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

Abstract

The present invention relates to a cathode active material for a lithium secondary battery, the cathode active material comprising a nickel-containing lithium metal oxide in the form of a single particle, wherein the lithium metal oxide includes Zr and Ti as doping elements, and the ratio (I(003) / I(104)) of the peak intensity of the (003) plane to the peak intensity of the (104) plane in an X-ray diffraction pattern analysis of the lithium metal oxide is 1.53 to 1.7.

Description

Positive electrode active material for lithium secondary batteries, method for producing the same, and lithium secondary batteries comprising the same

[0001] The present invention relates to a positive electrode active material for a lithium secondary battery, a method for producing the same, and a lithium secondary battery comprising the same, and more specifically, to a positive electrode active material for a single-particle lithium secondary battery, a method for producing the same, and a lithium secondary battery comprising the same.

[0002]

[0003] Lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (such as LiMnO2 or LiMnO4), and lithium iron phosphate compound (LiFePO4) have been used as cathode active materials for lithium secondary batteries. Among these, lithium cobalt oxide has the advantages of high operating voltage and excellent capacity characteristics, but the high price of cobalt, which is the raw material, and its supply are unstable, making it difficult to commercially apply it to large-capacity batteries. Lithium nickel oxide has poor structural stability, making it difficult to achieve sufficient cycle life characteristics. Meanwhile, lithium manganese oxide has excellent stability but has the problem of poor capacity characteristics. Therefore, lithium composite transition metal oxides containing two or more transition metals have been developed to complement the problems of lithium transition metal oxides containing only Ni, Co, or Mn. Among these, lithium nickel cobalt manganese oxides containing Ni, Co, and Mn are widely used in the field of electric vehicle batteries.

[0004] Conventional lithium nickel cobalt manganese oxides are generally in the form of spherical secondary particles formed by agglomeration of tens to hundreds of primary particles. However, in the case of lithium nickel cobalt manganese oxides formed in the form of secondary particles formed by agglomeration of many primary particles, there is a problem in that the primary particles are easily broken during the rolling process during the manufacture of the positive electrode, and cracks occur inside the particles during the charge and discharge process. When the positive electrode active material particles are broken or cracked, the contact area with the electrolyte increases, which increases the generation of gases and degradation of the active material due to side reactions with the electrolyte, and this causes problems in that the life characteristics are reduced.

[0005] In addition, the demand for high-power, high-capacity batteries, such as those for electric vehicles, is increasing recently, and accordingly, the nickel content in the cathode active material is gradually increasing (so-called "high nickel"). When the nickel content in the cathode active material increases, the initial capacity characteristics are improved, but when charge and discharge are repeated, the highly reactive Ni +4 There is a problem that a large amount of ions are generated, causing structural collapse of the positive electrode active material, which increases the rate of deterioration of the positive electrode active material, resulting in a decrease in life characteristics and battery safety.

[0006] To address the above issues, a technique has been proposed for producing single-particle cathode active materials, rather than secondary particles, by increasing the sintering temperature during the production of lithium nickel cobalt manganese oxide. Single-particle cathode active materials have a smaller contact area with the electrolyte than conventional secondary-particle cathode active materials, resulting in less side reactions with the electrolyte. Furthermore, their superior particle strength reduces particle breakage during electrode production. Therefore, the application of single-particle cathode active materials offers the advantages of reduced gas generation and superior cycle life.

[0007] However, in order to grow high-nickel single-particle lithium transition metal oxide into a cathode active material with a particle size of several microns, sintering at high temperatures and for a long time is required. At this time, if sintering at high temperatures and for a long time is performed, defects in the layered crystal structure due to oversintering occur, and since it is manufactured at a relatively high sintering temperature, a rock salt phase is formed on the particle surface, which increases the surface resistance and reduces the mobility of lithium ions. This decrease in lithium ion mobility primarily reduces the capacity characteristics, and secondarily causes an imbalance in lithium ion movement, which causes crystal structure deformation and particle cracking, resulting in a problem of reduced life characteristics such as an increase in resistance as the cycle progresses.

[0008]

[0009] Accordingly, one object of the present invention is to provide a cathode active material for a lithium secondary battery having improved capacity and lifespan characteristics as a lithium metal oxide in the form of a single particle, a method for producing the same, and a lithium secondary battery including the same.

[0010]

[0011] One embodiment of the present invention provides a cathode active material for a lithium secondary battery, which comprises a nickel-containing lithium metal oxide in the form of a single particle, wherein the lithium metal oxide comprises Zr and Ti as doping elements, and wherein the lithium metal oxide has a ratio of the peak intensity of the (003) plane to the peak intensity of the (104) plane (I(003) / I(104)) of 1.53 to 1.7 when analyzing an X-ray diffraction pattern.

[0012] The content of Zr in the above lithium metal oxide may be 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium.

[0013] The content of Ti in the lithium metal oxide may be 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium.

[0014] The molar ratio of Ti to Zr in the lithium metal oxide (Ti / Zr) may be 0.5 to 4.

[0015] The above lithium metal oxide may have a c-axis lattice constant of 14.22 to 14.4 Å.

[0016] The above lithium metal oxide may have a peak full width at half maximum (FWHM) of 0.12 to 0.14˚ on the (003) plane when analyzed by X-ray diffraction pattern.

[0017] The average particle diameter (D50) of the above lithium metal oxide may be 3 to 6 μm.

[0018] The content of nickel in the above lithium metal oxide may be 80 mol% or more based on the total mole number of metals excluding lithium.

[0019] The above lithium metal oxide can be represented by the following chemical formula 1.

[0020] [Chemical Formula 1]

[0021] Li a [Ni x Co y Mn z Zr w1 Ti w2 M w3 ]O2

[0022] In the above chemical formula 1, 0.8≤a≤1.2, 0.8≤x<1, 0≤y≤0.2, 0≤z≤0.2, 0.002≤w1≤0.022, 0.002≤w2≤0.022, 0≤w3≤0.1, x+y+z+w1+w2+w3=1, and M is another doping element, such as Al, B, Y, Nb, W, V, Cr, Mo, Ta, Fe, Cu, Zn, Ga, Ge, Ru, Rh, Sn, Sb, Re, Ir, Pt, Pb, Bi, Na, K, Rb, Cs, Ca, Sr, Ba, Mg, Si, Sc, or a combination thereof.

[0023]

[0024] Another embodiment of the present invention provides a method for producing a cathode active material for a lithium secondary battery, comprising the steps of: preparing a metal precursor; mixing the metal precursor, a lithium raw material, and a doping raw material, and then calcining to form a lithium metal oxide; and pulverizing the lithium metal oxide to form a lithium metal oxide in the form of single particles, wherein the doping raw material includes a Zr raw material and a Ti raw material, and the lithium metal oxide in the form of single particles has a ratio of the peak intensity of the (003) plane to the peak intensity of the (104) plane (I(003) / I(104)) of 1.53 to 1.7 when analyzing an X-ray diffraction pattern.

[0025] The above firing can be performed at a temperature of 740 to 810°C.

[0026] The above firing can be performed for 5 to 10 hours.

[0027] The above Zr raw material can be added so that the content of Zr in the lithium metal oxide is 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium.

[0028] The above Ti raw material can be added so that the content of Ti in the lithium metal oxide is 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium.

[0029] The above firing can be performed in an oxygen atmosphere.

[0030]

[0031] Another embodiment of the present invention provides a positive electrode for a lithium secondary battery comprising the positive electrode active material described above.

[0032] Another embodiment of the present invention provides a lithium secondary battery including the positive electrode for the lithium secondary battery.

[0033]

[0034] According to one embodiment of the present invention, a positive electrode active material for a lithium secondary battery can have improved capacity and life characteristics by doping Zr and Ti as doping elements into a lithium metal oxide in the form of a single particle.

[0035]

[0036] Figure 1 is a SEM image of a positive electrode active material manufactured according to Example 2.

[0037] Figure 2 is a SEM image of a positive electrode active material manufactured according to Example 3.

[0038]

[0039] The terms first, second, and third, etc., are used to describe, but are not limited to, various parts, components, regions, layers, and / or sections. These terms are used solely to distinguish one part, component, region, layer, or section from another part, component, region, layer, or section. Accordingly, a first part, component, region, layer, or section described below may be referred to as a second part, component, region, layer, or section without departing from the scope of the present invention.

[0040] The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the present invention. As used herein, the singular forms "singular" and "comprising" include plural forms as well, unless the context clearly dictates otherwise. The word "comprising" as used herein specifies a particular feature, region, integer, step, operation, element, and / or component, but does not exclude the presence or addition of other features, regions, integers, steps, operations, elements, and / or components.

[0041] When a part is referred to as being "on" or "over" another part, it can be directly on or over the other part, or there may be other parts intervening. Conversely, when a part is referred to as being "directly on" another part, there are no other parts intervening.

[0042] Although not defined otherwise, all terms, including technical and scientific terms, used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the present invention pertains. Terms defined in commonly used dictionaries are further interpreted to have meanings consistent with the relevant technical literature and the present disclosure, and are not to be construed as ideal or overly formal unless otherwise defined.

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

[0044] In this specification, the term "combination(s) thereof" described in the expression in the Makushi format means one or more mixtures or combinations selected from the group consisting of the components described in the expression in the Makushi format, and means including any one or more selected from the group consisting of said components.

[0045] Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily implement them. However, the present invention may be implemented in various different forms and is not limited to the embodiments described herein.

[0046]

[0047] 1. Positive active material

[0048] According to one embodiment of the present invention, a cathode active material for a lithium secondary battery comprises a lithium metal oxide in the form of a single particle. Compared to conventional secondary particles, the cathode active material in the form of a single particle has a smaller specific surface area, which reduces the amount of gas generated by side reactions with the electrolyte. Furthermore, the material has a higher particle strength, which suppresses particle breakage during rolling, and reduces the occurrence of cracks during repeated charging and discharging. Accordingly, the cathode active material has superior lifespan and safety compared to secondary particles, and has the advantage of being able to realize a high energy density of the electrode.

[0049] In this specification, the term "single particle" is used to distinguish it from the secondary particle type positive electrode active material particle formed by the aggregation of tens to hundreds of primary particles, which has been commonly used in the past, and is a concept that includes a single particle composed of one primary particle and an aggregate particle of 50 or fewer primary particles. In addition, "secondary particle" means an aggregate, i.e., a secondary structure, formed by the physical or chemical bonding between tens to hundreds of primary particles without an intentional aggregation or assembly process for the primary particles.

[0050] Additionally, "primary particle" refers to the smallest particle unit that can be distinguished as a single lump when observing the cross-section of a positive electrode active material through a scanning electron microscope (SEM), and may be composed of a single crystal grain or multiple crystal grains. Furthermore, "crystal grain" refers to a distinct region in the form of a lattice structure in which atoms within a primary particle form a lattice structure with a certain direction.

[0051] Meanwhile, the lithium metal oxide according to the present invention may be a lithium metal oxide having a nickel-containing layered crystal structure.

[0052] Additionally, the content of nickel in the lithium metal oxide according to the present invention may be 80 mol% or more based on the total mole number of metals excluding lithium. Since the content of nickel in the lithium metal oxide is included at such a high content (so-called "high nickel"), it is possible to achieve high capacity of the battery.

[0053] However, in order to grow high-nickel single-particle lithium transition metal oxide into a cathode active material with a particle size of several microns, sintering at high temperatures and for a long time is required. At this time, if sintering at high temperatures and for a long time is performed, defects in the layered crystal structure due to oversintering occur, and since it is manufactured at a relatively high sintering temperature, a rock salt phase is formed on the particle surface, which increases the surface resistance and reduces the mobility of lithium ions. This decrease in lithium ion mobility primarily reduces the capacity characteristics, and secondarily causes an imbalance in lithium ion movement, which causes crystal structure deformation and particle cracking, resulting in a problem of reduced life characteristics such as an increase in resistance as the cycle progresses.

[0054] Accordingly, a cathode active material for a lithium secondary battery according to one embodiment of the present invention includes Zr and Ti as doping elements in a lithium metal oxide. The doping element has a grain growth promoting effect, so that the crystal grain size and average grain diameter (D50) of the lithium metal oxide can be sufficiently grown even at a relatively low firing temperature. Accordingly, the grain growth effect can be maximized while lowering the firing temperature, thereby improving the capacity and life characteristics of the cathode active material and increasing the cathode density to maximize the energy density of the battery. On the other hand, when the lithium metal oxide contains only Zr or only Ti as a doping element, it may be inappropriate from the perspective of simultaneous improvement of the capacity and life characteristics of the battery, compared to a case where the lithium metal oxide contains both Zr and Ti as doping elements.

[0055] In addition, the lithium metal oxide according to the present invention may have a ratio of the peak intensity of the (003) plane to the peak intensity of the (104) plane (I(003) / I(104)) of 1.53 to 1.7, more specifically, 1.535 to 1.65, when analyzing the X-ray diffraction pattern of the lithium metal oxide. The ratio of the peak intensity of the (003) plane to the peak intensity of the (104) plane (I(003) / I(104)) when analyzing the X-ray diffraction pattern of the lithium metal oxide may be used as a measure of the so-called cation mixing ratio. At this time, a larger I(003) / I(104) peak intensity ratio may mean a smaller cation mixing ratio. Cation mixing refers to a phenomenon in which transition metal cations in a transition metal layer are partially substituted into the lithium layer in a layered crystal structure, that is, a layered crystal structure in which lithium layers and transition metal layers are alternately laminated. At this time, the ratio of the transition metal cations substituted within the lithium layer is referred to as the cation mixing ratio. In particular, nickel ions having a similar ionic radius to lithium ions are representative transition metals substituted within the lithium layer. At this time, if the cation mixing ratio of the lithium metal oxide is too large, the mobility of lithium ions within the lithium layer may be reduced, thereby deteriorating the capacity and life characteristics of the battery. Therefore, the lithium metal oxide according to the present invention has an I(003) / I(104) peak intensity ratio that satisfies the above range, so that the effect of improving the capacity and life characteristics of the positive electrode active material can be more preferably implemented. Meanwhile, the I(003) / I(104) peak intensity ratio of the lithium metal oxide may vary sharply depending on the doping amount of Zr and Ti, the firing temperature, the firing time, the firing atmosphere, etc. of each.

[0056] More specifically, the content of Zr in the lithium metal oxide may be 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium, and more specifically, may be 0.4 to 2.1 mol%. When the content of Zr in the lithium metal oxide satisfies the above range, the capacity and lifespan characteristics improvement effects of the positive electrode active material mentioned above may be more preferably implemented.

[0057] In addition, the content of Ti in the lithium metal oxide may be 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium, and more specifically, may be 0.4 to 2.1 mol%. When the content of Ti in the lithium metal oxide satisfies the above range, the capacity and lifespan characteristics improvement effects of the positive electrode active material mentioned above may be more preferably implemented.

[0058] In addition, the molar ratio of Ti to Zr in the lithium metal oxide (Ti / Zr) may be 0.5 to 4. When the molar ratio of Ti to Zr in the lithium metal oxide (Ti / Zr) satisfies the above range, the capacity and life characteristics improvement effects of the positive electrode active material mentioned above can be more preferably implemented.

[0059] In addition, the lithium metal oxide may have a c-axis lattice constant of 14.22 to 14.4 Å, and more specifically, may have a c-axis lattice constant of 14.221 to 14.37 Å. The c-axis lattice constant of the lithium metal oxide may refer to a width within which lithium ions can move in the lithium metal oxide, and may significantly affect the electrochemical characteristics of the battery. When the c-axis lattice constant of the lithium metal oxide according to the present invention satisfies the above range, the capacity and life-cycle characteristics improvement effects of the positive electrode active material mentioned above may be more preferably implemented. Meanwhile, the c-axis lattice constant of the lithium metal oxide may vary sharply depending on the doping amount of Zr and Ti, the sintering temperature, the sintering time, the sintering atmosphere, etc. In addition, the c-axis lattice constant of the lithium metal oxide can be estimated using the peak broadening of XRD data, and can be quantitatively calculated through the Scherrer equation.

[0060] In addition, the lithium metal oxide may have a peak full width at half maximum (FWHM) of the (003) plane of 0.12 to 0.14 degrees when analyzing the X-ray diffraction pattern. The peak full width at half maximum (FWHM) of the (003) plane may indicate the degree of development of the layered crystal structure of the lithium metal oxide, and may have a significant influence on the electrochemical characteristics of the battery. When the peak full width at half maximum (FWHM) of the (003) plane of the lithium metal oxide according to the present invention satisfies the above range, the capacity and lifespan characteristics improvement effect of the positive electrode active material mentioned above can be more preferably implemented. Meanwhile, the peak full width at half maximum (FWHM) of the (003) plane of the lithium metal oxide may vary sharply depending on the doping amount of Zr and Ti, the firing temperature, the firing time, the firing atmosphere, etc., respectively.

[0061] In addition, the average particle diameter (D50) of the lithium metal oxide may be 3 to 6 μm. If the average particle diameter (D50) of the lithium metal oxide is too small, the positive electrode density may decrease due to the decrease in the density of the positive electrode active material, which may lower the positive electrode energy density. If the average particle diameter (D50) of the lithium metal oxide is too large, the movement distance of lithium ions may become long, which may lower the capacity and rate characteristics. Therefore, when the average particle diameter (D50) of the lithium metal oxide satisfies the above range, the energy density of the battery can be preferably implemented. In the present specification, the average particle diameter (D50) can be defined as a particle diameter corresponding to 50% of the volume accumulation amount in the particle diameter distribution curve of the particles. The average particle diameter (D50) can be measured using, for example, a laser diffraction method.

[0062]

[0063] The lithium metal oxide can be more specifically represented by the following chemical formula 1.

[0064] [Chemical Formula 1]

[0065] Li a [Ni x Co y Mn z Zr w1 Ti w2 M w3 ]O2

[0066] In the above chemical formula 1, 0.8≤a≤1.2, 0.8≤x<1, 0≤y≤0.2, 0≤z≤0.2, 0.002≤w1≤0.022, 0.002≤w2≤0.022, 0≤w3≤0.1, x+y+z+w1+w2+w3=1, and M is another doping element, such as Al, B, Y, Nb, W, V, Cr, Mo, Ta, Fe, Cu, Zn, Ga, Ge, Ru, Rh, Sn, Sb, Re, Ir, Pt, Pb, Bi, Na, K, Rb, Cs, Ca, Sr, Ba, Mg, Si, Sc, or a combination thereof.

[0067] In the lithium metal oxide of the above chemical formula 1, lithium may be included in an amount corresponding to a, that is, 0.8≤a≤1.2. If a is too small, the capacity may be reduced, and if a is too large, the strength of the sintered positive electrode active material may be increased, making pulverization difficult, and the amount of gas generated may increase due to an increase in lithium byproducts. Considering the effect of improving the capacity characteristics of the positive electrode active material according to the control of the lithium content and the sinterability balance during the production of the active material, the lithium may be included in an amount of 0.9≤a≤1.1 more preferably.

[0068] In the lithium metal oxide of the above chemical formula 1, nickel may be included in an amount corresponding to x, i.e., 0.8≤x<1. Accordingly, it is possible to achieve high capacity of the battery.

[0069] In the lithium metal oxide of the above chemical formula 1, cobalt may be included in an amount corresponding to y, i.e., 0≤y≤0.2. If the cobalt content is too low, grain size growth may be inhibited and output characteristics may deteriorate. If the cobalt content is too high, manufacturing costs may increase and reversible capacity may decrease.

[0070] In the lithium metal oxide of the above chemical formula 1, manganese may be included in a content corresponding to z, i.e., 0≤z≤0.2. If the manganese content is too low, the production cost may increase and the stability of the active material may decrease. If the manganese content is too high, the capacity and output characteristics of the battery may decrease.

[0071] In the lithium metal oxide of the above chemical formula 1, the doping element Zr may be included in a content corresponding to w1, that is, 0.002≤w1≤0.022, and more specifically, 0.004≤w1≤0.021. When the content of Zr satisfies the above range, the capacity and life characteristics of the battery may be preferably implemented.

[0072] In the lithium metal oxide of the above chemical formula 1, the doping element Ti may be included in a content corresponding to w2, that is, 0.002≤w2≤0.022, and more specifically, 0.004≤w2≤0.021. When the content of Ti satisfies the above range, the capacity and life characteristics of the battery may be preferably implemented.

[0073] In the lithium metal oxide of the above chemical formula 1, M, which is another doping element, may be included in a content corresponding to w3, that is, 0≤w3≤0.1. At this time, M may be Al, B, Y, Nb, W, V, Cr, Mo, Ta, Fe, Cu, Zn, Ga, Ge, Ru, Rh, Sn, Sb, Re, Ir, Pt, Pb, Bi, Na, K, Rb, Cs, Ca, Sr, Ba, Mg, Si, Sc or a combination thereof. The content of the other doping element may be appropriately selected to implement other doping effects.

[0074]

[0075] 2. Method for manufacturing positive electrode active material

[0076] Another embodiment of the present invention provides a method for producing a cathode active material for a lithium secondary battery, comprising the steps of: preparing a metal precursor; mixing the metal precursor, a lithium raw material, and a doping raw material, and then calcining to form a lithium metal oxide; and pulverizing the lithium metal oxide to form a lithium metal oxide in the form of single particles, wherein the doping raw material includes a Zr raw material and a Ti raw material, and the lithium metal oxide in the form of single particles has a ratio of the peak intensity of the (003) plane to the peak intensity of the (104) plane (I(003) / I(104)) of 1.53 to 1.7 when analyzing an X-ray diffraction pattern.

[0077] Hereinafter, a method for manufacturing a positive electrode active material for a lithium secondary battery according to another embodiment of the present invention will be described in detail step by step.

[0078]

[0079] First, prepare a metal precursor.

[0080] The above metal precursor may more specifically be a metal hydroxide.

[0081] The above metal precursor may be manufactured by, for example, adding a complexing agent-containing solution and a pH adjusting agent-containing solution to a metal-containing solution including a nickel raw material, a manganese raw material, or a cobalt raw material, and performing a co-precipitation reaction.

[0082] The above nickel raw material is not particularly limited as long as it is used in the art for manufacturing a positive electrode active material precursor. For example, the nickel raw material may be a nickel-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically, may be NiSO4, NiSO4·6H2O, Ni(OH)2, NiO, NiOOH, NiCO3·2Ni(OH)2·4H2O, NiC2O2·2H2O, Ni(NO3)2·6H2O, fatty acid nickel salt, nickel halide, or a combination thereof, but is not limited thereto.

[0083] The above cobalt raw material is not particularly limited as long as it is used in the art for manufacturing a positive electrode active material precursor. For example, the cobalt raw material may be a cobalt-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, or oxyhydroxide, and specifically, CoSO 4, It may be, but is not limited to, CoSO4ㆍ7H2O, Co(OH)2, CoOOH, Co(OCOCH3)2ㆍ4H2O, Co(NO3)2ㆍ6H2O or a combination thereof.

[0084] The manganese raw material is not particularly limited as long as it is used in the art for manufacturing a precursor of a cathode active material. For example, the manganese raw material may be a manganese-containing sulfate, acetate, nitrate, halide, sulfide, hydroxide, oxide, oxyhydroxide, or a combination thereof, and specifically, may be a manganese salt such as MnSO4, MnCO3, Mn(NO3)2, manganese acetate, manganese dicarboxylic acid salt, manganese citrate, and manganese fatty acid salt, manganese oxide such as Mn2O3, MnO2, and Mn3O4, oxyhydroxide, manganese chloride, or a combination thereof, but is not limited thereto.

[0085] The above metal-containing solution may be prepared by adding a nickel raw material, a manganese raw material, or a cobalt raw material to a solvent, specifically, water, or a mixture of water and an organic solvent (e.g., alcohol, etc.) that can be uniformly mixed with water.

[0086] The above complexing agent-containing solution performs the function of forming a complex, and may include, but is not limited to, NH3, NH4OH, (NH4)2SO4, NH4NO3, NH4Cl, CH3COONH4, NH4CO3 or a combination thereof as the complexing agent. Meanwhile, the complexing agent-containing solution may be used in the form of an aqueous solution, and at this time, water or a mixture of water and an organic solvent (e.g., alcohol, etc.) that can be uniformly mixed with water may be used as the solvent.

[0087] The above pH adjusting agent-containing solution acts as a precipitant or pH adjusting agent, and may include an alkaline compound such as a hydroxide of an alkali metal or alkaline earth metal, such as NaOH, KOH, or Ca(OH)2, a hydrate thereof, or a combination thereof. Meanwhile, the pH adjusting agent-containing solution may also be used in the form of an aqueous solution, and at this time, water or a mixture of water and an organic solvent (e.g., alcohol, etc.) that can be uniformly mixed with water may be used as the solvent. At this time, the pH adjusting agent-containing solution may be added in an amount such that the pH of the reaction solution becomes 10 to 13.

[0088] The above coprecipitation reaction can be performed under an inert atmosphere such as nitrogen or argon, can be performed at a temperature of 30 to 70°C, and can be performed at a pH of 10 to 13.

[0089] Nickel (or manganese-cobalt) hydroxide particles are generated through the above process and precipitated within the reaction solution. The precipitated precursor particles can be separated, washed, and dried using conventional methods to obtain the precursor. The precursor may be a secondary particle formed by the agglomeration of primary particles.

[0090] At this time, the molar ratio of nickel, cobalt, or manganese in the precursor can be controlled by adjusting the concentration of the nickel raw material, cobalt raw material, or manganese raw material. That is, the concentration of the nickel raw material, cobalt raw material, and manganese raw material can be controlled so that the molar ratio of nickel, cobalt, or manganese in the final product, lithium metal oxide, falls within the range according to the present invention.

[0091]

[0092] Next, the metal precursor, lithium raw material, and doping raw material are mixed and then calcined to form a lithium metal oxide.

[0093] At this time, the doping raw material may include a Zr raw material and a Ti raw material.

[0094] The above Zr raw material is not particularly limited as long as it is a Zr-containing compound, but may be, for example, ZrO2.

[0095] The above Ti raw material is not particularly limited as long as it is a Ti-containing compound, but may be, for example, TiO2.

[0096] The lithium raw material may be lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it can be dissolved in water. Specifically, the lithium raw material may be, but is not limited to, Li2CO3, LiNO3, LiNO2, LiOH, LiOHㆍH2O, LiH, LiF, LiCl, LiBr, LiI, CH3COOLi, Li2O, Li2SO4, CH3COOLi, Li3C6H5O7, or a combination thereof.

[0097] The above Zr raw material can be added so that the content of Zr in the lithium metal oxide is 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium. The technical significance of controlling the amount of Zr raw material added is the same as described above, and therefore is omitted.

[0098] The above Ti raw material can be added so that the content of Ti in the lithium metal oxide is 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium. The technical significance of controlling the amount of Ti raw material added is the same as described above, and therefore is omitted.

[0099] The above sintering can be performed at a temperature of 740 to 810°C, and more specifically, can be performed at a temperature of 740 to 800°C. This sintering temperature range is lower than the sintering temperature used in the production of conventional high-nickel single-particle cathode materials. This is a phenomenon made possible by doping Zr and Ti in the lithium metal oxide as described above. When the sintering temperature satisfies the above range, the lithium metal oxide having a layered crystal structure is well formed, and at the same time, defects in the layered crystal structure caused by oversintering are prevented, so that the capacity and life characteristics of the battery can be preferably implemented, and various X-ray diffraction analysis properties including the I(003) / I(104) peak intensity of the lithium metal oxide can be appropriately implemented within the range according to the present invention.

[0100] The above firing can be performed for 5 to 10 hours, and more specifically, can be performed for 5 to 9 hours. This firing time range is a shorter range of the firing time than the firing time performed in the production of a conventional high-nickel single-particle cathode material. This is a phenomenon made possible by doping Zr and Ti in the lithium metal oxide as described above. When the firing time satisfies the above range, the lithium metal oxide having a layered crystal structure is well formed, and at the same time, defects in the layered crystal structure due to over-firing are prevented, so that the capacity and life characteristics of the battery can be preferably implemented, and various X-ray diffraction analysis properties including the I(003) / I(104) peak intensity of the lithium metal oxide can be appropriately implemented within the range according to the present invention.

[0101]

[0102] Next, the lithium metal oxide is crushed to form lithium metal oxide in the form of single particles.

[0103] The above disintegration can be performed using disintegration equipment commonly used in the art. For example, the disintegration can be performed using a jet mill, but is not necessarily limited thereto.

[0104]

[0105] Through the above series of manufacturing methods, a lithium metal oxide having a composition according to the present invention, including a doping content, can be formed in the form of a single particle, and the obtained lithium metal oxide can appropriately implement various X-ray diffraction analysis properties, including the I(003) / I(104) peak intensity, within the range according to the present invention. Accordingly, the capacity and life characteristics of the battery can be preferably implemented.

[0106]

[0107] 3. Cathode ray and lithium secondary battery

[0108] Another embodiment of the present invention provides a positive electrode for a lithium secondary battery comprising the positive electrode active material described above.

[0109] More specifically, the positive electrode may include a positive electrode current collector and a positive electrode active material layer disposed on the positive electrode current collector, and including the positive electrode active material described above.

[0110] The positive electrode current collector is not particularly limited as long as it is conductive and does not cause a chemical change in the battery, and for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel surface-treated with carbon, nickel, titanium, silver, etc. may be used. In addition, the positive electrode current collector may typically have a thickness of 3 to 500 μm, and fine unevenness may be formed on the surface of the positive electrode current collector to increase the adhesion of the positive electrode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, or non-woven fabric.

[0111] The above-described positive electrode active material layer may include a binder and / or a conductive material together with the above-described positive electrode active material.

[0112] At this time, the binder plays a role of improving the adhesion between the positive electrode active material particles and the adhesive strength between the positive electrode active material and the positive electrode current collector. Specific examples include polyvinylidene fluoride (PVDF), vinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinyl pyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene monomer rubber (EPDM rubber), sulfonated-EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one kind alone or a mixture of two or more kinds thereof may be used, but is not limited thereto. The binder may be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0113] And, the conductive material is used to provide conductivity to the electrode, and in the battery to be constructed, as long as it does not cause a chemical change and has electronic conductivity, it can be used without any special restrictions. Specific examples include graphite such as natural graphite or artificial graphite; carbon-based materials such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, summer black, and carbon fiber; metal powder or metal fiber such as copper, nickel, aluminum, and silver; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; or conductive polymers such as polyphenylene derivatives, and the like. One type alone or a mixture of two or more types among these may be used, but the present invention is not limited thereto. The conductive material may typically be included in an amount of 1 to 30 wt% based on the total weight of the positive electrode active material layer.

[0114] The above positive electrode can be manufactured according to a conventional positive electrode manufacturing method, except that the above positive electrode active material is used.

[0115] Specifically, the positive electrode can be manufactured by applying a composition for forming a positive electrode active material layer, including the positive electrode active material described above and optionally a binder, a conductive agent, or a solvent, on a positive electrode current collector, followed by drying and rolling. At this time, the types and contents of the positive electrode active material, binder, and conductive agent are as described above.

[0116] The solvent may be a solvent generally used in the relevant technical field, such as dimethylsulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water. One of these may be used alone or a mixture of two or more thereof may be used. The amount of the solvent used is sufficient to dissolve or disperse the positive electrode active material, conductive material, and binder, taking into account the coating thickness and manufacturing yield of the slurry, and to have a viscosity that can exhibit excellent thickness uniformity when applied thereafter for manufacturing the positive electrode.

[0117] Alternatively, the positive electrode may be manufactured by casting the composition for forming the positive electrode active material layer on a separate support, and then laminating the resulting film on a positive electrode current collector by peeling it off from the support.

[0118]

[0119] Another embodiment of the present invention provides a lithium secondary battery including the positive electrode for a lithium secondary battery as described above.

[0120] The above lithium secondary battery may more specifically include a positive electrode; a negative electrode; a separator; and an electrolyte.

[0121] The above lithium secondary battery may optionally further include a battery container that houses an electrode assembly of the positive electrode, negative electrode, and separator, and a sealing member that seals the battery container.

[0122] The above negative electrode may include a negative electrode current collector and a negative electrode active material layer positioned on the negative electrode current collector.

[0123] The negative electrode current collector is not particularly limited as long as it has high conductivity without causing chemical changes in the battery, and for example, copper, stainless steel, aluminum, nickel, titanium, calcined carbon, copper or stainless steel surface-treated with carbon, nickel, titanium, silver, etc., aluminum-cadmium alloy, etc. can be used. In addition, the negative electrode current collector can typically have a thickness of 3 to 500 ㎛, and like the positive electrode current collector, fine unevenness can be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it can be used in various forms such as a film, a sheet, a foil, a net, a porous body, a foam, a non-woven fabric, etc.

[0124] The negative electrode active material layer may optionally include a binder and a conductive material together with the negative electrode active material. As an example, the negative electrode active material layer may be manufactured by applying a composition for forming a negative electrode active material layer comprising the negative electrode active material and optionally a binder and a conductive material onto a negative electrode current collector and drying the composition, or by casting the negative electrode forming composition onto a separate support and then laminating the resulting film onto a negative electrode current collector by peeling the film off from the support.

[0125] As the negative electrode active material, a compound capable of reversible intercalation and deintercalation of lithium may be used. Specific examples thereof include carbonaceous materials such as artificial graphite, natural graphite, graphitized carbon fiber, and amorphous carbon; metallic compounds capable of alloying with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloy, Sn alloy, and Al alloy; metallic oxides capable of doping and dedoping lithium, such as SiOβ (0 < β < 2), SnO2, vanadium oxide, and lithium vanadium oxide; or composites comprising the metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites, and any one or a mixture of two or more of these may be used. In addition, a metallic lithium thin film may be used as the negative electrode active material. In addition, both low-crystalline carbon and high-crystalline carbon may be used as the carbonaceous material. Representative examples of low-crystalline carbon include soft carbon and hard carbon, and representative examples of high-crystalline carbon include natural graphite or artificial graphite in the form of amorphous, plate-like, flaky, spherical, or fiber-like forms, Kish graphite, pyrolytic carbon, mesophase pitch-based carbon fiber, meso-carbon microbeads, mesophase pitches, and high-temperature calcined carbon such as petroleum or coal tar pitch derived cokes.

[0126] The above binder and conductive material may be the same as those described above for the positive electrode.

[0127]

[0128] The above separator separates the negative electrode and the positive electrode and provides a passage for lithium ions to move. Any separator commonly used as a separator in lithium secondary batteries can be used without any particular restrictions. In particular, a separator having low resistance to ion movement of the electrolyte and excellent electrolyte moisture absorption capacity is preferable. Specifically, a porous polymer film, for example, a porous polymer film made of a polyolefin polymer such as an ethylene homopolymer, a propylene homopolymer, an ethylene / butene copolymer, an ethylene / hexene copolymer, and an ethylene / methacrylate copolymer, or a laminated structure of two or more layers thereof, may be used. In addition, a conventional porous nonwoven fabric, for example, a nonwoven fabric made of high-melting-point glass fiber, polyethylene terephthalate fiber, etc. may be used. In addition, a coated separator containing a ceramic component or a polymer material to secure heat resistance or mechanical strength may be used, and may optionally be used in a single-layer or multi-layer structure.

[0129]

[0130] The above electrolyte may include, but is not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel-type polymer electrolytes, solid inorganic electrolytes, and molten inorganic electrolytes that can be used in the manufacture of lithium secondary batteries.

[0131] Specifically, the organic liquid electrolyte may include an organic solvent and a lithium salt.

[0132] The organic solvent may be used without any particular limitation as long as it can serve as a medium through which ions involved in the electrochemical reaction of the battery can move. Specifically, the organic solvent may include ester solvents such as methyl acetate, ethyl acetate, γ-butyrolactone, and ε-caprolactone; ether solvents such as dibutyl ether or tetrahydrofuran; ketone solvents such as cyclohexanone; aromatic hydrocarbon solvents such as benzene and fluorobenzene; Carbonate solvents such as dimethylcarbonate (DMC), diethylcarbonate (DEC), methylethylcarbonate (MEC), ethylmethylcarbonate (EMC), ethylene carbonate (EC), and propylene carbonate (PC); alcohol solvents such as ethyl alcohol and isopropyl alcohol; nitriles such as R-CN (wherein R is a C2 to C20 linear, branched, or cyclic hydrocarbon group, and may include a double-bonded aromatic ring or an ether bond); amides such as dimethylformamide; dioxolanes such as 1,3-dioxolane; or sulfolanes can be used. Among these, a carbonate solvent is preferable, 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 linear carbonate compound having low viscosity (e.g., ethyl methyl carbonate, dimethyl carbonate, or diethyl carbonate, etc.) is more preferable.In this case, the performance of the electrolyte may be improved when the cyclic carbonate and the chain carbonate are mixed and used in a volume ratio of about 1:1 to about 1:9.

[0133] The lithium salt may be used without any particular limitation as long as it is a compound capable of providing lithium ions used in a lithium secondary battery. Specifically, the lithium salt may be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAl04, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2. LiCl, LiI, or LiB(C2O4)2. It is preferable that the concentration of the lithium salt be used within the range of 0.1 to 2.0 M. When the concentration of the lithium salt is within the above range, the electrolyte can exhibit excellent electrolyte performance because it has appropriate conductivity and viscosity, and lithium ions can move effectively.

[0134] In addition to the electrolyte components, the electrolyte may further include one or more additives, such as haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ethers, ethylene diamine, n-glyme, hexamethylphosphoric acid triamide, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinones, N,N-substituted imidazolidines, ethylene glycol dialkyl ethers, ammonium salts, pyrrole, 2-methoxyethanol, or aluminum trichloride, for the purpose of improving the life characteristics of the battery, suppressing battery capacity decrease, and improving the discharge capacity of the battery. At this time, the additives may be included in an amount of 0.1 to 5 wt% based on the total weight of the electrolyte.

[0135] As described above, a lithium secondary battery including a cathode active material according to the present invention stably exhibits excellent discharge capacity, output characteristics, and capacity retention, and is therefore useful in portable devices such as mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0136] Accordingly, another embodiment of the present invention provides a battery module including the lithium secondary battery as a unit cell and a battery pack including the same.

[0137] The above battery module or battery pack can be used as a power source for one or more medium- to large-sized devices, such as a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0138]

[0139] Hereinafter, embodiments of the present invention will be described in more detail through examples. However, the following examples are merely preferred embodiments of the present invention, and the present invention is not limited to the following examples.

[0140]

[0141] Example 1

[0142] (1) Manufacturing of positive electrode active material

[0143] (Mixed) Ni 0.88 Co 0.095 Mn 0.025(OH)2 precursor, LiOHH2O as a lithium raw material, ZrO2 as a Zr raw material, and TiO2 as a Ti raw material were introduced into a mixer and mechanically mixed to form a mixture. At this time, the amount of ZrO2 introduced was such that the content of Zr based on the total mole number of metals excluding lithium in the lithium metal oxide was 0.5 mol%, and the amount of TiO2 introduced was such that the content of Ti based on the total mole number of metals excluding lithium in the lithium metal oxide was 0.5 mol%.

[0144] (After calcination), the mixture was heated to 760°C through heat treatment under an oxygen atmosphere, calcined at a constant temperature of 760°C for 8 hours, and then naturally cooled to form lithium metal oxide.

[0145] (After crushing), a lithium transition metal oxide in the form of single particles was formed by crushing using a jet mill.

[0146] (2) Lithium secondary battery manufacturing

[0147] The slurry for manufacturing the electrode plate was mixed with the above-mentioned positive electrode active material: conductive material (carbon black, Denka black): binder (PVDF, KF1100) = 96.5:1.5:2 wt%, and the viscosity was adjusted so that the solid content was approximately 30% by adding NMP (N-Methyl-2-pyrrolidone). The manufactured slurry was coated on a 20 μm thick Al foil using a doctor blade, and then dried and rolled. The electrode loading was 15.4 mg / cm 2 and the rolling density (25℃, 20kN) was 3.6 g / cm 3 It was.

[0148] The electrolyte was 1M LiPF6in EC:DMC:EMC=3:4:3 (vol%), with 3.0 vol% VC added to the total amount of the electrolyte, and a coin cell was manufactured using a PP separator and a lithium negative electrode (200 μm, Honzo metal).

[0149]

[0150] Other Examples, Comparative Examples, and Reference Examples

[0151] A positive electrode active material and a lithium secondary battery were manufactured in the same manner as in Example 1, except that the process conditions were changed as shown in Table 1 below.

[0152] Process conditionsZr doping amount(mol%)Ti doping amount(mol%)Ti / Zr molar ratioSintering temperature(℃)Sintering time(h)Sintering atmosphereExample 10.50.517608OxygenExample 21117608OxygenExample 31117908OxygenExample 42217608OxygenComparative example 10007608OxygenComparative example 21007908OxygenComparative example 30107608OxygenReference example 10.050.5107605OxygenReference example 22.510.47605OxygenReference example 30.50.050.17905OxygenReference example 412.52.57905OxygenReference example 50.2157908OxygenReference example 61.50.60.47908 Oxygen Reference Example 71117008 Oxygen Reference Example 81118508 Oxygen Reference Example 90.50.517604 Oxygen Reference Example 100.50.5176012 Oxygen

[0153] Tables 2 and 3 below are tables summarizing the results of evaluating the physical properties of positive electrode active materials and the electrochemical characteristics of lithium secondary batteries according to Experimental Examples 2 and 3 described below.

[0154] Active material properties I(003) / I(104) peak intensity ratio (003) peak full width at half maximum (FWHM) (˚) c-axis lattice constant (Å) Example 11.53940.12814.2435 Example 21.57760.12714.2223 Example 31.58770.13214.3022 Example 41.5980.13414.3233 Comparative example 11.51120.12214.0221 Comparative example 21.52310.1214.0322 Comparative example 31.50250.11414.0566 Reference example 11.48890.11214.2654 Reference example 21.49040.12314.2234Reference Example 31.52210.12514.033Reference Example 41.52350.12614.4223Reference Example 51.54660.12714.4344Reference Example 61.62320.1214.1123Reference Example 71.50870.11414.0223Reference Example 81.52320.12914.998Reference Example 91.47780.13214.1123Reference Example 101.65660.13714.7785

[0155] Battery PerformanceInitial Charge Capacity (mAh / g)Initial Discharge Capacity (mAh / g)Initial Efficiency (%)1 st cycle resistance (Ω)30 thCycle Resistance (Ω) Resistance Increase Rate (%) Example 1 229.5 207.19 0.2 12.2 129.11 138.41 Example 2 229.6 207.59 0.4 11.9 128.43 138.71 Example 3 229.4 208.19 0.7 11.66 27.11 32.42 Example 4 229.8 207.49 0.3 11.88 26.2 120.54 Comparative Example 1 227.4 206.89 0.9 13.83 9.7 18 7.68 Comparative Example 2 229.7 204.58 9.0 13.69 34.6 15 2.74 Comparative Example 3230.4207.590.112.0732.2166.78Reference Example 1227.120489.812.731.2145.67Reference Example 2227.5204.289.813.233.5153.79Reference Example 3226.5203.589.813.532.1137.78Reference Example 4226.1205.490.812.632.5157.94Reference Example 5225.6203.490.212.4329.1134.11Reference Example 6227.3199.987.911.1224.06116.37Reference Example 7227.1206.290.813.236.2174.24Reference Example 8221.9191.786.410.2419.2387.79Reference Example 9225.1199.888.811.629150.00Reference Example 10222.3197.889.010.5620.291.29

[0156]

[0157] Experimental Example 1: Evaluation of SEM images of positive electrode active materials

[0158] SEM (scanning electron microscope) images of the positive electrode active materials manufactured according to Examples 2 and 3 were observed and are shown in FIGS. 1 and 2, respectively, in that order.

[0159] Referring to FIGS. 1 and 2, it was confirmed that the positive electrode active material manufactured according to the example had a single particle form.

[0160]

[0161] Experimental Example 2: Evaluation of the properties of positive electrode active materials

[0162] (1) I(003) / I(104) peak intensity ratio, (003) side full width at half maximum (FWHM) evaluation

[0163] The I(003) / I(104) peak intensity ratio and the (003) full width at half maximum (FWHM) were evaluated through X-ray diffraction pattern analysis.

[0164] (2) Evaluation of c-axis lattice constant

[0165] The c-axis lattice constant was evaluated through X-ray diffraction pattern analysis and Rietveld refinement.

[0166]

[0167] Experimental Example 3: Evaluation of Electrochemical Characteristics of Lithium Secondary Battery

[0168] (1) Initial capacity and initial efficiency evaluation

[0169] After fabricating a lithium secondary battery half-cell, it was aged at 25°C for 12 hours and then subjected to a charge-discharge test at 25°C. To evaluate the initial capacity, the reference capacity was set to 200 mAh / g, and the battery was charged to 4.25 V at a constant current of 0.1 C. Then, the battery was switched to a constant voltage and charged until the end current reached 0.05 C. After a 10-minute rest time after charging, the battery was discharged to 2.5 V at a constant current of 0.1 C, using the reference capacity of 200 mAh / g.

[0170] (2) Evaluation of high temperature resistance increase rate (45℃, 30 cycles)

[0171] After fabricating a lithium secondary battery half-cell, it was charged to 4.25 V at a constant current of 0.5 C at 45°C, then switched to constant voltage and charged until the end current reached 0.05 C. After a rest time of 10 minutes after charging, it was discharged at a constant current of 1.0 C until it reached 2.5 V. Under these charge-discharge cycle conditions, 30 charge-discharge cycles were performed, and the resistance increase rate of the 30th cycle compared to the first cycle was calculated.

[0172]

[0173] Referring to Tables 1 to 3, in the case of Examples 1 to 4 in which the composition of the lithium metal oxide, such as the doping amount of Zr and Ti, and the sintering process conditions, including the sintering temperature, satisfied the range according to the present invention, it was confirmed that the composition of the lithium metal oxide, the I(003) / I(104) peak intensity ratio, and other X-ray diffraction analysis-related properties were appropriately implemented within the range according to the present invention. As a result, the capacity (initial discharge capacity) and resistance characteristics (1) of the battery st It was confirmed that the cycle resistance) and life characteristics (resistance increase rate according to cycle progression) were comprehensively implemented very well.

[0174] On the other hand, in the case of Comparative Example 1, since Zr and Ti were not doped in the lithium metal oxide, it was confirmed that the I(003) / I(104) peak intensity ratio and the c-axis lattice constant of the lithium metal oxide were outside the range according to the present invention. In addition, it was confirmed that the capacity, resistance characteristics, and life characteristics of the battery were poor.

[0175] In Comparative Example 2, since Ti was not doped in the lithium metal oxide, it was confirmed that the I(003) / I(104) peak intensity ratio and the c-axis lattice constant of the lithium metal oxide were outside the range according to the present invention. In addition, it was confirmed that the capacity, resistance characteristics, and life characteristics of the battery were poor.

[0176] In Comparative Example 3, as a result of not doping Zr in the lithium metal oxide, it was confirmed that the I(003) / I(104) peak intensity ratio, the (003) plane peak half-width, and the c-axis lattice constant of the lithium metal oxide were outside the range according to the present invention. In addition, it was confirmed that the life characteristics of the battery were poor.

[0177] In the case of Reference Example 1, the doping amount of Zr in the lithium metal oxide was too low, and it was confirmed that the I(003) / I(104) peak intensity ratio and the (003) peak half width of the lithium metal oxide were outside the range according to the present invention. In addition, it was confirmed that the capacity, resistance characteristics, and life characteristics of the battery were reduced.

[0178] In the case of Reference Example 2, it was confirmed that the I(003) / I(104) peak intensity ratio of the lithium metal oxide was outside the range according to the present invention as a result of the excessive doping amount of Zr in the lithium metal oxide. In addition, it was confirmed that the capacity, resistance characteristics, and life characteristics of the battery were reduced.

[0179] In the case of Reference Example 3, it was confirmed that the I(003) / I(104) peak intensity ratio and c-axis lattice constant of the lithium metal oxide were outside the range according to the present invention due to the doping amount of Ti in the lithium metal oxide being too small. In addition, it was confirmed that the capacity and resistance characteristics of the battery were reduced.

[0180] In the case of Reference Example 4, it was confirmed that the I(003) / I(104) peak intensity ratio and the c-axis lattice constant of the lithium metal oxide were outside the range according to the present invention due to the excessive doping amount of Ti in the lithium metal oxide. In addition, it was confirmed that the capacity, resistance characteristics, and life characteristics of the battery were reduced.

[0181] In the case of Reference Example 5, although the doping amounts of Zr and Ti in the lithium metal oxide were appropriate, the Ti / Zr molar ratio was too large, and it was confirmed that the c-axis lattice constant of the lithium metal oxide was outside the range according to the present invention. In addition, it was confirmed that the capacity and resistance characteristics of the battery were reduced.

[0182] In the case of Reference Example 6, although the doping amounts of Zr and Ti in the lithium metal oxide were appropriate, the Ti / Zr molar ratio was too small, and it was confirmed that the c-axis lattice constant of the lithium metal oxide was outside the range according to the present invention. In addition, it was confirmed that the capacity characteristics of the battery were poor.

[0183] In the case of Reference Example 7, although the composition of the lithium metal oxide was appropriate, the sintering temperature was too low, resulting in the I(003) / I(104) peak intensity ratio, the (003) plane peak half-width, and the c-axis lattice constant of the lithium metal oxide being outside the ranges according to the present invention. In addition, it was confirmed that the capacity, resistance characteristics, and life characteristics of the battery were deteriorated.

[0184] In the case of Reference Example 8, even though the composition of the lithium metal oxide was appropriate, it was confirmed that the I(003) / I(104) peak intensity ratio and the c-axis lattice constant of the lithium metal oxide were outside the range according to the present invention as a result of the sintering temperature being too high.

[0185] In the case of Reference Example 9, although the lithium metal oxide composition was appropriate, the firing time was too short, and as a result, the I(003) / I(104) peak intensity ratio and the c-axis lattice constant of the lithium metal oxide were found to be outside the range according to the present invention. In addition, it was confirmed that the capacity and life characteristics of the battery were poor.

[0186] In the case of Reference Example 10, although the composition of the lithium metal oxide was appropriate, the firing time was too long, and as a result, the I(003) / I(104) peak intensity ratio and the c-axis lattice constant of the lithium metal oxide were found to be outside the range according to the present invention. In addition, it was confirmed that the capacity characteristics of the battery were poor.

[0187]

[0188] Although the preferred embodiments of the present invention have been described above, the present invention is not limited thereto, and various modifications can be made within the scope of the patent claims, the detailed description of the invention, and the attached drawings, and it is obvious that this also falls within the scope of the present invention.

[0189] Accordingly, the actual scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. Contains nickel-containing lithium metal oxide in the form of single particles, The above lithium metal oxide contains Zr and Ti as doping elements, The above lithium metal oxide is a cathode active material for a lithium secondary battery, wherein the ratio of the peak intensity of the (003) plane to the peak intensity of the (104) plane (I(003) / I(104)) when analyzing an X-ray diffraction pattern is 1.53 to 1.

7.

2. In paragraph 1, A cathode active material for a lithium secondary battery, wherein the content of Zr in the lithium metal oxide is 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium.

3. In paragraph 1, A cathode active material for a lithium secondary battery, wherein the content of Ti in the lithium metal oxide is 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium.

4. In paragraph 1, A cathode active material for a lithium secondary battery, wherein the molar ratio of Ti to Zr in the lithium metal oxide (Ti / Zr) is 0.5 to 4.

5. In paragraph 1, The above lithium metal oxide is a cathode active material for a lithium secondary battery having a c-axis lattice constant of 14.22 to 14.4 Å.

6. In paragraph 1, The above lithium metal oxide is a cathode active material for a lithium secondary battery having a peak full width at half maximum (FWHM) of 0.12 to 0.14˚ on the (003) plane when analyzed by an X-ray diffraction pattern.

7. In paragraph 1, A cathode active material for a lithium secondary battery, wherein the average particle diameter (D50) of the lithium metal oxide is 3 to 6 μm.

8. In paragraph 1, A cathode active material for a lithium secondary battery, wherein the content of nickel in the lithium metal oxide is 80 mol% or more based on the total mole number of metals excluding lithium.

9. In paragraph 1, The above lithium metal oxide is a cathode active material for a lithium secondary battery represented by the following chemical formula 1: [Chemical Formula 1] Li a [Nor x What? y Mn z Zr w1 You w2 M w3 ]O2 In the chemical formula 1, 0.8≤a≤1.2, 0.8≤x<1, 0≤y≤0.2, 0≤z≤0.2, 0.002≤w1≤0.022, 0.002≤w2≤0.022, 0≤w3≤0.1, and x+y+z+w1+w2+w3=1, and M is another doping element, such as Al, B, Y, Nb, W, V, Cr, Mo, Ta, Fe, Cu, Zn, Ga, Ge, Ru, Rh, Sn, Sb, Re, Ir, Pt, Pb, Bi, Na, K, Rb, Cs, Ca, Sr, Ba, Mg, Si, Sc or a combination thereof.

10. Step of preparing metal precursor; A step of mixing the above metal precursor, lithium raw material and doping raw material and then calcining to form lithium metal oxide; and Comprising a step of crushing the lithium metal oxide to form a lithium metal oxide in the form of single particles, The above doping raw material includes Zr raw material and Ti raw material, The lithium metal oxide in the form of a single particle has a ratio of the peak intensity of the (003) plane to the peak intensity of the (104) plane (I(003) / I(104)) of 1.53 to 1.7 when analyzing the X-ray diffraction pattern. A method for manufacturing a cathode active material for a lithium secondary battery.

11. In paragraph 10, A method for producing a cathode active material for a lithium secondary battery, wherein the above-mentioned calcination is performed at a temperature of 740 to 810°C.

12. In paragraph 10, A method for producing a cathode active material for a lithium secondary battery, wherein the above-mentioned firing is performed for 5 to 10 hours.

13. In paragraph 10, A method for manufacturing a cathode active material for a lithium secondary battery, wherein the Zr raw material is added so that the content of Zr in the lithium metal oxide is 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium.

14. In paragraph 10, A method for manufacturing a cathode active material for a lithium secondary battery, wherein the above Ti raw material is added so that the content of Ti in the lithium metal oxide is 0.2 to 2.2 mol% based on the total mole number of metals excluding lithium.

15. In paragraph 10, A method for producing a cathode active material for a lithium secondary battery, wherein the above-mentioned calcination is performed in an oxygen atmosphere.

16. A cathode for a lithium secondary battery comprising a cathode active material according to Article 1.

17. A lithium secondary battery comprising a positive electrode for a lithium secondary battery according to Article 16.

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