Dry electrode film, dry electrode including the same, and lithium battery

Abstract

a dry electrode active material and a dry binder, the dry electrode active material comprising a core and a shell disposed along a surface of the core, the shell comprising one or more first metal oxides and a first carbon-based material, the first metal oxide being disposed within a first carbon-based material matrix, and the first metal oxide having a chemical formula M a O b (0

Description

[Technical Field]

[0001] The present invention relates to a dry electrode film, a dry electrode including the same, and a lithium battery. [Background technology]

[0002] In order to meet the trend toward smaller and more powerful devices, it is becoming increasingly important to make lithium batteries not only smaller and lighter, but also to increase their energy density, i.e., to develop high-capacity lithium batteries.

[0003] Electrodes manufactured from solvent-containing slurries use excessive amounts of solvent during electrode manufacture, and dry processes that eliminate the use of such organic solvents are being investigated. Summary of the Invention [Problem to be solved by the invention]

[0004] One aspect is to provide a novel dry electrode film that has improved cycle characteristics due to reduced internal resistance and improved mechanical strength.

[0005] Another aspect is to provide a dry electrode including the dry electrode film.

[0006] Another aspect is to provide a lithium battery including the dry electrode. [Means for solving the problem]

[0007] From one aspect, A dry electrode active material and a dry binder are included, The dry electrode active material includes a core and a shell disposed along a surface of the core, the shell comprises one or more first metal oxides and a first carbon-based material; the first metal oxide is disposed within a first carbon-based material matrix; The first metal oxide has the formula M a Ob (0 < a ≤ 3, 0 < b < 4, and if a is 1, 2, or 3, then b is not an integer), and M is one or more metals selected from Groups 2 to 16 of the periodic table, a dry electrode film is provided.

[0008] On another aspect, an electrode current collector, and the dry electrode film according to the above disposed on one or both surfaces of the electrode current collector, a dry electrode is provided.

[0009] On yet another aspect, including a first electrode, a second electrode, and an electrolyte disposed between the first electrode and the second electrode, a lithium battery is provided, wherein the first electrode, the second electrode, or a combination thereof includes the dry electrode according to the above.

Advantages of the Invention

[0010] According to one aspect, the internal resistance of the dry electrode film decreases and the mechanical properties improve, thereby improving the cycle characteristics of a lithium battery employing such a dry electrode film.

Brief Description of the Drawings

[0011] [Figure 1] It is a schematic cross-sectional view of a dry electrode cathode active material according to one embodiment. [Figure 2] It is a schematic cross-sectional view of a dry electrode cathode active material according to one embodiment. [Figure 3] It is a scanning electron microscope image of the surface of bare NCA91 prepared in Comparative Example 1. [Figure 4] It is a scanning electron microscope image of the surface of the composite cathode active material manufactured in Example 1. [Figure 5] It is an XPS image of bare NCA91 prepared in Comparative Example 1, the composite manufactured in Production Example 1, and the composite cathode active material manufactured in Example 1. [Figure 6]1 shows Raman spectrum images of the composite prepared in Preparation Example 1 and the composite positive electrode active material prepared in Example 1. [Figure 7A] 1 is a scanning electron microscope image of a cross section of a dry positive electrode prepared in Comparative Example 3. [Figure 7B] 1 is a SEM-EDS mapping image of a cross section of a dry positive electrode prepared in Comparative Example 3. [Figure 8A] 1 is a scanning electron microscope image of a cross section of a dry cathode prepared in Example 4. [Figure 8B] 1 is a SEM-EDS mapping image of a cross section of the dry cathode prepared in Example 4. [Figure 9] 1 is a schematic diagram of a lithium battery according to an embodiment. [Figure 10] 1 is a schematic diagram of a lithium battery according to an embodiment. [Figure 11] 1 is a schematic diagram of a lithium battery according to an embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Various embodiments are illustrated in the accompanying drawings. However, the present invention may be embodied in various other forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Like reference numerals refer to like elements throughout.

[0013] When an element is referred to as being "on" another element, it will be understood that it may be directly on top of the other element, or that there may be other intervening elements. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements.

[0014] Terms such as "first," "second," and "third" may be used herein to describe various components, components, regions, layers, and / or sections, but these components, components, regions, layers, and / or sections should not be limited by these terms. These terms are used only to distinguish one component, component, region, layer, or section from another component, component, region, layer, or section. Thus, a first component, component, region, layer, or section described below may be referred to as a second component, component, region, layer, or section without departing from the teachings of this specification.

[0015] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the invention. As used herein, the singular forms "a," "an," "the ...

[0016] Spatially relative terms such as "below," "lower," "bottom," "top," "upper," and "top" may be used herein to easily describe the relationship of one component or feature to another. It will be understood that spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were inverted, a component described as "below" or "below" another component or feature would be oriented "above" that other component or feature. Thus, the exemplary term "below" can encompass both an orientation of above and below. The device could be otherwise oriented (rotated 90 degrees or rotated in another direction), and the spatially relative terms used herein interpreted accordingly.

[0017] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by a person of ordinary skill in the art to which this disclosure belongs. Furthermore, terms as defined in commonly used dictionaries should be interpreted as having a meaning consistent with the context of the relevant art and the contents of this disclosure, and should not be interpreted as idealized or overly formal.

[0018] Example embodiments are described herein with reference to cross-section 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. Therefore, the embodiments described herein should not be construed as limited to the specific shapes of regions as illustrated herein but are to include deviations in shape that, for example, result from manufacturing. For example, a region illustrated or described as flat typically has rough and / or non-linear features. Additionally, corners illustrated as sharp may also be rounded. Accordingly, regions illustrated in the figures are schematic in nature, and their shapes are not intended to illustrate the precise shape of the regions and are not intended to limit the scope of the claims.

[0019] "Group" means a group of the Periodic Table of Elements according to the International Union of Pure and Applied Chemistry ("IUPAC") Groups 1-18 classification system.

[0020] In this specification, "particle size" refers to the average diameter when the particles are spherical, and refers to the average major axis length when the particles are non-spherical. Particle size can be measured using a particle size analyzer (PSA). "Particle size" refers to, for example, the average particle size. "Average particle size" refers to, for example, D50, which is the median particle size.

[0021] D50 is the particle size corresponding to 50% cumulative volume calculated from the smallest particle size in the particle size distribution measured by laser diffraction.

[0022] D90 is the particle size corresponding to the 90% cumulative volume calculated from the smallest particle size in the particle size distribution measured by laser diffraction.

[0023] D10 is the particle size corresponding to 10% cumulative volume calculated from the small particle side in the particle size distribution measured by laser diffraction method.

[0024] As used herein, "metal" includes both metals and metalloids such as silicon and germanium, in either the elemental or ionic state.

[0025] In the present invention, "alloy" means a mixture of two or more metals.

[0026] In the present invention, the term "electrode active material" refers to an electrode material that can be lithiated and delithiated.

[0027] In the present invention, the term "positive electrode active material" refers to a positive electrode material that can be lithiated and delithiated.

[0028] In the present invention, the term "negative electrode active material" refers to a negative electrode material that can be lithiated and delithiated.

[0029] As used herein, "lithiation" and "lithiating" refer to the process of adding lithium to an electrode active material.

[0030] In the present invention, the terms "delithiation" and "delithiating" refer to the process of removing lithium from an electrode active material.

[0031] As used herein, "charge" and "charging" refer to the process of providing electrochemical energy to a battery.

[0032] As used herein, "discharge" and "discharging" refer to the process of removing electrochemical energy from a battery.

[0033] As used herein, "positive electrode" and "cathode" refer to electrodes where electrochemical reduction and lithiation occur during the discharge process.

[0034] As used herein, "negative electrode" and "anode" refer to electrodes where electrochemical oxidation and delithiation occur during the discharge process.

[0035] While particular embodiments have been described, presently unforeseen or unanticipated alternatives, modifications, variations, improvements, and substantial equivalents may occur to applicant or those skilled in the art. Accordingly, the claims as filed and as they may be amended are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0036] Hereinafter, a dry electrode film, a dry electrode including the same, and a lithium battery according to example embodiments will be described in detail.

[0037] According to an embodiment, the dry electrode film includes a dry electrode active material and a dry binder. The dry electrode active material includes a core and a shell disposed along a surface of the core. The shell includes one or more first metal oxides and a first carbon-based material. The first metal oxide is disposed in a first carbon-based material matrix. The first metal oxide has a chemical formula M a O b(0 < a ≤ 3, 0 < b < 4, and if a is 1, 2, or 3, then b is not an integer), and M is one or more metals selected from Groups 2 to 16 of the Periodic Table. Referring to FIG. 1, the dry electrode active material 100 includes a core 10 and a shell 20 disposed continuously or discontinuously along the surface of the core 10. The shell 20 can cover all or part of the core 10. The shell 20 includes a first metal oxide 21 and a first carbon-based material 22. The dry electrode active material is, for example, an electrode active material that is not impregnated, dissolved, or dispersed in a process solvent during the dry electrode film manufacturing process. The dry electrode active material is, for example, an electrode active material that includes a process solvent or does not contact a process solvent during the dry electrode film manufacturing process.

[0038] Since the dry electrode active material has a core / shell structure and the shell contains a first carbon-based material, the dry electrode active material and the dry binder can be more uniformly mixed. Therefore, aggregation of the dry binder in the dry electrode film is suppressed, and the dry binder can be three-dimensionally uniformly distributed. By suppressing local resistance regions in the dry electrode film, the imbalance of current density is reduced, and the overall internal resistance of the dry electrode film can be reduced.

[0039] Since the dry electrode active material has a core / shell structure and the shell contains a first carbon-based material, the interfacial resistance between the dry electrode active materials can be reduced. Since the dry electrode active material has a core / shell structure and the shell contains a first carbon-based material, the internal resistance of the dry electrode film can be reduced. Since the dry electrode active material has a core / shell structure and the shell contains a first carbon-based material, the adhesion between the dry electrode active material and the dry binder can be improved. Since the dry electrode active material has a core / shell structure and the shell contains a first carbon-based material, mechanical properties such as the tensile strength of the dry electrode film can be improved. By reducing the internal resistance of the dry electrode film and improving the mechanical properties, the cycle characteristics of a lithium battery including such a dry electrode film can be improved.

[0040] When the shell contains the first metal oxide, the ionic conductivity is improved compared to a shell made of a carbonaceous material, and as a result, the ionic conductivity of the dry electrode active material can be improved.

[0041] The dry electrode active material may have a core / shell structure, with the shell being disposed continuously or discontinuously along the surface of the core. The shell may be more uniformly disposed on the core by including a first metal oxide disposed in a first carbon-based material matrix. The shell may be more uniformly disposed on the core without agglomeration, for example, by being introduced onto the core from a composite including the first metal oxide disposed in a first carbon-based material matrix. The uniformly disposed shell on the core effectively blocks contact between the core and the electrolyte, thereby preventing side reactions due to contact between the core and the electrolyte. Furthermore, cation mixing due to contact between the core and the electrolyte is suppressed, thereby suppressing the formation of a resistive layer on the core surface. Furthermore, the introduction of a shell on the core may suppress the elution of transition metal ions from the core, even in a transition metal-containing core. The first carbon-based material may be, for example, a crystalline carbon-based material. The first carbon-based material may be, for example, a carbon-based nanostructure. The first carbon-based material may be, for example, a two-dimensional carbon-based nanostructure. For example, the first carbon-based material may be graphene. For example, a shell containing graphene and / or its matrix is ​​flexible and can easily accommodate volume changes in the dry electrode active material during charge and discharge, thereby suppressing cracks within the dry electrode active material. Graphene has high electronic conductivity, which reduces the interfacial resistance between the dry electrode active material and the electrolyte. Therefore, despite the introduction of a shell containing graphene, an increase in the internal resistance of a lithium battery can be suppressed. Meanwhile, conventional carbon-based materials that do not contain a first metal oxide easily aggregate, making it difficult to uniformly arrange them on the core of the dry electrode active material. Furthermore, since the first carbon-based material matrix is ​​derived from, for example, a graphene matrix, it has a relatively low density and a high porosity compared to conventional carbon-based materials derived from graphite-based materials.

[0042] The dry electrode active material has a core / shell structure. The shell contains a first metal oxide, and the metal contained in the first metal oxide is selected from one or more of, for example, Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se. The first metal oxide is, for example, 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[[ID=2x3]] 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 (0 < y < 2) is selected from one or more of them. By arranging such a first metal oxide in the first carbon-based material matrix, the uniformity of the shell disposed on the core is improved, and the high-voltage resistance of the dry electrode active material is further improved. The shell contains, for example, Al2O x (0 < x < 3).

[0043] The shell may further contain one or more second metal oxides. The second metal oxide is, for example, the chemical formula M a O c(0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, c is an integer), and M is one or more metals selected from Groups 2 to 13, Group 15, and Group 16 of the periodic table. The second metal oxide may, for example, contain the same metal as the first metal oxide. The ratio c / a of a and c of the second metal oxide has a value greater than the ratio b / a of a and b of the first metal oxide. For example, c / a > b / a. The second metal oxide may be disposed within the first carbon-based material matrix. The second metal oxide is selected from, for example, Al2O3, NbO, NbO2, Nb2O5, MgO, Sc2O3, TiO2, ZrO2, V2O3, WO2, MnO2, Fe2O3, Co3O4, PdO, CuO, AgO, ZnO, Sb2O3, and SeO2. The first metal oxide is, for example, a reduction product of the second metal oxide. The first metal oxide is obtained by reducing part or all of the second metal oxide. Therefore, the first metal oxide has a lower oxygen content and a lower oxidation number of the metal compared to the second metal oxide. For example, the shell is the first metal oxide Al x (0 < x < 3) and contains Al2O3 as the second metal oxide.

[0044] The shell contains, for example, one or more selected from the first metal oxide and the second metal oxide, and the particle size of one or more selected from the first metal oxide and the second metal oxide is, for example, 0.1 nm to 100 nm, 0.5 nm to 100 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, 5 nm to 30 nm, or 10 nm to 30 nm. By having such a nano-scale particle size for the first metal oxide and / or the second metal oxide, it can be more uniformly distributed within the first carbon-based material matrix. If the particle size of one or more of the first metal oxide and the second metal oxide increases excessively, the internal resistance of the composite electrode active material may increase due to an increase in the shell thickness. If the particle size of one or more of the first metal oxide and the second metal oxide decreases excessively, uniform dispersion is also difficult.

[0045] The shell may include a first metal oxide and / or a second metal oxide and may include a first carbon-based material. The first carbon-based material may be arranged in a direction protruding from the surface of the first metal oxide and / or the second metal oxide. The first carbon-based material may be arranged in a direction protruding from the surface of the first metal oxide and / or the second metal oxide by growing directly from the surface of the first metal oxide and / or the second metal oxide. The first carbon-based material arranged in a direction protruding from the surface of the first metal oxide and / or the second metal oxide may be, for example, a carbon-based two-dimensional nanostructure, a carbon-based flake, or graphene.

[0046] The shell thickness is, for example, 0.1 nm to 5 μm, 0.5 nm to 5 μm, 1 nm to 5 μm, 1 nm to 1 μm, 1 nm to 500 nm, 1 nm to 200 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 20 nm. When the shell has a thickness within this range, the electronic conductivity of the dry electrode including the dry electrode active material can be further improved, and the internal resistance can be further reduced.

[0047] The shell may have a single-layer structure or a multi-layer structure. The multi-layer structure may be, for example, a two-layer structure, a three-layer structure, or a four-layer structure. In the multi-layer structure, for example, each layer may contain a different type of metal in the first metal oxide.

[0048] The content of the shell is, for example, 0.01 wt% to 5 wt%, 0.01 wt% to 3 wt%, 0.01 wt% to 2 wt%, or 0.01 wt% to 1 wt% of the total weight of the dry electrode active material. The content of the first metal oxide is, for example, 0.006 wt% to 3 wt%, 0.06 wt% to 1.8 wt%, 0.006 wt% to 1.2 wt%, or 0.006 wt% to 0.6 wt% of the total weight of the dry electrode active material. When the dry electrode active material contains the shell and the first metal oxide in such content ranges, the cycle characteristics of the lithium battery are further improved.

[0049] The dry electrode active material may further include, for example, a third metal doped onto the core or a third metal oxide coated on the core. The shell may then be disposed on the third metal doped onto the core or the third metal oxide coated on the core. For example, the third metal may be doped onto the surface of a compound contained in the core, such as a lithium transition metal oxide, or the third metal oxide may be coated onto the surface of a compound contained in the core, such as a lithium transition metal oxide, and then the shell may be disposed on the third metal and / or the third metal oxide. The dry electrode active material may include, for example, a core, an intermediate layer disposed on the core, and a shell disposed on the intermediate layer, wherein the intermediate layer includes a third metal or a third metal oxide. The third metal may be one or more metals selected from Al, Zr, W, and Co, and the third metal oxide may be Al2O3, Li2O-ZrO2, WO2, CoO, Co2O3, Co3O4, or a combination thereof.

[0050] The shell disposed along the surface of the core may be, for example, a dry coating layer. The shell may be applied to the core by a dry method such as milling. The shell may include, for example, one or more selected from a composite including a first metal oxide and a first carbon-based material, such as graphene, and a milling product of the composite. The first metal oxide is disposed within a matrix of the first carbon-based material, such as a graphene matrix.

[0051] The shell is made of a composite including, for example, a first metal oxide and a first carbon-based material, such as graphene. The composite may further include a second metal oxide in addition to the first metal oxide. The composite may include, for example, two or more first metal oxides. The composite may include, for example, two or more first metal oxides and two or more second metal oxides.

[0052] The content of one or more of the composite and its milling products is, for example, 5 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, or 0.5 wt% or less of the total weight of the dry electrode active material. The content of one or more of the composite and its milling products may be 0.01 wt% to 5 wt%, 0.01 wt% to 3 wt%, 0.01 wt% to 1 wt%, 0.01 wt% to 0.7 wt%, or 0.01 wt% to 0.5 wt% of the total weight of the dry electrode active material. When the dry electrode active material contains one or more of the composite and its milling products within these ranges, the cycle characteristics of a lithium battery including the dry electrode active material are further improved.

[0053] The composite may include one or more selected from a first metal oxide and a second metal oxide. The particle size of the one or more selected from the first metal oxide and the second metal oxide may be 0.1 nm to 100 nm, 0.5 nm to 100 nm, 1 nm to 100 nm, 1 nm to 50 nm, 1 nm to 30 nm, 5 nm to 30 nm, or 10 nm to 30 nm. When the first metal oxide and / or the second metal oxide have such nano-sized particle sizes, they can be more uniformly distributed within the first carbon-based material matrix of the composite. Therefore, such a composite can be uniformly coated on the core without agglomeration to form a shell. Furthermore, when the first metal oxide and / or the second metal oxide have particle sizes in such ranges, they can be more uniformly arranged on the core. Therefore, the uniform arrangement of the first metal oxide and / or the second metal oxide on the core can more effectively exhibit voltage resistance characteristics. The particle size of the first metal oxide and / or the second metal oxide is measured, for example, using a laser diffraction or dynamic light scattering measuring device. The particle size is measured, for example, using a laser scattering particle size distribution analyzer (e.g., HORIBA LA-920) and is the median particle size (D50) value when 50% of the smallest particles are accumulated in volume. The uniformity deviation of one or more selected from the first metal oxide and / or the second metal oxide is 3% or less, 2% or less, or 1% or less. The uniformity can be determined, for example, by XPS. Therefore, one or more selected from the first metal oxide and the second metal oxide can be uniformly distributed within the composite with a deviation of 3% or less, 2% or less, or 1% or less.

[0054] The composite includes a first carbon-based material. The first carbon-based material may have, for example, a branched structure, and one or more metal oxides selected from a first metal oxide and a second metal oxide may be distributed within the branched structure of the first carbon-based material. The branched structure of the first carbon-based material may include, for example, a plurality of first carbon-based material particles that are in contact with each other. The branched structure of the first carbon-based material may provide various conductive paths. The first carbon-based material may be, for example, graphene. The graphene may have, for example, a branched structure, and one or more metal oxides selected from a first metal oxide and a second metal oxide may be distributed within the branched structure of the graphene. The branched structure of the graphene may include, for example, a plurality of graphene particles that are in contact with each other. The branched structure of the graphene may provide various conductive paths.

[0055] The first carbon-based material may have, for example, a spherical structure, and one or more metal oxides selected from the first metal oxide and the second metal oxide may be distributed within the spherical structure. The size of the spherical structure of the first carbon-based material may be 50 nm to 300 nm. There may be a plurality of first carbon-based materials having a spherical structure. Since the first carbon-based material has a spherical structure, the composite has a rigid structure. The first carbon-based material may be, for example, graphene. The graphene may have, for example, a spherical structure, and one or more metal oxides selected from the first metal oxide and the second metal oxide may be distributed within the spherical structure. The size of the spherical structure of the graphene may be 50 nm to 300 nm. There may be a plurality of graphenes having a spherical structure. Since the graphene has a spherical structure, the composite has a rigid structure.

[0056] The first carbon-based material may have a spiral structure in which a plurality of spherical structures are connected, and one or more metal oxides selected from the first metal oxide and the second metal oxide may be distributed within the spiral structures. The size of the spiral structure of the first carbon-based material is 500 nm to 100 μm. The first carbon-based material has a spiral structure, which allows the composite to have a rigid structure. The first carbon-based material may also be graphene. Graphene may have a spiral structure in which a plurality of spherical structures are connected, and one or more metal oxides selected from the first metal oxide and the second metal oxide may be distributed within the spiral structures. The size of the spiral structure of graphene is 500 nm to 100 μm. The graphene has a spiral structure, which allows the composite to have a rigid structure.

[0057] The first carbon-based material may have a cluster structure in which a plurality of spherical structures are aggregated, and one or more metal oxides selected from the first metal oxide and the second metal oxide may be distributed within the spherical structures. The size of the cluster structure of the first carbon-based material may be 0.5 mm to 10 mm. As the first carbon-based material has a cluster structure, the composite has a robust structure. The first carbon-based material may be graphene, for example. Graphene may have a cluster structure in which a plurality of spherical structures are aggregated, and one or more metal oxides selected from the first metal oxide and the second metal oxide may be distributed within the spherical structures. The size of the graphene cluster structure may be 0.5 mm to 10 mm. As the graphene has a cluster structure, the composite has a robust structure.

[0058] The composite may have, for example, a faceted-ball structure, and one or more selected from the first metal oxide and the second metal oxide may be distributed inside or on the surface of the structure. Such a faceted-ball structure allows the composite to be easily coated on the irregular surface irregularities of the core.

[0059] The composite may have a planar structure, for example, and one or more selected from the first metal oxide and the second metal oxide may be distributed inside or on the surface of the structure. Such a two-dimensional planar structure of the composite allows the composite to be easily coated on the irregular surface irregularities of the core.

[0060] The first carbon-based material may extend over the first metal oxide for a distance of 10 nm or less and include at least 1 to 20 carbon-based material layers. For example, a plurality of first carbon-based material layers may be stacked to form a first carbon-based material having a total thickness of 12 nm or less on the first metal oxide. For example, the total thickness of the first carbon-based material may be 0.6 nm to 12 nm. The first carbon-based material may be, for example, graphene. The graphene may extend over the first metal oxide for a distance of 10 nm or less and include at least 1 to 20 graphene layers. For example, a plurality of graphene layers may be stacked to form a first carbon-based material having a total thickness of 12 nm or less on the first metal oxide. For example, the total thickness of the graphene may be 0.6 nm to 12 nm.

[0061] The shell may further include, for example, a second carbon-based material distinct from the first carbon-based material. The shell may further include, for example, fibrous carbon having an aspect ratio of 10 or more. This may further lengthen the conductive path of the dry electrode active material. The second carbon-based material may form a three-dimensional conductive network between the dry electrode active materials, thereby reducing the internal resistance of the dry electrode including the dry electrode active material. The fibrous carbon fixed on the dry electrode active material may form a uniform and stable three-dimensional conductive network between the dry electrode active materials. Therefore, the dry electrode active material including the second carbon-based material may improve the high-rate performance of a lithium battery including the dry electrode active material. On the other hand, a simple mixture of the core and the second carbon-based material, i.e., fibrous carbon, may have difficulty forming a uniform three-dimensional conductive network between the multiple core particles due to agglomeration of the fibrous carbon. The second carbon-based material 23 may be disposed on the surface of the dry electrode active material 100.

[0062] Referring to FIG. 2 , the dry electrode active material 100 includes a core 10 and a shell 20 disposed continuously or discontinuously along the surface of the core 10. The shell 20 may cover all or a portion of the core 10. The shell 20 includes a first metal oxide 21, a first carbon-based material 22, and a second carbon-based material 23. The second carbon-based material 23 may protrude from the surface of the dry electrode active material 100. The second carbon-based material 23 may effectively provide a conductive network between the plurality of dry electrode active materials 100. The second carbon-based material 23 may be disposed within the matrix of the first carbon-based material 22, thereby allowing the second carbon-based material 23 to be easily coated onto the core 10. The matrix of the first carbon-based material 22 may act as a binder binding the core and the second carbon-based material 23. Therefore, without the matrix of the first carbon-based material 22, the second carbon-based material 23 may not be easily attached to the core 10, or the second carbon-based material 23 may be easily detached from the core 10 during the preparation of a positive electrode slurry. When a binder is added to bind the lithium transition metal oxide core 20 and the second carbon-based material 23, the core 10 is coated with an insulating binder, which may increase the internal resistance of the dry electrode active material 100. When the second carbon-based material and the core coated with the binder are heat-treated at high temperature to carbonize the binder, the core 10 and the second carbon-based material 23 may be deteriorated during the heat-treatment process.

[0063] The aspect ratio of the second carbon-based material is equal to or greater than 10 or equal to or greater than 20. The aspect ratio of the second carbon-based material is, for example, 10 to 100,000, 10 to 80,000, 10 to 50,000, 10 to 10,000, 10 to 5000, 10 to 1000, 10 to 500, 10 to 100, or 10 to 50. The aspect ratio of the second carbon-based material is, for example, the ratio of the major axis length passing through the center of the second carbon-based material, i.e., the ratio of the minor axis length passing through the center of the second carbon-based material and perpendicular to the major axis, i.e., the diameter of the second carbon-based material.

[0064] The diameter of the second carbon-based material is, for example, 50 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. The diameter of the second carbon-based material is, for example, 1 nm to 50 nm, 1 nm to 30 nm, or 1 nm to 10 nm. If the diameter of the second carbon-based material is too large, the absolute number per volume decreases, and the effect of reducing internal resistance is negligible. If the diameter of the second carbon-based material is too small, uniform dispersion is difficult.

[0065] The length of the second carbon-based material is, for example, 1000 μm or less, 100 μm or less, 50 μm or less, 10 μm or less, 5 μm or less, 2 μm or less, 1 μm or less, 500 nm or less, or 300 nm or less. The length of the second carbon-based material is, for example, 100 nm to 1000 μm, 100 nm to 500 μm, 100 nm to 100 μm, 100 nm to 50 μm, 100 nm to 10 μm, 100 nm to 5 μm, 100 nm to 2 μm, 100 nm to 1 μm, 100 nm to 500 nm, or 100 nm to 300 nm. The length of the second carbon-based material is, for example, 500 nm to 1000 μm, 500 nm to 500 μm, 500 nm to 100 μm, 500 nm to 50 μm, 500 nm to 10 μm, 500 nm to 5 μm, or 500 nm to 2 μm. The longer the length of the second carbon-based material, the lower the internal resistance of the electrode. If the length of the second carbon-based material is too short, it is difficult to provide an effective conductive path.

[0066] The second carbon-based material can include, for example, carbon nanofibers, carbon nanotubes, or a combination thereof.

[0067] The carbon nanotubes may 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.

[0068] The primary structure of a carbon nanotube is one carbon nanotube unit. A carbon nanotube unit has a cylindrical graphite sheet with a nano-sized diameter and an sp2 bond structure. Depending on the bending angle and structure of the graphite sheet, it can exhibit conductive or semiconductive properties. Carbon nanotube units can be classified into single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), and multi-walled carbon nanotubes (MWCNTs) depending on the number of bonds forming the wall. The thinner the wall thickness of a carbon nanotube unit, the lower the resistance.

[0069] The carbon nanotube primary structure may 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 carbon nanotube primary structure is, for example, 1 nm or more, or 2 nm or more. The diameter of the carbon nanotube primary structure is, for example, 20 nm or less, or 10 nm or less. The diameter of the carbon nanotube primary structure is, for example, 1 nm to 20 nm, 1 nm to 15 nm, or 1 nm to 10 nm. The length of the carbon nanotube primary structure is, for example, 100 nm or more, or 200 nm or more. The length of the carbon nanotube primary structure is, for example, 2 μm or less, 1 μm or less, 500 nm or less, or 300 nm or less. The length of the carbon nanotube primary structure is, for example, 100 nm to 2 μm, 100 nm to 1 μm, 100 nm to 500 nm, 100 nm to 400 nm, 100 nm to 300 nm, or 200 nm to 300 nm. The diameter and length of the carbon nanotube primary structure can be measured from a scanning electron microscope (SEM) or transmission electron microscope (TEM) image. Alternatively, the diameter and / or length of the carbon nanotube primary structure can be measured by laser diffraction.

[0070] A carbon nanotube secondary structure is a structure formed by assembling carbon nanotube primary structures entirely or partially into a bundle or rope shape. The carbon nanotube secondary structure may include, for example, bundle-type carbon nanotubes, rope-type carbon nanotubes, or a combination thereof. The diameter of the carbon nanotube secondary structure is, for example, 2 nm or more or 3 nm or more. The diameter of the carbon nanotube secondary structure is, for example, 50 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. The diameter of the carbon nanotube secondary structure is, for example, 2 nm to 50 nm, 2 nm to 30 nm, or 2 nm to 20 nm. The length of the carbon nanotube secondary structure is, for example, 500 nm or more, 700 nm or more, 1 μm or more, or 10 μm or more. The length of the carbon nanotube secondary structures is, for example, 1000 μm or less, 500 μm or less, or 100 μm or less. The length of the carbon nanotube secondary structures is, for example, 500 nm to 1000 μm, 500 nm to 500 μm, 500 nm to 200 μm, 500 nm to 100 μm, or 500 nm to 50 μm. The diameter and length of the carbon nanotube secondary structures can be measured from a scanning electron microscope (SEM) image or an optical microscope. Alternatively, the diameter and / or length of the carbon nanotube secondary structures can be measured by laser diffraction.

[0071] The carbon nanotube secondary structure can be converted into a carbon nanotube primary structure by dispersing it in a solvent, for example, and then used in the dry production of an electrode active material.

[0072] The content of the second carbon-based material is, for example, 0.1 wt% to 50 wt%, 1 wt% to 40 wt%, or 5 wt% to 30 wt% based on the total weight of the first carbon-based material and the second carbon-based material. By including the first carbon-based material and the second carbon-based material within such ranges in the dry electrode active material, a conduction path can be more effectively ensured within the dry electrode active material, and the internal resistance of the dry electrode active material can be further reduced. As a result, the cycle characteristics of the lithium battery including the dry electrode active material can be further improved. The content of the second carbon-based material is, for example, 0.001 wt% to 5 wt%, 0.01 wt% to 3 wt%, 0.01 wt% to 1 wt%, 0.01 wt% to 0.5 wt%, or 0.01 wt% to 0.1 wt% based on the total weight of the dry electrode active material. By including the second carbon-based material within such ranges in the dry electrode active material, a conduction path can be ensured within the dry electrode active material, and the internal resistance of the dry electrode active material can be further reduced. As a result, the cycle characteristics of the lithium battery including the dry electrode active material can be further improved.

[0073] The dry electrode active material includes a core, and the core can include, for example, a lithium transition metal oxide.

[0074] The core can include, for example, a compound selected from among the lithium transition metal oxides represented by the following Chemical Formulas 1 to 8.

[0075] <Chemical Formula 1> Li a Ni x Co y M z O 2-b A b In the Chemical Formula 1, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.8 ≤ x < 1, 0 ≤ y ≤ 0.3, 0 < z ≤ 0.3, and x + y + z = 1, M is 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), boron (B) or a combination thereof, A is F, S, Cl, Br or a combination thereof, <Chemical formula 2> LiNi x Co y Mn z O2 <Chemical formula 3> LiNi x Co y Al z O2 In the chemical formulas 2 to 3, 0.8 ≦ x ≦ 0.95, 0 ≦ y ≦ 0.2, 0 < z ≦ 0.2 and x + y + z = 1, <Chemical formula 4> LiNi x Co y Mn z Al w O2 In the chemical formula 4, 0.8 ≦ x ≦ 0.95, 0 ≦ y ≦ 0.2, 0 < z ≦ 0.2, 0 < w ≦ 0.2, and x + y + z + w = 1, <Chemical formula 5> Li a Co x M y O 2-b A b In the chemical formula 5, 1.0 ≦ a ≦ 1.2, 0 ≦ b ≦ 0.2, 0.9 ≦ x ≦ 1, 0 ≦ y ≦ 0.1, and x + y = 1, M is 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), boron (B) or a combination thereof, A is F, S, Cl, Br or a combination thereof, <Chemical formula 6> Li a Nix Mn y M’ z O 2-b A b In Chemical Formula 6, 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’ is 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, A is F, S, Cl, Br or a combination thereof, <Chemical Formula 7> Li a M1 x M2 y PO 4-b X b In Chemical Formula 7, 0.90 ≦ a ≦ 1.1, 0 ≦ x ≦ 0.9, 0 ≦ y ≦ 0.5, 0.9 < x + y < 1.1, 0 ≦ b ≦ 2, M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr) or a combination thereof, M2 is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zinc (Zn), boron (B), niobium (Nb), gallium (Ga), indium (In), molybdenum (Mo), tungsten (W), aluminum (Al), silicon (Si), chromium (Cr), vanadium (V), scandium (Sc), yttrium (Y) or a combination thereof, and X is O, F, S, P or a combination thereof.

[0076] <Chemical Formula 8> Li a M3 z PO4 In Chemical Formula 8, 0.90 ≦ a ≦ 1.1, 0.9 ≦ z ≦ 1.1, M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof.

[0077] The shell includes a first metal oxide and a first carbon-based material, and the core includes, for example, a lithium transition metal oxide. The first carbon-based material and the transition metal of the lithium transition metal oxide may be chemically bound, for example, via a chemical bond. The carbon atom (C) of the first carbon-based material and the transition metal (Me) of the lithium transition metal oxide may be chemically bound, for example, via a CO-Me bond (e.g., a CO-Ni bond or a CO-Co bond) mediated by an oxygen atom. The first carbon-based material disposed in the shell and the lithium transition metal oxide disposed in the core are chemically bound through a chemical bond, thereby forming a composite of the core and shell. Therefore, the dry electrode active material is distinguished from a simple physical mixture or blend of the first carbon-based material and the lithium transition metal oxide. The first metal oxide and the first carbon-based material may also be chemically bound through a chemical bond. Here, the chemical bond may be, for example, a covalent bond or an ionic bond.

[0078] The dry electrode active material may include, for example, a first dry electrode active material and a second dry electrode active material, which may have different particle sizes.

[0079] The first dry electrode active material may be, for example, a large-diameter dry electrode active material having a larger particle size than the second dry electrode active material. The second dry electrode active material may be, for example, a small-diameter dry electrode active material having a smaller particle size than the first dry electrode active material. For example, the first dry electrode active material may be a large-diameter dry electrode active material, and the second dry electrode active material may be a small-diameter dry electrode active material. For example, a second dry electrode active material having a smaller average particle size than the first dry electrode active material may be disposed in the gaps between the first dry electrode active materials. By disposing the small-diameter second dry electrode active material particles in the gaps between the large-diameter first dry electrode active material particles, the ionic conductivity and electronic conductivity of a dry electrode including the dry electrode active material may be simultaneously improved. In addition, the energy density of a dry electrode including the dry electrode active material may be further improved. As a result, the energy density and cycle characteristics of a lithium battery including the dry electrode active material may be improved.

[0080] The first and second dry electrode active materials have, for example, a bimodal particle size distribution in a particle size distribution diagram. For example, the composite positive electrode active material has a bimodal particle size distribution with two peaks in a particle size distribution diagram obtained using a particle size analyzer (PSA). The bimodal particle size distribution has a first peak corresponding to the first dry electrode active material and a second peak corresponding to the second dry electrode active material.

[0081] The particle size ratio of the first dry electrode active material to the second dry electrode active material may be, for example, 3:1 to 40:1, 3:1 to 30:1, 3:1 to 20:1, 3:1 to 10:1, or 3:1 to 5:1. When the first dry electrode active material to the second dry electrode active material have a particle size ratio within such a range, the energy density and cycle characteristics of a lithium battery including the composite positive electrode active material may be further improved.

[0082] The particle size of the first dry electrode active material is, for example, more than 8 μm to 30 μm, 9 μm to 25 μm, 9 μm to 20 μm, 9 μm to 15 μm, or 9 μm to 12 μm. The particle size of the first dry electrode active material is also, for example, the median particle size (D50). The particle size of the second dry electrode active material is, for example, 1 μm to less than 8 μm, 1 μm to 7 μm, 1 μm to 6 μm, 1 μm to 5 μm, or 1 μm to 4 μm. The particle size of the first dry electrode active material is also, for example, the median particle size (D50). When the first dry electrode active material and the second dry electrode active material have average particle sizes within such ranges, the energy density and / or cycle characteristics of a lithium battery including the composite positive electrode active material can be further improved. The particle sizes of the first dry electrode active material and the second dry electrode active material are measured, for example, using a measuring device using a laser diffraction method or a dynamic light scattering method. The particle size is measured, for example, using a laser scattering particle size distribution analyzer (e.g., HORIBA LA-920) and is the median particle size (D50) value when 50% of the particles are accumulated from the smallest particle side in volume conversion. Alternatively, the particle sizes of the first and second dry electrode active materials can be measured from scanning electron microscope (SEM) images or optical microscopes.

[0083] The weight ratio of the first dry electrode active material to the second dry electrode active material is, for example, 90:10 to 60:40, 85:15 to 65:35, 80:20 to 65:35, or 75:25 to 65:35. When the weight ratio of the first dry electrode active material to the second dry electrode active material is within such a range, the energy density and / or cycle characteristics of a lithium battery including the composite positive electrode active material may be further improved.

[0084] The dry electrode film includes a dry binder. The dry binder is, for example, a binder that is impregnated, dissolved, or not dispersed in a process solvent during the manufacturing process of the dry electrode film. The dry binder is, for example, a binder that contains a process solvent or does not come into contact with a process solvent during the manufacturing process of the dry electrode film. The dry binder is, for example, a fibrillated binder or a fibrous binder. The fibrillated binder or fibrous binder can serve as a matrix that supports and binds the electrode active material and other components contained in the electrode active material layer. The fibrillated binder or fibrous binder can be confirmed to have a fibrous morphology, for example, in a scanning electron microscope image of the electrode cross section. The fibrillated binder or fibrous binder has an aspect ratio of, for example, 10 or more, 20 or more, 50 or more, or 100 or more.

[0085] Examples of dry binders include, but are not limited to, polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexapropylene (PVDF-HFP) copolymer, polyvinylidene fluoride (PVDF), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, cellulose, polyvinylpyrrolidone, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, and copolymers thereof. Any binder used in the manufacture of dry electrodes can be used. Dry binders may particularly include fluorine-based binders. Examples of fluorine-based binders include polytetrafluoroethylene (PTFE), polyvinylidene fluoride-hexapropylene (PVDF-HFP) copolymer, and polyvinylidene fluoride (PVDF).

[0086] The glass transition temperature (Tg) of the dry binder is, for example, -30°C to 150°C, 15°C to 150°C, 15°C to 130°C, 50°C to 130°C, 100°C to 130°C, or 120°C to 130°C. The glass transition temperature (Tg) of the dry binder is, for example, -30°C to 150°C, -30°C to 100°C, -30°C to 50°C, -30°C to 15°C, -30°C to -10°C, or -30°C to -20°C. The glass transition temperature of polytetrafluoroethylene (PTFE) is, for example, 120°C to 130°C. When the dry binder has a glass transition temperature in such a range, a fibrous binder or a fibrous binder can be more easily obtained during the production of a dry electrode.

[0087] The content of the dry binder is, for example, 0.1 to 5 wt%, 0.5 to 5 wt%, or 1 to 5 wt%, based on the total weight of the dry electrode film. When the dry electrode film contains a dry binder in such a range, the binding strength of the dry electrode film is improved, allowing the dry electrode film to maintain a high energy density.

[0088] The dry electrode film may further include, for example, a conductive material. The conductive material is, for example, a dry conductive material. The dry conductive material is, for example, a conductive material that is not impregnated, dissolved, or dispersed in a process solvent during the manufacturing process of the dry electrode film. The dry conductive material is, for example, a conductive material that contains a process solvent or does not come into contact with a process solvent during the manufacturing process of the dry electrode film. The dry conductive material includes, for example, a carbon-based conductive material. The carbon-based conductive material includes, for example, a fibrous carbon-based material with an aspect ratio of 10 or more, a granular carbon-based material with an aspect ratio of less than 10, or a combination thereof.

[0089] The fibrous carbon-based material having an aspect ratio of 10 or more may be, but is not limited to, a carbon fiber, a carbon nanotube, a carbon nanobelt, or the like, and any material used in the art for carbon-based conductive materials may be used. The fibrous carbon-based material having an aspect ratio of 10 or more may be selected from the second carbon-based materials described above. The fibrous carbon-based conductive material is distinguished from the second carbon-based material that constitutes a part of the dry electrode active material in that it is simply mixed with the dry electrode active material.

[0090] Examples of granular carbonaceous materials having an aspect ratio of less than 10 include, but are not limited to, carbon black, acetylene black, ketjen black, natural graphite, and artificial graphite, and any material used in the art as a carbonaceous conductive material can be used. The aspect ratio of the granular carbonaceous material is, for example, 1 to 7, 1 to 5, 1 to 3, or 1 to 2.

[0091] The content of the dry conductive material in the dry electrode film is, for example, 0.1 to 5 wt%, 0.5 to 5 wt%, or 1 to 5 wt%, based on the total weight of the dry electrode film. When the dry electrode film contains the dry conductive material in such a range, the conductivity of the dry electrode film is improved, and the cycle characteristics of a lithium battery including such a dry electrode film can be improved.

[0092] A dry electrode film is, for example, a self-standing film. A dry electrode film can maintain its film form without a support. Therefore, a dry electrode film can be prepared as a separate self-standing film and then placed on an electrode current collector. Because a dry electrode film is manufactured using a dry process, it does not contain intentionally added process solvents. For example, it does not contain residual processing solvents. Although trace amounts of unintentional solvents may remain in a dry electrode film, such solvents are not intentionally added process solvents. Therefore, a dry electrode film is distinguished from a wet electrode film, which is manufactured by mixing components and a process solvent and then drying to remove some or all of the process solvent.

[0093] The tensile strength of the dry electrode film at 25°C is, for example, 500 kPa or more, 700 kPa or more, or 1000 kPa or more. The tensile strength of the dry electrode film at 25°C is, for example, 500 kPa to 5000 kPa, 700 kPa to 5000 kPa, or 1000 kPa to 5000 kPa. When the dry electrode film has a tensile strength in this range, the structural stability of the dry electrode film can be improved. Therefore, the dry electrode film maintains a stable three-dimensional conductive network during charge and discharge, improving the plasticity of the electrode reaction. When the dry electrode film has a high tensile strength in this range, the mechanical strength of the dry electrode film can be improved. The improved mechanical strength of the dry electrode film can suppress localized deterioration due to volumetric changes during charge and discharge of an electrode including the dry electrode film and a lithium battery including the same. As a result, the cycle characteristics of the lithium battery can be improved.

[0094] A dry electrode according to another embodiment includes an electrode current collector and the above-described dry electrode film disposed on one or both sides of the electrode current collector.

[0095] By including a dry electrode film in the dry electrode, the internal resistance of the dry electrode is reduced and the mechanical properties are improved.

[0096] The electrode current collector can include, for example, a substrate.

[0097] The substrate may be made of any material that is non-reactive with lithium, i.e., does not form an alloy or compound with lithium, and is electrically conductive. The substrate may be, for example, a metal or alloy. The substrate may be made of, 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 an alloy thereof. The substrate may have a form selected from, for example, a sheet, foil, film, plate, porous material, mesoporous material, through-hole-containing material, polygonal ring, mesh, foam, and nonwoven fabric. However, the substrate is not necessarily limited to such a form, and any form commonly used in the art may be used.

[0098] The electrode current collector may include, for example, a substrate and an interlayer disposed between the substrate and the dry electrode film, and the interlayer may include, for example, a carbon-based conductive material.

[0099] The interlayer may be disposed directly on one or both surfaces of the substrate, with no other layers disposed between the substrate and the interlayer. By disposing the interlayer directly on one or both surfaces of the substrate, the bonding strength between the substrate and the dry electrode film may be further improved.

[0100] The thickness of the intermediate layer is, for example, 0.01 to 30%, 0.1 to 30%, 0.5 to 30%, 1 to 25%, 1 to 20%, 1 to 15%, 1 to 10%, 1 to 5%, or 1 to 3% of the thickness of the substrate. The thickness of the intermediate layer is, for example, 10 nm to 5 μm, 50 nm to 5 μm, 200 nm to 4 μm, 500 nm to 3 μm, 500 nm to 2 μm, 500 nm to 1.5 μm, or 700 nm to 1.3 μm. When the intermediate layer has a thickness within this range, the bonding strength between the substrate and the dry electrode film is further improved, and an increase in interfacial resistance is suppressed.

[0101] The intermediate layer may include, for example, a carbon-based conductive material. The carbon-based conductive material included in the intermediate layer may be selected from among the carbon-based conductive materials used in the dry electrode film. The intermediate layer may include the same carbon-based conductive material as the carbon-based conductive material used in the dry electrode film. By including a carbon-based conductive material in the intermediate layer, the intermediate layer may also be, for example, a conductive layer.

[0102] The intermediate layer may further include, for example, a binder. When the intermediate layer further includes a binder, the bonding strength between the substrate and the dry electrode film may be further improved. The binder included in the intermediate layer may be, for example, a conductive binder or a non-conductive binder. The conductive binder may be, for example, an ionically conductive binder and / or an electronically conductive binder. A binder that has both ion conductivity and electronic conductivity also belongs to the category of ionically conductive binders and electronically conductive binders.

[0103] The binder contained in the intermediate layer may be selected from binders used in dry electrode films. The intermediate layer may contain the same binder as the binder used in the dry electrode film. The binder contained in the intermediate layer may be, for example, a fluorine-based binder. The fluorine-based binder contained in the intermediate layer may be, for example, polyvinylidene fluoride (PVDF). The intermediate layer may also be, for example, a bonding layer containing a binder. The intermediate layer may also be, for example, a conductive layer containing a binder and a carbon-based conductive material.

[0104] The intermediate layer can be disposed on the substrate by, for example, a dry or wet process. The intermediate layer can be disposed on the substrate by, for example, a dry process, such as vapor deposition (CVD) or PVD. The intermediate layer can be disposed on the substrate by, for example, a wet process, such as spin coating or dip coating. The intermediate layer can be disposed on the substrate by, for example, vapor depositing a carbon-based conductive material onto the substrate. A dry-coated intermediate layer is made of a carbon-based conductive material and does not contain a binder. The intermediate layer can be disposed on the substrate by, for example, coating a composition containing a carbon-based conductive material, a binder, and a solvent onto the substrate surface and drying it. The intermediate layer can have a single-layer structure or a multilayer structure including multiple layers. The multilayer structure can be a two-layer structure, a three-layer structure, a four-layer structure, etc.

[0105] The electrode current collector may include, for example, a base film and a metal layer disposed on one or both sides of the base film. The electrode current collector may include a substrate, and the substrate may have a structure including, for example, a base film and a metal layer disposed on one or both sides of the base film. The base film may include, for example, a polymer. The polymer may also include, for example, a thermoplastic polymer. The polymer may include, for example, polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. When the base film includes a thermoplastic polymer, the base film melts in the event of a short circuit, thereby suppressing a sudden increase in current. The base film may also be, for example, an insulator. The metal layer may include, for example, indium (In), magnesium (Mg), titanium (Ti), zinc (Zn), aluminum (Al), germanium (Ge), copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The metal layer acts as an electrochemical fuse and breaks in the event of an overcurrent, preventing short circuits. The limiting current and maximum current can be adjusted by adjusting the thickness of the metal layer. The metal layer can be electrodeposited or vapor-deposited on the base film. A thinner metal layer reduces the limiting current and / or maximum current of the electrode current collector, thereby improving the stability of the lithium battery during a short circuit. A lead tab can be added to the metal layer for external connection. The lead tab can be welded to the metal layer or the metal layer / base film laminate by ultrasonic welding, laser welding, spot welding, etc. During welding, the base film and / or metal layer melts, electrically connecting the metal layer to the lead tab. A metal chip can be added between the metal layer and the lead tab to further strengthen the weld between the metal layer and the lead tab. The metal chip can be a thin piece of the same material as the metal of the metal layer. The metal chip can be, for example, a metal foil or metal mesh.The metal piece may be, for example, aluminum foil, copper foil, or SUS foil. After placing the metal piece on the metal layer, the lead tab may be welded to the metal piece / metal layer laminate or the metal piece / metal layer / base film laminate. During welding, the base film, metal layer, and / or metal piece melt, electrically connecting the metal layer or metal layer / metal piece laminate to the lead tab. A metal piece and / or lead tab may be added to a portion of the metal layer. The thickness of the base film is, for example, 1 to 50 μm, 1.5 to 50 μm, 1.5 to 40 μm, or 1 to 30 μm. The thickness of the base film within this range can further effectively reduce the weight of the electrode assembly. The melting point of the base film is, for example, 100 to 300°C, 100 to 250°C, or 100 to 200°C. When the base film has a melting point within this range, the base film melts during the welding process of the lead tab, allowing it to be easily bonded to the lead tab. To improve the adhesion between the base film and the metal layer, a surface treatment such as a corona treatment may be performed on the base film. The thickness of the metal layer is, for example, 0.01 to 3 μm, 0.1 to 3 μm, 0.1 to 2 μm, or 0.1 to μm. When the metal layer has a thickness within this range, the stability of the electrode assembly can be ensured while maintaining conductivity. The thickness of the metal piece is, for example, 2 to 10 μm, 2 to 7 μm, or 4 to 6 μm. When the metal piece has a thickness within this range, the connection between the metal layer and the lead tab can be more easily achieved. When the electrode current collector has such a structure, the weight of the electrode can be reduced, resulting in improved energy density. The electrode current collector can also be, for example, a positive electrode current collector. The electrode current collector can also be, for example, a negative electrode current collector.

[0106] The dry electrode film included in the dry electrode corresponds to the electrode active material layer.

[0107] In an electrode active material layer of a dry electrode (i.e., a dry electrode film), when measured by SAICAS (surface and interfacial measuring analysis system), the relative adhesive strength (F) in the vertical direction is measured from a first point 5% apart from the surface of the electrode active material layer in the direction of the electrode current collector to a second point 5% apart from the surface of the electrode current collector with respect to the entire thickness of the electrode active material layer. VR The rate of change in the vertical relative binding strength (Vertical Relative Force) is, for example, 300% or less. The rate of change in the vertical relative binding strength is, for example, 10 to 300%, 10 to 250%, 10 to 200%, 10 to 150%, or 10 to 100%. The second point 5% away from the surface of the electrode current collector in the direction of the electrode active material layer corresponds, for example, to a point 95% away from the surface of the electrode active material layer in the direction of the electrode current collector with respect to the entire thickness of the electrode active material layer. The vertical relative binding strength is calculated using the following Equation 1. For the SAICAS measurement method, see, for example, Evaluation Example 11.

[0108] <Number 1> Vertical relative adhesive force (F V , Vertical Relative Force) change rate = [(maximum value of vertical relative adhesive force (F VR2 )-Minimum value of vertical relative adhesive force (F VR1 ) / Minimum value of vertical relative adhesive force (F VR1 )] × 100 In the electrode active material layer of the dry electrode, the change rate of the relative binding strength in the vertical direction is 300% or less when measured by SAICAS (surface and interfacial measuring analysis system), which improves the uniformity of the distribution of components within the electrode. Furthermore, side reactions and increases in internal resistance due to uneven distribution of components within the electrode active material layer are suppressed, improving the flexibility of the electrode reaction. The cycle characteristics of lithium batteries can be improved even in the case of electrodes with high loading.

[0109] In the electrode active material layer of the dry electrode, when SAICAS is measured, the first horizontal direction binding strength (F) at a first point 10% apart from the surface of the electrode active material layer in the direction of the electrode current collector relative to the entire depth from the surface of the electrode active material layer to the surface of the electrode current collector is H1 , Horizontal Force) at a second point 10% apart from the surface of the electrode current collector in the direction of the electrode active material layer (e.g., in the depth direction). H2 The ratio of the horizontal adhesive force (Horizontal Force) to the total thickness of the electrode active material layer is, for example, 50% or more. The ratio of the horizontal adhesive force is, for example, 50 to 100%, 60 to 100%, 70 to 100%, 80 to 100%, or 90 to 100%. A second point 10% away from the surface of the electrode current collector in the direction of the electrode active material layer corresponds, for example, to a point 90% away from the surface of the electrode active material layer in the direction of the electrode current collector with respect to the total thickness of the electrode active material layer. The ratio of the horizontal adhesive force is expressed, for example, by the following Equation 2. For the SAICAS measurement method, see, for example, Evaluation Example 12.

[0110] <Number 2> Ratio of horizontal cohesion force = [Second horizontal cohesion force (F H2 ) / First horizontal adhesive force (F H1 )] × 100 During SAICAS measurement, the horizontal adhesive strength ratio was 50% or more, which further improved the uniformity of the distribution of components within the electrode. When a dry electrode has a horizontal adhesive strength in this range, the cycle characteristics of a lithium battery using such a dry electrode are further improved.

[0111] The dry electrode is, for example, a dry positive electrode, which includes a dry positive electrode film, and the dry positive electrode film includes the dry positive electrode active material having the above-mentioned core / shell structure.

[0112] The dry cathode active material having the core / shell structure described above includes a lithium transition metal oxide in the core, and a first metal oxide and a first carbon-based material in the shell.

[0113] The dry positive electrode active material may further include a conventional dry positive electrode active material in addition to the dry positive electrode active material having the core / shell structure described above. Any conventional dry positive electrode active material commonly used in the art may be used without limitation.

[0114] The dry cathode active material may be, for example, one or more composite oxides of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof. Specific examples include Li a A 1-b B b D2 (wherein 0.90≦a≦1 and 0≦b≦0.5), Li a E 1-b B' b O 2-c D c (wherein, 0.90≦a≦1, 0≦b≦0.5, 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, 0≦b≦0.5, 0≦c≦0.05, 0<α≦2), Li a Ni 1-b-c Co b B' c O 2-α F' α (wherein, 0.90≦a≦1, 0≦b≦0.5, 0≦c≦0.05, 0<α<2), Li a Ni 1-b-c Co b B' c O 2-α F' α (wherein, 0.90≦a≦1, 0≦b≦0.5, 0≦c≦0.05, 0<α<2), Li a Ni 1-b-c Mn b B' c D α(wherein, 0.90≦a≦1, 0≦b≦0.5, 0≦c≦0.05, 0<α≦2), Li a Ni 1-b-c Mn b B' c O 2-α F' α (wherein, 0.90≦a≦1, 0≦b≦0.5, 0≦c≦0.05, 0<α<2), Li a Ni 1-b-c Mn b B' c O 2-α F' α (wherein, 0.90≦a≦1, 0≦b ≦0.5, 0≦c≦0.05, 0<α<2), Li a Ni b E c G d O2 (wherein 0.90≦a≦1, 0≦b≦0.9, 0≦c≦0.5, 0.001≦d≦0.1), Li a Ni b Co c Mn d G e O2 (wherein 0.90≦a≦1, 0≦b≦0.9, 0≦c≦0.5, 0≦d ≦0.5, 0.001≦e≦0.1), Li a NiG b O2 (wherein 0.90≦a≦1, 0.001≦b≦0.1), Li a CoG b O2 (wherein 0.90≦a≦1, 0.001≦b≦0.1), Li a MnG b O2 (wherein 0.90≦a≦1, 0.001≦b≦0.1), Li a Mn2G b O4 (wherein 0.90≦a≦1, 0.001≦b≦0.1), QO2, QS2, LiQS2, V2O5, LiV2O5, LiI'O2, LiNiVO4, Li (3-f) J2(PO4)3(0≦f≦2), Li (3-f) A compound expressed by one of the chemical formulas Fe2(PO4)3(0≦f≦2) and LiFePO4 can be used.

[0115] In the chemical formula representing the above-mentioned compound, A is Ni, Co, Mn, or a combination thereof; B' is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I' is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0116] A compound having a coating layer added to the surface of the above-mentioned compound may also be used, or a mixture of the above-mentioned compound and a compound having a coating layer added thereto may also be used. The coating layer added to the surface of the above-mentioned compound may include, for example, a coating element compound such as an oxide, hydroxide, oxyhydroxide, oxycarbonate, or hydroxycarbonate of the coating element of the coating element. The compound forming such a coating layer may be amorphous or crystalline. The coating element contained in the coating layer may be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method for forming the coating layer may be selected within a range that does not adversely affect the physical properties of the positive electrode active material. Examples of the coating method include spray coating and dipping. Specific coating methods are well known to those skilled in the art, so a detailed description will be omitted.

[0117] The dry electrode is, 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 electrode active material.

[0118] The dry-type negative electrode active material can be any material that is used as the negative electrode active material of a lithium battery in the relevant technical field. For example, it includes one or more selected from the group consisting of lithium metal, metals alloyable with lithium, transition metal oxides, non-transition metal oxides, and carbon-based materials. Metals alloyable with lithium include, for example, Si, Sn, Al, Ge, Pb, Bi, Sb, Si-X alloys (where X is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or a combined element thereof, and is not Si), Sn-X alloys (where X is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or a combined element thereof, and is not Sn), and the like. Element Y includes, 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, Tl, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof. Transition metal oxides include, for example, lithium titanate oxide, vanadium oxide, lithium vanadium oxide, and the like. Non-transition metal oxides include, for example, SnO2, SiO x (0 < x < 2), and the like. Carbon-based materials include, for example, crystalline carbon, amorphous carbon, or a mixture thereof. Crystalline carbon is, for example, graphite such as amorphous, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite. Amorphous carbon includes, for example, soft carbon (low-temperature fired carbon) or hard carbon, mesophase pitch carbide, fired coke, and the like.

[0119] According to another embodiment, a lithium battery includes a first electrode, a second electrode, and an electrolyte disposed between the first electrode and the second electrode, and the first electrode, the second electrode, or a combination thereof is the dry-type electrode described above.

[0120] The lithium battery has dry electrodes with reduced internal resistance and improved mechanical properties, thereby improving the cycle characteristics of the lithium battery.

[0121] A lithium battery can include, for example, a dry positive electrode, a dry negative electrode, or a dry positive electrode and a dry negative electrode.A lithium battery can include, for example, a dry positive electrode and a wet negative electrode, or a wet positive electrode and a dry negative electrode.

[0122] Lithium batteries include an electrolyte, which may include, for example, a liquid electrolyte, a solid electrolyte, or a combination thereof.

[0123] The liquid electrolyte is, for example, an organic electrolyte solution, which is produced by dissolving a lithium salt in an organic solvent.

[0124] Any organic solvent known in the art can be used, such as 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.

[0125] Any lithium salt used in the art can be used. Examples of lithium salts include LiPF, LiBF, LiSbF, LiAsF, LiClO, LiCF, SO, Li(CF, SO)N, LiC, F, SO, LiAlO, LiAlCl, LiN(Cx F 2x+1 SO2)(C y F 2y+1 SO2) (where x and y are natural numbers), LiCl, LiI, or a mixture thereof.

[0126] The solid electrolyte may include, for example, an inorganic solid electrolyte, an organic solid electrolyte, an organic-inorganic composite solid electrolyte, or a combination thereof.

[0127] The solid electrolyte may include, for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a polymer-based solid electrolyte, or a combination thereof.

[0128] The solid electrolyte may be, but is not limited to, boron oxide, lithium oxynitride, etc. Any solid electrolyte known in the art may be used. The solid electrolyte may be formed on the negative electrode by, for example, sputtering, or a separate solid electrolyte sheet may be laminated on the negative electrode.

[0129] The oxide-based solid electrolyte is, 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 combinations thereof, 0 ≦ x ≦ 10, 0 < y < 2), Li7La3Zr 2-x Ta x O 12 (0 < x < 2, LLZ - Ta), or combinations thereof. The oxide - based solid electrolyte is, for example, a garnet - type solid electrolyte. The oxide - based solid electrolyte is produced by a sintering method or the like. <000—791><000—792><000—793>The oxide - based solid electrolyte is, for example, Li7La3Zr2O 12 (LLZO), Li 6.5 La3Zr 1.5 [[ID=4l]]Ta 0.5 O 12 , Li<—000177>Al 0.3 Ti<—000179>(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 combinations thereof.

[0131] Examples of sulfide-based solid electrolytes include 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, and Li2S-P2S5-Z m S n , m and n are positive numbers, Z is one of Ge, Zn or Ga, Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q , p, q are positive numbers, M is one of P, Si, Ge, B, Al, GaIn, Li 7-x PS 6-x Cl x , 0(x(2, Li 7-x PS 6-x Br x , 0(x(2, and Li 7-x PS 6-x I x , 0(x(2). The sulfide-based solid electrolyte is prepared by processing starting materials such as LiS and P2S5 by a melt quenching method or a mechanical milling method. After such processing, a heat treatment may be performed. The sulfide-based solid electrolyte may be amorphous, crystalline, or a mixture thereof.

[0132] The sulfide-based solid electrolyte may include, for example, an argyrodite-type solid electrolyte represented by the following Chemical Formula 9.

[0133] <9> Li + 12-n-x A n+ X 2- 6-x Y - x In the formula, A is P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta; X is S, Se, or Te; Y is Cl, Br, I, F, CN, OCN, SCN, or N; and 1(n)(5, 0(x)(2).

[0134] Sulfide-based solid electrolytes are 7-x PS 6-x Cl x , 0≦x≦2, Li 7-x PS 6-x Br x , 0≦x≦2, and Li 7-x PS 6-x I x , and 0≦x≦2. In particular, the sulfide-based solid electrolyte contained in the solid electrolyte is an argyrodite-type compound containing one or more selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0135] The polymer-based solid electrolyte may be, for example, a solid electrolyte containing an ion-conductive polymer and a lithium salt, a solid electrolyte containing an ionic liquid polymer and a lithium salt, or a combination thereof.

[0136] An ion-conducting polymer is a polymer containing an ion-conducting repeating unit in the main chain or side chain. The ion-conducting repeating unit is a unit having ion conductivity, such as an alkylene oxide unit or a hydrophilic unit. The ion-conducting polymer may contain, for example, an ether-based monomer, an acrylic monomer, a methacrylic monomer, a siloxane-based monomer, or a combination thereof as the ion-conducting repeating unit. Examples of the ion-conducting polymer include 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-conducting polymer may be, for example, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinylsulfone, or a combination thereof.

[0137] Ionic liquid polymers (PILs) include, for example, i) one or more cations selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazole, and mixtures thereof; and ii) BF4-, PF6-, AsF6-, SbF6-, AlCl4-, HSO4-, ClO4-, CH3SO3-, CF3CO2-, (CF3SO2)2N-, Cl-, Br-, I-, BF4-, SO4 - , PF6-, ClO4-, CF3SO3-, CF3CO2-, (C2F5SO2)2N-, (C2F5SO2)(CF3SO2)N-, NO3 - , Al2Cl7 - , 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 - , (O(CF3)2C2(CF3)2O)2PO - and (CF3SO2)2N-. The ionic liquid polymer may include, for example, poly(diallyldimethylammonium)TFSI), poly(1-allyl-3-methylimidazolium trifluoromethanesulfonyl imide), poly((N-Methyl-N-propylpiperidinium bis(trifluoromethanesulfonyl)imide), or a combination thereof.

[0138] Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, and LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (1≦x≦20, 1≦y≦20), LiCl, LiI or a combination thereof.

[0139] According to another embodiment, a method for manufacturing a dry electrode is provided.

[0140] The method for manufacturing a dry electrode includes providing a dry electrode film and disposing the dry electrode film on one or both sides of an electrode current collector.

[0141] The step of providing the dry electrode film includes the steps of dry-mixing a dry electrode active material, a dry conductive material, and a dry binder to prepare a dry mixture, and forming the dry mixture to prepare the dry electrode film.

[0142] First, an electrode active material, a dry conductive material, and a dry binder are dry-mixed to prepare a dry mixture. For example, a dry mixture is prepared by dry-mixing a dry electrode active material, a dry conductive material, and a dry binder.

[0143] Dry mixing refers to mixing without a process solvent. The process solvent is, for example, a solvent used in preparing an electrode slurry. The process solvent is, for example, water, NMP, etc., but is not limited thereto, as long as it is a process solvent used in preparing an electrode slurry. Dry mixing may be performed using a stirrer, for example, at a temperature of 15°C to 65°C and a rotation speed of 10 to 10,000 rpm. Dry mixing may be performed using a stirrer, for example, for 1 to 200 minutes.

[0144] Dry mixing may be performed, for example, one or more times. First, a dry electrode active material, a dry conductive material, and a dry binder may be dry-mixed to prepare a first dry mixture. The first dry mixing may be performed, for example, at a temperature of 25 to 65°C and a rotation speed of 10 to 2000 rpm for 15 minutes or less. Then, the first dry mixture may be dry-mixed a second time to prepare a second mixture. The second dry mixing may be performed, for example, at a temperature of 25 to 65°C and a rotation speed of 3000 to 9000 rpm for 10 to 60 minutes. A dry mixture containing a fibrillated dry binder is obtained by the second dry mixing.

[0145] The agitator may be, for example, a kneader. The agitator may include, for example, a chamber, one or more rotating shafts disposed within the chamber and rotating, and blades rotatably coupled to the rotating shafts and arranged in the longitudinal direction of the rotating shafts. The blades may be, for example, one or more selected from a ribbon blade, a sigma blade, a Z blade, a dispersion blade, and a screw blade. The inclusion of the blades allows the electrode active material, the dry conductive material, and the dry binder to be effectively mixed without a solvent to produce a dough-like mixture.

[0146] Examples of the dry binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene (PTFE), a mixture of the above polymers, a styrene-butadiene rubber-based polymer, etc. The dry binder may be selected from the dry binders used in the dry electrode film described above.

[0147] Examples of the dry conductive material include, but are not limited to, carbon black, graphite particles, natural graphite, artificial graphite, acetylene black, ketjen black, carbon fiber, carbon nanotube, metal powder, metal fiber, or metal tube, such as copper, nickel, aluminum, or silver, and conductive polymers such as polyphenylene derivatives. Any material known in the art for use as a conductive material can be used. The conductive material is, for example, a carbon-based conductive material. The dry conductive material can be selected from the dry conductive materials used in the dry electrode film described above.

[0148] A plasticizer or pore former may also be added to the dry mixture to form pores within the electrode plate.

[0149] The contents of the dry electrode active material, dry binder, and dry conductive material used in the dry electrode film are at the levels commonly used in lithium batteries.

[0150] The dry positive electrode film uses a dry positive electrode active material as the dry electrode active material. The dry positive electrode active material is similar to the dry electrode film described above. The dry negative electrode film uses a dry negative electrode active material as the dry electrode active material. The dry negative electrode active material is similar to the dry electrode film described above.

[0151] The dry mixture is then molded to prepare a dry electrode film.

[0152] The prepared dry mixture can be fed into an extrusion device and extruded into a sheet or film form under a pressure of, for example, 4 MPa to 100 MPa.

[0153] An electrode current collector is then provided having an intermediate layer disposed on one or both sides of the substrate.

[0154] Providing an electrode current collector having an intermediate layer disposed on one or both surfaces of a substrate includes, for example, providing a substrate and disposing an intermediate layer on the one or both surfaces.

[0155] The substrate of the electrode current collector is the same as that of the electrode current collector described above. The substrate of the positive electrode current collector is, for example, aluminum foil. The substrate of the negative electrode current collector is, for example, copper foil.

[0156] The step of disposing an intermediate layer on one or both surfaces of the substrate may include dry coating and / or wet coating. Dry coating involves, for example, coating one or both surfaces of an electrode current collector with a carbon-based conductive material and / or its precursor by vapor deposition. Vapor deposition is performed at room temperature to a high temperature and under atmospheric pressure or vacuum. The intermediate layer disposed by dry coating is made of a carbon-based material and does not include a binder. Wet coating involves, for example, coating one or both surfaces of an electrode current collector with a composition including a carbon-based conductive material and a binder. The composition includes, for example, a carbon-based conductive material, a binder, and a process solvent. For details about the carbon-based conductive material and the binder, see the electrode section above. The process solvent may be selected from solvents used in preparing an electrode slurry. After the composition is coated on the electrode current collector, the process solvent is removed by drying. Coating methods include, but are not limited to, spin coating and dip coating, and any coating method commonly used in the art may be used.

[0157] Then, the dry electrode films are simultaneously or sequentially disposed on one or both sides of an electrode current collector to prepare a dry electrode.

[0158] A rolling step may be added during and / or after disposing the dry electrode film on one or both sides of the electrode current collector.

[0159] The rolling may be performed by, for example, a roll press or a plate press, but is not limited thereto. The pressure during rolling is, for example, 1.0 to 10.0 ton / cm. If the pressure during rolling is excessively high, cracks may occur in the electrode current collector. If the pressure during rolling is excessively low, the bonding strength between the electrode current collector and the dry electrode film decreases.

[0160] The lithium battery is manufactured, for example, by the following exemplary method, but is not necessarily limited to such a method and may vary depending on required conditions.

[0161] First, one or both of the positive electrode and the negative electrode may be manufactured using the dry electrode manufacturing method described above. Alternatively, if one of the positive electrode and the negative electrode is manufactured using the above-described electrode manufacturing method, the other electrode may be manufactured using a wet manufacturing method. For example, the other electrode may be manufactured by preparing an electrode slurry containing an electrode active material, a conductive material, a binder, and a solvent, coating the electrode slurry on an electrode current collector, and drying the coated electrode slurry. The conductive material and binder contained in the electrode manufactured using the wet method may be selected from the conductive materials and binders used in the manufacture of the dry electrodes described above.

[0162] Next, a separator to be inserted between the positive electrode and the negative electrode is prepared.

[0163] Any separator commonly used in lithium batteries can be used. For example, a separator that has low resistance to ion migration of the electrolyte and excellent electrolyte humidification ability is used. The separator is made of, for example, glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, and is in the form of a nonwoven or woven fabric. For lithium ion batteries, rollable separators such as polyethylene and polypropylene are used, while for lithium ion polymer batteries, separators with excellent organic electrolyte humidification ability are used.

[0164] The separator is manufactured by the following exemplary method, but is not necessarily limited to such a method and may be adjusted according to the required conditions.

[0165] First, a separator composition is prepared by mixing a polymer resin, a filler, and a solvent. The separator composition is directly coated on the electrode and dried to form a separator. Alternatively, the separator composition is cast on a support and dried, and the separator film is peeled off from the support and laminated on the electrode to form a separator.

[0166] The polymer used to manufacture the separator is not particularly limited, and any polymer used as a binder for electrode plates can be used, such as vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or a mixture thereof.

[0167] The electrolyte is then prepared, which refers to the lithium battery section above.

[0168] As shown in FIG. 9, 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 are wound or folded to form a battery structure 7. The formed battery structure 7 is housed in a battery case 5. An organic electrolyte solution is poured into the battery case 5, which is then sealed with a cap assembly 6 to complete the lithium battery 1. The battery case 5 is cylindrical, but is not necessarily limited to such a shape and may be, for example, rectangular or thin-film.

[0169] As shown in FIG. 10 , a lithium battery 1 includes a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 is disposed between the positive electrode 3 and the negative electrode 2, and the positive electrode 3, the negative electrode 2, and the separator 4 are wound or folded to form a battery structure 7. The formed battery structure 7 is housed in a battery case 5. It may include electrode tabs 8 that serve as electrical paths for conducting current generated in the battery structure 7 to the outside. An organic electrolyte solution is injected into the battery case 5 and sealed to complete the lithium battery 1. The battery case 5 is rectangular, but is not necessarily limited to such a shape and may be cylindrical, thin-film, or the like.

[0170] As shown in FIG. 11, the lithium battery 1 includes a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 is disposed between the positive electrode 3 and the negative electrode 2 to form a battery structure. The battery structure 7 is stacked in a bi-cell structure and then housed in a battery case 5. The battery structure 7 may include electrode tabs 8 that serve as electrical paths for conducting current generated in the battery structure 7 to the outside. An organic electrolyte solution is injected into the battery case 5 and sealed to complete the lithium battery 1. The battery case 5 is rectangular, but is not necessarily limited to such a shape and may be cylindrical, thin-film, or the like.

[0171] The pouch-type lithium battery corresponds to the lithium batteries of FIGS. 9 to 11, respectively, in which a pouch is used as the battery case. A pouch-type lithium battery includes one or more battery structures. A separator is disposed between a positive electrode and a negative electrode to form a battery structure. The battery structures are stacked in a bi-cell structure, impregnated with an organic electrolyte solution, and then housed in a pouch and sealed to complete the pouch-type lithium battery. For example, although not shown in the drawings, the above-mentioned positive electrode, negative electrode, and separator may be simply stacked and housed in a pouch in the form of an electrode assembly, or may be wound into a jellyroll-type electrode assembly or folded and housed in a pouch. The pouch is then filled with an organic electrolyte solution and sealed to complete the lithium battery.

[0172] Lithium batteries have excellent life and high-rate characteristics and are therefore used in, for example, electric vehicles (EVs), hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs), and fields requiring large amounts of stored power, such as electric bicycles and power tools.

[0173] Lithium batteries are stacked in multiple numbers to form a battery module, and multiple battery modules form a battery pack. Such a battery pack can be used in all devices that require high capacity and high output. For example, it can be used in notebook computers, smartphones, electric vehicles, etc. A battery module includes, for example, a plurality of batteries and a frame that holds them. A battery pack includes, for example, a plurality of battery modules and a bus bar that connects them. The battery module and / or the battery pack may further include a cooling device. Multiple battery packs are regulated by a battery management system. The battery management system includes a battery pack and a battery control device connected to the battery pack.

[0174] According to still another embodiment, a method for manufacturing a dry electrode active material includes providing a core, providing a composite, and mechanically milling the core and the composite to manufacture a dry electrode active material. The composite includes one or more first metal oxides and a first carbon-based material. The first metal oxide is disposed within a first carbon-based material matrix, and the first metal oxide is represented by the chemical formula M a O b (0 < a ≤ 3, 0 < b < 4; if a is 1, 2, or 3, b is not an integer), and M is one or more metals selected from Groups 2 to 16 of the periodic table.

[0175] As the core, for example, a lithium transition metal oxide is provided. The lithium transition metal oxide is, for example, a compound represented by Chemical Formulas 1 to 8 described above.

[0176] A composite is provided. The step of providing the composite includes, for example, supplying a reaction gas composed of a carbon source gas to a structure containing a metal oxide and performing heat treatment to provide the composite. The step of providing the composite includes, for example, M a O cSupplying a reaction gas composed of a carbon source gas to one or more second metal oxides represented by (0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3, b is an integer), and performing heat treatment to produce a composite, wherein M is one or more metals selected from Groups 2 to 13, 15, and 16 of the periodic table.

[0177] The carbon source gas is a gas composed of a compound represented by the following Chemical Formula 10, or one or more mixed gases selected from the group consisting of a compound represented by the following Chemical Formula 10, a compound represented by the following Chemical Formula 11, and an oxygen-containing gas represented by the following Chemical Formula 12.

[0178] <Chemical Formula 10> C n H (2n+2-a) [OH] a In the Chemical Formula 10, n is 1 to 20, and a is 0 or 1. <Chemical Formula 11><000094I3>C n H 2n In the Chemical Formula 11, n is 2 to 6. <Chemical Formula 12> C x H|D=33]] y O z In the Chemical Formula 12, x is 0 or an integer of 1 to 20, y is 0 or an integer of 1 to 20, and z is 1 or 2. <00E0948>

[0179] The compound represented by Chemical Formula 10 and the compound represented by Chemical Formula 11 are one or more selected from the group consisting of methane, ethylene, propylene, methanol, ethanol, and propanol. The oxygen-containing gas represented by Chemical Formula 12 includes, for example, carbon dioxide (CO2), carbon monoxide (CO), water vapor (H2O), or a mixture thereof.

[0180] M a O<00E0258>(0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, then c is an integer), after supplying a reaction gas composed of a carbon source gas to the second metal oxide and performing heat treatment, a cooling step using one or more inert gases selected from the group consisting of nitrogen, helium, and argon is further carried out. The cooling step refers to the step of adjusting to room temperature (20 - 25°C). The carbon source gas may contain one or more inert gases selected from the group consisting of nitrogen, helium, and argon.)

[0181] In the method for producing a composite, the process of growing a carbon-based material, such as graphene, by a gas-phase reaction can be carried out under various conditions.)

[0182] According to the first condition, for example, M a O c (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, then c is an integer), first supply methane to the reactor in which the second metal oxide is disposed, and perform a temperature-raising treatment to the heat treatment temperature (T). The temperature-raising time to the heat treatment temperature (T) is 10 minutes to 4 hours, and the heat treatment temperature (T) is in the range of 700°C to 1100°C. Perform heat treatment for about the reaction time at the heat treatment temperature (T). The reaction time is, for example, 4 hours to 8 hours. Cool the heat-treated product to room temperature to produce a composite. The time taken during the process of cooling from the heat treatment temperature (T) to room temperature is, for example, 1 hour to 5 hours.)

[0183] According to the second condition, for example, M a O c (0 < a ≤ 3, 0 < c ≤ 4, and if a is 1, 2, or 3, then c is an integer), first supply hydrogen to the reactor in which the second metal oxide is disposed, and perform a temperature-raising treatment to the heat treatment temperature (T). The temperature-raising time to the heat treatment temperature (T) is 10 minutes to 4 hours, and the heat treatment temperature (T) is in the range of 700°C to 1100°C. After performing heat treatment for a certain reaction time at the heat treatment temperature (T), supply methane gas and perform heat treatment for the remaining reaction time. The reaction time is, for example, 4 hours to 8 hours. Cool the heat-treated product to room temperature to produce a composite. Supply nitrogen during the cooling process. The time taken during the process of cooling from the heat treatment temperature (T) to room temperature is, for example, 1 hour to 5 hours.)

[0184] According to the third condition, for example, M a O c (0 < a ≤ 3, 0 < c ≤ 4, if a is 1, 2, or 3, c is an integer), hydrogen is first supplied to the reactor in which the second metal oxide is disposed and heated to the heat treatment temperature (T). The heating time to the heat treatment temperature (T) is 10 minutes to 4 hours, and the heat treatment temperature (T) is in the range of 700°C to 1100°C. After heat treatment for a certain reaction time at the heat treatment temperature (T), a mixed gas of methane and hydrogen is supplied and heat treatment is performed for the remaining reaction time. The reaction time is, for example, 4 hours to 8 hours. The heat-treated product is cooled to room temperature to produce a composite. Nitrogen is supplied during the cooling process. The time from the heat treatment temperature (T) to room temperature during the cooling process is, for example, 1 hour to 5 hours.

[0185] In the process of producing the composite, when the carbon source gas contains water vapor, a composite having very excellent conductivity can be obtained. The content of water vapor in the gas mixture is not limited, and is, for example, 0.01% by volume to 10% by volume based on 100% by volume of the total carbon source gas. The carbon source gas is, for example, methane, a mixed gas containing methane and an inert gas, or a mixed gas containing methane and an oxygen-containing gas.

[0186] The carbon source gas is also, for example, 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 is about 1:0.20 to 1:0.50, about 1:0.25 to 1:0.45, or about 1:0.30 to 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 is about 1:0.20 to 0.50:0.01 to 1.45, about 1:0.25 to 0.45:0.10 to 1.35, or about 1:0.30 to 0.40:0.50 to 1.0.

[0187] The carbon source gas is, for example, carbon monoxide or carbon dioxide. The carbon source gas is, for example, a mixed gas of methane and nitrogen. In the mixed gas of methane and nitrogen, the molar ratio of methane to nitrogen is about 1:0.20 to 1:0.50, about 1:0.25 to 1:0.45, or about 1:0.30 to 1:0.40. The carbon source gas does not contain an inert gas such as nitrogen.

[0188] The heat treatment pressure can be selected in consideration of the heat treatment temperature, the composition of the gas mixture, the desired amount of carbon coating, etc. The heat treatment pressure can be controlled by adjusting the amount of the inflowing gas mixture and the amount of the outflowing gas mixture. The heat treatment pressure is, for example, 0.5 atm or more, 1 atm or more, 2 atm or more, 3 atm or more, 4 atm or more, or 5 atm or more. The heat treatment pressure is, for example, 0.5 atm to 10 atm, 1 atm to 10 atm, 2 atm to 10 atm, 3 atm to 10 atm, 4 atm to 10 atm, or 5 atm to 10 atm.

[0189] The heat treatment time is not particularly limited and can be appropriately adjusted according to the heat treatment temperature, the pressure during heat treatment, the composition of the gas mixture, and the desired amount of carbon coating. For example, the reaction time at the heat treatment temperature is, for example, 10 minutes to 100 hours, 30 minutes to 9 hours, or 50 minutes to 40 hours. For example, as the heat treatment time increases, the amount of carbon deposited, for example, the amount of graphene (carbon), increases, whereby the electrical physical properties of the composite can be improved. However, such a tendency is not necessarily directly proportional to time. For example, after a predetermined time has elapsed, no further carbon deposition, for example, graphene deposition, occurs or the deposition rate becomes low.

[0190] Even at a relatively low temperature through the gas-phase reaction of the above-described carbon source gas, M a O c (0 < a ≤ 3, 0 < c ≤ 4, if a is 1, 2, or 3, then c is an integer) and the reduced product thereof, M a O b(0 < a ≤ 3, 0 < b < 4, a is 1, 2, or 3, and b is not an integer) By providing a coating of a carbon-based material that is uniform over one or more selected from the first metal oxides represented thereby, for example, a graphene coating, a composite is obtained.

[0191] The composite has, for example, a matrix of a carbon-based material having one or more structures selected from a spherical structure, a spiral structure in which a plurality of spherical structures are connected, a cluster structure in which a plurality of spherical structures are aggregated, and a sponge structure, for example, a graphene matrix and M arranged within the graphene matrix a O b (0 < a ≤ 3, 0 < b < 4, a is 1, 2, or 3, and b is not an integer) the first metal oxide represented thereby and M a O c includes one or more selected from the second metal oxides represented by (0 < a ≤ 3, 0 < c ≤ 4, if a is 1, 2, or 3, then c is an integer).

[0192] Next, the lithium transition metal oxide and the composite are mechanically milled to produce a dry electrode active material. A noble mixer or the like can be used during milling. The rotation speed of the mixer during milling is, for example, 1000 rpm to 5000 rpm. The milling time is, for example, 5 minutes to 100 minutes. The average particle size (D50) of the composite used for the mechanical milling of the lithium transition metal oxide and the composite is, for example, 50 nm to 200 nm, 100 nm to 300 nm, or 200 nm to 500 nm. At the stage of mechanically milling, the milling method is not particularly limited, and any method that can be used in the art as a method of bringing the lithium transition metal oxide and the composite into contact using a machine can be used.

[0193] The present invention will be described in more detail through the following examples and comparative examples. However, the examples are for illustrative purposes only and do not limit the scope of the present invention solely thereby.

[0194] (Production of composite) Production Example 1: Al2O3@Gr composite After placing Al2O3 particles (average particle size: about 15 nm) in the reactor, the internal temperature of the reactor was raised to 1000 °C under the condition that CH4 was supplied at about 300 sccm and 1 atm for about 30 minutes in the reactor.

[0195] Next, heat treatment was performed by holding at the said temperature for 7 hours. Subsequently, the internal temperature of the reactor was adjusted to room temperature (20 - 25 °C) to obtain a composite in which Al2O3 particles and Al2O z (0 < z < 3) particles were embedded in graphene.

[0196] The alumina content contained in the composite was 60 wt%.

[0197] Production Example 2: SiO2@Gr composite After placing SiO2 particles (average particle size: about 15 nm) in the reactor, the internal temperature of the reactor was raised to 1000 °C under the condition that CH4 was supplied at about 300 sccm and 1 atm for about 30 minutes in the reactor.

[0198] Next, heat treatment was performed by holding at the said temperature for 7 hours. Subsequently, the internal temperature of the reactor was adjusted to room temperature (20 - 25 °C) to obtain a composite in which SiO2 particles and SiO y (0 < y < 2) particles were embedded in graphene.

[0199] (Production of composite positive electrode active material) Example 1: Al2O3@Gr composite 0.4 wt% (alumina 0.24 wt%) - coated large - diameter NCA91 LiNi with an average particle size (D50) of 14 μm 0.91 Co 0.05 Al 0.04O2 (hereinafter referred to as NCA91) and the composite prepared in Preparation Example 1 were milled in a Nobilta Mixer (Hosokawa, Japan) at a rotation speed of approximately 1000 to 2000 rpm for approximately 5 to 30 minutes to obtain a composite cathode active material. The mixing weight ratio of NCA91 to the composite prepared in Preparation Example 1 was 99.6:0.4.

[0200] Example 2: Al2O3@Gr composite 0.4 wt% (alumina 0.24 wt%) coated small diameter NCA91 LiNi with an average particle size (D50) of 3.5 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91) and the composite prepared in Preparation Example 1 were milled in a Nobilta Mixer (Hosokawa, Japan) at a rotation speed of approximately 1000 to 2000 rpm for approximately 5 to 30 minutes to obtain a composite cathode active material. The mixing weight ratio of NCA91 to the composite prepared in Preparation Example 1 was 99.6:0.4.

[0201] Example 3: Large diameter NCA91 coated with 0.2 wt% Al2O3@Gr composite (0.12 wt% alumina) and 0.05 wt% CNT LiNi with an average particle size (D50) of 14 μm 0.91 Co 0.05 Al 0.04 A composite cathode active material was prepared by milling O2 (hereinafter referred to as NCA91), the composite prepared in Preparation Example 1, and carbon nanotubes (hereinafter referred to as CNTs) using a Nobilta Mixer (Hosokawa, Japan) at a rotation speed of approximately 1000-2000 rpm for approximately 5-30 minutes. NCA91, the composite, and CNTs were mixed in a ratio of 97.5:0.2:0.05 to prepare the composite cathode active material.

[0202] The carbon nanotube includes a carbon nanotube primary structure and a carbon nanotube secondary structure formed by aggregating a plurality of carbon nanotube units.

[0203] The carbon nanotube primary structure consisted of one carbon nanotube unit, the length of which was 200 nm to 300 nm, and the diameter of the carbon nanotube was approximately 10 nm.

[0204] The carbon nanotube secondary structure was formed by aggregating multiple carbon nanotube units. The length of the carbon nanotube secondary structure was 500 nm or more, and the diameter was about 40 nm.

[0205] Comparative Example 1: Large diameter bare NCA91 LiNi with an average particle size (D50) of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91) was used as a composite positive electrode active material.

[0206] Comparative Example 2: NCA91 coated with 0.4 wt% SiO2@Gr composite A composite positive electrode active material was prepared in the same manner as in Preparation Example 1, except that the SiO@Gr composite prepared in Preparation Example 2 was used instead of the AlO@Gr composite prepared in Preparation Example 1.

[0207] (Lithium battery (half cell) manufacturing) Example 4: Dry positive electrode, core / shell composite positive electrode active material (Manufacturing dry cathode films and dry cathodes) The dry composite positive electrode active material prepared in Preparation Example 1, a dry carbon conductive material, and polytetrafluoroethylene (PTFE) as a dry binder were added to a blade mixer in a weight ratio of 96:2:2, and then primary dry mixing was performed at 25°C and 1200 rpm for 10 minutes to prepare a first dry mixture in which the dry positive electrode active material, dry conductive material, and dry binder were uniformly mixed. The dry carbon conductive material was a mixture of carbon nanotubes (CNTs) and Ketjenblack (ECP) in a weight ratio of 7:3.

[0208] Next, the first dry mixture was further mixed at 25° C. in a blade mixer at a speed of 4000 rpm for 25 minutes to allow the binder to be fiberized, thereby preparing a second dry mixture.

[0209] No separate solvent is used in the preparation of the first dry mixture and the second dry mixture.

[0210] The prepared second dry mixture was put into an extruder and extruded to prepare a sheet-shaped dry cathode film self-standing film. The extrusion pressure was 60 MPa.

[0211] The prepared dry-type positive electrode film free-standing membrane was rolled to prepare a rolled dry-type electrode film free-standing membrane. The pressure during rolling was 3.5 ton / cm. 2 The thickness of the dry positive electrode film was about 200 μm.

[0212] A positive electrode current collector was prepared in which a carbon layer was coated on one side of a 25 μm thick aluminum thin film.

[0213] The carbon layer was prepared by coating a composition containing a carbon conductive material (Danka Black) and polyvinylidene fluoride (PVDF) on the positive electrode current collector and then drying it. The thickness of the carbon layer disposed on one side of the positive electrode current collector was approximately 1 μm.

[0214] A rolled dry positive electrode film was placed on one surface of a positive electrode current collector to prepare a dry positive electrode.

[0215] (Coin cell manufacturing) A coin cell was fabricated using the cathode prepared above, lithium metal as a counter electrode, a PTFE separator, and a solution of 1.3M LiPF6 dissolved in EC (ethylene carbonate) + EMC (ethyl methyl carbonate) + DMC (dimethyl carbonate) (3:4:3 volume ratio) as an electrolyte.

[0216] Example 5: Bimodal dry cathode active material A dry electrode film, a dry positive electrode, and a coin cell were prepared in the same manner as in Example 4, except that a 7:3 weight ratio mixture of the dry composite positive electrode active material prepared in Example 1 (large diameter dry composite positive electrode active material) and the dry composite positive electrode active material prepared in Example 2 (small diameter dry composite positive electrode active material) was used instead of the dry composite positive electrode active material prepared in Example 1.

[0217] Example 6: CNT-added composite positive electrode active material A dry electrode film, a dry positive electrode, and a coin cell were prepared in the same manner as in Example 4, except that the dry composite positive electrode active material prepared in Example 3 was used instead of the dry composite positive electrode active material prepared in Example 1.

[0218] Comparative example 3: Dry positive electrode, bare NCA91 positive electrode active material Instead of the dry composite positive electrode active material prepared in Example 1, LiNi 0.91 Co 0.05 Al 0.04 A dry positive electrode film, a dry positive electrode, and a coin cell were manufactured in the same manner as in Example 4, except that O2 (hereinafter referred to as NCA91) was used as is.

[0219] Comparative Example 4: Wet cathode, bare NCA91 cathode active material (Cathode manufacturing) LiNi with an average particle size (D50) of 14 μm 0.91 Co 0.05 Al 0.04 A mixture of O2 (hereafter referred to as NCA91), a carbon conductive material, and polyvinylidene fluoride (PVDF) in a weight ratio of 96:2:2 was mixed with N-methylpyrrolidone (NMP) in an agate mortar to prepare a cathode active material slurry. The dry carbon conductive material was a mixture of carbon nanotubes (CNTs) and Ketjenblack (ECP) in a weight ratio of 7:3.

[0220] The positive electrode active material slurry was bar coated on one surface of a prepared positive electrode current collector having a thickness of 30 μm, dried at room temperature, and then dried again under vacuum at 120° C. to prepare a laminate.

[0221] The prepared laminate was rolled to produce a positive electrode in which a positive electrode active material layer was disposed on a positive electrode current collector. The pressure during rolling was 3.5 ton / cm. 2 The thickness of the positive electrode active material layer was about 200 μm.

[0222] (Coin cell manufacturing) A coin cell was fabricated in the same manner as in Example 4, except that the prepared positive electrode was used.

[0223] Comparative Example 5: Dry positive electrode, SiO2@Gr coated composite positive electrode active material A dry positive electrode film, a dry positive electrode, and a coin cell were prepared in the same manner as in Example 4, except that the dry composite positive electrode active material prepared in Comparative Example 2 was used instead of the dry composite positive electrode active material prepared in Example 1.

[0224] Evaluation example 1: XPS spectrum evaluation XPS spectra were measured over time using a Qunatum 2000 (Physical Electronics) during the production process of the composite produced in Production Example 1. XPS spectra of the C 1s orbital and Al 2p orbital were measured for the sample before heating, and after 1 minute, 5 minutes, 30 minutes, 1 hour, and 4 hours. At the beginning of the temperature rise, only a peak corresponding to the Al 2p orbital was observed, and no peak corresponding to the C 1s orbital was observed. After 30 minutes, a clear peak corresponding to the C 1s orbital was observed, and the magnitude of the peak corresponding to the Al 2p orbital significantly decreased.

[0225] After 30 minutes, a clear peak for the C 1s orbital due to the C═C bond and C═C bond due to graphene growth was observed near 284.5 eV.

[0226] As the reaction time increased, the oxidation number of aluminum decreased, and the peak position of the Al 2p orbital shifted to a lower binding energy (eV).

[0227] Therefore, as the reaction proceeds, graphene grows on the Al2O3 particles, and Al2O, which is the reduction product of Al2O3 x (0 < x < 3) was confirmed to be generated.

[0228] The average contents of carbon and aluminum were measured through XPS analysis of 10 regions of the composite sample produced in Production Example 1. The deviation of the aluminum content for each region was calculated with respect to the measurement results. The deviation of the aluminum content was shown as a percentage with respect to the average value, and this was referred to as the uniformity. The percentage with respect to the average value of the deviation of the aluminum content, that is, the uniformity of the aluminum content, was 1%. Therefore, it was confirmed that alumina was uniformly distributed within the composite produced in Production Example 1.

[0229] Evaluation Example 2: SEM, HR-TEM and SEM-EDS Analyses Scanning electron microscopy, high-resolution transmission electron microscopy and EDS (Energy-dispersive X-ray spectroscopy) analyses were performed on the composite produced in Production Example 1, the composite positive electrode active material produced in Example 1, and the bare NCA91 prepared in Comparative Example 1.

[0230] FEI Titan 80-300 from Philips was used during the SEM-EDS analysis. Figure 3 is a scanning electron microscope image of the bare NCA91 prepared in Comparative Example 1. Figure 4 is a scanning electron microscope image of the composite positive electrode active material produced in Example 1.

[0231] The composite produced in Production Example 1 was shown to have a structure in which Al2O3 particles and Al2O z (0 < z < 3) particles are embedded in graphene. It was confirmed that a graphene layer is arranged on the outer contour of one or more particles selected from among the Al2O3 particles and Al2O z (0 < z < 3).z One or more particles selected from (0 < z < 3) were uniformly dispersed in the graphene matrix. Al2O3 particles and Al2O z One or more particle sizes of (0 < z < 3) particles were about 20 nm. The particle size of the composite produced in Production Example 1 was about 50 nm to 200 nm.

[0232] Referring to FIG. 3, it was confirmed that the large-diameter NCA91 in the bare NCA91 prepared in Comparative Example 1 was a secondary particle in which a plurality of primary particles were aggregated, and there was no coating layer on the surface.

[0233] Referring to FIG. 4, it was confirmed that a shell formed by a composite containing graphene was disposed on the large-diameter NCA91 core in the composite positive electrode active material produced in Example 1.

[0234] In the SEM-EDS mapping analysis of the bare large-diameter NCA91 of Comparative Example 1 and the first core / shell structure produced in Example 1, it was confirmed that the concentration of aluminum (Al) distributed on the surface of the first core / shell structure of Example 1 increased compared to the surface of the bare NCA91 of Comparative Example 1. It was confirmed that the composite produced in Production Example 1 was coated on the large-diameter NCA91 core in the first core / shell structure of Example 1 to form a shell.

[0235] Evaluation Example 3: XPS Spectrum Evaluation (Graphene-NCA Chemical Bond) For the composite produced in Production Example 1, the bare large-diameter NCA91 of Comparative Example 1, and the composite positive electrode active material produced in Example 1, the XPS spectrum for the O1s orbital was measured using Quantum 2000 (Physical Electronics), and the results are shown in FIG. 5.

[0236] As shown in Figure 5, a peak due to a CO-Ni bond was observed near 530.2 eV for the composite cathode active material of Example 1. This peak was determined to be due to the bond formed between the NiO phase present on the NCA91 surface and the carbon of the graphene. Therefore, it was confirmed that the graphene contained in the shell formed on the core forms a covalent bond with Ni, a transition metal contained in the core.

[0237] Evaluation example 4: Raman spectrum evaluation (graphene-NCA chemical bond) The Raman spectra of the composite prepared in Preparation Example 1 and the composite positive electrode active material prepared in Example 1 were measured, and the results are shown in FIG.

[0238] As shown in FIG. 6, the composite prepared in Preparation Example 1 exhibited a peak at 1338.7 cm due to graphene. -1 D band peak at 1575.0 cm -1 The G-band peak at

[0239] On the other hand, in the composite positive electrode active material of Example 1, the D band peak was 1351.3 cm -1 and about 12 cm -1 The G-band peak shifted to 1593.6 cm -1 and about 18 cm -1 Shifted.

[0240] The shift in the D-band peak was attributed to the strain of the graphene that was bonded onto the core by milling to form the shell.

[0241] The shift in the G-band peak was determined to be due to charge transfer between the core and graphene in the complex formed by CO-Ni bonds.

[0242] Therefore, it was confirmed that the graphene contained in the shell formed on the core forms a covalent bond with Ni, a transition metal contained in the core.

[0243] Evaluation example 5: Electrode cross section evaluation Scanning electron microscope (SEM) and SEM-EDS (Energy-dispersive X-ray spectroscopy) images of the cross sections of the dry cathodes prepared in Comparative Example 3 and Example 4 were measured, and the results are shown in FIGS. 7A to 8B.

[0244] 7A is a scanning electron microscope image of a cross section of the dry positive electrode prepared in Comparative Example 3. FIG. 7B is a SEM-EDS mapping image of a cross section of the dry positive electrode prepared in Comparative Example 3.

[0245] 8A is a scanning electron microscope image of a cross section of the dry positive electrode prepared in Example 4. FIG. 8B is a SEM-EDS mapping image of a cross section of the dry positive electrode prepared in Example 4.

[0246] 7A and 7B, it was confirmed that the dry binder was not uniformly distributed within the dry electrode film and agglomerated in the dry positive electrode prepared in Comparative Example 3. The area where the binder was agglomerated is indicated by a dotted circle.

[0247] As shown in FIGS. 8A and 8B, it was confirmed that the dry binder was uniformly distributed within the dry electrode film in the dry positive electrode prepared in Example 4.

[0248] It was determined that the use of a core / shell structured composite positive electrode active material in the dry electrode of Example 4 resulted in a uniform distribution of the binder and conductive material within the dry electrode film.

[0249] On the other hand, it was determined that the use of a bare positive electrode active material in the dry electrode of Comparative Example 3 made it impossible to suppress the aggregation of the binder and conductive material within the dry electrode film, resulting in uneven distribution of the binder within the dry electrode film.

[0250] Evaluation example 6: Peel strength evaluation For each of the dry cathodes prepared in Example 4 and Comparative Example 3 and the wet cathode prepared in Comparative Example 4, the cathode was cut into a 25 mm × 150 mm piece and attached to the center of a 30 mm × 200 mm glass slide using tape. The current collector was then peeled from the positive electrode active material layer using a Universal Testing Machine (UTM) to measure the 90° peel strength. The measurement results are shown in Table 1 below.

[0251] [Table 1]

[0252] As shown in Table 1, the dry positive electrode of Example 4 exhibits improved adhesive strength compared to the dry positive electrode of Comparative Example 3.

[0253] It was determined that this was because the binder in the dry positive electrode of Example 4 was more uniformly distributed within the dry electrode film compared to the dry positive electrode of Comparative Example 3, and the fibrous binder more effectively bound the dry electrode film and the positive electrode current collector.

[0254] Furthermore, the dry positive electrode of Example 4 exhibits improved adhesive strength compared to the wet positive electrode of Comparative Example 4.

[0255] Evaluation example 7: Tensile strength evaluation For each of the dry cathode films prepared in Example 4 and Comparative Example 3, a test specimen (216 mm (Length) × 19±0.5 mm (Width) × 3.18±0.38 mm (Depth)) for measuring tensile strength according to ASTM D 638 was prepared. A tensile strength test was performed according to the ASTM D 638 method to measure the tensile strength. The measurement results are shown in Table 2 below.

[0256] [Table 2]

[0257] As shown in Table 2, the dry positive electrode film of Example 4 exhibits improved mechanical strength compared to the dry positive electrode film of Comparative Example 3.

[0258] It was determined that this was because the binder in the dry positive electrode of Example 4 was more uniformly distributed within the dry electrode film compared to the dry positive electrode of Comparative Example 3, and the fibrous binder more effectively bound the composite positive electrode active material.

[0259] Evaluation Example 8: Combination drug resistance evaluation The composite resistance of each of the dry positive electrodes prepared in Example 4 and Comparative Example 3 and the wet positive electrode prepared in Comparative Example 4 was measured at 25°C using an electrode resistance measurement system (Hioki, RM2610). The measurement results are shown in Table 3 below.

[0260] Using an electrode resistance measurement system (Hioki, RM2610), a probe was placed on the positive electrode so that the positive electrode active material layer of the positive electrode faced the probe, and a constant current was passed through the surface of the positive electrode active material layer to measure the volume resistivity of the positive electrode active material layer and the interface resistance between the positive electrode active material layer and the positive electrode current collector from the surface potential distribution. The volume resistivity of the positive electrode active material layer was considered to be the composite resistance of the positive electrode active material layer.

[0261] [Table 3]

[0262] As shown in Table 3, the dry positive electrode of Example 4 had a reduced composite resistance compared to the dry positive electrode of Comparative Example 3 and the wet positive electrode of Comparative Example 4.

[0263] It was determined that the dry positive electrode of Example 4 had improved electronic conductivity and / or ionic conductivity within the dry positive electrode film due to the inclusion of a composite positive electrode active material in which a shell including a first metal oxide and a first carbon-based material was uniformly disposed on a core.

[0264] It was determined that this was because the dry positive electrode of Comparative Example 3 and the wet positive electrode of Comparative Example 4 did not contain the composite positive electrode active material described above, and therefore the electronic conductivity and / or ionic conductivity decreased.

[0265] Evaluation example 9: Interface resistance evaluation The interface resistance of each of the dry positive electrodes prepared in Example 4 and Comparative Example 3 and the wet positive electrode prepared in Comparative Example 4 was measured at 25°C using an electrode resistance measurement system (Hioki, RM2610). The measurement results are shown in Table 4 below.

[0266] Using an electrode resistance measurement system (Hioki, RM2610), a probe was placed on the positive electrode so that the positive electrode active material layer of the positive electrode faced the probe, and a constant current was passed through the surface of the positive electrode active material layer. From the surface potential distribution, the volume resistivity of the positive electrode active material layer and the interface resistance between the positive electrode active material layer and the positive electrode current collector were measured.

[0267] [Table 4]

[0268] As shown in Table 4, the dry positive electrode of Example 4 had a reduced interfacial resistance compared to the dry positive electrode of Comparative Example 3 and the wet positive electrode of Comparative Example 4.

[0269] Evaluation example 10: Evaluation of charge / discharge characteristics at room temperature (25°C) The lithium batteries prepared in Examples 4 to 6 and Comparative Examples 3 to 5 were charged at a constant current of 0.1 C rate at 25°C until the voltage reached 4.3 V (vs. Li), and then cut off at a current of 0.05 C rate while maintaining 4.3 V in constant voltage mode. They were then discharged at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during discharge (formation cycle).

[0270] The lithium battery after the chemical formation cycle was charged at 25°C at a constant current of 0.5 C rate until the voltage reached 4.3 V (vs. Li). It was then cut off at a current of 0.05 C rate while maintaining 4.3 V in constant voltage mode. It was then discharged at a constant current of 0.5 C rate until the voltage reached 2.8 V (vs. Li) (1st cycle). This cycle was repeated under the same conditions up to 350th cycle.

[0271] In all charge / discharge cycles, a 10-minute rest period was allowed after each charge / discharge cycle. Some of the results of the room temperature charge / discharge experiments are shown in Table 5 below. The capacity retention rate is defined by the following Equation 3.

[0272] <Number 3> Capacity retention rate [%] = [discharge capacity at 300th cycle / discharge capacity at 1st cycle] x 100

[0273] [Table 5]

[0274] As shown in Table 1 and FIG. 1, the lithium batteries of Examples 4 to 6 had improved life characteristics compared to the lithium batteries of Comparative Examples 3 and 4.

[0275] The lithium batteries of Examples 5 and 6 had further improved life characteristics compared to the lithium battery of Example 4.

[0276] Although not shown in Table 1, the lithium battery of Comparative Example 5 was inferior to the lithium battery of Example 4 in life characteristics.

[0277] It was determined that this was because the high voltage stability of the SiO2@Gr composite placed on the NCA91 core was poor in the lithium battery of Comparative Example 5.

[0278] Evaluation Example 11: Evaluation of vertical adhesion strength of positive electrode active material layer (I) Using SAICAS (SAICAS EN-EX, Daipla Wintes, JAPAN), the binding properties of the positive electrode active material layers included in the dry positive electrode of Example 4 and the wet positive electrode prepared in Comparative Example 4 were analyzed.

[0279] A constant speed analysis was performed using a 1mm wide diamond blade with a clearance angle of 10°, a rake angle of 20°, a shearing angle of 45°, a horizontal velocity of 4μm / s, and a vertical velocity of 0.4μm / s to measure the vertical adhesive force (F V , Vertical Force) were measured.

[0280] First, a first constant-rate analysis was performed from a first position on the surface of the positive electrode active material layer to the surface of the positive electrode current collector. The blade was then moved horizontally along the surface of the positive electrode current collector to remove the positive electrode active material layer. Next, a second constant-rate analysis was performed under the same conditions as the first constant-rate analysis at a position 10 μm back from the first position. The data measured in the second constant-rate analysis were used.

[0281] The vertical binding strength of the positive electrode active material layer was measured, and the measured data was normalized to the area of ​​the binding strength graph to determine the vertical relative binding strength (F VR , Vertical Relative Force) were derived.

[0282] The vertical adhesive strength of the positive electrode active material layer was measured from a first point 5% away from the surface of the positive electrode active material layer to a second point 5% away from the surface of the electrode current collector relative to the total thickness of the positive electrode active material layer. That is, data near the surface of the positive electrode active material layer and near the surface of the electrode current collector were excluded to prevent measurement errors.

[0283] The vertical relative binding strength (F VR From the vertical relative force data, the vertical cohesive force (FVR The rate of change in the vertical relative force (F VR Arithmetic mean values ​​were also calculated from the Vertical Relative Force (VRF) data.

[0284] <Number 1> Vertical relative adhesive force (F VR , Vertical Relative Force) change rate = [(maximum value of vertical relative adhesive force - minimum value of vertical relative adhesive force) / minimum value of vertical relative adhesive force] x 100 As a result of the measurement, the rate of change in the vertical relative binding strength of the positive electrode active material layer contained in the dry positive electrode of Example 4 was 200% or less.

[0285] Therefore, it was confirmed that the positive electrode active material layer (ie, dry electrode film) of Example 4 had uniform binding strength and composition distribution regardless of the position in the thickness direction of the positive electrode active material layer.

[0286] On the other hand, the positive electrode active material layer included in the wet positive electrode of Comparative Example 4 had a rate of change in the relative binding strength in the vertical direction of more than 400%.

[0287] Therefore, it was confirmed that the positive electrode active material layer of Comparative Example 4 had a binding strength and composition distribution that significantly changed depending on the position in the thickness direction of the positive electrode active material layer.

[0288] Evaluation Example 12: Evaluation of horizontal adhesion strength of positive electrode active material layer (II) Using SAICAS (SAICAS EN-EX, Daipla Wintes, JAPAN), the binding properties of the positive electrode active material layers included in the dry positive electrode prepared in Example 4 and the wet positive electrode prepared in Comparative Example 4 were analyzed.

[0289] A constant speed analysis was performed using a 1mm wide diamond blade under the conditions of a clearance angle of 10°, a rake angle of 20°, a shearing angle of 45°, a horizontal velocity of 4μm / s, and a vertical velocity of 0.4μm / s, and the horizontal adhesive force (F H , Horizontal Force) were measured.

[0290] First, a first constant-rate analysis was performed from a first position on the surface of the positive electrode active material layer to the surface of the positive electrode current collector. The blade was then moved horizontally along the surface of the positive electrode current collector to remove the positive electrode active material layer. Next, a second constant-rate analysis was performed under the same conditions as the first constant-rate analysis at a position 10 μm back from the first position. The data measured in the second constant-rate analysis were used.

[0291] The first horizontal adhesive strength (F) at a first point 10% away from the surface of the positive electrode active material layer relative to the total thickness of the positive electrode active material layer H1 , Horizontal Force) and a second horizontal adhesion force (F H2 , Horizontal Force) were measured.

[0292] The ratio of the horizontal adhesive force between the first point and the second point is defined by the following equation 2.

[0293] <Number 2> Ratio of horizontal bonding strength between point 1 and point 2 (%) = [F H2 / F H1 ] x 100 As a result of the measurement, the ratio of the horizontal relative binding strength of the positive electrode active material layer of Example 4 was 60% or more.

[0294] On the other hand, the ratio of the horizontal bonding strength of the positive electrode active material layer of Comparative Example 4 was less than 50%.

[0295] That is, the ratio of the horizontal relative binding strength of the positive electrode active material layer of Example 4 was increased compared to that of the positive electrode active material layer of Comparative Example 4.

[0296] Therefore, it was confirmed that the positive electrode active material layer of Example 4 (ie, dry electrode film) had a more uniform binding strength and composition distribution than the positive electrode active material layer of Comparative Example 4. [Industrial Applicability]

[0297] In one aspect, the internal resistance of the dry electrode film is reduced and the mechanical properties are improved, thereby improving the cycle characteristics of a lithium battery employing such a dry electrode film. [Explanation of symbols]

[0298] 1 lithium battery 2 negative electrode 3 Positive electrode 4 Separator 5 Battery case 6 Cap Assembly 7 Battery structure 8 Electrode Tabs 10 cores 20 shells 21 First Metal Oxides 22 First carbon-based materials 23 Secondary carbon-based materials 100 Dry electrode active material

Claims

1. A dry electrode active material and a dry binder are included, The dry electrode active material includes a core and a shell disposed along a surface of the core, the shell comprises one or more first metal oxides and a first carbon-based material; the first metal oxide is disposed within a first carbon-based material matrix; The first metal oxide is represented by the chemical formula M ａ O ｂ (0<a≦3, 0<b<4, and if a is 1, 2, or 3, b is not an integer), and M is one or more metals selected from Groups 2 to 16 of the Periodic Table of Elements.

2. the metal contained in the first metal oxide is one or more metals selected from Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se; The first metal oxide is Al ２ O ｚ (0<z<3), NbO ｘ (0<x<2.5), MgO ｘ (0<x<1), Sc ２ O ｚ (0<z<3), TiO ｙ (0<y<2), ZrO ｙ (0<y<2), V ２ O ｚ (0<z<3), WO ｙ (0<y<2), MnO ｙ (0<y<2), Fe ２ O ｚ (0<z<3), Co ３ O ｗ (0<w<4), PdO ｘ (0<x<1), CuO ｘ (0<x<1), AgO ｘ (0<x<1), ZnO ｘ (0<x<1), Sb ２ O ｚ (0<z<3), and SeO ｙ The dry electrode film according to claim 1 , wherein y is one or more selected from (0<y<2).

3. the shell further comprises a second metal oxide; The second metal oxide is represented by the chemical formula M ａ O ｃ (0<a≦3, 0<c≦4, if a is 1, 2, or 3, then c is an integer), the second metal oxide comprises the same metal as the first metal oxide; The ratio of a to c of the second metal oxide, c / a, is greater than the ratio of a to b of the first metal oxide, b / a, The dry electrode film of claim 1 , wherein the second metal oxide is disposed within the first carbon-based material matrix.

4. The second metal oxide is Al ２ O ３ , NbO, NbO ２ , Nb ２ O ５ MgO, Sc ２ O ３ , TiO ２ , ZrO ２ , V ２ O ３ , W.O. ２ , MnO ２ , Fe ２ O ３ , Co ３ O ４ , PdO, CuO, AgO, ZnO, Sb ２ O ３ , and SeO ２ is selected from 4. The dry electrode film of claim 3, wherein the first metal oxide is a reduction product of the second metal oxide.

5. the shell has a thickness of 0.1 nm to 5 μm and a single-layer structure or a multi-layer structure; The dry electrode film of claim 1 , wherein the shell is a dry coating layer, and the content of the shell is 5 wt % or less based on the total weight of the dry electrode active material.

6. further comprising a third metal doped on the core or a third metal oxide coated on the core; the shell is disposed on the third metal oxide; The dry electrode film according to claim 1 , wherein the third metal oxide is an oxide of one or more third metals selected from the group consisting of Al, Zr, W, and Co.

7. the shell further comprises a second carbon-based material; the second carbon-based material includes a fibrous carbon-based material with an aspect ratio of 10 or more, the second carbon-based material comprises carbon nanofibers, carbon nanotubes, or a combination thereof; The carbon nanotubes include a carbon nanotube primary structure, a carbon nanotube secondary structure formed by aggregating a plurality of carbon nanotube primary particles, or a combination thereof; The dry electrode film according to claim 1 , wherein the carbon nanotube primary structure is a single carbon nanotube unit.

8. 10. The dry electrode film of claim 1, wherein the core comprises a lithium transition metal oxide.

9. The dry electrode film according to claim 8 , wherein the lithium transition metal oxide is represented by a chemical formula selected from the following Chemical Formula 1 to Chemical Formula 8: <Chemical 1> Li ａ Ni ｘ Co ｙ M ｚ O ２－ｂ A ｂ In the above Chemical Formula 1, 1.0≦a≦1.2, 0≦b≦0.2, 0.8≦x<1, 0≦y≦0.3, 0<z≦0.3, and x+y+z=1; M is 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), boron (B), or a combination thereof; A is F, S, Cl, Br or a combination thereof; <Case 2> L)) ｘ Co ｙ Mn ｚ O ２ <C3> L)) ｘ Co ｙ Al ｚ O ２ In Formulas 2 and 3, 0.8≦x≦0.95, 0≦y≦0.2, 0<z≦0.2, and x+y+z=1; <Case 4> L)) ｘ Co ｙ Mn ｚ Al ｗ O ２ In the formula 4, 0.8≦x≦0.95, 0≦y≦0.2, 0<z≦0.2, 0<w≦0.2, and x+y+z+w=1; <C5> Li ａ Co ｘ M ｙ O ２－ｂ A ｂ In the above Chemical Formula 5, 1.0≦a≦1.2, 0≦b≦0.2, 0.9≦x≦1, 0≦y≦0.1, and x+y=1; M is 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), boron (B), or a combination thereof; A is F, S, Cl, Br or a combination thereof; <C6> Li ａ Ni ｘ Mn ｙ M' ｚ O ２－ｂ A ｂ In the above Chemical Formula 6, 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' is 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; A is F, S, Cl, Br or a combination thereof; <C7> Li ａ M1 ｘ M2 ｙ PO ４－ｂ X ｂ In the formula 7, 0.90≦a≦1.1, 0≦x≦0.9, 0≦y≦0.5, 0.9<x+y<1.1, and 0≦b≦2; M1 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof; M2 is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), titanium (Ti), zinc (Zn), boron (B), niobium (Nb), gallium (Ga), indium (In), molybdenum (Mo), tungsten (W), aluminum (Al), silicon (Si), chromium (Cr), vanadium (V), scandium (Sc), yttrium (Y), or a combination thereof; and X is O, F, S, P, or a combination thereof. <Chemical formula 8> Li ａ M3 ｚ PO ４ In the formula 8, 0.90≦a≦1.1 and 0.9≦z≦1.1; M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof.

10. the shell comprises a first metal oxide and a first carbon-based material, and the core comprises a lithium transition metal oxide; The first carbon-based material and the transition metal of the lithium transition metal oxide are chemically bound through a chemical bond; The carbon atom (C) of the first carbon-based material and the transition metal (Me) of the lithium transition metal oxide are chemically bound via a C—O—Me bond via an oxygen atom; The dry electrode film of claim 1 , wherein the first metal oxide is chemically bound to the first carbon-based material via a chemical bond.

11. The dry electrode film according to claim 1 , wherein the dry electrode active material comprises a first dry electrode active material and a second dry electrode active material, and the first dry electrode active material and the second dry electrode active material have different particle sizes.

12. The first dry electrode active material is a large-diameter dry electrode active material having a particle size larger than that of the second dry electrode active material, The dry electrode film according to claim 11 , wherein the second dry electrode active material is a small-diameter dry electrode active material having a particle size smaller than that of the first dry electrode active material.

13. the first dry electrode active material and the second dry electrode active material have a bimodal particle size distribution in a particle size distribution diagram; The particle size ratio of the first dry electrode active material to the second dry electrode active material is 3:1 to 40:1; The particle size of the first dry electrode active material is more than 8 μm and less than 30 μm, and the particle size of the second dry electrode active material is 1 μm to less than 8 μm; the second dry electrode active material includes primary particles with a particle diameter of 1 μm or more; The dry electrode film according to claim 12, wherein the weight ratio of the first electrode active material to the second dry electrode active material is 90:10 to 60:

40.

14. the dry binder comprises a fibrillized binder; The dry binder includes a fluorine-based binder, The glass transition temperature (Tg) of the dry binder is 15 to 100°C; The dry electrode film of claim 1 , wherein the dry binder content is 0.1 to 5 wt % based on the total weight of the dry electrode film.

15. The dry electrode film further comprises a dry conductive material; the dry conductive material comprises a carbon-based conductive material; the carbonaceous conductive material comprises a fibrous carbonaceous material with an aspect ratio of 10 or more, a granular carbonaceous material with an aspect ratio of less than 10, or a combination thereof; The dry electrode film of claim 1 , wherein the content of the dry conductive material is 0.1 to 5 wt % based on the total weight of the dry electrode film.

16. The dry electrode film is a self-standing film, and the dry electrode film is free of residual processing solvents; The dry electrode film according to claim 1, wherein the dry electrode film has a tensile strength of 500 kPa to 5000 kPa.

17. an electrode current collector; and the dry electrode film according to any one of claims 1 to 16, which is disposed on one or both surfaces of the electrode current collector.

18. the electrode current collector includes a substrate and an interlayer disposed between the substrate and the dry electrode film; 18. The dry electrode of claim 17, wherein the intermediate layer comprises a carbon-based conductive material.

19. the electrode current collector includes a base film and a metal layer disposed on one or both sides of the base film, the dry film is disposed on the metal layer; the base film comprises a polymer, the polymer comprising polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof; 18. The dry electrode of claim 17, wherein the metal layer comprises indium (In), copper (Cu), magnesium (Mg), titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof.

20. a first electrode, a second electrode, and an electrolyte disposed between the first and second electrodes; The first electrode, the second electrode, or a combination thereof is the dry electrode of claim 17, The lithium battery, wherein the electrolyte comprises a liquid electrolyte, a solid electrolyte, or a combination thereof.

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