Positive electrode and rechargeable lithium battery including same

Abstract

The invention relates to a positive electrode and a rechargeable lithium battery including the same. A positive electrode for rechargeable lithium includes a positive electrode current collector. The first active material layer is provided on the positive electrode current collector and includes first particles, second particles, a first binder, and a first conductive material. The second active material layer is provided on the first active material layer and includes third particles, a second binder, and a second conductive material. The first particles contain an olivine structured compound, the second particles contain a layered compound, the third particles contain an olivine structured compound, the first particles are single particles, and the first particles have an average diameter of about 100 nm to about 2 [mu] m. The first active material layer and the second active material layer have a cobalt (Co) content of less than about 100 ppm. The average diameter of the second particles is greater than the average diameter of the first particles. The third particles are single particles, and the third particles have an average diameter of about 100 nm to about 2 [mu] m.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0057103, filed on April 29, 2024, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This disclosure relates to a positive electrode and a rechargeable lithium battery including a positive electrode. More specifically, this disclosure relates to a positive electrode including an olivine-based lithium compound (an olivine-structured compound) and a rechargeable lithium battery including a positive electrode. Background Technology

[0004] The rapid proliferation of battery-powered devices, such as mobile phones, laptops, and electric vehicles, has driven a dramatic increase in demand for rechargeable lithium-ion batteries with high energy density and capacity. Consequently, extensive research has focused on improving the performance of rechargeable lithium-ion batteries.

[0005] A rechargeable lithium-ion battery includes a positive electrode and a negative electrode, each comprising an active material that allows lithium ions to intercalate and deintercalate, and an electrolyte. The battery generates electrical energy through redox reactions that occur when lithium ions intercalate into or deintercalate from the positive and negative electrodes. Summary of the Invention

[0006] This disclosure provides a positive electrode for a rechargeable lithium-ion battery, which increases the bonding force between the positive electrode active material layer and the positive electrode current collector, reduces the resistance of the electrode plate, and facilitates the fabrication of the electrode plate. This disclosure also provides a rechargeable lithium-ion battery with excellent capacity and lifespan characteristics, as well as high operating voltage and energy density.

[0007] Embodiments of this disclosure provide a positive electrode for a rechargeable lithium battery, comprising a positive electrode current collector, a first active material layer on the positive electrode current collector, and a second active material layer on the first active material layer. The first active material layer comprises a first particle, a second particle, a first binder, and a first conductive material. The second active material layer comprises a third particle, a second binder, and a second conductive material. The first particle is a olivine-structured compound of Formula 1, the second particle is a layered compound of Formula 2, and the third particle is a olivine-structured compound of Formula 3. The first and second active material layers have a cobalt content of less than about 100 ppm. The first particle is a single particle with an average diameter of about 100 nm to about 2 μm. The average diameter of the second particle is greater than the average diameter of the first particle. The third particle is a single particle with an average diameter of about 100 nm to about 2 μm.

[0008] Formula 1:

[0009] Li 4-b3 , , y3 , , , a3 , ,

[0017] , z3 ,

[0016] ,

[0015] , x3 ,

[0014] Mn x1 Fe y1 B1 z1 PO 4-b1

[0010] In Formula 1, 0.8 ≤ a1 ≤ 1.2, 0.4 ≤ x1 ≤ 0.8, 0 ≤ y1 ≤ 0.6, 0 ≤ z1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, and x1 + y1 + z1 = 1 are satisfied, and B1 includes at least one of Al, Ti, V, and Mg.

[0011] Formula 2:

[0012] Li a2 Ni x2 Mn z2 Al c2 Y d2 O 2-b2

[0013] In Formula 2, 0.8 < a2 ≤ 1.2, 0.7 ≤ x2 ≤ 0.8, 0.2 ≤ z2 ≤ 0.3, 0 ≤ c2 ≤ 0.02, 0 ≤ d2 ≤ 0.003, 0 ≤ b2 ≤ 0.05, and x2 + z2 + c2 + d2 = 1 are satisfied, and Y includes at least one of Ti, Mg, Zr, Mo, and Nb.

[0014] Formula 3:

[0015] Li a3 Mn x3 Fe y3 B3 z3 PO 4-b3

[0016] In Formula 3, 0.8 ≤ a3 ≤ 1.2, 0.4 ≤ x3 ≤ 0.8, 0 ≤ y3 ≤ 0.6, 0 ≤ z3 ≤ 0.05, 0 ≤ b3 ≤ 0.05, and x3 + y3 + z3 = 1 are satisfied, and B3 includes at least one of Al, Ti, V, and Mg.

[0017] In an embodiment of the present disclosure, a positive electrode for a rechargeable lithium battery includes a positive electrode current collector, a first active material layer on the positive electrode current collector, and a second active material layer on the first active material layer. The first active material layer includes first particles, second particles, a first binder, and a first conductive material. The second active material layer includes third particles, a second binder, and a second conductive material. The first particles are an olivine-structured compound of Formula 1, the second particles are a layered compound of Formula 2, the third particles are an olivine-structured compound of Formula 3. The first active material layer and the second active material layer have a cobalt content of less than about 100 ppm. The first particles are single particles, the first particles have an average diameter of about 100 nm to about 2 μm, the average diameter of the second particles is greater than the average diameter of the first particles. Each of the third particles includes a plurality of fourth particles agglomerated together, the third particles have an average diameter of about 3 μm to about 10 μm, the fourth particles are primary particles, and the fourth particles have an average diameter of about 200 nm or less.

[0018] Formula 1:

[0019] Li a1 Mn x1 Fe y1 B1 z1 PO 4-b1

[0020] In Formula 1, 0.8 ≤ a1 ≤ 1.2, 0.4 ≤ x1 ≤ 0.8, 0 ≤ y1 ≤ 0.6, 0 ≤ z1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, and x1 + y1 + z1 = 1, and B1 includes at least one of Al, Ti, V, and Mg.

[0021] Formula 2:

[0022] Li a2 Ni x2 Mn z2 Al c2 Y d2 O 2-b2

[0023] In Formula 2, 0.8 < a2 ≤ 1.2, 0.7 ≤ x2 ≤ 0.8, 0.2 ≤ z2 ≤ 0.3, 0 ≤ c2 ≤ 0.02, 0 ≤ d2 ≤ 0.003, 0 ≤ b2 ≤ 0.05, and x2 + z2 + c2 + d2 = 1, and Y includes at least one of Ti, Mg, Zr, Mo, and Nb.

[0024] Formula 3:

[0025] Li a3 Mn x3 Fe y3 B3 z3 PO4-b3

[0026] In Equation 3, the following conditions must be met: 0.8≤a3≤1.2, 0.4≤x3≤0.8, 0≤y3≤0.6, 0≤z3≤0.05, 0≤b3≤0.05, and x3+y3+z3=1, and B3 includes at least one of Al, Ti, V and Mg.

[0027] In embodiments of this disclosure, the rechargeable lithium battery includes the aforementioned positive electrode. Attached Figure Description

[0028] The accompanying drawings are included to provide a further understanding of this disclosure, and are incorporated in and form a part of this specification. The drawings illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure. In the drawings:

[0029] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to an embodiment of the present disclosure;

[0030] Figures 2-5 This is a schematic diagram illustrating a rechargeable lithium battery according to an embodiment of the present disclosure. Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown, and Figure 4 and Figure 5 A pouch-type battery is shown;

[0031] Figure 6 A cross-sectional view of a positive electrode for a rechargeable lithium battery according to an embodiment of the present disclosure.

[0032] Figure 7 An enlarged view of the first active material layer according to an embodiment of the present disclosure is shown.

[0033] Figure 8 An enlarged view of the second active material layer according to an embodiment of the present disclosure is provided.

[0034] Figure 9 To show an enlarged view of the second active material layer according to another embodiment of the present disclosure;

[0035] Figure 10 To illustrate a SEM image of a first particle according to an embodiment of the present disclosure;

[0036] Figure 11 To illustrate a SEM image of a second particle according to an embodiment of the present disclosure;

[0037] Figure 12 To illustrate a SEM image of a third particle in the form of a single particle according to an embodiment of the present disclosure; and

[0038] Figure 13 To illustrate a SEM image of a third particle in the form of a secondary particle according to an embodiment of another disclosure. Detailed Implementation

[0039] To fully understand the layout and effects of this disclosure, preferred embodiments of the disclosure will be described with reference to the accompanying drawings. However, it should be noted that this disclosure is not limited to the embodiments described below and can be implemented in various forms and modified differently. The embodiments provided herein are intended to make this disclosure thorough and complete, and to fully convey the scope of this disclosure to those skilled in the art.

[0040] In this document, when a component is referred to as being on another component, the component may be directly on the other component, or there may be an intermediate third component. Additionally, in the accompanying drawings, the dimensions (e.g., thickness) of the components are enlarged for the purpose of effectively describing the technical content. The same reference numerals refer to the same elements throughout the document.

[0041] Unless otherwise indicated herein, singular expressions may include plural expressions. Additionally, unless otherwise indicated, the phrase “A or B” may indicate “A but not B,” “B but not A,” or “A and B.” The terms “comprises” and / or “comprising” as used herein do not exclude the presence or addition of one or more other components.

[0042] As used herein, the term "combination thereof" may refer to a mixture, stack, complex, copolymer, alloy, blend, or reaction product of the components.

[0043] Unless otherwise specified herein, particle size may be the average diameter. Furthermore, particle size is defined as the average diameter (D). 50 The average diameter (D) indicates the diameter of particles whose cumulative volume is approximately 50 vol% in the particle size distribution. 50 The average diameter (D) can be measured by methods widely known to those skilled in the art, for example, by means of a particle size analyzer, transmission electron microscopy (TEM) images, or scanning electron microscopy (SEM) images. Optionally, the average diameter (D) 50 This can be measured using a dynamic light scattering measurement device, where data analysis is performed to count the number of particles for each particle size range, and then the average diameter (D) can be calculated. 50 ) value. Optionally, the average diameter (D 50The particle size distribution can be measured using laser diffraction. In laser diffraction measurements, the target particles are dispersed in a dispersion medium and introduced into a commercially available laser diffraction particle size measurement device (e.g., the MT 3000 available from Microtrac, Ltd.). Ultrasonic radiation at approximately 28 kHz is applied at a power of 60 W. The average diameter (D) based on 50% of the particle size distribution in the measurement device can then be calculated. 50 ).

[0044] Figure 1 A simplified conceptual diagram illustrating a rechargeable lithium battery according to an embodiment of the present disclosure is provided. (Reference) Figure 1 A rechargeable lithium battery may include a positive electrode 10, a negative electrode 20, a separator 30, and an electrolyte ELL.

[0045] The positive electrode 10 and the negative electrode 20 can be separated from each other by a diaphragm 30. That is, 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.

[0046] The electrolyte ELL can be used as a medium for transporting lithium ions between the positive electrode 10 and the negative electrode 20. In the electrolyte ELL, lithium ions can move towards the positive electrode 10 or the negative electrode 20 through the membrane 30.

[0047] positive electrode

[0048] The positive electrode 10 for a rechargeable lithium battery may include a positive electrode current collector COL1 and a positive electrode active material layer AML1 on the positive electrode current collector. The positive electrode active material layer AML1 may include a positive electrode active material and may further include a binder and / or a conductive material (e.g., an electrically conductive material). The positive electrode 10 may further include components that can be used as a sacrificial positive electrode.

[0049] Aluminum foil can be used as the positive electrode current collector COL1, but the embodiments of this disclosure are not limited thereto.

[0050] Please refer to later Figure 6 The positive electrode 10 is described in detail.

[0051] negative electrode

[0052] The negative electrode 20 for a rechargeable lithium battery may include a negative electrode current collector COL2 and a negative electrode active material layer AML2 on the negative electrode current collector COL2. The negative electrode active material layer AML2 may include a negative electrode active material and may further include a binder and / or a conductive material (e.g., an electrically conductive material).

[0053] The negative electrode active material layer AML2 may include about 90 wt% to about 99.5 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.

[0054] The binder can be used to attach the negative electrode active material particles to each other, and also to attach the negative electrode active material to the negative electrode current collector COL2. The binder may include non-aqueous binders, aqueous binders, dry binders, or combinations thereof. Non-aqueous binders may include polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene-propylene copolymer, polystyrene, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, polyamide-imide, polyimide, or combinations thereof. Aqueous binders may be selected from 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.

[0055] When an aqueous binder is used as a binder in the negative electrode active material layer AML2, it may further 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 Na, K, or Li.

[0056] Dry adhesives can be fibrous polymer materials. For example, dry adhesives can be polytetrafluoroethylene, polyvinylidene fluoride, polyvinylidene fluoride-hexafluoropropylene copolymer, polyethylene oxide, or combinations thereof.

[0057] Conductive materials can be used to impart conductivity to electrodes. Any material that does not cause 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 of conductive materials may include carbon-based materials such as natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials including copper, nickel, aluminum, silver, etc., in the form of metal powders or metal fibers; conductive polymers (such as polyphenylene derivatives); or mixtures thereof.

[0058] The negative electrode current collector COL2 may include copper foil, nickel foil, stainless steel foil, titanium foil, nickel foam, copper foam, a polymer substrate coated with a conductive metal, or a combination thereof.

[0059] Negative electrode active material

[0060] The negative electrode active material in the negative electrode active material layer AML2 may include a material that reversibly intercalates / deintercalates lithium ions, lithium metal, a lithium metal alloy, a material capable of doping / de-doping lithium, or a transition metal oxide.

[0061] The material that reversibly intercalates / deintercalates lithium ions may include a carbon-based negative electrode active material, such as crystalline carbon, amorphous carbon, or a combination thereof. Examples of crystalline carbon are graphite, such as irregular, plate-like, flaky, spherical, or fibrous natural graphite or artificial graphite, and examples of amorphous carbon are soft carbon (low-temperature fired carbon), hard carbon, mesophase pitch carbide, fired coke, etc.

[0062] The lithium metal alloy includes an alloy of lithium and a metal selected from Na, K, Rb, Cs, Fr, Be, Mg, Ca, Sr, Si, Sb, Pb, In, Zn, Ba, Ra, Ge, Al, and Sn.

[0063] The material capable of doping / de-doping lithium may be a Si-based negative electrode active material or a Sn-based negative electrode active material. The Si-based negative electrode active material may include silicon, a silicon-carbon composite, SiO x (0 < x ≤ 2), a Si-Q alloy, or a combination thereof. In the Si-Q alloy, Q is selected from 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, or a combination thereof. The Sn-based negative electrode active material may include Sn, SnO x (0 < x ≤ 2) (for example, SnO2), a Sn-based alloy, or a combination thereof.

[0064] The silicon-carbon composite may be a composite of silicon and amorphous carbon. According to an embodiment, the silicon-carbon composite may 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 may include secondary particles (cores) (primary silicon particles assembled in each secondary particle) and an amorphous carbon coating (shell) on the surface of the secondary particles. Amorphous carbon may also be between the primary silicon particles. And the primary silicon particles may be coated with amorphous carbon. The secondary particles may be dispersed in an amorphous carbon matrix.

[0065] The silicon-carbon composite may further include crystalline carbon. The silicon-carbon composite may include: for example, a core including crystalline carbon and silicon particles and an amorphous carbon coating on the surface of the core.

[0066] The Si-based negative electrode active material or the Sn-based negative electrode active material may be used in combination with the carbon-based negative electrode active material.

[0067] diaphragm

[0068] Depending on the type of rechargeable lithium battery, the separator 30 may be present between the positive electrode 10 and the negative electrode 20. The separator 30 may include a polyethylene separator, a polypropylene separator, a polyvinylidene fluoride separator, or a multilayer film of two or more layers thereof, such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polypropylene three-layer separator, a polypropylene / polypropylene / polypropylene three-layer separator, etc.

[0069] The diaphragm 30 may include a porous substrate and a coating on one or both surfaces of the porous substrate, the coating comprising an organic material, an inorganic material, or a combination of organic and inorganic materials.

[0070] The porous substrate may be a polymer film formed from copolymers or mixtures selected from any one or two or more of the following: polyolefins (such as polyethylene and polypropylene), polyesters (such as polyethylene terephthalate and polybutylene terephthalate), polyacetal, polyamide, polyimide, polycarbonate, polyetherketone, polyaryletherketone, polyetherimide, polyamideimide, polybenzimidazole, polyethersulfone, polyphenylene ether, cyclic olefin copolymers, polyphenylene sulfide, polyethylene naphthalate, glass fiber, and polytetrafluoroethylene (e.g., ).

[0071] Organic materials may include polymers such as polyvinylidene fluoride or (meth)acrylic acid polymers.

[0072] Inorganic materials may include inorganic particles selected from Al2O3, SiO2, TiO2, SnO2, CeO2, MgO, NiO, CaO, GaO, ZnO, ZrO2, Y2O3, SrTiO3, BaTiO3, Mg(OH)2, boehmite, and combinations thereof. However, this disclosure is not limited to these examples.

[0073] Organic and inorganic materials can be mixed in a coating, or coatings containing organic materials and coatings containing inorganic materials can be stacked.

[0074] electrolyte

[0075] Electrolytes (ELLs) used in rechargeable lithium batteries may include non-aqueous organic solvents and lithium salts.

[0076] Non-aqueous organic solvents can be used as media for transporting ions that participate in the electrochemical reactions of a battery. Non-aqueous organic solvents may include carbonate solvents, ester solvents, ether solvents, ketone solvents, alcohol solvents, aprotic solvents, or combinations thereof.

[0077] Carbonate solvents may include one or more of the following: dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), methyl propyl carbonate (MPC), ethyl propyl carbonate (EPC), methyl ethyl carbonate (EMC), ethylene carbonate (EC), propylene carbonate (PC), and butyl carbonate (BC).

[0078] Ester solvents may include methyl acetate, ethyl acetate, n-propyl acetate, dimethyl acetate, methyl propionate, ethyl propionate, decanoic acid lactone, mevalonate lactone, caprolactone, etc.

[0079] Ether solvents may include dibutyl ether, tetraethylene glycol dimethyl ether, diethylene glycol dimethyl ether, ethylene glycol dimethyl ether, 2-methyltetrahydrofuran, 2,5-dimethyltetrahydrofuran, tetrahydrofuran, etc. Additionally, ketone solvents may include cyclohexanone, etc. Alcohol solvents may include ethanol, isopropanol, etc., and aprotic solvents may include nitrile solvents (such as R-CN, where R is a C2-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.

[0080] Non-aqueous organic solvents can be used alone or in combination of two or more.

[0081] In addition, when using carbonate solvents, cyclic carbonates and chain carbonates can be mixed and used. Cyclic carbonates and chain carbonates can be mixed in a volume ratio of about 1:1 to about 1:9.

[0082] Lithium salts dissolved in non-aqueous organic solvents supply lithium ions to batteries, ensuring basic operation of rechargeable lithium batteries and improving 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 trifluoromethanesulfonate, lithium tetrafluoroethanesulfonate, lithium difluorobis(oxalate)phosphate (LiDFBOP), and lithium bis(oxalate)borate (LiBOB).

[0083] Rechargeable lithium batteries

[0084] Rechargeable lithium batteries can be classified according to their shape as cylindrical, prismatic, pouch, or coin-shaped batteries, etc. Figures 2-5 A schematic diagram illustrating a rechargeable lithium battery according to an embodiment. Figure 2 A cylindrical battery is shown. Figure 3 A prismatic battery is shown, and Figure 4 and Figure 5 A pouch-type battery is shown. (Reference) Figures 2-5 The rechargeable lithium battery 100 may include an electrode assembly 40 (including a separator 30 between a positive electrode 10 and a negative electrode 20) and a housing 50 (in which the electrode assembly 40 is housed). 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 a sealed housing 50. Figure 3 In this context, the rechargeable lithium battery 100 may include a positive electrode lead connector 11, a positive electrode terminal 12, a negative electrode lead connector 21, and a negative electrode terminal 22. For example... Figure 4 and Figure 5 As shown, the rechargeable lithium battery 100 may include electrode terminals 70, which may be, for example, a positive electrode terminal 71 and a negative electrode terminal 72, serving as an electrical path for guiding the current generated in the electrode assembly 40 to the outside of the battery.

[0085] As a non-limiting example, the rechargeable lithium battery according to the embodiments can be used in automobiles, mobile phones and / or various types of electronic devices.

[0086] Figure 6 A cross-sectional view of the positive electrode for a rechargeable lithium battery according to an embodiment of the present disclosure is shown. (Reference) Figure 6 As described above, the positive electrode 10 may include a positive electrode current collector COL1 and a positive electrode active material layer AML1. The positive electrode active material layer AML1 may be provided on the positive electrode current collector COL1.

[0087] The positive electrode active material layer AML1 may include positive electrode active material particles PTC1, PTC2, and PTC3, which will be described below. Relative to 100 wt% of the positive electrode active material layer AML1, the positive electrode active material layer AML1 may contain approximately 90 wt% to approximately 99 wt% of positive electrode active material particles PTC1, PTC2, and PTC3 (first particle PTC1, second particle PTC, and third particle PTC3).

[0088] The positive electrode active material layer AML1 may include binders BND1 and BND2, as described below, and conductive materials CDM1 and CDM2. Relative to 100 wt% of the positive electrode active material layer AML1, the positive electrode active material layer AML1 may contain approximately 1.0 wt% to approximately 10 wt% of each of binders BND1 and BND2, and conductive materials CDM1 and CDM2.

[0089] The positive electrode active material layer AML1 may include a first active material layer ATL1 and a second active material layer ATL2. The positive electrode active material layer AML1, providing the first active material layer ATL1 and the second active material layer ATL2, may contain a large number of nano-sized olivine compounds and increase the bonding force with respect to the positive electrode current collector, thereby facilitating the fabrication of the electrode plate and reducing the resistance of the electrode plate. Furthermore, including the positive electrode active material layer AML1 can provide a rechargeable lithium battery with excellent performance.

[0090] The first active material layer ATL1 may have a thickness T1. In an embodiment, T1 may increase with the increase of the weight of the first particle PTC1 (hereinafter referred to as "the first particle") and / or the second particle PTC2 (hereinafter referred to as "the second particle") included in the first active material layer ATL1. The second active material layer ATL2 may have a thickness T2. In an embodiment, T2 may increase with the increase of the weight of the third particle PTC3 (hereinafter referred to as "the third particle") included in the second active material layer ATL2.

[0091] The thickness ratio T1:T2 of the first active material layer ATL1 and the second active material layer ATL2 can be approximately 3:7 to approximately 7:3. For example, the thickness ratio T1:T2 of the first active material layer ATL1 and the second active material layer ATL2 can be approximately 5:5. When the thickness ratio T1:T2 of the first active material layer ATL1 and the second active material layer ATL2 meets these ranges, the positive electrode active material layer AML1 has improved adhesion to the positive electrode current collector COL1, thus facilitating the fabrication of the electrode plate and reducing the resistance of the electrode plate. In addition, when the first active material layer ATL1 and the second active material layer ATL2 are included, a rechargeable lithium battery with excellent performance can be provided.

[0092] Figure 7 An enlarged view of the first active material layer ATL1 according to an embodiment of the present disclosure is shown. Figure 8 An enlarged view of the second active material layer ATL2 according to an embodiment of the present disclosure is shown. Figure 9 An enlarged view is shown for illustrating the second active material layer ATL2 according to another embodiment of the present disclosure.

[0093] refer to Figure 7 The first active material layer ATL1 may include a first particle PTC1, a second particle PTC2, and a first functional additive FAD1. The first functional additive FAD1 may include a first binder BND1 and a first conductive material CDM1.

[0094] The first active material layer ATL1 includes the second particle PTC2, thus reducing the content of the first functional additive FAD1. For example, the weight proportion of the first functional additive FAD1 in the first positive electrode active material layer ATL1 can be about 0.024 to about 0.06. The weight proportion of the first functional additive FAD1 in the first active material layer ATL1 can be defined as the weight of the first functional additive FAD1 relative to the total weight of the first active material layer ATL1.

[0095] The amount of the first binder BND1 relative to 100 parts by weight of the first active material layer ATL1 may be about 1.2 parts by weight to about 3 parts by weight. The amount of the first conductive material CDM1 relative to 100 parts by weight of the first active material layer ATL1 may be about 1.2 parts by weight to about 3 parts by weight.

[0096] refer to Figure 8 and Figure 9 The second active material layer ATL2 may include a third particle PTC3 and a second functional additive FAD2. The second functional additive FAD2 may include a second binder BND2 and a second conductive material CDM2. The weight proportion of the second functional additive FAD2 in the second active material layer ATL2 may be equal to or greater than the weight proportion of the first functional additive FAD1 in the first active material layer ATL1.

[0097] The weight ratio of the second functional additive FAD2 to the first functional additive FAD1 (weight ratio of the second functional additive / weight ratio of the first functional additive) can be approximately 1 to approximately 4.5. For example, the weight ratio of the second functional additive FAD2 to the first functional additive FAD1 can be approximately 1.5 to approximately 4.5 or approximately 1.66 to approximately 4.32. When the weight ratio of the second functional additive FAD2 to the first functional additive FAD1 is within these ranges, the positive electrode active material layer AML1 has improved adhesion to the positive electrode current collector COL1, thus facilitating the fabrication of the electrode plate and reducing the resistance of the electrode plate. Furthermore, rechargeable lithium batteries with superior performance can be provided with a positive electrode active material layer AML1.

[0098] The weight proportion of the second functional additive FAD2 in the second positive electrode active material layer ATL2 can be about 0.024 to about 0.1. The weight proportion of the second functional additive FAD2 in the second active material layer ATL2 can be defined as the weight of the second functional additive FAD2 relative to the total weight of the second active material layer.

[0099] The amount of the second adhesive BND2 may be equal to or greater than the amount of the first adhesive BND1. For example, relative to 100 parts by weight of the second active material layer ATL2, the amount of the second adhesive BND2 may be about 1.2 parts by weight to about 5 parts by weight.

[0100] The amount of the second conductive material CDM2 can be equal to or greater than the amount of the first conductive material CDM1. For example, relative to 100 parts by weight of the second active material layer ATL2, the amount of the second conductive material CDM2 can be about 1.2 parts by weight to about 5 parts by weight.

[0101] Binders BND1 and BND2 are used to bond the positive electrode active material particles PTC1, PTC2, and PTC3 to each other, and also to bond the positive electrode active material particles PTC1 and PTC2 to the positive electrode current collector COL1. Examples of binders BND1 and BND2 include polyvinyl alcohol, carboxymethyl cellulose, hydroxypropyl cellulose, diacetyl cellulose, polyvinyl chloride, carboxylated polyvinyl chloride, polyvinyl fluoride, ethylene oxide-containing polymers, polyvinylpyrrolidone, polyurethane, polytetrafluoroethylene, polyvinylidene fluoride, polyethylene, polypropylene, styrene-butadiene rubber, (meth)acrylated styrene-butadiene rubber, epoxy resin, (meth)acrylate resin, polyester resin, and nylon. However, embodiments disclosed herein are not limited to these examples.

[0102] Conductive materials CDM1 and CDM2 can be used to impart conductivity to electrodes. Any material that does not cause chemical changes (e.g., does not cause undesirable chemical changes in rechargeable lithium batteries) and conducts electrons can be used as a conductive material in the battery. Examples of conductive materials CDM1 and CDM2 include: carbon-based materials such as natural graphite, synthetic graphite, carbon black, acetylene black, Ketjen black, carbon fibers, carbon nanofibers, and carbon nanotubes; metallic materials, including copper, nickel, aluminum, silver, etc., in the form of metal powders or metal fibers; conductive polymers, such as polyphenylene derivatives; or mixtures thereof.

[0103] The following sections will describe in detail the first particle PTC1, the second particle PTC2, and the third particle PTC3.

[0104] First particle

[0105] refer to Figure 7The first PTC1 particle can be in the form of a single particle. In this document, a single particle can refer to a single type of particle without grain boundaries within it. A single particle can refer to a single particle that exists morphologically as an independent phase (where the particles do not aggregate), a particle with a monolithic structure, a particle with an integral structure, or a non-agglomerated particle. For example, a single particle can be a single crystal. Alternatively, a single particle can be a particle containing several crystals. A single particle can be in a separated form. Alternatively, a single particle can be in the form of about 2 to about 100 single particles attached to each other. That is, the first PTC1 particle can be provided in various sizes. For example, the first PTC1 particle can have an average diameter of about 1 μm. The first PTC1 particle can have a minimum diameter of about 20 nm to about 500 nm or about 200 nm to about 300 nm. The minimum diameter indicates the diameter measured by randomly selecting about 30 primary particles (hereinafter, the first primary particles) from an electron micrograph of the positive electrode active material. The first PTC1 particle may have an average diameter of approximately 100 nm to approximately 2 μm or approximately 500 nm to approximately 2 μm (D 50 For example, the first particle, PTC1, may have an average diameter of about 1 μm. In an embodiment, the average diameter can be measured using a particle size analyzer. The average diameter indicates the particle size when the cumulative volume in the particle size distribution is about 50 vol%.

[0106] The first PTC1 particle may include a compound structured with olivine of Formula 1:

[0107] Li a1 Mn x1 Fe y1 B1 z1 PO 4-b1

[0108] In Equation 1, the following conditions must be met: 0.8 ≤ a1 ≤ 1.2, 0.4 ≤ x1 ≤ 0.8, 0 ≤ y1 ≤ 0.6 (e.g., 0.2 ≤ y1 ≤ 0.6), 0 ≤ z1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, and x1 + y1 + z1 = 1. For example, z1 can be 0.002. B1 can be the dopant doped into the first PTC1 particle. B1 can include at least one of Al, Ti, V, and Mg. B1 can make the size of the first primary particle uniform. Therefore, the rechargeable lithium battery can have improved charge / discharge efficiency, low-temperature characteristics, and lifespan characteristics.

[0109] In one embodiment, the first PTC1 particle may include a carbon-containing coating on its surface. The coating may completely cover the surface of the first PTC1 particle or may partially cover the surface of the first PTC1 particle. The coating may include elemental carbon and / or carbon-containing compounds. By providing the coating, the first PTC1 particle may have improved structural stability and electrical conductivity.

[0110] The coating may further include at least one metal-containing compound selected from titanium-containing compounds, magnesium-containing compounds, and vanadium-containing compounds. In certain embodiments, the coating may include metal-containing compounds (such as titanium-containing compounds, magnesium-containing compounds, and vanadium-containing compounds), and the metal-containing compounds are metal oxides, metal hydroxides, metal carbonates, their complexes, or mixtures thereof. The metal-containing compounds may further include other metal elements or non-metal elements. For example, the metal-containing compounds may include lithium.

[0111] The first PTC particle PTC1 may further include carbon (i.e., carbon element) derived from the above coating. The amount of carbon element in the first PTC particle PTC1 may be about 0.5 wt% to about 10 wt%, about 1 wt% to about 3 wt%, or about 1.5 wt% to about 2.5 wt%.

[0112] The first PTC particle PTC1 may have a large Brunauer-Emmett-Teller (BET) specific surface area. For example, the first PTC particle PTC1 may have a BET specific surface area of about 10 m 2 / g to about 30 m 2 / g. As another example, the first PTC particle PTC1 may have a BET specific surface area of about 20 m 2 / g.

[0113] Second particle

[0114] Reference Figure 7 , the second PTC particle PTC2 may include a layered lithium compound represented by Formula 2:

[0115] Li a2 Ni x2 Mn z2 Al c2 Y d2 O 2-b2

[0116] In Formula 2, 0.8 < a2 ≤ 1.2, 0.7 ≤ x2 ≤ 0.8, 0.2 ≤ z2 ≤ 0.3, 0 ≤ c2 ≤ 0.02, 0 ≤ d2 ≤ 0.003, 0 ≤ b2 ≤ 0.05, and x2 + z2 + c2 + d2 = 1 may be satisfied. For example, c2 may be 0.004 and d2 may be 0.001. Y may be a dopant doped in the second PTC particle PTC2. Y may include at least one of Ti, Mg, Zr, Mo, and Nb.

[0117] The second PTC particle PTC2 may have an amount of cobalt less than about 100 ppm. That is, the second PTC particle PTC2 according to an embodiment of the present disclosure may be substantially cobalt-free. The second PTC particle PTC2 according to an embodiment of the present disclosure can thus provide a cobalt-free positive electrode active material. In an embodiment, the second PTC particle PTC2 may have an amount of cobalt lower than the amount of aluminum.

[0118] The second PTC2 particle may be provided as part of a cobalt-free layered positive electrode active material, a cobalt-free nickel-based positive electrode active material, or a cobalt-free nickel-manganese-based positive electrode active material. As used herein, cobalt-free means containing no cobalt, using no cobalt, or containing only a very small amount of cobalt.

[0119] In an embodiment, the second PTC2 particle may include a carbon-containing coating on its surface. The coating may completely cover the surface of the second PTC2 particle or may partially cover it. The coating may include a boron-containing compound, a titanium-containing compound, an aluminum-containing compound, or a combination thereof. The metal-containing compound in the coating may be, for example, a metal oxide, a metal hydroxide, a metal carbonate, a complex thereof, or a mixture thereof. The compound forming the coating may be crystalline or amorphous. The metal-containing compound may further include other metallic or non-metallic elements. For example, the coating may further include lithium, manganese, and / or nickel. Surface modification using the coating can stabilize the structure and improve the thermal stability of the positive electrode active material.

[0120] The second PTC2 particle can be larger than the first PTC1 particle. When a first active material layer ATL1, comprising the first PTC1 particle and the second PTC2 particle, is introduced, the positive electrode active material layer AML1 can contain a large number of nano-sized olivine compounds and have greater binding force relative to the positive electrode current collector. This, in turn, can facilitate the fabrication of the electrode plate and reduce its resistance. Furthermore, the electrode plate can provide a rechargeable lithium battery with superior performance.

[0121] The second PTC2 particle can exist as a single particle. As discussed above, a single particle can refer to a single type of particle without grain boundaries within it. A single particle can refer to a single particle that exists morphologically as an independent phase (where the particles do not aggregate with each other), a particle with a monolithic structure, a particle with a unified structure, or a non-agglomerated particle. For example, a single particle can be a single crystal or several crystals. In this paper, the second PTC2 particle existing as a single particle can be referred to as the second single particle SP2. Furthermore, the second single particle SP2 can be referred to as a small particle.

[0122] As discussed above, the average particle size (average diameter) (D 50 This indicates the particle size when the cumulative volume in the particle size distribution is approximately 50 vol%. The average diameter (D) of the second particle, PTC2, is... 50 The value can be measured using a particle size analyzer. The second single particle SP2 can have an average diameter (D) of about 3 μm to about 7 μm or about 3 μm to about 4 μm. 50 The second single particle SP2 can have a larger average diameter (D) than the first single particle mentioned above. 50 ).

[0123] The second particle PTC2 may be in a polycrystalline form and may include secondary particles in which at least two second primary particles (MMPs) are aggregated. That is, a second particle PTC2 may include multiple second primary particles (MMPs) aggregated together. The second particle PTC2 composed of multiple second primary particles (MMPs) may be spherical or ellipsoidal in shape. In this document, the second particle PTC2 in the form of a secondary particle may be referred to as a second secondary particle PC2. In addition, in this document, the second secondary particle PC2 may be referred to as a large particle.

[0124] The secondary particles PC2 can have an average diameter (D) of approximately 12 μm to approximately 18 μm. 50 The second-stage particle PC2 can have a larger average diameter (D) than the first particle PTC1. 50 ).

[0125] In this paper, the second PTC2 particle may be presented as a second single particle SP2 or a second secondary particle PC2. Alternatively, the second PTC2 particle may be provided as part of a positive electrode active material comprising both the second single particle SP2 and the second secondary particle PC2.

[0126] In this paper, both the second single particle SP2 and the second secondary particle PC2 can indicate the second particle PTC2. Alternatively, the second particle PTC2 can indicate either the second single particle SP2 or the second secondary particle PC2. The presence of the second particle PTC2 in the positive electrode active material as both a single particle and a secondary particle, or as both a large particle and a small particle, is referred to as bimodal.

[0127] The second PTC2 particle may have a small BET specific surface area. In an embodiment, the second PTC2 particle may have a smaller BET specific surface area than the first PTC1 particle. For example, the second PTC2 particle may have a BET specific surface area of ​​approximately 0.8 μm. 2 / g~approximately 1.5m 2 / g BET specific surface area. As another example, the second PTC2 particle may have approximately 1m². 2 / g BET specific surface area. Therefore, in embodiments of this disclosure, a small amount of binder can be used in combination with nano-sized olivine compounds.

[0128] Third particle

[0129] refer to Figure 8The third PTC3 particle can be in the form of a single particle. In this document, the third particle can be a single particle according to the definition of a single particle provided above. That is, the third PTC3 particle can be provided in various sizes. For example, the third PTC3 particle can have an average diameter of about 1 μm. The third PTC3 particle can have a minimum diameter of about 20 nm to about 500 nm or about 200 nm to about 300 nm. The minimum diameter can be indicated by measuring the diameter by randomly selecting about 30 primary particles (hereinafter, the third primary particles) from an electron micrograph of the positive electrode active material.

[0130] The third PTC3 particle can have an average diameter of approximately 100 nm to approximately 2 μm or approximately 500 nm to approximately 2 μm (D 50 For example, the third PTC3 particle can have an average diameter of about 1 μm.

[0131] The third PTC3 particle may include olivine-structured compounds of Formula 3:

[0132] Li a3 Mn x3 Fe y3 B3 z3 PO 4-b3

[0133] In Equation 3, the following conditions must be met: 0.8 ≤ a3 ≤ 1.2, 0.4 ≤ x3 ≤ 0.8, 0 ≤ y3 ≤ 0.6 (e.g., 0.2 ≤ y3 ≤ 0.6), 0 ≤ z3 ≤ 0.05, 0 ≤ b3 ≤ 0.05, and x3 + y3 + z3 = 1. For example, z3 can be 0.002. B3 can be a dopant doped in the third primary particle PTC3. B3 can include at least one of Al, Ti, V, and Mg. B3 can make the size of the third primary particle uniform. Therefore, when a third primary particle is provided, the rechargeable lithium battery can have improved charge / discharge efficiency, low-temperature characteristics, and lifespan characteristics.

[0134] In one embodiment, the third PTC3 particle may include a carbon-containing coating on its surface. The coating may completely cover the surface of the third PTC3 particle or may partially cover the surface of the third PTC3 particle. The coating may include elemental carbon and / or carbon-containing compounds. When a coating is provided, the third PTC3 particle may have improved structural stability and electrical conductivity.

[0135] The coating may further include at least one metal-containing compound selected from titanium-containing compounds, magnesium-containing compounds, and vanadium-containing compounds. The titanium-containing, magnesium-containing, and vanadium-containing compounds may be, for example, metal oxides, metal hydroxides, metal carbonates, complexes thereof, or mixtures thereof. The metal-containing compound may further include other metallic or non-metallic elements. For example, the metal-containing compound may further include lithium.

[0136] The third PTC3 particle may further include carbon derived from the coating described above. The amount of carbon in the third PTC3 particle may be from about 0.5 wt% to about 10 wt%, from about 1 wt% to about 3 wt%, or from about 1.5 wt% to about 2.5 wt%.

[0137] When the third particle PTC3 is a single particle, the weight proportion of the second functional additive FAD2 in the second active material layer ATL2 can be equal to or greater than the weight proportion of the first functional additive FAD1 in the first active material layer ATL1. Optionally, the weight proportion of the second functional additive FAD2 in the second active material layer ATL2 can be greater than the weight proportion of the first functional additive FAD1 in the first active material layer ATL1. For example, the ratio of the weight proportion of the second functional additive FAD2 to the weight proportion of the first functional additive FAD1 can be about 1.5 to about 4.5.

[0138] When the third particle PTC3 is a single particle, the amount of the second functional additive FAD2 relative to 100 parts by weight of the second active material layer ATL2 can be about 4 parts by weight to about 10 parts by weight or about 6 parts by weight. For example, the amount of the second binder BND2 relative to 100 parts by weight of the second active material layer can be about 2 parts by weight to about 5 parts by weight or about 3 parts by weight. The amount of the second conductive material CDM2 relative to 100 parts by weight of the second active material layer can be about 2 parts by weight to about 5 parts by weight or about 3 parts by weight. When the amount of the second functional additive FAD2 meets these ranges, the second active material layer ATL2 can provide the desired bonding strength.

[0139] refer to Figure 9 The third PTC3 particle is polycrystalline and may include secondary particles from which at least two primary particles are aggregated. That is, a third PTC3 particle may include multiple fourth PTC4 particles aggregated together. Each of the fourth PTC4 particles may be a primary particle. The third PTC3 particle may be spherical or ellipsoidal in shape.

[0140] In an embodiment, the third PTC3 may further include a grain boundary coating on the surface of each of the fourth PTC4 particles. The grain boundary coating may be present within the third PTC3 particle. The grain boundary coating may be formed along the interfaces between the fourth PTC4 particles within the third PTC3 particle. That is, the grain boundary coating may indicate a layer of material formed at the grain boundaries within the third PTC3 particle. The grain boundary coating may include elemental carbon and / or carbon-containing compounds. The grain boundary coating may further include at least one of titanium-containing compounds, magnesium-containing compounds, and vanadium-containing compounds.

[0141] The interior of the third PTC3 can refer to the entire interior portion of the third PTC3 excluding the surface of the third PTC3. For example, the interior of the third PTC3 can refer to the entire interior from a depth of about 10 nm relative to the surface of the third PTC3, or a region of the interior from about 10 nm to about 2 μm relative to the surface of the third PTC3.

[0142] Because the third PTC3 particle includes a grain boundary coating, it can therefore exhibit greater structural stability and a uniform coating formed on its surface. Furthermore, due to the grain boundary coating, the third PTC3 particle can also possess further improved electrical conductivity.

[0143] The third PTC3 particle may further include carbon derived from the above-mentioned coating and / or grain boundary coating. The amount of carbon in the third PTC3 particle may be from about 0.5 wt% to about 10 wt%, from about 1 wt% to about 3 wt%, or from about 1.5 wt% to about 2.5 wt%.

[0144] When the third PTC3 particle is a secondary particle, the third PTC3 particle may have an average diameter (D) of about 2 μm to about 15 μm, about 3 μm to about 10 μm, or about 3 μm to about 7 μm. 50 For example, the third PTC3 particle may have an average diameter of approximately 5 μm. The third PTC3 particle may have a larger average diameter than the fourth PTC4 particle (described later).

[0145] The fourth PTC4 particle may have an average diameter of about 200 nm or less. For example, the fourth PTC4 particle may have an average diameter of about 10 nm to about 200 nm, about 20 nm to about 200 nm, about 50 nm to about 200 nm, or about 100 nm to about 200 nm. For example, the average diameter may indicate the diameter measured by randomly selecting about 30 fourth PTC4 particles from an electron micrograph of the positive electrode active material. The fourth PTC4 particle may also have a uniform particle size. And the fourth PTC4 particle may have a smaller diameter than the third primary particle. For example, the average diameter of the fourth PTC4 particle may be about 100 nm smaller than the average diameter of the third primary particle.

[0146] When the fourth particle and its average diameter meet the above range, and the size of the fourth particle is uniform, the rechargeable lithium battery containing the fourth particle can have improved charge / discharge capacity and low-temperature capacity.

[0147] The third PTC3 particle can be spherical in shape, containing agglomerated fourth PTC4 particles of nanoscale size. The fourth PTC4 particle can be tightly aggregated within the third PTC3 particle, thus exhibiting the following properties. The third PTC3 particle can be spherical or ellipsoidal in shape. The third PTC3 particle can have an average diameter (D) of approximately 2 μm to approximately 15 μm. 50 The third PTC3 particle can have a porosity of approximately 20% to approximately 40%. The span value of the third PTC3 particle, analyzed by a particle size analyzer, can be approximately 0.3 to approximately 0.75. The span value is determined by (D... 90 -D 10 ) / D 50 Indicated. As used in this article, the term "D" 10 "D" refers to the average diameter of particles when the cumulative percentage reaches 10% by volume in the particle size distribution, and is used as a term "D" in this document. 90 "Porosity (n) refers to the average diameter of particles when the cumulative percentage reaches 90% of the particle size distribution. Here, porosity (n) can be defined as pore volume (V)." p Divide by the total volume of the particles (V) t ),or

[0148] When the third particle PTC3 is a secondary particle, the weight ratio of the second functional additive FAD2 in the second active material layer ATL2 can be equal to or greater than the weight ratio of the first functional additive FAD1 in the first active material layer ATL1. For example, the weight ratio of the second functional additive FAD2 to the first functional additive FAD1 can be about 1 to about 4.5.

[0149] When the third particle PTC3 is a secondary particle, the amount of the second functional additive FAD2 relative to 100 parts by weight of the second active material layer ATL2 can be about 2.4 parts by weight to 6 parts by weight or about 4 parts by weight. For example, the amount of the second binder relative to 100 parts by weight of the second active material layer can be about 1.2 parts by weight to about 3 parts by weight or about 2 parts by weight. The amount of the second conductive material relative to 100 parts by weight of the second active material layer can be about 1.2 parts by weight to about 3 parts by weight or about 2 parts by weight. When the amount of the second functional additive FAD2 meets these ranges, the second active material layer ATL2 can provide the desired bonding strength.

[0150] When in the form of secondary particles, the third PTC3 particles have a larger average diameter than when in the form of single particles. Accordingly, even when the third PTC3 particles as secondary particles contain a smaller amount of the second binder BND2 than when they are single particles, the second active material layer ATL2 can still have the desired bonding strength.

[0151] Return to reference Figure 7According to embodiments of the present disclosure, the first active material layer ATL1 may include both a first particle PTC1 and a second particle PTC2.

[0152] The first PTC1 particle can be a lithium iron phosphate compound with an olivine structure, exhibiting high structural stability and chemical stability. Compared to other positive electrode active materials, this compound demonstrates superior lifetime characteristics due to its stable structure. However, in certain situations, lifetime characteristics can deteriorate at high voltages, limiting the usable operating voltage. Nevertheless, the first PTC1 particle may contain manganese, and compared to conventional lithium iron phosphate compounds, the first PTC1 particle can improve high-voltage characteristics and energy density.

[0153] The first PTC1 particle can cause manganese leaching. Furthermore, the first PTC1 particle can have an extremely small grain size. When the size of the first PTC1 particle is small, the bonding force between the positive electrode current collector and the positive electrode active material can be low, and correspondingly, a large amount of binder can be used to bond the positive electrode active material and the positive electrode current collector.

[0154] The second PTC2 particle may comprise a cobalt-free lithium nickel manganese oxide. The second PTC2 particle may be substantially cobalt-free, but may contain nickel, manganese, or other key components. Positive electrode active materials containing the second PTC2 particle are economical and can achieve high energy density.

[0155] Compared to olivine-structured compounds, lithium nickel manganese oxides exhibit higher powder compaction density under pressure. Therefore, lithium nickel manganese oxides can address the issue of low electrode density observed in olivine-structured phosphate compounds.

[0156] like Figure 7 As shown, by mixing the first PTC1 particles and the second PTC2 particles in an appropriate ratio, the electrode plate can have improved adhesion and require less binder (BND). Additionally, mixing improves capacity, density characteristics, high-temperature stability, and lifetime characteristics. Furthermore, by mixing the second particles, which are bimodal in shape and consist of both large and small particles, the density can be further improved.

[0157] The amount of the first particle PTC1 is approximately 30 wt% to approximately 40 wt% relative to the total amount of the first particle PTC1, the second particle PTC2, and the third particle PTC3 included in the first active material layer ATL1 and the second active material layer ATL2. For example, the amount of the first particle PTC1 is approximately 35 wt% relative to the total amount of the first particle PTC1, the second particle PTC2, and the third particle PTC3 included in the first active material layer ATL1 and the second active material layer ATL2. That is, the ratio of the weight of the first particle PTC1 to the total weight of the first particle PTC1, the second particle PTC2, and the third particle PTC3 (i.e., the weight ratio of the first particle PTC1) can be approximately 0.3 to approximately 0.4.

[0158] The amount of the second particle PTC2 is approximately 15 wt% to approximately 30 wt% relative to the total amount of the first particle PTC1, the second particle PTC2, and the third particle PTC3 included in the first active material layer ATL1 and the second active material layer ATL2. For example, the amount of the second particle PTC2 is approximately 20 wt% to approximately 30 wt% or approximately 30 wt% relative to the total amount of the first particle PTC1, the second particle PTC2, and the third particle PTC3 included in the first active material layer ATL1 and the second active material layer ATL2. That is, the ratio of the weight of the second particle PTC2 to the total weight of the first particle PTC1, the second particle PTC2, and the third particle PTC3 (i.e., the weight ratio of the second particle PTC2) can be approximately 0.15 to approximately 0.3.

[0159] The amount of the second PTC2 particle is about 40 wt% to about 60 wt% relative to the total content of the first PTC1 and the second PTC2 particles included in the first active material layer ATL1. For example, the amount of the second PTC2 particle is about 45 wt% to about 50 wt% relative to the total content of the first PTC1 and the second PTC2 particles included in the first active material layer ATL1.

[0160] Return to reference Figure 8 and Figure 9According to embodiments of the present disclosure, the second active material layer ATL2 may include a third particle PTC3. The content of the third particle PTC3 may be a remainder obtained by subtracting the content of the first particle PTC1 and the content of the second particle PTC2 from the total amount of the first particle PTC1, the second particle PTC2, and the third particle PTC3 included in the first active material layer ATL1 and the second active material layer ATL2. For example, the amount of the third particle PTC3 is about 30 wt% to about 40 wt% relative to the total amount of the first particle PTC1, the second particle PTC2, and the third particle PTC3 included in the first active material layer ATL1 and the second active material layer ATL2. For example, the amount of the third particle PTC3 is about 35 wt% relative to the total amount of the first particle PTC1, the second particle PTC2, and the third particle PTC3 included in the first active material layer ATL1 and the second active material layer ATL2. That is, the ratio of the weight of the third PTC3 particle to the total weight of the first PTC1, the second PTC2, and the third PTC3 particle (i.e., the weight ratio of the third PTC3 particle) can be about 0.3 to about 0.4.

[0161] When the amounts of the first PTC1 and the second PTC2 particles meet the above-mentioned range, the positive electrode active material layer AML1 can have improved adhesion to the positive electrode current collector COL1. Accordingly, a rechargeable lithium battery with reduced resistance can be provided. Furthermore, when the amounts of the first PTC1, the second PTC2, and the third PTC3 particles meet the above-mentioned range, a rechargeable lithium battery with superior performance can be provided.

[0162] The total manganese doping amount can be about 0.40 to about 0.60 (e.g., about 0.46 to about 0.52). For example, the total manganese doping amount can be about 0.49 to about 0.50. The total Mn doping amount (A+B) can be defined as the sum of the manganese (i.e., manganese element) doping amount (A) contained in the first active material layer ATL1 and the manganese doping amount (B) contained in the second active material layer ATL2. The manganese doping amount (A) contained in the first active material layer ATL1 can be defined as the sum of the product of the manganese doping amount (x1 in Formula 1) in the first particle PTC1 and the weight ratio of the first particle PTC1 and the manganese doping amount (z2 in Formula 2) in the second particle PTC2 and the weight ratio of the second particle PTC2. The manganese doping amount (B) included in the second active material layer ATL2 can be defined as the product of the manganese doping amount (x3 in Formula 3) in the third particle PTC3 and the weight ratio of the third particle PTC3.

[0163] When the total manganese doping content meets the above range, the positive electrode active material layer AML1 can have improved adhesion to the positive electrode current collector COL1. Accordingly, a rechargeable lithium battery with reduced resistance can be provided. Additionally, a rechargeable lithium battery with superior performance can be provided.

[0164] The positive electrode for a rechargeable lithium battery according to embodiments of this disclosure has the following effects.

[0165] The first particle PCT1, which has a small average diameter, is attached to the positive electrode current collector COL1 (see...). Figure 1 A relatively large amount of the first binder BND1 may be required, while attaching the second particles PTC2, which have a small BET specific surface area and a large average diameter, to the first active material layer ATL1 may require a relatively small amount of the first binder BND1. The positive electrode active material layer AML1 according to embodiments of the present disclosure includes the first particles PTC1, the second particles PTC2, and the third particles PTC3, and incorporates the first active material layer ATL1 and the second active material layer ATL2. Therefore, the positive electrode active material layer may include a large number of nano-sized olivine compounds and increase the bonding force with respect to the positive electrode current collector, thereby facilitating the fabrication of the electrode plate and reducing the resistance of the electrode plate. Furthermore, a rechargeable lithium battery with excellent capacity and lifetime characteristics, as well as high operating voltage and energy density, can be provided.

[0166] The present disclosure will now be described in more detail through embodiments. However, the embodiments are merely illustrative of the present disclosure, and the scope of the present disclosure is not limited to the following embodiments.

[0167] Preparation Example 1: Preparation of NMX Particles

[0168] Ni 0.75 Mn 0.23 Al 0.02 (OH)₂ and LiOH were mixed in a molar ratio of 1:1.05, and the mixture was subjected to an initial heat treatment at 900°C for 8 hours in an oxygen atmosphere to obtain Li 1.05 Ni 0.75 Mn 0.23 Al 0.02 Composed of O2 and with an average diameter (D) 50 The oxide is approximately 4 μm in size. Alumina was added to the oxide, and the mixture was then subjected to a secondary heat treatment at 825 °C for 8 hours in an oxygen atmosphere to prepare NMX particles. The NMX particles are derived from LiNi... 0.75 Mn 0.23 Al 0.02 O2 represents.

[0169] Preparation Example 2: Preparation of LMFP particles in single-particle form

[0170] Manganese iron phosphate precursor (Mn) 0.6 Fe 0.4 PO4), lithium carbonate, magnesium oxide, and titanium dioxide were added to water in a molar ratio of (Mn+Fe):Li:Mg:Ti of 1:1.03:0.01:0.004. 10 wt% glucose was further added to the mixture. The mixture was wet-milled using a ball mill. The mixture was evaporated to dryness on a heating tray and then dried in a vacuum oven at 85°C for 4 hours. The dried mixture was calcined in a nitrogen atmosphere at 650°C for 10 hours. The calcined product was ground at a rotational speed of 8000 rpm to obtain LMFP particles in single-particle form. The LMFP particles in single-particle form consisted of approximately LiMn... 0.6 Fe 0.4 The formula for PO4.

[0171] Preparation Example 3: Preparation of LMFP particles in the form of secondary particles

[0172] Manganese iron phosphate precursor (Mn) 0.6 Fe 0.4 PO4), lithium carbonate, magnesium oxide, and titanium dioxide were added to water in a molar ratio of (Mn+Fe):Li:Mg:Ti of 1:1.03:0.01:0.004. 10 wt% glucose was further added to the mixture. The slurry mixture was spray-dried and evaporated to dryness at a spray pressure of 0.5 MPa and a temperature of 230 °C. The dried mixture was calcined at 750 °C for 10 hours under a nitrogen atmosphere to obtain LMFP particles in the form of secondary particles. The LMFP particles in the form of secondary particles consisted of approximately LiMn... 0.6 Fe 0.4 The formula for PO4.

[0173] Example 1: Preparation of a positive electrode comprising a first active material layer and a second active material layer

[0174] A first active material slurry was prepared by dispersing NMX particles, LMFP particles in single-particle form, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) in N-methylpyrrolidone at a weight ratio of 0.96:0.02:0.02.

[0175] A second active material slurry was prepared by dispersing LMFP particles in single-particle form, a second binder (polyvinylidene fluoride), and a second conductive material (carbon black) in N-methylpyrrolidone at a weight ratio of 0.94:0.03:0.03.

[0176] A first active material slurry is applied to a 15 μm thick aluminum film serving as the positive electrode current collector and dried to form a first active material layer. A second active material slurry is applied to the first active material layer and dried to form a second active material layer. The first and second active material layers are formed such that NMX particles, LMFP particles in the first active material layer in single-particle form, and LMFP particles in the second active material layer in single-particle form are provided in a weight ratio of 30:35:35. A positive electrode in which the aluminum current collector, the first active material layer, and the second active material layer are stacked in this order is prepared by roll forming. The thickness ratio of the first and second active material layers is 5:5.

[0177] Example 2: Preparation of a positive electrode comprising a first active material layer and a second active material layer

[0178] The positive electrode was prepared in essentially the same manner as in Example 1, except that LMFP particles in the form of secondary particles, a second binder (polyvinylidene fluoride), and a second conductive material (carbon black) were dispersed in N-methylpyrrolidone at a weight ratio of 0.96:0.02:0.02 to prepare a second active material slurry. The thickness ratio of the first active material layer to the second active material layer was 5:5.

[0179] Comparative Example 1: Preparation of a positive electrode including a first active material layer

[0180] A positive electrode comprising a first active material layer containing only NMX particles was prepared.

[0181] NMX particles, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone at a weight ratio of 0.976:0.012:0.012 to prepare a first active material slurry. The first active material slurry was applied to a 15 μm thick aluminum film serving as the positive electrode current collector and dried to form a first active material layer. A positive electrode, in which the aluminum current collector and the first active material layer were stacked in this order, was prepared by roll forming.

[0182] Comparative Example 2: Preparation of a positive electrode including a first active material layer

[0183] A positive electrode comprising a first active material layer containing only LMFP particles was prepared.

[0184] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that LMFP particles in the form of single particles, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.94:0.03:0.03 to prepare a first active material slurry.

[0185] Comparative Example 3: Preparation of a positive electrode including a first active material layer

[0186] A positive electrode consisting only of a first active material layer containing LMFP particles in the form of secondary particles was prepared.

[0187] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that LMFP particles in the form of secondary particles, the first binder (polyvinylidene fluoride), and the first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.976:0.012:0.012 to prepare the first active material slurry.

[0188] Comparative Example 4: Preparation of a positive electrode including a first active material layer

[0189] A positive electrode consisting only of a first active material layer was prepared, which has NMX particles in a weight ratio of 70:30 and LMFP particles in the form of single particles.

[0190] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that NMX particles, LMFP particles in the form of single particles, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.672:0.288:0.02:0.02 to prepare a first active material slurry.

[0191] Comparative Example 5: Preparation of a positive electrode including a first active material layer

[0192] A positive electrode consisting only of a first active material layer was prepared, which has NMX particles in a weight ratio of 60:40 and LMFP particles in the form of single particles.

[0193] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that NMX particles, LMFP particles in the form of single particles, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.576:0.384:0.02:0.02 to prepare a first active material slurry.

[0194] Comparative Example 6: Preparation of a positive electrode including a first active material layer

[0195] A positive electrode consisting only of a first active material layer was prepared, which has NMX particles in a weight ratio of 50:50 and LMFP particles in the form of single particles.

[0196] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that NMX particles, LMFP particles in the form of single particles, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.48:0.48:0.02:0.02 to prepare a first active material slurry.

[0197] Comparative Example 7: Preparation of a positive electrode including a first active material layer

[0198] A positive electrode consisting only of a first active material layer was prepared, which has NMX particles in a weight ratio of 40:60 and LMFP particles in the form of single particles.

[0199] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that NMX particles, LMFP particles in the form of single particles, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.384:0.576:0.02:0.02 to prepare a first active material slurry.

[0200] Comparative Example 8: Preparation of a positive electrode including a first active material layer

[0201] A positive electrode consisting only of a first active material layer was prepared, which has NMX particles in a weight ratio of 30:70 and LMFP particles in the form of single particles.

[0202] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that NMX particles, LMFP particles in the form of single particles, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.288:0.672:0.02:0.02 to prepare a first active material slurry.

[0203] Comparative Example 9: Preparation of a positive electrode including a first active material layer

[0204] A positive electrode consisting only of a first active material layer was prepared, which has NMX particles in a weight ratio of 20:80 and LMFP particles in the form of single particles.

[0205] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that NMX particles, LMFP particles in single-particle form, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.192:0.768:0.02:0.02 to prepare a first active material slurry.

[0206] Comparative Example 10: Preparation of a positive electrode including a first active material layer

[0207] A positive electrode consisting only of a first active material layer was prepared, which has NMX particles in a weight ratio of 10:90 and LMFP particles in the form of single particles.

[0208] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that NMX particles, LMFP particles in single-particle form, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.096:0.864:0.02:0.02 to prepare a first active material slurry.

[0209] Comparative Example 11: Preparation of a positive electrode including a first active material layer

[0210] A positive electrode consisting only of a first active material layer was prepared, which has NMX particles in a weight ratio of 30:35:35, LMFP particles in the form of single particles, and LMFP particles in the form of secondary particles.

[0211] The positive electrode was prepared in essentially the same manner as in Comparative Example 1, except that NMX particles, LMFP particles in the form of single particles, LMFP particles in the form of secondary particles, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.3:0.33:0.33:0.02:0.02 to prepare a first active material slurry.

[0212] Comparative Example 12: Fabrication of a positive electrode comprising a first active material layer and a second active material layer

[0213] A positive electrode with a weight ratio of FAD2 to FAD1 of 0.67 was prepared.

[0214] The positive electrode was prepared in essentially the same manner as in Example 2, except that NMX particles, LMFP particles in single-particle form, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.94:0.03:0.03 to prepare a first active material slurry, and LMFP particles in secondary-particle form, a second binder (polyvinylidene fluoride), and a second conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.96:0.02:0.02 to prepare a second active material slurry.

[0215] Comparative Example 13: Fabrication of a positive electrode comprising a first active material layer and a second active material layer

[0216] A positive electrode with a weight ratio of FAD2 to FAD1 of 5.00 was prepared.

[0217] The positive electrode was prepared in essentially the same manner as in Example 2, except that NMX particles, LMFP particles in single-particle form, a first binder (polyvinylidene fluoride), and a first conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.976:0.012:0.012 to prepare a first active material slurry, and LMFP particles in secondary-particle form, a second binder (polyvinylidene fluoride), and a second conductive material (carbon black) were dispersed in N-methylpyrrolidone in a weight ratio of 0.88:0.06:0.06 to prepare a second active material slurry.

[0218] Preparation of rechargeable lithium batteries

[0219] A 2032-type coin half-cell was prepared using a prepared positive electrode and a lithium metal counter electrode. A separator of approximately 16 μm thickness, formed of a porous polyethylene (PE) membrane, was placed between the positive electrode and the lithium metal counter electrode, and an electrolyte was injected to prepare a rechargeable lithium battery. The electrolyte was prepared by mixing 1.3 M LiPF6 with a solvent containing a mixture of ethylene carbonate (EC), ethyl methyl carbonate (EMC), and dimethyl carbonate (DMC) in a volume ratio of 3:4:3.

[0220] Tables 1 and 2 summarize Examples 1 and 2, as well as Comparative Examples 1 to 13.

[0221] Table 1

[0222]

[0223] Table 2

[0224]

[0225]

[0226] Evaluation Example 1: Analysis of the surface of the active material in the positive electrode

[0227] SEM images of each of the first, second, and third particles prepared in Preparation Examples 1 to 3 are shown below. Figures 10-13 (Chinese) Reference Figure 10 As can be seen, the first particle prepared according to Example 2 is in the form of a fine, single particle with a nanometer size. (Reference) Figure 11 As can be seen, the second particle prepared according to Example 1 is in the form of a small, single particle with a micrometer-sized particle. (Reference) Figure 12 As can be seen, the third particle prepared according to Example 2 is in the form of a fine, single particle with a nanometer size. (Reference) Figure 13 As can be seen, the third particle according to Preparation Example 3 is in the form of a spherical secondary particle in which multiple primary particles are aggregated.

[0228] Evaluation Example 2: Evaluation of Positive Electrode Active Material

[0229] The powder compaction density (PD) of the positive electrode active materials of the examples and comparative examples was measured, and the results are shown in Table 3. It can be seen that the positive electrode active materials according to one or more embodiments have a powder compaction density of 2.55 (g / cc) to 2.65 (g / cc).

[0230] Table 3

[0231]

[0232]

[0233] Evaluation Example 3: Evaluation of Resistance and Adhesion

[0234] The characteristics of rechargeable lithium batteries prepared using positive electrode active materials from the respective examples and comparative examples were evaluated.

[0235] For the initial charge / discharge, the rechargeable lithium battery was initially charged at 25°C with a constant current and constant voltage (4.45V) at 0.2C (0.05C cutoff). After resting for 10 minutes, it was discharged to 3.0V with a constant current of 0.2C, thus obtaining the initial charge capacity (charge at 0.2C (mAh / g)) and the initial discharge capacity (discharge at 0.2C (mAh / g)). The efficiency at 0.2C (%) (0.2C efficiency (%)) is expressed as initial discharge capacity / initial charge capacity. The rechargeable lithium battery was charged to SOC50 with a constant current of 0.2C and then rested at SOC50 for 1 hour. After that, the rechargeable lithium battery was discharged at 1.0C for 10 seconds and then rested for 10 seconds. At this time, the difference between the voltage after discharge and the voltage after 10 seconds of rest was divided by the current to calculate the cell resistance (DC-IR). The results are shown in Table 4.

[0236] Table 4

[0237]

[0238]

[0239] Referring to Table 4, the rechargeable lithium batteries including the positive electrodes according to Examples 1 and 2 exhibit higher discharge capacity and lower resistance than the rechargeable lithium batteries of Comparative Examples 2 and 3. Accordingly, it was determined that the addition of NMX particles increased the binding force of the positive electrode containing olivine-like compounds.

[0240] Furthermore, it is evident that the rechargeable lithium battery including the positive electrodes according to Examples 1 and 2 has a lower resistance than the rechargeable lithium batteries of Comparative Examples 12 and 13. Accordingly, it is evident that when the weight ratio of the second functional additive to the weight ratio of the first functional additive meets the desired range, the bonding force of the positive electrode can be increased.

[0241] Evaluation Example 4: Evaluation of Battery Characteristics

[0242] The characteristics of rechargeable lithium batteries prepared using positive electrode active materials from the respective examples and comparative examples were evaluated.

[0243] For initial charge / discharge, the rechargeable lithium battery was initially charged at 25°C with a constant current of 0.2C and a constant voltage (4.45V) (0.05C cutoff). After resting for 10 minutes, it was discharged to 3.0V with a constant current of 0.2C to obtain the initial charge and discharge capacities. The average voltage and current density were then evaluated. The average voltage (average drive voltage) was obtained by integrating the area under the discharge voltage curve (voltage-capacity plot) after the initial charge and discharge of the rechargeable lithium battery, and then dividing this integral by the discharge capacity. The energy density was obtained using the formula {average drive voltage (V) x capacity (Ah) / rechargeable lithium battery weight (kg)}, where the capacity was calculated by multiplying the positive electrode weight (g) by the discharge capacity (mAh / g). Subsequently, the battery was repeatedly charged / discharged 50 times at 1.0C (4.45V, 0.05C cutoff) / 1.0C (to 3.0V) to measure the discharge capacity at the 50th cycle. The efficiency (%) at 1.0C (1C lifetime (%, 50 cycles)) is expressed as the discharge capacity at the 50th cycle / initial discharge capacity. A rechargeable lithium battery was also prepared and initially charged at 25°C with a constant current and constant voltage (4.45V) (0.05C cutoff). After resting for 10 minutes, it was discharged to 3.0V with a constant current of 0.2C and then recharged at -20°C with a constant current and constant voltage (4.45V, 0.05C cutoff), followed by discharge to 3.0V with a constant current of 0.2C to measure the discharge capacity (-20°C capacity (mAh / g)). The battery performance evaluation results are shown in Table 5 below.

[0244] Table 5

[0245]

[0246]

[0247] Referring to Table 5, it can be seen that the rechargeable lithium battery including the positive electrode according to Examples 1 and 2 has excellent capacity and life characteristics, as well as high operating voltage and energy density.

[0248] The positive electrode for a rechargeable lithium battery according to embodiments of this disclosure contains a large amount of nano-sized olivine compounds, which increases the bonding force with respect to the positive electrode current collector. Therefore, this facilitates the fabrication of the electrode plate and reduces its resistance.

[0249] The rechargeable lithium battery according to embodiments of this disclosure can have excellent capacity and lifespan characteristics, as well as high operating voltage and energy density.

[0250] Examples and comparative examples are provided to highlight the characteristics of one or more implementations; however, it will be understood that the examples and comparative examples do not limit the scope of the implementations, nor should they be construed as exceeding the scope of the implementations. Furthermore, the implementations are not limited to the specific details described in the examples and comparative examples.

Claims

1. A positive electrode for a rechargeable lithium battery, comprising: A positive electrode current collector; A first active material layer on the positive electrode current collector, the first active material layer comprising first particles, second particles, a first binder, and a first conductive material; And A second active material layer on the first active material layer, the second active material layer comprising third particles, a second binder, and a second conductive material, Where the first particles are olivine-structured compounds of formula 1, Where the second particles are layered compounds of formula 2, Where the third particles are olivine-structured compounds of formula 3, Where the first active material layer and the second active material layer comprise less than 100 ppm of cobalt, Where the first particles are single particles, Where the first particles have an average diameter of 100 nm to 2 μm, Where the average diameter of the second particles is greater than the average diameter of the first particles, Where the third particles are single particles, and Where the third particles have an average diameter of 100 nm to 2 μm, Where formula 1 is: Li a1 Mn x1 Fe y1 B1 z1 PER 4-b1 Where 0.8 ≤ a1 ≤ 1.2, 0.4 ≤ x1 ≤ 0.8, 0 ≤ y1 ≤ 0.6, 0 ≤ z1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, and x1 + y1 + z1 = 1, and B1 comprises at least one of Al, Ti, V, and Mg, Where formula 2 is: Li a2 Ni x2 Mr z2 Al c2 Y d2 O 2-b2 Where 0.8 < a2 ≤ 1.2, 0.7 ≤ x2 ≤ 0.8, 0.2 ≤ z2 ≤ 0.3, 0 ≤ c2 ≤ 0.02, 0 ≤ d2 ≤ 0.003, 0 ≤ b2 ≤ 0.05, and x2 + z2 + c2 + d2 = 1, and Y comprises at least one of Ti, Mg, Zr, Mo, and Nb, and Where formula 3 is: Li a3 Mn x3 Fe y3 B3 z3 PO 4-b3 Where 0.8 ≤ a3 ≤ 1.2, 0.4 ≤ x3 ≤ 0.8, 0 ≤ y3 ≤ 0.6, 0 ≤ z3 ≤ 0.05, 0 ≤ b3 ≤ 0.05, and x3 + y3 + z3 = 1, and B3 comprises at least one of Al, Ti, V, and Mg.

2. The positive electrode for a rechargeable lithium battery according to claim 1, where the first binder and the first conductive material constitute a first functional additive, Where the second binder and the second conductive material constitute a second functional additive, and Where the weight ratio of the first functional additive in the first active material layer is lower than the weight ratio of the second functional additive in the second active material layer.

3. The positive electrode for a rechargeable lithium battery according to claim 2, where the ratio of the weight ratio of the second functional additive to the weight ratio of the first functional additive is 1.5 to 4.

5.

4. The positive electrode for a rechargeable lithium battery according to claim 1, where the amount of the first binder is 1.2 parts by weight to 3 parts by weight relative to 100 parts by weight of the first active material layer, and Where the amount of the second binder is 2 parts by weight to 5 parts by weight relative to 100 parts by weight of the second active material layer.

5. The positive electrode for a rechargeable lithium battery according to claim 1, wherein the amount of the first conductive material is 1.2 to 3 parts by weight relative to 100 parts by weight of the first active material layer, and wherein the amount of the second conductive material is 2 to 5 parts by weight relative to 100 parts by weight of the second active material layer.

6. The positive electrode for a rechargeable lithium battery according to claim 1, wherein the amount of the second particles is 15 wt% to 30 wt% relative to the total amount of the first particles, the second particles, and the third particles included in the first active material layer and the second active material layer.

7. The positive electrode for a rechargeable lithium battery according to claim 1, wherein the total doping amount of manganese included in the first active material layer and the second active material layer is 0.46 to 0.

52.

8. The positive electrode for a rechargeable lithium battery as claimed in claim 1, wherein the second particles have an average diameter of 3 μm to 7 μm.

9. The positive electrode for a rechargeable lithium battery as claimed in claim 1, wherein the BET specific surface area of the second particles is smaller than the BET specific surface area of the first particles.

10. A positive electrode for a rechargeable lithium battery, comprising: a positive electrode current collector; a first active material layer on the positive electrode current collector, the first active material layer including first particles, second particles, a first binder, and a first conductive material; and a second active material layer on the first active material layer, the second active material layer including third particles, a second binder, and a second conductive material, wherein the first particles are olivine-structured compounds of formula 1, wherein the second particles are layered compounds of formula 2, wherein the third particles are olivine-structured compounds of formula 3, wherein the first active material layer and the second active material layer include less than 100 ppm of cobalt, wherein the first particles are single particles, wherein the first particles have an average diameter of 100 nm to 2 μm, wherein the average diameter of the second particles is greater than the average diameter of the first particles, wherein each of the third particles includes a plurality of fourth particles aggregated together, wherein the third particles have an average diameter of 2 μm to 15 μm, and wherein the fourth particles are primary particles having an average diameter of 200 nm or less, wherein formula 1 is: Li a1 Mn x1 Fe y1 B1 z1 PER 4-b1 where 0.8 ≤ a1 ≤ 1.2, 0.4 ≤ x1 ≤ 0.8, 0 ≤ y1 ≤ 0.6, 0 ≤ z1 ≤ 0.05, 0 ≤ b1 ≤ 0.05, and x1 + y1 + z1 = 1, and where B1 includes at least one of Al, Ti, V, and Mg, wherein formula 2 is: Li a2 Ni x2 Mr z2 Al c2 Y d2 O 2-b2 where 0.8 < a2 ≤ 1.2, 0.7 ≤ x2 ≤ 0.8, 0.2 ≤ z2 ≤ 0.3, 0 ≤ c2 ≤ 0.02, 0 ≤ d2 ≤ 0.003, 0 ≤ b2 ≤ 0.05, and x2 + z2 + c2 + d2 = 1, and wherein Y includes at least one of Ti, Mg, Zr, Mo, and Nb, and wherein formula 3 is: Li a3 Mn x3 Fe y3 B3 z3 PO 4-b3 Where 0.8≤a3≤1.2, 0.4≤x3≤0.8, 0≤y3≤0.6, 0≤z3≤0.05, 0≤b3≤0.05, and x3+y3+z3=1, and B3 includes at least one of Al, Ti, V and Mg.

11. The positive electrode for a rechargeable lithium battery according to claim 10, wherein the first binder and the first conductive material constitute a first functional additive. The second adhesive and the second conductive material constitute the second functional additive, and The weight ratio of the first functional additive in the first active material layer is equal to or lower than the weight ratio of the second functional additive in the second active material layer.

12. The positive electrode for a rechargeable lithium battery according to claim 11, wherein the weight ratio of the second functional additive to the weight ratio of the first functional additive is 1 to 4.

5.

13. The positive electrode for a rechargeable lithium battery according to claim 10, wherein the amount of the first binder is 1.2 to 3 parts by weight relative to 100 parts by weight of the first active material layer, and The amount of the second adhesive is 1.2 to 3 parts by weight relative to 100 parts by weight of the second active material layer.

14. The positive electrode for a rechargeable lithium battery as claimed in claim 10, wherein the amount of the first conductive material is 1.2 to 3 parts by weight relative to 100 parts by weight of the first active material layer, and The amount of the second conductive material is 1.2 to 3 parts by weight relative to 100 parts by weight of the second active material layer.

15. The positive electrode for a rechargeable lithium battery as claimed in claim 10, wherein the amount of the second particle is 15 wt% to 30 wt% relative to the total amount of the first particle, the second particle, and the third particle included in the first active material layer and the second active material layer.

16. The positive electrode for a rechargeable lithium battery as claimed in claim 10, wherein the total manganese doping amount in the first active material layer and the second active material layer is 0.46 to 0.

52.

17. The positive electrode for a rechargeable lithium battery as claimed in claim 10, wherein the second particle has an average diameter of 3 μm to 7 μm.

18. The positive electrode for a rechargeable lithium battery as claimed in claim 10, wherein the BET specific surface area of ​​the second particle is smaller than that of the first particle.

19. The positive electrode for a rechargeable lithium battery as claimed in claim 10, wherein the third particle has a porosity of 20% to 40% and the span value of the third particle is 0.3 to 0.

75.

20. A rechargeable lithium battery comprising a positive electrode according to any one of claims 1 to 19.

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