Positive electrode active material for lithium secondary battery, and lithium secondary batterty comprising same

Abstract

The present invention relates to a positive electrode active material for a lithium secondary battery, the positive electrode active material comprising a layered lithium metal oxide having a composition with an excess of lithium and manganese, wherein the average number of internal pores in the lithium metal oxide is 200 or more.

Description

Cathode active material for lithium secondary batteries and lithium secondary battery including the same

[0001] The present invention relates to a positive electrode active material for a lithium secondary battery and a lithium secondary battery comprising the same.

[0002] This application claims priority to Korean Patent Application No. 10-2024-0189846, filed on December 18, 2024, the entire contents of which are incorporated herein by reference.

[0003]

[0004] As the application range of lithium-ion batteries expands from small electronic devices to electric vehicles and power storage devices, there is a growing demand for cathode materials with excellent high energy density and high power characteristics.

[0005] In this regard, lithium and manganese-excess layered lithium metal oxides are attracting attention as candidates for next-generation cathode active materials due to their very high capacity, and research on this is currently being actively conducted worldwide.

[0006] However, lithium and manganese-excess lithium metal oxides exhibit low electrochemical reactivity, resulting in low initial efficiency and significant degradation of actual capacity compared to theoretical capacity. Although various strategies, such as coating technologies, are being attempted to address this, commercialization remains difficult due to the fundamental structural limitations of the lithium metal oxide substrate.

[0007]

[0008] Accordingly, one objective of the present invention is to provide a positive electrode active material for a lithium secondary battery with improved electrochemical reactivity, resulting in improved initial efficiency, capacity characteristics, and rate characteristics, and a lithium secondary battery including the same.

[0009]

[0010] One embodiment of the present invention provides a positive electrode active material for a lithium secondary battery comprising a layered lithium metal oxide having an excess composition of lithium and manganese, wherein the lithium metal oxide has an average number of internal pores of 200 or more.

[0011] The above lithium metal oxide may have an average number of internal pores ranging from 220 to 800.

[0012] The above lithium metal oxide has an average internal pore size of 340 nm 2 It could be more than that.

[0013] The above lithium metal oxide may have an average internal pore sphericity of 0.70 to 0.95.

[0014] The above lithium metal oxide may have an average internal porosity of 3.4% to 10.0%.

[0015] The above lithium metal oxide has an average standard deviation of internal pore size of 114 to 170 nm 2 It could be.

[0016] The above lithium metal oxide can satisfy the following Formula 1:

[0017] [Equation 1]

[0018] 79 < (Npore / Ppore) ≤ 112

[0019] (In Equation 1,

[0020] Npore is the average number of internal pores in lithium metal oxide, and

[0021] Ppore is the average internal porosity (%) of lithium metal oxide.

[0022] The above lithium metal oxide can satisfy the following Equation 2:

[0023] [Equation 2]

[0024] 2500 ≤ {ln(Npore)*Apore / Cpore} ≤ 4500

[0025] (In Equation 2,

[0026] Npore is the average number of internal pores in lithium metal oxide, and

[0027] Apore is the average internal pore size (nm) of lithium metal oxide. 2 ) and,

[0028] Cpore refers to the average internal pore sphericity of lithium metal oxides).

[0029] The above lithium metal oxide can satisfy the following Equation 3:

[0030] [Equation 3]

[0031] 31 ≤ (Apore / D50) ≤ 60

[0032] (In Equation 3,

[0033] Apore is the average internal pore size (nm) of lithium metal oxide. 2 ) and,

[0034] D50 is the average particle size (D50) (μm) of the lithium metal oxide.

[0035] The above lithium metal oxide may be a solid solution or composite of a phase belonging to the C2 / m space group and a phase belonging to the R3-m space group.

[0036] The above lithium metal oxide may include a LiMO2 phase (M is Ni, Co, Mn, Zr, Al, B, Y, Mg, Na, Ga, Ce, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir or a combination thereof, but must include Ni and Mn) and a Li2MnO3 phase.

[0037] The above lithium metal oxide can be represented by the following chemical formula 1:

[0038] [Chemical Formula 1]

[0039] Li 1+a (Ni x Co y Mnz M w ) 1-a O2

[0040] (In the above chemical formula 1,

[0041] 0.08≤a≤0.3, 0.2≤x≤0.4, 0≤y≤0.2, 0.5≤z≤0.75, 0≤w≤0.2, and x+y+z+w=1,

[0042] M is Zr, Al, B, Y, Mg, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir, or a combination thereof).

[0043] Another embodiment of the present invention comprises the steps of: mixing a nickel raw material, a manganese raw material, and a solvent to form a metal-containing solution; introducing the metal-containing solution, a complexing agent-containing solution, and a pH regulator-containing solution into a reactor to form a reaction solution; co-precipitating the reaction solution to form a metal precursor having a molar ratio (Mn / Me) of manganese (Mn) to the total metal (Me) of 0.5 or more; and mixing the metal precursor and a lithium raw material, followed by calcination to form a lithium metal oxide having an excess composition of lithium and manganese; wherein the specific surface area (BET) of the metal precursor is 26 to 38 m² 2 A method for manufacturing a positive electrode active material for a lithium secondary battery, with a content of 1 / g, is provided.

[0044] The tap density of the above metal precursor is 1.47 to 1.74 g / cm³ 3 It could be.

[0045] The average particle size (D50) of the metal precursor may be 8 to 12 μm.

[0046] Another embodiment of the present invention provides a positive electrode for a lithium secondary battery comprising the aforementioned positive electrode active material.

[0047] Another embodiment of the present invention provides a lithium secondary battery comprising the aforementioned positive electrode for a lithium secondary battery.

[0048]

[0049] In a positive electrode active material for a lithium secondary battery according to one embodiment of the present invention, the morphology of the internal pores of the lithium metal oxide is multidimensionally controlled, thereby improving the initial efficiency, capacity characteristics, and rate characteristics.

[0050]

[0051] Figure 1 is a cross-sectional SEM image of a positive electrode active material prepared according to Example 1 after Focused Ion Beam (FIB) milling.

[0052] Figure 2 is a processed image of Figure 1 processed using image software.

[0053] Figure 3 is a cross-sectional SEM image of the positive electrode active material prepared according to Example 2 after Focused Ion Beam (FIB) milling.

[0054] Figure 4 is a processed image of Figure 3 processed using image software.

[0055] Figure 5 is a cross-sectional SEM image of the positive electrode active material prepared according to Comparative Example 1 after Focused Ion Beam (FIB) milling.

[0056] Figure 6 is a processed image of Figure 5 processed using image software.

[0057]

[0058] Terms such as first, second, and third are used to describe various parts, components, regions, layers, and / or sections, but are not limited thereto. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, the first part, component, region, layer, or section described below may be referred to as the second part, component, region, layer, or section without departing from the scope of the present invention.

[0059] The technical terms used herein are for the reference of specific embodiments only and are not intended to limit the invention. The singular forms used herein include plural forms unless phrases clearly indicate otherwise. As used in the specification, the meaning of "comprising" specifies certain characteristics, areas, integers, steps, actions, elements, and / or components, and does not exclude the presence or addition of other characteristics, areas, integers, steps, actions, elements, and / or components.

[0060] When it is stated that one part is "on" or "on" another part, it may be directly on or on the other part, or another part may be involved in between. In contrast, when it is stated that one part is "directly on" another part, no other part is interposed in between.

[0061] Unless otherwise defined, all terms used herein, including technical and scientific terms, have the same meaning as generally understood by those skilled in the art to which this invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with relevant technical literature and the present disclosure, and are not interpreted in an ideal or highly formal sense unless otherwise defined.

[0062] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0063] In this specification, the term “combination(s) of these” described in the Markush-type expression means one or more mixtures or combinations selected from the group consisting of the components described in the Markush-type expression, and means including any one or more selected from the group consisting of said components.

[0064] Hereinafter, embodiments of the present invention are described in detail so that those skilled in the art can easily implement the invention. However, the present invention may be embodied in various different forms and is not limited to the embodiments described herein.

[0065]

[0066] positive electrode active material

[0067] A positive electrode active material for a lithium secondary battery according to one embodiment of the present invention comprises a lithium metal oxide having a composition with excess lithium and manganese. Although the lithium metal oxide with an excess lithium and manganese composition has a low nickel content, it can undergo oxidation / reduction reactions of anions (oxygen) as well as transition metals during battery operation. Additionally, since excess lithium may exist in the transition metal layer in addition to the lithium layer, the insertion and extraction efficiency of lithium ions can be increased. As a result, the initial discharge capacity is 240 mAh / g or higher, and the capacity characteristics can be significantly improved compared to a conventional NCM composition positive electrode material. Furthermore, it offers excellent economic efficiency as it allows for a reduction in the content of relatively expensive nickel and cobalt and an increase in the content of inexpensive manganese.

[0068] Meanwhile, the lithium metal oxide according to the present invention may be in the form of secondary particles formed by the aggregation of a plurality of primary particles.

[0069] In this specification, “secondary particle” means an aggregate, i.e., a secondary structure, formed by the aggregation of tens to hundreds of primary particles by physical or chemical bonding between primary particles without an intentional aggregation or assembly process of the primary particles.

[0070] In addition, in this specification, “primary particle” refers to a minimum particle unit that is distinguished as a single mass when the cross-section of the positive electrode active material is observed through a scanning electron microscope (SEM), and may consist of a single crystal grain or multiple crystal grains. In this specification, “crystal grain” refers to a distinct region in which atoms within the primary particle form a lattice structure in a specific direction.

[0071] At this time, the lithium metal oxide with excess lithium and manganese composition has a layered crystal structure, and space groups of C2 / m and R3-m can be dissolved or combined.

[0072] That is, unlike lithium metal oxides of a lithium and manganese excess composition according to the present invention, a LiMO2 phase having an R3-m space group (M is Ni, Co, Mn, Zr, Al, B, Y, Mg, Na, Ga, Ce, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir or a combination thereof, but must include Ni and Mn) and a Li2MnO3 phase having a C2 / m space group can be dissolved or combined.

[0073] However, lithium and manganese-excess lithium metal oxides present a problem where, if the internal morphology of the substrate is not well controlled, their low electrochemical reactivity results in low initial efficiency and significantly degraded actual capacity compared to the theoretical capacity. To address this, various strategies, such as doping or coating technologies, are being attempted. However, while doping technology can modify the microscopic internal crystal structure of lithium metal oxides, it has limitations in controlling the internal morphology of the substrate; similarly, coating technology can control the morphology of the coating layer outside the substrate, but it also has limitations in controlling the internal morphology of the substrate.

[0074] Accordingly, the inventors studied the internal morphology of the substrate to improve the initial efficiency and capacity of lithium and manganese-excess lithium metal oxides. As a result, they discovered that by precisely controlling the morphology of the internal pores of the lithium and manganese-excess lithium metal oxides, not only the initial efficiency and capacity but also the rate characteristics could be improved, thereby completing the present invention.

[0075]

[0076] Specifically, the lithium metal oxide according to the present invention has an average number of internal pores of 200 or more. Specifically, it may be 220 to 800, and more specifically, 250 to 780, 300 to 760, or 350 to 740. By sufficiently securing the number of internal pores within the lithium metal oxide within the above range, the internal pores provide a sufficient diffusion path for lithium ions, thereby improving lithium ion mobility and thus improving initial efficiency, capacity, and rate characteristics. More specifically, if the average number of internal pores in the lithium metal oxide is less than the lower limit value, internal pores are not sufficiently formed, resulting in reduced lithium ion mobility, and consequently, reduced initial efficiency, capacity characteristics, and rate characteristics. On the other hand, if it exceeds the upper limit value, the internal reaction interface increases and the pore structure becomes non-uniform, which may lead to reduced initial efficiency, increased consumption of active lithium, and reduced rate characteristics.

[0077] Meanwhile, the number of internal pores in lithium metal oxides is correlated to some extent with the internal porosity, which refers to the ratio of the pore area within the lithium metal oxide, but this correlation is not strictly observed. In other words, even if the internal porosity of the lithium metal oxide is high, the number of internal pores may be small or large.

[0078] In this specification, “average number of internal pores” refers to the number of pores formed inside the manufactured positive electrode active material particles and can be calculated through image analysis based on FIB-SEM cross-sectional images. Specifically, in this embodiment, the “average number of internal pores” may be calculated by cutting the manufactured positive electrode active material particles by FIB (Focused Ion Beam) milling to obtain a cross-sectional SEM image, measuring the total number of internal pores within the cut cross-section using image software, and then calculating the number of internal pores for 30 random positive electrode active material particles within the positive electrode active material powder in the same manner and calculating the average value.

[0079] In addition, the lithium metal oxide according to the present invention has an average internal pore size of 340 nm 2 It could be more than that. Specifically, 343 nm 2 to 520 nm 2 It could be, and more specifically 346 nm 2 to 500 nm 2 , 348 nm 2 to 480 nm 2 or 350 nm 2 to 450 nm 2 It could be. By ensuring a sufficient internal pore size within the lithium metal oxide within the above range, the internal pores provide a sufficient effective area as a lithium ion diffusion path, thereby improving lithium ion mobility and improving initial efficiency, capacity, and rate characteristics. More specifically, if the average internal pore size of the lithium metal oxide is below the above lower limit, the pore size is too small, which restricts the diffusion path, and consequently, a decrease in initial efficiency, insufficient capacity, and reduced rate characteristics may occur. On the other hand, if it exceeds the above upper limit, the non-uniformity of the internal reaction interface increases and structural stability decreases, which may lead to problems such as increased consumption of active lithium, a decrease in initial efficiency, and a decrease in rate characteristics.

[0080] Meanwhile, the average internal pore size of lithium metal oxides has some correlation with the internal porosity, which refers to the ratio of the pore area within the lithium metal oxide, but this correlation is not strictly observed. In other words, even if the internal porosity of the lithium metal oxide is high, the average internal pore size can be small or large.

[0081] In this specification, “average internal pore size” refers to the area of ​​pores formed inside manufactured positive electrode active material particles and can be calculated through image analysis based on FIB-SEM cross-sectional images. Specifically, in this embodiment, the “average internal pore size” may be calculated by cutting manufactured positive electrode active material particles by FIB (Focused Ion Beam) milling to obtain a cross-sectional SEM image, measuring the internal pore area within the cut cross-section using image software, and then calculating the internal pore area for 30 random positive electrode active material particles within the positive electrode active material powder in the same manner and calculating the average value.

[0082] In addition, the lithium metal oxide according to the present invention may have an average internal pore sphericity of 0.70 to 0.95. More specifically, it may be 0.70 to 0.92 or 0.70 to 0.88, and preferably 0.72 to 0.85. When the average internal pore sphericity of the lithium metal oxide is controlled within the above range, the internal pores maintain a uniform shape without distortion, thereby maximizing lithium ion mobility and improving initial efficiency, capacity, and rate characteristics. More specifically, if the average internal pore sphericity of the lithium metal oxide is below the lower limit value, the pores are formed with an irregular shape, resulting in the formation of inefficient lithium ion diffusion paths, which may lead to a decrease in initial efficiency and rate characteristics. On the other hand, if it exceeds the upper limit value, the pores become excessively spherical, which may reduce the pore area and pore connectivity, and consequently, the lithium ion movement paths may not be sufficiently secured, which may lead to a decrease in initial efficiency and rate characteristics.

[0083] Meanwhile, the average internal pore sphericity of lithium metal oxides has little correlation with the internal porosity of lithium metal oxides, and the range of internal sphericity can vary significantly depending on lithium and manganese-excess lithium metal oxides.

[0084] In this specification, “average internal pore sphericity” refers to the squared value of the ratio of the circumference of a circle having the same area as the internal pore to the circumference of a pore formed inside a manufactured positive electrode active material particle, and can be calculated through image analysis based on a FIB-SEM cross-sectional image. Specifically, in this embodiment, the “average internal pore sphericity” may be calculated by cutting a manufactured positive electrode active material particle by FIB (Focused Ion Beam) milling to obtain a cross-sectional SEM image, measuring the internal pore sphericity within the cut cross-section using image software, and then calculating the internal pore sphericity for 30 random positive electrode active material particles in the positive electrode active material powder using the same method and calculating the average value.

[0085] In addition, the lithium metal oxide according to the present invention may have an average internal porosity of 3.4% to 10.0%. More specifically, it may be 3.4% to 9.8% or 3.5% to 9.5%, and preferably 3.6% to 9.2%. When the average internal porosity of the lithium metal oxide satisfies the above range, excellent initial efficiency, capacity, and rate characteristics can be realized while ensuring structural stability. More specifically, if the average internal porosity of the lithium metal oxide is below the lower limit value, lithium ion mobility is reduced, which may result in reduced initial efficiency and capacity. On the other hand, if it exceeds the upper limit value, structural stability is reduced, which may result in inferior lifespan characteristics.

[0086] In this specification, “average internal porosity” refers to the ratio of the total area of ​​pores formed inside the manufactured positive electrode active material particles to the total area of ​​the cut cross-section, and can be calculated through image analysis based on FIB-SEM cross-sectional images. Specifically, in this embodiment, the “average internal porosity” may be calculated by cutting the manufactured positive electrode active material particles by FIB (Focused Ion Beam) milling to obtain a cross-sectional SEM image, measuring the ratio of the total area of ​​internal pores to the total area of ​​the cut cross-section using image software, and then calculating the internal porosity for 30 random positive electrode active material particles within the positive electrode active material powder in the same manner and calculating the average value.

[0087] In addition, the lithium metal oxide according to the present invention has an average standard deviation of internal pore size of 114 to 170 nm 2 It may be. More specifically, 118 to 165 nm 2 or 120 to 160 nm 2 It may be, preferably 125 to 150 nm 2 It may be possible. When the average of the standard deviation of the internal pore size of the lithium metal oxide satisfies the above range, excellent initial efficiency, capacity, and rate characteristics can be achieved while ensuring structural stability. More specifically, if the average of the standard deviation of the internal pore size of the lithium metal oxide is below the above lower limit, lithium ion mobility is reduced, which may result in reduced initial efficiency and capacity. On the other hand, if it exceeds the above upper limit, structural stability is reduced, which may result in inferior lifespan characteristics.

[0088] In this specification, “average of standard deviation of internal pore size” refers to an indicator that quantitatively represents the uniformity of the size distribution of individual internal pores formed inside manufactured positive electrode active material particles, and can be calculated through image analysis based on FIB-SEM cross-sectional images. Specifically, in this embodiment, the “average of standard deviation of internal pore size” may be calculated by cutting the manufactured positive electrode active material particles by FIB (Focused Ion Beam) milling to obtain cross-sectional SEM images, individually calculating the area of ​​each internal pore within the cut cross-section using image software, calculating the standard deviation from these internal pore area values ​​to derive the standard deviation of the internal pore size for one positive electrode active material particle, and then calculating the standard deviation of the internal pore size for 30 arbitrary positive electrode active material particles within the positive electrode active material powder using the same method and calculating the average value.

[0089] In one embodiment, the positive active material may satisfy the following Formula 1:

[0090] [Equation 1]

[0091] 79 < (Npore / Ppore) ≤ 112

[0092] (In Equation 1,

[0093] Npore is the average number of internal pores in lithium metal oxide, and

[0094] Ppore is the average internal porosity (%) of lithium metal oxide.

[0095] The above (Npore / Ppore) is an indicator representing whether internal pores within the cathode active material are formed with continuity and effectiveness as lithium ion diffusion pathways based on the porosity. In other words, it is a value that quantitatively evaluates whether the internal pore structure secures distribution characteristics capable of substantially contributing to lithium ion diffusion, even if the internal porosity is the same. By designing an internal pore structure that ensures a balance between porosity and the number of pores through the above indicator, it can be utilized as a design criterion to simultaneously improve initial efficiency, discharge capacity, and rate characteristics.

[0096] Specifically, the above (Npore / Ppore) may be 79.2 or higher, 79.4 or higher, or 79.6 or higher, or 111 or lower, 110 or lower, or 109 or lower. In this embodiment, the above (Npore / Ppore) may satisfy 79.8 ≤ (Npore / Ppore) ≤ 108.

[0097] As the above Equation 1 is satisfied, appropriate internal pore distribution characteristics relative to the porosity are secured, allowing the lithium ion diffusion path to be smoothly formed, and accordingly, the initial efficiency, initial discharge capacity, and rate characteristics can be improved.

[0098] In particular, if the value of (Npore / Ppore) is below the lower limit, the number of pores is insufficient, so a diffusion path is not sufficiently formed relative to the porosity, which may lead to a decrease in lithium ion mobility and a deterioration in initial efficiency, capacity characteristics, and rate characteristics. On the other hand, if the value of (Npore / Ppore) exceeds the upper limit, the number of pores relative to the porosity increases excessively, causing the internal pore structure to become excessively fine or non-uniformly distributed, which may lead to an increase in side reactivity within the electrode and a decrease in the uniformity of the internal reaction interface, thereby degrading the initial efficiency and rate characteristics.

[0099] In one embodiment, the positive active material may satisfy the following Formula 2:

[0100] [Equation 2]

[0101] 2500 ≤ {ln(Npore)*Apore / Cpore} ≤ 4500

[0102] (In Equation 2,

[0103] Npore is the average number of internal pores in lithium metal oxide, and

[0104] Apore is the average internal pore size (nm) of lithium metal oxide. 2 ) and,

[0105] Cpore refers to the average internal pore sphericity of lithium metal oxides).

[0106] The above {ln(Npore)*Apore / Cpore} is an indicator that quantifies the balance between pore activity and pore shape stability within the cathode active material. That is, the indicator represents whether the internal pore structure of the lithium metal oxide possesses effective activity capable of contributing to lithium ion diffusion, while suppressing pore shape distortion to ensure a pore structure suitable for enhancing electrochemical reactivity. By optimizing the internal pore structure of the cathode active material through this indicator, it can be utilized as a design criterion to achieve improvements in initial efficiency, discharge capacity, and rate characteristics.

[0107] Specifically, the above {ln(Npore)*Apore / Cpore} may be 2550 or more, 2600 or more, or 2700 or more, or 4300 or less, 4100 or less, or 3800 or less. In this embodiment, the above {ln(Npore)*Apore / Cpore} may satisfy 2900 ≤ {ln(Npore)*Apore / Cpore} ≤ 3600.

[0108] By satisfying Equation 2 above, pore activity based on the number and size of internal pores and shape stability based on sphericity are secured in balance, thereby ensuring a sufficient lithium ion diffusion path while suppressing excessive surface reactions, so that initial efficiency, capacity characteristics, and rate characteristics can be improved simultaneously.

[0109] In particular, if the value of {ln(Npore)*Apore / Cpore} is below the lower limit, the number or size of internal pores may be insufficient or the pore network may not be sufficiently developed, thereby restricting the lithium ion diffusion pathway and, as a result, the initial efficiency, initial capacity, and rate characteristics may be degraded. On the other hand, if the value of {ln(Npore)*Apore / Cpore} exceeds the upper limit, the pore activity may increase excessively due to the number and size of internal pores, or the sphericity may decrease, causing the internal pore shape to become excessively irregular; consequently, surface reactivity may increase and the internal reaction interface may be formed unevenly. As a result, electrochemical properties such as reduced initial efficiency, increased gas generation, increased consumption of active lithium, and reduced rate characteristics may occur.

[0110] In one embodiment, the positive active material may satisfy the following Formula 3:

[0111] [Equation 3]

[0112] 31 ≤ (Apore / D50) ≤ 60

[0113] (In Equation 3,

[0114] Apore is the average internal pore size (nm) of lithium metal oxide. 2 ) and,

[0115] D50 is the average particle size (D50) (μm) of the lithium metal oxide.

[0116] The above Apore / D50 is an indicator that quantifies the relative contribution of the internal pore size to the average particle size (D50). That is, the above indicator is a value that quantitatively represents the effect of the balance between the internal pore size and the average particle size (D50) on electrochemical reactivity. Through the above indicator, criteria for designing the internal pore structure to secure a sufficient diffusion path without excessive pore formation can be obtained.

[0117] Specifically, the above Apore / D50 is 31 nm 2 / μm or greater, 32 nm 2 / μm or greater or 33 nm 2 / μm or greater or 55 nm 2 / μm or less, 50 nm 2 / μm or less or 45 nm 2 It may be / μm. In this embodiment, the Apore / D50 may satisfy 34≤Apore / D50 ≤43.

[0118] By satisfying Equation 3 above, the ratio of the internal pore size to the total size of the lithium metal oxide particles is further optimized, and the lithium ion mobility is further optimized, so that the initial efficiency and capacity enhancement effects can be more preferably realized.

[0119] Meanwhile, the lithium metal oxide according to the present invention may have a molar ratio of lithium to lithium metal oxide of 1.08 to 1.3. More specifically, it may be introduced such that the ratio is 1.1 to 1.28 or 1.12 to 1.25. As the lithium content increases, the amount of lithium involved in the insertion and extraction of lithium ions increases, thereby improving capacity characteristics. However, if the lithium content becomes too high, a problem with phase stability may occur due to the excessive occurrence of oxygen oxidation / reduction reactions, which may lead to a decrease in lifespan characteristics.

[0120] In addition, the lithium metal oxide according to the present invention may have a molar ratio of nickel to the total metal excluding lithium of 0.2 to 0.4. More specifically, it may be 0.22 to 0.38 or 0.25 to 0.36. When the nickel content satisfies the above range, the capacity, output, and lifespan characteristics of the battery can be more preferably realized. If the nickel content is too low, the amount of oxygen oxidation / reduction reaction increases too much, and the lifespan characteristics may deteriorate. If the nickel content is too high, the amount of oxygen oxidation / reduction reaction decreases, and the capacity and output characteristics may deteriorate.

[0121] In addition, the lithium metal oxide according to the present invention may have a molar ratio of manganese to the total metal excluding lithium of 0.5 to 0.75. More specifically, it may be 0.55 to 0.72 or 0.6 to 0.7. If the manganese content is too low, manufacturing costs increase, the safety of the active material decreases, and the capacity improvement effect due to the excessive manganese content may be negligible. If the manganese content is too high, lifespan characteristics deteriorate due to the excessive use of oxygen oxidation / reduction reactions, and there may be a problem of manganese leaching.

[0122] In addition, the lithium metal oxide according to the present invention may have a molar ratio of cobalt to the total metal excluding lithium of 0.2 or less, more specifically 0.1 or 0.05 or less, and may not contain cobalt. In the present invention, even if the cobalt content is reduced to the above range, good lifespan or output characteristics can be achieved.

[0123] More specifically, the lithium metal oxide according to the present invention can be represented by the following chemical formula 1.

[0124] [Chemical Formula 1]

[0125] Li 1+a (Ni x Co y Mn z M w ) 1-a O2

[0126] In the above chemical formula 1, 0.08≤a≤0.3, 0.2≤x≤0.4, 0≤y≤0.2, 0.5≤z≤0.75, 0≤w≤0.2, x+y+z+w=1, and M is Zr, Al, B, Y, Mg, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir, or a combination thereof.

[0127] In the lithium transition metal oxide of Chemical Formula 1 above, lithium may be included in an amount corresponding to 1+a, where a may be 0.08≤a≤0.3. If a is too small, the effect of improving capacity characteristics due to the excess lithium content may be negligible. However, if a is too large, lifespan characteristics may deteriorate due to reduced phase stability.

[0128] In the lithium transition metal oxide of Chemical Formula 1 above, nickel may be included in an amount corresponding to x, i.e., 0.2 ≤ x ≤ 0.4. If the nickel content is too low, the amount of oxygen oxidation / reduction reaction increases too much, and the lifespan characteristics may deteriorate. If the nickel content is too high, the amount of oxygen oxidation / reduction reaction decreases, and the capacity and output characteristics may deteriorate.

[0129] In the lithium transition metal oxide of Chemical Formula 1 above, cobalt may be included in an amount corresponding to y, i.e., 0 ≤ y ≤ 0.2. If the cobalt content is too low, it may be difficult to simultaneously achieve sufficient rate characteristics and high powder density of the active material. If the cobalt content is too high, the cost of the raw material increases overall and the reversible capacity may decrease.

[0130] In the lithium transition metal oxide of Chemical Formula 1 above, manganese may be included in an amount corresponding to z, i.e., 0.5≤z≤0.75. If the manganese content is too low, the production cost may increase, the stability of the active material may decrease, and the capacity may deteriorate. If the manganese content is too high, there may be a decrease in lifespan characteristics due to excessive use of oxygen oxidation / reduction reactions and a problem with manganese leaching.

[0131] In the lithium transition metal oxide of Chemical Formula 1 above, the other doping element M may be included in an amount corresponding to w, i.e., 0≤w≤0.2. The content of the doping element may be appropriately selected and controlled to achieve a doping effect within a range that does not degrade electrochemical properties. At this time, M may be Zr, Al, B, Y, Mg, Ti, Nb, W, Sc, Si, V, Fe, Y, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir, or a combination thereof.

[0132] The tap density of the above lithium metal oxide is 1.7 to 2.3 g / cm³ 3 It may be. More specifically, 1.75 to 2.25 g / cm³ 3 or 1.8 to 2.2 g / cm³ 3 It may be, preferably 1.85 to 2.18 g / cm³ 3 It may be possible. If the tap density of the lithium metal oxide satisfies the above range, both the energy density of the electrode and the battery output characteristics can be well realized. If the tap density of the lithium metal oxide exceeds the above upper limit, the battery output characteristics may deteriorate. On the other hand, if it is below the above lower limit, it may be difficult to realize high-energy anode density, and grain cracks may occur during rolling.

[0133] In this specification, “tap density” refers to a method for measuring the degree of packing of a sample per unit volume, which can be measured using a method generally used in the industry. Specifically, in this embodiment, “tap density” may be measured using a tap density meter of GEOPYC 1365 (Micromeritics), and may be calculated as a density by filling about 10 g of the manufactured cathode active material into a cylinder mold with a diameter of 19.1 mm, compressing it by applying a horizontal load of 108 N, and repeating the same conditions twice.

[0134] The BET specific surface area of ​​the above lithium metal oxide is 1.5 to 2.3 m² 2 It can be / g. More specifically, 1.7 to 2.28 m 2 / g or 1.8 to 2.25 m 2 It may be / g, preferably 1.85 to 2.2 m 2 / g. If the BET specific surface area of ​​the lithium metal oxide satisfies the above range, the electrolyte can penetrate smoothly into the cathode active material, improving the mobility of Li+ ions and securing rate characteristics. If the BET specific surface area of ​​the lithium metal oxide exceeds the above upper limit, side reactions with the electrolyte may intensify, leading to a decrease in lifespan characteristics. On the other hand, if it is below the above lower limit, the diffusion resistance of Li ions increases, which may result in a decrease in rate characteristics and initial discharge capacity.

[0135] In this specification, “specific surface area” refers to the surface area per unit mass of the active material powder and can be measured using the BET method commonly used in the industry. Specifically, in this embodiment, the “specific surface area” can be measured using the BET method (Surface area and Porosity analyzer) (Macsorb, HM Model-1200) for the active material powder.

[0136] The average particle size (D50) of the lithium metal oxide may be 8 to 12 μm. More specifically, it may be 8.5 to 11.5 μm or 9 to 11 μm, and preferably 9.5 to 10.5 μm. When the average particle size (D50) of the lithium metal oxide satisfies the above range, the mobility of Li+ ions can be improved and the charge transfer resistance can be reduced. If the average particle size (D50) of the lithium metal oxide exceeds the above upper limit, the mobility of atoms within the battery may be hindered due to the high resistance of the lithium excess oxide material itself, which may result in a decrease in capacity and output characteristics. On the other hand, if it is below the above lower limit, side reactions with the electrolyte may intensify, leading to a decrease in lifespan characteristics.

[0137] In this specification, the average particle size (D50) may be defined as the particle size corresponding to 50% of the volume accumulation in the particle size distribution curve. The average particle size (D50) may be measured, for example, using a laser diffraction method.

[0138]

[0139] Method for manufacturing positive electrode active material

[0140] A method for manufacturing a positive electrode active material for a lithium secondary battery according to another embodiment of the present invention comprises: a step of mixing a nickel raw material, a manganese raw material, and a solvent to form a metal-containing solution; a step of introducing the metal-containing solution, a complexing agent-containing solution, and a pH adjusting agent-containing solution into a reactor to form a reaction solution; a step of co-precipitating the reaction solution to form a metal precursor having a molar ratio (Mn / Me) of manganese (Mn) to the total metal (Me) of 0.5 or more; and a step of mixing the metal precursor and the lithium raw material, and then calcining to form a lithium metal oxide having an excess composition of lithium and manganese; wherein the specific surface area (BET) of the metal precursor is 26 to 38 m² 2 / g is.

[0141]

[0142] Hereinafter, a method for manufacturing a positive electrode active material according to one embodiment of the present invention will be described step by step.

[0143]

[0144] The internal pore morphology of the lithium metal oxide according to the present invention can be controlled by appropriately implementing the morphology and physical properties of the precursor in the manufacturing method.

[0145] In particular, the present invention controls the morphology of internal pores of a lithium metal oxide with an excess composition of lithium and manganese by controlling the specific surface area of ​​a metal precursor, thereby easily obtaining the average number of internal pores, average internal pore size, average internal pore sphericity, average internal porosity, and the average of the standard deviation of internal pore size within the lithium metal oxide within the range according to the present invention, and can satisfy Equations 1 to 3.

[0146] More specifically, the positive electrode active material of the present invention comprises a lithium metal oxide in which the molar ratio of lithium (Li) to the total metal (Me) excluding lithium (Li / Me) is greater than 1, and the molar ratio of manganese (Mn) to the total metal (Me) excluding lithium (Mn / Me) is greater than 0.5. That is, the lithium metal oxide may be in the form of secondary particles formed by the aggregation of a plurality of primary particles, with an excess composition of lithium and manganese.

[0147]

[0148] First, nickel raw material, manganese raw material, and a solvent are mixed to form a metal-containing solution.

[0149] When mixing the above, additional cobalt raw materials may be mixed as needed.

[0150] The above nickel raw material is not particularly limited as long as it is used in the industry for the manufacture of cathode active material precursors. For example, the above nickel raw material may be nickel-containing sulfates, acetates, nitrates, halides, sulfides, hydroxides, oxides, or oxyhydrooxides, and specifically, may be NiSO4, NiSO4·6H2O, Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, nickel fatty acid salts, nickel halides, or combinations thereof, but is not limited thereto.

[0151] The above manganese raw material is not particularly limited as long as it is used in the industry for the manufacture of cathode active material precursors. For example, the above manganese raw material may be a manganese-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof. Specifically, it may be a manganese salt such as MnSO4, MnCO3, Mn(NO3)2, manganese acetate, manganese dicarboxylate, manganese citrate, and manganese fatty acid, manganese oxide such as Mn2O3, MnO2, and Mn3O4, oxyhydroxide, manganese chloride, or a combination thereof, but is not limited thereto.

[0152] The above-mentioned cobalt raw material is not particularly limited as long as it is used in the industry for the manufacture of cathode active material precursors. For example, the above-mentioned cobalt raw material may be a cobalt-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically, may be CoSO4, CoSO4·7H2O, Co(OH)2, CoOOH, Co(OCOCH3)2·4H2O, Co(NO3)2·6H2O, or a combination thereof, but is not limited thereto.

[0153] The above solvent is not particularly limited as long as it is capable of dissolving the metal raw materials, but, for example, it may be water.

[0154] At this time, the molar ratio of nickel, cobalt, and manganese in the precursor can be controlled by adjusting the concentrations of the nickel raw material, the cobalt raw material, and the manganese raw material. Accordingly, the content of nickel, cobalt, and manganese in the metal precursor can be controlled to the range according to the present invention mentioned above.

[0155]

[0156] Next, the metal-containing solution, the complexing agent-containing solution, and the pH adjuster-containing solution are introduced into a reactor to form a reaction solution.

[0157] The above-mentioned complexing agent-containing solution performs the role of forming a complex, and may include, for example, NH3, NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, NH4CO3, or a combination thereof as the complexing agent, but is not limited thereto. Meanwhile, the above-mentioned complexing agent-containing solution may be used in the form of an aqueous solution, and in this case, water or a mixture of water and an organic solvent that is uniformly miscible with water (e.g., alcohol, etc.) may be used as the solvent.

[0158] The above-mentioned solution containing a pH adjuster performs the role of a precipitating agent or a pH adjuster and may include alkali compounds such as hydroxides of alkali metals or alkaline earth metals like NaOH, KOH, or Ca(OH)2, their hydrates, or combinations thereof. Meanwhile, the above-mentioned solution containing a pH adjuster may also be used in the form of an aqueous solution, in which case water or a mixture of water and an organic solvent that is uniformly miscible with water (e.g., alcohol) may be used as the solvent.

[0159] Next, the above reaction solution is subjected to a co-precipitation reaction to form a metal precursor.

[0160] The above co-precipitation reaction can be carried out by stirring the reaction solution.

[0161] At this time, the above co-precipitation reaction can be carried out under an inert atmosphere such as nitrogen or argon.

[0162] In addition, the above co-precipitation reaction can be performed at a temperature of 30 to 70°C, and more specifically, at a temperature of 40 to 60°C. When the co-precipitation reaction temperature is controlled within the above range, reaction activity is secured at a temperature sufficiently higher than room temperature while suppressing excessive particle surface reactions, thereby stably maintaining the compositional uniformity of the precursor and the primary particle growth behavior. This allows the lithium and manganese excess compositional structure formed during the subsequent calcination step to be stabilized. As a result, the initial efficiency and lifespan characteristics of the cathode active material can be comprehensively improved.

[0163] In addition, the pH of the reaction solution during the above co-precipitation reaction can be controlled to 10.0 to 12.0. When the pH of the reaction solution satisfies the above range, the initial efficiency and capacity characteristics of the cathode active material can be comprehensively improved.

[0164] By the above process, particles of nickel-manganese (-cobalt-doping element) hydroxide are generated and precipitated in the reaction solution. The precipitated precursor particles can be separated by conventional methods, washed, and dried to obtain a precursor. The precursor may be a secondary particle formed by the aggregation of primary particles.

[0165] At this time, the molar ratio of nickel and manganese in the precursor can be controlled by adjusting the concentrations of the nickel raw material and the manganese raw material. Accordingly, the content of nickel and manganese in the metal precursor can be controlled to the range according to the present invention mentioned above.

[0166] Accordingly, the molar ratio of manganese (Mn) to the total metal (Me) in the metal precursor (Mn / Me) may be 0.5 to 0.75. Additionally, the molar ratio of nickel (Ni) to the total metal (Me) (Ni / Me) may be 0.2 to 0.4. Furthermore, the molar ratio of cobalt (Co) to the total metal (Me) in the metal precursor (Co / Me) may be 0.2 or less, specifically 0.1 or less, 0.08 or less, or 0.05 or less, and more specifically, may not contain cobalt in the metal precursor. The technical significance of controlling the content of each metal is as described above and is therefore omitted.

[0167] Meanwhile, the doping element may also be doped during the preparation stage of the cathode active material precursor. In this case, the doping element may be doped into the metal precursor by additionally adding a doping raw material to the metal-containing solution and causing a co-precipitation reaction. For example, a doping raw material comprising at least one of Zr, Al, B, Y, Mg, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, and Ir may be used.

[0168] The specific surface area (BET) of the metal precursor according to one embodiment of the present invention is 26 to 38 m² 2 It is / g. More specifically, 26 to 36 m 2 / g or 26 to 34 m 2 It may be / g, preferably 26 to 33 m 2 / g. When the BET specific surface area of ​​the metal precursor satisfies the above range, sufficient pore formation can be induced without the surface reactivity of the metal precursor increasing excessively, so that in the subsequent calcination process, the average number of internal pores, average internal pore size, average internal pore sphericity, average internal porosity, and the average of the standard deviation of internal pore size in the lithium metal oxide can be easily obtained within the range according to the present invention, and can satisfy Equations 1 to 3.

[0169] If the specific surface area (BET) of the metal precursor exceeds the upper limit, the surface reactivity becomes excessively large, leading to aggregation between precursor particles and the formation of irregular pores, and the internal pore development is insufficient, which may result in a decrease in initial efficiency and rate characteristics. On the other hand, if it is below the lower limit, the surface reactivity is insufficient, resulting in insufficient nucleation during the co-precipitation process, under-formation of internal pores or an increase in closed pores, which restricts the lithium ion diffusion pathway and may lead to inferior initial efficiency and capacity characteristics.

[0170] In one embodiment, the tap density of the metal precursor is 1.47 to 1.74 g / cm³ 3 It may be. More specifically, 1.50 to 1.74 g / cm³ 3 or 1.53 to 1.74 g / cm³ 3 It may be, preferably 1.55 to 1.73 g / cm³ 3 It may be possible. When the BET specific surface area of ​​the metal precursor satisfies the above range, the balance between the precursor packing and internal pores is properly secured, so that the particle shrinkage and growth process can proceed stably during subsequent calcination, and as a result, during the subsequent calcination process, the average number of internal pores, average internal pore size, average internal pore sphericity, average internal porosity, and the average of the standard deviation of internal pore size in the lithium metal oxide can be easily obtained within the range according to the present invention, and can satisfy Equations 1 to 3.

[0171] If the tap density of the metal precursor exceeds the upper limit value, the internal pores of the precursor are not sufficiently secured, and as particle shrinkage proceeds rapidly during the calcination process, problems may arise such as under-formation of internal pores or closure of the pore structure. Consequently, initial efficiency and rate characteristics may be reduced. On the other hand, if it is below the lower limit value, the internal pores of the precursor become excessively large, causing unstable aggregation between particles. During the calcination process, pores may grow excessively or become irregularly connected, resulting in an excessive distribution of porosity and number of pores, which may lead to reduced initial efficiency, increased consumption of active lithium, and reduced rate characteristics.

[0172] In one embodiment, the average particle size (D50) of the metal precursor may be 8 to 12 μm. More specifically, it may be 8.5 to 11.8 μm or 9 to 11.5 μm, and preferably 9.5 to 11.3 μm. When the average particle size (D50) of the metal precursor satisfies the above range, the packing structure between precursor particles and the internal pore distribution are formed in a balanced manner, so that particle shrinkage and crystal growth behavior can proceed stably during the subsequent calcination process. Accordingly, the average number of internal pores, average internal pore size, average internal pore sphericity and average internal porosity, and the average of the standard deviation of internal pore size in the lithium metal oxide can be easily controlled to the range according to the present invention.

[0173] If the average particle size (D50) of the metal precursor exceeds the upper limit value, the internal pore formation becomes uneven, which may lead to a decrease in initial efficiency and rate characteristics. On the other hand, if it is below the lower limit value, the pores grow excessively or become irregularly connected during the firing process, making it difficult to control the pore structure, and as a result, the initial efficiency and lifespan characteristics may be inferior.

[0174]

[0175] Next, the above metal precursor and lithium raw material are mixed and then calcined to produce a lithium metal oxide.

[0176] At this time, the lithium raw material may be introduced such that the molar ratio (Li / Me) of lithium (Li) to the total metal (Me) excluding lithium in the lithium metal oxide is 1.01 to 1.5. More specifically, it may be introduced such that it is 1.1 to 1.4 or 1.25 to 1.35. As the amount of lithium raw material introduced is controlled within the above range, the lithium content in the lithium metal oxide can be appropriately controlled within the range according to the present invention. Meanwhile, as the lithium content increases, the amount of lithium involved in the insertion and extraction of lithium ions increases, thereby improving capacity characteristics. However, if the lithium content becomes too high, problems with phase stability may occur due to the excessive occurrence of oxygen oxidation / reduction reactions, which may lead to a decrease in lifespan characteristics; therefore, it is desirable to satisfy the above range.

[0177] The above lithium raw material may be a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it is soluble in water. Specifically, the above lithium raw material may be Li2CO3, LiNO3, LiNO2, LiOH, LiOH·H2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, Li3C6H5O7, or a combination thereof, but is not limited thereto.

[0178] If necessary, additional doping raw materials may be added at this stage, for example, a doping raw material containing at least one of Zr, Al, B, Y, Mg, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir may be used.

[0179] The above calcination can be performed at 800 to 900°C, and more specifically at 810 to 890°C or 820 to 880°C. Additionally, the above calcination can be performed for 5 to 20 hours, and more specifically at 7 to 15 hours or 8 to 12 hours. If the calcination temperature or time satisfies the above range, a lithium metal oxide with an excess composition of lithium and manganese can be formed into a stable layered structure. If the calcination temperature or time is below the above lower limit, the layered lithium metal oxide is formed incompletely, and consequently, the electrochemical properties of the active material may be degraded. On the other hand, if the calcination temperature or time exceeds the above upper limit, crystal defects may occur due to under-calcination, which may degrade the electrochemical properties.

[0180] In the step of forming the lithium metal oxide, the calcination may be performed in an air or oxygen atmosphere. In particular, when calcination is carried out in an oxygen atmosphere, sufficient oxidation of the metal precursor occurs, allowing for better electrochemical properties to be realized.

[0181] Meanwhile, the doping element can be doped during the lithium metal oxide formation stage. Specifically, the doping element can be doped into the lithium metal oxide by additionally adding the doping raw material during the formation of the mixture and then calcining it.

[0182]

[0183] Positive electrodes and lithium secondary batteries

[0184] Another embodiment of the present invention provides a positive electrode for a lithium secondary battery comprising the aforementioned positive electrode active material.

[0185] More specifically, the anode may include an anode current collector and an anode active material layer disposed on the anode current collector and comprising the aforementioned anode active material.

[0186] The above positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the above positive current collector may typically have a thickness of 3 to 500 μm, and fine irregularities may be formed on the surface of the positive current collector to increase the adhesion of the positive active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0187] The above positive active material layer may include a binder and / or a conductive material together with the aforementioned positive active material.

[0188] At this time, the binder serves to improve adhesion between positive active material particles and adhesion between the positive active material and the positive current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof. One of these alone or a mixture of two or more may be used, but is not limited thereto. The binder may be included in an amount of 1 to 30 weight% based on the total weight of the positive active material layer.

[0189] In addition, the conductive material is used to impart conductivity to the electrode, and in the battery being constructed, any material that possesses electronic conductivity without causing chemical changes may be used without any particular limitations. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon fibers; metal powders or metal fibers such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide and potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives. One of these alone or a mixture of two or more may be used, but is not limited thereto. The conductive material may typically be included in an amount of 1 to 30 weight percent relative to the total weight of the positive electrode active material layer.

[0190] The above-mentioned anode can be manufactured according to a conventional anode manufacturing method, except for using the above-mentioned anode active material.

[0191] Specifically, the anode can be manufactured by applying a composition for forming an anode active material layer, comprising the aforementioned anode active material and optionally a binder, conductive material, or solvent as needed, onto an anode current collector, followed by drying and rolling. At this time, the types and contents of the anode active material, binder, and conductive material are as described above.

[0192] The above solvent may be a solvent commonly used in the relevant technical field, such as dimethylsulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of the above solvent used is sufficient if it has a viscosity that allows for the dissolution or dispersion of the anode active material, conductive material, and binder, taking into account the coating thickness of the slurry and the manufacturing yield, and subsequently provides excellent thickness uniformity when coated for anode manufacturing.

[0193] Alternatively, the anode may be manufactured by casting the composition for forming the anode active material layer onto a separate support and then laminating the film obtained by peeling off from the support onto an anode current collector.

[0194]

[0195] Another embodiment of the present invention provides a lithium secondary battery comprising a positive electrode for a lithium secondary battery as described above.

[0196] More specifically, the above lithium secondary battery may include a positive electrode; a negative electrode; a separator; and an electrolyte.

[0197] The above lithium secondary battery may optionally further include a battery container that accommodates the electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member that seals the battery container.

[0198] The above cathode may include a cathode current collector and a cathode active material layer located on the cathode current collector.

[0199] The above-mentioned negative current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., and aluminum-cadmium alloy may be used. In addition, the above-mentioned negative current collector may typically have a thickness of 3 to 500 μm, and, similar to the positive current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding strength of the negative active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0200] The above-mentioned cathode active material layer may optionally include a binder and a conductive material together with the cathode active material. The above-mentioned cathode active material layer may be manufactured, as an example, by applying a composition for forming a cathode active material layer, comprising a cathode active material and optionally a binder and a conductive material, onto a cathode current collector and drying it, or by casting the composition for forming a cathode onto a separate support and then laminating the film obtained by peeling it off from the support onto a cathode current collector.

[0201] As the above-mentioned negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; metal oxides capable of doping and dedoping lithium, such as SiOβ (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the above-mentioned metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or more of these may be used. Additionally, a metallic lithium thin film may be used as the above-mentioned negative electrode active material. Furthermore, the carbon material may include both low-crystallinity carbon and high-crystallinity carbon. Representative examples of low-crystallinity carbon include soft carbon and hard carbon, while representative examples of high-crystallinity carbon include amorphous, plate-like, flake-like, spherical, or fibrous natural or artificial graphite, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch-derived cokes.

[0202] The binder and conductive material mentioned above may be the same as those previously described in the anode.

[0203]

[0204] The above separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. It can be used without special restrictions as long as it is typically used as a separator in a lithium secondary battery, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte wettability. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like ethylene homopolymer, propylene homopolymer, ethylene / butene copolymer, ethylene / hexene copolymer, and ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof may be used. In addition, a conventional porous nonwoven fabric, such as a nonwoven fabric made of high-melting-point glass fiber or polyethylene terephthalate fiber, may be used. Furthermore, a coated separator containing ceramic components or polymer materials may be used to ensure heat resistance or mechanical strength, and it may optionally be used in a single-layer or multi-layer structure.

[0205]

[0206] The above electrolytes include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which can be used in the manufacture of lithium secondary batteries, but are not limited to these.

[0207] Specifically, the organic liquid electrolyte may include an organic solvent and a lithium salt.

[0208] The above organic solvent may be used without special restrictions as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the above organic solvent may include ester-based solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether-based solvents such as dibutyl ether or tetrahydrofuran; ketone-based solvents such as cyclohexanone; and aromatic hydrocarbon-based solvents such as benzene and fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), methyl ethyl carbonate (MEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol-based solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (where R is a straight-chain, branched, or cyclic hydrocarbon group having C2 to C20 structures and may include a double bond, a directional ring, or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes may be used. Among these, a carbonate-based solvent is preferred, and a mixture of a cyclic carbonate (e.g., ethylene carbonate or propylene carbonate, etc.) having high ionic conductivity and high dielectric constant that can improve the charge / discharge performance of the battery, and a low-viscosity linear carbonate-based compound (e.g., ethylmethyl carbonate, dimethyl carbonate or diethyl carbonate, etc.) is more preferred.In this case, using a mixture of cyclic carbonate and chain carbonate in a volume ratio of about 1:1 to about 1:9 can result in excellent performance of the electrolyte.

[0209] The above lithium salt can be used without special restrictions as long as it is a compound capable of providing lithium ions used in lithium secondary batteries. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, or LiB(C2O4)2. The concentration of the lithium salt is preferably used within the range of 0.1 to 2.0 M. When the concentration of the lithium salt falls within the above range, the electrolyte has appropriate conductivity and viscosity, so it can exhibit excellent electrolyte performance and allow lithium ions to move effectively.

[0210] In addition to the above electrolyte components, the above electrolyte may further include one or more additives for the purpose of improving the lifespan characteristics of the battery, suppressing the decrease in battery capacity, and improving the discharge capacity of the battery, such as, for example, haloalkylene carbonate-based compounds like difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyme, hexamethylphosphate triamide, nitrobenzene derivative, sulfur, quinone imine dye, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salt, pyrrole, 2-methoxyethanol, or aluminum trichloride. In this case, the additive may be included in an amount of 0.1 to 5 weight% based on the total weight of the electrolyte.

[0211] As described above, since the lithium secondary battery containing the positive electrode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention rate, it is useful in portable devices such as mobile phones, laptop computers, and digital cameras, as well as in the field of electric vehicles such as hybrid electric vehicles (HEVs).

[0212] Accordingly, another embodiment of the present invention provides a battery module comprising the lithium secondary battery as a unit cell and a battery pack comprising the same.

[0213] The above battery module or battery pack can be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0214]

[0215] The embodiments of the present invention will be described in more detail below through examples. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited by the following examples.

[0216]

[0217] Example 1

[0218] (1) Preparation of a positive electrode active material precursor

[0219] (Preparation of metal-containing solution) A 2.5 mol / L metal-containing solution was prepared by dissolving NiSO4·6H2O and MnSO4·H2O in distilled water. At this time, the molar ratio of Ni to Mn was set to 35:65.

[0220] After (co-precipitation), the metal-containing solution, an aqueous NH4(OH) solution of 15.3 mol / L as a complexing agent solution, and an aqueous NaOH solution of 8.0 mol / L as a pH adjusting agent solution were added to a co-precipitation reactor to form a reaction solution, and the co-precipitation reaction was carried out while stirring.

[0221] (Filtering, washing, and drying) Subsequently, the precipitate obtained according to the above co-precipitation reaction is filtered, washed with distilled water, and then vacuum dried in a 100°C oven for 24 hours to obtain Ni 0.35 Mn 0.65 A metal precursor of (OH)2 composition was prepared.

[0222] (2) Preparation of positive electrode active material

[0223] The above-mentioned metal precursor is mixed with LiOH·H2O as a lithium raw material so that the Li / Me(Ni+Mn) ratio is 1.31, and then calcined at 900°C for 10 hours under an air atmosphere to produce Li 1.14 Ni 0.30 Mn 0.56 A lithium metal oxide of O2 composition was prepared.

[0224] (3) Lithium secondary battery manufacturing

[0225] A CR2032 coin cell was manufactured using the manufactured positive electrode active material in the following manner.

[0226] Specifically, the slurry for manufacturing the electrode plate was prepared by mixing the above-prepared cathode active material, conductive material (carbon black, Denka black), and binder (PVDF, KF1100) in a ratio of 92.5 : 3.5 : 4 wt%, and NMP (N-Methyl-2-pyrrolidone) was added to adjust the viscosity so that the solid content concentration was approximately 30%. The prepared slurry was coated onto a 15 µm thick Al foil using a doctor blade, dried, and then rolled. At this time, the electrode loading amount was approximately 14 mg / cm². 2 It was.

[0227] A CR2032 coin cell was manufactured using an electrolyte of 1M LiPF6 in EC:EMC=3:7 (vol%) with 3.0 vol% FEC added relative to the total amount of the electrolyte, a PP separator, and a lithium anode (200 μm, Honzo metal).

[0228]

[0229] Examples 2-3 and Comparative Examples 1-4

[0230] A positive electrode active material and a lithium secondary battery were prepared in the same manner as in Example 1, except that the specific surface area, tap density, and average particle size of the positive electrode active material precursor were varied as shown in Table 1 below. (The composition of the metal precursor and the composition of the lithium metal oxide were kept exactly the same as in Example 1.)

[0231]

[0232] Table 1 below shows the physical properties of the metal precursors prepared in the examples and comparative examples.

[0233]

[0234] Specific surface area (BET) (m²) 2 / g)Tap density (g / cm²) 3 Average particle size (D50) (μm) Example 1 31.85 1.57 10.48 Example 2 32.98 1.73 9.76 Example 3 28.85 1.72 10.56 Comparative Example 1 13.06 1.98 10.35 Comparative Example 2 23.54 1.87 10.51 Comparative Example 3 25.55 1.75 10.06 Comparative Example 4 40.25 1.45 10.27

[0235]

[0236] Experimental Example 1: Evaluation of Physical Properties

[0237] (1) Tap density evaluation

[0238] The tap density of the cathode active material precursor and cathode active material prepared in the examples and comparative examples was measured using a GEOPYC 1365 (Micromeritics) tap density meter. Specifically, 10g each of the prepared active material precursor and active material powder were placed into a cylinder with a diameter of 19.1mm, and a force of 108N was applied horizontally. The density was measured by repeating this process twice, and the results are shown in Tables 2 and 3.

[0239] (2) Specific surface area evaluation

[0240] The specific surface area of ​​the cathode active material precursor and cathode active material prepared in the examples and comparative examples was measured using the BET method (Surface area and Porosity analyzer) (Micromeritics, ASAP2020), and the results are shown in Tables 2 and 3.

[0241] (3) Evaluation of particle size (D50)

[0242] For the cathode active material precursors and cathode active materials prepared in the examples and comparative examples, the particle size (D50) was measured using the laser diffraction method, and the results are shown in Tables 2 and 3.

[0243] At this time, the particle size (D50) can be defined as the particle size corresponding to 50% of the volume accumulation in the particle size distribution curve of each particle.

[0244]

[0245] Experimental Example 2: Cross-sectional SEM image of cathode active material after FIB milling

[0246] Cross-sectional SEM images of the cathode active materials prepared in the examples and comparative examples were obtained after FIB (Focused Ion Beam) milling using a SEM (Scanning Electron Microscopy) analysis device at 8k magnification under an acceleration voltage of 1.5 kV, and are shown in FIGS. 1, FIGS. 3, and FIGS. 5.

[0247] In this regard, Fig. 1 is a cross-sectional SEM image of a positive electrode active material prepared according to Example 1 after Focused Ion Beam (FIB) milling. Fig. 2 is a processed image of Fig. 1 processed using image software. Fig. 3 is a cross-sectional SEM image of a positive electrode active material prepared according to Example 2 after Focused Ion Beam (FIB) milling. Fig. 4 is a processed image of Fig. 3 processed using image software. Fig. 5 is a cross-sectional SEM image of a positive electrode active material prepared according to Comparative Example 1 after Focused Ion Beam (FIB) milling. Fig. 6 is a processed image of Fig. 5 processed using image software.

[0248] Referring to FIGS. 1 to 6, it can be seen that Examples 1 and 2 have a larger average number of internal pores and a larger average internal pore size in the lithium metal oxide compared to Comparative Example 1.

[0249]

[0250] Experimental Example 3: Evaluation of Internal Pore Morphology of Anode Active Material

[0251] (1) Average number of internal pores

[0252] The manufactured cathode active material particles were center-cut using Focused Ion Beam (FIB) milling, and the cross-section was obtained as an SEM image. Subsequently, a processed image was generated by color-coding the internal pores and the non-porous areas using image software. Based on this image, the total number of internal pores within the cut cross-section was measured using image software to calculate the number of internal pores for a single cathode active material particle.

[0253] Subsequently, using the same method, the number of internal pores for 30 randomly selected positive active material particles in the positive active material powder was calculated, and the average value was taken to measure the average number of internal pores of the positive active material.

[0254] (2) Average internal pore size

[0255] The manufactured cathode active material particles were center-cut using Focused Ion Beam (FIB) milling, and the cross-section was obtained as an SEM image. Subsequently, a processed image was produced by color-coding the internal pores and the non-porous areas using image software. Based on this image, the area of ​​each internal pore within the cut cross-section was calculated using image software, and the average of these values ​​was taken to determine the internal pore size for a single cathode active material particle.

[0256] Subsequently, using the same method, the internal pore size of 30 randomly selected positive active material particles in the positive active material powder was calculated, and the average value was taken to measure the average internal pore size of the positive active material.

[0257] (3) Average internal pore sphericity

[0258] The manufactured cathode active material particles were center-cut using Focused Ion Beam (FIB) milling, and the cross-section was obtained as an SEM image. Subsequently, a processed image was generated by color-coding the internal pores and the surrounding areas using image software. Based on this image, the sphericity of each internal pore within the cut cross-section was measured using image software, and the average of these measurements was calculated to determine the sphericity of a single cathode active material particle.

[0259] Specifically, the sphericity of the internal pore refers to the square of the ratio of the circumference of a circle having the same area as the internal pore to the circumference of the internal pore, and was calculated using the following mathematical formula 1.

[0260] [Mathematical Formula 1]

[0261] Circularity = (4ΠA) / P 2

[0262] (In the above mathematical formula 1,

[0263] A is the area of ​​the internal pore, and P is the perimeter of the internal pore).

[0264] Subsequently, the internal pore sphericity of 30 randomly selected positive active material particles in the positive active material powder was calculated using the same method, and the average value was taken to measure the average internal pore sphericity of the positive active material.

[0265] (4) Average internal porosity

[0266] The manufactured cathode active material particles were center-cut using Focused Ion Beam (FIB) milling, and the cross-section was obtained as an SEM image. Subsequently, a processed image was generated by color-coding the internal porous portions and the non-porous portions using image software. Based on this image, the internal porosity of a single cathode active material particle was calculated using image software by determining the ratio of the total internal pore area to the total cross-sectional area.

[0267] Subsequently, the internal porosity of 30 randomly selected positive active material particles in the positive active material powder was calculated using the same method, and the average value was taken to measure the average internal porosity of the positive active material.

[0268] (5) Average of the standard deviations of internal pore sizes

[0269] After cutting the center of the manufactured cathode active material particles using Focused Ion Beam (FIB) milling and obtaining a cross-section SEM image, image software was used to color-code the internal pores and other areas to produce a processed image. Subsequently, based on this image, the area of ​​each internal pore within the cut cross-section was calculated using image software, and the standard deviation was determined to calculate the standard deviation of the internal pore size for a single cathode active material particle.

[0270] Subsequently, using the same method, the standard deviation of the internal pore size for 30 randomly selected positive active material particles in the positive active material powder was calculated, and the average value was taken to measure the average of the standard deviations of the internal pore size of the positive active material.

[0271]

[0272] Experimental Example 4: Evaluation of Formulas 1 to 3

[0273] Formulas 1 to 3 were evaluated for the cathode active materials prepared in the examples and comparative examples, and the results are shown in Table 5 below.

[0274] [Equation 1]

[0275] 79 < (Npore / Ppore) ≤ 112

[0276] (In Equation 1,

[0277] Npore is the average number of internal pores in lithium metal oxide, and

[0278] Ppore is the average internal porosity (%) of lithium metal oxide.

[0279] [Equation 2]

[0280] 2500 ≤ {ln(Npore)*Apore / Cpore} ≤ 4500

[0281] (In Equation 2,

[0282] Npore is the average number of internal pores in lithium metal oxide, and

[0283] Apore is the average internal pore size (nm) of lithium metal oxide. 2 ) and,

[0284] Cpore refers to the average internal pore sphericity of lithium metal oxides).

[0285] [Equation 3]

[0286] 31 ≤ Apore / D50 ≤ 60

[0287] (In Equation 3,

[0288] Apore is the average internal pore size (nm) of lithium metal oxide.2 ) and,

[0289] D50 is the average particle size (D50) (μm) of the lithium metal oxide.

[0290]

[0291] Experimental Example 5: Evaluation of Electrochemical Characteristics of Lithium Secondary Battery

[0292] (1) Evaluation of initial (formation) capacity and efficiency

[0293] After fabricating the lithium secondary battery half cell, it was aged at 25°C for 10 hours, and then formation was performed at 45°C to maximize the initial oxygen generation. At this time, to evaluate the initial capacity, 200 mAh / g was set as the 1C reference capacity and charged to 4.65V with a constant current of 0.1C, then switched to a constant voltage and continued charging until the termination current reached 0.05C. After a 10-minute rest time following charging, discharge was performed until it reached 2V with a constant current of 0.1C and a 1C reference capacity of 200 mAh / g.

[0294] (2) Rate characteristics after 50 cycles (0.33C / 0.1C, %) evaluation

[0295] The rate characteristic (0.33C / 0.1C, %) was evaluated after 50 cycles by testing with a constant current of 0.33C.

[0296]

[0297] Analysis results

[0298] (1) Evaluation of the physical properties of the positive active material

[0299] Classification Average particle size (D50) (μm) Specific surface area (BET) (m² 2 / g)Tap density (g / cm²) 3 Example 1 10.07 2.175 11.871 Example 29.86 2.166 02.156 Example 3 10.3 12.136 41.919 Comparative Example 1 10.33 0.928 42.225 Comparative Example 2 10.212.000 92.193 Comparative Example 39.93 2.0918 2.167 Comparative Example 4 10.14 2.877 01.667

[0300] (2) Evaluation of internal pore morphology of the positive active material base material

[0301] Classification average, average number of internal pores, internal pore size (nm) 2 ) Average internal pore sphericity Average internal porosity (%) Average of the standard deviations of internal pore size (nm 2 Example 1 389412.650.7503.635143.02 Example 2 682.1373.340.7887.281131.45 Example 3 715.8352.150.7348.971144.38 Comparative Example 1 64.7313.370.6490.49100.65 Comparative Example 2 135.4311.410.6360.95111.70 Comparative Example 3 174.2300.780.6681.53110.42 Comparative Example 4 813.5413.420.61310.3174.09

[0302] (3) Formulas 1 to 3

[0303] Classification [Equation 1][Equation 2][Equation 3] Example 1 107 328 140.98 Example 2 9 4309 237.86 Example 3 80 315 434.16 Comparative Example 1 132 201 330.34 Comparative Example 2 14 3240 330.50 Comparative Example 3 114 232 330.29 Comparative Example 4 79 45 2030.29

[0304] (4) Evaluation of the electrochemical characteristics of lithium secondary batteries

[0305] Classification Initial Charge Capacity (mAh / g) Initial Discharge Capacity (mAh / g) Initial Efficiency (%) Rate Characteristics After 50 Cycles (0.33C / 0.1C, %) Example 1 297.8 275.8 92.6 93 Example 2 282.7 262.8 93 94.8 Example 3 286.4 267.8 93.5 95.1 Comparative Example 1 281.7 252.9 89.8 89.8 Comparative Example 2 281.6 257.6 90.2 90.4 Comparative Example 3 283.3 255.3 90.1 91.6 Comparative Example 4 301.2 261.9 87.0 96.2

[0306] Referring to Tables 1 to 5, it can be seen that in the case of Examples 1 and 3, in which the various properties related to the internal pore morphology of lithium metal oxide, including the average number of internal pores, average internal pore size, average internal pore sphericity, average internal porosity, and the average of the standard deviation of internal pore size, are appropriately controlled within the range according to the present invention, the initial efficiency and capacity, and the rate characteristics after 50 cycles are superior to those of Comparative Examples 1 to 3. In particular, in Examples 1 to 3, the average number of internal pores and the average internal porosity are sufficiently secured, while the average of the standard deviation of internal pore size does not increase excessively, so it is determined that lithium ion mobility and structural stability are simultaneously secured.

[0307] On the other hand, in the case of Comparative Examples 1 to 3, where the various physical properties related to pore morphology were not implemented within the range according to the present invention, the diffusion path of lithium ions was not sufficiently secured, and accordingly, the initial efficiency and initial discharge capacity were reduced, and the rate characteristics after 50 cycles also showed inferior results compared to the examples.

[0308] Meanwhile, in the case of Comparative Example 4, the average number of internal pores, average internal pore size, and overall internal porosity were relatively high, and the rate characteristics after 50 cycles were found to be at a higher level than those of the example. However, as the average internal pore sphericity was the lowest and the average of the standard deviations of the internal pore sizes exceeded the upper limit according to the present invention, the non-uniformity of the internal pore distribution increased, and as a result, side reactions with the electrolyte and initial irreversible reactions were intensified, and it can be confirmed that the initial efficiency was significantly reduced.

[0309]

[0310] Although preferred embodiments of the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and it is obvious that such modifications also fall within the scope of the present invention.

[0311] Therefore, the substantive scope of the present invention shall be defined by the appended claims and their equivalents.

Claims

1. A layered lithium metal oxide having an excess composition of lithium and manganese, and The above lithium metal oxide is a positive electrode active material for a lithium secondary battery having an average number of internal pores of 200 or more.

2. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery having an average number of internal pores of 220 to 800.

3. In Paragraph 1, The above lithium metal oxide has an average internal pore size of 340 nm 2 Lee Sang-in, positive electrode active material for lithium secondary batteries.

4. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery having an average internal pore sphericity of 0.70 to 0.

95.

5. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery having an average internal porosity of 3.4% to 10.0%.

6. In Paragraph 1, The above lithium metal oxide has an average standard deviation of internal pore size of 114 to 170 nm 2 Phosphorus, positive electrode active material for lithium secondary batteries.

7. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery satisfying Formula 1 below: [Equation 1] 79 < (Npore / Ppore) ≤ 112 (In Equation 1, Npore is the average number of internal pores in lithium metal oxide, and Ppore is the average internal porosity (%) of lithium metal oxide.

8. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery satisfying Formula 2 below: [Equation 2] 2500 ≤ {ln(Npore)*Apore / Cpore} ≤ 4500 (In Equation 2, Npore is the average number of internal pores in lithium metal oxide, and Apore is the average internal pore size (nm) of lithium metal oxide. 2 ) and, Cpore refers to the average internal pore sphericity of lithium metal oxides).

9. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery satisfying Formula 3 below: [Equation 3] 31 ≤ (Apore / D50) ≤ 60 (In Equation 3, Apore is the average internal pore size (nm) of lithium metal oxide. 2 ) and, D50 is the average particle size (D50) (μm) of the lithium metal oxide.

10. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery in which a phase belonging to the C2 / m space group and a phase belonging to the R3-m space group are in solid solution or composite.

11. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery comprising a LiMO2 phase (where M is Ni, Co, Mn, Zr, Al, B, Y, Mg, Na, Ga, Ce, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir or a combination thereof, and must include Ni and Mn) and a Li2MnO3 phase.

12. In Paragraph 1, The above lithium metal oxide is a positive electrode active material for a lithium secondary battery represented by the following chemical formula 1: [Chemical Formula 1] Li 1+a (Ni x Co y Mr z M w ) 1-a O2 (In the above chemical formula 1, 0.08≤a≤0.3, 0.2≤x≤0.4, 0≤y≤0.2, 0.5≤z≤0.75, 0≤w≤0.2, and x+y+z+w=1, M is Zr, Al, B, Y, Mg, Ti, Nb, W, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Mo, Ru, Ir, or a combination thereof).

13. A step of mixing nickel raw material, manganese raw material and a solvent to form a metal-containing solution; A step of forming a reaction solution by introducing the metal-containing solution, the complexing agent-containing solution, and the pH adjuster-containing solution into a reactor; A step of forming a metal precursor having a molar ratio (Mn / Me) of manganese (Mn) to the total metal (Me) of 0.5 or more by co-precipitating the above reaction solution; and The method includes the step of mixing the metal precursor and lithium raw material, and then calcining to form a lithium metal oxide having an excess composition of lithium and manganese. The specific surface area (BET) of the above metal precursor is 26 to 38 m² 2 Method for manufacturing a positive electrode active material for a lithium secondary battery, with a content of / g.

14. In Paragraph 13, The tap density of the above metal precursor is 1.47 to 1.74 g / cm³ 3 Method for manufacturing a positive electrode active material for a lithium secondary battery.

15. In Paragraph 13, A method for manufacturing a positive electrode active material for a lithium secondary battery, wherein the average particle size (D50) of the metal precursor is 8 to 12 μm.

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