 500 nm, about 1 nm to about 200 nm, about 1 nm to about 100 nm, about 1 nm to about 50 nm, about 1 nm to about 30 nm, or about 1 nm to about 20 nm. If the shell has a thickness in these ranges, the electronic conductivity of the dry negative electrode including the dry negative electrode active material can be further improved, and the internal resistance thereof can be further reduced.

[0055] The shell can have a single-layer structure or a multi-layer structure. The multi-layer structure can have, for example, a two-layer structure, a three-layer structure, or a four-layer structure. In the multi-layer structure, for example, the type of metal included in the first metal oxide can be different in each layer.

[0056] In some embodiments, the shell can have a content of 5 wt% or less, about 0.01 wt% to about 5 wt%, about 0.01 wt% to about 3 wt%, about 0.01 wt% to about 2 wt%, or about 0.01 wt% to about 1 wt%, based on the total weight of the dry negative electrode active material. In some embodiments, the first metal oxide can have a content of 3 wt% or less, about 0.006 wt% to about 3 wt%, about 0.06 wt% to about 1.8 wt%, about 0.006 wt% to about 1.2 wt%, or about 0.006 wt% to about 0.6 wt%, based on the total weight of the dry negative electrode active material. If the dry negative electrode active material includes a shell and a first metal oxide in such ranges, the cycling characteristics of the lithium battery can be further improved.

[0057] The shell disposed along the surface of the core can be, for example, a dry coating layer. The shell can be introduced onto the core by a dry method (e.g., by milling). In some embodiments, the shell disposed on the surface of the core can include at least one selected from the group consisting of: a composite including a first metal oxide and a first carbonaceous material (e.g., graphene); and a milling product of the composite. The first metal oxide can be disposed within a matrix of the first carbonaceous material (e.g., a graphene matrix).

[0058] In some embodiments, the shell can be prepared from a composite including a first metal oxide and a first carbonaceous material (e.g., graphene). The composite can include a second metal oxide in addition to the first metal oxide. For example, the composite can include two or more types of the first metal oxide. For example, the composite can include two or more types of the first metal oxide and two or more types of the second metal oxide.

[0059] The composite can include at least one selected from the first metal oxide and the second metal oxide. The particle diameter of the at least one selected from the first metal oxide and the second metal oxide can be about 0.1 nm to about 100 nm, about 0.5 nm to about 100 nm, about 1 nm to about 100 nm, about 1 nm to about 50 nm, about 1 nm to about 30 nm, about 5 nm to about 30 nm, or about 10 nm to about 30 nm. In these nanometer ranges of the particle diameter of the first metal oxide and / or the second metal oxide, a uniform distribution can be obtained in the matrix of the first carbon-based material of the composite. Accordingly, the composite can be uniformly coated on the core without aggregation to form a shell. In some embodiments, due to having a particle diameter in the above ranges, the first metal oxide and / or the second metal oxide can be more uniformly disposed on the core. As the first metal oxide and / or the second metal oxide are uniformly disposed on the core, the pressure resistance characteristics can be more effectively achieved. The particle diameter of the first metal oxide and / or the second metal oxide can be measured by using a measuring device using, for example, a laser diffraction method or a dynamic light scattering method. The particle diameter is a value of a median particle diameter (D50) in the case where the cumulative volume reaches 50% from the smallest particle size, and it can be measured, for example, using a laser scattering particle size analyzer such as a Horiba LA-920 and converting the data to volume. The uniformity deviation of the at least one selected from the first metal oxide and the second metal oxide can be 3% or less, 2% or less, or 1% or less.

[0060] The uniformity can be measured, for example, by X-ray photoelectron spectroscopy (XPS). Accordingly, the at least one selected from the first metal oxide and the second metal oxide can be uniformly distributed in the composite with a deviation of 3% or less, 2% or less, or 1% or less.

[0061] The dry negative active material can include a core, and the core can include, for example: a carbon-based material; a mixture of a carbon-based material and a silicon-based active material; a composite of a carbon-based material and a silicon-based active material; or a combination thereof.

[0062] The content of the silicon-based active material in the mixture of a carbon-based material and a silicon-based active material or the composite of a carbon-based material and a silicon-based active material can be about 5 wt% to about 20 wt%, about 7 wt% to about 18 wt%, about 10 wt% to about 17 wt%, or about 10 wt% to about 15 wt% based on the total weight of 100 wt% of the mixture of a carbon-based material and a silicon-based active material or the composite of a carbon-based material and a silicon-based active material.

[0063] The carbon-based material can be crystalline carbon, amorphous carbon, or a combination thereof, the crystalline carbon can be at least one selected from the group consisting of natural graphite, artificial graphite, graphene, fullerene, and carbon nanotube, and the amorphous carbon can be at least one selected from the group consisting of pitch carbon, soft carbon, hard carbon, meso-carbon microbead, calcined coke, and carbon fiber.

[0064] The precursor of the amorphous carbon can be coal-based pitch, meso-carbon pitch, petroleum-based pitch, coal-based oil, petroleum-based heavy oil, or a polymer resin such as phenol resin, furan resin, or polyimide resin.

[0065] The silicon-based active material can be a Si alloy, a silicon-containing structure, a silicon-containing compound, or a combination thereof.

[0066] The silicon-containing compound can be SiO2, SiO x (0 < x < 2), SiC, or a combination thereof, and the silicon-containing structure includes a silicon composite structure.

[0067] According to an embodiment, the silicon composite structure can be a silicon-carbon composite.

[0068] The silicon-carbon composite can be: a silicon-carbon composite including silicon particles and a first carbon-based material; a silicon-carbon composite including a core in which silicon particles and a second carbon-based material are mixed, and a third carbon-based material surrounding the core; or a combination thereof.

[0069] The first to third carbon-based materials can each independently be crystalline carbon, amorphous carbon, or a combination thereof. The silicon-carbon composite includes a core including silicon particles and crystalline carbon, and an amorphous carbon coating layer on a surface of the core.

[0070] If the silicon-carbon composite is used as the silicon-based active material, the secondary battery can achieve stable cycle characteristics while exhibiting high capacity.

[0071] In the silicon-carbon composite including silicon particles and a first carbon-based material, the content of the silicon particles can be about 30 wt% to about 70 wt%, about 30 wt% to about 60 wt%, for example, about 40 wt% to about 50 wt%. In some embodiments, the silicon-based active material can include a silicon-carbon composite including a core in which silicon particles and a second carbon-based material are mixed, and a third carbon-based material surrounding the core. If such a silicon-carbon composite is used, very high capacity of the secondary battery can be obtained, and capacity retention and high-temperature life characteristics of the secondary battery can be improved. The average particle diameter (D50) used herein refers to the diameter of particles whose cumulative volume is 50% by volume in the particle size distribution.

[0072] In some embodiments, the third carbon-based material can be included in an amount of about 1 wt% to about 50 wt% and the silicon particles can be included in an amount of about 30 wt% to about 70 wt% based on 100 wt% of the silicon-carbon composite. The second carbon-based material can be included in an amount of about 20 wt% to about 69 wt%. If the contents of the silicon particles, the third carbon-based material, and the second carbon-based material are included in these ranges, the discharge capacity of the secondary battery is excellent, and the capacity retention rate is improved.

[0073] The particle diameter of the silicon particles can be about 10 nm to about 30 µm, for example, about 10 nm to about 1000 nm or about 20 nm to about 150 nm. If the average particle diameter of the silicon particles is included in these ranges, the volume expansion that occurs during charging and discharging can be suppressed, and the transfer of electrons during charging and discharging can be prevented from being interrupted due to the breakage of the particles.

[0074] In the silicon-carbon composite, for example, the second carbon-based material can be crystalline carbon, and the third carbon-based material can be amorphous carbon. The silicon-carbon composite can be a silicon-carbon composite including a core including silicon particles and crystalline carbon, and an amorphous carbon coating layer located on the surface of the core.

[0075] The silicon-carbon composite can be, for example, a silicon-carbon nanocomposite. The silicon-carbon nanocomposite refers to a composite in which at least one of silicon and carbon has a nanoscale size of less than 1 µm. For example, the silicon-carbon nanocomposite can be a composite of silicon nanoparticles and carbon nanoparticles.

[0076] In some embodiments, the silicon-containing compound can include silicon, a silicon alloy, silicon oxide, silicon nitride, silicon oxynitride, silicon carbide, or a combination thereof. The silicon-containing compound can include, for example, SiO x (0 < x ≤ 2).

[0077] The silicon alloy can include: silicon; and an element selected from an alkali metal, an alkaline earth metal, a group 13 to 16 element, a transition metal, a rare earth element, or a combination thereof. The element can be, for example, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof.

[0078] According to an embodiment, the silicon composite structure can include: porous silicon secondary particles; and first carbon sheets disposed on the porous silicon secondary particles, wherein the porous silicon secondary particles are an aggregate of a plurality of silicon composite primary particles, and the silicon composite primary particles include: silicon; silicon dioxide SiO2 and / or silicon suboxide (SiOx a second carbon sheet disposed on the silicon suboxide.

[0079] The silicon composite structure can include porous silicon secondary particles including aggregates of a plurality of silicon composite primary particles and a first carbon sheet disposed on the porous silicon secondary particles. In some embodiments, the first carbon sheet disposed on the porous silicon secondary particles can be disposed to cover at least one surface of the porous silicon secondary particles. The first carbon sheet can be disposed directly on the porous silicon secondary particles. The first carbon sheet can be grown directly on the silicon suboxide of the porous silicon secondary particles. The first carbon sheet can be grown directly from and deposited directly on the surface of the porous silicon secondary particles. The first carbon sheet can completely or partially cover the surface of the porous silicon secondary particles. The coverage of the first carbon sheet can be, for example, about 5% to about 100%, about 10% to about 99%, about 20% to about 95%, or about 40% to about 90%, based on the total surface area of the porous silicon secondary particles. The carbon of the first carbon sheet is present on the surface of the porous silicon secondary particles and effectively buffers the volume change of the porous silicon secondary particles. The size of the porous silicon secondary particles can be, for example, about 1 μιη to about 20 μιη, about 2 μιη to about 18 μιη, or about 3 μιη to about 10 μιη. The size of the first carbon sheet can be, for example, about 1 nm to about 200 nm, about 5 nm to about 150 nm, or about 10 nm to about 100 nm. In some embodiments, the size refers to the diameter or the length of the long axis.

[0080] The silicon composite primary particle can include: silicon; silicon suboxide (SiO x , 0 < x < 2) disposed on at least one surface of the silicon; and a second carbon sheet disposed on one surface of the silicon suboxide. The silicon can be, for example, plate-like, needle-like, spherical, or a combination thereof. The silicon is not limited in its shape and can be, for example, a sphere, a nanowire, a needle, a rod, a particle, a nanotube, a nanorod, a wafer, and a nanoribbon, or a combination thereof. The average size of the silicon can be, for example, about 10 nm to about 1 μιη, about 10 nm to about 500 nm, about 20 nm to about 150 nm, or 100 nm. If the silicon is a spherical particle, the average size of the silicon refers to the average particle diameter; and if the silicon is a non-spherical particle (e.g., a plate-like particle or a needle-like particle), the average size of the silicon refers to the length of the long axis, the length, or the thickness. The silicon suboxide (SiO xThe silicon suboxide can be disposed directly on the silicon. The silicon suboxide can completely or partially cover a surface of the silicon. The coverage of the silicon suboxide can be, for example, about 1% to about 100%, about 5% to about 99%, about 10% to about 95%, or about 20% to about 90% based on the total surface area of the silicon. The second carbon sheet disposed on the silicon suboxide can be disposed to cover at least one surface of the silicon suboxide. The second carbon sheet can be disposed directly on the silicon suboxide. The second carbon sheet can be grown directly from and disposed directly on a surface of the silicon suboxide. In some embodiments, the second carbon sheet can completely or partially cover a surface of the silicon suboxide. The coverage of the second carbon sheet can be, for example, about 10% to about 100%, about 10% to about 99%, about 20% to about 95%, or about 40% to about 90% based on the total surface area of the silicon suboxide. The carbon in the second carbon sheet is present on the surface of the silicon and / or the silicon suboxide and can effectively buffer the volume change of the silicon composite primary particle. The size of the second carbon sheet can be, for example, about 1 nm to about 200 nm, about 5 nm to about 150 nm, or about 10 nm to about 100 nm. In some embodiments, the size refers to the diameter or the length of the major axis.

[0081] The silicon composite structure can include a porous silicon secondary particle and a first carbon sheet disposed on the porous silicon secondary particle. The first carbon sheet can be disposed to completely or partially cover the porous silicon secondary particle. For example, the first carbon sheet can be disposed to completely or partially surround the porous silicon secondary particle. A second carbon sheet can be disposed on the silicon composite primary particle in the porous silicon secondary particle. During the volume expansion / contraction of the silicon composite structure, the silicon included in the porous silicon secondary particle can maintain contact with the first carbon sheet and / or the second carbon sheet. Since the porous secondary particle includes pores, it can act as an internal buffer space during the volume expansion / contraction of the silicon composite structure. Thus, unlike the silicon-based anode active material of the related art, the silicon composite structure can suppress the increase in internal resistance while effectively accommodating the volume change of the silicon composite structure during charging and discharging.

[0082] The silicon composite structure can have a porosity of, for example, 60% or less, for example, about 30% to about 60%. In some embodiments, the silicon composite structure can be non-porous. The non-porous structure can have a porosity of, for example, 10% or less, or 5% or less. The non-porous structure can have a porosity of, for example, about 0.01% to about 5% or 0%. The porosity can be measured by a mercury porosimetry or nitrogen adsorption.

[0083] The silicon composite structure can have, for example, a non-spherical shape. The silicon composite structure can have, for example, a sphericity of 0.9 or less. The silicon composite structure can have, for example, a sphericity of about 0.7 to about 0.9, about 0.8 to about 0.9, or about 0.85 to about 0.9. The sphericity can be determined by, for example, 4πA / P 2

[0084] The silicon composite structure can include a first carbon sheet and a second carbon sheet. The first carbon sheet and the second carbon sheet can be, for example, the same carbon sheet. The first carbon sheet and the second carbon sheet can be any carbon-based material having a sheet shape. The first carbon sheet and the second carbon sheet can independently be graphene, graphite, carbon fiber, graphitic carbon, graphene oxide, or a mixture thereof. The porous composite structure can include, for example, first graphene and second graphene as the first carbon sheet and the second carbon sheet. The first graphene and the second graphene can each have a structure such as a nanoplate, a layer (film), or a flake. The nanoplate refers to a shape having a thickness of about 1000 nm or less (e.g., about 1 nm to about 1000 nm) formed in an irregular state on the silicon suboxide or the porous silicon secondary particle. The film refers to a morphology formed continuously and uniformly on the silicon suboxide or the porous silicon secondary particle.

[0085] The silicon-containing structure can further include a carbon-based coating layer disposed on the silicon composite structure. The carbon-based coating layer can improve the physical stability of the silicon composite structure and more effectively prevent side reactions between silicon and an electrolyte during charging and discharging. The carbon-based coating layer can include, for example, first amorphous carbon. The carbon-based coating layer can include the first amorphous carbon having a high density. The first amorphous carbon can include, for example, pitch carbon, soft carbon, hard carbon, meso-phase pitch carbide, calcined coke, carbon fiber, or a mixture thereof. The carbon-based coating layer can further include crystalline carbon. Due to the addition of the crystalline carbon in the carbon-based coating layer, the carbon-based coating layer can more effectively buffer the volume change of the silicon composite structure. The crystalline carbon can be, for example, natural graphite, artificial graphite, graphene, fullerene, carbon nanotube, or a mixture thereof. The thickness of the carbon-based coating layer can be, for example, about 1 nm to about 5000 nm, about 10 nm to about 2000 nm, or about 5 nm to about 2500 nm.

[0086] In some embodiments, the silicon-containing structure can further include second amorphous carbon disposed within the silicon composite structure. For example, the silicon composite structure can include a porous silicon secondary particle, and the second amorphous carbon can be disposed in pores of the porous silicon secondary particle. The second amorphous carbon can be disposed between a plurality of silicon composite primary particles constituting the porous silicon secondary particle. The silicon composite primary particle can include, for example: silicon; silicon dioxide SiO2 and / or silicon suboxide (SiO x ​carbon disposed on the silicon; a second carbon sheet disposed on the silicon dioxide SiO2 and / or silicon suboxide; and a second amorphous carbon disposed on the second carbon sheet. Since the pores of the silicon composite structure are filled with the dense second amorphous carbon, a dense structure having a non-porous structure can be obtained. Since the silicon composite structure includes such a non-porous structure, a side reaction with an electrolyte solution during charging and discharging can be further reduced, and the volume change of silicon can be more effectively alleviated. The second amorphous carbon can include, for example, pitch carbon, soft carbon, hard carbon, meso-phase pitch carbide, calcined coke, carbon fiber, or a mixture thereof.

[0087] In the silicon composite structure, a mixing ratio of the total weight of the first carbon, which is the sum of the carbon of the first carbon sheet and the carbon of the second carbon sheet, to the weight of the second carbon, which is the carbon of the carbon-based coating layer, can be, for example, 30:1 to 1:3, 20:1 to 1:1, or 10:1 to 1:0.9. Due to the mixing ratio of the first carbon to the second carbon in these ranges, a lithium battery having improved cycle characteristics can be provided. The mixing ratio of the first carbon to the second carbon can be confirmed by thermogravimetric analysis. The first carbon is associated with a peak occurring in the range of 700°C to 750°C, and the second carbon is associated with a peak occurring in the range of 600°C to 650°C. The thermogravimetric analysis can be performed in an air atmosphere in the range of 25°C to 1,000°C at a heating rate of, for example, about 10°C / min. The first carbon can be, for example, crystalline carbon, and the second carbon can be, for example, amorphous carbon. The mixing ratio of the total weight of the carbon of the first carbon sheet and the carbon of the second carbon sheet to the total weight of the first amorphous carbon and the second amorphous carbon can be, for example, about 1:99 to about 99:1, about 1:20 to about 80:1, or about 1:1 to about 1:10.

[0088] The core can include a silicon-containing compound SiO x (0 < x ≤ 2) as a silicon-based active material. The SiO x The average particle diameter of the SiO x The average particle diameter of the SiO

[0089] The shell can include a composite including a first metal oxide and a first carbon-based material.

[0090] Since the first carbon-based material (e.g., graphene) has high electronic conductivity, the interface resistance between the dry negative active material and the electrolyte can be reduced. Although the shell including the first carbon-based material is introduced, an increase in the internal resistance of the lithium battery can be suppressed.

[0091] Because the first carbon-based material is derived from a graphene matrix, the first carbon-based material included in the shell can have a low density and a high porosity relative to conventional carbon-based materials derived from graphite materials. The interplanar spacing d002 of the first carbon-based material included in the shell of the dry negative electrode active material can be, for example, 3.38 Å or greater, 3.45 Å or greater, 3.50 Å or greater, 3.60 Å or greater, 3.80 Å or greater, or 4.00 Å or greater. The interplanar spacing d002 of the first carbon-based material included in the shell of the dry negative electrode active material can be, for example, about 3.38 Å to about 4.0 Å, about 3.38 Å to about 3.8 Å, about 3.38 Å to about 3.6 Å, about 3.38 Å to about 3.5 Å, or about 3.38 Å to about 3.45 Å. In some embodiments, the interplanar spacing d002 of conventional carbon-based materials derived from graphite materials can be, for example, 3.38 Å or less or about 3.35 Å to about 3.38 Å. Because the first metal oxide has high voltage resistance, the first metal oxide can prevent degradation of the core at high voltages during charging and discharging. For example, the shell can include a single type of first metal oxide, or two or more different types of first metal oxides. As a result, the cycle characteristics of a lithium battery including the dry negative electrode active material are improved, and volume changes can be suppressed.

[0092] The shell can include, for example, the first carbon-based material, and the core can include, for example, a silicon-containing structure and / or a silicon-containing compound as a silicon-based active material. For example, the first carbon-based material can form a composite with the silicon-containing structure and / or the silicon-containing compound through a mechanochemical reaction. In some embodiments, the first carbon-based material can be chemically bonded to the silicon-containing structure and / or the silicon-containing compound through a chemical bond. The core and the shell are complexed by chemically bonding the first carbon-based material disposed in the shell and the silicon-containing structure and / or the silicon-containing compound disposed in the core through a chemical bond. Thus, the complexed negative electrode active material can be distinguished from a simple physical mixture of the first carbon-based material and the silicon-containing structure and / or the silicon-containing compound. The first metal oxide and the first carbon-based material included in the shell can also be chemically bonded through a chemical bond. In some embodiments, the chemical bond can be, for example, a covalent bond or an ionic bond.

[0093] The composite can include a first carbon-based material. The first carbon-based material has, for example, a branched structure, and at least one metal oxide selected from the first metal oxide and the second metal oxide can be distributed in the branched structure of the first carbon-based material. The branched structure of the first carbon-based material can include, for example, a plurality of first carbon-based material particles in contact with each other. Since the first carbon-based material has a branched structure, various conductive paths can be provided. The first carbon-based material can be, for example, graphene. The graphene has, for example, a branched structure, and at least one metal oxide selected from the first metal oxide and the second metal oxide can be distributed in the branched structure of the graphene. The branched structure of the graphene can include, for example, a plurality of graphene particles in contact with each other. Since the graphene has a branched structure, various conductive paths can be provided.

[0094] The first carbon-based material can have, for example, a spherical structure, and at least one metal oxide selected from the first metal oxide and the second metal oxide can be distributed in the spherical structure. The size of the spherical structure of the first carbon-based material can be about 50 nm to about 300 nm. The number of the first carbon-based material having the spherical structure can be two or more. The spherical structure of the first carbon-based material can allow the composite to have a rigid structure. The first carbon-based material can be, for example, graphene. The graphene can have, for example, a spherical structure, and at least one metal oxide selected from the first metal oxide and the second metal oxide can be distributed in the spherical structure. The size of the spherical structure of the graphene can be about 50 nm to about 300 nm. The number of the graphene having the spherical structure can be two or more. The spherical structure of the graphene allows the composite to have a rigid structure.

[0095] The first carbon-based material can have, for example, a spiral structure in which a plurality of spherical structures are connected, and at least one metal oxide selected from the first metal oxide and the second metal oxide can be distributed in the spherical structure of the spiral structure. The size of the spiral structure of the first carbon-based material can be about 500 nm to about 100 µm. The spiral structure of the first carbon-based material allows the composite to have a rigid structure. The first carbon-based material can be, for example, graphene. The graphene can have, for example, a spiral structure in which a plurality of spherical structures are connected, and at least one metal oxide selected from the first metal oxide and the second metal oxide can be distributed in the spherical structure in the spiral structure. The spiral structure of the graphene can have a size of about 500 nm to about 100 µm. The spiral structure of the graphene can allow the composite to have a rigid structure.

[0096] The first carbon-based material can have, for example, a cluster structure in which a plurality of spherical structures are aggregated, and at least one metal oxide selected from the first metal oxide and the second metal oxide can be distributed in the spherical structures of the cluster structure. The size of the cluster structure of the first carbon-based material can be about 0.5 mm to about 10 cm. The cluster structure of the first carbon-based material can give the composite a rigid structure. The first carbon-based material can be, for example, graphene. The graphene can have, for example, a cluster structure in which a plurality of spherical structures are aggregated, and at least one metal oxide selected from the first metal oxide and the second metal oxide can be distributed in the spherical structures of the cluster structure. The size of the cluster structure of the graphene can be about 0.5 mm to about 10 cm. The cluster structure of the graphene can give the composite a rigid structure.

[0097] The composite can have, for example, a faceted-ball structure having facets, and at least one selected from the first metal oxide and the second metal oxide can be distributed within the structure or on the surface of the structure. Since the composite is such a polyhedral ball structure, the composite can be easily coated on the irregular surface of the core.

[0098] The composite can have, for example, a planar structure, and at least one selected from the first metal oxide and the second metal oxide can be distributed inside or on the surface of the planar structure. Since the composite is such a two-dimensional planar structure, the composite can be easily coated on the irregular surface of the core.

[0099] The first carbon-based material can extend from the first metal oxide by a distance of 10 nm or less, and can include at least 1 to 20 layers of the first carbon-based material. For example, by stacking a plurality (e.g., 20) of layers of the first carbon-based material, a first carbon-based material having a total thickness of 12 nm or less can be disposed on the first metal oxide. For example, the total thickness of the carbon-based material can be about 0.6 nm to about 12 nm. The first carbon-based material can be, for example, graphene. The graphene can extend from the first metal oxide by a distance of 10 nm or less, and include at least 1 to 20 layers of graphene. For example, graphene having a total thickness of 12 nm or less can be disposed on the first metal oxide by stacking a plurality of layers of graphene. For example, the total thickness of the graphene can be about 0.6 nm to about 12 nm.

[0100] Referring to Figure 2 The shell 20 can further include a second carbon-based material 23 that is a fibrous carbon. The second carbon-based material can include a fibrous carbon.

[0101] By further including a second carbon-based material that is a fibrous carbon in the shell, the conductive path of the negative active material can be further increased. The second carbon-based material can form a three-dimensional conductive network among the plurality of negative active materials to reduce the internal resistance of the negative electrode including the negative active material. By fixing the fibrous carbon on the negative active material, a uniform and stable three-dimensional conductive network can be formed among the plurality of negative active materials. Accordingly, the high rate characteristics of the lithium battery including the negative active material including the second carbon-based material can be improved.

[0102] The aspect ratio of the second carbon-based material can be 10 or more, for example, about 10 to about 100,000, about 10 to about 80,000, about 10 to about 50,000, about 10 to about 10,000, about 10 to about 5000, about 10 to about 1000, about 10 to about 500, about 10 to about 100, or about 10 to about 50. The aspect ratio of the second carbon-based material can be, for example, the ratio of the length of a long axis (e.g., the length of the second carbon-based material) passing through the center of the second carbon-based material to the length of a short axis (e.g., the diameter of the second carbon-based material) passing through the center of the second carbon-based material and perpendicular to the long axis.

[0103] The diameter of the second carbon-based material can be, for example, about 1 nm to about 50 nm, about 1 nm to about 30 nm, or about 1 nm to about 10 nm. If the diameter of the second carbon-based material is within these ranges, the absolute number of strands per volume can be reduced, and thus uniform dispersion can be achieved without producing a non-significant internal resistance reduction effect.

[0104] The length of the second carbon-based material can be, for example, about 100 nm to about 1000 µm, about 100 nm to about 500 µm, about 100 nm to about 100 µm, about 100 nm to about 50 µm, about 100 nm to about 10 µm, about 100 nm to about 5 µm, about 100 nm to about 2 µm, about 100 nm to about 1 µm, about 100 nm to about 500 nm, or about 100 nm to about 300 nm. The length of the second carbon-based material can be, for example, about 500 nm to about 1000 µm, about 500 nm to about 500 µm, about 500 nm to about 100 µm, about 500 nm to about 50 µm, about 500 nm to about 10 µm, about 500 nm to about 5 µm, or about 500 nm to about 2 µm. If the length of the second carbon-based material is within these ranges, an effective conduction path can be provided without increasing the internal resistance of the electrode.

[0105] The second carbon-based material can include, for example, carbon nanofibers, carbon nanotubes, or a combination thereof.

[0106] The carbon nanotube can include, for example, a carbon nanotube primary structure, a carbon nanotube secondary structure formed by aggregating a plurality of carbon nanotube primary particles, or a combination thereof.

[0107] The primary structure of the carbon nanotube can be a carbon nanotube unit.

[0108] The primary structure of the carbon nanotube can include, for example, a single-walled carbon nanotube (SWCNT), a double-walled carbon nanotube (DWCNT), a multi-walled carbon nanotube (MWCNT), or a combination thereof. The diameter of the primary structure of the carbon nanotube can be, for example, about 1 nm to about 20 nm, about 1 nm to about 15 nm, or about 2 nm to about 10 nm. The length of the primary structure of the carbon nanotube can be, for example, about 100 nm to about 2 μm, about 100 nm to about 1 μm, about 100 nm to about 500 nm, about 100 nm to about 400 nm, about 100 nm to about 300 nm, or about 200 nm to about 300 nm. The diameter and length of the primary structure of the carbon nanotube can be measured using a scanning electron microscope (SEM) image or a laser diffraction method.

[0109] The secondary structure of the carbon nanotube is a structure in which the primary structure of the carbon nanotube is partially or entirely assembled to form a bundle type or a rope type. The secondary structure of the carbon nanotube can include, for example, a bundle type carbon nanotube, a rope type carbon nanotube, or a combination thereof. The diameter of the secondary structure of the carbon nanotube can be, for example, greater than or equal to 2 nm or greater than or equal to 3 nm. The diameter of the secondary structure of the carbon nanotube can be, for example, 50 nm or less, 30 nm or less, or 10 nm or less. The diameter of the secondary structure of the carbon nanotube can be, for example, about 2 nm to about 50 nm, about 2 nm to about 30 nm, or about 2 nm to about 20 nm. The length of the secondary structure of the carbon nanotube can be, for example, about 500 nm to about 1000 μm, about 500 nm to about 500 μm, about 500 nm to about 200 μm, about 500 nm to about 100 μm, or about 500 nm to about 50 μm. The diameter and length of the secondary structure of the carbon nanotube can be measured by a SEM image or an optical microscope or a laser diffraction. The secondary structure of the carbon nanotube can be used to prepare a dry negative active material after being dispersed in a solvent and converted into the primary structure of the carbon nanotube.

[0110] The amount of the second carbon-based material can be, for example, about 0.1 wt% to about 50 wt%, about 1 wt% to about 40 wt%, or about 5 wt% to about 30 wt%, based on the total weight of the first carbon-based material and the second carbon-based material. Since the dry negative active material includes the first carbon-based material and the second carbon-based material in these ranges, an electrically conductive path can be effectively obtained within the composite negative active material, which can allow further reduction in internal resistance of the dry negative active material. As a result, the cycle characteristics of a lithium battery including the dry negative active material can be further improved. The content of the second carbon-based material can be, for example, about 0.001 wt% to about 5 wt%, about 0.01 wt% to about 3 wt%, or about 0.01 wt% to about 1 wt%, based on the total weight of the dry negative active material. Since the dry negative active material includes the second carbon-based material in these ranges, an electrically conductive path can be ensured within the composite negative active material, which can allow further reduction in internal resistance of the dry negative active material. As a result, the cycle characteristics of a lithium battery including the dry negative active material can be further improved.

[0111] The specific surface area of the dry negative active material can be, for example, about 1 m 2 / g to about 100 m 2 / g, about 1 m 2 / g to about 50 m 2 / g, or about 1 m 2 / g to about 30 m 2 / g. If the composite negative active material has a specific surface area in these ranges, the cycle characteristics of a lithium battery using the composite negative active material can be further improved. The average particle diameter (D50) of the composite negative active material can be, for example, about 1 μm to about 30 μm, about 3 μm to about 20 μm, or about 5 μm to about 15 μm. The particle diameter (D10) of the composite negative active material can be, for example, about 0.1 μm to about 10 μm, about 0.5 μm to about 10 μm, or about 1 μm to about 10 μm. The particle diameter (D90) of the composite negative active material can be, for example, about 10 μm to about 50 μm, about 10 μm to about 30 μm, or about 10 μm to about 25 μm. If the composite negative active material has an average particle diameter (D50), an average particle diameter (D10), and / or an average particle diameter (D90) in these ranges, the cycle characteristics of a lithium battery using such a dry negative electrode can be further improved.

[0112] The content of the dry conductive material included in the dry negative electrode film can be, for example, about 0.1 wt% to about 5 wt%, about 0.5 wt% to about 5 wt%, or about 1 wt% to about 5 wt%, based on the total weight of the dry negative electrode film. If the dry negative electrode film includes a dry conductive material in these ranges, the conductivity of the dry negative electrode film is improved, and the cycle characteristics of a lithium battery including the dry negative electrode film can be improved.

[0113] The dry negative electrode film can be, for example, a self-standing membrane. In some embodiments, the dry negative electrode film can maintain its membrane form without a support. Therefore, the dry negative electrode film can be prepared as a separate self-standing membrane and then disposed on an electrode current collector. The dry negative electrode film is manufactured using a dry process, and therefore may not contain intentionally added process solvents. For example, residual process solvents may not be included. Unintended trace amounts of solvent may remain in the dry negative electrode film, but these solvents are not intentionally added process solvents. Therefore, the dry negative electrode film can be distinguished from a wet electrode film prepared by mixing components and process solvents and then removing some or all of the process solvents by drying.

[0114] In some embodiments, regarding the dry negative electrode film, the first dry negative electrode film may include a mixture of carbon-based materials and silicon-based active materials as the core of the dry composite negative electrode active material, a composite of carbon-based materials and silicon-based active materials, or a combination thereof, and the second dry negative electrode film includes a carbon-based material as the core of the dry composite negative electrode active material, wherein the content of the binder and the content of the composite (GB) of the first dry negative electrode film are equal to or greater than the content of the binder and the content of the composite (GB) of the second dry negative electrode film, respectively.

[0115] The second dry negative electrode film may also include a conductive material. The conductive material may be a composite (GB), Denka Black, Summer Black, Super P superconducting carbon black, carbon nanotubes, activated carbon, carbon molecular sieves, graphene, carbon black, fine graphite particles, natural graphite, artificial graphite, acetylene black, Ketjen black, carbon fiber, carbon nanotubes; metal powders or fibers or tubes of copper, nickel, aluminum, or silver; or conductive polymers, such as polyphenylene derivatives. In some embodiments, the composite (GB) is the same as the composite comprising at least one first metal oxide and a first carbon-based material constituting the shell of the composite negative electrode active material, and therefore its description will be omitted.

[0116] The dry negative electrode film can include a first dry negative electrode film disposed adjacent to the negative electrode current collector and a second dry negative electrode film disposed on the first dry negative electrode film, wherein the first dry negative electrode film can include a mixture of a carbon-based material and a silicon-based active material, a composite of a carbon-based material and a silicon-based active material, or a combination thereof as a core of a dry composite negative electrode active material, and the second dry negative electrode film can include a mixture of a carbon-based material and a silicon-based active material, a composite of a carbon-based material and a silicon-based active material, or a combination thereof as a core of a dry composite negative electrode active material, wherein the content of the composite (GB) and the binder of the first dry negative electrode film can be equal to or greater than the content of the composite (GB) and the binder of the second dry negative electrode film, respectively, and the content of the mixture of a carbon-based material and a silicon-based active material, the composite of a carbon-based material and a silicon-based active material, or the combination thereof in the first dry negative electrode film can be equal to or greater than the content of the mixture of a carbon-based material and a silicon-based active material, the composite of a carbon-based material and a silicon-based active material, or the combination thereof in the second dry negative electrode film.

[0117] The first dry negative electrode film can include a carbon-based material and a silicon-based active material as a core of a dry composite negative electrode active material, and the silicon-based active material includes a silicon composite structure, and the second dry negative electrode film can include a carbon-based material as a core of a dry composite negative electrode active material, and the content of the binder and the content of the composite (GB) of the first dry negative electrode film can be equal to or greater than the content of the binder and the content of the composite (GB) of the second dry negative electrode film, respectively.

[0118] The dry negative electrode film can include a first dry negative electrode film disposed adjacent to the negative electrode current collector and a second dry negative electrode film disposed on the first dry negative electrode film, wherein the first dry negative electrode film can include a carbon-based material and a silicon-based active material as a core of a dry composite negative electrode active material, and the second dry negative electrode film includes a carbon-based material and a silicon-based active material as a core of a dry composite negative electrode active material. In some embodiments, the silicon-based active material of the first dry negative electrode film and the second dry negative electrode film can include a silicon composite structure. The content of the composite (GB) and the binder in the first dry negative electrode film can be equal to or greater than the content of the composite (GB) and the binder in the second dry negative electrode film.

[0119] The content of the carbon-based material and the silicon-based active material in the first dry negative electrode film can be equal to or greater than the content of the carbon-based material and the silicon-based active material in the second dry negative electrode film.

[0120] A structure of a dry negative electrode-separator subassembly using a dry negative electrode film according to an embodiment will be described with reference to the accompanying drawings.

[0121] Referring to Figure 3a , the dry negative electrode-separator subassembly 200 includes a first dry negative electrode film 20a stacked on the negative electrode current collector 20, a second dry negative electrode film 20b on the first dry negative electrode film 20a, and a separator 4 stacked on the second dry negative electrode film 20b.

[0122] Figure 3b The dry negative electrode-separator subassembly 200 shown in FIG. 1A is different from the embodiment of FIG. 1B in that an intermediate layer 30 is disposed between the negative electrode current collector 20 and the first dry negative electrode film 20a. Figure 3a

[0123] Figure 4a to Figure 4c A stacked structure of a dry negative electrode according to an embodiment is shown, and specifically, components of a first dry negative electrode film and a second dry negative electrode film are shown.

[0124] According to an embodiment, as shown in FIG. 1A, the first dry negative electrode film 20a can include: a negative active material as a first negative active material, in which a shell containing a composite (GB1) is coated on graphite as a carbon-based material; a silicon composite structure (SCN) as a second negative active material; and polytetrafluoroethylene (PTFE1) as a dry binder. The second dry negative electrode film 20b can include: a negative active material as a first negative active material, in which a shell containing a composite (GB2) is coated on graphite; a silicon composite structure (SCN) as a second negative active material; and polytetrafluoroethylene (PTFE2) as a dry binder. Figure 4a The silicon composite structure can be: a silicon-carbon composite including silicon particles and a first carbon-based material; a silicon-carbon composite including a core in which silicon particles and a second carbon-based material are mixed and a third carbon-based material surrounding the core; or a combination thereof.

[0125] The contents of PTFE1 and GB1 of the first dry negative electrode film 20a can be adjusted to be equal to or greater than the contents of PTFE2 and GB2 of the second dry negative electrode film 20b (PTFE1 ≥ PTFE2, GB1 ≥ GB2), respectively. Within these ranges, peeling of the dry negative electrode film from the negative electrode current collector can be effectively prevented, and lithium dendrites can be induced to grow less in a direction away from the negative electrode current collector.

[0126] The mixed weight ratio of PTFE1 and PTFE2 is not limited and can be 10:1 to 1.1:1, 9.5:1 to 1.3:1, 9:1 to 1.5:1, 9:1 to 1.5:1, 6:1 to 1.5:1, 5:1 to 1.8:1, or 4:1 to 2:1.

[0127] The mixed weight ratio of GB1 and GB2 is not limited and can be 10:1 to 1.1:1, 9.5:1 to 1.3:1, 9:1 to 1.5:1, 9:1 to 1.5:1, 6:1 to 1.5:1, 5:1 to 1.8:1, or 4:1 to 2:1.

[0128]

[0129] ​​Based on a total content of 100 parts by weight of graphite and silicon composite structure, the content of silicon composite structure in the first dry negative electrode film and the content of silicon composite structure in the second dry negative electrode film can be from about 5 parts by weight to about 20 parts by weight, from about 11 parts by weight to about 18 parts by weight, or from about 12 parts by weight to about 15 parts by weight.

[0130] According to the embodiments, such as Figure 4b As shown, the first dry negative electrode film 20a may include: a composite negative electrode active material containing a compound (GB1) coated on graphite as a first negative electrode active material; a silicon composite structure (SCN1) as a second negative electrode active material; and polytetrafluoroethylene (PTFE1) as a dry binder. The second dry negative electrode film 20b may include: a composite negative electrode active material containing a compound (GB2) coated on graphite as a first negative electrode active material; a silicon composite structure (SCN2) as a second negative electrode active material; and polytetrafluoroethylene (PTFE2) as a dry binder.

[0131] The SCN1 content in the first dry negative electrode film can be adjusted to be greater than the SCN2 content in the second dry negative electrode film. If the SCN1 content is adjusted to be greater than the SCN2 content, then the PTFE1 and GB1 contents of the first dry negative electrode film can be adjusted to be equal to or greater than the PTFE2 and GB2 contents of the second dry negative electrode film, respectively (SCN1>SCN2, PTFE1≥PTFE2, GB1≥GB2). Within these ranges, volume expansion of the dry negative electrode film can be suppressed, and less lithium dendrite growth can be induced in the direction away from the current collector.

[0132] The mixing weight ratio of the SCN1 content of the first dry negative electrode film and the SCN2 content of the second dry negative electrode film is not limited, and can be 10:1 to 1.1:1, 9.5:1 to 1.3:1, 9:1 to 1.5:1, 9:1 to 1.5:1, 6:1 to 1.5:1, 5:1 to 1.8:1, or 4:1 to 2:1.

[0133] If the silicon content of the first dry negative electrode film is greater than that of the second dry negative electrode film, the electrode expansion rate is reduced, lithium dendrite formation is decreased during fast charging, electrolyte intrusion is improved, electrode detachment is reduced, and high electrode stability can be achieved using a smaller amount of binder. In some embodiments, if the PTFE1 and GB1 contents of the first dry negative electrode film are equal to or greater than the PTFE2 and GB2 contents of the second dry negative electrode film, respectively, the dry negative electrode film can be effectively prevented from peeling off from the negative electrode current collector, and less lithium dendrite growth can be induced in the direction away from the current collector.

[0134] According to some embodiments, such as Figure 4cAs shown in FIG. 1, the second dry negative electrode film 20b disposed farther from the negative electrode current collector 20 can include: a first composite negative electrode active material including a graphite core / composite (GB2) shell as a negative electrode active material; and PTFE2 as a binder, and the first dry negative electrode film 20a disposed adjacent to the negative electrode current collector 20 can include: a first composite negative electrode active material in which a shell including a composite (GB1) is coated on graphite as a dry composite negative electrode active material; a second composite negative electrode active material including a silicon composite structure (SCN) as a core / a composite (GB1) as a shell; and PTFE1 as a binder.

[0135] The total content of graphite and the silicon composite structure (SCN) of the first dry negative electrode film can be adjusted to be greater than the total content of graphite of the second dry negative electrode film.

[0136] The mixed weight ratio of the total content of graphite and the silicon composite structure (SCN) in the first dry negative electrode film to the content of graphite in the second dry negative electrode film is not limited, and can be 10:1 to 1.1:1, 9.5:1 to 1.3:1, 9:1 to 1.5:1, 9:1 to 1.5:1, 6:1 to 1.5:1, 5:1 to 1.8:1, or 4:1 to 2:1.

[0137] For example, in the first composite negative electrode active material, the content of the composite (GB1) can be adjusted to be equal to or greater than the content of the composite (GB2), and the content of PTFE1 as a binder can be adjusted to be equal to or greater than the content of PTFE2 as a binder (PTFE1≥PTFE2, GB1≥GB2). By forming such a structure, control of volume expansion and smaller growth of lithium dendrites in a direction farther than the current collector can be achieved.

[0138] In the embodiments described in Figure 4b and Figure 4c The mixed weight ratio of PTFE1 and PTFE2 and the mixed weight ratio of GB1 and GB2 described in the embodiments described in Figure 4a are the same as those described in

[0139] Figure 4a to Figure 4c The first dry negative electrode film and the second dry negative electrode film of the embodiment of Figure 4c may further include an electrically conductive material. For example, The second dry negative electrode film of the embodiment of may include a first composite negative electrode active material including a graphite core / composite (GB1) shell as a negative electrode active material and PTFE1 as a binder, and the second dry negative electrode film can further include an electrically conductive material. A composite (GB) or the like can be used as the electrically conductive material. In some embodiments, since the composite (GB) is the same as the composite including the first carbon-based material and at least one first metal oxide constituting the shell, a description thereof will be omitted.

[0140] The thickness of each of the first dry negative electrode film and the second dry negative electrode film included in the dry negative electrode including the above-described dry negative electrode film can be formed in a ratio of 1:3 to 3:1, 1:2 to 2:1, or 1:1.

[0141] According to an embodiment, the dry negative electrode film can have a multi-layer structure of 2 layers or more, 2 to 5 layers, or 2 to 3 layers, and can be used to form a thick film.

[0142] The term "solvent-free" used herein means components excluding any amount of residual process solvent to operate properly. According to an embodiment, the dry negative electrode film can be a self-standing film, and can be free of residual process solvent.

[0143] The dry negative electrode film according to an embodiment can have a tensile strength of, for example, 450 kPa or more, 500 kPa or more, 700 kPa or more, or 1000 kPa or more at 25℃. The tensile strength can be a tensile strength before pressing. The tensile strength of the dry negative electrode film before pressing at 25℃ can be, for example, about 500 kPa to about 5000 kPa, about 600 kPa to about 5000 kPa, about 700 kPa to about 5000 kPa, or about 800 kPa to about 5000 kPa.

[0144] The tensile strength of the dry negative electrode film after pressing at 25℃ can be 1000 kPa or more, 1050 kPa or more, 1200 kPa or more, or 1500 kPa or more. The tensile strength of the dry negative electrode film after pressing at 25℃ can be, for example, about 1000 kPa to about 5000 kPa, about 1050 kPa to about 5000 kPa, about 1090 kPa to about 5000 kPa, about 1200 kPa to about 5000 kPa, or about 1800 kPa to about 5000 kPa. Within these ranges of the tensile strength, the structural stability of the dry negative electrode film can be increased. Accordingly, the dry negative electrode film maintains a stable three-dimensional conductive network during charging and discharging, and thus the reversibility of the electrode reaction can be improved. Within these ranges of the tensile strength, the mechanical strength of the dry negative electrode film can be improved. Since the dry negative electrode film has improved mechanical strength, local degradation due to volume change of the electrode having the dry negative electrode film and the lithium battery including the same during charging and discharging can be suppressed. As a result, the cycle characteristics of the lithium battery can be improved.

[0145] The dry negative electrode film can provide improved cycle characteristics and reduced volume change due to the inclusion of the dry negative electrode active material.

[0146] In some embodiments, the method of preparing the dry negative electrode includes: preparing a dry mixture by dry mixing a dry composite negative electrode active material and a dry binder; providing a negative electrode current collector, disposing an intermediate layer on one surface of the negative electrode current collector, and disposing the dry mixture on the intermediate layer and pressing to obtain a dry negative electrode film; and preparing a negative electrode in which a negative electrode active material layer is disposed on one surface of a negative electrode current collector.

[0147] First, a dry mixture can be prepared by dry mixing a negative electrode active material and a dry binder.

[0148] During preparation of the dry mixture, a dry conductive material can also be included.

[0149] Dry mixing refers to mixing that can be performed without including a process solvent. The process solvent can be, for example, a solvent used to prepare an electrode slurry. The process solvent can be, for example, water, NMP, etc., but is not limited thereto, and any process solvent used to prepare an electrode slurry can be used herein. Dry mixing can be performed using a stirrer at a temperature of, for example, 25 to 65°C. Dry mixing can be performed using a stirrer at a rotation speed of, for example, about 10 rpm to about 10,000 rpm or about 100 rpm to about 10,000 rpm. Dry mixing can be performed using a stirrer for, for example, about 1 minute to about 200 minutes or about 1 minute to about 150 minutes. The composite negative electrode active material can be a dry composite negative electrode active material.

[0150] Dry mixing can be performed, for example, at least once. First, a first mixture can be prepared by primary dry mixing of a dry composite negative electrode active material and a dry binder. During preparation of the first mixture, a dry conductive material can also be added. The primary dry mixing can be performed at a temperature of, for example, about 25 to about 65°C at a rotation speed of 2,000 rpm or less or about 500 rpm to about 2,000 rpm for 15 minutes or less, for example, about 5 minutes to about 15 minutes. The dry composite negative electrode active material and the dry binder can be uniformly mixed by the primary dry mixing. Subsequently, a second mixture can be prepared by secondary dry mixing of the dry composite negative electrode active material and the dry binder. In some embodiments, the secondary dry mixing can be performed at a temperature of 25 to 65°C at a rotation speed of 4,000 rpm or more or about 4,000 rpm to about 9,000 rpm for 10 minutes or more or about 10 minutes to about 60 minutes. A dry mixture including a fibrillated dry binder can be obtained by the secondary dry mixing.

[0151] The stirrer can be, for example, a kneader. In some embodiments, the stirrer can include a chamber, one or more rotating shafts located inside the chamber and rotatable, and blades rotatably coupled to the rotating shafts and positioned in the longitudinal direction of the rotating shafts. The blades can be, for example, one or more selected from ribbon blades, sigma blades, jet (Z) blades, dispersion blades, and helical blades. Since the blades are included, a dough-like mixture can be prepared by effectively mixing the dry negative electrode composite active material, the dry conductive material, and the dry binder even without a solvent.

[0152] The prepared dry mixture can be put into an extrusion device and extruded into a sheet form. The pressure at the time of extrusion can be, for example, about 4 MPa to about 100 MPa or about 10 MPa to about 90 MPa. The obtained extruded product in a sheet form can be a sheet for a negative electrode active material layer, for example, a dry negative electrode film. By repeating the process, a dry negative electrode film having a multi-layer structure can be easily manufactured.

[0153] As the dry conductive material, carbon black, graphite fine particles, natural graphite, artificial graphite, acetylene black, ketjen black, carbon fibers, carbon nanotubes, metal powders of, for example, copper, nickel, aluminum, or silver, metal fibers or metal tubes, or conductive polymers such as polyaniline derivatives can be used, but embodiments of the present disclosure are not limited thereto. Any conductive material can be used as long as it is used in the art. The dry conductive material can be, for example, a carbon-based conductive material, which can be the same as the carbon-based conductive material in the intermediate layer described below. The dry conductive material can be a conductive material that is not in contact with a process solvent.

[0154] According to embodiments, the dry binder includes a fluorine-based binder.

[0155] The dry binder can be a vinylidene fluoride / hexafluoropropylene copolymer, a polyvinylidene fluoride, a polyacrylonitrile, a polymethyl methacrylate, a polytetrafluoroethylene (PTFE), a mixture of these polymers, a styrene butadiene rubber-based polymer, or the like. However, the binder and the solvent are not limited thereto and can be any binder or solvent used in the art. The dry binder can be, for example, a polytetrafluoroethylene (PTFE). The dry binder is a binder that is not in contact with a process solvent.

[0156] In some embodiments, the dry binder can be a fibrillated binder. The term "fibrillation" as used herein refers to a process of converting fibers of a material into individual units of the material that are smaller than the fibers, for example, by grinding or pulverizing. In one embodiment, the dry binder can have a glass transition temperature (Tg) of about 15 °C to about 100 °C. The content of the dry binder included in the dry negative electrode film can be, for example, about 0.1 wt% to about 5 wt% based on the total weight of the dry negative electrode film.

[0157] A plasticizer or a pore-forming agent can be added to the dry mixture to form pores in the negative active material layer.

[0158] The contents of the dry composite negative active material, the dry conductive material, and the dry binder used in the negative active material layer can be used in the same range as the contents in the wet negative electrode manufacturing. Next, a negative current collector is provided.

[0159] Although not shown in the drawings, the negative current collector can include, for example, a base film and a metal layer disposed on one side or both sides of the base film. The base film can include, for example, a polymer. For example, the polymer can be a thermoplastic polymer. The polymer can include, for example, polyethylene terephthalate (PET), PE, PP, polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. Due to the inclusion of the thermoplastic polymer in the base film, the base film is liquefied in the case of a short circuit, and thus a rapid increase in current can be prevented. For example, the polymer can be an insulator. The metal layer can include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

[0160] The metal layer can function as an electrochemical fuse by being broken in the case of overcurrent, thereby providing protection against short circuits. The limit current and the peak current can be controlled by controlling the thickness of the metal layer. The metal layer can be plated or deposited on the base film. As the thickness of the metal layer decreases, the limit current and / or the peak current of the negative current collector also decrease, and thus, the lithium battery can have improved stability during a short circuit. A lead tab can be added on the metal layer for external connection. The lead tab can be welded to the metal layer or the metal layer / base film stack by ultrasonic welding, laser welding, spot welding, or the like. The metal layer can be electrically connected to the lead tab when the base film and / or the metal layer are melted during welding. To further secure the welding between the metal layer and the lead tab, a metal sheet can be added between the metal layer and the lead tab. The metal sheet can be a small piece of the same material as the metal of the metal layer. For example, the metal sheet can be a metal foil, a metal mesh, or the like. For example, the metal sheet can be an aluminum foil, a copper foil, a SUS foil, or the like. By welding the lead tab after placing the metal sheet on the metal layer, the lead tab can be welded to the metal sheet / metal layer stack or the metal sheet / metal layer / base film stack. The metal layer or the metal layer / metal sheet stack can be electrically connected to the lead tab when the base film, the metal layer, and / or the metal sheet are melted during welding. The metal sheet and / or the lead tab can be further added to a portion of the metal layer. The base film can have a thickness of, for example, about 1 µm to about 50 µm, about 1.5 µm to about 50 µm, about 1.5 µm to about 40 µm, or about 1 µm to about 30 µm. If the base film has a thickness within the above range, a reduction in the weight of the electrode assembly can be more effectively achieved. The base film can have a melting point of, for example, about 100 °C to about 300 °C, about 100 °C to about 250 °C, or about 100 °C to about 200 °C. Since the base film has a melting point within the above range, the base film can be melted and easily joined to the lead tab during a process of welding the lead tab. To improve the adhesion strength between the base film and the metal layer, the base film can be subjected to surface treatment such as corona treatment. The metal layer can have a thickness of, for example, about 0.01 µm to about 3 µm, about 0.1 µm to about 3 µm, about 0.1 µm to about 2 µm, or about 0.1 µm to about 1 µm. If the metal layer has a thickness within the above range, the stability of the electrode assembly can be secured while maintaining electrical conductivity. The metal sheet can have a thickness of, for example, about 2 µm to about 10 µm, about 2 µm to about 7 µm, or about 4 µm to about 6 µm. Since the metal sheet has a thickness within the above range, the connection between the metal layer and the lead tab can be more easily performed. Because the negative current collector has such a structure, the weight of the electrode can be reduced, so that the energy density is improved.

[0161] The negative current collector can be, for example, an aluminum foil.

[0162] Next, an intermediate layer can be provided on at least one surface of the negative current collector. The intermediate layer can include a carbon-based conductive material and a binder. The intermediate layer can be omitted.

[0163] The carbon-based conductive material can be or include a fibrous carbon-based material, a particulate carbon-based material, or a combination thereof. The fibrous carbon-based material can have an aspect ratio greater than or equal to 10, for example, about 10 to about 100,000, about 10 to about 80,000, about 10 to about 50,000, about 10 to about 10,000, and can be about 10,000, about 10 to about 5000, about 10 to about 1000, about 10 to about 500, about 10 to about 100, or about 10 to about 50. The particulate carbon-based material can have an aspect ratio less than 10.

[0164] Next, the dry negative electrode film, which is a sheet for a negative active material layer, can be provided on the intermediate layer, and then pressed, thereby preparing a negative electrode in which the negative active material layer is provided on one side of the negative current collector. The intermediate layer can be provided between the negative current collector and the negative active material layer.

[0165] The pressing can be, for example, roll pressing, flat pressing, etc., but is not necessarily limited thereto. The pressure during the pressing can be, for example, about 0.1 ton / cm 2 to about 10.0 ton / cm 2 but is not limited to this range. If the pressure during the pressing is excessively increased, cracks can be generated in the negative current collector. If the pressure during the pressing is too low, the adhesion strength between the negative current collector and the negative active material layer can be deteriorated.

[0166] The lithium battery according to the embodiments can use a negative electrode including the dry negative electrode film described above.

[0167] The lithium battery using the negative electrode can have improved interfacial resistance, improved cycle characteristics, and reduced volume change.

[0168] The lithium battery can be manufactured by the following example method, but embodiments of the disclosure are not limited to this method, and the method can be controlled according to the desired conditions.

[0169] First, a dry negative electrode can be manufactured according to the negative electrode manufacturing method described above.

[0170] Next, a positive active material composition in which a positive active material, a conductive material, a binder, and a solvent are mixed can be prepared. The positive active material composition can be directly coated on a positive current collector and dried to prepare a positive electrode plate. In some embodiments, after the positive active material composition is cast on a separate support, the film separated from the support can be stacked on an aluminum current collector to manufacture a positive electrode plate.

[0171] The positive electrode active material can be a lithium-containing metal oxide, and any material generally used in the art can be used without limitation. As the positive electrode active material, for example, at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof can be used. The positive electrode active material can include, for example, at least one selected from lithium cobalt oxide, lithium nickel cobalt manganese oxide, lithium nickel cobalt aluminum oxide, lithium iron phosphate, and lithium manganese oxide, but is not limited thereto. The positive electrode active material can be any material used in the art as a positive electrode active material for a lithium battery.

[0172] The positive electrode active material can include, for example, a compound represented by one of the following formulas: a A 1-b B b D2(wherein, 0.90≤a≤1.8 and 0≤b≤0.5); Li a E 1-b B b O 2-c D c (wherein, 0.90≤a≤1.8, 0≤b≤0.5 and 0≤c≤0.05); LiE 2-b B b O 4-c D c (wherein, 0≤b≤0.5 and 0≤c≤0.05); Li a Ni 1-b-c Co b B c D α (wherein, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α≤2); Li a Ni 1-b-c Co b B c O 2-α F α (wherein, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2); Li a Ni 1-b-c Co b B c O 2-α F2(wherein, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α<2); Li a Ni 1-b-c Mn b B c D α (wherein, 0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05 and 0<α≤2); Li a Ni 1-b-c Mn b Bc O 2-α F α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni 1-b- c Mn b B c O 2-α F2(0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.05, 0<α<2); Li a Ni b E c G d O2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0.001≤d≤0.1); Li a Ni b Co c Mn d GeO2(0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, 0.001≤e≤0.1); Li a NiG 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 MnG b O2(0.90≤a≤1.8, 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1.8, 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0≤f≤2); Li (3-f) Fe2(PO4)3(0≤f≤2); and LiFePO4.

[0173] In the above formula, A can be Ni, Co, Mn, or a combination thereof; B can be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D can be O, F, S, P, or a combination thereof; E can be Co, Mn, or a combination thereof; F can be F, S, P, or a combination thereof; G can be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q can be Ti, Mo, Mn, or a combination thereof; I can be Cr, V, Fe, Sc, Y, or a combination thereof; and J can be V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0174] A compound having a coating layer added to the surface of the above compound can also be used. In addition, a mixture of the above compound and a compound having a coating layer added thereto can also be used. The coating layer added to the surface of the above compound can include, for example, a compound of a coating element such as an oxide and a hydroxide of a coating element, a hydroxyl oxide of a coating element, an oxy carbonate of a coating element, and a hydroxyl carbonate of a coating element. The compound forming the above coating layer can be amorphous or crystalline. The coating element included in the coating layer can be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method of forming the coating layer can be selected from a method that does not adversely affect the physical properties of the positive electrode active material. Examples of the coating method can include spraying, dipping, and the like. The specific type of such a coating method is well known to one of ordinary skill in the art, and a detailed description of such a method will be omitted.

[0175] The positive electrode active material can be, for example, LiNiO2, LiCoO2, LiMn x O 2x (x = 1, 2), LiNi 1-x Mn x O2(0 < x < 1), LiNi 1-x-y Co x Mn y O2(0 ≤ x ≤ 0.5, 0 ≤ y ≤ 0.5), LiFeO2, V2O5, TiS, MoS, or the like.

[0176] In some embodiments, the positive electrode active material can have one of the following formulas: Li a Ni x Co y M z O 2-b A b(1.0 < a < 1.2, 0 < b < 0.2, 0.8 < x < 1, 0 < y < 0.3, 0 < z < 0.3, x + y + z = 1, M can be at least one selected from the group consisting of manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), and boron (B), and A can be F, S, Cl, Br, or a combination thereof), LiNi x Co y Mn z O2(0.8 < x < 0.95, 0 < y < 0.2, 0 < z < 0.2 and x + y + z = 1), LiNi x Co y Al z O2(0.8 < x < 0.95, 0 < y < 0.2, 0 < z < 0.2 and x + y + z = 1), LiNi x Co y Al v Mn w O2(0.8 < x < 0.95, 0 < y < 0.2, 0 < v < 0.2, 0 < w < 0.2 and x + y + v + w = 1), and Li a Ni x Mn y M' z O 2-b A b (1.0 < a < 1.2, 0 < b < 0.2, 0 < x < 0.3, 0.5 < y < 1, 0 < z < 0.3 and x + y + z = 1, M' can be cobalt (Co), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof, and A can be F, S, Cl, Br, or a combination thereof).

[0177] The conductive material, the binder, and the solvent for the positive active material composition can be the same as those for the negative active material. In some embodiments, by further adding a plasticizer to the positive active material composition and / or the negative active material composition, pores can be formed inside the electrode plate.

[0178] The contents of the positive active material, the conductive material, the binder, and the solvent can be at levels commonly used in lithium batteries. At least one of the conductive material, the binder, and the solvent can be omitted depending on the use and configuration of the lithium battery.

[0179] In some embodiments, the content of the binder included in the cathode can be about 0.1 wt% to about 10 wt%, or about 0.1 wt% to about 5 wt% of the total weight of the cathode active material layer. In some embodiments, the content of the conductive material included in the cathode can be about 0.1 wt% to about 10 wt% or about 0.1 wt% to about 5 wt% of the total weight of the cathode active material layer. In some embodiments, the content of the cathode active material included in the cathode can be about 70 wt% to about 99 wt%, about 90 wt% to about 99 wt%, or about 95 wt% to about 99 wt% of the total weight of the cathode active material layer.

[0180] For example, the cathode current collector can include a base film and a metal layer disposed on one side or both sides of the base film. The base film can include, for example, a polymer. For example, the polymer can include polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. For example, the metal layer can include indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. Due to the cathode current collector having such a structure, the weight of the electrode can be reduced, and as a result, the energy density of the lithium battery can be improved.

[0181] Next, a separator interposed between the cathode and the anode can be prepared.

[0182] For the separator, any one of those commonly used in lithium batteries can be used. As the separator, for example, any separator having low resistance to ion migration of the electrolyte and excellent ability to absorb the electrolyte can be used. The separator can be a non-woven fabric or a woven fabric including at least one selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), and combinations thereof. For a lithium ion battery, a separator that can be wound, such as polyethylene and polypropylene, can be used, and for a lithium ion polymer battery, a separator having excellent organic electrolyte solution wetting ability can be used.

[0183] The separator can be manufactured by the following exemplary method, but embodiments of the present disclosure are not necessarily limited to the method, and the method is adjusted according to the required conditions.

[0184] First, a separator composition can be prepared by mixing a polymer resin, a filler, and a solvent. The separator composition can be coated directly on the electrode and dried to form a separator. In some embodiments, after the separator composition is cast on a support and dried, the separator peeled off from the support can be stacked on the electrode to form a separator.

[0185] The polymer used to manufacture the separator is not particularly limited, and any polymer used for the binder of the electrode plate can be used. For example, the polymer can utilize a vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or a mixture thereof.

[0186] Next, an electrolyte can be prepared.

[0187] The electrolyte can be, for example, an organic electrolyte solution. The organic electrolyte solution can be prepared by dissolving a lithium salt in an organic solvent.

[0188] For the organic solvent, any organic solvent available in the art can be used. Examples of the organic solvent can include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or a mixture thereof.

[0189] The lithium salt can be any lithium salt available in the art, and the lithium salt can be, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(FSO2)2N, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+ 1SO2)(C y F 2y+1 SO2) (1≤x≤20, 1≤y≤20), LiCl, LiI, or a mixture thereof.

[0190] In some embodiments, the electrolyte can be a solid electrolyte. The solid electrolyte can be, for example, boron oxide, lithium oxy-nitride, etc., but is not limited thereto, and any solid electrolyte used in the art can be used herein. The solid electrolyte can be formed on the negative electrode by a method such as sputtering, or a separate solid electrolyte sheet can be stacked on the negative electrode.

[0191] The solid electrolyte can be, for example, an oxide-based solid electrolyte or a sulfide-based solid electrolyte.

[0192] For example, the solid electrolyte can be an oxide-based solid electrolyte. The oxide-based solid electrolyte can be selected from Li 1+x+y Al x Ti 2-x Siy P 3-y O 12 (0 < x < 2, 0 ≤ y < 3), BaTiO3, Pb(Zr, Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT) (0 ≤ x < 1, 0 ≤ y < 1), Pb(Mg3Nb 2 / 3 )O3-PbTiO3 (PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3 (0 < x < 2, 0 < y < 3), Li x Al y Ti z (PO4)3 (0 < x < 2, 0 < y < 1, 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0 ≤ x ≤ 1, 0 ≤ y ≤ 1), Li x La y TiO3 (0 < x < 2, 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (M = Te, Nb, or Zr, and x can be an integer from 1 to 10). The solid electrolyte can be prepared by a sintering method or the like. For example, the oxide-based solid electrolyte can be a garnet-type solid electrolyte selected from Li7La3Zr2O 12 (LLZO) and Li 3+x La3Zr 2-a M a O 12 (M-doped LLZO, M = Ga, W, Nb, Ta, or Al, and x is an integer from 1 to 10, 0 < a < 2).

[0193] Examples of sulfide-based solid electrolytes can include lithium sulfide, silicon sulfide, phosphorus sulfide, boron sulfide, or combinations thereof. The sulfide-based solid electrolyte particles can include Li2S, P2S5, SiS2, GeS2, B2S3, or combinations thereof. The sulfide-based solid electrolyte particles can be Li2S or P2S5. Sulfide-based solid electrolyte particles are known to have higher lithium ion conductivity than other inorganic compounds. For example, the sulfide-based solid electrolyte can include Li2S and P2S5. If the sulfide solid electrolyte material constituting the sulfide-based solid electrolyte includes Li2S-P2S5, the mixed molar ratio of Li2S and P2S5may be, for example, in the range of about 5:50 to about 90:10. In some embodiments, by adding Li3PO4, halogen, halogen compound, Li2O, LiI, LiBr, LiCl, LiF, Li3PO4, or combinations thereof to the inorganic solid electrolyte of Li2S-P2S5, SiS2, GeS2, B2S3, or combinations thereof, the sulfide solid electrolyte material can be prepared. 2+2x Zn 1-x GeO4 (“LISICON”, 0≤x<1), Li 3+y PO 4-x N x (“LIPON”, 0 3.25 Ge 0.25 P 0.75 S4 (“thio-LISICON”), Li2O-Al2O3-TiO2-P2O5 (“LATP”), and the like can be used as the sulfide solid electrolyte. Non-limiting examples of the sulfide solid electrolyte material can include: Li2S-P2S5; Li2S-P2S5-LiX (X = halogen element); Li2S-P2S5-Li2O; Li2S-P2S5-Li2O-LiI; Li2S-SiS2; Li2S-SiS2-LiI; Li2S-SiS2-LiBr; Li2S-SiS2-LiCl; Li2S-SiS2-B2S3-LiI; Li2S-SiS2-P2S5-LiI; Li2S-B2S3; Li2S-P2S5-Z m S n (0 < m < 10, 0 < n < 10, Z = Ge, Zn, or Ga); Li2S-GeS2; Li2S-SiS2-Li3PO4; and Li2S-SiS2-Li p MO q(0 < p < 10, 0 < q < 10, and M = P, Si, Ge, B, Al, Ga, or In). In this regard, the sulfide-based solid electrolyte material can be prepared by performing a process such as melt-quenching, mechanical milling, or the like on starting materials (e.g., Li2S, P2S5, etc.) of the sulfide-based solid electrolyte material. In some embodiments, a calcination process can be performed after the above-described process. The sulfide-based solid electrolyte can be amorphous or crystalline, or can be in a mixed state thereof.

[0194] In some embodiments, referring to Figure 5 , the lithium battery 1 includes a positive electrode 3, a negative electrode 2, and a separator 4. The positive electrode 3, the negative electrode 2, and the separator 4 can be wound or stacked to form a battery structure 7. The battery structure 7 thus formed can be accommodated in a battery case 5. An organic electrolyte can be injected into the battery case 5 and sealed with a cap assembly 6 to complete the manufacture of the lithium battery 1. The battery case 5 can have a cylindrical shape, but is not necessarily limited thereto, and can have a polygonal shape, a film shape, or the like.

[0195] Referring to Figure 6 , the lithium battery 1 according to an embodiment can include a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 can be located between the positive electrode 3 and the negative electrode 2, and the positive electrode 3, the negative electrode 2, and the separator 4 can be wound or stacked to form a battery structure 7. The battery structure 7 thus formed can be accommodated in a battery case 5. An electrode tab 8 serving as an electrical path for guiding an electric current generated in the battery structure 7 to the outside can be included. An organic electrolyte can be injected into the battery case 5 and sealed to complete the manufacture of the lithium battery 1. The battery case 5 can have a polygonal shape, but is not necessarily limited thereto, for example, the battery case 5 can also have a cylindrical shape, a film shape, or the like.

[0196] Referring to Figure 7 , the lithium battery 1 according to an embodiment can include a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 can be located between the positive electrode 3 and the negative electrode 2 to form a battery structure. The battery structure 7 can be stacked in a dual-cell structure and then accommodated into a battery case 5. An electrode tab 8 serving as an electrical path for guiding an electric current generated in the battery structure 7 to the outside can be included. An organic electrolyte can be injected into the battery case 5 and sealed to complete the manufacture of the lithium battery 1. The battery case 5 can have a polygonal shape, but is not necessarily limited thereto, for example, the battery case 5 can also have a cylindrical shape, a film shape, or the like.

[0197] A pouch-type lithium battery corresponds to a battery in which Figure 5 to Figure 7A pouch-type lithium battery can include one or more battery structures. A separator can be located between a positive electrode and a negative electrode to form a cell structure. After the battery structures are stacked into a double cell structure, the resulting structure is wetted by an organic electrolyte solution, and then housed and sealed by a pouch, thereby completing the manufacturing of the pouch-type lithium battery. For example, although not shown in the drawings, a positive electrode, a negative electrode, and a separator can be simply stacked and housed in a pouch in the form of an electrode assembly. In some embodiments, a positive electrode, a negative electrode, and a separator can be wound or stacked in the form of a pole core into an electrode assembly, and then housed in a pouch. Then, an organic electrolyte solution can be injected into the pouch, and then the pouch is sealed to complete the manufacturing of the lithium battery.

[0198] Lithium batteries can have excellent life characteristics and high rate characteristics, and thus they are used, for example, in electric vehicles (EVs). For example, lithium metal batteries can be used in hybrid electric vehicles, such as plug-in hybrid electric vehicles (PHEVs), etc. In addition, lithium metal batteries can be used in any field requiring a large amount of energy storage. For example, lithium metal batteries can be used in electric bicycles, power tools, etc.

[0199] A plurality of lithium batteries can be stacked to form a battery module, and a plurality of battery modules can form a battery pack. Such a battery pack can be used in all types of devices requiring high capacity and high output. For example, a battery pack can be used in a laptop computer, a smart phone, an electric vehicle, etc. A battery module can include, for example, a plurality of batteries and a frame holding the batteries. A battery pack can include, for example, a plurality of battery modules and bus bars connecting the battery modules. A battery module and / or a battery pack can further include a cooling device. A plurality of battery packs can be controlled by a battery management system. The battery management system can include a battery pack and a battery control device connected to the battery pack.

[0200] In some embodiments, the dry negative electrode includes: an electrode current collector; and a dry negative electrode film disposed on one or both sides of the electrode current collector.

[0201] Because the dry negative electrode includes the dry negative electrode film, the internal resistance of the dry negative electrode is reduced and the mechanical properties are improved.

[0202] The electrode current collector can include, for example, a substrate.

[0203] The material constituting the substrate can be a material that does not react with lithium (e.g., a material that does not form an alloy or a compound with lithium), and can be any material having electrical conductivity. The substrate can be, for example, a metal or an alloy. The substrate can include, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel (SUS), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), or alloys thereof. The substrate can be in a form selected from, for example, a sheet, a foil, a film, a plate, a porous material, a mesoporous material, a material having a through-hole, a polygonal ring material, a mesh material, a foamed material, and a non-woven material, and is not limited thereto. The substrate can have any form available in the art.

[0204] In some embodiments, the electrode current collector can include, for example, a substrate and an intermediate layer disposed between the substrate and the dry negative electrode film. The intermediate layer can include, for example, a carbon-based conductive material.

[0205] In some embodiments, the intermediate layer can be directly disposed on one side or both opposite sides of the substrate. In some embodiments, no other layer can be disposed between the substrate and the intermediate layer. Because the intermediate layer is directly disposed on one side or both opposite sides of the substrate, the bonding force between the substrate and the dry negative electrode film can be further improved.

[0206] The thickness of the intermediate layer can be, for example, about 0.01% to about 30%, about 0.1% to about 30%, about 0.5% to about 30%, about 1% to about 25%, about 1% to about 20%, about 1% to about 15%, about 1% to about 10%, about 1% to about 5%, or about 1% to about 3% of the thickness of the substrate. The thickness of the intermediate layer can be, for example, about 10 nm to about 5 μm, about 50 nm to about 5 μm, about 200 nm to about 4 μm, about 500 nm to about 3 μm, about 500 nm to about 2 μm, about 500 nm to about 1.5 μm, about 700 nm to about 1.3 μm. If the intermediate layer has a thickness in these ranges, the bonding force between the substrate and the dry negative electrode film can be further improved, and an increase in the interfacial resistance can be suppressed.

[0207] The intermediate layer can include, for example, a carbon-based conductive material. The carbon-based conductive material included in the intermediate layer can be selected from the carbon-based conductive materials used in the dry negative electrode film. The intermediate layer can include the same carbon-based conductive material as that used in the dry negative electrode film. Because the intermediate layer includes a carbon-based conductive material, the intermediate layer can be, for example, an electrically conductive layer.

[0208] The intermediate layer can additionally include, for example, a binder. Because the intermediate layer additionally includes a binder, the adhesion between the substrate and the dry negative electrode film can be further improved. The binder included in the intermediate layer can be, for example, an electrically conductive binder or a non-electrically conductive binder. The electrically conductive binder can be, for example, an ionically conductive binder and / or an electronically conductive binder. A binder having both ionically conductive and electronically conductive properties can belong to both ionically conductive binders and electronically conductive binders.

[0209] The binder included in the intermediate layer can be selected from among binders used in the dry negative electrode film. The intermediate layer can include the same binder as that used for the dry negative electrode film. The binder included in the intermediate layer can be, for example, a fluorine-based binder. The fluorine-based binder included in the intermediate layer can be, for example, polyvinylidene fluoride (PVDF). The intermediate layer can be, for example, an adhesive layer including a binder. The intermediate layer can be, for example, an electrically conductive layer including a binder and a carbon-based conductive material.

[0210] In some embodiments, the intermediate layer can be disposed on the substrate in a dry manner or in a wet manner. In some embodiments, the intermediate layer can be disposed on the substrate in a dry manner by vapor deposition, such as chemical vapor deposition (CVD), physical vapor deposition (PVD), or the like. In some embodiments, the intermediate layer can be disposed on the substrate in a wet manner by spin coating, dip coating, or the like. In some embodiments, the intermediate layer can be disposed on the substrate by depositing a carbon-based conductive material on the substrate by vapor deposition. The intermediate layer coated in a dry manner can include a carbon-based conductive material and can not include a binder. In some embodiments, the intermediate layer can be disposed on the substrate by coating a composition including a carbon-based conductive material, a binder, and a solvent on a surface of the substrate and drying. The intermediate layer can have a single layer structure or a multi-layer structure including a plurality of layers, and can have, for example, a two-layer structure, a three-layer structure, or a four-layer structure.

[0211] The dry negative electrode film included in the dry negative electrode corresponds to an electrode active material layer.

[0212] The dry negative electrode includes a dry negative electrode film, and the dry negative electrode film includes a dry negative electrode active material having a core / shell structure.

[0213] The dry negative electrode active material having a core / shell structure includes a core including a carbon-based material, a mixture of a carbon-based material and a silicon-based active material, a composite of a carbon-based material and a silicon-based active material, or a combination thereof, and a shell including a first metal oxide and a first carbon-based material.

[0214] In addition to the dry negative electrode active material having a core / shell structure, the dry negative electrode active material can additionally include dry negative electrode active materials in the art. The dry negative electrode active materials of the prior art can be used without limitation as long as they are commonly used in the art.

[0215] Any dry negative active material can be used as long as it is used as a negative active material for a lithium battery in the art. For example, at least one selected from the group consisting of lithium metal, metal alloyable with lithium, transition metal oxide, non-transition metal oxide, and carbon-based material can be included. Examples of the metal alloyable with lithium include Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloy (Y is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or a combination thereof, except for Si), and Sn-Y alloy (Y is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or a combination thereof, except for Sn). The element Y can be, for example, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof. The transition metal oxide can be, for example, lithium titanium oxide, vanadium oxide, lithium vanadium oxide, or the like. The non-transition metal oxide can be, for example, SnO2, SiO x (0 < x ≤ 2), and the like. The carbon-based material can be, for example, crystalline carbon, amorphous carbon, or a mixture thereof. For example, the crystalline carbon can be, for example, graphite (such as natural graphite or artificial graphite) in the form of amorphous, plate, sheet, spherical, or fibrous form. The amorphous carbon can be, for example, soft carbon (low-temperature calcined carbon) or hard carbon, mesophase pitch carbide, calcined coke, or the like.

[0216] As the positive active material, for example, at least one of a composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and a combination thereof can be used. Detailed examples thereof are described above.

[0217] The dry negative electrode can be, for example, a dry negative electrode. The dry negative electrode includes a dry negative electrode film, and the dry negative electrode film includes a dry negative active material.

[0218] In some embodiments, the lithium battery includes a first electrode, a second electrode, and an electrolyte disposed between the first electrode and the second electrode, wherein the first electrode, the second electrode, or a combination thereof is a dry negative electrode.

[0219] Because the lithium battery includes a dry negative electrode having reduced internal resistance and improved mechanical properties, the cycle characteristics of the lithium battery are improved.

[0220] In some embodiments, the lithium battery can include a dry negative electrode. In some embodiments, the lithium battery can include a dry negative electrode and a dry positive electrode. The lithium battery can include, for example, a dry negative electrode and a wet positive electrode, or can include a dry positive electrode and a wet negative electrode.

[0221] The lithium battery includes an electrolyte, and the electrolyte can include, for example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0222] The liquid electrolyte (e.g., electrolyte solution) can be an organic electrolyte solution. The organic electrolyte solution can be prepared by dissolving a lithium salt in an organic solvent.

[0223] For the organic solvent, any organic solvent available in the art can be used. Examples of the organic solvent can include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or a mixture thereof.

[0224] The lithium salt can be any lithium salt available in the art, and the lithium salt can be, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+ 1SO2) (x and y are natural numbers), LiCl, LiI, or a mixture thereof.

[0225] The solid electrolyte can include, for example, an inorganic solid electrolyte, an organic solid electrolyte, an organic / inorganic composite solid electrolyte, or a combination thereof.

[0226] The solid electrolyte can include, for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a polymer-based solid electrolyte, or a combination thereof.

[0227] The solid electrolyte is, for example, boron oxide, lithium oxy-nitride, etc., but is not limited thereto, and any solid electrolyte used in the art can be used herein. The solid electrolyte can be formed on the negative electrode by a method such as sputtering, or a separate solid electrolyte sheet can be stacked on the negative electrode.

[0228] The oxide-based solid electrolyte can include, for example, Li 1+x+y Al x Ti 2-x Si y P 3-y O 12(0 < x < 2, 0 < y < 3), BaTiO3, Pb(Zr, Ti)O3(PZT), Pb 1-x La x Zr 1-y Ti y O3(PLZT)(0 < x < 1, 0 < y < 1), Pb(Mg3Nb 2 / 3 )O3-PbTiO3(PMN-PT), HfO2, SrTiO3, SnO2, CeO2, Na2O, MgO, NiO, CaO, BaO, ZnO, ZrO2, Y2O3, Al2O3, TiO2, SiO2, Li3PO4, Li x Ti y (PO4)3(0 < x < 2, 0 < y < 3), Li x Al y Ti z (PO4)3(0 < x < 2, 0 < y < 1, 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (0 < x < 1, 0 < y < 1), Li x La y TiO3(0 < x < 2, 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O-Al2O3-SiO2-P2O5-TiO2-GeO2, Li 3+x La3M2O 12 (M = Te, Nb, or Zr, 0 < x < 10), Li 3+x La3Zr 2-y M y O 12 (M-doped LLZO, M = Ga, W, Nb, Ta, Al, or a combination thereof, 0 < x < 10, 0 < y < 2), Li7La3Zr 2-x Ta x O 12 (0 < x < 2, LLZ-Ta), or a combination thereof. The oxide-based solid electrolyte can be, for example, a garnet-type solid electrolyte. The oxide-based solid electrolyte can be manufactured by a sintering method or the like.

[0229] The oxide-based solid electrolyte can include, for example, Li7La3Zr2O 12 (LLZO), Li 6.5 La3Zr 1.5 Ta 0.5 O 12 , Li1.3 Al 0.3 Ti 1.7 (PO4)3, Li 0.34 La 0.51 TiO 2.94 , Li 1.07 Al 0.69 Ti 1.46 (PO4)3, 50Li4SiO4-50Li2BO3, 90Li3BO3-10Li2SO4, Li 2.9 PO 3.3 N 0.46 , or a combination thereof.

[0230] The sulfide-based solid electrolyte can be, for example, selected from Li2S-P2S5, Li2S-P2S5-LiX (where X is a halogen element), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are each a positive number, and Z is Ge, Zn, or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are each a positive number, and M is P, Si, Ge, B, Al, Ga, or In), Li 7-x PS 6-x Cl x (where 0≤x≤2), Li 7- x PS 6-x Br x (where 0≤x≤2), and Li 7-x PS 6-x I x (where 0≤x≤2). The sulfide-based solid electrolyte can be prepared by a method such as melt quenching, mechanical milling, or the like, by processing starting materials such as Li2S and P2S5. In some embodiments, after such processing, a heat treatment can be performed. The sulfide-based solid electrolyte can be amorphous or crystalline, or can be in a mixed state thereof.

[0231] For example, the sulfide-based solid electrolyte can include a argyrodite-type solid electrolyte represented by Formula 9: Formula 9 Li + 12-n-x A n+ X 2- 6-x Y - x In formula 9, A can be P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta, X can be S, Se, or Te, Y can be Cl, Br, I, F, CN, OCN, SCN, or N3, and 1 < n < 5 and 0 < x < 2 can be satisfied.

[0232] For example, the sulfide-based solid electrolyte can be a solid electrolyte including a argyrodite-type compound selected from Li 7-x PS 6-x Cl x (wherein, 0 ≤ x ≤ 2), Li 7- x PS 6-x Br x (wherein, 0 ≤ x ≤ 2), and Li 7-x PS 6-x I x (wherein, 0 ≤ x ≤ 2). For example, the sulfide-based solid electrolyte included in the solid electrolyte can be an argyrodite-type compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0233] The polymer-based solid electrolyte can be, for example, a solid electrolyte including an ion conductive polymer and a lithium salt, a solid electrolyte including an ionic liquid polymer and a lithium salt, or a combination thereof.

[0234] The ion conductive polymer can be a polymer including an ion conductive repeating unit in a main chain or a side chain. The ion conductive repeating unit can be a unit having ion conductivity, and can be, for example, an alkylene oxide unit or a hydrophilic unit. In some embodiments, the ion conductive polymer can include an ether-based monomer, an acryl-based monomer, a methacrylic acid monomer, a siloxane-based monomer, or a combination thereof as a conductive repeating unit. The ion conductive polymer can be, for example, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyethyl methacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, polymethyl acrylate, polyethyl acrylate, poly-2-ethylhexyl acrylate, polybutyl methacrylate, poly-2-ethylhexyl methacrylate, polydecyl acrylate, polyethylene vinyl acetate, or a combination thereof. The ion conductive polymer can be, for example, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinyl sulfone, or a combination thereof.

[0235] In some embodiments, the polymeric ionic liquid (PIL) can include repeat units comprising: i) at least one cation selected from the group consisting of ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, onium, sulfonium, triazolium, and mixtures thereof; and ii) at least one anion selected from the group consisting of BF4 - , PF6 - , AsF6 - , SbF6 - , A1C14 - , HSO4 - , CIO4 - , CH3SO3 - , CF3CO2 - , (CF3SO2)2N - , CI - , Br - , I - , BF4 - , SO4 - , PF6 - , CIO4 - , CF3SO3 - , CF3CO2 - , (C2F5SO2)2N - , (C2F5SO2)(CF3SO2)N - , NO3 - , A12C17 - , AsF6 - , SbF6 - , CF3COO - , CH3COO - , CF3SO3 - , (CF3SO2)3C - , (CF3CF2SO2)2N - , (CF3)2PF4 - , (CF3)3PF3 - , (CF3)4PF2 - , (CF3)5PF - , (CF3)6P - , SF5CF2SO3 - , SF5CHFCF2SO3 - , CF3CF2(CF3)2CO - , (CF3SO2)2CH - , (SF5)3C - , (0(CF3)2C2(CF3)20)2PO - , and (CF3SO2)2N -In some embodiments, the PIL can be poly(diallyldimethylammonium) (TFSI), poly(1-allyl-3-methylimidazolium trifluoromethanesulfonimide), poly(N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide), or a combination thereof.

[0236] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2)(1≤x≤20 and 1≤y≤20), LiCl, LiI, or a combination thereof.

[0237] A dry negative electrode manufacturing method according to some embodiments can be provided.

[0238] The dry negative electrode manufacturing method can include: disposing a dry negative electrode film; and disposing the dry electrode film on one side or opposite sides of a current collector.

[0239] Disposing the dry negative electrode film can include: preparing a dry mixture by dry mixing a dry negative electrode active material and a dry binder; and preparing the dry negative electrode film by molding the dry mixture.

[0240] First, a dry mixture can be prepared by dry mixing a negative electrode active material and a dry binder. For example, a dry mixture can be prepared by dry mixing a dry negative electrode active material and a dry binder.

[0241] The dry mixture can further include a dry conductive material.

[0242] Dry mixing refers to mixing that can be performed without including a process solvent. The process solvent can be, for example, a solvent used to prepare an electrode slurry. The process solvent can be, for example, water, NMP, etc., but is not limited thereto, and any process solvent used to prepare an electrode slurry can be used herein. In some embodiments, dry mixing can be performed using a stirrer at a temperature of 15°C to 65°C at a rotation speed of about 10 rpm to about 10,000 rpm. Dry mixing can be performed using a stirrer for 1 minute to 200 minutes.

[0243] The dry mixing can be performed, for example, at least once. First, a first dry mixture can be prepared by performing primary dry mixing of the dry negative active material, the dry conductive material, and the dry binder. The primary dry mixing can be performed, for example, at a temperature of 25°C to 65°C at a rotation speed of about 10 rpm to about 2000 rpm for 15 minutes or less. Subsequently, a second dry mixture can be prepared by additionally performing secondary dry mixing of the first dry mixture. In some embodiments, the secondary dry mixing can be performed, for example, at a temperature of about 25°C to about 65°C at a rotation speed of about 3000 rpm to about 9000 rpm for about 10 minutes to about 60 minutes. The dry mixture including the fibrillated dry binder can be obtained by the secondary dry mixing.

[0244] The stirrer can be, for example, a kneader. In some embodiments, the stirrer can include a chamber, one or more rotating shafts located inside the chamber and rotatable, and blades rotatably coupled to the rotating shafts and positioned in a longitudinal direction of the rotating shafts. The blades can be, for example, one or more selected from a ribbon blade, a sigma blade, a jet (Z) blade, a dispersion blade, and a screw blade. Due to the inclusion of the blades, the dough-like mixture can be prepared by effectively mixing the electrode active material, the dry conductive material, and the dry binder without a solvent.

[0245] Examples of the dry binder can include a vinylidene fluoride / hexafluoropropylene copolymer, a polyvinylidene fluoride, a polyacrylonitrile, a polymethyl methacrylate, a polytetrafluoroethylene (PTFE), a mixture of the foregoing polymers, and a styrene butadiene rubber-based polymer. The dry binder can be selected from dry binders used for the dry negative electrode film.

[0246] In some embodiments, as the dry conductive material, carbon black, graphite fine particles, natural graphite, artificial graphite, acetylene black, ketjen black, carbon fibers, carbon nanotubes, metal powders of, for example, copper, nickel, aluminum, or silver, metal fibers or metal tubes, or conductive polymers such as polyphenylene derivatives can be used, but embodiments of the present disclosure are not limited thereto. Any conductive material can be used as long as it is used in the art. The conductive material can be, for example, a carbon-based conductive material. The dry conductive material can be selected from dry conductive materials used in the dry negative electrode film.

[0247] A plasticizer or a pore-forming agent can be added to the dry mixture to form pores in the electrode plate.

[0248] The contents of the dry negative active material, the dry binder, and the dry conductive material used in the dry negative electrode film can be at a level commonly used in lithium batteries.

[0249] The dry cathode film can use a dry cathode active material as a cathode active material. The dry cathode active material can be understood by referring to the above-described dry cathode film. The dry anode film can use a dry anode active material as an anode active material. The dry anode active material can be understood by referring to the above-described dry anode film.

[0250] Then, the dry mixture can be molded to prepare a dry cathode film.

[0251] The prepared dry mixture can be fed into an extrusion device and extruded in the form of a sheet or a film. In some embodiments, the pressure at the time of extrusion can be about 4 MPa to about 100 MPa.

[0252] Next, an electrode current collector in which the intermediate layer is disposed on one side or opposite sides of a substrate can be provided.

[0253] Providing an electrode current collector in which the intermediate layer is disposed on one side or opposite sides of a substrate can include, for example: providing a substrate; and disposing the intermediate layer on one side or opposite sides of the substrate.

[0254] The substrate of the electrode current collector can be understood by referring to the above-described electrode current collector. In some embodiments, the substrate for the cathode current collector can be an aluminum foil. In some embodiments, the substrate for the anode current collector can be a copper foil.

[0255] Placing the intermediate layer on one side or opposite sides of the substrate includes dry coating and / or wet coating. In some embodiments, dry coating can be performed by depositing a carbon-based conductive material and / or a precursor thereof on one side or opposite sides of the electrode current collector. The deposition can be performed at room temperature to high temperature and at atmospheric pressure to vacuum pressure. If the intermediate layer disposed by dry coating includes a carbon-based material, a binder can not be included. In some embodiments, for wet coating, a composition including a carbon-based conductive material and a binder can be coated on one side or opposite sides of the electrode current collector. The composition can include, for example, a carbon-based conductive material, a binder, and a process solvent. The carbon-based conductive material and the binder can be understood by referring to the above-described electrode portion. The process solvent can be selected from the solvents used to prepare the electrode slurry. The process solvent can be removed by drying after the composition is coated on the electrode current collector. The coating method can include spin coating, dip coating, etc., and is not limited thereto, and the coating method can be any coating method used in the art.

[0256] Next, the dry anode film can be disposed on one side or opposite sides of the current collector simultaneously or sequentially, thereby preparing a dry anode.

[0257] Pressing can be further performed during and / or after the dry anode film is placed on one side or opposite sides of the electrode current collector.

[0258] The pressing can be, for example, roll pressing, flat pressing, etc., but is not necessarily limited thereto. The pressure during the pressing can be, for example, about 1.0 ton / cm 2 to about 10.0 ton / cm 2 If the pressure during the pressing is excessively increased, the electrode current collector can be broken. If the pressure during the pressing is too low, the binding force between the current collector and the dry negative electrode film can be reduced.

[0259] A lithium battery is manufactured by the following example method, but embodiments of the present disclosure are not necessarily limited to the method, and the method can vary depending on the desired conditions.

[0260] First, one or both of a positive electrode and a negative electrode can be manufactured according to the dry negative electrode manufacturing method described above. In some embodiments, if one of the positive electrode and the negative electrode is manufactured by using the dry electrode preparation method, the other electrode can be manufactured by a wet manufacturing method. For example, the other electrode can be prepared by the following steps: preparing an electrode slurry including an electrode active material, a conductive material, a binder, and a solvent; coating the prepared electrode slurry on an electrode current collector; and drying the electrode slurry. The conductive material and the binder included in the wet-manufactured electrode can be selected from the conductive material and the binder used to manufacture the dry negative electrode.

[0261] Next, a separator interposed between the positive electrode and the negative electrode can be prepared.

[0262] Providing the dry negative electrode film can include: preparing a dry mixture by dry-mixing the dry negative electrode active material and the dry binder as described above; and molding the dry mixture to prepare the dry negative electrode film.

[0263] The dry negative electrode active material can be formed in a process of dry-mixing the core and the composite.

[0264] The composite can include: at least one first metal oxide; and a first carbon-based material, wherein the first metal oxide is disposed in a matrix of the first carbon-based material, wherein the first metal oxide can be represented by the formula M a O b (0 < a ≤ 3, 0 < b < 4, where a is 1, 2, or 3, and b can not be an integer), wherein M can be at least one metal selected from Groups 2 to 16 of the periodic table.

[0265] Providing the composite includes, for example: providing the composite by supplying a reaction gas composed of a carbon source gas to a structure including a metal oxide and performing a heat treatment. The providing the composite can include, for example: providing the composite by supplying a reaction gas composed of a carbon source gas to a structure including M a O cat least one second metal oxide represented by formula (0 < a ≤ 3 and 0 < c ≤ 4, and if a is 1, 2, or 3, c can be an integer) and performing a heat treatment to set a composite, where M can be at least one metal selected from elements in Groups 2 to 13, Group 15, and Group 16 of the periodic table.

[0266] The carbon source gas can be a gas consisting of a compound represented by formula 10, or a mixture of at least one gas selected from the group consisting of the compound represented by formula 10, a compound represented by formula 11, and an oxygen-containing gas represented by formula 12: Formula 10 C n H (2n+2-a) [OH] a wherein, in formula 10, n can be 1 to 20, and a can be 0 or 1; Formula 11 C n H 2n wherein, in formula 11, n can be 2 to 6; Formula 12 C x H y O z wherein, in formula 12, x can be 0 or an integer of 1 to 20, y can be 0 or an integer of 1 to 20, and z is 1 or 2.

[0267] The compound represented by formula 10 and the compound represented by formula 11 can be at least one selected from the group consisting of methane, ethylene, propylene, methanol, ethanol, and propanol. The oxygen-containing gas represented by formula 12 can include, for example, carbon dioxide (CO2), carbon monoxide (CO), water vapor (H2O), or a mixture thereof.

[0268] After supplying a reaction gas consisting of a carbon source gas to the M a O c (0 < a ≤ 3 and 0 < c ≤ 4, and if a is 1, 2, or 3, c can be an integer) and performing a heat treatment, a cooling process using at least one inert gas selected from nitrogen, helium, and argon can be further performed. Cooling refers to adjustment to room temperature (20°C to 25°C). The cooling gas can include at least one inert gas selected from nitrogen, helium, and argon.

[0269] In the method of preparing a composite, the process of growing a carbon-based material (e.g., graphene) can be performed under various conditions according to a gas phase reaction.

[0270] According to a first condition, for example, prior to raising the temperature to a heat treatment temperature (T), methane can first be supplied to a reactor loaded with a second metal oxide represented by M a O c (0 < a ≤ 3 and 0 < c ≤ 4, and if a is 1, 2, or 3, c can be an integer) under a hydrogen atmosphere. The heating time to reach the heat treatment temperature (T) can be about 10 minutes to about 4 hours, and the heat treatment temperature (T) can be in the range of about 700°C to about 1100°C. After heat treatment under the heat treatment temperature (T) for the duration of the reaction time, a mixed gas of methane and hydrogen can be supplied, and heat treatment can be performed for the remaining reaction time. The reaction time can be, for example, 4 hours to 8 hours. The product of the heat treatment can be cooled to room temperature to produce a composite. Nitrogen can be supplied during the cooling process. The time spanning the process of cooling from the heat treatment temperature (T) to room temperature can be, for example, about 1 hour to about 5 hours.

[0271] According to a second condition, for example, prior to raising the temperature to a heat treatment temperature (T), hydrogen can first be supplied to a reactor loaded with a second metal oxide represented by M a O c (0 < a ≤ 3 and 0 < c ≤ 4, and if a is 1, 2, or 3, c can be an integer) under a hydrogen atmosphere. The heating time to reach the heat treatment temperature (T) can be about 10 minutes to about 4 hours, and the heat treatment temperature (T) can be in the range of about 700°C to about 1100°C. After heat treatment under the heat treatment temperature (T) for the duration of the reaction time, a mixed gas of methane and hydrogen can be supplied, and heat treatment can be performed for the remaining reaction time. The reaction time can be, for example, 4 hours to 8 hours. The product of the heat treatment can be cooled to room temperature to produce a composite. Nitrogen can be supplied during the cooling process. The time spanning the process of cooling from the heat treatment temperature (T) to room temperature can be, for example, about 1 hour to about 5 hours.

[0272] According to a third condition, for example, prior to raising the temperature to a heat treatment temperature (T), hydrogen can first be supplied to a reactor loaded with a second metal oxide represented by M a O c (0 < a ≤ 3 and 0 < c ≤ 4, and if a is 1, 2, or 3, c can be an integer) under a hydrogen atmosphere. The heating time to reach the heat treatment temperature (T) can be about 10 minutes to about 4 hours, and the heat treatment temperature (T) can be in the range of about 700°C to about 1100°C. After heat treatment under the heat treatment temperature (T) for the duration of the reaction time, a mixed gas of methane and hydrogen can be supplied, and heat treatment can be performed for the remaining reaction time. The reaction time can be, for example, 4 hours to 8 hours. The product of the heat treatment can be cooled to room temperature to produce a composite. Nitrogen can be supplied during the cooling process. The time spanning the process of cooling from the heat treatment temperature (T) to room temperature can be, for example, about 1 hour to about 5 hours.

[0273] If the carbon source gas includes water vapor in the process of preparing the composite, a composite having excellent electrical conductivity can be obtained. The amount of water vapor in the gas mixture is not limited and can be, for example, about 0.01 vol% to about 10 vol% based on 100 vol% of the total carbon source gas. For example, the carbon source gas can be: methane; a mixed gas including methane and an inert gas; or a mixed gas including methane and an oxygen-containing gas.

[0274] For example, the carbon source gas can be: methane; a mixed gas of methane and carbon dioxide; or a mixed gas of methane, carbon dioxide, and water vapor. In the mixed gas of methane and carbon dioxide, the molar ratio of methane to carbon dioxide can be about 1 :0.20 to about 1 :0.50, about 1 :0.25 to about 1 :0.45, or about 1 :0.30 to about 1 :0.40. In the mixed gas of methane, carbon dioxide, and water vapor, the molar ratio of methane to carbon dioxide to water vapor can be about 1 :0.20 to 0.50:0.01 to 1.45, about 1 :0.25 to 0.45:0.10 to about 1.35, or about 1 :0.30 to 0.40: about 0.50 to 1.0.

[0275] The carbon source gas can be, for example, carbon monoxide or carbon dioxide. The carbon source gas can be, for example, a mixed gas of methane and nitrogen. The molar ratio of methane to nitrogen in the mixed gas of methane and nitrogen can be about 1 :0.20 to about 1 :0.50, about 1 :0.25 to about 1 :0.45, or about 1 :0.30 to about 1 :0.40. The carbon source gas can not include an inert gas such as nitrogen.

[0276] The heat treatment pressure can be selected in consideration of the heat treatment temperature, the composition of the gas mixture, the amount of carbon coating desired, and the like. The heat treatment pressure can be controlled by adjusting the amount of the gas mixture that enters and the amount of the gas mixture that exits. The heat treatment pressure can be, for example, at least 0.5 atm, at least 1 atm, at least 2 atm, at least 3 atm, at least 4 atm, at least 5 atm. The heat treatment pressure can be, for example, about 0.5 atm to about 10 atm, about 1 atm to about 10 atm, about 2 atm to about 10 atm, about 3 atm to about 10 atm, about 4 atm to about 10 atm, or about 5 atm to about 10 atm.

[0277] The heat treatment time is not limited, and can be appropriately adjusted depending on the heat treatment temperature, the heat treatment pressure, the composition of the gas mixture, and the desired amount of carbon coating. For example, the reaction time at the heat treatment temperature can be, for example, about 10 minutes to about 100 hours, about 30 minutes to about 90 hours, or about 50 minutes to about 40 hours. For example, as the heat treatment time increases, the amount of deposited carbon (e.g., the amount of graphene) increases, and thus the electrical properties of the composite can be improved. It should be noted that this trend can not necessarily be directly proportional to time. For example, after a certain period of time, carbon deposition (e.g., graphene deposition) can no longer occur, or the deposition rate can decrease.

[0278] By the gas phase reaction of the carbon source gas, even at a relatively low temperature, a composite can be obtained by providing a uniform coating layer of a carbon-based material (e.g., graphene) on one or more of a first metal oxide represented by M a O c (0 < a ≤ 3 and 0 < c ≤ 4, where, if a is 1, 2, or 3, c can be an integer) and a reduced product thereof (e.g., M a O b (0 < a ≤ 3 and 0 < b < 4, where, if a is 1, 2, or 3, b can not be an integer).

[0279] The composite can include, for example: a matrix of a carbon-based material (e.g., a matrix of graphene) having at least one structure selected from a spherical structure, a spiral structure having a plurality of spherical structures connected to each other, a cluster structure having a plurality of aggregated spherical structures, and a sponge structure; and at least one of a first metal oxide represented by M a O b (0 < a ≤ 3 and 0 < b < 4, where, if a is 1, 2, or 3, b can not be an integer). a O c (0 < a ≤ 3 and 0 < c ≤ 4, where, if a is 1, 2, or 3, c can be an integer).

[0280] The content of the dry binder can be about 1 wt% to about 10 wt%, about 1 wt% to about 5 wt%, about 1.5 wt% to about 3.5 wt%, or about 1.5 wt% to about 3 wt%, based on 100 wt% of the total content of the core, the composite, and the dry binder.

[0281] The content of the composite including at least one selected from the first metal oxide and the second metal oxide and the first carbon-based material can be about 5 wt% or less, based on the total weight of the dry negative electrode film.

[0282] Hereinafter, the disclosure will be described in greater detail with reference to the following examples and comparative examples. However, the following examples are presented only to illustrate the disclosure, and the scope of the disclosure is not limited thereto.

[0283] (Preparation of composite) Preparation Example 1: Al2O3@Gr composite Al2O3 particles (average particle diameter: about 20 nm) were placed in a reactor, and then, the temperature inside the reactor was increased to 1000°C at a temperature increase rate of about 23°C / min for about 30 minutes under the condition that CH4was supplied to the reactor at about 300 seem at 1 atm.

[0284] Subsequently, heat treatment was performed while maintaining the above temperature for 7 hours. Subsequently, the supply of CH4was stopped, and then, the temperature inside the reactor was adjusted to room temperature (25°C) to obtain a composite in which Al2O3 particles and their reduction products (Al2O z (0<z<3) particles are embedded in graphene.

[0285] The amount of alumina included in the composite was 60 wt%.

[0286] Preparation Example 2: Al2O3@Gr composite The composite was prepared in the same process as Preparation Example 1 below, except that Al2O3 particles (average particle diameter: about 200 nm) were used instead of Al2O3 particles (average particle diameter: about 20 nm).

[0287] Preparation Example 3: SiO2@Gr composite SiO2 particles (average particle diameter: about 15 nm) were placed in a reactor, and then, the temperature inside the reactor was increased to 1000°C for about 30 minutes under the condition that CH4was supplied to the reactor at about 300 seem at 1 atm.

[0288] Subsequently, heat treatment was performed while maintaining the above temperature for 7 hours. Then, the temperature inside the reactor was adjusted to room temperature (20°C to 25°C) to obtain a composite in which SiO2 particles and their reduction products SiO y (0<y<2) particles are embedded in graphene.

[0289] (Preparation of silicon-based negative electrode active material) Preparation Example 4 Flaky graphite (SFG6) (Timcal, AG) (particle diameter: 4 µm, specific surface area: 17 m 2The pitch and silicon were wet mixed in a weight ratio of 2:25:73, and then spray dried. Subsequently, the dried product was carbonized at 900°C to obtain a silicon composite structure (SCN) (D50: about 13 μm).

[0290] (Manufacture of lithium battery (full cell) and dry negative electrode) Example 1: Dry negative electrode film containing graphite, binder, and 0.5% of GB (Manufacture of dry negative electrode) Graphite as a first negative electrode active material, polytetrafluoroethylene (PTFE) as a dry binder, and the composite (GB) prepared in Example 1 were put into a blade mixer in a weight ratio of 97.5:2.0:0.5, and then primary dry mixing was performed at 25°C at a speed of 1200 rpm for 10 minutes to prepare a first dry mixture (or a first mixture) in which the dry negative electrode active material and the dry binder are uniformly mixed.

[0291] Then, to make the binder be fibrous, the first mixture was additionally mixed at a speed of 5000 rpm for 20 minutes at 25°C to prepare a second mixture. No separate solvent was used in the preparation of the first mixture and the second mixture.

[0292] The prepared second mixture was put into an extruder and extruded to prepare a self-standing film of the negative electrode active material layer in the form of a dry negative electrode film. The pressure at the time of extrusion was 50 MPa. The dry negative electrode film includes a composite negative electrode active material having a structure in which a shell containing the composite and / or a ground product thereof is coated on a graphite core.

[0293] A carbon layer as an intermediate layer was disposed on one side of a copper thin film having a thickness of 12 μm to prepare a first stack in which the intermediate layer is disposed on one surface of the negative electrode current collector.

[0294] The intermediate layer was prepared by coating a composition including carbon conductive material (Danka black) and polyvinylidene fluoride (PVDF) on an aluminum thin film and then drying it. The thickness of the intermediate layer disposed on one surface of the aluminum thin film was about 1 μm.

[0295] The dry negative electrode film as a self-standing film of the negative electrode active material layer was disposed on the intermediate layer of the first stack, and then pressed, thereby preparing a negative electrode.

[0296] (Manufacture of positive electrode) LiNi 0.91 Co 0.05 Al 0.04A mixture of O2 (hereinafter referred to as NCA91) composite positive electrode active material, carbon conductive agent (Denka Black), and polyvinylidene fluoride (PVdF) was mixed with N-methylpyrrolidone (NMP) in an agate mortar to prepare a slurry.

[0297] The slurry rod was coated on an aluminum current collector to a thickness of 40 μm, dried at room temperature, re-dried at 120°C under vacuum, and pressed to prepare a positive electrode.

[0298] (Making of coin-type battery) A coin-type battery was prepared using the above-prepared positive electrode and negative electrode, a polypropylene separator (Celgard 3510), and a solution as an electrolyte, in which 1.15 M LiPF6 and 1.5 wt% of vinylene carbonate (VC) were dissolved in ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + dimethyl carbonate (DMC) (2:4:4 by volume ratio).

[0299] Example 2: Dry negative electrode film including graphite, SCN, binder, and 0.5% of GB A coin-type battery was manufactured in the same manner as in Example 1, except that a dry negative electrode film was manufactured according to the following process.

[0300] Graphite as a first negative electrode active material, the silicon composite structure (SCN) prepared in Preparation Example 4 as a second negative electrode active material, polytetrafluoroethylene (PTFE) as a dry binder, and the composite (GB) prepared in Preparation Example 1 were put into a blade mixer at a weight ratio of 81.5:15:3:0.5, and then primary dry mixing was performed at 25°C at a speed of 1200 rpm for 10 minutes, thereby preparing a first dry mixture in which the dry negative electrode active material, the dry conductive material, and the dry binder were uniformly mixed.

[0301] The dry negative electrode film includes a first composite negative electrode active material in which a shell including the composite and / or a milled product thereof is coated on a graphite core, and a second composite negative electrode active material in which a shell including the composite and / or a milled product thereof is coated on an SCN core.

[0302] Example 3 A coin-type battery was manufactured in the same manner as in Example 1, except that a negative electrode was manufactured according to the following process.

[0303] (Making of negative electrode) Graphite as a first negative electrode active material, the silicon composite structure (SCN) prepared in Preparation Example 4 as a second negative electrode active material, polytetrafluoroethylene (PTFE) as a dry binder, and the composite (GB) prepared in Preparation Example 1 were put in a blade mixer in a weight ratio of 40.5:7.5:1:0.2, and then primary dry mixing was performed at 25°C at a speed of 1200 rpm for 10 minutes, thereby preparing a first dry mixture (or a first mixture) in which the dry negative electrode active material and the dry binder are uniformly mixed.

[0304] Then, in order to allow the binder to be fibrous, the first mixture was additionally secondarily mixed at a speed of 5000 rpm for 20 minutes at 25°C to prepare a second mixture (or a second dry mixture). No separate solvent was used in the preparation of the first mixture and the second mixture.

[0305] The prepared second mixture was put in an extruder and extruded to prepare a self-standing film of a negative electrode active material layer in the form of a first dry negative electrode film. The pressure at the time of extrusion was 50 MPa. The dry negative electrode film included a composite negative electrode active material having a structure in which a shell containing the composite and / or a ground product thereof is coated on a graphite core.

[0306] Separately, a second dry negative electrode film was prepared in the same manner as in the above-described manner, except that, in the preparation of a second dry mixture for forming the second dry negative electrode film, graphite as a first negative electrode active material, the silicon composite structure (SCN) prepared in Preparation Example 4 as a second negative electrode active material, polytetrafluoroethylene (PTFE) as a dry binder, and the composite (GB) prepared in Preparation Example 1 were changed in a weight ratio of 40.5:7.5:2:0.3.

[0307] A carbon layer as an intermediate layer was disposed on one side of a copper thin film having a thickness of 12 μm to prepare a first stack in which the intermediate layer was disposed on one surface of a negative electrode current collector.

[0308] The intermediate layer was prepared by coating a composition including carbon conductive material (Danka black) and polyvinylidene fluoride (PVDF) on an aluminum thin film and then drying it. The thickness of the intermediate layer disposed on one surface of the aluminum thin film was about 1 μm.

[0309] The first dry negative electrode film and the second dry negative electrode film were sequentially disposed on the intermediate layer of the prepared first stack, and were pressed to prepare a dry negative electrode (copper thin film / intermediate layer (carbon layer) / first dry negative electrode film / second dry negative electrode film).

[0310] Example 4 In addition to the negative electrode manufactured according to the process shown in Preparation Example 1, a coin-type battery was manufactured in the same manner as in Example 2. Figure 4c In addition to the negative electrode manufactured according to the process shown in Preparation Example 1, a coin-type battery was manufactured in the same manner as in Example 2.

[0311] (Manufacture of dry negative electrode) Graphite as a first negative electrode active material, the silicon composite structure (SCN) prepared in Preparation Example 4 as a second negative electrode active material, polytetrafluoroethylene (PTFE) as a dry binder, and the composite (GB) prepared in Preparation Example 1 were put into a blade mixer in a weight ratio of 40.75:15:2:0.3, and then primary dry mixing was performed at 25°C at a speed of 1200 rpm for 10 minutes, thereby preparing a first dry mixture in which the dry negative electrode active material and the dry binder were uniformly mixed.

[0312] Then, in order to allow the binder to be fibrous, the first mixture was additionally secondarily mixed at 5000 rpm for 20 minutes at 25°C to prepare a second mixture. No separate solvent was used in the preparation of the first mixture and the second mixture.

[0313] The prepared second mixture was put into an extruder and extruded to prepare a self-standing film of the negative electrode active material layer in the form of a first dry negative electrode film. The pressure at the time of extrusion was 50 MPa. The dry negative electrode film included a composite negative electrode active material having a structure in which a shell containing the composite and / or a ground product thereof was coated on a graphite core and an SCN core.

[0314] Separately, a second dry negative electrode film was prepared in the same manner as in the above-described manner, except that, in the preparation of the second dry mixture, the weight ratio of graphite as a first negative electrode active material, polytetrafluoroethylene (PTFE) as a dry binder, and the composite (GB) prepared in Preparation Example 1 was changed to a weight ratio of 40.75:1:0.2.

[0315] A carbon layer as an intermediate layer was disposed on one side of a copper thin film having a thickness of 12 μm to prepare a first stack in which the intermediate layer was disposed on one surface of the negative electrode current collector.

[0316] The intermediate layer was prepared by coating a composition including carbon conductive material (Danka black) and polyvinylidene fluoride (PVDF) on an aluminum thin film and then drying it. The thickness of the intermediate layer disposed on one surface of the aluminum thin film was about 1 μm.

[0317] The first dry negative electrode film and the second dry negative electrode film were sequentially disposed on the intermediate layer of the prepared first stack, and were pressed to prepare a dry negative electrode (copper thin film / intermediate layer (carbon layer) / first dry negative electrode film / second dry negative electrode film).

[0318] Example 5 A coin-type battery was manufactured in the same manner as in Example 3, except that a negative electrode according to the following process was manufactured. Figure 4b ​

[0319] (Making of the negative electrode) Graphite as a first negative electrode active material, the silicon composite structure (SCN) used in Preparation Example 4 as a second negative electrode active material, polytetrafluoroethylene (PTFE) as a dry binder, and the composite (GB) prepared in Preparation Example 1 were put into a blade mixer in a weight ratio of 40.5:7:1:0.2, and then primary dry mixing was performed at 25°C at a speed of 1200 rpm for 10 minutes, thereby preparing a first dry mixture in which the dry negative electrode active material and the dry binder were uniformly mixed.

[0320] Then, in order to make the binder fibrous, the first mixture was additionally secondarily mixed at 5000 rpm for 20 minutes at 25°C to prepare a second mixture (or a second dry mixture). No separate solvent was used in the preparation of the first mixture and the second mixture.

[0321] The prepared second mixture was put into an extruder and extruded to prepare a first dry negative electrode film in the form of a sheet of a self-standing film. The pressure at the time of extrusion was 50 MPa. The dry negative electrode film included a composite negative electrode active material having a structure in which a shell containing the composite and / or a ground product thereof was coated on a graphite core.

[0322] Separately, a second dry negative electrode film was prepared in the same manner as the above-described manner, except that, in the preparation of a second dry mixture for forming the second dry negative electrode film, graphite as a first negative electrode active material, the silicon composite structure (SCN) prepared in Preparation Example 4 as a second negative electrode active material, polytetrafluoroethylene (PTFE) as a dry binder, and the composite (GB) prepared in Preparation Example 1 were changed in a weight ratio of 40.5:8:2:0.3.

[0323] A carbon layer as an intermediate layer was disposed on one side of a copper thin film having a thickness of 12 μm to prepare a first stack in which the intermediate layer was disposed on one surface of a negative electrode current collector.

[0324] The intermediate layer was prepared by coating a composition including carbon conductive material (Danka black) and polyvinylidene fluoride (PVDF) on an aluminum thin film and then drying it. The thickness of the intermediate layer disposed on one side of the aluminum thin film was about 1 μm.

[0325] The first dry negative electrode film and the second dry negative electrode film were sequentially disposed on the intermediate layer of the prepared first stack, and were pressed to prepare a dry negative electrode (copper thin film / intermediate layer (carbon layer) / first dry negative electrode film / second dry negative electrode film).

[0326] Comparative Example 1: Preparation of a wet negative electrode (Making of the negative electrode) Graphite as a first negative active material, polytetrafluoroethylene (PTFE) as a binder, and the composite (GB) prepared in Preparation Example 1 as a conductive material were put in a blade mixer at a weight ratio of 96.5:3:0.5, and then water was added thereto and mixed at a speed of 1200 rpm at 25℃ for 10 minutes to obtain a negative active material slurry.

[0327] The negative active material slurry was coated on a copper foil, and then a film was formed to a coating thickness of 20 μm using a doctor blade.

[0328] After drying in a vacuum at 130℃ for 3 hours, it was pressed to prepare a negative electrode.

[0329] Comparative Example 2: Preparation of a dry negative electrode A dry negative electrode was prepared in the same manner as in Example 1, except that Denka Black was used instead of the composite prepared in Preparation Example 1 in the preparation of the first dry mixture.

[0330] Comparative Example 3: Preparation of a dry negative electrode A dry negative electrode was prepared in the same manner as in Example 2, except that only the silicon composite structure (SCN) prepared in Preparation Example 4 was used instead of graphite as a first negative active material and the silicon composite structure (SCN) prepared in Preparation Example 4 as a second negative active material in the preparation of the first dry mixture.

[0331] Evaluation Example 1: Evaluation of tensile strength For each of the dry negative electrode films prepared in Example 1 to Example 5 and Comparative Example 1 to Comparative Example 3, a test piece (216 mm (length) x 19 ± 0.5 mm (width) x 3.18 ± 0.38 mm (thickness)) for measuring tensile strength according to ASTM D 638 was prepared. The tensile strength was measured by tensile strength testing according to the ASTM D 638 method. The results of the measurement are shown in Table 1 below.

[0332] [Table 1]

[0333] As shown in Table 1, the dry negative electrode films of Example 1 to Example 5 showed improved mechanical strength compared to the dry negative electrode films of Comparative Example 1 to Comparative Example 3.

[0334] The dry negative electrodes of Example 1 to Example 5 were determined to be superior to the dry negative electrodes of Comparative Example 1 to Comparative Example 3 because each component was more uniformly distributed, the binder was more uniformly distributed within the dry negative electrode film, and the fibrillated binder more effectively bound the composite negative active material.

[0335] Evaluation Example 2: Mixture resistance evaluation For each of the dry negative electrodes prepared in Example 1 to Example 5 and Comparative Example 1 to Comparative Example 3, the mixture resistance was measured at 25°C using an electrode resistance measuring system (Hioki, RM2610). The measurement results are shown in Table 2 below.

[0336] In the electrode resistance measuring system (Hioki, RM2610), the probe was disposed so that the negative electrode active material layer of the negative electrode faced the probe, a constant current was passed through the surface of the negative electrode active material layer, the volume resistivity of the negative electrode active material layer was measured from the surface potential distribution, and the interface resistance between the negative electrode active material layer and the negative electrode current collector was measured. The volume resistivity of the negative electrode active material layer was taken as the mixture resistance of the negative electrode active material layer.

[0337] Evaluation Example 3: Interface Resistance Evaluation For each of the dry negative electrodes prepared in Example 1 to Example 5 and Comparative Example 1 to Comparative Example 3, the interface resistance was measured at 25°C using an electrode resistance measuring system (Hioki, RM2610). The measurement results are shown in Table 2.

[0338] In the electrode resistance measuring system (Hioki, RM2610), the probe was disposed so that the negative electrode active material layer of the negative electrode faced the probe, a constant current was passed through the surface of the negative electrode active material layer, the volume resistivity of the negative electrode active material layer was measured from the surface potential distribution, and the interface resistance between the negative electrode active material layer and the negative electrode current collector was measured.

[0339] [Table 2]

[0340] As shown in Table 2, the dry negative electrodes of Example 1 to Example 5 had a reduced mixture resistance compared to the dry negative electrodes of Comparative Example 1 to Comparative Example 3.

[0341] It can be seen that, due to the composite negative electrode active material including the shell in which the complex is contained being uniformly disposed on the core, the dry negative electrodes of Example 1 to Example 5 had improved electronic conductivity and / or ionic conductivity.

[0342] Because the wet negative electrode of Comparative Example 1 and the dry negative electrodes of Comparative Example 2 and Comparative Example 3 did not include the composite negative electrode active material, they had reduced electronic conductivity and / or ionic conductivity.

[0343] As shown in Table 2, the dry negative electrodes of Example 1 to Example 5 had a reduced interface resistance compared to the dry negative electrodes of Comparative Example 1 to Comparative Example 3.

[0344] Evaluation Example 4: Adhesion of the Electrode Plate The dry negative electrode samples prepared in Example 1 to Example 5 and Comparative Example 1 to Comparative Example 3 were cut into 150 mm x 15 mm using a bonding force measuring device (UTM, Instron), and then the electrodes were attached to double-sided adhesive tape, and the force of 90° dislocation was measured. The results are shown in Table 3.

[0345] [Table 3]

[0346] As shown in Table 3, the wet negative electrode of Comparative Example 1 showed improved electrode adhesion compared to the dry negative electrode films of Comparative Example 2 and Comparative Example 3. However, it can be seen that the dry negative electrode films of Example 1 to Example 5 had improved electrode adhesion compared to the wet negative electrode of Comparative Example 1 and the dry negative electrodes of Comparative Example 2 and Comparative Example 3.

[0347] Evaluation Example 5: Evaluation of charge and discharge characteristics at room temperature (25℃) The lithium batteries prepared in Example 1 to Example 5 and Comparative Example 1 to Comparative Example 3 were charged at a current of 0.1C rate under constant current until the voltage reached 4.5V (vs. Li) at 25℃, and then cut off while maintaining the voltage of 4.5V in constant voltage mode with a current of 0.02C rate. Subsequently, during discharging, discharging was performed at a constant current of 0.1C rate until the voltage reached 2.75V (vs. Li) (formation cycle).

[0348] The lithium batteries that had undergone the formation cycle were charged at a current of 0.2C rate under constant current until the voltage reached 4.5V (vs. Li) at 25℃, and then cut off while maintaining the voltage of 4.5V in constant voltage mode with a current of 0.02C rate. Subsequently, during discharging, discharging was performed at a constant current of 0.2C rate until the voltage reached 2.75V (vs. Li) (1st cycle). The cycle was repeated under the same conditions (repeated 50 times) until the 50th cycle.

[0349] During the entire above-described charge-discharge cycle, a rest period of 10 minutes was provided after each charge / discharge cycle. Some of the room temperature charge / discharge test results are shown in Table 4 below. The initial efficiency is defined by Equation 1 below, and the capacity retention rate is defined by Equation 2 below.

[0350] Equation 1 Initial efficiency [%] = [discharge capacity in formation cycle / charge capacity in formation cycle] x 100 < Equation 2> Capacity retention rate [%] = [discharge capacity in 50th cycle / discharge capacity in 1st cycle] x 100 [Table 4]

[0351] As shown in Table 4, the lithium batteries of Examples 1 to 5 had improved life characteristics compared to the lithium batteries of Comparative Examples 1 to 3.

[0352] This improved life can be attributed to the formation of a solid electrolyte interphase (SEI) on the surface and / or inside of the negative electrode active material being suppressed by the coating with the composite, thereby suppressing an increase in internal resistance of the lithium battery.

[0353] Evaluation Example 6: XPS Spectroscopic Evaluation In the manufacturing process of the composite prepared in Production Example 1, XPS spectra were measured over time using Qunatum 2000 (Physical Electronics). The XPS spectra of the C 1s orbital and the Al 2p orbital of the sample were measured before the temperature increase, 1 minute, 5 minutes, 30 minutes, 1 hour, and 4 hours after the temperature increase. In the initial stage of the temperature increase, only the Al 2p orbital peak appeared, and the C 1s orbital peak did not appear. After 30 minutes, the peak of the C 1s orbital clearly appeared, and the size of the peak of the Al 2p orbital significantly decreased.

[0354] After 30 minutes, the peak of the C 1s orbital around 284.5 eV clearly appeared due to C-C bonds and C=C bonds caused by the growth of graphene.

[0355] As the reaction time elapsed, the peak position of the Al 2p orbital moved toward lower binding energy (eV) as the oxidation number of aluminum decreased.

[0356] Thus, it was confirmed that graphene grew on the Al2O3 particles as the reaction proceeded, and the reduced product of Al2O3, Al2O x (0 < x < 3).

[0357] The average content of carbon and aluminum was measured from the results of XPS analysis in 10 regions of the composite sample prepared in Production Example 1. Regarding the measurement results, the deviation of the aluminum content was calculated for each region. The variation in the aluminum content is expressed as a percentage of the average value and is referred to as uniformity. The percentage of the average value of the deviation of the aluminum content (e.g., the uniformity of the aluminum content) was 1%. Thus, it was confirmed that the aluminum oxide was uniformly distributed in the composite prepared in Production Example 1.

Claims

1. A dry negative electrode film, said dry negative electrode film comprising: Dry negative electrode active material; And dry adhesive, The dry negative electrode active material includes a composite negative electrode active material, which comprises a core and a shell disposed along the surface of the core. The core includes carbon-based materials, mixtures of carbon-based materials and silicon-based active substances, complexes of carbon-based materials and silicon-based active substances, or combinations thereof. The shell comprises a composite material, the composite material comprising a first carbon-based material and at least one first metal oxide. The at least one first metal oxide is disposed within the matrix of the first carbon-based material. Among them, the at least one first metal oxide is represented by the formula M a O b where 0 < a ≤ 3, 0 < b < 4, if a is 1, 2 or 3, then b is not an integer, and where M is at least one metal selected from Groups 2 to 16 of the Periodic Table of the Elements.

2. The dry negative electrode film according to claim 1, wherein, The dry negative electrode film has a multilayer structure with two or more layers.

3. The dry negative electrode film according to claim 1, wherein, The dry negative electrode film includes a first dry negative electrode film and a second dry negative electrode film, and The content of binder and the content of composite in the first dry negative electrode film are equal to or greater than the content of binder and the content of composite in the second dry negative electrode film, respectively.

4. The dry negative electrode film according to claim 1, wherein, The dry negative electrode membrane is a self-standing membrane and does not contain residual process solvents. The dry negative electrode film has a tensile strength of 450 kPa or greater before pressing and a tensile strength of 1000 kPa or greater after pressing.

5. The dry negative electrode film according to claim 1, wherein, Based on the total weight of the dry negative electrode film, the content of the composite is 5 wt% or less.

6. The dry negative electrode film according to claim 1, wherein, The metal included in the at least one first metal oxide is at least one metal selected from Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se. The at least one first metal oxide is selected from at least one of the following: Al2O z , 0 < z < 3; NbO x , 0 < x < 2.5; MgO x , 0 < x < 1; Sc2O z , 0 < z < 3; TiO y , 0 < y < 2; ZrO y , 0 < y < 2; V2O z , 0 < z < 3; WO y , 0 < y < 2; MnO y , 0 < y < 2; Fe2O z , 0 < z < 3; Co3O w , 0 < w < 4; PdO x , 0 < x < 1; CuO x , 0 < x < 1; AgO x , 0 < x < 1; ZnO x , 0 < x < 1; Sb2O z , 0 < z < 3; and SeO y at least one of 0 < y < 2.

7. The dry negative electrode film according to claim 1, wherein, The shell also includes a second metal oxide. The second metal oxide is represented by the formula M a O c where 0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, then c is an integer. The second metal oxide and the at least one first metal oxide comprise the same metal. The c / a ratio of the second metal oxide to its a has a larger value than the b / a ratio of the at least one first metal oxide to its a. The second metal oxide is disposed within the matrix of the first carbon-based material.

8. The dry negative electrode film according to claim 7, wherein, The second metal oxide is selected from Al2O3, NbO, NbO2, Nb2O5, MgO, Sc2O3, TiO2, ZrO2, V2O3, WO2, MnO2, Fe2O3, Co3O4, PdO, CuO, AgO, ZnO, Sb2O3, and SeO2, and The at least one first metal oxide is a reduction product of the second metal oxide.

9. The dry negative electrode film according to claim 1, wherein, The carbon-based material is crystalline carbon, amorphous carbon, or a combination thereof. The crystalline carbon is selected from at least one of natural graphite, artificial graphite, graphene, fullerene, and carbon nanotubes, and The amorphous carbon is selected from at least one of pitch carbon, soft carbon, hard carbon, mesophase pitch carbides, calcined coke, and carbon fiber.

10. The dry negative electrode film according to claim 1, wherein, The silicon-based active material is a silicon alloy, a silicon-containing structure, a silicon-containing compound, or a combination thereof. The silicon-containing compound is SiO x , SiC, or a combination thereof, where 0 < x ≤ 2, and The silicon-containing structure includes a silicon composite structure.

11. The dry negative electrode film according to claim 10, wherein, The silicon composite structure includes: a silicon-carbon composite comprising silicon particles and a first carbon-based material; a silicon-carbon composite comprising a core and a third carbon-based material surrounding the core, wherein silicon particles and a second carbon-based material are mixed in the core; or a combination thereof.

12. The dry negative electrode film according to claim 1, wherein, The dry adhesive includes fibrillated adhesive. The dry adhesive includes fluorinated adhesives. The glass transition temperature T of the dry adhesive g The temperature ranges from 15°C to 100°C, and Based on the total weight of the dry negative electrode film, the content of the dry binder is from 0.1 wt% to 5 wt%.

13. The dry negative electrode film according to claim 1, wherein the dry negative electrode film further comprises a dry conductive material, wherein, The dry conductive material includes carbon-based conductive materials. The carbon-based conductive material includes fibrous carbon materials, granular carbon materials, or combinations thereof, wherein the fibrous carbon materials have an aspect ratio of 10 or greater, and the granular carbon materials have an aspect ratio of less than 10. Based on the total weight of the dry negative electrode film, the content of the dry conductive material is from 0.1 wt% to 5 wt%.

14. A dry negative electrode, said dry negative electrode comprising: Negative electrode current collector; as well as The dry negative electrode membrane according to any one of claims 1 to 13 is disposed on one side or opposite sides of the negative electrode current collector.

15. The dry negative electrode according to claim 14, wherein, The negative electrode current collector includes: a substrate; and an intermediate layer disposed between the substrate and the dry negative electrode film, and The intermediate layer comprises a carbon-based conductive material.

16. The dry negative electrode according to claim 14, wherein, The dry negative electrode film includes: a first dry negative electrode film, configured to be adjacent to the negative electrode current collector; and a second dry negative electrode film, disposed on the first dry negative electrode film, and The content of the composite and the content of the binder in the first dry negative electrode film are equal to or greater than the content of the composite and the content of the binder in the second dry negative electrode film, respectively.

17. The dry negative electrode according to claim 16, wherein, The first dry negative electrode film comprises a carbon-based material and a silicon-based active material as the core of the dry composite negative electrode active material. The silicon-based active material includes a silicon composite structure, and The second dry negative electrode film includes a carbon-based material as the core of the dry composite negative electrode active material.

18. The dry negative electrode according to claim 14, wherein, The dry negative electrode film includes: a first dry negative electrode film, configured to be adjacent to the negative electrode current collector; and a second dry negative electrode film, disposed on the first dry negative electrode film. The first dry negative electrode film comprises a carbon-based material and a silicon-based active material as the core of the dry composite negative electrode active material. The second dry negative electrode film comprises a carbon-based material and a silicon-based active material as the core of the dry composite negative electrode active material. The silicon-based active material in each of the first and second dry negative electrode films includes a silicon composite structure. The content of the composite and the content of the binder in the first dry negative electrode film are equal to or greater than the content of the composite and the content of the binder in the second dry negative electrode film, respectively. The content of carbon-based materials and silicon-based active materials in the first dry negative electrode film are equal to or greater than the content of carbon-based materials and silicon-based active materials in the second dry negative electrode film, respectively.

19. A lithium battery, said lithium battery comprising: A positive electrode; a negative electrode; and an electrolyte are disposed between the positive electrode and the negative electrode, wherein, The negative electrode is the dry negative electrode according to claim 15. The electrolyte includes liquid electrolytes, solid electrolytes, gel electrolytes, or combinations thereof, and The solid electrolyte includes oxide solid electrolytes, sulfide solid electrolytes, polymer solid electrolytes, or combinations thereof.

20. The lithium battery according to claim 19, wherein, The positive electrode includes a positive current collector, the negative electrode includes a negative current collector, and both the positive current collector and the negative current collector include a substrate film and a metal layer disposed on one side or opposite sides of the substrate film. The substrate film includes a polymer, and the polymer includes polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or combinations thereof. The metal layer includes indium (In), copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or alloys thereof.

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