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

Abstract

A dry electrode film, and a dry electrode and a lithium battery including the dry electrode film are provided. The dry electrode film includes a dry electrode active material and a dry binder, in which the dry electrode active material includes: a core; and a shell disposed along a surface of the core, the shell comprising a first carbon-based material and at least one type of first metal oxide disposed within a matrix of the first carbon-based material, and the first metal oxide being formed from a first metal oxide of the chemical formula MaOb (0lt; a < = 3 and 0 lt; blt; and b is not an integer when a is 1, 2 or 3), and M is one or more metals selected from Group 2 to Group 16 of the Periodic Table of Elements.

Description

Technical Field

[0001] One or more embodiments of the present disclosure relate to a dry electrode film, a dry electrode, and a lithium battery, all of which include the dry electrode film. Background Art

[0002] To meet the miniaturization and high performance of one or more suitable electronic devices, in addition to miniaturization and weight reduction, the high energy density of lithium batteries is becoming important and attractive. For example, high-capacity lithium batteries are becoming important and / or desirable.

[0003] Since an excessive amount of solvent is used to fabricate an electrode made of a solvent-containing slurry, a dry (e.g., solid-state) method that excludes (or does not use) organic solvents is attracting attention and / or being studied. Summary of the Invention

[0004] Technical Problem One or more aspects of embodiments of the present disclosure relate to a dry (e.g., solid-state) electrode film having improved cycle characteristics by reducing internal resistance and improving mechanical strength.

[0005] One or more aspects of embodiments of the present disclosure relate to a dry electrode including the dry electrode film.

[0006] One or more aspects of embodiments of the present disclosure relate to a lithium battery including the dry electrode.

[0007] Technical Solution According to one or more embodiments of the present disclosure, the dry electrode film includes a dry electrode active material and a dry binder, wherein the dry electrode active material includes a core and a shell on the surface of the core, the shell includes a first carbonaceous material and at least one first metal oxide, the first metal oxide is in the first carbonaceous material matrix, the first metal oxide is represented by the formula M a O b (where 0 < a ≤ 3, 0 < b < 4, and when a is 1, 2, or 3, b is not an integer), where M includes at least one element selected from the elements of Groups 2 to 16 of the periodic table.

[0008] According to one or more embodiments of the present disclosure, the dry electrode includes: an electrode current collector; and the dry electrode film on one or both sides (e.g., opposite sides) of the electrode current collector.

[0009] According to one or more embodiments of the present disclosure, The lithium battery includes a first electrode, a second electrode, and an electrolyte between the first electrode and the second electrode, and wherein, the first electrode, the second electrode, or a combination thereof is the dry electrode.

[0010] Advantageous Effects According to one or more aspects of the embodiments of the present disclosure, since the dry electrode film has a reduced internal resistance and improved mechanical properties, the cycle characteristics of the lithium battery including the dry electrode film can be improved. Description of the Drawings

[0011] Figure 1 is a schematic cross-sectional view of a dry positive electrode active material according to one or more embodiments of the present disclosure.

[0012] Figure 2 is a schematic cross-sectional view of a dry positive electrode active material according to one or more embodiments of the present disclosure.

[0013] Figure 3 is a scanning electron microscope (SEM) image of the surface of bare NCA91 prepared in Comparative Example 1 according to one or more embodiments of the present disclosure.

[0014] Figure 4 is an SEM image of the composite positive electrode active material prepared in Example 1 according to one or more embodiments of the present disclosure.

[0015] Figure 4 is an image showing the X-ray photoelectron spectroscopy (XPS) results of bare NCA91 prepared in Comparative Example 1, the composite prepared in Preparation Example 1, and the composite positive electrode active material prepared in Example 1 according to one or more embodiments of the present disclosure.

[0016] Figure 5 is an image showing the Raman spectroscopy results of the composite prepared in Preparation Example 1 and the composite positive electrode active material prepared in Example 1 according to one or more embodiments of the present disclosure.

[0017] Figure 7a is an SEM image of the cross-section of the dry positive electrode prepared in Comparative Example 3 according to one or more embodiments of the present disclosure.

[0018] Figure 7b is an SEM-EDS mapping image of the cross-section of the dry positive electrode prepared in Comparative Example 3 according to one or more embodiments of the present disclosure.

[0019] Figure 8a is an SEM image of the cross-section of the dry positive electrode prepared in Example 4 according to one or more embodiments of the present disclosure.

[0020] Figure 8b SEM-EDS mapping image of the cross-section of the dry positive electrode prepared in Example 4 according to one or more embodiments of the present disclosure.

[0021] Figure 9 Schematic diagram of a lithium battery according to one or more embodiments of the present disclosure.

[0022] Figure 10 Schematic diagram of a lithium battery according to one or more embodiments of the present disclosure.

[0023] Figure 11 Schematic diagram of a lithium battery according to one or more embodiments of the present disclosure.

[0024] Description of the reference numerals of the main elements of the drawings 1 Lithium battery; 2 Negative electrode 3 Positive electrode; 4 Separator 5 Battery housing; 6 Cover assembly 7 Battery assembly; 8 Electrode tab 10 Core; 20 Shell 21 First metal oxide; 22 First carbonaceous material 23 Second carbonaceous material; 100 Dry electrode active material. Detailed description of the embodiments

[0025] Various embodiments are shown in the drawings. However, the present disclosure may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. On the contrary, the embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art. Like reference numerals in the drawings denote like elements.

[0026] It will be understood that when an element is referred to as being "on" another element, it can be directly on the other element, or intervening elements may also be present therebetween. In contrast, when an element is referred to as being "directly on" another element, there are no intervening elements therebetween.

[0027] Although the terms "first", "second", "third", etc. may be used herein to describe one or more suitable elements, components, regions, layers, and / or parts, these elements, components, regions, layers, and / or parts should not be limited by these terms. These terms are only used to distinguish one element, component, region, layer, or part from another element, component, region, layer, or part. Thus, without departing from the teachings herein, the first element, first component, first region, first layer, or first part discussed may be referred to as the second element, second component, second region, second layer, or second part.

[0028] The terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the present disclosure. As used herein, unless otherwise indicated, the singular forms of expressions cover the expression “at least one (kind / one)”. “At least one (kind / one)” should not be construed as singular. As used herein, terms such as “comprising”, “having”, “including” and / or their variants are intended to indicate the presence of the features, regions, wholes, operations, components and / or elements disclosed in the specification, and are not intended to preclude the possibility that one or more other features, regions, wholes, operations, components and / or elements may exist or may be added.

[0029] For ease of description of the relationship of one element or feature to another (others) as shown in the drawings, spatial relative terms such as “below”, “beneath”, “lower”, “on”, “above” or “upper” may be used herein. It will be understood that the spatial relative terms are intended to cover different orientations of the device in use or operation in addition to the orientation depicted in the drawings. For example, when the device in the drawings is turned over, an element described as “below” other elements or features will then be oriented “above” the other elements or features. Thus, the example term “below” can (e.g., simultaneously) cover both the upper and lower orientations. The device may be otherwise oriented (e.g., rotated 90 degrees or at other orientations), and the spatial relative descriptors used herein are to be interpreted accordingly.

[0030] Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. In addition, it will be understood that terms (such as those defined in a common dictionary) should be interpreted as having a meaning consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.

[0031] Example embodiments will be described herein with reference to schematic cross-sectional views of one or more embodiments. As such, variations in the shape of the illustrations due to, for example, manufacturing techniques and / or tolerances can be expected. Thus, example embodiments should not be construed as limited to the specific shapes of the regions shown herein, but include, for example, shape deviations caused by manufacturing. For example, regions shown or described as flat may generally have rough and / or non-linear features. In addition, the acute angles shown may be rounded. Thus, the regions shown in the drawings are schematic in nature, and their shapes are not intended to show or limit the actual shape of the regions of the device and thus are not intended to limit the scope of the claims.

[0032] The term "group" refers to a set of elements in the periodic table numbered from 1 to 18 classified according to the classification system of the International Union of Pure and Applied Chemistry ("IUPAC").

[0033] In the present disclosure, the "particle size" of a particle represents the average diameter of a spherical particle or the average length of the major axis of a non-spherical particle. The particle size of a particle can be measured using a particle size analyzer (PSA). The "particle size" of a particle can be, for example, the average particle size. The "average particle size" can be, for example, the median particle size (D50).

[0034] D50 refers to the particle size corresponding to 50% of the particles in a cumulative particle size distribution curve measured by laser diffraction method in which the particles are accumulated in order of particle size from the smallest particle to the largest particle.

[0035] D90 refers to the particle size corresponding to 90% of the particles in a cumulative particle size distribution curve measured by laser diffraction method in which the particles are accumulated in order of particle size from the smallest particle to the largest particle.

[0036] D10 refers to the particle size corresponding to 10% of the particles in a cumulative particle size distribution curve measured by laser diffraction method in which the particles are accumulated in order of particle size from the smallest particle to the largest particle.

[0037] In the present disclosure, the term "metal" can include metals and metalloids (such as silicon and germanium) in elemental or ionic states.

[0038] In the present disclosure, the term "alloy" can refer to a mixture of two or more metals.

[0039] In the present disclosure, the term "electrode active material" can refer to a material for an electrode that allows lithiation and delithiation.

[0040] In the present disclosure, the term "positive electrode active material" can refer to a material for a positive electrode that allows lithiation and delithiation.

[0041] In the present disclosure, the term "negative electrode active material" can refer to a material for a negative electrode that allows lithiation and delithiation.

[0042] In the present disclosure, the term "lithiation" and its variants can refer to the process of adding lithium to an electrode active material.

[0043] In the present disclosure, the term "delithiation" and its variants can refer to the process of removing lithium from an electrode active material.

[0044] In the present disclosure, the term "charging" and its variants can refer to the process of supplying electrochemical energy to a battery.

[0045] In the present disclosure, the term "discharging" and its variants can refer to the process of removing electrochemical energy from a battery.

[0046] In the present disclosure, the terms "positive electrode" and "positive electrode" may refer to an electrode that undergoes electrochemical reduction and lithiation during discharge.

[0047] In the present disclosure, the terms “negative electrode” and “anode” may refer to an electrode that undergoes electrochemical oxidation and delithiation during discharge.

[0048] Although example embodiments will be described, the applicant or other skilled in the art may think of alternatives, modifications, variations, improvements, and substantial equivalents that are not currently foreseen or may not be foreseen. Therefore, the appended claims as filed and as may be amended are intended to cover all such alternatives, modifications, variations, improvements, and substantial equivalents.

[0049] Hereinafter, a dry electrode film according to one or more embodiments, and a dry electrode and a lithium battery each including the dry electrode film will be described in more detail.

[0050] According to one or more embodiments, a dry (e.g., solid) electrode film may include a dry electrode active material and a dry binder, wherein the dry electrode active material may include a core and a shell on the surface of the core, the shell may include at least one first metal oxide and a first carbon-based material, the first metal oxide is located in a first carbon-based material matrix (e.g., a matrix of the first carbon-based material), and the first metal oxide may be represented by formula M a O b (where 0 <a≤3,0<b<4,并且在a为1、2或3的情况下(例如,实施例中),b不为整数)表示,其中,M可以包括选自元素周期表的第2族至第16族的元素中的至少一种金属。参照 Figure 1 , the dry electrode active material 100 may include a core 10 and a shell 20 that is continuously or discontinuously on (e.g., located on) the surface of the core 10. The shell 20 may cover the core 10 in whole or in part. The shell 20 may include a first metal oxide 21 and a first carbon-based material 22. The dry electrode active material may be, for example, an electrode active material that is not impregnated by a process solvent, is not dissolved in a process solvent, or is not dispersed in a process solvent during a process for manufacturing a dry electrode film. The dry electrode active material may be, for example, an electrode active material that does not include a process solvent or does not come into contact with a process solvent during a process for manufacturing a dry electrode film.

[0051] Because the dry electrode active material has a core / shell structure and the shell includes the first carbon-based material, the dry electrode active material can be more evenly mixed with the dry binder. Therefore, the agglomeration of the dry binder can be suppressed in the dry electrode film, and the dry binder can be substantially uniformly dispersed in three dimensions. Because the formation of the local resistance region is suppressed in the dry electrode film, the imbalance of the current density can be reduced, and the overall internal resistance of the dry electrode film can be reduced.

[0052] Since the dry electrode active material has a core / shell structure and the shell includes a first carbonaceous material, the interfacial resistance between multiple dry electrode active materials can be reduced. Since the dry electrode active material has a core / shell structure and the shell includes a first carbonaceous 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 includes a first carbonaceous material, the binding force 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 includes a first carbonaceous material, the mechanical properties (such as tensile strength) of the dry electrode film can be improved. Since the dry electrode film has a reduced internal resistance and improved mechanical properties, the cycle characteristics of a lithium battery including the dry electrode film can be improved.

[0053] In one or more embodiments, compared with a shell formed of a carbonaceous material, a shell including a first metal oxide can have improved ionic conductivity, and thus the ionic conductivity of the dry electrode active material can be improved.

[0054] In one or more embodiments, the dry electrode active material may have a core / shell structure, and the shell may be disposed on the surface of the core continuously or discontinuously. Since the shell includes a first metal oxide located (e.g., dispersed) in a first carbonaceous material matrix, the shell may be disposed on the core more uniformly. Since the shell is introduced onto the core by a composite including a first metal oxide located in a first carbonaceous material matrix, the shell does not agglomerate and may be disposed on the core more uniformly. The shell disposed on the core uniformly effectively blocks the contact between the core and the electrolyte, thereby preventing or reducing side reactions caused by the contact between the core and the electrolyte. In some embodiments, cation mixing caused by the contact between the core and the electrolyte is inhibited, thereby preventing or reducing the formation of a resistive layer on the surface of the core. In some embodiments, the shell introduced onto the core may inhibit the elution of ions of transition metals from the core including transition metals. In one or more embodiments, the first carbonaceous material may be, for example, a crystalline carbonaceous material. In one or more embodiments, the first carbonaceous material may be, for example, a carbonaceous nanostructure. In one or more embodiments, the first carbonaceous material may be, for example, a two-dimensional carbonaceous nanostructure. In some embodiments, the first carbonaceous material may be, for example, graphene. For example, since the shell including graphene and / or its matrix is flexible, it is easy to accept and / or tolerate volume changes of the dry electrode active material during charging and discharging, and thus cracks appearing inside the dry electrode active material can be inhibited. Since graphene has high electronic conductivity, the interfacial resistance between the dry electrode active material and an electrolyte solution (e.g., an electrolyte) is reduced. Therefore, an increase in the internal resistance of the lithium battery can be inhibited despite the introduction of the shell including graphene. In contrast, a comparative carbonaceous material not including the first metal oxide may be prone to agglomeration and cannot be disposed on the core of the dry electrode active material uniformly. In some embodiments, the first carbonaceous material matrix derived from, for example, a graphene matrix has a relatively low density and a high porosity compared to a comparative carbonaceous material derived from a graphite-like material.

[0055] The dry electrode active material has a core / shell structure. The shell includes a first metal oxide, and the metal included in the first metal oxide may include, for example, at least one selected from aluminum (Al), niobium (Nb), magnesium (Mg), scandium (Sc), titanium (Ti), zirconium (Zr), vanadium (V), tungsten (W), manganese (Mn), iron (Fe), cobalt (Co), palladium (Pd), copper (Cu), silver (Ag), zinc (Zn), antimony (Sb), and selenium (Se). The first metal oxide may include, for example, those selected from Al2O z (where 0 < z < 3), NbO x (where 0 < x < 2.5), MgO x (where 0 < x < 1), Sc2O z (where 0 < z < 3), TiO y(where 0 < y < 2), ZrO y (where 0 < y < 2), V2O z (where 0 < z < 3), WO y (where 0 < y < 2), MnO y (where 0 < y < 2), Fe2O z (where 0 < z < 3), Co3O w (where 0 < w < 4), PdO x (where 0 < x < 1), CuO x (where 0 < x < 1), AgO x (where 0 < x < 1), ZnO x (where 0 < x < 1), Sb2O z (where 0 < z < 3) and SeO y (where 0 < y < 2) of at least one. By positioning the first metal oxide in the first carbonaceous 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. In some embodiments, the shell can include, for example, Al2O x (where 0 < x < 3) as the first metal oxide.

[0056] In one or more embodiments, the shell can further include at least one second metal oxide. The second metal oxide can be represented, for example, by the formula M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3 (for example, in embodiments), c is an integer), where M can include at least one metal selected from the elements of Groups 2 to 13, 15, and 16 of the periodic table. In some embodiments, the second metal oxide can include, for example, the same metal as the metal of the first metal oxide. The c / a ratio of the second metal oxide can have a value greater than the b / a ratio of the first metal oxide. For example, c / a > b / a. The second metal oxide can be located in the first carbonaceous material matrix. The second metal oxide can be 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 can be, for example, a reduction product of the second metal oxide. The first metal oxide can be obtained as a result of reducing part or all of the second metal oxide. Therefore, compared with the second metal oxide, the first metal oxide has a lower oxygen content (for example, oxygen amount) and a lower metal oxidation value. For example, in some embodiments, the shell includes Al2O as the first metal oxide xwhere 0 < x < 3) and Al2O3 as the second metal oxide.

[0057] In one or more embodiments, the shell may include at least one selected from the first metal oxide and the second metal oxide, and the particle size of at least one selected from the first metal oxide and the second metal oxide may be, 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 a nanoscale particle size within the above range, the first metal oxide and / or the second metal oxide can be more uniformly dispersed in the first carbonaceous material matrix. In embodiments where the particle size of at least one of the first metal oxide and the second metal oxide is too large, the thickness of the shell increases, resulting in an increase in the internal resistance of the composite electrode active material. In embodiments where the particle size of at least one of the first metal oxide and the second metal oxide is too small, it may be difficult to achieve a substantially uniform distribution.

[0058] In one or more embodiments, the shell may include the first metal oxide and / or the second metal oxide and include a first carbonaceous material. The first carbonaceous material may be arranged in a direction protruding from the surface of the first metal oxide and / or the second metal oxide. The first carbonaceous material may grow directly from the surface of the first metal oxide and / or the second metal oxide to be arranged in a direction protruding from the surface of the first metal oxide and / or the second metal oxide. The first carbonaceous 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 carbonaceous two-dimensional nanostructure, a carbonaceous flake, and / or graphene.

[0059] In one or more embodiments, the shell may have a thickness of, 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. In embodiments where the thickness of the shell is within the above range, the dry electrode including the dry electrode active material may have further improved electronic conductivity and further reduced internal resistance.

[0060] In one or more embodiments, the shell may have a single-layer structure or a multi-layer structure. The multi-layer structure may have a bilayer structure, a trilayer structure, and a four-layer structure. In the multi-layer structure, the types (species) of the metals of the first metal oxide included in different layers may be different from each other.

[0061] In one or more embodiments, based on the total weight of the dry electrode active material, the amount of the shell can be, for example, from 0.01 wt% to 5 wt%, from 0.01 wt% to 3 wt%, from 0.01 wt% to 2 wt%, or from 0.01 wt% to 1 wt%. Based on the total weight of the dry electrode active material, the amount of the first metal oxide can be, for example, from 0.006 wt% to 3 wt%, from 0.006 wt% to 1.8 wt%, from 0.006 wt% to 1.2 wt%, or from 0.006 wt% to 0.6 wt%. In embodiments where the amounts of the shell and the first metal oxide in the dry electrode active material are within the above ranges, the cycling characteristics of the lithium battery are further improved.

[0062] In one or more embodiments, the dry electrode active material may further include, for example, a third metal doped on the core or a third metal oxide coated on the core. In some embodiments, the shell may be on (e.g., disposed on) the third metal doped on the core or the third metal oxide coated on the core. For example, after doping a third metal on the surface of a compound (e.g., a lithium transition metal oxide) included in the core or coating a third metal oxide on the compound (e.g., a lithium transition metal oxide) included in the core, the shell may be disposed on the third metal and / or the third metal oxide. For example, in one or more embodiments, the dry electrode active material may include: a core; an intermediate layer disposed on the core; and a shell disposed on the intermediate layer, wherein the intermediate layer may include a third metal and / or a third metal oxide. The third metal may include at least one metal 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.

[0063] The shell disposed on the surface of the core may be, for example, a dry coating. The shell can be introduced onto the core by a dry method (such as by grinding). In some embodiments, the shell disposed on the surface of the core may include, for example, at least one selected from a composite including a first metal oxide and a first carbonaceous material (such as graphene) and a product obtained by grinding the composite. The first metal oxide is located in the matrix of the first carbonaceous material (e.g., the graphene matrix).

[0064] For example, in some embodiments, the shell may be prepared from a composite including a first metal oxide and a first carbonaceous material (such as graphene). In some embodiments, in addition to the first metal oxide, the composite may further include a second metal oxide. In some embodiments, the composite may include, for example, two or more types (species) of the first metal oxide. In some embodiments, the composite may include, for example, two or more types (species) of the first metal oxide and two or more types (species) of the second metal oxide.

[0065] In one or more embodiments, based on the total weight of the dry electrode active material, the amount of at least one of the composite and its ground product may be 5 wt% or less, 3 wt% or less, 2 wt% or less, 1 wt% or less, or 0.5 wt% or less. In some embodiments, based on the total weight of the dry electrode active material, the amount of at least one of the composite and its ground product may be from 0.01 wt% to 5 wt%, from 0.01 wt% to 3 wt%, from 0.01 wt% to 1 wt%, from 0.01 wt% to 0.7 wt%, or from 0.01 wt% to 0.5 wt%. In embodiments where the dry electrode active material includes at least one of the composite and its ground product within the above ranges, the cycling characteristics of the lithium battery including the dry electrode active material are further improved.

[0066] The composite may include at least one selected from a first metal oxide and a second metal oxide. The particle size of at least one selected from the first metal oxide and the second metal oxide may be from 0.1 nm to 100 nm, from 0.5 nm to 100 nm, from 1 nm to 100 nm, from 1 nm to 50 nm, from 1 nm to 30 nm, from 5 nm to 30 nm, or from 10 nm to 30 nm. By having a nanoscale particle size within the above ranges, the first metal oxide and / or the second metal oxide can be more uniformly dispersed in the first carbonaceous material matrix of the composite. Accordingly, the composite can be uniformly coated on the core without agglomeration to form a shell. In some embodiments, by having a particle size within the above ranges, the first metal oxide and / or the second metal oxide can be more uniformly disposed on the core. Accordingly, by uniformly disposing the first metal oxide and / or the second metal oxide on the core, high-voltage resistance can be obtained more effectively. The particle size of the first metal oxide and / or the second metal oxide can be measured by a measuring device using a laser diffraction method or a dynamic light scattering method. In one or more embodiments, the particle size can be measured by using, for example, a laser scattering particle size distribution analyzer (e.g., LA-920 from Horiba Instruments), and may be the median particle size (D50) at 50% of the total cumulative particle size distribution starting from the minimum particle size. The uniformity deviation of at least one selected from the first metal oxide and / or the second metal oxide may be 3% or less, 2% or less, or 1% or less. The uniformity can be obtained, for example, by X-ray photoelectron spectroscopy (XPS). Accordingly, at least one selected from the first metal oxide and the second metal oxide may have a uniformity deviation of 3% or less, 2% or less, or 1% or less, and may be uniformly dispersed in the composite.

[0067] In one or more embodiments, the composite includes a first carbonaceous material. The first carbonaceous material may have, for example, a branched structure, and at least one metal oxide selected from a first metal oxide and a second metal oxide may be dispersed in the branched structure of the first carbonaceous material. The branched structure of the first carbonaceous material may include, for example, a plurality of particles of the first carbonaceous material in contact with each other. Since the first carbonaceous material has a branched structure, one or more suitable conductive paths can be provided. In some embodiments, the first carbonaceous material may be, for example, graphene. Graphene may have, for example, a branched structure, and at least one metal oxide selected from a first metal oxide and a second metal oxide may be dispersed in the branched structure of the graphene. The branched structure of the graphene includes a plurality of graphene particles in contact with each other. Since graphene has a branched structure, one or more suitable conductive paths can be provided.

[0068] In one or more embodiments, the first carbonaceous material may have, for example, a spherical structure (e.g., a substantially spherical structure), and at least one metal oxide selected from a first metal oxide and a second metal oxide may be dispersed in the spherical structure. The spherical structure of the first carbonaceous material may have a size of 50 nm to 300 nm. There may be a plurality of first carbonaceous materials having a spherical structure. Since the first carbonaceous material has a spherical structure, the composite may have a rigid structure. In some embodiments, the first carbonaceous material may be, for example, graphene. Graphene may have, for example, a spherical structure, and at least one metal oxide selected from a first metal oxide and a second metal oxide may be dispersed in the spherical structure. The spherical structure of the graphene may have a size of 50 nm to 300 nm. There may be a plurality of graphene having a spherical structure. Since graphene has a spherical structure, the composite may have a rigid structure.

[0069] In one or more embodiments, the first carbonaceous material may have, for example, a helical structure formed by connecting a plurality of spherical structures (e.g., a substantially spherical structure), and at least one metal oxide selected from a first metal oxide and a second metal oxide may be dispersed in the spherical structures of the helical structure. The helical structure of the first carbonaceous material may have a size of 500 nm to 100 μm. Since the first carbonaceous material has a helical structure, the composite may have a rigid structure. In some embodiments, the first carbonaceous material may be, for example, graphene. Graphene may have, for example, a helical structure formed by connecting a plurality of spherical structures (e.g., a substantially spherical structure), and at least one metal oxide selected from a first metal oxide and a second metal oxide may be dispersed in the spherical structures of the helical structure. The helical structure of the graphene may have a size of 500 nm to 100 μm. Since graphene has a helical structure, the composite may have a rigid structure.

[0070] In one or more embodiments, the first carbonaceous material may have, for example, a cluster structure formed by aggregation of a plurality of spherical structures (e.g., substantially spherical structures), and at least one metal oxide selected from the first metal oxide and the second metal oxide may be dispersed in the spherical structures of the cluster structure. The cluster structure of the first carbonaceous material may have a size of 0.5 mm to 10 mm. Because the first carbonaceous material has a cluster structure, the composite may have a rigid structure. In some embodiments, the first carbonaceous material may be, for example, graphene. Graphene may have, for example, a cluster structure formed by aggregation of a plurality of spherical structures (e.g., substantially spherical structures), and at least one metal oxide selected from the first metal oxide and the second metal oxide may be dispersed in the spherical structures of the cluster structure. The cluster structure of graphene may have a size of 0.5 mm to 10 mm. Because graphene has a cluster structure, the composite may have a rigid structure.

[0071] In one or more embodiments, the composite may have, for example, a crumpled faceted-ball structure, and at least one metal oxide selected from the first metal oxide and the second metal oxide may be dispersed inside or on the surface of the crumpled faceted-ball structure. Because the composite has a crumpled faceted-ball structure, the composite can be easily coated on the non-substantially uniform surface irregularities of the core.

[0072] In one or more embodiments, the composite may have, for example, a planar structure, and at least one metal oxide selected from the first metal oxide and the second metal oxide may be dispersed inside or on the surface of the planar structure. Because the composite has such a two-dimensional planar structure, the composite can be easily coated on the non-substantially uniform surface irregularities of the core.

[0073] In one or more embodiments, the first carbonaceous material may extend a distance of 10 nm or less from the first metal oxide and may include at least 1 to 20 carbonaceous material layers. For example, by stacking a plurality of first carbonaceous material layers, the first carbonaceous material having a total thickness of 12 nm or less can be on (e.g., disposed on) the first metal oxide. For example, in some embodiments, the total thickness of the first carbonaceous material may be 0.6 nm to 12 nm. In some embodiments, the first carbonaceous material may be, for example, graphene. Graphene may extend a distance of 10 nm or less from the first metal oxide and may include at least 1 to 20 graphene layers. For example, by stacking a plurality of graphene layers, the graphene having a total thickness of 12 nm or less can be on (e.g., disposed on) the first metal oxide. For example, in some embodiments, the total thickness of graphene may be 0.6 nm to 12 nm.

[0074] In one or more embodiments, the shell may further include, for example, a second carbonaceous material distinct from the first carbonaceous material. For example, in one or more embodiments, the shell may further include a second carbonaceous material that is fibrous carbon having an aspect ratio of 10 or greater. Accordingly, the conduction path of the dry electrode active material can be further extended. The second carbonaceous material may form a three-dimensional conductive network among the plurality of particles of the dry electrode active material to reduce the internal resistance of the dry electrode including the dry electrode active material. Since the fibrous carbon is fixed to the dry electrode active material, a substantially uniform and stable three-dimensional conductive network can be formed among the plurality of particles of the dry electrode active material. Accordingly, since the dry electrode active material includes the second carbonaceous material, the high-rate characteristics of the lithium battery including the dry electrode active material can be improved. In contrast, in a comparative example of a simple mixture of the core and fibrous carbon as the second carbonaceous material, it is difficult to form a substantially uniform three-dimensional conductive network among the plurality of core particles due to the aggregation of the fibrous carbon. In one or more embodiments, the second carbonaceous material 23 ( Figure 2 as shown) may be disposed on the surface of the dry electrode active material 100.

[0075] Referring to Figure 2 , the dry electrode active material 100 may include a core 10 and a shell 20 that is continuous or discontinuous on (e.g., disposed on) the surface of the core 10. The shell 20 may entirely or partially cover the core 10. The shell 20 may include a first metal oxide 21, a first carbonaceous material 22, and a second carbonaceous material 23. The second carbonaceous material 23 may protrude from the surface of the dry electrode active material 100. The second carbonaceous material 23 can effectively provide a conductive network among the plurality of dry electrode active materials 100. Since the second carbonaceous material 23 is located in the matrix of the first carbonaceous material 22, the second carbonaceous material 23 can be easily coated on the core 10. The matrix of the first carbonaceous material 22 can serve as a binder for binding the core to the second carbonaceous material 23. Accordingly, in an embodiment in which the matrix of the first carbonaceous material 22 is not used, it is difficult to attach the second carbonaceous material 23 to the core 10, or the second carbonaceous material 23 may be easily detached from the core 10 during the process of manufacturing the slurry for the positive electrode. In an embodiment in which a binder is added to bind the lithium transition metal oxide core 10 and the second carbonaceous material 23, the core 10 is coated with an insulating binder, which may increase the internal resistance of the dry electrode active material 100. In an embodiment in which heat treatment is performed on the core coated with the second carbonaceous material and the binder to carbonize the binder, the core 10 and the second carbonaceous material 23 may deteriorate during the heat treatment process.

[0076] In one or more embodiments, the second carbonaceous material may have an aspect ratio of 10 or greater, or 20 or greater. In some embodiments, the aspect ratio of the second carbonaceous material may be, for example, from 10 to 100000, from 10 to 80000, from 10 to 50000, from 10 to 10000, from 10 to 5000, from 10 to 1000, from 10 to 500, from 10 to 100, or from 10 to 50. The aspect ratio of the second carbonaceous material may be, for example, the ratio of the length of the major axis passing through the center of the second carbonaceous material to the length of the minor axis (i.e., the diameter of the second carbonaceous material) passing through the center of the second carbonaceous material and perpendicular to the major axis (i.e., the diameter of the second carbonaceous material).

[0077] In one or more embodiments, the second carbonaceous material may have a diameter of, for example, 50 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. In some embodiments, the second carbonaceous material may have a diameter of, for example, from 1 nm to 50 nm, from 1 nm to 30 nm, or from 1 nm to 10 nm. In embodiments where the diameter of the second carbonaceous material is too large, the absolute number of strands per volume decreases, and the effect of reducing the internal resistance would be negligible. In comparative examples where the diameter of the second carbonaceous material is too small, substantially uniform dispersion may be difficult.

[0078] In one or more embodiments, the second carbonaceous material may have a length of, 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. In some embodiments, the second carbonaceous material may have a length of, for example, from 100 nm to 1000 μm, from 100 nm to 500 μm, from 100 nm to 100 μm, from 100 nm to 50 μm, from 100 nm to 10 μm, from 100 nm to 5 μm, from 100 nm to 2 μm, from 100 nm to 1 μm, from 100 nm to 500 nm, or from 100 nm to 300 nm. In some embodiments, the second carbonaceous material may have a length of, for example, from 500 nm to 1000 μm, from 500 nm to 500 μm, from 500 nm to 100 μm, from 500 nm to 50 μm, from 500 nm to 10 μm, from 500 nm to 5 μm, or from 500 nm to 2 μm. As the length of the second carbonaceous material increases, the internal resistance of the electrode can be reduced. In comparative examples where the length of the second carbonaceous material is too small, it is difficult to provide an effective conduction path.

[0079] In one or more embodiments, the second carbonaceous material may include, for example, carbon nanofibers, carbon nanotubes, or a combination thereof.

[0080] The carbon nanotubes may include a carbon nanotube primary structure, a carbon nanotube secondary structure formed by aggregation of a plurality of carbon nanotube primary structures, or a combination thereof.

[0081] The carbon nanotube primary structure may be a carbon nanotube unit. The carbon nanotube unit has a cylindrical-shaped graphite sheet with a nanoscale diameter and has an sp2 bonding structure. Depending on the bending angle and structure of the graphite sheet, it can exhibit the characteristics of a conductor or a semiconductor. According to the number of bonds constituting the wall, the carbon nanotube unit can be classified into a single-walled carbon nanotube (SWCNT), a double-walled carbon nanotube (DWCNT), or a multi-walled carbon nanotube (MWCNT). As the wall thickness of the carbon nanotube unit decreases, the resistance decreases.

[0082] The carbon nanotube primary structure may include, for example, single-walled carbon nanotubes (SWCNTs), double-walled carbon nanotubes (DWCNTs), multi-walled carbon nanotubes (MWCNTs), or a combination thereof. The carbon nanotube primary structure may have a diameter (e.g., average cross-sectional width or major axis) of, for example, 1 nm or greater or 2 nm or greater. The diameter of the carbon nanotube primary structure may be, for example, 20 nm or less or 10 nm or less. In some embodiments, the diameter of the carbon nanotube primary structure may be, for example, 1 nm to 20 nm, 1 nm to 15 nm, or 1 nm to 10 nm. The carbon nanotube primary structure may have a length (e.g., average longitudinal length) of, for example, 100 nm or greater or 200 nm or greater. The length of the carbon nanotube primary structure may be, for example, 2 μm or less, 1 μm or less, 500 nm or less, or 300 nm or less. In some embodiments, the length of the carbon nanotube primary structure may be, 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 by scanning electron microscope (SEM) images or transmission electron microscope (TEM) images. In some embodiments, the diameter and / or length (e.g., average value) of the carbon nanotube primary structure can be measured by laser diffraction method.

[0083] The secondary structure of carbon nanotubes is a structure formed by assembling the primary structure of carbon nanotubes to form, wholly or in part, bundle-type (or like) carbon nanotubes or rope-type (or like) carbon nanotubes. The secondary structure of carbon nanotubes may include, for example, bundle-type (or like) carbon nanotubes, rope-type (or like) carbon nanotubes, or a combination thereof. The secondary structure of carbon nanotubes may have a diameter of, for example, 2 nm or greater, or 3 nm or greater. The secondary structure of carbon nanotubes may have a diameter of, for example, 50 nm or less, 30 nm or less, 20 nm or less, or 10 nm or less. In some embodiments, the secondary structure of carbon nanotubes may have a diameter of, for example, 2 nm to 50 nm, 2 nm to 30 nm, or 2 nm to 20 nm. The secondary structure of carbon nanotubes may have a length of, for example, 500 nm or greater, 700 nm or greater, 1 μm or greater, or 10 μm or greater. The secondary structure of carbon nanotubes may have a length of, for example, 1000 μm or less, 500 μm or less, or 100 μm or less. In some embodiments, the secondary structure of carbon nanotubes may have a length of, 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 secondary structure of carbon nanotubes can be measured by scanning electron microscope (SEM) images or using an optical microscope. In some embodiments, the diameter and / or length of the secondary structure of carbon nanotubes can be measured by laser diffraction method.

[0084] The secondary structure of carbon nanotubes can be used to prepare a dry electrode active material after being converted into the primary structure of carbon nanotubes.

[0085] In one or more embodiments, based on the total weight of the first carbonaceous material and the second carbonaceous material, the amount of the second carbonaceous material can be, for example, 0.1 wt% to 50 wt%, 1 wt% to 40 wt%, or 5 wt% to 30 wt%. Since the dry electrode active material includes the first carbonaceous material and the second carbonaceous material in the amounts within the above ranges, a conductive path is formed more effectively in the dry electrode active material, thereby further reducing the internal resistance of the dry electrode active material. Thus, the cycle characteristics of a lithium battery including the dry electrode active material can be further improved. In some embodiments, based on the total weight of the dry electrode active material, the amount of the second carbonaceous material can be, 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%. Since the amount of the second carbonaceous material included in the dry electrode active material is within the above ranges, a conductive path is formed in the dry electrode active material, thereby further reducing the internal resistance of the dry electrode active material. Thus, the cycle characteristics of a lithium battery including the dry electrode active material can be further improved.

[0086] The dry electrode active material may include a core, and the core may include, for example, a lithium transition metal oxide.

[0087] In one or more embodiments, the core may include, for example, a compound selected from lithium transition metal oxides represented by Formula 1 to Formula 8.

[0088] Formula 1 Li a Ni x Co y M z O 2-b A b In 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 may be 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, and A may be fluorine (F), sulfur (S), chlorine (Cl), bromine (Br), or a combination thereof.

[0089] Formula 2 LiNi x Co y Mn z O2 Formula 3 LiNi x Co y Al z O2 In Formula 2 and Formula 3, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1.

[0090] Formula 4 LiNi x Co y Mn z Al w O2 In 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.

[0091] Formula 5 Li a Co x M y O 2-b A b In Formula 5, 1.0 ≤ a ≤ 1.2, 0 ≤ b ≤ 0.2, 0.9 ≤ x ≤ 1, 0 ≤ y ≤ 0.1, and x + y = 1, M can be 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, and A can be F, S, Cl, Br, or a combination thereof.

[0092] Formula 6 Li a Ni x Mn y M' z O 2-b A b In 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' can be cobalt (Co), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), boron (B), or a combination thereof, and A can be F, S, Cl, Br, or a combination thereof.

[0093] Formula 7 Li a M1 x M2 y PO 4-b X b In 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 can be chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof, M2 can be 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 can be O, F, S, P, or a combination thereof.

[0094] Formula 8 Lia M3 z PO4 In Formula 8, 0.90 ≤ a ≤ 1.1 and 0.9 ≤ z ≤ 1.1, and M3 can be chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof.

[0095] In one or more embodiments, the shell can include a first metal oxide and a first carbonaceous material, and the core can include, for example, a lithium transition metal oxide. The first carbonaceous material can be chemically bonded to the transition metal of the lithium transition metal oxide, for example, by a chemical bond. The carbon atoms (C) of the first carbonaceous material can be chemically bonded to the transition metal (Me) of the lithium transition metal oxide, for example, via an oxygen atom by a C-O-Me bond (e.g., a C-O-Ni bond or a C-O-Co bond). When the first carbonaceous material located in the shell is chemically bonded to the lithium transition metal oxide located in the core by a chemical bond, the core and the shell are bonded. Thus, the dry electrode active material is different from a simple physical mixture or blend of the first carbonaceous material and the lithium transition metal oxide. The first metal oxide can be chemically bonded to the first carbonaceous material by a chemical bond. In this regard, the chemical bond is, for example, a covalent bond or an ionic bond.

[0096] In one or more embodiments, the dry electrode active material can include, for example, a first dry electrode active material and a second dry electrode active material. The first dry electrode active material and the second dry electrode active material can have different particle sizes.

[0097] The first dry electrode active material can be, for example, a large-diameter dry electrode active material having a particle size larger than that of the second dry electrode active material. The second dry electrode active material can be, for example, a small-diameter dry electrode active material having a particle size smaller than that of the first dry electrode active material. For example, in one or more embodiments, the first dry electrode active material can be a large-diameter dry electrode active material, and the second dry electrode active material can be a small-diameter dry electrode active material. For example, the second dry electrode active material having an average particle size smaller than the average particle size of the first dry electrode active material can be disposed in the pores between the particles of the first dry electrode active material. By disposing the particles of the second dry electrode active material having a small diameter in the pores between the particles of the first dry electrode active material having a large diameter, the ionic conductivity and the electronic conductivity of the dry electrode including the dry electrode active material can be improved (e.g., simultaneously). In some embodiments, the dry electrode including the dry electrode active material can have a higher energy density. Accordingly, the lithium battery including the dry electrode active material can have a higher energy density and improved cycle characteristics.

[0098] For example, in one or more embodiments, the first dry electrode active material and the second dry electrode active material may have a bimodal particle size distribution in a particle size distribution graph. For example, in one or more embodiments, the composite positive electrode active material (e.g., dry electrode active material) may have a bimodal particle size distribution having two peaks in a particle size distribution graph obtained by using a particle size analyzer (PSA) or the like. The bimodal particle size distribution may have a first peak corresponding to the first dry electrode active material and a second peak corresponding to the second dry electrode active material.

[0099] The particle size ratio of the first dry electrode active material to the second dry electrode active material may be, for example, from 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. Since the particle size ratio of the first dry electrode active material to the second dry electrode active material is within the above range, the lithium battery including the composite positive electrode active material may have a higher energy density and improved cycle characteristics.

[0100] In one or more embodiments, the particle size of the first dry electrode active material may be, for example, greater than 8 μm and at most 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 may be, for example, the median particle size (D50). The particle size of the second dry electrode active material may be, for example, at least 1 μm and 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 second dry electrode active material may be, for example, the median particle size (D50). Since the first dry electrode active material and the second dry electrode active material have average particle sizes within the above range, the energy density and / or cycle characteristics of the 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 can be measured by using a measuring device of laser diffraction method or dynamic light scattering method. In some embodiments, the particle size is measured by using, for example, a laser scattering particle size distribution analyzer (e.g., LA-920 from Horiba Instruments), and may be the median particle size (D50) value at 50% of the total cumulative particle size distribution of particles from the minimum particle size to the maximum particle size. In some embodiments, the particle sizes of the first dry electrode active material and the second dry electrode active material can be measured by scanning electron microscope (SEM) images or by using an optical microscope.

[0101] The weight ratio of the first dry electrode active material to the second dry electrode active material can be, for example, from 90:10 to 60:40, from 85:15 to 65:35, from 80:20 to 65:35, or from 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 the above range, the energy density and / or cycle characteristics of the lithium battery including the composite positive electrode active material can be further improved.

[0102] The dry electrode film can include a dry binder. The dry binder can be, for example, a binder that is not impregnated with the process solvent, does not dissolve in the process solvent, or does not disperse in the process solvent during the process of manufacturing the dry electrode film. The dry binder can be, for example, a binder that does not include the process solvent or does not come into contact with the process solvent during the process of manufacturing the dry electrode film. In some embodiments, the dry binder can be, for example, a fibrillated binder or a fibrous binder. The fibrillated binder or the fibrous binder can be used as a matrix for supporting and binding the electrode active material and other components included in the electrode active material layer. Based on the SEM image of its cross-section, it can be confirmed that the fibrillated binder or the fibrous binder has a fibrous form. The fibrillated binder or the fibrous binder has an aspect ratio of, for example, 10 or greater, 20 or greater, 50 or greater, or 100 or greater.

[0103] Examples of the dry binder can include polytetrafluoroethylene (PTFE), poly(vinylidene fluoride - hexafluoropropylene) (PVDF - HFP) copolymer, poly(vinylidene 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 / or their copolymers, but the embodiments of the present disclosure are not limited thereto, and any binder used in the manufacture of the dry electrode can also be used. For example, in some embodiments, the dry binder can include a fluorine - based binder. The fluorine - based binder can be, for example, polytetrafluoroethylene (PTFE), poly(vinylidene fluoride - hexafluoropropylene) (PVDF - HFP) copolymer, and / or poly(vinylidene fluoride) (PVDF).

[0104] In one or more embodiments, the dry binder can have a glass transition temperature (T g ), for example, of - 30°C to 150°C, 15°C to 150°C, 15°C to 130°C, 15°C to 100°C, 50°C to 130°C, 100°C to 130°C, or 120°C to 130°C. In some embodiments, the dry binder can have a glass transition temperature (T g). The glass transition temperature of polytetrafluoroethylene (PTFE) is, for example, 120°C to 130°C. Since the dry binder has a glass transition temperature within the above range, fibrillated or fibrous binders can be more easily obtained during the process of manufacturing the dry electrode.

[0105] Based on the total weight of the dry electrode film, the amount of the dry binder is, for example, 0.1 wt% to 5 wt%, 0.5 wt% to 5 wt%, or 1 wt% to 5 wt%. Since the amount of the dry binder included in the dry electrode film is within the above range, the binding force of the dry electrode film can be improved, and the high energy density of the dry electrode film can be maintained.

[0106] In one or more embodiments, the dry electrode film may further include, for example, a conductive material. The conductive material may be, for example, a dry conductive material. The dry conductive material may be, for example, a conductive material that is not impregnated with the process solvent, does not dissolve in the process solvent, or is not dispersed in the process solvent during the process of manufacturing the dry electrode film. The dry conductive material may be, for example, a conductive material that does not include the process solvent or does not come into contact with the process solvent during the process of manufacturing the dry electrode film. In some embodiments, the dry conductive material may include, for example, carbon-based conductive materials. The carbon-based conductive materials may include, for example, fibrous carbon-based materials having an aspect ratio of 10 or greater, particulate carbon-based materials having an aspect ratio of less than 10, or a combination thereof.

[0107] The fibrous carbon-based materials having an aspect ratio of 10 or greater may be, for example, carbon fibers, carbon nanotubes, and / or carbon nanoribbons, but the embodiments of the present disclosure are not limited thereto, and any material that can be used as a carbon-based conductive material in the art may also be used. In one or more embodiments, the fibrous carbon-based materials having an aspect ratio of 10 or greater may include at least one of the above-mentioned second carbon-based materials. The fibrous carbon-based conductive material is different from the second carbon-based material constituting the dry electrode active material in terms of simply mixing with the dry electrode active material.

[0108] Examples of the particulate carbon-based materials having an aspect ratio of less than 10 may include carbon black, acetylene black, Ketjen black, natural graphite, and / or artificial graphite, but the embodiments of the present disclosure are not limited thereto, and any carbon-based conductive material that is generally available in the art may also be used. The aspect ratio of the particulate carbon-based materials is, for example, 1 to 7, 1 to 5, 1 to 3, or 1 to 2.

[0109] Based on the total weight of the dry electrode film, the amount of the dry conductive material included in the dry electrode film may be, for example, 0.1 wt% to 5 wt%, 0.5 wt% to 5 wt%, or 1 wt% to 5 wt%. Since the amount of the dry conductive material included in the dry electrode film is within the above range, the dry electrode film may have improved conductivity, and the lithium battery including the dry electrode film may have improved cycle characteristics.

[0110] In one or more embodiments, the dry electrode film can be, for example, a free-standing film. For example, the dry electrode film can have a film shape without using a support. Thus, the dry electrode film can be disposed on the electrode current collector after being prepared as a separate free-standing film. The dry electrode film prepared by a dry process does not include intentionally added process solvents. For example, the dry electrode film does not include residual process solvents. Although trace (minute) amounts of unintended solvents may remain in the dry electrode film, the solvents are not the process solvents intentionally added thereto. Thus, the dry electrode film is distinguished from the wet electrode film, which is prepared by mixing components with a process solvent, drying the mixture, and removing all or part of the process solvent.

[0111] In one or more embodiments, the dry electrode film can have a tensile strength of, for example, 500 kPa or greater, 700 kPa or greater, or 1000 kPa or greater at 25°C. In some embodiments, the dry electrode film can have a tensile strength of, for example, 500 kPa to 5000 kPa, 700 kPa to 5000 kPa, or 1000 kPa to 5000 kPa at 25°C. When the tensile strength is within the above ranges, the structural stability of the dry electrode film can be improved. Thus, the reversibility of the electrode reaction can be improved because the three-dimensional conductive network of the dry electrode film is maintained during the charge and discharge processes. Due to this high tensile strength of the dry electrode film, the mechanical strength of the dry electrode film can be improved. Due to the improved mechanical strength of the dry electrode film, local deterioration caused by volume changes of the electrode including the dry electrode film and the lithium battery including the electrode can be suppressed during charge and discharge. Thereby, the cycle characteristics of the lithium battery can be improved.

[0112] According to one or more embodiments of the present disclosure, the dry electrode can include an electrode current collector and the above-described dry electrode film disposed on one or both sides (e.g., opposite sides) (e.g., on at least one side of the electrode current collector).

[0113] By including the dry electrode film, the dry electrode has a reduced internal resistance and improved mechanical properties.

[0114] The electrode current collector can include, for example, a substrate.

[0115] The material constituting the substrate can be any material that does not react with lithium, i.e., any conductive material that does not form an alloy or compound with lithium. The substrate can be formed of, for example, a metal or an alloy. In one or more embodiments, the substrate can be formed of, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), or an alloy thereof. For example, in one or more embodiments, the substrate can be in the form selected from a foil, a film, a plate, a porous structure, a mesoporous structure, a structure with through holes, a polygonal ring, a net, a foam, and a nonwoven structure, but the embodiments of the present disclosure are not limited thereto, and the substrate can be in any form commonly available in the art.

[0116] In one or more embodiments, the electrode current collector can include, for example, a substrate and an intermediate layer between the substrate and the dry electrode film. The intermediate layer can include, for example, a carbonaceous conductive material.

[0117] For example, in some embodiments, the intermediate layer can be directly disposed on one or both sides (e.g., opposite sides) of the substrate. Thus, another layer may not be provided between the substrate and the intermediate layer. By directly disposing the intermediate layer on one or both sides (e.g., opposite sides) of the substrate, the bonding force between the substrate and the dry electrode film can be further improved.

[0118] The thickness of the intermediate layer can be, 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. In some embodiments, the thickness of the intermediate layer can be, 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 thickness of the intermediate layer is within the above range, the bonding force between the substrate and the dry electrode film is further improved, and an increase in the interfacial resistance is suppressed.

[0119] The intermediate layer includes, for example, a carbonaceous conductive material. The carbonaceous conductive material included in the intermediate layer can be selected from the carbonaceous conductive materials used in the dry electrode film. The intermediate layer can include the same carbonaceous conductive material as the carbonaceous conductive material used in the dry electrode film. Since the intermediate layer includes a carbonaceous conductive material, the intermediate layer can be, for example, a conductive layer.

[0120] In one or more embodiments, the intermediate layer may further include, for example, a binder. Since the intermediate layer further includes a binder, the bonding force between the substrate and the dry electrode film can be further improved. The binder included in the intermediate layer may be, for example, a conductive binder and / or a non-conductive binder. The conductive binder may be, for example, an ion-conductive binder and / or an electron-conductive binder. A binder having (e.g., having both) both ion conductivity and electron conductivity may belong to the ion-conductive binder and the electron-conductive binder.

[0121] In one or more embodiments, the binder included in the intermediate layer may be selected from the binders used in the dry electrode film. In some embodiments, the intermediate layer may include the same binder as the binder used in the dry electrode film. The binder included in the intermediate layer may be, for example, a fluorine-based binder. The fluorine-based binder included in the intermediate layer may be, for example, polyvinylidene fluoride (PVDF). In some embodiments, the intermediate layer may be, for example, an adhesive layer including a binder. In some embodiments, the intermediate layer may be a conductive layer including, for example, a binder and a carbon-based conductive material.

[0122] The intermediate layer may be provided on the substrate by, for example, a dry method or a wet method. In some embodiments, the intermediate layer may be provided on the substrate by a dry method such as chemical vapor deposition (CVD) or physical vapor deposition (PVD). In some embodiments, the intermediate layer may be provided on the substrate by a wet method such as spin coating or dip coating. The intermediate layer may be provided on the substrate by depositing a carbon-based conductive material on the substrate. The dry-coated intermediate layer is formed of a carbon-based conductive material and may not include (e.g., may exclude) any binder. In some embodiments, for example, the intermediate layer may be provided on the substrate by coating a composition including a carbon-based conductive material, a binder, and a solvent on the surface of the substrate and drying the coated composition. The intermediate layer may have a single-layer structure or a multi-layer structure. The multi-layer structure may be a double-layer structure, a triple-layer structure, or a four-layer structure.

[0123] In one or more embodiments, the electrode current collector may include, for example, a substrate film and a metal layer on one or both (e.g., opposite) sides of the substrate film (e.g., disposed on). In some embodiments, the electrode current collector may include a substrate, and the substrate may have a structure including a substrate film and a metal layer on one or both (e.g., opposite) sides of the substrate film (e.g., disposed on). The substrate film may include, for example, a polymer. The polymer may be, 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. Since the substrate film includes a thermoplastic polymer, in the case of a short circuit, the substrate film melts, thereby suppressing a rapid increase in current. In some embodiments, the substrate film may 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 is cut off due to overcurrent, thereby preventing or reducing a short circuit. By controlling the thickness of the metal layer, the limiting current and the maximum current can be adjusted. The metal layer may be plated or deposited on the substrate film. As the thickness of the metal layer decreases, the limiting current and / or the maximum current of the electrode current collector decreases, so that the stability of the lithium battery can be improved in the case of a short circuit. In some embodiments, a lead tab may be added to the metal layer for external connection. The lead tab may be welded to the metal layer or the metal layer / substrate film stack structure by ultrasonic welding, laser welding, spot welding, etc. When the substrate film and / or the metal layer melts during welding, the metal layer can be electrically connected to the lead tab. In some embodiments, a metal sheet may be further added between the metal layer and the lead tab for stronger welding between the metal layer and the lead tab. The metal sheet may be a sheet of the same material as the metal of the metal layer. The metal sheet may be, for example, a metal foil and a metal mesh. The metal sheet may be, for example, an aluminum foil, a copper foil, and a SUS foil. By disposing the metal sheet on the metal layer and performing welding, the lead tab can be welded to the metal sheet / metal layer stack structure or the metal sheet / metal layer / substrate film stack structure. When the substrate film, the metal layer, and / or the metal sheet melts during welding, the metal layer or the metal layer / metal sheet stack structure can be electrically connected to the lead tab. In some embodiments, a metal sheet and / or a lead tab may be further added to a part of the metal layer. In one or more embodiments, the substrate film may have a thickness of, for example, 1 μm to 50 μm, 1.5 μm to 50 μm, 1.5 μm to 40 μm, or 1 to 30 μm. When the thickness of the substrate film is within the above range, the weight of the electrode assembly can be reduced more effectively. The melting point of the substrate film may be, for example, 100 °C to 300 °C, 100 °C to 250 °C, or 100 °C to 200 °C.Because the base film has a melting point within the above range, the base film melts during the process of welding the lead tab, so as to be easily bonded to the lead tab. In some embodiments, in order to improve the adhesion between the base film and the metal layer, surface treatment such as corona treatment may be performed on the base film. In one or more embodiments, the thickness of the metal layer may be, for example, 0.01 μm to 3 μm, 0.1 μm to 3 μm, 0.1 μm to 2 μm, or 0.1 μm to 1 μm. When the thickness of the metal layer is within the above range, the stability of the electrode assembly can be obtained while maintaining the conductivity of the electrode assembly. In one or more embodiments, the thickness of the metal sheet may be, for example, 2 μm to 10 μm, 2 μm to 7 μm, or 4 μm to 6 μm. When the thickness of the metal sheet is within the above range, the metal layer can be more easily connected to the lead tab. Because the electrode current collector has the above structure, the weight of the electrode can be reduced, so that the energy density of the lithium battery can be increased. The electrode current collector may be, for example, a positive electrode current collector. The electrode current collector may be, for example, a negative electrode current collector.

[0124] The dry electrode film included in the dry electrode corresponds to the electrode active material layer.

[0125] In an embodiment where the electrode active material layer (i.e., the dry electrode film) of the dry electrode is measured by using a surface and interface cutting analysis system (SAICAS), the vertical relative force (F VR ) change rate with respect to the depth between the first point and the second point is, for example, 300% or less. The first point is 5% of the total thickness of the electrode active material layer away from the surface of the electrode active material layer in the direction towards the electrode current collector, and the second point is 5% of the total thickness of the electrode active material layer away from the surface of the electrode current collector. In some embodiments, the vertical relative force change rate may be, for example, 10% to 300%, 10% to 250%, 10% to 200%, 10% to 150%, or 10% to 100%. The second point that is 5% of the total thickness of the electrode active material layer away from the surface of the electrode current collector in the direction towards the electrode active material layer corresponds to the point that is 95% of the total thickness of the electrode active material layer away from the surface of the electrode active material layer in the direction towards the electrode current collector. The vertical relative force change rate is calculated by Equation 1. The measurement method using SAICAS is described in Evaluation Example 11.

[0126] Equation 1 Vertical relative force (F VR ) change rate (%) = [(maximum value of vertical relative force (F VR2 ) - minimum value of vertical relative force (F VR1 ) ) / minimum value of vertical relative force (F VR1 ) ] × 100 In the embodiment of measuring the electrode active material layer of the dry electrode by SAICAS, since the vertical relative force change rate is 300% or less, the distribution uniformity of the components in the electrode can be improved. In addition, since side reactions and an increase in internal resistance caused by the non-uniform distribution of the components of the electrode active material layer are suppressed, the reversibility of the electrode reaction can be improved. In the embodiment of the electrode with a high loading amount, the cycle characteristics of the lithium battery can be improved.

[0127] In the embodiment of measuring the electrode active material layer of the dry electrode by using SAICAS, the second horizontal force (F H2 ) at the second point and the first horizontal force (F H1 ) at the first point can have a horizontal force ratio of, for example, 50% or more. The second point is 10% of the total thickness from the electrode active material layer to the electrode current collector surface in the direction toward the electrode active material layer (e.g., in the depth direction), and the first point is 10% of the total thickness from the electrode active material layer to the electrode current collector surface in the direction toward the electrode current collector. In some embodiments, the horizontal force ratio can be, for example, 50% to 100%, 60% to 100%, 70% to 100%, 80% to 100%, or 90% to 100%. The second point, which is 10% of the total thickness of the electrode active material layer from the surface of the electrode current collector in the direction toward the electrode active material layer, corresponds to the point that is 90% of the total thickness of the electrode active material layer from the surface of the electrode active material layer in the direction toward the electrode current collector. The horizontal force ratio is represented by, for example, Equation 2. The measurement method using SAICAS is described in Evaluation Example 12.

[0128] Equation 2 Horizontal force ratio (%) = [Second horizontal force (F H2 ) / First horizontal force (F H1 )] × 100 In the embodiment of measuring the electrode active material layer of the dry electrode by using SAICAS, since the horizontal force ratio is 50% or more, the distribution uniformity of the components in the electrode can be further improved. Since the dry electrode has a horizontal force ratio within the above range, the cycle characteristics of the lithium battery including the dry electrode can be further improved.

[0129] In one or more embodiments, the dry electrode can be, for example, a dry positive electrode. The dry positive electrode can include a dry positive electrode film, and the dry positive electrode film can include a dry positive electrode active material having the above core / shell structure.

[0130] The dry positive electrode active material having the above core / shell structure can include a lithium transition metal oxide in the core and a first metal oxide and a first carbonaceous material in the shell.

[0131] In one or more embodiments, in addition to the dry positive electrode active material including the above core / shell structure, the dry positive electrode active material may further include a suitable ordinary dry positive electrode active material. Any suitable dry positive electrode active material that is commonly available in the art can be used without limitation.

[0132] For example, in one or more embodiments, the dry positive electrode active material may include at least one composite oxide of lithium and a metal selected from cobalt, manganese, nickel, and combinations thereof, and non-limiting examples thereof may be compounds represented by one of the following formulas: Li a A 1-b B' b D2 (where 0.90 ≤ a ≤ 1 and 0 ≤ b ≤ 0.5); Li a E 1-b B' b O 2-c D c (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE 2-b B' b O 4-c D c (where 0 ≤ b ≤ 0.5 and 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b B' c D α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni 1-b-c Co b B' c O 2-α F' α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Co b B' c O 2-α F'2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b B' c D α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α ≤ 2); Li a Ni 1-b-c Mn b B' c O2-α F' α (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni 1-b-c Mn b B' c O 2-α F'2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, 0 ≤ c ≤ 0.05, and 0 < α < 2); Li a Ni b E c G d O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, and 0.001 ≤ d ≤ 0.1); Li a Ni b Co c Mn d G e O2 (where 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.9, 0 ≤ c ≤ 0.5, 0 ≤ d ≤ 0.5, and 0.001 ≤ e ≤ 0.1); Li a NiG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a CoG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a MnG b O2 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); Li a Mn2G b O4 (where 0.90 ≤ a ≤ 1 and 0.001 ≤ b ≤ 0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiI'O2; LiNiVO4; Li (3-f) J2(PO4)3 (where 0 ≤ f ≤ 2); Li (3-f) Fe2(PO4)3 (where 0 ≤ f ≤ 2); and LiFePO4.

[0133] In the formula representing the above compound, A can be Ni, Co, Mn, or a combination thereof; B' can be Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, or a combination thereof; D can be O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F' can be F, S, P, or a combination thereof; G can be Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q can be Ti, Mo, Mn, or a combination thereof; I' can be Cr, V, Fe, Sc, Y, or a combination thereof; and J can be V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0134] In one or more embodiments, the above compound having a coating on its surface can be utilized, or a mixture of the above compound and a compound having a coating can also be utilized. The coating added to the surface of the compound can include, for example, compounds of coating elements, such as oxides, hydroxides, hydroxyoxides, oxocarbonates, or hydroxycarbonates of coating elements. The compound constituting the coating can be amorphous or crystalline. The coating elements included in the coating can be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or any mixture thereof. The method of forming the coating can be selected from methods that do not adversely affect the physical properties of the positive electrode active material. The coating method can be, for example, spraying and dip coating. These coating methods are obvious to those of ordinary skill in the art, and thus their detailed descriptions will not be given.

[0135] In one or more embodiments, the dry electrode can be, for example, a dry negative electrode. The dry negative electrode can include a dry negative electrode film, and the dry negative electrode film can include a dry negative electrode active material.

[0136] The dry negative electrode active material can be any negative electrode active material of a lithium battery commonly used in the art. For example, it may include at least one selected from lithium metal, a metal alloyable with lithium, transition metal oxides, non-transition metal oxides, and carbonaceous materials. For example, the metal alloyable with lithium may be silicon (Si), tin (Sn), aluminum (Al), germanium (Ge), lead (Pb), bismuth (Bi), antimony (Sb), Si-X alloy (where X is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or a combination thereof, excluding Si), Sn-X alloy (where X is an alkali metal, alkaline earth metal, Group 13 element, Group 14 element, transition metal, rare earth element, or a combination thereof, excluding Sn), etc. The element X may be, for example, magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), radium (Ra), scandium (Sc), yttrium (Y), titanium (Ti), zirconium (Zr), hafnium (Hf), rutherfordium (Rf), vanadium (V), niobium (Nb), tantalum (Ta), (Db), chromium (Cr), molybdenum (Mo), tungsten (W), (Sg), technetium (Tc), rhenium (Re), (Bh), iron (Fe), lead (Pb), ruthenium (Ru), osmium (Os), (Hs), rhodium (Rh), iridium (Ir), palladium (Pd), platinum (Pt), copper (Cu), silver (Ag), gold (Au), zinc (Zn), cadmium (Cd), boron (B), aluminum (Al), gallium (Ga), tin (Sn), indium (In), titanium (Ti), germanium (Ge), phosphorus (P), arsenic (As), antimony (Sb), bismuth (Bi), sulfur (S), selenium (Se), tellurium (Te), polonium (Po), or a combination thereof. For example, the transition metal oxide may be lithium titanium oxide, vanadium oxide, lithium vanadium oxide, etc. The non-transition metal oxide may be, for example, SnO2 and SiO x (where 0 < x < 2). The carbonaceous material may be, for example, crystalline carbon, amorphous carbon, or any mixture thereof. The crystalline carbon may be, for example, graphite, such as natural graphite or artificial graphite in an amorphous, plate-like, flake-like, spherical (e.g., substantially spherical), or fibrous form. The amorphous carbon may be, for example, soft carbon (carbon calcined at a low temperature) or hard carbon, mesophase pitch carbide, and / or calcined coke.

[0137] According to one or more embodiments, a lithium battery may include a first electrode, a second electrode, and an electrolyte between the first electrode and the second electrode, wherein the first electrode, the second electrode, or a combination thereof is the above dry electrode.

[0138] Since the lithium battery includes a dry electrode having a reduced internal resistance and improved mechanical properties, the cycle characteristics of the lithium battery are improved.

[0139] In one or more embodiments, a lithium battery may include, for example, a dry positive electrode, a dry negative electrode, or (e.g., simultaneously) both a dry positive electrode and a dry negative electrode. In some embodiments, a lithium battery may include, for example, a dry positive electrode and a wet negative electrode, or a wet positive electrode and a dry negative electrode.

[0140] In one or more embodiments, a lithium battery may include an electrolyte, and the electrolyte may be, for example, a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

[0141] The liquid electrolyte may be, for example, an organic electrolyte solution. The organic electrolyte solution may be prepared, for example, by dissolving a lithium salt in an organic solvent.

[0142] Any organic solvent commonly used in the art may be used. Non-limiting examples of the organic solvent may include propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, ethyl methyl 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 any mixture thereof.

[0143] The lithium salt may be any lithium salt commonly used in the art. For example, in some embodiments, the lithium salt may be LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (where x and y are natural numbers), LiCl, LiI, or any mixture thereof.

[0144] 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.

[0145] The solid electrolyte may include, for example, an oxide-based solid electrolyte, a sulfide-based solid electrolyte, a polymer solid electrolyte, or a combination thereof.

[0146] For example, in some embodiments, the solid electrolyte may be boron oxide, lithium oxynitride, etc. However, the solid electrolyte is not limited thereto, and any suitable solid electrolyte may be used. The solid electrolyte may be formed on the negative electrode by sputtering or the like, or a separate solid electrolyte sheet may be laminated on the negative electrode.

[0147] Non-limiting examples of oxide-based solid electrolytes may include Li 1+x+y Al x Ti 2-x Si y P 3-y O 12 (where 0 < x < 2 and 0 ≤ y < 3), BaTiO3, Pb(Zr,Ti)O3 (PZT), Pb 1-x La x Zr 1-y Ti y O3 (PLZT, where 0 ≤ x < 1 and 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 (where 0 < x < 2 and 0 < y < 3), Li x Al y Ti z (PO4)3 (where 0 < x < 2, 0 < y < 1 and 0 < z < 3), Li 1+x+y (Al, Ga) x (Ti, Ge) 2-x Si y P 3-y O 12 (where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1), Li x La y TiO3 (where 0 < x < 2 and 0 < y < 3), Li2O, LiOH, Li2CO3, LiAlO2, Li2O - Al2O3 - SiO2 - P2O5 - TiO2 - GeO2, Li 3+x La3M2O 12 (where M = Te, Nb or Zr and 0 ≤ x ≤ 10), Li 3+x La3Zr 2-y M y O 12(M-doped LLZO, M = Ga, W, Nb, Ta, Al or their combination, 0 ≤ x ≤ 10 and 0 <y<2)、Li7La3Zr 2-x Ta x O 12 (where 0 <x<2,LLZ-Ta)或它们的组合。在一些实施例中,氧化物类固体电解质可以是例如石榴石型(或类)固体电解质。氧化物类固体电解质可以通过烧结方法等制造。

[0148] In some embodiments, the oxide-based solid electrolyte may include, for example, Li7La3Zr2O 12 LLZO, Li 6.5 Ln3Z 1.5 Ta 0.5 O 12 , Li 1.3 Al 0.3 Ti 1.7 (PO4)3、Li 0.34 La 0.51 TiO 2.94 , Li 1.07 Al 0.69 Ti 1.46 (PO4)3, 50Li4SiO4-50Li2BO3, 90Li3BO3-10Li2SO4, Li 2.9 PO 3.3 N 0.46 or a combination thereof.

[0149] Sulfide-based solid electrolytes may include, for example, selected from Li2S-P2S5, Li2S-P2S5-LiX (wherein X is a halogen), Li2S-P2S5-Li2O, Li2S-P2S5-Li2O-LiI, Li2S-SiS2, Li2S-SiS2-LiI, Li2S-SiS2-LiBr, Li2S-SiS2-LiCl, Li2S-SiS2-B2S3-LiI, Li2S-SiS2-P2S5-LiI, Li2S-B2S3, Li2S-P2S5-Z m S n (where m and n are positive numbers and Z is Ge, Zn or Ga), Li2S-GeS2, Li2S-SiS2-Li3PO4, Li2S-SiS2-Li p MO q (where p and q are positive numbers and M is P, Si, Ge, B, Al, Ga or In), Li 7-x PS 6-x Cl x (where 0≤x≤2), Li7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x at least one of (where 0 ≤ x ≤ 2). The sulfide-based solid electrolyte can be prepared by treating starting materials such as Li2S and P2S5 via melt quenching or mechanical grinding. In some embodiments, heat treatment can be performed after such treatment. The sulfide-based solid electrolyte can be in an amorphous form, a crystalline form, or a mixed form thereof.

[0150] In one or more embodiments, the sulfide-based solid electrolyte can include, for example, a thiogermanate-type (or analogous) solid electrolyte represented by Formula 9.

[0151] Formula 9 Li + 12-n-x A n+ X 2- 6-x Y - x In Formula 9, A can be P, As, Ge, Ga, Sb, Si, Sn, Al, In, Ti, V, Nb, or Ta, X can be S, Se, or Te, and Y can be Cl, Br, I, F, CN, OCN, SCN, or N3, where 1 ≤ n ≤ 5 and 0 ≤ x ≤ 2.

[0152] In some embodiments, the sulfide-based solid electrolyte can be a thiogermanate-type (or analogous) compound including at least one selected from Li 7-x PS 6-x Cl x (where 0 ≤ x ≤ 2), Li 7-x PS 6-x Br x (where 0 ≤ x ≤ 2) and Li 7-x PS 6-x I x (where 0 ≤ x ≤ 2). In some embodiments, the sulfide-based solid electrolyte included in the solid electrolyte can be a thiogermanate-type (or analogous) compound including at least one selected from Li6PS5Cl, Li6PS5Br, and Li6PS5I.

[0153] The polymer solid electrolyte can include, for example, a solid electrolyte including an ion-conductive polymer and a lithium salt, a solid electrolyte including an ionic liquid polymer and a lithium salt, or a combination thereof.

[0154] The ion-conductive polymer can be a polymer including ion-conductive repeating units at the main chain or side chain. The ion-conductive repeating unit as the unit having ion conductivity can be, for example, an alkylene oxide unit or a hydrophilic unit. In some embodiments, the ion-conductive polymer can include, for example, an ether monomer (e.g., ether unit), an acrylate monomer (e.g., acrylate unit), a methacrylate monomer (e.g., methacrylate unit), a siloxane monomer (e.g., siloxane unit), or a combination thereof as the ion-conductive repeating unit. In some embodiments, the ion-conductive polymer can be, for example, polyethylene oxide, polypropylene oxide, polymethyl methacrylate, polyethyl methacrylate, polydimethylsiloxane, polyacrylic acid, polymethacrylic acid, poly(methyl acrylate), poly(ethyl acrylate), poly(2-ethylhexyl acrylate), poly(butyl methacrylate), poly(2-ethylhexyl methacrylate), poly(decyl acrylate), poly(vinyl acetate), or a combination thereof. In some embodiments, the ion-conductive polymer can be, for example, polyethylene oxide (PEO), polyvinyl alcohol (PVA), polyvinylpyrrolidone (PVP), polyvinyl sulfone, or a combination thereof.

[0155] The polymer ionic liquid (PIL) can include, for example, repeating units containing: i) at least one cation selected from ammonium, pyrrolidinium, pyridinium, pyrimidinium, imidazolium, piperidinium, pyrazolium, oxazolium, pyridazinium, phosphonium, sulfonium, triazole, and any mixture thereof; and ii) at least one anion selected from BF4-, PF6-, AsF6-, SbF6-, AlCl4-, HSO4-, ClO4-, CH3SO3-, CF3CO2-, (CF3SO2)2N-, Cl-, Br-, I-, SO4-, CF3SO3-, (C2F5SO2)2N-, (C2F5SO2)(CF3SO2)N-, NO3-, Al2Cl7-, CH3COO-, (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-. In some embodiments, the polymer ionic liquid can be, for example, poly(diallyldimethylammonium) trifluoromethanesulfonimide (poly(diallyldimethylammonium) TFSI), poly(1-allyl-3-methylimidazolium trifluoromethanesulfonimide), poly(N-methyl-N-propylpiperidinium bis(trifluoromethylsulfonyl)imide), or a combination thereof.

[0156] In one or more embodiments, the lithium salt can be, for example, LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiCF3SO3, Li(CF3SO2)2N, LiC4F9SO3, LiAlO2, LiAlCl4, LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2) (where 1 ≤ x ≤ 20 and 1 ≤ y ≤ 20), LiCl, LiI, or a combination thereof.

[0157] According to one or more embodiments, a method of manufacturing a dry electrode is provided.

[0158] The method of manufacturing a dry electrode may include the steps of: providing a dry electrode film; and disposing / placing the dry electrode film on one or both sides (e.g., opposite sides) of an electrode current collector.

[0159] The step of providing a dry electrode film may include: preparing a dry mixture by dry-mixing a dry electrode active material, a dry conductive material, and a dry binder; and preparing a dry electrode film by molding the dry mixture.

[0160] First, the electrode active material, the dry conductive material, and the dry binder are dry-mixed to prepare a dry mixture. For example, the dry electrode active material, the dry conductive material, and the dry binder are dry-mixed to prepare a dry mixture.

[0161] Dry-mixing refers to mixing in a state without including a process solvent. The process solvent can be, for example, a solvent used in the art for preparing an electrode paste. The process solvent can be, for example, water and N-methylpyrrolidone (NMP), but the embodiments of the present disclosure are not limited thereto, and any process solvent commonly used for preparing an electrode paste can be utilized. Dry-mixing can be performed, for example, using a stirrer at a temperature of 15°C to 65°C at a rotation speed of 10 rpm to 10000 rpm. Dry-mixing can be performed, for example, using a stirrer for 1 minute to 200 minutes.

[0162] Dry-mixing can be performed, for example, one or more times. First, the dry electrode active material, the dry conductive material, and the dry binder are initially dry-mixed to prepare a first dry mixture. The initial dry-mixing can be performed, for example, at a temperature of 25°C to 65°C at a rotation speed of 10 rpm to 2000 rpm for 15 minutes or less. Subsequently, the first dry mixture can be further dry-mixed to prepare a second dry mixture. The secondary dry-mixing can be performed, for example, at a temperature of 25°C to 65°C at a rotation speed of 3000 rpm to 9000 rpm for 10 minutes to 60 minutes. Through the secondary dry-mixing, a dry mixture including a fibrillated dry binder can be obtained.

[0163] The agitator can be, for example, a kneader. The agitator can include, for example: a chamber; at least one rotating shaft disposed / placed in the chamber and rotating; and blades rotatably coupled to the rotating shaft and arranged along the longitudinal direction of the rotating shaft. The blades can include, for example, at least one selected from the group consisting of ribbon blades, sigma blades, Z blades, dispersion blades, and helical blades. Since the agitator includes blades, the electrode active material, the dry conductive material, and the dry binder can be effectively mixed without using a solvent to prepare a dough-like mixture.

[0164] The dry binder can be, for example, a vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene (PTFE), a mixture thereof, or a styrene-butadiene rubber polymer. The dry binder can be selected from the dry binders used in the above dry electrode membranes.

[0165] The dry conductive material can be, but is not limited to: carbon black; graphite particles; natural graphite; artificial graphite; acetylene black; Ketjen black; carbon fibers; carbon nanotubes; metals such as copper, nickel, aluminum, and silver, each used in the form of powder, fiber, or tube; or conductive polymers such as polyphenylene derivatives, and any material commonly used as a conductive material in the art can also be used. In some embodiments, 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 above dry electrode membranes.

[0166] In one or more embodiments, a plasticizer or a pore former can be further added to the dry mixture to form pores inside the electrode plate (e.g., the dry electrode membrane).

[0167] The amounts of the dry electrode active material, the dry binder, and the dry conductive material used in the dry electrode membrane are at levels commonly used in lithium batteries.

[0168] In the dry positive electrode membrane, the dry positive electrode active material can be used as the dry electrode active material. For the description of the dry positive electrode active material, refer to the above dry electrode membrane. In the dry negative electrode membrane, the dry negative electrode active material can be used as the dry electrode active material. For the description of the dry negative electrode active material, refer to the above dry electrode membrane.

[0169] Subsequently, the dry mixture is molded to prepare a dry electrode membrane.

[0170] The prepared dry mixture can be extruded into a sheet or film form by using an extrusion device. The pressure during extrusion can be, for example, 4 MPa to 100 MPa.

[0171] Subsequently, an electrode current collector with an intermediate layer disposed on one or both sides (e.g., opposite sides) of the substrate is provided.

[0172] The step of providing an electrode current collector with an intermediate layer disposed on one or both sides (e.g., opposite sides) of a substrate may include, for example: providing a substrate; and disposing the intermediate layer on one or both sides (e.g., opposite sides) of the substrate.

[0173] For a detailed description of the substrate of the electrode current collector, refer to the above-mentioned electrode current collector. In some embodiments, the substrate of the positive electrode current collector may be, for example, aluminum foil. The substrate of the negative electrode current collector may be, for example, copper foil.

[0174] The step of disposing the intermediate layer on one or both sides (e.g., opposite sides) of the substrate may include dry coating and / or wet coating. Dry coating may be performed, for example, by depositing a carbonaceous conductive material and / or its precursor on one or both sides (e.g., opposite sides) of the substrate of the electrode current collector. The deposition may be performed at room temperature or high temperature, under atmospheric pressure or in a vacuum. In embodiments formed of a carbonaceous conductive material, the intermediate layer provided by dry coating may not include (e.g., may exclude) one (or any) binder. Wet coating may be performed, for example, by coating a composition including a carbonaceous conductive material and a binder on one or both sides (e.g., opposite sides) of the substrate of the electrode current collector. The composition may include, for example, a carbonaceous conductive material, a binder, and a process solvent. For a detailed description of the carbonaceous conductive material and the binder, refer to the above-mentioned electrode. The process solvent may be selected from solvents used for preparing electrode slurries. The process solvent is removed by drying after the composition is coated on the substrate of the electrode current collector. Coating methods such as spin coating or dip coating may be used, but the embodiments of the present disclosure are not limited thereto, and any coating method commonly available in the art may also be used.

[0175] Subsequently, a dry electrode film is concurrently (e.g., simultaneously) or sequentially disposed or placed on one or both sides (e.g., opposite sides) of the electrode current collector to prepare a dry electrode.

[0176] In one or more embodiments, a rolling operation may be further performed while or after the dry electrode film is disposed / placed on one or both sides (e.g., opposite sides) of the electrode current collector.

[0177] Rolling may be performed, for example, by using a rolling press or a flat press, but is not limited thereto. Rolling may be performed, for example, at a pressure of 1.0 ton / cm 2 to 10.0 ton / cm 2 . Excessive pressure during rolling may cause cracks in the electrode current collector. Too low pressure during rolling may cause a decrease in the bonding force between the electrode current collector and the dry electrode film.

[0178] In one or more embodiments, a lithium battery may be manufactured by the following exemplary method, but the method is not limited thereto and may vary according to required conditions.

[0179] First, one or both (e.g., both) of the positive electrode and the negative electrode can be prepared according to the above method for manufacturing a dry electrode. In some embodiments, one selected from the positive electrode and the negative electrode can be prepared according to the above method, and the other electrode can be prepared by a wet method. For example, the other electrode can be prepared by preparing an electrode paste including an electrode active material, a conductive material, a binder, and a solvent, coating the prepared electrode paste on an electrode current collector, and drying the composition. The conductive material and the binder included in the electrode prepared by the wet method can be selected from the conductive materials and the binders used in the above method for manufacturing a dry electrode.

[0180] Subsequently, a separator to be disposed between the positive electrode and the negative electrode is prepared.

[0181] Any separator commonly used in lithium batteries in the art can be used. For example, any separator having a low resistance to ion migration of the electrolyte and excellent or suitable electrolyte retention ability can be used. For example, in one or more embodiments, the separator can be selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), or a combination thereof, each of which is a non-woven or woven fabric. For example, a wound separator such as polyethylene or polypropylene can be used in a lithium ion battery, and a separator having excellent or suitable organic electrolyte retention ability can be used in a lithium ion polymer battery.

[0182] The separator is prepared according to the following exemplary method. However, the method is not limited thereto and can be adjusted according to the required conditions.

[0183] First, a polymer resin, a filler, and a solvent are mixed to prepare a separator composition. The separator composition is directly coated on the electrode and dried to prepare a separator. In some embodiments, the separator composition can be cast on a support and dried, and then the separator film separated from the support is laminated on the electrode to form a separator.

[0184] The polymer (e.g., polymer resin) used for preparing the separator is not particularly limited, and any polymer commonly used as a binder for an electrode plate can also be used. For example, a vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or any mixture thereof can be used.

[0185] Subsequently, an electrolyte is prepared. For a detailed description of the electrolyte, refer to the above lithium battery.

[0186] As Figure 9As shown, according to one or more embodiments of the present disclosure, the lithium battery 1 may include a positive electrode 3, a negative electrode 2, and a separator 4. The positive electrode 3, the negative electrode 2, and the separator 4 may be wound or folded to form a battery assembly 7. The battery assembly 7 may be accommodated in a battery case 5. An organic electrolyte may be injected into the battery case 5, and the battery case 5 may be sealed with a cover assembly 6 to complete the preparation of the lithium battery 1. The battery case 5 may be of a cylindrical type (or kind), but is not limited thereto. For example, a rectangular type (or kind) or a thin film type (or kind) may also be used.

[0187] As Figure 10 As shown, according to one or more embodiments of the present disclosure, the lithium battery 1 may include a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 may be between the positive electrode 3 and the negative electrode 2, and the positive electrode 3, the negative electrode 2, and the separator 4 may be wound or folded to form a battery assembly 7. The battery assembly 7 may be accommodated in a battery case 5. The lithium battery 1 may include an electrode tab 8 that serves as an electrical channel for guiding the current generated in the battery assembly 7 to the outside. An organic electrolyte may be injected into the battery case 5, and the battery case 5 may be sealed to complete the preparation of the lithium battery 1. The battery case 5 may be of a rectangular type (or kind), but is not limited thereto, and for example, a cylindrical type (or kind) or a thin film type (or kind) may also be used.

[0188] As Figure 11 As shown, according to one or more embodiments of the present disclosure, the lithium battery 1 may include a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 may be between the positive electrode 3 and the negative electrode 2 to form a battery assembly 7. The battery assembly 7 may be stacked in a dual-cell structure and accommodated in a battery case 5. The lithium battery 1 may include an electrode tab 8 that serves as an electrical channel for guiding the current generated in the battery assembly 7 to the outside. An organic electrolyte may be injected into the battery case 5, and the battery case 5 may be sealed to complete the preparation of the lithium battery 1. The battery case 5 may be of a rectangular type (or kind), but is not limited thereto, and for example, a cylindrical type (or kind) or a thin film type (or kind) may also be used.

[0189] In a pouch-type (or kind) lithium battery, the pouch may be used as Figures 9 to 11The battery case of the lithium battery shown in the figure. A pouch-type (or similar) lithium battery may include at least one battery component. A separator may be disposed / placed between the positive electrode and the negative electrode to form a battery component. The battery components may be stacked in a dual-cell structure, impregnated with an organic electrolyte, housed in a pouch, and sealed to complete the preparation of the pouch-type (or similar) lithium battery. For example, in one or more embodiments, the above positive electrode, negative electrode, and separator may be simply stacked into a battery component and housed in a pouch. In some embodiments, the positive electrode, negative electrode, and separator may be wound into a pole core form or folded into a battery component and housed in a pouch. Subsequently, an organic electrolyte may be injected into the pouch, and the pouch may be sealed to complete the preparation of the lithium battery.

[0190] Due to excellent or suitable life characteristics and high-rate characteristics, lithium batteries can be used, for example, in electric vehicles (EVs). For example, lithium batteries can be used in hybrid vehicles, such as plug-in hybrid electric vehicles (PHEVs). In some embodiments, lithium batteries can be used in fields that require a large amount of electrical energy storage. For example, lithium batteries can be used in one or more of electric bicycles and power tools.

[0191] Multiple lithium batteries can be stacked to form a battery module, and multiple battery modules can constitute a battery pack. Such a battery pack can be used in any device that requires high capacity and high output. For example, the battery pack can be used in laptop computers, smartphones, and electric vehicles. For example, a battery module may include multiple batteries and a frame for holding the batteries. A battery pack may include, for example, multiple battery modules and busbars for connecting the battery modules. The battery module and / or the battery pack may also include a cooling device. Multiple battery packs can be controlled or selected by a battery management system. The battery management system may include a battery pack and a battery control device connected to the battery pack.

[0192] According to one or more embodiments of the present disclosure, a method for preparing a dry electrode active material may include the following steps: providing a core; providing a composite; and preparing the dry electrode active material by mechanically grinding the core and the composite, wherein the composite may include: at least one first metal oxide; and a first carbonaceous material, wherein the first metal oxide may be disposed in a first carbonaceous material matrix of the first carbonaceous material, and the first metal oxide may be represented by the formula M a O b (where 0 < a ≤ 3, 0 < b < 4, and when a is 1, 2, or 3 (for example, in embodiments), b is not an integer), where M may include at least one metal selected from the elements of Groups 2 to 16 of the periodic table.

[0193] As the core, for example, a lithium transition metal oxide can be provided and utilized. The lithium transition metal oxide may be, for example, a compound represented by one of Formulas 1 to 8.

[0194] Provide a composite. The step of providing the composite may include, for example: supplying a reaction gas including a carbon source gas to a structure including a metal oxide; and performing a heat treatment. In one or more embodiments, the step of providing the composite may include, for example: by supplying at least one reaction gas including a carbon source gas to at least one second metal oxide represented by M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3 (for example, in an embodiment), c is an integer) to prepare a composite; and performing a heat treatment, where M may include at least one metal selected from the elements of Groups 2 to 13, 15, and 16 of the Periodic Table.

[0195] The carbon source gas may be a gas formed from a compound represented by Formula 10, or a mixed gas including at least one selected from the compound represented by Formula 10, the compound represented by Formula 11, and the oxygen-containing gas represented by Formula 12.

[0196] Formula 10 C n H (2n+2-a) [OH] a In Formula 10, n is from 1 to 20, and a is 0 or 1.

[0197] Formula 11 C n H 2n In Formula 11, n is from 2 to 6.

[0198] Formula 12 C x H y O z In Formula 12, x is 0 or an integer from 1 to 20, y is 0 or an integer from 1 to 20, and z is 1 or 2.

[0199] The compound represented by Formula 10 and the compound represented by Formula 11 may each be at least one selected from methane, ethylene, propylene, methanol, ethanol, and propanol. The oxygen-containing gas represented by Formula 12 may include, for example, carbon dioxide (CO2), carbon monoxide (CO), water vapor (H2O), or a mixture thereof.

[0200] When supplying the reaction gas including the carbon source gas to M a O cAfter the second metal oxide represented by (where 0 < a ≤ 3, 0 < c ≤ 4, and in the case where a is 1, 2, or 3 (for example, in the embodiments), c is an integer) is used and heat treatment is performed, a cooling process using at least one inert gas selected from nitrogen, helium, and argon can be further performed. The cooling process can refer to a process of adjusting the temperature to room temperature (about 20 °C to about 25 °C). The carbon source gas can include at least one inert gas selected from nitrogen, helium, and argon.

[0201] In the method of manufacturing a composite, a process of growing a carbonaceous material (e.g., graphene) can be performed under one or more suitable conditions according to a gas-phase reaction.

[0202] In one or more embodiments, according to the first condition, for example, first, methane is supplied to a reactor provided with a second metal oxide represented by M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and if (e.g., when) a is 1, 2, or 3, c is an integer), and the reactor is heated to a heat treatment temperature T. The heating time to reach the heat treatment temperature T is about 10 minutes to about 4 hours, and the heat treatment temperature T is in the range of 700 °C to 1100 °C. Heat treatment is performed for a reaction time at the heat treatment temperature T. The reaction time is, for example, 4 hours to 8 hours. The product obtained by the heat treatment is cooled to room temperature to prepare the composite. The cooling time from the heat treatment temperature T to room temperature is, for example, 1 hour to 5 hours.

[0203] In one or more embodiments, according to the second condition, for example, first, hydrogen is supplied to a reactor provided with a second metal oxide represented by M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and in the case where a is 1, 2, or 3 (for example, in the embodiments), c is an integer), and the temperature is raised to the heat treatment temperature T. The heating time to reach 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 is performed for a set or predetermined reaction time at the heat treatment temperature T, methane gas is supplied, and heat treatment is performed for the remaining reaction time. The reaction time is, for example, 4 hours to 8 hours. The product obtained by the heat treatment is cooled to room temperature to prepare the composite. Nitrogen is supplied during the process of cooling the obtained product. The cooling time from the heat treatment temperature T to room temperature is, for example, 1 hour to 5 hours.

[0204] In one or more embodiments, according to the third condition, for example, first, hydrogen is supplied to a reactor provided with a second metal oxide represented by M a O cA reactor for a second metal oxide represented by (where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3 (e.g., in the examples), c is an integer) and heated to a heat treatment temperature T. The heating time to reach the heat treatment temperature T is 10 minutes to 4 hours, and the heat treatment temperature (T) is 700 °C to 1100 °C. After heat treatment for a set or predetermined reaction time at the heat treatment temperature T, a mixed gas of methane and hydrogen is supplied, and heat treatment for the remaining reaction time is performed. The reaction time is, for example, 4 hours to 8 hours. The product obtained by heat treatment is cooled to room temperature to prepare a composite. Nitrogen is supplied during the process of cooling the obtained product. The cooling time from the heat treatment temperature T to room temperature is, for example, 1 hour to 5 hours.

[0205] In the process of preparing the composite, in examples where the carbon source gas includes water vapor, a composite with excellent or suitable conductivity can be obtained. The amount of water vapor in the gas mixture is not limited, and in some examples, based on 100 vol% of the total carbon source gas, the amount of water vapor can be 0.01 vol% to 10 vol%. The carbon source gas can be, for example: methane; a mixed gas containing methane and an inert gas; or a mixed gas containing methane and an oxygen-containing gas.

[0206] In some examples, the carbon source gas can be, for example: methane; a mixed gas of methane and carbon dioxide; or a mixed gas of methane, carbon dioxide, and water vapor. The molar ratio of methane to carbon dioxide in the mixed gas of methane and carbon dioxide can be about 1:0.20 to about 1:0.50, about 1:0.25 to about 1:0.45, or about 1:0.30 to about 1:0.40. In the mixed gas of methane, carbon dioxide, and water vapor, the molar ratio of methane to carbon dioxide to water vapor can be about 1:0.20 to 0.50:0.01 to 1.45, about 1:0.25 to 0.45:0.10 to 1.35, or about 1:0.30 to 0.40:0.50 to 1.0.

[0207] In some examples, the carbon source gas can be, for example, carbon monoxide or carbon dioxide. In some examples, the carbon source gas can be, for example, a mixed gas of methane and nitrogen. In the mixed gas of methane and nitrogen, the molar ratio of methane to nitrogen can be about 1:0.20 to about 1:0.50, about 1:0.25 to about 1:0.45, or about 1:0.30 to about 1:0.40. In some examples, the carbon source gas may not include (e.g., may exclude) one (or any) inert gas (such as nitrogen).

[0208] In one or more embodiments, the heat treatment pressure can be selected considering the heat treatment temperature, the composition of the gas mixture, and the desired or appropriate amount of carbon coating. The heat treatment pressure can be controlled or selected by adjusting the amount of the inflowing gas mixture and the amount of the outflowing gas mixture. The heat treatment pressure can be, for example, 0.5 atm or greater, 1 atm or greater, 2 atm or greater, 3 atm or greater, 4 atm or greater, or 5 atm or greater. In some embodiments, the heat treatment pressure can be, for example, from 0.5 atm to 10 atm, from 1 atm to 10 atm, from 2 atm to 10 atm, from 3 atm to 10 atm, from 4 atm to 10 atm, or from 5 atm to 10 atm.

[0209] The heat treatment time is not particularly limited and can be appropriately adjusted according to the heat treatment temperature, the heat treatment pressure, the composition of the gas mixture, and the desired or appropriate amount of carbon coating. For example, in some embodiments, the reaction time at the heat treatment temperature is from 10 minutes to 100 hours, from 30 minutes to 90 hours, or from 50 minutes to 40 hours. For example, as the heat treatment time increases, the amount of deposited carbon (e.g., graphene (carbon)) increases, and thus the electrical properties of the composite can be improved. However, this tendency may not necessarily be proportional to the time. For example, after a set or predetermined time, carbon deposition, such as graphene deposition, may no longer occur, or the deposition rate may decrease.

[0210] Through the gas-phase reaction of the above carbon source gas, even at a low temperature, a composite can be obtained by uniformly coating a first carbonaceous material (such as graphene) on at least one of a second metal oxide represented by M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3 (e.g., in the embodiments), c is an integer) and its reduction product (i.e., a first metal oxide represented by M a O b (where 0 < a ≤ 3, 0 < b < 4, and when a is 1, 2, or 3 (e.g., in the embodiments), b is not an integer)).

[0211] For example, in one or more embodiments, the composite can include: a first carbonaceous material matrix (such as a graphene matrix) having at least one structure selected from a spherical structure (e.g., a substantially spherical structure), a helical structure formed by connecting a plurality of spherical structures (e.g., a substantially spherical structure) to each other, a cluster structure formed by aggregating a plurality of spherical structures (e.g., a substantially spherical structure) to each other, and a wrinkled faceted sphere structure; and at least one selected from a first metal oxide and a second metal oxide, located in the first carbonaceous material matrix, the first metal oxide being represented by M a O b(where 0 < a ≤ 3, 0 < b < 4, and when a is 1, 2, or 3 (e.g., in the examples), b is not an integer) indicates that the second metal oxide is M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3 (e.g., in the examples), c is an integer) indicates.

[0212] Subsequently, the lithium transition metal oxide and the composite are mechanically ground to prepare a dry electrode active material. In some embodiments, a Nobilta mixer can be used in the grinding. The rotation speed of the mixer during grinding can be, for example, 1000 rpm to 5000 rpm. The grinding time can be, for example, 5 minutes to 100 minutes. The average particle size D50 of the composite used in the mechanical grinding of the lithium transition metal oxide and the composite can be, for example, 50 nm to 200 nm, 100 nm to 300 nm, or 200 nm to 500 nm. The grinding method used in the mechanical grinding is not particularly limited, and any method available in the art for bringing the lithium transition metal oxide into contact with the composite using a machine can also be used.

[0213] Specific examples of the invention Hereinafter, one or more embodiments will be described in more detail with reference to the following examples and comparative examples. However, these examples and comparative examples are not intended to limit the purpose and scope of one or more embodiments.

[0214] Preparation of the composite Preparation Example 1: Al2O3@Gr composite Al2O3 particles (average particle size: about 15 nm) were placed in a reactor, and then the temperature inside the reactor was raised to 1000 °C while supplying CH4 to the reactor at 300 sccm (i.e., standard cubic centimeters per minute) and 1 atm for about 30 minutes.

[0215] Subsequently, heat treatment was carried out for 7 hours while maintaining this temperature. Then, the temperature inside the reactor was adjusted to room temperature (20 °C to 25 °C) to obtain a composite in which Al2O3 particles and Al2O z (where 0 < z < 3) particles, which are reduction products of Al2O3, are embedded in graphene.

[0216] The amount of alumina included in the composite is 60 wt%.

[0217] Preparation Example 2: SiO2@Gr composite SiO2 particles (average particle size: about 15 nm) were placed in a reactor, and then the temperature inside the reactor was raised to 1000 °C while supplying CH4 to the reactor at about 300 sccm and 1 atm for about 30 minutes.

[0218] Subsequently, a heat treatment is performed for 7 hours while maintaining this temperature. Then, the temperature inside the reactor is adjusted to room temperature (20 °C to 25 °C) to obtain a composite in which SiO2 particles and SiO y (where 0 < y < 2) particles, which are reduction products of SiO2, are embedded in graphene.

[0219] Preparation of Composite Cathode Active Material Example 1: Large-diameter NCA91 coated with 0.4 wt% of Al2O3@Gr composite (0.24 wt% of alumina) LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91) and the composite prepared in Preparation Example 1 are ground using a Nobilta mixer (Hosokawa, Japan) at a rotation speed of about 1000 rpm to about 2000 rpm for about 5 minutes to about 30 minutes to obtain a composite cathode active material. The mixing weight ratio of NCA91 to the composite prepared in Preparation Example 1 is 99.6:0.4.

[0220] Example 2: Small-diameter NCA91 coated with 0.4 wt% of Al2O3@Gr composite (0.24 wt% of alumina) 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 are ground using a Nobilta mixer (Hosokawa, Japan) at a rotation speed of about 1000 rpm to about 2000 rpm for about 5 minutes to about 30 minutes to obtain a composite cathode active material. The mixing weight ratio of NCA91 to the composite prepared in Preparation Example 1 is 99.6:0.4.

[0221] Example 3: Large-diameter NCA91 coated with 0.2 wt% of Al2O3@Gr composite (0.12 wt% of alumina) and 0.05 wt% of CNT LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04O2 (hereinafter referred to as NCA91), the composite prepared in Preparation Example 1, and carbon nanotubes (hereinafter referred to as CNT) were ground using a Nobilta mixer (Hosokawa, Japan) at a rotational speed of about 1000 rpm to about 2000 rpm for about 5 minutes to about 30 minutes to obtain a composite positive electrode active material. A composite positive electrode active material was prepared by mixing NCA91, the composite, and CNT in a ratio of 99.75:0.2:0.05.

[0222] The carbon nanotubes include a carbon nanotube primary structure and a carbon nanotube secondary structure formed by aggregation of a plurality of carbon nanotube units.

[0223] The carbon nanotube primary structure includes one carbon nanotube unit (e.g., consisting of one carbon nanotube unit). The carbon nanotube unit can have a length of 200 nm to 300 nm, and the carbon nanotube has a diameter of about 10 nm.

[0224] A plurality of carbon nanotube units aggregate to form a carbon nanotube secondary structure. The carbon nanotube secondary structure can have a length of 500 nm and a diameter of about 40 nm.

[0225] Comparative Example 1: Large-diameter bare NCA91 Using LiNi with an average particle size D50 of 14 μm 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91) as the composite positive electrode active material.

[0226] Comparative Example 2: NCA91 coated with 0.4 wt% of SiO2@Gr composite Except for using the SiO2@Gr composite prepared in Preparation Example 2 instead of the Al2O3@Gr composite prepared in Preparation Example 1, the composite positive electrode active material was prepared in substantially the same manner as in Example 1.

[0227] Preparation of a lithium battery (half cell) Example 4: Dry positive electrode, core / shell composite positive electrode active material Preparation of a dry positive electrode film and a dry positive electrode The dry composite positive electrode active material prepared in Example 1, a dry carbon-based conductive material, and polytetrafluoroethylene (PTFE) as a dry binder were added to a blade mixer at a weight ratio of 96:2:2 and preliminarily mixed at 25 °C at a speed of 1200 rpm for 10 minutes to prepare a first dry mixture in which the dry composite positive electrode active material, the dry carbon-based conductive material, and the dry binder were uniformly mixed. As the dry carbon-based conductive material, a mixture of carbon nanotubes (CNT) and Ketjenblack (ECP) at a weight ratio of 7:3 was used.

[0228] Subsequently, in order to fibrillate the binder, the first dry mixture was further secondarily mixed at 25 °C at a speed of 4000 rpm for 25 minutes using a blade mixer to prepare a second dry mixture.

[0229] No separate solvent was used in the preparation of the first dry mixture and the second dry mixture.

[0230] The prepared second dry mixture was added to an extruder and extruded to prepare a dry positive electrode film in the form of a sheet as a self-standing film. The pressure during extrusion was 60 MPa.

[0231] The prepared dry positive electrode film as a self-standing film was roll-pressed to prepare a roll-pressed dry positive electrode film as a self-standing film. The pressure during roll-pressing was 3.5 tons / cm 2 . The thickness of the dry positive electrode film was about 200 μm.

[0232] A positive electrode current collector was prepared by coating a carbon layer on one side of a 25-μm-thick aluminum thin film.

[0233] A carbon layer was formed by applying a composition including a carbon-based conductive material (Denka black) and polyvinylidene fluoride (PVDF) to one side of the aluminum thin film and drying the composition. The thickness of the carbon layer provided on one side of the positive electrode current collector was about 1 μm.

[0234] The roll-pressed dry positive electrode film was disposed on one side of the positive electrode current collector to prepare a dry positive electrode.

[0235] Preparation of coin cell A coin cell was prepared by using the positive electrode prepared as described above, lithium metal as a counter electrode, a PTFE separator, and a solution of 1.3 M LiPF6 dissolved in a mixed solvent of ethylene carbonate (EC) + ethyl methyl carbonate (EMC) + dimethyl carbonate (DMC) (volume ratio 3:4:3) as a solvent.

[0236] Example 5: Bimodal dry positive electrode active material A dry electrode film, a dry positive electrode, and a coin cell were prepared in substantially the same manner as in Example 4, except that a 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) mixed at a weight ratio of 7:3 was used instead of the dry composite positive electrode active material of Example 1.

[0237] Example 6: Composite positive electrode active material with CNT added A dry electrode film, a dry positive electrode, and a coin cell were prepared in substantially the same manner as in Example 4, except that the dry composite positive electrode active material of Example 3 was used instead of the dry composite positive electrode active material of Example 1.

[0238] Comparative Example 3: Dry positive electrode and bare NCA91 cathode active material Except for using the LiNi prepared in Comparative Example 1 0.91 Co 0.05 Al 0.04 O2 (hereinafter referred to as NCA91) to replace the dry composite cathode active material of Example 1, a dry electrode film, a dry positive electrode, and a coin cell were prepared in substantially the same manner as in Example 4.

[0239] Comparative Example 4: Wet positive electrode and bare NCA91 cathode active material Preparation of the positive electrode By mixing LiNi with an average particle size D50 of 14 μm in an agate mortar 0.91 Co 0.05 Al 0.04 O2 (herein referred to as NCA91), a carbon-based conductive material, and polyvinylidene fluoride (PVDF) were mixed with N-methylpyrrolidone (NMP) in a weight ratio of 96:2:2 to prepare a cathode active material slurry. As the carbon-based conductive material, a mixture of carbon nanotubes (CNT) and Ketjenblack (ECP) with a weight ratio of 7:3 was used.

[0240] The cathode active material slurry was coated on one side of a 30-μm-thick positive electrode current collector by bar coating and dried at room temperature, and then further dried in vacuo at 120 °C to prepare a stacked structure.

[0241] The prepared stacked structure was roll-pressed to prepare a positive electrode, wherein the cathode active material layer was disposed on the positive electrode current collector. The pressure during roll pressing was 3.5 tons / cm 2 . The thickness of the cathode active material layer was about 200 μm.

[0242] Preparation of the coin cell Except for using the positive electrode prepared as described above, a coin cell was prepared in substantially the same manner as in Example 4.

[0243] Comparative Example 5: Dry positive electrode and SiO2@Gr-coated composite cathode active material Except for using the dry composite cathode active material prepared in Comparative Example 2 to replace the dry composite cathode active material prepared in Example 1, a dry positive electrode film, a dry positive electrode, and a coin cell were prepared in substantially the same manner as in Example 4.

[0244] Evaluation Example 1: XPS spectrum evaluation During the process of preparing the composite prepared according to Preparation Example 1, XPS spectra were measured over time using Quantum 2000 (Physical Electronics). The XPS spectra of the C 1s orbital and the Al 2p orbital of the sample were measured before heating, after 1 minute, after 5 minutes, after 30 minutes, after 1 hour, and after 4 hours, respectively. At the initial stage of heating, only the peak of the Al 2p orbital appeared, and no peak of the C 1s orbital appeared. After 30 minutes, the peak of the C 1s orbital clearly appeared, and the size of the peak of the Al 2p orbital decreased significantly.

[0245] After 30 minutes, a peak of the C 1s orbital caused by C-C bonds and C=C bonds due to graphene growth clearly appeared near 284.5 eV.

[0246] As the reaction time elapsed, the oxidation number of aluminum decreased, and the position of the peak of the Al 2p orbital shifted towards a lower binding energy (eV).

[0247] Therefore, it was confirmed that graphene grew from the Al2O3 particles and Al2O x (the reduction product of Al2O3, where 0 < x < 3) was formed as the reaction proceeded.

[0248] The average amounts of carbon and aluminum in 10 regions of the composite sample prepared in Preparation Example 1 were measured from the XPS analysis results. For the measurement results, the deviation of the amount of aluminum for each region was calculated. The deviation of the amount of aluminum was expressed as a percentage relative to the average value, and it was called the uniformity. The percentage deviation of the average aluminum amount (i.e., the uniformity of the aluminum amount) was 1%. Therefore, it was confirmed that alumina was uniformly dispersed in the composite prepared in Preparation Example 1.

[0249] Evaluation Example 2: SEM, HR-TEM, and SEM-EDS Analyses The composite prepared in Preparation Example 1, the composite positive electrode active material prepared in Example 1, and the bare NCA91 prepared in Comparative Example 1 were analyzed using a scanning electron microscope (SEM), a high-resolution transmission electron microscope, and energy-dispersive X-ray spectroscopy (EDS), respectively.

[0250] For the SEM-EDS analysis, the FEI Titan 80-300 from Philips was used. Figure 3 It is a scanning electron microscope (SEM) image of the bare NCA91 prepared in Comparative Example 1. Figure 4 It is an SEM image of the composite positive electrode active material prepared in Example 1.

[0251] The composite prepared according to Preparation Example 1 showed Al2O3 particles and Al2O as its reduction product zStructure in which particles (where 0 < z < 3) are embedded in graphene. It is confirmed that the graphene layer is located on the outer side of one or more of the particles selected from Al2O3 particles and Al2O z (where 0 < z < 3). At least one of Al2O3 and Al2O z (where 0 < z < 3) particles are uniformly dispersed in the graphene matrix. At least one of Al2O3 particles and Al2O z (where 0 < z < 3) particles has a particle size of about 20 nm. The composite prepared in Preparation Example 1 has a particle size of about 50 nm to about 200 nm.

[0252] Refer to Figure 3 , it is confirmed that the large-diameter NCA91 core is a secondary particle formed by aggregation of multiple primary particles, and no coating is formed on the surface of the bare NCA91 prepared in Comparative Example 1.

[0253] Refer to Figure 4 , it is confirmed that a shell formed of a composite including graphene is provided on the large-diameter NCA91 core in the composite positive electrode active material prepared in Example 1.

[0254] In the SEM-EDS mapping analysis of the large-diameter bare NCA91 in Comparative Example 1 and the core / shell structure prepared in Example 1, it is confirmed that the concentration of aluminum (Al) distributed on the surface of the core / shell structure in Example 1 is increased compared to the concentration of aluminum (Al) on the surface of the bare NCA91 in Comparative Example 1. In the core / shell structure of Example 1, it is confirmed that the composite prepared in Preparation Example 1 is coated on the large-diameter NCA91 core to form a shell.

[0255] Evaluation Example 3: XPS Spectrum Evaluation (Graphene-NCA Chemical Bond) By using Quantum 2000 (Physical Electronics), the XPS spectra of the composite prepared in Preparation Example 1, the large-diameter bare NCA91 in Comparative Example 1, and the composite positive electrode active material prepared in Example 1 were analyzed through the O 1s orbital, and the results are shown in Figure 5 .

[0256] As shown in Figure 5 , due to the presence of C-O-Ni bonds in the composite positive electrode active material in Example 1, a peak appears near 530.2 eV. It is considered that this peak appears due to the bond between the NiO phase on the surface of NCA91 and the carbon of graphene. Therefore, it is confirmed that a covalent bond is formed between graphene included in the shell formed on the core and Ni as a transition metal included in the core.

[0257] Evaluation Example 4: Raman Spectrum Evaluation (Graphene-NCA Chemical Bond) The composite prepared in Preparation Example 1 and the composite positive electrode active material prepared in Example 1 were analyzed by Raman spectroscopy, and the results are shown in Figure 6 .

[0258] As Figure 6 shown, due to the graphene in the composite prepared in Preparation Example 1, a D-band peak at 1338.7 cm -1 and a G-band peak at 1575.0 cm -1 appeared.

[0259] In contrast, since the shell including graphene is included in the composite positive electrode active material of Example 1, the D-band peak shifted by about 12 cm -1 to 1351.3 cm -1 , and the G-band peak shifted by about 18 cm -1 to 1593.6 cm -1 .

[0260] It is considered that the D-band shift is caused by the strain of the graphene constituting the shell formed on the core by grinding.

[0261] It is considered that the G-band shift is caused by the charge transfer between the core and graphene in the composite because the composite is formed by the C-O-Ni bond between the core and the shell.

[0262] Therefore, it was confirmed that the graphene included in the shell formed on the core forms a covalent bond with Ni as a transition metal included in the core.

[0263] Evaluation Example 5: Evaluation of the cross-section of the electrode The cross-sectional images obtained by scanning electron microscopy (SEM) and scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) were used to evaluate the dry positive electrode prepared in Example 4 and the dry positive electrode prepared in Comparative Example 3, respectively, and the results are shown in Figure 7a , Figure 7b , Figure 8a and Figure 8b .

[0264] Figure 7a is an SEM image of the cross-section of the dry positive electrode prepared in Comparative Example 3. Figure 7b is an SEM-EDS mapping image of the cross-section of the dry positive electrode prepared in Comparative Example 3.

[0265] Figure 8a is an SEM image of the cross-section of the dry positive electrode prepared in Example 4. Figure 8b is an SEM-EDS mapping image of the cross-section of the dry positive electrode prepared in Example 4.

[0266] As Figure 7a and Figure 7bAs shown, it was confirmed that aggregation occurred in the dry positive electrode prepared in Comparative Example 3 because the dry binder was not uniformly dispersed in the dry electrode film. The areas of binder aggregation are indicated by the dashed lines.

[0267] As Figure 8a and Figure 8b shown, it was confirmed that in the dry positive electrode prepared in Example 4, the dry binder was uniformly dispersed in the dry electrode film.

[0268] It is considered that because a dry electrode including a composite positive electrode active material having a core / shell structure was used in Example 4, the binder and the conductive material were uniformly dispersed in the dry electrode film.

[0269] In contrast, it is considered that because a dry electrode including a bare positive electrode active material was used in Comparative Example 3, aggregation of the binder and the conductive material could not be suppressed in the dry electrode film, resulting in non-uniform dispersion of the binder in the dry electrode film.

[0270] Evaluation Example 6: Peel Strength Evaluation The dry positive electrodes prepared in Example 4 and Comparative Example 3 and the wet positive electrode prepared in Comparative Example 4 were each cut into pieces having dimensions of 25 mm × 150 mm and fixed to the center of a glass slide having dimensions of 30 mm × 200 mm using tape. Then, the 90° peel strength was measured while peeling the current collector from the positive electrode active material layer using a universal testing machine (UTM). The measurement results are shown in Table 1.

[0271] Table 1

[0272] As shown in Table 1, the dry positive electrode of Example 4 exhibited improved binding force compared to the dry positive electrode of Comparative Example 3.

[0273] It is considered that, compared to the dry positive electrode of Comparative Example 3, the binder was more uniformly dispersed in the dry electrode film of the dry positive electrode of Example 4, enabling the fibrillated binder to more effectively promote the binding of the dry electrode film to the positive electrode current collector.

[0274] Furthermore, the dry positive electrode of Example 4 exhibited improved binding force compared to the wet positive electrode of Comparative Example 4.

[0275] Evaluation Example 7: Tensile Strength Evaluation According to the ASTM D 638 method, samples (216 mm (length) × 19 ± 0.5 mm (width) × 3.18 ± 0.38 mm (thickness)) of the dry positive electrode films prepared in Example 4 and Comparative Example 3 were respectively subjected to tensile strength measurement. The tensile strength was measured by a tensile strength test performed according to the ASTM D 638 method. The measurement results are shown in Table 2.

[0276] Table 2

[0277] As shown in Table 2, compared with the dry positive electrode film of Comparative Example 3, the dry positive electrode film of Example 4 exhibits improved mechanical strength.

[0278] It is considered that, compared with the dry positive electrode of Comparative Example 3, in the dry positive electrode of Example 4, the binder is more uniformly dispersed in the dry electrode film, so that the fibrillated binder more effectively promotes the binding of the composite positive electrode active material.

[0279] Evaluation Example 8: Mixture Resistance Evaluation By using an electrode resistance measurement system (Hioki, RM2610), the mixture 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, and the measurement results are shown in Table 3.

[0280] After positioning the probe on the positive electrode in the electrode resistance measurement system (Hioki, RM2610) so that the positive electrode active material of the positive electrode faces the probe and supplying a constant current to the surface of the positive electrode active material layer, the volume resistivity of the positive electrode active material layer and the interfacial resistance between the positive electrode active material layer and the positive electrode current collector are measured. The volume resistivity of the positive electrode active material layer is regarded as the mixture resistance of the positive electrode active material layer.

[0281] Table 3

[0282] As shown in Table 3, compared with the mixture resistance of the dry positive electrode of Comparative Example 3 and the wet positive electrode of Comparative Example 4, the dry positive electrode of Example 4 has a lower mixture resistance.

[0283] It is considered that the dry positive electrode of Example 4 has an increased electronic conductivity and / or ionic conductivity in the dry positive electrode film because a composite positive electrode active material in which a shell including a first metal oxide and a first carbonaceous material is uniformly provided on a core is used.

[0284] It is considered that the dry positive electrode of Comparative Example 3 and the wet positive electrode of Comparative Example 4 have low electronic conductivity and / or ionic conductivity because the above composite positive electrode active material is not used therein.

[0285] Evaluation Example 9: Interfacial Resistance Evaluation By using an electrode resistance measurement system (Hioki, RM2610), the interfacial 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, and the measurement results are shown in Table 4.

[0286] After positioning the probe on the positive electrode in an electrode resistance measurement system (Hioki, RM2610) such that the positive electrode active material faces the probe and supplying a constant current to the surface of the positive electrode active material layer, the volume resistivity of the positive electrode active material layer and the interfacial resistance between the positive electrode active material layer and the positive electrode current collector are measured by surface potential distribution.

[0287] Table 4

[0288] As shown in Table 4, the dry positive electrode of Example 4 has a lower interfacial resistance compared to the interfacial resistances of the dry positive electrode of Comparative Example 3 and the wet positive electrode of Comparative Example 4.

[0289] Evaluation Example 10: Evaluation of Charge / Discharge Characteristics at Room Temperature (25 °C) Each of the lithium batteries prepared in Examples 4 to 6 and Comparative Examples 3 to 5 was charged at a constant current of 0.1 C rate at 25 °C until the voltage reached 4.3 V (vs. Li), and the charging process was cut off at a current of 0.05 C rate in constant voltage mode while maintaining the voltage of 4.3 V. Subsequently, the lithium battery was discharged at a constant current of 0.1 C rate until the voltage reached 2.8 V (vs. Li) during discharge (formation cycle).

[0290] The lithium battery that had undergone the formation cycle was charged at a constant current of 0.5 C rate at 25 °C until the voltage reached 4.3 V (vs. Li), and then the charging process was cut off at a current of 0.05 C rate in constant voltage mode while maintaining the voltage of 4.3 V. Subsequently, the lithium battery was discharged at a constant current of 0.5 C rate until the voltage reached 2.8 V (vs. Li) during discharge (first cycle). This cycle was repeated up to the 350th cycle under the same conditions.

[0291] After each charge / discharge cycle, the lithium battery was allowed to stand for 10 minutes. Some results of the room temperature charge / discharge test are shown in Table 5. The capacity retention rate is defined as shown in Equation 3.

[0292] Equation 3 Capacity retention rate [%] = [Discharge capacity at the 300th cycle / Discharge capacity at the first cycle] × 100 Table 5

[0293] As shown in Table 5, the lithium batteries of Examples 4 to 6 all have improved life characteristics compared to the lithium batteries of Comparative Examples 3 and 4.

[0294] The lithium batteries of Example 5 and Example 6 both have excellent life characteristics compared to the life characteristics of the lithium battery of Example 4.

[0295] Although not shown in Table 5, the lithium battery of Comparative Example 5 has poor life characteristics compared to the life characteristics of the lithium battery of Example 4.

[0296] It is considered that the lithium battery of Comparative Example 5 has poor high-voltage stability of the SiO2@Gr composite provided on the NCA91 core.

[0297] Evaluation Example 11: Evaluation of the vertical force of the positive electrode active material layer (I) The adhesion characteristics of the positive electrode active material layer included in the dry positive electrode of Example 4 and the wet positive electrode prepared in Comparative Example 4 were analyzed using SAICAS (SAICAS EN-EX, Daipla Wintes, Japan), respectively.

[0298] The vertical force according to the depth (F VR ) was measured by performing a constant-speed analysis using a diamond blade with a width of 1 mm under the conditions of a clearance angle of 10°, an inclination angle of 20°, a shear angle of 45°, a horizontal speed of 4 μm / s, and a vertical speed of 0.4 μm / s.

[0299] First, a first constant-speed analysis was performed from the first position on the surface of the positive electrode active material layer to the surface of the positive electrode current collector, and the blade was horizontally moved along the surface of the positive electrode current collector to remove the positive electrode active material layer. Then, a second constant-speed analysis was performed at a position 10 μm back from the first position under the same conditions as the first constant-speed analysis. The data measured during the second constant-speed analysis was used.

[0300] The vertical force of the positive electrode active material layer was measured, and the measured data was normalized with respect to the force curve area to derive the vertical relative force of the positive electrode active material layer according to the depth (F VR ).

[0301] The vertical force of the positive electrode active material layer was obtained by using the data measured along the interval starting from the first point and ending at the second point. The first point was 5% of the total thickness of the positive electrode active material layer away from the surface of the positive electrode active material layer, and the second point was 5% of the total thickness of the positive electrode active material layer away from the surface of the electrode current collector. For example, the data near the surface of the positive electrode active material layer and the data near the surface of the electrode current collector were excluded to prevent or reduce measurement errors.

[0302] According to the derived data of the vertical relative force (F VR ) of the positive electrode active material layer, the vertical relative force (F VR). Rate of change. In addition, the arithmetic mean is calculated from the data of the vertical relative force (F VR ) of the derived positive electrode active material layer.

[0303] Equation 1 Vertical relative force (F VR ) Rate of change (%) = [(Maximum value of vertical relative force (F VR2 ) - Minimum value of vertical relative force (F VR1 )) / Minimum value of vertical relative force (F VR1 ))] × 100 As a result of the measurement, the rate of change of the vertical relative force of the positive electrode active material layer included in the dry positive electrode of Example 4 was 200% or less.

[0304] Therefore, it was confirmed that the positive electrode active material layer (i.e., the dry electrode film) of Example 4 had substantially uniform binding force and component distribution regardless of the position in the thickness direction of the positive electrode active material layer.

[0305] On the contrary, the rate of change of the vertical relative force of the positive electrode active material layer included in the wet positive electrode of Comparative Example 4 exceeded 400%.

[0306] Therefore, it was confirmed that in the positive electrode active material layer of Comparative Example 4, the binding force and the component distribution changed significantly according to the position in the thickness direction of the positive electrode active material layer.

[0307] Evaluation Example 12: Evaluation of the horizontal force of the positive electrode active material layer (II) The adhesion characteristics of the positive electrode active material layer included in the dry positive electrode prepared in Example 4 and the wet positive electrode prepared in Comparative Example 4 were analyzed using SAICAS (SAICAS EN-EX, Daipla Wintes, Japan), respectively.

[0308] The horizontal force (F H ) according to the depth was measured by performing a constant speed analysis using a diamond blade with a width of 1 mm under the conditions of a clearance angle of 10°, an inclination angle of 20°, a shear angle of 45°, a horizontal speed of 4 μm / s, and a vertical speed of 0.4 μm / s.

[0309] First, a first constant speed analysis was performed from the first position on the surface of the positive electrode active material layer to the surface of the positive electrode current collector, and the blade was horizontally moved along the surface of the positive electrode current collector to remove the positive electrode active material layer. Then, a second constant speed analysis was performed at a position 10 μm back from the first position under the same conditions as the first constant speed analysis. The data measured by the second constant speed analysis was used.

[0310] The first horizontal force (F H1), and the second horizontal force (F at the second point H2 ), the first point is 10% of the total thickness of the positive electrode active material layer away from the surface of the positive electrode active material layer, and the second point is 10% of the total thickness of the positive electrode active material layer away from the surface of the positive current collector.

[0311] The horizontal force ratio between the first point and the second point is defined by Equation 2.

[0312] Equation 2 Horizontal force ratio (%) from the first point to the second point = [F H2 / F H1 × 100 As a result of the measurement, the horizontal force ratio of the positive electrode active material layer of Example 4 is 60% or more.

[0313] In contrast, the horizontal force ratio of the positive electrode active material layer of Comparative Example 4 is less than 50%.

[0314] For example, the horizontal force ratio of the positive electrode active material layer of Example 4 is greater than that of the positive electrode active material layer of Comparative Example 4.

[0315] Therefore, it is confirmed that the positive electrode active material layer (i.e., the dry electrode film) of Example 4 has a more substantially uniform adhesive force and component distribution than the positive electrode active material layer of Comparative Example 4.

[0316] Industrial Applicability According to one or more aspects of the embodiments of the present disclosure, since the dry electrode film has a reduced internal resistance and improved mechanical properties, the cycle characteristics of a lithium battery including the dry electrode film can be improved.

Claims

1. A dry electrode film, the dry electrode film comprising: Dry electrode active material; And Dry binder, Wherein, the dry electrode active material comprises: a core; and a shell on the surface of the core, The shell comprises a first carbonaceous material and at least one first metal oxide, The first metal oxide is in a first carbonaceous material matrix, and The first metal oxide is represented by the formula M a O b where 0 < a ≤ 3, 0 < b < 4, and when a is 1, 2, or 3, b is not an integer, and M includes at least one element selected from the elements of Groups 2 to 16 of the periodic table.

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

3. The dry electrode film according to claim 1, wherein, The shell further comprises a second metal oxide, The second metal oxide is represented by the formula M a O c (where 0 < a ≤ 3, 0 < c ≤ 4, and when a is 1, 2, or 3, c is an integer). The second metal oxide comprises the same metal as the metal of the first metal oxide, The c / a ratio of the second metal oxide has a value larger than the b / a ratio of the first metal oxide, and The second metal oxide is in the first carbonaceous material matrix.

4. The dry electrode film according to claim 3, wherein, The second metal oxide is selected from Al2O3, NbO, NbO2, Nb2O5, MgO, Sc2O3, TiO2, ZrO2, V2O3, WO2, MnO2, Fe2O3, Co3O4, PdO, CuO, AgO, ZnO, Sb2O3 and SeO2, and The first metal oxide is a reduction product of the second metal oxide.

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

6. The dry electrode film according to claim 1, the dry electrode film further comprises a third metal doped on the core or a third metal oxide coated on the core, Among them, The shell is on the third metal oxide, The third metal oxide is an oxide of the third metal, and the third metal comprises at least one selected from Al, Zr, W and Co.

7. The dry electrode film according to claim 1, wherein The shell further comprises a second carbonaceous material, The second carbonaceous material comprises a fibrous carbonaceous material with an aspect ratio of 10 or more, The second carbonaceous material comprises carbon nanofibers, carbon nanotubes or a combination thereof, The carbon nanotubes comprise a carbon nanotube primary structure, a carbon nanotube secondary structure formed by aggregation of multiple carbon nanotube primary structures, or a combination thereof, and The carbon nanotube primary structure is a single carbon nanotube unit.

8. The dry electrode film according to 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 one of Formula 1 to Formula 8: Formula 1 Li a Ni x Co y M z O 2-b A b Wherein, in 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, and A is F, S, Cl, Br or a combination thereof, Formula 2 LiNi x Co y Mn z O2 Formula 3 LiNi x Co y Al z O2 In Formulas 2 and 3, 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1, Formula 4 LiNi x Co y Mn z Al w O2 In 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, Formula 5 Li a Co x M y O 2-b A b In 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, and A is F, S, Cl, Br, or a combination thereof, Formula 6 Li a Ni x Mn y M' z O 2-b A b In 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, and A is F, S, Cl, Br, or a combination thereof, Formula 7 Li a M1 x M2 y PO 4-b X b In 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, and 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, Formula 8 Li a M3 z PO4 In Formula 8, 0.90 ≤ a ≤ 1.1 and 0.9 ≤ z ≤ 1.1, and M3 is chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), zirconium (Zr), or a combination thereof.

10. The dry electrode film according to claim 1, wherein, The shell includes the first metal oxide and the first carbonaceous material, and the core includes a lithium transition metal oxide, and wherein, the first carbonaceous material is chemically bonded to the transition metal (Me) of the lithium transition metal oxide by a chemical bond, the carbon atoms (C) of the first carbonaceous material are chemically bonded to the transition metal (Me) of the lithium transition metal oxide via an oxygen atom by a C-O-Me bond, or the first metal oxide is chemically bonded to the first carbonaceous material by a chemical bond.

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

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

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

40.

14. The dry electrode film according to claim 1, wherein, The dry binder includes a fibrillated binder, the dry binder includes a fluorine-based binder, The dry binder has a glass transition temperature (T g ) ranging from 15 °C to 100 °C, and Based on the total weight of the dry electrode film, the amount of the dry binder is 0.1 wt% to 5 wt%.

15. The dry electrode film according to claim 1, wherein, The dry electrode film further includes a dry conductive material, the dry conductive material includes a carbon-based conductive material, the carbon-based conductive material includes a fibrous carbon-based material having an aspect ratio of 10 or more, a particulate carbon-based material having an aspect ratio of less than 10, or a combination thereof, and Based on the total weight of the dry electrode film, the amount of the dry conductive material is 0.1 wt% to 5 wt%.

16. The dry electrode film according to claim 1, wherein The dry electrode film is a self-supporting film, and the dry electrode film does not include residual process solvents, and the tensile strength of the dry electrode film is 500 kPa to 5000 kPa.

17. A dry electrode, the dry electrode comprising: an electrode current collector; and the dry electrode film according to claim 1, the dry electrode film being on at least one side of the electrode current collector.

18. The dry electrode according to claim 17, wherein, The electrode current collector includes: a substrate; and an intermediate layer between the substrate and the dry electrode film, and the intermediate layer includes a carbon-based conductive material.

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

20. A lithium battery, the lithium battery comprising: a first electrode; a second electrode; and an electrolyte between the first electrode and the second electrode, wherein the first electrode, the second electrode, or a combination thereof is the dry electrode according to claim 17, and The electrolyte includes a liquid electrolyte, a solid electrolyte, a gel electrolyte, or a combination thereof.

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