Positive electrode active material, method for producing same, and positive electrode and lithium secondary battery comprising same

Abstract

The present invention relates to: a positive electrode active material capable of improving the performance of a lithium secondary battery, the positive electrode active material comprising a lithium-rich manganese-based oxide including both an Li2MnO3 phase and a LiMO2 (where, M is an element including Ni, Mn, or a combination thereof) phase, wherein the lithium-rich manganese-based oxide has a composition represented by chemical formula 1 disclosed in the present specification; a method for producing same; and a positive electrode and a lithium secondary battery comprising same.

Description

Positive electrode active material, method for producing the same, and positive electrode and lithium secondary battery including the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority from Korean Patent Application No. 10-2023-0109714, filed August 22, 2023, the entire contents of which are incorporated herein by reference.

[0003] Technology field

[0004] The present invention relates to a positive electrode active material, a method for producing the same, and a positive electrode and a lithium secondary battery including the same.

[0005]

[0006] Lithium secondary batteries are composed of four major components: a cathode, an anode, a separator, and an electrolyte. Among these, the cathode active material contained in the cathode plays a significant role in determining the battery's capacity, output, and lifespan. For lithium secondary batteries to achieve high energy density, output, and lifespan, improving the performance of the cathode active material is essential. Consequently, extensive research has been conducted recently to develop high-performance cathode active materials.

[0007] Li-rich layered oxide, a type of cathode active material, is a mixed phase of Li2MnO3 phase and LiMO2 (where M is an element including Ni, Mn, Co or a combination thereof) phase and has a high operating voltage (>3.5 V vs. Li / Li). + ) has the characteristic of providing a very large capacity of 250 mAh / g. Therefore, the lithium-excess oxide is attracting attention as a high-capacity cathode active material.

[0008] However, the lithium-excess oxide has problems that arise due to its structural characteristic of having two phases mixed together. Specifically, when a battery containing the lithium-excess oxide is operated under high voltage, there is a problem of reduced efficiency due to irreversible capacity loss occurring in the first formation process, and during charge / discharge cycles, voltage fading occurs as the layered structure changes to a spinel structure and then to a rock salt structure, and there are problems such as generation of O2 gas.

[0009] Additionally, the rising price of cobalt, a raw material used in lithium-excess oxides, is also emerging as a significant issue. The price of cobalt is expected to continue to rise, necessitating the development of cathode active materials with reduced cobalt content.

[0010] Therefore, there is a need to secure technology to improve the stability, performance, and economic feasibility of the lithium-excess oxide.

[0011]

[0012] [Prior Art Literature]

[0013] [Patent Document]

[0014] (Patent Document 1) Korean Patent Publication No. 10-2014-0025102

[0015]

[0016] The present invention is intended to solve the above problems, and to provide a cathode active material and a method for manufacturing the same, which can improve the capacity characteristics, efficiency characteristics, and output characteristics of a battery and reduce costs.

[0017] In addition, the present invention seeks to provide an economical cathode and secondary battery having excellent capacity characteristics, efficiency characteristics, and output characteristics, including the cathode active material as described above.

[0018]

[0019] (1) The present invention provides a cathode active material comprising a lithium-excess manganese oxide simultaneously including a Li2MnO3 phase and a LiMO2 (wherein M is an element including Ni, Mn or a combination thereof) phase, wherein the lithium-excess manganese oxide has a composition represented by the following chemical formula 1.

[0020] [Chemical Formula 1]

[0021] Li 1+x Ni a Mn b W c M 1 d O2

[0022] In the above chemical formula 1,

[0023] M 1 is at least one selected from Al, P, V, Y, Ti and Nb,

[0024] 0.10≤x≤0.20, 0 <a<0.5, 0.5≤b<1.0, 0<c<0.008, 0≤d<0.005이다.

[0025] (2) The present invention provides a positive electrode active material in the above (1), wherein a is 0.30 to 0.35.

[0026] (3) The present invention provides a positive electrode active material in (1) or (2) above, wherein b is 0.55 to 0.60.

[0027] (4) The present invention provides a positive electrode active material in any one of the above (1) to (3), wherein c is 0.0005 to 0.007.

[0028] (5) The present invention provides a positive electrode active material in any one of the above (1) to (4), wherein the content of W is 800 ppm to 15,000 ppm based on the total weight of the lithium-excess manganese oxide.

[0029] (6) In any one of (1) to (5), the lithium-excess manganese oxide has a tap density of 1.5 g / cm. 3 2.5g / cm 3 It provides a positive electrode active material.

[0030] (7) In any one of the above (1) to (6), the lithium-excess manganese oxide has an average particle diameter (D 50 ) provides a positive electrode active material having a diameter of 2㎛ to 12㎛.

[0031] (8) (A) a step of preparing a mixture by mixing a composite transition metal hydroxide, a lithium (Li)-containing raw material, and a tungsten (W)-containing raw material; and (B) a step of heat-treating the mixture to prepare a lithium-excess manganese oxide; wherein the heat treatment is performed at a temperature of 600°C to 1,000°C. A method for preparing a positive electrode active material according to any one of (1) to (7) is provided.

[0032] (9) The present invention provides a method for producing a positive electrode active material, wherein, in the above (8), the tungsten (W)-containing raw material is mixed in an amount of 1,000 ppm to 17,000 ppm based on the total weight of the composite transition metal hydroxide.

[0033] (10) The present invention provides a method for manufacturing a positive electrode active material, wherein in step (8) or (9), the heat treatment in step (B) is performed under an air atmosphere.

[0034] (11) The present invention provides a positive electrode comprising a positive electrode active material according to any one of (1) to (7).

[0035] (12) The present invention provides a lithium secondary battery including a positive electrode according to (11) above.

[0036]

[0037] The cathode active material according to the present invention includes a lithium-excess manganese oxide that simultaneously includes a Li2MnO3 phase and a LiMO2 (wherein M is an element including Ni, Mn or a combination thereof) phase, and includes tungsten (W), thereby improving the performance of a lithium secondary battery, for example, capacity characteristics, efficiency characteristics and output characteristics, and has the effect of reducing cost.

[0038] In addition, according to the method for manufacturing a positive electrode active material of the present invention, the positive electrode active material described above can be effectively manufactured.

[0039]

[0040] Figure 1 shows XRD data of each of the positive electrode active materials manufactured in Examples 1 to 5.

[0041] Figure 2 shows XRD data of each of the positive electrode active materials manufactured in Comparative Examples 1 to 4.

[0042] Figure 3 is SEM data of the positive electrode active material manufactured in Example 1.

[0043]

[0044] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0045] Terms or words used in this specification and claims should not be interpreted as limited to their usual or dictionary meanings, but should be interpreted as meanings and concepts that conform to the technical idea of ​​the present invention, based on the principle that the inventor can appropriately define the concept of the term to explain his or her own invention in the best way.

[0046] It should be understood that the terms “include,” “have,” or “have” used in this specification are intended to specify the presence of a feature, number, step, component, or combination thereof, but do not preclude the possibility of the presence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0047] In this specification, tap density is measured at a distance of about 20 cm using a conventional tap density meter (e.g., GEOPYC-1360 from Micromeritics). 3 It can be measured by filling 10g of powder into a container, applying pressure of 108N, measuring the density of the particles twice, and calculating the average of the measured values.

[0048] In this specification, the average particle diameter (D 50 ) can be defined as the particle size corresponding to 50% of the volume cumulative distribution in the particle size distribution curve (graph curve of particle size distribution) of each particle. The above average particle size is calculated by dispersing the powder to be measured in a dispersion medium, introducing it into a commercially available laser diffraction particle size measuring device (e.g., S3500 of Microtrac), and measuring the difference in diffraction pattern according to particle size when the particles pass through the laser beam, and calculating the particle diameter at the point where it becomes 50% of the volume cumulative distribution according to the particle size in the measuring device, thereby obtaining D 50 can be measured.

[0049] In this specification, a primary particle means the smallest particle unit recognized when observing a positive electrode active material using a scanning electron microscope (SEM), and a secondary particle means a secondary structure formed by the aggregation of multiple primary particles.

[0050]

[0051] positive electrode active material

[0052] Hereinafter, the positive electrode active material according to the present invention will be described.

[0053] The cathode active material according to the present invention includes a lithium-excess manganese oxide that simultaneously includes a Li2MnO3 phase and a LiMO2 (wherein M is an element including Ni, Mn or a combination thereof) phase, and the lithium-excess manganese oxide has a composition represented by the following chemical formula 1.

[0054] [Chemical Formula 1]

[0055] Li 1+x Ni a Mn b W c M 1 d O2

[0056] In the above chemical formula 1,

[0057] M 1 is at least one selected from Al, P, V, Y, Ti and Nb,

[0058] 0.10≤x≤0.20, 0 <a<0.5, 0.5≤b<1.0, 0<c<0.008, 0≤d<0.005이다.

[0059] Lithium-rich layered oxide, a type of positive electrode active material, is a mixed phase in which Li2MnO3 phase and LiMO2 phase (where M is an element including Ni, Mn, Co or a combination thereof) phase are mixed. When Co is included, Co acts as an impurity, which reduces the capacity characteristics of a secondary battery including lithium-rich layered oxide and has the problem of high manufacturing costs.

[0060] The inventors of the present invention have conducted repeated research to solve such problems and have found that by doping W in a specific amount without including Co in the lithium-excess oxide, the phenomenon of capacity reduction can be suppressed and the activation of Mn can be increased, thereby improving the capacity characteristics, efficiency characteristics, output characteristics and economic feasibility of the existing lithium-excess manganese oxide, thereby completing the present invention.

[0061] Above M 1 is a doping element, specifically the above M 1 M may be at least one selected from Al, P, V, Y, Ti and Nb. 1 Although it is not essential, if included in an appropriate amount, the particle shape of the positive electrode active material can be improved and the stability of the crystal structure can be enhanced.

[0062] The above x may be 0.10 or more, 0.11 or more, 0.12 or more, 0.14 or more, 0.145 or more, or 0.150 or more, and may be 0.155 or less, 0.16 or less, 0.18 or less, or 0.20 or less. When x satisfies the above range, a high energy density per unit g may be exhibited, thereby realizing high-capacity characteristics.

[0063] The above a may be greater than 0, 0.2 or more, 0.3 or more, 0.305 or more, 0.306 or more, 0.307 or more, or 0.310 or more, and may be 0.313 or less, 0.32 or less, 0.35 or less, 0.4 or less, 0.45 or less, or less than 0.5. When a satisfies the above range, high energy density is exhibited, so that high-capacity characteristics can be realized. In particular, when a is 0.30 to 0.35, stability and economy can be improved.

[0064] The above b may be 0.50 or more, 0.52 or more, 0.54 or more, or 0.55 or more, and may be 0.57 or less, 0.60 or less, 0.65 or less, 0.7 or less, 0.8 or less, 0.9 or less, or less than 1. When b satisfies the above range, high energy density is exhibited, and high capacity characteristics can be implemented. In particular, when b is 0.55 to 0.60, stability and economy can be improved.

[0065] The above c may be greater than 0, 0.0005 or more, 0.0009 or more, 0.001 or more, 0.002 or more, or 0.004 or more, and may be 0.006 or less, 0.007 or less, or less than 0.008. When c satisfies the above range, the capacity characteristics, efficiency characteristics, and output characteristics can be improved. In particular, when c is 0.0005 to 0.007, the activation degree of Mn can be effectively increased to improve the capacity characteristics. On the other hand, when the lithium-excess oxide does not contain W, there is a problem that the capacity characteristics, efficiency characteristics, and output characteristics of the lithium secondary battery including the lithium-excess oxide are deteriorated due to the structural instability of the lithium-excess oxide. When c is 0.008 or more, there is a problem that the capacity characteristics, efficiency characteristics, and output characteristics of the lithium secondary battery including the lithium-excess oxide are deteriorated due to the excessive tungsten (W) acting as an impurity.

[0066] The above d may be 0 or more, 0.001 or more, 0.003 or more, or 0.002 or more, and may be 0.004 or less, or less than 0.005. When d satisfies the above range, the particle shape of the positive electrode active material may be improved and the stability of the crystal structure may be enhanced.

[0067] The above lithium-excess manganese oxide may be one that does not contain cobalt (Co). In this case, there is a cost-saving effect and the performance of a lithium secondary battery can be improved without containing cobalt.

[0068] In the above chemical formula 1, x, a, b, c, and d may be x+a+b+c+d≥1.

[0069] The above lithium-excess manganese oxide may have a composition represented by the following chemical formula 2.

[0070] [Chemical Formula 2]

[0071] αLi2Mn y1 W z1 O3·(1-α)Li(Nix2 Mn y2 W z2 )O2

[0072] In the above chemical formula 2,

[0073] 0.2≤α≤0.4, y1+z1≤1, 0.4≤x2≤0.6, 0.4≤y2≤0.6, 0.0007≤z1+z2<0.011, and x2+y2+z2≤1.

[0074] The above α refers to the molar ratio of Li2MnO3 phase in the lithium-excess manganese oxide, and may be 0.2 or more, 0.25 or more, or 0.27 or more, and may be 0.33 or less, 0.35 or less, or 0.4 or less. When α satisfies the above range, a high energy density per unit g is exhibited, so that high-capacity characteristics can be realized. In addition, the charge / discharge capacity, initial charge / discharge efficiency, and rate characteristics of a battery including a positive electrode active material can be further improved.

[0075] The above y1 and z1 are y1+z1≤1. When y1 and z1 satisfy the above range, high energy density is exhibited, so that high capacity characteristics can be realized.

[0076] The above x2 may be 0.4 or more, 0.44 or more, or 0.48 or more, and may be 0.52 or less, 0.56 or less, or 0.6 or less. When x2 satisfies the above range, high energy density may be exhibited, thereby realizing high-capacity characteristics.

[0077] The above y2 may be 0.4 or more, 0.44 or more, or 0.48 or more, and may be 0.52 or less, 0.56 or less, or 0.6 or less. When y2 satisfies the above range, a high energy density may be exhibited, thereby realizing high-capacity characteristics.

[0078] The above z1+z2 may be 0.0007 or more, 0.003 or more, or 0.005 or more, and may be 0.006 or less, 0.008 or less, or less than 0.011. When z1+z2 satisfies the above range, the capacity characteristics, efficiency characteristics, and output characteristics can be improved.

[0079] The above x2, y2, and z2 are x2+y2+z2≤1. When x2, y2, and z2 satisfy the above range, the capacity characteristics, efficiency characteristics, and output characteristics can be improved.

[0080]

[0081] According to one embodiment of the present invention, the content of W may be 800 ppm or more, 1,000 ppm or more, 2,000 ppm or more, 4,000 ppm or more, 6,000 ppm or more, or 8,700 ppm or more, and may be 12,000 ppm or less, 13,500 ppm or less, or 15,000 ppm or less, based on the total weight of the lithium-excess manganese oxide. When the content of W is within the above range, the capacity characteristics, efficiency characteristics, and output characteristics of the positive electrode active material may be improved.

[0082]

[0083] According to one embodiment of the present invention, the lithium-excess manganese oxide has a tap density of 1.5 g / cm 3 Above, 1.7g / cm 3 Above, 1.9g / cm 3 Above, 2.1g / cm 3 or 2.2 g / cm 3 It may be more than 2.3g / cm 3 Below, 2.4g / cm 3 or less, or 2.5 g / cm 3 It may be as follows. When the tap density is within the above range, the packing density of the electrode increases, so that high-capacity characteristics can be realized and economic efficiency can be improved.

[0084]

[0085] According to one embodiment of the present invention, the lithium-excess manganese oxide has an average particle diameter (D 50 ) may be 2 ㎛ or more, 2.5 ㎛ or more, or 3 ㎛ or more, and may be 9 ㎛ or less, 10 ㎛ or less, 11 ㎛ or less, or 12 ㎛ or less. The average particle diameter (D 50 ) is within the above range, electrode rolling is possible without breaking the particles of the positive electrode active material, thereby improving the capacity characteristics.

[0086]

[0087] Method for manufacturing positive electrode active material

[0088] Next, a method for manufacturing the positive electrode active material of the present invention will be described. The method for manufacturing the positive electrode active material of the present invention is a method for manufacturing the positive electrode active material according to the present invention.

[0089]

[0090] The method for producing a cathode active material of the present invention comprises the steps of (A) mixing a composite transition metal hydroxide, a lithium (Li)-containing raw material, and a tungsten (W)-containing raw material to produce a mixture; and (B) heat-treating the mixture to produce a lithium-excess manganese oxide; wherein the heat treatment is performed at a temperature of 600°C to 1,000°C.

[0091] According to the present invention described above, the type of raw material, the mixing ratio of raw materials, the heat treatment temperature, the heat treatment time, etc. can be appropriately adjusted to manufacture the product.

[0092]

[0093] Hereinafter, each step of the present invention will be described in detail.

[0094]

[0095] (A) Step

[0096] It includes the step (A) of preparing a mixture by mixing a composite transition metal hydroxide, a lithium (Li)-containing raw material, and a tungsten (W)-containing raw material.

[0097]

[0098] The above mixing can be done by dry mixing or wet mixing. When mixing each component through dry mixing, the firing process can be performed without a separate drying process. When mixing each component through wet mixing, the mixture can be prepared by adding it to a solvent, specifically water, or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water, or a solution containing each raw material, specifically an aqueous solution, is prepared, and then the mixed components are mixed and spray-dried before the firing process is performed. Each raw material and composite transition metal hydroxide can be used in an appropriate amount considering the content of each metal element in the lithium composite transition metal oxide to be finally manufactured.

[0099] The above complex transition metal hydroxide can be produced through a co-precipitation reaction by introducing a complex transition metal aqueous solution, an ammonium cation complex forming agent, and a basic compound into a reactor.

[0100] The above-mentioned complex transition metal aqueous solution can be prepared by dissolving a transition metal-containing raw material in a solvent such as water. For example, it can be prepared by dissolving a nickel (Ni)-containing raw material and a manganese (Mn)-containing raw material in water. In addition, if necessary, the above-mentioned transition metal aqueous solution can further include a metal-containing raw material.

[0101] The above nickel (Ni)-containing raw material may be at least one selected from the group consisting of NiO, Ni(OH)2, NiOㆍOH, NiCO3ㆍ2Ni(OH)2ㆍ4H2O, NiC2O4ㆍ2H2O, Ni(NO3)2ㆍ6H2O, NiSO4ㆍ6H2O, fatty acid nickel, and nickel halides, and a mixture of one or two or more of these may be used. Specifically, when considering economic feasibility and ease of manufacturing process, NiSO4ㆍ6H2O may be used as the nickel-containing raw material.

[0102] The manganese (Mn)-containing raw material may be at least one selected from the group consisting of MnCO3, Mn2O3, MnO2, Mn3O4, Mn(NO3)2, MnSO4ㆍH2O, manganese acetate, manganese dicarboxylate, manganese citrate, manganese salts of fatty acid manganese, oxyhydroxides, and halides of manganese chloride, and a mixture of one or two or more of these may be used. Specifically, when considering economic feasibility and ease of manufacturing process, MnSO4ㆍH2O may be used as the manganese-containing raw material.

[0103] Nickel (Ni)-containing raw materials and manganese (Mn)-containing raw materials can be used in appropriate amounts considering the content of each metal element in the composite transition metal hydroxide being manufactured.

[0104] Meanwhile, the ammonium cation complex forming agent may include at least one compound selected from the group consisting of NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, and NH4CO3, and may be introduced into the reactor in the form of a solution in which the compound is dissolved in a solvent. At this time, as the solvent, water or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water may be used.

[0105] The basic compound may be at least one compound selected from the group consisting of NaOH, KOH, and Ca(OH)2, and may be introduced into the reactor in the form of a solution in which the compound is dissolved in a solvent. At this time, the solvent may be water, or a mixture of water and an organic solvent (specifically, alcohol, etc.) that can be uniformly mixed with water.

[0106] When a complex transition metal aqueous solution, an ammonium cation complex forming agent, and a basic compound are introduced into a reactor as described above, precursor particles in the form of a complex transition metal hydroxide are generated due to a coprecipitation reaction between the transition metal ions in the complex transition metal aqueous solution and the hydroxide ions of the basic compound.

[0107] The above coprecipitation reaction can be carried out for 24 to 80 hours. When the coprecipitation reaction is carried out for a time within the above range, the crystallinity of the precursor particles can be controlled to a sufficient degree.

[0108] At this time, the basic compound can be added in an amount such that the pH of the reaction solution becomes within the desired range.

[0109] Once precursor particles are formed using the above method, the particles are separated from the reaction solution to obtain a composite transition metal. Specifically, the reaction solution is filtered to separate the particles, and then the separated particles are washed and dried to obtain a composite transition metal. At this time, processes such as grinding and / or classification may also be performed, as needed.

[0110] The above complex transition metal hydroxide is Ni p Mn q M 2 r (OH)2(M above 2 is at least one selected from Al, P, V, Y, Ti and Nb, and the p, q and r are 0. <p<0.5, 0.5≤q<1.0, 0≤r<0.005이다.)로 표시되는 조성을 가질 수 있다.

[0111] Additionally, the composite transition metal hydroxide may not contain cobalt (Co). In this case, cost savings are achieved and the performance of a lithium secondary battery can be improved without including cobalt in the composite transition metal hydroxide.

[0112]

[0113] The above lithium (Li)-containing raw material may be at least one selected from the group consisting of LiOH, Li2CO3, LiNO3, LiNO2, LiOHㆍH2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li acetate, Li dicarboxylic acid, Li citrate, Li fatty acid, alkyl lithium, and lithium halides, and a mixture of one or two or more of these may be used. Specifically, when calcination at high temperature is taken into consideration, LiOH may be used.

[0114] The above tungsten (W) containing raw materials are WO3, WC, WS2 and C8H 16 At least one selected from the group consisting of O8W may be used, and a mixture of one or more of these may be used. Specifically, WO3 may be used considering economic feasibility, the amount of gas generated during heat treatment, and the heat treatment temperature.

[0115]

[0116] According to one embodiment of the present invention, the tungsten (W)-containing raw material may be mixed in an amount of 1,000 ppm or more, 1,500 ppm or more, 5,000 ppm or more, or 10,000 ppm or more, and 15,000 ppm or less, 16,000 ppm or less, or 17,000 ppm or less, based on the total weight of the composite transition metal hydroxide. When the mixing amount of the tungsten (W)-containing raw material is within the above range, the capacity characteristics, efficiency characteristics, and output characteristics of the positive electrode active material can be improved.

[0117]

[0118] According to the present invention, in the step (A), a composite transition metal hydroxide containing nickel and manganese but not containing cobalt, a lithium (Li)-containing raw material, and a tungsten (W)-containing raw material can be mixed in an amount such that the composition is represented by the chemical formula 1 or chemical formula 2.

[0119]

[0120] (B) Step

[0121] Thereafter, the step (B) of heat-treating the mixture to produce a lithium-excess manganese oxide according to the present invention described above is included.

[0122]

[0123] When the above mixture is heat-treated, the composite transition metal hydroxide, the lithium (Li)-containing raw material, and the tungsten (W)-containing raw material react to produce a lithium-excess manganese oxide according to the present invention. Specifically, a lithium-excess manganese oxide containing both a Li2MnO3 phase and a LiMO2 (wherein M is an element including Ni, Mn, or a combination thereof) phase and having a composition represented by the following chemical formula 1 is produced.

[0124] [Chemical Formula 1]

[0125] Li 1+x Ni a Mn b W c M 1 d O2

[0126] In the above chemical formula 1,

[0127] M 1 is at least one selected from Al, P, V, Y, Ti and Nb,

[0128] 0.10≤x≤0.20, 0 <a<0.5, 0.5≤b<1.0, 0<c<0.008, 0≤d<0.005이다.

[0129]

[0130] The above heat treatment may be performed at a temperature of 600°C or higher, 700°C or higher, 750°C or higher, or 800°C or higher, and 900°C or lower, 950°C or lower, 975°C or lower, or 1,000°C or lower. When the heat treatment temperature is within the above range, sufficient heat energy required for doping can be supplied. When the heat treatment is performed at less than 600°C, sufficient heat energy required for doping cannot be supplied, and when it is performed at more than 1,000°C, there is a problem that the crystal size increases due to oversintering, thereby lowering the capacity characteristics of the lithium-excess manganese oxide.

[0131]

[0132] According to one embodiment of the present invention, the heat treatment can be performed under an air atmosphere. This facilitates the maintenance of the sintering atmosphere and is advantageous from an economic perspective. The heat treatment can be maintained at a constant temperature for 6 to 15 hours. This provides sufficient thermal energy for doping, enabling the production of a positive electrode active material free of impurities and with high crystallinity.

[0133]

[0134] anode

[0135] Next, the anode according to the present invention will be described.

[0136]

[0137] The positive electrode according to the present invention comprises a positive electrode active material layer comprising the positive electrode active material according to the present invention. Specifically, the positive electrode comprises a positive electrode current collector and a positive electrode active material layer formed on the positive electrode current collector, and comprising the positive electrode active material. Since the positive electrode active material has been described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0138]

[0139] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change 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 positive electrode current collector may typically have a thickness of 3 µm to 500 µm, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesive strength of the positive electrode active material. For example, the positive electrode current collector may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0140]

[0141] The above-mentioned positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material. In this case, the positive electrode active material may be included in an amount of 80 wt% to 99 wt%, more specifically 85 wt% to 98.5 wt%, based on the total weight of the positive electrode active material layer, and excellent capacity characteristics may be exhibited within this range.

[0142]

[0143] The conductive material is used to provide conductivity to the electrode, and in the battery to be formed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. 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, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and 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 the like. One of these may be used alone or a mixture of two or more may be used. The conductive material may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0144]

[0145] The above binder serves to improve the adhesion between positive electrode active material particles and the adhesive strength between the positive electrode active material and the current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene butadiene rubber (SBR), fluoroelastomer, or various copolymers thereof, and one of these may be used alone or a mixture of two or more thereof. The binder may be included in an amount of 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0146]

[0147] The positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the positive electrode active material described above is used. Specifically, the positive electrode can be manufactured by coating a composition for forming a positive electrode active material layer, which is manufactured by dissolving or dispersing the positive electrode active material and optionally a binder and a conductive material in a solvent, on a positive electrode current collector, followed by drying and rolling. At this time, the types and contents of the positive electrode active material, binder, and conductive material are as described above. Alternatively, the positive electrode can be manufactured by casting the composition for forming a positive electrode active material layer on a separate support, and then laminating the film obtained by peeling it from the support on a positive electrode current collector.

[0148]

[0149] The solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, taking into account the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0150]

[0151] lithium secondary battery

[0152] Next, a lithium secondary battery according to the present invention will be described.

[0153]

[0154] The present invention can manufacture an electrochemical device including the above-described positive electrode. The electrochemical device may be, specifically, a battery, a capacitor, or the like, and more specifically, a lithium secondary battery.

[0155]

[0156] The lithium secondary battery specifically includes a positive electrode, a negative electrode positioned opposite the positive electrode, and a separator and electrolyte interposed between the positive electrode and the negative electrode. Since the positive electrode is the same as described above, a detailed description thereof will be omitted, and only the remaining components will be described in detail below.

[0157]

[0158] In addition, the lithium secondary battery may optionally further include a battery container that houses the electrode assembly of the positive electrode, the negative electrode, and the separator, and a sealing member that seals the battery container.

[0159]

[0160] In the above lithium secondary battery, the negative electrode includes a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0161] The negative electrode 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., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 ㎛ to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0162]

[0163] The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0164]

[0165] As the 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 alloy, Sn alloy, or Al alloy; SiO β(0<β<2), SnO2, vanadium oxide, lithium vanadium oxide, and other metal oxides capable of doping and dedoping lithium; or composites containing the above metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical, or fiber-like forms, 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.

[0166] The above negative electrode active material may be included in an amount of 80% to 99% by weight based on the total weight of the negative electrode active material layer.

[0167]

[0168] The above binder is a component that assists in bonding between the conductive material, the active material, and the current collector, and can typically be added in an amount of 0.1 wt% to 10 wt% based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0169]

[0170] The conductive agent is a component for further improving the conductivity of the negative electrode active material, and may be added in an amount of 10 wt% or less, specifically, 5 wt% or less, based on the total weight of the negative electrode active material layer. The conductive agent is not particularly limited as long as it has conductivity and does not cause a chemical change in the battery, and examples thereof include graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal black; conductive fibers such as carbon fiber or metal fiber; metal powders such as fluorocarbon, aluminum, and nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; and conductive materials such as polyphenylene derivatives.

[0171]

[0172] The 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, on a negative electrode current collector, or by casting the composition for forming a negative electrode active material layer on a separate support, and then laminating the film obtained by peeling it off from the support on a negative electrode current collector.

[0173]

[0174] Meanwhile, in the lithium secondary battery, the separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used in lithium secondary batteries can be used without special restrictions, and in particular, one having low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, can be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. can also be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength can be used, and can optionally be used in a single-layer or multi-layer structure.

[0175]

[0176] In addition, examples of the electrolyte used in the present invention include, but are not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0177] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0178] As the organic solvent, any solvent that can serve as a medium through which ions involved in the electrochemical reaction of the battery can move may be used without particular limitation. Specifically, the organic solvent includes ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); Alcohol solvents such as ethyl alcohol, isopropyl alcohol, etc.; nitriles such as R-CN (R is a linear, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes, etc. can be used. Among these, carbonate solvents are preferable, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of a battery and a low-viscosity linear carbonate compound (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate) is more preferable.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0179]

[0180] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, 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 is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0181]

[0182] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexaphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additive may be included in an amount of 0.1 to 10 wt%, specifically, 0.1 to 5 wt%, based on the total weight of the electrolyte.

[0183]

[0184] As described above, a lithium secondary battery including a cathode active material according to the present invention exhibits excellent life characteristics and capacity characteristics, and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0185] Accordingly, according to another embodiment of the present invention, a battery module including the lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0186] The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0187] There is no particular limitation on the external shape of the lithium secondary battery of the present invention, but it may be a cylindrical shape using a can, a square shape, a pouch shape, or a coin shape.

[0188] 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 be preferably used as a unit battery in a medium- to large-sized battery module including a plurality of battery cells.

[0189]

[0190] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0191]

[0192] Examples and Comparative Examples

[0193] Example 1

[0194] LiOH, Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 10μm) and WO3 were mixed so that the molar ratio of Li:(Ni+Mn):W was 1.30:1:0.001. The mixture was heat-treated at a temperature of 800 to 1,000°C for 10 hours in an air atmosphere to produce a cathode active material (lithium-excess manganese oxide). At this time, the WO3 was mixed with the Ni 0.35 Mn 0.65 (OH)2 was mixed in an amount of 1,300 ppm based on the total weight.

[0195] Example 2

[0196] LiOH, Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 10μm) and WO3 A positive electrode active material (lithium-excess manganese oxide) was manufactured in the same manner as in Example 1, except that a mixture was used in which the molar ratio of Li:(Ni+Mn):W was 1.30:1:0.003. At this time, the WO3 was the Ni 0.35 Mn 0.65 (OH)2 was mixed in an amount of 5,200 ppm based on the total weight.

[0197] Example 3

[0198] LiOH, Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 10μm) and WO3 A positive electrode active material (lithium-excess manganese oxide) was manufactured in the same manner as in Example 1, except that a mixture was used in which the molar ratio of Li:(Ni+Mn):W was 1.30:1:0.005. At this time, the WO3 was the Ni 0.35 Mn 0.65 (OH)2 was mixed in an amount of 10,400 ppm based on the total weight.

[0199] Example 4

[0200] LiOH, Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 10μm) and WO3 A positive electrode active material (lithium-excess manganese oxide) was manufactured in the same manner as in Example 1, except that a mixture was used in which the molar ratio of Li:(Ni+Mn):W was 1.30:1:0.008. At this time, the WO3 was the Ni 0.35 Mn 0.65 (OH)2 was mixed in an amount of 15,600 ppm based on the total weight.

[0201] Example 5

[0202] LiOH, Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 3μm) and WO3 were mixed so that the molar ratio of Li:(Ni+Mn):W was 1.30:1:0.005, and a positive electrode active material (lithium-excess manganese oxide) was manufactured in the same manner as in Example 1. In this case, the WO3 was the Ni 0.35 Mn 0.65 (OH)2 was mixed in an amount of 10,400 ppm based on the total weight.

[0203] Comparative Example 1

[0204] LiOH and Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 10μm) was used so that the molar ratio of Li:(Ni+Mn) was 1.30:1, and a positive electrode active material (lithium-excess manganese oxide) was manufactured in the same manner as in Example 1.

[0205] Comparative Example 2

[0206] LiOH, Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 10μm) and WO3 were mixed so that the molar ratio of Li:(Ni+Mn):W was 1.30:1:0.009, and a positive electrode active material (lithium-excess manganese oxide) was manufactured in the same manner as in Example 1. In this case, the WO3 was the Ni 0.35 Mn 0.65 (OH)2 was mixed in an amount of 18,200 ppm based on the total weight.

[0207] Comparative Example 3

[0208] LiOH, Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 10μm), Co(OH)2 and WO3 were mixed so that the molar ratio of Li:(Ni+Mn):Co:W was 1.30:1:0.05:0.005, and the positive electrode active material (lithium-excess manganese oxide) was manufactured in the same manner as in Example 1, except that the WO3 was mixed with the Ni 0.35 Mn 0.65 (OH)2 was mixed in an amount of 10,400 ppm based on the total weight.

[0209] Comparative Example 4

[0210] LiOH, Ni 0.35 Mn 0.65 (OH)2 (Product name: Nickel manganese hydroxide, Manufacturer: Huayou, D 50 : 10μm), Co(OH)2 and WO3 were mixed so that the molar ratio of Li:(Ni+Mn):Co:W was 1.30:1:0.05:0.009, and the positive electrode active material (lithium-excess manganese oxide) was manufactured in the same manner as in Example 1, except that the WO3 was mixed with the Ni 0.35 Mn 0.65 (OH)2 was mixed in an amount of 18,200 ppm based on the total weight.

[0211]

[0212] Experimental example

[0213] Experimental Example 1: XRD Analysis

[0214] For each of the positive electrode active materials manufactured in Examples 1 to 5, after XRD measurement, the XRD data is shown in Fig. 1. In addition, for each of the positive electrode active materials manufactured in Comparative Examples 1 to 4, after XRD measurement, the XRD data is shown in Fig. 2.

[0215] At this time, the XRD was measured by collecting 2g to 3g of positive electrode active material particles from each positive electrode active material powder, and using Cu-Kα rays (wavelength 1.54 Å), at an acceleration voltage of 40 kV / 40 mA, at a scan speed of 0.2° / sec, in a 2θ range of 15° to 80° using an X-ray diffraction analysis method.

[0216] Through Fig. 1, it was confirmed that the positive electrode active materials manufactured in Examples 1 to 5 simultaneously contained two phases. Specifically, it was confirmed that the Li2MnO3 phase was included as a small peak existing at 20° to 25°, and the LiMO2 phase (wherein M is an element including Ni, Mn, or a combination thereof) was simultaneously included as a large peak existing at 18°.

[0217] Through FIG. 2, in the case of the positive electrode active material manufactured in Comparative Example 1, which was not doped with W, it was confirmed that it had the same peaks as the Example at 20° to 25° and 18°, and that it simultaneously contained a Li2MnO3 phase and a LiMO2 (wherein M is an element including Ni, Mn, or a combination thereof) phase. On the other hand, in the case of the positive electrode active material manufactured in Comparative Example 2, which was doped with an excessive amount of W, an additional peak expected to be an impurity was confirmed at 20° to 40°, and it was confirmed that the peak pattern was different from the Example. In the case of the positive electrode active material manufactured in Comparative Example 3, which was additionally doped with Co, separate peaks were confirmed at around 23°, 38°, 45°, and 58° compared to the Example and Comparative Example 1, and it was confirmed that the peak pattern was different overall. In the case of Comparative Example 4, in which Co was additionally doped and W was excessively doped, it was confirmed that the peak pattern was similar to that of Comparative Example 3 at 20° to 35°, and that the peak pattern was similar to that of Comparative Example 2 at 35° to 60°.

[0218] In conclusion, it was confirmed that the positive electrode active material according to the present invention simultaneously includes a Li2MnO3 phase and a LiMO2 phase (wherein M is an element including Ni, Mn, or a combination thereof), and when W is doped in excess (Comparative Example 2) or Co is additionally doped (Comparative Examples 3 and 4), it was confirmed that it has a different crystal structure from the positive electrode active material according to the present invention due to the excess W and / or Co.

[0219]

[0220] Experimental Example 2: ICP Analysis

[0221] Each of the positive electrode active materials manufactured in Examples 1 to 5 and Comparative Examples 1 to 4 was taken in an amount of 0.1 g, 1 ml of hydrochloric acid was added, and heated to dissolve the positive electrode active material. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction, completely dissolving the positive electrode active material to prepare a solution. Next, the solution was diluted with deionized water to a total volume of 10 ml to prepare an analysis sample. Using an ICP device (Perkin Elmer, OPTIMA 7300DV), the weight ratio of the constituent elements present in the analysis sample was measured, and the composition of the positive electrode active material, the content of W (ppm) and the content of Co (ppm) with respect to the total weight of the lithium-excess manganese oxide are shown in Table 1 below.

[0222]

[0223] Cathode active material composition W content (ppm) Co content (ppm) Example 1 Li 1.145 Ni 0.306 Mn 0.567 W 0.001 O21,101-Example 2Li 1.140 Ni 0.307 Mn 0.569 W 0.002 O24,348-Example 3Li 1.150 Ni 0.304 Mn 0.562 W 0.004 O28,616-Example 4Li 1.145 Ni 0.305 Mn 0.563 W 0.006 O213,010-Example 5Li 1.150 Ni 0.313 Mn 0.553 W 0.004 O28,810 Comparative Example 1Li 1.140 Ni 0.316 Mn 0.561 O2--Comparative example 2Li 1.140 Ni 0.315 Mn 0.553 W 0.008 O217,800-Comparative Example 3Li 1.140 Ni0.304 Co 0.035 Mn 0.531 W 0.004 O28,42022,760Comparative example 4Li 1.140 Ni 0.302 Co 0.037 Mn 0.530 W 0.008 O216,43024,140

[0224] Through Table 1, it was confirmed that the content of W in the positive electrode active materials manufactured in Examples 1 to 5 was 1,101 ppm to 13,010 ppm with respect to the total weight of the lithium-excess manganese oxide.

[0225] Experimental Example 3: Measurement of tap density and average particle size

[0226] 10 g of each of the positive electrode active materials manufactured in Examples 1 to 5 above was measured at a tap density measuring device (e.g., GEOPYC-1360 from Micromeritics) at a distance of about 20 cm 3 The tap density was measured by filling the container with 108 N, pressurizing the container, measuring the density of the particles twice, and calculating the average of the measured values, and the results are shown in Table 2 below.

[0227] In order to measure the average particle size of each of the positive electrode active material particles manufactured in Examples 1 to 5, the particle size of the positive electrode active material was measured using PSA (Microtrac, S3500), and the results are shown in Table 2 below.

[0228] Density of the tab (g / cm) 3 )Average particle diameter (D) 50 )(㎛)Example 12.189.59Example 22.189.53Example 32.209.57Example 42.189.53Example 52.173.82

[0229] Through Table 2, each of the positive electrode active materials manufactured in Examples 1 to 5 had a tap density of 2.17 g / cm 3 2.20g / cm 3 and the average particle diameter (D 50) was confirmed to be 3.82㎛ to 9.59㎛.

[0230] Experimental Example 4: Morphological Analysis

[0231] For the positive electrode active material manufactured in Example 1, an SEM image was obtained using a scanning electron microscope (SEM), and is shown in Fig. 3.

[0232] Through Figure 3, it was confirmed that the positive electrode active material manufactured in Example 1 was in the form of secondary particles formed by agglomeration of multiple primary particles.

[0233]

[0234] Experimental Example 5: Battery Characteristics Evaluation

[0235] Coin-type half-cell manufacturing

[0236] A positive electrode slurry was prepared by mixing 92.5 wt% of each of the positive electrode active materials manufactured in Examples 1 to 5 and Comparative Examples 1 to 4, 3.0 wt% of Super P as a conductive agent, and 4.5 wt% of polyvinylidene fluoride (PVDF) as a binder in an N-methylpyrrolidone (NMP) solvent. The prepared positive electrode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and then rolled to prepare a positive electrode.

[0237] An electrode assembly was manufactured using a lithium metal electrode as the negative electrode and a porous polyethylene separator interposed between the positive and negative electrodes. This was placed inside a battery case and an electrolyte solution containing 1 M LiPF6 dissolved in an organic solvent of ethylene carbonate (EC) and ethyl methyl carbonate (EMC) in a volume ratio of 3:7 was injected to manufacture a coin-type half-cell.

[0238] Evaluation of battery capacity characteristics

[0239] Coin-type half-cells containing each of the positive electrode active materials manufactured in Examples 1 to 5 and Comparative Examples 1 to 4 were charged (0.1C) in a CC-CV manner at 45°C to 4.65 V, and then discharged (0.1C) in a CC manner to 2.0 V to perform an activation process (formation), and the charge and discharge capacities at this time were measured. The measured charge and discharge capacities and the percentage of discharge capacity to charge capacity (efficiency (%)) are shown in Table 3 below.

[0240] Next, the initial charge-discharge process was performed by charging (0.1C) to 4.4 V at 25°C using the CC-CV method, and then discharging (0.1C) to 2.5 V using the CC method, and the charge and discharge capacities at this time were measured. The measured charge and discharge capacities and the percentage of discharge capacity to charge capacity (efficiency (%)) are shown in Table 3 below.

[0241] After charging (0.33C) to 4.4 V at 25°C using the CC-CV method, the initial charge-discharge process was performed by discharging (0.33C) to 2.5 V using the CC method, and the charge and discharge capacities at this time were measured. The measured charge and discharge capacities and the percentage of discharge capacity to charge capacity (efficiency (%)) are shown in Table 3 below.

[0242] Differential activation process @ 45℃ First cycle charge and discharge @ 0.1C First cycle charge and discharge @ 0.33C 0.33C / 0.1C (%) Charge capacity (mAh / g) Discharge capacity (mAh / g) Efficiency (%) Charge capacity (mAh / g) Discharge capacity (mAh / g) Efficiency (%) Charge capacity (mAh / g) Discharge capacity (mAh / g) Efficiency (%) Example 1 294.5 272.192.4 223.3 211.3 94.6 210.1 197.193.8 93.3 Example 2 291.7 270.5 92.7 221.9 211.195.1 209.7 197.9 94.3 93.7 Example 3291.3271.093.0221.6211.795.5210.0199.995.294.4Example 4290.4263.590.7213.0205.196.3202.9195.396.395.2Example 5299.1274.992.0226.7213.994.3212.1199.994.393.5Comparative Example 1295.9272.992.2227.6212.493.3211.1194.492.191.5Comparative Example 2230.6177.577.0130.4116.289.1115.690.878.578.1Comparative example 3271.5234.386.3190.0181.895.7179.3165.592.391.0Comparative example 4260.6205.478.8159.0147.192.5144.6125.086.485.0

[0243] As shown in Table 3, in the case of the battery including the positive electrode active material manufactured in the Examples, the activation process, charge / discharge capacities at 0.1 C and 0.33 C were maintained at similar levels, and the efficiency and rate characteristics were improved compared to the battery including the positive electrode active material manufactured in Comparative Example 1 in which W was not doped. In the case of the battery including the positive electrode active material manufactured in the Examples, the activation process, charge / discharge capacities at 0.1 C and 0.33 C were very excellent, and the efficiency and rate characteristics were very excellent. In the case of the battery including the positive electrode active material manufactured in Comparative Examples 3 and 4 in which Co was additionally doped, the activation process, charge / discharge capacities at 0.1 C and 0.33 C, and the efficiency of the activation process were very excellent, and the efficiency and rate characteristics at 0.1 C and 0.33 C were improved.

[0244] In conclusion, it can be seen that the cathode active material according to the present invention not only effectively increases the activation degree of Mn, resulting in less irreversible capacity loss during the activation process, but also is stable with little structural change during charge / discharge cycles.

Claims

1. A lithium-excess manganese oxide containing both Li2MnO3 phase and LiMO2 (wherein M is an element including Ni, Mn or a combination thereof) phase, The above lithium-excess manganese oxide is a positive electrode active material having a composition represented by the following chemical formula 1: [Chemical Formula 1] Li 1+x Ni a Mr b W c M 1 d O2 In the above chemical formula 1, M 1 is at least one selected from Al, P, V, Y, Ti and Nb, 0.10≤x≤0.20, 0 <a<0.5, 0.5≤b<1.0, 0<c<0.008, 0≤d<0.005이다.

2. In claim 1, The above a is a positive electrode active material having a value of 0.30 to 0.

35.

3. In claim 1, The above b is a positive electrode active material having a value of 0.55 to 0.

60.

4. In claim 1, The above c is a positive electrode active material of 0.0005 to 0.

007.

5. In claim 1, A cathode active material having a content of W of 800 ppm to 15,000 ppm based on the total weight of the lithium-excess manganese oxide.

6. In claim 1, The above lithium-excess manganese oxide has a tap density of 1.5 g / cm 3 2.5g / cm 3 The positive electrode active material.

7. In claim 1, The above lithium-excess manganese oxide has an average particle diameter (D 50 ) is a positive electrode active material having a diameter of 2㎛ to 12㎛. 8.(A) A step of preparing a mixture by mixing a composite transition metal hydroxide, a lithium (Li)-containing raw material, and a tungsten (W)-containing raw material; and (B) a step of heat-treating the mixture to produce a lithium-excess manganese oxide; A method for producing a positive electrode active material according to claim 1, wherein the heat treatment is performed at a temperature of 600°C to 1,000°C.

9. In claim 8, A method for producing a cathode active material, wherein the tungsten (W)-containing raw material is mixed in an amount of 1,000 ppm to 17,000 ppm based on the total weight of the composite transition metal hydroxide.

10. In claim 8, A method for manufacturing a positive electrode active material, wherein the heat treatment in the above step (B) is performed under an air atmosphere.

11. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 7.

12. A lithium secondary battery comprising a positive electrode according to claim 11.

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