Lithium-nickel composite oxides as cathode active materials for rechargeable lithium-ion batteries

Abstract

A cathode active material for a solid-state battery comprising Li, M' and oxygen, M' comprising Ni with a content x of 70.0 mol% to 95.0 mol%, Co with a content y of 0.0 mol% to 40.0 mol%, Mn with a content z of 0.0 mol% to 40.0 mol%, a dopant with a content a of 0.0 mol% to 2.0 mol%, and Zr with a content b of 0.1 mol% to 5.0 mol%, where x+y+z+a+b is 100.0 mol%, and the cathode active material has a Zr content ZrA defined as formula (I), B and Zr B is expressed as a mole fraction relative to the sum of the mole fractions of Co, Mn, Ni and Zr as determined by XPS analysis, Zr B / Zr A >50.0, and the active cathode material comprises secondary particles having a plurality of primary particles, the primary particles having an average diameter of at least 250 nm.

Description

[Technical Field]

[0001] Background technology The present invention relates to a lithium nickel-based oxide positive electrode active material for solid-state batteries suitable for electric vehicle (EV) and hybrid electric vehicle (HEV) applications, which comprises lithium nickel-based oxide particles containing zirconium (Zr). [Background technology]

[0002] The positive electrode active material is defined as a material that is electrochemically active in the positive electrode, and is understood to be a material that can capture and release Li ions when exposed to a voltage change over a period of time.

[0003] In the framework of the present invention, atomic % means atomic percentage. Atomic % or "atom percent" as an expression of the concentration of a given element means what percentage of all atoms in the claimed compound are atoms of that element. The term atomic % is synonymous with mol % or "mole percent".

[0004] The weight percent (wt%) of the first element E in the material (E wt1 ) is the following expression:

[0005]

number

[0006] It is an object of the present invention to provide a positive electrode active material having an improved first charge capacity of at least 160 mAh / g in a solid state battery. [Means for solving the problem]

[0007] The object is to provide a cathode active material for a solid-state battery, the cathode active material comprising Li, M' and oxygen, wherein M' is Ni with a content x of 70.0 mol% to 95.0 mol% relative to M', Co with a content y of 0.0 mol% to 40.0 mol% relative to M'; Mn with a content z of 0.0 mol% to 40.0 mol% relative to M'; D having a content a of 0.0 mol% to 2.0 mol% relative to the total atomic content of M', which contains at least one element selected from the group consisting of Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, W and Zn; Zr having a content b of 0.1 mol% to 5.0 mol% relative to M', where x, y, z, a, and b are measured by ICP; x+y+z+a+b is 100.0 mol%, The positive electrode active material is

[0008]

number

[0009] Zr content defined as Zr A The positive electrode active material has a Zr content of Zr B and Zr B was determined by XPS analysis, and Zr B is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni and Zr as determined by XPS analysis, Zr ratio B / Zr A >50.0, the positive electrode active material includes secondary particles having a plurality of primary particles, The primary particles are achieved by providing a cathode active material having an average diameter of at least 250 nm as determined by measuring the primary particle size in an image taken by SEM.

[0010] The present invention relates to the following embodiments.

[0011] Embodiment 1 In a first aspect, the present invention provides a cathode active material for a solid-state battery, the cathode active material comprising Li, M′, and oxygen, wherein M′ is: Ni with a content x of 70.0 mol% to 95.0 mol% relative to M', preferably Ni with a content x of 75.0 mol% to 95.0 mol% relative to M', Co with a content y of 0.0 mol% to 40.0 mol% relative to M'; Mn with a content z of 0.0 mol% to 70.0 mol% relative to M', preferably Mn with a content z of 0.0 mol% to 40.0 mol% relative to M', D having a content a of 0.0 mol% to 2.0 mol% relative to the total atomic content of M', which contains at least one element selected from the group consisting of Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, W and Zn; Zr having a content b of 0.1 mol% to 5.0 mol% relative to M', x, y, z, a, and b are measured by ICP, x+y+z+a+b is 100.0 mol%, The positive electrode active material contains Zr

[0012]

number

[0013] The positive electrode active material has a Zr content of Zr B and Zr B was determined by XPS analysis, and Zr Bis expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni and Zr as determined by XPS analysis, Zr ratio B / Zr A >50.0 for the positive electrode active material.

[0014] Zr A Note that σ is the Zr content of the positive electrode active material determined by ICP, expressed as a fraction of the total Co, Ni, Mn, and Zr contents.

[0015] Preferably, Zr B / Zr A The ratio is at least 80, preferably at least 100, more preferably at least 120, and most preferably at least 130. Preferably, Zr B / Zr A The ratio is at most 500, more preferably at most 300, and most preferably at most 200.

[0016] Preferably, the positive electrode active material comprises secondary particles having a plurality of primary particles, the primary particles having an average diameter of at least 200 nm as determined by measuring the primary particle size in an image taken by SEM.

[0017] More preferably, the primary particles have an average diameter of at least 250 nm, even more preferably at least 300 nm, and most preferably at least 350 nm.Even more preferably, the primary particles have an average diameter of at least 260 nm, preferably at least 270 nm, even more preferably at least 280 nm, and most preferably at least 290 nm.

[0018] Preferably, the primary particles have an average diameter of at most 1000 nm, preferably at most 600 nm, more preferably at most 500 nm.

[0019] Preferably, the primary particles have an average diameter of 250 nm to 1000 nm, preferably 300 nm to 600 nm, more preferably 350 nm to 500 nm.

[0020] Preferably, x≧77.0 mol%, more preferably x≧80.0 mol%, and even more preferably x>81.0 mol%.

[0021] Preferably, x≦91.0 mol %, more preferably x≦90.0 mol %.

[0022] Preferably, y>0 mol%, more preferably y≧5.0 mol%, and even more preferably y≧9.0 mol%.

[0023] In another embodiment, the Ni content x is 77 mol % to 90 mol % relative to M', and the Co content y is 0.0 mol % to 20.0 mol % relative to M'.

[0024] In a preferred embodiment, the Ni content is x≧78.0 mol%, preferably x≧80.0 mol%, more preferably x≧82.0 mol%. In a preferred embodiment, x≦92.0 mol%, preferably x≦90.0 mol%, more preferably x≦88.0 mol%. A more preferred embodiment is the positive electrode active material of the present invention, in which the Ni content x is 78.0 mol%≦x≦92.0 mol%, preferably 80.0 mol%≦x≦92.0 mol%, more preferably 82.0 mol%≦x≦88.0 mol%.

[0025] As will be understood by those skilled in the art, the amounts of Li and M', preferably Li, Ni, Mn, Co, D, and Zr, in the positive electrode active material are measured by inductively coupled plasma-optical emission spectroscopy (ICP-OES). For example, and not by way of limitation, an Agilent ICP 720-ES is used for ICP-OES analysis.

[0026] In a preferred embodiment, Mn has a content of z > 0.0 mol%, more preferably z ≥ 5.0 mol%, and even more preferably z ≥ 8.0 mol%. In a preferred embodiment, the content is z ≤ 40.0 mol%, preferably z ≤ 30.0 mol%, and more preferably z ≤ 15.0 mol%. In a preferred embodiment, the content is 0.0 mol% < z ≤ 40.0 mol%, preferably 5.0 mol% ≤ z ≤ 30.0 mol%, and more preferably 8.0 mol% ≤ z ≤ 15.0 mol%.

[0027] In a preferred embodiment, Co has a content of y > 0.0 mol%, more preferably y ≥ 1.0 mol%, and even more preferably y ≥ 3.0 mol%. In a preferred embodiment, the content is y ≤ 40.0 mol%, more preferably y ≤ 20.0 mol%, and even more preferably y ≤ 10.0 mol%. In a preferred embodiment, the content is 0.0 mol% < y ≤ 40.0 mol%, preferably 1.0 mol% ≤ y ≤ 20.0 mol%, and more preferably 3.0 mol% ≤ y ≤ 10.0 mol%.

[0028] In a preferred embodiment, D contains at least one element from the group consisting of Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, W, and Zn, preferably Al, B, Cr, Nb, S, Si, Ti, Y, and W.

[0029] In a preferred embodiment, D has a content of a > 0.0 mol%, more preferably a ≥ 0.25 mol%, and even more preferably a ≥ 0.5 mol%. In a preferred embodiment, the content is a ≤ 2.0 mol%, preferably a ≤ 1.75 mol%, and more preferably a ≤ 1.5 mol%. In a preferred embodiment, the content is 0.0 mol% < a ≤ 2.0 mol%, preferably 0.25 mol% ≤ a ≤ 1.75 mol%, and more preferably 0.5 mol% ≤ a ≤ 1.5 mol%.

[0030] As will be appreciated by those skilled in the art, a secondary particle comprises a plurality of primary particles, preferably more than 20 primary particles, preferably more than 10 primary particles, and most preferably more than 5 primary particles. A primary particle is either an individual crystal or a particle formed from fewer than 5, preferably at most 3, primary particles that are themselves individual crystals. This can be seen by observing the grain boundaries with a suitable microscopic technique, such as a Scanning Electron Microscope (SEM).

[0031] Embodiment 2 In a second embodiment, preferably according to embodiment 1, the Zr content Zr A is b / (b+x+y+z) and is at least 0.10 mol% and at most 1.00 mol%. Preferably, the Zr content Zr A is b / (b+x+y+z) and is at least 0.20 mol % and at most 0.80 mol %. Most preferably, the Zr content Zr A is b / (b+x+y+z) and is at least 0.30 mol % and at most 0.70 mol %. In an alternative but more preferred embodiment, the Zr content Zr A is b / (b+x+y+z) and is at least 0.10 mol% and at most 1.50 mol%. Preferably, the Zr content Zr A is b / (b+x+y+z) and is at least 0.20 mol % and at most 1.00 mol %. Most preferably, the Zr content Zr A is b / (b+x+y+z) and is at least 0.30 mol % and at most 0.90 mol %.

[0032] In a preferred embodiment, Zr has a content b of at least 0.10 mol% and at most 1.00 mol% relative to M', more preferably at least 0.20 mol% and at most 0.80 mol% relative to M', and most preferably at least 0.30 mol% and at most 0.70 mol% relative to M'.

[0033] In an alternative but even more preferred embodiment, Zr has a content b of at least 0.10 mol % and at most 1.50 mol % relative to M', more preferably at least 0.20 mol % and at most 1.00 mol % relative to M', and most preferably at least 0.30 mol % and at most 0.90 mol % relative to M'.

[0034] In a preferred embodiment, the Zr content is Zr B is greater than 0.25 mol%, preferably greater than 0.50 mol%, most preferably greater than 0.60 mol%. In a preferred embodiment, Zr B is less than 2.0 mol%, preferably less than 1.5 mol%, more preferably less than 1.0 mol%. In a preferred embodiment, Zr B is 0.25 mol % to 2.0 mol %, preferably 0.50 mol % to 1.5 mol %, and most preferably 0.60 mol % to 1.0 mol %. As will be understood by those skilled in the art, Zr B is expressed as the mole fraction determined by XPS analysis compared to the sum of the mole fractions of Co, Mn, Ni and Zr determined by XPS analysis.

[0035] Embodiment 3 In a third embodiment according to embodiment 1 or 2, the material has a median secondary particle size D50 of at least 2 μm, preferably at least 3 μm, as determined by laser diffraction particle size analysis.

[0036] Preferably, the material has a median secondary particle size D50 of at most 15 μm, preferably at most 10 μm, as determined by laser diffraction particle size analysis.

[0037] For example, and not by way of limitation, laser diffraction particle size analysis is performed on a Malvern Mastersizer 3000.

[0038] Embodiment 4 In a fourth embodiment according to embodiments 1 to 3, the material has a carbon content of at least 600 ppm, preferably at least 650 ppm, more preferably at least 750, and most preferably at least 900 ppm, as determined by a carbon analyzer.

[0039] Preferably, the material has a carbon content, as determined by a carbon analyzer, of at most 8000 ppm, preferably at most 7500 ppm, more preferably at most 5000 ppm, most preferably at most 2000 ppm.

[0040] As will be appreciated by those skilled in the art, in any of the first to fourth embodiments, Zr B is expressed as the mole fraction measured by XPS analysis compared to the sum of the mole fractions of Co, Mn, Ni, and Zr measured by XPS analysis, and in particular Zr B is the mole fraction of Zr measured in a region of a secondary particle of the positive electrode active material according to the present invention, defined between a first point on the outer edge of the particle and a second point at a certain distance from the first point, and the distance separating the first point and the second point is equal to the XPS penetration depth, D, which is 1.0 to 10.0 nm. In particular, the penetration depth is the distance along an axis perpendicular to an imaginary line tangent to the outer edge and passing through the first point.

[0041] The outer edge of a particle is, in the framework of the present invention, the boundary or outer limit that distinguishes the particle from its external environment.

[0042] Therefore, XPS analysis provides the atomic content of an element in the top layer of a particle with a penetration depth of about 10.0 nm from the particle's periphery. The particle's periphery is also called the "surface." In the context of the present invention, atomic % means atomic percentage. As an expression of the concentration of a given element, atomic % or "atomic percent" means what percentage of all atoms in the compound are atoms of that element. The term atomic % is synonymous with mol % or "mole percent." For example, and not limiting to the present invention, XPS analysis is performed using a Thermo K-α+ spectrometer (Thermo Scientific).

[0043] The present invention relates to the use of the positive electrode active material according to any one of the above-mentioned embodiments 1 to 4 in a battery.

[0044] The present invention also provides a method for producing a positive electrode active material according to any one of the above-described first to fourth embodiments, preparing a lithium transition metal based compound; mixing the lithium transition metal-based compound with a Zr source, preferably Zr alkoxide in a lithium alkoxide-containing alcohol solvent, thereby obtaining a mixture; removing the volatile phase comprising the solvent, preferably by vacuum heating; and heating the mixture in an oxidizing atmosphere in a furnace at a temperature of 350°C to less than 500°C, preferably at most 450°C, for a time period of 1 hour to 20 hours to obtain the positive electrode active material powder according to the present invention.

[0045] In a preferred embodiment, the lithium transition metal based compound is a lithium nickel based oxide compound.

[0046] In a preferred embodiment of the method, the lithium transition metal based oxide compound comprises Li, M' and oxygen, wherein M' comprises Ni, Mn, Co and D, wherein D is Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, W and Zn; preferably at least one element from the group consisting of Al, B, Cr, Nb, S, Si, Ti, Y, W.

[0047] Preferably, the lithium transition metal oxide powders used are also typically prepared according to a lithiation process, i.e., a process in which a mixture of a transition metal precursor and a lithium source is heated, preferably at a temperature of at least 500° C. Typically, the transition metal precursor is prepared by co-precipitation of one or more transition metal sources, such as salts, preferably sulfates, of the M′ elements Ni, Mn and / or Co, in the presence of an alkali compound, such as an alkali hydroxide, for example sodium hydroxide and / or ammonia.

[0048] Preferably, the method comprises the further step of drying the mixture, preferably by vacuum heating, before heating the mixture.

[0049] In a preferred embodiment of the present method, the Zr source is a Zr alkoxide, preferably Zr ethoxide, Zr propoxide, or Zr butoxide, more preferably Zr propoxide. In a preferred embodiment, the Zr alkoxide is mixed with the mixture as a solid. Alternatively, more preferably, the Zr alkoxide is mixed with the slurry as a solution, the solution comprising the Zr alkoxide and an additional alcohol, the alkoxide group being the conjugate base of the additional alcohol. For example, the Zr alkoxide is Zr propoxide dissolved in propanol. Typically, the solution contains 50 to 90 wt. % of the Zr alkoxide based on the total weight of the solution. Examples of such solutions are 70 wt. % Zr propoxide in 1-propanol or 80 wt. % Zr butoxide in 1-butanol.

[0050] Preferably, the alcohol solvent is methanol, ethanol, propanol or butanol, preferably ethanol.

[0051] The present invention also includes a solid-state battery including the positive electrode active material according to any one of the above-described first to fourth embodiments. Preferably, the solid-state battery includes a sulfide-based solid electrolyte, more preferably, the sulfide-based solid electrolyte includes Li, P, and S. Typically, the solid-state battery includes the following sulfur-containing compounds: Li6PS5Cl (LPSCL), thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, LiC2S-SiS2, LiI-Li2S-SiS 2、 Li-P2S5-LiCl, LiC2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2SP2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, Li3PS4, Li7P3S 11 , LiI-Li2S-B2S3, Li3PO4-Li2S-SiS2, Li3PO4Li2S-SiS2, LiPO4-Li2S-SiS2, Li 10 GeP2S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and / or Li7P3S 11 can be suitably used. [Brief explanation of the drawings]

[0052] [Figure 1a] The SEM image shows the secondary particles of Example 1, which contain multiple primary particles. The dotted line indicates the area captured to obtain the average primary particle diameter. [Figure 1b] SEM image of Example 1 to obtain the average primary particle diameter. [Figure 1c] SEM image of Example 2 to obtain the average primary particle diameter. [Figure 1d] SEM image of Comparative Example 3.2 to obtain the average primary particle diameter. [Figure 2] 1 shows XPS spectra showing Zr peaks of Examples 1 and 2. DETAILED DESCRIPTION OF THE INVENTION

[0053] To enable the practice of the invention, preferred embodiments are described in the drawings and the following detailed description. While the invention has been described with reference to these particular preferred embodiments, it will be understood that the invention is not limited to these preferred embodiments. The invention includes numerous alternatives, modifications, and equivalents that will be apparent from consideration of the following detailed description and the accompanying drawings.

[0054] A) ICP analysis The amounts of Li, Ni, Mn, Co, and Zr in the positive electrode active material powder were measured using an inductively coupled plasma (ICP) method using an Agilent ICP 720-ES (Agilent Technologies, https: / / www.agilent.com / cs / library / brochures / 5990-6497EN%20720-725_ICP-OES_LR.pdf). Two grams of powder sample were dissolved in 10 mL of high-purity hydrochloric acid (at least 37 wt% HCl based on the total weight of the solution) in an Erlenmeyer flask. The flask was covered with glass and heated on a hot plate at 380 °C until the precursor was completely dissolved. After cooling to room temperature, the solution in the Erlenmeyer flask was poured into a 250 mL volumetric flask. The volumetric flask was then filled with deionized water up to the 250 mL mark, followed by thorough homogenization. Pipette an appropriate amount of the solution into a 250 mL volumetric flask for the second dilution, fill the volumetric flask up to the 250 mL mark with the internal standard and 10% hydrochloric acid, then homogenize. Finally, use this 50 mL solution for ICP measurement.

[0055] B) SEM (scanning electron microscope) analysis The morphology of the positive electrode active material is analyzed by scanning electron microscopy (SEM) using a JEOL JSM 7100F (https: / / www.jeolbenelux.com / JEOL-BV-News / jsm-7100f-thermal-field-emission-electron-microscope) at 25 °C with a resolution of 9.6 × 10 -5 The process is carried out in a high vacuum environment of 100 Pa.

[0056] C) Particle size C1) Secondary particle size analysis The particle size distribution (PSD) of the cathode active material powders was measured by laser diffraction particle size analysis using a Malvern Mastersizer 3000 equipped with a Hydro MV wet dispersion accessory (https: / / www.malvernpanalytical.com / en / products / product-range / mastersizer-range / mastersizer-3000#overview) after dispersing each powder sample in aqueous media. Sufficient ultrasonic irradiation and stirring were applied and appropriate surfactants were introduced to improve powder dispersion. D50 was defined as the particle size at 50% of the cumulative volume percent distribution obtained from the Malvern Mastersizer 3000 using Hydro MV measurements.

[0057] C2) Primary particle size analysis The diameter of the primary particles is calculated by using ImageJ software (ImageJ 1.52a, National Institutes of Health, USA) according to the following steps.

[0058] Step 1) Open a file containing an SEM image of the cathode active material taken at 10,000x magnification, taken at the center of a secondary particle. An example of such an image is shown in Figure 1a, where the dotted line indicates the captured area corresponding to Figure 1b.

[0059] Step 2) Set the scale according to the SEM magnification.

[0060] Step 3) For at least 50 particles, use the polygon selection tool to draw lines along the edges of the primary particles. Particles at the edge of the image are excluded if they are truncated.

[0061] Step 4) Measure the area of the selected, drawn primary particle using the measurement settings and area box.

[0062] Step 5) By assuming the particles to be spherical,

[0063]

number

[0064] Calculate the particle diameter from each measured area according to The average primary particle diameter is obtained for at least 50 particles.

[0065] D) X-ray photoelectron spectroscopy In the present invention, X-ray photoelectron spectroscopy (XPS) is used to analyze the surface of positive electrode active material powder particles. In XPS measurements, signals are acquired from the top of the sample, i.e., the first few nanometers (e.g., 1 nm to 10 nm) of the surface layer. Therefore, all elements measured by XPS are contained in the surface layer.

[0066] For the surface analysis of the positive electrode active material powder particles, XPS measurements are performed using a Thermo K-α+ spectrometer (Thermo Scientific, https: / / www.thermofisher.com / order / catalog / product / IQLAADGAAFFACVMAHV).

[0067] Monochromatic Al Kα radiation (hυ = 1486.6 eV) is used with a spot size of 400 μm and a measurement angle of 45°. An extensive survey scan to identify the elements present on the surface is performed with a pass energy of 200 eV. The C1s peak with maximum intensity (or center) at a binding energy of 284.8 eV is used as the calibration peak position after data collection.

[0068] Then, for each identified element, at least 10 precise narrow scans at 50 eV are performed to determine the exact surface composition.

[0069] Curve fitting was performed using CasaXPS version 2.3.19PR1.0 (Casa Software, http: / / www.casaxps.com / ) using Shirley-type background processing and Scofield sensitivity coefficients. Fitting parameters are according to Table 1a. The line shape GL(30) is a Gaussian / Lorentzian product formula with a 70% Gaussian line and a 30% Lorentzian line. LA(α,β,m) is the asymmetric line shape, where α and β define the tail broadening of the peak and m defines the width.

[0070] [Table 1]

[0071] For Zr and Co peaks, limits are set for the peaks defined respectively according to Table 1b.

[0072] [Table 2]

[0073] The surface content of Zr determined by XPS is expressed as the mole fraction of Zr in the surface layer of a particle divided by the total content of Ni, Mn, Co and Zr in that surface layer, which is calculated as follows:

[0074]

number

[0075] E) Sulfide solid-state battery testing E1) Preparation of sulfide solid-state battery Preparation of the positive electrode: To prepare the positive electrode, a slurry containing the positive electrode active material powder, Li-PS solid electrolyte, carbon (Super-P, Timcal), and binder (RC-10, Arkema) in a weight ratio of 64.0:30.0:3.0:3.0 in butyl acetate solvent was mixed in an Ar-filled glove box. The slurry was cast onto one side of an aluminum foil, and the coated foil was then dried in a vacuum oven to obtain the positive electrode.

[0076] The obtained positive electrode was punched to a diameter of 10 nm, and the amount of the active material carried was approximately 4 mg / cm 2 is.

[0077] Preparation of the negative electrode: To prepare the negative electrode, a Li foil (3 mm diameter, 100 μm thickness) is placed centered on an In foil (10 nm diameter, 100 μm thickness) and pressed to form a Li-In alloy negative electrode.

[0078] Separator For the preparation of a separator that also functions as a solid electrolyte in a battery, the Li-PS-based solid electrolyte is pelletized under a pressure of 250 MPa to obtain a pellet thickness of 100 μm.

[0079] Cell assembly The sulfide solid-state battery was assembled in an argon-filled glove box from bottom to top: cathode with Al current collector with a coated portion on top, separator, anode with Li side up, and Cu current collector. The stacked components were pressed together at a pressure of 250 MPa and placed in an external cage to prevent air exposure.

[0080] E2) Test method The test method is a conventional "constant cut-off voltage" test. Conventional cell testing of the present invention follows the schedule shown in Table 2. Each cell is cycled at 60°C using a Toscat-3100 computer-controlled galvanostatic cycling station (manufactured by Toyo). This schedule uses a 1C current definition of 160mA / g. The initial charge capacity (CQ1) and discharge capacity (DQ1) are measured in constant current mode (CC) at a C-rate of 0.1C over the following voltage ranges: -For Comparative Example 1, Example 1, Comparative Example 2, and Example 2, 4.3V to 2.5V (Li / Li + ) or 3.7V~1.9V(InLi / Li + ). For Comparative Examples 3.1 and 3.2, 4.2V to 2.5V (Li / Li+) or 3.6V to 1.9V (InLi / Li+).

[0081] The irreversible capacity IRRQ is expressed as a percentage as follows:

[0082]

number

[0083] [Table 3]

[0084] F) Carbon analyzer The carbon content of the positive electrode active material powder is measured using a Horiba Emia-Expert carbon / sulfur analyzer. 1 g of hNMC powder is placed in a ceramic crucible in a high-frequency induction furnace. 1.5 g of tungsten and 0.3 g of tin as promoters are added to the crucible. The powder is heated at a programmable temperature, and the gases produced during combustion are then analyzed by an infrared detector. The carbon concentration is determined by CO2 and CO2 analysis.

[0085] The invention is further illustrated by the following (non-limiting) examples.

[0086] Comparative Example 1 Comparative Example 1 is obtained by a solid-state reaction between a lithium source and a transition metal-based source, which is carried out as follows. 1) Coprecipitation: The metal composition Ni was obtained by a coprecipitation process in a large continuous stirred tank reactor (CSTR) containing mixed nickel-manganese-cobalt sulfate, sodium hydroxide, and ammonia. 0.83 Mn 0.12 Co 0.05 A transition metal-based oxide hydroxide precursor having the formula: 2) First mixing: The transition metal-based oxide hydroxide precursor and LiOH as the lithium source are homogeneously mixed in an industrial blending device with a lithium to metal M′ (Li / M′) ratio of 0.96 to obtain a mixture. 3) First heating: The mixture from step 2) is heated under an oxygen atmosphere at 765°C for 10 hours. The heated powder is crushed, classified and sieved to obtain an intermediate product. 4) Second mixing: The heated powder from step 3) and LiOH as the lithium source are homogeneously mixed in an industrial blending device with a lithium to metal M′ (Li / M′) ratio of 1.02 to obtain a mixture. 5) Second heating: The mixture from step 4) is heated at 770°C for 10 hours under oxygen atmosphere to obtain Comparative Example 1 having M' containing Ni, Mn and Co with a Ni:Mn:Co ratio of 0.829:0.120:0.050 obtained by ICP. Comparative Example 1 has a D50 of 6µm.

[0087] Optionally, a dopant source can be added together with the lithium source during the co-precipitation process in step 1) or the mixing process in step 2) or step 4). For example, certain elements can be added as dopants to improve the electrochemical properties of the positive electrode active material.

[0088] Example 1 Example 1 is obtained by the following steps:

[0089] 1) Wet mixing: Zr is introduced into the positive electrode active material by applying the following steps 1a) to 1c).

[0090] Step 1a) Preparation of Zr solution: 0.5 mol% of Zr from Zr propoxide (70 wt% Zr propoxide in n-propanol solution), 1.0 mol% of Li ethoxide powder, and ethanol solvent, each based on the total molar content of Ni, Mn, and Co in the intermediate product, are mixed to form a solution. The amount of ethanol solvent is 55 wt% of the total weight of the designated Comparative Example 1 to be mixed in Step 1b).

[0091] Step 1b) Mixing: Comparative Example 1 is mixed with the Zr solution prepared in step 1a) in a heatable reactor for 20 minutes.

[0092] Step 1c) Heating: Heat of 70°C is applied to the reactor of step 1b) while the reactor is connected to a vacuum pump to evaporate the volatile phase. The product obtained from this step is a dry powder.

[0093] 5) Heating: The dried powder from step 1c) is heated at 350°C for 6 hours under oxygen atmosphere to obtain Example 1 having M' containing Ni, Mn, Co and Zr with Ni:Mn:Co:Zr ratio obtained by ICP of 0.825:0.120:0.050:0.005. Example 1 has a D50 of 6 μm.

[0094] Comparative Example 2 Comparative Example 2 is obtained by the same procedure as Comparative Example 1, except that the second heating temperature in step 3) is 730°C.

[0095] Example 2 Example 2 is obtained by the same procedure as Example 1, except that Comparative Example 2 is used instead of Comparative Example 1.

[0096] Comparative Example 3 Comparative Example 3.1 is obtained by solid state reaction between a lithium source and a transition metal based source, which is carried out as follows.

[0097] 1) Coprecipitation: A coprecipitation process in a large continuous stirred tank reactor (CSTR) containing mixed nickel-manganese-cobalt sulfate, sodium hydroxide, and ammonia produces the metal composition Ni 0.64 Mn 0.17 Co 0.20 A transition metal-based oxide hydroxide precursor having the formula:

[0098] 2) Mixing: The transition metal-based oxide hydroxide precursor and LiOH as the lithium source are homogeneously mixed in an industrial blending device at a lithium to metal M' (Li / M') ratio of 1.03 to obtain a mixture.

[0099] 3) First heating: The mixture from step 2) is heated under an oxygen atmosphere at 860°C for 10 hours. The heated powder is crushed, classified and sieved to obtain an intermediate product.

[0100] 4) Second heating: The intermediate product from step 3) is heated at 350°C for 6 hours under oxygen atmosphere to obtain Comparative Example 3.1 having M' containing Ni, Mn and Co with Ni:Mn:Co ratio obtained by ICP of 0.638:0.165:0.197. Comparative Example 3.1 has a D50 of 10µm.

[0101] Comparative Example 3.2 is obtained by solid state reaction between a lithium source and a transition metal based source, which is carried out as follows.

[0102] 1) Coprecipitation: A coprecipitation process in a large continuous stirred tank reactor (CSTR) containing mixed nickel-manganese-cobalt sulfate, sodium hydroxide, and ammonia produces the metal composition Ni 0.64 Mn 0.17 Co 0.20 A transition metal-based oxide hydroxide precursor having the formula:

[0103] 2) Mixing: The transition metal-based oxide hydroxide precursor and LiOH as the lithium source are homogeneously mixed in an industrial blending device at a lithium to metal M' (Li / M') ratio of 1.03 to obtain a mixture.

[0104] 3) First heating: The mixture from step 2) is heated under an oxygen atmosphere at 860°C for 10 hours. The heated powder is crushed, classified and sieved to obtain an intermediate product.

[0105] 4) Wet mixing: Zr is introduced into the positive electrode active material by applying the following steps 4a) to 4c).

[0106] Step 4a) Preparation of Zr solution: 0.6 mol% of Zr from Zr propoxide (70 wt% Zr propoxide in n-propanol solution), 1.2 mol% of Li ethoxide powder, and ethanol solvent are mixed to form a solution, each based on the total molar content of Ni, Mn, and Co in the intermediate product. The amount of ethanol solvent is 55 wt% of the total weight of the designated intermediate product to be mixed in step 4b).

[0107] Step 4b) Mixing: The intermediate product obtained from step 3) is mixed with the Zr solution prepared in step 4a) in a heatable reactor for 20 minutes.

[0108] Step 4c) Heating: Heat of 70°C is applied to the reactor of step 4b) while the reactor is connected to a vacuum pump to evaporate the volatile phase. The product obtained from this step is a dry powder.

[0109] 5) Second heating: The dried powder from step 4c) is heated at 350°C for 6 hours under oxygen atmosphere to obtain Comparative Example 3.2 having M' containing Ni, Mn, Co and Zr with a Ni:Mn:Co:Zr ratio of 0.632:0.164:0.198:0.006 obtained by ICP. Comparative Example 3.2 has a D50 of 10 μm.

[0110] Example 3 Example 3 is obtained by the same procedure as Example 1, except that in the preparation of Comparative Example 1, 2500 ppm of Zr is added together with the Li source in the first mixing in step 2), and the second heating temperature in step 5) is 725°C.

[0111] Example 4 Example 4 is obtained by the same procedure as Example 1, except that in the preparation of Comparative Example 1, 2500 ppm of Zr is added together with the Li source in the first mixing in step 2), and the second heating temperature in step 5) is 750°C.

[0112] [Table 4]

[0113] * For the molar contents of Ni, Mn, Co and Zr ** Zr A is 0, so it cannot be applied.

[0114] Table 3 summarizes the primary particle diameters, compositions, and corresponding electrochemical properties of Examples and Comparative Examples. The average primary particle diameter of Comparative Example 1 and Example 1 is 383 nm, which is larger than the average primary particle diameter of Comparative Example 2 and Example 2 (292 nm). Similarly, the average primary particle diameter of Example 4 is larger than that of Example 3, which is related to the higher heating temperature applied in step 5). The positive electrode active materials of Comparative Example 1, Example 1, Comparative Example 2, Example 2, Example 3, and Example 4 contain approximately 83 mol% Ni. Comparative Examples 3.1 and 3.2, which have a Ni content of approximately 64 mol%, have an average primary particle diameter of 371 nm. SEM images of primary particles of Example 1, Example 2, and Comparative Example 3.2 are shown in Figures 1b, 1c, and 1d, respectively. The images include lines drawn to identify primary particles and numbers to obtain the average primary particle diameter.

[0115] In Table 3, the XPS analysis results for Example 1, Example 2, Comparative Example 3.2, Example 3, and Example 4 show that Ni, Mn, Co, and Zr (Zr B The table also compares the results with those of ICP. B indicates that the Zr is present on the surface of the positive electrode active material, in relation to the XPS measurement, where the signal is obtained from the top of the sample, i.e., the first few nanometers (e.g., 1 nm to 10 nm) of the surface layer. On the other hand, the atomic ratio of Zr obtained from the ICP measurement (ZrA ) is from the whole particle. Therefore, the ratio of XPS to ICP (Zr B / Zr A ) indicates that the element Zr is present mainly on the surface of the positive electrode active material. B / Zr A The Zr values in Example 1, Example 2, Comparative Example 3.2, Example 3, and Example 4 correspond to the presence of more Zr on the surface of the positive electrode active material. B / Zr A are all greater than 50, confirming the effectiveness of the Zr treatment according to the present invention. Representative XPS spectra showing the Zr 3d5 and 3d3 peaks of Examples 1 and 2 are shown in FIG.

[0116] The carbon content in the positive electrode active material after Zr treatment was higher than that before treatment, which is related to the better electrochemical performance of the active material. The carbon comes from the Zr alkoxide compound used in the treatment.

[0117] In a positive electrode active material having a Ni content of at least 70 mol%, primary particles having an average diameter of at least 250 nm and Zr greater than 50.0 B / Zr A can achieve the object of the present invention to provide a positive electrode active material having an improved first charge capacity of at least 160 mAh / g in a solid-state battery.

Claims

1. A cathode active material for a solid-state battery, the cathode active material comprising Li, M′, and oxygen, wherein M′ is Ni with a content x of 70.0 mol% to 95.0 mol% relative to M', Co with a content y of 0.0 mol % to 40.0 mol % relative to M', Mn with a content z of 0.0 mol % to 40.0 mol % relative to M', D having a content a of 0.0 mol % to 2.0 mol % relative to M', and containing at least one element selected from the group consisting of Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, W and Zn; Zr having a content b of 0.1 mol% to 5.0 mol% relative to M'; x, y, z, a and b are measured by ICP; x+y+z+a+b is 100.0 mol%, The positive electrode active material is [Equation 1] Zr content defined as Zr Ａ and The positive electrode active material has a Zr content of Zr Ｂ and Zr Ｂ is determined by XPS analysis, Zr Ｂ is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni and Zr as determined by XPS analysis, Ratio Zr Ｂ / Zr Ａ is 100 or more and 200 or less, the positive electrode active material includes secondary particles having a plurality of primary particles, the primary particles have an average diameter of at least 250 nm as determined by measuring the primary particle size in an image taken by SEM.

2. 10. The cathode active material of claim 1, wherein the primary particles have an average diameter of at least 300 nm.

3. The ratio Zr Ｂ / Zr Ａ 3. The cathode active material of claim 1, wherein the σ is at least 120, or at least 130.

4. The ratio Zr Ｂ / Zr Ａ The positive electrode active material according to claim 1 or 2, wherein R is at most 161.

6.

5. The positive electrode active material according to any one of claims 1 to 4, wherein x≧77.0 mol%, or x>81.0 mol%.

6. The positive electrode active material according to any one of claims 1 to 5, wherein x≦91.0 mol%.

7. The positive electrode active material according to any one of claims 1 to 6, wherein 0 mol%≦y≦20 mol%.

8. The positive electrode active material according to any one of claims 1 to 7, wherein 5.0 mol%≦z≦30.0 mol%.

9. 9. The positive electrode active material according to claim 1, wherein b / (b+x+y+z) is at least 0.10 mol% and at most 1.00 mol%.

10. 10. The cathode active material of claim 1, wherein the secondary particle median diameter D50 is at least 2.0 μm and at most 15.0 μm as determined by laser diffraction particle size analysis.

11. 11. The cathode active material of claim 1, wherein the carbon content is at least 600 ppm and at most 8000 ppm as determined by a carbon analyzer.

12. A method for producing a positive electrode active material for a solid-state battery, wherein the positive electrode active material is the positive electrode active material according to any one of claims 1 to 11, and the method comprises the steps of: preparing a lithium transition metal oxide compound; Mixing the lithium transition metal oxide compound with a Zr source or a Zr alkoxide in a lithium alkoxide-containing alcohol solvent, thereby obtaining a mixture; and heating the mixture in an oxidizing atmosphere in a furnace at a temperature of 350°C or higher but lower than 500°C, or at most 450°C, for a time period of 1 hour to 20 hours to obtain the cathode active material powder according to the present invention.

13. 13. The method of claim 12, comprising the further step of drying the mixture before heating the mixture.

14. 13. The method of claim 12, comprising the further step of drying the mixture by vacuum heating before heating the mixture.

15. A solid-state battery comprising the positive electrode active material according to any one of claims 1 to 11.

16. 16. The solid-state battery of claim 15, comprising a sulfide-based solid electrolyte containing Li, P, and S.

17. 17. Use of a battery according to claim 15 or 16 in an electric vehicle or a hybrid electric vehicle.

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