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

Abstract

The present embodiments relate to a positive electrode material for a lithium secondary battery, and a lithium secondary battery comprising same. A positive electrode material for a lithium secondary battery, according to one embodiment, comprises: a first positive electrode active material comprising a first lithium metal oxide in which a molar ratio (Mn / M) of manganese (Mn) to total transition metal (M) is 0.5 or more; and a second positive electrode active material comprising a second lithium metal oxide in which a molar ratio (Mn / M) of manganese (Mn) to total transition metal (M) is 0.5 or more, wherein an average particle diameter (D50) of the first positive electrode active material is greater than that of the second positive electrode active material, and equation 1 may be satisfied. [Equation 1] 1.0 ≤ A / B ≤ 1.3 In equation 1, A is the BET specific surface area of the first positive electrode active material, and B is the BET specific surface area of the second positive electrode active material.

Description

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

[0001] The present invention relates to a cathode material for a lithium secondary battery and a lithium secondary battery including the same.

[0002] This application claims priority to Korean Patent Application No. 10-2024-0190996, filed on December 19, 2024, the entire contents of which are incorporated herein by reference.

[0003] 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.

[0004] In this regard, lithium manganese oxides with excess lithium and manganese are attracting attention as next-generation cathode active materials due to their very high capacity of over 240 mAh / g, and research on them is currently being actively conducted.

[0005] However, since lithium and manganese-excess lithium transition metal oxides utilize oxygen oxidation-reduction reactions in addition to the transition metal, oxygen on the surface or within the bulk is prone to emitting as oxygen gas. Consequently, dense, non-reactive, or low-reactivity spinel / rock salt structures can easily form within the particles, leading to increased structural instability and, consequently, problems such as reduced capacity and degraded output characteristics.

[0006] In this embodiment, we aim to provide a cathode material for a lithium secondary battery with excellent electrochemical characteristics such as capacity and output, and a lithium secondary battery including the same.

[0007] A cathode material for a lithium secondary battery according to one embodiment comprises: a first cathode active material comprising a first lithium metal oxide having a molar ratio (Mn / M) of manganese (Mn) to the entire transition metal (M) of 0.5 or more; and a second cathode active material comprising a second lithium metal oxide having a molar ratio (Mn / M) of manganese (Mn) to the entire transition metal (M) of 0.5 or more, wherein the average particle size (D50) of the first cathode active material is larger than the average particle size (D50) of the second cathode active material and may satisfy the following Equation 1.

[0008] [Equation 1]

[0009] 1.0 ≤ A / B ≤ 1.3

[0010] In the above Equation 1, A is the BET specific surface area of ​​the first positive active material, and B is the BET specific surface area of ​​the second positive active material.

[0011] The BET specific surface area of ​​the first positive active material is 1.8 to 2.8 m 2 It can be / g.

[0012] The BET specific surface area of ​​the second positive active material is 1.7 to 2.6 m² 2 / g can be.

[0013] In one embodiment, the anode material may satisfy the following Equation 2.

[0014] [Equation 2]

[0015] 0.82 ≤ C / D ≤ 1.0

[0016] In the above Equation 2, C is the grain size of the first positive active material and D is the grain size of the second positive active material.

[0017] The crystal grain size of the first positive active material may be in the range of 58.0 nm to 75 nm.

[0018] The crystal grain size of the second positive active material may be in the range of 64.0 nm to 80 nm.

[0019] The average particle size (D50) of the first positive active material may be in the range of 8㎛ to 15㎛.

[0020] The average particle size (D50) of the second positive active material may be in the range of 1㎛ to 5㎛.

[0021] The first lithium metal oxide above may be represented by the following chemical formula 1.

[0022] [Chemical Formula 1]

[0023] Li 1+a1 (Ni x1 Co y1 Mn z1 W b1 M1 c1 ) 1-a1 O 2-d1 A1 d1

[0024] In the above chemical formula 1, 0.1≤a1≤0.3, 0.35≤x1≤0.45, 0≤y1≤0.05, 0.45≤z1≤0.65, 0.001≤b1≤0.013, 0≤c1≤0.1, 0≤d1≤0.1, x1+y1+z1+b1+c1=1, M1 is B, Ti, Cr, Zr, Al, Y, Mg, Nb, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Ru, Ir or a combination thereof, and A1 is It is F, Cl, Br, I, or a combination thereof.

[0025] The above second lithium metal oxide may be represented by the following chemical formula 2.

[0026] [Chemical Formula 2]

[0027] Li 1+a2 (Ni x2 Co y2 Mn z2 W b2 M2 c2 ) 1-a2 O 2-d2 A2 d2

[0028] In the above chemical formula 2, 0.1≤a2≤0.3, 0.35≤x2≤0.45, 0≤y2≤0.05, 0.45≤z2≤0.65, 0.001≤b2≤0.013, 0≤c2≤0.1, 0≤d2≤0.1, x2+y2+z2+b2+c2=1, M2 is B, Ti, Cr, Zr, Al, Y, Mg, Nb, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Ru, Ir or a combination thereof, and A2 is It is F, Cl, Br, I, or a combination thereof.

[0029] In one embodiment, the first lithium metal oxide may include a first surface portion located on the surface, and the second lithium metal oxide may include a second surface portion located on the surface.

[0030] The first surface portion and the second surface portion may each include a B-containing compound and an Al-containing compound.

[0031] In the first positive electrode active material, the content of B may be 2000 ppm or less based on the entire first positive electrode active material.

[0032] In the first positive electrode active material, the content of Al may be 1000 ppm or less based on the entire first positive electrode active material.

[0033] In the second positive electrode active material, the content of B may be 2000 ppm or less based on the entire second positive electrode active material.

[0034] In the second positive electrode active material, the content of Al may be 1000 ppm or less based on the entire second positive electrode active material.

[0035] The weight ratio of the mixture of the first positive active material and the second positive active material (weight of the first positive active material:weight of the second positive active material) may be in the range of 5:5 to 7:3.

[0036] A positive electrode for a lithium secondary battery according to another embodiment may include a positive electrode active material according to one embodiment.

[0037] A lithium secondary battery according to another embodiment may include a positive electrode comprising a positive electrode active material according to one embodiment.

[0038] According to the present embodiment, by controlling the molar ratio of nickel and manganese to an appropriate range in a lithium manganese-based cathode active material with a high manganese content, and simultaneously doping tungsten, a cathode active material with excellent high-temperature capacity and output characteristics can be realized.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] Also, unless otherwise specified, % means weight %, and 1 ppm is 0.0001 weight %.

[0044] 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.

[0045] 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.

[0046]

[0047] Cathode material for lithium secondary batteries

[0048] A cathode material for a lithium secondary battery according to one embodiment comprises: a first cathode active material comprising a first lithium metal oxide having a molar ratio (Mn / M) of manganese (Mn) to the entire transition metal (M) of 0.5 or more; and a second cathode active material comprising a second lithium metal oxide having a molar ratio (Mn / M) of manganese (Mn) to the entire transition metal (M) of 0.5 or more, wherein the average particle size (D50) of the first cathode active material is larger than the average particle size (D50) of the second cathode active material and may satisfy the following Equation 1.

[0049] [Equation 1]

[0050] 1.0 ≤ A / B ≤ 1.3

[0051] In the above Equation 1, A is the BET specific surface area of ​​the first positive active material, and B is the BET specific surface area of ​​the second positive active material.

[0052] The cathode material of the present embodiment includes first and second cathode active materials having different average particle sizes (D50). When an electrode is implemented using a cathode material that mixes two types of cathode active materials having different average particle sizes (D50), the empty space between the cathode active materials with large average particle sizes (D50) can be occupied by the cathode active material with small average particle size (D50), thereby improving the rolling density of the electrode and enabling the realization of a lithium secondary battery with excellent energy density.

[0053] The above Equation 1 is derived using the BET specific surface area of ​​the first positive active material and the second positive active material. Equation 1 may be 1.0 to 1.3, and more specifically, may be 1.0 to 1.25 or 1.0 to 1.15. That is, the BET specific surface area of ​​the first positive active material with a large particle size may be greater than or equal to the BET specific surface area of ​​the second positive active material with a small particle size. When the value of Equation 1 satisfies the above range, the insertion and extraction reactions of lithium ions can be carried out more uniformly, and the charging and discharging speeds can be accelerated because the reaction area increases. In addition, when manufacturing an electrode using the positive material of the present embodiment, it is possible to maintain the electrochemical reaction while improving electrode density, thereby realizing a lithium secondary battery with excellent capacity and output characteristics.

[0054] In the cathode material of one embodiment, the first and second cathode active materials each include the first and second lithium metal oxides.

[0055] Here, the first and second metal oxides are manganese-excess compositions in which the molar ratio (Mn / M) of manganese (Mn) to the total transition metal (M) is 0.5 or higher.

[0056] Lithium transition metal oxides with an excess composition of lithium and manganese have a low nickel content, but during battery operation, they can involve oxidation / reduction reactions of anions (oxygen) as well as potential metals. Additionally, since excess lithium can 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, which can significantly improve capacity characteristics compared to conventional NCM cathode materials. Furthermore, it is economically advantageous because the content of relatively expensive nickel and cobalt can be reduced, while the content of inexpensive manganese can be increased. In other words, when the molar ratio of manganese to nickel satisfies the above range, it is possible to manufacture a cathode active material that is economically advantageous while also having excellent capacity and lifespan characteristics.

[0057] In addition, the first and second lithium metal oxides may each have a layered crystal structure and may be secondary particles formed by the aggregation of multiple primary particles.

[0058] 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.

[0059] In addition, “primary particle” refers to the smallest particle unit that is distinguished as a single mass when the cross-section of the positive active material is observed through a scanning electron microscope (SEM), and it may consist of a single crystal grain or multiple crystal grains.

[0060] In one embodiment, the BET specific surface area of ​​the first positive electrode active material is 1.8 to 2.8 m² 2 It can be / g, and more specifically 1.9 to 2.6m 2 / g or 1.95 to 2.5m 2 It can be / g.

[0061] The BET specific surface area of ​​the second positive active material is 1.7 to 2.6 m² 2 It can be / g, and more specifically 1.8 to 2.5 m 2 / g or 1.95 to 2.2 m 2 It can be / g.

[0062]

[0063] The inventors confirmed through experiments that when the BET specific surface area values ​​of the first and second cathode active materials in the cathode material of the present embodiment satisfy the above range, the capacity, lifespan, and output characteristics are maximized.

[0064] The cathode material of this embodiment may satisfy the following Equation 2.

[0065] [Equation 2]

[0066] 0.82 ≤ C / D ≤ 1.0

[0067] In the above Equation 2, C is the grain size of the first positive active material and D is the grain size of the second positive active material.

[0068] In this specification, “grain” refers to a distinct region in which atoms within a primary particle form a lattice structure in a specific direction. Additionally, in this specification, “grain size” can be estimated using peak broadening of XRD data and can be quantitatively calculated using the Scherr equation.

[0069] Equation 2 above is derived using the grain sizes of the first and second positive active materials, and the value of Equation 2 may be 0.82 to 1.0, and more specifically, 0.85 to 1.0 or 0.9 to 1.0. That is, the grain size of the first positive active material, which has a large particle size, may be smaller than or equal to the grain size of the second positive active material, which has a small particle size. When Equation 2 satisfies the above range, internal stress generated when volume changes are repeated during the charging and discharging process is evenly distributed, thereby reducing cracking and breakage of particles and improving structural stability. In addition, side reactions occurring at the contact surface with the electrolyte on the surface of the positive material can be dispersed, thereby improving the surface characteristics of the positive material through a side reaction suppression effect. Therefore, when the positive material of the present embodiment is applied, the lifespan of the lithium secondary battery can be improved and voltage reduction can be prevented.

[0070] More specifically, the crystal grain size of the first positive active material may be 58.0 nm to 75.0 nm, and more specifically, 60.0 nm to 75.0 nm or 60.0 nm to 70.0 nm.

[0071] The crystal grain size of the second positive active material may be 64.0 nm to 80.0 nm, and more specifically, 64.0 nm to 75.0 nm or 65.0 nm to 71.0 nm.

[0072] The inventors confirmed through experiments that when the crystal grain sizes of the first and second cathode active materials in the cathode material of the present embodiment satisfy the above range, the capacity, lifespan, and output characteristics are maximized.

[0073]

[0074] The average particle size (D50) of the first positive active material may be 8㎛ to 15㎛, and more specifically 9㎛ to 14㎛ or 10㎛ to 13㎛.

[0075] The average particle size (D50) of the second positive active material may be 1 μm to 5 μm, and more specifically, 1.5 μm to 4 μm or 2 μm to 3.5 μm.

[0076] In the cathode material of this embodiment, first and second cathode active material particles with different average particle sizes (D50) can be positioned in an appropriate distribution, and accordingly, the energy density of the lithium secondary battery can be improved.

[0077] Meanwhile, in this specification, the average particle size (D50) can be defined as the particle size corresponding to 50% of the volume accumulation in the particle size distribution curve. The average particle size can be measured, for example, using a laser diffraction method.

[0078] In the cathode material of one embodiment, the first lithium metal oxide may have the same composition or a different composition.

[0079] Specifically, the first lithium metal oxide can be represented by the following chemical formula 1.

[0080] [Chemical Formula 1]

[0081] Li 1+a1 (Nix1 Co y1 Mn z1 W b1 M1 c1 ) 1-a1 O 2-d1 A1 d1

[0082] In the above chemical formula 1, 0.1≤a1≤0.3, 0.35≤x1≤0.45, 0≤y1≤0.05, 0.45≤z1≤0.65, 0.001≤b1≤0.013, 0≤c1≤0.1, 0≤d1≤0.1, x1+y1+z1+b1+c1=1, M1 is B, Ti, Cr, Zr, Al, Y, Mg, Nb, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Ru, Ir or a combination thereof, and A1 is It is F, Cl, Br, I, or a combination thereof.

[0083] In the first lithium transition oxide of Chemical Formula 1 above, lithium may be included in an amount corresponding to 1+a1, where a1 may be 0.1≤a1≤0.3. If a1 is too small, the effect of improving capacity characteristics due to the excess lithium content may be negligible. However, if a1 is too large, the lifespan characteristics may deteriorate due to a decrease in phase stability.

[0084] In the first lithium metal oxide of Chemical Formula 1 above, nickel may be included in an amount corresponding to x1, i.e., 0.35≤x1≤0.45. 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.

[0085] In the first lithium metal oxide of the above chemical formula 1, cobalt may be included in an amount corresponding to y1, i.e., 0≤y1≤0.05. If the cobalt content is too high, the cost of the raw materials increases overall and the reversible capacity may decrease.

[0086] In the first lithium metal oxide of Chemical Formula 1 above, manganese may be included in an amount corresponding to z1, i.e., 0.45≤z1≤0.65. 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.

[0087] In the first lithium metal oxide of Chemical Formula 1 above, the other doping element M1 may be included in an amount corresponding to c1, i.e., 0≤c1≤0.1. 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, M1 may be B, Ti, Cr, Zr, Al, Y, Mg, Nb, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Ru, Ir, or a combination thereof.

[0088] A1 is an element that can substitute for the oxygen site in the first lithium metal oxide of Chemical Formula 1. A1 may be included in an amount corresponding to A1, i.e., 0 ≤ d1 ≤ 0.1. Here, A1 may be F, Cl, Br, I, or a combination thereof.

[0089] Next, in Chemical Formula 1, W (tungsten) is a doping element included in the first lithium metal oxide. As previously mentioned, lithium manganese oxides with excess lithium and manganese have the advantage of having a high theoretical capacity, but they are difficult to activate, so it is necessary to maximize the capacity.

[0090] In this embodiment, a lithium secondary battery with high energy density can be realized by doping tungsten into a lithium manganese-based oxide with excess lithium and manganese to induce the reduction of transition metals and activate the oxygen reaction.

[0091] W may be included in an amount corresponding to tungsten, i.e., 0.001≤b1≤0.013.

[0092] Specifically, the content of tungsten in the first lithium metal oxide may be 0.013 moles or less based on 1 mole of total metal excluding lithium, more specifically in the range of 0.001 mole to 0.013 moles, 0.001 mole to 0.010 moles, or 0.002 mole to 0.009 moles. In this embodiment, by doping tungsten, which is a high valence cation, to the above content range, the reduction of nickel, cobalt, and manganese can be induced to activate the oxygen reaction, and in this case, excellent capacity of the lithium secondary battery can be secured.

[0093] In one embodiment, the second lithium metal oxide can be represented by the following chemical formula 2.

[0094] [Chemical Formula 2]

[0095] Li 1+a2 (Ni x2 Co y2 Mn z2 W b2 M2 c2 ) 1-a2 O 2-d2 A2 d2

[0096] In the above chemical formula 2, 0.1≤a2≤0.3, 0.35≤x2≤0.45, 0≤y2≤0.05, 0.45≤z2≤0.65, 0.001≤b2≤0.013, 0≤c2≤0.1, 0≤d2≤0.1, x2+y2+z2+b2+c2=1, M2 is B, Ti, Cr, Zr, Al, Y, Mg, Nb, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Ru, Ir or a combination thereof, and A2 is It is F, Cl, Br, I, or a combination thereof.

[0097] In the second lithium transition oxide of Chemical Formula 2 above, lithium may be included in an amount corresponding to 1+a2, where a2 may be 0.1≤a1≤0.3. If a2 is too small, the effect of improving capacity characteristics due to the excess lithium content may be negligible. However, if a2 is too large, the lifespan characteristics may deteriorate due to a decrease in phase stability.

[0098] In the second lithium metal oxide of Chemical Formula 2 above, nickel may be included in an amount corresponding to x2, i.e., 0.35≤x2≤0.45. 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.

[0099] In the second lithium metal oxide of the above chemical formula 2, cobalt may be included in an amount corresponding to y2, i.e., 0≤y2≤0.05. If the cobalt content is too high, the cost of the raw materials increases overall and the reversible capacity may decrease.

[0100] In the second lithium metal oxide of Chemical Formula 2 above, manganese may be included in an amount corresponding to z2, i.e., 0.45≤z2≤0.65. 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.

[0101] In the second lithium metal oxide of Chemical Formula 2 above, the other doping element M2 may be included in an amount corresponding to c2, i.e., 0≤c2≤0.1. 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, M1 may be B, Ti, Cr, Zr, Al, Y, Mg, Nb, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Ru, Ir, or a combination thereof.

[0102] A2 is an element that can substitute for the oxygen site in the second lithium metal oxide of Chemical Formula 2. A2 may be included in an amount corresponding to A2, i.e., 0 ≤ d2 ≤ 0.1. Here, A2 may be F, Cl, Br, I, or a combination thereof.

[0103] Next, in Chemical Formula 2, W (tungsten) is a doping element included in the second lithium metal oxide. As mentioned above, lithium manganese oxides with excess lithium and manganese have the advantage of having a high theoretical capacity, but they are difficult to activate, so it is necessary to maximize the capacity.

[0104] In this embodiment, a lithium secondary battery with high energy density can be realized by doping tungsten into a lithium manganese-based oxide with excess lithium and manganese to induce the reduction of transition metals and activate the oxygen reaction.

[0105] W may be included in an amount corresponding to tungsten, i.e., 0.001≤b2≤0.013.

[0106] Specifically, the content of tungsten in the second lithium metal oxide may be 0.013 moles or less based on 1 mole of total metal excluding lithium, more specifically in the range of 0.001 mole to 0.013 moles, 0.001 mole to 0.010 moles, or 0.002 mole to 0.009 moles. In this embodiment, by doping tungsten, which is a high valence cation, to the above content range, the reduction of nickel, cobalt, and manganese can be induced to activate the oxygen reaction, and in this case, excellent capacity of the lithium secondary battery can be secured.

[0107] In one embodiment, the first lithium metal oxide may include a first surface portion located on the surface.

[0108] The second lithium metal oxide may include a second surface portion located on the surface.

[0109] The first surface portion and the second surface portion may each include a B-containing compound and an Al-containing compound.

[0110] Specifically, in the first positive electrode active material, the content of B may be 2000 ppm or less based on the entire first positive electrode active material, and more specifically, may be in the range of 100 ppm to 2000 ppm or 300 ppm to 1800 ppm.

[0111] When the content of B satisfies the above range, it improves ion conductivity, increases charging and discharging speeds, and suppresses side reactions between the surface of the positive active material and the electrolyte, which is highly advantageous for improving lifespan characteristics.

[0112] In the first positive electrode active material, the content of Al may be 1000 ppm or less based on the entire first positive electrode active material, and more specifically, may be 100 ppm to 1000 ppm, or 200 to 700 ppm. When the content of Al satisfies the above range, the deterioration of the layered structure into a spinel structure can be effectively suppressed. Since the layered structure facilitates the extraction and insertion of lithium ions, while the spinel structure does not allow for smooth movement of lithium ions, suppressing the deterioration of the layered structure into a spinel structure allows for smooth movement of lithium ions, and consequently, the lifespan characteristics of the battery can be effectively improved. In addition, the charge / discharge capacity can be increased while simultaneously improving output characteristics.

[0113] In the second positive electrode active material, the content of B may be 2000 ppm or less based on the entire second positive electrode active material, and more specifically, may be in the range of 100 ppm to 2000 ppm or 300 ppm to 1800 ppm.

[0114] When the content of B satisfies the above range, it improves ion conductivity, increases charging and discharging speeds, and suppresses side reactions between the surface of the positive active material and the electrolyte, which is highly advantageous for improving lifespan characteristics.

[0115] In the second positive electrode active material, the content of Al may be 1000 ppm or less based on the entire second positive electrode active material, and more specifically, may be 100 ppm to 1000 ppm, or 200 to 700 ppm. When the content of Al satisfies the above range, the deterioration of the layered structure into a spinel structure can be effectively suppressed. Since the layered structure facilitates the extraction and insertion of lithium ions, while the spinel structure does not allow for smooth movement of lithium ions, suppressing the deterioration of the layered structure into a spinel structure allows for smooth movement of lithium ions, and consequently, the lifespan characteristics of the battery can be effectively improved. In addition, the charge / discharge capacity can be increased while simultaneously improving output characteristics.

[0116] In this embodiment, the content of Al and B included in each of the first positive active material and the second positive active material may be the same or different.

[0117] In the cathode material of one embodiment, the mixed weight ratio of the first cathode active material and the second cathode active material (weight of the first cathode active material:weight of the second cathode active material) may be in the range of 5:5 to 7:3.

[0118] In this embodiment, when the mixing ratio of the first and second metal oxides satisfies the above range, a lithium secondary battery with excellent capacity and lifespan characteristics can be realized because the filling density is excellent and it satisfies an appropriate rolling density range when pressure is applied for electrode manufacturing. However, the mixing ratio of the first and second positive active materials can be appropriately adjusted according to the characteristics required for the lithium secondary battery.

[0119]

[0120] anode

[0121] In another embodiment, a positive electrode for a lithium secondary battery comprising a positive electrode active material according to one embodiment is provided.

[0122] The above positive electrode may include a current collector and a positive active material layer located on one side of the current collector, and the positive active material layer includes a positive active material of one embodiment.

[0123] The characteristics of the positive active material constituting the above positive active material layer are the same as those previously described. Therefore, a detailed description of the positive active material will be omitted.

[0124] The above current collector may be, for example, made of stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc.

[0125] Meanwhile, the above positive active material layer may include a binder and a conductive material.

[0126] 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.

[0127] In addition, the conductive material is used to impart conductivity to the electrode, and in the battery being constructed, it may be used without special limitations as long as it possesses electronic conductivity without causing chemical changes. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal black, and carbon 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, and 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% relative to the total weight of the positive electrode active material layer.

[0128] The above-mentioned anode can be manufactured according to a conventional anode manufacturing method, except for using the above-mentioned anode active material.

[0129] 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.

[0130] 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.

[0131] 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.

[0132]

[0133] lithium secondary battery

[0134] In another embodiment, a lithium secondary battery including the anode is provided.

[0135] Specifically, the lithium secondary battery may include a positive electrode, a negative electrode positioned opposite to the positive electrode, a separator interposed between the positive electrode and the negative electrode, and an electrolyte, wherein the positive electrode is as described above. Additionally, the lithium secondary battery may optionally further include a battery container housing an electrode assembly comprising the positive electrode, the negative electrode, and the separator, and a sealing member for sealing the battery container.

[0136] In the above lithium secondary battery, the negative electrode may include a negative electrode current collector and a negative electrode active material layer located on the negative electrode current collector.

[0137] 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.

[0138] 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.

[0139] 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.

[0140] The binder and conductive material mentioned above may be the same as those previously described in the anode.

[0141] Next, depending on the type of lithium secondary battery, a separator may be present between the positive and negative electrodes. As such a separator, polyethylene, polypropylene, polyvinylidene fluoride, or a multilayer film of two or more layers thereof may be used, and a mixed multilayer film such as a polyethylene / polypropylene two-layer separator, a polyethylene / polypropylene / polyethylene three-layer separator, or a polypropylene / polyethylene / polypropylene three-layer separator may also be used.

[0142] In addition, regarding the above lithium secondary battery, the electrolyte may include organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which are usable when manufacturing a lithium secondary battery, but is not limited to these.

[0143] Specifically, the organic liquid electrolyte may include an organic solvent and a lithium salt.

[0144] 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.

[0145] 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.

[0146]

[0147] 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).

[0148]

[0149] Hereinafter, embodiments of the present invention will be described in detail. However, these are presented as examples and are not intended to limit the present invention, and the present invention is defined only by the scope of the claims set forth below.

[0150]

[0151] Example 1

[0152] (1) Preparation of the first positive electrode active material

[0153] (Preparation of precursor) (Ni 0.40 Co 0.02 Mn 0.58 Prepare a precursor of the (OH)2 composition.

[0154] (Mixing) The above precursor was mixed with WO3 as a doping raw material and LiOH·H2O as a lithium raw material in a molar ratio of 0.995 : 0.005 : 1.22.

[0155] After (calcination), the above mixture was calcined at a temperature of 900°C for 10 hours under an oxygen atmosphere to prepare a lithium metal oxide. The composition of the obtained lithium metal oxide is Li 1.099 Ni 0.358 Co 0.018 Mn 0.520 W 0.004 It was O2.

[0156] (Discharge) Next, the above lithium metal oxide was discharged by natural cooling.

[0157] (Coating) As the above lithium metal oxide and coating raw materials, Al2O3 nanopowder with an average particle size of 100 nm to 200 nm and H3BO3 were dry-mixed, and then the temperature was gradually increased and heat-treated at 440°C for 6 hours in an air atmosphere to produce a first positive electrode active material comprising a first lithium metal oxide having a first surface portion formed. At this time, the coating raw materials were mixed such that Al2O3 nanopowder and H3BO3 had an Al content of 500 ppm and B had an B content of 1000 ppm based on the total amount of the produced positive electrode active material.

[0158] The average particle size (D50) of the manufactured first cathode active material is 11.1 μm, and the BET specific surface area is 2.23 m² 2 / g, the grain size was 64.3 nm.

[0159] (2) Preparation of the second positive active material

[0160] A second positive electrode active material comprising a second lithium metal oxide having a second surface portion formed thereon was prepared in the same manner as in (1) above, except that the second surface portion was formed by calcination at a temperature of 850°C for 10 hours during the calcination process. The average particle size (D50) of the prepared second positive electrode active material was 2.71 μm, and the BET specific surface area was 2.01 m². 2 / g, the grain size was 67.3 nm.

[0161] (3) Manufacturing of cathode material

[0162] A cathode material was prepared by mixing the above-mentioned first cathode active material and second cathode active material in a weight ratio of 6:4.

[0163]

[0164] Example 2 and Comparative Examples 1 to 4

[0165] A first cathode active material and a second cathode active material having BET specific surface area and grain size as shown in Table 1 below were prepared, and then mixed in a weight ratio of 6:4 to prepare a cathode material.

[0166]

[0167] Experimental Example 1: BET Specific Surface Area Measurement

[0168] The BET specific surface area was measured for each of the first positive active material and the second positive active material prepared according to Examples 1 to 2 and Comparative Examples 1 to 4.

[0169] Specifically, 4g of the first or second positive active material was dried at 300°C in a nitrogen atmosphere, which is an inert gas, and then nitrogen gas was adsorbed / desorbed onto the surface of the first or second positive active material, respectively. The specific surface area of ​​the material was measured by measuring the amount of adsorption at each partial pressure, and the results are shown in Table 1 below.

[0170]

[0171] Experimental Example 2: X-ray Diffraction Analysis of Anode Active Material

[0172] For each of the first and second positive active materials prepared according to Examples 1 and 2 and Comparative Examples 1 to 4, Cu Kα rays were used as an X-ray diffraction source, and the grain size values ​​were derived by measuring at a scan rate of 2 degrees / min in a diffraction angle (2theta) range of 14° to 100°. The results are shown in Table 1 below.

[0173]

[0174] Distinction BET (m 2 / g)Grain size (nm) Formula 1A / B Formula 2C / D First lithium metal oxide (A) Second lithium metal oxide (B) First lithium metal oxide (C) Second lithium metal oxide (D) Example 1 2.23 2.016 4.36 7.31.11 0.96 Example 2 2.05 1.95 6 5.16 9.01.05 0.94 Comparative Example 12.19 2.216 2.76 2.30.99 1.01 Comparative Example 22.05 2.29 6 6.96 2.10.90 1.08 Comparative Example 3 1.34 2.137 7.66 4.10.63 1.21 Comparative Example 4 2.31 1.675 9.87 3.51.38 0.81

[0175] Experimental Example 2: Coin Cell Fabrication and Electrochemical Characteristics Evaluation

[0176] CR2032 coin cells were manufactured using the positive electrode active materials prepared in the examples and comparative examples in the following manner, and their electrochemical characteristics were evaluated and are shown in Table 2 below.

[0177] (1) Coin cell manufacturing

[0178] The slurry for electrode manufacturing 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 adding NMP (N-Methyl-2-pyrrolidone) to adjust the viscosity so that the solid content was approximately 30%. The prepared slurry was coated onto a 15㎛ thick Al foil using a doctor blade, and the cathode was manufactured by dry rolling. The electrode loading amount was 14.6 mg / cm².2 It was, and the rolled density (25℃, 20kN) was 3.1 g / cm³ 3 It was.

[0179] A 2032 coin-type half-cell was manufactured using the above-mentioned positive electrode, lithium negative electrode (200 μm, Honzo metal), electrolyte, and polypropylene separator in a conventional manner. At this time, the electrolyte was prepared by adding 3.0 vol% of vinylene carbonate (VC) to the total amount of electrolyte to 1M LiPF6 in a mixed solvent of ethylene carbonate, dimethyl carbonate, and ethylmethyl carbonate (mixing ratio EC:DMC:EMC = 3:4:3 volume%) to prepare a mixed solution.

[0180] (2) Evaluation of initial discharge capacity

[0181] The coin cell prepared in (1) was aged at 25°C for 12 hours, and then formation was performed at 25°C. At this time, charging was performed up to 4.7V with a constant current of 0.1C and a reference capacity of 200 mAh / g. After charging, a rest time of 20 minutes was taken, and then discharging was performed until 2.5V was reached with a constant current of 0.1C and a reference capacity of 200 mAh / g. After formation, one more cycle was repeated under the same conditions to evaluate the initial discharge capacity. The results are shown in Table 1 below.

[0182] (3) Output characteristic evaluation (2C / 0.2C)

[0183] After evaluating the initial discharge capacity, the ratio of the discharge capacity to

[0184] (4) Life characteristic evaluation (25℃, 50 cycles)

[0185] From the second cycle onwards, following the initial discharge capacity evaluation, the device was charged to 4.5V with a constant current of 0.5C and then had a rest time of 20 minutes. Afterward, the device was discharged with a constant current of 0.5C until it reached 2.5V. Fifty charge-discharge cycles were performed under the same conditions as the second cycle, and the discharge capacity retention rate of the 50th cycle was calculated relative to the second cycle. The results are shown in Table 1 below.

[0186] (5) Voltage reduction measurement (25℃, 50 cycles)

[0187] From the second cycle onwards, following the initial discharge capacity evaluation, the device was charged to 4.5V with a constant current of 0.5C and then rested for 20 minutes. Afterward, the device was discharged with a constant current of 0.5C until it reached 2.5V. Fifty charge-discharge cycles were performed under the same conditions as the second cycle, and the voltage of the 50th cycle was measured relative to the second cycle to calculate the voltage decrease. The results are shown in Table 1 below.

[0188]

[0189] Classification 0.1C Discharge Capacity (mAh / g) Output, 2C / 0.2C Discharge Capacity Ratio (%) Lifespan, 50 th / 1 st Discharge capacity ratio (%) voltage decrease, 1 st -50 th (mV) Example 1 262.087.798.047.9 Example 2 261.286.698.347.7 Comparative Example 1 260.987.895.554.9 Comparative Example 2 261.587.996.255.7 Comparative Example 3 259.886.191.861.2 Comparative Example 4 255.179.296.953.8

[0190] Referring to Table 2, it can be seen that the cathode materials of Examples 1 and 2, in which the BET specific surface area of ​​the first and second cathode active materials satisfies the range of Equation 1, exhibit high discharge capacity, possess structural stability capable of inserting and extracting many lithium ions, and have excellent energy density. Furthermore, since the output and lifespan characteristics are excellent, it can be predicted that the structural stability of the cathode active material is maintained during the charging and discharging process and side reactions in the electrolyte are effectively suppressed. In addition, since the voltage drop is small, it can be seen that the increase in internal resistance during charging and discharging is suppressed. In contrast, it can be confirmed that the cathode materials of Comparative Examples 1 to 4, in which the BET specific surface area of ​​the first and second cathode active materials does not satisfy the range of Equation 1, have significantly lower output and lifespan characteristics and larger voltage drop values ​​compared to Examples 1 and 2.

[0191] That is, it can be confirmed that the cathode material according to the present embodiment satisfies Equation 1 for the BET specific surface area value and includes first and second cathode active materials with different average particle sizes (D50), thereby enabling the realization of a cathode active material with excellent capacity, lifespan, and output characteristics while having minimal voltage reduction.

[0192]

[0193] 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.

[0194] Therefore, the substantive scope of the present invention shall be defined by the appended claims and their equivalents.

Claims

1. A first positive electrode active material comprising a first lithium metal oxide having a molar ratio (Mn / M) of manganese (Mn) to the total transition metal (M) of 0.5 or more; and A second positive electrode active material comprising a second lithium metal oxide having a molar ratio (Mn / M) of manganese (Mn) to the total transition metal (M) of 0.5 or more, wherein The average particle size (D50) of the first positive active material is larger than the average particle size (D50) of the second positive active material, and A cathode material for a lithium secondary battery satisfying the following Equation 1: [Equation 1] 1.0 ≤ A / B ≤ 1.3 In the above Equation 1, A is the BET specific surface area of ​​the first positive active material, and B is the BET specific surface area of ​​the second positive active material.

2. In Paragraph 1, The BET specific surface area of ​​the first positive active material is 1.8 to 2.8 m 2 cathode material for lithium secondary batteries, with a phosphorus content of 1g.

3. In Paragraph 1, The BET specific surface area of ​​the second positive active material is 1.7 to 2.6 m² 2 cathode material for lithium secondary batteries, with a phosphorus content of 1g.

4. In Paragraph 1, The above-mentioned cathode material is a cathode material for a lithium secondary battery satisfying the following formula 2. [Equation 2] 0.82 ≤ C / D ≤ 1.0 In the above Equation 2, C is the grain size of the first positive active material, and D is the grain size of the second positive active material.

5. In Paragraph 4, A cathode material for a lithium secondary battery, wherein the crystal grain size of the first cathode active material is 58.0 nm to 75 nm.

6. In Paragraph 4, A cathode material for a lithium secondary battery, wherein the crystal grain size of the second cathode active material is 64.0 nm to 80 nm.

7. In Paragraph 1, The above first lithium metal oxide is a cathode material for a lithium secondary battery represented by the following chemical formula 1: [Chemical Formula 1] Li 1+a1 (Ni x1 Co y1 Mr z1 W b1 M1 c1 ) 1-a1 O 2-d1 A1 d1 In the above chemical formula 1, 0.1≤a1≤0.3, 0.35≤x1≤0.45, 0≤y1≤0.05, 0.45≤z1≤0.65, 0.001≤b1≤0.013, 0≤c1≤0.1, 0≤d1≤0.1, x1+y1+z1+b1+c1=1, M1 is B, Ti, Cr, Zr, Al, Y, Mg, Nb, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Ru, Ir or a combination thereof, and A1 is It is F, Cl, Br, I, or a combination thereof.

8. In Paragraph 1, The above second lithium metal oxide is a cathode material for a lithium secondary battery represented by the following chemical formula 2: [Chemical Formula 2] Li 1+a2 (Ni x2 Co y2 Mr z2 W b2 M2 c2 ) 1-a2 O 2-d2 A2 d2 In the above chemical formula 2, 0.1≤a2≤0.3, 0.35≤x2≤0.45, 0≤y2≤0.05, 0.45≤z2≤0.65, 0.001≤b2≤0.013, 0≤c2≤0.1, 0≤d2≤0.1, x2+y2+z2+b2+c2=1, M2 is B, Ti, Cr, Zr, Al, Y, Mg, Nb, Sc, Si, V, Fe, Mo, Ce, Hf, Ta, La, Sr, Sn, Sb, Zn, Cu, Ge, Ru, Ir or a combination thereof, and A2 is It is F, Cl, Br, I, or a combination thereof.

9. In Paragraph 1, The first lithium metal oxide above includes a first surface portion located on the surface, and The above second lithium metal oxide includes a second surface portion located on the surface, Cathode material for lithium secondary batteries.

10. In Paragraph 9, A cathode material for a lithium secondary battery, wherein the first surface portion and the second surface portion each comprise a B-containing compound and an Al-containing compound.

11. In Paragraph 10, A cathode material for a lithium secondary battery, wherein the content of B in the first cathode active material is 2000 ppm or less based on the entire first cathode active material.

12. In Paragraph 10, A cathode material for a lithium secondary battery, wherein the content of Al in the first cathode active material is 1000 ppm or less based on the entire first cathode active material.

13. In Paragraph 10, A cathode material for a lithium secondary battery, wherein the content of B in the second cathode active material is 2000 ppm or less based on the entire second cathode active material.

14. In Paragraph 10, A cathode material for a lithium secondary battery, wherein the content of Al in the second cathode active material is 1000 ppm or less based on the entire second cathode active material.

15. In Paragraph 1, A cathode material for a lithium secondary battery, wherein the mixing weight ratio (weight of the first cathode active material: weight of the second cathode active material) of the first cathode active material and the second cathode active material is in the range of 5:5 to 7:3.