Positive electrode material, and positive electrode and lithium secondary battery comprising same

Abstract

The present invention relates to: a positive electrode material capable of improving the performance of a lithium secondary battery; a positive electrode; and a lithium secondary battery, the positive electrode and the lithium secondary battery including the positive electrode material. The positive electrode material comprises: a first positive electrode active material including a first lithium-rich manganese-based oxide having a composition represented by chemical formula 1 or 2 described in the present specification, and a first coating portion formed on the first lithium-rich manganese-based oxide; and a second positive electrode active material including a second lithium-rich manganese-based oxide having a composition represented by chemical formula 1 or 2 described in the present specification, and a second coating portion formed on the second lithium-rich manganese-based oxide, wherein the first coating portion and the second coating portion each independently include at least one coating element (R) selected from the group consisting of aluminum (Al) and niobium (Nb), and the second positive electrode active material has a smaller average particle diameter (D50) than the first positive electrode active material.

Description

Cathode material, a cathode including the same, and a lithium secondary battery

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority based on Korean Patent Application No. 10-2024-0183884 filed on December 11, 2024, and all contents disclosed in the document of said Korean Patent Application are incorporated herein as part of this specification.

[0003] Technology field

[0004] The present invention relates to a cathode material, a cathode including the same, and a lithium secondary battery.

[0005]

[0006] Lithium secondary batteries consist of four major components: a positive electrode, a negative electrode, a separator, and an electrolyte. Among these, the positive electrode active material included in the positive electrode plays a significant role in determining the battery's capacity, output, and lifespan. Improving the performance of the positive electrode active material is essential for lithium secondary batteries to achieve high energy density, output, and lifespan; consequently, much research has recently been conducted to develop high-performance positive electrode active materials.

[0007] Lithium-rich layered oxide, a type of cathode active material, is a mixed phase consisting of Li2MnO3 and LiMO2 (M=Ni, Mn, Co) phases, with a high operating voltage (>3.5V vs. Li / Li + It has the characteristic of providing a very large capacity of 250 mAh / g. Accordingly, the lithium excess oxide is attracting attention as a low-cost, high-capacity cathode active material.

[0008] However, the aforementioned lithium excess oxide exhibits problems arising from its structural characteristics, specifically the presence of two mixed phases. Specifically, when a battery containing the lithium excess oxide is operated under high voltage, problems such as reduced efficiency occur due to irreversible capacity loss during the first formation process. Additionally, during charge-discharge cycles, voltage fading occurs as the structure changes from a layered structure through a spinel structure to a rock salt structure, leading to issues such as the generation of O2 gas.

[0009] Therefore, it is necessary to secure technology that improves the stability and performance of the above-mentioned lithium excess oxide.

[0010]

[0011] The present invention aims to solve the above-mentioned problems and to provide a cathode material capable of improving the lifespan and capacity characteristics of a battery.

[0012] In addition, the present invention aims to provide a positive electrode and a secondary battery having excellent lifespan characteristics and capacity characteristics, including the positive electrode material described above.

[0013]

[0014] (1) The present invention comprises: a first positive electrode active material comprising a first lithium-excess manganese oxide having a composition represented by the following chemical formula 1 or 2 and a first coating portion formed on the first lithium-excess manganese oxide; and a second positive electrode active material comprising a second lithium-excess manganese oxide having a composition represented by the following chemical formula 1 or 2 and a second coating portion formed on the second lithium-excess manganese oxide; wherein the first coating portion and the second coating portion each independently comprise one or more coating elements (R) selected from the group consisting of aluminum (Al) and niobium (Nb), and the second positive electrode active material has an average particle size (D) greater than that of the first positive electrode active material. 50) provides a cathode material that is small.

[0015] [Chemical Formula 1]

[0016] Li 1+x Mn a1 Ni b1 Q 1 c1 O2

[0017] In the above chemical formula 1,

[0018] Q 1 It is one or more selected from the group consisting of aluminum (Al) and cobalt (Co), and 0.00 <x≤0.20, 0.500≤a1<1.000, 0.200≤b1<0.500, 0.000<c1≤0.020이고,

[0019] [Chemical Formula 2]

[0020] αLi2Mn 1-c2 Q 2 c2 O3·βLi(Ni a2 Mn b2 Q 2 c3 )O2

[0021] In the above chemical formula 2,

[0022] Q 2 is one or more selected from the group consisting of aluminum (Al) and cobalt (Co), and 0<α<1, 0<β<1, 0.000≤c2≤0.010, 0.00 <a2≤0.50, 0.00<b2≤0.50, 0.00≤c3≤0.01, a2+b2+c3=1.00이고, c2+c3> It is 0.00.

[0023] (2) The present invention provides a cathode material in which the first lithium-excess manganese oxide and the second lithium-excess manganese oxide have the same composition as in (1).

[0024] (3) The present invention provides an anode material in which, in (1) or (2), the first coating part and the second coating part have the same coating element (R).

[0025] (4) The present invention provides a cathode material in which, in any one of (1) to (3), a1 in Chemical Formula 1 is 0.5 or more and 0.7 or less.

[0026] (5) In any one of (1) to (4) above, the present invention is such that the coating element (R) is Q 1 and Q 2 Provides a cathode material that is different in element.

[0027] (6) In any one of (1) to (5) above, the present invention is such that the first positive active material has an average particle size (D 50 Provides a cathode material having a thickness of 9.00㎛ or more and 15.00㎛ or less.

[0028] (7) In any one of (1) to (6) above, the present invention is such that the second positive active material has an average particle size (D 50 Provides a cathode material having a thickness of 2.00㎛ or more and 6.00㎛ or less.

[0029] (8) The present invention provides a cathode material in which, in any one of (1) to (7), the first cathode active material is included in an amount of 60% or more and 90% or less of the total weight of the first cathode active material and the second cathode active material.

[0030] (9) The present invention provides an anode comprising an anode material according to any one of (1) to (8).

[0031] (10) The present invention provides a lithium secondary battery comprising a positive electrode according to (9) above.

[0032]

[0033] The cathode material according to the present invention comprises cathode active materials having different average particle sizes, and each of the cathode active materials comprises a specific doping element and a specific coating element, thereby realizing an effect of improving the structural stability of the cathode material. Accordingly, the capacity characteristics and lifespan characteristics of the cathode and secondary battery including the cathode material are improved.

[0034]

[0035] Figure 1 is a graph of the amount of gas generated (ml) over time (weeks) of a monocell containing the cathode material prepared in the examples and comparative examples.

[0036] Figure 2 is a graph of the capacity retention rate according to the nth cycle of a battery containing the cathode material prepared in Example 1 and Comparative Example 1.

[0037]

[0038] Hereinafter, the present invention will be described in more detail to aid in understanding the invention.

[0039] Terms and words used in this specification and claims shall not be interpreted as being limited to their ordinary or dictionary meanings, but shall be interpreted in a meaning and concept consistent with the technical spirit of the invention, based on the principle that the inventor can appropriately define the concept of the terms to best describe his invention.

[0040] In this specification, terms such as 'comprising,' 'having,' or 'having' are intended to specify the existence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not excluding in advance the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0041] In this specification, the content of each element in the lithium-excess manganese-based oxide may be measured through inductive coupled plasma (ICP) analysis using an inductively coupled plasma emission spectrometer (ICP-OES; Optima 7300DV, PerkinElmer).

[0042] In this specification, the average particle size (D 50) can be defined as the particle diameter corresponding to 50% of the cumulative volume distribution in the particle size distribution curve (graph curve of the particle size distribution). The above average particle diameter is determined by dispersing the powder to be measured in a dispersant, introducing it into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500), calculating the particle size distribution by measuring the difference in diffraction patterns according to particle size as the particles pass through the laser beam, and calculating the particle diameter at the point where it is 50% of the cumulative volume distribution according to particle diameter in the measuring device, thereby determining the average particle diameter (D 50 ) can be measured.

[0043]

[0044] cathode material

[0045] Hereinafter, the cathode material according to the present invention will be described.

[0046] The cathode material according to the present invention comprises: a first cathode active material comprising a first lithium-excess manganese-based oxide having a composition represented by the following chemical formula 1 or 2 and a first coating portion formed on the first lithium-excess manganese-based oxide; and a second cathode active material comprising a second lithium-excess manganese-based oxide having a composition represented by the following chemical formula 1 or 2 and a second coating portion formed on the second lithium-excess manganese-based oxide; wherein the first coating portion and the second coating portion each independently comprise one or more coating elements (R) selected from the group consisting of aluminum (Al) and niobium (Nb), and the second cathode active material has an average particle size (D) greater than that of the first cathode active material. 50 ) is small.

[0047] [Chemical Formula 1]

[0048] Li 1+x Mn a1 Ni b1 Q 1 c1 O2

[0049] In the above chemical formula 1, Q 1It is one or more selected from the group consisting of aluminum (Al) and cobalt (Co), and 0.00 <x≤0.20, 0.500≤a1<1.000, 0.200≤b1<0.500, 0.000<c1≤0.020이고,

[0050] [Chemical Formula 2]

[0051] αLi2Mn 1-c2 Q 2 c2 O3·βLi(Ni a2 Mn b2 Q 2 c3 )O2

[0052] In the above chemical formula 2,

[0053] Q 2 is one or more selected from the group consisting of aluminum (Al) and cobalt (Co), and 0<α<1, 0<β<1, 0.000≤c2≤0.010, 0.00 <a2≤0.50, 0.00<b2≤0.50, 0.00≤c3≤0.01, a2+b2+c3=1.00이고, c2+c3> It is 0.00.

[0054]

[0055] The cathode material according to the present invention comprises a first cathode active material comprising a first lithium-excess manganese-based oxide having a composition represented by Formula 1 or 2 described herein and a first coating portion formed on the first lithium-excess manganese-based oxide, and a second cathode active material comprising a second lithium-excess manganese-based oxide having a composition represented by Formula 1 or 2 described herein and a second coating portion formed on the second lithium-excess manganese-based oxide, wherein the second cathode active material has an average particle size (D) greater than that of the first cathode active material. 50) is small. When the cathode material includes a first cathode active material and a second cathode active material with different particle sizes, small particles are positioned in the empty spaces between large particles, allowing more particles to be placed in the same volume, thereby increasing the charge / discharge characteristics of the cathode material and producing a uniform electrode slurry, which can improve the lifespan characteristics of the lithium secondary battery containing it.

[0056] On the other hand, when the cathode material contains only the first or second cathode active material, the empty spaces between particles cannot be efficiently filled, resulting in a problem where the tap density or rolled density of the cathode active material is low and the energy density of the battery is poor.

[0057] Meanwhile, the first positive electrode active material comprises a first lithium-excess manganese-based oxide having a composition represented by Chemical Formula 1 or 2 described in the present specification and a first coating portion formed on the first lithium-excess manganese-based oxide, and the second positive electrode active material comprises a second lithium-excess manganese-based oxide having a composition represented by Chemical Formula 1 or 2 described in the present specification and a second coating portion formed on the second lithium-excess manganese-based oxide; wherein the first coating portion and the second coating portion each independently comprise one or more coating elements (R) selected from the group consisting of aluminum (Al) and niobium (Nb), the voltage fading occurs relatively less and gas generation is reduced as the structure changes from a layered structure through a spinel structure to a rock salt structure during charge-discharge cycles.

[0058] On the other hand, if the first positive electrode active material does not include a first coating part comprising one or more coating elements (R) selected from the group consisting of aluminum (Al) and niobium (Nb) formed on a first lithium-excess manganese oxide having a composition represented by Chemical Formula 1 or 2 described in the present specification, or if the second positive electrode active material does not include a second coating part comprising one or more coating elements (R) selected from the group consisting of aluminum (Al) and niobium (Nb) formed on a second lithium-excess manganese oxide having a composition represented by Chemical Formula 1 or 2 described in the present specification, the structural stability is inferior, resulting in excessive gas generation during positive electrode charging and discharging, and a problem of inferior lifespan characteristics and capacity characteristics.

[0059]

[0060] Above Q 1 and Q 2 The doping element may be one or more selected from the group consisting of aluminum (Al) and cobalt (Co). By including the doping element, structural stability can be improved, and in particular, when combined with a coating element (R), lithium mobility can be improved, thereby improving the lifespan and capacity characteristics of the battery. When the doping element and the coating element (R) are not combined, there is a problem of inferior lifespan and capacity characteristics.

[0061] The above x may be greater than 0.00 and less than or equal to 0.20. When x satisfies the above range, the Li2MnO3 phase and the LiM'O2 phase are formed in an appropriate ratio, thereby enabling high capacity characteristics.

[0062] The above a1 may be 0.500 or more, 0.550 or more, or 0.600 or more, and may be 0.650 or less, 0.700 or less, 0.750 or less, 0.800 or less, 0.850 or less, 0.900 or less, 0.950 or less, or less than 1.000. When a1 satisfies the above range, it exhibits high energy density, thereby enabling high capacity characteristics. In particular, when a1 is 0.500 or more and 0.700 or less, the Li2MnO3 phase and the LiM'O2 phase are formed in an appropriate ratio, thereby enabling high capacity characteristics.

[0063] The above b1 may be 0.200 or more, 0.250 or more, or 0.300 or more, and may be 0.350 or less, 0.400 or less, 0.450 or less, or less than 0.500. When b1 satisfies the above range, it exhibits high energy density and can realize high capacity characteristics.

[0064] The above c1 may be greater than 0.000, greater than or equal to 0.001, greater than or equal to 0.002, or greater than or equal to 0.003, and less than or equal to 0.004, less than or equal to 0.005, less than or equal to 0.010, less than or equal to 0.050, less than or equal to 0.100, less than or equal to 0.150, or less than or equal to 0.020. When c1 satisfies the above range, the stability of the crystal structure of the positive electrode active material can be improved and the particle shape can be improved. In addition, when combined with a specific coating element, lithium mobility can be improved, thereby improving the lifespan and capacity characteristics of the battery.

[0065] The above α represents the molar ratio of the Li2MnO3 phase in the lithium-excess manganese-based oxide, and may be greater than 0, greater than 0.2, or greater than 0.4, and less than 0.6, less than 0.8, or less than 1. When α satisfies the above range, high energy density per unit volume is exhibited, thereby enabling high capacity characteristics. In addition, the capacity characteristics of the battery containing the cathode active material can be further improved.

[0066] The above c2 may be 0.000 or more, 0.002 or more, 0.004 or more, or 0.006 or more, and may be 0.008 or less, 0.009 or less, or 0.010 or less. When c2 satisfies the above range, the stability of the crystal structure of the positive electrode active material can be improved and the particle shape can be improved. In addition, when combined with a specific coating element, lithium mobility can be improved, thereby improving the lifespan and capacity characteristics of the secondary battery.

[0067] The above β represents the molar ratio of the LiM'O2 phase in the lithium-excess manganese-based oxide, and may be greater than 0, greater than 0.2, or greater than 0.4, and less than 0.6, less than 0.8, or less than 1. When β satisfies the above range, high energy density per unit volume is exhibited, thereby enabling high capacity characteristics. In addition, the capacity characteristics of the battery containing the cathode active material can be further improved.

[0068] The above a2 may be greater than 0.00, greater than or equal to 0.10, greater than or equal to 0.20, or greater than or equal to 0.30, and less than or equal to 0.40, or less than or equal to 0.50. When a2 satisfies the above range, it exhibits high energy density and can realize high capacity characteristics.

[0069] The above b2 may be greater than 0.00, greater than or equal to 0.10, greater than or equal to 0.20, or greater than or equal to 0.30, and less than or equal to 0.40, or less than or equal to 0.50. When b2 satisfies the above range, it exhibits high energy density and can realize high capacity characteristics.

[0070] The above c3 may be 0 or more, 0.002 or more, 0.004 or more, or 0.006 or more, and 0.008 or less, or 0.01 or less. When c3 satisfies the above range, the stability of the crystal structure of the positive active material can be improved and the particle shape can be improved. In addition, when combined with a specific coating element, lithium mobility can be improved to improve the capacity characteristics of the secondary battery.

[0071] In the above chemical formula 2, a2, b2, and c3 may be a2+b2+c3=1.00, and c2 and c3 may be c2+c3>0.00.

[0072]

[0073] The above lithium-excess manganese-based oxide may contain cobalt (Co) as a doping element. In this case, the cobalt (Co) in the lithium-excess manganese-based oxide may be included in trace amounts.

[0074]

[0075] According to one embodiment of the present invention, the first lithium-excess manganese oxide and the second lithium-excess manganese oxide may have the same composition. Specifically, the first lithium-excess manganese oxide and the second lithium-excess manganese oxide are Li 1.14 Mn 0.560 Ni 0.300 Al 0.002 It could be O2. When the compositions of the first lithium-excess manganese oxide and the second lithium-excess manganese oxide are identical, there is an advantageous aspect in the manufacturing process.

[0076]

[0077] According to one embodiment of the present invention, the first coating part and the second coating part may have the same coating element (R). Specifically, the first coating part and the second coating part may include niobium (Nb). When the coating element (R) of the first coating part and the second coating part is the same, there is an advantageous aspect in terms of the manufacturing process.

[0078]

[0079] According to one embodiment of the present invention, the coating element (R) is Q 1 and Q 2 The elements may be different. Specifically, the coating element (R) is niobium (Nb), and Q 1 and Q 2It may be aluminum (Al). In this case, the stability of the crystal structure of the positive electrode active material and the shape of the particles can be improved, as well as the lithium mobility can be improved, thereby improving the lifespan and capacity characteristics of the secondary battery.

[0080]

[0081] According to one embodiment of the present invention, the first positive active material has an average particle size (D 50 ) may be 9.00㎛ or more and 15.00㎛ or less. Specifically, the first cathode active material has an average particle size (D 50 The average particle size of the first cathode active material may be 9.00㎛ or more, 9.50㎛ or more, or 10.00㎛ or more, and may be 10.50㎛ or less, 11.00㎛ or less, 11.50㎛ or less, 12.00㎛ or less, 12.50㎛ or less, 13.00㎛ or less, 13.50㎛ or less, 14.00㎛ or less, 14.50㎛ or less, or 15.00㎛ or less. When the average particle size of the first cathode active material is within the above range, a cathode material with excellent energy density can be manufactured while improving electrode density. Since the coating portion formed on the lithium-excess manganese-based oxide according to the present invention is formed with a thickness in the nano range, the difference between the average particle size of the lithium-excess manganese-based oxide and the first cathode active material may not be large.

[0082] According to one embodiment of the present invention, the second positive active material has an average particle size (D 50 ) may be 2.00㎛ or more and 6.00㎛ or less. Specifically, the second positive active material has an average particle size (D 50The average particle size of the second cathode active material may be 2.00㎛ or more, 2.50㎛ or more, 3.00㎛ or more, 3.50㎛ or more, or 4.00㎛ or more, and may be 4.50㎛ or less, 5.00㎛ or less, 5.50㎛ or less, or 6.00㎛ or less. When the average particle size of the second cathode active material is within the above range, a cathode material with excellent energy density can be manufactured while improving electrode density. Since the coating portion formed on the lithium-excess manganese-based oxide according to the present invention is formed with a thickness in the nano range, the difference between the average particle size of the lithium-excess manganese-based oxide and the second cathode active material may not be large.

[0083]

[0084] According to one embodiment of the present invention, the first positive active material may be included in an amount of 60% by weight or more and 90% by weight or less relative to the total weight of the first positive active material and the second positive active material. Specifically, the first positive active material may be included in an amount of 60% by weight or more, or 65% by weight, and 70% by weight or less, 75% by weight or less, 80% by weight or less, 85% by weight or less, or 90% by weight or less relative to the total weight of the first positive active material and the second positive active material. When the content of the first positive active material in the positive material is within the above range, there is an effect of improving capacity characteristics, etc., while maintaining the structural stability of the positive material.

[0085]

[0086] Specifically, the first and second positive active materials of the present invention may be manufactured by a method for manufacturing a positive active material comprising: (A) a step of preparing a mixture by mixing a composite transition metal hydroxide containing nickel and manganese, a raw material containing a doping element, and a raw material containing lithium; (B) a step of preparing a lithium-excess manganese-based oxide by calcining the mixture; and (C) a step of mixing the lithium-excess manganese-based oxide with a raw material containing a coating element and heat-treating it.

[0087] According to one embodiment of the present invention, in step (A), a complex transition metal hydroxide containing nickel and manganese, a lithium (Li)-containing raw material, and a doping element-containing raw material may be mixed in an amount such that they have a composition represented by Formula 1 or 2 as described herein. The complex transition metal hydroxide containing nickel and manganese may not contain cobalt.

[0088] And, the average particle size of the composite transition metal hydroxide and the average particle size of the manufactured anode active material (D 50 The difference in ) may not be significant.

[0089] The above lithium-containing raw material may be a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it is soluble in water. Specifically, the above lithium-containing raw material may be Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, or Li3C6H5O7, and any one or more of these may be used.

[0090] The above-mentioned complex transition metal hydroxide containing nickel and manganese can be mixed such that the ratio (Li / M'') of the number of moles of lithium (Li) contained in the lithium-containing raw material to the total number of moles of transition metal (M'') contained in the above-mentioned complex transition metal hydroxide is 1.0 or more, 1.1 or more, 1.2 or more, 1.3 or more, and 1.5 or less.

[0091] When preparing the mixture of step (A) above, raw materials containing doping elements, such as aluminum-containing raw materials or cobalt-containing raw materials, may be further mixed.

[0092] The above step (B) may be a single calcination in which the mixture is calcined at a temperature of 600°C or higher and 1,000°C or lower to produce a lithium-excess manganese-based oxide, or a multi-stage calcination in which the mixture is calcined at a temperature of 600°C or higher and 1,000°C or lower to produce a calcined product, and then a lithium-containing raw material is additionally added and calcined at a temperature of 600°C or higher and 1,000°C or lower to produce a lithium-excess manganese-based oxide.

[0093] The above calcination may be performed under an atmospheric or oxygen atmosphere.

[0094] The first positive active material and the second positive active material manufactured according to the above method for manufacturing positive active materials may have a composition represented by Chemical Formula 1 or 2 described in this specification.

[0095]

[0096] The cathode material of the present invention can be manufactured according to conventional methods in the art. Specifically, it can be manufactured by mixing a first cathode active material and a second cathode active material.

[0097]

[0098] anode

[0099]

[0100] Next, the anode according to the present invention will be described.

[0101] The anode according to the present invention comprises an anode active material layer comprising an anode material according to the present invention. Specifically, the anode comprises an anode current collector and an anode active material layer formed on the anode current collector and comprising the anode material. Since the anode material has been described above, a detailed explanation is omitted, and only the remaining components are described in detail below.

[0102]

[0103] The above positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the above positive current collector may typically have a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the current collector to increase the adhesion of the positive active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0104]

[0105] The above-mentioned positive active material layer may include a conductive material and a binder together with the positive material. In this case, the positive material may be included in an amount of 80% to 99% by weight, more specifically 85% to 98.5% by weight, based on the total weight of the positive active material layer, and may exhibit excellent capacity characteristics within this range.

[0106]

[0107] The above conductive material is used to impart conductivity to the electrode, and in the battery being constructed, it may be used without special limitations as long as it possesses electronic conductivity without causing chemical changes. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, or silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and one of these alone or a mixture of two or more may be used. The above conductive material may be included in an amount of 0.1% to 15% by weight relative to the total weight of the positive electrode active material layer.

[0108]

[0109] The above binder serves to improve adhesion between positive active material particles and adhesion between the positive material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. The above binder may be included in an amount of 0.1% to 15% by weight based on the total weight of the positive active material layer.

[0110]

[0111] The above-described anode may be manufactured according to a conventional anode manufacturing method, except for using the anode material described above. Specifically, it may be manufactured by applying a composition for forming an anode active material layer, prepared by dissolving or dispersing the above-described anode material and, optionally, a binder and a conductive material in a solvent, onto an anode current collector, followed by drying and rolling. At this time, the types and contents of the anode material, binder, and conductive material are as described above. Alternatively, the above-described anode may be manufactured by casting the composition for forming an anode active material layer onto a separate support, and then laminating the film obtained by peeling from the support onto an anode current collector.

[0112]

[0113] The above solvent may be a solvent commonly used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of the above solvent used is sufficient if it is sufficient to dissolve or disperse the cathode material, conductive material, and binder, taking into account the coating thickness of the slurry and the manufacturing yield, and to have a viscosity that can exhibit excellent thickness uniformity when coated for cathode manufacturing thereafter.

[0114]

[0115] lithium secondary battery

[0116] Next, a lithium secondary battery according to the present invention will be described.

[0117]

[0118] The present invention can manufacture an electrochemical device comprising the anode. Specifically, the electrochemical device may be a battery, a capacitor, etc., and more specifically, a lithium secondary battery.

[0119]

[0120] Specifically, the above lithium secondary battery comprises a positive electrode, a negative electrode positioned opposite the positive electrode, and a separator and an electrolyte interposed between the positive electrode and the negative electrode. Since the positive electrode is identical to the one described above, a detailed description is omitted, and only the remaining components are described in detail below.

[0121]

[0122] In addition, the lithium secondary battery may optionally further include a battery container that accommodates the electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member that seals the battery container.

[0123]

[0124] In the above lithium secondary battery, the negative electrode comprises a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0125] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. In addition, the above-mentioned negative current collector may typically have a thickness of 3 μm to 500 μm, and, similar to the positive current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding strength of the negative active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0126]

[0127] The above-mentioned cathode active material layer optionally includes a binder and a conductive material together with the cathode active material.

[0128]

[0129] As the above-mentioned negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and SiO₂ βExamples include metal oxides capable of doping and dedoping lithium, such as (0<β<2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the metal compound and carbonaceous material, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the negative electrode active material. Furthermore, the carbon material may include low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0130] The above-mentioned negative electrode active material may be included in an amount of 80% to 99% by weight relative to the total weight of the negative electrode active material layer.

[0131]

[0132] The above binder is a component that assists in the bonding between the conductive material, the active material, and the current collector, and can typically be added in an amount of 0.1% to 10% by weight relative to the total weight of the negative active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0133]

[0134] The above conductive material is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10% by weight or less, specifically 5% by weight or less, based on the total weight of the negative electrode active material layer. Such conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fiber or metal fiber; metal powder such as carbon fluoride, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives may be used.

[0135]

[0136] The above-mentioned negative electrode active material layer may be manufactured by applying and drying a composition for forming a negative electrode active material layer, prepared by dissolving or dispersing a negative electrode active material and optionally a binder and a conductive material in a solvent, or by casting the composition for forming a negative electrode active material layer onto a separate support and then laminating the film obtained by peeling from the support onto a negative electrode current collector.

[0137]

[0138] Meanwhile, in the above-mentioned lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. Any separator typically used in lithium secondary batteries may be used without special limitations, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte moisture retention capacity. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber or polyethylene terephthalate fiber, may be used. Furthermore, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and may optionally be used in a single-layer or multi-layer structure.

[0139]

[0140] In addition, the electrolytes used in the present invention may include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which are usable when manufacturing lithium secondary batteries, but are not limited to these.

[0141] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0142] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; aromatic hydrocarbon-based solvents such as benzene and fluorobenzene; and carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC). Alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double bond-directing ring or ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, carbonate-based solvents are preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.In this case, using a mixture of cyclic carbonate and chain carbonate in a volume ratio of about 1:1 to about 1:9 can result in excellent performance of the electrolyte.

[0143]

[0144] The above lithium salt can be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably used within the range of 0.1 to 5.0 M, specifically 0.1 to 3.0 M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and allow lithium ions to move effectively.

[0145]

[0146] In addition to the above electrolyte components, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, a haloalkylene carbonate-based compound such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, triamide hexaphosphate, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the additive may be included in an amount of 0.1 to 10 weight%, specifically 0.1 to 5 weight%, based on the total weight of the electrolyte.

[0147]

[0148] As described above, since the lithium secondary battery containing the cathode material according to the present invention exhibits excellent lifespan and capacity characteristics, it is useful in portable devices such as mobile phones, laptop computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0149] Accordingly, according to another embodiment of the present invention, a battery module comprising the lithium secondary battery as a unit cell and a battery pack comprising the same are provided.

[0150] The above battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0151] The external shape of the lithium secondary battery of the present invention is not particularly limited, but can be a cylindrical shape using a can, a prismatic shape, a pouch shape, or a coin shape.

[0152] The lithium secondary battery according to the present invention can be used not only as a battery cell used as a power source for a small device, but can also preferably be used as a unit cell in a medium-to-large battery module comprising a plurality of battery cells.

[0153]

[0154] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0155]

[0156] Examples and Comparative Examples

[0157] Example 1

[0158] Mn 0.65 Ni 0.35 Complex transition metal hydroxide having a composition represented by (OH)2 (D 50 : 10㎛, secondary particle form) and Al(OH)3 were mixed so that the molar ratio of (Ni+Mn):Al was 1:0.019, and then LiOHH2O was mixed so that the molar ratio of (Ni+Mn+Al):Li was 1:1.31 to prepare a mixture.

[0159] The above mixture was calcined for 10 hours in an oxygen atmosphere at a temperature of 910 ℃ to produce a first lithium-excess manganese-based oxide.

[0160] Subsequently, the above first lithium-excess manganese oxide and Nb2O5 are Mn 0.65 Ni 0.35 A first cathode active material was prepared by mixing so that niobium (Nb) was 2,000 ppm relative to the total weight of (OH)2 and heat-treating for 6 hours at a temperature of 700 ℃ in an oxygen atmosphere. At this time, the Nb2O5 is Mn 0.65 Ni 0.35 The mixture is prepared such that niobium (Nb) is 0.19 mol% relative to the total number of moles of (OH)2.

[0161] Mn 0.65 Ni 0.35 Complex transition metal hydroxide having a composition represented by (OH)2 (D 50 : 4 μm, secondary particle form) and Al(OH)3 were mixed so that the molar ratio of (Ni+Mn):Al was 1:0.019, and then LiOHH2O was mixed so that the molar ratio of (Ni+Mn+Al):Li was 1:1.31 to prepare a mixture.

[0162] The above mixture was calcined for 10 hours in an oxygen atmosphere at a temperature of 910 ℃ to produce a second lithium-excess manganese-based oxide.

[0163] Subsequently, the above second lithium-excess manganese oxide and Nb2O5 are Mn0.65 Ni 0.35 A second cathode active material was prepared by mixing so that niobium (Nb) was 2,000 ppm relative to the total weight of (OH)2 and heat-treating for 6 hours at a temperature of 700 ℃ in an oxygen atmosphere. The above Nb2O5 is Mn 0.65 Ni 0.35 The mixture is prepared such that niobium (Nb) is 0.19 mol% relative to the total number of moles of (OH)2.

[0164] A cathode material was prepared by mixing the first cathode active material and the second cathode active material in a weight ratio of 65:35. That is, the first cathode active material in the cathode material is included in an amount of 65% by weight relative to the total weight of the first cathode active material and the second cathode active material.

[0165]

[0166] Comparative Example 1

[0167] A first positive active material was prepared in the same manner as in Example 1, except that Co(OH)2 was mixed instead of Nb2O5, and a second positive active material was prepared in the same manner as in Example 1, except that Co(OH)2 was mixed instead of Nb2O5.

[0168] A cathode material was prepared by mixing the first cathode active material and the second cathode active material in a weight ratio of 65:35. That is, the first cathode active material in the cathode material is included in an amount of 65% by weight relative to the total weight of the first cathode active material and the second cathode active material.

[0169]

[0170] Comparative Example 2

[0171] A first positive active material was prepared in the same manner as in Example 1, except that WO3 was mixed instead of Al(OH)3, and a second positive active material was prepared in the same manner as in Example 1, except that WO3 was mixed instead of Al(OH)3.

[0172] A cathode material was prepared by mixing the first cathode active material and the second cathode active material in a weight ratio of 65:35. That is, the first cathode active material in the cathode material is included in an amount of 65% by weight relative to the total weight of the first cathode active material and the second cathode active material.

[0173]

[0174] Comparative Example 3

[0175] A first positive active material was prepared in the same manner as in Example 1, except that WO3 was mixed instead of Al(OH)3 and Co(OH)2 was mixed instead of Nb2O5, and a second positive active material was prepared in the same manner as in Example 1, except that WO3 was mixed instead of Al(OH)3 and Co(OH)2 was mixed instead of Nb2O5.

[0176] A cathode material was prepared by mixing the first cathode active material and the second cathode active material in a weight ratio of 65:35. That is, the first cathode active material in the cathode material is included in an amount of 65% by weight relative to the total weight of the first cathode active material and the second cathode active material.

[0177]

[0178] Classification 1 Coating element (R) of the positive electrode active material 2 Coating element (R) of the positive electrode active material Example 1 NbNb Comparative Example 1 CoCo Comparative Example 2 NbNb Comparative Example 3 CoCo

[0179] Experimental Example

[0180] Experimental Example 1: ICP Analysis

[0181] Analysis of Lithium-Excess Manganese-Based Oxides

[0182] 0.1 g each of the first and second lithium-excess manganese oxides prepared in the above examples and comparative examples was taken, 1 ml of hydrochloric acid was added, and the mixture was heated to dissolve it. Subsequently, a small amount of hydrogen peroxide was added to promote the reaction and completely dissolve the lithium-excess manganese oxides to prepare a solution. Then, the solution was diluted with deionized water to a total volume of 10 ml to prepare an analytical sample. Using an ICP device (Perkin Elmer, OPTIMA 7300DV), the weight ratio of the constituent elements present in the analytical sample was measured, and the compositions of the first and second lithium-excess manganese oxides are shown in Table 2 below.

[0183] Classification 1 Lithium-Excess Manganese-Based Oxide Composition 2 Lithium-Excess Manganese-Based Oxide Composition Example 1 Li 1.14 Mn 0.560 Ni 0.300 Al 0.002 O2Li 1.14 Mn 0.560 Ni 0.300 Al 0.002 O2 Comparative Example 1Li 1.14 Mn 0.560 Ni 0.300 Al 0.002 O2Li 1.14 Mn 0.560 Ni 0.300 Al 0.002 O2 Comparative Example 2Li 1.14 Mn 0.560 Ni 0.300 W 0.002 O2Li 1.14 Mn 0.560 Ni 0.300 W 0.002 O2 Comparative Example 3Li 1.14 Mn 0.560 Ni 0.300 W 0.002 O2Li 1.14 Mn 0.560 Ni 0.300 W 0.002 O2

[0184] Through Table 2, it was confirmed that the first lithium-excess manganese oxide and the second lithium-excess manganese oxide prepared in Example 1 have a composition represented by Formula 1 or Formula 2 as described in this specification. In addition, it was confirmed that the first lithium-excess manganese oxide and the second lithium-excess manganese oxide prepared in Example 1 have the same composition.

[0185] Experimental Example 2: Measurement of Average Particle Size

[0186] In order to measure the average particle size of the first and second positive active material particles prepared in the above examples and comparative examples, the particle size of the first and positive active materials was measured using a PSA (Microtrac, S3500), and the results are shown in Table 3 below.

[0187] Average particle size (D 50 ) (㎛) First positive active material Second positive active material Example 19.6 13.74 Comparative Example 19.6 03.79 Comparative Example 29.6 03.76 Comparative Example 39.5 23.76

[0188] Through Table 3, the second cathode active material of the cathode material prepared in Example 1 has an average particle size (D) compared to the first cathode active material. 50 ) is small, and the first positive active material has an average particle size (D 50 ) is 9.00㎛ or more and 15.00㎛ or less, and the second cathode active material has an average particle size (D 50 It was confirmed that ) is 2.00㎛ or more and 6.00㎛ or less.

[0189] Experimental Example 3: Measurement of Gas Generation Amount

[0190] An anode slurry was prepared by mixing the anode material prepared in the above example or comparative example, a conductive material (Denka Black), and a binder (PVDF) in a weight ratio of 95:2:3 in an N-methyl-2-pyrrolidone (NMP) solvent. The anode slurry was applied onto an aluminum current collector, dried, and then rolled to produce an anode.

[0191] Next, a cathode active material (natural graphite), a conductive material (carbon black), and a binder (SBR+CMC) were mixed with water in a weight ratio of 95.6:1.0:3.4 to prepare a cathode slurry. The cathode slurry was applied onto a copper current collector, dried, and then rolled to produce a cathode.

[0192] An electrode assembly was manufactured by interposing a separator between the anode and the cathode, and then placed inside a battery case. Afterward, an electrolyte was injected to manufacture two mono cells with electrode sizes of 3 cm × 4 cm. At this time, as the electrolyte, an electrolyte solution was used in which 0.7 M LiPF6 and 0.3 M LiFSI were dissolved in an organic solvent mixed with ethylene carbonate and ethyl methyl carbonate in a volume ratio of 3:7.

[0193] The two monocells were charged to 4.2V with a 0.05C cut-off at 25°C using a constant current of 0.33C, and then the anodes were separated. The separated anodes were placed in a cell pouch, additional electrolyte was injected, and the pouch was sealed to prepare a sample. The sample was stored at 60°C for 12 weeks, and the amount of gas generated was measured. The amounts of gas generated at weeks 1, 2, 3, 4, 6, 8, and 12 are shown in Table 4 and Figure 1 below.

[0194] Figure 1 is a graph of the amount of gas generated (ml) over time (weeks) of a monocell containing the cathode material prepared in the examples and comparative examples.

[0195]

[0196] Gas Generation Amount (mL) Week 1 Week 2 Week 3 Week 4 Week 6 Week 8 Week 12 Week Example 10.070.090.120.130.130.160.21 Comparative Example 10.070.090.100.110.110.130.16 Comparative Example 20.090.130.160.200.200.240.36 Comparative Example 30.130.170.230.260.260.330.47

[0197] Through Table 4 and Figure 1, it was confirmed that the amount of gas generated in the monocell containing the cathode material prepared in Example 1 was lower compared to the monocell containing the cathode material prepared in Comparative Examples 2 and 3.

[0198] Experimental Example 4: High-temperature life evaluation

[0199] For the monocell prepared in Experimental Example 4 above, charging and discharging were repeated for a total of 300 cycles, with one cycle consisting of charging to 4.25 V at 45 ℃ using the CC-CV method (0.1C, cut-off current: 0.05C) followed by discharging to 2.5 V using the CC method (0.1C). After measuring the discharge capacity in the first cycle and the 300th cycle, the percentage of the discharge capacity of the 300th cycle relative to the discharge capacity of the first cycle (capacity retention rate (%)) was calculated. The results for the monocell containing the cathode material prepared in Example 1 and Comparative Example 1 are shown in Table 5 below.

[0200] Then, a total of 400 cycles of charging and discharging were repeated, and the discharge capacity in the first cycle and the nth cycle was measured. The percentage of the discharge capacity of the nth cycle relative to the discharge capacity of the first cycle (Capacity Retention (%)) was calculated and is shown in Figure 2 below.

[0201]

[0202] Figure 2 is a graph of the capacity retention rate according to the nth cycle of a battery containing the cathode material prepared in Example 1 and Comparative Example 1.

[0203]

[0204] Volume retention rate (%) Example 186.4 Comparative Example 185.7

[0205] Through Table 5, it was confirmed that the monocell containing the cathode material prepared in Example 1 had a superior capacity retention rate compared to the monocell containing the cathode material prepared in Comparative Example 1.

[0206] Experimental Example 5: Evaluation of Room Temperature Capacity

[0207] An anode slurry was prepared by mixing 97.5 wt% of each anode material prepared in the above examples and comparative examples, 1.0 wt% of Super P as a conductive material, and 1.5 wt% of polyvinylidene fluoride (PVDF) as a binder in an N-methylpyrrolidone (NMP) solvent. The prepared anode slurry was applied to one side of an aluminum current collector, dried at 130°C, and then rolled to produce an anode.

[0208] An electrode assembly was manufactured by using a lithium metal electrode as the negative electrode and interposing a porous polyethylene separator between the positive and negative electrodes. This was placed inside a battery case, and a coin-type half-cell was manufactured by injecting an electrolyte solution in which 1M LiPF6 was dissolved in an organic solvent mixed with ethylene carbonate (EC):ethyl methyl carbonate (EMC):diethyl carbonate (DEC) in a volume ratio of 3:4:3.

[0209]

[0210] Using a coin-type half-cell containing each of the cathode materials prepared in the above examples and comparative examples, an activation process (formation) was performed, followed by charging (0.33C) in a CC-CV manner to 4.4 V at 25 ℃, and then discharging (0.33C) in a CC manner to 2.5 V, and the discharge capacity at this time was measured. For the batteries containing the cathode materials prepared in Example 1 and Comparative Example 1, the measured discharge capacity (mAh / g) is shown in Table 5 below.

[0211] After charging (0.1C) to 4.4 V using the CC-CV method at 25 ℃, the discharge (0.1C) was discharged (0.1C) using the CC method to 2.5 V, and the discharge capacity was measured. For the batteries containing the cathode materials prepared in Example 1 and Comparative Example 1, the measured discharge capacity (mAh / g) is shown in Table 6 below.

[0212]

[0213] Discharge capacity (mAh / g) 0.1C 0.33C Example 1 216.3 202.2 Comparative Example 1 209.9 194.5

[0214] Through Table 6, it was confirmed that the discharge capacity at 0.1C and 0.33C of the battery containing the cathode material prepared in Example 1 was superior to that of the battery containing the cathode material prepared in Comparative Example 1. In conclusion, the cathode material prepared in Example 1, i.e., the cathode material according to the present invention, comprises: a first cathode active material comprising a first lithium-excess manganese oxide having a composition represented by Formula 1 or 2 described herein and a first coating portion formed on the first lithium-excess manganese oxide; and a second cathode active material comprising a second lithium-excess manganese oxide having a composition represented by Formula 1 or 2 described herein and a second coating portion formed on the second lithium-excess manganese oxide; wherein the first coating portion and the second coating portion each independently comprise one or more coating elements (R) selected from the group consisting of aluminum (Al) and niobium (Nb), and the second cathode active material has an average particle size (D) greater than that of the first cathode active material. 50 By satisfying the condition that ) is small, it was confirmed that the structural stability is improved compared to the cathode material prepared in Comparative Example 1, in which the coating element does not include aluminum (Al) and niobium (Nb); Comparative Example 2, in which the first and second lithium-excess manganese-based oxides having a composition represented by Chemical Formula 1 or 2 described in this specification do not include the first and second lithium-excess manganese-based oxides having a composition represented by Chemical Formula 1 or 2 described in this specification, and the coating element does not include aluminum (Al) and niobium (Nb). Accordingly, it was confirmed that when a battery is manufactured using the cathode material according to the present invention, the amount of gas generated by the battery is low, while the high-temperature capacity retention rate and discharge capacity are excellent.

Claims

1. A first positive electrode active material comprising a first lithium-excess manganese-based oxide having a composition represented by the following chemical formula 1 or 2 and a first coating portion formed on the first lithium-excess manganese-based oxide; and A second positive electrode active material comprising a second lithium-excess manganese-based oxide having a composition represented by the following chemical formula 1 or 2 and a second coating portion formed on the second lithium-excess manganese-based oxide; and The first coating part and the second coating part each independently comprise one or more coating elements (R) selected from the group consisting of aluminum (Al) and niobium (Nb), and The above second positive active material has an average particle size (D) greater than that of the above first positive active material. 50 Cathode material that is small: [Chemical Formula 1] The 1+x Mn a1 Nor b1 Q 1 c1 O2 In the above chemical formula 1, Q 1 It is one or more selected from the group consisting of aluminum (Al) and cobalt (Co), and 0.00 <x≤0.20, 0.500≤a1<1.000, 0.200≤b1<0.500, 0.000<c1≤0.020이고, [Chemical Formula 2] αLi2Mn 1-c2 Q 2 c2 O3·βLi(Ni a2 Mn b2 Q 2 c3 )O2 In the above chemical formula 2, Q 2 is one or more selected from the group consisting of aluminum (Al) and cobalt (Co), and 0<α<1, 0<β<1, 0.000≤c2≤0.010, 0.00 <a2≤0.50, 0.00<b2≤0.50, 0.00≤c3≤0.01, a2+b2+c3=1.00이고, c2+c3> It is 0.

00.

2. In Claim 1, The above-mentioned first lithium-excess manganese-based oxide and second lithium-excess manganese-based oxide are cathode materials having the same composition.

3. In Claim 1, The anode material in which the first coating part and the second coating part have the same coating element (R).

4. In Claim 1, A cathode material in which, in the above chemical formula 1, a1 is 0.5 or more and 0.7 or less.

5. In Claim 1, The above coating element (R) is Q 1 and Q 2 A cathode material that is different from the element.

6. In Claim 1, The above first positive active material has an average particle size (D 50 A cathode material having a thickness of 9.00㎛ or more and 15.00㎛ or less.

7. In Claim 1, The above second positive active material has an average particle size (D 50 A cathode material having a thickness of 2.00㎛ or more and 6.00㎛ or less.

8. In Claim 1, A cathode material comprising the first positive active material in an amount of 60% or more and 90% or less of the total weight of the first positive active material and the second positive active material.

9. An anode comprising an anode material according to any one of claims 1 to 8.

10. A lithium secondary battery comprising a positive electrode according to claim 9.

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