Lithium nickel-based complex oxides as positive electrode active materials for rechargeable lithium-ion batteries

Abstract

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

Description

[0001] Technical Field and Background Technology

[0002] This invention relates to lithium nickel-based oxide positive electrode active materials for solid-state batteries suitable for electric vehicle (EV) and hybrid electric vehicle (HEV) applications, wherein the positive electrode active material comprises lithium nickel-based oxide particles containing zirconium (Zr).

[0003] Positive electrode active materials are defined as materials that are electrochemically active in a positive electrode. For active materials, it is essential to understand their ability to capture and release lithium ions when subjected to voltage changes over a predetermined time period.

[0004] In the framework of this invention, at% represents atomic percentage. At% or “atomic percentage” in a given elemental expression of concentration means what percentage of all atoms in the claimed compound are atoms of the element. Specifying “at%” is equivalent to the term “mol%” or “molar percentage”.

[0005] The weight percentage (wt%) of the first element E in the material (E) wt1 The first element E in the material can be determined by applying the following formula: given atomic percentage (at%) (E) at1 Conversion: Where E at1 With E aw1 (E aw1 It is the product of the atomic weight (or molecular weight) of the first element E and the atomic weights (or molecular weights) of the other elements in the material. ati ×E awi The sum, where n is an integer representing the number of different elements contained in the material.

[0006] The purpose of this invention is to provide a positive electrode active material for a solid-state battery having an improved initial charge capacity of at least 160 mAh / g. Summary of the Invention

[0007] This objective is achieved by providing a positive electrode active material for solid-state batteries, wherein the positive electrode active material comprises Li, M', and oxygen, wherein M' comprises:

[0008] -Ni, the content of which x is between 70.0 mol% and 95.0 mol% relative to M';

[0009] -Co, the content of which is y relative to M' is between 0.0 mol% and 40.0 mol%;

[0010] -Mn, the content of which z is between 0.0 mol% and 40.0 mol% relative to M',

[0011] -D, the content of which is between 0.0 mol% and 2.0 mol% relative to the total atomic content of M', wherein D comprises 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, and

[0012] -Zr, with a content b relative to M' between 0.1 mol% and 5.0 mol%, wherein x, y, z, a, and b were measured by ICP.

[0013] -where x+y+z+a+b is 100.0 mol%.

[0014] The positive electrode active material has a Zr content as defined below. A : The positive electrode active material has a Zr content. B Zr B It was determined through XPS analysis, where Zr B Mole fraction expressed as a comparison with the sum of the mole fractions of Co, Mn, Ni, and Zr as measured by XPS analysis.

[0015] The ratio Zr B / Zr A >50.0,

[0016] The positive electrode active material described herein comprises secondary particles having a plurality of primary particles.

[0017] The primary particles described therein have an average diameter of at least 250 nm, as determined by measuring the size of the primary particles in an image captured by SEM.

[0018] This invention relates to the following embodiments:

[0019] Implementation Plan 1

[0020] In a first aspect, the present invention relates to a positive electrode active material for a solid-state battery, wherein the positive electrode active material comprises Li, M' and oxygen, wherein M' comprises:

[0021] -Ni, wherein the content x relative to M' is between 70.0 mol% and 95.0 mol%, preferably Ni, wherein the content x relative to M' is between 75.0 mol% and 95.0 mol%.

[0022] -Co, the content of which is y relative to M' is between 0.0 mol% and 40.0 mol%.

[0023] -Mn, the content of which z is between 0.0 mol% and 70.0 mol% relative to M', preferably Mn, the content of which z is between 0.0 mol% and 40.0 mol% relative to M',

[0024] -D, the content of which is between 0.0 mol% and 2.0 mol% relative to the total atomic content of M', wherein D comprises 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, and

[0025] -Zr, the content of which b is between 0.1 mol% and 5.0 mol% relative to M',

[0026] -Where x, y, z, a, and b are measured via ICP.

[0027] -where x+y+z+a+b is 100.0 mol%.

[0028] The positive electrode active material has the Zr content defined as follows. The positive electrode active material has a Zr content. B Zr B It was determined through XPS analysis, where Zr B Mole fraction expressed as a comparison with the sum of the mole fractions of Co, Mn, Ni, and Zr as measured by XPS analysis.

[0029] The ratio Zr B / Zr A >50.0.

[0030] Note that Zr A It is the Zr content of the positive electrode active material as determined by ICP, and is expressed as a percentage relative to the sum of the contents of Co, Ni, Mn and Zr.

[0031] 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.

[0032] Preferably, the positive electrode active material comprises secondary particles having a plurality of primary particles, wherein said primary particles have an average diameter of at least 200 nm, as determined by measuring the size of the primary particles in an image taken by SEM.

[0033] 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.

[0034] Preferably, the primary particles have an average diameter of up to 1000 nm, more preferably up to 600 nm, and more preferably up to 500 nm.

[0035] Preferably, the primary particles have an average diameter between 250 nm and 1000 nm, more preferably between 300 nm and 600 nm, and even more preferably between 350 nm and 500 nm.

[0036] Preferably, x ≥ 77.0 mol%, and more preferably x ≥ 80.0 mol%, and even more preferably x > 81.0 mol%.

[0037] Preferably, x ≤ 91.0 mol%, and more preferably x ≤ 90.0 mol%.

[0038] Preferably, y > 0 mol%, and more preferably y ≥ 5.0 mol%, and even more preferably y ≥ 9.0 mol%.

[0039] In another embodiment, the Ni content x is between 77 mol% and 90 mol% relative to M' and the Co content y is between 0.0 mol% and 20.0 mol% relative to M'.

[0040] In a preferred embodiment, the Ni content 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%, and more preferably x ≤ 88.0 mol%. A more preferred embodiment is the positive electrode active material of the present invention, wherein 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%.

[0041] As those skilled in the art will understand, the amounts of Li and M' in the positive electrode active material, preferably the amounts of Li, Ni, Mn, Co, D, and Zr, are measured using inductively coupled plasma optical emission spectrometry (ICP-OES). For example, not limited to this invention, an Agilent ICP 720-ES is used in ICP-OES analysis.

[0042] In a preferred embodiment, the content z of Mn is > 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%.

[0043] In a preferred embodiment, the content y of Co is > 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%.

[0044] In a preferred embodiment, D comprises 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; preferably Al, B, Cr, Nb, S, Si, Ti, Y, and W.

[0045] In a preferred embodiment, the content a of D is > 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%.

[0046] As will be understood by those skilled in the art, the secondary particles comprise 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. The primary particles are particles formed as a single crystal or by fewer than five and preferably at most three primary particles each being a single crystal. This can be observed by observing grain boundaries in suitable microscopy techniques such as scanning electron microscopy (SEM).

[0047] Embodiment 2

[0048] In the second embodiment, preferably according to embodiment 1, the Zr content is Zr A The Zr content is b(b+x+y+z), which is at least 0.10 mol% and at most 1.00 mol%. Preferably, the Zr content is... A The Zr content is b / (b+x+y+z), which is at least 0.20 mol% and at most 0.80 mol%. Most preferably, the Zr content is... A The value is b / (b+x+y+z), which is at least 0.30 mol% and at most 0.70 mol%. In alternative but even preferred embodiments, the Zr content is... A The value is b / (b+x+y+z), which is at least 0.10 mol% and at most 1.50 mol%. Preferably, the Zr content is... A The value is b / (b+x+y+z), which is at least 0.20 mol% and at most 1.00 mol%. Most preferably, the Zr content is [missing value]. A It is b / (b+x+y+z), which is at least 0.30 mol% and at most 0.90 mol%.

[0049] In a preferred embodiment, the Zr content b is 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'.

[0050] In alternative but even preferred embodiments, the Zr content b is 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'.

[0051] In the preferred embodiment, the Zr content is Zr B Greater than 0.25 mol%, preferably greater than 0.50 mol%, most preferably greater than 0.60 mol%. In the preferred embodiment, Zr B Less than 2.0 mol%, preferably less than 1.5 mol%, more preferably less than 1.0 mol%. In a preferred embodiment, Zr B The concentration is between 0.25 mol% and 2.0 mol%, preferably between 0.50 mol% and 1.5 mol%, and most preferably between 0.60 mol% and 1.0 mol%. As those skilled in the art will understand, Zr... B Mole fraction expressed as the sum of the mole fractions of Co, Mn, Ni, and Zr measured by XPS analysis compared to the sum of the mole fractions of Co, Mn, Ni, and Zr measured by XPS analysis.

[0052] Implementation Plan 3

[0053] In the third embodiment, according to embodiments 1 to 2, the material has a secondary particle median size D50 of at least 2 pm, and preferably at least 3 pm, as determined by laser diffraction particle size analysis.

[0054] Preferably, the material has a secondary particle median size D50 of up to 15 μm, and more preferably up to 10 μm, as determined by laser diffraction particle size analysis.

[0055] For example, but not limited to this invention, laser diffraction particle size analysis is performed using a Malvern Mastersizer 3000.

[0056] Implementation Plan 4

[0057] In the 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 ppm, and most preferably at least 900 ppm, as determined by a carbon analyzer.

[0058] Preferably, the material has a carbon content of up to 8000 ppm, more preferably up to 7500 ppm, more preferably up to 5000 ppm, and most preferably up to 2000 ppm, as determined by a carbon analyzer.

[0059] As those skilled in the art will understand, for any of implementation schemes 1 to 4, Zr B The mole fraction is expressed as the sum of the mole fractions of Co, Mn, Ni, and Zr measured by XPS analysis, with particular emphasis on Zr. B It is the mole fraction of Zr, which is measured in a region of the secondary particles of the positive electrode active material according to the invention, the region being defined between a first point at the outer edge of the particles and a second point at a distance from the first point, the distance separating the first point and the second point being equal to the penetration depth of the XPS, the penetration depth D being included between 1.0 nm and 10.0 nm. Specifically, the penetration depth is the distance along an axis perpendicular to an axis tangent to the outer edge and passing through the first point.

[0060] In the framework of this invention, the outer edge of a particle is the boundary or external limit that distinguishes the particle from its external environment.

[0061] Therefore, XPS analysis provides the atomic content of the element in the uppermost layer of the particle, where the penetration depth from the outer boundary of the particle is approximately 10.0 nm. The outer boundary of the particle is also referred to as the “surface.” Within the framework of this invention, at% represents the atomic percentage. The at% or “atomic percentage” in a given elemental expression of concentration refers to what percentage of all atoms in the compound in question are atoms of the element. Specifying “at%” is equivalent to the term “mol%” or “molar percentage.” For example, but not limited to this invention, XPS analysis is performed using a Thermo K-a+ spectrometer (Thermo Scientific).

[0062] The present invention relates to the use of the positive electrode active material according to any one of the foregoing embodiments 1 to 4 in a battery.

[0063] The present invention also includes a method for manufacturing a positive electrode active material according to any one of embodiments 1 to 4, the method comprising the following steps:

[0064] -Preparation of lithium transition metal-based compounds

[0065] - The lithium transition metal-based compound is mixed with a Zr source, preferably a Zr alkoxide, in an alcohol solvent containing lithium alkoxide to obtain a mixture, and

[0066] - Removal of volatile phases, including solvents, preferably by vacuum heating.

[0067] - The mixture is heated in an oxidizing atmosphere in a furnace at a temperature of 350°C to less than 500°C, preferably up to 450°C, for a period of 1 hour to 20 hours in order to obtain the positive electrode active material powder according to the invention.

[0068] In a preferred embodiment, the lithium transition metal-based compound is a lithium nickel-based oxide compound.

[0069] In a preferred embodiment of the method, the lithium transition metal-based oxide compound comprises Li, M' and oxygen, wherein M' includes Ni, Mn, Co and D, and D is 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, W.

[0070] Preferably, the lithium transition metal oxide powder used is also typically prepared according to a lithiation method, i.e., a method in which a mixture of a transition metal precursor and a lithium source is heated at a temperature preferably at least 500°C. Typically, the transition metal precursor is prepared by co-precipitation of one or more transition metal sources (such as salts, and preferably sulfates of elements M', Ni, Mn, and / or Co) in the presence of a basic compound (such as alkali metal hydroxides, for example, sodium hydroxide and / or ammonia).

[0071] Preferably, the method further includes an additional step of drying the mixture before heating it, preferably by vacuum heating.

[0072] In a preferred embodiment of the method, the Zr source is a Zr-alkoxide, preferably a Zr-ethanol, Zr-propanol, or Zr-butanol, more preferably a Zr-propanol. In a preferred embodiment, the Zr-alkoxide is mixed as a solid with the mixture. Alternatively and more preferably, the Zr-alkoxide is mixed as a solution with the slurry, wherein the solution comprises the Zr-alkoxide and an additional alcohol, wherein the alkoxide group is the conjugate base of the additional alcohol. For example, the Zr-alkoxide is a Zr-propanol dissolved in propanol. Typically, the solution contains 50% to 90% by weight of Zr-alkoxide based on the total weight of the solution. Examples of such solutions are 70% by weight of Zr-propanol in 1-propanol or 80% by weight of Zr-butanol in 1-butanol.

[0073] Preferably, the alcohol solvent is methanol, ethanol, propanol or butanol, with ethanol being the most preferred.

[0074] The present invention also includes a solid-state battery comprising the positive electrode active material according to any one of embodiments 1 to 4 above, preferably, the solid-state battery comprising a sulfide-based solid electrolyte, more preferably, the sulfide-based solid electrolyte comprising Li, P and S. Typically, the following sulfur-containing compounds may be suitably used: U6PS5Cl (LPSCL), thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCI, LiC2S-SiS2, LiI-Li2S-SiS2, Li-P2S5-LiCI, LiC2S-SiS2, LiI-Li2S-SiS2, LiI-Li2S-P2S5, LiI-Li2SP2O5, LiI-Li3PO 4- P2S5, Li2S-P2S5, Li3PS4, Li7P3S 11 , LiI-Li2S-B2S3, Li3PO4-Li2S-SiS2, Li3PO4Li2S-SiS2, LiPO4-Li2S-SiS2, Li10 GeP2S 12 Li 9.54 Si 1.74 P 1.44 S 11.7 CI 0.3 and / or Li7P3S 11 . Attached Figure Description

[0075] Figure 1a. SEM image showing secondary particles containing multiple primary particles of EX1. Dashed lines indicate the area to be captured to obtain the average primary particle diameter.

[0076] Figure 1b.EX1 shows the SEM image to obtain the average primary particle diameter.

[0077] Figure lc.EX2 shows the SEM image to obtain the average primary particle diameter.

[0078] Figure Id. CEX3.2 shows the SEM image to obtain the average primary particle diameter.

[0079] Figure 2 XPS spectra show Zr peaks in EX1 and EX2. Detailed Implementation

[0080] Preferred embodiments have been described in detail in the accompanying drawings and the following detailed description to enable practice of the invention. Although the invention has been described with reference to these specific preferred embodiments, it should be understood that the invention is not limited to these preferred embodiments. The invention includes many alternatives, modifications, and equivalents, which will become apparent from the following detailed description and drawings.

[0081] A) ICP analysis

[0082] The amounts of Li, Ni, Mn, Co, and Zr in the positive electrode active material powder were measured by inductively coupled plasma (ICP) 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 the powder sample were dissolved in 10 mL of high-purity hydrochloric acid (at least 37% by weight HCl relative to the total weight of the solution) in an Erlenmeyer flask. The flask was covered with a glass slide 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 to the 250 mL mark and completely homogenized. Take an appropriate amount of solution using a pipette and transfer it to a 250 mL volumetric flask for a second dilution. Fill the flask with internal standard and 10% hydrochloric acid up to the 250 mL mark, then homogenize. Finally, use this 50 mL solution for ICP measurement.

[0083] B) SEM (Scanning Electron Microscopy) Analysis

[0084] The morphology of the positive electrode active material was analyzed using scanning electron microscopy (SEM). A JEOL JSM7100F microscope (https: / / www.jeolbenelux.com / JEOL-BV-News / jsm-7100f-thermal-field-emission-electron-microscope) at 9.6 x 10⁻⁶ mm was used. -5 The measurements were performed at 25°C under a high vacuum environment.

[0085] C) Particle size

[0086] Cl) Secondary particle size analysis

[0087] After dispersing each powder sample in an aqueous medium, the particle size distribution (PSD) of the positive electrode active material powder was measured by laser diffraction particle size analysis using a Malvern Mastersizer 3000 with a Hydro MV wet dispersion attachment (https: / / www.malvernpanalytical.com / en / products / product-range / mastersizer-range / mastersizer-3000#overview). To improve powder dispersibility, sufficient ultrasonic irradiation and stirring were applied, and a suitable surfactant was introduced. D50 was defined as the particle size at 50% of the cumulative volume % distribution obtained from the Malvern Mastersizer 3000 with Hydro MV.

[0088] C2) Primary Particle Size Analysis

[0089] The diameter of the primary particle was calculated using ImageJ software (ImageJ 1.52a, National Institutes of Health, USA) according to the following steps:

[0090] Step 1) Open the file containing a SEM image of the positive electrode active material magnified 10,000 times, where the image was taken at the center of the secondary particles. An example of such an image is shown in Figure 1a, where the dashed lines indicate the corresponding... Figure 1b The area to be captured.

[0091] Step 2) Set the scale according to the SEM magnification.

[0092] Step 3) For at least 50 particles, use the polygon selection tool to draw lines after the edges of the primary particles. If truncated, exclude particles at the edges of the image.

[0093] Step 4) Measure the area of ​​the stretched primary particle selected from the Set Measurements and Area box.

[0094] Step 5) Calculate the particle size of each measurement region as follows, assuming the particles are spherical. And obtain the average primary particle diameter of at least 50 particles.

[0095] D) X-ray photoelectron spectroscopy analysis

[0096] In this invention, X-ray photoelectron spectroscopy (XPS) is used to analyze the surface of the positive electrode active material powder particles. In XPS measurements, signals are acquired from the first few nanometers (e.g., 1 nm to 10 nm) of the uppermost portion of the sample (i.e., the surface layer). Therefore, all elements measured by XPS are contained within the surface layer.

[0097] For surface analysis of the positive electrode active material powder particles, XPS measurements were performed using a Thermo K-a+ spectrometer (ThermoScientific, https: / / www.thermofisher.com / order / catalog / product / IQLAADGAAFFACVMAHV). Monochromatic Al Ka ​​radiation (hu = 1486.6 eV) was used with a spot size of 400 μm and a measurement angle of 45°. Wide-range measurements were performed at a pass energy of 200 eV to identify elements present on the surface. The C1s peak with maximum intensity (or intermediate intensity) at a binding energy of 284.8 eV was used as the calibration peak position after data collection. Subsequently, at least 10 precise narrow-range scans were performed at 50 eV for each identified element to determine the accurate surface composition.

[0098] Curve fitting was performed using CasaXPS 2.3.19PR1.0 (Casa Software, http: / / www.casaxps.com / ) with Shirley-type background processing and Scofield sensitivity factor. The fitting parameters conform to Table 1a. The linear shape GL(30) is a Gaussian / Lorentz product formula with a 70% Gaussian line and a 30% Lorentz line. LA(a,β,m) is an asymmetric linear shape, where a and b define the tail extension of the peak, and m defines the width.

[0099] Table 1a. XPS fitting parameters for Ni2p3, Mn2p3, Co2p3 and Zr3d1.

[0100]

[0101] For the Zr and Co peaks, constraints are set for each defined peak according to Table 1b.

[0102] Table 1b. XPS fitting constraints for peak fitting .

[0103]

[0104] The Zr surface content determined by XPS is expressed as the mole fraction of Zr in the particle's surface layer divided by the total content of Ni, Mn, Co, and Zr in that surface layer. The calculation is as follows:

[0105]

[0106] E) Sulfide Solid-State Battery Testing

[0107] E1) Sulfide solid-state battery fabrication

[0108] Positive electrode preparation :

[0109] To prepare the positive electrode, a slurry containing positive electrode active material powder, a Li-PS-based solid electrolyte, carbon (Super-P, Timcal), and a binder (RC-10, Arkema) was mixed in butyl acetate solvent at a weight ratio of 64.0:30.0:3.0:3.0 in an Ar-filled glove box. The slurry was cast onto one side of an aluminum foil, and then the slurry-coated foil was dried in a vacuum oven to obtain the positive electrode.

[0110] The resulting positive electrode was stamped into a diameter of 10 nm, wherein the active material loading was approximately 4 mg / cm². 2 .

[0111] negative electrode preparation :

[0112] To prepare the negative electrode, a Li foil (3 mm in diameter and 100 μm in thickness) was placed at the center of the top of an In foil (10 nm in diameter and 100 μm in thickness) and pressed to form a Li-In alloy negative electrode.

[0113] partition

[0114] To prepare a separator that also functions as a solid electrolyte in the battery, a Li-PS-based solid electrolyte was granulated at a pressure of 250 MPa to obtain a particle thickness of 100 pm.

[0115] Battery assembly

[0116] The sulfide solid-state battery was assembled in an argon-filled glove box in a bottom-to-top sequence: a positive electrode with an Al current collector on the top, a separator, and a negative electrode with a Cu current collector on the Li side on the top. The stacked components were pressed together under a pressure of 250 MPa and placed in an external cage to prevent air exposure.

[0117] E2) Test Method

[0118] The testing method is the conventional "constant cutoff voltage" test. The conventional battery test in this invention follows the plan shown in Table 2. Each battery was cycled at 60°C using a Toscat-3100 computer-controlled constant current cycling station (from Toyo). A 1C current definition of 160 mA / g was used. Initial charge capacity (CQ1) and discharge capacity (DQ1) were measured at a C-rate of 0.1C in constant current mode (CC) within the following voltage range:

[0119] - For CEX1, EX1, CEX2, and EX2, the voltage ranges from 4.3V to 2.5V (Li / Li + ) or 3.7V to 1.9V (InLi / Li + ).

[0120] - For CEX3.1 and CEX3.2, the voltage range is 4.2V to 2.5V (Li / Li + ) or 3.6V to 1.9V (InLi / Li + ).

[0121] The irreversible capacity IRRQ is expressed as a percentage as follows:

[0122]

[0123] Table 2. Cyclic Plan for Testing Sulfide Solid-State Batteries

[0124]

[0125] F) Carbon analyzer

[0126] The carbon content of the positive electrode active material powder was measured using a Horiba Emia-Expert carbon / sulfur analyzer. One gram of hNMC powder was placed in a ceramic crucible within a high-frequency induction furnace. 1.5 grams of tungsten and 0.3 grams of tin were added to the crucible as promoters. The powder was heated at a programmable temperature, and the gases produced during combustion were then analyzed using an infrared detector. Analysis of CO2 and CO determined the carbon concentration.

[0127] The present invention is further illustrated by the following embodiments:

[0128] Comparative Example 1

[0129] CEX1 is obtained through a solid-state reaction between a lithium source and a transition metal-based source, as follows:

[0130] 1) Coprecipitation: A coprecipitation process is used to prepare a metal with a Ni composition in a large continuous stirred tank reactor (CSTR) containing a mixture of nickel, manganese, and cobalt sulfate, sodium hydroxide, and ammonia. 0.83 Mn 0.12 Co0.05 A transition metal-based oxidized hydroxide precursor.

[0131] 2) First mixing: The transition metal-based oxidized hydroxide precursor and LiOH as a lithium source are uniformly mixed in an industrial blending device at a lithium to metal M' (Li / M') ratio of 0.96 to obtain a mixture.

[0132] 3) First heating: The mixture from step 2) is heated at 765°C for 10 hours in an oxygen atmosphere. The heated powder is crushed, sorted and sieved to obtain the intermediate product.

[0133] 4) Second mixing: The heated powder from step 3) and LiOH as a lithium source are uniformly mixed in an industrial blending apparatus at a lithium to metal M' (Li / M') ratio of 1.02 to obtain a mixture.

[0134] 5) Second heating: The mixture from step 4) is heated at 770°C for 10 hours under an oxygen atmosphere to obtain CEX1 with M' comprising Ni, Mn, and Co in a Ni:Mn:Co ratio of 0.829:0.120:0.050 as obtained by ICP. CEX1 has a D50 of 6 μm.

[0135] Optionally, the source of the dopant may be added together with the lithium source in the co-precipitation process in step 1) or in the mixing step in step 2) or step 4). For example, certain elements may be added as dopant to improve the electrochemical properties of the positive electrode active material.

[0136] Example 1

[0137] Obtain EX1 through the following steps:

[0138] 1) Wet mixing: Apply steps 1a) to 1c) below to introduce Zr into the positive electrode active material.

[0139] Step 1a) Zr solution preparation: 0.5 mol% Zr from Zr-propoxide (a solution of 70 wt% Zr-propoxide in n-propanol), 1.0 mol% lithium ethoxide powder, and ethanol solvent are mixed to form a solution relative to 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 specified CEX1 to be mixed in step 1b).

[0140] Step 1b) Mixing: Mix CEX1 with the Zr solution prepared in step 1a) in a heatable reactor for 20 minutes.

[0141] Step 1c) Heating: Apply heat of 70°C to the reactor from step 1b) while connecting the reactor to a vacuum pump to evaporate the volatile phase. The product obtained from this step is a dry powder.

[0142] 5) Heating: The dried powder from step 1c) is heated at 350°C for 6 hours in an oxygen atmosphere to obtain EX1 with M', M' comprising Ni, Mn, Co and Zr in a Ni:Mn:Co:Zr ratio of 0.825:0.120:0.050:0.005, as obtained by ICP. EX1 has a D50 of 6 pm.

[0143] Comparative Example 2

[0144] CEX2 is obtained using the same procedure as CEX1, except that the second heating temperature in step 3) is 730°C.

[0145] Example 2

[0146] EX2 is obtained using the same procedure as EX1, except that CEX2 is used instead of CEX1.

[0147] Comparative Example 3

[0148] CEX3.1 was obtained through a solid-state reaction between a lithium source and a transition metal-based source, as follows:

[0149] 1) Coprecipitation: A coprecipitation process is used to prepare a metal with a Ni composition in a large continuous stirred tank reactor (CSTR) containing a mixture of nickel, manganese, and cobalt sulfate, sodium hydroxide, and ammonia. 0.64 Mn 0.17 Co 0.20 A transition metal-based oxidized hydroxide precursor.

[0150] 2) Mixing: The transition metal-based oxidized hydroxide precursor and LiOH as a lithium source are uniformly mixed in an industrial blending device at a lithium to metal M' (Li / M') ratio of 1.03 to obtain a mixture.

[0151] 3) First heating: The mixture from step 2) is heated at 860°C for 10 hours in an oxygen atmosphere. The heated powder is crushed, sorted and sieved to obtain the intermediate product.

[0152] 4) Second heating: The intermediate product from step 3) is heated at 350°C for 6 hours under an oxygen atmosphere to obtain CEX3.1 with M' comprising Ni, Mn, and Co in a Ni:Mn:Co ratio of 0.638:0.165:0.197, as obtained by ICP. CEX3.1 has a D50 of 10 μm.

[0153] CEX3.2 was obtained through a solid-state reaction between a lithium source and a transition metal-based source, as follows:

[0154] 1) Coprecipitation: A coprecipitation process is used to prepare a metal with a Ni composition in a large continuous stirred tank reactor (CSTR) containing a mixture of nickel, manganese, and cobalt sulfate, sodium hydroxide, and ammonia. 0.64 Mn 0.17 Co 0.20 A transition metal-based oxidized hydroxide precursor.

[0155] 2) Mixing: The transition metal-based oxidized hydroxide precursor and LiOH as a lithium source are uniformly mixed in an industrial blending device at a lithium to metal M' (Li / M') ratio of 1.03 to obtain a mixture.

[0156] 3) First heating: The mixture from step 2) is heated at 860°C for 10 hours in an oxygen atmosphere. The heated powder is crushed, sorted and sieved to obtain the intermediate product.

[0157] 4) Wet mixing: Apply steps 4a) through 4c) below to introduce Zr into the positive electrode active material.

[0158] Step 4a) Zr solution preparation: 0.6 mol% of Zr from Zr-propoxide (a solution of 70 wt% Zr-propoxide in n-propanol), 1.2 mol% lithium ethoxide powder, and ethanol solvent are mixed to form a solution relative to 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 specified intermediate product to be mixed in Step 4b).

[0159] 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.

[0160] Step 4c) Heating: Apply heat of 70°C to the reactor from step 4b) while connecting the reactor to a vacuum pump to evaporate the volatile phase. The product obtained from this step is a dry powder.

[0161] 5) Second heating: The dried powder from step 4c) is heated at 350°C for 6 hours in an oxygen atmosphere to obtain CEX3.2 with M', M' comprising Ni, Mn, Co, and Zr in a Ni:Mn:Co:Zr ratio of 0.632:0.164:0.198:0.006, as obtained by ICP. CEX3.2 has a D50 of 10 μm.

[0162] Example 3

[0163] EX3 is obtained using the same procedure as EX1, except that in the preparation of CEX1, 2500 ppm 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.

[0164] Example 4

[0165] EX4 is obtained using the same procedure as EX1, except that in the preparation of CEX1, 2500 ppm 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.

[0166] Table 3. Overview of primary particle diameter, composition, and corresponding electrochemical properties for the Examples and Comparative Examples .

[0167]

[0168] relative to the molar content of Ni, Mn, Co and Zr

[0169] **Due to Zr A It is 0 and therefore not applicable.

[0170] Table 3 summarizes the primary particle diameter, composition, and corresponding electrochemical properties of the examples and comparative examples. The average primary particle diameter of CEX1 and EX1 is 383 nm, which is greater than the average primary particle diameter of CEX2 and EX2 (292 nm). Similarly, the average primary particle diameter of EX4 is greater than that of EX3, which is related to the higher heating temperature applied in step 5). The positive electrode active materials CEX1, EX1, CEX2, EX2, EX3, and EX4 contain approximately 83 mol% Ni. CEX3.1 and CEX3.2, with a Ni content of approximately 64 mol%, have an average primary particle diameter of 371 nm. SEM images of the primary particles of EX1, EX2, and CEX3.2 are shown in Figures 1b, 1c, and 1d, respectively. To obtain the average primary particle diameter, the images include lines and numbers used to identify the primary particles.

[0171] Table 3 shows the XPS analysis results for EX1, EX2, CEX3.2, EX3, and EX4, which represent the Zr atomic ratio (equivalent to molar ratio) relative to the total atomic fractions of Ni, Mn, Co, and Zr. B The table also compares the results with those from the ICP. Zr B A value higher than 0 indicates that the Zr, associated with XPS measurements, exists on the surface of the positive electrode active material. The XPS measurement signal is obtained from the first few nanometers (e.g., 1 nm to 10 nm) of the topmost portion of the sample (i.e., the surface layer). On the other hand, the Zr atomic ratio obtained by ICP measurements comes from the entire particle. Therefore, the XPS to ICP ratio (Zr...) B / Zr AA value higher than 1 indicates that the element Zr is mainly present on the surface of the positive electrode active material. Higher Zr values... B / Zr A The higher the Zr value, the more Zr present on the surface of the positive electrode active material. Zr values ​​in EX1, EX2, CEX3.2, EX3, and EX4 are also higher. B / Zr A All values ​​are above 50, confirming the effectiveness of the Zr treatment according to the present invention. Representative XPS spectra of the Zr 3d5 and 3d3 peaks for EX1 and EX2 are shown in [the figures]. Figure 2 middle.

[0172] Compared to the untreated material, the Zr-treated positive electrode active material has a higher carbon content, which is related to the improved electrochemical performance of the active material. The carbon originates from the Zr alkoxide compounds used in the treatment.

[0173] For positive electrode active materials with a Ni content of at least 70 mol%, primary particles with an average diameter of at least 250 nm and a Zr content higher than 50.0 B / Zr A The combination of these elements can achieve the objective of the present invention, namely, 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 positive electrode active material for a solid-state battery, wherein the positive electrode active material comprises Li, M', and oxygen, wherein M' comprises: - Ni, the content of which x is between 80.0 mol% and 95.0 mol% relative to M'; - Co, the content of which is between 0.0 mol% and 40.0 mol% relative to M'; - Mn, the content of which z is between 0.0 mol% and 40.0 mol% relative to M', - D, the content of which is between 0.0 mol% and 2.0 mol% relative to M', wherein D comprises at least one of the following elements: Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, Ti, Y, V, W, and Zn, and - Zr, the content of which b relative to M' is between 0.1 mol% and 5.0 mol%, - Where x, y, z, a, and b are measured via ICP. - where x + y + z + a + b is 100.0 mol%. The positive electrode active material has a Zr content as defined below. A : , The positive electrode active material has a Zr content. B Zr B It was determined through XPS analysis, where Zr B The mole fraction is expressed as the sum of the mole fractions of Co, Mn, Ni, and Zr as measured by XPS analysis, and Zr B Between 0.50 mol% and 1.5 mol%, The ratio Zr B / Zr A > 50.0, The positive electrode active material described herein comprises secondary particles having a plurality of primary particles. The primary particles described herein have an average diameter between 250 nm and 600 nm, determined by measuring the size of primary particles in images captured by SEM. The positive electrode active material has a carbon content of at least 600 ppm and at most 8000 ppm as determined by a carbon analyzer.

2. The positive electrode active material according to claim 1, wherein the primary particles have an average diameter between 300 nm and 600 nm.

3. The positive electrode active material according to claim 1 or 2, wherein the ratio Zr B / Zr A It should be at least 80.

4. The positive electrode active material according to claim 1 or 2, wherein the ratio Zr B / Zr A The minimum is 100.

5. The positive electrode active material according to claim 1 or 2, wherein the ratio Zr B / Zr A The minimum is 120.

6. The positive electrode active material according to claim 1 or 2, wherein the ratio Zr B / Zr A The minimum is 130.

7. The positive electrode active material according to claim 1 or 2, wherein the ratio Zr B / Zr A The maximum is 500.

8. The positive electrode active material according to claim 1 or 2, wherein the ratio Zr B / Zr A The maximum is 300.

9. The positive electrode active material according to claim 1 or 2, wherein the ratio Zr B / Zr A The maximum is 200.

10. The positive electrode active material according to claim 1 or 2, wherein x > 81.0 mol.

11. The positive electrode active material according to claim 1 or 2, wherein x ≤ 91.0 mol.

12. The positive electrode active material according to claim 1 or 2, wherein 0 mol% ≤ y ≤ 20 mol%.

13. The positive electrode active material according to claim 1 or 2, wherein 5.0 mol% ≤ z ≤ 30.0 mol%.

14. The positive electrode active material according to claim 1 or 2, wherein b / (b+x+y+z) is at least 0.10 mol% and at most 1.00 mol%.

15. The positive electrode active material according to claim 1 or 2, wherein the median size D50 of the secondary particles, as determined by laser diffraction particle size analysis, is at least 2.0 µm and at most 15.0 µm.

16. A method for manufacturing 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 15, the method comprising the following sequential steps: - Preparation of lithium transition metal-based oxide compounds, - The lithium transition metal-based oxide compound is mixed with a Zr source selected from Zr alkoxides in an alcohol solvent containing lithium alkoxides to obtain a mixture, and - The mixture is heated in an oxidizing atmosphere in a furnace at a temperature of 350°C to less than 500°C for 1 to 20 hours to obtain the powder of the positive electrode active material.

17. The method of claim 16, wherein the heating temperature of the mixture is at most 450°C.

18. The method of claim 16, wherein the method includes an additional step of drying the mixture before heating the mixture.

19. The method of claim 16, wherein the method includes an additional step of drying the mixture by vacuum heating prior to heating the mixture.

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

21. The solid-state battery of claim 20, wherein the solid-state battery comprises a sulfide-based solid electrolyte containing Li, P and S.

22. Use of the solid-state battery according to claim 20 or 21 in an electric vehicle.

23. Use of the solid-state battery according to claim 20 or 21 in a hybrid electric vehicle.

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