Electrode and rechargeable lithium battery including the same

Abstract

The present disclosure relates to an electrode for a rechargeable lithium battery and a rechargeable lithium battery including the same, the electrode including an electrode current collector and a plurality of active material layers. The multi-layer active material layer includes a first active material layer, a second active material layer, and a third active material layer stacked on the electrode current collector. The first active material layer includes a first active material, and the third active material layer includes a second active material. The second active material layer includes a first region containing a first active material and a second region containing a second active material. The first regions and the second regions are alternately arranged along a first direction, the first regions extend parallel to each other in a second direction crossing the first direction, and the second regions extend parallel to each other in the second direction.

Description

[0001] This application claims priority to Korean Patent Application No. 10-2024-0154273, filed on November 4, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This disclosure relates herein to an electrode and a rechargeable lithium battery including the electrode. Background Technology

[0003] With the increasing prevalence of battery-powered electronic devices (such as mobile phones, laptops, and electric vehicles), the demand for rechargeable batteries with high energy density and high capacity is growing. Therefore, improving the performance of rechargeable lithium-ion batteries can be advantageous.

[0004] A rechargeable lithium battery includes a positive electrode and a negative electrode containing active materials capable of inserting and deintercalating lithium ions, as well as an electrolyte, and generates electrical energy through oxidation and reduction reactions while lithium ions are deintercalated from the positive electrode and inserted into the negative electrode and deintercalated from the negative electrode and inserted into the positive electrode. Summary of the Invention

[0005] Examples of electrodes with improved capacity and lifetime characteristics are described in this disclosure.

[0006] Other embodiments of this disclosure describe a rechargeable lithium battery including the electrode.

[0007] An electrode for a rechargeable lithium battery conceived according to examples of this disclosure may include an electrode current collector and a multilayer active material layer on the electrode current collector. The multilayer active material layer may include a first active material layer, a second active material layer, and a third active material layer stacked (e.g., sequentially stacked) on the electrode current collector. The first active material layer may include a first active material, and the third active material layer may include a second active material. The second active material layer may include a first region containing the first active material and a second region containing the second active material. The first and second regions may be arranged alternately along a first direction. The first regions may extend parallel to each other in a second direction intersecting the first direction, and the second regions may extend parallel to each other in the second direction. The third active material layer may have a larger porosity than the second active material layer, and the second active material layer may have a larger porosity than the first active material layer.

[0008] An electrode for a rechargeable lithium battery conceived according to another example of this disclosure may include an electrode current collector, a first active material layer on the electrode current collector, and a second active material layer on the first active material layer. The first active material layer may include a first region comprising the first active material and a second region comprising the second active material. The first and second regions may be arranged alternately along a first direction, the first regions may extend parallel to each other in a second direction intersecting the first direction, and the second regions may extend parallel to each other in the second direction. The second active material layer may include the second active material, and the second active material layer may have a lower rolling density than the first active material layer.

[0009] A rechargeable lithium battery conceived according to another example of this disclosure may include a positive electrode, a negative electrode, a separator disposed between the positive electrode and the negative electrode, and an electrolyte, wherein at least one of the positive electrode and the negative electrode may include the electrode discussed above. Attached Figure Description

[0010] The accompanying drawings are included to provide a further understanding of this disclosure, and are incorporated in and constitute a part of this specification. The drawings illustrate exemplary embodiments of this disclosure and, together with the description, explain the principles of this disclosure. In the drawings: Figure 1 This is a conceptual diagram illustrating a rechargeable lithium battery according to an example embodiment of the present disclosure; Figures 2 to 5 This is a schematic diagram illustrating a rechargeable lithium battery according to an example embodiment, wherein, Figure 2 It can be a cylindrical battery. Figure 3 It can be a prismatic battery, and Figure 4 and Figure 5 It can be a pouch-type battery; Figure 6 This is a schematic diagram of an electrode for a rechargeable lithium battery according to an exemplary embodiment of the present disclosure; Figure 7 This is a cross-sectional view used to describe an electrode for a rechargeable lithium battery according to an exemplary embodiment of the present disclosure; Figure 8 This is an enlarged view used to describe the electrodes according to an exemplary embodiment of the present disclosure; Figure 9 This is a schematic diagram of electrodes according to other exemplary embodiments of this disclosure; Figure 10 This is a cross-sectional view used to describe electrodes according to other exemplary embodiments of this disclosure; Figure 11 This is an enlarged view used to describe electrodes according to other exemplary embodiments of this disclosure; Figure 12AThese are diagrams illustrating a method of manufacturing an electrode according to an exemplary embodiment of the present disclosure; and Figure 12B This is a diagram illustrating a method of manufacturing an electrode according to other exemplary embodiments of this disclosure. Detailed Implementation

[0011] To fully understand the structure and effects of this disclosure, exemplary embodiments of the disclosure are described with reference to the accompanying drawings. However, it should be noted that this disclosure is not limited to the exemplary embodiments disclosed below, but can be implemented in various forms. Rather, exemplary embodiments are provided to fully disclose this disclosure and to enable those skilled in the art to fully understand its scope.

[0012] In the specification, when an element is referred to as being "on" another element, the element may be formed "directly" on the other element, or an intervening element may be placed between them. In the accompanying drawings, the thickness of the components may be exaggerated for the purpose of effectively describing the technical content. Throughout the specification, the same reference numerals or symbols refer to the same elements.

[0013] The exemplary embodiments described herein are described with reference to cross-sectional views and / or plan views, which serve as ideal illustrations of this disclosure. In the drawings, the thickness of layers and regions is exaggerated for the purpose of effectively describing the technical content. Therefore, the regions shown in the figures are schematic, and the shapes of the regions shown are intended to illustrate a given form of the apparatus, and not to limit the scope of the disclosure. Although terms such as first, second, third, etc., have been used to describe various components in the various exemplary embodiments of the specification, the components may not be limited by these terms. These terms are used only to distinguish one component from another. The exemplary embodiments described and illustrated herein also include complementary embodiments thereof.

[0014] In this specification, unless otherwise specifically stated, singular terms may include plural forms. Furthermore, unless otherwise stated, "A or B" may imply "including A, including B, or including both A and B". The term "including" and / or variations thereof as used in this specification does not exclude the presence or addition of one or more other components besides those specifically mentioned.

[0015] As used herein, the term “combination of them” can refer to a mixture, stack, complex, copolymer, alloy, blend, or reaction product of the components.

[0016] Unless otherwise defined in this specification, particle size may be the average particle size. Additionally, particle size indicates the average particle size (D). 50 The average particle size (D) refers to the diameter of particles that constitute approximately 50% of the total volume in the particle size distribution. 50The average particle size can be measured using methods known to those skilled in the art, for example, by a particle size analyzer or by using transmission electron microscopy (TEM) images or scanning electron microscopy (SEM) images. Alternatively, the average particle size can be measured using a dynamic light scattering measuring device, wherein data analysis is performed to count the number of particles in each particle size range, and then the average particle size (D) can be calculated. 50 The average particle size can also be measured using laser diffraction. In laser diffraction, target particles are dispersed in a dispersion medium and then introduced into a commercial laser diffraction particle size analyzer (e.g., Microtrac MT3000), irradiated with ultrasound at approximately 28 kHz with an output of approximately 60 W. The average particle size (D) can then be calculated within the analyzer based on approximately 50% of the particle size distribution. 50 ).

[0017] When the terms “about” or “substantially” are used in conjunction with numerical values ​​in this specification, they mean that the relevant numerical value includes a tolerance of ±10% around the stated value. When a range is specified, the range includes all values ​​in between (such as increments of 0.1%).

[0018] Figure 1 This is a cross-sectional view of a rechargeable lithium battery according to an exemplary embodiment of this disclosure. (Refer to...) Figure 1 A rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0019] The positive electrode 10 and the negative electrode 20 can be separated from each other by a diaphragm 30. The diaphragm 30 can be disposed between the positive electrode 10 and the negative electrode 20. The positive electrode 10, the negative electrode 20 and the diaphragm 30 can be in contact with the electrolyte ELL. The positive electrode 10, the negative electrode 20 and the diaphragm 30 can be immersed in the electrolyte ELL.

[0020] The electrolyte ELL can be or includes a medium for transferring lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions can move toward the positive electrode 10 or the negative electrode 20 through the separator 30.

[0021] Positive electrode 10 The positive electrode 10 for a rechargeable lithium battery may include a current collector COL1 and a positive electrode active material layer AML1 on the current collector. The positive electrode active material layer AML1 may include a positive electrode active material and may also include a binder and / or a conductive material (e.g., an electrically conductive material).

[0022] For example, the positive electrode 10 may also include additives that can constitute a sacrificial positive electrode.

[0023] Based on a 100 wt% positive electrode active material layer AML1, the amount of positive electrode active material can range from about 90 wt% to about 99.5 wt%. Based on a 100 wt% positive electrode active material layer AML1, the amounts of binder and conductive material can each range from about 0.5 wt% to about 5 wt%.

[0024] The binder is configured to adhere the positive electrode active material particles to each other and to adhere the positive electrode active material to the current collector COL1. As a non-limiting example, examples of the binder may include at least one of the following: polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, polymers including ethylene oxide, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, nylon, etc.

[0025] Conductive materials can be configured to impart electrical conductivity (e.g., conductivity) to electrodes. Any material that does not cause adverse chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and conducts electrons can be used in the battery. Examples of conductive materials can include: carbon-based materials, such as at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, comprising at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0026] Al can be used as a current collector COL1, but current collector COL1 is not limited to this.

[0027] Positive electrode active material The positive electrode active material may include compounds capable of intercalating and deintercalating lithium (lithiation intercalation compounds). For example, at least one of the composite oxides of lithium and metals such as or including at least one of cobalt, manganese, nickel, and combinations thereof may be used.

[0028] The composite oxide can be or includes lithium transition metal composite oxides. Examples of composite oxides may include at least one of lithium nickel oxides, lithium cobalt oxides, lithium manganese oxides, lithium iron phosphate compounds, cobalt-free lithium nickel manganese oxides, and combinations thereof.

[0029] As an example, a compound represented by any of the following chemical formulas can be used. Li a A 1-b X b O 2-c D c(0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Mn 2-b X b O 4-c D c (0.90≤a≤1.8, 0≤b≤0.5, and 0≤c≤0.05); Li a Ni 1-b-c Co b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni 1-b-c Mn b X c O 2-α D α (0.90≤a≤1.8, 0≤b≤0.5, 0≤c≤0.5, and 0<α<2); Li a Ni b Co c L 1 d G e O2 (0.90≤a≤1.8, 0≤b≤0.9, 0≤c≤0.5, 0≤d≤0.5, and 0≤e≤0.1); Li a NiG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a CoG b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-b G b O2 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn2G b O4 (0.90≤a≤1.8, and 0.001≤b≤0.1); Li a Mn 1-g G g PO4 (0.90 ≤ a ≤ 1.8, and 0 ≤ g ≤ 0.5); Li (3-f) Fe2(PO4)3 (0≤f≤2); and Li a FePO4 (0.90≤a≤1.8).

[0030] In the above chemical formulas, A is or includes at least one of Ni, Co, Mn, and combinations thereof; X is or includes at least one of Al, Ni, Co, Mn, Cr, Fe, Mg, Sr, V, rare earth elements, and combinations thereof; D is or includes at least one of O, F, S, P, and combinations thereof; G is or includes at least one of Al, Cr, Mn, Fe, Mg, La, Ce, Sr, V, and combinations thereof; and L 1 It is or includes at least one of Mn, Al and combinations thereof.

[0031] The positive electrode active material can be, or includes, for example, a high-nickel positive electrode active material, based on 100 mol% of metals other than lithium in a lithium transition metal complex oxide. The high-nickel positive electrode active material has a nickel content greater than or equal to about 80 mol%, greater than or equal to about 85 mol%, greater than or equal to about 90 mol%, greater than or equal to about 91 mol%, or greater than or equal to about 94 mol% and less than or equal to about 99 mol%. High-nickel positive electrode active materials can achieve high capacity and can be used in high-capacity, high-density rechargeable lithium batteries.

[0032] negative electrode 20 The negative electrode 20 for a rechargeable lithium battery may include a current collector COL2 and a negative electrode active material layer AML2 on the current collector COL2. The negative electrode active material layer AML2 may include a negative electrode active material and may also include a binder and / or a conductive material (e.g., an electrically conductive material).

[0033] For example, the negative electrode active material layer AML2 may include about 90 wt% to about 99 wt% of negative electrode active material, about 0.5 wt% to about 5 wt% of binder, and about 0 wt% to about 5 wt% of conductive material.

[0034] The binder can be configured to adhere the negative electrode active material particles to each other and to adhere the negative electrode active material to the current collector COL2. The binder may include at least one of non-aqueous binders, aqueous binders, dry binders, and combinations thereof.

[0035] Non-aqueous adhesives may include at least one of polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, and combinations thereof.

[0036] The waterborne adhesive may be or include at least one of styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, (meth)acrylonitrile-butadiene rubber, (meth)acrylic rubber, butyl rubber, fluororubber, polyethylene oxide, polyvinylpyrrolidone, polyepoxychloropropane, polyphosphazene, poly(meth)acrylonitrile, ethylene propylene diene copolymer, polyvinylpyridine, chlorosulfonated polyethylene, latex, polyester resin, (meth)acrylic resin, phenolic resin, epoxy resin, polyvinyl alcohol, and combinations thereof.

[0037] When using an aqueous binder as the negative electrode binder, it may also include a cellulose compound capable of imparting viscosity. The cellulose compound may include at least one of carboxymethyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, and their alkali metal salts. The alkali metal may include at least one of Na, K, and Li.

[0038] Dry adhesives can be or include polymeric materials capable of being fibrous. For example, dry adhesives can be or include at least one of polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, and combinations thereof.

[0039] Conductive materials can be configured to impart electrical conductivity (e.g., conductivity) to electrodes. Any material that does not cause adverse chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and conducts electrons can be used in the battery. Non-limiting examples may include: carbon-based materials, such as at least one of natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, including at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0040] The current collector COL2 of the negative electrode may include at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, polymer substrate coated with conductive metal, and combinations thereof.

[0041] Negative electrode active material The negative electrode active material may include at least one of the following: materials capable of reversibly inserting / deintercalating lithium ions, lithium metal, lithium metal alloys, materials capable of doping / dedoping lithium, and transition metal oxides.

[0042] Materials capable of reversibly inserting / deintercalating lithium ions can include carbon-based negative electrode active materials, such as crystalline carbon, amorphous carbon, or combinations thereof. Crystalline carbon can be graphite, such as amorphous, flake-like, sheet-like, spherical, or fibrous natural or artificial graphite. Amorphous carbon can be or includes at least one of soft carbon, hard carbon, mesophase pitch carbonization products, calcined coke, etc.

[0043] The lithium metal alloy includes an alloy of lithium and a metal such as or including at least one of Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0044] The material capable of doping / dedoping lithium can be or include a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material can include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2) and at least one of Si-Q alloys (where Q is or includes at least one of an alkali metal, an alkaline earth metal, a Group 13 element, a Group 14 element (excluding Si), a Group 15 element, a Group 16 element, a transition metal, a rare earth element, and their combinations). The Sn-based negative electrode active material can include at least one of Sn, SnO2, Sn-based alloys, and their combinations.

[0045] The silicon-carbon composite can be or include a composite of silicon and amorphous carbon. According to an exemplary embodiment, the silicon-carbon composite can be in the form of silicon particles and an amorphous carbon coating on the surface of the silicon particles. For example, the silicon-carbon composite can include secondary particles (cores) in which primary silicon particles are assembled and an amorphous carbon coating layer (shells) on the surface of the secondary particles. Amorphous carbon can also be present between the primary silicon particles, and, for example, the primary silicon particles can be coated with amorphous carbon. The secondary particles can be dispersed in an amorphous carbon matrix.

[0046] The silicon-carbon composite can also include crystalline carbon. For example, the silicon-carbon composite can include a core containing crystalline carbon and silicon particles and an amorphous carbon coating layer on the surface of the core.

[0047] The Si-based negative electrode active material or the Sn-based negative electrode active material can be used in combination with a carbon-based negative electrode active material.

[0048] Diaphragm 30 Depending on the type of rechargeable lithium battery, a separator 30 can be present between the positive electrode 10 and the negative electrode 20. The separator 30 can include at least one of polyethylene, polypropylene, polyvinylidene fluoride, and a multilayer film of two or more layers thereof (e.g., a hybrid multilayer film (such as a polyethylene / polypropylene bilayer separator, a polyethylene / polypropylene / polyethylene trilayer separator, a polypropylene / polyethylene / polypropylene trilayer separator, etc.)).

[0049] The separator 30 can include a porous substrate and a coating layer including an organic material, an inorganic material, or a combination thereof on one or both surfaces of the porous substrate.

[0050] The porous substrate may be or include a polymer membrane, which is formed or includes one or more copolymers or mixtures of two or more of the following: polymeric polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetals, polyamides, polyimides, polycarbonates, polyetherketones, polyaryletherketones, polyetherimides, polyamideimides, polybenzimidazoles, polyethersulfones, polyphenylene ethers, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fibers, and polytetrafluoroethylene (e.g., TEFLON). ® ).

[0051] Organic materials may include polymers such as polyvinylidene fluoride or (meth)acrylic acid polymers.

[0052] Inorganic materials may include inorganic particles, such as or including at least one of Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof, but are not limited thereto.

[0053] Organic and inorganic materials can be mixed in a coating layer, or a coating layer containing organic materials and a coating layer containing inorganic materials can be stacked together.

[0054] Electrolyte ELL Electrolytes (ELLs) used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0055] Non-aqueous organic solvents can be constructed as media for transporting ions that participate in the electrochemical reactions of a battery.

[0056] Non-aqueous organic solvents may be or include at least one of carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, and combinations thereof.

[0057] Carbonate solvents may include at least one of dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (MEC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC).

[0058] Ester solvents may include at least one of the following: methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc.

[0059] Ether solvents may include at least one of dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, dimethoxyethane, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc. Aprotic solvents may include at least one of the following: nitriles, such as R-CN (wherein R is a C2 to C20 straight-chain, branched, or cyclic hydrocarbon group, and may include double bonds, aromatic rings, or ether bonds, etc.); amides, such as dimethylformamide; dioxolane, such as 1,3-dioxolane, 1,4-dioxolane, etc.; sulfolane, etc.

[0060] Non-aqueous organic solvents can be used alone or in combination of two or more solvents.

[0061] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed, and the cyclic carbonates and chain carbonates can be mixed in a volume ratio ranging from about 1:1 to about 1:9.

[0062] Lithium salts dissolved in organic solvents are configured to supply lithium ions in batteries to enable basic operation of rechargeable lithium batteries and improve lithium ion transport between the positive and negative electrodes. Examples of lithium salts include LiPF6, LiBF4, LiSbF6, LiAsF6, LiClO4, LiAlO2, LiAlCl4, LiPO2F2, LiCl, LiI, LiN(SO3C2F5)2, Li(FSO2)2N (lithium bis(fluorosulfonyl)imide, LiFSI), LiC4F9SO3, and LiN(C x F 2x+1 SO2)(C y F 2y+1 SO2 (where x and y are integers from 1 to 20), lithium trifluoromethane sulfonate, lithium tetrafluoroethane sulfonate, lithium difluoro(oxalate)borate (LiDFOB), lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0063] Rechargeable lithium batteries Rechargeable lithium batteries can be classified according to their shape, such as cylindrical, prismatic, pouch, or coin-shaped batteries. Figures 2 to 5 This is a schematic diagram illustrating a rechargeable lithium battery according to an example embodiment. Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown. Figure 4 and Figure 5 A pouch-type battery is shown. (See reference) Figures 2 to 5The rechargeable lithium battery 100 may include an electrode assembly 40 and a housing 50 therein housing the electrode assembly 40. The electrode assembly 40 includes a separator 30 between a positive electrode 10 and a negative electrode 20. The positive electrode 10, the negative electrode 20, and the separator 30 may be impregnated with an electrolyte (not shown). Figure 2 As shown, the rechargeable lithium battery 100 may include a sealing member 60 of the sealed housing 50. Figure 3 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive terminal 12 connected to the positive electrode lead connector 11, a negative electrode lead connector 21, and a negative terminal 22 connected to the negative electrode lead connector 21. For example... Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include Figure 5 The electrode terminal 70 shown, or for example Figure 4 The positive electrode terminal 71 and negative electrode terminal 72 shown form an electrical path for guiding the current formed in the electrode assembly 40 to the outside of the rechargeable lithium battery 100.

[0064] According to exemplary embodiments of the present disclosure, a rechargeable lithium battery is provided, comprising an electrode, a separator, and an electrolyte. For example, the rechargeable lithium battery according to the exemplary embodiment may include a positive electrode comprising a positive electrode active material, a negative electrode comprising a negative electrode active material, a separator between the positive and negative electrodes, and an electrolyte. At least one of the positive and negative electrodes may be an electrode as described below, and for example, the positive electrode may be an electrode as described below. The electrode according to the present disclosure may also be applicable to the negative electrode, but is not limited thereto.

[0065] Electrodes for rechargeable lithium batteries The electrodes according to exemplary embodiments of the present disclosure are described in more detail below. References to the above are omitted. Figures 1 to 5 The description provides a detailed explanation of the reusable technical features of rechargeable lithium batteries, and details the differences between them.

[0066] Figure 6 This is a schematic diagram illustrating a rechargeable lithium battery according to an exemplary embodiment of the present disclosure. Figure 7 This is a cross-sectional view used to describe the electrodes for a rechargeable lithium battery according to an exemplary embodiment of the present disclosure, and along with... Figure 6 The cross section cut by line I-I' corresponds to the section in the middle.

[0067] Figure 6 and Figure 7 Each of the figures shows a rolled electrode. In the following, in this specification, unless otherwise stated, an electrode refers to a rolled electrode.

[0068] Reference Figure 6 and Figure 7 Electrodes 10 and 20 may include an electrode current collector COL and an active material layer AML positioned on the electrode current collector COL.

[0069] Electrodes 10 and 20 may have a top surface that is parallel to a first direction D1 and a second direction D2 that intersects the first direction D1 and is orthogonal to a third direction D3. For example, the first direction D1, the second direction D2, and the third direction D3 may be orthogonal to each other.

[0070] The electrode current collector COL may include the aforementioned current collector COL1 or current collector COL2.

[0071] For example, the electrode current collector COL can be or include at least one of copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, and combinations thereof. In an example embodiment, Al can be used as the electrode current collector COL, but the electrode current collector COL is not limited thereto.

[0072] The active material layer AML can include a multilayer active material layer structure. The multilayer active material layer can include a first active material layer ATL1, a second active material layer ATL2, and a third active material layer ATL3 stacked (e.g., sequentially stacked) on the electrode current collector COL. For example, the multilayer active material layer can include a first active material layer ATL1 disposed on the electrode current collector COL, a second active material layer ATL2 disposed on the first active material layer ATL1, and a third active material layer ATL3 disposed on the second active material layer ATL2.

[0073] The first active material layer ATL1 can have a thickness TKL1 on the third-direction D3, the second active material layer ATL2 can have a thickness TKL2 on the third-direction D3, and the third active material layer ATL3 can have a thickness TKL3 on the third-direction D3.

[0074] The thickness TKL of the active material layer AML can be the sum of the thickness TKL1 of the first active material layer ATL1, the thickness TKL2 of the second active material layer ATL2, and the thickness TKL3 of the third active material layer ATL3.

[0075] The thickness TKL of the active substance layer AML can range from about 10 μm to about 170 μm. For example, the thickness TKL of the active substance layer AML can be about 10 μm or more, about 11 μm or more, about 15 μm or more, about 20 μm or more, about 30 μm or more, or about 40 μm or more. For example, the thickness TKL of the active substance layer AML can be about 170 μm or less, about 160 μm or less, about 150 μm or less, about 140 μm or less, about 130 μm or less, about 120 μm or less, about 110 μm or less, about 100 μm or less, about 90 μm or less, about 80 μm or less, about 70 μm or less, about 60 μm or less, or about 50 μm or less. When the thickness TKL of the active material layer AML falls within the above range, the volume change of the battery during charging and discharging can be reduced or minimized, and a battery with a longer lifespan can be provided.

[0076] The thickness TKL1 of the first active material layer ATL1 can be in the range of about 10 μm to about 100 μm. The thickness TKL1 of the first active material layer ATL1 can be, for example, about 15 μm or greater, about 20 μm or greater, about 30 μm or greater, or about 40 μm or greater. The thickness TKL1 of the first active material layer ATL1 can be, for example, about 90 μm or less, about 80 μm or less, about 70 μm or less, about 60 μm or less, about 50 μm or less, or about 40 μm or less.

[0077] The thickness TKL2 of the second active material layer ATL2 can be in the range of about 10 μm to about 100 μm. The thickness TKL2 of the second active material layer ATL2 can be, for example, about 15 μm or greater, about 20 μm or greater, about 30 μm or greater, or about 40 μm or greater. The thickness TKL2 of the second active material layer ATL2 can be, for example, about 90 μm or less, about 80 μm or less, about 70 μm or less, about 60 μm or less, about 50 μm or less, or about 40 μm or less.

[0078] The thickness TKL3 of the third active material layer ATL3 can range from about 10 μm to about 100 μm. For example, the thickness TKL3 of the third active material layer ATL3 can be 15 μm or more, 20 μm or more, 30 μm or more, or 40 μm or more. The thickness TKL3 of the third active material layer ATL3 can be, for example, 90 μm or less, 80 μm or less, 70 μm or less, 60 μm or less, 50 μm or less, or 40 μm or less.

[0079] In an example embodiment, the thickness TKL1 can increase as the weight of the active material included in the first active material layer ATL1 increases. In an example embodiment, the thickness TKL2 can increase as the amount of active material included in the second active material layer ATL2 increases. In an example embodiment, the thickness TKL3 can increase as the amount of active material included in the third active material layer ATL3 increases.

[0080] When the thicknesses TKL1 of the first active material layer ATL1, TKL2 of the second active material layer ATL2, and TKL3 of the third active material layer ATL3 fall within the aforementioned range, volume changes during charging and discharging can be reduced or minimized, resulting in a battery with a longer lifespan. Furthermore, improved adhesion of the active material layer AML to the electrode current collector COL also facilitates easier electrode processing while increasing or maximizing battery capacity and energy density.

[0081] According to an example embodiment, the thickness TKL2 of the second active material layer ATL2 can be in the range of approximately 30% to approximately 100%, approximately 30% to approximately 90%, or approximately 30% to approximately 70% of the thickness of the first active material layer ATL1 or the third active material layer ATL3. When the thickness TKL2 of the second active material layer ATL2 is less than the above range, the conductivity may decrease. Furthermore, when the thickness TKL2 of the second active material layer ATL2 exceeds the above range, the interface resistance may increase.

[0082] For example, the thickness ratio of the first active material layer ATL1, the second active material layer ATL2, and the third active material layer ATL3, TKL1:TKL2:TKL3, is approximately 1:1:1, approximately 1:0.9:1, approximately 1:0.7:1, approximately 1:0.5:1, or approximately 1:0.3:1.

[0083] Figure 8 This is an enlarged view used to describe an exemplary embodiment of the electrode according to the inventive concept. That is, Figure 8 It is one of them Figure 7 An enlarged view of the region "M" in the image.

[0084] Reference Figure 8 The first active material layer ATL1 can be in contact with one surface of the electrode current collector COL. This surface of the first active material layer ATL1 can be the surface on which the first active material layer ATL1 contacts the electrode current collector COL.

[0085] The first active material layer ATL1, which is in contact with the electrode current collector COL in the multilayer active material layer, may include the first active material CAM1.

[0086] When the electrode for a rechargeable lithium battery according to an exemplary embodiment of the present disclosure is a positive electrode, any material that can be used as a positive electrode active material for a rechargeable lithium battery can be used as the first active material CAM1.

[0087] For example, as the first active material CAM1, a compound capable of intercalating and deintercalating lithium (lithium-intercalating compound) can be used. The first active material CAM1 may include a lithium composite oxide represented by the following Formula 1.

[0088] Formula 1: Li x4 M 1 y M 2 z M 3 1-y-z O 2-a X a In the above Formula 1, 0.5 ≤ x4 ≤ 1.8, 0 ≤ a ≤ 0.05, 0 < y ≤ 1, 0 ≤ z ≤ 1, and 0 ≤ y + z ≤ 1, M 1 、M 2 and M 3 may each independently include one or more metals, such as or including at least one of Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Zr, La, and combinations thereof, and X may include one or more elements, such as or including at least one of F, S, P, and Cl.

[0089] In an exemplary embodiment, in the above Formula 1, M 1 may be or include Ni, 0.8 ≤ y ≤ 1, 0 ≤ z ≤ 0.2. For example, as the first active material CAM1, at least one of lithium iron manganese phosphate (LFMP, LiFePO4), lithium nickel manganese oxide (NMX, LiNiMnO4), lithium nickel cobalt aluminum oxide (NCA, LiNiCoAlO2), and lithium nickel cobalt manganese oxide (NCM, LiNiCoMnO2) can be used.

[0090] When the electrode for a rechargeable lithium battery according to an exemplary embodiment of the present disclosure is a negative electrode, any material that can be used as a negative electrode active material for a rechargeable lithium battery can be used as the first active material CAM1 without limitation.

[0091] The first active material CAM1 can have different physical properties than the second active material CAM2. For example, the first active material CAM1 can have a higher particle density and tap density, and a smaller average particle size (D) than the second active material CAM2. 50 ).

[0092] Each of the physical properties mentioned above is one of the important properties related to porosity. Particle density, tap density, and average particle size (D) 50 The particle size distribution can be measured using instruments (such as pellet mills, tap density testers, and particle size analyzers) by methods known to those skilled in the art.

[0093] The first active material CAM1 may be or include elements having a relatively high rolling reduction rate. For example, the first active material CAM1 may have a rolling reduction rate of about 1.7 g / cm³. 3 Or a wider range of particle densities. The particle density of the first active substance CAM1 can be, for example, about 1.7 g / cm³. 3 Approximately 2.0 g / cm³ 3 Approximately 1.7 g / cm³ 3 Approximately 1.9 g / cm³ 3 or approximately 1.7 g / cm³ 3 Approximately 1.8 g / cm³ 3 Additionally, the first active substance CAM1 can have a concentration of approximately 1.1 g / cm³. 3 Or a wider range of tap densities. The tap density of the first active substance CAM1 can be, for example, about 1.1 g / cm³. 3 Approximately 1.4 g / cm³ 3 Approximately 1.1 g / cm³ 3 Approximately 1.3 g / cm³ 3 When the particle density and tap density of the first active material CAM1 fall within the above range, the first active material layer ATL1 can have a relatively high rolling density.

[0094] The first active substance CAM1 can have an average particle size (D) in the range of about 2 μm to about 30 μm. 50 The average particle size of the first active substance CAM1 can be, for example, about 3 μm to about 25 μm, about 4 μm to about 23 μm, about 5 μm to about 22 μm, about 6 μm to about 30 μm, etc.

[0095] The first active substance CAM1 can have a concentration of approximately 2.0 m. 2 Specific surface area in the range of / g or smaller. The specific surface area of ​​the first active substance CAM1 can be, for example, about 0.1m². 2 / g to approximately 2.0m 2 / g, approximately 0.5m2 / g to approximately 1.9m 2 / g, approximately 0.7m 2 / g to approximately 1.8m 2 / g, approximately 1.0m 2 / g to approximately 1.7m 2 / g etc.

[0096] When the average particle size of the first active substance CAM1 (D) 50 When both the specific surface area and the specific surface area fall within the above range, the first active substance CAM1 can exhibit high capacity and high energy density.

[0097] The first active material layer ATL1 can have a porosity in the range of about 5% to about 12%. Porosity can be the area ratio of voids in the active material layer, obtained by capturing an image of a cross-section of the rolled electrode using a scanning electron microscope or similar means and analyzing the captured image using image analysis software (such as Image J).

[0098] In another example embodiment, the porosity can be obtained by Equation 1 below.

[0099] Equation 1: Porosity (%) = {1 - (apparent density / true density)} × 100 Porosity is the ratio of pores in the total volume of a sample. Based on porosity, the presence or absence of pores in a sample, as well as the size of the pores, can be indirectly evaluated.

[0100] The volume used in the calculation of apparent density includes the total volume of the sample (apparent volume), where void spaces within the sample (such as open pores) may be considered in the calculation. Apparent density can be a concept contrasted with true density. Apparent density can be defined as the ratio of the mass of the first active material layer ATL1 to the total volume of the first active material layer ATL1.

[0101] Apparent density can be measured using methods such as Archimedes' principle, mercury porosity determination, and liquid specific gravity determination. For example, Archimedes' principle can be used to calculate volume by measuring the degree of buoyancy applied to a sample in a liquid. Mercury porosity determination can be used to examine the pore structure inside a sample using mercury to calculate the total volume of the sample based on the results. Liquid specific gravity determination can be used to directly measure the volume of a sample and calculate the apparent density. However, methods for measuring apparent density are not limited to the examples described above.

[0102] True density represents the density of the pure material itself, excluding all pores within the sample. In other words, true density can be defined as the theoretical density of the first active material layer ATL1, excluding pores. In an example embodiment, true density can be measured using a gas specific gravity bottle. A true density value can be obtained by adsorbing a gas, such as helium, onto the sample and measuring the pressure change due to the reduction in the volume of the adsorbed gas.

[0103] The method for measuring the true density using a gas specific gravity bottle is as follows. The sample chamber, into which the sample is injected, is connected to a reference chamber via an expansion valve. The volume (Vc) of the sample chamber and the volume (Vr) of the reference chamber are measured. When the gas inlet valve is opened to introduce helium into the sample chamber, the equilibrium pressure inside the sample chamber is P1, and the volume is Vc - Vs. In this case, Vs is the volume of the sample. When the expansion valve is opened, the system has a new equilibrium pressure P2 and a volume Vc - Vs + Vr. This can be simply represented by P1(Vc - Vs) = P2(Vc - Vs + Vr). Using pressure sensors to measure the equilibrium pressures P1 and P2, and with the volumes Vc and Vr of the two chambers known, Vs can be derived, thus obtaining the true density. The true density can be calculated by dividing the pre-measured mass of the sample by Vs.

[0104] According to an example embodiment, the porosity of the first active material layer ATL1 can be, for example, in the range of about 5% to about 12%, about 9% to about 12%, about 10% to about 12%, about 11% to about 12%, etc. When the first active material layer ATL1 exhibits such porosity, high-rate charge and discharge properties can be improved while achieving high capacity and high energy density.

[0105] According to an example embodiment, the amount of the first active material CAM1 relative to the total weight of the first active material layer ATL1 can be in the range of about 90 wt% to about 99.5 wt%.

[0106] In the example embodiment, since the active material with a high rolling reduction rate is disposed in the bottom layer among the multilayer active material layers, the energy density on the bottom side is increased, thereby improving the charging and discharging properties of the battery.

[0107] In addition to the first active material CAM1, the first active material layer ATL1 may also include the binder BND.

[0108] The binder BND can be configured to adhere the first active material particles to each other, and can be configured to adhere the first active material CAM1 to the electrode current collector COL. For example, the binder BND may include, but is not limited to, at least one of rubber-based binders, acrylate-based binders, polyvinylidene fluoride-based binders, polyvinylpyrrolidone-based binders, nitrile-based binders, acetate-based binders, polyvinyl alcohol-based binders, and cellulose-based binders.

[0109] Rubber adhesives may be or include at least one of, for example, styrene-butadiene rubber (SBR), nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), and ethylene propylene diene monomer rubber (EPDM).

[0110] Acrylic adhesives may be or include at least one of, for example, polyacrylic acid (PAA), polymethyl methacrylate, polyisobutyl methacrylate, ethyl acrylate, butyl acrylate and poly(2-ethylhexyl acrylate).

[0111] For example, polyvinylidene fluoride adhesives may be or include at least one of polyvinylidene fluoride, polyvinylidene fluoride-co-hexafluoropropylene, polyvinylidene fluoride-co-trichloroethylene, polyvinylidene fluoride-co-tetrafluoroethylene, polyvinylidene fluoride-co-trifluoroethylene, polyvinylidene fluoride-co-trifluorochloroethylene, polyvinylidene fluoride-co-hexafluoropropylene (PVdF-HFP), and polyvinylidene fluoride-co-trichloroethylene.

[0112] Polyvinylpyrrolidone adhesives may be or include, for example, polyvinylpyrrolidone.

[0113] Nitrile adhesives may be, for example, polyacrylonitrile or acrylonitrile-styrene-butadiene copolymers.

[0114] Acetate-based adhesives may be or include at least one of the following: polyvinyl acetate, polyethylene-co-vinyl acetate, cellulose acetate, cellulose acetate butyrate, and cellulose acetate propionate.

[0115] Polyvinyl alcohol adhesives may be or include, for example, polyvinyl alcohol.

[0116] For example, cellulose-based binders may be or include at least one of carboxymethyl cellulose (CMC), methyl cellulose (MC), hydroxypropyl cellulose (HPC), methyl hydroxypropyl cellulose (MHPC), ethyl hydroxyethyl cellulose (EHEC), methyl ethyl hydroxyethyl cellulose (MEHEC), and cellulose gum.

[0117] In an example embodiment, the amount of adhesive BND may be in the range of about 0.01 wt% to about 5 wt% relative to the total weight of the first active material layer ATL1.

[0118] In addition to the first active material CAM1 and the binder BND, the first active material layer ATL1 may also include the conductive material CDM.

[0119] The conductive material CDM can be configured to impart conductivity of 10 or 20 to the electrodes. Any material that does not cause chemical changes in the constructed battery and is an electrically conductive material can be used. As examples, the conductive material CDM may include: carbon-based materials, such as at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, including at least one of copper, nickel, aluminum, silver, etc., in the form of metal powder or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0120] The amount of conductive material CDM included in the first active material layer ATL1 can be less than the amount of conductive material CDM included in the second active material layer ATL2, which will be described below. The first active material layer ATL1 may include trace amounts of conductive material CDM. For example, the amount of conductive material CDM in the first active material layer ATL1 may be in the range of about 0.5 wt% or less.

[0121] According to the example embodiment, the amount of conductive material CDM relative to the total weight of the first active material layer ATL1 can be in the range of about 0.001 wt% to about 0.5 wt%. When the amount of conductive material CDM in the first active material layer ATL1 falls within the above range, the capacity and energy density of the battery can be increased or maximized.

[0122] The third active material layer ATL3 may be in contact with one surface of the second active material layer ATL2. This surface of the second active material layer ATL2 may not be in contact with the first active material layer ATL1. The third active material layer ATL3 may be positioned on the outermost side of the multilayer active material layers and may include the second active material CAM2.

[0123] The second active material CAM2 may be the same as or different from the first active material CAM1 described with respect to the first active material layer ATL1. For example, the second active material CAM2 may include a lithium composite oxide represented by Formula 1 above.

[0124] The second active substance CAM2 may have different physical properties than the first active substance CAM1. For example, the second active substance CAM2 may have a smaller particle density and tap density than the first active substance CAM1, and a larger average particle size (D) than the first active substance CAM1. 50 ).

[0125] In other words, the second active material CAM2 can be or includes a material with a relatively low rolling reduction rate.

[0126] The particle density and tap density of the second active substance CAM2 can be lower than those of the first active substance CAM1. For example, the second active substance CAM2 can have a particle density and tap density of less than about 1.6 g / cm³. 3 The particle density, and the particle density of the second active substance CAM2 can be, for example, about 1.3 g / cm³. 3 Approximately 1.59 g / cm³ 3 Approximately 1.4 g / cm³ 3 Approximately 1.57 g / cm³ 3 Approximately 1.5g / cm 3 Approximately 1.55 g / cm³ 3 Within the range of [etc.]. Additionally, the second active substance CAM2 can have a concentration of approximately 1.1 g / cm³. 3 The tap density may be within a smaller range, and the tap density of the second active substance CAM2 may be, for example, about 0.9 g / cm³. 3 Approximately 1.1 g / cm³ 3 Approximately 1.0 g / cm³ 3 Approximately 1.1 g / cm³ 3 Approximately 0.9 g / cm³ 3 Approximately 1.05 g / cm³ 3 When the particle density and tap density of the second active material CAM2 fall within the above range, the third active material layer ATL3 can have a relatively low rolling density.

[0127] The second active substance CAM2 can have a larger average particle size (D) than the first active substance CAM1. 50 The second active substance CAM2 can have an average particle size (D) in the range of about 10 μm to about 50 μm. 50 For example, the average particle size (D) of the second active substance CAM2. 50 It can be in the range of about 10 μm to about 45 μm, about 10 μm to about 30 μm, or about 5 μm to about 30 μm.

[0128] The second active substance CAM2 can have a larger specific surface area than the first active substance CAM1. The second active substance CAM2 can have a specific surface area of ​​approximately 1.5 m². 2 A relatively large specific surface area of ​​ / g or greater. The specific surface area of ​​the second active substance CAM2 can be, for example, about 1.5m². 2 / g to approximately 2.5m 2 / g, approximately 1.6m 2 / g to approximately 2.3m 2 / g, approximately 1.7m2 / g to approximately 2.1m 2 / g or approximately 1.8m 2 / g to approximately 2.0m 2 Within the range of / g.

[0129] When the specific surface area and average particle size (D) of the second active substance CAM2 50 When the content falls within the above range, the porosity of the electrode surface can be improved.

[0130] Because a material with physical properties within the aforementioned range is used in the third active material layer ATL3, a third active material layer ATL3 with a porosity in the range of, for example, about 16% to about 22% after drying and rolling can be manufactured. Therefore, the high-rate charging and discharging properties of the battery can be improved, and a battery with high capacity and high energy density can be realized.

[0131] According to exemplary embodiments of this disclosure, the porosity of the third active material layer ATL3 can be, for example, in the range of about 16% to about 22%, about 16% to about 21%, about 16% to about 20%, or about 17% to about 20%. Therefore, it is possible to achieve a battery with high capacity and high energy density while reducing plate resistance and improving high-rate charge and discharge properties.

[0132] Furthermore, porosity here can be a value measured after the active material layer has been coated, dried, and rolled, or it can be a value representing the ratio of void spaces within the active material layer, measured using image analysis software. Additionally, porosity can be calculated by comparing theoretical density with actual density.

[0133] In the third active material layer ATL3, the path of lithium ions can be ensured on the surface of the active material layer AML. In the example embodiment, since the active material with a low rolling reduction rate is disposed on the top layer of the multilayer active material layer AML, the porosity on the top side is increased to improve ionic conductivity, thereby improving the charge and discharge properties of the battery.

[0134] According to the example embodiment, the amount of the second active material CAM2 relative to the total weight of the third active material layer ATL3 can be in the range of about 90 wt% to about 99.5%.

[0135] In addition to the second active material CAM2, the third active material layer ATL3 may also include a binder. The binder BND may be the same as the binder described in the first active material layer ATL1.

[0136] According to an example embodiment, the amount of binder BND can be in the range of about 0.01 wt% to about 5 wt% relative to the total weight of the third active material layer ATL3.

[0137] In addition to the second active material CAM2 and the binder BND, the third active material layer ATL3 may also include a conductive material CDM. The conductive material CDM may be the same as the conductive material CDM described in the first active material layer ATL1.

[0138] The amount of conductive material CDM included in the third active material layer ATL3 can be less than the amount of conductive material CDM included in the second active material layer ATL2, which will be described below. The third active material layer ATL3 may include trace amounts of conductive material CDM. For example, the amount of conductive material CDM in the third active material layer ATL3 can be less than about 0.5 wt%.

[0139] According to the example embodiment, the amount of conductive material CDM relative to the total weight of the third active material layer ATL3 can be in the range of about 0.001 wt% to about 0.5 wt%. When the amount of conductive material CDM in the third active material layer ATL3 falls within the above range, the capacity and energy density of the battery can be increased or maximized.

[0140] The second active material layer ATL2 can be in contact with one surface of the first active material layer ATL1. This surface of the first active material layer ATL1 may not be in contact with the electrode current collector COL.

[0141] The second active material layer ATL2 may be or include an active material layer located between the first active material layer ATL1 and the third active material layer ATL3, and may include the first active material CAM1 and the second active material CAM2.

[0142] The first active substance CAM1 may be the same as the first active substance CAM1 described with respect to the first active substance layer ATL1, and the second active substance CAM2 may be the same as the second active substance CAM2 described with respect to the third active substance layer ATL3.

[0143] The second active material layer ATL2 may include a first region RG1 containing the first active material CAM1 and a second region RG2 containing the second active material CAM2.

[0144] The first region RG1 and the second region RG2 can be arranged alternately along the first direction D1.

[0145] For example, the first region RG1 can extend along a second direction D2 that intersects the first direction D1. From a planar perspective, the first region RG1 can be in the form of a line or a strip. The first regions RG1 can be arranged along the first direction D1 and can extend parallel to each other along the second direction D2.

[0146] The first regions RG1 can be spaced apart from each other in the first direction D1. The first region RG1 can be in direct contact with one surface of the first active material layer ATL1.

[0147] Each of the first regions RG1 may have a first width W1 in the first direction D1. The first width W1 of each of the first regions RG1 may be substantially the same or different.

[0148] The second regions RG2 can be arranged between each other in the adjacent first regions RG1. For example, the second regions RG2 can extend parallel to each other in the second direction D2. From a planar viewpoint, the second regions RG2 can take the form of lines or strips.

[0149] The second regions RG2 can be spaced apart from each other in the first direction D1. That is, the second regions RG2 can be disposed between adjacent first regions RG1. The second regions RG2 can be in contact with one surface of the first active material layer ATL1.

[0150] Each of the second regions RG2 may have a second width W2 in the first direction D1. The second width W2 of each of the second regions RG2 may be substantially the same or different.

[0151] According to the example embodiment, the first region RG1 and the second region RG2 can completely cover one surface of the first active material layer ATL1, and the surface of the first active material layer ATL1 can be kept from being exposed to the outside.

[0152] Reference Figure 7 The first width W1 is shown to be the same as the second width W2, but this is for illustrative purposes only, and the disclosure is not limited thereto. For example, the first width W1 may be the same as the second width W2. Alternatively, the first width W1 and the second width W2 may be different from each other. For example, the first width W1 may be greater than the second width W2. For example, the first width W1 may be less than the second width W2.

[0153] According to the example embodiment, the first width W1 and the second width W2 can both be greater than about 1 mm and less than or equal to about 100 nm.

[0154] The second active material layer ATL2 can be divided into regions with different porosities to form a pattern. That is, the second active material layer ATL2 may include a first region RG1 and a second region RG2 with different porosities.

[0155] The first region RG1 may include the first active material CAM1 described in the first active material layer ATL1, and the second region RG2 may include the second active material CAM2 described in the third active material layer ATL3. That is, the second region RG2 may have a relatively higher porosity than the first region RG1.

[0156] In the first region RG1 and the second region RG2, the total area, shape, and size of each region may be the same or different. However, it may be advantageous for the first region RG1 and the second region RG2 to be distributed as uniformly as possible in the second active material layer ATL2 in a coating form, so that no single region is concentrated in a localized portion of the second active material layer ATL2. Therefore, the resistance to lithium ion movement between the first active material layer ATL1, which has low porosity, and the third active material layer ATL3, which has high porosity, can be reduced.

[0157] Depending on the content ratio of the active material, the volume ratio of the first region RG1 to the second region RG2 can be in the range of approximately 1:9 to approximately 9:1 or approximately 3:7 to approximately 5:5. When the volume ratio is less than the values ​​within the above range, there may be limitations such as poor processability or the inability to manufacture batteries with high capacity and high density. When the volume ratio is greater than the values ​​within the above range, the resistance difference between the first region RG1 and the second region RG2 increases, and the structural stability and performance of the battery may decrease.

[0158] The volume of the first region RG1 is calculated by multiplying the first width W1 by the height and length of the first region RG1, and the volume of the second region RG2 is calculated by multiplying the second width W2 by the height and length of the second region RG2. Here, the height of the first region RG1 and the height of the second region RG2 can be substantially the same and can correspond to the thickness TKL2 of the second active material layer ATL2. The length of the first region RG1 and the length of the second region RG2 can be substantially the same and can correspond to the length of the second active material layer ATL2 in the second direction D2.

[0159] According to the example embodiment, the amounts of the first active material CAM1 and the second active material CAM2 can be in the range of about 90 wt% to about 98 wt% relative to the total weight of the second active material layer ATL2.

[0160] According to an example embodiment, the porosity of the second active material layer ATL2 can be less than the porosity of the third active material layer ATL3, and greater than the porosity of the first active material layer ATL1. That is, since the first region RG1 and the second region RG2 are alternately arranged in the second active material layer ATL2, the second active material layer ATL2 can have a porosity value between that of the first active material layer ATL1 and the third active material layer ATL3. In other words, in the electrodes 10 and 20 according to the example embodiments of this disclosure, the porosity of the active material layer located near the electrode current collector COL can be relatively less than the porosity of the active material layer located away from the electrode current collector COL.

[0161] A second active material layer ATL2, after drying and rolling, can be manufactured by alternately arranging a first region RG1 comprising a first active material CAM1 and a second region RG2 comprising a second active material CAM2. According to an example embodiment, the porosity of the second active material layer ATL2 can be, for example, about 10% to about 18%, about 11% to about 17%, about 12% to about 16%, or about 12% to about 15%. Therefore, a battery with high capacity and high energy density can be obtained while reducing the resistance of the plates and improving high-rate charge and discharge properties.

[0162] Furthermore, porosity here can be a value measured after coating, drying, and rolling the active material layer, or it can be a ratio of the area of ​​the pore spaces within the active material layer measured using image analysis software. Additionally, porosity can be calculated by comparing the theoretical density with the actual density.

[0163] In addition to the first active material CAM1 and the second active material CAM2, the second active material layer ATL2 may also include an adhesive BND. The adhesive BND may be the same as the adhesive described in the first active material layer ATL1.

[0164] According to an example embodiment, the amount of adhesive BND may be in the range of about 0.01 wt% to about 5 wt% relative to the total weight of the second active material layer ATL2.

[0165] In addition to the first active material CAM1, the second active material CAM2, and the binder BND, the second active material layer ATL2 may also include a conductive material CDM. The conductive material CDM may be the same as the conductive material CDM described in the first active material layer ATL1.

[0166] The amount of conductive material CDM included in the second active material layer ATL2 can be greater than the amount of conductive material CDM included in the first active material layer ATL1 and the third active material layer ATL3.

[0167] According to an example embodiment, the amount of conductive material CDM in the second active material layer ATL2 can be in the range of about 3 to about 10 times the amount of conductive material CDM in the first active material layer ATL1 or the third active material layer ATL3. For example, the amount of conductive material CDM in the second active material layer ATL2 can be in the range of about 1 wt% to about 5 wt%.

[0168] Meanwhile, when the amount of conductive material CDM in the second active material layer ATL2 is quite high, the content of active material decreases, and therefore the energy density may decrease. Therefore, the amount of conductive material CDM included in the first region RG1 and the second region RG2 can be appropriately adjusted.

[0169] Electrodes 10, 20 according to exemplary embodiments of the present disclosure may include a higher amount of conductive material CDM in the second active material layer ATL2 compared to the first active material layer ATL1 and the third active material layer ATL3, thereby reducing the interface resistance between the first active material layer ATL1 and the third active material layer ATL3.

[0170] Furthermore, electrodes 10, 20 according to exemplary embodiments of this disclosure may include a structure in which a second active material layer ATL2 comprising alternating first regions RG1 and second regions RG2 with different porosities is disposed between the first active material layer ATL1 having relatively low porosity and a third active material layer ATL3 having relatively high porosity. Therefore, the increase in ion resistance due to the increased amount of conductive material CDM in the second active material layer ATL2 can be mitigated, thereby ensuring the path of lithium ions in the active material layer AML.

[0171] For example, when the second active material layer ATL2, in which a first region RG1 and a second region RG2 with different porosities are alternately arranged, is omitted, the interfacial resistance between the layers of the multilayer active material layer increases, which may lead to reduced durability during charging and discharging.

[0172] Electrodes 10, 20 according to exemplary embodiments of the present disclosure have improved ionic conductivity and allow for reduced interfacial resistance between layers of multilayer active material, thereby improving the electrochemical performance, cycle performance, and lifespan characteristics of rechargeable lithium batteries.

[0173] Figure 9 This is a schematic diagram of an electrode for a rechargeable lithium battery according to other exemplary embodiments of this disclosure. Figure 10 This is a cross-sectional view used to describe the electrodes for a rechargeable battery according to other exemplary embodiments of this disclosure, which are along... Figure 9The cross section cut by line I-I' corresponds to the section in the middle.

[0174] In the following text, in the example embodiments, references to the above are omitted. Figures 6 to 8 The explanation provides a detailed description of the repeated technical features and explains the differences in detail.

[0175] Reference Figure 9 and Figure 10 In another exemplary embodiment of the inventive concept, electrodes 10 and 20 may include a double-layer active material layer AML. That is, in another exemplary embodiment of the electrodes 10 and 20 according to this disclosure, [the following may be omitted] Figures 6 to 8 The first active material layer ATL1 is described in the text.

[0176] According to another example embodiment, electrodes 10, 20 may include an electrode current collector COL and an active material layer AML disposed on the electrode current collector COL.

[0177] Electrodes 10 and 20 may have a top surface that is parallel to a first direction D1 and a second direction D2 that intersects the first direction D1 and is orthogonal to a third direction D3. The first direction D1, the second direction D2, and the third direction D3 may, for example, be orthogonal to each other.

[0178] The electrode current collector COL may include the aforementioned current collector COL1 or current collector COL2.

[0179] The active material layer AML may include a first active material layer ATL1 and a second active material layer ATL2 stacked (e.g., sequentially stacked) on the electrode current collector COL. For example, the active material layer AML may include a first active material layer ATL1 disposed on the electrode current collector COL and a second active material layer ATL2 disposed on the first active material layer ATL1.

[0180] The first active material layer ATL1 may have a thickness TKL1 on the third direction D3, and the second active material layer ATL2 may have a thickness TKL2 on the third direction D3. The thickness TKL of the active material layer AML may be the sum of the thickness TKL1 of the first active material layer ATL1 and the thickness TKL2 of the second active material layer ATL2.

[0181] The thickness TKL1 of the first active material layer ATL1 can be in the range of about 30% to about 100%, about 30% to about 90%, or about 30% to about 70% relative to the thickness of the second active material layer ATL2.

[0182] When the thickness TKL1 of the first active material layer ATL1 is less than the above range, the conductivity tends to decrease. Conversely, when the thickness TKL1 of the first active material layer ATL1 exceeds the above range, there is a disadvantage of increased interfacial resistance.

[0183] For example, the thickness ratio of the first active material layer ATL1 to the second active material layer ATL2, TKL1:TKL2, can be about 1:1, about 0.9:1, about 0.7:1, about 0.5:1, or about 0.3:1.

[0184] Figure 11 This is an enlarged view depicting electrodes according to other exemplary embodiments of this disclosure. That is, Figure 11 It is magnification Figure 10 An enlarged view of the area "M" shown.

[0185] Reference Figure 11 The first active material layer ATL1 can be in contact with one surface of the electrode current collector COL. This surface of the first active material layer ATL1 can be the surface on which the first active material layer ATL1 contacts the electrode current collector COL.

[0186] The first active material layer ATL1 may be an active material layer in contact with the electrode current collector COL among multiple active material layers, and may include the first active material CAM1 and the second active material CAM2.

[0187] The first active substance CAM1 can interact with the above-mentioned... Figures 6 to 8 The first active substance CAM1 described is the same as that described above, and the second active substance CAM2 can be the same as that described above. Figures 6 to 8 The second active substance described is the same as CAM2.

[0188] The first active material layer ATL1 may include a first region RG1 containing the first active material CAM1 and a second region RG2 containing the second active material CAM2.

[0189] The first region RG1 and the second region RG2 can be arranged alternately along the first direction D1.

[0190] For example, the first regions RG1 can extend parallel to each other in a second direction D2 that intersects the first direction D1. From a planar viewpoint, the first regions RG1 can have the shape of a line or a strip. The first regions RG1 can be arranged along the first direction D1 and can extend parallel to each other in the second direction D2.

[0191] The first regions RG1 can be spaced apart from each other in the first direction D1. The first region RG1 can be in direct contact with one surface of the electrode current collector COL.

[0192] Each of the first regions RG1 may have a first width W1 in the first direction D1. The first width W1 of each of the first regions RG1 may be the same as or different from each other.

[0193] The second regions RG2 can be arranged between each other in a first region RG1 that is adjacent to each other. For example, the second regions RG2 can extend parallel to each other in the second direction D2. From a planar viewpoint, the second regions RG2 can have the shape of a line or a strip.

[0194] The second regions RG2 can be spaced apart from each other in the first direction D1. That is, the second regions RG2 can be disposed between the first regions RG1 that are adjacent to each other along the first direction D1. The second regions RG2 can be in direct contact with one surface of the electrode current collector COL.

[0195] Each of the second regions RG2 may have a second width W2 in the first direction D1. The second width W2 of each of the second regions RG2 may be the same or different from each other.

[0196] According to the example embodiment, the first region RG1 and the second region RG2 can completely cover one surface of the electrode current collector COL, and the surface of the electrode current collector COL can be kept out of the external environment.

[0197] The shape or composition of the first region RG1 and the second region RG2 can be similar to... Figures 6 to 8 The structure of the second active material layer ATL2 described in the text is the same.

[0198] For example, the first width W1 can be the same as the second width W2. Alternatively, the first width W1 can be different from the second width W2. For example, the first width W1 can be greater than the second width W2. For example, the first width W1 can be less than the second width W2.

[0199] Depending on the molar ratio of the active substances, the volume ratio of the first region RG1 to the second region RG2 can be a ratio in the range of about 1:9 to 9:1, about 3:7 to about 5:5.

[0200] The volume of the first region RG1 is determined by multiplying the first width W1 by the height and length of the first region RG1, and the volume of the second region RG2 is determined by multiplying the second width W2 by the height and length of the second region RG2. Here, the height of the first region RG1 and the height of the second region RG2 are the same, and correspond to the thickness TKL1 of the first active material layer ATL1. The length of the first region RG1 and the length of the second region RG2 are the same, and correspond to the length of the first active material layer ATL1 in the second direction D2.

[0201] According to the example embodiment, the amounts of the first active material CAM1 and the second active material CAM2 relative to the total weight of the first active material layer ATL1 can be in the range of about 90 wt% to about 98 wt%.

[0202] The first active material layer ATL1 can be divided into regions with different porosities to form a pattern. For example, the first active material layer ATL1 may include a first region RG1 and a second region RG2 with different porosities.

[0203] The first region RG1 may include the first active material CAM1, and the second region RG2 may include the second active material CAM2. For example, the second region RG2 may have a relatively higher porosity than the first region RG1.

[0204] According to the example embodiment, the porosity of the first active material layer ATL1 can be less than the porosity of the second active material layer ATL2.

[0205] By alternately arranging the first active material CAM1 and the second active material CAM2 in the first active material layer ATL1, a first active material layer ATL1 with a porosity in the range of about 10% to about 18% after drying and rolling can be manufactured.

[0206] According to the example embodiment, the porosity of the first active material layer ATL1 can be in the range of about 10% to about 18%, about 11% to about 17%, about 12% to about 16%, or about 12% to about 15%.

[0207] In addition to the first active material CAM1 and the second active material CAM2, the first active material layer ATL1 may also include an adhesive BND. The adhesive BND may be the same as the adhesive BND described above.

[0208] In addition to the first active material CAM1, the second active material CAM2, and the binder BND, the first active material layer ATL1 may also include a conductive material CDM. The conductive material CDM may be the same as the conductive material CDM described above.

[0209] The amount of conductive material CDM included in the first active material layer ATL1 can be greater than the amount of conductive material CDM included in the second active material layer ATL2, which will be described below.

[0210] According to another example embodiment, the amount of conductive material CDM in the first active material layer ATL1 can be in the range of about 3 to about 10 times the amount of conductive material CDM in the second active material layer ATL2, which will be described below. For example, the amount of conductive material CDM in the first active material layer ATL1 can be in the range of about 1 wt% to about 5 wt%.

[0211] The second active material layer ATL2 may be in contact with a surface of the first active material layer ATL1. This surface of the first active material layer ATL1 may be a surface on which the first active material layer ATL1 is not in contact with the electrode current collector COL. The second active material layer ATL2 is located on the outermost side of the double active material layer and may include the second active material CAM2.

[0212] The second active substance CAM2 may be the same as or different from the first active substance CAM1 described above. For example, the second active substance CAM2 may have different physical properties than the first active substance CAM1 described above. For example, the second active substance CAM2 may have a lower particle density and tap density than the first active substance CAM1, and a larger average particle size (D) than the first active substance CAM1. 50 ).

[0213] The second active material CAM2 can be a material with a relatively low rolling reduction rate. The particle density and tap density of the second active material CAM2 can be lower than those of the first active material CAM1.

[0214] According to an example embodiment, the porosity of the second active material layer ATL2 can be in the range of, for example, about 16% to about 22%, about 16% to about 21%, about 16% to about 20%, or about 17% to about 19%. Furthermore, here, the porosity can be measured after the active material layer has been coated, dried, and rolled, and can be a ratio of the area of ​​the void spaces within the active material layer measured using image analysis software. Therefore, a battery with high capacity and high energy density can be obtained, which has reduced plate resistance and improved high-rate charge and discharge performance.

[0215] In the second active material layer ATL2, lithium ion pathways can be ensured on the surface of the active material layer AML. In an example embodiment, by providing an active material with a low rolling reduction rate on the top layer of the active material layer, the porosity of the top layer can be increased to improve ionic conductivity, thereby improving the high-rate charging and discharging properties of the battery.

[0216] According to the example embodiment, the amount of the second active material CAM2 relative to the total weight of the second active material layer ATL2 can be in the range of about 90 wt% to about 99.5 wt%.

[0217] In addition to the second active material CAM2, the second active material layer ATL2 may also include an adhesive BND. The adhesive BND may be the same as the adhesive described above.

[0218] According to an example embodiment, the amount of adhesive BND can be in the range of about 0.01 wt% to about 5 wt% relative to the total weight of the second active material layer ATL2.

[0219] In addition to the second active material CAM2 and the binder BND, the second active material layer ATL2 may also include a conductive material CDM. The conductive material CDM may be the same as the conductive material CDM described above.

[0220] The amount of conductive material CDM included in the second active material layer ATL2 can be less than the amount of conductive material CDM included in the first active material layer ATL1. The second active material layer ATL2 may include trace amounts of conductive material CDM. For example, the amount of conductive material CDM in the second active material layer ATL2 may be in the range of about 0.5 wt% or less.

[0221] According to the example embodiment, the amount of conductive material CDM relative to the total weight of the second active material layer ATL2 can be in the range of about 0.001 wt% to about 0.5 wt%. When the amount of conductive material CDM in the second active material layer ATL2 falls within the above range, the capacity and energy density of the battery can be increased or maximized.

[0222] According to another example embodiment, electrodes 10 and 20 include a higher amount of conductive material CDM within the first active material layer ATL1 compared to the second active material layer ATL2, thus improving their conductivity. Furthermore, since the first region RG1 and the second region RG2 with different porosities are arranged alternately, the resistance to ions caused by the increased amount of conductive material CDM in the first active material layer ATL1 can be reduced, thus ensuring the path of lithium ions.

[0223] Furthermore, in electrodes 10 and 20 according to another example embodiment of the present disclosure, since the active material with a low rolling reduction rate is disposed on the top layer of the multilayer active material layer, and the porosity in the top side is increased, thereby improving the ionic conductivity, and the porosity in the bottom layer is reduced, thereby increasing the energy density, a battery with high capacity and high energy density can be obtained.

[0224] Methods for preparing electrodes Figure 12A This is a diagram illustrating a method of manufacturing an electrode according to an exemplary embodiment of the present disclosure.

[0225] Reference Figure 12AA method for manufacturing an electrode according to an example embodiment of the present disclosure may include: providing an electrode current collector COL; forming a first active material layer ATL1 on the electrode current collector COL; forming a second active material layer ATL2 on the first active material layer ATL1; and forming a third active material layer ATL3 on the second active material layer ATL2.

[0226] In an example embodiment, the first active material layer ATL1 may include Figure 8 The first active material CAM1, the binder BND, and the conductive material CDM are described in the text. Additionally, the second active material layer ATL2 may include... Figure 8 The first active material CAM1, the second active material CAM2, the binder BND, and the conductive material CDM are described in the text. Additionally, the third active material layer ATL3 may include... Figure 8 The second active substance CAM2, binder BND, and conductive material CDM are described in the text.

[0227] The electrode current collector COL, the first active material layer ATL1, the second active material layer ATL2, and the third active material layer ATL3 can each have the properties specified above. Figure 8 The electrodes 10 and 20 in the example embodiments described have the same construction, so their detailed description is omitted.

[0228] The formation of the second active material layer ATL2 may include a process for forming a patterned coating layer. The patterned coating layer can be formed using common coating processes, such as slot coating, photolithography, micro-contact printing, screen printing, spraying, etc., but other processes may also be used.

[0229] The second active material layer ATL2 may include a first region RG1 containing a first active material CAM1 and a second region RG2 containing a second active material CAM2. The first region RG1 and the second region RG2 may be arranged alternately along a first direction D1. The first region RG1 may extend parallel to each other in a second direction D2 that intersects the first direction D1, and the second region RG2 may extend parallel to each other in the second direction D2.

[0230] According to exemplary embodiments, at least one of the formation of the first active material layer ATL1, the second active material layer ATL2, and the third active material layer ATL3 can be performed using either a wet process or a dry process. In exemplary embodiments, the first active material layer ATL1, the second active material layer ATL2, and the third active material layer ATL3 can be formed using a wet process, or they can be formed using a dry process. However, the exemplary embodiments of this disclosure are not limited thereto.

[0231] For wet processes, active materials CAM1 and CAM2, binder BND, and conductive material CDM can be mixed in a solvent to prepare an electrode mixture, which can then be coated onto an electrode current collector COL, dried, and rolled. Solvents commonly used in the art can be used as the solvent in the slurry. For example, at least one of dimethyl sulfoxide (DMSO), isopropanol, N-methylpyrrolidone (NMP), acetone, water, and combinations thereof can be included.

[0232] For dry processes, active materials CAM1 and CAM2, binder BND, and conductive material CDM, which are in a dry state, can be dry-mixed without solvents to prepare an electrode mixture, which can then be placed on an electrode current collector COL and rolled.

[0233] Figure 12B This is a diagram illustrating a method of manufacturing an electrode according to another example embodiment.

[0234] Reference Figure 12B A method for preparing an electrode according to another example embodiment may include: providing an electrode current collector COL; forming a first active material layer ATL1 on the electrode current collector COL; and forming a second active material layer ATL2 on the first active material layer ATL1.

[0235] In an example embodiment, the first active material layer ATL1 may include Figure 11 The first active material CAM1, the second active material CAM2, the binder BND, and the conductive material CDM are described herein. Additionally, the second active material layer ATL2 may include... Figure 11 The second active substance CAM2, binder BND, and conductive material CDM are described in the text.

[0236] The electrode current collector COL, the first active material layer ATL1, and the second active material layer ATL2 can each have the same properties as described above. Figure 11 The electrodes 10 and 20 described have the same construction, therefore, their detailed description is omitted below.

[0237] Forming the first active material layer ATL1 may include forming a patterned coating layer. Common coating processes can be used to form the patterned coating layer, such as slot coating, photolithography, micro-contact printing, screen printing, spraying, etc., but other processes may also be used.

[0238] The first active material layer ATL1 may include a first region RG1 containing a first active material CAM1 and a second region RG2 containing a second active material CAM2. The first region RG1 and the second region RG2 may be arranged alternately along a first direction D1. The first region RG1 may extend parallel to each other in a second direction D2 that intersects the first direction D1, and the second region RG2 may extend parallel to each other in the second direction D2.

[0239] According to another example embodiment, at least one of the formation of the first active material layer ATL1 and the formation of the second active material layer ATL2 can be carried out by a wet process or a dry process.

[0240] In the following description, the positive electrode 10 and negative electrode 20 manufactured according to the above process may be subjected to a rolling process, a cutting or slitting process, and a grooving process in sequence. The rechargeable lithium battery according to this disclosure can be manufactured by stacking (e.g., sequentially stacking) the positive electrode 10, the separator 30, and the negative electrode 20 and providing an electrolyte.

[0241] As a non-limiting example, the rechargeable lithium battery according to exemplary embodiments of this disclosure can be used in, for example, automobiles, mobile phones and / or various types of electronic devices.

[0242] The present disclosure is explained below with reference to examples and comparative examples. However, the following examples are merely illustrative for explaining the present disclosure, and the scope of the disclosure is not limited thereto.

[0243] Example 1 1) Manufacturing of positive electrode paste The average particle size (D) of the first active substance 50 The LiNi is approximately 15 μm in size. 0.8 Mn 0.1 Co 0.1 O2 (NCM), carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder resin were added to the solvent N-methylpyrrolidone (NMP) in a weight ratio of approximately 98:0.5:1.5 to prepare a first active material slurry.

[0244] The average particle size (D) of the second active substance 50 The LiNi is approximately 30 μm in size. 0.8 Mn 0.1 Co 0.1 O2 (NCM), carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder resin were added to the solvent N-methylpyrrolidone (NMP) in a weight ratio of approximately 98:0.5:1.5 to prepare a second active material slurry.

[0245] A first active material, carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder resin are added to a solvent N-methylpyrrolidone (NMP) in a weight ratio of approximately 96:2.5:1.5 to prepare a first area coating slurry.

[0246] Next, the second active material, carbon black as a conductive material, and polyvinylidene fluoride (PVdF) as a binder resin are added to the solvent N-methylpyrrolidone (NMP) in a weight ratio of approximately 96:2.5:1.5 to prepare a second area coating slurry.

[0247] 2) Manufacturing of the positive electrode Formation of the first active substance layer: The first active material slurry is applied to an aluminum film with a thickness of about 15 μm, which serves as the positive electrode current collector, and dried to form a first active material layer with a thickness of about 50 μm.

[0248] Formation of the second active substance layer: A surface of the first active material layer is coated with a first area coating slurry and a second area coating slurry, and then dried to form a second active material layer with a thickness of about 50 μm.

[0249] The first region formed by coating the first region with a first region slurry and the second region formed by coating the second region slurry are arranged alternately, each of the first and second regions having a stripe shape with a width of about 10 mm, and the volume ratio of the first region to the second region is about 5:5.

[0250] Formation of the third active substance layer: The manufactured second active material slurry is applied onto the second active material layer and dried to form a third active material layer with a thickness of about 50 μm.

[0251] Subsequently, rolling is performed to manufacture a positive electrode in which an aluminum current collector, a first active material layer, a second active material layer, and a third active material layer are sequentially stacked.

[0252] The porosity of each active material layer was measured using ImageJ software. The porosity of the first active material layer was approximately 12%, the porosity of the third active material layer was approximately 20%, the porosity of the first region in the second active material layer was approximately 12%, and the porosity of the second region in the second active material layer was approximately 20%.

[0253] 3) Manufacturing of rechargeable lithium batteries Approximately 98 wt% of a negative electrode active material in which graphite and Si composite are mixed at a weight ratio of approximately 92:8, approximately 1 wt% of styrene-butadiene rubber (SBR), and approximately 1 wt% of carboxymethyl cellulose (CMC) were mixed and then injected into distilled water. The mixture was stirred using a mechanical stirrer for approximately 60 minutes to prepare a negative electrode active material slurry. The slurry was then coated onto a copper current collector with a thickness of approximately 10 μm to a thickness of approximately 60 μm using a doctor blade. The mixture was dried in a hot air dryer at approximately 100 °C for approximately 0.5 hours, then dried again under vacuum at approximately 120 °C for approximately 4 hours, and finally rolled to prepare the negative electrode.

[0254] An electrolyte is prepared by dissolving approximately 1.15 M of LiPF6 in a non-aqueous organic solvent in which ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) are mixed in a volume ratio of approximately 20:40:40.

[0255] The positive electrode, negative electrode, and polyethylene separator with a thickness of about 16 μm are assembled to manufacture the electrode assembly, and the electrolyte is injected to manufacture the rechargeable lithium battery.

[0256] Example 2 Formation of the first active substance layer: A surface of the positive electrode current collector is coated with a first region coating slurry and a second region coating slurry, and dried to form a first active material layer with a thickness of about 50 μm.

[0257] The first region formed by coating the first region with a first region slurry and the second region formed by coating the second region slurry are arranged alternately, each of the first and second regions having a stripe shape with a width of about 10 mm, and the volume ratio of the first region to the second region is about 5:5.

[0258] Formation of the second active substance layer: The manufactured second active material slurry is applied onto the first active material layer and dried to form a second active material layer with a thickness of about 50 μm.

[0259] Subsequently, rolling is performed to manufacture a positive electrode in which an aluminum current collector, a first active material layer, and a second active material layer are sequentially stacked.

[0260] As a result of measuring the porosity of each active material layer using ImageJ software, the porosity of the second active material layer is approximately 20%, the porosity of the first region in the first active material layer is approximately 12%, and the porosity of the second region in the first active material layer is approximately 20%.

[0261] Example 3 In addition to using an average particle size (D) of approximately 5 μm in the fabrication of the positive electrode. 50 LiNi 0.8 Mn 0.1 Co 0.1 O2 is used as the primary active ingredient, and an average particle size (D) of approximately 30 μm is employed. 50 LiNi 0.8 Mn 0.1 Co 0.1 In addition to using O2 as a second active material, the positive electrode and rechargeable lithium battery are manufactured in the same manner as in Example 1.

[0262] In this case, as a result of measuring the porosity of each active material layer using ImageJ software, the porosity of the first active material layer is about 8%, the porosity of the third active material layer is about 20%, the porosity of the first region in the second active material layer is about 8%, and the porosity of the second region in the second active material layer is about 20%.

[0263] Example 4 The positive electrode and the rechargeable lithium battery are manufactured in the same manner as in Example 1, except that: in the manufacture of the positive electrode, the components in the first region coating slurry are mixed such that the weight ratio of the first active material, the conductive material and the binder is approximately 95:3.5:1.5, and in the manufacture of the positive electrode, the components in the second region coating slurry are mixed such that the weight ratio of the second active material, the conductive material and the binder is approximately 95:3.5:1.5.

[0264] As a result of measuring the porosity of each active material layer using ImageJ software, the porosity of the first active material layer is approximately 12%, the porosity of the third active material layer is approximately 20%, the porosity of the first region in the second active material layer is approximately 12%, and the porosity of the second region in the second active material layer is approximately 20%.

[0265] Comparative Example 1: A structure with a double layer of active material without coating the active material including the first and second regions. Positive electrode of the sexual material layer Formation of the first active substance layer: The first active material slurry is applied to an aluminum film with a thickness of about 15 μm, which serves as an electrode current collector, and dried to form a first active material layer with a thickness of about 50 μm.

[0266] Formation of the second active substance layer: The manufactured second active material slurry is applied onto the first active material layer and dried to form a second active material layer with a thickness of about 50 μm.

[0267] Subsequently, rolling is performed to manufacture a positive electrode in which an aluminum current collector, a first active material layer, and a second active material layer are sequentially stacked.

[0268] Comparative Example 2: A structure with three active material layers without increasing the activity of the first and second regions. The positive electrode of the conductive material in the conductive material layer The positive electrode and the rechargeable lithium battery are manufactured in the same manner as in Example 1, except that: in the manufacture of the positive electrode, the components in the first region coating slurry are mixed such that the weight ratio of the first active material, the conductive material and the binder is approximately 98:0.5:1.5, and in the manufacture of the positive electrode, the components in the second region coating slurry are mixed such that the weight ratio of the second active material, the conductive material and the binder is approximately 98:0.5:1.5.

[0269] The components of the positive electrode according to the example and comparative examples are listed in Table 1 below.

[0270] Table 1:

[0271] Evaluation Example 1: Resistance Measurement The resistance of the mixture layer of electrodes (positive electrodes) manufactured according to the various examples and comparative examples is measured.

[0272] The resistance of each mixture layer was measured five times at room temperature (approximately 25°C) using a Laresta-GP (MCP-T600 type, manufactured by Mitsubishi Chemical), and the average value was obtained. The results are listed in Table 2 below. Here, the mixture layer refers to the active material layer stacked on the current collector.

[0273] Table 2:

[0274] As shown in Table 2, when using the electrodes of the examples (Examples 1 to 4) according to this disclosure, it can be confirmed that the resistance of the entire mixture layer is significantly reduced compared to the electrodes according to the comparative examples.

[0275] Therefore, the electrode according to the example of this disclosure can provide current dispersion by alternately arranging the first region and the second region in the second active material layer.

[0276] Evaluation Example 2: Measurement of Battery Life Rechargeable lithium batteries manufactured according to the example and comparative examples were subjected to 300 charge and discharge cycles under 0.5C charging (CC / CV, 4.25V, 0.05C cutoff) / 0.5C discharging (CC, 2.8V cutoff) conditions. The discharge capacity was measured, and the capacity retention rate was calculated. The results are listed in Table 3 below. The capacity retention rate is calculated according to Equation 1 below.

[0277] Equation 1: Capacity retention (%) = (Discharge capacity at 300th cycle / Initial discharge capacity) × 100 Table 3:

[0278] Referring to Table 3 above, it can be confirmed that when using electrodes (Examples 1 to 4) according to the present disclosure, the capacity retention rate at room temperature is improved based on charge and discharge cycles compared to the capacity retention rate of electrodes according to the comparative examples at room temperature.

[0279] The electrode according to this disclosure includes layers of active material in which first and second regions, each with a different porosity, are alternately arranged, which allows lithium ions to move easily within the electrode. Therefore, the lifespan characteristics of rechargeable lithium batteries can be improved.

[0280] Therefore, although exemplary embodiments of this disclosure have been described with reference to the accompanying drawings, this disclosure can be implemented in other specific forms without altering its technical concept or essential characteristics. It should be understood that the above exemplary embodiments are illustrative in all respects and not restrictive.

Claims

1. An electrode for a rechargeable lithium battery, the electrode comprising: An electrode current collector; And A multi-layer active material layer on the electrode current collector, Wherein the multi-layer active material layer includes a first active material layer, a second active material layer, and a third active material layer stacked on the electrode current collector, The first active material layer includes a first active material, The third active material layer includes a second active material, The second active material layer includes: a first region including the first active material; and a second region including the second active material, The first region and the second region are alternately arranged along a first direction, The first region extends parallel to each other in a second direction intersecting the first direction, The second region extends parallel to each other in the second direction, The third active material layer has a porosity greater than that of the second active material layer, and The second active material layer has a porosity greater than that of the first active material layer.

2. The electrode according to claim 1, in, At least one of the first active material layer, the second active material layer, and the third active material layer further includes a binder and a conductive material, and The amount of the conductive material in the second active material layer is 3 to 10 times greater than the amount of the conductive material in the first active material layer or the third active material layer.

3. The electrode according to claim 2, wherein, The amount of the conductive material in each of the first active material layer and the third active material layer is in the range of 0.001 wt% to 0.5 wt%.

4. The electrode according to claim 2, wherein, The amount of the conductive material in the second active material layer is in the range of 1 wt% to 5 wt%.

5. The electrode according to claim 2, wherein, The conductive material includes at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube.

6. The electrode according to claim 2, wherein, The binder includes at least one of rubber-based binders, acrylate-based binders, polyvinylidene fluoride-based binders, polyvinylpyrrolidone-based binders, nitrile-based binders, acetate-based binders, polyvinyl alcohol-based binders, and cellulose-based binders.

7. The electrode according to claim 1, in, The average particle size D of the first active material 50 Smaller than the average particle size D of the second active material 50 , The first active material has an average particle size D in the range of 2 μm to 30 μm. 50 ,and The second active material has an average particle size D in the range of 10 μm to 50 μm. 50 .

8. The electrode according to claim 1, wherein, Both the first active material and the second active material are independently represented by the following formula 1: Formula 1: Li x4 M 1 y M 2 z M 3 1-y-z O 2-a X a Wherein, in the above formula 1, 0.5 ≤ x4 ≤ 1.8, 0 ≤ a ≤ 0.05, 0 < y ≤ 1, 0 ≤ z ≤ 1, and 0 ≤ y + z ≤ 1, M 1 M 2 and M 3 Each independently includes one or more of Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Zr, La, and combinations thereof, and X includes one or more of F, S, P, and Cl.

9. The electrode according to claim 1, wherein, The volume ratio of the first region to the second region is in the range of 1:9 to 9:

1.

10. The electrode according to claim 1, wherein, The second active material layer has a thickness in the range of 30% to 100% of the thickness of one of the first active material layer and the third active material layer.

11. An electrode for a rechargeable lithium battery, the electrode comprising: An electrode current collector; A first active material layer on the electrode current collector; And A second active material layer on the first active material layer, Wherein the first active material layer includes: a first region including a first active material; and a second region including a second active material, The first region and the second region are alternately arranged along a first direction, The first regions extend parallel to each other in a second direction that intersects the first direction, The second regions extend parallel to each other in the second direction, The second active material layer includes the second active material, and The second active material layer has a rolling density lower than that of the first active material layer.

12. The electrode according to claim 11, wherein, The second active material layer has a porosity larger than that of the first active material layer.

13. The electrode according to claim 11, in, At least one of the first active material layer and the second active material layer further includes a binder and a conductive material, The amount of the conductive material in the first active material layer is in the range of 3 to 10 times the amount of the conductive material in the second active material layer.

14. The electrode according to claim 13, wherein, The amount of the conductive material in the first active material layer is in the range of 1 wt% to 5 wt%.

15. The electrode according to claim 13, in, The conductive material includes at least one of natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, carbon fiber, carbon nanofiber, and carbon nanotube, and The binder includes at least one of a rubber binder, an acrylate binder, a polyvinylidene fluoride binder, a polyvinylpyrrolidone binder, a nitrile binder, an acetate binder, a polyvinyl alcohol binder, and a cellulose binder.

16. The electrode according to claim 11, in, The average particle size D of the first active material 50 Smaller than the average particle size D of the second active material 50 , The average particle size D of the first active material 50 Within the range of 2μm to 30μm, and The average particle size D of the second active material 50 Within the range of 10μm to 50μm.

17. The electrode according to claim 11, in, Both the first active material and the second active material are independently represented by the following Formula 1: Formula 1: Li x4 M 1 y M 2 z M 3 1-y-z O 2-a X a Wherein, in the above Formula 1, 0.5 ≤ x4 ≤ 1.8, 0 ≤ a ≤ 0.05, 0 < y ≤ 1, 0 ≤ z ≤ 1, and 0 ≤ y + z ≤ 1, M 1 M 2 and M 3 Each independently includes one or more of Ni, Co, Mn, Al, B, Ba, Ca, Ce, Cr, Fe, Mo, Nb, Si, Sr, Mg, Ti, V, W, Zr, La, and combinations thereof, and X includes one or more of F, S, P, and Cl.

18. The electrode according to claim 11, wherein, The volume ratio of the first region to the second region is in the range of 1:9 to 9:

1.

19. The electrode according to claim 11, wherein, The first active material layer has a thickness in the range of 30% to 100% of the thickness of the second active material layer.

20. A rechargeable lithium battery, the rechargeable lithium battery comprising: A positive electrode; A negative electrode; A separator between the positive electrode and the negative electrode; And An electrolyte, Wherein, at least one of the positive electrode and the negative electrode includes the electrode according to any one of claims 1 to 19.

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