Positive electrode active material precursor

Abstract

The present invention relates to a positive electrode active material precursor having a secondary particle form formed by aggregating a plurality of primary particles and an average value of a structure orientation DoAcrystal value of 0.5 or more represented by the following Equation 1: [Equation 1] DoAcrystal = sin 2 θ, where θ is an angle between a vector in a straight line direction from the center of the secondary particle to the surface and a vector in the c-axis direction of the crystal grain after obtaining a TEM image of a cross section of the positive electrode active material precursor.

Description

Technical Field

[0001] Cross-reference of related applications

[0002] This application claims priority to Korean Patent Application No. 10-2024-0037382, filed on March 18, 2024, the entire contents of which are incorporated herein by reference for all purposes. Technical Field

[0004] This invention relates to cathode active material precursors, and more specifically, to cathode active material precursors for lithium secondary batteries, which can achieve cathode active materials with excellent lifetime and lifetime tolerance characteristics by ensuring optimal lithium migration pathways within the particles and improving structural stability during charging and discharging. Background Technology

[0005] Recently, with technological advancements and increasing demand for mobile devices and electric vehicles, the demand for secondary batteries as an energy source is rapidly increasing. Among secondary batteries, lithium-ion batteries, characterized by high energy density and voltage, long cycle life, and low self-discharge rate, have been commercialized and are widely used.

[0006] As positive electrode active materials for lithium secondary batteries, lithium transition metal oxides such as lithium cobalt oxides such as LiCoO2, lithium nickel oxides such as LiNiO2, lithium manganese oxides such as LiMnO2 or LiMn2O4, and lithium iron phosphate oxides such as LiFePO4 have been developed. More recently, lithium composite transition metal oxides containing two or more transition metals, such as Li[Ni], have been developed and are widely used. a Co b Mn c O2, Li[Ni a Co b Al c ]O2 and Li[Ni a Co b Mn c Al d O2.

[0007] Lithium-containing composite transition metal oxides, which have been developed to date, are typically fabricated as spherical secondary particles in which tens to hundreds of primary particles are aggregated. However, physical properties such as lithium-ion mobility and electrolyte impregnation vary depending on the orientation or shape (aspect ratio) of the primary particles. Therefore, research is underway to improve the performance of cathode active materials by controlling the particle structure of the cathode active material particles.

[0008] In this regard, it is known that the lithium-ion migration distance can be advantageously shortened by shaping the primary particles of the positive electrode active material precursor into rod or columnar shapes, or by aligning the primary particles radially from the center of the secondary particles toward the surface. However, a drawback of these morphological factors is that they cannot accurately represent actual battery performance due to the lack of information about the crystal structure of the particles.

[0009] To compensate for this problem, XRD can be used to determine crystal structure information, but it is limited in analyzing the crystal structure of micro-regions due to the limitation of beam size. Although it is known that quantitative analysis by integrating the diffraction peaks is possible, it has the disadvantage of requiring comparable reference samples or additional measurement information (FT-IR).

[0010] Therefore, it is necessary to study the grain structure of the positive electrode active material precursor, which is essentially representative of battery performance. Summary of the Invention

[0011] Technical issues

[0012] The present invention aims to solve the above problems and to provide a positive electrode active material precursor with an average DoA crystal value of 0.5 or greater, wherein the average DoA crystal value is a parameter that can indicate structural orientation, and the positive electrode active material precursor can realize a positive electrode active material with excellent lifetime and lifetime tolerance characteristics.

[0013] Technical solution

[0014] This invention provides a precursor for a positive electrode active material.

[0015] (1) The present invention provides a positive electrode active material precursor having a secondary particle form formed by aggregating multiple primary particles and an average DoA crystal value of 0.5 or greater according to the following Equation 1.

[0016] [Equation 1]

[0017] DoA crystal = sin 2 θ

[0018] Where θ is the angle between the vector along the straight line from the center of the secondary particle to the surface and the vector along the c-axis of the grain after obtaining a TEM image of the cross-section of the positive electrode active material precursor.

[0019] (2) The present invention provides a positive electrode active material precursor according to (1) above, wherein the average value of the DoA crystal value is 0.6 or greater.

[0020] (3) The present invention provides a positive electrode active material precursor according to (1) or (2) above, wherein the average value of the DoA crystal value is 0.7 or greater.

[0021] (4) The present invention provides the positive electrode active material precursor according to any one of (1) to (3) above, wherein the average value of L value of the positive electrode active material precursor according to the following Equation 2 is 0.3 or greater:

[0022] [Equation 2]

[0023] L = (a-axis length of crystal grain) / (c-axis length of crystal grain)

[0024] wherein the a-axis length of the crystal grain is the length of the longest axis among vectors passing through the crystal grain in the a-axis direction, and the c-axis length of the crystal grain is the length of the longest axis among vectors passing through the crystal grain in the c-axis direction.

[0025] (5) The present invention provides the positive electrode active material precursor according to (4) above, wherein the average value of L value is 0.4 or greater.

[0026] (6) The present invention provides the positive electrode active material precursor according to (4) or (5) above, wherein the average value of L value is 0.5 or greater.

[0027] (7) The present invention provides the positive electrode active material precursor according to any one of (1) to (6) above, wherein the positive electrode active material precursor comprises a composite transition metal hydroxide represented by the following Chemical Formula 1:

[0028] [Chemical Formula 1]

[0029] Ni a Co b Mn c M d (OH)₂

[0030] wherein M is at least one element selected from the group consisting of Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo,

[0031] 0.6 ≤ a < 1.0, 0 < b < 0.4, 0 < c < 0.4, and 0 ≤ d ≤ 0.2.

[0032] (8) The present invention provides the positive electrode active material precursor according to any one of (1) to (7) above, wherein the BET specific surface area of the positive electrode active material precursor is 2.0 m 2 / g to 15.0 m 2 / g.

[0033] (9) The present invention provides the positive electrode active material precursor according to any one of (1) to (8) above, wherein the BET specific surface area of the positive electrode active material precursor is 3.0 m2 / g to 15.0 m 2 / g.

[0034] (10) The present invention provides a positive electrode active material precursor according to any one of (1) to (9) above, wherein the average particle size (D) of the positive electrode active material precursor is... 50 The range is from 2.0 μm to 20.0 μm.

[0035] Beneficial effects

[0036] The cathode active material precursor of the present invention satisfies an average DoA crystal value of 0.5 or greater (which is a parameter that can indicate the structural orientation of the grains), thereby enabling the realization of a cathode active material with optimal lithium mobility and improved structural stability during charging and discharging. Attached Figure Description

[0037] Figure 1 A diagram illustrating the differences in structural and shape orientations based on the cross-sections of single-crystal primary grains with triaxial elliptical shapes.

[0038] Figures 2 to 4 The images shown are, in order: a TEM image of the positive electrode active material precursor according to Example 1, a c-axis pattern, and an image showing the DoA crystal and the angle between the c-axis and the xy plane.

[0039] Figures 5 to 7 The images shown are, in order: a TEM image of the positive electrode active material precursor according to Example 2, a c-axis pattern, and an image showing the DoA crystal and the angle between the c-axis and the xy plane.

[0040] Figures 8 to 10 The images shown are, in order: a TEM image of the positive electrode active material precursor according to Example 3, a c-axis pattern, and an image showing the DoA crystal and the angle between the c-axis and the xy plane.

[0041] Figures 11 to 13 The images shown are, in order: a TEM image of the positive electrode active material precursor according to Example 4, a c-axis pattern, and an image showing the DoA crystal and the angle between the c-axis and the xy plane. Detailed Implementation

[0042] The terms or words used in the specification and claims of this application should not be construed as limited to their ordinary or dictionary meanings, but should be interpreted as meanings and concepts consistent with the technical spirit of the invention, based on the principle that the inventor can adequately define the concepts of the terms to best describe his invention.

[0043] In this invention, "crystal" refers to a single-crystal particle unit with a regular atomic arrangement.

[0044] In this invention, a "primary particle" refers to the smallest particle unit that is distinguished as a single block when the cross-section of the positive electrode active material is observed using a scanning electron microscope (SEM), and can be formed by one grain or a plurality of grains. In this invention, the average particle size of the primary particles can be measured by measuring the size of each particle distinguished in the cross-sectional SEM data of the positive electrode active material.

[0045] In this invention, "secondary particles" refers to a secondary structure formed by aggregating multiple primary particles. The average particle size of the secondary particles can be measured using a particle size analyzer, and in this invention, the Microtrac S3500 is used as the particle size analyzer.

[0046] The present invention will be described in detail below.

[0047] The inventors conducted repeated research to develop a cathode active material precursor that can achieve an optimal lithium migration path within the particles and improved structural stability during charging and discharging. As a result, it was found that when the average value of the DoA crystal value (which is a parameter that can indicate structural orientation) is 0.5 or greater, the excellent lifespan and lifespan tolerance characteristics of the secondary battery can be improved, thus completing the present invention.

[0048] Positive electrode active material precursor

[0049] The positive electrode active material precursor according to the present invention is characterized by having a secondary particle form formed by aggregating multiple primary particles, and satisfying an average DoA crystal value of 0.5 or greater, as expressed by the following Equation 1:

[0050] [Equation 1]

[0051] DoA crystal = sin 2 θ

[0052] Where θ is the angle between the vector along the straight line from the center of the secondary particle to the surface and the vector along the c-axis of the grain after obtaining a TEM image of the cross-section of the positive electrode active material precursor.

[0053] First, the DoA crystal represented by Equation 1 above will be described.

[0054] The DoA crystal, as represented by Equation 1 above, is intended to indicate the orientation of the c-axis direction vector of the grain and is a value analyzed using TEM-ASTAR. ASTAR is a crystal and orientation analysis instrument with superior spatial resolution compared to EBSD, and is a TEM-based orientation analysis instrument that can even analyze thin slices (approximately 100 nm or less) with a thickness that allows electrons to pass through. TEM-ASTAR is an instrument that forms a diffraction pattern (hereinafter referred to as DP) with a transmitted electron beam and analyzes the phase and orientation by matching the measured DP with the simulated DP, and has a spatial resolution of 4 nm.

[0055] θ is, for example, the angle between a vector along a straight line from the center of the secondary particle to the surface and a vector along the c-axis at a specific pixel in the TEM image. Here, the center of the secondary particle is the particle's centroid. θ can be obtained using the inner product formula from the components of the vector along the straight line from the center of the secondary particle to the surface and the vector along the c-axis at a specific pixel in the TEM image.

[0056] Furthermore, the c-axis direction vector of the grain is the actual c-axis direction vector, and is different from the short axis vector perpendicular to the long axis of the primary grain used when determining the shape orientation. Figure 1 A diagram illustrating the differences in structural and shape orientations based on the cross-sections of single-crystal primary grains with triaxial elliptical shapes. (See diagram.) Figure 1 As shown, when the primary particle, as a single crystal, has a triaxial elliptical shape, the structural orientation (DoA) of the crystal does not change according to the cross section, but the shape orientation (DoA) may change. The shape orientation (DoA) is the square of the angle between the vector in the straight line direction from the center of the secondary particle to the surface and the principal axis of the primary particle.

[0057] The DoA crystals described in this specification can be obtained, for example, by the following methods.

[0058] First, by performing crystal orientation analysis using TEM-ASTAR, the crystal orientation at each pixel in the two-dimensional image of the sample can be obtained as Euler angles. The definition of each Euler angle follows the Bunge convention. The equation for converting Euler angles into rotation matrices is as follows, and the following rotation matrix is ​​the matrix that transforms the crystal coordinate system into the sample coordinate system.

[0059]

[0060] Since the c-axis vector of the crystal in the crystal coordinate system is Therefore, the direction of the c-axis in the sample coordinate system is the same as the third column vector of the rotation matrix R. Thus, the direction of the c-axis in the sample coordinate system is calculated as... .

[0061] Since the transformed c-axis vector is the value for each pixel, it is necessary to cluster pixels into grain units in order to calculate the characteristics of the grain units. Clustering is performed through the following process.

[0062] The DBSCAN algorithm (a type of clustering algorithm) is used to perform a first clustering of the c-axis vector under the conditions of eps = 2 sin(0.5°) to 2 sin(1°) and minPts = 100 to 200, and the number n of representative c-axis direction types is obtained under these conditions. Using the n obtained here, a second clustering is performed using the KMeans algorithm (a type of clustering algorithm) (fixing the number of clusters to n). As a result of the first and second clustering (angle clustering), clustering for the entire c-axis direction is completed. Since clustering is only performed in the c-axis direction, crystals existing in independent locations on the image are also clustered into the same crystals. Therefore, additional clustering is required based on location. For the pixel locations within each c-axis direction cluster where the first and second clustering were performed, DBSCAN is executed under the conditions of DBSCAN parameters eps = 3 and minPts = 1 to 3 to obtain clustering by location again (location clustering). The clusters that have undergone the above process are assumed to be primary particles, and the c-axis direction within each primary particle is reset to the average direction of the c-axis directions of the pixels included in the primary particle. Thus, the segmentation of the primary particle and its c-axis direction are obtained. As a reference, clusters with a pixel area of ​​8 or less are removed for noise removal.

[0063] In the above process, the number of clusters (number of grains) for each pixel in the data and the orientation vector c of each grain were obtained.

[0064] The DoA crystal value is then calculated as follows. First, for each pixel, the square of the sine of the small angle between the direction vector *r* from the center of the secondary particle to the pixel and the direction vector *c* at the pixel location is calculated. The small angle ranges from 0° to 90°, and the sine and square of the sine range from 0 to 1. When calculating the direction vector at the center of the secondary particle, the coordinate system is set such that the left side is +x and the bottom side is +y, because in the coordinate system of the calculated c-axis vector, the left side is +x and the bottom side is +y. This may be defined differently by the device and software and should be set accordingly. It is important that the coordinate systems of the direction vector and the c-axis vector are the same. If the square of the sine calculated for each pixel is averaged, this value becomes the DoA crystal value.

[0065] Furthermore, the L value described in this specification can be obtained, for example, by performing clustering to determine a specific grain and its c-axis direction, and in this case, obtaining the length of the longest axis among the c-axis direction vectors passing through the grain within the two-dimensional projected grain (the c-axis length of the grain), defining the axis perpendicular to the projected c-axis as the a-axis, and obtaining the length of the longest axis among the a-axis direction vectors passing through the grain (the a-axis length of the grain), and then dividing the a-axis length of the grain by the c-axis length of the grain. Here, since the definitions of the a-axis and c-axis are independent of the major and minor axes of the ellipse, the L value can have any value.

[0066] The DoA crystal value calculated by Equation 1 above refers to the value representing the degree of inclination of the c-axis direction vector of the corresponding grain relative to the straight line passing through the centroid and surface of the positive electrode active material precursor. The closer the DoA crystal value is to 1, the more perpendicular the angle between the c-axis direction vector of the corresponding grain and the straight line.

[0067] According to the present invention, the average value of the DoA crystal value for structural orientation, as expressed in Equation 1 above, is 0.5 or greater. When the average DoA crystal value (which is a parameter that can indicate structural orientation) is 0.5 or greater, the optimal lithium migration path within the particle is ensured, and the structural stability during charging and discharging is improved, making it possible to realize a positive electrode active material with excellent lifetime and lifetime tolerance characteristics. Specifically, the average value of the DoA crystal value for structural orientation, as expressed in Equation 1 above, can be 0.500 or greater, 0.600 or greater, 0.700 or greater, 0.750 or greater, and can be 0.880 or less, 0.890 or less, 0.900 or less, 0.950 or less, or less than 1.00. More specifically, the average value of the DoA crystal value for structural orientation, as expressed in Equation 1 above, can be from 0.7 to 0.8.

[0068] On the other hand, when the average value of DoA crystal is less than 0.5, the lithium migration path cannot be guaranteed, resulting in poor lifetime and lifetime tolerance characteristics of the positive electrode active material made from it.

[0069] The structural orientation of the cathode active material precursor varies depending on the type / concentration / mixing ratio of raw materials, input rate, pH conditions, reaction temperature, stirring speed, reaction time, etc., used in the production of the cathode active material precursor. Therefore, by appropriately controlling these factors, cathode active material precursors with a structural orientation and an average DoA crystal value that satisfy the present invention can be produced.

[0070] According to the present invention, the average value of L for the positive electrode active material precursor according to the following Equation 2 can be 0.3 or greater:

[0071] [Equation 2]

[0072] L = (a-axis length of a crystal grain) / (c-axis length of a crystal grain)

[0073] wherein the a-axis length of the crystal grain is the length of the longest axis among vectors passing through the crystal grain in the a-axis direction, and the c-axis length of the crystal grain is the length of the longest axis among vectors passing through the crystal grain in the c-axis direction.

[0074] The above (a-axis length of crystal grain / c-axis length of crystal grain) is different from (major axis / minor axis) defined by particle shape, and even if a particle has an elongated shape, the value of (a-axis length of crystal grain / c-axis length of crystal grain) may still be low.

[0075] According to the present invention, when the average value of L according to the above Equation 2 is 0.3 or more, a cathode active material with improved orientation having optimal lithium migration paths and structural stability during charging and discharging can be achieved.

[0076] According to the present invention, the average value of L according to the above Equation 2 may specifically be 0.3 or more, 0.35 or more, 0.4 or more, or 0.45 or more, and be 2.5 or less, 3.0 or less, 3.5 or less, 4.0 or less, 4.5 or less, 5.0 or less, 5.5 or less, or 6.0 or less.

[0077] According to the present invention, the cathode active material precursor may comprise a composite transition metal hydroxide containing two or more transition metals, and for example, may comprise a composite transition metal hydroxide represented by the following Chemical Formula 1:

[0078] [Chemical Formula 1]

[0079] Ni a Co b Mn c M d (OH)2

[0080] wherein M is at least one element selected from the group consisting of: Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo,

[0081] 0.6≤a<1.0, 0<b<0.4, 0<c<0.4, and 0≤d≤0.2.

[0082] a represents a ratio of the number of moles of Ni to the number of moles of all transition metals, and may satisfy 0<a<1, preferably 0.3≤a<1, more preferably 0.6≤a<1, and even more preferably 0.8≤a<1.

[0083] b represents the ratio of the moles of Co to the moles of all transition metals, and 0<b<1, preferably 0<b<0.7, more preferably 0<b<0.4, and even more preferably 0<b<0.2.

[0084] c represents the ratio of the moles of Mn to the moles of all transition metals, and 0<c<1, preferably 0<c<0.7, more preferably 0<c<0.4, and even more preferably 0<c<0.2.

[0085] d represents the ratio of the moles of M to the moles of all transition metals, and 0≤d≤0.2, preferably 0≤d≤0.15, and even more preferably 0≤d≤0.10.

[0086] According to the present invention, the BET specific surface area of the positive electrode active material precursor may be 2.0 m 2 / g to 15.0 m 2 / g. Specifically, the BET specific surface area of the positive electrode active material precursor may be 2.0 m 2 / g or greater, 2.1 m 2 / g or greater, 2.2 m 2 / g or greater, 2.3 m 2 / g or greater, 2.4 m 2 / g or greater, 2.5 m 2 / g or greater, 2.6 m 2 / g or greater, 2.7 m 2 / g or greater, 2.8 m 2 / g or greater, 2.9 m 2 / g or greater, or 3.0 m 2 / g or greater, and may be 10.0 m 2 / g or less, 11.0 m 2 / g or less, 12.0 m 2 / g or less, 13.0 m 2 / g or less, 14.0 m 2 / g or less, or 15.0 m 2 / g or less. More specifically, the BET specific surface area of the positive electrode active material precursor may be 3.0 m 2 / g to 15.0 m 2 / g. When the BET specific surface area is within the above range, the reactivity with lithium during calcination is good, thereby increasing the efficiency in the calcination process (reduction of calcination temperature / time), and a positive electrode active material with improved orientation having optimal lithium migration paths and structural stability during charging and discharging can be achieved.

[0087] According to the present invention, the average particle size (D) of the positive electrode active material precursor is 50 The average particle size (D) of the positive electrode active material precursor can range from 2.0 μm to 20.0 μm. 50 The average particle size (D) is the average particle size of the secondary particles, and specifically, it can be 2.0 μm or larger, 3.0 μm or larger, or 4.0 μm or larger, and can be 10.5 μm or smaller, 11.0 μm or smaller, 12.0 μm or smaller, 13.0 μm or smaller, 14.0 μm or smaller, 15.0 μm or smaller, 16.0 μm or smaller, 17.0 μm or smaller, 18.0 μm or smaller, 19.0 μm or smaller, or 20.0 μm or smaller. 50 Within the above range, the ratio of the surface area of ​​the positive electrode active material where side reactions occur in the electrode to the internal size of the positive electrode active material where lithium ions move relatively slowly compared to the electrolyte is suitable, so that a battery with favorable lifespan and lifespan tolerance characteristics can be realized.

[0088] Positive electrode active material

[0089] This invention provides a positive electrode active material, which is a calcined product of a mixture of the above-mentioned positive electrode active material precursor and a lithium raw material. That is, the positive electrode active material can be manufactured by mixing the positive electrode active material precursor according to the invention with a lithium raw material, and then calcining the mixture. Furthermore, the positive electrode active material can be manufactured from the positive electrode active material precursor according to the invention, thereby achieving a positive electrode active material with improved orientation, exhibiting optimal lithium migration path and structural stability during charging and discharging.

[0090] The lithium raw materials can be, for example, lithium-containing carbonates (such as lithium carbonate), hydrates (such as lithium hydroxide hydrate (LiOH·H2O)), hydroxides (such as lithium hydroxide), nitrates (such as lithium nitrate (LiNO3), chlorides (such as lithium chloride (LiCl), etc.), etc., and can be one or a mixture of two or more of them.

[0091] Meanwhile, the mixing of the cathode active material precursor and the lithium raw material can be carried out through solid-state mixing, and the mixing ratio of the cathode active material precursor to the lithium raw material can be determined within a range that satisfies the atomic fraction of each component in the final manufactured cathode active material. For example, the cathode active material precursor and the lithium raw material can be mixed in an amount such that the molar ratio of the transition metal contained in the cathode active material precursor to Li is 1:0.9 to 1:1.2, preferably 1:0.98 to 1:1.1. When the cathode active material precursor and the lithium raw material are mixed within the above range, a cathode active material exhibiting excellent capacity characteristics can be manufactured.

[0092] Calcination can be carried out at 600°C to 1000°C, preferably 700°C to 900°C, and the calcination time can be 5 hours to 30 hours, preferably 10 hours to 20 hours, but is not limited thereto.

[0093] The average particle size (D) of the positive electrode active material 50 The thickness can range from 2.0 μm to 20.0 μm.

[0094] The positive electrode active material can have a composition represented by the following chemical formula 2:

[0095] [Chemical Formula 2]

[0096] Li x [Ni a2 Co b2 Mn c2 M d2 O2

[0097] in:

[0098] M is at least one element selected from the following: Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B, and Mo.

[0099] , , , ,as well as .

[0100] positive electrode

[0101] The present invention provides a positive electrode comprising the aforementioned positive electrode active material.

[0102] The positive electrode may include a positive current collector and a positive active material layer formed on the positive current collector, wherein the positive active material layer may contain a positive active material.

[0103] The positive electrode current collector can contain a highly conductive metal, and there are no particular limitations, as long as the positive electrode active material layer can easily adhere to it and does not react within the battery's voltage range. The positive electrode current collector can be, for example, stainless steel, aluminum, nickel, titanium, calcined carbon, or aluminum or stainless steel with a surface treated with carbon, nickel, titanium, silver, etc. Furthermore, the thickness of the positive electrode current collector is typically from 3 μm to 500 μm, and it can have fine irregularities formed on its surface to increase the adhesion of the positive electrode active material. For example, it can be used in various forms such as films, sheets, foils, meshes, porous bodies, foams, nonwoven fabrics, etc.

[0104] If desired, the positive electrode active material layer may optionally contain conductive materials and binders in addition to the positive electrode active material. In this case, based on the total weight of the positive electrode active material layer, the positive electrode active material may be included in an amount of 80% to 99% by weight, more specifically 85% to 98.5% by weight, and within this range, excellent capacity characteristics can be exhibited.

[0105] Conductive materials are used to impart conductivity to the electrodes and can be any material without particular limitation, as long as they are electronically conductive without causing chemical changes in the battery to be configured. Specific examples may include: graphite, such as natural or artificial graphite; carbon-based materials, such as carbon black, acetylene black, Ketjen black, channel black, furnace black, lamp black, thermal cracking black, and carbon fibers; powders or fibers of metals such as copper, nickel, aluminum, silver, etc.; conductive tubes, such as carbon nanotubes; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; or conductive polymers, such as polyphenylene derivatives, and mixtures of any one or more of these may be used. Based on the total weight of the positive electrode active material layer, the conductive material may be included in an amount from 0.1% to 15% by weight.

[0106] The binder is used to improve the bonding between positive electrode active material particles and the adhesion between the positive electrode active material and the current collector. Specific examples may include polyvinylidene fluoride (PVDF), polyvinylidene fluoride-hexafluoropropylene copolymer (PVDF-co-HFP), polyvinyl alcohol, polyacrylonitrile, polymethyl methacrylate, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber (SBR), fluororubber, polyacrylic acid, polymers in which hydrogen is replaced by Li, Na, or Ca, or various copolymers thereof, and mixtures of any one or more of them may be used. Based on the total weight of the positive electrode active material layer, the binder may be included in an amount from 0.1% to 15% by weight.

[0107] The positive electrode can be manufactured using conventional positive electrode manufacturing methods, the difference being the use of the aforementioned positive electrode active material. Specifically, the aforementioned positive electrode active material, along with (if needed) a binder, conductive material, and dispersant, can be dissolved or dispersed in a solvent to prepare a composition for forming a positive electrode active material layer. This composition can be applied to a positive electrode current collector, then dried and wound to manufacture the positive electrode. Alternatively, the positive electrode can be manufactured by casting the composition for forming the positive electrode active material layer onto a separate support, peeling off the support to obtain a film, and laminating the film onto the positive electrode current collector.

[0108] The solvent can be any solvent commonly used in the art, such as dimethyl sulfoxide (DMSO), isopropanol, N-methylpyrrolidone (NMP), dimethylformamide (DMF), acetone, water, etc., and mixtures of any one or more of these solvents can be used. The solvent can be used in an amount sufficient to dissolve or disperse the positive electrode active material, conductive material, binder, and dispersant, taking into account the applied thickness of the slurry and the manufacturing yield, and to allow the slurry to have a viscosity that can exhibit excellent thickness uniformity when applied to the subsequent positive electrode production.

[0109] Lithium secondary batteries

[0110] The present invention provides a lithium secondary battery comprising: a positive electrode; a negative electrode; and a separator and an electrolyte between the positive electrode and the negative electrode.

[0111] The lithium secondary battery may optionally also include a battery container for housing an electrode assembly formed by a positive electrode, a negative electrode and a separator, and a sealing member for sealing the battery container.

[0112] The negative electrode may include a negative electrode current collector and a layer of negative electrode active material disposed on the negative electrode current collector.

[0113] There are no particular restrictions on the negative electrode current collector, as long as it has high conductivity without causing chemical changes in the battery. It can be made of materials such as copper, stainless steel, aluminum, nickel, titanium, calcined carbon, or copper or stainless steel and aluminum-cadmium alloys that have undergone surface treatment with carbon, nickel, titanium, or silver. Furthermore, the thickness of the negative electrode current collector can typically range from 3 μm to 500 μm, and like the positive electrode current collector, it can have fine irregularities formed on its surface to increase the adhesion of the negative electrode active material. For example, it can be used in various forms such as films, sheets, foils, meshes, porous bodies, foams, and nonwoven fabrics.

[0114] In addition to the negative electrode active material, the negative electrode active material layer may optionally contain a binder and a conductive material.

[0115] As anode active materials, compounds capable of reversibly inserting and de-intercalating lithium can be used. Specific examples can include carbon-containing materials, such as artificial graphite, natural graphite, graphitized carbon fibers, and amorphous carbon; metal compounds that can alloy with lithium, such as Si, Al, Sn, Pb, Zn, Bi, In, Mg, Ga, Cd, Si alloys, Sn alloys, or Al alloys; and metal oxides capable of doping and de-doping lithium, such as SiO₂. β ( The materials used may include SnO2, vanadium oxide, and lithium vanadium oxide; or composite materials comprising metal compounds and carbon-containing materials, such as Si-C composites or Sn-C composites, and mixtures of any one or more of these may be used. Furthermore, lithium metal films may be used as the negative electrode active material. Additionally, low-crystallinity carbon, high-crystallinity carbon, etc., may be used as carbon materials. Representative examples of low-crystallinity carbon may include soft carbon and hard carbon, and representative examples of high-crystallinity carbon may include amorphous, flake-like, scaly, spherical, or fibrous natural or artificial graphite, primary graphite, pyrolytic carbon, carbon fibers based on mesophase pitch, mesophase carbon microspheres, mesophase pitch, and high-temperature calcined carbon such as coke derived from petroleum or coal tar pitch. Based on the total weight of the negative electrode active material layer, the negative electrode active material may be included in an amount of 80% to 99% by weight.

[0116] The binder for the negative electrode active material layer is a component that facilitates the bonding between the conductive material, the active material, and the current collector, and is typically added in an amount from 0.1% to 10% by weight, based on the total weight of the negative electrode active material layer. Examples of such binders include polyvinylidene fluoride (PVDF), polyvinyl alcohol, carboxymethyl cellulose (CMC), starch, hydroxypropyl cellulose, regenerated cellulose, polyvinylpyrrolidone, polytetrafluoroethylene, polyethylene, polypropylene, ethylene-propylene-diene polymer (EPDM), sulfonated EPDM, styrene-butadiene rubber, nitrile rubber, fluororubber, and various copolymers thereof.

[0117] The conductive material in the negative electrode active material layer is a component that further improves the conductivity of the negative electrode active material, and can be added in an amount of 10% by weight or less, preferably 5% by weight or less, based on the total weight of the negative electrode active material layer. There are no particular limitations on the conductive material, as long as it is conductive without causing chemical changes in the battery, and it can be, for example, graphite, such as natural or artificial graphite; carbon black, such as acetylene black, Ketjen black, channel black, furnace black, lamp black, and thermal cracking black; conductive fibers, such as carbon fibers and metal fibers; fluorinated carbon; metal powders, such as aluminum powder and nickel powder; conductive whiskers, such as zinc oxide and potassium titanate; conductive metal oxides, such as titanium oxide; and conductive materials, such as polyphenylene derivatives.

[0118] The negative electrode active material and optional binders and conductive materials can be dissolved or dispersed in a solvent to prepare a composition for forming a negative electrode active material layer, which can be applied to a negative electrode current collector and dried to produce a negative electrode. Alternatively, the negative electrode can be manufactured by casting the composition for forming the negative electrode active material layer onto a separate support, peeling the film off the support, and then laminating the film onto the negative electrode current collector.

[0119] The separator is used to separate the negative and positive electrodes and provide a channel for lithium-ion movement. Any separator can be used without particular limitation, as long as it is commonly used as a separator in lithium secondary batteries. In particular, separators with excellent electrolyte retention while exhibiting low resistance to electrolyte ion migration are preferred. Specifically, porous polymer membranes can be used, such as porous polymer membranes made from polyolefin-based polymers (e.g., ethylene homopolymers, propylene homopolymers, ethylene / butene copolymers, ethylene / hexene copolymers, and ethylene / methacrylate copolymers), or laminated structures having two or more layers. Alternatively, conventional porous nonwoven fabrics can be used, such as nonwoven fabrics made from high-melting-point glass fibers, polyethylene terephthalate fibers, etc. Furthermore, coated separators containing ceramic components or polymer materials can also be used to ensure heat resistance or mechanical strength, and can optionally be used in single-layer or multi-layer structures.

[0120] The electrolyte can be, but is not limited to, organic liquid electrolytes, inorganic liquid electrolytes, solid polymer electrolytes, gel polymer electrolytes, solid inorganic electrolytes, molten inorganic electrolytes, etc., which can be used to prepare lithium secondary batteries. As a specific example, the electrolyte can include organic solvents and lithium salts.

[0121] As an organic solvent, any solvent can be used without particular limitation, as long as it can serve as a medium through which ions participating in the electrochemical reaction of the battery can move. Specifically, the organic solvent can 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; an aromatic hydrocarbon-based solvent, such as benzene or fluorobenzene; a carbonate-based solvent, such as dimethyl carbonate (DMC), diethyl carbonate (DEC), ethyl methyl carbonate (EMC), ethylene carbonate (EC), or propylene carbonate (PC); an alcohol-based solvent, such as ethanol or isopropanol; a nitrile, such as R-CN (R being a straight-chain, branched, or cyclic hydrocarbon group having 2 to 20 carbon atoms, and may include double bonds, aromatic rings, or ether bonds); an amide, such as dimethylformamide; a dioxolane, such as 1,3-dioxolane; or sulfolane. Among these, carbonate-based solvents are preferred, and mixtures of cyclic carbonates (e.g., ethylene carbonate, propylene carbonate, etc.) with high ionic conductivity and high dielectric constants that can improve the charging / discharging performance of batteries and compounds based on low-viscosity linear carbonates (e.g., ethyl methyl carbonate, dimethyl carbonate, diethyl carbonate, etc.) are even more preferred.

[0122] Lithium salts can be any compound without particular limitation, as long as they can provide lithium ions used in lithium secondary batteries. Specifically, the anion of the lithium salt can be selected from at least one of the following: F -Cl - ,Br - I - NO3 - N(CN)2 - BF4 - CF3CF2SO3 - (CF3SO2)2N - (FSO2)2N - CF3CF2(CF3)2CO - (CF3SO2)2CH - (SF5)3C - (CF3SO2)3C - CF3(CF2)7SO3 - CF3CO2 - CH3CO2 - SCN - and (CF3CF2SO2)2N - The lithium salt can be LiPF6, LiClO4, LiAsF6, LiBF4, LiSbF6, LiAlO4, LiAlCl4, LiCF3SO3, LiC4F9SO3, LiN(C2F5SO3)2, LiN(C2F5SO2)2, LiN(CF3SO2)2, LiCl, LiI, LiB(C2O4)2, etc. The lithium salt is preferably used at a concentration in the range of 0.1 M to 2.0 M. When the concentration of the lithium salt is within this range, the electrolyte has suitable conductivity and viscosity, thus exhibiting excellent electrolyte performance, and lithium ions can move efficiently.

[0123] To improve battery life characteristics, suppress battery capacity reduction, and improve battery discharge capacity, in addition to the electrolyte components mentioned above, the electrolyte may also contain one or more additives, such as compounds based on alkyl halogenated carbonates (e.g., ethylene difluorocarbonate), pyridine, triethyl phosphite, triethanolamine, cyclic ethers, ethylenediamine, n-glycol dimethyl ether (n-glyme), hexaphosphoric triamine, nitrobenzene derivatives, sulfur, quinone imine dyes, and N-substituted compounds. Alzolidinediones, N,N-substituted imidazolidinyl ethers, ethylene glycol dialkyl ethers, ammonium salts, pyrroles, 2-methoxyethanol, or aluminum trichloride. In this case, the additive may be included in an amount from 0.1% to 5% by weight, based on the total weight of the electrolyte.

[0124] Because lithium secondary batteries containing the positive electrode active material according to the present invention have excellent capacity characteristics, initial efficiency, resistance characteristics and lifespan characteristics, they can be used in the field of portable devices, such as mobile phones, laptops, digital cameras and electric vehicles such as hybrid electric vehicles (HEVs) and electric vehicles (EVs).

[0125] The external shape of the lithium secondary battery of the present invention is not particularly limited, but it can be cylindrical, prismatic, pouch-shaped or coin-shaped using a can.

[0126] The lithium secondary battery according to the present invention can be used not only in battery cells as power sources for small devices, but also preferably as a unit battery in medium to large battery modules containing multiple battery cells.

[0127] Therefore, a battery module including a lithium secondary battery as a unit cell and a battery pack including the same are provided.

[0128] Battery modules or battery packs can be used as power sources for power tools; electric vehicles, including electric vehicles (EVs), hybrid electric vehicles and plug-in hybrid electric vehicles (PHEVs); or for power storage systems for any one or more medium and large-sized devices.

[0129] [Methods of Implementing the Invention]

[0130] Embodiments of the present invention will be described in detail below to enable those skilled in the art to readily implement the invention. However, the present invention can be implemented in many forms and is not limited to the embodiments described herein.

[0131] Example

[0132] Example 1

[0133] NiSO4, CoSO4, and MnSO4 were mixed in distilled water in amounts such that the molar ratio of nickel:cobalt:manganese was 65:15:20 to prepare a transition metal aqueous solution with a concentration of 2.4 M.

[0134] Deionized water was then added to a 20 L reactor, followed by nitrogen gas injection at 30 L / h to remove dissolved oxygen from the water and create a non-oxidizing atmosphere inside the reactor. Subsequently, a 25 wt% NaOH aqueous solution was introduced to maintain the pH inside the reactor between 11.40 and 12.50.

[0135] Subsequently, a transition metal aqueous solution was injected into the reactor at a rate of 1.5 L / h, a 25 wt% NaOH aqueous solution was injected to maintain the pH at 11.40 to 12.50, and a 9 wt% NH4OH aqueous solution was injected at a rate of 0.3 L / h. The reaction was carried out at a reaction temperature of 60 °C, a pH of 11.40 to 12.50, and a stirring speed of 250 rpm to 1000 rpm until the average particle size (D) was reached. 50 The particle size was reduced to 9.0 μm. Subsequently, it was washed with water, filtered, and dried to prepare a material with the composition of Ni. 0.65 Co 0.15 Mn 0.20 (OH)2 represents the composition of the positive electrode active material precursor.

[0136] Subsequently, the positive electrode active material precursor and Li2CO3 were mixed to make the molar ratio of (Ni+Co+Mn):Li 1:1.05, and then calcined at 850°C for 10 hours in air atmosphere to produce the positive electrode active material.

[0137] Example 2

[0138] NiSO4, CoSO4, and MnSO4 were mixed in distilled water in amounts such that the molar ratio of nickel:cobalt:manganese was 70:10:20 to prepare a 2.4 M aqueous solution of transition metals.

[0139] Deionized water was then added to a 20 L reactor, and nitrogen gas was injected into the reactor at a rate of 30 L / h to remove dissolved oxygen from the water and create a non-oxidizing atmosphere inside the reactor. Subsequently, a 25 wt% NaOH aqueous solution was introduced to maintain the pH inside the reactor between 11.10 and 12.45.

[0140] Subsequently, a transition metal aqueous solution was injected into the reactor at a rate of 1.5 L / h, a 25 wt% NaOH aqueous solution was injected to maintain the pH at 11.10 to 12.45, and a 9 wt% NH4OH aqueous solution was injected at a rate of 0.1 L / h. The reaction was carried out at a reaction temperature of 50 °C, a pH at 11.10 to 12.45, and a stirring speed at 250 rpm to 1000 rpm until the average particle size (D) was reached. 50 The particle size was reduced to 9.0 μm. Subsequently, it was washed with water, filtered, and dried to prepare a material with the composition of Ni. 0.7 Co 0.1 Mn 0.2 (OH)2 represents the composition of the positive electrode active material precursor.

[0141] Subsequently, the positive electrode active material precursor and LiOH were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.05, and then calcined at 820°C for 10 hours in an oxygen atmosphere to produce the positive electrode active material.

[0142] Example 3

[0143] NiSO4, CoSO4, and MnSO4 were mixed in distilled water in a molar ratio of nickel:cobalt:manganese of 88:5:7 to prepare a transition metal aqueous solution with a concentration of 2.4 M.

[0144] Deionized water was then added to a 20 L reactor, followed by nitrogen gas injection at 30 L / h to remove dissolved oxygen from the water and create a non-oxidizing atmosphere inside the reactor. Subsequently, a 25% by weight NaOH aqueous solution was introduced to maintain the pH inside the reactor between 10.55 and 12.10.

[0145] Subsequently, a transition metal aqueous solution was injected into the reactor at a rate of 1.5 L / h, a 25 wt% NaOH aqueous solution was injected to maintain the pH at 10.55 to 12.10, and a 9 wt% NH4OH aqueous solution was injected at a rate of 0.1 L / h. The reaction was carried out at a reaction temperature of 50 °C, a pH at 10.55 to 12.10, and a stirring speed at 250 rpm to 1000 rpm until the average particle size (D) was reached. 50 The particle size was reduced to 10.0 μm. Subsequently, it was washed with water, filtered, and dried to prepare a material with the composition of Ni. 0.88 Co 0.05 Mn 0.07 (OH)2 represents the composition of the positive electrode active material precursor.

[0146] Subsequently, the positive electrode active material precursor and LiOH were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.07, and then calcined at 770°C for 10 hours in an oxygen atmosphere to produce the positive electrode active material.

[0147] Example 4

[0148] NiSO4, CoSO4, and MnSO4 were mixed in distilled water in an amount such that the molar ratio of nickel:cobalt:manganese was 88.5:3.5:8 to prepare a transition metal aqueous solution with a concentration of 2.4 M.

[0149] Deionized water was then added to a 20 L reactor, followed by nitrogen gas injection at 30 L / h to remove dissolved oxygen from the water and create a non-oxidizing atmosphere inside the reactor. Subsequently, a 25 wt% NaOH aqueous solution was introduced to maintain the pH inside the reactor between 12.50 and 12.90.

[0150] Subsequently, a transition metal aqueous solution was injected into the reactor at a rate of 1.5 L / h, a 25 wt% NaOH aqueous solution was injected to maintain the pH at 12.50 to 12.90, and a 9 wt% NH4OH aqueous solution was injected at a rate of 0.3 L / h. The reaction was carried out at a reaction temperature of 50 °C, a pH of 12.50 to 12.90, and a stirring speed of 250 rpm to 1000 rpm until the average particle size (D) was reached. 50 The particle size was reduced to 4.2 μm. Subsequently, it was washed with water, filtered, and dried to prepare a material with the composition of Ni. 0.885 Co 0.035 Mn 0.08 (OH)2 represents the composition of the positive electrode active material precursor.

[0151] Subsequently, the positive electrode active material precursor and LiOH were mixed so that the molar ratio of (Ni+Co+Mn):Li was 1:1.07, and then calcined at 770°C for 10 hours in an oxygen atmosphere to produce the positive electrode active material.

[0152] Experimental Example

[0153] Experimental Example 1

[0154] The positive electrode active material precursors prepared in Examples 1 to 4 above were processed into thin sections using a focused ion beam (Thermo Fisher Scientific, Helios 5), and then TEM-ASTAR (NanoMEGAS, ASTAR) analysis was performed to obtain the average value of the DoA crystal values.

[0155] Figures 2 to 4 The images shown are, in order, TEM images of the positive electrode active material precursor according to Example 1 (…). Figure 2 c-axis direction pattern Figure 3 ), and an image showing the DoA crystal and the angle between the c-axis and the xy-plane ( Figure 4 ).

[0156] Figures 5 to 7 The images shown are, in order, TEM images of the positive electrode active material precursor according to Example 2 (…). Figure 5 c-axis direction pattern Figure 6 ), and an image showing the DoA crystal and the angle between the c-axis and the xy-plane ( Figure 7 ).

[0157] Figures 8 to 10 The images shown are, in order, TEM images of the positive electrode active material precursor according to Example 3 (…). Figure 8 c-axis direction pattern Figure 9), and an image showing the DoA crystal and the angle between the c-axis and the xy-plane ( Figure 10 ).

[0158] Figures 11 to 13 The images shown are, in order, TEM images of the positive electrode active material precursor according to Example 4 (…). Figure 11 c-axis direction pattern Figure 12 ), and an image showing the DoA crystal and the angle between the c-axis and the xy-plane ( Figure 13 ).

[0159] Figure 3 , Figure 6 , Figure 9 and Figure 12 The c-axis pattern visualizes the c-axis vector as an RGB image by converting "-1" to "0" and "1" to "255" for each x, y, and z component; and Figure 4 , Figure 7 , Figure 10 and Figure 13 This image illustrates a DoA crystal and the angle between the c-axis and the xy-plane, where the value of each pixel represents sin... 2 θ, the arrow represents the two-dimensional projection of the c-axis vector of the corresponding crystal, and the color of the arrow represents the angle between the c-axis and the xy plane (screen).

[0160] Furthermore, the (a-axis length of grains / c-axis length of grains) of each positive electrode active material precursor prepared in Examples 1 to 4 was obtained by XRD analysis. Specifically, XRD (Panalytica, Empyrean) was used to obtain data in the 2θ 10° to 90° region under the conditions of Cu target, voltage 45 kV and current 40 mA, and the FWHM (full width at half maximum) of the (001) peak in the 18° to 20° region and the (100) peak in the 32° to 34° region were obtained, and the FWHM (001) / FWHM (100) value was calculated to obtain (a-axis length of grains / c-axis length of grains) and its average value.

[0161] Furthermore, the BET specific surface area of ​​each positive electrode active material precursor prepared in Examples 1 to 4 was obtained by using the nitrogen adsorption amount at liquid nitrogen temperature (77K) with BELSORP mini-II of Japan BEL according to the BET method.

[0162] Finally, the average particle size (D) of each positive electrode active material precursor prepared in Examples 1 to 4 was obtained using a PSA (Microtrac, S3500). 50 ).

[0163] The results are shown in Table 1 below.

[0164] [Table 1]

[0165]

[0166] Experimental Example 2

[0167] The positive electrode active materials, carbon black conductive materials and PVdF binder prepared in Examples 1 to 4 were mixed in N-methylpyrrolidone solvent at a weight ratio of 96:2:2 to prepare a positive electrode slurry. The positive electrode slurry was then applied to one surface of an aluminum current collector, dried at 100°C and rolled to manufacture a positive electrode.

[0168] A porous polyethylene separator is placed between the positive electrode and the negative electrode (lithium metal) manufactured as described above to create an electrode assembly. This electrode assembly is then positioned within a housing, and an electrolyte is injected into the housing to create a lithium secondary battery. In this case, the electrolyte is prepared by dissolving 1.0 M lithium hexafluorophosphate (LiPF6) in an organic solvent composed of ethylene carbonate, ethyl methyl carbonate, and diethyl carbonate (volume ratio = 3:4:3).

[0169] Each lithium secondary battery manufactured as described above was charged at 45°C with a constant current of 1 C to 4.25 V and a cutoff value of 3 C, and then discharged with a constant current of 0.33 C to 3.0 V. This charging and discharging behavior was considered as one cycle, and this cycle was repeated 50 times. The capacity retention rate and resistance increase rate based on the cycle were then calculated and are shown in Table 2 below. The capacity retention rate is the percentage of the discharge capacity of the 50th cycle (50th cycle capacity) to the discharge capacity of the 1st cycle (initial capacity) ({(50th cycle capacity) / (initial capacity)}×100[%]), and the resistance increase rate is the percentage of the resistance of the 50th cycle (50th cycle resistance) to the resistance of the 1st cycle (initial resistance) ({(50th cycle resistance) / (initial resistance)}×100[%]).

[0170] [Table 2]

[0171]

[0172] Refer to Table 1 above and Figures 2 to 13 In the case of the positive electrode active material precursors of Examples 1 to 4, it can be determined that they take the form of secondary particles formed by aggregating multiple primary particles, and the average value of the DoA crystal value expressed by Equation 1 described herein is 0.5 or greater. Furthermore, in the case of the positive electrode active material precursors of Examples 1 to 4, it can be determined that the average value of the L value according to Equation 2 described herein is 0.3 or greater, and the BET specific surface area is within 2 m². 2 / g to 15 m 2Within the range of / g.

[0173] Referring to Table 2 above, it can be determined that batteries containing positive active materials manufactured from the positive active material precursors of Examples 1 to 4 have a high capacity retention rate of 95.0% or greater and a low resistance increase rate of 18.5% or less under high temperature conditions.

[0174] In summary, it can be seen that the cathode active material precursor of the present invention satisfies an average DoA crystal value of 0.5 or greater (which is a parameter that can indicate the structural orientation of the grains), thereby enabling the realization of a cathode active material with optimal lithium mobility and improved structural stability during charging and discharging.

Claims

1. A positive electrode active material precursor, comprising: a form of secondary particles formed by aggregating a plurality of primary particles, and an average degree of crystal orientation (DoA) value represented by the following Equation 1 of 0.5 or more, [Equation 1] wherein θ is the angle between a vector in a straight line direction from the center to the surface of the secondary particle and a vector in the c-axis direction of a crystal grain after obtaining a TEM image of a cross-section of the positive electrode active material precursor.

2. The positive electrode active material precursor according to claim 1, wherein the average degree of crystal orientation DoA value is 0.6 or more.

3. The positive electrode active material precursor according to claim 1, wherein the average degree of crystal orientation DoA value is 0.7 or more.

4. The positive electrode active material precursor according to claim 1, wherein an average L-value of the positive electrode active material precursor according to the following Equation 2 is 0.3 or more: [Equation 2] L = (a-axis length of the crystal grain) / (c-axis length of the crystal grain) wherein the a-axis length of the crystal grain is the length of the longest axis among vectors passing through the crystal grain in the a-axis direction, and the c-axis length of the crystal grain is the length of the longest axis among vectors passing through the crystal grain in the c-axis direction.

5. The positive electrode active material precursor according to claim 4, wherein the average L-value is 0.4 or more.

6. The positive electrode active material precursor according to claim 4, wherein the average L-value is 0.5 or more.

7. The positive electrode active material precursor according to claim 1, wherein the positive electrode active material precursor comprises a composite transition metal hydroxide represented by the following Chemical Formula 1: [Chemical Formula 1] Ni a Co b Mn c M d (OH)2 wherein M is at least one element selected from the group consisting of Al, W, Cu, Fe, V, Cr, Ti, Zr, Zn, Ta, Y, In, La, Sr, Ga, Sc, Gd, Sm, Ca, Ce, Nb, Mg, B and Mo, 0.6≤a<1.0, 0<b<0.4, 0<c<0.4, and 0≤d≤0.

2.

8. The positive electrode active material precursor of claim 1, wherein the BET specific surface area of the positive electrode active material precursor is 2.0 m 2 / g to 15.0 m 2 / g.

9. The positive electrode active material precursor according to claim 1, wherein the BET specific surface area of ​​the positive electrode active material precursor is 3.0 m². 2 / g to 15.0 m 2 / g.

10. The positive electrode active material precursor according to claim 1, wherein the average particle size (D) of the positive electrode active material precursor is... 50 The range is from 2.0 μm to 20.0 μm.

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