Lithium nickel composite oxides as cathode active materials for rechargeable sulfide solid-state batteries

Abstract

The present invention relates to a positive electrode active material containing Li, M', and oxygen, wherein M' contains Ni, Co, Mn, and BQ, and Q is an element other than Li, O, Ni, Co, Mn, and B, the positive electrode active material having a large amount of B in a surface layer, and the positive electrode active material containing secondary particles including a plurality of primary particles with a small crystallite size.

Description

[Technical Field]

[0001] The present invention relates to a cathode active material for a solid-state battery comprising Li, M', and O, wherein M' comprises B. The present invention also relates to a method for producing the cathode active material, a solid-state battery comprising the cathode active material, and the use of the solid-state battery. [Background technology]

[0002] The rapid development of small and lightweight electronic products, electronic devices, communication devices, and the like, and the widespread need for electric vehicles in relation to environmental issues, have created a demand for improved performance of secondary batteries used as power sources for these products. Among these, lithium secondary batteries have attracted attention as high-performance batteries due to their high energy density and high reference electrode potential.

[0003] During the charging process of a secondary battery, lithium ions are removed from the cathode, transported through the electrolyte, and inserted into the anode, while electrons are removed from the cathode and injected into the anode through an external circuit (charger). During use or discharge of a secondary battery, lithium ions are removed from the anode, transported through the electrolyte, and inserted into the cathode, and electrons flow through the external circuit to provide electrical work.

[0004] Commonly used cathode active materials are lithium transition metal oxides. During charging and / or discharging of lithium batteries, delithiated cathode active materials react slowly with non-aqueous or solid electrolytes, potentially leading to gradual degradation of the electrochemical performance of lithium batteries using such cathode active materials. Coating cathode active materials with metals such as B or Zr (i.e., applying a thin surface layer of a metal onto the cathode active material, resulting in an increased amount of the metal in the surface layer) has been shown to result in cathode active materials that exhibit greater stability than their counterparts lacking the coating layer.

[0005] US 2020 / 0303720 A1 contemplates a boron-coated cathode active material comprising nickel, cobalt, and manganese in a ratio of 8:1:1 by dry mixing the uncoated cathode active material with boron, followed by a heat treatment step at 300°C for 5 hours.

[0006] Zhang et al. (Adv. Energy Mater. 2020, 10, 1903778) described a boron-coated cathode active material containing nickel, cobalt, and manganese in a 5:2:3 ratio using a sol-gel method, where triisopropyl borate was dissolved in ethanol, and then the uncoated cathode active material was dispersed in the solution, followed by solvent removal and subsequent heat treatment at 350°C.

[0007] However, there remains a need to provide a positive electrode active material with a high amount of boron in the surface layer to improve the cycling efficiency of the resulting battery and / or reduce battery polarization as much as possible.

[0008] It is an object of the present invention to provide a positive electrode active material with a high amount of boron in the surface layer that improves the cycling efficiency of the resulting battery.

[0009] Another object of the present invention is to provide a method for producing the positive electrode active material.

[0010] Another object of the present invention is to provide a battery containing the positive electrode active material.

[0011] Another object of the present invention is to provide a use of said battery. [Prior art documents] [Patent documents]

[0012] [Patent Document 1] US 2020 / 0303720 A1 [Non-patent literature]

[0013] [Non-Patent Document 1] Adv. Energy Mater. 2020, 10, 1903778 Summary of the Invention

[0014] In a first aspect, the present invention provides an active cathode material for a solid-state battery comprising Li, M′, and oxygen, wherein M′ is: Ni with a content x, where x is 50.0 ≦ x ≦ 75.0 mol% relative to M'; Co with a content y of 0.0≦y≦25.0 mol% relative to M′; Mn with a content z of 0.0≦z≦25.0 mol% relative to M'; B having a content b of 0.01≦b≦1.5 mol% relative to M'; Q is an element other than Li, O, Ni, Co, Mn, and B, and has a content q of 0.0≦q≦2.0 mol% relative to M′; x, y, z, b, and q are measured by ICP-OES; x+y+z+b+q is 100.0 mol%, The positive electrode active material has a large amount of B in the surface layer, This is achieved by providing a positive electrode active material that includes secondary particles that include a plurality of primary particles having a small crystallite size.

[0015] The present inventors have surprisingly found that the positive electrode active material of the present invention significantly increases the cycling efficiency of batteries, particularly sulfide solid state batteries, and furthermore, exhibits low polarization within the battery.

[0016] Without wishing to be bound by any theory, the inventors believe that the combination of a large amount of B in the surface layer (i.e., boron coating) and a positive electrode active material having a low crystallite size (i.e., an average diameter of secondary particles, including primary particles, of 100 nm to 400 nm) improves the cycling efficiency of the battery and / or reduces polarization within the battery.

[0017] Although boron-coated positive electrode active materials are already known in the art (see US 2020 / 0303720 A1 or Zhang et al. (Adv. Energy Mater. 2020, 10, 1903778)), the present inventors report for the first time the synergistic effect of boron coating and low crystallite size of the positive electrode active material. US 2020 / 0303720 A1 or Zhang et al. (Adv. Energy Mater. 2020, 10, 1903778) do not disclose the crystallization size of the particles, nor do they describe or suggest the synergistic effect of boron coating and low crystallite size of the particles.

[0018] In a further aspect, the present invention provides a method for making the cathode active material.

[0019] In a further aspect, the present invention provides a battery comprising the active cathode material.

[0020] In a further aspect, the present invention provides a use of the battery. [Brief explanation of the drawings]

[0021] [Figure 1] This is an XPS spectrum of the B1s peak of EX1.1. [Figure 2a] 1 is an SEM image showing secondary particles of CEX1 containing multiple primary particles, where the dotted line indicates the area captured to obtain the average primary particle size. [Figure 2b] SEM image of CEX1 to obtain the average primary particle size. DETAILED DESCRIPTION OF THE INVENTION

[0022] In the following detailed description, preferred embodiments are described in detail to enable the practice of the invention. While the invention is described with reference to these particular preferred embodiments, it should be understood that the invention is not limited to these preferred embodiments. To the contrary, the invention includes numerous alternatives, modifications, and equivalents that will become apparent in light of the following detailed description.

[0023] When used in the present specification and claims, the term "comprising" should not be interpreted as being limited to the means listed below, nor does it exclude other elements or steps. It should be interpreted as specifying the presence of the mentioned or stated features, integers, steps, or components, but does not exclude the presence or addition of one or more other features, integers, steps, or components, or groups thereof. Thus, the scope of the expression "a composition comprising components A and B" should not be limited to a composition consisting only of components A and B. This means that, in the context of the present invention, the only relevant components of the composition are A and B. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of."

[0024] As used herein and in the claims, the term "solid-state battery" refers to a cell or battery that contains only solid or substantially solid components, such as solid electrodes (e.g., anode and cathode) and a solid electrolyte.

[0025] The term "positive electrode active material" (also known as cathode active material) as used herein and in the claims is defined as a material that is electrochemically active in a positive electrode or cathode. It should be understood that an active material is a material that can capture Li ions and release them when subjected to a voltage change over a predetermined period of time.

[0026] In the context of the present invention, the terms "solid" and "liquid" shall be considered to be solids and liquids under standard conditions of temperature and pressure as defined by IUPAC, unless otherwise defined, whereby boiling and melting points are considered to be boiling and melting points at standard atmospheric pressure, i.e., 101325 Pa.

[0027] positive electrode active material In a first aspect, the present invention provides a cathode active material for a solid-state battery comprising Li, M′, and oxygen, wherein M′ is: Ni with a content x, where x is 50.0 ≦ x ≦ 75.0 mol% relative to M'; Co with a content y of 0.0≦y≦25.0 mol% relative to M′; Mn with a content z of 0.0≦z≦25.0 mol% relative to M'; B with a content b of 0.01≦b≦2.0 mol% relative to M′, preferably 0.01≦b≦1.5 mol% relative to M′; Q is an element other than Li, O, Ni, Co, Mn, and B, and has a content q of 0.0≦q≦2.0 mol% relative to M′; x, y, z, b, and q are measured by ICP-OES; x+y+z+b+q is 100.0 mol%, The positive electrode active material has a content B defined as b / (x+y+z+b) A B of The positive electrode active material has a content of B B B has B B was determined by XPS analysis, and B B is expressed as the mole fraction B compared to the sum of the mole fractions of Ni, Mn, Co, and B, as measured by XPS analysis, and B B / B A Ratio > 40.0, preferably B B / B A the ratio is greater than 45.0, the positive electrode active material contains secondary particles that contain a plurality of primary particles, Regarding the positive electrode active material, when the primary particle is determined by measuring the primary particle size in the image taken by SEM, it has an average diameter of 100 nm to 400 nm.

[0028] A preferred embodiment is the positive electrode active material of the present invention, wherein the Ni content is x≥55.0 mol%, preferably x≥58.0 mol%, more preferably x≥60.0 mol%. In a preferred embodiment, the Ni content is x≤70.0 mol%, preferably x≤68.0 mol%, more preferably x≤65.0 mol%. A more preferred embodiment is the positive electrode active material of the present invention, wherein the Ni content is 55.0 mol%≤x≤70.0 mol%, preferably 58.0 mol%≤x≤68.0 mol%, more preferably 60.0 mol%≤x≤65.0 mol%.

[0029] As understood by those skilled in the art, the amounts of Li and M' in the positive electrode active material, preferably Li, Ni, Mn, Co, Q and B, are measured by inductively coupled plasma optical emission spectrometry (ICP-OES). For example, without being limited to the present invention, Agilent ICP 720-ES is used for ICP-OES analysis.

[0030] A preferred embodiment is the positive electrode active material of the present invention, wherein the Co content is y>0.0 mol%, preferably y≥10.0 mol%, more preferably y≥18.0 mol%. In a preferred embodiment, the content is y≤28.0 mol%, preferably y≤25.0 mol%, more preferably y≤22.0 mol%. In a preferred embodiment, the Mn content is 0.0 mol%<y≤28.0 mol%, preferably 10.0 mol%≤y≤25.0 mol%, more preferably 18.0 mol%≤y≤22.0 mol%.

[0031] A preferred embodiment is the positive electrode active material of the present invention in which the content of Mn is z > 0.0 mol%, preferably z ≥ 10.0 mol%, more preferably z ≥ 15.0 mol%. In a preferred embodiment, the content is z ≤ 28.0 mol%, preferably z ≤ 25.0 mol%, more preferably z ≤ 20.0 mol%. In a preferred embodiment, the content of Mn is 0.0 mol% < z ≤ 28.0 mol%, preferably 10.0 mol% ≤ z ≤ 25.0 mol%, more preferably 15.0 mol% ≤ z ≤ 20.0 mol%.

[0032] As known to those skilled in the art, the positive electrode active material of the present invention may contain impurities or be doped or coated, and as a result, the entire positive electrode active material may contain one or more elements other than Li, Ni, Mn, Co, B, and O, which are reflected by the parameter "Q" used herein. A preferred embodiment is the positive electrode active material according to the present invention containing Q, and Q is at least one element selected from the group consisting of Al, Ti, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr, preferably Al, Ti, Cr, Nb, S, Si, Y, Zr, and W, more preferably Al, Ti, Nb, Zr, and W.

[0033] A preferred embodiment is the positive electrode active material according to the present invention in which the content q of Q is q > 0.0 mol%, preferably q ≥ 0.25 mol%, more preferably q ≥ 0.5 mol%. In a preferred embodiment, the content is q ≤ 1.75 mol%, preferably q ≤ 1.5 mol%, more preferably q ≤ 1.25 mol%. In a preferred embodiment, the content is 0.0 mol% < q ≤ 1.75 mol%, preferably 0.25 mol% ≤ q ≤ 1.5 mol%, more preferably 0.5 mol% ≤ q ≤ 1.25 mol%.

[0034] In a specific preferred embodiment, the positive electrode active material is according to the present invention with q = 0.0 mol%.<​​In a preferred embodiment, the B content is b≧0.05 mol%, preferably b≧0.1 mol%, and more preferably b≧0.2 mol%. In a preferred embodiment, b≦1.25 mol%, preferably b≦1.1 mol%, and more preferably b≦1.0 mol%. In a preferred embodiment, 0.05 mol%≦b≦1.25 mol%, preferably 0.1 mol%≦b≦1.1 mol%, and more preferably 0.2 mol%≦b≦1.0 mol%.

[0036] A preferred embodiment is a cathode active material of the present invention having a Li / M' ratio, preferably a Li / (Ni+Mn+Co) ratio, of >0.90, preferably >0.92, more preferably >0.95. A preferred embodiment is a cathode active material of the present invention having a Li / M' ratio, preferably a Li / (Ni+Mn+Co) ratio, of <1.10, preferably <1.08, more preferably <1.05. A preferred embodiment is a cathode active material of the present invention having a Li / M' ratio, preferably a Li / (Ni+Mn+Co) ratio, in the range of 0.90 to 1.10, preferably 0.92 to 1.08, more preferably 0.95 to 1.05. As will be understood by those skilled in the art, the Li / M' ratio, preferably the Li / (Ni+Mn+Co) ratio, is a molar ratio (mol / mol).

[0037] A preferred embodiment is the positive electrode active material of the present invention having a carbon content exceeding 0.010 wt% of the total weight of the positive electrode active material, preferably a carbon content exceeding 0.011 wt% of the total weight of the positive electrode active material, more preferably a carbon content exceeding 0.012 wt%. A preferred embodiment is the positive electrode active material of the present invention having a carbon content less than 0.050 wt% of the total weight of the positive electrode active material, preferably a carbon content less than 0.040 wt% of the total weight of the positive electrode active material, more preferably a carbon content less than 0.030 wt%. A preferred embodiment is the positive electrode active material of the present invention having a carbon content in the range of 0.010 wt% to 0.050 wt% of the total weight of the positive electrode active material, preferably a carbon content in the range of 0.011 wt% to 0.040 wt% of the total weight of the positive electrode active material, more preferably a carbon content in the range of 0.012 wt% to 0.030 wt%. As understood by those skilled in the art, the carbon content of the positive electrode active material of the present invention is measured by a carbon analyzer. For example, but not limited to the present invention, the carbon content C can be measured using a Horiba Emia-Expert carbon / sulfur analyzer.

[0038] A very preferred embodiment is the positive electrode active material according to the present invention having the formula (I):

[0039] Li w2 Ni x2 Co y2 Mn z2 B b2 [[ID=,18]]Q2 q2 O2(I)

[0040] (where 0.90 ≦ w2 ≦ 1.10, preferably 0.92 ≦ w2 ≦ 1.08, more preferably 0.95 ≦ w2 ≦ 1.05, 0.50 ≦ x2 ≦ 0.75, preferably 0.55 ≦ x2 ≦ 0.70, more preferably 0.60 ≦ x2 ≦ 0.65, 0.0 < y2 ≦ 0.28, preferably 0.10 ≦ y2 ≦ 0.25, more preferably 0.18 ≦ y2 ≦ 0.22, 0.0 < z2 ≦ 0.28, preferably 0.10 ≦ z2 ≦ 0.25, more preferably 0.15 ≦ z2 ≦ 0.20, 0.0005≦b2≦0.0125, preferably 0.001≦b2≦0.011, more preferably 0.002≦b2≦0.01, 0.0≦q2≦0.0175, preferably 0.0≦q2≦0.015, more preferably 0.0≦q2≦0.0125, and most preferably q2 is about 0.0; x2+y2+z2+b2+q2=1.00, Q2 is an element other than Li, O, Ni, Co, Mn, and B).

[0041] As known to those skilled in the art, the active cathode materials of the present invention may contain impurities or may be doped or coated such that the overall active cathode material contains one or more elements other than Li, Ni, Mn, Co, B, and O, as reflected by the parameter "Q2" used herein. A preferred embodiment is an active cathode material according to the present invention comprising Q2, where Q2 is at least one element selected from the group consisting of Al, Ti, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr, preferably Al, Ti, Cr, Nb, S, Si, Y, Zr, and W, more preferably Al, Ti, Nb, Zr, and W.

[0042] surface layer In a preferred embodiment, the positive electrode active material has a content B defined as b / (x+y+z+b). A The positive electrode active material has a content of B B B has B B was determined by XPS analysis, and B B is expressed as the mole fraction B compared to the sum of the mole fractions of Ni, Mn, Co, and B, as measured by XPS analysis, and the ratio B B / B A The positive electrode active material of the present invention has a refractive index of 1.0 to 1.25, and the refractive index is 1.0 to 1.25.

[0043] A more preferred embodiment is a ratio B B / B A >45.0, preferably ratio B B / B A >50.0, more preferably ratio B B / B A >60.0, even more preferably ratio B B / B A >70.0, even more preferably ratio B B / B A >80.0, most preferably ratio B B / B A The positive electrode active material of the present invention has a refractive index of >90.0.

[0044] A more preferred embodiment is a ratio B B / B A <1000.0, preferably ratio B B / B A <500.0, more preferably ratio B B / B A <200.0, even more preferably ratio B B / B A <150.0, most preferably ratio B B / B A <125.0.

[0045] A more preferred embodiment is a ratio B B / B A is in the range of 50.0 to 1000.0, and preferably the ratio B B / B A is in the range of 70.0 to 200.0, and more preferably the ratio B B / B A The positive electrode active material of the present invention relates to a positive electrode active material in which the value of the positive electrode active material is in the range of 90.0 to 125.0.

[0046] In the context of the present invention, B Bis the mole fraction B relative to the sum of the mole fractions of Ni, Mn, Co, and B, and the mole fraction of B measured within a region of a particle of a positive electrode active material according to the present invention is defined between a first point on the outer edge of the particle and a second point spaced from the first point. The distance separating the first point from the second point is equal to the XPS penetration depth, D', which is between 1.0 and 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. As will be understood by those skilled in the art, similar XPS analyses can be performed for the mole fractions of Ni, Mn, and Co.

[0047] Within the framework of the present invention, the outer edge of a particle is the boundary or outer limit that distinguishes the particle from its external environment. Therefore, XPS analysis provides the atomic content of elements in the top layer of the particle, with a penetration depth of approximately 10.0 nm from the outer boundary of the particle. The outer boundary of the particle is also referred to as the "surface." For example, but not limited to, the XPS analysis was performed using a Thermo K-α+ spectrometer (Thermo Scientific).

[0048] Within the framework of the present invention, at% means atomic percentage. At% or "atomic percentage" of a given element as an expression of concentration means what percentage of all atoms in the compound under consideration are atoms of that element. Furthermore, within the framework of the present invention, the designation at% is equivalent to mol% or "mol percent".

[0049] In the context of the present invention, the active cathode material may include an additional surface layer comprising Q, where Q is at least one element selected from the group consisting of Al, Ti, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr, preferably Al, Ti, Cr, Nb, S, Si, Y, Zr, and W, more preferably Al, Ti, Nb, Zr, and W, and a surface layer of B may be disposed on the additional surface layer, and / or the additional surface layer may be disposed on the surface layer of B, and / or the active cathode material may include a mixed surface layer comprising the surface layer of B and the additional surface layer.

[0050] structure In a preferred embodiment, the cathode active material of the present invention comprises polycrystalline particles comprising a plurality of primary particles. As will be understood by those skilled in the art, polycrystalline particles are aggregated by five or more single-crystal particles, preferably ten or more single-crystal particles, and more preferably fifty or more single-crystal particles. This can be observed by observing the grain boundaries using a suitable microscopy technique, such as a scanning electron microscope (SEM). The aggregation of single-crystal particles into polycrystalline particles occurs during post-treatment steps, such as heat treatment steps. In the context of the present invention, a particle is considered to be single crystalline if it consists of only one grain or up to five grains, preferably up to three grains, as observed by a scanning electron microscope (SEM) or a transmission electron microscope (TEM), preferably by observing the grain boundaries of the particle. A grain boundary is defined as the interface between two grains within a particle, and preferably, the atomic planes of the two grains are aligned in different orientations and intersect as a crystalline discontinuity.

[0051] A preferred embodiment relates to a cathode active material of the present invention comprising polycrystalline particles having a secondary particle median D50 value of less than 20 μm, preferably less than 15 μm, and more preferably less than 12 μm. A preferred embodiment relates to a cathode active material of the present invention comprising polycrystalline particles having a secondary particle median D50 value of greater than 2 μm, preferably greater than 5 μm, and more preferably greater than 8 μm. A preferred embodiment relates to a cathode active material of the present invention comprising polycrystalline particles having a secondary particle median D50 value of 2 to 20 μm, preferably 5 to 15 μm, and more preferably 8 to 12 μm. As will be understood by those skilled in the art, the particle size distribution (PSD) D50 of a cathode active material powder is measured by laser diffraction particle size analysis. For example, but not limited to, the particle median D50 value can be measured using a Malvern Mastersizer 3000. In a highly preferred embodiment, the particle size distribution (PSD) of the polycrystalline particles included in the active cathode materials of the present invention is measured by secondary particle size analysis, preferably by laser diffraction particle size analysis using a Malvern Mastersizer 3000 equipped with a Hydro MV wet dispersion accessory after dispersing each powder sample in an aqueous medium. More preferably, D50 is defined as the particle size at 50% of the cumulative volume percent distribution obtained from the Malvern Mastersizer 3000 using Hydro MV measurement.

[0052] In certain preferred embodiments of the present invention, and in the context of the present invention, polycrystalline particles as defined herein are secondary particles. In these certain preferred embodiments, as will be understood by those skilled in the art, all embodiments relating to polycrystalline particles apply equally to secondary particles as defined in the present invention.

[0053] In a preferred embodiment, the cathode active material of the present invention comprises polycrystalline particles comprising a plurality of primary particles, the primary particles having an average diameter of 100 nm to 400 nm, as determined by measuring the primary particle size in an image taken by SEM. A preferred embodiment relates to a cathode active material of the present invention comprising polycrystalline particles comprising a plurality of primary particles, the primary particles having an average diameter of greater than 150 nm, preferably greater than 200 nm, and more preferably greater than 250 nm. A preferred embodiment relates to a cathode active material of the present invention comprising polycrystalline particles comprising a plurality of primary particles, the primary particles having an average diameter of less than 375 nm, preferably less than 350 nm, and more preferably less than 325 nm. A preferred embodiment relates to a cathode active material of the present invention comprising polycrystalline particles comprising a plurality of primary particles, the primary particles having an average diameter of 150 to 375 nm, preferably 200 to 350 nm, and more preferably 250 to 325 nm. In a highly preferred embodiment, the average diameter of primary particles is measured by primary particle size analysis method, preferably by measuring the primary particle size in the image taken by SEM.As will be understood by those skilled in the art, the average diameter of primary particles is measured by primary particle size analysis method, and the diameter of primary particles is calculated using ImageJ software (ImageJ 1.52a, National Institutes of Health, USA) according to the following steps: Step 1) Open the file containing the SEM image of the positive electrode active material at 10,000x magnification (this image was taken at the center of a secondary particle). Step 2) Set the scale according to the SEM magnification. Step 3) Use the polygon selection tool to draw lines that follow the edges of the primary particles for at least 50 particles. When truncating, particles at the edges of the image will be excluded. Step 4) Measure the area of ​​the drawn primary particle, which is selected from the Measurement Settings and Area boxes. Step 5) The particles are as follows:

number

[0054] As will be appreciated by those skilled in the art, and in a highly preferred embodiment of the present invention, the secondary particles have a content B as defined herein. A B, the content B as defined herein B B and the ratio B as defined herein B / B A Includes: In certain preferred embodiments of the present invention, the cathode active material of the present invention comprises polycrystalline particles comprising a plurality of primary particles, The polycrystalline particles have a secondary particle median D50 value of 12 to 20 μm, preferably 5 to 15 μm, and more preferably 8 to 12 μm; The average diameter of the primary particles is 150 to 375 nm, preferably 200 to 350 nm, and more preferably 250 to 325 nm.

[0055] In certain preferred embodiments of the present invention, the cathode active material of the present invention comprises polycrystalline particles comprising a plurality of primary particles, The polycrystalline particles have a secondary particle median D50 value of 12 to 20 μm, preferably 5 to 15 μm, and more preferably 8 to 12 μm; Ratio B B / B A is in the range of 50.0 to 1000.0, and preferably, the ratio B B / B A is in the range of 70.0 to 200.0, and more preferably, the ratio B B / B A is in the range of 90.0 to 125.0.

[0056] In certain preferred embodiments of the present invention, the cathode active material of the present invention comprises polycrystalline particles comprising a plurality of primary particles, the primary particles have an average diameter of 150 to 375 nm, preferably 200 to 350 nm, more preferably 250 to 325 nm; Ratio B B / B Ais in the range of 50.0 to 1000.0, and preferably, the ratio B B / B A is in the range of 70.0 to 200.0, and more preferably, the ratio B B / B A is in the range of 90.0 to 125.0.

[0057] In a preferred embodiment of the present invention, the positive electrode active material of the present invention comprises polycrystalline particles including a plurality of primary particles, The polycrystalline particles have a secondary particle median D50 value of 12 to 20 μm, preferably 5 to 15 μm, and more preferably 8 to 12 μm; the primary particles have an average diameter of 150 to 375 nm, preferably 200 to 350 nm, more preferably 250 to 325 nm; Ratio B B / B A is in the range of 50.0 to 1000.0, and preferably, the ratio B B / B A is in the range of 70.0 to 200.0, and more preferably, the ratio B B / B A is in the range of 90.0 to 125.0.

[0058] In a further aspect, the present invention provides a secondary particle-based cathode active material for a solid-state battery comprising Li, M′, and oxygen, wherein M′ is: Ni with a content x, where x is 50.0 ≦ x ≦ 75.0 mol% relative to M'; Co with a content y of 0.0≦y≦30.0 mol% relative to M′; Mn with a content z of 0.0≦z≦30.0 mol% relative to M'; B having a content b of 0.01≦b≦1.5 mol% relative to M'; Q is an element other than Li, O, Ni, Co, Mn, and B, and has a content q of 0.0≦q≦2.0 mol% relative to M′; x, y, z, b, and q are measured by ICP-OES; x+y+z+b+q is 100.0 mol%, The positive electrode active material has a content B defined as b / (x+y+z+b) A B of The positive electrode active material has a content of B B B has B B was determined by XPS analysis, and B B is expressed as the mole fraction B compared to the sum of the mole fractions of Ni, Mn, Co, and B, as measured by XPS analysis, and the ratio B B / B A >40.0, the secondary particles include a plurality of primary particles, The positive electrode active material is provided in which the primary particles have an average diameter of 100 nm to 400 nm as determined by measuring the primary particle size in an image taken by SEM.

[0059] In a highly preferred embodiment of the secondary particle-based cathode active material, all embodiments directed to the cathode active material according to the first aspect of the present invention apply mutatis mutandis to the secondary particle-based cathode active material. For example, Li, M', B as described herein in the context of the cathode active material B , B A , the various embodiments regarding the identity and amount of primary and secondary particle sizes are equally applicable to secondary particle-based positive electrode active materials.

[0060] method In a second aspect, the present invention provides a method for making a cathode active material, the method comprising: preparing a lithium transition metal based oxide compound; mixing the lithium transition metal oxide compound with a B source to obtain a mixture; and heating the mixture at a temperature of 250°C to less than 500°C for 1 hour to 20 hours to obtain a positive electrode active material.

[0061] In a highly preferred embodiment of the method of making a cathode active material of the present invention, the cathode active material is according to the first aspect of the present invention. As will be understood by those skilled in the art, when the method of making a cathode active material of the present invention results in a cathode active material according to the first aspect of the present invention, all embodiments directed to the cathode active material according to the first aspect of the present invention apply mutatis mutandis to the method of making a cathode active material according to the first aspect of the present invention. For example, Li, M', B as described herein in the context of the cathode active material may be used. B , B A The various embodiments regarding the identity and amount of primary and secondary particle sizes are equally applicable to the method of preparing the positive electrode active material.

[0062] In a preferred embodiment of the method, the lithium transition metal-based oxide compound comprises Li, M″, and oxygen, where M″ comprises Ni, Mn, Co, and Q, where Q is at least one element selected from the group consisting of Al, Ti, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr; preferably Al, Ti, Cr, Nb, S, Si, Y, Zr, and W; more preferably Al, Ti, Nb, Zr, and W. Preferably, the lithium transition metal-based oxide used is also typically prepared according to a lithiation process, in which a mixture of a transition metal oxide precursor and a lithium source is heated at a temperature of preferably at least 500°C and at most 1000°C. Typically, the transition metal precursor is prepared by co-precipitation of one or more transition metal sources, such as salts, preferably sulfates or nitrates, more preferably sulfates, of the elements Ni, Mn, and / or Co, in the presence of an alkali compound, such as an alkali hydroxide, e.g., sodium hydroxide and / or ammonia. Preferably, the lithium source is metallic lithium or a lithium salt, preferably a lithium salt such as LiOH.

[0063] In a preferred embodiment, mixing the lithium transition metal-based oxide compound with the B source is dry mixing the lithium transition metal-based oxide compound with the B source. As will be understood by those skilled in the art, dry mixing means that no additional solvent is added to the mixture of the lithium transition metal-based oxide compound and the B source.

[0064] In a preferred embodiment, the B source is boric acid (HBO), boron oxide (BO) or a borate such as sodium tetrahydroxyborate (NaB(OH)), trisodium orthoborate (NaBO), sodium perborate (NaHBO), sodium metaborate (NaBO), etc., and preferably the B source is boric acid (HBO).

[0065] In a preferred embodiment, the amount of B source added is at least 0.05 mol % of B present in the B source for M″, preferably at least 0.1 mol % of B present in the B source for M″, more preferably at least 0.2 mol % of B. In a preferred embodiment, the amount of B source added is at most 1.25 mol % of B present in the B source for M″, preferably at most 1.1 mol % of B present in the B source for M′, more preferably at most 1.0 mol % of B. In a preferred embodiment, the amount of B source added is 0.05 mol % to 1.25 mol % of B present in the B source for M″, preferably 0.1 mol % to 1.1 mol % of B present in the B source for M″, more preferably 0.2 mol % to 1.0 mol % of B present in the B source for M″.

[0066] In a preferred embodiment of the method, the mixture is heated to a temperature above 275° C., preferably above 300° C., most preferably above 325° C. In a preferred embodiment of the method, the mixture is heated to a temperature below 450° C., preferably below 400° C., more preferably below 375° C. In a preferred embodiment of the method, the mixture is heated to a temperature between 275° C. and 450° C., preferably between 300 and 400° C., more preferably between 325 and 375° C.

[0067] In a preferred embodiment, the mixture is heated for a period of more than 2 hours, preferably more than 3 hours, more preferably more than 4 hours. In a preferred embodiment, the mixture is heated for a period of less than 15 hours, preferably less than 10 hours, preferably less than 7 hours. In a preferred embodiment, the mixture is heated for a period of 2 to 15 hours, preferably 3 to 12 hours, more preferably 4 to 10 hours.

[0068] In a preferred embodiment, heating the mixture comprises: At a temperature of 275°C to 450°C, preferably 300 to 400°C, more preferably 325 to 375°C, The reaction is carried out for a time period of 2 to 15 hours, preferably 3 to 12 hours, and more preferably 4 to 10 hours.

[0069] A preferred embodiment of the method is heating the mixture under an oxidizing atmosphere, preferably comprising or consisting of oxygen, such as air.

[0070] In a more preferred embodiment, the heating is carried out in a furnace.

[0071] Product by Process In a third aspect, the present invention relates to a cathode active material obtainable by the method according to the second aspect of the present invention.

[0072] As will be understood by those skilled in the art, all embodiments directed to the cathode active material according to the first aspect of the present invention and / or the method according to the second aspect of the present invention apply mutatis mutandis to the cathode active material obtainable by the method according to the present invention. For example, Li, M', B described herein in the context of the cathode active material of the present invention and / or in the context of the method of the present invention may be used. B , B A The various embodiments regarding the identity and amount of primary particle size and secondary particle size are equally applicable to the positive electrode active material obtainable by the method of manufacturing the positive electrode active material.

[0073] battery In a fourth aspect, the present invention relates to a battery comprising an active cathode material according to the first aspect of the invention and / or an active cathode material obtainable by a method according to the third aspect of the invention.

[0074] In a preferred embodiment, the battery is a solid-state battery. Preferably, the solid-state battery includes a sulfide-based electrolyte. Preferably, the electrolyte is a sulfide-based solid electrolyte, more preferably, the electrolyte includes Li, P, and S. Typically, the following sulfur-containing compounds are used: Li6PS5X, where X is F, Br, Cl, or I, preferably Br or Cl; thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S4), Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li2S-SiS2, Li2S-P2S5-LiCl, Li2S-SiS2, LiI-Li 2S-SiS2, LiI-Li2S-P2S5, LiI-Li2S-P2O5, LiI-Li3PO4-P2S5, Li2S-P2S5, Li3PS4, Li7P3S 11 , LiI-Li2S-B2S3, Li3PO4-Li2S-SiS2, Li3PO4-Li2S-SiS2, Li3PO4-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 may be suitably used. In a highly preferred embodiment, the battery is a sulfide solid state battery.

[0075] Preferably, the solid-state battery further comprises an anode comprising an anode active material. Suitable electrochemically active anode materials are known in the art. For example, the anode may comprise graphite carbon, metallic lithium, or a metal alloy containing lithium, such as a Li-In alloy, as the anode active material.

[0076] In a preferred embodiment, the rate efficiency of the battery according to the present invention is at least 85%, preferably at least 86%, more preferably at least 88%, and most preferably at least 90%. As will be appreciated by those skilled in the art, the rate efficiency of a battery is determined through a rate efficiency test method, which is a conventional "constant cut-off voltage" test, in which each cell is cycled at 60°C using a Toscat-3100 computer-controlled galvanostatic cycling station (manufactured by Toyo). The rate efficiency (%) is obtained according to the following formula, where DQ5 is the discharge capacity at the fifth cycle:

[0077]

number

[0078] Preferably, the schedule uses a 1C current definition of 160mA / g, and the initial charge capacity (CQ1) and discharge capacity (DQ1) are measured from 4.3V to 2.5V (Li / Li + ) or 3.7V~1.9V(In-Li / Li + ) voltage range, measured in constant current mode (CC) at a C rate of 0.1C.

[0079] In a preferred embodiment, the battery according to the present invention has a first discharge capacity of at least 180 mAh / g, more preferably at least 182 mAh / g, and most preferably at least 190 mAh / g. As will be understood by those skilled in the art, the first discharge capacity (DQ1) is measured in a constant current mode (CC) at a C rate of 0.1 C in the voltage range of 4.3 V to 2.5 V (Li / Li + ) or 3.7V~1.9V(InLi / Li + ) is measured.

[0080] In a preferred embodiment, the battery according to the present invention has an efficiency of at least 88%, preferably at least 90%, more preferably at least 92%, and most preferably at least 94%. As will be understood by those skilled in the art, the efficiency of a battery is determined by the initial charge capacity (CQ1) and discharge capacity (DQ1) between 4.3 V and 2.5 V (Li / Li + ) or 3.7V~1.9V(In-Li / Li + ) in constant current mode (CC) at a C-rate of 0.1 C. The reversible capacity efficiency (%) is obtained according to the following formula:

[0081]

number

[0082] In a preferred embodiment, the battery according to the present invention has a polarization (CV1-DV1) of less than 50 mV, preferably less than 40 mV, more preferably less than 35 mV. As will be understood by those skilled in the art, the polarization of a battery is determined where the difference between the average voltage of the initial charge (CV1) and the average voltage of the initial discharge (DV1) is used to determine the amount of polarization of the positive electrode:

[0083]

number

[0084] Preferably, to calculate CV1, the capacity in terms of power, expressed in watt-hours (Wh), is divided by CQ1 to obtain the capacity in terms of power of discharge in the first cycle (W C1 ) is calculated from the area under a plot of voltage (V) versus capacity (mAh / g). Preferably, DV1 is the capacity (W) in terms of the power of discharge in the first cycle. D1 ) divided by DQ1.

[0085] use In a fifth aspect, the present invention relates to the use in a battery of an active cathode material according to the first aspect of the invention and / or an active cathode material obtainable by the method according to the third aspect of the invention.

[0086] A preferred embodiment is the use of the cathode active material in a battery, preferably a solid-state battery, more preferably a sulfide solid-state battery, to increase the efficiency of the battery and / or increase the first discharge capacity of the battery and / or increase the rate efficiency of the battery and / or reduce the polarization of the battery.

[0087] In a sixth aspect, the present invention relates to the use of a battery according to the present invention in any one of a portable computer, a tablet, a mobile phone, an energy storage system, an electric vehicle, or a hybrid electric vehicle, preferably in an electric vehicle or a hybrid electric vehicle. [Example]

[0088] Experimental Analysis Used in the Examples The following analytical methods are used in the examples.

[0089] A) Measurement by inductively coupled plasma optical emission spectrometry (ICP-OES) The amounts of Li, Ni, Co, Mn, and B in the positive electrode active material powder were measured by inductively coupled plasma optical emission spectroscopy (ICP-OES) using an Agilent ICP 720-ES (Agilent Technologies). Two grams of powder sample was 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.

[0090] B) Measurement by X-ray photoelectron spectroscopy (XPS) The surface of the positive electrode active material is analyzed using X-ray photoelectron spectroscopy (XPS). In XPS measurements, the signal is obtained from the surface layer, i.e., the topmost few nanometers (e.g., 1 nm to 10 nm) of the sample. Therefore, all elements measured by XPS are contained in the surface layer.

[0091] XPS measurements were performed on the surface of the cathode active material powder particles using a Thermo K-α+ spectrometer. Monochromated Al Kα radiation (hν = 1486.6 eV) was used with a 400 μm spot size and a 45° measurement angle. A broad survey scan to identify the elements present on the surface was performed with a 200 eV pass energy. The C1s peak with maximum intensity (or centered) at a binding energy of 284.8 eV was used as the calibration peak position after data collection. Then, precise narrow scans were performed at 50 eV with at least 10 scans for each identified element to determine the exact surface composition.

[0092] Curve fitting was performed using CasaXPS Version 2.3.19PR1.0 (Casa Software, using Shirley-type background processing and Scofield sensitivity factors). Fitting parameters are from Table 1a. Linear GL(30) is a Gaussian / Lorentzian product formula with a 70% Gaussian line and a 30% Lorentzian line. LA(α, β, m) is an asymmetric lineshape where α and β define the tail broadening of the peak and m defines its width.

[0093] [Table 1]

[0094] For the Mn and Co peaks, constraints are set for each identified peak according to Table 1b.

[0095] [Table 2]

[0096] The surface B content determined by XPS is expressed as the mole fraction of B in the surface layer of the particle divided by the total content of Ni, Co, Mn, and B in that surface layer, and is calculated as follows:

[0097]

number

[0098] Information on the XPS peak positions can be easily obtained by reporting the area and components after fitting. The XPS graph of EX1 B is shown in Figure 1.

[0099] C) Measurement by scanning electron microscope (SEM) The structure and primary particle size of the positive electrode active material are analyzed by scanning electron microscopy (SEM). The measurements are performed at 25°C, 9.6×10 -5 This is performed using a JEOL JSM 7100F under a high vacuum environment of 100 Pa.

[0100] D) Particle size D-1) Secondary particle size analysis The particle size distribution (PSD) of the cathode active material is measured by laser diffraction particle size analysis using a Malvern Mastersizer 3000 equipped with a Hydro MV wet dispersion accessory after dispersing each powder sample in aqueous media. Sufficient sonication and agitation are applied to improve powder dispersion, and appropriate surfactants are incorporated. D50 is defined as the particle size at 50% of the cumulative volume percent distribution obtained from the Malvern Mastersizer 3000 using Hydro MV measurement.

[0101] D-2) Primary particle size analysis The diameter of the primary particles is calculated using ImageJ software (ImageJ 1.52a, US National Institutes of Health) according to the following steps: Step 1) Open a file containing a 10,000x SEM image of the cathode active material (the image was taken at the center of a secondary particle). An example of such an image is shown in Figure 2a, where the dotted line indicates the capture area corresponding to Figure 2b. Step 2) Set the scale according to the SEM magnification. Step 3) Use the polygon selection tool to draw lines that follow the edges of the primary particles for at least 50 particles. When truncating, particles at the edges of the image will be excluded. Step 4) Measure the area of ​​the drawn primary particle, which is selected from the Measurement Settings and Area boxes. Step 5) The particles are as follows:

number

[0102] E) Carbon Analysis The carbon content of the cathode active material powder is measured with a Horiba Emia-Expert carbon / sulfur analyzer. One gram of cathode active material powder is placed in a ceramic crucible inside a high-frequency induction furnace. 1.5 grams of tungsten and 0.2 grams of tin are added to the crucible as promoters. 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 analysis of CO2 and CO.

[0103] F) Rechargeable sulfide solid-state battery test F-1) Preparation of rechargeable 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-based solid electrolyte, carbon (Super-P, Timcal), and binder (RC-10, Arkema) in a weight ratio of 64.0:30.0:3.0:3.0 was mixed in butyl acetate solvent in an Ar-filled glove box. The slurry was cast onto one side of aluminum foil, and the slurry-coated foil was subsequently dried in a vacuum oven to obtain the positive electrode. The resulting positive electrode was punched to a diameter of 10 nm, with an active material loading of approximately 4 mg / cm. 2 is.

[0104] Preparation of the negative electrode: For the preparation of the negative electrode, a Li foil (3 mm diameter, 100 μm thickness) is placed centered on top of an In foil (10 nm diameter, 100 μm thickness) and pressed to form a Li-In alloy negative electrode.

[0105] Preparation of the separator: For the preparation of the separator, which also functions as a solid electrolyte in the battery, the Li-PS-based solid electrolyte is pelletized under a pressure of 250 MPa to obtain a pellet thickness of 100 μm.

[0106] Cell Assembly: The rechargeable sulfide solid-state battery is assembled in an argon-filled glove box from bottom to top: cathode with an Al current collector with a coated portion on top, separator, anode with Li side up, and Cu current collector. The stacked components are pressed together at a pressure of 250 MPa and placed in an external cage to prevent exposure to air.

[0107] F-2) Test method The test method is a conventional "constant cutoff voltage" test. Conventional cell testing in this invention follows the schedule shown in Table 2. Each cell is cycled at 60°C using a Toscat-3100 computer-controlled galvanostatic cycle station (manufactured by Toyo).

[0108] The schedule uses a 1C current definition of 160mA / g. The initial charge capacity (CQ1) and discharge capacity (DQ1) are measured from 4.3V to 2.5V (Li / Li + ) or 3.7V~1.9V(In-Li / Li + ) in constant current mode (CC) at a C-rate of 0.1 C. The reversible capacity efficiency (%) is obtained according to the following formula:

[0109]

number

[0110] The difference between the average voltage of the initial charge (CV1) and the average voltage of the initial discharge (DV1) is used to determine the amount of polarization of the positive electrode. To calculate CV1, the capacity in terms of power, expressed in watt-hours (Wh), is divided by CQ1. The capacity in terms of discharge power in the first cycle (W C1 ) is calculated from the area under a plot of voltage (V) versus capacity (mAh / g). DV1 is the capacity (W) in terms of discharge power in the first cycle. D1 ) divided by DQ1:

[0111]

number

[0112] [Table 3]

[0113] The present invention is further illustrated in the following examples.

[0114] Comparative Example 1 The positive electrode active material CEX1 is obtained by the following steps: 1) Prepare a mixture: 100.0 grams of Ni 0.625 Mn 0.175 Co 0.200 (OH)2 and 26.8 grams of LiOH are mixed uniformly to obtain a mixture. 2) Heating: The mixture obtained from step 1) is heated at 830°C for 10 hours while flowing dry air, and then cooled to room temperature to obtain the positive electrode active material CEX1.

[0115] Example 1.1 The positive electrode active material EX1.1 is obtained by the following steps: 1) Prepare a first mixture: 100.0 grams of Ni 0.625 Mn 0.175 Co 0.200 (OH)2 and 26.8 grams of LiOH are mixed uniformly to obtain a first mixture. 2) First heating: The first mixture obtained from step 1) is heated at 830°C for 10 hours while flowing dry air, and then cooled to room temperature. 3) Prepare a second mixture: 50.0 grams of the first heated material obtained from step 2) and 0.14 grams of H3BO3 are mixed uniformly to obtain a second mixture. 4) Second heating: The second mixture obtained from step 3) is heated at 350°C for 7 hours under an O2 atmosphere. The second heated material is cooled to room temperature, crushed, and sieved to obtain positive electrode active material EX1.1.

[0116] Example 1.2 Positive electrode active material EX1.2 is prepared according to the same method as EX1.1, except that 0.27 grams of H3BO3 is used in step 3).

[0117] Comparative Example 2 Prepare the positive electrode active material CEX2 according to the same method as CEX1, except that step 2) is carried out at 860°C for 10 hours.

[0118] Example 2.1 Positive electrode active material EX2.1 is prepared according to the same method as EX1.1, except that step 2) is carried out at 860°C for 10 hours.

[0119] Example 2.2 Positive electrode active material EX2.2 is prepared according to the same method as EX1.1, except that step 2) is performed at 860°C for 10 hours and 0.27 grams of H3BO3 is used in step 3).

[0120] Comparative Example 3.1 The positive electrode active material CEX3.1 is obtained by the following steps: 1) Prepare a mixture: 100.00 grams of Ni 0.92 Mn 0.03 Co 0.05 (OH)2 and 25.34 grams of anhydrous LiOH are mixed uniformly to obtain a mixture. 2) Heating: The mixture prepared in step 1) is heated at 750°C for 10 hours under an O2 atmosphere and then cooled to room temperature to obtain the positive electrode active material CEX3.1.

[0121] Comparative Example 3.2 The positive electrode active material CEX3.2 is obtained by the following steps: 1) Prepare a first mixture: 100.00 grams Ni 0.92 Mn 0.03 Co 0.05 (OH)2 and 25.34 grams of anhydrous LiOH are mixed uniformly to obtain a first mixture. 2) First heating: The first mixture obtained from step 1) is heated at 750°C for 10 hours under an O2 atmosphere and cooled to room temperature. 3) Prepare a second mixture: 100.00 grams of the first heated material obtained from step 2) and 0.37 grams of H3BO3 are mixed uniformly to obtain a second mixture. 4) Second heating: The second mixture obtained from step 3) is heated at 350°C for 6 hours under an O2 atmosphere. The second heated material is cooled to room temperature, crushed, and sieved to obtain the positive electrode active material CEX3.2.

[0122] Example 4 The positive electrode active material CEX4 is obtained by the following steps: 1) Prepare a first mixture: 100.00 grams Ni 0.625 Mn 0.175 Co0.200 (OH)2 and 26.8 grams of LiOH are mixed uniformly to obtain a first mixture. 2) First heating: The first mixture obtained from step 1) is heated at 830°C for 10 hours while flowing dry air, and then cooled to room temperature. 3) Prepare a second mixture: 100.0 grams of the first heated material obtained from step 2) and 1.14 grams of H3BO3 are mixed uniformly to obtain a second mixture. 4) Second heating: The second mixture obtained in step 3) is heated at 350°C for 6 hours under a dry air flow atmosphere. The second heated material is cooled to room temperature, crushed, and sieved to obtain the positive electrode active material CEX4.

[0123] Comparative Example 5 The positive electrode active material CEX5 is obtained by the following steps: 1) Prepare a first mixture: 100.00 grams Ni 0.625 Mn 0.175 Co 0.200 (OH)2, 0.38 grams of H3BO3, and 26.63 grams of LiOH are mixed uniformly to obtain a first mixture. 2) Heating: The mixture obtained from step 1) is heated to 830°C for 10 hours under a dry air flow, and then cooled to room temperature. The heated material is cooled to room temperature, crushed, and sieved to obtain the positive electrode active material CEX5.

[0124] [Table 4] * Composition relative to the total molar content of Ni, Co, Mn, and B **B B is the mole fraction of B relative to the total molar content of Ni, Co, Mn, and B analyzed by XPS *** B A is the mole fraction of B relative to the total molar content of Ni, Co, Mn, and B analyzed by ICP-OES **** n / a: Not applicable

[0125] [Table 5] * n / a: Not applicable

[0126] Table 3 shows the chemical composition, B B / B A The ratio, average primary particle size, and average secondary particle diameter are summarized in Table 4. Table 4 summarizes the electrochemical properties such as DQ1, efficiency, polarization (CV1-DV1), and rate efficiency of the examples and comparative examples.

[0127] The average primary particle diameters of CEX1, EX1.1, and EX1.2 were smaller than those of CEX2, EX2.1, and EX2.2. The average primary particle diameters were 270 nm to 300 nm for CEX1, EX1.1, and EX1.2, and 312 nm for CEX2, EX2.1, and EX2.2. An SEM image of CEX1 is shown in Figure 2a as a representative example. The image in Figure 2b includes lines and numbers to identify primary particles and obtain the average primary particle diameter. Rechargeable solid-state batteries containing CEX1, EX1.1, or EX1.2 had higher DQ1 than batteries containing CEX2, EX2.1, or EX2.2, and CEX1, EX1.1, and EX1.2 had smaller primary particle sizes than CEX2, EX2.1, and EX2.2.

[0128] In Table 3, B( B ) XPS analysis results of EX1.1, EX1.2, EX2.1, and EX2.2 are shown in B (B A ) and compare with the ICP-OES results. B higher than 0 B The results show that the B is present on the surface of the positive electrode active material, which is related to the XPS measurements, where the signal is obtained from the top few nanometers (e.g., 1 nm to 10 nm) of the sample. On the other hand, the B from the ICP-OES measurements A is the B content of the whole particle. Therefore, B higher than 1 B / B A The ratio of the XPS results to the ICP-OES results indicates that the B is mainly present on the surface of the positive electrode active material. B / BA A higher value corresponds to a greater amount of B present on the surface of the positive electrode active material. Figure 1 shows a representative example of an XPS spectrum showing the B1s peak of EX1.1.

[0129] The positive electrode active materials EX1.1 and EX1.2 contain 0.43 mol % and 0.85 mol % of B, respectively, based on the total molar content of Ni, Co, Mn, and B. B / B A The DQ1 values ​​were 109.6 for EX1.1 and 76.4 for EX1.2, confirming the presence of B on the surface of the particles according to the present invention. The rechargeable solid-state battery containing EX1.1 had a DQ1 value of 190.0 mAh / g, higher than that of the battery containing CEX1. The battery containing EX1.2, which contains a higher B molar content, had a maximum DQ1 value of 195.0 mAh / g among CEX1, EX1.1, and EX1.2. Furthermore, the batteries containing EX1.1 or EX1.2 each exhibited improved rate efficiency compared to the battery containing CEX1, indicating improved electrochemical stability. The positive electrode active materials EX2.1 and EX2.2 contained 0.47 mol% and 0.90 mol% B, respectively, based on the total molar content of Ni, Co, Mn, and B. It was observed that rechargeable solid-state batteries containing EX2.1 or EX2.2 have higher DQ1 values ​​and improved rate efficiency compared to batteries containing CEX2, where B B / B A The value was 97.1 for EX2.2 and 98.1 for EX2.2, indicating the presence of B on the surface of the particles.

[0130] Positive electrode active material CEX3.2 B B / B AThe value was 91.9, indicating the presence of B on the particle surface, whereas CEX3.1 does not contain B on the particle surface. Rechargeable solid-state batteries containing EX1.1, EX1.2, EX2.1, or EX2.2 have improved efficiency and CV1-DV1 compared to batteries containing CEX3.2. It was observed that the positive electrode material according to the present invention containing Ni in the range of 50.0 mol% to 75.0 mol% relative to the total amount of Ni, Co, Mn, B, and Q can result in significantly improved DQ1 and / or improved CV1-DV1 and / or improved reversible capacity efficiency.

[0131] The positive electrode active materials EX4 and CEX5 contained 1.74 mol% and 0.59 mol% B, respectively, based on the total molar content of Ni, Co, Mn, and B. EX4 contained 58.7 mol% B. B / B A CEX5 has a B value of 41.9 B / B A The average primary particle diameters of EX4 and CEX5 were calculated by analyzing SEM images to be 239 nm and 208 nm, respectively. The rechargeable solid-state battery containing CEX5 has a significantly lower DQ1 compared to the batteries containing EX1.1 or EX1.2, and both the efficiency and polarization values ​​CV1-DV1 are improved in the batteries containing EX1.1 or EX1.2. This is due to the fact that B B / B A This suggests that a rechargeable solid state containing a positive electrode active material with a B value higher than 43.0 has improved electrochemical properties.

[0132] Furthermore, the average primary particle size is in the range of 100 nm to 400 nm, and B is more than 40.0, preferably more than 45.0, more preferably more than 50.0. B / B A It is clearly observed that the object of the present invention, which is to provide a positive electrode active material having improved DQ1 and improved rate efficiency, can be achieved by combining

Claims

1. A cathode active material for a solid-state battery comprising Li, M′, and oxygen, wherein M′ is: Ni with a content x of 50.0≦x≦75.0 mol% relative to M′; Co with a content y of 0.0≦y≦30.0 mol% relative to M′; Mn with a content z of 0.0≦z≦30.0 mol% relative to M′; B with a content b of 0.01≦b≦2.0 mol% relative to M′; Q is an element other than Li, O, Ni, Co, Mn, and B, and Q has a content q of 0.0≦q≦2.0 mol% relative to M′; x, y, z, b, and q are measured by ICP-OES; x+y+z+b+q is 100.0 mol%, The positive electrode active material has a content B defined as b / (x+y+z+b) Ａ B of The positive electrode active material has a content of B Ｂ B Ｂ was determined by XPS analysis, and B Ｂ is expressed as the mole fraction B compared to the sum of the mole fractions of Ni, Mn, Co, and B, as measured by XPS analysis, and B Ｂ / B Ａ The ratio of is greater than 45.0, the positive electrode active material includes secondary particles including a plurality of primary particles, The positive electrode active material, wherein the primary particles have an average diameter of 100 nm to 400 nm as determined by measuring the primary particle size in an image taken by SEM.

2. The ratio B Ｂ / B Ａ is >50.0, preferably B Ｂ / B Ａ is >70.0, and most preferably B Ｂ / B Ａ 2. The positive electrode active material of claim 1, wherein R is > 90.

0.

3. The ratio B Ｂ / B Ａ 3. The cathode active material according to claim 1, wherein R is <1000.0, preferably <200.0, more preferably <125.

0.

4. 4. The positive electrode active material according to claim 1, wherein x≧55.0 mol%, preferably x≧58.0 mol%, more preferably x≧60.0 mol%.

5. 5. The positive electrode active material according to claim 1, wherein x≦70.0 mol%, preferably x≦68.0 mol%, more preferably x≦65.0 mol%.

6. 6. The positive electrode active material according to claim 1, wherein the content of Co is 0.0 mol%<y≦28.0 mol%, preferably 10.0 mol%≦y≦25.0 mol%, more preferably 18.0 mol%≦y≦22.0 mol%.

7. 7. The positive electrode active material according to claim 1, wherein the Mn content is 0.0 mol%<z≦28.0 mol%, preferably 10.0 mol%≦z≦25.0 mol%, more preferably 15.0 mol%≦z≦20.0 mol%.

8. 8. The positive electrode active material according to claim 1, wherein 0.01 mol%≦b≦1.5 mol%, preferably 0.05 mol%≦b≦1.25 mol%, more preferably 0.1 mol%≦b≦1.1 mol%, and most preferably 0.2 mol%≦b≦1.0 mol%.

9. 9. The cathode active material according to claim 1, wherein the median diameter D50 of the secondary particles is 12 to 20 μm as determined by laser diffraction particle size analysis.

10. 10. The positive electrode active material according to claim 1, wherein the primary particles have an average diameter of 150 to 375 nm, preferably 200 to 350 nm, more preferably 250 to 325 nm.

11. The positive electrode active material according to any one of claims 1 to 10, wherein the Li / M' ratio (mol / mol) is in the range of 0.90 to 1.10, preferably in the range of 0.92 to 1.08, and more preferably in the range of 0.95 to 1.

05.

12. 12. The positive electrode active material according to claim 1, wherein Q is at least one element selected from the group consisting of Al, Ti, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr, preferably Al, Ti, Cr, Nb, S, Si, Y, Zr, and W, more preferably Al, Ti, Nb, Zr, and W.

13. A method for producing a positive electrode active material for a solid state battery according to any one of claims 1 to 12, comprising: Preparing a lithium transition metal based oxide compound; mixing the lithium transition metal-based oxide compound with a B source to obtain a mixture; and heating the mixture at a temperature of 250° C. to less than 500° C. for 1 hour to 20 hours to obtain a positive electrode active material powder.

14. 14. The method of claim 13, wherein the heating of the mixture is carried out under an oxidizing atmosphere.

15. A solid state battery comprising the positive electrode active material according to any one of claims 1 to 12.

16. 16. The solid-state battery of claim 15, wherein the solid-state battery comprises a sulfide-based solid electrolyte.

17. 17. Use of the solid state battery according to claim 15 or 16 in any one of a portable computer, a tablet, a mobile phone, an energy storage system, an electric vehicle or a hybrid electric vehicle, preferably in an electric vehicle or a hybrid electric vehicle.

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