Positive electrode active material and method for manufacturing positive electrode active material

Abstract

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 Ti. The present inventors have surprisingly found that the positive electrode active material of the present invention significantly increases the cycle efficiency of the battery, in particular a sulfide solid state battery.

Description

Technical Field and Background Art

[0001] The present invention relates to a positive electrode active material for a solid-state battery, wherein the positive electrode active material contains Li, M' and oxygen, and M' includes Ti. The present invention also relates to a method for manufacturing the positive electrode active material, a solid-state battery including the positive electrode active material, and the use of the solid-state battery.

[0002] With the rapid progress in the development of small and lightweight electronic products, electronic devices, communication devices, etc., and the widespread emergence of the demand for electric vehicles in terms of environmental issues, there is a need to improve the performance of secondary batteries used as power sources for these products. Among these secondary batteries, lithium secondary batteries have become the focus of 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 the use or discharge of a secondary battery, lithium ions are removed from the anode, transported through the electrolyte, and inserted into the cathode, while electrons flow through the external circuit to provide electrical work.

[0004] Commonly used cathode active materials are lithium transition metal oxides. During the charging and / or discharging of a lithium battery, the delithiated cathode active material can react slowly with a non-aqueous electrolyte or a solid electrolyte, resulting in a gradual deterioration of the electrochemical performance of the lithium battery using such a cathode active material. It has been demonstrated that treating the cathode active material with a metal such as Ti (i.e., applying a thin metal surface layer on the cathode active material, resulting in an increase in the amount of the metal in the surface layer) causes the cathode active material to exhibit higher stability compared to its counterpart without such a surface layer.

[0005] CN109742376A discloses a Ti-treated positive electrode active material containing 83% nickel, 5% manganese, and 12% cobalt, wherein the positive electrode active material is obtained after dry treatment of the positive electrode active material with 0.1% by weight of TiO2.

[0006] US2019 / 0006662A1 contemplates a Ti-treated positive electrode active material containing 60% nickel, 20% manganese, and 20% cobalt, wherein the treated positive electrode active material is obtained after treating the positive electrode active material with titanium butoxide in ethanol.

[0007] Disadvantages associated with these known Ti-treated positive electrode active materials are the low cycle efficiency and / or low initial discharge capacity of the batteries containing the Ti-treated positive electrode active materials. Therefore, there is still a need to provide a positive electrode active material having an enriched amount of Ti in the surface layer to improve the cycle efficiency of the resulting batteries.

[0008] An object of the present invention is to provide a positive electrode active material having an enriched amount of Ti in the surface layer, which improves the cycle efficiency of the resulting battery.

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

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

[0011] Another object of the present invention is to provide the use of the battery. Summary of the Invention

[0012] In a first aspect, the object of the present invention is achieved by providing a positive electrode active material for a solid-state battery, wherein the positive electrode active material comprises Li, M', and oxygen, wherein M' comprises:

[0013] - Ni with a content of x, where 55.0 mol% ≤ x ≤ 98.0 mol%,

[0014] - Mn with a content of y, where 0.0 mol% ≤ y ≤ 45.0 mol%,

[0015] - Co with a content of z, where 0.0 mol% ≤ z ≤ 45.0 mol%,

[0016] - D with a content of a, where 0.0 mol% ≤ a ≤ 5.0 mol%, where D is at least one other element other than Li, Ni, Mn, Co, Ti, and O,

[0017] - Ti with a content of b, where 0.01 mol% ≤ b ≤ 5.0 mol%,

[0018] - where x, y, z, a, and b are measured by ICP-OES,

[0019] - where x + y + z + a + b is 100.0 mol%,

[0020] where the positive electrode active material has an enriched amount of Ti in the surface layer.

[0021] The inventors have surprisingly found that the positive electrode active material of the present invention significantly improves the cycle efficiency of the battery, especially a sulfide solid-state battery. In addition, the positive electrode active material of the present invention shows a high first discharge capacity. Preferably, the treated positive electrode active material comprising polycrystalline particles is superior to the corresponding single-crystalline positive electrode active material or the positive electrode active material comprising single particles and / or secondary particles as defined herein in terms of cycle efficiency.

[0022] Without wishing to be bound by any theory, the inventors believe that in order to obtain a lithium titanium oxide compound as an effective treatment for a positive electrode active material, it is necessary to add a Li source and a Ti source together as treatment agents.

[0023] On the other hand, the present invention provides a method for manufacturing the positive electrode active material.

[0024] On the other hand, the present invention provides a battery comprising the positive electrode active material.

[0025] On the other hand, the present invention provides the use of the battery. Detailed Description

[0026] In the following detailed description, preferred embodiments are described in detail to practice the present invention. Although the present invention is described with reference to these specific preferred embodiments, it should be understood that the present invention is not limited to these preferred embodiments. On the contrary, the present invention includes many alternatives, modifications and equivalent forms, which will become apparent by considering the following detailed description and the drawings.

[0027] As used herein and in the claims, the term "comprising" should not be construed as limited to the manner listed thereafter; it does not exclude other elements or steps. It is to be interpreted as specifying the presence of the stated features, integers, steps or components, but not excluding 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 component A and component B" should not be limited to a composition consisting only of components A and B. This means that the only relevant components of the composition with respect to the present invention are A and B. Thus, the terms "comprising" and "including" encompass the more restrictive terms "consisting essentially of" and "consisting of".

[0028] As used herein and in the claims, the term "solid-state battery" refers to a battery cell or battery that includes only solid-state components or substantially solid-state components such as solid electrodes (e.g., an anode and a cathode) and a solid electrolyte.

[0029] As used herein and in the claims, the term "positive electrode active material" (also referred to as cathode active material) is defined as a material that is electrochemically active in the positive electrode or cathode. For an active material, it must be understood that the material is capable of capturing and releasing Li ions when subjected to a voltage change over a predetermined period of time.

[0030] As used herein and in the claims, the term "slurry" refers to a mixture, premix, and / or blend of solid particles suspended in a liquid, such as water, alcohol, or a combination thereof. When the term "slurry" is used, the solid particles are not dissolved or are only partially dissolved in the liquid. For example, a slurry of a lithium transition metal-based oxide compound is a suspension of the particles that make up the lithium transition metal-based oxide compound in a liquid. In other words, the particles that make up the lithium transition metal-based oxide compound are not dissolved or are only partially dissolved in the liquid.

[0031] In the context of the present invention, the terms "solid" and "liquid" shall be considered as solids and liquids under standard conditions of temperature and pressure as defined by IUPAC, unless otherwise defined. Accordingly, the boiling point and melting point shall be considered to be the boiling point and melting point at standard atmospheric pressure, i.e., 101325 Pa.

[0032] Positive electrode active material

[0033] 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 contains Li, M', and oxygen, and wherein M' includes:

[0034] - Ni in an amount x, where 55.0 mol% ≤ x ≤ 98.0 mol%,

[0035] - Mn in an amount y, where 0.0 mol% ≤ y ≤ 45.0 mol%,

[0036] - Co in an amount z, where 0.0 mol% ≤ z ≤ 45.0 mol%,

[0037] - D in an amount a, where 0.0 mol% ≤ a ≤ 5.0 mol%, where D is at least one other element other than Li, Ni, Mn, Co, Ti, and O,

[0038] - Ti in an amount b, where 0.01 mol% ≤ b ≤ 5.0 mol%,

[0039] - where x, y, z, a, and b are measured by ICP-OES,

[0040] - where x + y + z + a + b is 100.0 mol%.

[0041] A specific preferred embodiment is the positive electrode active material of the present invention, where the content x of Ni ≥ 60.0 mol%, preferably x ≥ 61.0 mol%, more preferably x ≥ 62.0 mol%. In a specific preferred embodiment, the content x of Ni ≤ 90.0 mol%, preferably x ≤ 88 mol%, and more preferably x ≤ 85.0 mol%. A more preferred specific embodiment is the positive electrode active material of the present invention, where the content x of Ni is between 55.0 mol% ≤ x ≤ 75.0 mol%, preferably 60.0 mol% ≤ x ≤ 70.0 mol%, more preferably 62.0 mol% ≤ x ≤ 68.0 mol%. Another more preferred specific embodiment is the positive electrode active material of the present invention, where the content x of Ni is between 60.0 mol% ≤ x ≤ 90.0 mol%, preferably 61.0 mol% ≤ x ≤ 88.0 mol%, more preferably 62.0 mol% ≤ x ≤ 85.0 mol%.

[0042] A more preferred specific embodiment is the positive electrode active material of the present invention, where the content x of Ni > 75.0 mol%, preferably x ≥ 76.0 mol%, more preferably x ≥ 77.0 mol%. A more preferred specific embodiment is the positive electrode active material of the present invention, where the content x of Ni is between x ≤ 95.0 mol%, preferably ≤ x ≤ 90.0 mol%, more preferably x ≤ 88.0 mol%. A more preferred specific embodiment is the positive electrode active material of the present invention, where the content x of Ni is between 75.0 mol% < x ≤ 95.0 mol%, preferably 76.0 mol% ≤ x ≤ 90.0 mol%, more preferably 77.0 mol% ≤ x ≤ 88.0 mol%.

[0043] As understood by those skilled in the art, the amounts of Li and M' in the positive electrode active material, preferably the amounts of Li, Ni, Mn, Co, D, and Ti, are measured by inductively coupled plasma optical emission spectrometry (ICP-OES). For example, but not limited to the present invention, an Agilent ICP 720-ES is used in the ICP-OES analysis.

[0044] A preferred embodiment is the positive electrode active material of the present invention, wherein the content y of Mn > 0.0 mol%, preferably y ≥ 3.0 mol%, more preferably y ≥ 5.0 mol%. In a preferred embodiment, the content is y ≤ 30.0 mol%, preferably y ≤ 20.0 mol%, and more preferably y ≤ 15.0 mol%. In a preferred embodiment, the content of Mn is 0.0 mol% < y ≤ 30.0 mol%, preferably 3.0 mol% ≤ y ≤ 20.0 mol%, more preferably 5.0 mol% ≤ y ≤ 15.0 mol%.

[0045] A preferred embodiment is the positive electrode active material of the present invention, wherein the content z of Co > 0.0 mol%, preferably z ≥ 1.0 mol%, more preferably z ≥ 3.0 mol%. In a preferred embodiment, the content is z ≤ 30.0 mol%, preferably z ≤ 20.0 mol%, more preferably z ≤ 15.0 mol%. In a preferred embodiment, the content is 0.0 mol% < z ≤ 30.0 mol%, preferably 1.0 mol% ≤ z ≤ 20.0 mol%, more preferably 3.0 mol% ≤ z ≤ 15.0 mol%.

[0046] As is known to those skilled in the art, the positive electrode active material of the present invention may contain impurities or be doped or added to the surface layer, so as to obtain an overall positive electrode active material containing one or more elements other than Li, Ni, Mn, Co, Ti, and O, which is reflected in the parameter "D" used herein. A preferred embodiment is the positive electrode active material containing D according to the present invention, wherein D is at least one element selected from the following elements: Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr; preferably Al, B, Cr, Nb, S, Si, Y, Zr, and W; more preferably B, Nb, Zr, and W.

[0047] A preferred embodiment is the positive electrode active material according to the present invention, wherein the content a of Co > 0.0 mol%, preferably a ≥ 0.25 mol%, more preferably a ≥ 0.5 mol%. In a preferred embodiment, the content a ≤ 2.0 mol%, preferably a ≤ 1.75 mol%, 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%, more preferably 0.5 mol% ≤ a ≤ 1.5 mol%.

[0048] A preferred embodiment is the positive electrode active material of the present invention, wherein the content b of Ti is b ≥ 0.01 mol%, preferably b ≥ 0.05 mol%, more preferably b ≥ 0.10 mol%. In a preferred embodiment, b ≤ 2.5 mol%, preferably b ≤ 2.0 mol%, more preferably b ≤ 1.0 mol%. In a preferred embodiment, 0.01 mol% ≤ b ≤ 2.5 mol%, preferably 0.05 mol% ≤ b ≤ 2.0 mol%, more preferably 0.10 mol% ≤ b ≤ 1.0 mol%.

[0049] A preferred embodiment is the positive electrode active material of the present invention, and the carbon content of the positive electrode active material is higher than 0.020 wt.%, preferably higher than 0.030 wt.%, more preferably higher than 0.045 wt.% based on the total weight of the positive electrode active material. A preferred embodiment is the positive electrode active material of the present invention, and the carbon content of the positive electrode active material is less than 0.10 wt.%, preferably less than 0.080 wt.%, more preferably less than 0.065 wt.% based on the total weight of the positive electrode active material. A preferred embodiment is the positive electrode active material of the present invention, and the carbon content of the positive electrode active material is in the range of 0.020 wt.% to 0.10 wt.%, preferably in the range of 0.030 wt.% to 0.080 wt.%, more preferably in the range of 0.045 wt.% to 0.065 wt.% based on the total weight of the positive electrode active material. As understood by those skilled in the art, the carbon content can be analyzed using a carbon analyzer. For example, but not limited to the present invention, a Horiba EmiaExpert carbon / sulfur analyzer can be used.

[0050] A preferred embodiment is the positive electrode active material of the present invention, and the positive electrode active material has a Li / M' ratio, preferably a Li / (Ni + Mn + Co) ratio > 0.90, preferably > 0.92, more preferably > 0.95. A preferred embodiment is the positive electrode active material of the present invention, and the positive electrode active material has a Li / M' ratio, preferably a Li / (Ni + Mn + Co) ratio < 1.10, preferably < 1.08, more preferably < 1.05. A preferred embodiment is the positive electrode active material of the present invention, and the positive electrode active material has a Li / M' ratio, preferably a Li / (Ni + Mn + Co) ratio in the range of 0.90 to 1.10, preferably in the range of 0.92 to 1.08, more preferably in the range of 0.95 to 1.05. As understood by those skilled in the art, the Li / M' ratio, preferably the Li / (Ni + Mn + Co) ratio, is a molar ratio (mol / mol).

[0051] In a very preferred embodiment, the positive electrode active material is according to the formula Li w2 Ni x2 Mn y2 Co z2 D a2 Ti b2 O 2 , where

[0052] 0.90 ≤ w2 ≤ 1.10, preferably 0.92 ≤ w2 ≤ 1.1, more preferably 0.95 ≤ w2 ≤ 1.05;

[0053] 0.55 ≤ x2 ≤ 0.98, preferably 0.60 ≤ x2 ≤ 0.88, more preferably 0.65 ≤ x2 ≤ 0.85;

[0054] 0.0 ≤ y2 ≤ 0.45, preferably 0.03 ≤ y2 ≤ 0.20, more preferably 0.05 ≤ y2 ≤ 0.10;

[0055] 0.0 ≤ z2 ≤ 0.45, preferably 0.03 ≤ z2 ≤ 0.20, more preferably 0.05 ≤ z2 ≤ 0.10;

[0056] 0.0 ≤ a2 ≤ 0.02, preferably 0.025 ≤ a2 ≤ 0.0175, more preferably 0.005 ≤ a2 ≤0.015;

[0057] 0.001 ≤ b2 ≤0.025, preferably 0.005 ≤ b2 ≤ 0.02, more preferably 0.01 ≤ b2 ≤ 0.1,

[0058] where x2 + y2 + z2 + a2 + b2 = 1.00.

[0059] In a very preferred embodiment, 0.99 ≤ w2 ≤ 1.01, preferably w2 is about 1.00.

[0060] In a very preferred embodiment, 0.75 ≤ x2 ≤ 0.85, preferably 0.80 ≤ x2 ≤ 0.85, more preferably x2 is about 0.83.

[0061] In a very preferred embodiment, 0.06 ≤ y2 ≤ 0.08, preferably y2 is about 0.07.

[0062] In a very preferred embodiment, 0.08 ≤ z2 ≤ 0.10, preferably z2 is about 0.09.

[0063] In a highly preferred embodiment, 0.0 ≤ a2 ≤ 0.01, preferably a2 is about 0.0.

[0064] In a highly preferred embodiment, 0.01 ≤ b2 ≤ 0.05, preferably b2 is about 0.01.

[0065] Surface layer

[0066] A preferred embodiment relates to the positive electrode active material of the present invention, wherein the Ti content Ti of the positive electrode active material A is defined as , and wherein the Ti content of the positive electrode active material is Ti B , where Ti B is determined by XPS analysis, where Ti B is expressed as the mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, and Ti measured by XPS analysis, where the ratio Ti B / Ti A > 25.0.

[0067] A more preferred embodiment relates to the positive electrode active material of the present invention, wherein the ratio Ti B / Ti A > 50.0, preferably the ratio Ti B / Ti A > 75.0, more preferably Ti B / Ti A > 100.0, even more preferably the ratio Ti B / Ti A > 125.0, most preferably the ratio Ti B / Ti A > 150.0.

[0068] A more preferred embodiment relates to the positive electrode active material of the present invention, wherein the ratio Ti B / Ti A < 1250.0, preferably the ratio Ti B / Ti A < 1000.0, more preferably Ti B / Ti A < 750.0, even more preferably the ratio Ti B / Ti A <500.0, most preferably the ratio Ti B / Ti A < 250.0.

[0069] A more preferred embodiment relates to the positive electrode active material of the present invention, wherein the ratio of Ti B / Ti A is in the range of 50.0 to 1000, preferably the ratio of Ti B / Ti A is in the range of 75.0 to 500.0, and more preferably the ratio of Ti B / Ti A is in the range of 100.0 to 250.0.

[0070] In the context of the present invention, Ti B is the molar fraction of Ti measured in the region of the particles of the positive electrode active material according to the present invention, and this region is defined between a first point on the outer edge of the particles and a second point at a certain distance from the first point. The distance separating the first point from the second point is equal to the penetration depth of the XPS, and the penetration depth D is included between 1.0 nm and 10.0 nm. In particular, the penetration depth is the distance along the axis perpendicular to the virtual line tangent to the outer edge and passing through the first point.

[0071] In the framework of the present invention, the outer edge of the particle is the boundary or outer limit that differentiates the particle from its external environment. Therefore, XPS analysis provides the atomic content of the elements in the uppermost layer of the particle, where the penetration depth from the outer boundary of the particle is about 10.0 nm. The outer boundary of the particle is also referred to as the "surface". For example, but not limited to the present invention, XPS analysis is performed using a Thermo K-α+ spectrometer (Thermo Scientific).

[0072] In the framework of the present invention, at% represents atomic percentage. At% or "atomic percentage" in the given elemental expression of concentration means what percentage of all the atoms in the compound involved are the atoms of the said element. In addition, in the framework of the present invention, the label at% is equivalent to mol% or "molar percentage".

[0073] As understood by those skilled in the art, the defined Ti B / Ti A refers to the positive electrode active material having an enriched amount of Ti in the surface layer of the positive electrode active material of the present invention. The surface layer of the positive electrode active material is the uppermost 1 nm to 10 nm of the positive electrode active material. In other words, the positive electrode active material of the present invention includes a surface layer of Ti.

[0074] In the context of the present invention, the positive electrode active material may include a first surface layer containing D, where D is at least one element selected from the group consisting of: Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr; preferably Al, B, Cr, Nb, S, Si, Y, Zr, and W; more preferably B, Nb, Zr, and W, where the surface layer of Ti may be placed on the first surface layer and / or the first surface layer may be placed on the surface layer of Ti and / or the positive electrode active layer may include a mixed surface layer including the surface layer of Ti and the first surface layer.

[0075] A preferred embodiment relates to the positive electrode active material of the present invention, where the positive electrode active material has a Li content of Li A , where Li A is determined by ICP analysis, where Li A is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, and Ti measured by ICP analysis, and where the positive electrode active material has a Li content of Li B , where Li B is determined by XPS analysis, where Li B is expressed as a mole fraction compared to the sum of the mole ratios of Co, Mn, Ni, and Ti measured by XPS analysis.

[0076] A preferred embodiment relates to the positive electrode active material of the present invention, where the ratio Li B / Li A > 1.0.

[0077] A more preferred embodiment relates to the positive electrode active material of the present invention, where the ratio Li B / Li A > 2.0, preferably the ratio Li B / Li A > 2.5, more preferably the ratio Li B / Li A > 3.0, even more preferably Li B / Li A > 3.5, most preferably the ratio Li B / Li A > 4.0.

[0078] A more preferred embodiment relates to the positive electrode active material of the present invention, where the ratio Li B / Li A < 60.0, preferably the ratio Li B / Li A< 45.0, more preferably Li B / Li A < 30.0, even more preferably the ratio of Li B / Li A < 20.0, most preferably the ratio of Li B / Li A < 10.0.

[0079] A more preferred embodiment relates to the positive electrode active material of the present invention, wherein the ratio of Li B / Li A is between 2.0 and 60.0, preferably the ratio of Li B / Li A is between 3.0 and 30.0, even more preferably the ratio of Li B / Li A is between 4.0 and 10.0.

[0080] In the context of the present invention, Li B is the mole fraction of Li measured in the region of the particles of the positive electrode active material according to the present invention, and this region is defined between a first point on the outer edge of the particles and a second point at a certain distance from the first point. The distance separating the first point from the second point is equal to the penetration depth of the XPS, and the penetration depth D is included between 1.0 nm and 10.0 nm. In particular, the penetration depth is the distance along the axis perpendicular to the virtual line tangent to the outer edge and passing through the first point.

[0081] As understood by those skilled in the art, the defined ratio of Li B / Li A refers to the positive electrode active material having an enriched amount of Ti in the surface layer of the positive electrode active material of the present invention. The surface layer of the positive electrode active material is the uppermost 1 nm to 10 nm of the positive electrode active material. In other words, the positive electrode active material of the present invention includes a surface layer of Li.

[0082] In the context of the present invention, the positive electrode active material may include a second surface layer, and this second surface layer contains D, where D is at least one element selected from the following elements: Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr; preferably Al, B, Cr, Nb, S, Si, Y, Zr, and W; more preferably B, NB, Zr, and W, and the surface layer of Li may be placed on this second surface layer and / or this second surface layer may be placed on the surface layer of Li and / or the positive electrode active layer may include a mixed surface layer, and this mixed surface layer includes the surface layer of Li and the second surface layer.

[0083] Preferred embodiments relate to the positive electrode active material of the present invention, wherein the ratio of Li B / Ti A > 1.0.

[0084] More preferred embodiments relate to the positive electrode active material of the present invention, wherein the ratio of Li B / Ti B > 2.0, preferably the ratio of Li B / Ti B > 3.0, more preferably the ratio of Li B / Ti B > 4.0, even more preferably Li B / Ti B > 5.0, most preferably the ratio of Li B / Ti B > 6.0.

[0085] More preferred embodiments relate to the positive electrode active material of the present invention, wherein the ratio of Li B / Ti B < 100.0, preferably the ratio of Li B / Ti B < 60.0, more preferably the ratio of Li B / Ti B < 45.0, even more preferably the ratio of Li B / Ti B < 30.0, most preferably the ratio of Li B / Ti B < 10.0.

[0086] More preferred embodiments relate to the positive electrode active material of the present invention, wherein the ratio of Li B / Ti B is between 2.0 and 60.0, preferably the ratio of Li B / Ti B is between 4.0 and 30.0, more preferably the ratio of Li B / Ti B is between 6.0 and 10.0.

[0087] As understood by those skilled in the art, the defined ratio of Li B / Ti B refers to the positive electrode active material having a specific amount of Li and Ti in the surface layer of the positive electrode active material of the present invention. The surface layer of the positive electrode active material is the uppermost 1 nm to 10 nm of the positive electrode active material.

[0088] In the context of the present invention, the positive electrode active material may include a third surface layer containing D, where D is at least one element selected from the group consisting of: Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr; preferably Al, B, Cr, Nb, S, Si, Y, Zr, and W; more preferably B, Nb, Zr, and W, where the surface layer of Ti and Li may be placed on the third surface layer and / or the third surface layer may be placed on the surface layer of Ti and Li and / or the positive electrode active layer may include a mixed surface layer including the surface layer of Ti and Li and the third surface layer.

[0089] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0090] - Ratio of Ti B / Ti A > 25.0, and

[0091] - Ratio of Li B / Li A > 1.0.

[0092] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0093] - Ratio of Ti B / Ti A > 50.0, preferably the ratio of Ti B / Ti A > 75.0, more preferably the ratio of Ti B / Ti A > 100.0; and

[0094] - Ratio of Li B / Li A > 2.0, preferably the ratio of Li B / Li A > 3.0, more preferably the ratio of Li B / Li A > 4.0.

[0095] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0096] - Ratio of Ti B / Ti A < 1000.0, preferably the ratio of Ti B / Ti A < 500.0, more preferably the ratio of Ti B / TiA <250.0; and

[0097] - ratio of Li B / Li A < 60.0, preferably the ratio of Li B / Li A < 30.0, more preferably the ratio of Li B / Li A <10.0.

[0098] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0099] - ratio of Ti B / Ti A is in the range of 50.0 to 1000, preferably the ratio of Ti B / Ti A is in the range of 75.0 to 500.0, more preferably the ratio of Ti B / Ti A is in the range of 100.0 to 250.0; and

[0100] - ratio of Li B / Li A is between 2.0 and 60.0, preferably the ratio of Li B / Li A is between 3.0 and 30.0, more preferably the ratio of Li B / Li A is between 4.0 and 10.0.

[0101] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0102] - ratio of Ti B / Ti A > 25.0, and

[0103] - ratio of Li B / Ti B > 1.0.

[0104] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0105] - ratio of Ti B / Ti A > 50.0, preferably the ratio of Ti B / Ti A > 75.0, more preferably the ratio of Ti B / Ti A> 100.0; and

[0106] - Ratio of Li B / Ti B > 2.0, preferably the ratio of Li B / Ti B > 4.0, most preferably the ratio of Li B / Ti B > 6.0.

[0107] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0108] - Ratio of Ti B / Ti A < 1000.0, preferably the ratio of Ti B / Ti A < 500.0, more preferably the ratio of Ti B / Ti A < 250.0; and

[0109] - Ratio of Li B / Ti B < 100.0, preferably the ratio of Li B / Ti B < 30.0, more preferably the ratio of Li B / Ti B < 10.0.

[0110] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0111] - Ratio of Ti B / Ti A In the range of 50.0 to 1000, preferably the ratio of Ti B / Ti A In the range of 75.0 to 500.0, and more preferably the ratio of Ti B / Ti A In the range of 100.0 to 250.0; and

[0112] - Ratio of Li B / Li A Between 2.0 and 60.0, preferably the ratio of Li B / Li A Between 3.0 and 30.0, more preferably the ratio of Li B / Li A Between 4.0 and 10.0.

[0113] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0114] - The ratio of Li B / Li A > 1.0, and

[0115] - The ratio of Li B / Ti B > 1.0.

[0116] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0117] - The ratio of Li B / Li A > 2.0, preferably the ratio of Li B / Li A > 3.0, more preferably the ratio of Li B / Li A > 4.0; and

[0118] - The ratio of Li B / Ti B > 2.0, preferably the ratio of Li B / Ti B > 4.0, more preferably the ratio of Li B / Ti B > 6.0.

[0119] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0120] - The ratio of Li B / Li A < 60.0, preferably the ratio of Li B / Li A < 30.0, more preferably the ratio of Li B / Li A <10.0; and

[0121] - The ratio of Li B / Ti B < 100.0, preferably the ratio of Li B / Ti B < 30.0, more preferably the ratio of Li B / Ti B <10.0.

[0122] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0123] - The ratio of LiB / Li A Between 2.0 and 60.0, preferably the ratio of Li B / Li A Between 3.0 and 30.0, more preferably the ratio of Li B / Li A Between 4.0 and 10.0; and

[0124] - ratio of Li B / Li A Between 2.0 and 60.0, preferably the ratio of Li B / Li A Between 3.0 and 30.0, more preferably the ratio of Li B / Li A Between 4.0 and 10.0.

[0125] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0126] - ratio of Ti B / Ti A > 25.0;

[0127] - ratio of Li B / Li A > 1.0, and

[0128] - ratio of Li B / Ti B > 1.0.

[0129] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0130] - ratio of Ti B / Ti A > 50.0, preferably the ratio of Ti B / Ti A > 75.0, more preferably the ratio of Ti B / Ti A >100.0;

[0131] - ratio of Li B / Li A > 2.0, preferably the ratio of Li B / Li A > 3.0, more preferably the ratio of Li B / Li A > 4.0; and

[0132] - ratio of Li B / Ti B > 2.0, preferably the ratio of Li B / Ti B > 4.0, more preferably the ratio of Li B / Ti B > 6.0.

[0133] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0134] - ratio of Ti B / Ti A < 1000.0, preferably the ratio of Ti B / Ti A < 500.0, more preferably the ratio of Ti B / Ti A < 250.0;

[0135] - ratio of Li B / Li A < 60.0, preferably the ratio of Li B / Li A < 30.0, more preferably the ratio of Li B / Li A < 10.0; and

[0136] - ratio of Li B / Ti B < 100.0, preferably the ratio of Li B / Ti B < 30.0, more preferably the ratio of Li B / Ti B < 10.0.

[0137] Certain preferred embodiments relate to the positive electrode active material of the present invention, wherein:

[0138] - ratio of Ti B / Ti A within the range of 50.0 to 1000, preferably the ratio of Ti B / Ti A within the range of 75.0 to 500.0, more preferably the ratio of Ti B / Ti A within the range of 100.0 to 250.0;

[0139] - ratio of Li B / Li A between 2.0 and 60.0, preferably the ratio of Li B / Li ABetween 3.0 and 30.0, more preferably the ratio Li B / Li A Between 4.0 and 10.0; and

[0140] - ratio Li B / Ti B Between 2.0 and 60.0, preferably the ratio Li B / Li A Between 3.0 and 30.0, more preferably the ratio Li B / Li A Between 4.0 and 10.0.

[0141] Morphology

[0142] In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles. In the context of the present invention, a particle is considered to be single crystal if, when observed by scanning electron microscopy (SEM) or transmission electron microscopy (TEM), preferably by observing the grain boundaries of the particles, the particle consists of only one grain or at most five, preferably at most three grains. A grain boundary is defined as the interface between two grains in a particle, and preferably, the atomic planes of the two grains are aligned in different orientations and meet as a crystallographic discontinuity plane. As understood by those skilled in the art and in the context of the present invention, the positive electrode active material comprises single crystal particles, wherein in the SEM image, at least 45 μm × at least 60 μm (i.e., at least 2700 µm 2 ), preferably at least 100 µm × 100 µm (i.e., at least 10,000 µm 2 ), 80% or more of the particles in the field of view are single crystal. To determine single crystal particles, grains with a maximum linear dimension observed by SEM less than 20% of the median particle size D50 determined by laser diffraction are ignored. This avoids particles that are essentially single crystal but may have a few very small other grains deposited thereon from being misidentified as not single crystal.

[0143] In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, and the carbon content of the single crystal particles is higher than 0.020 wt.%, preferably higher than 0.025 wt.%, more preferably higher than 0.030 wt.% based on the total weight of the positive electrode active material. In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, and the carbon content of the single crystal particles is less than 0.050 wt.%, preferably less than 0.040 wt.%, more preferably less than 0.035 wt.% based on the total weight of the positive electrode active material. In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, and the carbon content of the single crystal particles is in the range of 0.020 wt.% to 0.050 wt.%, preferably in the range of 0.025 wt.% to 0.040 wt.%, more preferably in the range of 0.030 wt.% to 0.035 wt.% based on the total weight of the positive electrode active material.

[0144] In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, wherein the ratio of Li B / Li A > 2.0, preferably the ratio of Li B / Li A > 2.5, more preferably the ratio of Li B / Li A > 3.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, wherein the ratio of Li B / Li A < 8.0, preferably the ratio of Li B / Li A < 7.0, more preferably the ratio of Li B / Li A < 6.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, wherein the ratio of Li B / Li A is in the range of 2.0 to 8.0, preferably the ratio of Li B / Li A is in the range of 2.5 to 7.0, more preferably the ratio of Li B / Li A is in the range of 3.0 to 6.0.

[0145] In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, wherein the ratio of Li B / Ti B> 2.0, preferably the ratio Li B / Ti B > 2.5, more preferably the ratio Li B / Ti B > 3.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, wherein the ratio Li B / Ti B < 7.0, preferably the ratio Li B / Ti B < 6.0, more preferably the ratio Li B / Ti B < 5.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises single crystal particles, wherein the ratio Li B / Ti B is in the range of 2.0 to 7.0, preferably the ratio Li B / Ti B is in the range of 2.5 to 6.0, more preferably the ratio Li B / Ti B is in the range of 3.0 to 5.0.

[0146] Certain preferred embodiments relate to the positive electrode active material of the present invention

[0147] - comprising single crystal particles,

[0148] - the carbon content is in the range of 0.020 wt.% to 0.50 wt.% based on the total weight of the positive electrode active material, preferably the carbon content is in the range of 0.025 wt.% to 0.040 wt.%, more preferably the carbon content is in the range of 0.030 wt.% to 0.050 wt.% based on the total weight of the positive electrode active material, and

[0149] - wherein the ratio Li B / Li A is in the range of 2.0 to 8.0, preferably the ratio Li B / Li A is in the range of 2.5 to 7.0, more preferably the ratio Li B / Li A is in the range of 3.0 to 6.0.

[0150] Certain preferred embodiments relate to the positive electrode active material of the present invention

[0151] - comprising single crystal particles,

[0152] - The carbon content is in the range of 0.020 wt.% to 0.50 wt.%, preferably in the range of 0.025 wt.% to 0.040 wt.%, more preferably in the range of 0.030 wt.% to 0.050 wt.% based on the total weight of the positive electrode active material, and

[0153] - wherein the ratio Li B / Ti B is in the range of 2.0 to 7.0, preferably the ratio Li B / Ti B is in the range of 2.5 to 6.0, more preferably the ratio Li B / Ti B is in the range of 3.0 to 5.0.

[0154] Certain preferred embodiments relate to a positive electrode active material

[0155] - comprising single crystal particles,

[0156] - The carbon content is in the range of 0.020 wt.% to 0.50 wt.%, preferably in the range of 0.025 wt.% to 0.040 wt.%, more preferably in the range of 0.030 wt.% to 0.050 wt.% based on the total weight of the positive electrode active material,

[0157] - wherein the ratio Li B / Li A is in the range of 2.0 to 8.0, preferably the ratio Li B / Li A is in the range of 2.5 to 7.0, more preferably the ratio Li B / Li A is in the range of 3.0 to 6.0, and

[0158] - wherein the ratio Li B / Ti B is in the range of 2.0 to 7.0, preferably the ratio Li B / Ti B is in the range of 2.5 to 6.0, more preferably the ratio Li B / Ti B is in the range of 3.0 to 5.0.

[0159] Certain preferred embodiments relate to a positive electrode active material

[0160] - comprising single crystal particles, and

[0161] - wherein the particles have a Co content Co measured by cross-sectional EDS (CS-EDS) at the edge of the particles edge , where Co edge is expressed as mol% at the edge of the particles measured by CS-EDS relative to the sum of the Ni, Mn, and Co contents, wherein the particles have a Co content Co measured by CS-EEDS at the center of the particles center , where Co center is expressed as mol% at the center of the particles measured by CS-ESS relative to the sum of the Ni, Mn, and Co contents, and wherein the ratio Co edge / Co center > 1.10, preferably Co edge / Co center > 1.20, more preferably Co edge / Co center > 1.30, most preferably Co edge / Co center > 1.50.

[0163] In the framework of the present invention, the edge of the particles is the boundary or outer limit that separates the particles from their external environment. The center of the particles is the midpoint of the straight line that is the longest straight line connecting two points on the edge of the particles.

[0164] A particularly preferred embodiment relates to a positive electrode active material

[0165] - comprising single crystal particles, and

[0166] - wherein the particles have an Al content Al defined as where c is the content of Al measured by XPS, and wherein the positive electrode active material has an Al content Al A , where Al B is determined by XPS analysis, where Al B is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, and Al measured by XPS analysis, where the ratio Al B / Al B / Al A > 1.0, preferably the ratio Al B / Al A > 2.0, more preferably the ratio Al B / Al A > 2.5, even more preferably the ratio Al B / Al A > 3.0, even more preferably the ratio Al B / Al A> 3.5, most preferably the ratio of Al B / Al A > 4.0.

[0167] Certain preferred embodiments relate to a positive electrode active material

[0168] - comprising single crystal particles,

[0169] - wherein the particles have a Co content Co measured by cross-sectional EDS (CS-EDS) at the edges of the particles edge , where Co edge is expressed as mol% at the particle edges measured by CS-EDS relative to the sum of the Ni, Mn, and Co contents, and wherein the particles have a Co content Co measured by CS-EEDS at the particle centers center , where Co center is expressed as mol% at the particle centers measured by CS-ESS relative to the sum of the Ni, Mn, and Co contents, and wherein the ratio Co edge / Co center > 1.10, preferably Co edge / Co center > 1.20, more preferably Co edge / Co center > 1.30, most preferably Co edge / Co center > 1.50, and

[0170] - wherein the particles have an Al content Al defined as , where c is the content of Al measured by XPS, and wherein the positive electrode active material has an Al content Al A , where Al B is determined by XPS analysis, where Al B is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, and Al measured by XPS analysis, and wherein the ratio Al B / Al B > 1.0, preferably the ratio of Al A / Al B > 2.0, more preferably the ratio of Al A / Al B > 2.5, even more preferably the ratio of Al A / Al B > 3.0, even more preferably the ratio of Al A > 3.5, most preferably the ratio of Al B / Al A > 3.5, most preferably the ratio of Al B / AlA > 4.0。

[0171] In certain preferred embodiments of the present invention and in the context of the present invention, single crystal particles as defined herein are monolithic particles. As will be understood by those skilled in the art, in these particular preferred embodiments, all embodiments relating to single crystal particles are equally applicable to monolithic particles as defined in the present invention.

[0172] In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, wherein each particle in the single particles consists of only one primary particle, and each secondary particle in the secondary particles consists of at least two primary particles and at most twenty primary particles, as observed in a SEM image. Preferably, at least 30%, more preferably at least 50% of the particles constituting the powder observed in the SEM image are single particles and / or secondary particles. The number of primary particles constituting the single particles and / or secondary particles is determined in a field of view of at least 45 μm × at least 60 μm (i.e., at least 2700 μm 2 ), preferably: at least 100 μm × 100 μm (i.e., at least 10000 μm 2 ).

[0173] The particles in the image should be evenly distributed so as to avoid overlap between the particles. This can be achieved by pouring a small amount of powder sample into an adhesive attached to the SEM sample holder and blowing air to remove the excess powder. In the context of the present invention, the primary particles are distinguished from each other in the SEM image by observing the grain boundaries between the primary particles. The grain boundary is defined as the interface between two primary particles, preferably where the atomic planes of the two primary particles are aligned in different orientations and meet as a crystallographic discontinuity plane.

[0174] In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, and the carbon content of the single particles and / or secondary particles is higher than 0.020 wt.%, preferably higher than 0.025 wt.%, more preferably higher than 0.030 wt.% based on the total weight of the positive electrode active material. In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, and the carbon content of the single particles and / or secondary particles is less than 0.050 wt.%, preferably less than 0.040 wt.%, more preferably less than 0.035 wt.% based on the total weight of the positive electrode active material. In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, and the carbon content of the single particles and / or secondary particles is in the range of 0.020 wt.% to 0.050 wt.%, preferably in the range of 0.025 wt.% to 0.040 wt.%, more preferably in the range of 0.030 wt.% to 0.035 wt.% based on the total weight of the positive electrode active material.

[0175] In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, wherein the ratio Li B / Li A > 2.0, preferably the ratio Li B / Li A > 2.5, more preferably the ratio Li B / Li A > 3.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, wherein the ratio Li B / Li A < 8.0, preferably the ratio Li B / Li A < 7.0, more preferably the ratio Li B / Li A < 6.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, wherein the ratio Li B / Li A is in the range of 2.0 to 8.0, preferably the ratio Li B / Li A is in the range of 2.5 to 7.0, more preferably the ratio Li B / Li A is in the range of 3.0 to 6.0.

[0176] In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, wherein the ratio Li B / Ti B > 2.0, preferably the ratio Li B / Ti B > 2.5, more preferably the ratio Li B / Ti B > 3.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, wherein the ratio Li B / Ti B < 7.0, preferably the ratio Li B / Ti B < 6.0, more preferably the ratio Li B / Ti B < 5.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises single particles and / or secondary particles, wherein the ratio Li B / Ti B is in the range of 2.0 to 7.0, preferably the ratio Li B / Ti B is in the range of 2.5 to 6.0, more preferably the ratio Li B / Ti B is in the range of 3.0 to 5.0.

[0177] Certain preferred embodiments relate to the positive electrode active material of the present invention

[0178] - comprising single particles and / or secondary particles,

[0179] - the carbon content is in the range of 0.020 wt.% to 0.50 wt.% based on the total weight of the positive electrode active material, preferably the carbon content is in the range of 0.025 wt.% to 0.040 wt.%, more preferably the carbon content is in the range of 0.030 wt.% to 0.050 wt.% based on the total weight of the positive electrode active material, and

[0180] - wherein the ratio Li B / Li A is in the range of 2.0 to 8.0, preferably the ratio Li B / Li A is in the range of 2.5 to 7.0, more preferably the ratio Li B / Li A is in the range of 3.0 to 6.0.

[0181] Certain preferred embodiments relate to the positive electrode active material of the present invention

[0182] - Comprising single particles and / or secondary particles,

[0183] - The carbon content is in the range of 0.020 wt.% to 0.50 wt.%, preferably in the range of 0.025 wt.% to 0.040 wt.%, more preferably in the range of 0.030 wt.% to 0.050 wt.%, based on the total weight of the positive electrode active material, and

[0184] - Wherein the ratio Li B / Ti B is in the range of 2.0 to 7.0, preferably the ratio Li B / Ti B is in the range of 2.5 to 6.0, more preferably the ratio Li B / Ti B is in the range of 3.0 to 5.0.

[0185] Certain preferred embodiments relate to positive electrode active materials

[0186] - Comprising single particles and / or secondary particles,

[0187] - The carbon content is in the range of 0.020 wt.% to 0.50 wt.%, preferably in the range of 0.025 wt.% to 0.040 wt.%, more preferably in the range of 0.030 wt.% to 0.050 wt.%, based on the total weight of the positive electrode active material,

[0188] - Wherein the ratio Li B / Li A is in the range of 2.0 to 8.0, preferably the ratio Li B / Li A is in the range of 2.5 to 7.0, more preferably the ratio Li B / Li A is in the range of 3.0 to 6.0, and

[0189] - Wherein the ratio Li B / Ti B is in the range of 2.0 to 7.0, preferably the ratio Li B / Ti B is in the range of 2.5 to 6.0, more preferably the ratio Li B / Ti B is in the range of 3.0 to 5.0.

[0190] Certain preferred embodiments relate to positive electrode active materials

[0191] - contains single particles and / or secondary particles, and

[0192] - where the particles have a Co content Co at the edge of the particles as measured by cross-sectional EDS (CS-EDS) edge , where Co edge Expressed as mol % at the particle edge relative to the sum of the Ni, Mn and Co contents measured by CS-EDS, where the particle has a Co content Co measured by CS-EEDS at the particle center. center , where Co center Expressed as mol% at the particle center measured by CS-ESS relative to the sum of Ni, Mn and Co contents, and where the ratio Co edge / Co center >1.10, preferably Co edge / Co center > 1.20, more preferably Co edge / Co center > 1.30, most preferably Co edge / Co center >1.50.

[0193] In the framework of the present invention, the edge of a particle is the boundary or outer limit that distinguishes the particle from its external environment. The center of a particle is the midpoint of the line that is the longest of the lines connecting two points on the edge of the particle.

[0194] Particularly preferred embodiments relate to the positive electrode active material

[0195] - contains single particles and / or secondary particles, and

[0196] - where the particle has a Al content A , wherein c is the content of Al measured by XPS, and wherein the positive electrode active material has an Al content Al B , where Al B XPS analysis confirmed that Al B Expressed as the mole fraction compared to the sum of the mole fractions of Co, Mn, Ni and Al measured by XPS analysis, where the ratio Al B / Al A > 1.0, preferred ratio Al B / Al A > 2.0, more preferably ratio A1 B / Al A > 2.5, even more preferably ratio A1 B / Al A> 3.0, and even more preferably a ratio of Al B / Al A > 3.5, and most preferably a ratio of Al B / Al A > 4.0.

[0197] Certain preferred embodiments relate to a positive electrode active material

[0198] - comprising single particles and / or secondary particles,

[0199] - wherein the particles have a Co content Co measured by cross-sectional EDS (CS-EDS) at the edge of the particles edge where Co edge is expressed as mol% at the edge of the particles measured by CS-EDS relative to the sum of the Ni, Mn, and Co contents, and wherein the particles have a Co content Co measured by CS-EEDS at the center of the particles center where Co center is expressed as mol% at the center of the particles measured by CS-ESS relative to the sum of the Ni, Mn, and Co contents, and wherein the ratio Co edge / Co center > 1.10, preferably Co edge / Co center > 1.20, more preferably Co edge / Co center > 1.30, most preferably Co edge / Co center > 1.50, and

[0200] - wherein the particles have an Al content Al defined as where c is the content of Al measured by XPS, and wherein the positive electrode active material has an Al content Al A where Al B is determined by XPS analysis, where Al B is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, and Al measured by XPS analysis, and wherein the ratio Al B / Al B / Al A > 1.0, preferably a ratio of Al B / Al A > 2.0, more preferably a ratio of Al B / Al A > 2.5, even more preferably a ratio of Al B / Al A > 3.0, even more preferably a ratio of Al B / Al A > 3.5, most preferably the ratio of Al B / Al A > 4.0.

[0201] In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles. As will be understood by those skilled in the art, polycrystalline particles are coalesced from 5 or more single crystal particles, preferably 10 or more single crystal particles, more preferably 50 or more single crystal particles. This can be observed by observing grain boundaries in appropriate microscopy techniques such as scanning electron microscopy (SEM). Under post-treatment steps (such as heat treatment steps), the coalescence of single crystal particles into polycrystalline particles occurs.

[0202] In certain preferred embodiments, the polycrystalline particles are coalesced from more than 20 primary particles, preferably 50 or more primary particles, more preferably 100 or more primary particles. Thus, in certain preferred embodiments, the positive electrode active material is a powder comprising polycrystalline particles, wherein each polycrystalline particle in the polycrystalline particles is composed of more than 20 primary particles, preferably 50 or more primary particles, more preferably 100 or more primary particles, as observed in the SEM image.

[0203] Preferably, at least 30% of the particles constituting the powder observed in the SEM image, more preferably at least 50% of the particles, are polycrystalline particles. The number of primary particles constituting the polycrystalline particles is determined in a field of view of at least 45 μm × at least 60 μm (i.e., at least 2700 μm 2 ), preferably: at least 100 μm × 100 μm (i.e., at least 10000 μm 2 ). The particles in the image should be evenly distributed to avoid overlap between particles. This can be achieved by pouring a small amount of powder sample into an adhesive attached to the SEM sample holder and blowing air to remove excess powder.

[0204] In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, and the carbon content of the polycrystalline particles is higher than 0.035 wt.%, preferably higher than 0.040 wt.%, more preferably higher than 0.045 wt.% based on the total weight of the positive electrode active material. In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, and the carbon content of the polycrystalline particles is less than 0.075 wt.%, preferably less than 0.070 wt.%, more preferably less than 0.065 wt.% based on the total weight of the positive electrode active material. In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, and the carbon content of the polycrystalline particles is in the range of 0.035 wt.% to 0.075 wt.%, preferably in the range of 0.040 wt.% to 0.070 wt.%, more preferably in the range of 0.045 wt.% to 0.065 wt.% based on the total weight of the positive electrode active material.

[0205] In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, wherein the ratio Li B / Li A > 3.0, preferably the ratio Li B / Li A > 3.5, more preferably the ratio Li B / Li A > 4.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, wherein the ratio Li B / Li A < 10.0, preferably the ratio Li B / Li A < 9.0, more preferably the ratio Li B / Li A < 8.5. In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, wherein the ratio Li B / Li A is in the range of 3.0 to 10.0, preferably the ratio Li B / Li A is in the range of 3.5 to 9.0, more preferably the ratio Li B / Li A is in the range of 4.0 to 8.5.

[0206] In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, wherein the ratio Li B / Ti B> 4.0, preferably a ratio of Li B / Ti B > 5.0, more preferably a ratio of Li B / Ti B > 6.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, wherein the ratio of Li B / Ti B < 12.0, preferably a ratio of Li B / Ti B < 11.0, more preferably a ratio of Li B / Ti B < 10.0. In certain preferred embodiments, the positive electrode active material of the present invention comprises polycrystalline particles, wherein the ratio of Li B / Ti B is in the range of 4.0 to 12.0, preferably a ratio of Li B / Ti B is in the range of 5.0 to 11.0, more preferably a ratio of Li B / Ti B is in the range of 6.0 to 10.0.

[0207] Certain preferred embodiments relate to the positive electrode active material of the present invention

[0208] - comprising polycrystalline particles,

[0209] - the carbon content is in the range of 0.035 wt.% to 0.075 wt.% based on the total weight of the positive electrode active material, preferably the carbon content is in the range of 0.040 wt.% to 0.070 wt.%, more preferably the carbon content is in the range of 0.045 wt.% to 0.065 wt.% based on the total weight of the positive electrode active material, and

[0210] - wherein the ratio of Li B / Li A is in the range of 3.0 to 10.0, preferably a ratio of Li B / Li A is in the range of 3.5 to 9.0, more preferably a ratio of Li B / Li A is in the range of 4.0 to 8.5.

[0211] Certain preferred embodiments relate to the positive electrode active material of the present invention

[0212] - comprising polycrystalline particles,

[0213] - The carbon content is in the range of 0.035 wt.% to 0.075 wt.%, preferably in the range of 0.040 wt.% to 0.070 wt.%, more preferably in the range of 0.045 wt.% to 0.065 wt.%, based on the total weight of the positive electrode active material, and

[0214] - The ratio Li B / Ti B is in the range of 4.0 to 12.0, preferably the ratio Li B / Ti B is in the range of 5.0 to 11.0, more preferably the ratio Li B / Ti B is in the range of 6.0 to 10.0.

[0215] Certain preferred embodiments relate to the positive electrode active material of the present invention

[0216] - comprising polycrystalline particles,

[0217] - The carbon content is in the range of 0.035 wt.% to 0.075 wt.%, preferably in the range of 0.040 wt.% to 0.070 wt.%, more preferably in the range of 0.045 wt.% to 0.065 wt.%, based on the total weight of the positive electrode active material,

[0218] - wherein the ratio Li B / Li A is in the range of 3.0 to 10.0, preferably the ratio Li B / Li A is in the range of 3.5 to 9.0, more preferably the ratio Li B / Li A is in the range of 4.0 to 8.5, and

[0219] - The ratio Li B / Ti B is in the range of 4.0 to 12.0, preferably the ratio Li B / Ti B is in the range of 5.0 to 11.0, more preferably the ratio Li B / Ti B is in the range of 6.0 to 10.0.

[0220] Certain preferred embodiments relate to the positive electrode active material of the present invention, which comprises single crystal particles, and the median D50 value of the primary particles of the single crystal particles is less than 10 μm, preferably less than 8 μm, more preferably less than 5 μm. Certain preferred embodiments relate to the positive electrode active material of the present invention, which comprises single crystal particles, and the median D50 value of the primary particles of the single crystal particles is greater than 1 μm, preferably greater than 2 μm, more preferably greater than 3 μm. Some embodiments relate to the positive electrode active material of the present invention, which comprises single crystal particles, and the median D50 value of the primary particles of the single crystal particles is between 1 μm and 10 μm, preferably between 2 μm and 8 μm, more preferably between 3 μm and 5 μm. As understood by those skilled in the art, the particle size distribution (PSD) D50 of the positive electrode active material powder is measured by laser diffraction particle size analysis. For example, but not limited to the present invention, the particle median D50 can be measured using a Malvern Mastersizer 3000.

[0221] Certain preferred embodiments relate to the positive electrode active material of the present invention, which comprises single particles and / or secondary particles, and the median D50 value of the single particles and / or secondary particles is less than 10 μm, preferably less than 8 μm, more preferably less than 5 μm. Certain preferred embodiments relate to the positive electrode active material of the present invention, which comprises single particles and / or secondary particles, and the median D50 value of the single particles and / or secondary particles is greater than 1 μm, preferably greater than 2 μm, more preferably greater than 3 μm. Some embodiments relate to the positive electrode active material of the present invention, which comprises single particles and / or secondary particles, and the median D50 value of the single particles and / or secondary particles is between 1 μm and 10 μm, preferably between 2 μm and 8 μm, more preferably between 3 μm and 5 μm. As understood by those skilled in the art, the particle size distribution (PSD) D50 of the positive electrode active material powder is measured by laser diffraction particle size analysis. For example, but not limited to the present invention, the particle median D50 can be measured using a Malvern Mastersizer 3000. Preferably, the particle median D50 is the volume median particle size.

[0222] Certain preferred embodiments relate to the positive electrode active material of the present invention, which comprises polycrystalline particles, and the median D50 value of the secondary particles of the polycrystalline particles is less than 10 μm, preferably less than 8 μm, more preferably less than 5 μm. Certain preferred embodiments relate to the positive electrode active material of the present invention, which comprises polycrystalline particles, and the median D50 value of the secondary particles of the polycrystalline particles is greater than 1 μm, preferably greater than 2 μm, more preferably greater than 3 μm. Certain embodiments relate to the positive electrode active material of the present invention, which comprises polycrystalline particles, and the median D50 value of the secondary particles of the polycrystalline particles is between 1 μm and 10 μm, preferably between 2 μm and 8 μm, more preferably between 3 μm and 5 μm. As understood by those skilled in the art, the particle size distribution (PSD) D50 of the positive electrode active material powder is measured by laser diffraction particle size analysis. For example, but not limited to the present invention, the particle median D50 can be measured using a Malvern Mastersizer 3000. Preferably, the particle median D50 is the volume median particle size.

[0223] Method

[0224] In a second aspect, the present invention provides a method for manufacturing a positive electrode active material, wherein the method comprises:

[0225] - preparing a slurry of a lithium transition metal-based oxide compound, a first lithium source, water and an alcohol,

[0226] - mixing the slurry with a Ti source, and

[0227] - heating the mixture at a temperature between 250 °C and less than 500 °C for a time between 1 hour and 20 hours to obtain a positive electrode active material.

[0228] In a highly preferred embodiment of the method for manufacturing the positive electrode active material of the present invention, the positive electrode active material is according to the first aspect of the present invention. As understood by those skilled in the art, if the method for manufacturing the positive electrode active material of the present invention provides a positive electrode material according to the first aspect of the present invention, then all embodiments of the positive electrode active material according to the first aspect of the present invention are applicable, mutatis mutandis, to the method for manufacturing the positive electrode active material according to the first aspect of the present invention. For example, as explained herein in the context of the positive electrode active material, the various embodiments relating to the properties and amounts of Li, M’, Ti A 、Ti B 、Li A and Li B are equally applicable to the method for preparing the positive electrode active material.

[0229] In a preferred embodiment of the method, the lithium transition metal-based oxide compound comprises Li, M', and oxygen, where M' includes Ni, Mn, Co, and D, and D is at least one element among the following elements: Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr; preferably Al, B, Cr, Nb, S, Si, Y, Zr, and W; more preferably B, Nb, Zr, and W. Preferably, the lithium transition metal-based oxide used is also typically prepared according to a lithiation method, i.e., a method in which a mixture of a transition metal oxide precursor and a second lithium source is heated at a temperature preferably of at least 500 °C and at most 1000 °C. Generally, the transition metal precursor is prepared by coprecipitation of one or more transition metal sources, such as salts, preferably sulfates or nitrates, more preferably sulfates; in the presence of an alkali metal compound, such as an alkali metal hydroxide, e.g., sodium hydroxide, and / or ammonia, it is prepared by coprecipitation of the elements Ni, Mn, and / or Co. Preferably, the second lithium source is metallic lithium or a lithium salt, preferably a lithium salt such as LiOH. Optionally, the lithium transition metal-based oxide compound includes single crystal particles or single particles and / or secondary particles as explained herein, and is further mixed with a Co source (such as Co 3 O 4 ) and a third lithium source, preferably the third lithium source is metallic lithium or a lithium salt, preferably a lithium salt (such as LiOH), where the Co content of the Co source is in the range of 1.0 mol% to 2.0 mol% relative to the total of Ni, Mn, and Co, and the Li content of the Li source is in the range of 5.0 mol% to 10 mol% relative to the total amount of Ni, Mn, and Co. Optionally, the lithium transition metal-based oxide compound is further pulverized and sieved with alumina, and the amount of the alumina is 250 ppm to 750 ppm relative to the total amount of the positive electrode active material.

[0230] In a preferred embodiment of the method, the first Li source is metallic lithium or a lithium salt, preferably a lithium salt such as LiOH.

[0231] In a preferred embodiment, the solid content of the slurry is greater than 40 wt.% (based on the total weight of the slurry), preferably the solid content is greater than 50 wt.%, more preferably the solid content is greater than 55 wt.% (based on the total weight of the slurry). In a preferred embodiment, the solid content of the slurry is less than 80 wt.% (based on the total weight of the slurry), preferably the solid content is less than 70 wt.%, more preferably the solid content is less than 65 wt.% (based on the total weight of the slurry). In a preferred embodiment, the solid content of the slurry is in the range of 40 wt.% to 80 wt.% (based on the total weight of the slurry), preferably the solid content is in the range of 50 wt.% to 70 wt.%, more preferably the solid content is in the range of 55 wt.% to 65 wt.% (based on the total mass of the slurry).

[0232] In a preferred embodiment of the method, the alcohol is methanol, ethanol, propanol, butanol or a combination thereof, preferably ethanol.

[0233] In a preferred embodiment of the method, the molar ratio of Li present in the first Li source to Ti present in the Ti source is in the range of 5:1 to 1:3, preferably in the range of 4:1 to 1:2, more preferably in the range of 3:1 to 1:1, such as about 2:1.

[0234] In a preferred embodiment of the method, the molar ratio of water to Ti present in the Ti source is in the range of 5:1 to 1:3, preferably in the range of 4:1 to 1:2, more preferably in the range of 3:1 to 1:1, such as about 2:1.

[0235] In a preferred embodiment of the method, the molar ratio of water to Li present in the first Li source is in the range of 4:1 to 1:4, preferably in the range of 3:1 to 1:3, more preferably in the range of 2:1 to 1:2, such as about 1:1.

[0236] In a preferred embodiment, the amount of water in the slurry is between 0.5 mol% and 25.0 mol%, preferably between 0.7 mol% and 10.0 mol%, more preferably between 1 mol% and 5 mol% relative to the metal content in the lithium transition metal oxide compound.

[0237] In a preferred embodiment, the amount of Li present in the first lithium source in the slurry is between 0.5 mol% and 25.0 mol%, preferably between 0.7 mol% and 10.0 mol%, more preferably between 1.0 mol% and 5.0 mol% relative to the metal content in the lithium transition metal oxide compound.

[0238] In a preferred embodiment, relative to the metal content in the lithium transition metal oxide compound, the amount of Ti present in the titanium source in the slurry is between 0.1 mol% and 10.0 mol%, preferably between 0.25 mol% and 5.0 mol%, more preferably between 0.5 mol% and 1.5 mol% relative to the metal content in the lithium transition metal oxide compound. In a preferred embodiment, the Ti source is a Ti-alcoholate, preferably Ti-ethoxide, Ti-propoxide or Ti-butoxide, more preferably Ti-propoxide or Ti-isopropoxide, such as Ti(IV)-propoxide or Ti(IV)-isopropoxide. In a preferred embodiment, the Ti-alcoholate is mixed with the mixture as a solid. Alternatively, the Ti-alcoholate is mixed with the slurry as a solution, where the solution contains the Ti-alcoholate and an additional alcohol, and the alkoxide group is the conjugate base of the additional alcohol. For example, the Ti-alcoholate is Ti(IV)-propoxide dissolved in propanol. Generally, the solution contains 50 wt.% to 90 wt.% of the Ti-alcoholate based on the total weight of the solution. Examples of such solutions are a 70 wt.% solution of Ti(IV)-isopropoxide in 1-propanol or an 80 wt.% solution of Ti(IV)-butoxide in 1-butanol.

[0239] In a preferred embodiment of the method, the mixture is heated

[0240] - at a temperature between 275 °C and 450 °C, preferably between 300 °C and 400 °C, most preferably between 325 °C and 375 °C; and

[0241] - for a time between 2 hours and 15 hours, preferably between 3 hours and 10 hours, more preferably between 4 hours and 7 hours.

[0242] In a preferred embodiment of the method, the heating of the mixture is carried out in an oxidizing atmosphere. Preferably, the oxidizing atmosphere contains oxygen, such as air, or consists of oxygen.

[0243] In a more preferred embodiment, the heating takes place in a furnace.

[0244] In a particularly preferred embodiment, the method includes an additional step of filtering and drying the mixture before heating it. Preferably, the drying is carried out under vacuum, vacuum heating or under a constant flow of N 2 gas for at least 4 hours and at most 20 hours. As will be understood by those skilled in the art, the filtration of the mixture is achieved by conventional filtration techniques known in the art.

[0245] In a particularly preferred embodiment, the method includes an additional step of drying the mixture before heating it. Preferably, the drying is carried out under vacuum, vacuum heating or under a constant flow of N 2The constant flow of the gas is carried out for at least 4 hours and at most 20 hours.

[0246] The method defines the product

[0247] In a third aspect, the present invention relates to a positive electrode active material obtainable by the method according to the second aspect of the present invention.

[0248] As will be understood by those skilled in the art, all embodiments relating to the positive electrode active material according to the first aspect of the present invention and / or the method according to the second aspect of the present invention are, mutatis mutandis, applicable to the positive electrode active material obtainable by the method according to the present invention. For example, as explained herein in the context of the positive electrode active material, the various embodiments relating to the properties and amounts of Li, M', Ti A , Ti B , Li A and Li B are equally applicable to the positive electrode active material obtainable by the method for preparing the positive electrode active material.

[0249] Battery

[0250] In a fourth aspect, the present invention relates to a battery comprising the positive electrode active material according to the first aspect of the present invention and / or the positive electrode active material obtainable by the method according to the third aspect of the present invention.

[0251] 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 contains Li, P, and S. Typically, the following sulfur-containing compounds can be suitably used: Li 6 PS 5 Cl (LPSCL), thio-LISICON (Li 3.25 Ge 0.25 P 0.75 S 4 ), Li 2 S-P 2 S 5 -LiCl, Li 2 S-SiS 2 , LiI-Li 2 S-SiS 2 , Li 2 S-P 2 S 5 , Li 2 S-SiS 2 , LiI-Li 2 S-SiS 2 , LiI-Li 2 S-P2 S 5 、LiI-Li 2 SP 2 O 5 、LiI-Li 3 PO 4 -P 2 S 5 , Li 2 SP 2 S 5 , Li 3 PS 4 , Li 7 P 3 S 11 、LiI-Li 2 SB 2 S 3 , Li 3 PO 4 -Li 2 S-SiS 2 , Li 3 PO 4 -Li 2 S-SiS 2 , Li 3 PO 4 -Li 2 S-SiS 2 , Li 10 G 2 S 12 , Li 9.54 Si 1.74 P 1.44 S 11.7 Cl 0.3 and / or Li 7 P 3 S 11 In a highly preferred embodiment, the battery is a sulfide solid state battery.

[0252] Preferably, the solid-state battery further comprises an anode comprising an anode active material. Suitable electrochemically active anode materials are those known in the art. For example, the anode may comprise graphite carbon, metallic lithium or a metal alloy comprising lithium (e.g., a Li-In alloy) as the anode active material.

[0253] In a preferred embodiment, the cell according to the invention has an efficiency of at least 88%, preferably at least 90%, more preferably at least 92%, most preferably at least 94%. As understood by a person skilled in the art, the efficiency of the cell is determined as explained under point E2) of the examples.

[0254] In a preferred embodiment, the battery according to the present invention has a first discharge capacity of at least 200 mAh / g, more preferably at least 205 mAh / g, and even more preferably at least 210 mAh / g. As 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 0.1C within the following voltage ranges: 4.3V to 2.5V (Li / Li + ), or 3.7V to 1.9V (InLi / Li + ).

[0255] Use

[0256] In a fifth aspect, the present invention relates to the use of the positive electrode active material according to the first aspect of the present invention and / or the positive electrode active material obtainable by the method according to the third aspect of the present invention in a battery.

[0257] A preferred embodiment is the use of the positive electrode active material in a battery, preferably a solid-state battery, more preferably a sulfide solid-state battery, for improving the efficiency of the battery and / or increasing the first discharge capacity of the battery.

[0258] In a sixth aspect, the present invention relates to the use of the battery according to the present invention in any one of a portable computer, a tablet computer, a mobile phone, an energy storage system, an electric vehicle, or in a hybrid electric vehicle, preferably in an electric vehicle or a hybrid electric vehicle.

[0259] Examples

[0260] Experimental tests used in the examples

[0261] The following analytical methods were used in the examples:

[0262] A) ICP analysis

[0263] The amounts of Li, Ni, Mn, Co, and Ti in the positive electrode active material powder were measured by using an inductively coupled plasma (ICP-OES) method with an Agilent ICP 720-ES. 2 grams of the powder sample was dissolved in 10 mL of high-purity hydrochloric acid (at least 37 wt% HCl relative to the total weight of the solution) in a conical flask. The flask was covered with a glass slide and heated on a hot plate at 380 °C until the powder was completely dissolved. After cooling to room temperature, the solution in the conical flask was poured into a 250 mL volumetric flask. Then, the volumetric flask was filled with deionized water up to the 250 mL mark and then thoroughly homogenized. An appropriate amount of the solution was taken out by a pipette and transferred to a 250 mL volumetric flask for a second dilution. At this time, the internal standard and 10% hydrochloric acid were filled into this volumetric flask up to the 250 mL mark and then homogenized. Finally, this 50 mL solution was used for ICP-OES measurement.

[0264] B) Particle size

[0265] After dispersing each powder sample in the 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. To improve the dispersibility of the powder, sufficient ultrasonic radiation and stirring were applied, and a suitable surfactant was introduced. D50 is defined as the particle size at 50% of the cumulative volume % distribution obtained from the measurement with a Malvern Mastersizer 3000 with Hydro MV.

[0266] C) X-ray photoelectron spectroscopy analysis

[0267] In the present invention, X-ray photoelectron spectroscopy (XPS) was used to analyze the surface of the positive electrode active material powder particles. In XPS measurement, signals were collected from the first few nanometers (e.g., 1 nm to 10 nm) of the uppermost part (i.e., the surface layer) of the sample. Therefore, all elements measured by XPS are included in the surface layer.

[0268] For the surface analysis of the positive electrode active material powder particles, XPS measurement was performed using a Thermo K-α+ spectrometer (Thermo Scientific). Monochromatic Al Kα radiation (hυ = 1486.6 eV) was used with a spot size of 400 μm and a measurement angle of 45°. Wide scan measurements were performed at a pass energy of 200 eV to identify the elements present on the surface. The C1s peak with the maximum intensity (or centered) at a binding energy of 284.8 eV was used as the calibration peak position after data collection. Then, at least 10 precise narrow scans were performed for each identified element at 50 eV to determine the precise surface composition.

[0269] Curve fitting was performed using CasaXPS version 2.3.19PR1.0 (Casa Software) with Shirley-type background processing and Scofield sensitivity factors. The fitting parameters were based on Table 1a. The line shape GL(30) is a Gaussian / Lorentzian product formula with 70% Gaussian line and 30% Lorentzian line.

[0270] Table 1a. XPS fitting parameters of Ni2p3, Mn2p3, Co2p3 and Ti2p 。

[0271]

[0272] For the Ti and Co peaks, constraints were set for each defined peak according to Table 1b.

[0273] Table 1b. XPS fitting constraints for peak fitting 。

[0274]

[0275] The surface contents of Ti and Li determined by XPS are respectively expressed as the mole fractions of Ti and Li in the surface layer of the particles divided by the total content of Ni, Mn, Co, and Ti in the surface layer. The calculation is as follows:

[0276]

[0277] 。

[0278] D) Carbon analyzer

[0279] The carbon content of the positive electrode active material powder is measured by a Horiba Emia-Expert carbon / sulfur analyzer. 1 g of the positive electrode active material powder is placed in a ceramic crucible in a high-frequency induction furnace. 1.5 g of tungsten and 0.3 g of tin are added to the crucible as accelerators. The powder is heated at a programmable temperature, and then the gas generated during combustion is analyzed by an infrared detector. The analysis of CO 2 and CO determines the carbon concentration.

[0280] E) Sulfide solid-state battery test

[0281] E1) Preparation of sulfide solid-state battery

[0282] Positive electrode preparation :

[0283] To prepare the positive electrode, a slurry containing positive electrode active material powder, a Li-P-S-based solid electrolyte, carbon (Super-P, Timcal), and a binder (RC-10, Arkema) is mixed in a butyl acetate solvent in a formulation of 64.0:30.0:3.0:3.0 weight ratio in an Ar-filled glove box. The slurry is cast on one side of an aluminum foil, and then the slurry-coated foil is dried in a vacuum oven to obtain the positive electrode. The obtained positive electrode is punched into a diameter of 10 nm, with an active material loading of about 4 mg / cm 2 。

[0284] Negative electrode preparation :

[0285] To prepare the negative electrode, a Li foil (diameter 3 mm, thickness 100 μm) is placed at the center on top of an In foil (diameter 10 mm, thickness 100 μm) and pressed to form a Li-In alloy negative electrode.

[0286] Separator

[0287] To prepare a separator that also has a solid electrolyte function in a battery, a Li-P-S-Cl-based solid electrolyte was granulated at a pressure of 250 MPa to obtain a pellet thickness of 1 mm.

[0288] Cell assembly

[0289] A sulfide solid-state battery was assembled in an argon-filled glove box in a bottom-to-top order: a positive electrode including an Al current collector with a coated portion on the top - a separator - a negative electrode with a Cu current collector on the Li side on the top. The stacked components were pressed together at a pressure of 250 MPa and placed in an outer cage to prevent air exposure.

[0290] E2) Test method

[0291] The test method was the conventional "constant cut-off voltage" test. The conventional battery tests in the present invention followed 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).

[0292] A 1C current was defined using 160 mA / g. The initial charge capacity (CQ1) and discharge capacity (DQ1) were measured at a C-rate of 0.1C in the constant current mode (CC) within the following voltage ranges: 4.3 V to 2.5 V (Li / Li + ) or 3.7 V to 1.9 V (InLi / Li + ).

[0293] The efficiency EF was expressed as follows in %:

[0294]

[0295] Table 2. Cycling plan for the sulfide solid-state battery test method

[0296]

[0297] The present invention is further illustrated in the following examples:

[0298] Comparative Example 1

[0299] A single-piece positive electrode active material labeled CEX1.1 (i.e., a positive electrode active material composed of single particles and secondary particles) was prepared according to the following steps:

[0300] Step 1) Preparation of a transition metal hydroxide precursor: In a large continuous stirred tank reactor (CSTR) with a mixture of nickel manganese cobalt sulfate, sodium hydroxide, and ammonia, a metal composition of Ni 0.85 Mn 0.07 Co0.08 Nickel-based transition metal hydroxide powder of nickel-based transition metal hydroxide (TMH1).

[0301] Step 2) First mixing: Mix the TMH1 prepared in step 1) with LiOH in an industrial blender to obtain a first mixture with a lithium to metal M' (Li / M') ratio of 0.96.

[0302] Step 3) First heating: Heat the first mixture obtained from step 2) at 885 °C for 11 hours in an oxidizing atmosphere to obtain a first heated product.

[0303] Step 4) Wet bead milling: Subject the first heated product obtained from step 3) to bead milling in a solution containing 0.5 mol% Co relative to the total molar content of Ni, Mn, and Co in the first heated product, followed by a drying and sieving process to obtain a milled product. The bead mill solid to solution weight ratio is 6:4 and it is carried out for 40 minutes.

[0304] Step 5) Drying: Dry the milled product obtained from step 4) at 150 °C for 12 hours.

[0305] Step 6) Second mixing: Relative to the total molar content of Ni, Mn, and Co in the milled product respectively, mix the milled product obtained from step 5) with 1.5 mol% Co obtained from CO 3 O 4 and 7.5 mol% Li obtained from LiOH in an industrial blender to obtain a second mixture.

[0306] Step 7) Second heating: Heat the second mixture obtained from step 6) at 760 °C for 10 hours in an oxidizing atmosphere, and then crush and sieve it with 500 ppm of alumina powder to obtain CEX1.1.

[0307] Prepare CEX1.2 by mixing CEX1.1 with 0.45 mol% Ti obtained from TiO 2 and 0.90 mol% Li obtained from LiOH, and then heating it at 350 °C in an oxidizing atmosphere for 6 hours.

[0308] Example 1

[0309] Prepare a single-piece positive electrode active material labeled EX1.1 (i.e., a positive electrode active material composed of single particles and secondary particles) according to the following steps:

[0310] Step 1) Ti solution preparation: Dissolve 0.97 mol% Ti obtained from Ti-isopropanol in 4 g of ethanol.

[0311] Step 2) Slurry preparation: 60 g of CEX1.1 is mixed with 1.94 mol% LiOH and 1.94 mol% water (both relative to Ti) and 40 g of ethanol to form a slurry.

[0312] Step 3) Mixing: The Ti solution prepared in step 1) and the slurry prepared in step 2) are mixed and stirred at room temperature for 15 hours, then filtered and vacuum dried at 80 °C for 6 hours.

[0313] Step 4) Heating: The dried powder obtained from step 3) is heated at 350 °C in an oxygen atmosphere for 5 hours to obtain EX1.1 with M', where M' includes Ni, Mn, Co, and Ti in a ratio of Ni:Mn:Co:Ti of 0.84:0.07:0.09:0.010, as obtained by ICP - OES. EX1.1 has a D50 of 4 µm.

[0314] EX1.2 is prepared according to the same method as EX1.1, except that 0.58 mol% of Ti obtained from Zr - propoxide is used in step 1), and 1.16 mol% of Li obtained from LiOH and 1.97 mol% of H 2 O.

[0315] EX1.3 is prepared according to the same method as EX1.1, except that 0.38 mol% of Ti obtained from Zr - propoxide is used in step 1), and 0.76 mol% of Li obtained from LiOH and 1.90 mol% of H 2 O.

[0316] Comparative Example 2

[0317] The polycrystalline positive electrode active material labeled as CEX2 is prepared according to the following steps:

[0318] Step 1) Preparation of transition metal - oxidized hydroxide precursor: In a large continuous stirred - tank reactor (CSTR) with a mixture of nickel - manganese - cobalt sulfate, sodium hydroxide, and ammonia, a nickel - based transition metal - oxidized hydroxide powder (TMH2) with a metal composition of Ni 0.83 Mn 0.12 Co 0.05 is prepared by a coprecipitation process.

[0319] Step 2) First mixing: The TMH2 prepared in step 1) is mixed with LiOH in an industrial blender to obtain a first mixture with a lithium - to - metal M' (Li / M') ratio of 0.97.

[0320] Step 3) First heating: In an oxidizing atmosphere, the first mixture obtained from step 2) is heated at 750 °C for 11 hours to obtain a first heated product.

[0321] Step 4) Second mixing: Mix the first heated product with LiOH in an industrial blender to obtain a first mixture with a lithium to metal M' (Li / M') ratio of 1.02.

[0322] Step 5) Second heating: Heat the second mixture obtained from Step 4) in an oxidizing atmosphere at 770 °C for 12 hours, followed by crushing and sieving to obtain CEX2.

[0323] Example 2

[0324] The polycrystalline positive electrode active material labeled EX2.1 is prepared according to the following steps:

[0325] Step 1) Ti solution preparation: Dissolve 0.63 mol% of Ti obtained from Ti-isopropanol in 4 g of ethanol.

[0326] Step 2) Slurry preparation: Mix 60 g of CEX1.1 with 1.26 mol% LiOH and 1.26 mol% water (both relative to M') and 40 g of ethanol to form a slurry.

[0327] Step 3) Mixing: Mix the Ti solution prepared in Step 1) and the slurry prepared in Step 2) and stir at room temperature for 15 hours, followed by filtration and vacuum drying at 80 °C for 6 hours.

[0328] Step 4) Heating: Heat the dried powder obtained from Step 3) in an oxygen atmosphere at 350 °C for 5 hours to obtain EX2.1 with M' including Ni, Mn, Co, and Ti in a ratio of 0.83:0.12:0.05:0.006 of Ni:Mn:Co:Ti, as obtained by ICP-OES. EX2.1 has a D50 of 5.5 µm.

[0329] EX2.2 is prepared according to the same method as EX2.1, except that 0.38 mol% of Ti obtained from Zr-propoxide is used in Step 1), and 0.76 mol% of Li obtained from LiOH and 0.76 mol% of H 2 O.

[0330] EX2.3 is prepared according to the same method as EX2.2, except that in Step 3), the mixture is dried using a vacuum pump.

[0331] Results

[0332] Table 3. Overview of the compositions, surface areas and corresponding electrochemical properties of the examples and comparative examples .

[0333]

[0334] Table 3 summarizes the compositions of the examples and comparative examples and their corresponding electrochemical properties. The XPS analysis results for Ti B and Li B show the atomic ratios (equivalent to molar ratios) of Li and Ti relative to the total atomic fraction of Ni, Mn, Co, and Ti. The table also compares the results with those of ICP. An atomic ratio higher than 1 indicates that Li and Ti are enriched in the surface of the positive electrode active material as associated with the XPS measurement, and the signal of this XPS measurement is obtained from the first few nanometers (e.g., 1 nm to 10 nm) of the topmost part (i.e., the surface layer) of the sample. On the other hand, the atomic ratios of Li and Ti obtained from ICP measurement are obtained from the whole particles. Therefore, an XPS-to-ICP ratio higher than 1 indicates that the elements Li and Ti are mostly present on the surface of the positive electrode active material.

[0335] CEX1.1, CEX1.2, and EX1.1 to EX1.3 are single-crystal positive electrode active materials with an Ni content of 84 mol%. CEX1.1 is the core material, and CEX1.2 is the material obtained by heating after dry mixing CEX1.1 with a Ti material. The difference in the process of introducing Ti by preparing a Ti solution results in a higher Ti B and Ti B / Ti A ratio in EX1.1 to EX1.3 compared to CEX1.2. It is further observed that a higher Ti content on the surface is associated with an improvement in the solid-state battery efficiency.

[0336] CEX2 and EX2.1 to EX2.3 are polycrystalline positive electrode active materials with an Ni content of approximately 83 mol%. Compared to CEX2, EX2.1 and EX2.2 prepared according to the method of the present invention show a higher Ti content, Ti B and Ti B / Ti A ratio, and thus are associated with a higher electrochemical cell efficiency. EX2.3 is prepared according to the same method as EX2.2, except that evaporation is used instead of filtration. EX2.2 and EX2.3 with the same Ti content both show similar electrochemical cell efficiencies.

[0337] The present invention shows a comparison between CEX1 and EX1, and between CEX2 and EX2. All these examples show enhanced electrochemical cell efficiency associated with a higher Ti B ratio for each comparative example.

Claims

1. A positive electrode active material for a solid-state battery, wherein the positive electrode active material contains Li, M', and oxygen, where M' comprises: - Ni in an amount x, where 55.0 mol% ≤ x ≤ 98.0 mol%, - Mn in an amount y, where 0.0 mol% ≤ y ≤ 45.0 mol%, - Co in an amount z, where 0.0 mol% ≤ z ≤ 45.0 mol%, - D in an amount a, where 0.0 mol% ≤ a ≤ 5.0 mol%, where D is at least one other element other than Li, Ni, Mn, Co, Ti, and O, - Ti in an amount b, where 0.01 mol% ≤ b ≤ 5.0 mol%, - where x, y, z, a, and b are measured by ICP-OES, - where x + y + z + a + b is 100.0 mol%, wherein the positive electrode active material has a Ti content Ti defined as follows A : , wherein the positive electrode active material has a Ti content of Ti B , where Ti B is determined by XPS analysis, where Ti B is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, and Ti measured by XPS analysis where the ratio Ti B / Ti A > 25.0, wherein the positive electrode active material has a Li content of Li A , where Li A is determined by ICP analysis, where Li A is expressed as a mole fraction compared to the sum of the mole fractions of Co, Mn, Ni, and Ti measured by ICP analysis wherein the positive electrode active material has an Li content Li B , where Li B is determined by XPS analysis, where Li B is expressed as a molar fraction compared to the sum of the molar fractions of Co, Mn, Ni, and Ti measured by XPS analysis, and where the ratio Li B / Li A > 1.0 2. The positive electrode active material according to claim 1, wherein D is at least one element selected from the group consisting of: Al, B, Ba, Ca, Cr, Fe, Mg, Mo, Nb, S, Si, Sr, V, W, Y, Zn, and Zr; preferably Al, B, Cr, Nb, S, Si, Y, Zr, and W; more preferably B, Nb, Zr, and W.

3. The positive electrode active material according to claim 2, wherein the ratio Li B / Li A > 2.0, preferably the ratio Li B / Li A > 3.0, more preferably the ratio Li B / Li A > 4.

0.

4. The positive electrode active material according to any one of claims 1 to 3, wherein the ratio Li B / Ti B > 2.0, preferably the ratio Li B / Ti B > 3.0, more preferably the ratio Li B / Ti B > 4.

0.

5. The positive electrode active material according to any one of the preceding claims, wherein the ratio Li B / Ti B < 60.0, preferably the ratio Li B / Ti B < 30.0, more preferably the ratio Li B / Ti B < 10.

0.

6. The positive electrode active material according to any one of the preceding claims, wherein the ratio Ti B / Ti A > 50.0, preferably the ratio Ti B / Ti A > 75.0, more preferably the ratio Ti B / Ti A > 100.

0.

7. The positive electrode active material according to any one of the preceding claims, wherein 60.0 mol% ≤ x ≤ 95.0 mol%, preferably 65.0 mol% ≤ x ≤ 92.0 mol%, more preferably 70.0 mol% ≤ x ≤ 90.0 mol%.

8. The positive electrode active material according to any one of the preceding claims, wherein 0.05 mol% ≤ b ≤ 2.5 mol%, preferably 0.1 mol% ≤ b ≤ 2.0 mol%, more preferably 0.2 mol% ≤ b ≤ 1.5 mol%.

9. A method for manufacturing a positive electrode active material, preferably the positive electrode active material according to any one of claims 1 to 8, wherein the method comprises: - preparing a slurry of a lithium transition metal-based oxide compound, a first lithium source, water, and an alcohol, - mixing the slurry with a Ti source, and - heating the mixture at a temperature between 250°C and less than 500°C for a time between 1 hour and 20 hours to obtain the positive electrode active material.

10. The method according to claim 9, wherein the method further comprises the additional steps of filtering and drying the mixture before heating the mixture.

11. The method according to claim 9, wherein the method further comprises the additional step of drying the mixture before heating the mixture.

12. The method according to any one of claims 9 to 11, wherein the Ti source is Ti-propoxide or Ti-isopropoxide.

13. The method according to any one of claims 9 to 12, wherein the amount of water in the slurry is between 0.5 mol% and 25.0 mol%, preferably between 0.7 mol% and 10.0 mol%, more preferably between 1.0 mol% and 5.0 mol%, relative to the metal content in the lithium transition metal oxide compound.

14. The method according to any one of claims 9 to 13, wherein the pH of the slurry is > 7.

15. A solid-state battery, the solid-state battery comprising a positive electrode active material according to claims 1 to 8.

16. The solid-state battery according to claim 15, wherein the solid-state battery comprises a sulfide-based solid electrolyte containing Li, P, and S.

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

Images