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

Abstract

The present specification relates to a positive electrode active material, and a positive electrode and a lithium secondary battery comprising same, the positive electrode active material comprising: a lithium transition metal compound having an olivine structure; and a lithium transition metal compound having a layered structure, wherein the value calculated by mathematical formula 1 is 14% or less.

Description

Cathode active material, a cathode including the same, and a lithium secondary battery

[0001] Cross-citation with related application(s)

[0002] This specification claims the benefit of the filing date of Patent No. 10-2025-0049274 filed with the Korean Intellectual Property Office on April 16, 2025, the contents of which are incorporated herein.

[0003] This specification relates to a positive electrode active material, a positive electrode containing the same, and a lithium secondary battery.

[0004] With the recent rapid proliferation of battery-powered electronic devices such as mobile phones, laptop computers, and electric vehicles, the demand for small, lightweight, and relatively high-capacity rechargeable batteries is increasing rapidly. In particular, lithium-ion batteries are gaining prominence as power sources for portable devices due to their lightweight nature and high energy density. Consequently, active research and development efforts are underway to improve the performance of lithium-ion batteries.

[0005] In a lithium secondary battery, electrical energy is produced by oxidation and reduction reactions when lithium ions are inserted into or removed from the positive and negative electrodes, which are composed of active materials capable of lithium ion intercalation and deintercalation, with an organic or polymer electrolyte charged between them.

[0006] Lithium cobalt oxide (LiCoO2), lithium nickel oxide (LiNiO2), lithium manganese oxide (LiMnO2 or LiMn2O4, etc.), and lithium iron phosphate compounds (LiFePO4) have been used as cathode active materials for lithium secondary batteries. Furthermore, as a method to improve the low thermal stability of LiNiO2 while maintaining its excellent reversible capacity, lithium composite metal oxides (hereinafter simply referred to as 'NCM-based lithium composite transition metal oxides' or 'NCA-based lithium composite transition metal oxides') in which a portion of the nickel (Ni) is substituted with cobalt (Co) or manganese (Mn) / aluminum (Al) have been developed.

[0007] Research is being conducted to increase the capacity per unit volume and improve the stability of such lithium composite transition metal oxides by forming a concentration gradient of the metal composition or increasing the nickel content. In addition, research is being conducted to increase the rolling density by manufacturing a cathode active material layer in a bimodal form by blending large and small particles to increase the capacity per unit volume of the electrode. However, there is still a need to develop cathode active materials that simultaneously satisfy high capacity and excellent thermal stability.

[0008] The present invention relates to a positive electrode active material with improved orientation characteristics and enhanced battery chemical performance, a positive electrode containing the same, and a lithium secondary battery.

[0009] The present invention relates to a lithium transition metal compound having an olivine structure; and

[0010] It includes a lithium transition metal compound having a layered structure, and

[0011] A positive electrode active material is provided in which the value calculated by the following mathematical formula 1 is 14% or less.

[0012] [Mathematical Formula 1]

[0013] |(P1-P0)| / P0×100(%)

[0014] In mathematical formula 1,

[0015] P1 is the crystal plane orientation index of the positive active material after rolling, and

[0016] P0 is the crystal plane orientation index of the positive active material before rolling, and

[0017] The above crystal plane orientation index is the ratio of the intensity of the (101) plane peak to the intensity of the (020) plane peak in the X-ray diffraction pattern of the positive active material (I 101 The ratio of )(I 101 / I 020 )am.

[0018] The present invention provides a positive electrode comprising the positive electrode active material described above.

[0019] The present invention provides a lithium secondary battery comprising the anode described above.

[0020] The positive active material of the present invention has the effect of improving battery chemical performance by improving orientation characteristics.

[0021] The present specification will be described in detail below.

[0022] Unless otherwise defined in this specification, all technical and scientific terms are used merely to describe exemplary embodiments and are not intended to limit this specification. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as 'comprising,' 'comprising,' or 'having' are intended to specify the presence of the implemented features, numbers, steps, components, or combinations thereof, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, components, or combinations thereof.

[0023] This specification is subject to various modifications and may take various forms, and specific embodiments are illustrated and described in detail below. However, this is not intended to limit this specification to the specific disclosed forms, and it should be understood that it includes all modifications, equivalents, and substitutions that fall within the spirit and scope of the technology.

[0024] The technical terms used in this specification are intended merely to refer to specific embodiments and are not intended to limit this specification. Furthermore, singular forms used herein include plural forms unless phrases clearly indicate otherwise.

[0025] In this specification, the 'positive active material' may be a composition comprising one or more lithium transition metal compounds having an olivine structure and two or more lithium transition metal compounds having a layered structure.

[0026] In this specification, the 'olivine structure' may have an orthorhombic crystal structure and is a structure in which oxygen atoms are arranged in a hexagonal close-packed form (HCP). In this case, lithium is located in a one-dimensional channel and has a one-dimensional ion diffusion pathway. A transition metal is located at an oxygen octahedral site and participates in a redox reaction, and phosphoric acid (PO4 3- It forms a framework of strong covalent tetrahedral units, contributing to structural stabilization.

[0027] In this specification, 'lithium transition metal compounds having an olivine structure' include lithium iron phosphate compounds (LFP), lithium manganese phosphate compounds (LMP), lithium iron manganese phosphate compounds (LMFP), etc. Specifically, it may be a lithium iron manganese phosphate compound.

[0028] In this specification, the 'layered structure' may have a hexagonal crystal structure and oxygen atoms may have a cubic close-packed structure. In this case, it may be a structure in which a lithium layer containing lithium and a transition metal layer containing a transition metal are alternately stacked with an oxygen layer containing oxygen atoms in between.

[0029] In this specification, "rolling" refers to a state in which the positive electrode active material is compressed by a rolling member such as a roller. It differs from a mixture in which a lithium transition metal compound having an olivine structure and a lithium transition metal compound having a layered structure are simply mixed.

[0030] In this specification, 'crystal plane' refers to a virtual plane formed in a specific direction within a structure in which atoms, ions, or molecules are arranged according to a certain rule in a crystalline solid. It may be denoted by a Miller index (hkl), and includes (020) planes, (101) planes, etc.

[0031] In this specification, 'orientation' is a factor indicating which direction a crystal plane is facing.

[0032] In this specification, 'particle size' refers to the diameter of an individual particle. In this case, if the particle is a perfect sphere, it refers to the diameter of the sphere. Additionally, if the particle is not a perfect sphere, it may refer to the diameter of a virtual perfect sphere having the same volume as the particle. Alternatively, it may refer to the diameter of a virtual circle having the same area as the cross-section of the particle as confirmed by an optical microscope image, such as a scanning electron microscope; the diameter of the largest circle that may be contained within the cross-section of the particle as confirmed by the optical microscope image (Maximum Inscribed Circle Diameter); or the diameter of the smallest circle that completely surrounds the cross-section of the particle as confirmed by the optical microscope image.

[0033] In this specification, 'mean particle size' refers to a statistical representative value representing a sample containing several particles (Mean Particle Size). For example, it may be the number mean particle size calculated by dividing the sum of the diameters of individual particles in the sample by the number of particles, or it may be the mean particle size (Dn) derived by a method using a particle size analyzer as described below.

[0034] In this specification, the method for measuring the particle size or average particle size may use a method using a particle size analyzer (PSD) or a scanning electron microscope image analysis method. Unless otherwise stated in this specification, the particle size or average particle size may be measured using the method using the particle size analyzer. For example, the average particle size of the positive electrode active material may be determined by analyzing a dispersion in which the positive electrode active material is dispersed using a particle size analyzer. Additionally, the average particle size of a lithium transition metal compound having an olivine structure or a lithium transition metal compound having a layered structure may be determined by analyzing a dispersion containing these compounds using a particle size analyzer.

[0035] In this specification, the method using the particle size analyzer is a laser diffraction analysis method in which a laser is irradiated onto a dispersion in which a positive electrode active material is dispersed, and the pattern of the scattered light is analyzed using an optical model. Statistical analysis of the entire sample is possible, and fast and automated analysis is possible. By using the particle size analyzer, a volume distribution curve or a volume accumulation distribution curve in which particles are accumulated in order from smallest to largest can be derived and analyzed. The scanning electron microscope image analysis method involves measuring the particle size of individual particles on the scanning electron microscope image of the positive electrode active material using image analysis software, etc. The actual morphology of the particles can be taken into account, and the particle sizes of primary and secondary particles distinguished in the scanning electron microscope image can be measured separately.

[0036] In this specification, 'Dn' refers to the particle size at the n% point of the cumulative volume distribution according to particle size. That is, D 50 is the particle size at the 50% point of the cumulative volume distribution according to particle size, and D 90 The particle size at the 90% point of the cumulative volume distribution according to particle size is D 10 Dn is the particle size at the 10% point of the cumulative volume distribution according to particle size. The above Dn can be measured using the Laser Diffraction Method. Specifically, after dispersing the powder to be measured in a dispersion medium, it is introduced into a commercially available laser diffraction particle size measuring device (e.g., Microtrac S3500) to calculate the particle size distribution by measuring the difference in diffraction patterns according to particle size as the particles pass through the laser beam. By calculating the particle diameters at the points corresponding to 10%, 50%, and 90% of the cumulative volume distribution according to particle size in the measuring device, D 10 , D 50 and D 90 It can measure.

[0037] In this specification, a 'Primary Particle' is a basic unit that forms a 'Secondary Particle,' which is an aggregate of particles, and the Primary Particle and the Secondary Particle are distinguished by the presence or absence of particle aggregation. When multiple Primary Particles aggregate to form a Secondary Particle, a particle interface existing between the Primary Particles may exist within the Secondary Particle. The Primary Particle may refer to the smallest unit demarcated by the particle interface when observing the positive electrode active material using a Scanning Electron Microscope (SEM). Additionally, the Primary Particle may refer to a particle in a state where the positive electrode active material containing the Secondary Particle has been sufficiently crushed in a grinder or disperser.

[0038] In this specification, 'Single Particle' refers to a secondary particle form in which the number of primary particles constituting the secondary particle is small; it may be a single particle form consisting of one primary particle, or a secondary particle form in which several primary particles are aggregated. In other words, it is a concept distinct from a secondary particle formed by the aggregation of hundreds of primary particles. Specifically, it may refer to a form in which the secondary particle consists of 40 or fewer, 30 or fewer, 20 or fewer, 10 or fewer, 5 or fewer, or 3 or fewer primary particles. In this case, particle breakage can be prevented even at high electrode densities. Furthermore, compared to a secondary particle in which hundreds of primary particles are aggregated, breakage during rolling is suppressed, enabling the realization of high energy density and preventing lifespan degradation caused by particle breakage.

[0039] In this specification, 'single crystal' refers to a particle form having a single crystal grain inside the particle. Alternatively, it may be a form that does not contain a crystal boundary inside the particle. Since the single crystal is distinguished by the number of crystals inside the particle, it is distinguished from the concept of a single particle defined based on the number of primary particles forming the particle, regardless of the type and number of crystals inside. When the positive electrode active material is of the single crystal type, structural stability is improved compared to the polycrystalline type, and high-speed charging characteristics are excellent due to improved lithium ion conductivity.

[0040] In this specification, 'grain' refers to a region in a sample where atoms are arranged continuously and periodically in one direction. The grains can be analyzed using an Electron Backscatter Diffraction (EBSD) analyzer. Within a polycrystalline particle, multiple grains can be separated into grain boundaries.

[0041] In this specification, 'Grain Size' refers to the size of a region having an aligned atomic arrangement. This region is named as a single grain and forms a boundary with other grains. The average grain size can be quantitatively analyzed using X-ray diffraction analysis (XRD) by Cu Kα X-rays. Specifically, XRD data of the synthesized cathode active material is obtained using a Bruker D8 XRD instrument (Cu-target, voltage: 45kV, current: 40mA, 2θ: 10 to 100 degrees), and structural analysis of the obtained data can be performed using the Rietveld refining method, a general structural analysis method, with Malvern Panalytical's Highscore software. The Rietveld refining method is a method in which a diffraction pattern is calculated from an initial structural model that the crystal structure of the material may have, and this is compared with the measured diffraction pattern of the actual synthesized material. Various structure-related factors are introduced and their values ​​are changed to gradually and iteratively adjust the pattern until the two patterns match well. This method adopts an iterative approach that determines validity based on the difference between the calculated and measured patterns, repeating the process until the difference between the two patterns is minimized. Among the structure-related factors that can be introduced in this process, the crystal size can be derived using the full width at half maximum (FWHM) of each crystal plane appearing in the measured diffraction pattern.

[0042] In this specification, the content of the components of the cathode active material can be quantified by known methods. For example, ICP-OES (Inductively Coupled Plasma-Optical Emission Spectroscopy) or ICP-MS (Inductively Coupled Plasma-Mass Spectrometry) methods may be used.

[0043] Conventionally, when lithium transition metal compounds having an olivine structure and lithium transition metal compounds having a layered structure are used together in the cathode active material composition, the performance of the lithium transition metal compounds having an olivine structure has sometimes deteriorated. Specifically, the orientation plane of the lithium transition metal compounds having an olivine structure can be distorted during the physical mixing and rolling processes of the lithium transition metal compounds having an olivine structure and the lithium transition metal compounds having a layered structure. Specifically, the orientation of the lithium transition metal compounds having an olivine structure is distorted due to the layered structure, which hinders the smooth diffusion pathway of lithium ions and can lead to a decrease in electrochemical performance. This hindering effect is more pronounced during the rolling process, where stress generated as the lithium transition metal compounds, which have low strength due to the unstable layered structure, are easily deformed is transferred to the lithium transition metal compounds having an olivine structure, potentially causing further distortion of the orientation plane.

[0044] The positive electrode active material of the present invention comprises a lithium transition metal compound having an olivine structure and a lithium transition metal compound having a layered structure, and has the characteristic that the orientation characteristics of the positive electrode active material (or the lithium transition metal compound having an olivine structure) are not distorted even after rolling. When a lithium secondary battery is manufactured by applying the positive electrode active material having the above characteristics to a battery, the orientation characteristics of the positive electrode active material can be excellently maintained even during the rolling process. Through this, a lithium ion diffusion pathway is secured, and the electrochemical performance is improved.

[0045] The positive active material of the present invention is characterized by having a value of 14% or less calculated by the following mathematical formula 1.

[0046] [Mathematical Formula 1]

[0047] |(P1-P0)| / P0×100(%)

[0048] In mathematical formula 1,

[0049] P1 is the crystal plane orientation index of the positive active material after rolling, and

[0050] P0 is the crystal plane orientation index of the positive active material before rolling, and

[0051] The above crystal plane orientation index is the ratio of the intensity of the (101) plane peak to the intensity of the (020) plane peak in the X-ray diffraction pattern of the positive active material (I 101 The ratio of )(I 101 / I 020 )am.

[0052] In the present invention, the value calculated by the above mathematical formula 1 can be expressed as a 'crystal plane distortion index' representing the degree of distortion of the orientation plane of the positive electrode active material (or, a lithium transition metal compound having an olivine structure) before and after the rolling process. The value calculated by the above mathematical formula 1 may represent the ratio of change in the crystal plane orientation index of the positive electrode active material before and after rolling.

[0053] In the present invention, the anode active material after rolling and the anode active material before rolling can be distinguished by porosity, density, etc. The porosity can be analyzed using the Brunauer-Emmett-Teller (BET) or Barrett-Joyner-Halenda (BJH) analysis method, and the density can be calculated using the relationship between the volume and weight of the anode active material.

[0054] In the present invention, the porosity of the anode active material prior to rolling may be 40% or more, 45% or more, 50% or more, or 55% or more. Additionally, it may be 90% or less, 80% or less, 70% or less, or 60% or less. In particular, it may be 55%.

[0055] In the present invention, the density of the anode active material before rolling is 1.9 g / cm³ 3 Less than, 1.8 g / cm³ 3 Below, 1.6 g / cm³ 3 Less than or equal to 1.5 g / cm³ 3 It may be less than or equal to 1 g / cm³. Also, 1 g / cm³ 3 Above, 1.1 g / cm³3 Above, 1.2 g / cm³ 3 Above or 1.3 g / cm³ 3 It may be abnormal. In particular, 1.4 g / cm³ 3 It could be.

[0056] In the present invention, the porosity of the anode active material after rolling may be less than 40%, 38% or less, 36% or less, or 34% or less. Additionally, it may be 10% or more, 20% or more, 25% or more, or 30% or more. In particular, it may be 30%.

[0057] In the present invention, the density of the anode active material after rolling is 1.9 g / cm³ 3 Above, 2g / cm² 3 Above, 2.2g / cm² 3 Above or 2.3 g / cm³ 3 It may be more than that. Also, 3g / cm² 3 Below, 2.8g / cm³ 3 Below, 2.6 g / cm³ 3 Less than or equal to 2.4 g / cm³ 3 It may be less than or equal to 2.3 g / cm³. In particular, 2.3 g / cm³ 3 It could be.

[0058] In the present invention, the 'crystal plane orientation index' is the ratio of the intensity of the (101) plane peak to the intensity of the (020) plane peak in the X-ray diffraction pattern of the positive electrode active material (I 101 The ratio of )(I 101 / I 020...is. When charging a lithium secondary battery, the d-spacing of the (020) plane increases, causing the b-axis to lengthen and the crystal structure to expand, and the (101) plane is also affected, causing deformation. Conversely, when discharging the battery, the d-spacing of the (020) plane decreases, and as lithium ions are reinserted, the crystal structure contracts, and stress accumulates in the (101) plane. That is, the (020) plane and the (101) plane influence phase changes and stress distribution within the interconnected crystal structure during the charging and discharging process; the (020) plane influences lithium ion diffusion, and the (101) plane influences structural stress. In other words, the above crystal plane orientation index can be understood as representing the correlation between lithium ion diffusion and structural stress. The above (020) plane is a plane parallel to the ion diffusion path (b-axis direction) within a lithium transition metal compound having an olivine structure, and as the intensity of the peak corresponding to the (020) plane increases, the insertion / extraction of lithium ions becomes smoother, which can improve electrochemical performance. The above (101) plane is one of the planes perpendicular to the lithium ion diffusion path (b-axis direction), and as the intensity of the peak corresponding to the (101) plane increases, the lithium ion diffusion path experiences resistance, which can degrade electrochemical performance. In other words, by adjusting the above 'crystal plane orientation index', the lithium ion diffusion path is optimized, and the electrochemical performance of the cathode material can be improved.

[0059] In the present invention, the value calculated by the above mathematical formula 1 may be 14% or less. Preferably, it may be 13% or less, 12% or less, 11% or less, 10% or less, 9% or less, 8% or less, 7% or less, 6% or less, 5% or less, 4% or less, 3% or less, or 2% or less. The lower limit is not particularly limited, but may be 0.1% or more, 0.5% or more, 1% or more, 1.5% or more, 1.7% or more, 1.8% or more, 1.85% or more, or 1.9% or more. Within the above numerical range, by preventing distortion of the orientation plane of the cathode active material or the lithium transition metal compound having an olivine structure even when a rolling process is performed, the lithium ion diffusion path is optimized and the electrochemical performance of the cathode material can be improved.

[0060] In the present invention, the value calculated by the above mathematical formula 1 can be achieved by changing the composition ratio, content ratio, particle size, doping element, coating element, carbon coating layer, etc. of the lithium transition metal compound having an olivine structure and the lithium transition metal compound having a layered structure.

[0061] In the present invention, the crystal plane orientation index (P1) of the anode active material after rolling may be 0.1 or higher and 1 or lower. Preferably, it may be 0.2 or higher, 0.3 or higher, 0.4 or higher, 0.5 or higher, 0.6 or higher, 0.7 or higher, 0.71 or higher, 0.72 or higher, 0.73 or higher, or 0.74 or higher. Additionally, it may be 0.9 or lower or 0.8 or lower. Within the above numerical range, the orientation plane within the lithium transition metal compound having an olivine structure is oriented as a plane parallel to the lithium ion diffusion path (b-axis direction), thereby optimizing the lithium ion diffusion path and improving the electrochemical performance of the anode material.

[0062] In the present invention, the 2θ angle at which the (101) plane peak appears in the X-ray diffraction pattern of the positive electrode active material may be 19 to 21 degrees, and the 2θ angle at which the (020) plane peak appears may be 29 to 32 degrees. The intensity of the peak may refer to the intensity of the peak with the highest height among the peaks appearing in the above range.

[0063] In the present invention, the 2θ angle at which the (101) plane peak appears may be 19 degrees or more, 19.2 degrees or more, 19.4 degrees or more, 19.6 degrees or more, 19.8 degrees or more, 20 degrees or more, 20.2 degrees or more, or 20.4 degrees or more. Additionally, it may be 20.9 degrees or less, 20.8 degrees or less, or 20.7 degrees or less.

[0064] In the present invention, the 2θ angle at which the (020) plane peak appears may be 29 degrees or more, 29.1 degrees or more, 29.2 degrees or more, 29.3 degrees or more, 29.4 degrees or more, 29.5 degrees or more, or 29.6 degrees or more. Additionally, it may be 32 degrees or less, 31.5 degrees or less, 31 degrees or less, 30.5 degrees or less, or 30 degrees or less.

[0065] In the present invention, the value calculated by the following mathematical formula 2 may be 150 or less. Preferably, it may be 140 or less, 130 or less, 120 or less, 110 or less, 100 or less, 95 or less, or 90 or less. The lower limit is not particularly limited, but may be 1 or more, 10 or more, 20 or more, 30 or more, or 40 or more.

[0066] [Mathematical Formula 2]

[0067] (D O ) / {D O +D L ×(W LO / 100)}*(D L ×M Ni )

[0068] In mathematical formula 2,

[0069] D OThe average particle size (D) of the lithium transition metal compound having the above olivine structure 50 , unit:㎛) and,

[0070] D L is the average particle size (D) of the lithium transition metal compound having the above layered structure. 50 , unit:㎛) and,

[0071] W LO is the content (unit: wt%) of the lithium transition metal compound having a layered structure based on the total weight of the lithium transition metal compound having the olivine structure, and

[0072] M Ni is the molar content of nickel (unit: mol%) based on the total number of moles of transition metal in the lithium transition metal compound having the above layered structure.

[0073] The above mathematical formula 2 can be understood as a parameter representing the stress transfer power within the positive electrode active material considering the mixing characteristics of the positive electrode active material. That is, the present invention can satisfy the above-described mathematical formula 1 by controlling the stress generated during the rolling process by adjusting the value calculated by the above mathematical formula 2 to a certain level.

[0074] In the cathode active material composition in which the lithium transition metal compound having an olivine structure and the lithium transition metal compound having a layered structure are mixed together, the lithium transition metal compound having a relatively small olivine structure is located in the empty spaces between the lithium transition metal compounds having a layered structure that have a relatively large size. Subsequently, during the rolling process of the cathode active material, stress caused by the lithium transition metal compound having a layered structure is transferred to the lithium transition metal compound having an olivine structure. At this time, the transferred stress is proportional to the frequency of contact between the lithium transition metal compound having an olivine structure and the lithium transition metal compound having a layered structure within the cathode active material, and may be proportional to the structural instability of the lithium transition metal compound having a layered structure.

[0075] The above 'contact frequency of lithium transition metal compounds having an olivine structure' can be understood as the occupancy rate of lithium transition metal compounds having an olivine structure for the empty spaces between lithium transition metal compounds having a layered structure. '(D in Equation 2 above O ) / {D O +D L ×(W LO / 100)}' refers to the relative spatial occupancy of lithium transition metal compounds having an olivine structure.

[0076] The above 'structural instability of lithium transition metal compounds having a layered structure' indicates that the high structural instability of lithium transition metal compounds having a layered structure makes them prone to deformation, and in the case of large sizes, the force transmitted by stress increases. In lithium transition metal compounds having a layered structure, the structural instability increases as the nickel content increases, and stress generation due to structural deformation may occur more easily. That is, '(D in the above Equation 2 L ×M Ni )' can be understood as 'the magnitude of stress that a lithium transition metal compound having a layered structure can transfer to a lithium transition metal compound having an olivine structure'.

[0077] The above mathematical formula 2 can be derived by combining the characteristics or physical properties of a lithium transition metal compound having an olivine structure and a lithium transition metal compound having a layered structure used in the process of manufacturing a positive electrode active material.

[0078] In addition, the above mathematical formula 2 can be derived by calculating the presence and content of each component using an analysis method that is not limited to any positive electrode active material.

[0079] First, W LO... can be quantified. From the X-ray diffraction (XRD) analysis results of the cathode active material, the position and intensity of peaks corresponding to the (020) plane, (101) plane, (311) plane, etc., which are the main peaks of the lithium transition metal compound having an olivine structure, are quantified. In addition, the position and intensity of peaks corresponding to the (003) plane, (104) plane, (108), etc., which are the main peaks of the lithium transition metal compound having a layered structure are quantified. Subsequently, W using software such as TOPAS LO It can be quantified.

[0080] Meanwhile, elements such as Li, Ni, Co, Mn, Fe, and P are identified using methods like ICP-OES or ICP-MS, and the molar concentration of each element is calculated. Subsequently, the previously quantified W LO Using M Ni It can calculate.

[0081] The above D O and D L The particles can be filtered using a sieve having an arbitrary particle size standard, and the filtered particles with small sizes are classified as lithium transition metal compounds having an olivine structure, while the unfiltered particles with large sizes are classified as lithium transition metal compounds having a layered structure. Afterward, the average particle size can be calculated for each classified compound using the laser particle size analyzer described above. At this time, the arbitrary particle size standard may be 1 μm, 1.5 μm, 2 μm, or 3 μm.

[0082] In addition, the above D O and D L EDS elemental mapping can be performed on scanning electron microscope (SEM) images of the cathode active material to classify particles with P or Fe signals as lithium transition metal compounds with an olivine structure and particles with Ni or Co signals as lithium transition metal compounds with a layered structure, and then the average value of the particle sizes of 50 or more or 100 or more particles can be applied using commercial software such as ImageJ.

[0083] In the present invention, the value calculated by the following mathematical formula 3 may be 1% or more and 12% or less. Preferably, it may be 2% or more, 3% or more, 4% or more, or 4.5% or more. Additionally, it may be 10% or less, 8% or less, or 6% or less.

[0084] [Mathematical Formula 3]

[0085] D O / W CO *100(%)

[0086] In mathematical formula 3,

[0087] D O The average particle size (D) of the lithium transition metal compound having the above olivine structure 50 , unit:㎛) and,

[0088] W CO is the content of carbon-containing raw materials included in the lithium transition metal compound having the olivine structure based on the total weight of the lithium transition metal compound having the olivine structure (unit: wt%).

[0089] During the rolling process of the above-mentioned positive electrode active material, stress caused by a lithium transition metal compound having a layered structure is transferred to a lithium transition metal compound having an olivine structure. At this time, the carbon coating layer of the lithium transition metal compound having an olivine structure acts as a protective layer, thereby controlling the transferred stress. On the other hand, if the carbon content is too high, the thickness of the carbon coating layer is non-uniform, which may result in lower mechanical strength. Equation 3 above can satisfy Equation 1 described above by controlling the ratio of the carbon content and average particle size of the lithium transition metal compound to secure the mechanical strength of the lithium transition metal compound having an olivine structure and controlling the stress during rolling.

[0090] In the present invention, the average particle size (D) of the lithium transition metal compound having the olivine structure 50) may be 0.1㎛ or more and 10㎛ or less. Specifically, it may be 0.25㎛ or more, 0.3㎛ or more, 0.35㎛ or more, 0.4㎛ or more, 0.45㎛ or more, or 0.48㎛ or more. In addition, it may be 8㎛ or less, 6㎛ or less, 4㎛ or less, 2㎛ or less, 1㎛ or less, 0.9㎛ or less, 0.8㎛ or less, 0.7㎛ or less, or 0.6㎛ or less. Within the above numerical range, a lithium transition metal compound having an olivine structure is provided between lithium transition metal compounds having a layered structure during the rolling process, and the rearrangement of particles or crystals is uniformly performed during the rolling process, and the above-described mathematical formula 1 can be satisfied.

[0091] In the present invention, the average particle size (D) of the lithium transition metal compound having the layered structure is 50 The ) may be 1㎛ or more and 20㎛ or less. Preferably, it may be 1.2㎛ or more, 1.4㎛ or more, 1.6㎛ or more, 1.8㎛ or more, 2㎛ or more, 2.3㎛ or more, 2.5㎛ or more, 2.8㎛ or more, 3㎛ or more, or 3.3㎛ or more. Or, it may be 18㎛ or less, 16㎛ or less, 14㎛ or less, 12㎛ or less, 10㎛ or less, 8.5㎛ or less, 7.5㎛ or less, 6㎛ or less, 5㎛ or less, 4㎛ or less, or 3.8㎛ or less. Within the above numerical range, a lithium transition metal compound having an olivine structure is provided between lithium transition metal compounds having a layered structure during the rolling process, and the rearrangement of particles or crystals is uniformly performed during the rolling process, and the above-described mathematical formula 1 can be satisfied.

[0092] In the present invention, the content (W) of the lithium transition metal compound having a layered structure based on the total weight of the lithium transition metal compound having an olivine structure. LO) may be 20 wt% or more and 200 wt% or less. Preferably, it may be 20 wt% or more, 24 wt% or more, 28 wt% or more, 32 wt% or more, 36 wt% or more, or 40 wt% or more. Additionally, it may be 170 wt% or less, 140 wt% or less, 110 wt% or less, 80 wt% or less, 70 wt% or less, 50 wt% or less, or 45 wt% or less. Within the above numerical range, the effect of improving electrochemical performance due to the addition of a lithium transition metal compound having a layered structure is maintained, while preventing the problem of the orientation characteristics of a lithium transition metal compound having an olivine structure being degraded by the lithium transition metal compound having a layered structure. That is, by satisfying the above numerical range, the above-described Equation 1 can be satisfied.

[0093] In the present invention, the lithium transition metal compound having an olivine structure and the lithium transition metal compound having a layered structure may exist as independent powders. This implies a state in which there is physical contact but no chemical bonding. In other words, it means that the lithium transition metal compound having an olivine structure and the lithium transition metal compound having a layered structure do not form a complex with each other. In this case, distortion of the crystal plane of the lithium transition metal compound having an olivine structure can be prevented.

[0094] In the present invention, the lithium transition metal compound having the olivine structure may comprise primary particles; secondary particles formed by the aggregation of primary particles; or a combination thereof.

[0095] In the present invention, the average particle size (D) of the primary particles of the lithium transition metal compound having the olivine structure 50) may be 50 nm or more and 200 nm or less. Preferably, it may be 60 nm or more, 70 nm or more, 80 nm or more, or 100 nm or more. Additionally, it may be 180 nm or less, 160 nm or less, 140 nm or less, or 120 nm or less. Within the above numerical range, internal reorientation of the crystal is advantageous, and there is an effect that is advantageous for orientation toward the (020) plane. In addition, the lithium migration path is shortened, so electrochemical performance can be improved.

[0096] In the present invention, the positive electrode active material comprises a lithium transition metal compound having an olivine structure. In this case, since it has strong PO bonds, it can prevent the crystal structure from collapsing during the charging and discharging process, thereby improving high-temperature stability. Furthermore, since lithium ions mainly move along the b-axis within the olivine structure, the effect of the value calculated by the above-described Equation 1 can be more pronounced in the olivine structure. The olivine structure can be confirmed using X-ray diffraction (XRD) analysis.

[0097] In the present invention, the manganese content of the lithium transition metal compound having an olivine structure may be 10 mol% or more and 90 mol% or less based on the total transition metal of the lithium transition metal compound having an olivine structure. Preferably, it may be 15 mol% or more, 18 mol% or more, 20 mol% or more, 23 mol% or more, 25 mol% or more, 27 mol% or more, 29 mol% or more, or 30 mol% or more. Additionally, it may be 80 mol% or less, 70 mol% or less, 68 mol% or less, 66 mol% or less, 60 mol% or less, 55 mol% or less, 50 mol% or less, or 40 mol% or less. The transition metal may refer to Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, or a combination thereof, or may refer only to Mn and Fe. Within the above numerical range, energy density and charge / discharge rates are improved, and cycle life stability can be improved. In addition, it can prevent the reduction of lifespan caused by manganese leaching.

[0098] In the present invention, when a positive electrode active material having a lithium transition metal compound having the olivine structure has a molar manganese content within the above numerical range and is applied to a lithium secondary battery, the effect of improving low-temperature performance is achieved. In the olivine crystal structure of conventional olivine-based positive electrode active materials, Fe 2+ / Fe 3+ The electron hopping mechanism is highly sensitive to temperature, and in olivine crystal structures with one-dimensional lithium ion diffusion channels, the lithium ion diffusion coefficient decreases further at low temperatures. Additionally, during the charging and discharging process, a two-phase reaction between the Li-rich phase (LiFePO4) and the Li-poor phase (FePO4) must proceed. However, at low temperatures, the migration speed of the phase interface decreases significantly, resulting in partial reactions only on the surface of the cathode active material while the interior remains an unreacted region, making it difficult to achieve a uniform reaction throughout the entire particle.

[0099] In the present invention, by controlling the molar manganese content of the lithium transition metal compound having the olivine structure to the above numerical range and substituting manganese, which has an ionic radius larger than that of iron, the crystal lattice structure expands slightly and the one-dimensional lithium ion diffusion channel expands. At this time, the activation energy required for the movement of lithium ions is lowered, thereby improving the lithium ion diffusion coefficient in the low-temperature region and narrowing the energy bandgap Fe 2+ / Fe 3+ The electron hopping mechanism can be facilitated. Through the above operating principle, battery performance can be improved even at low temperatures.

[0100] In the present invention, the lithium transition metal compound having the olivine structure can be represented by the following chemical formula 1.

[0101] [Chemical Formula 1]

[0102] Li 1+t1 Mn a Fe b M 1 w1 (PO4)

[0103] In the above chemical formula 1,

[0104] The above M 1 is B, Mg, Al, Si, Ca, Sc, Ti, V, Cr, K, Co, Ni, Cu, Zn, Ga, Ge, As, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, La, or a combination thereof, and

[0105] -0.2≤t1<1, 0<a<1, 0<b<1, 0≤w1<1, a+b+w1=1.

[0106] In the present invention, a, b, and w1 of Formula 1 may represent the molar content of each component. Specifically, among the lithium transition metal compounds having an olivine structure represented by Formula 1, Mn, Fe, and M 1 It can refer to the molar ratio of each element based on the total moles of. For example, if a and b are 0.5 and w1 is 0, then Mn, Fe, and M 1 Based on the total moles of, the molar content of Fe and Mn, respectively, is 50 mol%, and M 1 The molar content of may be 0 mol%. Meanwhile, M 1 In the case of two or more elements, M 1 It may mean the total molar content of the corresponding element. Or, it may mean the molar ratio of each element based on the total number of moles of PO4. For example, if a and b are 0.5, it may mean that the molar content of Fe and Mn, respectively, is 50 mol% based on the total number of moles of PO4.

[0107] In the present invention, t1 may be -0.1 or more, -0.05 or more, 0 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more. Additionally, it may be 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less, 0.09 or less, or 0.08 or less. When t1 satisfies the above range, the capacity can be increased while maintaining charge / discharge characteristics. Furthermore, by maintaining the orientation characteristics of the lithium transition metal compound having an olivine structure even during rolling, the above-described Equation 1 can be satisfied.

[0108] In the present invention, the a / (a+b) may be 0.1 or more and 0.9 or less. Preferably, it may be 0.15 or more, 0.18 or more, 0.22 or more, 0.23 or more, 0.25 or more, or 0.28 or more. Additionally, it may be 0.8 or less, 0.7 or less, 0.6 or less, 0.5 or less, or 0.45 or less. Within the above numerical range, energy density and charge / discharge speeds can be improved, and cycle life stability can be improved. Furthermore, it is possible to prevent the lifespan from degrading due to manganese leaching.

[0109] In the present invention, w1 may be 0.001 or more and 0.1 or less. Preferably, it may be 0.002 or more, 0.003 or more, 0.004 or more, 0.005 or more, 0.006 or more, 0.008 or more, or 0.01 or more. Additionally, it may be 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.015 or less, 0.013 or less, or 0.011 or less. Within the above numerical range, M 1 The effects of doping are excellently maintained, and excessive doping element M 1 This can prevent the degradation of lattice stability or electrical conductivity.

[0110] In the present invention, the above M 1 It may be B, Mg, Al, Si, Ca, Sc, Ti, V, Cr, K, Co, Ni, Cu, Zn, Ga, Ge, As, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, La, or a combination thereof. Meanwhile, other elements may be included in addition to the elements described above to improve chemical or physical performance, and non-metallic elements such as F, S, and N may also be included to improve electrochemical performance.

[0111] In the present invention, the above M1 The element may be B, Al, Y, Zr, or a combination thereof. The above elements are elements that are highly effective for improving lithium ion mobility characteristics or ensuring structural stability, and depending on the combination used, the effect can be further enhanced, and when using these elements, the above-described mathematical formula 1 can be satisfied.

[0112] In the present invention, the above M 1 When using B, B has a small ionic radius and can form strong bonds with oxygen within the crystal structure, which suppresses the formation of (101) planes and relatively increases (020) planes, thereby expanding the lithium diffusion path.

[0113] In the present invention, the above M 1 When using Al, the crystal structure can be formed more densely, the stress distribution in the (101) plane can be dispersed, and the (020) plane can be increased by controlling the crystal growth rate.

[0114] In the present invention, the above M 1 When using Y, the large ionic radius of Y can induce local expansion of the crystal lattice, the formation of (101) planes, and the cycle life of the battery can be improved.

[0115] In the present invention, the above M 1 When Zr is used, the cycle life of the battery can be improved by dispersing the stress generated during the phase change in the lithium insertion / extraction reaction.

[0116] In the present invention, the lithium transition metal compound having the olivine structure may include a carbon coating layer provided on part or all of its surface. By including the carbon coating layer, the electronic conductivity of the positive electrode active material can be improved.

[0117] In the present invention, the carbon coating layer may be provided on primary particles of a lithium transition metal compound having the olivine structure; secondary particles; or a combination thereof.

[0118] In the present invention, the carbon coating layer may be provided on an area of ​​10% or more and 100% or less based on the total surface area of ​​the surface of the lithium transition metal compound having the olivine structure. Within the above numerical range, since the carbon coating layer can be uniformly formed, the electrical conductivity of the lithium transition metal compound having the olivine structure can be improved.

[0119] In the present invention, the carbon content included in the carbon coating layer may be 1 wt% or more and 15 wt% or less based on the total weight of the lithium transition metal compound having an olivine structure. Preferably, it may be 2 wt% or more, 3 wt% or more, 4 wt% or more, 6 wt% or more, or 8 wt% or more. Additionally, it may be 14 wt% or less, 13 wt% or less, 12 wt% or less, or 11 wt% or less. Within the above numerical range, the carbon coating layer of the lithium transition metal compound having an olivine structure acts as a protective layer to control the transmitted stress. On the other hand, if the carbon content is too high, the thickness of the carbon coating layer becomes non-uniform, which may result in lower mechanical strength. Equation 3 above can satisfy Equation 1 described above by controlling the ratio of the carbon content and average particle size of the lithium transition metal compound, thereby securing the mechanical strength of the lithium transition metal compound having an olivine structure and controlling the stress during rolling.

[0120] In the present invention, the thickness of the carbon coating layer may be 10 nm or more and 50 nm or less. Preferably, it may be 10 nm or more, 15 nm or more, or 20 nm or more. Additionally, it may be 40 nm or less or 30 nm or less. Within the above numerical range, the carbon coating layer may not act as a resistor while improving the electron conductivity of the positive electrode active material. The thickness of the carbon coating layer can be measured by analyzing an image obtained using a transmission electron microscope (TEM). Specifically, the thickness of the coating layer at 10 to 30 positions on any particle may be measured and the average value calculated to be the thickness of the carbon coating layer of the corresponding particle, and the average value of the thickness of the carbon coating layer of 21 to 30 particles may be calculated to be the thickness of the carbon coating layer.

[0121] In the present invention, the nickel content of the lithium transition metal compound having the layered structure may be 85 mol% or more and 99 mol% or less based on the total transition metal of the lithium transition metal compound having the layered structure. Preferably, it may be 87 mol% or more, 89 mol% or more, 90 mol% or more, 91 mol% or more, 92 mol% or more, 93 mol% or more, 94 mol% or more, 95 mol% or more, 96 mol% or more, or 97% or more. Additionally, it may be 98.5 mol% or less, 98 mol% or less, or 97.5 mol% or less. Battery capacity may be improved within the above numerical range. Meanwhile, as the operating voltage increases, there is an effect of improving energy density.

[0122] In the present invention, the lithium transition metal compound having the layered structure can be represented by the following chemical formula 2.

[0123] [Chemical Formula 2]

[0124] Li 1+t2 Ni x Co y Mn z M 2w2 O2

[0125] In the above chemical formula 2,

[0126] The above M 2 is B, Mg, Al, Si, Ca, Sc, Ti, V, Cr, K, Co, Ni, Cu, Zn, Ga, Ge, As, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, La or a combination thereof, and

[0127] -0.2≤t2<1, 0.5≤x<1, 0 <y≤0.4, 0<z≤0.4, 0≤w2≤0.1, x+y+z+w2=1이다.

[0128] In the present invention, t2 may be -0.1 or more, -0.05 or more, 0 or more, 0.01 or more, 0.02 or more, 0.03 or more, 0.04 or more, or 0.05 or more. Additionally, it may be 0.5 or less, 0.4 or less, 0.3 or less, 0.2 or less, 0.1 or less, 0.09 or less, or 0.08 or less. When t2 satisfies the above range, the capacity may increase while maintaining charge / discharge characteristics.

[0129] In the present invention, the mole fraction of nickel (Ni) among the transition metals, x / (x+y+z), may be 0.5 or more, 0.6 or more, 0.7 or more, 0.8 or more, 0.85 or more, 0.88 or more, 0.90 or more, 0.91 or more, 0.92 or more, 0.93 or more, 0.94 or more, 0.95 or more, or 0.96 or more. Additionally, it may be less than 1.0, 0.99 or less, 0.98 or less, or 0.98 or less. The battery capacity may be improved within the above numerical range. Meanwhile, as the operating voltage increases, there is an effect of improving energy density.

[0130] In the present invention, the mole fraction of cobalt (Co) among the transition metals, y / (x+y+z), may be greater than 0, 0.01 or more, 0.02 or more, or 0.03 or more. Additionally, it may be 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0131] In the present invention, the mole fraction of manganese (Mn) among the transition metals, z / (x+y+z), may be greater than 0, 0.01 or more, 0.02 or more, or 0.03 or more. Additionally, it may be 0.4 or less, 0.3 or less, 0.2 or less, or 0.1 or less.

[0132] In the present invention, w2 is an element M among transition metals. 2 The mole fraction of may be 0. Preferably, it may be 0.002 or more, 0.003 or more, 0.004 or more, 0.005 or more, 0.006 or more, 0.008 or more, or 0.01 or more. Additionally, it may be 0.05 or less, 0.04 or less, 0.03 or less, 0.02 or less, 0.015 or less, 0.013 or less, or 0.011 or less.

[0133] In the present invention, the above M 2 can be B, Al, Y, Zr, or a combination thereof. The above elements are elements that are highly effective for improving lithium ion mobility characteristics or ensuring structural stability, and depending on the combination used, the effect can be further enhanced, and when these elements are used, the above-described mathematical formula 1 can be satisfied.

[0134] In the present invention, the lithium transition metal compound having the layered structure comprises a coating portion provided on a part or all of the surface, and the coating portion comprises one or more coating elements (M) selected from the group consisting of B, Al, Y, Zr, Co, Ba, Ce, Cr, F, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo, W, P, S, Sr, Ta, La, and Hf. 3It may include ). Accordingly, the positive electrode active material may be prevented from breaking during rolling, and durability against volume change during battery charging and discharging may be improved.

[0135] In the present invention, the coating element (M 3 ) may include B, Al, Y, Zr, or a combination thereof. In this case, by reducing the density of the positive active material, the dispersibility of the positive active material is improved during the preparation of the positive slurry. Furthermore, by reducing the sedimentation of positive active material particles within the positive slurry over time during storage of the prepared positive slurry, the phenomenon of gelation—that is, aggregation between particles occurring as positive active material particles settle to the bottom within the positive slurry—can be reduced. Additionally, the above-described Equation 1 can be satisfied, and the sphericity of the positive active material can be increased. Accordingly, this can have the effect of reducing collisions between particles and friction between the stirrer and the particles during the preparation of the positive slurry.

[0136] In the present invention, the coating element (M 3 ) may be boron (B). In this case, boron-oxygen bonds (BO bonds) are formed on the surface of the lithium transition metal compound, thereby stabilizing the surface structure and preventing the lithium transition metal compound from being damaged during the harsh rolling process in electrode manufacturing. In addition, it can provide excellent structural durability capable of resisting repeated volume changes (shrinkage and expansion) of the active material accompanying continuous charge-discharge cycles. The coating element is a doping element of Chemical Formula 2 (M 2 It is different from ) in the location where it is provided, and the types may be the same.

[0137] In the present invention, the lithium transition metal compound having the layered structure may have a layered (R-3m) structure.

[0138] In the present invention, the coating portion comprises a first coating portion or a second coating portion, wherein the first coating portion is in the form of discontinuously formed islands, and the second coating portion may be in the form of a continuously formed coating layer.

[0139] In the present invention, the coating element (M) included in the coating part is 3 The content of ) may be 100 ppm or more and 5,000 ppm or less based on the total weight of the lithium transition metal compound having the layered structure. Preferably, it may be 200 ppm or more, 300 ppm or more, 400 ppm or more, 500 ppm or more, or 600 ppm or more. Additionally, it may be 4,000 ppm or less, 3,000 ppm or less, 2,000 ppm or less, 1,000 ppm or less, or 900 ppm or less. In the case where two or more coating elements are included in the coating part, the content of the coating element refers to the content of each coating element.

[0140] In the present invention, the coating element (M) included in the coating part is 3 The total content of the coating element may be 100 ppm or more and 10,000 ppm or less based on the total weight of the lithium transition metal compound having the layered structure. Preferably, it may be 200 ppm or more, 300 ppm or more, 400 ppm or more, 500 ppm or more, or 600 ppm or more. Additionally, it may be 8,000 ppm or less, 6,000 ppm or less, or 5,000 ppm or less. The total content of the coating element refers to the total content of the coating element when two or more coating elements are included in the coating portion. Within the above numerical range, electrical conductivity, surface reactivity, and mechanical strength may be improved by the coating element. On the other hand, if the coating element content falls below the above numerical range, the effect of improving physical properties by the element coating may be negligible. Conversely, if the coating element content exceeds the above numerical range, the coating element itself may form an inactive region.

[0141] In the present invention, the coating portion may be formed on the outermost surface of the lithium transition metal compound having the layered structure, and the coating portion may be formed on a part or the entire outer surface.

[0142] The present invention provides a method for manufacturing the above-described positive electrode active material, comprising the step of mixing a lithium transition metal compound having an olivine structure and a lithium transition metal compound having a layered structure.

[0143] In the present invention, the method for manufacturing the positive electrode active material comprises the step of manufacturing a lithium transition metal compound having the olivine structure.

[0144] In the present invention, the step of preparing a lithium transition metal compound having an olivine structure comprises: a step of preparing a mixture by mixing raw materials of a lithium transition metal compound having an olivine structure; and a step of calcining the mixture.

[0145] In the present invention, the raw material of the lithium transition metal compound having the olivine structure may include a lithium-containing raw material, a manganese-containing raw material, an iron-containing raw material, a phosphoric acid-containing raw material, or a combination thereof.

[0146] In the present invention, the lithium-containing raw material may be a lithium-containing sulfate, nitrate, acetate, carbonate, oxalate, citrate, halide, hydroxide, or oxyhydroxide, and is not particularly limited as long as it is soluble in water. Specifically, lithium carbonate (Li2CO3), lithium hydroxide (LiOH), and lithium nitrate (LiNO3) , It may be lithium acetate (CH3COOLi) and Li2(COO)2 or a combination thereof. Specifically, it may be lithium carbonate (Li2CO3), lithium hydroxide (LiOH), or a combination thereof.

[0147] In the present invention, the manganese-containing raw material is MnSO4, MnPO4 3,It may be at least one selected from the group consisting of MnPO4, MnCO3, MnFeO, Mn2O3, MnO2, Mn3O4, Mn(NO3)2, manganese acetate, manganese dicarboxylate, manganese citric acid, manganese fatty acid salts, oxyhydroxides, and manganese chloride halides, and one or more of these may be used.

[0148] In the present invention, the iron-containing raw material may be iron sulfate (FeSO4), iron oxide (FeO), iron oxalate (FeC2O4), iron phosphate (FePO4), iron diphosphate {Fe3(PO4)2}, or a combination thereof. Preferably, iron phosphate may be used. In this case, chemical stability is high, and since the compound itself contains phosphoric acid, the use of additional phosphates can be reduced.

[0149] In the present invention, the phosphoric acid-containing raw material may be a phosphoric acid compound, a lithium phosphate compound, an ammonium phosphate compound, or a combination thereof. Depending on the type of phosphoric acid-containing raw material, the type of gas generated during the reaction, the dissolution characteristics of the phosphoric acid-containing raw material, and the behavior of the molten phase differ. In this case, the growth and aggregation modes of the lithium transition metal compound having an olivine structure differ, and the particle size distribution of the lithium transition metal compound having an olivine structure can be controlled depending on the selection of the type of phosphoric acid-containing raw material.

[0150] In the present invention, the phosphoric acid-containing raw material may be an ammonium phosphate compound. The ammonium phosphate compound is prone to generating a gas such as ammonia during the calcination process, and the gas acts as a physical spacer between the particles, thereby preventing excessive aggregation.

[0151] In the present invention, the lithium phosphate compound may be lithium phosphate (Li3PO4), lithium monohydrogen phosphate (Li2HPO4), lithium dihydrogen phosphate (LiH2PO4), or a combination thereof.

[0152] In the present invention, the ammonium phosphate compound may be ammonium dihydrogen phosphate {(NH4)2HPO4}, ammonium monohydrogen phosphate (NH4H2PO4), or a combination thereof. In this case, gases such as ammonia generated during the calcination process can form a microstructure and inhibit particle growth. Additionally, by-products of the chemical reaction can be reduced and the pH of the reaction system can be stabilized.

[0153] In the present invention, the method for manufacturing the cathode active material may include the step of adding a raw material containing a doping element to the mixture. The doping element is substituted at manganese or iron sites during the calcination process. The doping element is substituted at some manganese sites, some iron sites, or some manganese sites and some iron sites during the calcination process.

[0154] In the present invention, the raw material containing the doping element comprises a doping element (M) comprising Mg, Al, Si, Ca, Sc, Ti, V, Cr, K, Co, Ni, Cu, Zn, Ga, Ge, As, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, La, or a combination thereof. 1 It may include ).

[0155] In the present invention, the raw material containing the doping element may be an oxide, chloride, nitrate, sulfate compound, oxalate compound, or a combination thereof of the doping element.

[0156] In the present invention, when the doping element is aluminum (Al), the raw material containing the doping element may be aluminum oxide (Al2O3), aluminum hydroxide (Al(OH)3), aluminum nitrate (Al(NO3)3), aluminum sulfate (Al2(SO4)3), aluminum dihydrogen acetate ((HO)2AlCH3CO2), aluminum monohydrogen acetate (HOAl(CH3CO2)2), aluminum acetate (Al(CH3CO2)3), aluminum halides, or a combination thereof. Preferably, aluminum hydroxide may be used. In this case, excessive temperature is not required during the doping process, and since no components other than water are detected as byproducts, it is environmentally friendly and has the effect of enabling uniform doping.

[0157] In the present invention, when the doping element is vanadium (V), the raw material containing the doping element may be vanadium oxide. The vanadium oxide may be VO2, V2O3, V2O5, or a combination thereof. Preferably, it may be V2O5. V2O5 has high reactivity, which can improve doping efficiency, and since it has excellent heat resistance, it has the effect of stably maintaining the crystal structure of a lithium transition metal compound having an olivine structure during the calcination process.

[0158] In the present invention, when the doping element is magnesium (Mg), the raw material containing the doping element may be magnesium oxide (MgO), magnesium hydroxide {Mg(OH)2}, magnesium chloride (MgCl2), or a combination thereof. Preferably, magnesium oxide may be used. Magnesium oxide has excellent thermal stability and remains intact without decomposing even during high-temperature heat treatment, and has excellent dispersibility, which has the effect of excellent doping efficiency.

[0159] In the present invention, when the doping element is zirconium (Zr), the raw material containing the doping element may be zirconium oxide (ZrO2), zirconium chloride (ZrCl4), or a combination thereof. Preferably, zirconium oxide may be used. Zirconium oxide has excellent thermal stability, so it is maintained without decomposing even during high-temperature heat treatment, and has excellent reactivity and doping efficiency.

[0160] In the present invention, when the doping element is titanium (Ti), the raw material containing the doping element may be titanium oxide (TiO2). Titanium oxide has excellent thermal stability, so it is maintained without decomposing even during high-temperature heat treatment, and has the effect of excellent reactivity.

[0161] In the present invention, the method for manufacturing the positive electrode active material may include the step of adding a carbon raw material to the mixture; the step of adding a dispersant to the mixture, or a combination thereof. The carbon raw material can form a carbon coating layer on the surface of the raw material of a lithium transition metal compound having an olivine structure by carbonizing it during the step of calcining the mixture. Additionally, the dispersant can uniformly form the carbon coating layer by evenly dispersing the carbon raw material and the raw material of the lithium transition metal compound having an olivine structure.

[0162] In the present invention, the content of the carbon raw material may be 3 wt% or more and 13 wt% or less based on the total weight of the raw material of the lithium transition metal compound having the olivine structure. Preferably, it may be 4 wt% or more, 5 wt% or more, 6 wt% or more, 7 wt% or more, or 7.5 wt% or more. Additionally, it may be 12 wt% or less, 11 wt% or less, or 10 wt% or less. Within the above numerical range, the carbon coating layer can be uniformly formed, and the positive electrode active material can satisfy the mathematical formula described above.

[0163] In the present invention, the content of the dispersant may be 20 parts by weight or more and 50 parts by weight or less based on 100 parts by weight of the carbon raw material. Preferably, it may be 25 parts by weight or more, 28 parts by weight or more, or 30 parts by weight or more. Additionally, it may be 45 parts by weight or less, 40 parts by weight or less, or 35 parts by weight or less. Within the above numerical range, a carbon coating layer can be uniformly formed.

[0164] In the present invention, the carbon raw material may be sucrose, glucose, or a combination thereof. In this case, it has the effect of easily forming a carbon coating layer by being easily thermally decomposed even at low temperatures. In addition, since sucrose is uniformly carbonized upon heat treatment and glucose is well soluble in water and easily adsorbed onto a lithium transition metal compound having an olivine structure, the carbon coating is uniformly formed and the microstructure is easy to control.

[0165] In the present invention, the dispersant may be polyethylene glycol, polyvinyl alcohol, polyvinyl acetate, or a combination thereof. Preferably, polyethylene glycol, which has a good dispersion effect, may be used.

[0166] In the present invention, the steps of adding a raw material containing a doping element to the mixture; adding a carbon raw material to the mixture; adding a dispersant to the mixture, or a combination thereof, may be performed prior to the calcination step. That is, the mixture to which the raw material containing a doping element, the carbon raw material, and the dispersant are added may be a mixture prior to calcination. At this time, there is an effect of improving the density of the lithium transition metal compound having an olivine structure prepared.

[0167] In the present invention, the solid content of the mixture may be 10 wt% or more and 40 wt% or less. Preferably, it may be 15 wt% or more, 20 wt% or more, or 25 wt% or more. Additionally, it may be 35 wt% or less or 32 wt% or less. Within this numerical range, the processability can be improved by preventing an increase in viscosity, and a uniform carbon coating can be achieved. The solid content of the mixture can be achieved by adding a solvent such as water (H2O).

[0168] In the present invention, a step of pre-grinding the mixture before the calcination step may be included.

[0169] In the present invention, a step of post-grinding the mixture after the calcination step may be included.

[0170] In the present invention, the step of pre-grinding the mixture is performed before the calcination step, and differs from the post-grinding step described later in terms of the step of execution. At this time, by controlling the particle size through grinding in advance before calcination, the reaction rate for calcination is increased, so the formation and growth of the crystal structure can be performed stably.

[0171] In the present invention, the step of pre-grinding the mixture may be performed under wet conditions and intensity conditions of 10 Hz to 100 Hz for a pre-grinding time of 0.5 hours to 10 hours. Preferably, the intensity condition may be 15 Hz or higher, 20 Hz or higher, 25 Hz or higher, or 28 Hz or higher, and 90 Hz or lower, 80 Hz or lower, 70 Hz or lower, 60 Hz or lower, 50 Hz or lower, or 40 Hz or lower. Meanwhile, the pre-grinding time may be 1 hour or higher, 1.5 hours or higher, or 2 hours or higher, and 8 hours or lower, 6 hours or lower, 4 hours or lower, or 3 hours or lower. The raw material may be uniformly ground within the above numerical ranges.

[0172] In the present invention, the calcination temperature of the step of calcining the mixture may be 500°C or higher and 900°C or lower. Preferably, it may be 600°C or higher, 650°C or higher, 680°C or higher, 690°C or higher, 700°C or higher, or 750°C or higher. Additionally, it may be 880°C or lower, 850°C or lower, 820°C or lower, or 800°C or lower. Within the above numerical range, the raw materials can react sufficiently to stably form a crystal structure, and excessive particle growth or reduction of the lithium ion migration pathway can be prevented. That is, under the above temperature conditions, the electrochemical characteristics and crystallinity of the cathode active material can be improved.

[0173] In the present invention, the firing time of the step of firing the mixture may be 1 hour or more and 50 hours or less. Preferably, it may be 2 hours or more, 3 hours or more, 4 hours or more, 6 hours or more, or 8 hours or more. Additionally, it may be 40 hours or less, 30 hours or less, 20 hours or less, or 15 hours or less. Within the above numerical range, the effect of controlling the firing temperature described above can be secured without setting the firing temperature excessively.

[0174] In the present invention, the step of calcining the mixture may be performed in a reducing atmosphere. In this case, the oxidation state of the iron ions can be easily controlled to secure electrochemical properties due to the iron ions.

[0175] In the present invention, the step of calcining the mixture may be performed under inert gas conditions. The inert gas may be argon (Ar), nitrogen (N2), or a combination thereof. The inert gas conditions may mean that the molar content of the inert gas in the space where the mixture is calcined is 70 mol% or more, 80 mol% or more, 90 mol% or more, or 95 mol% or more. The remainder of the gas may be hydrogen (H2).

[0176] In the present invention, the step of calcining the mixture can be performed in a furnace.

[0177] In the present invention, the step of post-grinding the mixture is a step of breaking up inter-particle necking and controlling particle size. In addition, it is possible to maintain a uniform particle size distribution and prevent particles from aggregating with each other.

[0178] In the present invention, the step of post-grinding the mixture may utilize bead milling, ball milling, jet milling, ultrasonic milling, or vibratory milling, or a combination thereof. In this case, jet milling may be used. Jet milling is a method of grinding particles by colliding them at high speed using high-pressure gas, and it is easy to control particle size within a very small range.

[0179] In the present invention, the jet milling may include the step of introducing the mixture into a grinding chamber having a diameter of a predetermined size by applying an introduction pressure; and the step of introducing a grinding gas into the grinding chamber by applying a grinding pressure.

[0180] In the present invention, the difference between the grinding pressure and the input pressure may be 0.1 bar or more and 3 bar or less. Preferably, it may be 0.2 bar or more, 0.3 bar or more, or 0.4 bar or more. Additionally, it may be 2.5 bar or less, 2 bar or less, 1.5 bar or less, 1 bar or less, or 0.8 bar or less. Within the above numerical range, the grinding pressure and the input pressure are similar, so the mixture can be uniformly ground to a small particle size.

[0181] In the present invention, the grinding pressure, input pressure, or a combination thereof may be 1 bar or more and 10 bar or less. Preferably, it may be 2 bar or more, 3 bar or more, 4 bar or more, or 4.5 bar or more. Additionally, it may be 9 bar or less, 8 bar or less, 7 bar or less, or 6 bar or less. Within the above numerical range, the mixture can be uniformly ground to a small particle size.

[0182] In the present invention, the diameter of the grinding chamber may be 1 inch or more and 5 inches or less. Additionally, it may be 1.2 inches or more, 1.5 inches or more, or 1.8 inches or more. Additionally, it may be 4 inches or less, 3.5 inches or less, 3 inches or less, or 2.5 inches or less. Within the above numerical ranges, sufficient energy can be supplied to uniformly grind the mixture into small particles within a short period of time.

[0183] In the present invention, the method for manufacturing the positive electrode active material includes the step of drying the mixture.

[0184] In the present invention, the step of drying the mixture is a step of removing moisture present in the mixture to ensure excellent quality in subsequent processes such as a grinding process or a calcination process.

[0185] In the present invention, the step of drying the mixture may be performed after the step of pre-grinding the mixture; before the step of calcining the mixture; before the step of post-grinding the mixture; or a combination thereof.

[0186] In the present invention, if the step of drying the mixture is performed after the step of pre-grinding the mixture, moisture introduced during the grinding step can be removed.

[0187] In the present invention, if the step of drying the mixture is performed before the step of post-grinding the mixture, the mixture is easily broken down, thereby improving the grinding efficiency.

[0188] In the present invention, if the step of drying the mixture is performed prior to the step of calcining the mixture, moisture or impurities within the material are removed, thereby improving reactivity during the calcination process and enhancing crystallinity. If moisture or impurities are not sufficiently removed before calcination, pores formed by them may occur, resulting in defects in the crystal structure.

[0189] In the present invention, the step of drying the mixture may be performed in a temperature range of 50°C to 300°C. Preferably, it may be performed in a temperature range of 80°C to 250°C or 100°C to 200°C. Within these numerical ranges, moisture can be sufficiently removed and thermal deformation of the material can be prevented. The temperature may be the average temperature of the inlet and outlet temperatures when using spray drying.

[0190] In the present invention, the step of drying the mixture may be performed for 10 minutes to 10 hours. Preferably, it may be performed for 30 minutes to 5 hours or 40 minutes to 3 hours. Within these numerical ranges, moisture is sufficiently removed, and thermal deformation of the material can be prevented.

[0191] In the present invention, the step of drying the mixture may be oven drying, vacuum drying, spray drying, or a combination thereof. Preferably, simple mass production can be achieved by using spray drying or oven drying.

[0192] In the present invention, the step of drying the mixture may be performed using spray drying at an inlet temperature of 150°C to 300°C and an outlet temperature of 60°C to 120°C. Preferably, the inlet temperature may be 160°C or higher, 180°C or higher, 200°C or higher, or 220°C or higher. Additionally, it may be 280°C or lower, 260°C or lower, or 240°C or lower. Meanwhile, the outlet temperature may be 70°C or higher, 80°C or higher, or 85°C or higher, and may be 110°C or lower, 105°C or lower, 100°C or lower, or 95°C or lower. In the inlet temperature range, the drying speed can be improved and thermal denaturation can be prevented. Additionally, in the outlet temperature range, moisture remaining in the powder can be sufficiently removed and thermal denaturation can be prevented.

[0193] In the present invention, the method for manufacturing the positive electrode active material comprises the step of manufacturing a lithium transition metal compound having the layered structure.

[0194] In the present invention, the step of manufacturing a lithium transition metal compound having a layered structure may include the step of preparing a mixture by mixing a transition metal hydroxide precursor and a lithium-containing raw material; and the step of manufacturing a calcined product by calcining the mixture. The lithium-containing raw material may be of the types described above.

[0195] In the present invention, the transition metal hydroxide precursor may be represented by the following chemical formula 3 or chemical formula 4.

[0196] [Chemical Formula 3]

[0197] Ni x Co y Mn z M 2 w2 (OH)2

[0198] [Chemical Formula 4]

[0199] Ni x Co y Mn z M2 w2 O·OH

[0200] In the above chemical formulas 3 and 4,

[0201] The definitions of x, y, z, and w2 are the same as those in Chemical Formula 2.

[0202] In the present invention, the ratio of the total moles (Me) of the transition metal included in the transition metal hydroxide precursor to the Li of the lithium-containing raw material (Me:Li) may be 1:0.98 or higher and 1:1.1 or lower. Preferably, it may be 1:0.99 or higher, 1:1 or higher, 1:1.01 or higher, or 1:1.02 or higher. Additionally, it may be 1:1.09 or lower, 1:1.08 or lower, or 1:1.06 or lower.

[0203] In the present invention, in the step of manufacturing a sintered product by calcining the mixture, primary particles of the transition metal hydroxide precursor may aggregate to produce a sintered product in the form of a single particle.

[0204] In the present invention, the firing temperature of the step of firing the mixture to produce a fired product may be 650°C or higher and 980°C or lower. Specifically, it may be 660°C or higher, 670°C or higher, 680°C or higher, 690°C or higher, 700°C or higher, 710°C or higher, or 720°C or higher. Additionally, it may be 950°C or lower, 900°C or lower, 850°C or lower, 800°C or lower, or 750°C or lower. Within the above numerical range, a structurally stable single-particle fired product may be formed as the primary particles of the transition metal hydroxide precursor aggregate.

[0205] In the present invention, the firing time of the step of firing the mixture to produce a fired product may be 3 hours or more and 20 hours or less. Preferably, it may be 4 hours or more, 6 hours or more, 8 hours or more, or 10 hours or more. Additionally, it may be 18 hours or less, 16 hours or less, or 14 hours or less. Within the above numerical range, a structurally stable single-particle fired product may be formed as the primary particles of the transition metal hydroxide precursor aggregate.

[0206] In the present invention, the step of manufacturing a sintered product by calcining the mixture may be performed two or more times. After each calcination step, a step of crushing the sintered product may be included.

[0207] In the present invention, a step of crushing the sintered product may be included. In this case, there is an effect of preventing the initial resistance from increasing.

[0208] In the present invention, the step of grinding the calcined product can be performed using a pin mill, an ACM, a jet mill, etc. Meanwhile, the pin mill can be performed at 18,000 rpm, the ACM can be performed using a machine from Hosokawa at 6,000 rpm for classification and 12,000 rpm for main grinding, and the jet mill can be performed using a machine from ZM Solution at a grinding pressure of 6 bar and a classification of 3,500 rpm. In this case, the desired average particle size (D 50 A positive electrode active material having ) can be easily obtained.

[0209] In the present invention, the step of preparing the lithium transition metal compound having the layered structure may include the step of forming a coating portion on part or all of the surface of the lithium transition metal compound having the layered structure after the step of calcining the mixture.

[0210] In the present invention, the step of forming the coating portion may include the step of mixing a coating element-containing raw material containing a coating element and a lithium transition metal compound having a layered structure; and the step of heat treatment. At this time, the coating element-containing raw material may be an oxide, hydroxide, oxyhydroxide, carbonate, sulfate, halide, sulfide, acetate, nitrate, carboxylate, or a combination thereof of the coating element.

[0211] In the present invention, the raw material containing the coating element is the coating element (M 3 It may include one or a combination thereof from the group consisting of B, Al, Y, Zr, Co, Ba, Ce, Cr, F, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo, W, P, S, Sr, Ta, La and Hf.

[0212] In the present invention, the heat treatment step may be performed under an oxygen atmosphere. At this time, the degradation of the lithium transition metal compound into a rock salt structure can be prevented.

[0213] In the present invention, the heat treatment step may include a step of heat treatment under temperature conditions of 200°C or higher and 950°C or lower. Preferably, the temperature may be 250°C or higher, 290°C or higher, and may be performed under a temperature of 900°C or lower, 880°C or lower, 850°C or lower, or 820°C or lower. If the above range is satisfied, side reactions caused by the raw material containing the coating element can be prevented.

[0214] In the present invention, the heat treatment step may include a step of heat treatment for a period of 3 hours or more and 12 hours or less. Preferably, it may be 4 hours or more, 5 hours or more, 10 hours or less, or 8 hours or less. If the above range is satisfied, side reactions caused by the raw material containing the coating element can be prevented.

[0215] The present invention provides a positive electrode comprising the positive electrode active material described above.

[0216] In the present invention, the anode comprises an anode active material layer comprising the anode active material described above. Specifically, the anode comprises an anode current collector; and an anode active material layer provided on the anode current collector. At this time, the anode active material layer may include the anode active material described above. Since the anode active material has been described above, a detailed description is omitted, and only the remaining components are described in detail below.

[0217] In the present invention, the positive current collector is not particularly limited as long as it is conductive without causing chemical changes in the battery. 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 current collector may typically have a thickness of 3 μm to 500 μm, and fine irregularities may be formed on the surface of the current collector to increase the adhesion of the positive active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0218] In the present invention, the positive active material layer may comprise a positive active material, a conductive material, and a binder. At this time, the content of the positive active material may be 80 wt% to 99 wt% based on the total weight of the positive active material layer. Specifically, it may be 85 wt% or more or 90 wt% or more. Additionally, it may be 98.5 wt% or less or 98 wt% or less. Within the above numerical range, excellent capacity characteristics may be exhibited.

[0219] In the present invention, the conductive material is used to impart conductivity to the electrode, and can be used without special limitations as long as it has conductivity without causing chemical changes in the battery. 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 fiber; metal powder or metal fiber such as copper, nickel, aluminum, or 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 one of these alone or a mixture of two or more may be used. The content of the conductive material may be 0.1 wt% to 15 wt% based on the total weight of the positive electrode active material layer.

[0220] In the present invention, the binder serves to improve the adhesion between positive active material particles and the 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, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene butadiene rubber (SBR), fluororubber, or various copolymers thereof, and one of these alone or a mixture of two or more may be used. The content of the binder may be 0.1 wt% to 15 wt% based on the total weight of the positive active material layer.

[0221] In the present invention, the anode may be manufactured according to a conventional method for manufacturing anodes, except for using the anode active material. Specifically, it may be manufactured by applying a composition for forming an anode active material layer to an anode current collector, followed by drying and rolling. Specifically, the composition for forming an anode active material layer may be one in which an anode active material, a binder, and a conductive material are dissolved or dispersed in a solvent. In this case, the types and contents of the anode active material, binder, and conductive material are as described above. Alternatively, the anode may be manufactured by casting the composition for forming an anode active material layer onto a separate support, and then laminating the film obtained by peeling from the support onto an anode current collector.

[0222] In the present invention, the solvent may be a solvent generally used in the relevant technical field, such as dimethyl sulfoxide (DMSO), isopropyl alcohol, N-methylpyrrolidone (NMP), acetone, or water, and one of these alone or a mixture of two or more may be used. The amount of solvent used is sufficient if it has a viscosity that dissolves or disperses the cathode 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 cathode manufacturing.

[0223] The present invention provides an electrochemical device comprising the anode described above. Specifically, the electrochemical device may be a battery, a capacitor, etc., and more specifically, may be a lithium secondary battery.

[0224] The present invention provides a lithium secondary battery comprising the anode described above.

[0225] In the present invention, the lithium secondary battery specifically comprises a positive electrode and a negative electrode positioned opposite to the positive electrode. Additionally, it comprises a separator and an electrolyte provided between the positive electrode and the negative electrode. Since the positive electrode is identical to the one described above, a detailed description is omitted, and only the remaining components are described in detail below.

[0226] In the present invention, the lithium secondary battery may optionally further include a battery container housing an electrode assembly comprising the positive electrode, the negative electrode, and a separator, and a sealing member sealing the battery container.

[0227] In the present invention, the cathode comprises a cathode current collector and a cathode active material layer provided on the cathode current collector.

[0228] In the present invention, 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., and aluminum-cadmium alloy may be used. In addition, the negative electrode current collector may typically have a thickness of 3 μm to 500 μm, and, similar to the positive electrode current collector, fine irregularities may be formed on the surface of the current collector to strengthen the bonding strength of the negative electrode active material. For example, it may be used in various forms such as a film, sheet, foil, net, porous body, foam, nonwoven fabric, etc.

[0229] In the present invention, the negative electrode active material layer optionally includes a binder and a conductive material together with the negative electrode active material.

[0230] In the present invention, the negative electrode active material may be a compound capable of reversible intercalation and deintercalation of lithium. Specific examples include carbonaceous materials; metallic compounds; metal oxides; composites thereof; or mixtures thereof. The carbonaceous materials include artificial graphite, natural graphite, graphitized carbon fiber, amorphous carbon, etc. The metallic compounds include 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. The metal oxides include metal oxides capable of doping and dedoping lithium, such as vanadium oxide and lithium vanadium oxide. The composites include composites comprising the metallic compounds and carbonaceous materials, such as Si-C composites or Sn-C composites.

[0231] In the present invention, the carbonaceous 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.

[0232] In the present invention, a metal lithium thin film may be used as the negative electrode active material.

[0233] In the present invention, the content of the negative electrode active material may be 80 wt% to 99 wt% based on the total weight of the negative electrode active material layer.

[0234] In the present invention, the binder is a component that assists in the bonding between the conductive material, the active material, and the current collector, and can typically be added in an amount of 0.1 wt% to 10 wt% relative to the total weight of the negative active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethylcellulose (CMC), starch, hydroxypropylcellulose, regenerated cellulose, polyvinylpyrrolidone, tetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated-EPDM, styrene-butadiene rubber, nitrile-butadiene rubber, fluororubber, and various copolymers thereof.

[0235] In the present invention, the conductive material may be added as a component to further improve the conductivity of the negative electrode active material in an amount of 10 wt% or less, specifically 5 wt% or less, based on the total weight of the negative electrode active material layer. Such conductive material is not particularly limited as long as it is conductive without causing chemical changes in the battery, and for example, graphite such as natural graphite or artificial graphite; carbon black such as acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black; conductive fibers such as carbon fibers or metal fibers; metal powders such as carbon fluoride, aluminum, or nickel powder; conductive whiskers such as zinc oxide or potassium titanate; conductive metal oxides such as titanium oxide; conductive materials such as polyphenylene derivatives, etc. may be used.

[0236] In the present invention, the cathode may be manufactured according to a conventional method for manufacturing a cathode, except for using the cathode active material. Specifically, it may be manufactured by applying a composition for forming a cathode active material layer to a cathode current collector, followed by drying and rolling. Specifically, the composition for forming a cathode active material layer may be one in which a cathode active material, a binder, and a conductive material are dissolved or dispersed in a solvent. At this time, the types and contents of the cathode active material, binder, and conductive material are as described above. Alternatively, the cathode may be manufactured by casting the composition for forming a cathode active material layer onto a separate support, and then laminating the film obtained by peeling from the support onto a cathode current collector.

[0237] In the present invention, the separator separates the negative electrode and the positive electrode and provides a pathway for the movement of lithium ions. Any separator commonly used in lithium secondary batteries can be used without special limitations, and it is particularly desirable that it has low resistance to the movement of electrolyte ions and excellent electrolyte moisture retention capacity. Specifically, a porous polymer film, such as a porous polymer film made of a polyolefin-based polymer like 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, such as a nonwoven fabric made of high-melting-point glass fibers or polyethylene terephthalate fibers, may be used. Furthermore, a coated separator containing a ceramic component or a polymer material may be used to ensure heat resistance or mechanical strength, and it may optionally be used in a single-layer or multi-layer structure.

[0238] In the present invention, the electrolyte may be an organic liquid electrolyte, an inorganic liquid electrolyte, a solid polymer electrolyte, a gel-type polymer electrolyte, a solid inorganic electrolyte, a molten inorganic electrolyte, etc., which can be used in the manufacture of a lithium secondary battery, but is not limited to these.

[0239] In the present invention, the electrolyte may include an organic solvent and a lithium salt.

[0240] In the present invention, the organic solvent may be used without special limitations 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 be an ester-based solvent such as methyl acetate, ethyl acetate, γ-butyrolactone, or ε-caprolactone; an ether-based solvent such as dibutyl ether or tetrahydrofuran; a ketone-based solvent such as cyclohexanone; or an aromatic hydrocarbon-based solvent such as benzene or fluorobenzene. Carbonate-based solvents such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethylmethyl 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 2 to 20 carbon atoms and may include a double aromatic ring or 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 and 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.

[0241] In the present invention, the lithium salt can be used without special limitations 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, 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 5.0 M, specifically 0.1 to 3.0 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.

[0242] In the present invention, the electrolyte may further include additives in addition to the electrolyte components. These additives are intended to improve the lifespan characteristics of the battery, suppress the reduction of battery capacity, and improve the discharge capacity of the battery. The additives may include haloalkylene carbonate compounds such as difluoroethylene carbonate, pyridine, triethylphosphite, triethanolamine, cyclic ether, ethylene diamine, n-glyce, triamide hexaphosphate, nitrobenzene derivatives, sulfur, quinone imine dyes, N-substituted oxazolidinone, N,N-substituted imidazolidine, ethylene glycol dialkyl ether, ammonium salts, pyrrole, 2-methoxyethanol, aluminum trichloride, or combinations thereof. In this case, the total content of the additives may be 0.1 wt% to 10 wt% based on the total weight of the electrolyte. Specifically, it may be 0.2 wt% or more or 1 wt% or more, and 8 wt% or less or 5 wt% or less.

[0243] The positive electrode active material of the present invention has the effect of improving lifespan characteristics or capacity characteristics when applied to a lithium secondary battery. In this case, the lithium secondary battery is useful in fields such as portable devices like mobile phones, laptop computers, and digital cameras, and electric vehicles such as hybrid electric vehicles (HEVs).

[0244] The present invention can provide a battery module including the above-described lithium secondary battery as a unit cell and a battery pack including the same.

[0245] In the present invention, the battery module or battery pack may be used as a power source for one or more medium-to-large devices, including a power tool; an electric vehicle (EV), a hybrid electric vehicle, and a plug-in hybrid electric vehicle (PHEV); or a power storage system.

[0246] In the present invention, the external shape of the lithium secondary battery is not particularly limited, but can be a cylindrical shape using a can, a prismatic shape, a pouch shape, or a coin shape.

[0247] In the present invention, the lithium secondary battery can be used not only as a battery cell used as a power source for a small device, but can also preferably be used as a unit cell in a medium-to-large battery module comprising a plurality of battery cells.

[0248] Hereinafter, embodiments of this specification are described in detail so that those skilled in the art to which this specification pertains can easily implement them. However, this specification may be implemented in various different forms and is not limited to the embodiments described herein.

[0249] <Preparation Example>

[0250] <Preparation Examples 1 to 2: Preparation of Lithium Transition Metal Compounds Having an Olivine Structure>

[0251] LMFP-1 and LMFP-2 were manufactured using the following method.

[0252] <Preparation Example 1: Preparation of LMFP-1>

[0253] lithium-containing raw material (Li2CO3) as a raw material for lithium transition metal compounds having an olivine structure, A mixture was prepared by mixing a manganese-containing raw material (MnPO3), an iron-containing raw material (FePO4), and a phosphoric acid-containing raw material (NH4H2PO4) such that the molar ratio of the raw materials (Li:Mn:Fe:PO4) was 1:0.3:0.7:1.

[0254] Sucrose was added as a carbon source at 10 wt% based on the total weight of the solids in the above mixture, and water was mixed to achieve a solid content of 30 wt%. Subsequently, by wet grinding, a slurry (average particle size D) was prepared. 50 : 0.4㎛) was manufactured.

[0255] The above slurry was introduced into a spray dryer and sprayed, the inlet temperature of the drying air entering the spray dryer was adjusted to 235℃, the outlet temperature of the air exiting from the spray dryer was set to 90℃, and moisture was removed by drying for 1 hour.

[0256] The above-mentioned water-removed slurry was fed into a furnace and fired at a temperature of 694°C for 10 hours to produce a fired product.

[0257] By grinding the above-mentioned calcined product using a jet mill grinder having a grinding chamber diameter of 2 inches at an injection pressure of 5.5 bar and a grinding pressure of 5 bar, LiMn 0.3 Fe 0.7 A lithium transition metal compound having an olivine structure with a composition represented by PO4 was prepared. At this time, the average particle size (D 50 ) was 0.5㎛.

[0258] <Preparation Example 2: Preparation of LMFP-2>

[0259] lithium-containing raw material (Li2CO3) as a raw material for lithium transition metal compounds having an olivine structure, A mixture was prepared by mixing a manganese-containing raw material (MnPO3), an iron-containing raw material (FePO4), and a phosphoric acid-containing raw material (NH4H2PO4) such that the molar ratio of the raw materials (Li:Mn:Fe:PO4) was 1.02:0.3:0.7:1.

[0260] Based on the total weight of the solids in the above mixture, 7 wt% of sucrose, a carbon raw material, was added, and water was mixed to achieve a solid content of 34 wt%. Subsequently, by wet grinding, a slurry (average particle size D) was prepared. 50 : 0.4㎛) was manufactured.

[0261] The above slurry was introduced into a spray dryer and sprayed, the inlet temperature of the drying air entering the spray dryer was adjusted to 235℃, the outlet temperature of the air exiting from the spray dryer was set to 90℃, and moisture was removed by drying for 1 hour.

[0262] The above-mentioned water-removed slurry was fed into a furnace and fired at a temperature of 698°C for 10 hours to produce a fired product.

[0263] By grinding the above-mentioned calcined product using a jet mill grinder having a grinding chamber diameter of 4 inches at an injection pressure of 5 bar and a grinding pressure of 1.5 bar, Li 1.02 Mn 0.3 Fe 0.7 A lithium transition metal compound having an olivine structure with a composition represented by PO4 was prepared. At this time, the average particle size (D 50 ) was 0.92㎛.

[0264] <Preparation Examples 3 to 6: Preparation of Lithium Transition Metal Compounds Having a Layered Structure>

[0265] NCM-1 to NCM-4 were prepared by the following method.

[0266] <Preparation Example 3: Preparation of NCM-1>

[0267] Average particle size (D) of transition metal hydroxide precursor 50 Ni with a ) of 10.9㎛ 0.97 Co 0.01 Mn 0.02 LiOH was prepared using (OH)2 and a lithium-containing raw material. A mixture was prepared by mixing a transition metal hydroxide precursor and a lithium-containing raw material such that the molar ratio of lithium to transition metal [Li / (Ni+Co+Mn)] was 1.06.

[0268] The above mixture was fired under an oxygen atmosphere at a firing temperature of 725°C for a firing time of 12 hours to produce a fired product.

[0269] The above-mentioned calcined product was cleaned by mixing it with distilled water, stirring for 10 minutes, and then filtering for 20 minutes.

[0270] The cleaned fired product was placed in a vacuum oven, dried at a temperature of 130°C, and then sieved.

[0271] Subsequently, a mixture was prepared by mixing the calcined product with B(OH)3, a boron-containing raw material. The mixture was introduced into a furnace and heat-treated for 5 hours under an air atmosphere and a heat treatment temperature of 300°C to produce NCM-1, a lithium transition metal compound having a boron-coated layered structure. At this time, the boron content was set to 700 ppm based on the total weight of the NCM-1 solids, and the average particle size (D) of NCM-1 50 ) was 11.2㎛.

[0272] <Preparation Example 4: Preparation of NCM-2>

[0273] Average particle size (D) of transition metal hydroxide precursor 50 Ni with ) of 3.1㎛ 0.97 Co 0.01 Mn 0.02 NCM-2, a lithium transition metal compound having a layered structure, was prepared using the same method as NCM-1, except that (OH)2 was used. At this time, the average particle size of NCM-2 (D 50 ) was 3.5㎛.

[0274] <Preparation Example 5: Preparation of NCM-3>

[0275] Ni as a transition metal hydroxide precursor 0.88 Co 0.05 Mn 0.07LiOH was prepared using (OH)2 and a lithium-containing raw material. A mixture was prepared by mixing a transition metal hydroxide precursor and a lithium-containing raw material such that the molar ratio of lithium to transition metal [Li / (Ni+Co+Mn)] was 1.04.

[0276] The above mixture was fired under an oxygen atmosphere at a firing temperature of 725°C for a firing time of 12 hours to produce a fired product.

[0277] The above-mentioned calcined product was cleaned by mixing it with distilled water, stirring for 10 minutes, and then filtering for 20 minutes.

[0278] The cleaned fired product was placed in a vacuum oven, dried at a temperature of 130°C, and then sieved.

[0279] Subsequently, a mixture was prepared by mixing the calcined product with B(OH)3, a boron-containing raw material. The mixture was introduced into a furnace and heat-treated for 5 hours under an air atmosphere and a heat treatment temperature of 300°C to produce NCM-3, a lithium transition metal compound having a boron-coated layered structure. At this time, the boron content was set to 700 ppm based on the total weight of the NCM-3 solids, and the average particle size (D) of NCM-3 50 ) was 11.2㎛.

[0280] <Preparation Example 6: Preparation of NCM-4>

[0281] Aluminum-doped lithium transition metal oxide (LiNi 0.86 Co 0.05 Mn 0.08 Al 0.01 O2) was prepared. At this time, the ratio of Ni:Co:Mn:Al was 86:5:8:1, and the average particle size (D 50 ) was 10.7㎛.

[0282] <Examples and Comparative Examples>

[0283] <Example 1>

[0284] A positive electrode active material was prepared by mixing LMFP-1, a lithium transition metal compound having an olivine structure, and NCM-1, a lithium transition metal compound having a layered structure. At this time, the content of the lithium transition metal compound having a layered structure (W) based on the total weight of the lithium transition metal compound having an olivine structure LO ) was 42.8wt%.

[0285] <Example 2>

[0286] A positive electrode active material was prepared in the same manner as in Example 1, except that NCM-2 was used instead of NCM-1 as a lithium transition metal compound having a layered structure.

[0287] <Example 3>

[0288] A positive electrode active material was prepared in the same manner as in Example 1, except that NCM-3 was used instead of NCM-1 as a lithium transition metal compound having a layered structure.

[0289] <Comparative Example 1>

[0290] A positive electrode active material was prepared in the same manner as in Example 1, except that LMFP-2 was used instead of LMFP-1 as a lithium transition metal compound having an olivine structure.

[0291] <Comparative Example 2>

[0292] A positive electrode active material was prepared in the same manner as in Example 1, except that LMFP-2 was used instead of LMFP-1 as the lithium transition metal compound having an olivine structure, and NCM-4 was used instead of NCM-1 as the lithium transition metal compound having a layered structure.

[0293] <Experimental Example>

[0294] <Experimental Example 1: X-ray Diffraction Pattern Analysis>

[0295] Rolling was performed on the cathode active materials prepared in the examples and comparative examples, and values ​​calculated using Equation 1 below were derived for the cathode active materials before and after rolling and recorded in Table 1 below. The density of the cathode active material before rolling was 1.4 g / cm³ 3 and the density of the cathode active material after rolling is 2.3 g / cm³ 3 It was.

[0296] The above X-ray diffraction pattern analysis equipment used was the Bruker D8 Endeavor instrument (light source: Cu Kα, λ=1.54Å, voltage: 45kV, current: 40mA, and 2θ: range from 15 to 115 degrees). At this time, the height of the peak with the greatest height among the peaks with a 2θ angle of 19 to 21 degrees was (101) plane peak intensity (I 101 ) and the height of the peak with the highest height among peaks where the 2θ angle is 29 to 32 degrees was set as the intensity of the (020) plane peak. At this time, the intensity of the (101) plane peak (I 101 ) was defined as the peak intensity that appeared at a 2θ angle of approximately 20.6 degrees, and (020) plane peak intensity was defined as the peak intensity that appeared at a 2θ angle of approximately 29.7 degrees.

[0297] [Mathematical Formula 1]

[0298] |(P1-P0)| / P0×100(%)

[0299] In mathematical formula 1,

[0300] P1 is the crystal plane orientation index of the positive active material after rolling, and

[0301] P0 is the crystal plane orientation index of the positive active material before rolling, and

[0302] The above crystal plane orientation index is the ratio of the intensity of the (101) plane peak to the intensity of the (020) plane peak in the X-ray diffraction pattern of the positive active material (I 101 The ratio of )(I 101 / I 020 )am.

[0303] <Experimental Example 2: Analysis of Relationship between Particle Size and Content>

[0304] For the cathode active materials prepared in the examples and comparative examples, values ​​calculated using the following mathematical formulas 2 and 3 were derived and recorded in Table 1 below. Specifically, the physical property information of the lithium transition metal compound having an olivine structure and the lithium transition metal compound having a layered structure recorded in the above-described preparation examples was utilized.

[0305] [Mathematical Formula 2]

[0306] (D O ) / {D O +D L ×(W LO / 100)}*(D L ×M Ni )

[0307] [Mathematical Formula 3]

[0308] D O / W CO *100(%)

[0309] In mathematical formulas 2 and 3,

[0310] D O The average particle size (D) of the lithium transition metal compound having the above olivine structure 50 , unit:㎛) and,

[0311] D L is the average particle size (D) of the lithium transition metal compound having the above layered structure. 50 , unit:㎛) and,

[0312] W LO is the content (unit: wt%) of the lithium transition metal compound having a layered structure based on the total weight of the lithium transition metal compound having the olivine structure, and

[0313] M Ni is the molar content of nickel (unit: mol%) based on the total number of moles of transition metal in the lithium transition metal compound having the above layered structure, and

[0314] W COis the content of carbon-containing raw materials included in the lithium transition metal compound having the olivine structure based on the total weight of the lithium transition metal compound having the olivine structure (unit: wt%).

[0315] <Experimental Example 3: Battery Performance Evaluation>

[0316] The positive active material, carbon black conductive material, and polyvinylidene fluoride (PVdF) binder prepared in the examples and comparative examples, respectively, were mixed in a weight ratio of 90:5:5 in an N-methylpyrrolidone solvent to prepare a positive composite material, which was then coated on one side of an aluminum current collector, dried at 130°C, and rolled to produce a positive electrode. Lithium metal was prepared as the negative electrode.

[0317] An electrode assembly was manufactured by providing a porous polyethylene separator between the manufactured positive and negative electrodes, and after placing the electrode assembly inside a case, an electrolyte was injected into the case to manufacture a lithium secondary battery half cell. At this time, the electrolyte was prepared by dissolving 1 M concentration lithium hexafluorophosphate (LiPF6) in an organic solvent composed of ethylene carbonate / ethyl methyl carbonate / diethyl carbonate / (EC / EMC / DEC = 1 / 2 / 1 volume ratio).

[0318] For the manufactured half-cell, a charge-discharge experiment was conducted by charging at 25°C in CCCV mode at 0.2C until it reached 4.25V (termination current 1 / 20C), and discharging at a constant current of 0.1C until it reached 2.5V. The charge capacity and discharge capacity were calculated, and the ratio (%) of discharge capacity to charge capacity was evaluated as efficiency.

[0319] <Experimental Example 4: Evaluation of Cycle Capacity Retention Rate>

[0320] For half cells manufactured in the same way, 30 charge / discharge cycles were performed at 45°C in CCCV mode within a driving voltage range of 2.5V to 4.25V under conditions of 0.5C / 1C, and the cycle capacity retention rate, which is the ratio of the discharge capacity at the 30th cycle to the initial capacity after 30 charge / discharge cycles, was measured.

[0321] Classification Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Experimental Example 1 Mathematical Formula 11.708%1.966%6.544%14.668%17.243%P00.74340.75780.77470.9640.9366P10.73070.74290.7240.82260.7751 Experimental Example 2 Mathematical Formula 2102.68593.1174.9153.9 Mathematical Formula 355513.113.1D O (Unit: ㎛) 0.5 0.5 0.5 0.9 20.9 2D L (Unit: ㎛) 11.2 3.5 11.2 11.2 10.7 W LO (Unit: wt%) 42.842.842.842.842.8M Ni (Unit: mol%) 9797889786W CO (Unit: wt%) 10 10 10 77 Experimental Example 3 Charge Capacity (mAh) 18 3.2 18 0.8 18 2.2 18 1.8 17 9.2 Discharge Capacity (mAh) 17 5 17 7.9 17 3.6 17 1.5 17 0.2 Efficiency (%) 95 5 9 8.4 95 39 4.4 95 Experimental Example 4 Cycle Capacity Retention Rate (%) 99 6 9 9.2 10 0 95 5 9 7.8

[0322] From the above results, it was confirmed that the positive active material with a value of 14% or less calculated by Equation 1 has excellent charge-discharge efficiency and cycle capacity retention rate (Examples 1 to 3).

[0323] On the other hand, it was confirmed that the charge-discharge efficiency and cycle capacity retention rate of the positive active material with a value exceeding 14% calculated by Equation 1 decreased (Comparative Examples 1 and 2).

Claims

1. A lithium transition metal compound having an olivine structure; and It includes a lithium transition metal compound having a layered structure, and Anode active material with a value of 14% or less calculated by the following mathematical formula 1: [Mathematical Formula 1] |(P1-P0)| / P0×100(%) In mathematical formula 1, P1 is the crystal plane orientation index of the positive active material after rolling, and P0 is the crystal plane orientation index of the positive active material before rolling, and The above crystal plane orientation index is the ratio of the intensity of the (101) plane peak to the intensity of the (020) plane peak in the X-ray diffraction pattern of the positive active material (I 101 The ratio of )(I 101 / I 020 )am.

2. In Claim 1, A positive active material having a crystal plane orientation index (P1) of the positive active material after rolling of the above-mentioned above, which is 0.1 or greater and 1 or less.

3. In Claim 1, The 2θ angle at which the (101) plane peak appears in the X-ray diffraction pattern of the positive electrode active material is 19 to 21 degrees, and A positive active material in which the 2θ angle at which the above (020) plane peak appears is 29 to 32 degrees.

4. In Claim 1, Anode active material with a value of 150 or less calculated by the following mathematical formula 2: [Mathematical Formula 2] (D O ) / {D O +D L ×(W LO / 100)}*(D L ×M Ni ) In mathematical formula 2, D O The average particle size (D) of the lithium transition metal compound having the above olivine structure 50 , unit:㎛) and, D L is the average particle size (D) of the lithium transition metal compound having the above layered structure. 50 , unit:㎛) and, W LO is the content (unit: wt%) of the lithium transition metal compound having a layered structure based on the total weight of the lithium transition metal compound having the olivine structure, and M Ni is the molar content of nickel (unit: mol%) based on the total number of moles of transition metal in the lithium transition metal compound having the above layered structure.

5. In Claim 1, Average particle size (D) of the lithium transition metal compound having the above olivine structure 50 A positive electrode active material having a thickness of 0.1㎛ or more and 10㎛ or less.

6. In Claim 1, Average particle size (D) of the lithium transition metal compound having the above layered structure 50 A positive electrode active material having a thickness of 1㎛ or more and 20㎛ or less.

7. In Claim 1, The lithium transition metal compound having the above olivine structure is a positive electrode active material comprising a lithium iron phosphate manganese-based compound.

8. In Claim 1, A positive electrode active material having a manganese content of 10 mol% or more and 90 mol% or less based on the total transition metal of the lithium transition metal compound having the olivine structure.

9. In Claim 1, The lithium transition metal compound having the above olivine structure is a positive active material represented by the following chemical formula 1: [Chemical Formula 1] Li 1+t1 Mn a Fe b M 1 w1 (PO4) In the above chemical formula 1, The above M 1 is B, Mg, Al, Si, Ca, Sc, Ti, V, Cr, K, Co, Ni, Cu, Zn, Ga, Ge, As, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, La, or a combination thereof, and -0.2≤t1<1, 0<a<1, 0<b<1, 0≤w1<1, a+b+w1=1.

10. In Claim 1, A positive electrode active material having a lithium transition metal compound having the above layered structure, wherein the nickel content of the lithium transition metal compound having the above layered structure is 85 mol% or more and 99 mol% or less based on the total transition metal of the lithium transition metal compound having the above layered structure.

11. In Claim 1, The lithium transition metal compound having the above layered structure is an anode active material represented by the following chemical formula 2: [Chemical Formula 2] Li 1+t2 Ni x Co y Mr z M 2 w2 O2 In the above chemical formula 2, The above M 2 is B, Mg, Al, Si, Ca, Sc, Ti, V, Cr, K, Co, Ni, Cu, Zn, Ga, Ge, As, Sr, Y, Zr, Nb, Mo, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, Tl, Pb, Bi, La or a combination thereof, and -0.2≤t2<1, 0.5≤x<1, 0 <y≤0.4, 0<z≤0.4, 0≤w2≤0.1, x+y+z+w2=1이다.

12. In Claim 1, The lithium transition metal compound having the above layered structure includes a coating portion provided on part or all of the surface, and The above coating part comprises one or more coating elements (M) selected from the group consisting of B, Al, Y, Zr, Co, Ba, Ce, Cr, F, Mg, V, Ti, Fe, Zn, Si, Nb, Ga, Sn, Mo, W, P, S, Sr, Ta, La, and Hf. 3 A positive electrode active material containing ).

13. A positive electrode comprising a positive electrode active material according to any one of claims 1 to 12.

14. A lithium secondary battery comprising a positive electrode according to claim 13.