Cathode active material, method for preparing same, and cathode and lithium secondary battery each comprising same

Abstract

The present invention relates to a cathode active material, a method for preparing same, and a cathode and a lithium secondary battery each comprising same, wherein the cathode active material comprises: a lithium-rich manganese-based oxide including both a Li2MnO3 phase and a LiM'O2 phase (where, M' is an element including at least one selected from Ni and Mn); and a coating part formed on the lithium-rich manganese-based oxide, the lithium-rich manganese-based oxide containing at least two doping elements (Q) selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt, the coating part containing at least one coating element (R) selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni, and satisfies formula 1 described in the present specification.

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. 10-2024-0005034, filed January 11, 2024, 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] Lithium-rich layered oxide, a type of cathode active material, is a mixed phase of Li2MnO3 phase and LiM'O2 (where M' is an element including at least one selected from Ni, Mn, and Co) 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, there are problems such as voltage fading, increased resistance, and generation of O2 gas as the layered structure changes to a spinel structure and then to a rock salt structure.

[0009] Additionally, the rising price of cobalt, a raw material that can be included 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, it is necessary to secure technology to improve the capacity characteristics, resistance characteristics, life characteristics, and economic feasibility of the lithium-excess oxide.

[0011]

[0012] [Prior Art Literature]

[0013] [Patent Document]

[0014] (Patent Document 1) Korean Patent Publication No. 10-2003-088247

[0015]

[0016] The present invention is intended to solve the above problems, and to provide a positive electrode active material and a method for manufacturing the same that can improve the capacity 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, 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 LiM'O2 (wherein M' is an element including at least one selected from Ni and Mn) phase; and a coating formed on the lithium-excess manganese oxide; wherein the lithium-excess manganese oxide includes two or more doping elements (Q) selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt, and the coating includes one or more coating elements (R) selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni, and satisfies the following formula 1.

[0020] [Formula 1]

[0021] (Oxidation number of R) < (sum of oxidation numbers of Q).

[0022] (2) The present invention provides a positive electrode active material in the above (1), wherein the lithium-excess manganese oxide has a composition represented by the following chemical formula 1 or chemical formula 2.

[0023] [Chemical Formula 1]

[0024] Li 1+x Mn a1 Ni b1 Q c1 O2

[0025] In the above chemical formula 1,

[0026] Q is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na and Pt,

[0027] 0.000 <x≤0.200, 0.500≤a1<1.000, 0.200≤b1<0.500, 0.0000<c1≤0.0300이고,

[0028] [Chemical Formula 2]

[0029] αLi2Mn 1-c2 Qc2 O3·βLi(Mn a2 Ni b2 Q c3 )O2

[0030] In the above chemical formula 2,

[0031] Q is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na and Pt,

[0032] 0<α<1, 0<β<1, 0.0000≤c2≤0.0100, 0.000 <a2≤0.500, 0.000<b2≤0.500 0.0000≤c3≤0.0100, a2+b2+c3=1.000이고, c2+c3> It's 0.0000.

[0033] (3) The present invention provides a positive electrode active material in (1) or (2) above, wherein the content of the doping element (Q) is 500 ppm or more and 13,000 ppm or less based on the total weight of the lithium-excess manganese oxide.

[0034] (4) The present invention provides a positive electrode active material in any one of the above (1) to (3), wherein the shape of the coating portion is a film type, an island type, or a combination thereof.

[0035] (5) The present invention, in any one of the above (1) to (4), wherein the coating part comprises R, RO compound, Li-RO compound and Li-M'-RO A positive electrode active material is provided, which comprises at least one selected from compounds.

[0036] (6) The present invention provides a positive electrode active material in any one of the above (1) to (5), wherein the content of the coating part is 0.05 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the lithium-excess manganese oxide.

[0037] (7) The present invention provides a positive electrode active material in which the content of the coating element (R) included in the coating portion is 300 ppm or more and 4,000 ppm or less based on the total weight of the lithium-excess manganese oxide in any one of the above (1) to (6).

[0038] (8) The present invention provides a positive electrode active material in any one of the above (1) to (7), wherein the oxidation number of Q is 3 or more and 6 or less.

[0039] (9) The present invention provides a positive electrode active material in any one of the above (1) to (8), wherein Q is two or more selected from W, Al, Zr, Ti, Mo, and Co, and R is one or more selected from Zn, Al, Co, Ti, Nb, V, Mo, and W.

[0040] (10) The present invention relates to any one of the above (1) to (9), wherein the average particle diameter (D 50 ) provides a positive electrode active material having a size of 4㎛ or more and 12㎛ or less.

[0041] (11) (A) a step of preparing a mixture by mixing a composite transition metal hydroxide, a lithium (Li)-containing raw material, and a doping element (Q)-containing raw material; (B) a step of preparing a lithium-excess manganese oxide by calcining the mixture; And (C) a step of mixing the lithium-excess manganese oxide and the raw material containing the coating element (R) and then heat-treating the mixture to form a coating portion; wherein the firing is performed in an air atmosphere at a temperature of 800°C or higher and 1,000°C or lower, the doping element (Q) is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt, the coating element (R) is one or more selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni, and the doping element (Q) and the coating element (R) satisfy the following formula 1.

[0042] [Formula 1]

[0043] (Oxidation number of R) < (sum of oxidation numbers of Q).

[0044] (12) The present invention provides a method for producing a positive electrode active material, wherein, in the above (11), the raw material containing the doping element (Q) is at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides, and halides containing the doping element (Q).

[0045] (13) The present invention provides a method for producing a positive electrode active material, wherein, in the above (11) or (12), the raw material containing the doping element (Q) is mixed so that the content of the doping element (Q) is 500 ppm or more and 13,500 ppm or less with respect to the total weight of the composite transition metal hydroxide.

[0046] (14) The present invention provides a method for producing a positive electrode active material, wherein the raw material containing the coating element (R) in any one of the above (11) to (13) is at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides, and halides containing the coating element (R).

[0047] (15) The present invention provides a method for producing a positive electrode active material, wherein the raw material containing the coating element (R) is mixed in such a way that the coating element (R) content is 300 ppm or more and 5,000 ppm or less based on the total weight of the lithium-excess manganese oxide in any one of the above (11) to (14).

[0048] (16) The present invention provides a method for manufacturing a positive electrode active material, wherein the heat treatment is performed at a temperature of 400°C or higher and 700°C or lower in any one of the above (11) to (15).

[0049] (17) The present invention provides a positive electrode comprising a positive electrode active material according to any one of (1) to (10).

[0050] (18) The present invention provides a lithium secondary battery including a positive electrode according to (17) above.

[0051]

[0052] The cathode active material of the present invention comprises a lithium-excess manganese oxide including a Li2MnO3 phase and a LiM'O2 (wherein M' is an element including at least one selected from Ni and Mn) phase at the same time, and including two or more doping elements (Q) selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt; and a coating portion including a coating element (R) formed on the lithium-excess manganese oxide; wherein the oxidation number of the coating element (R) is smaller than the sum of the oxidation numbers of the doping elements (Q), so that the lithium-excess manganese oxide including the doping element (Q) attracts electrons from the coating portion including the coating element (R), thereby reducing the electron density on the surface of the coating portion. And, the coating part containing the coating element (R) attracts oxygen from the lithium-excess manganese oxide containing the doping element (Q), thereby changing the oxidation number of manganese bonded with oxygen. Among them, Mn, which is structurally stable but redox-inactive 4+ The oxidation number of the lithium-excess manganese oxide decreases, making it electrochemically active. As a result, the lithium storage capacity of the lithium-excess manganese oxide is improved, and the ionic conductivity of the positive electrode active material is improved due to the coating formed on the lithium-excess manganese oxide, while the coating does not interfere with the insertion and deintercalation reaction of lithium ions, thereby promoting the movement of lithium ions. Accordingly, there is an effect of improving the capacity characteristics of the positive electrode and secondary battery including the positive electrode active material, and there is an effect of reducing costs.

[0053] 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.

[0054]

[0055] Figure 1 shows XRD data of the positive electrode active materials manufactured in Examples 1 to 12.

[0056] Figure 2 shows XRD data of the positive electrode active materials manufactured in Comparative Examples 1 to 5.

[0057] Figure 3 is an EPMA cobalt element mapping image of a cross-section of a positive electrode including a positive electrode active material manufactured in Example 1.

[0058]

[0059] Hereinafter, the present invention will be described in more detail to help understand the present invention.

[0060] 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 spirit 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 possible manner.

[0061] In this specification, it should be understood that terms such as “include,” “have,” or “have” 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.

[0062] In this specification, the term 'on' means not only when a configuration is formed directly on the top surface of another configuration, but also when a third configuration is interposed between these configurations.

[0063] In this specification, the content of each element in the lithium-excess manganese oxide may be measured through ICP (Inductive Coupled Plasma) analysis using an inductively coupled plasma optical emission spectrometer (ICP-OES; Optima 7300DV, PerkinElmer).

[0064] 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.

[0065]

[0066] positive electrode active material

[0067] Hereinafter, the positive electrode active material according to the present invention will be described.

[0068]

[0069] The cathode active material according to the present invention comprises a lithium-excess manganese oxide including both a Li2MnO3 phase and a LiM'O2 (wherein M' is an element including at least one selected from Ni and Mn) phase; and a coating formed on the lithium-excess manganese oxide; wherein the lithium-excess manganese oxide includes two or more doping elements (Q) selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt, and the coating includes one or more coating elements (R) selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni, and satisfies the following formula 1.

[0070] [Formula 1]

[0071] (Oxidation number of R) < (sum of oxidation numbers of Q)

[0072] Lithium-rich layered oxide, a type of positive electrode active material, is a mixed phase in which Li2MnO3 phase and LiM'O2 phase (wherein M' is an element including at least one selected from Ni, Mn, and Co) phase are mixed, and there is a problem that a large irreversible capacity loss occurs during the activation process and a large structural change occurs during the charge / discharge cycle.

[0073] The present inventors have conducted repeated research to solve the above problem and have found that, in the case of a cathode active material that uses a lithium-excess manganese oxide that simultaneously includes a Li2MnO3 phase and a LiM'O2 (wherein M' is an element including at least one selected from Ni and Mn) phase, and the lithium-excess manganese oxide includes two or more doping elements (Q), forms a coating portion including a coating element (R) on the lithium-excess manganese oxide, and the oxidation number of the R is lower than the sum of the oxidation numbers of the Q, the coating portion including the coating element (R) attracts oxygen from the lithium-excess manganese oxide including the doping element (Q), thereby reducing the oxidation number of manganese in the lithium-excess manganese oxide. Specifically, in the lithium-excess manganese oxide, manganese is Mn 2+ / Mn 4+ It exists in the form of Mn 4+ In the case of Mn, it plays a role in supporting the crystal lattice. Therefore, there is no concern about structural changes such as Janteller distortion, and the battery capacity can be maintained for a long time. However, there is a problem that it has almost no electrochemical activity and very low electrical conductivity. 2+In this case, it is electrochemically active, but structurally unstable and has a problem of being eluted. In the case of a positive electrode active material in which the oxidation number of the above R is smaller than the sum of the oxidation numbers of the above Q, the coating part including the coating element (R) attracts oxygen from the lithium-excess manganese oxide including the doping element (Q), and the oxidation number of manganese bonded with oxygen changes. Among them, Mn, which is structurally stable but redox inactive 4+ The oxidation number of manganese decreases and becomes electrochemically active. Then, the lithium-excess manganese oxide containing the doping element (Q) attracts electrons from the coating portion containing the coating element (R), so that the electron density on the surface of the coating portion decreases, and the coating portion does not interfere with the insertion and deintercalation reaction of lithium ions, thereby promoting the movement of lithium ions. As a result, the ion conductivity of the positive electrode active material is improved due to the coating portion formed on the lithium-excess manganese oxide, while the lithium storage capacity in the lithium-excess manganese oxide is improved. In addition, even if the oxidation number of manganese decreases, manganese ion elution and structural deformation do not occur, and a stable layered structure is maintained, and charge and discharge cycles can be performed. Accordingly, the inventors found out that the electrical conductivity of the positive electrode active material can be improved and the capacity characteristics of the secondary battery can be improved, and completed the present invention.

[0074]

[0075] The above Q is a doping element, and is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt. The doping element is an element having a molar fraction of 0.1 or less among metal elements excluding lithium in the lithium-excess manganese oxide, and refers to an element that exists evenly throughout the positive electrode active material particles. When the lithium-excess manganese oxide includes the doping element (Q), the doping element chemically combines with other elements in the lithium-excess manganese oxide to form a conductive path, thereby improving electrical conductivity. Specifically, the doping element includes a first doping element (Q1) and a second doping element (Q2). Since the doping element includes the first doping element (Q1) and the second doping element (Q2), there is an effect of increasing the mobility of lithium ions and strengthening oxygen stability. In addition, since the doping element includes a first doping element (Q1) and a second doping element (Q2) having different crystal sizes, there is an effect of reducing irreversible changes in the crystal structure during charge and discharge.

[0076] Meanwhile, when the doping element is one type or does not contain the doping element, there is a problem in that the structural stability is poor and an irreversible change in the crystal structure occurs during charging and discharging.

[0077] The above R is a coating element, and is at least one selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni. The coating element refers to an element that is concentrated in the outermost part of the positive electrode active material particle. Specifically, it refers to an element whose mole fraction is 0.5 or more at a depth of 0.5 nm from the outermost part of the positive electrode active material toward the center.

[0078] When the above coating portion includes the above coating element (R), the particle surface can be protected and stability can be improved, thereby improving capacity retention and life characteristics, and a material with good conductivity can be coated on the particle surface to improve electrical conductivity, thereby improving charge / discharge reaction and improving output characteristics.

[0079] The oxidation number of the above R is smaller than the sum of the oxidation numbers of Q. Specifically, the oxidation number of R is smaller than the sum of the oxidation numbers of the first doping element (Q1) and the second doping element (Q2).

[0080] When the above R is two or more, the sum of the oxidation numbers of R is less than the sum of the oxidation numbers of Q. Specifically, the sum of the oxidation numbers of Q is greater than the sum of the oxidation numbers of the first coating element (R1) and the second coating element (R2). When the oxidation number of R is greater than or equal to the sum of the oxidation numbers of Q, oxygen is attracted toward the lithium-excess manganese oxide containing Q, so that the oxidation number of manganese in the lithium-excess manganese oxide increases. As a result, the existing Mn 4+ The lithium-excess manganese oxide still exists in an electrochemically inactive state, and the coating formed on the lithium-excess manganese oxide hinders the insertion and deintercalation reaction of lithium ions, thereby reducing lithium ion mobility. As a result, there is a problem that the capacity and life characteristics of the positive electrode active material are deteriorated.

[0081]

[0082] According to one embodiment of the present invention, the lithium-excess manganese oxide may have a composition represented by the following chemical formula 1 or chemical formula 2.

[0083] [Chemical Formula 1]

[0084] Li 1+x Mn a1 Ni b1 Q c1 O2

[0085] In the above chemical formula 1,

[0086] Q is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na and Pt,

[0087] 0.000 <x≤0.200, 0.500≤a1<1.000, 0.200≤b1<0.500, 0.0000<c1≤0.0300이고,

[0088] [Chemical Formula 2]

[0089] αLi2Mn 1-c2 Q c2 O3·βLi(Mn a2 Ni b2 Q c3 )O2

[0090] In the above chemical formula 2,

[0091] Q is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na and Pt,

[0092] 0<α<1, 0<β<1, 0.0000≤c2≤0.0100, 0.000 <a2≤0.500, 0.000<b2≤0.500 0.0000≤c3≤0.0100, a2+b2+c3=1.000이고, c2+c3> It's 0.0000.

[0093] The above Q is a doping element, and may be two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt. Specifically, Q may include a first doping element (Q1) and a second doping element (Q2).

[0094] The above x may be greater than 0.000, greater than or equal to 0.130, greater than or equal to 0.131, or greater than or equal to 0.132, and may be less than or equal to 0.139, less than or equal to 0.150, less than or equal to 0.160, less than or equal to 0.170, less than or equal to 0.180, less than or equal to 0.190, or less than or equal to 0.200. When x satisfies the above range, the Li2MnO3 phase and the LiM'O2 phase are formed in an appropriate ratio, thereby realizing high-capacity characteristics.

[0095] The above a1 may be 0.500 or more, or 0.550 or more, and may be 0.600 or less, 0.700 or less, 0.800 or less, 0.900 or less, or less than 1.000. When b1 satisfies the above range, high energy density is exhibited, so that high-capacity characteristics can be realized. In particular, when a1 is 0.550 or more and 0.600 or less, Li2MnO3 phase and LiM'O2 phase are formed in an appropriate ratio, so that high-capacity characteristics can be realized.

[0096] The above b1 may be 0.200 or more, 0.250 or more, or 0.290 or more, and may be 0.300 or less, 0.350 or less, 0.400 or less, or less than 0.500. When b1 satisfies the above range, a high energy density may be exhibited, thereby realizing high-capacity characteristics.

[0097] The above c1 may be greater than 0.0000, or greater than 0.0050, and may be less than or equal to 0.0160, less than or equal to 0.0180, less than or equal to 0.0200, or less than or equal to 0.0300. When c1 satisfies the above range, the stability of the crystal structure of the positive electrode active material may be improved and the particle shape may be improved. In addition, when combined with a specific coating element, lithium mobility may be improved, thereby improving the capacity characteristics of the secondary battery.

[0098] The above α refers to the molar ratio of Li2MnO3 phase in the lithium-excess manganese oxide, and may be greater than 0, 0.2 or more, or 0.4 or more, and may be 0.6 or less, 0.8 or less, or less than 1. When α satisfies the above range, a high energy density per unit volume is exhibited, so that high-capacity characteristics can be realized. In addition, the capacity characteristics of a battery including a positive electrode active material can be further improved.

[0099] The above c2 may be 0.0000 or more, 0.0020 or more, 0.0040 or more, or 0.0060 or more, and may be 0.0080 or less, 0.0090 or less, or 0.0100 or less. When c2 satisfies the above range, the stability of the crystal structure of the positive electrode active material may be improved and the particle shape may be improved. In addition, when combined with a specific coating element, lithium mobility may be improved, thereby improving the capacity characteristics of the secondary battery.

[0100] The above β refers to the molar ratio of LiM'O2 in the lithium-excess manganese oxide, and may be greater than 0, 0.2 or more, or 0.4 or more, and may be 0.6 or less, 0.8 or less, or less than 1. When β satisfies the above range, a high energy density per unit volume is exhibited, so that high-capacity characteristics can be realized. In addition, the capacity characteristics of a battery including a positive electrode active material can be further improved.

[0101] The above a2 may be greater than 0.000, greater than 0.100, greater than 0.200, or greater than 0.300, and less than 0.400, or less than 0.500. When a2 satisfies the above range, high energy density is exhibited, thereby realizing high capacity characteristics.

[0102] The above b2 may be 0.000 or more, 0.100 or more, 0.200 or more, or 0.300 or more, and may be 0.400 or less, or 0.500 or less. When b2 satisfies the above range, a high energy density is exhibited, and high-capacity characteristics can be realized.

[0103] The above c3 may be 0.0000 or more, 0.0020 or more, 0.0040 or more, or 0.0060 or more, and 0.0080 or less, or 0.0100 or less. When c3 satisfies the above range, the stability of the crystal structure of the positive electrode active material may be improved and the particle shape may be improved. In addition, when combined with a specific coating element, lithium mobility may be improved, thereby improving the capacity characteristics of the secondary battery.

[0104] In the above chemical formula 2, a2, b2, and c3 may be a2+b2+c3=1.000, and c2 and c3 may be c2+c3>0.0000.

[0105]

[0106] The above lithium-excess manganese oxide may contain cobalt (Co) as a doping element (Q). In this case, cobalt (Co) may be contained in a trace amount in the lithium-excess manganese oxide.

[0107]

[0108] According to one embodiment of the present invention, the content of the doping element (Q) may be 500 ppm or more and 13,000 ppm or less based on the total weight of the lithium-excess manganese oxide. Specifically, the content of Q may be 500 ppm or more, 700 ppm or more, or 3,000 ppm or more, and 9,000 ppm or less, 10,000 ppm or less, 11,000 ppm or less, 12,000 ppm or less, or 13,000 ppm or less based on the total weight of the lithium-excess manganese oxide. When the content of Q is within the above range, the stability and electrical conductivity of the crystal structure of the positive electrode active material may be improved, thereby improving the capacity characteristics.

[0109]

[0110] According to one embodiment of the present invention, the shape of the coating portion may be a film type, an island type, or a combination thereof. The film type may be a continuous shape, and the island type may be a discontinuous shape. When the coating portion satisfies the above shapes, the mobility of lithium ions may be enhanced, thereby improving capacity characteristics.

[0111]

[0112] According to one embodiment of the present invention, the coating part comprises R, RO compound, Li-RO compound, Li-M'-RO It may include one or more selected from compounds. Specifically, when the component of the coating portion is R, the chemical composition of the coating portion is simple, resulting in high stability, and the electrical conductivity is high, so that the rate at which lithium ions pass through the coating portion increases, thereby improving the capacity characteristics and output characteristics of a secondary battery including a positive electrode active material.

[0113]

[0114] According to one embodiment of the present invention, the content of the coating portion may be 0.05 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the lithium-excess manganese oxide. Specifically, the content of the coating part may be 0.05 parts by weight or more, 0.06 parts by weight or more, 0.07 parts by weight or more, 0.08 parts by weight or more, 0.09 parts by weight or more, 0.1 parts by weight or more, 0.11 parts by weight or more, 0.12 parts by weight or more, 0.13 parts by weight or more, 0.14 parts by weight or more, 0.15 parts by weight or more, 0.16 parts by weight or more, 0.17 parts by weight or more, 0.18 parts by weight or more, 0.19 parts by weight or more, or 0.2 parts by weight or more, and 0.21 parts by weight or less, 0.22 parts by weight or less, 0.23 parts by weight or less, 0.24 parts by weight or less, 0.25 parts by weight or less, 0.26 parts by weight or less, 0.27 parts by weight or less, 0.28 parts by weight or less, It may be 0.29 parts by weight or less, or 0.3 parts by weight or less. When the content of the coating portion is within the above range, the structural stability and electrical conductivity of the positive electrode active material are improved without acting as a resistor, thereby improving the capacity characteristics.

[0115]

[0116] According to one embodiment of the present invention, the content of the coating element (R) included in the coating portion may be 300 ppm or more and 4,000 ppm or less based on the total weight of the lithium-excess manganese oxide. Specifically, the content of R included in the coating portion may be 300 ppm or more, 500 ppm or more, 750 ppm or more, 1,000 ppm or more, or 2,000 ppm or more, and may be 3,000 ppm or less, or 4,000 ppm or less based on the total weight of the lithium-excess manganese oxide. When the content of R is within the above range, the structural stability and electrical conductivity of the positive electrode active material are improved without acting as a resistor, so that the capacity characteristics can be improved.

[0117]

[0118] According to one embodiment of the present invention, the oxidation number of Q may be 3 or more and 6 or less. Specifically, the oxidation number of Q1 may be 6, and the oxidation number of Q2 may be 3 or more and 6 or less. When the oxidation number of Q is within the above range, an appropriate amount of charge capable of moving lithium ions in a lithium-excess manganese oxide exists, so that capacity characteristics can be improved, and it may be advantageous to combine a coating element (R) having a smaller sum of oxidation numbers of Q.

[0119]

[0120] According to one embodiment of the present invention, the Q may be two or more selected from W, Al, Zr, Ti, Mo, and Co, and the R may be one or more selected from Zn, Al, Co, Ti, Nb, V, Mo, and W. Specifically, the Q may be two or more selected from W, Al, Zr, Ti, Mo, and Co, and the R may be Co. In this case, the oxidation number of R is smaller than the sum of the oxidation numbers of Q, so that the coating portion including the coating element (R) attracts oxygen from the lithium-excess manganese oxide including the doping element (Q), thereby reducing the oxygen density of the lithium-excess manganese oxide. As a result, the ion conductivity is improved due to the coating portion formed on the lithium-excess manganese oxide, and the coating portion does not interfere with the insertion and deintercalation reaction of lithium ions, thereby promoting the movement of lithium ions. Accordingly, the electrical conductivity is improved, and the capacity characteristics of the secondary battery, etc., can be improved.

[0121]

[0122] According to one embodiment of the present invention, the positive electrode active material has an average particle diameter (D 50 ) may be 4 ㎛ or more and 12 ㎛ or less. Specifically, the positive electrode active material has an average particle diameter (D 50) may be 4 ㎛ or more, 5 ㎛ or more, 6 ㎛ or more, 7 ㎛ or more, 8 ㎛ or more, or 9 ㎛ or more, and may be 10 ㎛ or less, 11 ㎛ or less, or 12 ㎛ or less. Within the above range, excellent electrode density can be realized and structural stability can be improved.

[0123]

[0124] Method for manufacturing positive electrode active material

[0125] 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.

[0126]

[0127] The method for manufacturing a cathode active material according to the present invention comprises the steps of (A) preparing a mixture by mixing a composite transition metal hydroxide, a lithium (Li)-containing raw material, and a doping element (Q)-containing raw material; (B) preparing a lithium-excess manganese oxide by calcining the mixture; And (C) a step of mixing the lithium-excess manganese oxide and the raw material containing the coating element (R) and then heat-treating the mixture to form a coating portion; wherein the firing is performed in an air atmosphere at a temperature of 800° C. or higher and 1,000° C. or lower, and the doping element (Q) is at least two selected from among W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt, and the coating element (R) is at least one selected from among Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni, and the doping element (Q) and the coating element (R) may satisfy the following equation 1.

[0128] [Formula 1]

[0129] (Oxidation number of R) < (sum of oxidation numbers of Q)

[0130]

[0131] The cathode active material according to the present invention described above can be manufactured by appropriately controlling the type of raw material, the mixing ratio of raw materials, the sintering and heat treatment times, etc.

[0132]

[0133] Hereinafter, each step of the present invention will be described in detail.

[0134]

[0135] (A) Step

[0136] It includes the step (A) of preparing a mixture by mixing a composite transition metal hydroxide, a lithium (Li)-containing raw material, and a doping element (Q)-containing raw material.

[0137]

[0138] 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.

[0139] 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 complex transition metal aqueous solution can further include a metal-containing raw material.

[0140] The above nickel (Ni) containing raw material is NiSO 4, At least one selected from the group consisting of NiO, Ni(OH)2, NiOㆍOH, NiCO3ㆍ2Ni(OH)2ㆍ4H2O, NiC2O4ㆍ2H2O, Ni(NO3)2ㆍ6H2O, fatty acid nickel, and nickel halides may be used, and a mixture of one or two or more of these may be used. Considering the strong base used to control pH during the coprecipitation reaction, specifically, NiSO4 may be used.

[0141] The above manganese (Mn)-containing raw material may be at least one selected from the group consisting of MnSO4, MnCO3, Mn2O3, MnO2, Mn3O4, Mn(NO3)2, 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. Considering the strong base used to control pH during the coprecipitation reaction, specifically, MnSO4 may be used.

[0142] The above metal-containing raw material includes at least one transition metal other than nickel (Ni) and manganese (Mn), and may be at least one selected from the group consisting of carbonates, nitrates, hydroxides, oxides, halides, etc., and a mixture of one or two or more of these may be used.

[0143] 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.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] The above coprecipitation reaction can be carried out for 60 hours or more and 80 hours or less. 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.

[0148] 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.

[0149] Once the precursor particles are formed by the above method, the particles are separated from the reaction solution to obtain a complex transition metal hydroxide. Specifically, the reaction solution is filtered to separate the particles, and then the separated particles are washed and dried to obtain a complex transition metal hydroxide. At this time, processes such as grinding and / or classification may also be performed as needed.

[0150]

[0151] The above complex transition metal hydroxide is Mn a4 Ni b4 Q 1 c4 (OH)2(Q above 1The composite transition metal hydroxide may have a composition represented by (wherein a4, b4, and c4 are 0.500≤a4<1.000, 0.200≤b4<0.500, and 0.0000≤c4≤0.0300). In addition, the composite transition metal hydroxide may 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 including cobalt in the composite transition metal hydroxide.

[0152]

[0153] 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. Considering firing at a high temperature of about 800°C or higher and 1,000°C or lower, LiOH may be used specifically.

[0154]

[0155] According to the present invention, the doping element (Q) is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt.

[0156] According to one embodiment of the present invention, the raw material containing the doping element (Q) may be at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides, and halides containing the doping element (Q). Considering economic feasibility, processability, and accessibility, a raw material containing the doping element in the form of an oxide or hydroxide containing the doping element (Q) may be used.

[0157]

[0158] 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-excess manganese oxide to be finally manufactured.

[0159] According to one embodiment of the present invention, in step (A), a composite transition metal hydroxide containing nickel and manganese but not containing cobalt, a lithium (Li)-containing raw material, and a doping element (Q)-containing raw material can be mixed in an amount such that the raw material has a composition represented by the chemical formula 1 or 2.

[0160]

[0161] According to one embodiment of the present invention, the raw material containing the doping element (Q) may be mixed so that the content of the doping element (Q) is 500 ppm or more, 750 ppm or more, or 3,000 ppm or more, and 3,300 ppm or less, 10,000 ppm or less, or 13,500 ppm or less, based on the total weight of the composite transition metal hydroxide. When the mixing amount of the raw material containing the doping element (Q) is within the above range, the stability and electrical conductivity of the crystal structure of the positive electrode active material may be improved, thereby improving the capacity characteristics.

[0162]

[0163] (B) Step

[0164] The method for manufacturing a positive electrode active material according to the present invention includes, after step (A), step (B) of calcining the mixture to manufacture a lithium-excess manganese oxide.

[0165]

[0166] The above-mentioned calcination is performed under an air atmosphere. This facilitates the maintenance of the calcination atmosphere and is economically advantageous. In an oxidizing atmosphere, the formation of manganese oxide is promoted, which can compromise the capacity and lifespan of secondary batteries. In an inert atmosphere, the oxygen necessary for the reaction is absent.

[0167]

[0168] According to the present invention, the sintering is performed at a temperature of 800°C or higher and 1,000°C or lower. Specifically, the sintering can be performed at a temperature of 800°C or higher, 850°C or higher, or 900°C or higher, and 950°C or lower, or 1,000°C or lower. When the sintering temperature is within the above range, an appropriate ratio of Li2MnO3 phase and LiM'O2 phase can be formed. When the sintering is performed at a temperature lower than 800°C, crystallization is not performed properly, resulting in an uneven distribution of manganese particles. As a result, electrical conductivity decreases, causing problems with capacity and life characteristics. In addition, when the sintering is performed at a temperature higher than 1,000°C, the particle size increases due to oversintering, and the bonding force between particles weakens, resulting in a problem of deterioration in structural stability.

[0169]

[0170] According to one embodiment of the present invention, the firing may be performed for 7 hours or more and 10 hours or less. When the firing time is within the above range, the crystallinity of the lithium-excess manganese oxide particles is sufficiently controlled, which is advantageous for lithium ion transport.

[0171]

[0172] (C) Step

[0173] The method for manufacturing a cathode active material according to the present invention includes the step (C), which includes, after the step (B), a step of mixing the lithium-excess manganese oxide and the raw material containing the coating element (R) and then performing a heat treatment to form a coating portion.

[0174]

[0175] According to the present invention, the coating element (R) is at least one selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni.

[0176] According to one embodiment of the present invention, the raw material containing the coating element (R) may be at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides, and halides. Considering accessibility and processability, at least one selected from ZnO, Al(OH)3, Co2O3, TiO2, Nb2O5, V2O5, MoO2, WO3, and H3BO3 may be used.

[0177]

[0178] According to the present invention, the doping element (Q) and the coating element (R) satisfy Equation 1 described herein. In this case, structural stability and electrical conductivity are improved, and a positive electrode active material with improved capacity characteristics can be manufactured.

[0179]

[0180] According to one embodiment of the present invention, the raw material containing the coating element (R) may be mixed so that the content of the coating element (R) is 300 ppm or more, 500 ppm or more, 750 ppm or more, or 1,000 ppm or more, and 1,200 ppm or less, 3,000 ppm or less, or 5,000 ppm or less, based on the total weight of the lithium-excess manganese oxide. When the mixing amount of the raw material containing the coating element (R) is within the above range, the structural stability and electrical conductivity of the positive electrode active material are improved without acting as a resistor, so that the capacity characteristics can be improved.

[0181]

[0182] According to one embodiment of the present invention, the heat treatment may be performed in an air atmosphere, an oxygen atmosphere, or an inert atmosphere, and the heat treatment may be performed at a temperature of 400°C or more and 700°C or less. Specifically, the heat treatment may be performed at a temperature of 400°C or more, or 500°C or more, and 600°C or less, or 700°C or less. When the heat treatment temperature is within the above range, sufficient heat energy required for coating can be supplied. When the lithium-excess manganese oxide and the coating (R) raw material are mixed and then heat-treated within the above temperature range, a coating portion including a coating element (R) can be formed on the lithium-excess manganese oxide. The coating portion including the coating element (R) may partially cover (discontinuously) at least a portion of the lithium-excess manganese oxide, that is, a region of the lithium-excess manganese oxide, or may cover (continuously) the entire region. The form of the coating portion may be a film type, an island type, or a combination thereof.

[0183]

[0184] anode

[0185] Next, the anode according to the present invention will be described.

[0186] 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.

[0187]

[0188] 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.

[0189]

[0190] The above-mentioned positive electrode active material layer may include a conductive material and a binder together with the positive electrode active material. At this time, 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.

[0191]

[0192] 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 type alone or a mixture of two or more types of these 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.

[0193]

[0194] 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.

[0195]

[0196] 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.

[0197]

[0198] 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.

[0199]

[0200] lithium secondary battery

[0201] Next, a lithium secondary battery according to the present invention will be described.

[0202]

[0203] 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.

[0204]

[0205] 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.

[0206]

[0207] 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.

[0208]

[0209] 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.

[0210] 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.

[0211]

[0212] The above negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0213]

[0214] 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.

[0215] 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.

[0216]

[0217] 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.

[0218]

[0219] 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.

[0220]

[0221] 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.

[0222]

[0223] 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.

[0224]

[0225] 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.

[0226] Specifically, the electrolyte may include an organic solvent and a lithium salt.

[0227] 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.

[0228]

[0229] 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.

[0230]

[0231] 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.

[0232]

[0233] 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).

[0234] 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.

[0235] 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.

[0236] 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.

[0237] 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.

[0238]

[0239] 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.

[0240]

[0241] Manufacturing example

[0242] A 2.4 M complex transition metal aqueous solution was prepared by dissolving NiSO4 and MnSO4 in deionized water so that the molar ratio of nickel:manganese was 0.35:0.65. The inlet pipes for the complex transition metal aqueous solution and the 25 wt% NaOH aqueous solution were each connected to a 10 L continuous stirred tank reactor. 2.6 L of deionized water and 3.5 mL of a 25 wt% NaOH aqueous solution were added to the reactor, maintained at 50°C, and stirred at 150 rpm to prepare the initial pH of the solution to 12.0 to 13.0 (based on 25°C conversion). In addition, N2 gas was purged at 2 L / min to remove dissolved oxygen and create a non-oxidizing atmosphere inside the reactor. After that, while stirring at 1,000 rpm, the composition ratio of the gas input inside the reactor is changed from N2100% to N2: atmosphere ratio from 99.5:0.5 to 85.0:15.0 to form a weak oxygen atmosphere, and the complex transition metal aqueous solution is continuously input into the reactor at a flow rate of 0.85 L / hr. The amount of NaOH input and the RPM are adjusted so that the pH reaches 10.0 to 11.0 within 1 to 2 hours from the start of the reaction, thereby generating complex transition metal hydroxide seeds with a size of 3 to 5 μm. After that, the co-precipitation reaction is performed while maintaining the pH at 10.0 to 11.0 for 60 hours to grow the complex transition metal hydroxide particles, and when the target particle size (10 μm) is reached, the input of raw materials is stopped. After that, the particles are separated from the reaction solution, washed with water, and dried to form Ni. 0.35 Mn 0.65 A complex transition metal hydroxide having the composition (OH)2 was prepared.

[0243]

[0244] Examples and Comparative Examples

[0245] Examples 1 to 12

[0246] Ni manufactured in the manufacturing example 0.35 Mn 0.65 (OH)2 A composite transition metal hydroxide having the composition shown and LiOH, a raw material containing a first doping element (Q1) and a raw material containing a second doping element (Q2) (see Table 1 below) were mixed so that the molar ratio of Li:(Ni+Mn):Q1:Q2 was as shown in Table 1 below (see Table 1 below), and calcined for 7 to 10 hours at a temperature of 910°C in an air atmosphere to produce a lithium-excess manganese oxide having the composition represented by the chemical formula 1 described in the present specification (see Table 4 below). At this time, the raw material containing the first doping element (Q1) is Ni 0.35 Mn 0.65 (OH)2 is mixed so that the content of the first doping element (Q1) is 200 ppm or more and 10,000 ppm or less with respect to the total weight (the amount of the first doping element (Q1) input, see Table 1 below), and the raw material containing the second doping element (Q2) is Ni 0.35 Mn 0.65 (OH)2 is mixed so that the content of the second doping element (Q2) is 300 ppm or more and 5,000 ppm or less with respect to the total weight (the amount of the second doping element (Q2) added, see Table 1 below).

[0247]

[0248] The above lithium-excess manganese oxide and the raw material containing the coating element (R) were mixed and heat-treated for 4 to 6 hours under an oxygen atmosphere at a temperature of 400°C or higher and 700°C or lower (see Table 2 below), thereby manufacturing the positive electrode active materials of Examples 1 to 12 in which a coating portion containing the coating element (R) was formed on the lithium-excess manganese oxide. At this time, the raw material containing the coating element (R) is the lithium-excess manganese oxide. The coating element (R) is mixed so that the content is 300 ppm or more and 5,000 ppm or less with respect to the total weight (the coating element (R) input amount, see Table 2 below). The coating part is R, RO compound, Li-RO compound, and Li-M'-RO. It is composed of a component including at least one selected from compounds, and is in the form of a film type, an island type, or a combination thereof. In addition, the content of the coating portion is 0.05 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the lithium-excess manganese oxide.

[0249]

[0250] The raw material containing the first doping element (Q1), the raw material containing the second doping element (Q2), the raw material containing the coating element (R), the molar ratio, the mixing amount of the raw material containing the first doping element (Q1), the mixing amount of the raw material containing the second doping element (Q2), the heat treatment temperature, the mixing amount of the raw material containing the coating element (R), and the oxidation number of the first doping element (Q1), the relationship between the oxidation number of the second doping element (Q2) and the oxidation number of the coating element (R), etc. are specifically described in Tables 1 to 3 below.

[0251]

[0252] Comparative Example 1

[0253] Ni manufactured in the manufacturing example 0.35 Mn 0.65 (OH)2 A complex transition metal hydroxide having the indicated composition and LiOH were mixed so that the molar ratio of Li:(Ni+Mn) was 1.140:0.860, and calcined for 10 hours at a temperature of 910℃ in an air atmosphere, to obtain Li 1.140 Mn 0.560 Ni 0.300 A lithium-excess manganese oxide having a composition represented by O2 was prepared.

[0254] The lithium-excess manganese oxide and Al(OH)3 were mixed and heat-treated for 4 to 6 hours under an oxygen atmosphere at a temperature of 500°C to manufacture a cathode active material in which a coating portion including aluminum (Al) was formed on the lithium-excess manganese oxide. At this time, the Al(OH)3 was mixed so that the Al content was 1,000 ppm based on the total weight of the lithium-excess manganese oxide. The coating portion was formed by mixing Al, an Al-O compound, a Li-Al-O compound, and Li-M'-Al-O. It is composed of a component including at least one selected from compounds, and is in the form of a film type, an island type, or a combination thereof.

[0255]

[0256] Comparative Example 2

[0257] Ni manufactured in the manufacturing example 0.35 Mn 0.65 (OH)2 A complex transition metal hydroxide having the indicated composition and LiOH, ZnO and Al(OH)3 were mixed so that the molar ratio of Li:(Ni+Mn):Zn:Al was 1.139:0.852:0.001:0.008, and calcined in an air atmosphere at a temperature of 910°C for 7 to 10 hours, Li 1.139 Mn 0.555 Ni 0.297 Zn 0.001 Al 0.008 A lithium-excess manganese oxide having a composition represented by O2 was prepared. At this time, the ZnO is the Ni 0.35 Mn 0.65 (OH)2 is mixed so that Zn has a content of 1,000 ppm with respect to the total weight, and the Al(OH)3 is mixed so that the Ni 0.35 Mn 0.65 (OH)2 is mixed so that the content of Al is 750 ppm with respect to the total weight.

[0258]

[0259] The above lithium-excess manganese oxide and WO3 were mixed and heat-treated in an oxygen atmosphere at a temperature of 600°C for 4 to 6 hours to produce a positive electrode active material in which a coating including W was formed on the lithium-excess manganese oxide. At this time, the WO3 was the lithium-excess manganese oxide. It is mixed so that W content is 1,000 ppm with respect to the total weight. The coating part is W, WO compound, Li-WO compound and Li-M'-WO It is composed of a component including at least one selected from compounds, and is in the form of a film type, an island type, or a combination thereof. In addition, the content of the coating portion is 0.05 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the lithium-excess manganese oxide.

[0260]

[0261] Comparative Example 3

[0262] Ni manufactured in the manufacturing example 0.35 Mn 0.65 (OH)2 A complex transition metal hydroxide having the indicated composition and LiOH, Co2O3 and Al(OH)3 were mixed so that the molar ratio of Li:(Ni+Mn):Co:Al was 1.137:0.839:0.016:0.008, and calcined in an air atmosphere at a temperature of 910°C for 7 to 10 hours, Li 1.137 Mn 0.547 Ni 0.293 Co 0.016 Al 0.008 A lithium-excess manganese oxide having a composition represented by O2 was prepared. At this time, the Co2O3 is the Ni 0.35 Mn 0.65 (OH)2 is mixed so that Co has a content of 3,300 ppm with respect to the total weight, and the Al(OH)3 is mixed so that Ni 0.35 Mn 0.65(OH)2 is mixed so that the content of Al is 750 ppm with respect to the total weight.

[0263]

[0264] The above lithium-excess manganese oxide and WO3 were mixed and heat-treated in an oxygen atmosphere at a temperature of 600°C for 4 to 6 hours to produce a positive electrode active material in which a coating including W was formed on the lithium-excess manganese oxide. At this time, the WO3 was the lithium-excess manganese oxide. It is mixed so that W content is 1,000 ppm with respect to the total weight. The coating part is W, WO compound, Li-WO compound and Li-M'-WO It is composed of a component including at least one selected from compounds, and is in the form of a film type, an island type, or a combination thereof. In addition, the content of the coating portion is 0.05 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the lithium-excess manganese oxide.

[0265]

[0266] Comparative Example 4

[0267] Ni manufactured in the manufacturing example 0.35 Mn 0.65 (OH)2 A complex transition metal hydroxide having the indicated composition and LiOH, ZnO and Al(OH)3 were mixed so that the molar ratio of Li:(Ni+Mn):Zn:Al was 1.139:0.852:0.001:0.008, and calcined in an air atmosphere at a temperature of 910°C for 7 to 10 hours, Li 1.139 Mn 0.555 Ni 0.293 Zn 0.001 Al 0.008 A lithium-excess manganese oxide having a composition represented by O2 was prepared. At this time, the ZnO is the Ni 0.35 Mn 0.65(OH)2 is mixed so that Zn has a content of 1,000 ppm with respect to the total weight, and the Al(OH)3 is mixed so that the Ni 0.35 Mn 0.65 (OH)2 is mixed so that the content of Al is 750 ppm with respect to the total weight.

[0268]

[0269] The above lithium-excess manganese oxide and Nb2O5 were mixed and heat-treated in an oxygen atmosphere at a temperature of 600°C for 4 to 6 hours to produce a cathode active material in which a coating including Nb was formed on the lithium-excess manganese oxide. At this time, the Nb2O5 was the lithium-excess manganese oxide. Nb is mixed to have a content of 750 ppm with respect to the total weight. The coating part is composed of Nb, Nb-O compound, Li-Nb-O compound and Li-M'-Nb-O It is composed of a component including at least one selected from compounds, and is in the form of a film type, an island type, or a combination thereof. In addition, the content of the coating portion is 0.05 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the lithium-excess manganese oxide.

[0270]

[0271] Comparative Example 5

[0272] Ni manufactured in the manufacturing example 0.35 Mn 0.65 (OH)2 A complex transition metal hydroxide having the indicated composition and LiOH and Al(OH)3 were mixed so that the molar ratio of Li:(Ni+Mn):Al was 1.139:0.853:0.008:0, and calcined in an air atmosphere at a temperature of 910°C for 7 to 10 hours, Li 1.139 Mn 0.556 Ni 0.298 Al 0.008A lithium-excess manganese oxide having a composition represented by O2 was prepared. At this time, the Al(OH)3 is the Ni 0.35 Mn 0.65 (OH)2 is mixed so that the content of Al is 750 ppm with respect to the total weight.

[0273]

[0274] The above lithium-excess manganese oxide and Co2O3 were mixed and heat-treated in an oxygen atmosphere at a temperature of 700°C for 4 to 6 hours to produce a positive electrode active material in which a coating including Co was formed on the lithium-excess manganese oxide. At this time, the Co2O3 was the lithium-excess manganese oxide. Co is mixed to have a content of 1000 ppm with respect to the total weight. The coating part is composed of Co, Co-O compound, Li-Co-O compound and Li-M'-Co-O It is composed of a component including at least one selected from compounds, and is in the form of a film type, an island type, or a combination thereof. In addition, the content of the coating portion is 0.05 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the lithium-excess manganese oxide.

[0275]

[0276] Comparative Example 6

[0277] Ni manufactured in the manufacturing example 0.35 Mn 0.65 (OH)2 A complex transition metal hydroxide having the indicated composition and LiOH and TiO2 were mixed so that the molar ratio of Li:(Ni+Mn):Ti was 1.140:0.857:0.003, and calcined in an air atmosphere at a temperature of 910°C for 7 to 10 hours, thereby obtaining Li 1.140 Mn 0.558 Ni 0.299 Ti 0.003 A lithium-excess manganese oxide having a composition represented by O2 was prepared. At this time, the TiO2 was Ni0.35 Mn 0.65 (OH)2 is mixed so that the content of Ti is 1,400 ppm with respect to the total weight.

[0278]

[0279] The lithium-excess manganese oxide and Al(OH)3 were mixed and heat-treated for 4 to 6 hours under an oxygen atmosphere at a temperature of 500°C to manufacture a cathode active material in which a coating portion including aluminum (Al) was formed on the lithium-excess manganese oxide. At this time, the Al(OH)3 was mixed so that the Al content was 1,000 ppm based on the total weight of the lithium-excess manganese oxide. The coating portion was formed by mixing Al, an Al-O compound, a Li-Al-O compound, and Li-M'-Al-O. It is composed of a component including at least one selected from compounds, and is in the form of a film type, an island type, or a combination thereof.

[0280]

[0281] Comparative Example 7

[0282] Ni manufactured in the manufacturing example 0.35 Mn 0.65 (OH)2 Complex transition metal hydroxides with the indicated composition and LiOH and ZrO2 with a molar ratio of Li:(Ni+Mn):Zr 1.140 Mn 0.558 Ni 0.299 Zr 0.003 O2 was mixed and calcined for 7 to 10 hours at a temperature of 910℃ in an air atmosphere to produce a lithium-excess manganese oxide having a composition of 1.140:0.857:0.003. At this time, the ZrO2 was Ni 0.35 Mn 0.65 (OH)2 is mixed so that the content of Zr is 2,700 ppm with respect to the total weight.

[0283]

[0284] The lithium-excess manganese oxide and Al(OH)3 were mixed and heat-treated for 4 to 6 hours under an oxygen atmosphere at a temperature of 500°C to manufacture a cathode active material in which a coating portion including aluminum (Al) was formed on the lithium-excess manganese oxide. At this time, the Al(OH)3 was mixed so that the Al content was 1,000 ppm based on the total weight of the lithium-excess manganese oxide. The coating portion was formed by mixing Al, an Al-O compound, a Li-Al-O compound, and Li-M'-Al-O. It is composed of a component including at least one selected from compounds, and is in the form of a film type, an island type, or a combination thereof.

[0285]

[0286] Raw material containing the first doping element (Q1) Raw material containing the second doping element (Q2) Li:(Ni+Mn):Q1:Q2 Firing temperature (℃) Amount of the first doping element (Q1) added (ppm) Amount of the second doping element (Q2) added (ppm) Example 1 WO3Zr2O3 1.139:0.856:0.002:0.0039101,0002,799 Example 2 WO3Zr2O3 1.139:0.853:0.005:0.0033,0002,700 Example 3 WO3TiO2 1.139:0.856:0.002:0.0031,0001,400 Example 4WO3TiO21.139:0.853:0.005:0.0033,0001,400 Example 5WO3Co2O31.137:0.840:0.015:0.00810,0001,650 Example 6WO3Al(OH)31.137:0.840:0.012:0.0117,9901,000 Example 7WO3Al(OH)31.135:0.832:0.012:0.0217,9902,000 Example 8WO3MoO31.138:0.850:0.011:0.00037,400270 Example 9WO3MoO31.138:0.849:0.011:0.0027,0001,820Example 10WO3ZrO21.138:0.848:0.011:0.0037,6602,780Example 11WO3Al(OH)31.132:0.812:0.012:0.0447,9904,120Example 12WO3TiO21.138:0.848:0.011:0.0037,0001,400Comparative Example 1--1.140:0.860--Comparative Example 2ZnOAl(OH)31.139:0.852:0.001:0.0081,000750Comparative Example 3Co2O3Al(OH)31.137:0.839:0.016:0.0083,300750Comparative example 4ZnOAl(OH)31.139:0.852:0.001:0.0081,000750Comparative example 5Al(OH)3-1.139:0.853:0.008750-Comparative example 6TiO2-1.140:0.857:0.0031,400-Comparative example 7ZrO2-1.140:0.857:0.0032,700-

[0287] Raw material containing coating element (R) Heat treatment temperature (℃) Coating element (R) input amount (ppm) Example 1 Co2O3 700 3,300 Example 2 Co2O3 3,300 Example 3 Co2O3 3,300 Example 4 Co2O3 3,300 Example 5 Co2O3 3,300 Example 6 Co2O3 3,300 Example 7 Co2O3 3,300 Example 8 Co2O3 3,300 Example 9 Co2O3 3,300 Example 10 Co2O3 3,300 Example 11 Co2O3 3,300 Example 12 Co2O3 3,300 Comparative Example 1 Al(OH)3 500 1,000 Comparative Example 2 WO3 600 1,000 Comparative Example 3WO36001,000Comparative example 4Nb2O5600750Comparative example 5Co2O37003,300Comparative example 6Al(OH)35001,000Comparative example 7Al(OH)35001,000

[0288] Oxidation number of Q1 Oxidation number of Q2 Oxidation number of R Oxidation number R < Sum of oxidation numbers of Q Example 1633O Example 2633O Example 3643O Example 4643O Example 5633O Example 6633O Example 7633O Example 8663O Example 9663O Example 10643O Example 11633O Example 12643O Comparative Example 1--3- Comparative Example 2236X Comparative Example 3336X Comparative Example 4235X Comparative Example 53-3X Comparative Example 64-3O Comparative Example 74-3O

[0289]

[0290] Experimental example

[0291] Experimental Example 1: XRD Analysis

[0292] For each positive electrode active material manufactured in the above examples, after XRD measurement, the XRD data is shown in Fig. 1, and for each positive electrode active material manufactured in the above comparative examples, after XRD measurement, the XRD data is shown in Fig. 2.

[0293] 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 14° to 60° using an X-ray diffraction analysis method.

[0294] Figure 1 shows XRD data of the positive electrode active materials manufactured in Examples 1 to 12.

[0295] Figure 2 shows XRD data of the positive electrode active materials manufactured in Comparative Examples 1 to 5.

[0296] Through FIGS. 1 and 2, it was confirmed that the embodiment simultaneously includes a Li2MnO3 phase and a LiM'O2 (wherein M' is an element including at least one selected from Ni and Mn) phase. Specifically, it was confirmed that the Li2MnO3 phase was included with a small peak present at 20.7°, and it was confirmed that the LiM'O2 (wherein M' is an element including at least one selected from Ni and Mn) phase was included with a large peak present at about 18°.

[0297]

[0298] Experimental Example 2: ICP Analysis

[0299] Each of the lithium-excess manganese oxides and positive electrode active materials manufactured in the above examples and comparative examples was taken in an amount of 0.1 g, 1 ml of hydrochloric acid was added, and the positive electrode active material was dissolved by heating. Thereafter, a small amount of hydrogen peroxide was added to promote the reaction to completely dissolve the positive electrode active material, thereby preparing 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 lithium-excess manganese oxide, the content (ppm) of the first doping element (Q1), the content (ppm) of the second doping element (Q2), and the content (ppm) of the coating element (R) are shown in Table 4 below. For reference, the measurement error of the element content is approximately ±110 ppm.

[0300] Composition Content of doping element (Q1) (ppm) Content of doping element (Q2) (ppm) Content of coating element (R) (ppm) Example 1 Li 1.139 Mn 0.557 Ni 0.299 W 0.002 Zr 0.003 O297227813301Example 2Li 1.139 Mn 0.556 Ni 0.298 W 0.005 Zr 0.003 O2290826533277Example 3Li 1.139 Mn 0.557 Ni 0.299 W 0.002 Ti 0.003 O299313563169Example 4Li 1.139 Mn 0.556 Ni 0.298 W 0.005 Ti 0.003 O2289414313160Example 5Li 1.137 Mn 0.547 Ni 0.293 W 0.015 Co 0.008 O2995616443277Example 6Li 1.137 Mn 0.547 Ni 0.293W 0.012 Al 0.011 O278649913187Example 7Li 1.135 Mn 0.542 Ni 0.290 W 0.012 Al 0.012 O2799121053262 Example 8Li 1.138 Mn 0.554 Ni 0.297 W 0.011 Mo 0.0003 O273522533306Example 9Li 1.138 Mn 0.553 Ni 0.296 W 0.011 Mo 0.002 O2685418053140 Example 10Li 1.138 Mn 0.552 Ni 0.296 W 0.011 Zr 0.002 O2756427763247Example 11Li 1.132 Mn 0.529 Ni 0.283 W 0.012 Al 0.044 O2790541153199 Example 12Li 1.138 Mn 0.552 Ni 0.296 W 0.011 Ti 0.003 O2687814053204Comparative Example 1Li 1.140 Mn 0.560 Ni 0.300 O2--998 Comparative Example 2Li 1.139 Mn 0.555 Ni 0.297 Zn 0.001 Al 0.008 O2988740964Comparative Example 3Li 1.137 Mn 0.547 Ni 0.293 Co 0.016 Al 0.008 O23255748975Comparative Example 4Li 1.139 Mn 0.555 Ni 0.293 Zn 0.001 Al 0.008 O2988740734Comparative Example 5Li 1.139 Mn 0.556 Ni 0.298 Al 0.008O2735-3297 Comparative Example 6Li 1.140 Mn 0.558 Ni 0.299 Ti 0.003 O21368-967 Comparative Example 7Li 1.140 Mn 0.558 Ni 0.299 Zr 0.003 O22691-978

[0301] Through Tables 3 and 4, it was confirmed that the positive electrode active materials manufactured in Examples 1 to 12 include two or more doping elements (Q) selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na, and Pt, and include one or more coating elements (R) selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni, and that the Q and R satisfy Formula 1 described herein. In addition, it was confirmed that the positive electrode active materials manufactured in Examples 1 to 12 include a lithium-excess manganese oxide having a composition represented by Chemical Formula 1 described herein. In addition, it was confirmed that the positive electrode active materials manufactured in Examples 1 to 12 had a sum of the content of the first doping element (Q1) and the content of the second doping element (Q2), i.e., a content of the doping element (Q), of 500 ppm or more and 13,000 ppm or less with respect to the total weight of the lithium-excess manganese oxide, and that the content of the coating element (R) included in the coating portion was 300 ppm or more and 4,000 ppm or less with respect to the total weight of the lithium-excess manganese oxide.

[0302]

[0303] Experimental Example 3: Morphological Analysis of the Coated Part

[0304] For each of the above examples and comparative examples, a cathode material or cathode active material, Super P as a conductive material, and polyvinylidene fluoride (PVDF) as a binder were mixed in a weight ratio of 92.5:3:4.5 in an N-methylpyrrolidone (NMP) solvent to prepare a cathode slurry. The prepared cathode slurry was applied to one surface of an aluminum current collector, dried at 130°C, and then rolled to a porosity of 26% to prepare a cathode.

[0305] To create a flat surface for EPMA cross-sectional analysis, the anode was subjected to Ar-ion milling to obtain a cross-section of the anode sample, and the cross-sectional image of the anode sample was observed using JEOL JXA-iHP200F equipment.

[0306] Figure 3 is an EPMA cobalt element mapping image of a cross-section of a positive electrode including a positive electrode active material manufactured in Example 1.

[0307] Through FIG. 3, it was confirmed that the positive electrode active material manufactured in Example 1 according to the present invention has a coating portion including cobalt evenly formed over the entire surface, and in particular, a coating portion including cobalt (green and red portions) is formed intensively along the adjacent boundaries between particles, and the coating portion is a film type, an island type, or a combination thereof.

[0308]

[0309] Experimental Example 4: Measurement of the average particle size of the positive electrode active material

[0310] In order to measure the average particle size of the positive electrode active material particles manufactured in the above examples and comparative examples, the particle size of the positive electrode active material produced in the examples and comparative examples was measured using PSA (Microtrac, S3500), and the results are shown in Table 5 below.

[0311] Average particle diameter (D 50) (㎛) Example 19.70 Example 29.65 Example 39.68 Example 49.72 Example 59.65 Example 69.86 Example 79.77 Example 89.85 Example 99.70 Example 109.79 Example 119.81 Example 129.78 Comparative Example 19.65 Comparative Example 29.66 Comparative Example 39.71 Comparative Example 49.63 Comparative Example 59.61 Comparative Example 69.78 Comparative Example 79.66

[0312] Through Table 5, the above positive electrode active material has an average particle diameter (D 50 ) was confirmed to be 4㎛ or more and 12㎛ or less.

[0313]

[0314] Experimental Example 5: Battery Characteristics Evaluation

[0315] - Manufacturing of coin-type half-cells

[0316] A positive electrode slurry was prepared by mixing 97.5 wt% of each of the positive electrode active materials manufactured in the above examples and comparative examples, 1.0 wt% of Super P as a conductive agent, and 1.5 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.

[0317] 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 a coin-type half-cell was manufactured by injecting an electrolyte solution containing 1 M LiPF6 dissolved in an organic solvent containing ethylene carbonate (EC): ethyl methyl carbonate (EMC): diethyl carbonate (DEC) in a volume ratio of 3:4:3.

[0318]

[0319] - Battery characteristic evaluation

[0320] Using the coin-type half-cells containing each of the positive electrode active materials manufactured in the above examples and comparative examples, an activation process (formation) was performed, and then the cells were charged (0.33C) in a CC-CV manner to 4.4 V at 25°C, and then discharged (0.33C) in a CC manner to 2.5 V to perform an initial charge-discharge process, and the charge and discharge capacities at this time were measured. The measured charge and discharge capacities are shown in Table 6 below.

[0321] Charge capacity (mAh / g)Discharge capacity (mAh / g)Example 1213.7205.3Example 2215.2201.4Example 3213.7204.5Example 4213.8202.3Example 5215.7204.8Example 6210.8201.9Example 7211.0202.3Example 8216.1201.7Example 9212.8203.9Example 10214.6200.7Example 11214.8205.0Example 12215.0203.7Comparative example 1206.1192.3Comparative example 2208.8195.6Comparative example 3209.0197.1Comparative Example 4208.2196.0Comparative Example 5205.5191.9Comparative Example 6203.3189.7Comparative Example 7207.3189.2

[0322] Through Table 6, it was confirmed that the batteries including the positive electrode active materials manufactured in Examples 1 to 12 had a greater charge / discharge capacity than Comparative Example 1, which did not include a doping element and a coating element, and Comparative Examples 5 to 7, which included only one type of doping element, and that the batteries including the positive electrode active materials manufactured in Examples 1 to 12 had a greater charge / discharge capacity than Comparative Example 2, which included two types of doping elements but in which the sum of the oxidation numbers of the doping elements was smaller than the oxidation number of the coating element, and Comparative Examples 3 and 4, in which the sum of the oxidation numbers of the doping elements was equal to the oxidation number of the coating element.

[0323] In conclusion, it was confirmed that the positive electrode active material including the doping element (Q) and coating element (R) according to formula 1 of the present invention improved the charge / discharge capacity of the battery.

Claims

1. A lithium-excess manganese oxide simultaneously comprising a Li2MnO3 phase and a LiM'O2 phase (wherein M' is an element including at least one selected from Ni and Mn); and A coating portion formed on the lithium-excess manganese oxide; The above lithium-excess manganese oxide contains two or more doping elements (Q) selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na and Pt, The above coating portion includes at least one coating element (R) selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B and Ni. A cathode active material satisfying the following equation 1: [Formula 1] (Oxidation number of R) < (sum of oxidation numbers of Q).

2. In claim 1, The above lithium-excess manganese oxide is a cathode active material having a composition represented by the following chemical formula 1 or chemical formula 2: [Chemical Formula 1] The 1+x Mn a1 Nor b1 Q c1 O2 In the above chemical formula 1, Q is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na and Pt, 0.000 <x≤0.200, 0.500≤a1<1.000, 0.200≤b1<0.500, 0.0000<c1≤0.0300이고, [Chemical formula 2] αLi2Mn 1-c2 Q c2 O3·βLi(Mn a2 If b2 Q c3 )O2 In the above chemical formula 2, Q is two or more selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na and Pt, 0<α<1, 0<β<1, 0.0000≤c2≤0.0100, 0.000 <a2≤0.500, 0.000<b2≤0.500 0.0000≤c3≤0.0100, a2+b2+c3=1.000이고, c2+c3> It is 0.0000.

3. In claim 1, A cathode active material having a content of the above doping element (Q) of 500 ppm or more and 13,000 ppm or less based on the total weight of the lithium-excess manganese oxide.

4. In claim 1, A cathode active material having a shape of the coating portion of a film type, an island type, or a combination thereof.

5. In claim 1, The above coating portion comprises R, RO compound, Li-RO compound and Li-M'-RO. A cathode active material comprising at least one compound selected from the group consisting of:

6. In claim 1, A cathode active material having a content of the coating part of 0.05 parts by weight or more and 0.3 parts by weight or less with respect to 100 parts by weight of the lithium-excess manganese oxide.

7. In claim 1, A cathode active material having a content of a coating element (R) included in the coating portion of 300 ppm or more and 4,000 ppm or less based on the total weight of the lithium-excess manganese oxide.

8. In claim 1, A cathode active material wherein the oxidation number of the above Q is 3 or more and 6 or less.

9. In claim 1, The above Q is two or more selected from W, Al, Zr, Ti, Mo and Co, A cathode active material wherein the above R is at least one selected from Zn, Al, Co, Ti, Nb, V, Mo, and W.

10. In claim 1, Average particle diameter (D 50 ) A positive electrode active material having a size of 4㎛ or more and 12㎛ or less. 11.(A) A step of preparing a mixture by mixing a composite transition metal hydroxide, a lithium (Li)-containing raw material, and a doping element (Q)-containing raw material; (B) a step of producing a lithium-excess manganese oxide by calcining the mixture; and (C) a step of forming a coating part by mixing the lithium-excess manganese oxide and the raw material containing the coating element (R) and then performing heat treatment; The above firing is performed under an atmospheric atmosphere at a temperature of 800℃ or higher and 1,000℃ or lower. The above doping element (Q) is at least two selected from W, Al, Co, Zr, Re, V, Cr, Fe, Ga, Si, B, Ru, Ti, Nb, Mo, Mg, Na and Pt, The above coating element (R) is at least one selected from Zn, Al, Co, Ti, Nb, V, Mo, W, B, and Ni. A method for manufacturing a cathode active material, wherein the above doping element (Q) and the above coating element (R) satisfy the following formula 1: [Formula 1] (Oxidation number of R) < (sum of oxidation numbers of Q).

12. In claim 11, A method for producing a cathode active material, wherein the raw material containing the above doping element (Q) is at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides and halides containing the doping element (Q).

13. In claim 11, A method for manufacturing a cathode active material, wherein the raw material containing the above doping element (Q) is mixed so that the content of the doping element (Q) is 500 ppm or more and 13,500 ppm or less with respect to the total weight of the above complex transition metal hydroxide.

14. In claim 11, A method for producing a cathode active material, wherein the raw material containing the coating element (R) is at least one selected from oxides, carbonates, nitrates, hydroxides, oxyhydroxides and halides containing the coating element (R).

15. In claim 11, A method for manufacturing a cathode active material, wherein the raw material containing the above coating element (R) is mixed so that the coating element (R) content is 300 ppm or more and 5,000 ppm or less with respect to the total weight of the lithium-excess manganese oxide.

16. In claim 11, A method for manufacturing a positive electrode active material, wherein the above heat treatment is performed at a temperature of 400°C or higher and 700°C or lower.

17. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 10.

18. A lithium secondary battery comprising a positive electrode according to claim 17.

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