Positive electrode active material

Abstract

(a) A first component containing lithium transition metal oxide spinel particles; (b) A cathode active material containing a second oxide component selected from oxides of Sr, Y, Zr, Nb, La, and W, and mixtures thereof, wherein the cathode active material (i) Particles containing one or more single crystals of the first component, wherein the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is 3 μm or less, and the second oxide component is at least partially disposed on the surface of the particles; and / or (ii) Secondary particles containing aggregated single crystal particles of the first component, wherein the second oxide component is dispersed over the entire secondary particle on the surface of the single crystal particles at the interface between the single crystal particles, and a cathode active material is provided.

Description

Technical Field

[0001] The present invention relates to a positive electrode active material and a method for producing the same.

Background Art

[0002] The development of rechargeable battery materials with high energy density has become an important research topic due to their wide applications in electric vehicles, portable electronic devices, and grid-scale energy storage devices. The first commercialization of Li-ion batteries (LiBs) in the early 1990s offers many advantages over other commercial battery technologies. In particular, their relatively high energy and specific power make LIBs the best candidates for electric mobility applications.

[0003] The lithium positive electrode active material may be characterized by the formula Li x Ni y Mn 2-y O 4-δ (where 0.9 ≦ x ≦ 1.1, 0.4 ≦ y ≦ 0.5, and 0 ≦ δ ≦ 0.1). Such materials can be used, for example, in portable devices (US8,404,381B2); electric vehicles, energy storage systems, auxiliary power units (APUs), and uninterruptible power supply devices (UPSs). The lithium positive electrode active material is regarded as a promising alternative to current lithium secondary battery cathode materials such as LiCoO2 and LiMn2O4.

[0004] The lithium positive electrode active material can be produced from precursors obtained by a coprecipitation process. These precursors and products are spherical due to the coprecipitation process. Electrochimica Acta (2014), pp. 290-296 (Non-Patent Document 1) discloses a material produced from precursors obtained by a coprecipitation process followed by successive sintering (heat treatment) at 500 °C and then 800 °C. The resulting product is highly crystalline and has a spinel structure after the first heat treatment step (500 °C). The uniform shape of this product, 2.03 g / cm 3Tap density and a uniform secondary particle size of 5.6 μm are observed. Electrochimica Acta (2004) pp. 939-948 (Non-Patent Document 2) describes that a uniform distribution of spherical particles exhibits a higher tap density than irregular particles due to their higher fluidity and ease of packing. LiNi 0.5 Mn 1.5 It is assumed that the resulting hierarchical shape and large secondary particle size of O4 increase the tap density.

[0005] The lithium positive electrode active material can also be produced from a precursor obtained by mechanically mixing raw materials to form a uniform mixture, as disclosed in US8,404,381B2 (Patent Document 1) and US7,754,384B2 (Patent Document 2). This precursor is heated to 600 °C, annealed between 700 °C and 950 °C, and cooled in an oxygen-containing medium. It is disclosed that the heat treatment step at 600 °C is required to ensure that lithium is sufficiently incorporated into the mixed nickel and manganese oxide precursor. Also, it is disclosed that the annealing step is generally at a temperature above 800 °C to cause oxygen loss while forming the desired spinel shape. Furthermore, it is disclosed that subsequent cooling in an oxygen-containing medium allows for partial return of oxygen. US7,754,384B2 (Patent Document 2) does not describe anything regarding the tap density of the material. Also, it is disclosed that 1 to 5 mol% excess lithium is used to produce the precursor.

[0006] J. Electrochem. Soc. (1997) 144, pp. 205-213 (Non-Patent Document 3) also discloses the production of spinel LiNi 0.5 Mn 1.5 O4 from a precursor produced by mechanically mixing raw materials to obtain a uniform mixture. This precursor is heated three times in air at 750 °C and once at 800 °C. LiNi 0.5 Mn 1.5 O4 loses oxygen and disproportionates when heated above 650 °C, but LiNi 0.5 Mn 1.5The O4 stoichiometry is disclosed to be restored by slow cooling rates in an oxygen-containing atmosphere. The particle size and tap density are not disclosed. Also, it is disclosed that the production of spinel phase materials by mechanically mixing raw materials to obtain a uniform mixture is difficult, and that precursors prepared by the sol-gel method were preferred.

[0007] WO2017220162 (Patent Document 3) discloses an electrode material for a lithium-ion-based electrochemical cell, comprising primary particles of an Mn-containing spinel-type metal oxide selected from the group consisting of spinel-type lithium-nickel-manganese oxide, spinel-type lithium-manganese oxide, or mixtures thereof, wherein the Mn of the Mn-containing spinel-type metal oxide is partially replaced by a substitution element selected from the group consisting of Si, Hf, Zr, Fe, Al, V, and mixtures thereof, and the primary particles are aggregated to form secondary particles, and the secondary particles have the shape of microspheres.

[0008] US2018053940 (Patent Document 4) relates to a positive electrode active material particle and a secondary battery including the same, and a positive electrode active material particle including a core containing a first lithium transition metal oxide; and a shell surrounding the core, wherein the shell has a form in which metal oxide particles are embedded in a second lithium transition metal oxide and a part of the metal oxide particles exists in a state of being exposed on the surface of the shell. It is disclosed that the positive electrode active material particles prevent side reactions from occurring by exposing a part of a metal oxide with low reactivity on the surface of the active material, thereby improving safety and lifespan. It is taught that stability can be maintained even at high temperatures and in situations where the battery fails because the electrical conductivity of the active material is low.

Prior Art Documents

Patent Documents

[0009]

Patent Document 1

[0010] [Non-Patent Document 1] Electrochimica Acta(2014),pp.290 - 296 [Non-Patent Document 2] Electrochimica Acta (2004) pp.939 - 948 [Non-Patent Document 3] J.Electrochem.Soc.(1997)144,pp.205 - 213 [Non-Patent Document 4] Jillavenkatesa A,Dapkunas S J,Lin-Sien Lum:Particle Size Characterization,NIST(National Institute of Standards and Technology)Special Publication 960 - 1,2001 [Non-Patent Document 5] Adv.Mater.(2012)24,pp 2109 - 2116 [Non-Patent Document 6] Journal of Power Sources (2013)238,245 - 250 [Summary of the Invention] [Problems to be Solved by the Invention]

[0011] Therefore, it would be desirable to provide a positive electrode active material having improved cycle stability at room temperature and elevated temperatures. [Means for Solving the Problems]

[0012] In one aspect, (a) a first component comprising lithium transition metal oxide spinel particles selected from oxides of formula Li x Ni y Mn 3-x-y O4 (where 0.98 < x < 1.00 and 0.41 < y < 0.50); (b) a second oxide component selected from oxides of Sr, Y, Zr, Nb, La and W and mixtures thereof, in an amount of from 0.01 to 3 atomic % based on the total number of atoms in the cathode active material; A cathode active material comprising: (i) particles comprising one or more single crystals of the first component (a), wherein the arithmetic mean value of the minimum Feret diameter of the particles measured using an electron scanning microscope is 3 μm or less, and the second oxide component (b) is disposed at least partially on the surface of these particles; and / or (ii) secondary particles comprising aggregated single crystal particles of the first component (a), wherein the second oxide component (b) is dispersed over the surface of the single crystal particles at the interface between the single crystal particles throughout the secondary particles, and the secondary particles have an average particle diameter (D50) of less than 20 μm; is provided.

[0013] In a second aspect, (a) a first component comprising lithium transition metal oxide spinel particles selected from oxides of formula Li x Ni y Mn 3-x-y O4 (where 0.98 < x < 1.00 and 0.41 < y < 0.50); (b) a second oxide component selected from oxides of Sr, Y, Zr, Nb, La and W and mixtures thereof; A cathode active material comprising: The cathode active material is particles formed from one or more single crystals of the first component, wherein the second oxide component is disposed on the surface of these particles; A method for producing the cathode active material is provided.

[0014] This method comprises the following steps: (i) providing one or more lithium precursor compounds and one or more transition metal precursor compounds; (ii) contacting and grinding the precursor compounds to form a ground mixture; (iii) calcining the ground mixture at a temperature of at least 800 °C to provide a calcined mixture and (A) before the calcination step (iii), combining the second oxide, or second oxide precursor, with the one or more lithium precursor compounds and the one or more transition metal precursor compounds; or (B) after the calcination step (iii), combining the calcined mixture with the second oxide.

[0015] In another aspect, (a) a first component comprising lithium transition metal oxide spinel particles selected from oxides of the formula Li x Ni y Mn 3-x-y O4 where 0.98 < x < 1.00 and 0.41 < y < 0.50; (b) a second oxide component selected from oxides of Sr, Y, Zr, Nb, La and W, and mixtures thereof; a positive electrode active material comprising the positive electrode active material being secondary particles formed from aggregated single crystal particles of the first component, wherein the second oxide component is dispersed over the surface of the single crystal particles at the interface between the single crystal particles throughout the secondary particles, and a method for manufacturing the positive electrode active material is provided.

[0016] This method comprises the following steps: (i) providing one or more transition metal compounds, (ii) contacting the transition metal compounds with one or more compounds containing the metal of the second oxide component, or with the second oxide component, (iii) precipitating a transition metal and the metal of the second oxide component to form a precipitate, and washing the precipitate to form a first precursor mixture; (iv) contacting the first precursor mixture with one or more lithium precursor compounds to form a second precursor mixture, and (v) calcining the second precursor mixture. It includes.

[0017] [Detailed Description of the Invention] As described herein, in one aspect, (a) a first component comprising lithium transition metal oxide spinel particles selected from oxides of the formula Li x Ni y Mn 3-x-y O4 (where 0.98 <x <1.00 and 0.41 <y <0.50); (b) a second oxide component in an amount of from 0.01 to 3 atomic percent, based on the total number of atoms in the positive electrode active material, selected from oxides of Sr, Y, Zr, Nb, La and W, and mixtures thereof; A positive electrode active material comprising, wherein the positive electrode active material is (i) particles comprising one or more single crystals of the first component (a), wherein the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is 3 μm or less, and the second oxide component (b) is at least partially disposed on the surface of these particles; and / or (ii) secondary particles comprising aggregated single crystal particles of the first component (a), wherein the second oxide component (b) is dispersed over the entire secondary particle on the surface of the single crystal particles at the interface between the single crystal particles, and the secondary particles have an average particle size (D50) of less than 20 μm; The positive electrode active material as described above is provided.

[0018] In the positive electrode active material of the present invention, at least two oxide components are provided. The first oxide component is a lithium transition metal oxide in the form of particles. The second oxide component is yet another material selected from oxides of Sr, Y, Zr, Nb, La, and W, for example, ZrO2. The first and second oxides are configured such that the second oxide is always disposed near most of the lithium transition metal oxide. This is achieved by providing particles in one of two possible configurations. In the first configuration, the particles are formed from one or more single crystals of the first component, and the second oxide component is disposed at least partially on the surface of the particles. These particles are formed to be relatively small, particularly such that the arithmetic mean of the minimum Feret diameter of these particles measured using a scanning electron microscope is 3 μm or less.

[0019] As will be understood by those skilled in the art, the Feret diameter is the distance between two parallel lines placed on opposite sides of each other as tangents on the contour of the particle. The Feret system is also referred to as the caliper diameter, because this corresponds to placing calipers on an object and measuring its size along a specific method. The minimum Feret is the minimum distance between such two tangents or the minimum distance measurable by calipers. This means that the minimum Feret diameter corresponds to the minimum sieve size through which a specific particle can pass when oriented in the appropriate direction. For example, in the case of rectangular particles, the minimum Feret diameter corresponds to the shortest side, and in the case of a circle, the minimum Feret diameter corresponds to the diameter of the circle.

[0020] In the second configuration, the secondary particles are formed from aggregated single crystal particles of the first component. In these aggregated particles, the second oxide component is not only disposed on the surface of the secondary particles, but the second oxide component is dispersed throughout the secondary particles on the surface of the single crystal particles at the interface between the single crystal particles.

[0021] The inventors have found that by providing these specific particle configurations in which the second oxide is always arranged near most of the lithium transition metal oxides, a cathode active material having improved cycle stability at room temperature and / or elevated temperatures can be provided.

[0022] For ease of reference, these and further aspects of the invention are described under appropriate section headings. However, the teachings in each section are not necessarily limited to each specific section.

[0023] Cathode active material In one aspect, the cathode active material includes particles formed from one or more single crystals of a first component, wherein the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is 3 μm or less, and the second oxide component is at least partially disposed on the surfaces of these particles.

[0024] The Feret diameter of particles is well understood by those skilled in the art. The Feret diameter is used in the analysis of particle size and its distribution and has been widespread in scientific literature since 1970. The Feret diameter is a measure of the size of an object, which is defined as the distance between two parallel planes that perpendicularly limit the object in that direction. Therefore, it is also referred to as the caliper diameter and refers to the measurement of the size of an object using calipers.

[0025] The size of single crystal particles or the size of aggregates of single crystal particles for determining the Feret diameter can be evaluated by a scanning electron microscope (SEM). To prepare a material for such measurement, the sample is embedded in epoxy and polished to create a flat surface in order to obtain an image of the cross-section of individual particles containing the sample. Then, the image thus obtained is analyzed to measure the size and shape of the particles. The minimum Feret diameter is the shortest distance between two such tangents and can also be regarded as the minimum sieve size through which a specific particle can pass. For example, in the case of rectangular particles, the minimum Feret diameter corresponds to the shortest side, and in the case of a circle, the minimum Feret diameter corresponds to the diameter of the circle.

[0026] The Feret diameter of the particles can be determined according to the following method. A sample for a scanning electron microscope (SEM) is prepared by embedding the material in epoxy and polishing to create a flat surface. The SEM images are obtained with a Zeiss GeminiSEM500 equipped with a field emission electron gun (FEG) using an acceleration voltage of 10 kV and an energy selective backscatter (ESB) detector of the backscattered electron detector type. The pixel size is 0.01 μm / pixel. A total of 25 images are obtained and stitched into a high-resolution image of 4930 pixels × 3697 pixels corresponding to an image area of 48 μm × 36 μm. The images are analyzed according to the following procedure and a total of 663 particles are detected and analyzed. The images are analyzed using software called ImageJ (https: / / imagej.nih.gov). The procedure is as follows: · Threshold setting and segmentation using "Otsu's algorithm". · Apply the binary process "Fill holes". · Apply the binary process "Erode" 8 times. · Apply the binary process "Dilate" 6 times. · Use "Analyze particles" without size limit.

[0027] Fill holes is used to fill holes that may exist within the particles. The subsequent erosion and dilation steps are then used to remove any possible noise and ensure that nearby particles are separated.

[0028] In one aspect, the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is 2.5 μm or less, for example 2 μm or less, for example 1.8 μm or less, for example 1.6 μm or less, for example 1.4 μm or less, for example 1.2 μm or less, for example 1 μm or less, for example 0.8 μm or less.

[0029] In one aspect, the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is at least 0.1 μm, for example at least 0.2 μm, for example at least 0.3 μm, for example at least 0.4 μm, for example at least 0.5 μm, for example at least 0.6 μm, for example at least 0.7 μm.

[0030] In one aspect, the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is from 0.1 to 2.5 μm, for example from 0.1 to 2 μm, for example from 0.1 to 1.8 μm, for example from 0.1 to 1.6 μm, for example from 0.1 to 1.4 μm, for example from 0.1 to 1.2 μm, for example from 0.1 to 1 μm, for example from 0.1 to 0.8 μm.

[0031] The size of irregularly shaped particles can also be quantified based on the diameter of a circle with the same projected area. Therefore, for a particle with a projected area A, a circle with the same area has a diameter of d = 2 * √(A / (2 * π)). In one aspect, the positive electrode active material includes particles formed from one or more single crystals of a first component, where the average equivalent circle diameter of the particles measured using a scanning electron microscope is 3 μm or less. In one aspect, the average equivalent circle diameter of the particles measured using a scanning electron microscope is 2.5 μm or less, for example 2 μm or less, for example 1.8 μm or less, for example 1.6 μm or less, for example 1.4 μm or less, for example 1.2 μm or less, for example 1 μm or less, for example 0.9 μm or less.

[0032] In one aspect, the average equivalent circle diameter of the particles measured using a scanning electron microscope is at least 0.1 μm, for example at least 0.2 μm, for example at least 0.3 μm, for example at least 0.4 μm, for example at least 0.5 μm, for example at least 0.6 μm, for example at least 0.7 μm.

[0033] In one aspect, the average equivalent circle diameter of the particles measured using a scanning electron microscope is from 0.1 to 2.5 μm, for example from 0.1 to 2 μm, for example from 0.1 to 1.8 μm, for example from 0.1 to 1.6 μm, for example from 0.1 to 1.4 μm, for example from 0.1 to 1.2 μm, for example from 0.1 to 1 μm, for example from 0.1 to 0.9 μm.

[0034] In one aspect, the positive electrode active material includes secondary particles formed from aggregated single crystal particles of a first component, where the second oxide component is dispersed throughout the secondary particles on the surface of the single crystal particles at the interface between the single crystal particles. As will be understood by those skilled in the art, by dispersing the second oxide component not only on the surface of the secondary particles but also throughout the secondary particles, the second oxide component is present in proximity to the crystal of the lithium transition metal oxide. This provides a positive electrode active material having enhanced positive effects of the second oxide component and improved cycle stability at room temperature and elevated temperatures during use.

[0035] The secondary particles may be of any suitable size. In one aspect, the one or more secondary particles have an average particle size (D50) of less than 50 μm, for example less than 45 μm, for example less than 40 μm, for example less than 35 μm, for example less than 30 μm, for example less than 25 μm, for example less than 20 μm, for example less than 15 μm, for example less than 10 μm.

[0036] In one aspect, the one or more secondary particles have an average particle size (D50) of at least 1 μm, for example at least 2 μm, for example at least 3 μm, for example at least 4 μm, for example at least 5 μm, for example at least 10 μm.

[0037] In one aspect, the one or more secondary particles have an average particle size (D50) from 4 to 50 μm, for example from 4 to 45 μm, for example from 4 to 40 μm, for example from 4 to 35 μm, for example from 4 to 30 μm, for example from 4 to 25 μm, for example from 4 to 20 μm, for example from 4 to 15 μm, for example from 4 to 10 μm.

[0038] One way to quantify the particle size is to plot the entire particle size distribution, that is, to plot the volume fraction of particles of a specific size as a function of the particle size. In such a distribution, D10 is defined as the particle size at which 10% of the total number of particles is less than the value of D10, D50 is defined as the particle size at which 50% of the total number of particles is less than the value of D50 (i.e., the median), and D90 is defined as the particle size at which 90% of the total number of particles is less than the value of D90. Methods commonly used to determine the particle size distribution include laser diffraction measurement and scanning electron microscope measurement combined with image analysis. The D50 of the particle size distribution value is defined and measured as described in Jillavenkatesa A, Dapkunas SJ, Lin-Sien Lum: Particle Size Characterization, NIST (National Institute of Standards and Technology) Special Publication 960-1, 2001 (Non-Patent Document 4).

[0039] As described herein, from one perspective, the positive electrode active material is particles formed from one or more single crystals of a first component, where the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is 3 μm or less, and the second oxide component is at least partially disposed on the surface of the particles. The secondary particles formed from the aggregated single crystal particles of the first component may or may not be formed from particles having these specific properties. In other words, the secondary particles formed from the aggregated single crystal particles of the first component may or may not be formed from one or more single crystals of the first component, where the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is 3 μm or less, and the second oxide component is at least partially disposed on the surface of the particles.

[0040] The secondary particles are formed from aggregated single-crystalline particles of a first component. As described herein, the first component includes lithium transition metal oxide particles. In one aspect, the single-crystalline particles that aggregate to form the secondary particles may be particles of different lithium transition metal oxides. In one aspect, the single-crystalline particles that aggregate to form the secondary particles are each single-crystalline particles of the same lithium transition metal oxide. In other words, the first component may be the same lithium transition metal oxide in each single-crystalline particle.

[0041] The present invention provides a positive electrode active material in which a substantial proportion of the surface of each single crystal is not in contact with other crystal surfaces. Therefore, the positive electrode active material provides single crystals in which a substantial proportion of the crystal surface is a free surface. As will be understood by those skilled in the art, when producing a crystalline lithium transition metal oxide, single crystals of the lithium transition metal oxide grow during production, and these single crystals can contact other single crystals to form boundaries between these crystals. The boundary between each crystal and other crystals is no longer the outer surface of the crystal and has low availability. By providing small particles having an arithmetic mean value of the minimum Feret diameter of the particles of 3 μm or less as measured using a scanning electron microscope, or by providing secondary particles formed from aggregated single-crystalline particles, the availability of crystals having a limited number of boundaries with other crystals is maintained. In one aspect, the positive electrode active material is one or more particles formed from one or more single crystals of a first component, where at least 20% of the surface of these single crystals is a free surface. As will be understood by those skilled in the art, the term "free surface" means a surface that is not bonded to other crystals. In one aspect, the positive electrode active material is one or more particles formed from one or more single crystals of a first component, where at least 30% of the surface of these single crystals is a free surface, for example at least 40% of the surface of these single crystals is a free surface, for example at least 50% of the surface of these single crystals is a free surface, for example at least 60% of the surface of these single crystals is a free surface, for example at least 70% of the surface of these single crystals is a free surface, for example at least 80% of the surface of these single crystals is a free surface.

[0042] In one aspect, the positive electrode active material has a tap density of at least 1.5 g / cm 3 . From one perspective, the tap density of the positive electrode active material is at least 1.6 g / cm 3 ; for example, at least 1.7 g / cm 3 , for example, at least 1.8 g / cm 3 .

[0043] In one aspect, when the positive electrode active material is formed from secondary particles formed from aggregated single crystal particles of the first component, it has a tap density of at least 2.0 g / cm 3 . From one perspective, the tap density of the positive electrode active material is at least 2.1 g / cm 3 ; for example, at least 2.2 g / cm 3 , for example, at least 2.3 g / cm 3 , particularly at least 2.4 g / cm 3 .

[0044] In one aspect, when the positive electrode active material is formed from particles formed from one or more single crystals of the first component, it has a tap density of at least 1.5 g / cm 3 . From one perspective, the tap density of the positive electrode active material is at least 1.6 g / cm 3 ; for example, at least 1.7 g / cm 3 , for example, at least 1.8 g / cm 3 , particularly at least 1.9 g / cm 3 .

[0045] "Tap density" is a term used to describe the bulk density of a powder (or granular solid) after consolidation / compression, usually defined in terms of the number of times a powder container is "tapped" from a predetermined height. The method of "tapping" is best described as "lifting and dropping". In this context, tapping should not be confused with tamping, side-ways hitting, or vibration. Since the measurement method can affect the tap density value, the same method should be used when comparing the tap densities of different materials. The tap density of the present invention is measured by weighing a graduated cylinder with an inner diameter of 10 mm before and after adding about 5 g of powder, recording the mass of the added material, tapping the cylinder on a table for a while, and then reading the volume of the tapped material. Typically, tapping should continue until no further change in volume occurs upon further tapping. By way of example only, tapping can be performed about 120 to 180 times per minute.

[0046] Lithium transition metal oxide As will be understood by those skilled in the art, the lithium transition metal oxide can be any suitable lithium transition metal oxide. In one aspect, the lithium transition metal oxide is a lithium nickel manganese oxide spinel.

[0047] "Spinel" means a crystal lattice in which oxygen is arranged in a face-centered cubic lattice that may be slightly distorted and cations occupy the octahedral or tetrahedral interstitial positions in the lattice. Oxygen and octahedrally coordinated cations form a framework structure having a three-dimensional channel system that occupies tetrahedrally coordinated cations. The ratio between tetrahedrally coordinated cations and octahedrally coordinated cations is approximately 1:2, and the cation:oxygen ratio is approximately 3:4 in the spinel-type structure. The cations at the octahedral positions can consist of a single element or a mixture of different elements. A mixture of different types of octahedrally coordinated cations, by itself, forms a three-dimensional periodic lattice, in which case the spinel is referred to as an ordered spinel. When the cations are distributed more randomly, the spinel is referred to as a disordered spinel. Examples of ordered and disordered spinels described in the P4332 and Fd-3m space groups, respectively, are described in Adv. Mater. (2012) 24, pp 2109-2116 (Non-Patent Document 5).

[0048] The phase composition of the lithium cathode active material can be determined based on the X-ray diffraction pattern obtained using a Philips PW1800 instrument system in a θ-2θ geometric arrangement operating in Bragg-Brentano mode using CuKα radiation (λ = 1.541 Å). The observed data needs to be corrected for experimental parameters that contribute to the shift in the observed data. This is achieved using the full-profile fundamental parameter approach implemented in the TOPAS software from Bruker. The phase composition determined from the Rietveld analysis is indicated in units of weight % with a typical uncertainty of 1-2 percentage points, and represents the relative composition of all the crystal phases. Therefore, any amorphous phase is not included in the phase composition.

[0049] In one aspect, the lithium transition metal oxide is selected from oxides of the formula Li x Ni y Mn 3-x-y O4 (0.98 < x < 1.00 and 0.41 < y < 0.50).

[0050] One aspect of the method of the present invention is at least 95% by weight of a spinel phase Li x Ni y Mn 3-x-y O4 (0.9 ≦ x ≦ 1.1, and 0.4 ≦ y ≦ 0.5).

[0051] It should be noted that the lithium positive electrode active material may also contain a small amount of elements other than Li, Ni, Mn, and O. Such elements can be, for example, one or more of B, N, F, Mg, Al, Si, P, S, Ca, Ti, Cr, Fe, Co, Cu, Zn, Zr, Sn, W. Such a small amount of elements may be derived from impurities in the raw materials for producing the lithium positive electrode active material, or may be added as a dopant for the purpose of improving some characteristics of the lithium positive electrode active material.

[0052] Second oxide As described herein, the second oxide component is selected from oxides of Sr, Y, Zr, Nb, La, and W, and mixtures thereof. From one perspective, the second oxide component is at least an oxide of Sr. From one perspective, the second oxide component is at least an oxide of Y. From one perspective, the second oxide component is at least an oxide of Zr. From one perspective, the second oxide component is at least an oxide of Nb. From one perspective, the second oxide component is at least an oxide of La. From one perspective, the second oxide component is at least an oxide of W.

[0053] It has been found that an oxide of Zr (ZrO2) is particularly preferred. From one perspective, Zr is at least 90 atomic% based on the metal of the second oxide component. From one perspective, Zr is at least 95 atomic% based on the metal of the second oxide component. From one perspective, Zr is at least 99 atomic% based on the metal of the second oxide component. From one perspective, the second oxide component is an oxide of Zr.

[0054] When the second oxide component is an oxide of Zr or when the second oxide component contains an oxide of Zr, the positive electrode active material has the formula zLix Ni y Mn 3-x-y It can be represented by O4·(1-z)ZrO2 (where 0.98 < x < 1.00 and 0.41 < y < 0.50, and 0.96 < z < 1).

[0055] In one aspect, the second oxide component is present in an amount that provides Sr, Y, Zr, Nb, La, and W in a total amount of less than 7 atomic %, for example less than 6 atomic %, for example less than 5 atomic %, for example less than 4 atomic %, for example less than 3 atomic %, for example less than 2 atomic %, for example less than 1 atomic %, for example less than 0.8 atomic %, for example less than 0.6 atomic %, for example less than 0.4 atomic %, based on the total number of atoms in the positive electrode active material.

[0056] In one aspect, the second oxide component is present in an amount that provides Sr, Y, Zr, Nb, La, and W in a total amount of more than 0.01 atomic %, for example more than 0.02 atomic %, for example more than 0.05 atomic %, for example more than 0.1 atomic %, for example more than 0.2 atomic %, for example more than 0.5 atomic %, for example more than 1 atomic %, based on the total number of atoms in the positive electrode active material.

[0057] In one aspect, the second oxide component is present in an amount that provides Sr, Y, Zr, Nb, La, and W in a total amount from 0.01 to 7 atomic %, for example from 0.01 to 6 atomic %, for example from 0.01 to 5 atomic %, for example from 0.01 to 4 atomic %, for example from 0.01 to 3 atomic %, for example from 0.01 to 2 atomic %, for example from 0.01 to 1 atomic %, for example from 0.01 to 0.8 atomic %, for example from 0.01 to 0.6 atomic %, for example from 0.01 to 0.4 atomic %, based on the total number of atoms in the positive electrode active material.

[0058] In one aspect, the second oxide component is present in an amount of Sr, Y, Zr, Nb, La, and W in a total amount of from 0.05 to 7 atomic %, for example, in a total amount of from 0.05 to 6 atomic %, for example, in a total amount of from 0.05 to 5 atomic %, for example, in a total amount of from 0.05 to 4 atomic %, for example, in a total amount of from 0.05 to 3 atomic %, for example, in a total amount of from 0.05 to 2 atomic %, for example, in a total amount of from 0.05 to 1 atomic %, for example, in a total amount of from 0.05 to 0.8 atomic %, for example, in a total amount of from 0.05 to 0.6 atomic %, for example, in a total amount of from 0.05 to 0.4 atomic %, based on the total number of atoms of the positive electrode active material.

[0059] The second oxide component is provided in combination with a first component including lithium transition metal oxide particles. The second oxide component may be mixed with the lithium transition metal oxide. It is desirable that the second oxide component be in intimate contact with the first component including the lithium transition metal oxide. In one aspect, the second oxide component is bonded to the surface of particles formed from one or more single crystals or to the surface of single crystal particles. The term "bonded" is understood to mean that the second oxide component is fixed to the first component including the lithium transition metal oxide by, for example, significant intergrowth between the second oxide component and the first component including the lithium transition metal oxide.

[0060] As described herein, the second oxide component is disposed at least partially on the surface of particles formed from one or more single crystals of the first component. Although it is desirable to provide the second oxide component on the surface of the first component crystals, a portion of the second oxide component may be incorporated between the boundaries of the first component crystals. In one aspect, at least 50%, for example, at least 60%, for example, at least 70%, for example, at least 80%, for example, at least 90%, for example, at least 95%, for example, at least 99%, for example, at least 99.9% of the second oxide component is disposed on the surface of particles formed from one or more single crystals of the first component.

[0061] Method As will be appreciated from this specification, two different processes are provided.

[0062] The first process is for manufacturing particles formed from one or more single crystals of a first component, where a second oxide component is disposed, at least in part, on the surface of said particles. In this regard, (a) a first component comprising lithium transition metal oxide spinel particles selected from oxides of the formula Li x Ni y Mn 3-x-y O4 (where 0.98 < x < 1.00 and 0.41 < y < 0.50); (b) a second oxide component selected from oxides of Sr, Y, Zr, Nb, La, and W, and mixtures thereof; A method for manufacturing a positive electrode active material comprising: There is provided a method in which the positive electrode active material is particles formed from one or more single crystals of a first component, and the second oxide component is disposed on the surface of these particles.

[0063] This method comprises the following steps: (i) providing one or more lithium precursor compounds and one or more transition metal precursor compounds; (ii) contacting and grinding said precursor compounds to form a ground mixture; (iii) calcining said ground mixture to provide a calcined mixture; comprising (A) combining, prior to the calcination step (iii), the second oxide, or a second oxide precursor, with said one or more lithium precursor compounds and said one or more transition metal compounds; or (B) combining the calcined mixture with the second oxide after the calcination step (iii).

[0064] In this regard, the positive electrode active material may be particles formed from one or more single crystals of a first component, having an arithmetic mean value of the minimum Feret diameter measured using a scanning electron microscope of 3 μm or less, and wherein the second oxide component is disposed, at least in part, on the surface of these particles; or The lithium precursor compound of the first process may be selected from Li2CO3, LiOH, LiNO3, and mixtures thereof.

[0065] The transition metal precursor compound of the first process may be selected from oxides of Mn and Ni, carbonates of Mn and Ni, and hydroxides of Mn and Ni. In one aspect, the transition metal precursor compound of the first process is MnO2, Mn3O4, MnCO3, NiCO3, basic Ni-carbonate, such as Ni(CO3) x (OH) y ·zH2O (2x + y = 2), and mixtures thereof.

[0066] The second oxide precursor of the first process may be selected from oxides, carbonates, and hydroxides of Sr, Y, Zr, Nb, La, and W, and mixtures thereof. In one aspect, the second oxide precursor of the first process is ZrO2, Zr(CO3) x (OH) y (2x + y = 4) and mixtures thereof.

[0067] In one aspect, the pulverized mixture is calcined at a temperature of at least 800 °C. In an embodiment of the process, the pulverized mixture is calcined at a temperature from 300 to 1200 °C, such as from 400 to 1100 °C, such as from 500 to 1100 °C, such as from 500 to 1000 °C, such as from 600 to 1000 °C, such as from 700 to 950 °C.

[0068] The pulverized mixture can be calcined for any suitable time. In one embodiment, the pulverized mixture is calcined for at least 10 minutes, such as at least 30 minutes, such as at least 1 hour, such as at least 2 hours, such as at least 3 hours. In one aspect, the pulverized mixture is calcined for a period from 10 minutes to 10 hours, such as from 30 minutes to 10 hours, such as from 1 hour to 10 hours, such as from 2 hours to 10 hours, such as from 3 hours to 10 hours.

[0069] After calcining the pulverized mixture, it is typically cooled. "Cooling" means treating the material at a certain temperature or a gradually decreasing temperature range to lower the temperature of the material. Typical cooling conditions are a cooling rate between 1°C and 5°C per minute when the temperature is reduced from 900°C to 700°C. Optionally, the material can be cooled to, for example, 600°C, 500°C, 400°C, 300°C, 200°C, 100°C, 50°C, room temperature (i.e., approximately 25°C).

[0070] The second process is for producing secondary particles formed from aggregated single-crystalline particles of the first component, where the second oxide component is dispersed over the entire secondary particles on the surface of the single-crystalline particles at the boundaries between the single-crystalline particles. The following (a) and (b): (a) a first component comprising lithium transition metal oxide spinel particles selected from oxides of the formula Li x Ni y Mn 3-x-y O4 (where 0.98 < x < 1.00 and 0.41 < y < 0.50); (b) a second oxide component selected from oxides of Sr, Y, Zr, Nb, La, and W, and mixtures thereof; A method for producing a positive electrode active material comprising wherein the positive electrode active material is secondary particles formed from aggregated single-crystalline particles of the first component, and wherein the second oxide component is dispersed over the entire secondary particles on the surface of the single-crystalline particles at the interfaces between the single-crystalline particles, A method is provided.

[0071] This method comprises the following steps: (i) providing one or more transition metal compounds, (ii) contacting the transition metal compounds with one or more compounds containing the metal of the second oxide component or with the second oxide component, (iii) precipitating the transition metal and the metal of the second oxide component to form a precipitate and washing the precipitate to form a first precursor mixture. (iv) contacting the first precursor mixture with one or more lithium precursor compounds to form a second precursor mixture, and (v) calcining the second precursor mixture, are included.

[0072] The lithium precursor compound can be selected from Li2CO3, LiOH, LiNO3, and mixtures thereof.

[0073] The transition metal precursor compound of the second process can be selected from compounds of Ni and Mn that may be dissolved in water. In one aspect, the transition metal precursor compound is selected from MnSO4, Mn(NO3)2, NiSO4, Ni(NO3)2, and mixtures thereof.

[0074] The second oxide precursor of the second process can be selected from compounds of Sr, Y, Zr, Nb, La, and W, and mixtures thereof. In one aspect, the second oxide precursor of the second process can be selected from compounds of Sr, Y, Zr, Nb, La, and W that are soluble in water, and mixtures thereof. In one aspect, the second oxide precursor of the second process can be selected from Zr(SO4)2, Zr(NO3)4, and mixtures thereof.

[0075] In one aspect, the first precursor mixture is dried before (iv) contacting the first precursor mixture with one or more lithium precursor compounds to form a second precursor mixture.

[0076] In one aspect, the second precursor mixture is dried before (v) calcining the second precursor mixture.

[0077] In one aspect, the second precursor mixture is calcined at a temperature of at least 500 °C in a nitrogen atmosphere and then at a temperature of at least 800 °C in air.

[0078] In an aspect of the process, the second precursor mixture is calcined at a temperature from 300 to 1200 °C, such as from 400 to 1100 °C, such as from 500 to 1100 °C, such as from 500 to 1000 °C, such as from 600 to 1000 °C, such as from 700 to 950 °C.

[0079] The second precursor mixture can be calcined for any suitable period. In one aspect, the second precursor mixture is calcined for a period of at least 10 minutes, such as at least 30 minutes, such as at least 1 hour, such as at least 2 hours, such as at least 3 hours, such as at least 4 hours, such as at least 5 hours, such as at least 6 hours, such as at least 7 hours, such as at least 8 hours, such as at least 9 hours, such as at least 10 hours. In one aspect, the second precursor mixture is calcined for a period from 10 minutes to 20 hours, such as from 30 minutes to 20 hours, such as from at least 1 hour to 20 hours, such as from at least 2 hours to 20 hours, such as from at least 3 hours to 20 hours, such as from at least 4 hours to 20 hours, such as from at least 5 hours to 20 hours, such as from at least 6 hours to 20 hours, such as from at least 7 hours to 20 hours, such as from at least 8 hours to 20 hours, such as from at least 9 hours to 20 hours, such as from at least 10 hours to 20 hours.

[0080] After the second precursor mixture is calcined, it is typically cooled. "Cooling" means treating the material at a temperature or a gradually decreasing temperature range to lower the temperature of the material. Typical cooling conditions are a cooling between 1 °C and 5 °C per minute when the temperature is lowered from 900 °C to 700 °C. Optionally, the material can be cooled to, for example, 600 °C, 500 °C, 400 °C, 300 °C, 200 °C, 100 °C, 50 °C, room temperature (i.e., about 25 °C).

[0081] In one aspect, the precursor for the lithium cathode active material is manufactured from two or more raw materials, where these raw materials are partially or completely decomposed by heat treatment. Such raw materials are, for example, nickel manganese carbonates and lithium carbonates, or nickel manganese carbonates and lithium hydroxides, or nickel manganese hydroxides and lithium hydroxides, or nickel manganese hydroxides and lithium carbonates, or manganese oxides and nickel carbonates and lithium carbonates.

[0082] In one aspect, the raw materials further contain up to 2 mol% of elements other than Li, Ni, Mn, and O. Such elements may be, for example, one or more of B, N, F, Mg, Al, Si, P, S, Ca, Ti, Cr, Fe, Co, Cu, Zn, Zr, Sn, W, mixtures thereof, or one or more of chemical compositions containing one or more of these compounds. The dopant may be derived from the addition or from impurities in the raw materials.

[0083] "Precursor" means a composition prepared by mechanically mixing or co-precipitating raw materials to obtain a homogeneous mixture (Journal of Power Sources (2013) 238, 245 - 250 (Non-Patent Document 6)); or a composition prepared by mixing a composition prepared by mechanically mixing raw materials to obtain a homogeneous mixture with a lithium source (Journal of Power Sources (2013) 238, 245 - 250 (Non-Patent Document 6)); or a composition prepared by mixing a composition prepared by co-precipitating raw materials with a lithium source (Electrochimica Acta (2014) 115, 290 - 296 (Non-Patent Document 1)).

[0084] The raw material is selected from one or more compounds selected from the group consisting of metal oxides, metal carbonates, metal oxalates, metal acetates, metal nitrates, metal sulfates, metal hydroxides and pure metals, where the metal is selected from nickel (Ni), manganese (Mn) and lithium (Li) and mixtures thereof. Preferably, the raw material is selected from one or more compounds selected from the group consisting of manganese oxide, nickel oxide, manganese carbonate, nickel carbonate, manganese sulfate, nickel sulfate, manganese nitrate, nickel nitrate, lithium hydroxide, lithium carbonate and mixtures thereof. The metal oxidation state of the raw material can be various, for example, MnO, Mn3O4, Mn2O3, MnO2, Mn(OH), MnOOH, Ni(OH)2, NiOOH, etc.

[0085] In one aspect, a reducing atmosphere is created during a portion of the calcination of the raw material and / or the precursor material by adding a substance to the precursor composition, by decomposing the precursor, or by adding a gaseous composition to the atmosphere, in order to remove all or part of the oxidizing species present in the atmosphere. Preferably, ambient air cannot enter the reaction vessel.

[0086] The term "reducing atmosphere" means an atmosphere that shifts the thermodynamic equilibrium of the solid towards a distribution of phases with a lower average metal oxidation state than in the spinel phase at the relevant heat treatment temperature. This reducing atmosphere can be provided by the type of gas present in the reaction vessel during heating. This gas can be provided by the presence of a reducing gas; for example, the reducing gas can be hydrogen; carbon monoxide; carbon dioxide; nitrogen; oxygen less than 15 volume % in an inert gas; and one or more gases selected from the group of mixtures thereof. The description "oxygen less than 15 volume % in an inert gas" is intended to cover from 0 volume % oxygen, corresponding to an inert gas without oxygen, to 15 volume % oxygen in the inert gas. Preferably, the amount of oxygen in the reducing atmosphere is low, for example less than 1000 ppm, most preferably less than 10 ppm. Typically, oxygen will not be added to the atmosphere, but oxygen may be generated during heating.

[0087] "Inert gas" means a gas that does not participate in the process. Examples of inert gases include one or more gases selected from the group of argon; nitrogen; helium; and mixtures thereof.

[0088] Additionally, the term "reducing atmosphere" is meant to include a composition containing two or more gases, where one gas would be considered a non-reducing atmosphere gas if used independently of the other gases, and the second gas or substance reduces the oxidation potential of the gas mixture. The overall reducing nature of the atmosphere corresponds to a reducing atmosphere. Such compositions may be selected from the group including nitrogen, less than 15 volume % oxygen in an inert gas, air and hydrogen; air and CO; air and methanol; air and carbon dioxide.

[0089] Additionally, a "reducing atmosphere" can be obtained by adding a substance to the precursor composition or by adding a gaseous composition to the atmosphere in order to remove all or part of the oxidizing chemical species present in the atmosphere of the reaction vessel during heating. The substance can be added to the precursor during the manufacture of the precursor or prior to the heat treatment. The substance can be a material that can oxidize and preferably contains carbon, for example the substance can be one or more compounds selected from the group consisting of graphite, acetic acid, carbon black, oxalic acid, wood fiber and plastic materials.

[0090] "Calcination" means treating a material at a certain temperature or temperature range to obtain a desired crystallinity. This temperature or temperature range is intended to represent the temperature of the material being heat treated. Typical calcination temperatures are about 500 °C, about 600 °C, about 700 °C, about 800 °C, about 900 °C, about 1000 °C, and the temperature ranges are from about 300 to about 1200 °C; from about 500 to about 1000 °C; from 650 to 950 °C. The description "calcination at a temperature between X and Y °C" is not meant to be limited to one specific temperature between X and Y, but instead the description also includes calcination in the range of temperatures within the temperature width from X to Y during the heating time.

[0091] The method of the present invention may include one or more further additional steps. These one or more further additional steps can be before, after or in the middle of the steps described herein.

[0092] Aspects of the present invention will be described by way of example with reference to the accompanying drawings. The accompanying drawings show only examples of aspects of the present invention and should not be regarded as limiting its scope. This is because other alternative aspects are possible in the present invention.

Brief Description of the Drawings

[0093]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

[0094] The present invention will be described based on the following non-limiting examples.

Example

[0095] The exemplary and non-limiting aspects of the present invention are described below in the form of experimental data. Examples 1 to 6 relate to a method for manufacturing a lithium cathode active material. Example 7 describes a method for measuring the minimum Feret diameter. Example 8 describes a method for electrochemical tests.

[0096] Example 1 Synthesis of Lithium Cathode Active Material MnO2 (280 g; corresponding to 3.2 mol of Mn), basic Ni(OH) x (CO3) y(133 g; equivalent to 0.9 mol of Ni), Li2CO3 (76.8 g; equivalent to 2.1 mol of Li), and ZrO2 (4 g; equivalent to 0.03 mol of Zr) were weighed, and in order to produce a slurry with a molar ratio of Li:Ni:Mn:Zr of 1.00:0.45:1.55:0.015, they were ball milled as an aqueous slurry in a planetary ball mill (using reverse rotation at 600 rpm for 30 minutes). Then, this mixture was dried at 120 °C for 12 hours. Next, this powder was mixed in a mortar for 15 minutes to obtain a precursor. This precursor was heated in a 50 mL crucible at 900 °C for 3 hours, and then cooled to room temperature at 1 °C / min. The resulting product was crushed in a mortar for 15 minutes and passed through a 45 micron sieve to obtain a lithium positive electrode active material composed of LNMO containing 1 wt% of ZrO2. The SEM image of this sample is shown in Figure 1. From Figure 1, it can be seen that ZrO2 exists as particles on the surface of the LNMO particles as bright points. The coverage rate of LNMO by the ZrO2 particles is as low as a few percent and is found to be less than at least 15 percent.

[0097] Example 2 Synthesis of Lithium Positive Electrode Active Material MnO2 (280 g; equivalent to 3.2 mol of Mn), basic Ni(OH) x (CO3) y (133 g; equivalent to 0.9 mol of Ni), and Li2CO3 (76.8 g; equivalent to 2.1 mol of Li) were weighed, and in order to produce a slurry with a molar ratio of Li:Ni:Mn of 1.00:0.45:1.55, they were ball milled as an aqueous slurry in a planetary ball mill (using reverse rotation at 600 rpm for 30 minutes). Then, this mixture was dried at 120 °C for 12 hours. Next, this powder was mixed in a mortar for 15 minutes to obtain a precursor. This precursor was heated in a 50 mL crucible at 900 °C for 3 hours, and then cooled to room temperature at 1 °C / min. The resulting product was crushed in a mortar for 15 minutes and passed through a 45 micron sieve to obtain a lithium positive electrode active material composed of LNMO. The SEM image of this sample is shown in Figure 2.

[0098] Example 3 Synthesis of Lithium Positive Electrode Active Material A 1M solution of NiSO4, MnSO4 and ZrSO4 corresponding to a molar ratio of Ni:Mn:Zr of 0.45:1.55:0.015 is mixed, and this mixture is combined with 1M Na2CO3 solution while stirring to form spherical particles of co-precipitated Ni,Mn,Zr-carbonate, which are washed and dried to remove Na + and SO4 2- ions, thereby co-precipitating Ni,Mn,Zr-carbonate. 949 g of the co-precipitated Ni,Mn,Zr-carbonate particles are mixed with 150 g of Li2CO3 (corresponding to Li:Ni:Mn:Zr of 1.00:0.45:1.55:0.015) and ethanol to form a viscous slurry. This slurry is shaken in a paint shaker for 3 minutes to obtain complete deaggregation and to mix the granular materials. This slurry is poured into a tray and dried at 80 °C. This dried material is shaken in a paint shaker for 1 minute for further deaggregation to obtain a free-flowing homogeneous powder mixture. This powder mixture is heated in a furnace to 550 °C at a rate of 2.5 °C / min using a nitrogen flow. This powder is heated at 550 °C for 4 hours. Thereafter, this powder is treated at 550 °C in air for 9 hours. The temperature is increased to 950 °C at a rate of 2.5 °C / min. The temperature of 950 °C is maintained for 10 hours and then lowered to room temperature at a rate of 2.5 °C / min.

[0099] This powder is deaggregated again by shaking in a paint shaker for 6 minutes and passed through a 45 micron sieve to obtain a lithium positive electrode active material composed of LNMO containing 1 wt% ZrO2. SEM images of this sample are shown in Figures 3 and 4. From Figures 3 and 4, it can be seen that ZrO2 exists as bright spots on the surface of the LNMO particles and in the grain boundaries of the individual crystal domains in the LNMO particles. The coverage rate of LNMO by the ZrO2 particles is as low as a few percent and is found to be less than at least 15 percent.

[0100] Example 4 Synthesis of Lithium Positive Electrode Active Material A 1M solution of NiSO4 and MnSO4 corresponding to a Ni:Mn molar ratio of 0.45:1.55 is mixed, and this mixture is combined with 1M Na2CO3 solution while stirring to produce spherical particles of co-precipitated Ni,Mn-carbonate, which are then washed and dried to remove + Na 2- and SO4 ions, thereby co-precipitating Ni,Mn-carbonate. 940 g of the co-precipitated Ni,Mn-carbonate particles are mixed with 150 g of Li2CO3 (corresponding to Li:Ni:Mn of 1.00:0.45:1.55) and ethanol to produce a viscous slurry. This slurry is shaken in a paint shaker for 3 minutes to obtain complete de-aggregation and mix the granular materials. This slurry is poured into a tray and dried at 80 °C. The dried material is further de-aggregated by shaking in a paint shaker for 1 minute to obtain a free-flowing, homogeneous powder mixture. This powder mixture is heated in a furnace to 550 °C at a rate of 2.5 °C / min using a nitrogen flow. The powder is heated at 550 °C for 4 hours. Then, this powder is treated at 550 °C in air for 9 hours. The temperature is increased to 950 °C at a rate of 2.5 °C / min. The temperature of 950 °C is maintained for 10 hours and then decreased to room temperature at a rate of 2.5 °C / min.

[0101] This powder is shaken in a paint shaker for 6 minutes to re-de-aggregate and then passed through a 45-micron sieve to obtain a lithium positive electrode active material composed of LNMO. SEM images of this sample are shown in Figures 5 and 6.

[0102] Example 5: Synthesis of Lithium Positive Electrode Active Material The LNMO single crystal material from Example 2 is mixed with ZrO2 particles having a primary particle size of 10 - 20 nm in a molar ratio corresponding to LNMO:Zr = 1:0.015, and this mixture is shaken in a paint shaker for 10 minutes to de-aggregate the aggregates of ZrO2 primary particles and disperse the ZrO2 particles. SEM images of this sample are shown in Figure 7.

[0103] Example 6: Synthesis of Lithium Positive Electrode Active Material The LMNO ZrO2 mixture from Example 5 was calcined as described in Examples 1 and 2 to obtain a closer contact between LNMO and ZrO2. The SEM image of this sample is shown in Figure 8.

[0104] Example 7: Material Characterization The material of Example 1 was embedded in epoxy and polished to a flat surface. The SEM image was obtained with a Zeiss GeminiSEM500 equipped with a field emission electron gun (FEG) with an acceleration voltage of 10 kV and an energy selective backscatter (ESB) detector of the backscattered electron detector type. The pixel size was 0.01 μm / pixel. A total of 25 images were obtained and stitched into a high-resolution image of 4930 pixels × 3697 pixels corresponding to an image area of 48 μm × 36 μm.

[0105] The image is shown in Figure 9. The said image was analyzed according to the procedure shown below, and a total of 663 particles were detected and analyzed.

[0106] The image was analyzed using software called ImageJ (https: / / imagej.nih.gov). The procedure was as follows: · Threshold setting and segmentation using "Otsu's algorithm" · Apply the binary process "Fill holes". · Apply the binary process "Erode" 8 times. · Apply the binary process "Dilate" 6 times. · Use "Analyze particles" without size limitation.

[0107] Fill holes is used to fill holes that may exist within the particles. Then, the erosion and subsequent dilation steps are used to remove possible noise and ensure that nearby particles are separated.

[0108] [Table 1]

[0109] Example 8 Electrochemical Characterization Electrochemical tests were carried out in 2032-type coin cells using a thin composite positive electrode and a negative electrode (half cell) of metallic lithium and a graphite composite electrode (full cell), respectively. The thin composite positive electrode was prepared by thoroughly mixing 92 wt% of a lithium positive electrode active material (manufactured according to Examples 1 to 4), 4 wt% of Super C65 carbon black (TIMCAL), and 4 wt% of a PVdF binder (polyvinylidene difluoride, Sigma-Aldrich) in NMP (N-methyl-pyrrolidone) to produce a slurry. The LNMO materials tested were LNMO containing ZrO2 from Example 3 ('LNMO containing 1 wt% of ZrO2' shown in FIG. 10), and LNMO from Example 4 ('LNMO' shown in FIG. 10), and a 40:60 mixture of LNMO containing ZrO2 from Examples 1 and 3 ('LNMO containing 1 wt% of ZrO2' shown in FIGS. 11 to 12), and a 40:60 mixture of LNMO from Examples 2 and 4 ('LNMO' shown in FIGS. 11 to 12).

[0110] These slurries were applied onto carbon-coated aluminum foil using a doctor blade having a 100-200 μm gap, and dried at 80° C. for 12 hours to form a film. Electrodes having a diameter of 14 mm and loaded with approximately 12 mg of the lithium positive electrode active material were cut out from the dried film, pressed with a hydraulic pellet press (diameter 20 mm; 3 metric tons), and subjected to drying under vacuum at 120° C. for 10 hours in an argon-filled glove box.

[0111] The graphite electrode was prepared using 97 wt% of graphite (GDHR15-4 manufactured by Imerys), 1 wt% of Super C65 carbon black, 1 wt% of a CMC binder, and 1 wt% of an SBR binder in an aqueous slurry. The slurry was cast onto carbon-coated copper foil using a coating bar height of 30-80 μm to obtain the desired loading amount.

[0112] For half-cells, coin cells were assembled in an argon-filled glove box (<1 ppm O2 and H2O) using a glass fiber separator, an electrolyte containing 1 mol of LiPF6 in EC:DEC (1:1 by weight), and two 250-μm thick lithium disks as the anode electrode. For full cells, a Celgard H2010 separator, an electrolyte containing 1 mol of LiPF6 in EC:DEC (1:1 by weight) with 1 wt% LiBOB and 1 wt% tris(trimethylsilyl)phosphite, and a 16-mm diameter graphite electrode with a loading corresponding to a balancing N / P of 1.2 (within the positive electrode region) were used.

[0113] Electrochemical lithium insertion and extraction were monitored using an automatic cycle data recording system (manufactured by McCall) operating in constant current mode.

[0114] The electrochemical tests for half-cells (Figure 10) included 6 formation cycles (3 cycles at 0.2C / 0.2C (charge / discharge) and 3 cycles at 0.5C / 0.2C), 25 power test cycles (5 cycles at 0.5C / 0.5C, 5 cycles at 0.5C / 1C, 5 cycles at 0.5C / 2C, 5 cycles at 0.5C / 5C, 5 cycles at 0.5C / 10C), and then 120 cycles at 0.5C / 1C to measure degradation. The electrochemical tests for full cells (Figures 11 - 12) included 2 formation cycles at 0.1C / 0.1C, then 1 cycle at 0.1C / 0.1C with a constant voltage step during charging up to 0.03C, and then 49 cycles at 0.5C / 1C with a constant voltage step during charging up to 0.1C. Then, the last 1 + 49 cycles were repeated multiple times to test the development of discharge capacity over a larger number of cycles. The C-rate was calculated based on the theoretical specific capacity of 147 mAh g−1 of the lithium positive electrode active material. Thus, for example, 0.2C corresponds to 29.6 mA g−1, and 20 and 10C correspond to 1.47 A g−1. The tests shown in Figures 10 - 11 were measured at 23 °C, and the test shown in Figure 12 was measured at 45 °C.

[0115] Various improvements and modifications of the present invention will be apparent to those skilled in the art without departing from the scope and spirit of the present invention. Although the present invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. In fact, various improvements of the modes described for carrying out the present invention, which will be apparent to those skilled in the art in the chemical and related fields, are intended to be within the scope of the claims.

[0116] It can be seen from these electrochemical measurements that the electrochemical performance, and in particular the capacity and cycle life, are significantly improved by adding ZrO2 particles to the LNMO material as described in Examples 1 and 3.

Claims

1. (a) formula Li ｘ Ni ｙ Mn ３－ｘ－ｙ O ４ (wherein, 0.98 < x < 1.00 and 0.41 < y < 0.50) a first component comprising lithium transition metal oxide spinel particles selected from oxides; (b) A total amount of a second oxide component of 0.01 to 3 atomic % based on the total number of atoms in the positive electrode active material, selected from oxides of Sr, Y, Zr, Nb, La, and W, and mixtures thereof; A positive electrode active material comprising: wherein the positive electrode active material: (i) Particles containing one or more single crystals of the first component (a), wherein the arithmetic mean value of the minimum Feret diameter of the particles measured using a scanning electron microscope is 3 μm or less, and the second oxide component (b) is at least partially disposed on the surfaces of these particles; and / or (ii) Secondary particles containing aggregated single crystal particles of the first component (a), wherein the second oxide component (b) is dispersed over the entire secondary particles on the surfaces of the single crystal particles at the interfaces between the single crystal particles, and the secondary particles have an average particle diameter (D50) of less than 20 μm; The positive electrode active material as described above.

2. The positive electrode active material according to claim 1, wherein the second oxide component (b) is at least an oxide of Zr.

3. The secondary particles (ii) have a tap density of at least 1.5 g / cm ３ The positive electrode active material according to claim 1 or 2.

4. The positive electrode active material according to any one of claims 1 to 3, wherein the second oxide component is present in an amount that provides Sr, Y, Zr, Nb, La, and W in a total amount of 0.05 to 0.4 atomic % based on the total number of atoms in the positive electrode active material.

5. The positive electrode active material according to any one of claims 1 to 4, wherein the second oxide component is formed on the surface of particles formed from one or more single crystals or is bonded to the surface of single crystal particles.

6. wherein the positive electrode active material is zLi ｘ Ni ｙ Mn ３－ｘ－ｙ O ４ ·(1 - z)ZrO ２ (where 0.98 < x < 1.00 and 0.41 < y < 0.50, and 0.96 < z < 1), the positive electrode active material according to any one of claims 1 to 5.

7. When the positive electrode active material is one or more particles containing one or more single crystals of the first component, at least 20% of the surface of the single crystal is a free surface, preferably at least 50% of the surface of the single crystal is a free surface. The positive electrode active material according to any one of claims 1 to 6.

8. (a) formula Li ｘ Ni ｙ Mn ３－ｘ－ｙ O ４ (wherein, 0.98 < x < 1.00 and 0.41 < y < 0.50) a first component containing lithium transition metal oxide spinel particles selected from oxides; (b) A second oxide component selected from oxides of Sr, Y, Zr, Nb, La, and W, and mixtures thereof; A method for manufacturing the positive electrode active material according to any one of claims 1 to 7, wherein the positive electrode active material is particles containing one or more single crystals of the first component, and the second oxide component (b) is disposed on the surfaces of these particles; The process for manufacturing the first component (a) comprises the following steps: (i) Providing one or more lithium precursor compounds and one or more transition metal precursor compounds; (ii) contacting and grinding the precursor compound to form a ground mixture; (iii) calcining the ground mixture at a temperature of at least 800° C. to provide a calcined mixture; (including (A) prior to the calcination step (iii), combining the second oxide, or second oxide precursor, with the one or more lithium precursor compounds and the one or more transition metal precursor compounds; or (B) after the calcination step (iii), combining the calcined mixture with the second oxide, the method.

9. wherein the lithium precursor compound is Li ２ CO ３ , LiOH, LiNO ３ , and a mixture thereof, the method according to claim 8.

10. wherein the transition metal precursor compound is MnO ２ , Mn ３ O ４ , MnCO ３ , NiCO ３ , basic Ni carbonate, for example Ni(CO ３ ), ｘ (OH) ｙ ·zH ２ O (where 2x + y = 2), and a mixture thereof, the method according to claim 8 or 9.

11. The second oxide precursor is ZrO ２ , Zr(CO ３ ) ４ The method according to any one of claims 8 to 10, wherein the hydroxyl group is selected from the group consisting of hydroxyl groups, ...

12. (a) type Li ｘ Ni ｙ Mn ３－ｘ－ｙ O ４ (wherein, 0.98 < x < 1.00 and 0.41 < y < 0.50) a first component containing lithium transition metal oxide spinel particles selected from oxides; (b) a second oxide component selected from oxides of Sr, Y, Zr, Nb, La and W, and mixtures thereof; A method for producing a positive electrode active material according to any one of claims 1 to 7, comprising: the positive electrode active material is secondary particles containing aggregated single crystal particles of the first component, and the second oxide component is dispersed over the secondary particles on the surface of the single crystal particles at the interface between the single crystal particles; The following steps: (i) providing one or more transition metal compounds, (ii) contacting the transition metal compound with one or more compounds containing the metal of the second oxide component, or with the second oxide component, (iii) depositing a transition metal and the metal of the second oxide component to form a deposit, and washing the deposit to form a first precursor mixture, (iv) contacting the first precursor mixture with one or more lithium precursor compounds to form a second precursor mixture, and (v) calcining the second precursor mixture. (including

13. wherein the lithium precursor compound is Li ２ CO ３ , LiOH, LiNO ３ , and mixtures thereof, the method according to claim 12.

14. The transition metal precursor compound is MnSO ４ , Mn(NO ３ ), ２ , NiSO ４ , Ni(NO ３ ), ２ and the method according to claim 12 or 13, selected from mixtures thereof.

15. The transition metal compound used to prepare the second oxide particles is Zr(SO ４ ) ２ , Zr(NO ３ ) ４ The method according to any one of claims 12 to 14, wherein the hydroxyl group is selected from the group consisting of hydroxyl groups, ...

16. The method according to any one of claims 12 to 15, wherein the second precursor mixture is dried before (v) calcining the second precursor mixture.

17. The method according to any one of claims 12 to 16, wherein the second precursor mixture is calcined in a nitrogen atmosphere at a temperature of at least 500° C., and then calcined in air at a temperature of at least 800° C.

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