Electrode, lithium battery comprising the electrode, and method of manufacturing the electrode

Abstract

An electrode, a lithium battery including the electrode, and a method of manufacturing the electrode are provided. The electrode includes: an electrode current collector; and an electrode active material layer disposed on one surface or both surfaces of the electrode current collector, wherein the electrode active material layer includes a first electrode active material, a second electrode active material, and a binder, the electrode active material layer includes first clusters, and the first clusters are agglomerates including a plurality of the first electrode active material, one surface of the electrode active material layer includes first domains including the first clusters, and an area of the first domains is 15% to 60% of a total area of the one surface of the electrode active material layer.

Description

[0001] This application is based on and claims priority to Korean Patent Application No. 10-2021-0178877, filed on December 14, 2021, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein in its entirety by reference. TECHNICAL FIELD

[0002] One or more embodiments relate to an electrode, a lithium battery including the electrode, and a method of manufacturing the electrode. BACKGROUND

[0003] To meet the miniaturization and high performance of various devices, lithium batteries need to have high energy density in addition to miniaturization and weight reduction. That is, high-capacity lithium batteries are becoming increasingly important.

[0004] To realize lithium batteries suitable for the above uses, electrodes having a high loading capacity are being studied.

[0005] In an electrode having a high loading capacity, the distribution of components in the electrode becomes non-uniform, and the density near the surface of the electrode increases. Therefore, the performance of a lithium battery including such an electrode deteriorates.

[0006] There is a need for an electrode capable of preventing the deterioration of the performance of a lithium battery. SUMMARY

[0007] One or more embodiments include a new electrode in which electrolyte impregnation characteristics are improved by including clusters of agglomerates as an electrode active material in the electrode.

[0008] One or more embodiments include a new electrode that prevents the deterioration of the performance of a battery in which components in the electrode have a uniform distribution.

[0009] One or more embodiments include a lithium battery including the electrode.

[0010] One or more embodiments provide a method of preparing an electrode.

[0011] Additional aspects will be set forth in part in the description which follows, and in part will become apparent to those skilled in the art by reference to the description, or can be learned by practice of the disclosed embodiments.

[0012] According to one or more embodiments, the electrode includes:

[0013] an electrode current collector; and

[0014] an electrode active material layer disposed on one surface or both surfaces of the electrode current collector, wherein

[0015] The electrode active material layer includes the first electrode active material, the second electrode active material, and a binder,

[0016] The electrode active material layer includes first clusters, wherein the first clusters are agglomerates including a plurality of the first electrode active material,

[0017] One surface of the electrode active material layer includes first domains including the first clusters, and

[0018] An area of the first domains is 15% to 60% of a total area of the one surface of the electrode active material layer.

[0019] According to one or more embodiments, a lithium battery includes:

[0020] a positive electrode;

[0021] a negative electrode; and

[0022] an electrolyte between the positive electrode and the negative electrode, wherein

[0023] one of the positive electrode and the negative electrode is the above-described electrode.

[0024] According to one or more embodiments, a method of manufacturing an electrode is provided, the method including the steps of:

[0025] preparing a dry mixture by dry mixing a first electrode active material, a second electrode active material, a dry conductive material, and a dry binder;

[0026] forming an electrode active material layer from the dry mixture;

[0027] roll-pressing the electrode active material layer; and disposing the roll-pressed electrode active material layer on an electrode current collector, wherein

[0028] The electrode includes: an electrode current collector; and an electrode active material layer disposed on one surface or both surfaces of the electrode current collector, wherein

[0029] The electrode active material layer includes the first electrode active material, the second electrode active material, and a binder,

[0030] The electrode active material layer includes first clusters, wherein the first clusters are agglomerates including a plurality of the first electrode active material,

[0031] One surface of the electrode active material layer includes first domains including the first clusters, and

[0032] An area of the first domains is 15% to 60% of a total area of the one surface of the electrode active material layer. BRIEF DESCRIPTION OF DRAWINGS

[0033] The above and other aspects, features, and advantages of certain embodiments of the disclosure will be more apparent from the following description taken in conjunction with the accompanying drawings, in which:

[0034] Figure 1 A scanning electron microscope image of one surface of an electrode active material layer included in the electrode prepared in Example 1 is shown;

[0035] Figure 2 A scanning electron microscope image of one surface of an electrode active material layer included in the electrode prepared in Example 2 is shown;

[0036] Figure 3A A scanning electron microscope image of one surface of an electrode active material layer included in the electrode prepared in Example 3 is shown;

[0037] Figure 3B An image obtained by converting a scanning electron microscope image by image analysis is shown; Figure 3A

[0038] Figure 4 A scanning electron microscope image of one surface of an electrode active material layer included in the electrode prepared in Comparative Example 1 is shown;

[0039] Figures 5A to 5D is a cross-sectional view of an electrode according to an embodiment;

[0040] Figure 6 is a schematic view of an electrode according to an exemplary embodiment;

[0041] Figures 7A to 7F is a plan view of an electrode according to an embodiment;

[0042] Figure 8 is a cross-sectional view of an electrode according to an embodiment;

[0043] Figure 9 is a side view of an electrode assembly according to an embodiment;

[0044] Figure 10 is a side view of an electrode assembly according to an embodiment;

[0045] Figure 11 is a front view of an electrode assembly according to an embodiment;

[0046] Figure 12 is a schematic view of a lithium battery according to an embodiment;

[0047] Figure 13 is a schematic view of a lithium battery according to an embodiment; and

[0048] Figure 14 ​A schematic diagram of a lithium battery according to an embodiment is shown. DETAILED DESCRIPTION

[0049] Reference will now be made in detail to embodiments, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. In this regard, the present embodiments can have different forms and should not be construed as being limited to the descriptions set forth herein. Accordingly, the embodiments are merely described below, by referring to the drawings, to explain aspects of the present description. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. Expressions such as "at least one of," when preceding the list of two or more members, modify the member(s) of the list as an alternative (i.e., the phrase "at least one of a, b, and c" can mean only a, only b, only c, or both a and b, or a and c, or b and c, or a, b, and c).

[0050] Since the inventive concept to be described below can be variously modified and can have various embodiments, specific embodiments are illustrated in the drawings and described in detail in the detailed description. However, it is not intended to limit the inventive concept to specific embodiments, and it is to be understood that all modifications, equivalents, or alternatives included in the technical scope of the inventive concept are included.

[0051] The terms used below are merely used to describe specific embodiments and are not intended to limit the inventive concept. Unless explicitly stated otherwise in the context, a singular expression includes a plural expression. In the following, it will also be understood that when the terms "include", "comprise" or "have" are used in the present specification, it is stated that the stated features, integers, steps, operations, elements, and / or components exist, but it does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. " / " used below can be interpreted as "and" or "or" according to the situation.

[0052] In the drawings, thicknesses are exaggerated or reduced for the sake of clarity in expressing various layers and regions. Throughout the specification, like drawing reference numerals denote like components. Throughout the specification, when a component (such as a layer, a film, a region, or a plate) is referred to as being "on" another component, it will be understood that the component can be directly on the other component, or another component can be interposed therebetween. Throughout the specification, although the terms "first", "second", "third", and the like can be used herein to describe various elements, components, regions, and / or layers, these elements, components, regions, and / or layers should not be limited by these terms. These terms are merely used to distinguish one component from another.

[0053] The term "dry" or "dry-type" refers to a state of not intentionally contacting a solvent (such as a processing solvent) or a state of not intentionally including a solvent. For example, a dry electrode active material refers to an electrode active material not intentionally contacting a solvent or an electrode active material not intentionally including a solvent. For example, a dry conductive material refers to a conductive material not intentionally contacting a solvent or a conductive material not intentionally including a solvent. For example, a dry binder refers to a binder not intentionally contacting a solvent or a binder not intentionally including a solvent. For example, a binder in a liquid state at room temperature without mixing with a solvent is a dry binder.

[0054] Hereinafter, an electrode according to an embodiment, a lithium battery including the same, and a method of manufacturing the same will be described in more detail.

[0055] The electrode according to an embodiment includes: an electrode current collector; and an electrode active material layer disposed on one surface or both surfaces of the electrode current collector, wherein the electrode active material layer includes a first electrode active material, a second electrode active material, and a binder, the electrode active material layer includes a first cluster, wherein the first cluster is an agglomerate including a plurality of the first electrode active material, one surface of the electrode active material layer includes a first domain including the first cluster, and an area of the first domain is 15% to 60% of a total area of the one surface of the electrode active material layer. The area of the first domain can be, for example, 20% to 60%, 25% to 60%, 30% to 60%, or 35% to 60% of the total area of the one surface of the electrode active material layer. The total area of the one surface of the electrode active material layer can be, for example, a total area of one surface of the electrode perpendicular to a thickness direction of the electrode. By including these area ranges of the first domain of the electrode, the electrolyte impregnation property of the electrode is improved. Accordingly, the cycle characteristics of a lithium battery including such an electrode are improved. The first cluster is an agglomerate including a plurality of the first electrode active material. Specifically, the first cluster can include 4 or more particles of the first active material that remain directly adjacent to each other (or positioned directly adjacent to each other) in the active material layer. To remain directly (or positioned directly) to each other means that the particles are in direct contact with each other and / or connected only by the binder. One surface of the electrode active material layer includes a first domain including the first cluster. In other words, all of the first clusters located on the surface of the electrode active material layer form the first domain. Specifically, at least the surface opposite to the electrode current collector exhibits a desired non-uniform distribution of particles of the first electrode material and the second electrode material. Specifically, all of the surface areas of the first clusters located on the surface of the electrode active material layer add up to the area of the first domain. The area of the first domain can be obtained by image analysis of a scanning electron microscope image.

[0056] Referring to Figure 1 and Figure 2Since the first cluster is a group of the plurality of first electrode active materials, a relatively increased porosity can be obtained among the first electrode active materials. Therefore, the electrolyte can easily penetrate into the electrode through the pores among these first electrode active materials. Thus, the electrolyte impregnation property of the electrode is improved. Therefore, the first cluster can provide an increased contact area between the first electrode active material and the electrolyte, and thus improve the reversibility of the electrode reaction. For example, the reversibility of the electrode reaction can be maintained even under a charge / discharge condition using overcurrent.

[0057] When the area of the first domain is too small, the electrolyte impregnation property of the electrode is deteriorated, and thus the high-rate characteristic of a lithium battery including such an electrode can be deteriorated. When the area of the first domain is too large, the electrolyte impregnation property of the electrode is improved, but the contact area between the electrode and the electrolyte is increased too much, and more side reactions can occur at the interface between the first electrode active material and the electrolyte. Thus, the life characteristic of a lithium battery including such an electrode can be deteriorated. In addition, since the porosity of the electrode is greatly increased, the energy density of a lithium battery including such an electrode can be reduced.

[0058] The number of the plurality of first electrode active materials included in the first cluster can be, for example, 4 to 200, 6 to 150, 8 to 100, or 10 to 50. Within these numbers of the first electrode active materials included in the first cluster, the electrolyte impregnation property of the electrode can be further improved. When the number of the first electrode active materials included in the first cluster is too small, the group is not properly formed.

[0059] The area occupied by one first cluster on one surface of the electrode active material layer can be, for example, 2500 μm 2 or more. The area occupied by one first cluster on one surface of the electrode active material layer can be, for example, 2500 μm 2 to 100,000 μm 2 , 2500 μm 2 to 50,000 μm 2 , 2500 μm 2 to 30,000 μm 2 , 2500 μm 2 to 20,000 μm 2 , or 2500 μm 2 to 10,000 μm 2 . When the area occupied by the first cluster is less than 2500 μm 2 , the effect on improving the electrolyte impregnation property of the electrode can be insignificant.

[0060] One surface of the electrode active material layer can include, for example, a second domain including a second cluster in addition to the first domain including the first cluster. The second domain can include, for example, a second electrode active material and a binder. The second cluster can include, for example, a cluster containing a plurality of the second electrode active material and the binder. In an embodiment, in one surface of the electrode active material layer, one or more second clusters included in the second domain can be disposed between one or more first clusters included in the first domain. By disposing a plurality of second clusters among a plurality of first clusters, the energy density of an electrode including the first and second clusters can be improved.

[0061] The first electrode active material can be, for example, a large-particle electrode active material having a particle diameter larger than that of the second electrode active material, and the second electrode active material can be, for example, a small-particle electrode active material having a particle diameter smaller than that of the first electrode active material. The first and second electrode active materials can each be, for example, a positive electrode active material. The first and second electrode active materials can be, for example, a first lithium transition metal oxide and a second lithium transition metal oxide, respectively. The first lithium transition metal oxide can be a lithium transition metal oxide having a larger particle diameter, and the second lithium transition metal oxide can be a lithium transition metal oxide having a smaller particle diameter. That is, the first electrode active material can be a lithium transition metal oxide having a larger particle diameter, and the second electrode active material can be a lithium transition metal oxide having a smaller particle diameter. For example, the second electrode active material having a particle diameter smaller than that of the first electrode active material can be disposed in a hole among the first electrode active material. Since the particles of the second electrode active material, which are smaller particles, are disposed in the holes among the particles of the first electrode active material, which are larger particles, the ion conductivity and the electronic conductivity of an electrode containing the first and second electrode active materials are simultaneously improved. In addition, the energy density of the electrode can be improved. Accordingly, the energy density of a lithium battery including such an electrode can be improved, and its cycle characteristics can be improved. In an embodiment, the first and second electrode active materials can each be, for example, a negative electrode active material.

[0062] The first electrode active material and the second electrode active material can each have, for example, a bimodal particle size distribution in a distribution profile according to particle diameter (i.e., a particle size distribution chart). For example, the mixture of the first electrode active material and the second electrode active material can have a bimodal particle size distribution having two peaks in a particle size distribution chart obtained by using a particle size analyzer (PSA) or the like. The bimodal particle size distribution can have a first peak corresponding to the first electrode active material and a second peak corresponding to the second electrode active material. Since the first electrode active material and the second electrode active material each have such a bimodal particle size distribution, the energy density of the electrode including the first electrode active material and the second electrode active material is further improved, and the cycle characteristics of the lithium battery including the electrode can be improved.

[0063] The particle diameter ratio of the first electrode active material to the second electrode active material can be, for example, 3:1 to 40:1, 3:1 to 30:1, 3:1 to 20:1, or 3:1 to 10:1. When the first electrode active material and the second electrode active material have these particle diameter ranges, the energy density of the electrode including the first electrode active material and the second electrode active material can be further improved, and the cycle characteristics of the lithium battery having such an electrode can also be improved.

[0064] The particle diameter of the first electrode active material can be, for example, 15 pm to 30 pm, 15 pm to 27 pm, or 15 pm to 25 pm. The particle diameter of the second electrode active material can be, for example, 1 pm to 6 pm, 1 pm to 5 pm, 2 pm to 5 pm, or 2 pm to 4 pm. When the first electrode active material and the second electrode active material each have these particle diameter ranges, the energy density and / or the cycle characteristics of the lithium battery including the first electrode active material and the second electrode active material can be further improved. The particle diameter of the first electrode active material and the second electrode active material can each be, for example, an average particle diameter. The average particle diameter can be measured using, for example, a laser diffraction method or a dynamic light scattering method. The average particle diameter is measured using a laser scattering particle size distribution meter (e.g., LA-920 by Horiba Corporation), and is a value of a median particle diameter (D50) when metal oxide particles are cumulatively converted to 50% by volume from small particles. In an embodiment, the average particle diameter can be, for example, an arithmetic mean of the particle diameters of the particles measured by image analysis of a scanning electron microscope image using software or a manual.

[0065] The weight ratio of the first electrode active material to the second electrode active material can be, for example, 9:1 to 6:4 or 8:2 to 7:3. When the first electrode active material and the second electrode active material have these weight ratio ranges, the energy density of the electrode including the first electrode active material and the second electrode active material can be further improved, and the cycle characteristics of the lithium battery having such an electrode can also be improved.

[0066] The mixed density of the electrode active material layer can be, for example, 1 g / cm 3 to 5 g / cm 3 , 2 g / cm 3 to 5 g / cm 3 , 3 g / cm 3 to 5 g / cm 3 , or 3 g / cm 3 to 4 g / cm 3 . The mixed density of the electrode active material layer can be derived by measuring the volume and weight of the electrode active material layer included in the prepared electrode. When the electrode active material layer has the mixed density in these ranges, the lithium battery including the electrode can provide both improved energy density and excellent high-rate characteristics.

[0067] The binder included in the electrode active material layer can be, for example, a dry binder. The dry binder can be, for example, a binder that is not impregnated, not dissolved, or not dispersed in a solvent. The dry binder can be, for example, a binder that does not include or does not contact a solvent.

[0068] The dry binder can be, for example, a fibrillated binder. The fibrillated binder can function as a matrix that supports and joins the electrode active material and other components included in the electrode active material layer. In a scanning electron microscope image of a cross section of the electrode, the fibrillated binder can be identified as, for example, having a fiber shape. The fibrillated binder can have, for example, an aspect ratio of 10 or more, 20 or more, 50 or more, or 100 or more. The dry binder can be, for example, polytetrafluoroethylene (PTFE), polyvinylidene-hexafluoropropylene (PVDF-HFP) copolymer, polyvinylidene fluoride (PVDF), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, cellulose, polyvinylpyrrolidone, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or a copolymer thereof, etc., but is not necessarily limited thereto, and the dry binder can be any binder used to manufacture a dry electrode. The dry binder can include, for example, a fluorine-based binder. The fluorine-based binder can be, for example, polytetrafluoroethylene (PTFE), polyvinylidene-hexafluoropropylene (PVDF-HFP) copolymer, or polyvinylidene fluoride (PVDF). The amount of the dry binder included in the electrode active material layer can be, for example, about 1 wt% to about 10 wt% or about 1 wt% to about 5 wt% based on the total weight of the electrode active material layer. As the electrode active material layer includes the dry binder in this amount range, the adhesion of the electrode can be improved and the high energy density of the electrode can be maintained.

[0069] The electrode active material layer can further include, for example, an electrically conductive material. The electrically conductive material can be, for example, a dry electrically conductive material. The dry electrically conductive material can be, for example, an electrically conductive material that is not impregnated, not dissolved, or not dispersed in a solvent. The dry electrically conductive material can be, for example, an electrically conductive material that does not include or does not contact a solvent. The dry electrically conductive material can be, for example, a carbon-based electrically conductive material, a metal-based electrically conductive material, or a combination thereof. The dry electrically conductive material can be, for example, a carbon-based electrically conductive material. The carbon-based electrically conductive material can be carbon black, graphite fine particles, natural graphite, artificial graphite, acetylene black, ketjen black, carbon fibers, and carbon nanotubes, and is not limited thereto, and can be any material used as a carbon-based electrically conductive material in the art. The amount of the dry electrically conductive material included in the electrode active material layer can be, for example, about 1 wt% to about 10 wt% or about 1 wt% to about 5 wt% based on the total weight of the electrode active material layer. Since the electrode active material layer includes the dry electrically conductive material in this amount range, the electrically conductive properties of the electrode can be improved and the high energy density of the electrode can be maintained.

[0070] The electrode active material layer can be, for example, a self-supporting film. In an embodiment, the electrode active material layer can maintain a film shape without a support. Accordingly, the electrode active material layer can be prepared as a separate self-supporting film and then placed on the electrode current collector. Since it is manufactured in a dry process, the electrode active material layer can not include a processing solvent that is intentionally added. For example, a residual processing solvent can not be included. Although a trace amount of an unintentional solvent can remain in the electrode active material layer, the solvent is not a processing solvent that is intentionally added. Accordingly, the electrode active material layer is distinguished from a wet electrode active material layer that is prepared by mixing components and a processing solvent and then removing some or all of the processing solvent therefrom through drying.

[0071] The electrode current collector can additionally include a coating layer disposed on one surface or both surfaces of the electrode current collector.

[0072] The material constituting the electrode current collector can be any material that does not react with lithium (i.e., a material that does not form an alloy or a compound with lithium and has electrical conductivity). The metal substrate can be made of, for example, a metal or an alloy. The metal substrate can be, for example, indium (In), copper (Cu), magnesium (Mg), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), zinc (Zn), aluminum (Al), germanium (Ge), lithium (Li), or an alloy thereof. The electrode current collector can have, for example, a form selected from the group consisting of a sheet, a foil, a film, a plate, a porous body, a mesoporous body, a through-hole-containing body, a polygonal ring body, a net body, a foam body, and a non-woven body. However, the electrode current collector is not limited thereto, and can be in any form used in the art. For example, the electrode current collector can include a base film and a metal layer disposed on one side or both sides of the base film. For example, the base film can include a polymer. For example, the polymer can include polyethylene terephthalate (PET), polyethylene (PE), polypropylene (PP), polybutylene terephthalate (PBT), polyimide (PI), or a combination thereof. For example, the metal layer can include copper (Cu), stainless steel, titanium (Ti), iron (Fe), cobalt (Co), nickel (Ni), or an alloy thereof. The electrode current collector has a structure including a base film and at least one coating layer on the base film. Accordingly, the weight of the electrode can be reduced, and the energy density of the lithium battery can be improved.

[0073] In an embodiment, the coating layer can be disposed directly on one side or both sides of the electrode current collector. Accordingly, another layer can not be disposed between the electrode current collector and the coating layer. Since the coating layer is disposed directly on one side or both sides of the electrode current collector, the bonding force between the electrode current collector and the electrode active material layer can be further increased. The thickness of the coating layer can be, for example, 30% or less of the thickness of the electrode current collector. The thickness of the coating layer can be, for example, about 0.01% to about 30%, about 0.1% to about 30%, about 0.5% to about 30%, about 1% to about 25%, about 1% to about 20%, about 1% to about 15%, about 1% to about 10%, about 1% to about 5%, or about 1% to about 3% of the thickness of the electrode current collector. The thickness of the coating layer can be, for example, about 10 nm to about 5 µm, about 50 nm to about 5 µm, about 200 nm to about 4 µm, about 500 nm to about 3 µm, about 500 nm to about 2 µm, about 500 nm to about 1.5 µm, or about 700 nm to about 1.3 µm. When the coating layer has these thickness ranges, the bonding force between the electrode current collector and the electrode active material layer can be further enhanced, and an increase in the interfacial resistance can be suppressed.

[0074] The coating layer can include, for example, a binder. Since the coating layer includes a binder, the adhesion between the electrode current collector and the electrode active material layer can be further improved. The binder included in the coating layer can be, for example, a conductive binder or a non-conductive binder. The conductive binder can be, for example, an ionically conductive binder and / or an electronically conductive binder. A binder having both ionically conductive and electronically conductive properties can belong to both ionically conductive and electronically conductive binders. The ionically conductive binder can be, for example, polystyrene sulfonate (PSS), polyvinylidene-hexafluoropropylene copolymer (PVDF-HFP), polyvinyl fluoride (PVF), polyvinylidene fluoride (PVDF), poly(methyl methacrylate) (PMMA), polyethylene oxide (PEO), polyethylene glycol (PEG), polyacrylonitrile (PAN), polytetrafluoroethylene (PTFE), poly(ethylene dioxythiophene) (PEDOT), polypyrrole (PPY), polyaniline, or polyacetylene. The ionically conductive binder can include a polar functional group. The ionically conductive binder including a polar functional group can be, for example, Nafion, Aquivion, Flemion, Gore, Aciplex, Morgane ADP, sulfonated poly(ether ether ketone) (SPEEK), sulfonated poly(arylene ether ketone ketone sulfone) (SPAEKKS), sulfonated poly(arylene ether ketone) (SPAEK), poly[bi(benzimidazobenzisoquinolinone)] (SPBIBI), poly(styrene sulfonate) (PSS), lithium 9,10-diphenylanthracene-2-sulfonate (DPASLi + ), or the like. The conductive binder can be, for example, polyacetylene, polythiophene, polypyrrole, poly(p-phenylene), poly(phenylenevinylene), poly(phenylene sulfide), polyaniline, or the like. The coating layer can be, for example, a conductive layer including a conductive polymer. The binder included in the coating layer can be selected from, for example, the binder included in the electrode active material layer. The coating layer can contain the same binder as the binder in the electrode active material layer. The binder included in the coating layer can be, for example, a fluorine-based binder. The fluorine-based binder included in the coating layer can be, for example, polyvinylidene fluoride (PVDF). In an embodiment, the coating layer can be disposed on the electrode current collector by a dry method or a wet method. The coating layer can be, for example, an adhesion layer including a binder.

[0075] The coating layer can include, for example, a carbonaceous conductive material. The carbonaceous conductive material included in the coating layer can be selected from the carbonaceous conductive material included in the electrode active material layer. The coating layer can contain the same carbonaceous conductive material as the carbonaceous conductive material in the electrode active material layer. Since the coating layer includes a carbonaceous conductive material, the coating layer can be, for example, a conductive layer. The coating layer can be, for example, a conductive layer including a binder and a carbonaceous conductive material.

[0076] In an embodiment, the coating layer can be disposed on the electrode current collector by deposition such as chemical vapor deposition (CVD) or physical vapor deposition (PVD) by a dry method. In an embodiment, the coating layer can be disposed on the electrode current collector by a wet method such as spin coating, dip coating, etc. In an embodiment, the coating layer can be disposed on the electrode current collector by depositing a carbonaceous conductive material on the electrode current collector via deposition. The coating layer formed by dry coating can consist of the carbonaceous conductive material and can not include a binder. Alternatively, the coating layer can be disposed on the electrode current collector by coating a composition including a carbonaceous conductive material, a binder, and a solvent on a surface of the electrode current collector and then drying it. The coating layer can have a single layer structure or a multi-layer structure including a plurality of layers.

[0077] The electrode current collector can have a reduced thickness compared to the electrode current collector included in the electrode of the related art. Accordingly, the electrode according to an embodiment can be distinguished from the electrode of the related art including a thick film current collector by including a thin film current collector. Since the electrode according to an embodiment includes a thin film current collector having a reduced thickness, the thickness of the electrode active material layer in the electrode including the thin film current collector can be relatively increased. Accordingly, the energy density of a lithium battery including such an electrode is increased. The thickness of the electrode current collector including the metal base and the coating layer can be, for example, less than 15 µm, less than 14.5 µm, or less than 14 µm. The thickness of the electrode current collector can be, for example, from about 0.1 µm to about 15 µm, from about 1 µm to about 14.5 µm, from about 2 µm to about 14 µm, from about 3 µm to about 14 µm, from about 5 µm to about 14 µm, or from about 10 µm to about 14 µm.

[0078] When the electrode active material layer is measured using a surface and interfacial measuring analysis system (SAICAS), the perpendicular force (Fz) with respect to the depth of the electrode active material layer from a first point spaced apart by 5% from the surface of the electrode active material layer in a direction from the surface of the electrode active material layer to the electrode current collector to a second point spaced apart by 5% from the surface of the electrode current collector in a direction from the surface of the electrode current collector to the electrode active material layer is increased as the depth of the electrode active material layer increases. VRThe rate of change of the vertical relative force (Frel) can be, for example, 300% or less. The rate of change of the vertical relative force can be, for example, about 10% to about 300%, about 10% to about 250%, about 10% to about 200%, about 10% to about 150%, or about 10% to about 100%. The second point spaced 5% from the surface of the electrode current collector in the direction from the surface of the electrode current collector to the electrode active material layer, relative to the entire thickness of the electrode active material layer, can be, for example, a point spaced 95% from the surface of the electrode active material layer in the direction from the surface of the electrode active material layer to the electrode current collector. The vertical relative force can be calculated by Equation 1. For the SAICAS measurement method, reference can be made to Evaluation Example 1.

[0079] < Equation 1 >

[0080] The vertical relative force (Frel) can be calculated by Equation 1. VR The rate of change of the vertical relative force (Frel) = [(maximum value of the vertical relative force (Frel) - minimum value of the vertical relative force (Frel)) / minimum value of the vertical relative force (Frel)] x 100 VR1 VR1 VR1

[0081] Since the rate of change of the vertical relative force is 300% or less when SAICAS is measured on the electrode active material layer, the uniformity of the distribution of components in the electrode can be improved. In addition, since the increase in the side reaction and internal resistance due to the non-uniform distribution of components in the electrode active material layer is suppressed, the reversibility of the electrode reaction can be improved. Even in the case of an electrode having a high loading amount, the cycle characteristics of the lithium battery can be improved. In addition, when the electrode includes an intermediate layer, the adhesion of the electrode active material layer to the electrode current collector is further improved, and the internal resistance of the electrode is reduced. Thus, the cycle characteristics of the lithium battery including such an electrode can be improved.

[0082] When SAICAS is measured on the electrode active material layer, the second horizontal force (F2) at a second point spaced 10% from the surface of the electrode current collector in the direction from the surface of the electrode current collector to the electrode active material layer (e.g., the depth direction), relative to the entire depth from the surface of the electrode active material layer to the surface of the electrode current collector, can be different from the first horizontal force (F1) at a first point spaced 10% from the surface of the electrode active material layer in the direction from the surface of the electrode active material layer to the electrode current collector. H2 H1 ​​​​The horizontal force ratio can be, for example, 50% or more. The horizontal force ratio can be, for example, about 50% to about 100%, about 60% to about 100%, about 70% to about 100%, about 80% to about 100%, or about 90% to about 100%. The second point spaced 10% from the surface of the electrode current collector in the direction from the surface of the electrode current collector to the electrode active material layer, relative to the entire thickness of the electrode active material layer, can be, for example, a point spaced 90% from the surface of the electrode active material layer in the direction from the surface of the electrode active material layer to the electrode current collector. For example, the horizontal force ratio is represented as Equation 2. For the SAICAS measurement method, reference can be made to Evaluation Example 2.

[0083] < Equation 2 >

[0084] Horizontal force ratio = [Second horizontal force (F H2 ) / First horizontal force (F H1 )] x 100

[0085] When SAICAS is measured, the uniformity of the distribution of components in the electrode can be further improved due to the horizontal force ratio of 50% or more. Since the electrode has a horizontal force ratio in these ranges, the cycle characteristics of a lithium battery including the electrode are further improved.

[0086] The electrode described above can be, for example, a positive electrode. The positive electrode can include a positive electrode active material layer, and the positive electrode active material layer can include a positive electrode active material.

[0087] As the positive electrode active material included in the positive electrode active material layer, any lithium metal oxide can be used without limitation, as long as it is used in the art.

[0088] The positive electrode active material can be, for example, a composite oxide of lithium and one or more types of metals selected from cobalt, manganese, nickel, and combinations thereof. The positive electrode active material can be, for example, a compound represented by one of the following formulas: Li a A 1-b B b D2(wherein, 0.90 ≤ a ≤ 1, and 0 ≤ b ≤ 0.5); Li a E 1-b B b O 2-c D c (wherein, 0.90 ≤ a ≤ 1, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); LiE 2-b B b O 4-c D c (wherein, 0 ≤ b ≤ 0.5, and 0 ≤ c ≤ 0.05); Li a Ni 1-b-c Co b Bc D α (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 (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 F2(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 (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 α (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 F2(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(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 GeO2(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(0.90≤a≤1 and 0.001≤b≤0.1); Li a CoG b O2(0.90≤a≤1 and 0.001≤b≤0.1); Lia MnG b O2(0.90≤a≤1 and 0.001≤b≤0.1); Li a Mn2G b O4(0.90≤a≤1 and 0.001≤b≤0.1); QO2; QS2; LiQS2; V2O5; LiV2O5; LiIO2; LiNiVO4; Li (3-f) J2(PO4)3(0≤f≤2); Li (3-f) Fe2(PO4)3(0≤f≤2); and LiFePO4.

[0089] In the formulae representing these compounds, A is Ni, Co, Mn, or a combination thereof; B is Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, a rare earth element, or a combination thereof; D is O, F, S, P, or a combination thereof; E is Co, Mn, or a combination thereof; F is F, S, P, or a combination thereof; G is Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, or a combination thereof; Q is Ti, Mo, Mn, or a combination thereof; I is Cr, V, Fe, Sc, Y, or a combination thereof; and J is V, Cr, Mn, Co, Ni, Cu, or a combination thereof.

[0090] Compounds in which a coating is provided on the surface of these compounds can be used, and mixtures of these compounds and the compounds provided with a coating can also be used. The coating provided on the surface of these compounds can include a coating element compound such as an oxide of a coating element, a hydroxide of a coating element, a hydroxy oxide of a coating element, an oxy carbonate of a coating element, or a hydroxy carbonate of a coating element. The compound constituting the coating is amorphous or crystalline. The coating element included in the coating can be Mg, Al, Co, K, Na, Ca, Si, Ti, V, Sn, Ge, Ga, B, As, Zr, or a mixture thereof. The method of forming the coating is selected within a range that does not adversely affect the physical properties of the positive electrode active material. The coating method can be, for example, a spray coating method, a dipping method, or the like. A detailed description of the coating method will be omitted because it can be well understood by those skilled in the art.

[0091] The amount of the positive electrode active material included in the positive electrode active material layer can be, for example, about 80 wt% to about 98 wt% or about 90 wt% to about 98 wt% based on the total weight of the positive electrode active material layer.

[0092] The positive electrode active material can be, for example, a composite positive electrode active material.

[0093] The composite positive electrode active material can include, for example, a core including a lithium transition metal oxide and a shell located on the core and conformal to the core, wherein the shell includes at least one type of first metal oxide represented by the formula M a O b (0 < a ≤ 3, 0 < b < 4, and when a is 1, 2, or 3, b is not an integer) and graphene, wherein the first metal oxide is located inside a matrix of the graphene, and M is at least one metal selected from Groups II to XIII, Group XV, and Group XVI of the periodic table, the lithium transition metal oxide includes nickel, and the amount of nickel is 80 mol% or more, based on the total number of moles of transition metals. The shell including the first metal oxide and the carbonaceous material is disposed on and / or conformal to the core of the composite positive electrode active material.

[0094] Due to aggregation, uniform coating of a conventional carbonaceous material on the core is difficult. On the other hand, the composite positive electrode active material uses a composite including a plurality of first metal oxides disposed inside a matrix of the carbonaceous material, thereby preventing aggregation of the carbonaceous material and placing a uniform shell on the core. Thus, contact between the core and the electrolyte is effectively blocked, thereby preventing side reactions due to contact between the core and the electrolyte. Furthermore, reduction of nickel ions (Ni 3+ ->Ni 2+) and mixing of cations due to the electrolyte, thereby preventing formation of a resistive layer such as a NiO phase. In addition, elution of nickel ions is also suppressed. The carbonaceous material can be, for example, a crystalline carbonaceous material. The carbonaceous material can be a carbonaceous nanostructure. The carbonaceous material can be graphene. In this case, since the shell including graphene has flexibility, volume change of the composite positive electrode active material is easily accepted during charging and discharging, and cracking of the composite positive electrode active material is suppressed. Since graphene has high electronic conductivity, the interfacial resistance between the composite positive electrode active material and the electrolyte is reduced. Therefore, although the shell including graphene is introduced, the internal resistance of the lithium battery is maintained or reduced. In addition, since the first metal oxide has voltage resistance, deterioration of the lithium transition metal oxide included in the core during charging and discharging at a high voltage can be prevented. Therefore, the cycle characteristics and high-temperature stability of the lithium battery including the composite positive electrode active material are improved. The shell can include, for example, one first metal oxide or two or more different first metal oxides. In addition, in the composite positive electrode active material, the lithium transition metal oxide has a nickel content of 80 mol% or more based on the total number of moles of transition metals, and the shell including the first metal oxide and the carbonaceous material is disposed on the core, thereby simultaneously providing a high discharge capacity and cycle characteristics. Therefore, the composite positive electrode active material having a nickel content of 80 mol% or more can provide improved capacity and excellent life characteristics compared to a composite positive electrode active material having a relatively low nickel content. The metal included in the first metal oxide can be at least one selected from Al, Nb, Mg, Sc, Ti, Zr, V, W, Mn, Fe, Co, Pd, Cu, Ag, Zn, Sb, and Se.

[0095] The first metal oxide can be, for example, at least one selected from Al2O z (0 < z < 3), NbO x (0 < x < 2.5), MgO x (0 < x < 1), Sc2O z (0 < z < 3), TiO y (0 < y < 2), ZrO y (0 < y < 2), V2O z (0 < z < 3), WO y (0 < y < 2), MnO y (0 < y < 2), Fe2O z (0 < z < 3), Co3O w (0 < w < 4), PdO x (0 < x < 1), CuO x (0 < x < 1), AgO x (0 < x < 1), ZnO x (0 < x < 1), Sb2Oz (0 < z < 3) and SeO y (0 < y < 2). Since this first metal oxide is disposed in the carbonaceous material matrix, the uniformity of the shell disposed on the core is improved, and further the voltage resistance of the composite positive electrode active material is improved. For example, the shell includes Al2O x (0 < x < 3). The shell can also include at least one type of second metal oxide represented by M a O c (0 < a < 3, 0 < c < 4, when a is 1, 2 or 3, c is an integer). M is at least one metal selected from Groups II to XIII, Group XV and Group XVI of the periodic table. For example, the second metal oxide includes the same metal as the first metal oxide, and the ratio c / a of c to a in the second metal oxide is larger than the ratio b / a of b to a in the first metal oxide. For example, c / a > b / a. 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. The first metal oxide is a reduction product of the second metal oxide. The first metal oxide is obtained by reducing a part or all of the second metal oxide. Therefore, the first metal oxide has a lower oxygen content and a higher metal oxidation value than the second metal oxide. For example, the shell includes Al2O x(0 < x < 3) and Al2O3 as a second metal oxide. In the composite positive electrode active material, for example, the carbonaceous material included in the shell is chemically bonded to the transition metal of the lithium transition metal oxide included in the core through a chemical bond. The carbon atom (C) of the carbonaceous material in the shell is chemically bonded to the transition metal (Me) of the lithium transition metal oxide using an oxygen atom as an intermediate through a C-O-Me bond (for example, a C-O-Ni bond). The carbonaceous material included in the shell is chemically bonded to the lithium transition metal oxide included in the core to make the core and the shell a composite. Thus, the composite of the core and the shell is distinguished from a simple physical mixture of the carbonaceous material and the lithium transition metal oxide. Furthermore, the first metal oxide included in the shell and the carbonaceous material are chemically bonded through a chemical bond. Here, the chemical bond is a covalent bond or an ionic bond. The covalent bond is, for example, a bond including at least one of an ester group, an ether group, a carbonyl group, an amide group, a carbonate anhydride group, and an acid anhydride group. The ionic bond can be, for example, a bond including a carboxylic acid ion, an ammonium ion, or an acyl cation group. The thickness of the shell can be, for example, about 1 nm to about 5 mm, about 1 nm to about 1 mm, about 1 nm to about 500 nm, about 1 nm to about 200 nm, about 1 nm to about 100 nm, about 1 nm to about 90 nm, about 1 nm to about 80 nm, about 1 nm to about 70 nm, about 1 nm to about 60 nm, about 1 nm to about 50 nm, about 1 nm to about 40 nm, about 1 nm to about 30 nm, about 1 nm to about 20 nm, or about 1 nm to about 10 nm. When the thickness of the shell is in the above range, an increase in internal resistance of a lithium battery including the composite positive electrode active material is suppressed.

[0096] The amount of the complex included in the composite cathode active material can be 3 wt% or less, 2 wt% or less, 1 wt% or less, 0.5 wt% or less, or 0.2 wt% or less, based on the total weight of the composite cathode active material. The amount of the complex can be about 0.01 wt% to about 3 wt%, about 0.01 wt% to about 1 wt%, about 0.01 wt% to about 0.7 wt%, about 0.01 wt% to about 0.6 wt%, about 0.1 wt% to about 0.5 wt%, about 0.01 wt% to about 0.2 wt%, about 0.01 wt% to about 0.1 wt%, or about 0.03 wt% to about 0.07 wt%, based on the total weight of the composite cathode active material. When the composite cathode active material includes the complex in these ranges, the cycle characteristics of the lithium battery including the composite cathode active material are further improved. The particle diameter of at least one selected from the first metal oxide and the second metal oxide included in the complex can be about 1 nm to about 1 µm, about 1 nm to about 500 nm, about 1 nm to about 200 nm, about 1 nm to about 100 nm, about 1 nm to about 70 nm, about 1 nm to about 50 nm, about 1 nm to about 30 nm, about 3 nm to about 30 nm, about 3 nm to about 25 nm, about 5 nm to about 25 nm, about 5 nm to about 20 nm, or about 7 nm to about 20 nm. Within these nano-range particle diameters, the first metal oxide and / or the second metal oxide can be more uniformly distributed in the matrix of the graphene of the complex. Accordingly, such a complex can be uniformly applied on the core to form a shell. Furthermore, because the first metal oxide and / or the second metal oxide has a particle diameter within this nano-range, the first metal oxide and / or the second metal oxide can be more uniformly located on the core. Accordingly, the first metal oxide and / or the second metal oxide can be uniformly located on the core, thereby more effectively exhibiting a voltage resistance characteristic. The particle diameter of the first metal oxide and / or the second metal oxide can be, for example, an average particle diameter. The average particle diameter of the first metal oxide and the second metal oxide is measured by a measuring device using a laser diffraction method or a dynamic light scattering method. The average particle diameter is measured using a laser scattering particle size distribution meter (e.g., LA-920 of Horiba Corporation), and is a value of a median particle diameter (D50) when metal oxide particles are cumulatively converted to 50% by volume from small particles.

[0097] The core included in the composite cathode active material includes, for example, a lithium transition metal oxide represented by the following Formula 1:

[0098] <Formula 1>

[0099] Li a Ni x Co y M z O 2-b Ab .

[0100] 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 at least one selected from manganese (Mn), niobium (Nb), vanadium (V), magnesium (Mg), gallium (Ga), silicon (Si), tungsten (W), molybdenum (Mo), iron (Fe), chromium (Cr), copper (Cu), zinc (Zn), titanium (Ti), aluminum (Al), and boron (B), and A is F, S, Cl, Br, or a combination thereof.

[0101] The core included in the composite cathode active material can include a lithium transition metal oxide represented by Formula 2 to Formula 4:

[0102] <Formula 2>

[0103] LiNi x Co y Mn z O2,

[0104] wherein 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1,

[0105] <Formula 3>

[0106] LiNi x Co y Al z O2,

[0107] wherein 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < z ≤ 0.2, and x + y + z = 1, and

[0108] <Formula 4>

[0109] LiNi x Co y Al v Mn w O2,

[0110] wherein 0.8 ≤ x ≤ 0.95, 0 ≤ y ≤ 0.2, 0 < v ≤ 0.2, 0 < w ≤ 0.2, and x + y + v + w = 1.

[0111] The above-described electrode can be, for example, a negative electrode. The negative electrode can include a negative electrode active material layer, and the negative electrode active material layer can include a negative electrode active material.

[0112] Any negative active material can be used as long as it is used in the art. For example, the negative active material includes at least one selected from lithium metal, a metal alloyable with lithium, a transition metal oxide, a non-transition metal oxide, and a carbon-based material. Examples of the metal alloyable with lithium include Si, Sn, Al, Ge, Pb, Bi, Sb, Si-Y alloys (Y is an alkali metal, an alkaline earth metal, a Group XIII element, a Group XIV element, a transition metal, a rare earth element, or a combination thereof, other than Si), and Sn-Y alloys (Y is an alkali metal, an alkaline earth metal, a Group XIII element, a Group XIV element, a transition metal, a rare earth element, or a combination thereof, other than Sn). The element Y can be, for example, Mg, Ca, Sr, Ba, Ra, Sc, Y, Ti, Zr, Hf, Rf, V, Nb, Ta, Db, Cr, Mo, W, Sg, Tc, Re, Bh, Fe, Pb, Ru, Os, Hs, Rh, Ir, Pd, Pt, Cu, Ag, Au, Zn, Cd, B, Al, Ga, Sn, In, Ti, Ge, P, As, Sb, Bi, S, Se, Te, Po, or a combination thereof. The transition metal oxide can be, for example, lithium titanium oxide, vanadium oxide, lithium vanadium oxide, or the like. The non-transition metal oxide is, for example, SnO2or SiO x (0 < x < 2). The carbon-based material is, for example, crystalline carbon, amorphous carbon, or a mixture thereof. The crystalline carbon is, for example, graphite (such as amorphous, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite). The amorphous carbon is, for example, soft carbon (low-temperature fired carbon), hard carbon, mesophase pitch carbide, fired coke, or the like.

[0113] The amount of the negative active material included in the negative active material layer can be, for example, about 80 wt% to about 98 wt% or about 90 wt% to about 98 wt%, based on the total weight of the negative active material layer.

[0114] Referring to Figure 5A The electrode 300 according to the embodiment includes the electrode current collector 200 and the electrode active material layer 100 disposed on one surface of the electrode current collector 200, and the electrode active material layer 100 includes the first electrode active material, the second electrode active material, and the binder. The electrode 300 can be, for example, a dry electrode. For example, the first electrode active material and the second electrode active material can each be a dry electrode active material, and the binder can be a dry binder.

[0115] Referring to Figure 5BThe electrode 300 according to the embodiment includes the electrode current collector 200 and the electrode active material layer 100 disposed on both surfaces of the electrode current collector 200, and the electrode active material layer 100 includes the first electrode active material, the second electrode active material, and the binder. The electrode 300 can be, for example, a dry electrode. For example, the first electrode active material and the second electrode active material can each be a dry electrode active material, and the binder can be a dry binder.

[0116] Referring to Figure 5C The electrode 300 according to the embodiment includes the electrode current collector 200, the electrode active material layer 100 disposed on one surface of the electrode current collector 200, in which the electrode active material layer 100 includes the first electrode active material, the second electrode active material, and the binder, and the coating layer 250 between the electrode active material layer 100 and the electrode current collector 200. Except for additionally including the coating layer 250, Figure 5C The electrode according to the embodiment has the same configuration as the electrode according to Figure 5A Since the electrode 300 further includes the coating layer 250, the adhesion of the electrode active material layer 100 to the electrode current collector 200 can be improved.

[0117] Referring to Figure 5D The electrode 300 according to the embodiment includes the electrode current collector 200, the electrode active material layer 100 disposed on both surfaces of the electrode current collector 200, in which the electrode active material layer 100 includes the first electrode active material, the second electrode active material, and the binder, and the coating layer 250 between the electrode active material layer 100 and the electrode current collector 200 on each surface of the electrode current collector 200. Except for additionally including the coating layer 250, Figure 5D The electrode according to the embodiment has the same configuration as the electrode according to Figure 5B Since the electrode 300 further includes the coating layer 250, the adhesion of the electrode active material layer 100 to the electrode current collector 200 can be improved.

[0118] Referring to Figure 6In the electrode 300 according to the embodiment, the electrode active material layer 100 has a first surface S1 and a second surface S2 opposite to the first surface S1, a first side surface SS1 connected to longitudinal ends of the first surface S1 and the second surface S2, and a second side surface SS2 opposite to the first side surface SS1, and a third side surface SS3 connected to lateral ends of the first surface S1 and the second surface S2, and a fourth side surface SS4 opposite to the third side surface SS3. The first domain D1 is defined by the first surface S1, the second surface S2, the third side surface SS3, and the fourth side surface SS4, and includes the electrode current collector 200 disposed between the first surface S1 and the second surface S2. The second domain D2 is defined by the first surface S1, the second surface S2, the third side surface SS3, and the fourth side surface SS4, and is a domain that does not contain the electrode current collector 200 between the first surface S1 and the second surface S2.

[0119] Referring to Figure 6 , the electrode active material layer 100 has a first area A1 defined by a longitudinal first distance L1 and a lateral first distance W1, and the electrode current collector 200 is disposed between the first surface S1 and the second surface S2, and the electrode current collector 200 has a second area A2 defined by a longitudinal second distance L2 and a lateral second distance W2, and the second area A2 of the electrode current collector 200 is 90% or less of the first area A1 of the electrode active material layer 100. For example, the second area A2 of the electrode current collector 200 can be about 10% to about 90%, about 10% to about 80%, about 10% to about 70%, about 10% to about 60%, about 10% to about 50%, about 10% to about 40%, about 10% to about 30%, or about 10% to about 20% of the first area A1 of the electrode active material layer 100. Since the area of the electrode current collector 200 in the electrode 300 is smaller than the area of the electrode active material layer 100, the energy density of the lithium battery 1000 (see Figure 9 ) including the electrode 300 can be further improved.

[0120] Referring to Figure 6For example, the longitudinal second distance L2 of the electrode current collector 200 can be about 10% to about 90%, about 10% to about 80%, about 10% to about 70%, about 10% to about 60%, about 10% to about 50%, about 10% to about 40%, about 10% to about 30%, or about 10% to about 20% of the longitudinal first distance L1 of the electrode active material layer 100. Alternatively, the lateral second distance W2 of the electrode current collector 200 can be less than or equal to 90% of the lateral first distance W1 of the electrode active material layer 100. For example, the lateral second distance W2 of the electrode current collector 200 can be about 10% to about 90%, about 10% to about 80%, about 10% to about 70%, about 10% to about 60%, about 10% to about 50%, about 10% to about 40%, about 10% to about 30%, or about 10% to about 20% of the lateral first distance W1 of the electrode active material layer 100. For example, the longitudinal second distance L2 of the electrode current collector 200 can be 90% or less of the longitudinal first distance L1 of the electrode active material layer 100, and the lateral second distance W2 of the electrode current collector 200 can be 90% or less of the lateral first distance W1 of the electrode active material layer 100. Since the electrode current collector 200 has such a size, the energy density of the lithium battery 1000 including the electrode 300 can be further improved.

[0121] Referring to Figure 6 The electrode current collector 200 is exposed to three or less side surfaces among the first side surface SS1, the second side surface SS2, the third side surface SS3, and the fourth side surface SS4 included in the electrode active material layer 100. Since the electrode current collector 200 has an area smaller than that of the electrode active material layer 100, the electrode current collector 200 can be exposed to some of the side surfaces of the electrode active material layer 100, for example, three, two, or one side surface thereof. Since the number of the side surfaces of the electrode active material layer 100 to which the electrode current collector 200 is exposed is reduced, the possibility of a short circuit through the side surface of the electrode active material layer 100 is reduced, so that the safety of the lithium battery 1000 is improved.

[0122] Referring to Figure 6The electrode current collector 200 has a tab T extending to the outside of the electrode active material layer 100 through at least two sides selected from the first side surface SS1, the second side surface SS2, the third side surface SS3, and the fourth side surface SS4. For example, the tab T extends to the outside of the electrode active material layer 100 through the first side surface SS1 and / or the second side surface SS2. Alternatively, the tab T extends to the outside of the electrode active material layer 100 through the third side surface SS3 and / or the fourth side surface SS4. Since the tab T extends to the outside of the electrode active material layer 100 through one side or two opposite sides, short circuiting caused by a plurality of adjacent tabs can be prevented.

[0123] Referring to Figures 7A to 7F , the electrode current collector 200 disposed in the portion between the two surfaces of the electrode active material layer 100 can have various shapes and can be disposed at various positions within the electrode active material layer 100. In Figures 7A to 7F , with respect to the electrode active material layer 100 defined by the first side surface SS1, the second side surface SS2, the third side surface SS3, and the fourth side surface SS4, the domain in which the electrode current collector 200 is disposed corresponds to the first domain, and the domain in which the electrode current collector 200 is not contained corresponds to the second domain.

[0124] Referring to Figure 7A , the electrode current collector 200 can be disposed in a portion of the electrode active material layer 100 defined by the first side surface SS1, the second side surface SS2, the third side surface SS3, and the fourth side surface SS4. The electrode current collector 200 is exposed through the first side surface SS1 of the electrode active material layer 100 and includes a tab T extending to the outside of the electrode active material layer 100 through the first side surface SS1. The lateral distance W T of the tab T can be 100% of the lateral second distance W2 of the electrode current collector 200.

[0125] Referring to Figure 7B , the electrode current collector 200 can be disposed in a portion of the electrode active material layer 100 defined by the first side surface SS1, the second side surface SS2, the third side surface SS3, and the fourth side surface SS4. The electrode current collector 200 is exposed through the first side surface SS1, the second side surface SS2, and the third side surface SS3 of the electrode active material layer 100 and includes a tab T extending to the outside of the electrode active material layer 100 through the first side surface SS1. The longitudinal second distance L2 of the electrode current collector 200 can be 100% of the longitudinal first distance L1 of the electrode active material layer 100. The lateral second distance W2 of the electrode current collector 200 can be less than 100% of the lateral first distance W1 of the electrode active material layer 100.

[0126] Referring toFigure 7C The electrode current collector 200 can be disposed in a portion of the electrode active material layer 100 defined by the first side surface SS1, the second side surface SS2, the third side surface SS3, and the fourth side surface SS4. The electrode current collector 200 is exposed through the first side surface SS1, the second side surface SS2, and the fourth side surface SS4 of the electrode active material layer 100, and includes a tab T extending to the outside of the electrode active material layer 100 through the first side surface SS1.

[0127] Referring to Figure 7D The electrode current collector 200 can be disposed in a portion of the electrode active material layer 100 defined by the first side surface SS1, the second side surface SS2, the third side surface SS3, and the fourth side surface SS4. The electrode current collector 200 is exposed through the first side surface SS1, the second side surface SS2, and the fourth side surface SS4 of the electrode active material layer 100, and includes a tab T extending to the outside of the electrode active material layer 100 through the first side surface SS1. The lateral distance W T may be less than 100% of the lateral second distance W2 of the electrode current collector 200.

[0128] Referring to Figure 7E and Figure 7F A plurality of electrode current collectors 200 can be disposed in a portion of the electrode active material layer 100 defined by the first side surface SS1, the second side surface SS2, the third side surface SS3, and the fourth side surface SS4. The plurality of electrode current collectors 200 are spaced apart from each other in the longitudinal direction or the width direction of the electrode active material layer 100. In an embodiment, the plurality of electrode current collectors 200 can be spaced apart from each other at the same interval or at different intervals. The plurality of electrode current collectors 200 can form an angle of 45 degrees or less, 40 degrees or less, 30 degrees or less, 25 degrees or less, 20 degrees or less, 15 degrees or less, less than 10 degrees, and less than 5 degrees with respect to one surface (e.g., at least one of the first surface S1 and the second surface S2 thereof) of the electrode active material layer 100. For example, the plurality of electrode current collectors 200 can form an angle of 0 degrees with respect to one surface of the electrode active material layer 100, i.e., be disposed in parallel with the same. In an embodiment, the plurality of electrode current collectors 200 can be disposed between the first surface S1 and the second surface S2 of the electrode active material layer 100.

[0129] Referring to Figure 8The electrode active material layer 100 includes a first domain D1 in which the electrode current collector 200 is disposed between the first surface S1 and the second surface S2, and a second domain D2 in which the electrode current collector 200 is not disposed between the first surface S1 and the second surface S2. The mixing density of the electrode active material layer 100 included in the second domain D2 can be less than 99%, 98% or less, 97% or less, 96% or less, 95% or less, or 90% or less of the mixing density of the electrode active material layer 100 included in the first domain D1. For example, the mixing density of the electrode active material layer 100 included in the second domain D2 can be about 50% to about 99%, about 60% to about 98%, about 70% to about 97%, about 80% to about 96%, or about 90% to about 95% of the mixing density of the electrode active material layer 100 included in the first domain D1.

[0130] A lithium battery according to an embodiment includes a positive electrode, a negative electrode, and an electrolyte between the positive electrode and the negative electrode, wherein at least one of the positive electrode and the negative electrode is the above-described electrode.

[0131] Referring to Figures 9 to 11 , the lithium battery 1000 includes a positive electrode 300a, a negative electrode 300b, and an electrolyte 400 disposed between the positive electrode 300a and the negative electrode 300b, wherein at least one of the positive electrode 300a and the negative electrode 300b is the above-described electrode. The lithium battery 1000 includes an electrode assembly 500.

[0132] Referring to Figure 9 , the electrode assembly 500 includes a plurality of positive electrodes 300a stacked along a thickness direction thereof, a plurality of negative electrodes 300b each disposed between adjacent ones of the plurality of positive electrodes 300a, and a plurality of electrolytes 400 disposed between the plurality of positive electrodes 300a and the plurality of negative electrodes 300b. The positive electrode 300a includes a positive electrode current collector 200a, and the positive electrode current collector 200a includes a positive electrode tab Ta extending to an outside of a positive electrode active material layer 100a through a side surface SS5 of the electrode assembly 500, and the negative electrode 300b includes a negative electrode current collector 200b including a negative electrode tab Tb extending to an outside of a negative electrode active material layer 100b through another surface SS6 of the electrode assembly 500 opposite to the side surface SS5. The lithium battery 1000 includes the electrode assembly 500. Since the positive electrode tab Ta and the negative electrode tab Tb are disposed on the side surfaces opposite to each other, the possibility of short circuit therebetween is reduced.

[0133] Referring to Figure 10The electrode assembly 500 includes a plurality of positive electrodes 300a stacked in a thickness direction, a plurality of negative electrodes 300b respectively provided between the plurality of positive electrodes 300a, and a plurality of electrolytes 400 provided between the plurality of positive electrodes 300a and the plurality of negative electrodes 300b. The positive electrode 300a includes a positive electrode current collector 200a, and the positive electrode current collector 200a includes a positive electrode tab Ta extending to the outside of the positive electrode active material layer 100a through a side surface SS5 of the electrode assembly 500, and the negative electrode 300b includes a negative electrode current collector 200b including a negative electrode tab Tb extending to the outside of the negative electrode active material layer 100b through the side surface SS5 of the electrode assembly 500. The lithium battery 1000 includes the electrode assembly 500.

[0134] Referring to Figure 11 , the plurality of positive electrode tabs Ta are provided on the side surface SS5 at regular intervals in the thickness direction of the electrode assembly 500, and the plurality of negative electrode tabs Tb are provided at regular intervals in the thickness direction thereof. The plurality of positive electrode tabs Ta are provided adjacent to the side surface SS7 in the width direction of the electrode assembly 500, and the plurality of negative electrode tabs Tb are provided adjacent to the other side surface SS8 opposite to the side surface SS7 in the width direction of the electrode assembly 500. Figure 11 is Figure 10 a front view of the side surface SS5 of the electrode assembly 500. The lithium battery 1000 includes the electrode assembly 500.

[0135] Although the positive electrode tab Ta and the negative electrode tab Tb are provided on the same side, since they are provided to be spaced apart from each other in the width direction, the possibility of short circuit therebetween is reduced.

[0136] The lithium battery 1000 can be, for example, a lithium ion battery, a lithium solid battery, and a lithium air battery.

[0137] The electrolyte included in the lithium battery 1000 can be, for example, a liquid electrolyte or a solid electrolyte. The solid electrolyte can be, for example, an oxide-based solid electrolyte or a sulfide-based solid electrolyte.

[0138] A method of manufacturing an electrode according to an embodiment is provided.

[0139] The method of manufacturing an electrode includes the steps of preparing a dry mixture by dry mixing a first electrode active material, a second electrode active material, a dry conductive material, and a dry binder; forming an electrode active material layer from the dry mixture; roll-pressing the electrode active material layer; and disposing the roll-pressed electrode active material layer on an electrode current collector, wherein the electrode includes the electrode current collector and the electrode active material layer disposed on one surface or both surfaces of the electrode current collector, wherein the electrode active material layer includes the first electrode active material, the second electrode active material, and the binder, the electrode active material layer includes first clusters, wherein the first clusters are agglomerates including a plurality of the first electrode active material, one surface of the electrode active material layer includes first domains including the first clusters, and an area of the first domains is 15% to 60% of a total area of the one surface of the electrode active material layer.

[0140] Since the electrode manufactured by the manufacturing method has the electrode active material layer in which the first domains have an area of 15% to 60% of a total area of the one surface of the electrode active material layer, the electrolyte impregnation property is improved, and the cycle characteristics of a lithium battery using the electrode are improved. In addition, in the electrode manufactured by the manufacturing method, the uniformity of the uniform bonding force distribution within the electrode is improved, and thus the performance of the lithium battery using the electrode is improved.

[0141] First, a dry mixture is prepared by dry mixing a first electrode active material, a second electrode active material, a dry conductive material, and a dry binder. Dry mixing refers to mixing without including a process solvent. The process solvent can be, for example, a solvent used to prepare an electrode slurry. The process solvent can be, for example, water, NMP, or the like, but is not limited thereto, and any process solvent used to prepare an electrode slurry can be used herein. The dry mixing can be performed using a stirrer at a temperature of, for example, 25°C to 65°C. The dry mixing can be performed using a stirrer at a rotation speed of, for example, about 10 rpm to about 10,000 rpm or about 100 rpm to about 10,000 rpm. The dry mixing can be performed using a stirrer for, for example, about 1 minute to about 200 minutes or about 1 minute to about 150 minutes. The first electrode active material and the second electrode active material are each a dry electrode active material.

[0142] The dry mixing can be performed, for example, one or more times. First, a first mixture can be prepared by one-time dry mixing of the electrode active material, the dry conductive material, and the dry binder. The one-time dry mixing can be performed, for example, at a temperature of 25 to 65°C, at a rotation speed of 2000 rpm or less, for 15 minutes or less. The one-time dry mixing can be performed, for example, at a temperature of about 25 to about 65°C, at a rotation speed of about 500 rpm to about 2000 rpm, for about 5 minutes to about 15 minutes. The electrode active material, the dry conductive material, and the dry binder can be uniformly mixed by the one-time dry mixing. Subsequently, a second mixture can be prepared by two-time dry mixing of the electrode active material, the dry conductive material, and the dry binder. The two-time dry mixing can be performed, for example, at a temperature of 25 to 65°C, at a rotation speed of 4000 rpm or more, for 10 minutes or more. The two-time dry mixing can be performed, for example, at a temperature of 25 to 65°C, at a rotation speed of about 4000 rpm to about 9000 rpm, for 10 minutes to 60 minutes. The dry mixture including the fibrillated dry binder can be obtained by the two-time dry mixing.

[0143] The stirrer can be, for example, a kneader. The stirrer can include, for example, a chamber, one or more rotating shafts located inside the chamber and rotating, and blades rotatably coupled to the rotating shafts and located in the longitudinal direction of the rotating shafts. The blades can be, for example, one or more selected from ribbon blades, sigma blades, jet (Z) blades, dispersing blades, and helical blades. By including the blades, the dough-like mixture can be prepared by effectively mixing the electrode active material, the dry conductive material, and the dry binder without a solvent.

[0144] As the dry conductive material, carbon black, graphite fine particles, natural graphite, artificial graphite, acetylene black, ketjen black, carbon fibers; carbon nanotubes; metal powders, metal fibers, or metal tubes of, for example, copper, nickel, aluminum, or silver; or conductive polymers such as polyaniline derivatives can be used, but the disclosure is not limited thereto. Any conductive material can be used as long as it is used in the art. The conductive material can be, for example, a carbonaceous conductive material.

[0145] Examples of the dry binder include vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride, polyacrylonitrile, polymethyl methacrylate, polytetrafluoroethylene (PTFE), a mixture of these polymers, and a styrene butadiene rubber-based polymer, and as a solvent, N-methyl pyrrolidone (NMP), acetone, water, or the like can be used, but the disclosure is not limited thereto, and any solvent used in the art can be used.

[0146] A plasticizer or a pore-forming agent can be further added to the dry mixture to form pores inside the electrode plate.

[0147] The amounts of the electrode active material, the dry conductive material, and the dry binder used in the dry mixture are the same as described above with reference to the electrode.

[0148] The positive electrode uses a positive electrode active material as the electrode active material. The positive electrode active material can be understood by referring to the description provided with reference to the electrode. The negative electrode uses a negative electrode active material as the electrode active material. The negative electrode active material can be understood by referring to the description provided with reference to the electrode.

[0149] Next, an electrode active material layer is formed from the dry mixture.

[0150] In an embodiment, the prepared dry mixture can be put into an extruder and extruded to form an electrode active material layer.

[0151] The electrode active material layer can be extruded in a sheet form. The pressure at the time of extrusion can be, for example, about 4 MPa to about 100 MPa or about 10 MPa to about 90 MPa. The resulting mixture can be a self-supporting film in the form of a sheet.

[0152] The electrode active material layer can be, for example, an electrode active material layer self-supporting film.

[0153] Next, the electrode active material layer is roll-pressed.

[0154] The electrode active material layer in the form of a self-supporting film is roll-pressed to prepare a roll-pressed electrode active material layer.

[0155] The roll-pressing can be, for example, a roll press, a flat press, or the like, but is not necessarily limited thereto. The pressure during roll-pressing can be, for example, 1.0 ton / cm 2 to 10.0 ton / cm 2 When the pressure during roll-pressing is excessively increased, the electrode active material layer can be broken. When the pressure during roll-pressing is too low, the mixing density of the electrode active material layer can be reduced.

[0156] Next, an electrode current collector is provided.

[0157] The electrode current collector can additionally include a coating layer provided on one surface or both surfaces of the electrode current collector.

[0158] The step of providing the electrode current collector can include, for example, providing a coating layer on one surface or both surfaces of the electrode current collector.

[0159] The material for the electrode current collector can be understood by referring to the description provided with reference to the electrode current collector. The positive electrode current collector can be, for example, an aluminum foil. The negative electrode current collector can be, for example, a copper foil.

[0160] When the coating layer is provided on one surface or both surfaces of the electrode current collector, the coating layer can be provided on one surface or both surfaces of the electrode current collector by a dry method or a wet method. The specific coating method can be understood by referring to the description provided with reference to the electrode current collector including the coating layer.

[0161] Next, the rolled electrode active material layer is placed on one surface or both surfaces of the electrode current collector to manufacture an electrode in which the electrode active material layer is provided on one surface or both surfaces of the electrode current collector. For example, the electrode can be manufactured by stacking the rolled electrode active material layer on the electrode current collector.

[0162] A lithium battery is manufactured by the following exemplary method, but the disclosure is not necessarily limited to the method, and the method can be varied according to the desired conditions.

[0163] First, one or all of the positive electrode and the negative electrode can be manufactured according to the electrode manufacturing method described above. Alternatively, when one of the positive electrode and the negative electrode is manufactured by the electrode manufacturing method described above, the other electrode can be manufactured by a wet manufacturing method. For example, the other electrode can be prepared by preparing an electrode slurry including an electrode active material, a conductive material, a binder, and a solvent and coating the prepared electrode slurry on an electrode current collector and drying it. The conductive material and the binder included in the electrode prepared using the wet method can be selected from the conductive material and the binder used in the preparation of the dry electrode.

[0164] Next, a separator interposed between the positive electrode and the negative electrode is prepared.

[0165] Any separator can be used as long as it is commonly used for lithium batteries. As the separator, for example, a separator having low resistance to ion movement of an electrolyte and excellent electrolyte moisture retention capacity is used. The separator can be a non-woven fabric or a woven fabric including at least one selected from glass fiber, polyester, Teflon, polyethylene, polypropylene, polytetrafluoroethylene (PTFE), and combinations thereof. For a lithium ion battery, for example, a rollable separator including polyethylene, polypropylene, or the like is used, and for a lithium ion polymer battery, a separator having excellent organic electrolyte impregnation capacity is used.

[0166] The separator is manufactured by the following exemplary method, but the disclosure is not necessarily limited to the method, and adjustments are made according to the desired conditions.

[0167] First, a polymer resin, a filler, and a solvent are mixed to prepare a separator composition. The separator composition is directly applied to the electrode and dried to form a separator. Alternatively, a film obtained by casting and drying the separator composition on a support and then separating the composition from the support is stacked on the electrode to form a separator.

[0168] The polymer used for manufacturing the separator is not particularly limited, and any polymer can be used as long as it is used for the binder of the electrode plate. For example, as the polymer, a vinylidene fluoride / hexafluoropropylene copolymer, polyvinylidene fluoride (PVDF), polyacrylonitrile, polymethyl methacrylate, or a mixture thereof is used.

[0169] Next, an electrolyte is prepared.

[0170] The electrolyte is, for example, an organic electrolyte. The organic electrolyte is prepared, for example, by dissolving a lithium salt in an organic solvent.

[0171] As the organic solvent, any organic solvent can be used as long as it is used in the art. The organic solvent is, for example, propylene carbonate, ethylene carbonate, fluoroethylene carbonate, butylene carbonate, dimethyl carbonate, diethyl carbonate, methyl ethyl carbonate, methyl propyl carbonate, ethyl propyl carbonate, methyl isopropyl carbonate, dipropyl carbonate, dibutyl carbonate, benzonitrile, acetonitrile, tetrahydrofuran, 2-methyltetrahydrofuran, γ-butyrolactone, dioxolane, 4-methyldioxolane, N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, dioxane, 1,2-dimethoxyethane, sulfolane, dichloroethane, chlorobenzene, nitrobenzene, diethylene glycol, dimethyl ether, or a mixture thereof.

[0172] As the lithium salt, any lithium salt can be used as long as it is used in the art. The lithium salt is, 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)(here, x and y are natural numbers), LiCl, LiI, or a mixture thereof.

[0173] Optionally, the electrolyte can be a solid electrolyte. The solid electrolyte is, for example, boron oxide or lithium oxynitride, but is not limited thereto. Any solid electrolyte can be used as long as it is used in the art. The solid electrolyte can be formed on the negative electrode by a method such as sputtering, or a separate solid electrolyte sheet can be stacked on the negative electrode. The solid electrolyte can be, for example, an oxide-based solid electrolyte or a sulfide-based solid electrolyte.

[0174] Referring to Figure 12 The lithium battery 1 according to the embodiment includes a positive electrode 3, a negative electrode 2, and a separator 4. The positive electrode 3, the negative electrode 2, and the separator 4 can be wound or folded to form a battery structure 7 (see Figure 13). The battery structure 7 is accommodated in the battery case 5. An organic electrolyte is injected into the battery case 5, and the battery case 5 is sealed with the cap assembly 6 to complete the lithium battery 1. The battery case 5 is cylindrical, but is not necessarily limited to this shape, for example, it is square, a thin film, etc.

[0175] Referring to Figure 13 , the lithium battery 1 according to the embodiment includes a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 can be located between the positive electrode 3 and the negative electrode 2, and the positive electrode 3 and the negative electrode 2 and the separator 4 can be wound or folded to form a battery structure 7. The battery structure 7 is accommodated in the battery case 5. An electrode tab 8 that functions as an electrical path for guiding an electric current formed in the battery structure 7 to the outside can be included. An organic electrolyte is injected into the battery case 5 and sealed to complete the manufacture of the lithium battery 1. The battery case 5 can have a rectangular shape, but is not necessarily limited to this shape, and can have, for example, a cylindrical shape, a thin film type, etc.

[0176] Referring to Figure 14 , the lithium battery 1 according to the embodiment includes a positive electrode 3, a negative electrode 2, and a separator 4. The separator 4 is located between the positive electrode 3 and the negative electrode 2 to form a battery structure. The battery structure 7 is stacked as a double monomer structure, and then is accommodated in the battery case 5. An electrode tab 8 that functions as an electrical path for guiding an electric current formed in the battery structure 7 to the outside can be included. An organic electrolyte is injected into the battery case 5 and sealed to complete the manufacture of the lithium battery 1. The battery case 5 can have a rectangular shape, but is not necessarily limited to this shape, and can have, for example, a cylindrical shape, a thin film type, etc.

[0177] The pouch type lithium battery corresponds to the case of the battery case of each of the lithium batteries in which a pouch is used as an electrical path for guiding an electric current formed in the battery structure to the outside. Figures 12 to 14 The pouch type lithium battery includes at least one monomer structure. A separator is located between a positive electrode and a negative electrode to form the monomer structure. After the monomer structure is stacked as a double monomer structure, it is impregnated with an organic electrolyte solution, and is accommodated and sealed in a pouch to complete the pouch type lithium battery. For example, although not shown in the drawings, the positive electrode, the negative electrode, and the separator can be simply stacked and accommodated in the pouch in the form of an electrode assembly. In the embodiment, the positive electrode, the negative electrode, and the separator can be wound or folded as an electrode assembly in the form of a jelly roll, and then are accommodated in the pouch. Then, an organic electrolyte is injected into the pouch, and then the pouch is sealed to complete the manufacture of the lithium battery.

[0178] Since the lithium battery has excellent life characteristics and high rate characteristics, it is used for electric vehicles (EVs). For example, the lithium battery is used for hybrid vehicles such as plug-in hybrid electric vehicles (PHEVs). In addition, the lithium battery is used in fields in which a large amount of electric power storage is required. For example, the lithium battery is used for electric bicycles, power tools, etc.

[0179] A plurality of lithium batteries are stacked to form a battery module, and a plurality of battery modules can form a battery pack. Such a battery pack can be used in any device requiring high capacity and high output. For example, the battery pack can be used for a laptop computer, a smart phone, an electric vehicle, etc. The battery module can include, for example, a plurality of batteries and a frame for holding the plurality of batteries. The battery pack can include, for example, a plurality of battery modules and bus bars connecting the plurality of battery modules. The battery module and / or the battery pack can further include a cooling device. A plurality of battery packs can be controlled by a battery management system. The battery management system can include a battery pack and a battery control device connected to the battery pack.

[0180] The disclosure will be described in greater detail by the following examples and comparative examples. However, these examples are for illustrative purposes only, and the scope of the present disclosure is not limited thereto.

[0181] (Manufacture of lithium battery (half cell))

[0182] Example 1: Dry positive electrode, bimodal positive electrode active material, 7:3 of larger particle diameter positive electrode active material and The weight ratio of the positive active material of a smaller particle size, 3.6 g / cm 3 The mixing density

[0183] (Manufacture of positive electrode)

[0184] LiNi0.8Co0.1Al0.1O2having an average particle size (D50) of 18 μm as a first positive active material, LiNi0.6Co0.2Al0.2O2having an average particle size (D50) of 3 μm as a second positive active material, a carbon conductive material (Denka Black) as a dry conductive material, and polytetrafluoroethylene (PTFE) as a dry binder were put into a blade mixer, and then, dry-mixed at 25°C at a speed of 1000 rpm for 10 minutes to prepare a first mixture in which the first positive active material and the second positive active material, the conductive material, and the binder were uniformly mixed. 0.91 Co 0.05 Al 0.04 O2(hereinafter, referred to as larger particle size NCA91), LiNi0.6Co0.2Al0.2O2having an average particle size (D50) of 3 μm as a second positive active material, a carbon conductive material (Denka Black) as a dry conductive material, and polytetrafluoroethylene (PTFE) as a dry binder were put into a blade mixer, and then, dry-mixed at 25°C at a speed of 1000 rpm for 10 minutes to prepare a first mixture in which the first positive active material and the second positive active material, the conductive material, and the binder were uniformly mixed. 0.91 Co 0.05 Al 0.04 O2(hereinafter, referred to as larger particle size NCA91), LiNi0.6Co0.2Al0.2O2having an average particle size (D50) of 3 μm as a second positive active material, a carbon conductive material (Denka Black) as a dry conductive material, and polytetrafluoroethylene (PTFE) as a dry binder were put into a blade mixer, and then, dry-mixed at 25°C at a speed of 1000 rpm for 10 minutes to prepare a first mixture in which the first positive active material and the second positive active material, the conductive material, and the binder were uniformly mixed.

[0185] Then, in order to fibrillate the binder, the first mixture was subjected to secondary mixing at 25°C at a speed of 1000 rpm for 10 minutes to prepare a second mixture. No separate solvent was used in the preparation of the first mixture and the second mixture.

[0186] The prepared second mixture was put into an extruder and extruded to prepare a self-supporting film of the positive electrode active material layer in the form of a sheet. The pressure at the time of extrusion was 50 MPa.

[0187] The prepared self-supporting film of the positive electrode active material layer was roll-pressed to prepare a roll-pressed self-supporting film of the positive electrode active material layer. The pressure during roll-pressing was 4 ton / cm 2 .

[0188] A positive current collector was prepared in which a carbon layer as a coating was provided on one surface of an aluminum thin film having a thickness of 12 μm.

[0189] The carbon layer was prepared by coating a composition including a carbon conductive material (super P) and polyvinylidene fluoride (PVDF) on the aluminum thin film and then drying the composition. The thickness of the carbon layer on one surface of the aluminum thin film was about 1 μm.

[0190] The roll-pressed self-supporting film of the positive electrode active material layer was placed on one surface of the positive current collector on which the carbon layer was provided.

[0191] The mixed density of the positive electrode active material layer was 3.6 g / cm 3 . The thickness of the positive electrode active material layer was 100 μm.

[0192] Figure 1 A scanning electron microscope image of the surface of the positive electrode prepared in Example 1 is shown. The circled portion is a first domain including a first cluster.

[0193] The area of the first domain including the first cluster was 51.4% of the total area of the surface of the positive electrode active material layer.

[0194] (Making of coin-type battery)

[0195] A coin-type battery was made using the above-prepared positive electrode, lithium metal as a counter electrode, a PTFE separator, and 1.3 M LiPF6EC (ethylene carbonate) + EMC (ethyl methyl carbonate) + DMC (dimethyl carbonate) (3:4:3 by volume) as an electrolyte.

[0196] Example 2: Dry positive electrode, bimodal positive electrode active material, 7:3 of larger particle diameter positive electrode active material and The weight ratio of the positive electrode active material of a smaller particle diameter, 3.0 g / cm 3 of the mixed density

[0197] A positive electrode and a lithium battery were made in the same manner as in Example 1 except that the mixed density of the positive electrode active material layer was changed to 3.0 g / cm 3 .

[0198] The area of the first domain including the first cluster was 57.7% of the total area of the surface of the positive electrode active material layer.

[0199] Figure 2 A scanning electron microscope image of the surface of the positive electrode prepared in Example 2 is shown. The circled portion is a first domain including a first cluster.

[0200] Example 3: Dry positive electrode, bimodal positive electrode active material, 8:2 of larger particle diameter positive electrode active material and The weight ratio of the positive electrode active material of a smaller particle diameter, 3.6 g / cm 3 of the mixed density

[0201] A positive electrode was manufactured in the same manner as in Example 1 except that, as the first positive electrode active material, a larger particle diameter LiNi 0.91 Co 0.05 Al 0.04 O2 (hereinafter, referred to as larger particle diameter NCA91), as the second positive electrode active material, a smaller particle diameter LiNi 0.91 Co 0.05 Al 0.04 O2 (hereinafter, referred to as smaller particle diameter NCA91), as the dry conductive material, a carbon conductive material (super P), and as the dry binder, polytetrafluoroethylene (PTFE) were changed to 76.8:19.2:1.8:2.2, and a positive electrode and a lithium battery were manufactured in the same manner as in Example 1.

[0202] Figure 3A A scanning electron microscope image of the surface of the positive electrode prepared in Example 3 is shown. The circled portion is a first domain including a first cluster.

[0203] Figure 3B An image obtained by image analysis of a scanning electron microscope image of Figure 3A is shown, in which the image is divided into a first domain including a first cluster and a second domain including a second cluster. The first domain is white, and the second domain is black.

[0204] However, among the plurality of clusters included in the white domain, a clustered body having an area of less than 2500 μm 2 is regarded as not forming a first cluster including four or more primary particles, and is excluded from the calculation of the area of the first domain.

[0205] As shown in Figure 3A and Figure 3B , the area of the first domain including the first cluster is 37.1% with respect to the total area of the surface of the positive electrode active material layer.

[0206] Example 4: Dry positive electrode, bimodal positive electrode active material, 8:2 of larger particle diameter positive electrode active material and The weight ratio of the positive electrode active material of a smaller particle diameter, 3.0 g / cm 3 of the mixed density

[0207] LiNi0.8Co0.1Al0.1O2(hereinafter, referred to as large particle size NCA91) having an average particle diameter (D50) of 18 μm as a first positive electrode active material 0.91 Co 0.05 Al 0.04 O2(hereinafter, referred to as large particle size NCA91), LiNi0.8Co0.1Al0.1O2(hereinafter, referred to as small particle size NCA91) having an average particle diameter (D50) of 3 μm as a second positive electrode active material, a carbon conductive material (super P) as a dry conductive material, and polyvinylidene fluoride (PVDF) as a dry binder were mixed in a weight ratio of 67.2:28.8:1.8:2.2 to obtain a mixture. 0.91 Co 0.05 Al 0.04 O2(hereinafter, referred to as large particle size NCA91), LiNi0.8Co0.1Al0.1O2(hereinafter, referred to as small particle size NCA91) having an average particle diameter (D50) of 3 μm as a second positive electrode active material, a carbon conductive material (super P) as a dry conductive material, and polyvinylidene fluoride (PVDF) as a dry binder were mixed in a weight ratio of 67.2:28.8:1.8:2.2 to obtain a mixture. 3 A positive electrode and a lithium battery were manufactured in the same manner as in Example 1 except that the weight ratio of LiNi0.8Co0.1Al0.1O2(hereinafter, referred to as large particle size NCA91) having an average particle diameter (D50) of 18 μm as a first positive electrode active material

[0208] The area of the first domain including the first cluster was 47.2% of the total area of the positive electrode active material layer surface.

[0209] Comparative Example 1: wet positive electrode, bimodal positive electrode active material, 3.6 g / cm 3 of the mixture density

[0210] (Manufacture of a positive electrode)

[0211] A positive electrode and a lithium battery were manufactured in the same manner as in Example 1 except that the weight ratio of LiNi0.8Co0.1Al0.1O2(hereinafter, referred to as large particle size NCA91) having an average particle diameter (D50) of 18 μm as a first positive electrode active material 0.91 Co 0.05 Al 0.04 O2(hereinafter, referred to as large particle size NCA91), LiNi0.8Co0.1Al0.1O2(hereinafter, referred to as small particle size NCA91) having an average particle diameter (D50) of 3 μm as a second positive electrode active material, a carbon conductive material (super P) as a dry conductive material, and polyvinylidene fluoride (PVDF) as a dry binder were mixed in a weight ratio of 67.2:28.8:1.8:2.2 to obtain a mixture. 0.91 Co 0.05 Al 0.04 O2(hereinafter, referred to as large particle size NCA91), LiNi0.8Co0.1Al0.1O2(hereinafter, referred to as small particle size NCA91) having an average particle diameter (D50) of 3 μm as a second positive electrode active material, a carbon conductive material (super P) as a dry conductive material, and polyvinylidene fluoride (PVDF) as a dry binder were mixed in a weight ratio of 67.2:28.8:1.8:2.2 to obtain a mixture.

[0212] The slurry rod was coated on one side of an aluminum current collector having a thickness of 15 μm, dried at room temperature, and again dried under vacuum and at 120°C to introduce a positive electrode active material layer to prepare a laminate.

[0213] The prepared laminate was roll-pressed to prepare a positive electrode. The mixture density of the positive electrode active material layer was 3.6 g / cm3 The thickness of the positive electrode active material layer was 100 pm.

[0214] The area of the first domain including the first cluster was 7.8% of the total area of the surface of the positive electrode active material layer.

[0215] Figure 4 A scanning electron microscope image of the surface of the positive electrode prepared in Comparative Example 1 is shown.

[0216] The first positive electrode active material was uniformly distributed on the surface of the positive electrode active material layer, and the second positive electrode active material and the binder were disposed between the first positive electrode active material, so that it was difficult to observe the cluster of the first positive electrode active material.

[0217] (Manufacture of coin-type battery)

[0218] A coin-type battery was manufactured in the same manner as in Example 1, except that the above-prepared positive electrode was used.

[0219] Comparative Example 2: Dry positive electrode, monomodal positive electrode active material of large particle size, 3.6 g / cm3 3 of the mixed density degrees

[0220] A positive electrode and a lithium battery were manufactured in the same manner as in Example 1, except that only LiNi0.8Co0.1Al0.1O2 (hereinafter, referred to as large particle size NCA91) having an average particle size (D50) of 18 pm was used as the positive electrode active material and the positive electrode active material of small particle size was excluded. 0.91 Co 0.05 Al 0.04 O2 (hereinafter, referred to as small particle size NCA91) having an average particle size (D50) of 3 pm was used as the positive electrode active material and the positive electrode active material of large particle size was excluded.

[0221] The area of the first domain including the first cluster was 90.2% of the total area of the surface of the positive electrode active material layer.

[0222] Since the first positive electrode active material was used, most of the first positive electrode active material constituted a cluster.

[0223] Comparative Example 3: Dry positive electrode, monomodal positive electrode active material of small particle size, 3.6 g / cm3 3 of the mixed density degrees

[0224] A positive electrode and a lithium battery were manufactured in the same manner as in Example 1, except that only LiNi0.8Co0.1Al0.1O2 (hereinafter, referred to as small particle size NCA91) having an average particle size (D50) of 3 pm was used as the positive electrode active material and the positive electrode active material of large particle size was excluded. 0.91 Co 0.05 Al 0.04 O2 (hereinafter, referred to as small particle size NCA91) having an average particle size (D50) of 3 pm was used as the positive electrode active material and the positive electrode active material of large particle size was excluded.

[0225] The area of the first domain including the first cluster is 0.9% of the total area of the surface of the positive electrode active material layer.

[0226] Since the second positive electrode active material is used, the second positive electrode active material does not substantially form a cluster.

[0227] Comparative Example 4: Dry positive electrode, bimodal positive electrode active material

[0228] A positive electrode and a lithium battery were manufactured in the same manner as in Example 1, except that the second mixture was put into a mortar mill and further processed for 5 minutes at a speed of 100 rpm, and then put into an extruder and extruded to prepare a sheet-shaped positive electrode active material layer self-supporting film (self-supporting film).

[0229] The area of the first domain including the first cluster is 8.9% of the total area of the surface of the positive electrode active material layer.

[0230] Comparative Example 5: Dry positive electrode, bimodal positive electrode active material

[0231] A positive electrode and a lithium battery were manufactured in the same manner as in Example 1, except that the second mixture was processed in a centrifugal mill at 12,000 rpm for 3 minutes, passed through a 200-μm sieve, and put into an extruder and extruded to prepare a sheet-shaped positive electrode active material layer self-supporting film.

[0232] The area of the first domain including the first cluster is 68% of the total area of the surface of the positive electrode active material layer.

[0233] Reference Example 1: Dry positive electrode, without coating

[0234] A dry positive electrode was manufactured in the same manner as in Example 1, except that an aluminum thin film having a thickness of 10 μm, which was not coated with a carbon layer, was used as a positive electrode current collector.

[0235] Since a part of the positive electrode active material layer was peeled from the positive electrode current collector in the manufactured positive electrode, it was not possible to manufacture a coin-type battery.

[0236] Evaluation Example 1: Evaluation of vertical force of positive electrode active material layer (I)

[0237] The adhesive properties of the positive electrode active material layer included in the positive electrode manufactured in Example 1 and Comparative Example 1 were analyzed using SAICAS (SAICAS EN-EX, Daipla Wintes, JAPAN).

[0238] The vertical force (Fz) according to depth was measured by performing constant velocity analysis using a diamond blade having a width of 1 mm at a gap angle of 10°, at a rake angle of 20°, at a shear angle of 45°, at a horizontal velocity of 4 μm / s, and at a vertical velocity of 0.4 μm / s. V ) according to depth was measured by performing constant velocity analysis using a diamond blade having a width of 1 mm at a gap angle of 10°, at a rake angle of 20°, at a shear angle of 45°, at a horizontal velocity of 4 μm / s, and at a vertical velocity of 0.4 μm / s.

[0239] First, first constant rate analysis is performed from a first position on the surface of the positive electrode active material layer to the surface of the positive electrode current collector, and a blade is moved horizontally along the surface of the positive electrode current collector to remove the positive electrode active material layer. Then, second constant rate analysis is performed at a position 10 μm backward from the first position under the same conditions as the first constant rate analysis. Data measured by the second constant rate analysis is used.

[0240] The vertical force of the positive electrode active material layer is measured with respect to the positive electrode active material layer, and the measured data is normalized to the bonding force map area to derive the vertical relative force (F VR ) according to the depth of the positive electrode active material layer.

[0241] For the vertical force of the positive electrode active material layer, data measured with respect to the total thickness of the positive electrode active material layer in a profile from a first point spaced 5% from the surface of the positive electrode active material layer to a second point spaced 5% from the surface of the electrode current collector is used. That is, data near the surface of the positive electrode active material layer and data near the surface of the electrode current collector are excluded to prevent measurement error.

[0242] From the derived vertical relative force (F VR ) data of the positive electrode active material layer, the rate of change of the vertical relative force (F VR ) is calculated using Equation 1 below. In addition, the arithmetic mean is calculated from the derived vertical relative force (F VR ) data of the positive electrode active material layer.

[0243] < Equation 1 >

[0244] Rate of change of vertical relative force (F VR ) = [(Maximum value of vertical relative force - Minimum value of vertical relative force) / Minimum value of vertical relative force] x 100

[0245] As a result of measurement, the rate of change of the vertical relative force of the positive electrode active material layer included in the positive electrode of Example 1 was 200% or less.

[0246] Therefore, it was confirmed that the positive electrode active material layer had a uniform bonding force and composition distribution regardless of the position along the thickness direction.

[0247] On the contrary, in the positive electrode active material layer included in the positive electrode of Comparative Example 1, the rate of change of the bonding force in the vertical direction exceeded 1000%.

[0248] Therefore, it was confirmed that the positive electrode active material layer of Comparative Example 1 had a bonding force and composition distribution that significantly varied according to the thickness direction.

[0249] Evaluation Example 2: Evaluation of horizontal force of positive electrode active material layer (II)

[0250] The adhesion properties of the positive electrode active material layer included in the positive electrode prepared in Example 1 and Comparative Example 1 were analyzed using SAICAS (SAICAS EN-EX, Daipla Wintes, JAPAN).

[0251] The horizontal force (F H ) according to the depth was measured by performing constant speed analysis using a diamond blade having a width of 1 mm at a gap angle of 10°, at a rake angle of 20°, at a shear angle of 45°, at a horizontal speed of 4 μm / s, and at a vertical speed of 0.4 μm / s.

[0252] First, a first constant speed analysis was performed from a first position on the surface of the positive electrode active material layer to the surface of the positive electrode current collector, and the blade was moved horizontally 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 backward from the first position under the same conditions as the first constant speed analysis. Data measured by the second constant speed analysis was used.

[0253] The first horizontal force (F H1 ) at a first point spaced 10% from the surface of the positive electrode active material layer and the second horizontal force (F H2 ) at a second point spaced 10% from the surface of the positive electrode current collector were measured with respect to the total thickness of the positive electrode active material layer.

[0254] The horizontal force ratio of the first point and the second point was defined by Equation 2.

[0255] < Equation 2 >

[0256] Horizontal force ratio (%) of first point and second point = [F H2 / F H1 ] x 100

[0257] The measurement results showed that the horizontal relative force ratio of the positive electrode active material layer of Example 1 was 70% or more.

[0258] In contrast, the horizontal force ratio of the positive electrode active material layer of Comparative Example 1 was less than 50%.

[0259] That is, the horizontal relative force ratio of the positive electrode active material layer of Example 1 was increased compared to the horizontal relative force ratio of the positive electrode active material layer of Comparative Example 1.

[0260] Accordingly, it was confirmed that the positive electrode active material layer of Example 1 had a more uniform bonding force and composition distribution compared to the positive electrode active material layer of Comparative Example 1.

[0261] Evaluation Example 3: Evaluation of charge and discharge characteristics at room temperature

[0262] Each of the lithium batteries manufactured in Example 1 to Example 4 and Comparative Example 1 to Comparative Example 5 was charged at a constant current of 0.1C rate at 25°C until the voltage reached 4.4V (vs. Li), and then cut off at a current of 0.05C rate while maintaining the voltage at 4.4V in constant voltage mode. Subsequently, each of the lithium batteries was discharged at a constant current of 0.1C rate until the voltage reached 2.8V (vs. Li) (formation cycle).

[0263] The lithium battery that had undergone the formation cycle was charged at a constant current of 0.5C rate at 25°C until the voltage reached 4.4V (vs. Li). Then, the lithium battery was discharged at a constant current of 0.5C rate until the voltage reached 2.8V (vs. Li) during discharging, and the cycle was repeated under the same conditions until the 100th cycle (repeated 100 times).

[0264] In all of the charge / discharge cycles, a stop time of 10 minutes was provided after each charge / discharge cycle. Some of the results in the charge and discharge experiments at room temperature are shown in Table 1 below. The capacity retention rate at the 100th cycle was defined by Equation 3 below.

[0265] < Equation 3 >

[0266] Capacity retention rate [%] = [discharge capacity at the 100th cycle / discharge capacity at the 1st cycle] x 100

[0267] [Table 1]

[0268] First domain area [%] Capacity retention rate [%] Example 1 51.4 94.6 Example 2 57.7 93.4 Example 3 37.1 95.4 Example 4 47.2 93.5 Comparative Example 1 7.8 93.3 Comparative Example 2 90.2 90.4 Comparative Example 3 0.9 87.8 Comparative Example 4 8.9 92.8 Comparative Example 5 68 93.4

[0269] As shown in Table 1, the lithium batteries of Example 1 to Example 4 had improved room temperature life characteristics compared to the lithium batteries of Comparative Example 1 to Comparative Example 5.

[0270] Evaluation Example 4: Evaluation of room temperature high rate characteristics

[0271] Each of the lithium batteries manufactured in Example 1 to Example 4 and Comparative Example 1 to Comparative Example 5 was charged at a constant current of 0.1C rate at 25°C until the voltage reached 4.4V (vs. Li), and then cut off at a current of 0.05C rate while maintaining the voltage at 4.4V in constant voltage mode. Subsequently, each of the lithium batteries was discharged at a constant current of 0.1C rate until the voltage reached 2.8V (vs. Li) (formation cycle).

[0272] The lithium battery that had undergone the formation cycle was charged at a constant current at a rate of 0.2 C at 25°C until the voltage reached 4.4 V (vs. Li). Subsequently, the lithium battery was discharged at a constant current at a rate of 0.2 C until the voltage reached 2.8 V (vs. Li) (1st cycle).

[0273] The lithium battery that had undergone the formation cycle was charged at a constant current at a rate of 0.2 C at 25°C until the voltage reached 4.4 V (vs. Li). Subsequently, the lithium battery was discharged at a constant current at a rate of 0.33 C until the voltage reached 2.8 V (vs. Li) (2nd cycle).

[0274] The lithium battery that had undergone the formation cycle was charged at a constant current at a rate of 0.2 C at 25°C until the voltage reached 4.4 V (vs. Li). Subsequently, the lithium battery was discharged at a constant current at a rate of 0.5 C until the voltage reached 2.8 V (vs. Li) (3rd cycle).

[0275] The lithium battery that had undergone the formation cycle was charged at a constant current at a rate of 0.2 C at 25°C until the voltage reached 4.4 V (vs. Li). Subsequently, the lithium battery was discharged at a constant current at a rate of 1.0 C until the voltage reached 2.8 V (vs. Li) (4th cycle).

[0276] The lithium battery that had undergone the formation cycle was charged at a constant current at a rate of 0.2 C at 25°C until the voltage reached 4.4 V (vs. Li). Subsequently, the lithium battery was discharged at a constant current at a rate of 2.0 C until the voltage reached 2.8 V (vs. Li) (5th cycle).

[0277] The lithium battery that had undergone the formation cycle was charged at a constant current at a rate of 0.2 C at 25°C until the voltage reached 4.4 V (vs. Li). Subsequently, the lithium battery was discharged at a constant current at a rate of 3.0 C until the voltage reached 2.8 V (vs. Li) (6th cycle).

[0278] In all charge / discharge cycles, a stop time of 10 minutes was provided after each charge / discharge cycle. Some of the results of the charge and discharge experiments at room temperature are shown in Table 2 below. The high rate property is defined by Equation 4 below.

[0279] < Equation 4 >

[0280] High rate property [%] = [discharge capacity of the 5th cycle / discharge capacity of the 1st cycle] x 100

[0281] [Table 2]

[0282] First domain area [%] High rate characteristics (2C / 0.2C) [%] Example 1 51.4 65.2 Example 2 57.7 67.4 Example 3 37.1 63.3 Example 4 47.2 69.4 Comparative Example 1 7.8 40.2 Comparative Example 2 90.2 70.1 Comparative Example 3 0.9 50.2 Comparative Example 4 8.9 53.8 Comparative Example 5 68 60.3

[0283] As shown in Table 2, the lithium batteries of Examples 1 to 4 have improved high rate characteristics compared to the lithium batteries of Comparative Example 1 and Comparative Example 5.

[0284] According to one aspect, electrolyte impregnation properties of an electrode can be improved by including, in the electrode, as a first electrode active material, a first cluster of agglomerates.

[0285] Since the electrode has a uniform distribution of components, high rate characteristics of a lithium battery using such an electrode are improved.

[0286] It is to be understood that the embodiments described herein are to be considered in a descriptive sense only and not for purposes of limitation. Descriptions of features or aspects within each embodiment should typically be considered as being applicable to other similar features or aspects in other embodiments. While one or more embodiments have been described with reference to the figures, it will be apparent to those with ordinary skill in the art that various changes in form and details can be made therein without departing from the spirit and scope of the disclosure as defined by the following claims.

Claims

1. An electrode comprising: an electrode current collector; and an electrode active material layer disposed on one surface or both surfaces of the electrode current collector, wherein the electrode active material layer comprises a first electrode active material, a second electrode active material, and a binder, the electrode active material layer comprises a first cluster, wherein the first cluster is a clustered body comprising a plurality of the first electrode active material, one surface of the electrode active material layer comprises a first domain comprising the first cluster, an area of the first domain is 15% to 60% of a total area of the one surface of the electrode active material layer, and the first electrode active material is a larger particle size electrode active material having a particle size larger than a particle size of the second electrode active material, and the second electrode active material is a smaller particle size electrode active material having a particle size smaller than the particle size of the first electrode active material.

2. The electrode of claim 1, wherein, a number of the plurality of the first electrode active material constituting the first cluster is 4 to 200.

3. The electrode of claim 1, wherein, The area occupied by one first cluster on the one surface of the electrode active material layer is 2500 μm 2 or more.

4. The electrode of claim 1, wherein, the one surface of the electrode active material layer further comprises a second domain comprising a second cluster, and the second cluster is a clustered body comprising a plurality of the second electrode active material and the binder.

5. The electrode of claim 1, wherein, both the first electrode active material and the second electrode active material have a bimodal particle size distribution in a particle size distribution profile thereof.

6. The electrode of claim 1, wherein, a particle size ratio of the first electrode active material to the second electrode active material is 3: 1 to 40:

1.

7. The electrode of claim 1, wherein, a particle size of the first electrode active material is 15 pm to 30 pm, and a particle size of the second electrode active material is 1 pm to 6 pm.

8. The electrode of claim 1, wherein, a weight ratio of the first electrode active material to the second electrode active material is 90: 10 to 60:

40.

9. The electrode of claim 1, wherein, the binder is a dry binder, the dry binder comprises a fibrillated binder, and the dry binder comprises a fluorine-based binder.

10. The electrode of claim 1, wherein, the electrode active material layer further comprises a conductive material, the conductive material is a dry conductive material, and the dry conductive material comprises a carbonaceous conductive material.

11. The electrode of claim 1, wherein, the electrode active material layer is a self-supporting film, and the electrode active material layer is free of a residual processing solvent.

12. The electrode of claim 1, wherein, the electrode current collector comprises a base film and a metal layer disposed on one side or both sides of the base film, the base film comprises a polymer, and the polymer comprises polyethylene terephthalate, polyethylene, polypropylene, polybutylene terephthalate, polyimide, or a combination thereof, the metal layer comprises indium, copper, magnesium, stainless steel, titanium, iron, cobalt, nickel, zinc, aluminum, germanium, lithium, or an alloy thereof.

13. The electrode of claim 1, further comprising a coating disposed on the one surface or the two surfaces of the electrode current collector, and a thickness of the coating is 30% or less of the electrode current collector thickness, wherein, the coating layer comprises a binder, the binder comprises at least one selected from a conductive binder and a non-conductive binder, and the binder comprises a fluorine-based binder.

14. The electrode of claim 13, wherein, the coating layer further comprises a carbonaceous conductive material.

15. The electrode of claim 1, wherein, When the electrode active material layer is measured using a surface and interface measuring analysis system, a vertical relative force change rate with respect to a depth from a first point to a second point is 300% or less with respect to an entire thickness of the electrode active material layer, the first point being spaced apart from a surface of the electrode active material layer by 5% in a direction from the surface of the electrode active material layer to an electrode current collector, the second point being spaced apart from a surface of the electrode current collector by 5% in a direction from the surface of the electrode current collector to the electrode active material layer.

16. The electrode of claim 1, wherein, When the electrode active material layer is measured using a surface and interface measuring analysis system, a horizontal force ratio of a second horizontal force at a second point to a first horizontal force at a first point is 50% or more with respect to an entire thickness of the electrode active material layer, the second point being spaced apart from a surface of the electrode current collector by 10% in a direction from the surface of the electrode current collector to the electrode active material layer, the first point being spaced apart from a surface of the electrode active material layer by 10% in a direction from the surface of the electrode active material layer to the electrode current collector. 17.A lithium battery, the lithium battery comprising: a positive electrode; a negative electrode; and an electrolyte between the positive electrode and the negative electrode, wherein, at least one of the positive electrode and the negative electrode is the electrode according to any one of claims 1 to 16.

18. The lithium battery of claim 17, wherein, The electrolyte is a liquid electrolyte or a solid electrolyte. 19.A method of manufacturing an electrode, the method comprising the steps of: preparing a dry mixture by dry mixing a first electrode active material, a second electrode active material, a dry conductive material, and a dry binder; forming an electrode active material layer from the dry mixture; roll-pressing the electrode active material layer; and placing the roll-pressed electrode active material layer on an electrode current collector, wherein, the electrode comprises: the electrode current collector; and the electrode active material layer disposed on one surface or both surfaces of the electrode current collector, wherein, the electrode active material layer comprises the first electrode active material, the second electrode active material, and the binder, the electrode active material layer comprises first clusters, wherein the first clusters are agglomerates comprising a plurality of the first electrode active material, one surface of the electrode active material layer comprises first domains comprising the first clusters, an area of the first domains is 15% to 60% of a total area of the one surface of the electrode active material layer, and the first electrode active material is a larger particle size electrode active material whose particle size is larger than a particle size of the second electrode active material, and the second electrode active material is a smaller particle size electrode active material whose particle size is smaller than the particle size of the first electrode active material.

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